TY - CHAP TI - Cytotoxicity of oxyradicals and the evolution of superoxide dismutases AU - Hassan, H.M. T2 - Oxygen, gene expression and cellular function A2 - Massaro, D. A2 - Clerch, L. T3 - Lung Biology series PY - 1997/// SP - 26–51 PB - Marcel Dekker SV - 15 ER - TY - PAT TI - Occupancy sensor and method of operating same AU - Myron, D. D. AU - Williams, E. R. AU - Hardin, C. C. AU - Woytek, T. W. AU - Stephens, M. A. C2 - 1997/// DA - 1997/// PY - 1997/// ER - TY - CONF TI - Ribosomal binding of modified tRNA anticodons related to thermal stability AU - Ashraf, S. S. AU - Guenther, R. AU - Ye, W. AU - Lee, Y. AU - Malkiewicz, A. AU - Agris, P. F. C2 - 1997/// C3 - Symposium on RNA Biology II. RNA: Tool and Target (1997: North Carolina Biotechnology Center) Research Triangle Park, North Carolina, USA, October 17-19, 1997 (Nucleic acids symposium series; no. 36) CN - QP623 .S96 1997 DA - 1997/// VL - 36 SP - 58-60 PB - Oxford: Oxford University Press ER - TY - JOUR TI - Exact determination of UV-induced crosslinks in 16S ribosomal RNA in 30s ribosomal subunits: Erratum AU - Wilms, C. AU - Noah, J. W. AU - Zhong, D. AU - Wollenzien, P. T2 - RNA DA - 1997/// PY - 1997/// VL - 3 IS - 8 SP - 945 ER - TY - JOUR TI - Allosteric interactions between DNA strands and monovalent cations in DNA quadruplex assembly: Thermodynamic evidence for three linked association pathways AU - Hardin, CC AU - Corregan, MJ AU - Lieberman, DV AU - Brown, BA T2 - BIOCHEMISTRY AB - The series of cooperative transitions that lead to [d(TG4)4.(K+)m] quadruplex assembly upon rapid addition of KCl to d(TG4) strands were studied. Quadruplex samples were dialyzed against KCl then Li-EDTA and found to retain between three and five strongly bound potassiums with affinities >10(6) M-2. Absorbance thermal denaturation (melt) and circular dichroism (CD) equilibrium binding data were obtained. The latter were analyzed using two classes of binding models to simulate the effects of the assumed intermolecular interactions on the binding curves (isotherms). The melt experiments yielded equilibrium dissociation constants (Kd) ranging from 10(-11) to 10(-12) M3 at the melting temperatures. Extrapolating these values to 23 degrees C predicts Kd values in the 10(-28) M3 range if the heat capacity (Cp) is not strongly dependent upon temperature changes over this range. Assuming Ka is equal to 1/Kd (from melting analyses), very large association free energies stabilize the quadruplex at 23 degrees C in 100 mM KCl (DeltaGa = -43 kcal mol-1). Plots of the differential melt curve peak half-widths, a measure of cooperativity, versus d(TG4) concentration showed that quadruplex dissociation is much more cooperative at 400 mM KCl than at 100 mM KCl. Forty-eight hour quadruplex assembly time courses were monitored by CD at 264 nm. Equilibrium quadruplex accumulation generally required over 10 h, and net reaction extents were in the 10-85% range. Hill plots of the data show that initial steps in the multistep pathway are positively cooperative, presumably due to strong strand-cation and strand-strand binding interactions in duplex and triplex assembly reactions, then negatively cooperative in quadruplex formation. Models were developed to rationalize the experimental observations in terms of consecutive cooperative allosteric transitions from cation-deficient relaxed (R) strand-aggregates to cation-containing tense (T) structures, driven by the allosteric effector K+. Quantitative mappings of positive and then negative cooperativity were obtained by fitting the results as a function of strand number incorporated during quadruplex assembly. Surprisingly, models for reactions involving incorporation of five and six strands fit the data better than models involving only four strands. The 5-step "induced fit" model fits the data as well as or better than 3- and 4-step models and better than all of the strand aggregation models that were devised and investigated. Net association free energies (summation operatori=1,n) ranged from -20 to -26 kcal mol-1, approximately half the magnitude of the apparent stabilities measured by absorbance melts. Likely explanations for this discrepancy involve hysteresis and errors due to inadequate equilibration in the melt experiments. Hysteresis is thought to be produced by irreversibility due to different predominant mechanisms in absorbance (dissociation) and CD (association) experiments. The kinetic block to quadruplex assembly can be unambiguously attributed to quadruplex formation and not intermediate steps in the assembly mechanism. On the basis of these results we propose that, in addition to the more conventional assembly mechanisms involving duplex dimerization and stepwise strand addition, quadruplex formation can also proceed by triplex-triplex disproportionation. Interaction statistics arguments that support the energetic feasibility of the disproportionation pathway are presented. The allosteric quadruplex assembly model provides a mechanism which could be used by the cell to simultaneously modulate DNA structure and activity within telomeres, transcriptional promoters, recombination-prone chromatin, and other G-rich DNAs. As a result of this allosterism, cation and strand availability and strand-pairing capabilities could profoundly influence the functional capacity of a particular strand over a relatively narrow range of effector concentration changes. (ABSTRACT TRUNCATED) DA - 1997/12/9/ PY - 1997/12/9/ DO - 10.1021/bi970488p VL - 36 IS - 49 SP - 15428-15450 SN - 0006-2960 ER - TY - CONF TI - Extended x-ray absorption fine structure study of mercury speciation in a flood plain soil AU - Wang, Z. AU - Hesterberg, D. AU - Zhou, W. AU - Sayers, D. E. AU - Robarge, W. P. C2 - 1997/// C3 - Contaminated soils: 3rd International Conference on the Biogeochemistry of Trace Elements, Paris (France), May 15-19, 1995 DA - 1997/// M1 - 1997 PB - Paris: INRA Editions ER - TY - CHAP TI - Translational regulation of bioiron AU - Theil, E. C. T2 - Metal ions in gene regulation A2 - S. Silver, A2 - Walden, W. CN - QP532 .M473 1998 PY - 1997/// DO - 10.1007/978-1-4615-5993-1_6 SP - 131-156 PB - New York: Chapman & Hall ER - TY - JOUR TI - Purification and characterization of protein D/E, a putative sperm-binding protein involved in fertilization AU - Hall, JC AU - Tubbs, CE T2 - PREPARATIVE BIOCHEMISTRY & BIOTECHNOLOGY AB - ABSTRACT We describe a method for the efficient purification of a 32 Kd glycoprotein from rat epididymal tissue. The glycoprotein was purified by gel filtration, ion-exchange, affinity, and reverse phase high pressure liquid chromatography. The highly purified glycoprotein was radiolabeled with an iodinatable, cleavable, photoreactive cross-linking agent, l-[N-(2-hydrox-5-azidobenzoyl)-2-aminoethyl]-4-(-hydroxysuccinimidyl)-succinate (HAHS). The soluble radiolabled glycoprotein was bound to washed epididymal spermatozoa in a time-dependent, saturable, and reversible manner. Scatchard analysis demonstrates mat there are approximately 3,403 binding sites/spermatozoon. The binding efficiency (Kd) for spermatozoa was ≈2.0 × 10−10 M. The function of this glycoprotein was verified by using an in vivo artificial insemination fertilization assay. The fertility rate for control spermatozoa was ≈53%, but the rate for spermatozoa exposed to polyclonal anti-glycoprotein antibodies was only 5%. These data suggest that the binding of the glycoprotein to the surface of rat spermatozoa is mediated by a receptor-type mechanism and is involved in the fertilization process. DA - 1997/// PY - 1997/// DO - 10.1080/10826069708001282 VL - 27 IS - 4 SP - 239-251 SN - 1082-6068 ER - TY - JOUR TI - Inheritance, gene expression, and lignin characterization in a mutant pine deficient in cinnamyl alcohol dehydrogenase AU - MacKay, JJ AU - OMalley, DM AU - Presnell, T AU - Booker, FL AU - Campbell, MM AU - Whetten, RW AU - Sederoff, RR T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - We have discovered a mutant loblolly pine (Pinus taeda L.) in which expression of the gene encoding cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) is severely reduced. The products of CAD, cinnamyl alcohols, are the precursors of lignin, a major cell wall polymer of plant vascular tissues. Lignin composition in this mutant shows dramatic modifications, including increased incorporation of the substrate of CAD (coniferaldehyde), indicating that CAD may modulate lignin composition in pine. The recessive cad-n1 allele, which