@article{leblanc_wang_holmes_kwon_medlock_2013, title={A Transgenerational Endocrine Signaling Pathway in Crustacea}, volume={8}, ISSN={1932-6203}, url={http://dx.doi.org/10.1371/journal.pone.0061715}, DOI={10.1371/journal.pone.0061715}, abstractNote={Background Environmental signals to maternal organisms can result in developmental alterations in progeny. One such example is environmental sex determination in Branchiopod crustaceans. We previously demonstrated that the hormone methyl farnesoate could orchestrate environmental sex determination in the early embryo to the male phenotype. Presently, we identify a transcription factor that is activated by methyl farnesoate and explore the extent and significance of this transgenerational signaling pathway. Methodology/Principal Findings Several candidate transcription factors were cloned from the water flea Daphnia pulex and evaluated for activation by methyl farnesoate. One of the factors evaluated, the complex of two bHLH-PAS proteins, dappuMet and SRC, activated a reporter gene in response to methyl farnesoate. Several juvenoid compounds were definitively evaluated for their ability to activate this receptor complex (methyl farnesoate receptor, MfR) in vitro and stimulate male sex determination in vivo. Potency to activate the MfR correlated to potency to stimulate male sex determination of offspring (pyriproxyfen>methyl farnesoate>methoprene, kinoprene). Daphnids were exposed to concentrations of pyriproxyfen and physiologic responses determined over multiple generations. Survivial, growth, and sex of maternal organisms were not affected by pyriproxyfen exposure. Sex ratio among offspring (generation 2) were increasingly skewed in favor of males with increasing pyriproxyfen concentration; while, the number of offspring per brood was progressively reduced. Female generation 2 daphnids were reared to reproductive maturity in the absence of pyriproxyfen. Sex ratios of offspring (generation 3) were not affected in this pyriproxyfen lineage, however, the number of offspring per brood, again, was significantly reduced. Conclusions Results reveal likely components to a hormone/receptor signaling pathway in a crustacean that orchestrates transgenerational modifications to important population metrics (sex ratios, fecundity of females). A model is provided that describes how these signaling processes can facilitate population sustainability under normal conditions or threaten sustainability when perturbed by environmental chemicals.}, number={4}, journal={PLoS ONE}, publisher={Public Library of Science (PLoS)}, author={LeBlanc, Gerald A. and Wang, Ying H. and Holmes, Charisse N. and Kwon, Gwijun and Medlock, Elizabeth K.}, editor={He, BinEditor}, year={2013}, month={Apr}, pages={e61715} }
 @article{hannas_wang_thomson_kwon_li_leblanc_2011, title={Regulation and dysregulation of vitellogenin mRNA accumulation in daphnids (Daphnia magna)}, volume={101}, ISSN={["1879-1514"]}, DOI={10.1016/j.aquatox.2010.11.006}, abstractNote={The induction of vitellogenin in oviparous vertebrates has become the gold standard biomarker of exposure to estrogenic chemicals in the environment. This biomarker of estrogen exposure also has been used in arthropods, however, little is known of the factors that regulate the expression of vitellogenin in these organisms. We investigated changes in accumulation of mRNA products of the vitellogenin gene Vtg2 in daphnids (Daphnia magna) exposed to a diverse array of chemicals. We further evaluated the involvement of hormonal factors in the regulation of vitellogenin expression that may be targets of xenobiotic chemicals. Expression of the Vtg2 gene was highly responsive to exposure to various chemicals with an expression range spanning approximately four orders of magnitude. Chemicals causing the greatest induction were piperonyl butoxide, chlordane, 4-nonylphenol, cadmium, and chloroform. Among these, only 4-nonylphenol is recognized to be