Linked Life Data

16473352

Source:http://linkedlifedata.com/resource/pubmed/id/16473352

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2006-5-15
pubmed:abstractText
Recent precipitous population declines in northern fur seal (Callorhinus ursinus) and other Alaskan pinniped populations are due in part to reduced fecundity and have emphasized deficits in basic reproductive knowledge of these species. Following estrus and mating, fertilized female pinnipeds experience an obligatory delayed implantation lasting several months and non-pregnant (pseudopregnant) females are indistinguishable by sex steroid levels during this time. The current study examined circulating steroid concentrations and ovarian expression of key steroid-synthesizing enzymes in northern fur seals to identify changes associated with embryonic implantation, data necessary for estimating early pregnancy rates of the population. Blood samples were collected from 84 female fur seals captured on an Alaskan rookery from October 15 to November 30, a period spanning the end of the delay and subsequent uterine implantation of the fertilized blastocyst in this species. Concentrations of progesterone, estradiol, and estrone measured in blood collected during boreal fall were contrasted with samples collected during late summer from post-ovulatory females and males. Serum sex steroids were also related to ovarian expression of key enzymes responsible for androgen (17alpha-hydroxylase/17,20-lyase, cytochrome b5, and 3beta-hydroxysteroid dehydrogenase) and estrogen (aromatase cytochrome P450) synthesis. Enzymes necessary for androgen synthesis were highly expressed in ovaries, and accordingly, endocrine profiles were expanded to include DHEA, androstenediol, androstenedione, and testosterone. Estradiol concentrations were universally low and free and conjugated estrone were the primary circulating estrogens in fur seal sera. No implantation-associated peak was identified for estrogens or progesterone and mean values of progesterone and estrone were actually greater in female serum samples collected during summer than fall. However, there was a significant positive relationship between fall sampling date and testosterone concentration. Additionally, DHEA concentrations in females were lower in samples collected during the implantation period than during the summer embryonic delay. These data suggest androgens may play a substantial regulatory role in the embryonic delay of northern fur seals.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0016-6480
pubmed:author
pubmed:issnType
Print
pubmed:volume
147
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
175-83
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:16473352-17-Hydroxysteroid Dehydrogenases, pubmed-meshheading:16473352-Androstenediol, pubmed-meshheading:16473352-Animals, pubmed-meshheading:16473352-Aromatase, pubmed-meshheading:16473352-Dehydroepiandrosterone, pubmed-meshheading:16473352-Embryo Implantation, pubmed-meshheading:16473352-Estradiol, pubmed-meshheading:16473352-Estrone, pubmed-meshheading:16473352-Estrus, pubmed-meshheading:16473352-Female, pubmed-meshheading:16473352-Fur Seals, pubmed-meshheading:16473352-Gonadal Steroid Hormones, pubmed-meshheading:16473352-Male, pubmed-meshheading:16473352-Ovary, pubmed-meshheading:16473352-Progesterone, pubmed-meshheading:16473352-Radioimmunoassay, pubmed-meshheading:16473352-Seasons, pubmed-meshheading:16473352-Steroid 17-alpha-Hydroxylase, pubmed-meshheading:16473352-Testosterone
pubmed:year
2006
pubmed:articleTitle
Sex steroid concentrations and localization of steroidogenic enzyme expression in free-ranging female northern fur seals (Callorhinus ursinus).
pubmed:affiliation
Population, Health and Reproduction, University of California, Davis, 1114 Tupper Hall, 95616, USA. pbrowne@ucdavis.edu
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't