causes this phenotype, was discovered in a tree heterozygous for this mutant allele. It is inherited as a simple Mendelian locus that maps to the same genomic region as the cad locus. In mutant plants, CAD activity and abundance of cad RNA transcript are low, and free CAD substrate accumulates to a high level. The wood of the mutant is brown, whereas the wood in wild types is nearly white. The wood phenotype resembles that of brown midrib (bm) mutants and some transgenic plants in which xylem is red-brown due to a reduction in CAD activity. However, unlike transgenics with reduced CAD, the pine mutant has decreased lignin content. Wood in which the composition of lignin varies beyond previous expectations still provides vascular function and mechanical support. DA - 1997/7/22/ PY - 1997/7/22/ DO - 10.1073/pnas.94.15.8255 VL - 94 IS - 15 SP - 8255-8260 SN - 0027-8424 ER - TY - JOUR TI - CIS elements that contribute to geminivirus transcriptional regulation and the efficiency of DNA replication AU - Eagle, P. A. AU - Hanley-Bowdoin, L. K. T2 - Journal of Virology DA - 1997/// PY - 1997/// VL - 71 IS - 9 SP - 6947-6955 ER - TY - JOUR TI - XAFS characterization of copper contamination in the unsaturated and saturated zones of a soil profile AU - Sayers, DE AU - Hesterberg, D AU - Zhou, W AU - Robarge, WP AU - Plummer, GM T2 - JOURNAL DE PHYSIQUE IV AB - The fate of heavy-metal contaminants in the environment, and the design and success of remediation strategies at hazardous waste sites depend on the chemical speciation of the contaminants. The objective of this study was to determine the molecular-scale chemical form (species) of heavy metals in different zones of a contaminated soil having a shallow ground water table. Copper in the unsaturated surface horizon and the water-saturated and partially-saturated subsurface horizons of a disturbed soil from the lower eastern coastal plain of North Carolina was characterized using XAFS spectroscopy. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) data showed that the dominant form of Cu(II) bonding ranged from Cu-S in the deeper soil zones to Cu-O in the shallowest zone. The results suggest that the surface and subsurface horizons will respond differently to remediation treatments. DA - 1997/4// PY - 1997/4// DO - 10.1051/jp4:1997252 VL - 7 IS - C2 SP - 831-832 SN - 1155-4339 ER - TY - JOUR TI - XAFS Characterization of Copper in Model Aqueous Systems of Humic Acid and Illite AU - Hesterberg, D. AU - Sayers, D. E. AU - Zhou, W. AU - Robarge, W. P. AU - Plummer, G. M. T2 - Le Journal de Physique IV AB - Adsorption of heavy metals at mineral surfaces and complexation with reactive organic-matter functional groups are important processes regulating the solubility and fate of soil contaminants. To determine the nature of Cu(II) bonding in complex clay-organic systems, XAFS analyses were conducted on aqueous suspensions containing Cu(II) in various forms: (i) complexed with soil humic acid (HA) at various HA:Cu ratios, (ii) bound to illite, or (iii) bound in a mixture of illite and HA. Spectral features for Cu bound to HA did not depend significantly on the HA:Cu ratio, and average first-shell Cu-O bond lengths were consistently shorter than for the Cu-illite systems. In the mixed clay-organic suspension, Cu bonding was more characteristic to that of Cu bound with HA. DA - 1997/4// PY - 1997/4// DO - 10.1051/jp4:1997253 VL - 7 IS - C2 SP - C2-833-C2-834 J2 - J. Phys. IV France OP - SN - 1155-4339 UR - http://dx.doi.org/10.1051/jp4:1997253 DB - Crossref ER - TY - JOUR TI - X-ray absorption spectroscopy of lead and zinc speciation in a contaminated groundwater aquifer AU - Hesterberg, D AU - Sayers, DE AU - Zhou, WQ AU - Plummer, GM AU - Robarge, WP T2 - ENVIRONMENTAL SCIENCE & TECHNOLOGY AB - The formation of insoluble metal sulfides in the environment may reduce the mobility and bioavailability of heavy metal contaminants and potentially eliminate the need for ex situ remediation of certain hazardous waste sites. To assist in assessing remediation strategies for the Bypass 601 Superfund site, groundwater aquifer samples were analyzed using synchrotron X-ray absorption spectroscopy (XAS) to determine whether lead and zinc sulfides were dominant mineral phases. Moist aquifer solids contained between 150 and 1800 mg of Pb/kg and between 100 and 250 mg of Zn/kg. Lead sulfide was not dominant in any of the samples analyzed, including one sample collected from a well in a flood plain that contained 70% of zinc bonded to sulfur, probably as ZnS. This portion of the aquifer had apparently been under reducing conditions. In all other samples, first-shell bonding of Pb and Zn was predominantly to oxygen. Data indicated that PbO, PbCO3, PbSO4, and ZnO were not dominant metal species. The XAS analyses showed that with one exception, metal sulfides were not prevalent. DA - 1997/10// PY - 1997/10// DO - 10.1021/es970077w VL - 31 IS - 10 SP - 2840-2846 SN - 1520-5851 ER - TY - JOUR TI - Using precharged zeolite as a source of potassium and phosphate in a soilless container medium during potted chrysanthemum production AU - Williams, K. A. AU - Nelson, P. V. T2 - Journal of the American Society for Horticultural Science DA - 1997/// PY - 1997/// VL - 122 IS - 5 SP - 703-708 ER - TY - JOUR TI - The influence of conserved tyrosine 30 and tissue-dependent differences in sequence on ferritin function: use of blue and purple Fe(III) species as reporters of ferroxidation AU - Fetter, J. AU - Cohen, J. AU - Danger, D. P. AU - Sanders, Loehr J. AU - Theil, E. C. T2 - Journal of Biological Inorganic Chemistry AB - Ferritins uniquely direct the vectorial transfer of hydrated Fe(II)/Fe(III) ions to a condensed ferric phase in the central cavity of the soluble protein. Secondary, tertiary and quaternary structure are conserved in ferritin, but only five amino acid residues are conserved among all known ferritins. The sensitivity of ferroxidation rates to small differences in primary sequence between ferritin subunits that are cell-specifically expressed or to the conservative replacement of the conserved tyrosine 30 residue was demonstrated by examining recombinant (frog) H-type (red blood cell predominant) and M-type subunit (liver predominant) proteins which are both fast ferritins; the proteins form two differently colored Fe(III)-protein complexes absorbing at 550 nm or 650 nm, respectively. The complexes are convenient reporters of Fe(III)-protein interaction because they are transient in contrast to the Fe(III)-oxy complexes measured in the past at 310–420 nm, which are stable because of contributions from the mineral itself. The A650-nm species formed 18-fold faster in the M-subunit protein than did the 550-nm species in H-subunit ferritin, even though all the ferroxidase residues are the same; the Vmax was fivefold faster but the Hill coefficents were identical (1.6), suggesting similar mechanisms. In H-subunit ferritin, substitution of phenylalanine for conserved tyrosine 30 (located in the core of the subunit four-helix bundle) slowed ferroxidation tenfold, whereas changing surface tyrosine 25 or tyrosine 28 had no effect. The Fe(III)-tyrosinate was fortunately not changed by the mutation, based on the resonance Raman spectrum, and remained a suitable reporter for Fe(III)-protein interactions. Thus, the A550/650 nm can also report on post-oxidation events such as transport through the protein. The impact of Y30F on rates of formation of Fe(III)-protein complexes in ferritin, combined with Mössbauer spectroscopic studies that showed the parallel formation of multiple Fe(III) postoxidation species (three dinuclear oxy and one trinuclear oxy species) (A. S. Periera et al., Biochemistry 36 : 7917–7927, 1997) and the loss of several of the multimeric Fe(III) post-oxidation species in a Y30F alteration of human recombinant H-ferritin (E. R. Bauminger et al., Biochem J. 296 : 709–719, 1993), indicate that at least one of the pathways for Fe oxidation/transfer in ferritin is through the center of the four-helix bundle and is influenced by structural features dependent on tyrosine 30. DA - 1997/// PY - 1997/// DO - 10.1007/s007750050180 VL - 2 IS - 5 SP - 652-661 ER - TY - JOUR TI - Rapid detection of Phytophthora infestans in late blight-infected potato and tomato using PCR AU - Trout, CL AU - Ristaino, JB AU - Madritch, M AU - Wangsomboondee, T T2 - PLANT DISEASE AB - Late blight caused by the oomycete pathogen Phytophthora infestans is a devastating disease