estrogenic. Exposure to several chemicals also suppressed Vtg2 mRNA levels, as much as 100-fold. Suppressive chemicals included cyproterone acetate, acetone, triclosan, and atrazine. Exposure to the estrogens diethylstilbestrol and bisphenol A had little effect on vitellogenin mRNA levels further substantiating that these genes are not induced by estrogen exposure. Exposure to the potent ecdysteroids 20-hydroxyecdysone and ponasterone A revealed that Vtg2 was subject to strong suppressive control by these hormones. Vtg2 mRNA levels were not significantly affected from exposure to several juvenoid hormones. Results indicate that ecdysteroids are suppressors of vitellogenin gene expression and that vitellogenin mRNA levels can be elevated or suppressed in daphnids by xenobiotics that elicit antiecdysteroidal or ecdysteroidal activity, respectively. Importantly, daphnid Vtg2 is not elevated in response to estrogenic activity.}, number={2}, journal={AQUATIC TOXICOLOGY}, author={Hannas, Bethany R. and Wang, Ying H. and Thomson, Susanne and Kwon, Gwijun and Li, Hong and LeBlanc, Gerald A.}, year={2011}, month={Jan}, pages={351–357} }
 @article{wang_kwon_li_leblanc_2011, title={Tributyltin Synergizes with 20-Hydroxyecdysone to Produce Endocrine Toxicity}, volume={123}, ISSN={["1096-0929"]}, DOI={10.1093/toxsci/kfr154}, abstractNote={One of the great challenges facing modern toxicology is in predicting the hazard associated with chemical mixtures. The development of effective means of predicting the toxicity of chemical mixtures requires an understanding of how chemicals interact to produce nonadditive outcomes (e.g., synergy). We hypothesized that tributyltin would elicit toxicity in daphnids (Daphnia magna) by exaggerating physiological responses to 20-hydroxyecdysone signaling via synergistic activation of the retinoid X receptor (RXR):ecdysteroid receptor (EcR) complex. Using reporter gene assays, we demonstrated that RXR, alone, is activated by a variety of ligands including tributyltin, whereas RXR:EcR heterodimers were not activated by tributyltin. However, tributyltin, in combination with the daphnid EcR ligand 20-hydroxyecdysone, caused concentration-dependent, synergistic activation of the RXR:EcR reporter. Electrophoretic mobility shift assays revealed that tributyltin did not enhance the activity of 20-hydroxyecdysone by increasing binding of the receptor complex to a DR-4 DNA-binding site. Exposure of daphnids to elevated concentrations of 20-hydroxyecdysone caused premature and incomplete ecdysis resulting in death. Tributyltin exaggerated this effect of exogenous 20-hydroxyecdysone. Further, exposure of daphnids to tributyltin enhanced the inductive effects of 20-hydroxyecdysone on expression of the 20-hydroxyecdysone-inducible gene HR3. Continuous, prolonged exposure of maternal daphnids to concentrations of tributyltin resulted in mortality concurrent with molting. Taken together, these results demonstrate that xenobiotics, such as tributyltin, can interact with RXR to influence gene expression regulated by the heterodimeric partner to RXR. The result of such interactions can be toxicity due to inappropriate or exaggerated hormonal signaling. The application of the in vitro/in vivo approach used in this study is discussed in relation to modeling of nonadditive interactions among constituents of chemical mixtures.}, number={1}, journal={TOXICOLOGICAL SCIENCES}, author={Wang, Ying H. and Kwon, Gwijun and Li, Hong and LeBlanc, Gerald A.}, year={2011}, month={Sep}, pages={71–79} }
