General and Comparative Endocrinology This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Effects of cooling on thyroid hormone secretion and growth of eastern bluebird (Sialia sialis) nestlings
We examined the effects of (1) a single cooling challenge on thyroid hormone secretion in pre-homeothermic nestlings, and (2) repeated cooling challenges prior to the onset of homeothermy on nestling growth and thyroid hormone secretion prior to fledging. We found that pre-homeothermic eastern bluebird nestlings exposed to a single cooling challenge increased circulating triiodothyronine (T3), demonstrating that the thyroid system can be activated by cooling early in life. However, we found no consequences of repeated cooling during the first week of life on nestling growth or baseline T3 levels prior to fledging. This wor...
Source: General and Comparative Endocrinology - December 11, 2023 Category: Endocrinology Authors: Sharon E Lynn Michael D Kern Nathan Cagwin Alexis Will Alexander Kitaysky Source Type: research

Incubation as a driver of maternal effects: Temperature influences levels of yolk maternally derived 5 α-dihydrotestosterone
Gen Comp Endocrinol. 2023 Dec 4:114420. doi: 10.1016/j.ygcen.2023.114420. Online ahead of print.ABSTRACTIn birds, maternal hormones deposited into eggs in response to environmental stimuli can impact offspring phenotype. Although less studied, environmental conditions can also influence females' incubation behavior, which might play a role in regulating embryo exposure to maternal hormones through changes in incubation temperature that affect the activity of the enzymes responsible for converting testosterone (T) to 5α-dihydrotestosterone (DHT) or estradiol. Here, we tested the hypothesis that the initial T content of the...
Source: General and Comparative Endocrinology - December 6, 2023 Category: Endocrinology Authors: Am érica Hernández Roxana Torres Bibiana Montoya Source Type: research

Influence of EE2 exposure, age and sex on telomere length in European long-snouted seahorse (Hippocampus guttulatus)
Gen Comp Endocrinol. 2023 Nov 29:114419. doi: 10.1016/j.ygcen.2023.114419. Online ahead of print.ABSTRACTAfter a Telomere Lengthening in juvenile stage, a progressive telomere shortening occurs with age despite higher telomerase level. Telomere Length (TL) may also reflect past physiological state such as a chronic chemical stress. Several studies have revealed a correlation between TL, ageing and/or sex in vertebrates, including teleosts; however, the patterns of telomere dynamics with telomerase mRNA expression, sex, lifespan or chemical stress in teleosts are unclear. The first aim of this study is to verify if telomere...
Source: General and Comparative Endocrinology - December 1, 2023 Category: Endocrinology Authors: Nathalie Pr évot D'Alvise Eliette Ascensio Simone Richard Source Type: research

Effects of testosterone on urogenital tract morphology and androgen receptor expression in immature Eastern Fence lizards (Sceloporus undulatus)
We examined gonads, mesonephric kidneys and ducts (male reproductive tract primordia), paramesonephric ducts (oviduct primordia), sexual segments of the kidneys (SSKs), and hemiphalluses to determine which structures were sexually dimorphic independent of T treatment and which structures exhibited sexually dimorphic responses to T. To better understand tissue-level responsiveness to T treatment, we also characterized androgen receptor (AR) expression by immunohistochemistry. At approximately 4 months after hatching in control animals, gonads were well differentiated but quiescent; paramesonephric ducts had fully degenerate...
Source: General and Comparative Endocrinology - November 30, 2023 Category: Endocrinology Authors: Matthew R Milnes Christopher D Robinson Alexis P Foley Charleigh Stepp Matthew D Hale Henry B John-Alder Robert M Cox Source Type: research

Structural and functional characterization of an egg-laying hormone signaling system in a lophotrochozoan - the Pacific oyster (Crassostrea gigas)
Gen Comp Endocrinol. 2023 Nov 27:114417. doi: 10.1016/j.ygcen.2023.114417. Online ahead of print.ABSTRACTThe egg-laying hormones (ELHs) of gastropod mollusks were characterized more than forty years ago. Yet, they have remained little explored in other mollusks. To gain insights into the functionality of the ELH signaling system in a bivalve mollusk - the oyster Crassostrea gigas, this study investigates the processing of its ELH precursor (Cragi-ELH) by mass spectrometry. Some of the ELH mature peptides identified in this study were subsequently investigated by nuclear magnetic resonance and shown to adopt an extended alp...
Source: General and Comparative Endocrinology - November 29, 2023 Category: Endocrinology Authors: P Favrel M P Dubos B Bernay J Pasquier J Schwartz B Lefranc L Mouret G Rivi ère J Leprince A Bondon Source Type: research

Timing of puberty in F1-generation hatchery-produced greater amberjack (Seriola dumerili)
Gen Comp Endocrinol. 2023 Nov 24:114414. doi: 10.1016/j.ygcen.2023.114414. Online ahead of print.ABSTRACTWe evaluated the onset of puberty of first-generation (F1) hatchery-produced greater amberjack (Seriola dumerili) reared in sea cages for 5 years. Fish were sampled every year in June, at the expected peak of the spawning period in the Mediterranean Sea. No sexual dimorphism in body weight was observed in the study. The ovaries of 1 and 2-year-old (yo) females consisted of primary oocytes only, while at the age of 3-yo early vitellogenic (Vg) oocytes were also identified. At the age of 4-yo, late Vg oocytes were observe...
Source: General and Comparative Endocrinology - November 26, 2023 Category: Endocrinology Authors: Stefano Lancerotto Ioannis Fakriadis Maria Papadaki Manolis Mandalakis Irini Sigelaki Constantinos C Mylonas Source Type: research