Heat stress is an increasingly concerning topic under global warming. Heat stress can induce organisms to produce excess reactive oxygen species, which will lead to cell damage and destroy the antioxidant defense of aquatic animals. Chinese mitten crab, Eriocheir sinensis, is sensitive to the change in water temperature, and parent crabs are more vulnerable during the breeding stage. In the present study, the multi-omics responses of parent E. sinensis gills to heat stress (24 h) were determined via transcriptome and proteome. The integrative analysis revealed that heat shock protein 70 (HSP70) and glutathione s-transferase (GST) were significantly up-regulated at gene and protein levels after heat stress, indicating that HSP70 and the antioxidant system participated in the regulatory mechanism of heat stress to resist oxidative damage. Moreover, the “Relaxin signaling pathway” was also activated at gene and protein levels under 30 °C stress, which implied that relaxin may be essential and responsible for reducing the oxidative damage of gills caused by extreme heat stress. These findings provided an understanding of the regulation mechanism in E. sinensis under heat stress at gene and protein levels. The mining of key functional genes, proteins, and pathways can also provide a basis for the cultivation of new varieties resistant to oxidative stress.

Cipangopaludina cathayensis (Gastropoda: Prosobranchia; Mesogastropoda; Viviparidae) is widely distributed in the freshwater habitats of China. It is an economically important snail with high edible and medicinal value. However, the genomic resources and the reference genome of this snail are lacking. In this study, we assembled the first chromosome-level genome of C. cathayensis. The preliminary assembly genome was 1.48 Gb in size, with a contig N50 size of 93.49 Mb. The assembled sequences were anchored to nine pseudochromosomes using Hi-C data. The final genome after Hi-C correction was 1.48 Gb, with a contig N50 of 98.49 Mb and scaffold N50 of 195.21 Mb. The anchored rate of the chromosome was 99.99%. A total of 22,702 protein-coding genes were predicted. Phylogenetic analyses indicated that C. cathayensis diverged with Bellamya purificata approximately 158.10 million years ago. There were 268 expanded and 505 contracted gene families in C. cathayensis when compared with its most recent common ancestor. Five putative genes under positive selection in C. cathayensis were identified (false discovery rate <0.05). These genome data provide a valuable resource for evolutionary studies of the family Viviparidae, and for the genetic improvement of C. cathayensis.

Selenium, an essential trace element, exerts beneficial effects on aquatic animals when present in suitable concentrations. This study investigates the effect of dietary nanometer selenium (Nano-Se) on the muscle selenium accumulation, nutrient composition, and antioxidant ability of Paramisgurnus dabryanus spp. Nano-Se was supplemented in the basal diets at levels of 0, 0.1, 0.2, 0.4, and 0.6 mg/kg. Three hundred fish, averaging 5.21 ± 0.06 g, were randomly divided into five groups and fed the experimental diet for 6 weeks. Fish with a dietary Nano-Se supplement of 0.2 mg/kg exhibited activities of SOD, GSH-Px, AKP, and CAT in the liver, which were significantly higher (p < 0.05) compared to the control diet, while MDA content was significantly lower (p < 0.05) in the 0.2 mg/kg group. The muscle selenium content significantly increased (p < 0.05) at ≥0.2 mg/kg Nano-Se levels. The highest levels of essential amino acids, EAA/TAA, and EAA/NEAA ratios were observed in fish fed 0.2 mg of Nano-Se. Thus, this study recommends incorporating 0.2 mg of Nano-Se per kg in the diet to enhance antioxidant defense, selenium content, and nutrient composition.

Procambarus clarkii is adept at using natural shelters and caves to evade attacks from predators. However, the concealment abilities and mechanisms of P. clarkii for different types of shelters under predation pressure have not yet been reported. In this study, laboratory experiments were carried out to determine the effects of different coverages (25%, 50%, and 75%) and different combinations (I–VII) of three types of shelters (PVC pipes, water grass, and stone) on the predation rhythm, behavior, and abilities of Silurus asotus on P. clarkii. The results indicated that the predation of S. asotus on P. clarkii exhibited significant rhythmicity under shelter conditions, excluding PVC pipes, 75% stone, and combination VI. Among the three types of shelters, PVC pipes provided the strongest concealment, followed by stone and water grass. With the increase in shelter coverage, the anti-predation ability of P. clarkii continued to increase, and the optimal shade rate for water grass was 50%. In the different shelter combinations, the environmental complexity had little effect on the predation activity of S. asotus on P. clarkii. These findings demonstrated that the type and abundance of shelters in the wild environment can affect the predation rhythm and activities of S. asotus on P. clarkii.

We obtained mtDNA control region sequences of 102 E. sinensis individuals of 7 populations in Yangtze River system (Adults of E. sinensis in Huangmai, Poyang lake, Pengze, Anqing, Zhenjiang and the Yangtze estuary, juveniles of E. sinensis in Zhenjiang and the Yangtze estuary, abbreviated as HM, PY, PP, AQ, ZC, ZY and CY) and analysed their genetic diversity. The resulted showed that the complete sequences of control region was 515 bp. Total of 65 variation sites including 31 singleton polymorphic sites and 34 parsimony informative polymorphic sites were defined in the 102 individuals sampled of 7 populations, in which 60 haplotypes were detected. The haplotype diversity (Hd) was found to be 0.919±0.023, nucleotide diversity 0.01007±0.00081, the average nucleotide difference (K) 5.106. Genetic differentiation index (Fst) among populations was -0.0098 to 0.0983; genetic distance was 0.0067 to 0.0122; the genetic variation among populations accounts for only 3.3% of total variation. Mismatch distributions suggested that E. sinensis in the Yangtze River system had not experienced a rapid population expansion in the recent past. The results showed that genetic diversity level of E. sinensis in the Yangtze River system was high. The seven populations had not been formed geographic differentiation obviously and apomixes would occur between them.