of potato and tomato worldwide. A rapid and accurate method for specific detection of P. infestans is necessary for determination of late blight in infected fruit, leaves, and tubers. Ribosomal DNA (rDNA) from four isolates of P. infestans representing the four genotypes US1, US6, US7, and US8 was amplified using polymerase chain reaction (PCR) and the universal primers internal transcribed spacer (ITS) 4 and ITS5. PCR products were sequenced using an automated sequencer. Sequences were aligned with published sequences from 5 other Phytophthora species, and a region specific to P. infestans was used to construct a PCR primer (PINF). Over 140 isolates representing 14 species of Phytophthora and at least 13 other genera of fungi and bacteria were used to screen the PINF primer. PCR amplification with primers PINF and ITS5 results in amplification of an approximately 600 base pair product with only isolates of P. infestans from potato and tomato, as well as isolates of P. mirabilis and P. cactorum. P. mirabilis and P. cactorum are not pathogens of potato; however, P. cactorum is a pathogen of tomato. P. infestans and P. cactorum were differentiated by restriction digests of the amplified product. The PINF primer was used with a rapid NaOH lysis technique for direct PCR of P. infestans from infected tomato and potato field samples. The PINF primer will provide a valuable tool for detection of P. infestans in potatoes and tomatoes. DA - 1997/9// PY - 1997/9// DO - 10.1094/PDIS.1997.81.9.1042 VL - 81 IS - 9 SP - 1042-1048 SN - 0191-2917 KW - disease diagnosis ER - TY - JOUR TI - Preliminary analysis of amphibian red cell M ferritin in a novel tetragonal unit cell AU - Ha, Y AU - Theil, EC AU - Allewell, NM T2 - ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY AB - The ferritins are a multigene family of proteins that concentrate and store iron in all prokaryotic and eukaryotic cells. 24 monomeric subunits which fold as four-helix bundles assemble to form a protein shell with 432 cubic symmetry and an external diameter of approximately 130 A. The iron is stored inside the protein shell as a mineralized core approximately 80 A in diameter. Recombinant amphibian red cell M ferritin crystallizes in approximately 2 M (NH(4))(2)SO(4) at pH 4.6 in a space group that has not been reported previously. Electron microscopy, precession photography, Patterson and Fourier maps of the native protein and a UO(2)(2+) derivative, and simulations were used to determine that the unit-cell dimensions are a = b = 169.6, c = 481.2 A, alpha = beta = gamma = 90 degrees and the space group is P4(1)2(1)2 or P4(3)2(1)2. A preliminary model of the structure was obtained by molecular replacement, with amphibian red cell L ferritin as the model. In contrast to previously determined ferritin crystal structures which have intermolecular contacts at the twofold and threefold molecular axes, M ferritin crystals have a novel intermolecular interaction mediated by interdigitation of the DE loops of two molecules at the fourfold molecular axes. DA - 1997/9/1/ PY - 1997/9/1/ DO - 10.1107/S0907444997003983 VL - 53 SP - 513-523 SN - 2059-7983 ER - TY - JOUR TI - Micro-scale method for determining foaming properties of protein AU - Huang, XL AU - Catignani, GL AU - Swaisgood, HE T2 - JOURNAL OF FOOD SCIENCE AB - ABSTRACT A 5% protein suspension (4 mL) was whipped in a modified 50‐mL centrifuge tube using a tissumizer equipped with a flat‐bottom generator. Drainage time at 50% liquid weight and the weight of the foam formed/unit volume were used for calculating foam stability and foam overrun, respectively. The foaming properties of a variety of milk proteins were determined using this method. This method distinguished differences in foaming properties among the proteins. Values for overrun confirmed published results. Compared with standard methods, this method required much less sample (about 1/20) and less measuring time (about 1/5 to 1/10). DA - 1997/// PY - 1997/// DO - 10.1111/j.1365-2621.1997.tb15030.x VL - 62 IS - 5 SP - 1028-& SN - 0022-1147 KW - microscale whipping method KW - foam properties KW - protein ER - TY - JOUR TI - Electrical and structural properties of zirconium germanosilicide formed by a bilayer solid state reaction of Zr with strained Si1-xGex alloys AU - Wang, Z AU - Aldrich, DB AU - Nemanich, RJ AU - Sayers, DE T2 - JOURNAL OF APPLIED PHYSICS AB - The effects of alloy composition on the electrical and structural properties of zirconium germanosilicide (Zr–Si–Ge) films formed during the Zr/Si1−xGex solid state reaction were investigated. Thin films of Zr(Si1−yGey) and C49 Zr(Si1−yGey)2 were formed from the solid phase reaction of Zr and Si1−xGex bilayer structures. The thicknesses of the Zr and Si1−xGex layers were 100 and 500 Å, respectively. It was observed that Zr reacts uniformly with the Si1−xGex alloy and that C49 Zr(Si1−yGey)2 with y=x is the final phase of the Zr/Si1−xGex solid phase reaction for all compositions examined. The sheet resistance of the Zr(Si1−yGey)2 thin films was higher than the sheet resistance of similarly prepared ZrSi2 films. The stability of Zr(Si1−yGey)2 in contact with Si1−xGex was investigated and compared to the stability of Ti(Si1−yGey)2 in contact with Si1−xGex. The Ti(Si1−yGey)2/Si1−xGex structure is unstable when annealed for 10 min at 700 °C, with Ge segregating from Ti(Si1−yGey)2 and forming Ge-rich Si1−zGez precipitates at grain boundaries. In contrast, no Ge segregation was detected in the Zr(Si1−yGey)2/Si1−xGex structures. We attribute the stability of the Zr-based structure to a smaller thermodynamic driving force for germanium segregation and stronger atomic bonding in C49 Zr(Si1−yGey)2. Classical thermodynamics were used to calculate Zr(Si1−yGey)2–Si1−xGex tie lines in the Zr–Si–Ge ternary phase diagram. The calculations were compared with previously calculated Ti(Si1−yGey)2–Si1−xGex tie lines. DA - 1997/9/1/ PY - 1997/9/1/ DO - 10.1063/1.366043 VL - 82 IS - 5 SP - 2342-2348 SN - 0021-8979 ER - TY - JOUR TI - Effects of canola oil based high fat diets on growth, fat deposition and serum triglyceride and cholesterol levels in lines of mice selected for high and low fat percentage AU - Benyon, L. S. AU - Eisen, E. J AU - Jones, E. E. T2 - Revista Brasileira De Genetica DA - 1997/// PY - 1997/// DO - 10.1590/s0100-84551997000200009 VL - 20 IS - 2 SP - 203-213 ER - TY - JOUR TI - Characterization of superoxide dismutase in Streptococcus thermophilus AU - Chang, S. K. AU - Hassan, H. M. T2 - Applied and Environmental Microbiology DA - 1997/// PY - 1997/// VL - 63 IS - 9 SP - 3732-3735 ER - TY - JOUR TI - Characterization of carbon supported Pt/Ru alloy particles using EXAFS spectroscopy AU - Pandya, KI AU - Anderson, EB AU - Sayers, DE AU - OGrady, WE T2 - JOURNAL DE PHYSIQUE IV AB - mu alloys are used for electmoxidation of methanol in direct methanol he1 cells. Theii catalytic activity shun& depends upon the stmckm and +tim of the We have investigated the stmhre of PtlRu alloy particles #anhighsurface~csrtmhthreedifferent compositions, namely Pt:Ru,8.5:1.5.1:1 and 1.5:8.5. The samples were prepared by impregnating the carbon with salt solutions ofthe two metals fdlowed by redwAon to the alloy. The total metal hdiag was I0 wt%. The Pt L, andRuKEXAFS -ts were e'. Data Processing: The EXAFS function ~(k) was separated from the experimentally measured absorption specbum using the standard procedures. The R L, and Ru Kedge radial shwture functions (RSFs) for the alloy samples are shown in the figures 3 and 4, respectively. The RSFs are sigdkdy different from each other indicating that the structure strongly depends upon the composition. The effect of the DA - 1997/4// PY - 1997/4// DO - 10.1051/jp4:1997299 VL - 7 IS - C2 SP - 955-956 SN - 1155-4339 ER - TY - JOUR TI - An integrated growth and analysis system for in-situ XAS studies of metal-semiconductor interactions AU - Wang, Z AU - Goeller, PT AU - Boyanov, BI AU - Sayers, DE AU - Nemanich, RJ T2 - JOURNAL DE PHYSIQUE IV AB - A UHV system for in-situ studies of metal-semiconductor interactions has been designed and assembled at North Carolina State University and recently installed and tested at the NSLS. The UHV system consists of interconnected deposition and analysis chambers, each of which is capable of maintaining a base pressure of approximately 1 x 10 -10 Torr. Up to three materials can be co-deposited on 25 mm wafers by electron-beam evaporation. Substrate temperature can be controlled in the