 @article{hannas_wang_baldwin_li_wallace_leblanc_2010, title={Interactions of the crustacean nuclear receptors HR3 and E75 in the regulation of gene transcription}, volume={167}, ISSN={["1095-6840"]}, DOI={10.1016/j.ygcen.2010.03.025}, abstractNote={Endocrine signal transduction occurs through cascades that involve the action of both ligand-dependent and ligand-independent nuclear receptors. In insects, two such nuclear receptors are HR3 and E75 that interact to transduce signals initiated by ecdysteroids. We have cloned these nuclear receptors from the crustacean Daphnia pulex to assess their function as regulators of gene transcription in this ecologically and economically important group of organisms. Both nuclear receptors from D. pulex (DappuHR3 (group NR1F) and DappuE75 (group NR1D)) exhibit a high degree of sequence similarity to other NR1F and NR1D group members that is indicative of monomeric binding to the RORE (retinoid orphan receptor element). DappuE75 possesses key amino acid residues required for heme binding to the ligand-binding domain. Next, we developed a gene transcription reporter assay containing a luciferase reporter gene driven by the RORE. DappuHR3, but not DappuE75, activated transcription of the luciferase gene in this system. Co-transfection experiments revealed that DappuE75 suppressed DappuHR3-dependent luciferase transcription in a dose-dependent manner. Electrophoretic mobility shift assays confirmed that DappuHR3 bound to the RORE. However, we found no evidence that DappuE75 similarly bound to the response element. These experiments further demonstrated that DappuE75 prevented DappuHR3 from binding to the response element. In conclusion, DappuHR3 functions as a transcriptional activator of genes regulated by the RORE and DappuE75 is a negative regulator of this activity. DappuE75 does not suppress the action of DappuHR3 by occupying the response element but presumably interacts directly with the DappuHR3 protein. Taken together with the previous demonstration that daphnid HR3 is highly induced by 20-hydroxyecdysone, these results support the premise that HR3 is a major component of ecdysteroid signaling in some crustaceans and is under the negative regulatory control of E75.}, number={2}, journal={GENERAL AND COMPARATIVE ENDOCRINOLOGY}, author={Hannas, Bethany R. and Wang, Ying H. and Baldwin, William S. and Li, Yangchun and Wallace, Andrew D. and LeBlanc, Gerald A.}, year={2010}, month={Jun}, pages={268–278} }
 @article{thomson_baldwin_wang_kwon_leblanc_2009, title={Annotation, phylogenetics, and expression of the nuclear receptors in Daphnia pulex}, volume={10}, journal={BMC Genomics}, author={Thomson, S. A. and Baldwin, W. S. and Wang, Y. H. and Kwon, G. and LeBlanc, G. A.}, year={2009} }
 @article{wang_leblanc_2009, title={Interactions of methyl farnesoate and related compounds with a crustacean retinoid X receptor}, volume={309}, ISSN={0303-7207}, url={http://dx.doi.org/10.1016/j.mce.2009.05.016}, DOI={10.1016/j.mce.2009.05.016}, abstractNote={While a functional role for the sesquiterpenoid hormone methyl farnesoate in arthropods has been recognized for decades, the identification of a receptor that mediates the action of this hormone remains equivocal. Luciferase reporter assays were used in the present study to evaluate the ability of methyl farnesoate and other putative ligands to activate gene transcription associated with the retinoid X receptor (RXR) and RXR:EcR heterodimeric complexes from the crustacean (Daphnia magna). The daphnid RXR constructs, transfected into HepG2 cells along with the reporter construct, significantly activated luciferase gene expression in response to tributyltin indicating that the crustacean RXR is indeed ligand activated. However, RXR was not activated by methyl farnesoate or other putative RXR ligands. Cells co-transfected with the daphnid RXR and EcR produced luciferase in response to ecdysteroids and this activation was significantly enhanced when cells were also provided either methyl farnesoate or other putative RXR ligands. This synergy among RXR and EcR ligands was not dependent upon the co-activator SRC-1 and did not correlate to a physiological response of daphnids to juvenoid hormones (male sex determination). Results indicate that methyl farnesoate, along with compounds that are functionally similar to methyl farnesoate synergize with ecdysteroids to activate the RXR:EcR receptor complex. However, this effect appears to be unrelated to the ability of these compounds to stimulate male sex determination.}, number={1-2}, journal={Molecular and Cellular Endocrinology}, publisher={Elsevier BV}, author={Wang, Ying H. and LeBlanc, Gerald A.}, year={2009}, month={Oct}, pages={109–116} }
