|
 |
|||||
RESEARCH INTERESTS: Fish Reproduction/Toxicology RESEARCH SUMMARY: The main focus is to understand the endocrine events that coordinate the growth of the gonads in fishes and how environmental contaminants affect their reproduction. A major aspect of ongoing research is the study of the sex hormone estradiol and gonadal estrogen receptors, and how they might be involved in ovarian and testicular development in salmonid fishes. Estrogens are important in both sexes and appear to play significant roles during early embryonic development and later within the maturing gonads. A more applied aspect of the estrogen receptor work is the apparent negative effect environmental contaminants, that mimic estrogens, could be having on wild fish reproduction. A major study is looking at low-level transgenerational effects of ethynylestradiol in the male rainbow trout. A significant environmental contaminant, ethynylestradiol derives from human birth control pharmaceuticals and has been shown to affect fish reproduction. Research is also being conducted on the variable reproductive performance of female rainbow trout broodstock in production aquaculture facilities. Some females produce egg batches with reduced embryos survival and studies to understand why this occurs are underway.
REPRESENTATIVE PUBLICATIONS: Nagler, James J., Tim Cavileer, Jack Sullivan, Daniel G. Cyr, and Caird Rexroad III (2007); The complete nuclear estrogen receptor family in the rainbow trout: discovery of the novel ERa2 and both ERb isoforms. Gene 392:164-173. de Montgolfier, Benjamin, Julie Dufresne, Myriam Letourneau, James J. Nagler, Alain Fournier, Celine Audet, and Daniel G. Cyr (2007); The expression of multiple connexins throughout spermatogenesis in the rainbow trout testis suggests a role for complex intercellular communication. Biol. Reprod. 76:2-8. Skillman, Ann D., James J. Nagler, Sharon E. Hook, Jack A. Small, and Irvin R. Schultz (2006); Dynamics of 17a-ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): absorption, tissue distribution and hepatic gene expression. Environ. Tox. Chem. 25:2997-3005. Wilson, Sean M. and James J. Nagler (2006); Age, but not salinity, affects the upper lethal temperature limits for juvenile walleye (Sander vitreus). Aquaculture 257:187-193. Stoddard, Jonathan W., James E. Parsons, and James J. Nagler (2005); Early onset of embryonic mortality in sub-fertile families of rainbow trout (Oncorhynchus mykiss). Reprod. Fertility Develop. 17:785-790. Bouma, Gerrit J., Joseph G. Cloud, and James J. Nagler (2005); An in vitro system for the long-term tissue culture of juvenile rainbow trout (Oncorhynchus mykiss) testis. J. Exp. Zool. 303A: 698-703. Chowen, Trevor R. and James J. Nagler. (2005); Lack of sex specificity for growth hormone pseudogene in fall-run chinook salmon from the Columbia River. Trans. Am. Fish. Soc. 134:279-282. Wendling, Neesha C., David C. Bencic, James J. Nagler, Joseph G. Cloud, and Rolf L. Ingermann (2004); Adenosine triphosphate (ATP) levels in steelhead (Oncorhynchus mykiss) eggs: An examination of turnover, localization, and role. Comp. Biochem. Physiol. Part A 137:739-748.
|
||||||
