Effects of temperature and sex steroids on sex ratio, growth, and growth-related gene expression in the Chinese giant salamander Andrias davidianus

Abstract

Andrias davidianus is one of most farmed amphibians owing to its palatability and nutritional value. In this transitional group between aquatic and terrestrial animals the effects of temperature and sex hormones on sex ratio and growth are not fully understood. Here, we quantified the sex dimorphism of A. davidianus growth with adult males approximately 30% larger than females, and for the first time determined the time of initiation of sex differentiation to be ~98 days post-hatching (dph). Mortality increased significantly with increased temperature, from 9.4% at 20°C to 40.6% at 28°C. At temperatures ≥30°C we observed 100% mortality. The proportion of males was 66.1% at 28°C, significantly higher than in the control group (p < 0.05). 17αestradiol induced larval feminization and produced female bias of 81−100% at concentrations from 25 µg l −1 to 1000 µg l −1 . However, sex bias was not observed in larvae exposed to 17α-methyltestosterone at concentrations of 50 µg l −1 and 100 µg l −1 . Additionally, growth characteristics at different temperatures showed that 28°C inhibited growth and 24°C promoted growth, reflecting the expression profile of growth-related genes (GH, GHR, and IGF-1). Sex steroids including 17βestradiol and 17α-methyltestosterone significantly inhibited growth (p < 0.05). The results suggest that water temperature and sex steroids play a vital role in gonad differentiation and growth of A. davidianus.

Temperature and Diet Acclimation Modify the Acute Thermal Performance of the Largest Extant Amphibian

“…According to laboratory studies, A. davidianus larvae are sensitive to temperature variations [ 37 , 38 ]. The optimal growth occurs in water with a temperature range of 15–21 °C [ 39 ].…”

Potential antagonistic relationship of fgf9 and rspo1 genes in WNT4 pathway to regulate the sex differentiation in Chinese giant salamander (Andrias davidianus)

“…2013001). According to previous study, we found that gonad of A. davidianus began to differentiate on the 98 days after fertilization (Hu et al, 2019a). The developing stage gonads of 62 dpf (days post fertilization), 98 dpf, 130 dpf and 1-, 2-, 3-, 4-, 5-, and 6-years-old (6 years old) giant salamanders in the normal group and sex hormone induction group were collected.…”

Genome-Wide DNA Methylation and RNA Analysis Reveal Potential Mechanism of Resistance toStreptococcus agalactiaein GIFT Strain of Nile Tilapia (Oreochromis niloticus)

“…At 5 h postchallenge with S. agalactiae as previously described (35), spleen tissue was collected from 15 resistant and 15 susceptible fish. Each sample was divided into three parts, one preserved in RNALater (Applied Biosystems, Foster City, CA) and stored at 270˚C for RNA extraction, the second fixed in 4% paraformaldehyde (pH 7.5) for 24 h and stored in 70% ethanol to detect the differences in microstructure by histology according to the described method (36), and a third preserved in ethanol for DNA extraction. Spleens of Nile tilapia with no pathogen exposure were collected and fixed in 4% paraformaldehyde (pH 7.5) as control.…”

“…The cytosine methylation levels were determined according to the uniquely mapped reads, as previously described (39). The library construction and RNA-seq were as described (36).…”