range 30-900 °C during deposition, and the growth process may be monitored with RHEED. The deposited materials and their reaction products can be studied in-Situ with a variety of technique: XAFS, AES, XPS, UPS and ARXPS/UPS. We describe the capabilities of the system and present our first EXAFS results on the stabilization of Co + 2 Si films co-deposited on Si 0.8 Ge 0.2 alloys. Preliminary results indicate that Co + 2Si forms a stable film on Si 0.8 Ge 0.2 with a CoSi 2 -like reaction path. As is the case with CO/Si 0.8 Ge 0.2 , silicide formation is complete at 700 °C. However, the Co+2Si/Si 0.8 Ge 0.2 system does not undergo a Cosi → CoSi 2 transition when annealed at 500-700 °C, and exhibits only weak CoSi features in this temperature range. DA - 1997/4// PY - 1997/4// DO - 10.1051/jp4/1997096 VL - 7 IS - C2 SP - 561-564 SN - 1155-4339 ER - TY - JOUR TI - Water quality of first flush runoff from 20 industrial sites AU - Line, DE AU - Wu, J AU - Arnold, JA AU - Jennings, GD AU - Rubin, AR T2 - WATER ENVIRONMENT RESEARCH AB - A sampling program was conducted to assess the quality of first flush storm water runoff from 10 industrial groups typical of many businesses located in North Carolina. Analysis of samples collected during the first 30 min of runoff (first flush) indicated that zinc and copper were the most common of the eight metals measured in runoff from the 20 industrial sites monitored. Ten volatile organic, semivolatile organic, or pesticide compounds were found at eight different sites, with the most common being methylene chloride (three sites). Conventional pollutants such as nutrients and solids were measured at varying levels at every site, but were generally the highest where a significant amount of biological waste or exposed soil was present. DA - 1997/// PY - 1997/// DO - 10.2175/106143097X125489 VL - 69 IS - 3 SP - 305-310 SN - 1061-4303 KW - metals KW - monitoring KW - runoff KW - stormwater KW - water quality ER - TY - JOUR TI - Unconventional structure of tRNA(Lys)SUU anticodon explains tRNA's role in bacterial and mammalian ribosomal frameshifting and primer selection by HIV-1 AU - Agris, P. F. AU - Guenther, R. H. AU - Ingram, P. C. AU - Basti, M. M. AU - Stuart, J. W. AU - Sochacka, E. AU - Malkiewicz, A. T2 - RNA DA - 1997/// PY - 1997/// VL - 3 IS - 4 SP - 420-428 ER - TY - JOUR TI - Two proximal activating protein-1-binding sites are sufficient to stimulate transcription of the ovine follicle-stimulating hormone-beta gene AU - Strahl, BD AU - Huang, HJ AU - Pedersen, NR AU - Wu, JC AU - Ghosh, BR AU - Miller, WL T2 - ENDOCRINOLOGY AB - FSH is an important regulator of mammalian gametogenesis and the female reproductive cycle. Although little is known about the transcriptional regulation of the β-subunit (the rate-limiting subunit of FSH synthesis), sequence analysis of the ovine FSHβ promoter has revealed a number of potential activating protein-1 (AP-1; Jun/Fos)-binding sites. To determine whether the gene encoding theβ -subunit of ovine FSH (oFSHβ) is responsive to AP-1 transcriptional complexes, chimeric constructs containing deleted portions of the oFSHβ promoter fused to a luciferase reporter were transiently transfected along with c-Jun and c-Fos expression constructs into JAR cells. Analysis of these deletion constructs revealed that the proximal promoter of oFSHβ is highly stimulated by c-Jun and c-Fos proteins (typically 20-fold with a reporter construct containing oFSHβ sequences from −215 to +759 bp). This stimulation was lost when a similar construct containing sequences from −84 to+ 759 bp was tested. Transcriptional start site analysis using reverse transcription-PCR verified that the transcriptional initiation of the− 215-bp deletion construct, with or without cotransfected c-Jun/c-Fos, was the same as that observed in vivo. Computer analysis of oFSHβ sequences from −215 to +1 bp identified four putative AP-1-like elements, located at −155, −120, −83, and −10 bp. Gel retardation experiments using oligonucleotides corresponding to the four putative AP-1-like sites revealed that only −120 and −83 sites in oFSHβ bound AP-1 proteins in vitro. Site-directed mutagenesis of the −120 and −83 sites showed that each element was required for stimulation by c-Jun and c-Fos proteins as well as 12-O-tetradecanoyl phorbol-13-acetate in transient transfection assays. Finally, immunocytochemical dual labeling was used to show that more than 75% of all FSHβ-containing cells in ovine pituitary sections from cycling ewes contained nuclear c-Jun, JunB, JunD, and Fos proteins. These data, taken together, show that oFSHβ transcription can be stimulated by c-Jun and c-Fos proteins via two functionally linked AP-1-like sites in the oFSHβ proximal promoter and that these sites are likely to be important regulators of FSH production in vivo. DA - 1997/6// PY - 1997/6// DO - 10.1210/en.138.6.2621 VL - 138 IS - 6 SP - 2621-2631 SN - 1945-7170 ER - TY - JOUR TI - Superinfection exclusion of alphaviruses in three mosquito cell lines persistently infected with sindbis virus AU - Karpf, A. R. AU - Lenches, E. AU - Strauss, E. G. AU - Strauss, J. H. AU - Brown, D. T. T2 - Journal of Virology DA - 1997/// PY - 1997/// VL - 71 IS - 9 SP - 7119-7123 ER - TY - JOUR TI - RRB1 and RRB2 encode maize retinoblastoma-related proteins that interact with a plant D-type cyclin and geminivirus replication protein AU - Ach, RA AU - Durfee, T AU - Miller, AB AU - Taranto, P AU - HanleyBowdoin, L AU - Zambryski, PC AU - Gruissem, W T2 - MOLECULAR AND CELLULAR BIOLOGY AB - Unlike mammalian and yeast cells, little is known about how plants regulate G1 progression and entry into the S phase of the cell cycle. In mammalian cells, a key regulator of this process is the retinoblastoma tumor suppressor protein (RB). In contrast, G1 control in Saccharomyces cerevisiae does not utilize an RB-like protein. We report here the cloning of cDNAs from two Zea mays genes, RRB1 and RRB2, that encode RB-related proteins. Further, RRB2 transcripts are alternatively spliced to yield two proteins with different C termini. At least one RRB gene is expressed in all the tissues examined, with the highest levels seen in the shoot apex. RRB1 is a 96-kDa nuclear protein that can physically interact with two mammalian DNA tumor virus oncoproteins, simian virus 40 large-T antigen and adenovirus E1A, and with a plant D-type cyclin. These associations are abolished by mutation of a conserved cysteine residue in RRB1 that is also essential for RB function. RRB1 binding potential is also sensitive to deletions in the conserved A and B domains, although differences exist in these effects compared to those of human RB. RRB1 can also bind to the AL1 protein from tomato golden mosaic virus (TGMV), a protein which is essential for TGMV DNA replication. These results suggest that G1 regulation in plant cells is controlled by a mechanism which is much more similar to that found in mammalian cells than that in yeast. DA - 1997/9// PY - 1997/9// DO - 10.1128/MCB.17.9.5077 VL - 17 IS - 9 SP - 5077-5086 SN - 0270-7306 ER - TY - JOUR TI - Purity and yield of beta-lactoglobulin isolated by an N-retinyl-Celite bioaffinity column AU - Heddleson, RA AU - Allen, JC AU - Wang, QW AU - Swaisgood, HE T2 - JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY AB - A bioaffinity column of all-trans-retinal immobilized on Celite was capable of isolating high-purity (94.5%) β-lactoglobulin from bovine acid whey. Conditions for producing a potentially hypoallergenic reduced β-lactoglobulin whey were investigated. Reapplication of pH 5.1 eluate to the column resulted in a final purity of 87% α-lactalbumin. The purity of β-lactoglobulin was slightly lower upon elution with buffers containing <0.4 M sodium phosphate, whereas the yield from desorbing buffers <0.1 M decreased to approximately 40% of that obtained with 0.4 M sodium phosphate. Desorption with low phosphate concentration was improved when pH was increased, suggesting that desorption involves titration of a protophilic group on β-lactoglobulin. These findings suggest that the retinal matrix shows promise in its application for creating hypoallergenic products and the isolation of high-purity β-lactoglobulin with useful functional properties. Keywords: β-Lactoglobulin; α-lactalbumin; bioselective adsorption; N-retinyl-Celite DA - 1997/7// PY - 1997/7// DO - 10.1021/jf9605198 VL - 45 IS - 7 SP - 2369-2373 SN - 0021-8561 KW - beta-lactoglobulin KW - alpha-lactalbumin KW - bioselective