@article{sommer_estrada_collins_bedell_alexander_yang_hughes_mir_gilger_grob_et al._2011, title={Production of ELOVL4 transgenic pigs: a large animal model for Stargardt-like macular degeneration}, volume={95}, ISSN={0007-1161}, url={http://dx.doi.org/10.1136/bjophthalmol-2011-300417}, DOI={10.1136/bjophthalmol-2011-300417}, abstractNote={Background Truncation mutations in the elongation of very long chain fatty acids-4 (AF277094, MIM #605512) (ELOVL4) gene cause Stargardt-like macular dystrophy type 3 (STGD3). Mice expressing truncated ELOVL4 develop rapid retinal degeneration, but are poor STGD3 models since mice lack a macula. Photoreceptor topography in the pig retina is more similar to that in humans as it includes the cone rich, macula-like area centralis. The authors generated transgenic pigs expressing human disease-causing ELOVL4 mutations to better model the pathobiology of this macular disease. Methods Pronuclear DNA microinjection and somatic cell nuclear transfer were used to produce transgenic pigs for two different ELOVL4 mutations: the 5 base pair deletion (5 bpdel) and the 270 stop mutation (Y270terEYFP). Retinal transgene expression, morphology and electrophysiology were examined. Results The authors obtained four lines of Y270terEYFP and one line of 5 bpdel transgenic animals. Direct fluorescence microscopy indicated that the Y270terEYFP protein is expressed in photoreceptors and mislocalised within the cell. Immunohistochemical examination of transgenic pigs showed photoreceptor loss and disorganised inner and outer segments. Electroretinography demonstrated diminished responses in both transgenic models. Conclusions These transgenic pigs provide unique animal models for examining macular degeneration and STGD3 pathogenesis.}, number={12}, journal={British Journal of Ophthalmology}, publisher={BMJ}, author={Sommer, J. R. and Estrada, J. L. and Collins, E. B. and Bedell, M. and Alexander, C. A. and Yang, Z. and Hughes, G. and Mir, B. and Gilger, B. C. and Grob, S. and et al.}, year={2011}, month={Aug}, pages={1749–1754} }
 @article{zaunbrecher_mir_dunne_breen_piedrahita_2008, title={Enhancement of extra chromosomal recombination in somatic cells by affecting the ratio of homologous recombination (HR) to non-homologous end joining (NHEJ)}, volume={19}, ISSN={["1532-2378"]}, DOI={10.1080/10495390701670099}, abstractNote={Advancements in somatic cell gene targeting have been slow due to the finite lifespan of somatic cells and the overall inefficiency of homologous recombination. The rate of homologous recombination is determined by mechanisms of DNA repair, and by the balance between homologous recombination (HR) and non-homologous end joining (NHEJ). A plasmid-to-plasmid, extra chromosomal recombination system was used to study the effects of the manipulation of molecules involved in NHEJ (Mre11, Ku70/80, and p53) on HR/NHEJ ratios. In addition, the effect of telomerase expression, cell synchrony, and DNA nuclear delivery was examined. While a mutant Mre11 and an anti-Ku aptamer did not significantly affect the rate of NHEJ or HR, transient expression of a p53 mutant increased overall HR/NHEJ by 2.5 fold. However, expression of the mutant p53 resulted in increased aneuploidy of the cultured cells. Additionally, we found no relationship between telomerase expression and changes in HR/NHEJ. In contrast, cell synchrony by thymidine incorporation did not induce chromosomal abnormalities, and increased the ratio of HR/NHEJ 5-fold by reducing the overall rate of NHEJ. Overall our results show that attempts at reducing NHEJ by use of Mre11 or anti-Ku aptamers were unsuccessful. Cell synchrony via thymidine incorporation, however, does increase the ratio of HR/NHEJ and this indicates that this approach may be of use to facilitate targeting in somatic cells by reducing the numbers of colonies that need to be analyzed before a HR is identified.}, number={1}, journal={ANIMAL BIOTECHNOLOGY}, author={Zaunbrecher, Gretchen M. and Mir, Bashir and Dunne, Patrick W. and Breen, Matthew and Piedrahita, Jorge A.}, year={2008}, pages={6–21} }
