Characterization of CCTα and evaluating its expression in the mud crab Scylla paramamosain when challenged by low temperatures alone and in combination with high and low salinity

Ecological genomics in the Northern krill uncovers loci for local adaptation across ocean basins

Krill are vital as food for many marine animals but also impacted by global warming. To learn how they and other zooplankton may adapt to a warmer world we studied local adaptation in the widespread Northern krill (Meganyctiphanes norvegica). We assemble and characterize its large genome and compare genome-scale variation among 74 specimens from the colder Atlantic Ocean and warmer Mediterranean Sea. The 19 Gb genome likely evolved through proliferation of retrotransposons, now targeted for inactivation by extensive DNA methylation, and contains many duplicated genes associated with molting and vision. Analysis of 760 million SNPs indicates extensive homogenizing gene-flow among populations. Nevertheless, we detect signatures of adaptive divergence across hundreds of genes, implicated in photoreception, circadian regulation, reproduction and thermal tolerance, indicating polygenic adaptation to light and temperature. The top gene candidate for ecological adaptation was nrf-6, a lipid transporter with a Mediterranean variant that may contribute to early spring reproduction. Such variation could become increasingly important for fitness in Atlantic stocks. Our study underscores the widespread but uneven distribution of adaptive variation, necessitating characterization of genetic variation among natural zooplankton populations to understand their adaptive potential, predict risks and support ocean conservation in the face of climate change.

Dietary Eucommia ulmoides Extract Alleviates the Effect of Cold Stress on Chick Growth Performance, Antioxidant and Immune Ability

This study aimed to investigate the protective value of Eucommia ulmoides extract (EUE) on chicks under cold stress. A total of 21 compounds were identified in EUE using mass spectrometry (LC-MS). Ninety chicks were divided into a control group (CS) fed a basal diet and an experimental group supplemented with EUE, exposed to 10 ± 1 °C for 8 h per day. Results showed, compared with the CS group, the body weights (BW) (p < 0.01) and average daily gains ADG (p < 0.05) of the EUE group were increased throughout the study period. Chicks fed EUE had higher AFI (0-7 d, p < 0.001) and lower feed-to-gain ratios (F/G) (0-15 d, p < 0.001). EUE increased the activities of superoxide dismutase (SOD) (15 d, p < 0.05) and glutathione peroxidase (GSH-Px) (7 d, p < 0.05), whereas it decreased malondialdehyde (MDA) (15 d, p < 0.01). The contents of IgA (7 d, p < 0.05), IgG (7 d; 15 d, p < 0.01), and IgM (15 d, p < 0. 001) were higher in the EUE group. Dietary EUE could also reduce chick organ damage. Overall, EUE as a natural feed additive can improve the growth performance, antioxidant capacity, and immune level, and reduce the organ damage of cold-stressed chicks.

Profiles of calreticulin and Ca2+ concentration under low temperature and salinity stress in the mud crab, Scylla paramamosain

Calreticulin (CRT) is an important molecular chaperon crucial to survival of organisms under adverse conditions. In this study, the potential roles of CRT in the mud crab, Scylla paramamosain, were investigated. Firstly, SpCRT gene expression was detected in various tissues of S. paramamosain with the highest expression found in the hepatopancreas. To evaluate potential role of SpCRT in cold adaption, sub-adult crabs were subjected to temperatures of 10, 15, 20 and 25°C and the profiles of SpCRT gene were determined in the hepatopancreas, chela muscle and gills. The results showed that the expressions of SpCRT mRNA in these tissues were significantly higher for those crabs exposed to low temperatures of 10 and 15°C as compared to those exposed to the higher temperatures, indicating SpCRT was involved in cold adaptation-probably through facilitating protein folding. When low temperature 10°C or 15°C was further combined with high and low salinity stress, the expression of SpCRT mRNA at low salinity (10 ppt) was in most cases significantly higher than that at high salinity (35 ppt), suggesting that under low temperatures, low salinity may represents a more stressful condition to the crab than high salinity. It was also shown that when crabs challenged by 10°C, Ca2+ concentration increased rapidly in the hepatopancreas and an in vitro experiment further showed that the expression of SpCRT mRNA increased concurrently with added Ca2+ concentration; these results together imply that Ca2+ probably plays a major role in low temperature signaling, which induces expression of genes related to cold adaption, such as CRT.