 @article{zhang_fang_wang_2008, title={A new tunnel function method for global optimization}, volume={4}, number={1}, journal={Pacific Journal of Optimization}, author={Zhang, L. S. and Fang, S. C. and Wang, Y.}, year={2008}, pages={125–138} }
 @article{wang_wang_leblanc_2007, title={Cloning and characterization of the retinoid X receptor from a primitive crustacean Daphnia magna}, volume={150}, ISSN={["0016-6480"]}, DOI={10.1016/j.ygcen.2006.08.002}, abstractNote={Terpenoid hormones function as morphogens throughout the animal kingdom and many of these activities are mediated through members of the retinoid X group of nuclear receptors (RXR; NR2B). In the present study, RXR was cloned from the water flea Daphnia magna, a primitive crustacean of the class Branchiopoda, and characterized with respect to phylogeny, developmental expression, and hormonal regulation. The full length daphnid RXR cDNA was cloned by initial PCR amplification of a cDNA fragment from the highly conserved DNA-binding domain followed by extension of the fragment using RACE PCR. The full length cDNA was 1888 base pairs in length and coded for a 400 amino acid protein that exhibited the five-domain structure of a nuclear receptor superfamily member. The RXR protein shared significant identity with other NR2B group members. Phylogenetic analyses of the ligand-binding domain of the receptor revealed that daphnid RXR clustered with RXR from decapod crustaceans on a branch of the phylogenetic tree that was distinct from RXRs known to bind retinoic acids and juvenile hormones. Daphnid RXR mRNA levels were greatest in embryos that were early in development and progressively declined through the initial five stages of embryo development. Adult females expressed higher levels of RXR mRNA than did males and exposure of females to the terpenoid mimic pyriproxyfen reduced RXR mRNA to levels approaching levels in males. RXR mRNA levels in males were refractory to pyriproxyfen. These results show that branchiopod crustaceans dynamically express RXR which should be evaluated as a candidate receptor for the terpenoid hormone methyl farnesoate which functions as a sex determinant in these organisms.}, number={2}, journal={GENERAL AND COMPARATIVE ENDOCRINOLOGY}, author={Wang, Ying H. and Wang, Guirong and LeBlanc, Gerald A.}, year={2007}, month={Jan}, pages={309–318} }
 @article{hobolth_nielsen_wang_wu_tanksley_2006, title={CpG plus CpNpG analysis of protein-coding sequences from tomato}, volume={23}, ISSN={["1537-1719"]}, DOI={10.1093/molbev/msk017}, abstractNote={We develop codon-based models for simultaneously inferring the mutational effects of CpG and CpNpG methylation in coding regions. In a data set of 369 tomato genes, we show that there is very little effect of CpNpG methylation but a strong effect of CpG methylation affecting almost all genes. We further show that the CpNpG and CpG effects are largely uncorrelated. Our results suggest different roles of CpG and CpNpG methylation, with CpNpG methylation possibly playing a specialized role in defense against transposons and RNA viruses.}, number={6}, journal={MOLECULAR BIOLOGY AND EVOLUTION}, author={Hobolth, Asger and Nielsen, Rasmus and Wang, Ying and Wu, Feinan and Tanksley, Steven D.}, year={2006}, month={Jun}, pages={1318–1323} }
 @article{wang_hubbe_sezaki_wang_rojas_argyropoulos_2006, title={The role of polyampholyte charge density on its interactions with cellulose}, volume={21}, number={5}, journal={Nordic Pulp & Paper Research Journal}, author={Wang, Y. and Hubbe, M. A. and Sezaki, T. and Wang, X. and Rojas, O. J. and Argyropoulos, D. S.}, year={2006}, pages={158–165} }