 @article{estrada_sommer_collins_mir_martin_york_petters_piedrahita_2007, title={Swine generated by somatic cell nuclear transfer have increased incidence of intrauterine growth restriction (IUGR)}, volume={9}, ISSN={["1536-2302"]}, DOI={10.1089/clo.2006.0079}, abstractNote={While somatic cell nuclear transfer (SCNT) has been successful in several species, many pregnancies are lost and anomalies are found in fetal and perinatal stages. In this study SCNT and artificial inseminations (AI) populations were compared for litter size, average birth weight, piglets alive at birth, stillborn, mummies, dead at the first week, intrauterine growth restriction (IUGR) and large for gestational age (LGA). Twenty-three SCNT litters (143 individuals) were compared to 112 AI litters (1300 individuals). Litter size average was 11.5 for AI and 6.2 for SCNT. Litter weight and average birth weight adjusted by litter size were significantly (p < 0.05) higher in AI than in SCNT litters. The SCNT population had a significant (p < 0.01) increase in the number of IUGRs per litter with LSmeans 7.2 +/- 1.4 versus 19.4 +/- 3.5 and means 8.0 +/- 10.8 versus 15.5 +/- 24.5 for AI and SCNT, respectively. Additionally, there was a trend for higher postnatal mortality and stillbirths in the SCNT population. These findings demonstrate that there are some differences between SCNT-derived and AI litters. SCNT-derived pigs are excellent models to study epigenetic factors and genes involved in IUGRs, and to develop effective means to improve fetal growth in humans and animals.}, number={2}, journal={CLONING AND STEM CELLS}, author={Estrada, Jose and Sommer, Jeffrey and Collins, Bruce and Mir, Bashir and Martin, Amy and York, Abby and Petters, Robert M. and Piedrahita, Jorge A.}, year={2007}, pages={229–236} }
 @article{tsai_mir_martin_estrada_bischoff_hsieh_cassady_freking_nonneman_rohrer_et al._2006, title={Detection of transcriptional difference of porcine imprinted genes using different microarray platforms}, volume={7}, journal={BMC Genomics}, author={Tsai, S. and Mir, B. and Martin, A. C. and Estrada, J. L. and Bischoff, S. R. and Hsieh, W. P. and Cassady, J. P. and Freking, B. A. and Nonneman, D. J. and Rohrer, G. A. and et al.}, year={2006} }
 @article{mir_zaunbrecher_archer_friend_piedrahita_2005, title={Progeny of somatic cell nuclear transfer (SCNT) pig clones are phenotypically similar to non-cloned pigs}, volume={7}, ISSN={["1536-2302"]}, DOI={10.1089/clo.2005.7.119}, abstractNote={Systematic studies of cloned animals generated from adult somatic cell nuclei are critical in assessing the utility of somatic cell cloning in various applications, including the safety of food products from cloned animals and their offspring. Previously, we compared somatic cell derived cloned pigs with naturally bred control pigs on a series of physiological and genetic parameters. We have extended our studies to the F1 progeny of these clones to see whether these phenotypic differences are transmitted to the next generation. There were no differences in the average litter size between litters from cloned gilts and naturally bred controls (7.78 +/- 2.6 and 7.40 +/- 3.0, respectively; mean +/- SD) or in the degree of litter size variation (coefficients of variation of 33.4% and 40.5% for litters of clones and controls, respectively). Similarly there were no statistical differences between sex ratios of cloned litters (51-49%, M:F) and control litters (59-41%, M:F). Blood profiles between cloned pigs, control pigs, and their progeny were compared at two time points (i.e., 15 and 27 weeks) to quantify the effect of cloning on various blood parameters and their transmission to the next generation. Although the range of values for all traits overlapped between different classes, the variability between all the traits in F1 progeny of clones and the control pigs was similar at 15 and 27 weeks, with one exception. Combined, our data and previous results in mice strongly support the hypothesis that offspring of clones are similar to offspring of naturally bred animals, and as such there should not be any increased risks associated with consumption of products from these animals.}, number={2}, journal={CLONING AND STEM CELLS}, author={Mir, B and Zaunbrecher, G and Archer, GS and Friend, TH and Piedrahita, JA}, year={2005}, pages={119–125} }