adsorption KW - N-retinyl-Celite ER - TY - JOUR TI - Production and purification of an active bovine lysozyme in tobacco (Nicotiana tabacum): Utilization of value-added crop plants traditionally grown under intensive agriculture AU - Wilcox, CP AU - Weissinger, AK AU - Long, RC AU - Fitzmaurice, LC AU - Mirkov, TE AU - Swaisgood, HE T2 - JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY AB - The goals of this study were to express bovine lysozyme in tobacco and to purify the protein with a scaleable process to >90% homogeneity while retaining antimicrobial characteristics. Results showed that the enzyme was expressed at levels equivalent to 1−1.5% of total fraction 2 protein in each of five different transformant groups. The enzyme was subsequently purified to 93% homogeneity using an easily scaleable process while retaining high activity. It was concluded that tobacco was an excellent choice for expression of the recombinant protein and that the purification process developed in this study demonstrates methodology for isolation of high-value enzymes from tobacco and other crop plants. Keywords: Transgenic; lysozyme; recombinant protein; antimicrobial; Nicotiana tabacum DA - 1997/7// PY - 1997/7// DO - 10.1021/jf970156r VL - 45 IS - 7 SP - 2793-2797 SN - 0021-8561 KW - transgenic KW - lysozyme KW - recombinant protein KW - antimicrobial KW - Nicotiana tabacum ER - TY - JOUR TI - Numerical simulation of the platinum L (III) edge white line relative to nanometer scale clusters AU - Bazin, D. AU - Sayers, D. E. AU - Rehr, J. J. AU - Mottet, C. T2 - Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces & Biophysical DA - 1997/// PY - 1997/// VL - 101 IS - 27 SP - 5332-5336 ER - TY - JOUR TI - Mutations that alter a conserved element upstream of the potato virus X triple block and coat protein genes affect subgenomic RNA accumulation AU - Kim, KH AU - Hemenway, C T2 - VIROLOGY AB - The putative subgenomic RNA (sgRNA) promoter regions upstream of the potato virus X (PVX) triple block and coat protein (CP) genes contain sequences common to other potexviruses. The importance of these sequences to PVX sgRNA accumulation was determined by inoculation ofNicotiana tabacumNT1 cell suspension protoplasts with transcripts derived from wild-type and modified PVX cDNA clones. Analyses of RNA accumulation by S1 nuclease digestion and primer extension indicated that a conserved octanucleotide sequence element and the spacing between this element and the start-site for sgRNA synthesis are critical for accumulation of the two major sgRNA species. The impact of mutations on CP sgRNA levels was also reflected in the accumulation of CP. In contrast, genomic minus- and plus-strand RNA accumulation were not significantly affected by mutations in these regions. Studies involving inoculation of tobacco plants with the modified transcripts suggested that the conserved octanucleotide element functions in sgRNA accumulation and some other aspect of the infection process. DA - 1997/5/26/ PY - 1997/5/26/ DO - 10.1006/viro.1997.8565 VL - 232 IS - 1 SP - 187-197 SN - 0042-6822 ER - TY - JOUR TI - Modification of milkfat physical properties by immobilized Pseudomonas fluorescens lipase AU - Lee, P AU - Swaisgood, HE T2 - JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY AB - A bifunctional fusion protein was constructed by fusion of the streptavidin gene from Streptomyces avidinii to the lipase gene from Pseudomonas fluorescens, and the resulting streptavidin−lipase was expressed in Escherichia coli. Immobilized streptavidin−lipase was prepared by direct bioselective adsorption from crude cell lysates on biotinylated controlled-pore glass and used to catalyze interesterification of anhydrous butteroil. Changes in the triacylglycerol composition indicated that those with equivalent carbon numbers (ECN) ranging from 36 to 42 decreased, while those with ECN values from 48 to 50 increased following interesterification for 120 h in hexane at 42 °C. Both the melting temperatures and the solid fat content at various temperatures were lower as compared to those of the unmodified butteroil. Addition of unsaturated fatty acids, linoleic and linolenic, yielded modified butteroils with lower melting points and solid fat content, whereas addition of saturated fatty acids, palmitic and stearic, increased the solid fat content of the modified butteroil. The liquid butteroil could function as a solvent as well as the substrate; however, the interesterification reaction rate was much slower than in hexane. Keywords: Milkfat; immobilized lipase; streptavidin−lipase; fusion protein; interesterification DA - 1997/8// PY - 1997/8// DO - 10.1021/jf970166s VL - 45 IS - 8 SP - 3343-3349 SN - 0021-8561 KW - milkfat KW - immobilized lipase KW - streptavidin-lipase KW - fusion protein KW - interesterification ER - TY - JOUR TI - Hydrogen chemisorption on silica-supported Pt clusters: In situ X-ray absorption spectroscopy AU - Reifsnyder, SN AU - Otten, MM AU - Sayers, DE AU - Lamb, HH T2 - JOURNAL OF PHYSICAL CHEMISTRY B AB - Hydrogen chemisorption on small silica-supported Pt clusters was investigated using in situ extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near-edge structure (XANES) spectroscopy. The clusters were found to exhibit a bulklike Pt first nearest neighbor (NN) distance (2.76 Å) and low disorder while covered by chemisorbed hydrogen. In contrast, bare Pt clusters produced by heating in vacuo at 300 °C are characterized by a contracted Pt NN distance (2.66 Å) and greater disorder. These effects are reversed by re-exposure of the bare Pt clusters to H2 at 25 °C. The metal−support interface is characterized by a short Pt−O distance, irrespective of the presence of chemisorbed hydrogen. An apparent L3 edge shift of 0.8 eV relative to bulk Pt is observed for the hydrogen-covered clusters. This shift is attributed to a decrease in the Pt L3 edge resonance (white line) intensity, as no corresponding shift is observed at the L2 edge. A hydrogen-related L2,3 XANES feature at 9 eV appears with nearly equal intensity at each edge. This peak is assigned to electronic transitions from Pt 2p levels to H 1s−Pt 5d antibonding states with mixed d3/2−d5/2 character. From the L2,3 XANES analysis, we find that the number of unoccupied d states in hydrogen-covered Pt clusters is 23% less than in bulk Pt. In contrast, the L2,3 XANES spectra of bare silica-supported Pt clusters are closely similar to those of bulk Pt; quantitative analysis reveals only a slight (4%) decrease in the number of unoccupied d states. DA - 1997/6/19/ PY - 1997/6/19/ DO - 10.1021/jp970244e VL - 101 IS - 25 SP - 4972-4977 SN - 1089-5647 ER - TY - JOUR TI - Exact determination of UV-induced crosslinks in 16S ribosomal RNA in 30s ribosomal subunits AU - Wilms, C. AU - Noah, J. W. AU - Zhong, D. G. AU - Wollenzien, P. L. T2 - RNA DA - 1997/// PY - 1997/// VL - 3 IS - 6 SP - 602-612 ER - TY - JOUR TI - Characterization of a chemically conjugated lipase bioreactor AU - Lee, P AU - Swaisgood, HE T2 - JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY AB - Lipase from Candida cylindracea was immobilized on glass beads using the biospecific and high-affinity avidin−biotin interaction. Biotinylated lipase and glass beads were prepared by reactions of lipase and 3-aminopropyl glass beads with sulfosuccinimidyl-6-(biotinamido)hexanoate (NHS-LC-biotin). Avidin and biotinylated lipase were sequentially adsorbed to the biotinylated glass beads. Biotinylated lipase in solution retained about 63% of the hydrolytic specific activity of native lipase when an average 3 mol of biotin was incorporated/mol of lipase. Nonporous glass beads contained more biotin and protein (avidin and lipase) per unit of surface area, followed by 302 nm mean pore diameter controlled-pore glass beads (CPG-3000) and 198 nm mean pore diameter controlled-pore glass beads (CPG-2000). The hydrolytic specific activity of lipase immobilized on CPG-3000 and on nonporous beads was essentially the same as that for the biotinylated free enzyme, whereas that immobilized on CPG-2000 was about 50% less. The long spacer of NHS-LC-biotin (22.4 Å maximum length) and avidin (70 Å diameter) reduced steric hindrances with emulsified substrates on the matrix surface, resulting in a higher hydrolytic activity as compared with lipase immobilized via covalent linkages. The interesterification activity was 4-fold greater for immobilized lipase than for free lipase. Keywords: Biotinylated lipase; immobilized