Corticosteroid receptor expression in a teleost fish that displays alternative male reproductive tactics

Abstract

Corticosteroid signaling mechanisms mediate a wide range of adaptive physiological responses, including those essential to reproduction. Here, we investigated the presence and relative abundance of corticosteroid receptors during the breeding season in the plainfin midshipman fish (Porichthys notatus), a species that has two male reproductive morphs. Only type I "singing" males acoustically court females and aggressively defend a nest site, whereas type II "sneaker" males steal fertilizations from nesting type I males. Cloning and sequencing first identified glucocorticoid (GR) and mineralocorticoid (MR) receptors in midshipman that exhibited high sequence identity with other vertebrate GRs and MRs. Absolute quantitative real time PCR then revealed higher levels of GR in the central nervous system (CNS) of type II males than type I males and females, while GR levels in the sound-producing, vocal muscle and the liver were higher in type I males than type II males and females. MR expression was also greater in the CNS of type II males than type I males or females, but the differences were more modest in magnitude. Lastly, plasma levels of cortisol, the main glucocorticoid in teleosts, were two to three fold greater in type II males compared to type I males. Together, the results suggest a link between corticosteroid regulation and physiological and behavioral variation in a teleost fish that displays male alternative reproductive tactics.

Manipulation of BK channel expression is sufficient to alter auditory hair cell thresholds in larval zebrafish

“…Reactions were run on an Applied Biosystems ViiA 7 System at the Cornell University Life Sciences Core Laboratory Center under the default manufacturer's conditions using 57°C as an annealing temperature. Gene copy number was determined using standard curve analysis for each target (Arterbery et al, 2010), including 18S rRNA (GenBank accession no. FJ915075.1), which was used as the reference gene for normalizing gene copy number.…”

“…All threshold data were graphed as means with 95% confidence interval error bars. qPCR data for slo1a or slo1b MO groups were analyzed with an ANOVA as described previously (Arterbery et al, 2010). Because qPCR reactions were carried out across several plates with an even number of each treatment group represented on each plate, qPCR data for the combined MO groups were fitted to a model with 18S-normalized expression as the response, and plate and treatment group as fixed effects.…”

Social regulation of cortisol receptor gene expression

“…Similar to A. burtoni, plainfin midshipman (Porichthys notatus) males occur in one of two phenotypes: a D male and a ND male (sneaker male). ND plainfin midshipman have twofold more circulating cortisol than D males (Arterbery et al, 2010) and also exhibit elevated GR1b mRNA levels in all brain…”

Some Aspects of Steroid Regulation in Teleosts

“…Вопрос о потенциальном лиганде рецептора MR у кос-тистых рыб, а также о необходимости сущест-вования такого лиганда не решен до сих пор [Takahashi, Sakamoto, 2013;Tokarz et al, 2015;Baker, Katsu, 2017]. Показано, что экспрессия MR рыб значительно выше в мозге, чем в орга-нах, участвующих в осморегуляции Sturm et al, 2005;Arterbery et al, 2010]. Высказано предположение, что ре-цепторы MR у рыб могут быть связаны с ре-гуляцией поведения [Takahashi, Sakamoto, 2013].…”