 @article{piedrahita_mir_2004, title={Cloning and transgenesis in mammals: Implications for xenotransplantation}, volume={4}, ISSN={["1600-6143"]}, DOI={10.1111/j.1600-6135.2004.0344.x}, abstractNote={Availability of suitable organs for transplantation remains of major concern and projections indicate that the problem will continue to increase. Therefore, alternatives to the use of human organs for transplantation, continue to be explored including use of stem cells, artificial organs, and organs from other species (xenotransplantation). In xenotransplantation, the species of choice remains the pig due to its physiological similarities to humans, reduced costs, ease of manipulation, and reduced ethical concerns to its use. However, in order to develop pig organs that are suitable for xenotransplantation, complex genetic modification need to be undertaken. These modifications require the introduction of precise genetic changes into the pig that can only be accomplished at this time using somatic cell nuclear transfer. We cover in this review advances in transgenic manipulation and cloning in swine and how the development of these two technologies is critical to the eventual utilization of the pig as a human organ donor.}, journal={AMERICAN JOURNAL OF TRANSPLANTATION}, author={Piedrahita, JA and Mir, B}, year={2004}, month={Feb}, pages={43–50} }
 @article{mir_piedrahita_2004, title={Nuclear localization signal and cell synchrony enhance gene targeting efficiency in primary fetal fibroblasts}, volume={32}, number={3}, journal={Nucleic Acids Research}, author={Mir, B. and Piedrahita, J. A.}, year={2004} }
 @article{piedrahita_mir_dindot_walker_2004, title={Somatic cell cloning: The ultimate form of nuclear reprogramming?}, volume={15}, ISSN={["1046-6673"]}, DOI={10.1097/01.ASN.0000110183.87476.05}, abstractNote={With the increasing difficulties associated with meeting the required needs for organs used in transplantation, alternative approaches need to be considered. These include the use of stem cells as potential sources of specialized cells, the ability to transdifferentiate cell types in culture, and the development of complete organs that can be used in humans. All of the above goals will require a complete understanding of the factors affecting cell differentiation and nuclear reprogramming. To make this a reality, however, techniques associated with cloning and genetic modifications in somatic cells need to be continued to be developed and optimized. This includes not only an enhancement of the rate of homologous recombination in somatic cells, but also a thorough understanding of the nuclear reprogramming process taking place during nuclear transfer. The understanding of this process is likely to have an effect beyond the area of nuclear transfer and assist with better methods for transdifferentiation of mammalian cells.}, number={5}, journal={JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY}, author={Piedrahita, JA and Mir, B and Dindot, S and Walker, S}, year={2004}, month={May}, pages={1140–1144} }
 @article{mir_tanner_chowdhary_piedrahita_2003, title={UP1 extends life of primary porcine fetal fibroblasts in culture}, volume={5}, ISSN={["1536-2302"]}, DOI={10.1089/153623003322234740}, abstractNote={Genetic modification of somatic cell nuclei and subsequent nuclear transfer has opened an opportunity to create gene-targeted animals. However, somatic cells have a limited life span in culture and it is not possible to introduce precise genetic changes in both alleles in this narrow time window. To increase the life span of somatic cell in culture, both genetic and chemical approaches have been tried with varying success. Here, we report the effect of two anti-oxidants, glutathione and n-t-butyl hydroxylamine, and of the expression of UP1, a shortened derivative of heterogeneous nuclear riboprotein (hnRNP)A1, on the life extension of primary porcine fibroblasts in culture. Under our experimental conditions, the use of anti-oxidants did not result in any prolongation of the life span. In contrast, UP1 expression increased the life span significantly. While most control cells stopped growing by PDL 20, and none survived beyond PDL 35, 100% of UP1-expressing clones reached PDL50, and 40% made it to PDL65. The five UP1-expressing clones were karyotyped at PDL 50. While all of them had a range of numerical chromosomal abnormalities, two clones retained 30-40% normal cells, all the cells in other three clones had abnormal chromosome numbers. Thus, expression of UP1 may be useful in extending the life span of somatic cells in culture. This, in turn, will facilitate the process of gene targeting in this cell type.}, number={2}, journal={CLONING AND STEM CELLS}, author={Mir, B and Tanner, N and Chowdhary, BP and Piedrahita, JA}, year={2003}, pages={143–148} }