lipase; immobilized avidin; interesterification DA - 1997/8// PY - 1997/8// DO - 10.1021/jf970167k VL - 45 IS - 8 SP - 3350-3356 SN - 0021-8561 KW - biotinylated lipase KW - immobilized lipase KW - immobilized avidin KW - interesterification ER - TY - JOUR TI - Binding of vitamin D and cholesterol to beta-lactoglobulin AU - Wang, QW AU - Allen, JC AU - Swaisgood, HE T2 - JOURNAL OF DAIRY SCIENCE AB - beta-Lactoglobulin was isolated directly from acidic whey by bioselective adsorption on N-retinyl-Celite, yielding preparations of > or = 96% purity. Interactions of these preparations with vitamin D2, vitamin D3, ergosterol, cholesterol, and 7-dehydrocholesterol were examined by following changes in the fluorescence spectra. Both the excitation and emission spectra indicated that energy was transferred between the tryptophanyl residues of the protein and the chromophore of the ligand. Analyses of the fluorescence changes that occurred upon titration of beta-LG with the various ligands allowed determination of the dissociation constant for the complex and the number of moles bound per mole of protein. The affinity for vitamin D2 (dissociation constant of 4.91 nM) was 10-fold higher than that of the other compounds, except for ergosterol, which was 5-fold larger than the others. Also, the affinity was 10-fold higher than that typically reported for the retinoids. Furthermore, the value obtained for the number of moles bound per mole of protein was 2 mol.mol-1 for each of the ligands examined in this study; it has been well established that all of the retinoids are bound with a stoichiometry of 1.0. These results suggest that beta-LG may be a better carrier of vitamin D than of vitamin A. DA - 1997/6// PY - 1997/6// DO - 10.3168/jds.S0022-0302(97)76030-2 VL - 80 IS - 6 SP - 1054-1059 SN - 0022-0302 KW - beta-lactoglobulin KW - vitamin D binding KW - cholesterol binding KW - bioselective adsorption ER - TY - JOUR TI - Binding of retinoids to beta-lactoglobulin isolated by bioselective adsorption AU - Wang, QW AU - Allen, JC AU - Swaisgood, HE T2 - JOURNAL OF DAIRY SCIENCE AB - Binding of the retinoids, all-trans-retinol, all-trans-retinal, all-trans-retinyl acetate, and all-trans-retinoic acid, to beta-lactoglobulin (LG) (96% purity) that had been prepared by bioselective adsorption on N-retinyl-Celite was determined from changes in the fluorescence quenching (332 nm) of the protein tryptophanyl residues. High affinity binding of all of these compounds occurred at pH 7.0, and the apparent dissociation constant ranged from 1.7 to 3.6 x 10(-8) M. Furthermore, a stoichiometry of 1.0 mol.mol-1 of protein was obtained for each case, indicating that all of the sites in the protein preparation were available. When beta-LG in whey protein isolate (57.4% beta-LG) was studied, a stoichiometry of 0.65 to 0.82 mol.mol-1 of protein was obtained, indicating that a large number of the sites already had bound lipid or that the protein had been denatured. As the pH was lowered toward 5.15, the affinity decreased about fourfold, but the stoichiometry of binding was unchanged. Far UV circular dichroism spectra indicated that the secondary structure of the protein was not significantly affected by ligand binding; however, the near UV spectra were changed, indicating that the flexibility of tryptophanyl residues decreased. The latter effect is consistent with the change in fluorescence quenching and suggests that a tryptophan is in the binding site. DA - 1997/6// PY - 1997/6// DO - 10.3168/jds.S0022-0302(97)76029-6 VL - 80 IS - 6 SP - 1047-1053 SN - 0022-0302 KW - beta-lactoglobulin KW - retinoid binding KW - bioselective adsorption KW - whey protein isolate ER - TY - JOUR TI - Two domains of the AL1 protein mediate geminivirus origin recognition AU - Gladfelter, HJ AU - Eagle, PA AU - Fontes, EPB AU - Batts, L AU - Hanley-Bowdoin, L T2 - VIROLOGY AB - The geminiviruses tomato golden mosaic virus (TGMV) and bean golden mosaic virus (BGMV) have bipartite genomes. Their A and B DNA components containcis-acting sequences that function as origins of replication, while their A components encode thetrans-acting replication proteins—AL1 and AL3. Earlier experiments demonstrated that virus-specific interactions between thecis- andtrans-acting functions are required for TGMV and BGMV replication and that the AL1 proteins of the two viruses specifically bind their respective origins. In the current study, characterization of AL1 and AL3 proteins produced from plant expression cassettes in transient replication assays revealed that interaction between AL1 and the origin is responsible for virus-specific replication. The AL3 protein does not contribute to specificity but can be preferred by its cognate AL1 protein when replication is impaired. Analysis of chimeric proteins showed that two regions of AL1 act as specificity determinants during replication. The first domain is located between amino acids 1 and 116 and recognizes the AL1 origin binding site. The second region, which is between amino acids 121 and 209, is not dependent on the known AL1 DNA binding site. Analysis of wild type and chimeric proteins in transient transcription assays showed that AL1 also represses its own promoter in a virus-specific manner. Transcriptional specificity is conferred primarily by AL1 amino acids 1–93 with amino acids 121–209 making a smaller contribution. Together, these results demonstrated that the virus-specific interactions of AL1 during replication and transcription are complex, involving at least two discreet domains of the protein. DA - 1997/12/8/ PY - 1997/12/8/ DO - 10.1006/viro.1997.8869 VL - 239 IS - 1 SP - 186-197 SN - 0042-6822 ER - TY - JOUR TI - Poststorage quality and rooting ability of Epipremnum pinnatum cuttings after treatment with ethylene action inhibitors AU - Muller, R AU - Serek, M AU - Sisler, EC AU - Andersen, AS T2 - JOURNAL OF HORTICULTURAL SCIENCE AB - SummaryThe influence of the ethylene action inhibitors STS and 1-MCP on poststorage performance and subsequent rooting of cuttings was investigated in Epipremnum pinnatum. Unfavourable storage conditions resulted in decreasing poststorage quality of single-eye cuttings, expressed as leaf drop and yellowing. 1-MCP and STS prohibited leaf drop and yellowing in E. pinnatum. STS pretreatment decreased rooting ability significantly, measured as percentage of rooted cuttings, number of roots, total root length and dry weight. STS caused severe injuries to the cuttings, which were worse if the cuttings were stored rather than propagated immediately. There was no significant difference in rooting between 1-MCP treated cuttings and untreated control in either stored or unstored cuttings. The influence of ethylene action inhibitors on rooting and a possible use of 1-MCP for practical use to increase poststorage performance in cuttings are discussed. DA - 1997/5// PY - 1997/5// DO - 10.1080/14620316.1997.11515532 VL - 72 IS - 3 SP - 445-452 SN - 0022-1589 ER - TY - JOUR TI - Differential effects of inhibin on gonadotropin stores and gonadotropin-releasing hormone binding to pituitary cells from cycling female rats AU - Childs, GV AU - Miller, BT AU - Miller, WL T2 - ENDOCRINOLOGY AB - Numerous studies of rat pituitaries have reported that inhibin suppresses the synthesis and release of FSH and decreases the release of LH. The latter effect seems to be related to the down-regulation of receptors for GnRH. The studies reported here identified cellular changes behind the inhibitory effects of inhibin on gonadotropes to learn whether its effects are mediated by changes in subtypes of gonadotropes. Cell populations from diestrous day 2 and proestrous (morning) rats were collected, dispersed to single cell populations, and plated in medium containing either recombinant 32-kDa inhibin or porcine follicular fluid for 24 h. GnRH binding was detected by exposing the cells to a biotinylated analog (Bio-GnRH) for 10 min before fixation, followed by avidin-peroxidase labeling protocols to detect the biotin on the analog. In parallel fields, the cells were further identified by immunolabeling for LH or FSH β-subunits or for GH with a different colored reaction product. The most striking changes were seen in cells from proestrous rats. Inhibin reduced the percentages of Bio-GnRH target cells in the population by 60% and the area and density of Bio-GnRH label on the remaining cells. Inhibin reduced the percentages of FSH cells by 30% and caused nearly a 60% reduction