Cloning and functional study of lipocalin: retinol-binding protein-like gene family of the ridgetail white prawn, Exopalaemon carinicauda

Genome-wide identification of crustacyanin and function analysis of one isoform high-expression in carapace from Neocaridina denticulata sinensis

Lipocalin proteins transport hydrophobic molecules, including apolipoprotein D, retinol-binding protein, and crustacyanin (CRCN). CRCN can combine with astaxanthin to cause a bathochromic shift in the emission spectrum of astaxanthin from red to blue. Therefore, CRCN influences the colors and patterns of crustaceans, which are important for various biological functions such as camouflage, reproduction, and communication. For aquatic organisms, body color is economically important and can be indicative of habitat water quality. In this study, thirteen CRCN genes (NdCRCNs) were first discovered in Neocaridina denticulata sinensis, contradicting prior findings of a few isoform genes in a species. The expression pattern of NdCRCNs in tissues showed that the expression of one CRCN isoform gene, named NdCRCN-30, was the highest in the carapace. In situ hybridization (ISH) analysis revealed that NdCRCN-30 was predominantly distributed in the outer epidermis of shrimp. Interference of NdCRCN-30 could cause a change in the color of the carapace. RNA-seq was performed after knockdown with the NdCRCN-30, and differential gene enrichment analysis revealed that this gene is primarily associated with antioxidant function, pigmentation, and molting. Overall, our results will provide new insights into the biological function of the CRCN and genetic breeding for changing body color in economic crustaceans.

Evaluation of anti-tick efficiency in rabbits induced by DNA vaccines encoding Haemaphysalis longicornis lipocalin homologue

Haemaphysalis longicornis is an obligate haematophagous ectoparasite, transmitting a variety of pathogens, which brings great damage to human health and animal husbandry development. Lipocalins (LIP) are a family of proteins that transport small hydrophobic molecules and also involve in immune regulation, such as the regulation of cell homeostasis, inhibiting the host's inflammatory response and resisting the contractile responses in host blood vessels. Therefore, it is one of the candidate antigens for vaccines. Based on previous studies, we constructed the recombinant plasmid pcDNA3.1-HlLIP of LIP homologue from H. longicornis (HlLIP). ELISA results showed that rabbits immunized with pcDNA3.1-HlLIP produced higher anti-rHlLIP antibody levels compared with the pcDNA3.1 group, indicating that pcDNA3.1-HlLIP induced the humoral immune response of host. Adult H. longicornis infestation trial in rabbits demonstrated that the engorgement weight, oviposition and hatchability of H. longicornis fed on rabbits immunized with pcDNA3.1-HlLIP decreased by 7.07%, 14.30% and 11.70% respectively, compared with that of the pcDNA3.1 group. In brief, DNA vaccine of pcDNA3.1-HlLIP provided immune protection efficiency of 30% in rabbits. This study demonstrated that pcDNA3.1-HlLIP can partially protect rabbits against H. longicornis, and it is possible to develop a new candidate antigen against ticks.

Effects of the Probiotic Psychrobacter sp. B6 on the Growth, Digestive Enzymes, Antioxidant Capacity, Immunity, and Resistance of Exopalaemon carinicauda to Aeromonas hydrophila

Probiotics, known to improve the water quality and the host's intestinal microbial balance, has gained more and more attention in recent years. The effects of Psychrobacter sp. B6 on the growth and immunity of Exopalaemon carinicauda were investigated in this study. Psychrobacter sp. B6 was sprayed to the basal diet with four different levels (0 [basal diet], 5 × 10⁵, 5 × 10⁷, and 5 × 10⁹ CFU/100 g diet) and were fed to E. carinicauda (average weight 1.15 ± 0.04 g) for 30 days. At the end of the feeding trial, shrimps were immersed in seawater contaminated with 10⁶ CFU/mL pathogenic Aeromonas hydrophila for 2 h and then the cumulative mortality was calculated after 14 days observation. The results showed that the weight gain rate, survival rate, and specific growth rate of E. carinicauda were significantly increased with the increasing dietary level of Psychrobacter sp. B6. The activities of digestive enzymes (α-amylase and chymotrypsin) were significantly increased (P < 0.05) in the groups fed with Psychrobacter sp. B6, and the highest activities of digestive enzymes were detected in the 5 × 10⁹ CFU/100 g diet group. The activities of antioxidant enzymes (catalase, peroxidase, and superoxide dismutase) in probiotics treated shrimp were significantly higher than those in the control shrimp, with the highest activity in 5 × 10⁹ and 5 × 10⁷ CFU/100 g diet group separately. At the same time, the activities of immune-related enzymes (alkaline phosphatase and lysozyme) were significantly affected by the dietary B6 content, and the highest activity of immune-related enzymes was found in shrimps fed with 5 × 10⁷ CFU/100 g diet. The relative expression levels of CTL (C-type lectin), MBL (mannose-binding lectin), SPI (serine protease inhibitor), and ProPo (prophenoloxidase) in hepatopancreas of E. carinicauda with 5 × 10⁹ CFU/100 g diet were significantly higher than those in the control. Moreover, cumulative mortality (22.22%) post-challenge with A. hydrophila was the lowest in 5 × 10⁹ CFU/100 g diet. The results suggested that Psychrobacter sp. B6 could effectively promote the growth, immunity, antioxidant capacity, and disease resistance of E. carinicauda. This study provided a reference for the study on the artificial breeding of E. carinicauda.

Comparison between cultured and wild Pacific white shrimp (Penaeus vannamei) vitellogenesis: next-generation sequencing and relative expression of genes directly and indirectly related to reproduction

Shrimp fisheries are among the most important fisheries worldwide, and shrimp culture has increased considerably in recent years. Most current studies on reproduction-related genes have been conducted on cultured shrimp. However, gene expression is intimately linked to physiological and environmental conditions, and therefore an organism’s growth environment has a great influence on reproduction. Thus, gene expression profiling, should be applied in fisheries studies. Here, we identified the expression patterns of 76 reproduction-related genes in P. vannamei via the analysis of pooled transcriptomes from a time-series experiment encompassing a full circadian cycle. The expression patterns of genes associated both directly (Vtg, ODP, and ProR) and indirectly (FAMet, CruA1, and CruC1) with reproduction were evaluated, as these genes could be used as molecular markers of previtellogenic and vitellogenic maturation stages. The evaluated genes were prominently upregulated during vitellogenic stages, with specific expression patterns depending on the organism’s environment, diet, and season. Vtg, ProR, ODP, and FaMet could serve as molecular markers for both wild and cultured organisms.