Search

Traditionally, sciaenid eggs have been identified based on morphological characteristics such as size, number of oil globules and/or pigmentation patterns. Identification of sciaenid eggs by these procedures is time consuming and often inaccurate due to considerable egg size overlap among species. The utilization of molecular techniques for the identification of economically important species has become a fundamental component in ecological studies involving fish eggs and larvae. This study reports the development of a series of both multiplex and individual polymerase chain reactions to identify the eggs of 11 sciaenid species commonly found in the Gulf of Mexico and estuaries near Port Aransas and Corpus Christi, TX, USA. Following method development, the discriminatory power of the assay was first determined with samples from adult fish collected from Aransas and Corpus Christi Bays, Galveston Bay and the lower Laguna Madre in northern Mexico. Most (97%) of these fishes were correctly identified to the level of species. To demonstrate the applicability of the assay, wild fish eggs were collected and analyzed from the Aransas Pass tidal inlet from September through December 2005. During this period, the eggs of four target species were positively identified which was in keeping with current knowledge regarding the spawning areas and seasons of these sciaenids based on the presence of mature females, eggs and/or larvae. Future use of this method can provide valuable information to better discriminate spawning sites and seasons of these species., Author(s): Lucia B. Carreon-Martinez [sup.1] , Scott A. Holt [sup.2] , B. Scott Nunez [sup.3] , Cynthia K. Faulk [sup.2] , G. Joan Holt [sup.2] Author Affiliations: (1) grid.267455.7, 0000000419369596, [...]

Four novel glucocorticoid receptor (hGR) alpha transcripts that have various deletions of exon 2 sequences are identified. Among these hGRalpha splice variants, three of them, 1A1/E2dist hGRalpha, 1A2/E2prox hGRalpha and 1A3/E3 hGRalpha, arise from the hGR 1 A promoter, while 1B/E3 hGRalpha comes from the hGR 1 B promoter.

Steroids are lipophilic hormones that impinge upon virtually every physiological process in vertebrates. The synthesis of the correct type and amount of steroid at the proper time requires the precise regulation of the steroidogenic acute regulatory protein (STAR) and various steroidogenic cytochrome P450 and hydroxysteroid dehydrogenase enzymes. The transcription factors steroidogenic factor-1, DAX-1 and chicken ovalbumin upstream promoter transcription factor are critical to the coordinated expression of steroidogenic genes. Factors that alter the activity of steroidogenic proteins or the expression of the genes encoding them can therefore have dramatic effects on the health and reproductive success of vertebrates. We have isolated cDNAs encoding STAR, steroidogenic enzymes and steroidogenic transcription factors from a teleost, the Atlantic croaker (Micropogonias undulatus) in order to investigate the effects of natural and anthropogenic stressors on gonadal steroidogenesis. The Atlantic croaker is an abundant and ecologically important species for which a wealth of ecological and physiological data exists, making it an excellent model for the study of environmental stress and its effects on reproduction. Atlantic croaker steroidogenic cDNAs encode proteins that are 28-86% identical to corresponding proteins in other species. Using RT-PCR, we detected steroidogenic mRNAs in ovary, testis and head kidney (adrenal cortex homolog). Preliminary evidence indicates that both reproductive hormones (e.g. gonadotropins) and stress hormones (e.g. adrenocorticotropic hormone, cortisol) can regulate gonadal steroidogenesis by modulating the expression and activity of steroidogenic proteins.