in the binding of Bio-GnRH by this cell type (from 83% of FSH cells to 32% of FSH cells). Inhibin also reduced the area of FSH cells and the density of FSH stores. Inhibin’s effects on LH cells were limited to a reduction in the area of the cells and the density of LH stores, but not the number of LH cells. In addition, it reduced the percentages of LH cells with Bio-GnRH receptors from 84% to 40%. When cells with GH were analyzed, inhibin had no effect on their percentages, areas, or GH stores. In populations from proestrous rats, inhibin reduced the percentages of GH cells with Bio-GnRH binding from 38% to 21%. These data suggest that inhibin’s target cell is the abundant multihormonal gonadotrope that contains LH, FSH, and GH and predominates during proestrus. Inhibin’s effects are most severe on FSH cells, which suggests that it may either selectively affect FSH synthesis and stores in bihormonal gonadotropes and/or affect monohormonal FSH cells. Thus, mechanisms behind its inhibitory effects include 1) a reduction in the percentage of Bio-GnRH target cells, 2) a reduction in the area of Bio-GnRH-binding sites on individual cells, and 3) a reduction in the stores of FSH and the percentages of FSH cells. These last effects are consistent with known reductions in FSH synthesis. The effects of inhibin on LH secretion may be secondary to the effects on Bio-GnRH receptors in bihormonal gonadotropes. DA - 1997/4// PY - 1997/4// DO - 10.1210/en.138.4.1577 VL - 138 IS - 4 SP - 1577-1584 SN - 0013-7227 ER - TY - JOUR TI - Development and characterization of a bioselective adsorption matrix for removal of Bacillus cereus spores from buffer and milk AU - Darquea, D. AU - Swaisgood, H. E. AU - Foegeding, P. M. T2 - Food Science & Technology = Lebensmittel-Wissenschaft & -Technologie AB - Bioselective adsorption was evaluated as a possible technology for food processing to enhance safety using Bacillus cereus in milk as a model system. Cataphote™ Microbeads class −400 were derivatized by attaching 3-aminopropyl groups (2.7 nm 2 /molecule) onto the surface of the bead. Carbohydrates on the Fc region of monoclonal antibody 183 against B. cereus T spores were oxidized with potassium meta-periodate to allow for an oriented antibody immobilization (270 nm 2 /molecule). The adsorption matrix was characterized for its ability to bind B. cereus spores in comparison to a control matrix containing immobilized bovine serum albumin. When 2.5 × 10 6 spores in skim milk were added to 1 mL of each matrix, the IgG-matrix was capable of removing 96% of that amount, 70% of which were bound with high affinity and were only eluted with 0.1 mol/L acetic acid. In contrast, the control matrix removed 90% of the spores added but only 7% were retained after washing the matrix. In addition, the IgG-matrix showed an excellent regeneration ability; the binding level did not decrease significantly after 28 trials with buffer or milk. Calculations determined that the bioadsorbant was capable of removing 8 × 10 6 spores/m 2 . Thus, bioselective adsorption has promise as a technology to enhance safety of liquid foods or to improve analytical methodology. DA - 1997/// PY - 1997/// DO - 10.1006/fstl.1997.0266 VL - 30 IS - 8 SP - 786-792 ER - TY - JOUR TI - Comparison of the properties of trypsin immobilized on 2 Celite(TM) derivatives AU - Huang, XL AU - Catignani, GL AU - Swaisgood, HE T2 - JOURNAL OF BIOTECHNOLOGY AB - Trypsin was immobilized on 2 Celite derivatives and the kinetic properties of trypsin immobilized on these derivatives were determined and compared. Celite was derivatized with organosilane to give aminopropyl-Celite (APC) and a portion of this derivative was then succinylated to give succinamidopropyl-Celite (SAPC). Trypsin was covalently immobilized on APC using glutaraldehyde to activate amino groups and on SAPC using water-soluble carbodiimide to activate surface carboxyl groups. Enzyme loadings were 13.9 and 17.8 mg ml-1 of beads on APC and SAPC, respectively. Using p-tosyl-L-arginine methyl ester as substrate, the catalyst specific activity, KMapp and kcat/KMapp were 17.8 U ml-1 of beads, 3.60 and 21.0 mM-1 min-1, respectively, for trypsin-APC as compared with 24.5 U ml-1 of beads, 3.77 and 20.3 mM-1 min-1, respectively, for trypsin-SAPC. With beta-lactoglobulin as substrate, KMapp and kcat/KMapp were 0.36 and 1.62 mM-1 min-1 for trypsin-APC and 0.54 and 1.39 mM-1 min-1 for trypsin-SAPC, respectively. The pH range for optimal activity was much larger for both immobilized forms as compared with the soluble enzyme. The optimal temperature ranges were 40-50 degrees C for trypsin-APC and 50-60 degrees C for trypsin-SAPC. The two methods of immobilization on Celite gave biocataysts with similar kinetic properties but immobilization on SAPC yielded slightly higher loadings and higher specific activities. DA - 1997/2/28/ PY - 1997/2/28/ DO - 10.1016/S0168-1656(96)01656-2 VL - 53 IS - 1 SP - 21-27 SN - 0168-1656 KW - immobilized trypsin KW - succinamidopropyl-Celite KW - aminopropyl-Celite KW - beta-lactoglobulin ER - TY - JOUR TI - Comparison between X ray absorption spectroscopy, anomalous wide angle X ray scattering, anomalous small angle X ray scattering, and diffraction anom AU - Bazin, D. C. AU - Sayers, D. A. AU - Rehr, J. J. T2 - Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces & Biophysical DA - 1997/// PY - 1997/// VL - 101 IS - 51 SP - 11040-11050 ER - TY - JOUR TI - Asparaginase associated lipid abnormalities in children with acute lymphoblastic leukemia AU - Parsons, S. K. AU - Skapek, S. X. AU - Neufeld, E. J. AU - Kuhlman, C. AU - Young, M. L. AU - Donnelly, M. AU - Brunzell, J. D. AU - Otvos, James D. AU - Sallan, S. E. AU - Rifai, N. T2 - Blood DA - 1997/// PY - 1997/// VL - 89 IS - 6 SP - 1886-1895 ER - TY - JOUR TI - Purification, characterization, and expression of rat epididymal beta-D-galactosidase AU - Hall, J. C. AU - Jacobetz, D. R. AU - LaMarche, M. D. AU - Kochins, J. G. AU - Tubbs, C. E. T2 - Biochemistry and Molecular Biology International DA - 1997/// PY - 1997/// VL - 42 IS - 3 SP - 443-451 ER - TY - JOUR TI - Inhibitors of ethylene responses in plants at the receptor level: recent developments AU - Sisler, E. C. AU - Serek, M. T2 - Physiologia Plantarum DA - 1997/// PY - 1997/// DO - 10.1034/j.1399-3054.1997.1000320.x VL - 100 IS - 3 SP - 577-582 ER - TY - JOUR TI - Diffraction enhanced X-ray imaging AU - Chapman, D. AU - Thomlinson, W. AU - Johnston, R. E. AU - Washburn, D. AU - Pisano, E. AU - Gmur, N. AU - Zhong, Z. AU - Menk, R. AU - Arfelli, F. AU - Sayers, D. E. T2 - Physics in Medicine & Biology DA - 1997/// PY - 1997/// VL - 42 IS - 11 SP - 2015-2025 ER - TY - JOUR TI - Sustainable solution for dietary iron deficiency through plant biotechnology and breeding to increase seed ferritin control AU - Theil, E. C. AU - Burton, J. W. AU - Beard, J. L. T2 - European Journal of Clinical Nutrition DA - 1997/// PY - 1997/// VL - 51 IS - Suppl. 4 SP - S28-31 ER - TY - JOUR TI - Rapid and parallel formation of Fe3+ multimers, including a trimer, during H-type subunit ferritin mineralization AU - Pereira, AS AU - Tavares, P AU - Lloyd, SG AU - Danger, D AU - Edmondson, DE AU - Theil, EC AU - Huynh, BH T2 - BIOCHEMISTRY AB - Conversion of Fe ions in solution to the solid phase in ferritin concentrates iron required for cell function. The rate of the Fe phase transition in ferritin is tissue specific and reflects the differential expression of two classes of ferritin subunits (H and L). Early stages of mineralization were probed by rapid freeze-quench Mossbauer, at strong fields (up to 8 T), and EPR spectroscopy in an H-type subunit, recombinant frog ferritin; small numbers of Fe (36 moles/mol of protein) were used to increase Fe3+ in mineral precursor forms. At 25 ms, four Fe3+-oxy species (three Fe dimers and one Fe trimer) were identified. These Fe3+-oxy species were found to form at similar rates and decay subsequently to a distinctive superparamagentic species designated the "young core." The rate of oxidation of Fe2+ (1026 s(-1)) corresponded well to the formation constant for the Fe3+-tyrosinate complex (920 s(-1)) observed previously [Waldo, G. S., & Theil, E. C. (1993) Biochemistry 32, 13261] and, coupled with EPR data, indicates that several or possibly all of the Fe3+-oxy species involve tyrosine. The results, combined with previous Mossbauer studies of Y30F human H-type ferritin which showed decreases in several Fe3+ intermediates and stabilization of Fe2+ [Bauminger, E. R., et al. (1993) Biochem. J. 296, 709], emphasize the involvement of tyrosyl residues in the mineralization of H-type ferritins. The subsequent decay of these multiple Fe3+-oxy species to the superparamagnetic mineral suggests that Fe3+ species in different environments may be translocated as intact units from the protein shell into the ferritin cavity where the conversion to a solid mineral occurs. DA - 1997/6/24/ PY - 1997/6/24/ DO - 10.1021/bi970348f VL - 36 IS - 25 SP - 7917-7927 SN - 0006-2960 ER - TY - JOUR TI - Identification of specific nucleotide sequences and structural elements required for intronic U14 snorna processing AU - Xia, L. AU - Watkins, N. J. AU - Maxwell, E. S. T2 - RNA DA - 1997/// PY - 1997/// VL - 3 IS - 1 SP - 17-26 ER - TY - JOUR TI - Abnormal lignin in a loblolly pine mutant AU - Ralph, J AU - MacKay, JJ AU - Hatfield, RD AU - OMalley, DM AU - Whetten, RW AU - Sederoff, RR T2 - SCIENCE AB - Novel lignin is formed in a mutant loblolly pine (Pinus taeda L.) severely depleted in cinnamyl alcohol dehydrogenase (E.C. 1.1.1.195), which converts coniferaldehyde to coniferyl alcohol, the primary lignin precursor in pines. Dihydroconiferyl alcohol, a monomer not normally associated with the lignin biosynthetic pathway, is the major component of the mutant's lignin, accounting for approximately 30 percent (versus approximately 3 percent in normal pine) of the units. The level of aldehydes, including new 2-methoxybenzaldehydes, is also increased. The mutant pines grew normally indicating that, even within a species, extensive variations in lignin composition need not disrupt the essential functions of lignin. DA - 1997/7/11/ PY - 1997/7/11/ DO - 10.1126/science.277.5323.235 VL - 277 IS - 5323 SP - 235-239 SN - 1095-9203 ER - TY - JOUR TI - The formation of intramolecular disulfide bridges is required for induction of the Sindbis virus mutant TS23 phenotype AU - Carleton, M. AU - Brown, D. T. T2 - Journal of Virology DA - 1997/// PY - 1997/// VL - 71 IS - 10 SP - 7696-7703 ER - TY - JOUR TI - Nucleotide sequence of porcine OTCase cDNA AU - Koger, J. B. AU - Jones, E. E. T2 - Journal of Animal Science AB - Journal Article Rapid Communication: Nucleotide sequence of porcine OTCase cDNA Get access Jeanne B. Koger, Jeanne B. Koger 1Department of Animal Science, North Carolina State University, Raleigh 27695-7621, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Evan E. Jones Evan E. Jones 1Department of Animal Science, North Carolina State University, Raleigh 27695-7621, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 75, Issue 12, December 1997, Page 3368, https://doi.org/10.2527/1997.75123368x Published: 01 December 1997 Article history Received: 13 May 1997 Accepted: 29 August 1997 Published: 01 December 1997 DA - 1997/// PY - 1997/// DO - 10.2527/1997.75123368x VL - 75 IS - 12 SP - 3368 ER - TY - JOUR TI - Functional domains of a geminivirus replication protein AU - Orozco, B. M. AU - Miller, A. B. AU - Settlage, S. B. AU - Hanley-Bowdoin, Linda T2 - Journal of Biological Chemistry AB - Tomato golden mosaic virus, a member of the geminivirus family, has a single-stranded DNA genome that is replicated and transcribed in infected plant cells through the concerted action of viral and host factors. One viral protein, AL1, contributes to both processes by binding to a directly repeated, double-stranded DNA sequence located in the overlapping (+) strand origin of replication and AL1 promoter. The AL1 protein, which occurs as a multimeric complex in solution, also catalyzes DNA cleavage during initiation of rolling circle replication. To identify the tomato golden mosaic virus AL1 domains that mediate protein oligomerization, DNA binding, and DNA cleavage, a series of truncated AL1 proteins were produced in a baculovirus expression system and assayed for each activity. These experiments localized the AL1 oligomerization domain between amino acids 121 and 181, the DNA binding domain between amino acids 1 and 181, and the DNA cleavage domain between amino acids 1 and 120. Deletion of the first 29 amino acids of AL1 abolished DNA binding and DNA cleavage, demonstrating that an intact N terminus is required for both activities. The observation that the DNA binding domain includes the oligomerization domain suggested that AL1-AL1 protein interaction may be a prerequisite for DNA binding but not for DNA cleavage. The significance of these results for AL1 function during geminivirus replication and transcription is discussed. Tomato golden mosaic virus, a member of the geminivirus family, has a single-stranded DNA genome that is replicated and transcribed in infected plant cells through the concerted action of viral and host factors. One viral protein, AL1, contributes to both processes by binding to a directly repeated, double-stranded DNA sequence located in the overlapping (+) strand origin of replication and AL1 promoter. The AL1 protein, which occurs as a multimeric complex in solution, also catalyzes DNA cleavage during initiation of rolling circle replication. To identify the tomato golden mosaic virus AL1 domains that mediate protein oligomerization, DNA binding, and DNA cleavage, a series of truncated AL1 proteins were produced in a baculovirus expression system and assayed for each activity. These experiments localized the AL1 oligomerization domain between amino acids 121 and 181, the DNA binding domain between amino acids 1 and 181, and the DNA cleavage domain between amino acids 1 and 120. Deletion of the first 29 amino acids of AL1 abolished DNA binding and DNA cleavage, demonstrating that an intact N terminus is required for both activities. The observation that the DNA binding domain includes the oligomerization domain suggested that AL1-AL1 protein interaction may be a prerequisite for DNA binding but not for DNA cleavage. The significance of these results for AL1 function during geminivirus replication and transcription is discussed. DA - 1997/// PY - 1997/// DO - 10.1074/jbc.272.15.9840 VL - 272 IS - 15 SP - 9840–9846 ER - TY - JOUR TI - Structure and stability of cobalt-silicon-germanium thin films AU - Goeller, PT AU - Boyanov, BI AU - Sayers, DE AU - Nemanich, RJ T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - The phase formation and stability of CoSi2 on strained epitaxial Si0.80Ge0.20Si (0 0 1) thin films has been investigated. Silicide films prepared via direct deposition of cobalt (CoSiGe), and via co-deposition of silicon and cobalt (Co+2SiSiGe), were compared. EXAFS, XRD, and sheet-resistance measurements indicated that co-deposited Co+2Si films annealed at 400–700°C exhibit the expected low-resistivity CoSi2 structure but were susceptible to roughening, pinhole formation, and agglomeration. In contrast, the CoSiGe structure formed CoSi2 only after annealing at 700°C and silicide formation was accompanied by Ge segregation in the contact region. In situ RHEED experiments indicated that growth of CoSi2 co-deposited on SiGe at 400–500°C results in immediate island formation. Template methods, which are often used to enhance the quality of co-deposited Co+2SiSi structures, did not lead to two-dimensional growth in the Co+2SiSiGe system. In situ EXAFS measurements of 2 Å Co films deposited on SiGe substrates and annealed at 450°C suggested that the failure to achieve two-dimensional growth may be due to preferential bonding of Co to Si atoms at the interface, which prevents the formation of a continuous CoSi2 template. DA - 1997/12// PY - 1997/12// DO - 10.1016/S0168-583X(97)00458-8 VL - 133 IS - 1-4 SP - 84-89 SN - 0168-583X KW - cobalt silicide KW - silicon-germanium alloys KW - metal-semiconductor contacts KW - molecular beam epitaxy ER - TY - JOUR TI - Preferential Co-SI bonding at the Co/SiGe(100) interface AU - Boyanov, B. I. AU - Goeller, P. T. AU - Sayers, D. E. AU - Nemanich, R. J. T2 - Applied Physics Letters AB - The initial stages of the reaction of Co with Si0.79Ge0.21(100) were studied in situ with extended x-ray absorption fine structure spectroscopy and reflection high energy electron diffraction. The Si:Ge ratio in the first coordination shell of Co in sub-monolayer Co films was found to increase with film thickness and annealing temperature, indicating preferential formation of Co–Si bonds. The impact of the observed preference for Co–Si bonding on the morphology of epitaxial CoSi2/Si1−xGex heterostructures is discussed. DA - 1997/// PY - 1997/// DO - 10.1063/1.119436 VL - 71 IS - 21 SP - 3060-3062 ER -