Single-Cell Ribonucleic Acid Sequencing Clarifies Cold Tolerance Mechanisms in the Pacific White Shrimp (Litopenaeus Vannamei)

To characterize the cold tolerance mechanism of the Pacific white shrimp (Litopenaeus vannamei), we performed single-cell RNA sequencing (scRNA-seq) of ∼5185 hepatopancreas cells from cold-tolerant (Lv-T) and common (Lv-C) L. vannamei at preferred and low temperatures (28°C and 10°C, respectively). The cells fell into 10 clusters and 4 cell types: embryonic, resorptive, blister-like, and fibrillar. We identified differentially expressed genes between Lv-T and Lv-C, which were mainly associated with the terms “immune system,” “cytoskeleton,” “antioxidant system,” “digestive enzyme,” and “detoxification,” as well as the pathways “metabolic pathways of oxidative phosphorylation,” “metabolism of xenobiotics by cytochrome P450,” “chemical carcinogenesis,” “drug metabolism-cytochrome P450,” and “fatty acid metabolism.” Reconstruction of fibrillar cell trajectories showed that, under low temperature stress, hepatopancreas cells had two distinct fates, cell fate 1 and cell fate 2. Cell fate 1 was mainly involved in signal transduction and sensory organ development. Cell fate 2 was mainly involved in metabolic processes. This study preliminarily clarifies the molecular mechanisms underlying cold tolerance in L. vannamei, which will be useful for the breeding of shrimp with greater cold tolerance.

Micro-Aid Liquid 10 Promotes Growth Performance and Health Status of White Shrimp, Litopenaeus vannamei

An experiment was conducted to evaluate the effects of the Micro-Aid Liquid 10 (MAL10) (DPI Global, Porterville, CA, USA), a product made from yucca extract, on growth performance, gut microbiota, and resistance of white shrimp, Litopenaeus vannamei against infectious disease caused by Vibrio alginolyticus. MAL10 was added to shrimp rearing water at different levels of 0 (control), 0.25 mL m3−1 (W0.25), 0.5 mL m3−1 (W0.5), 1 mL m3−1 (W1), and 5 mL m3−1 (W5), respectively, once per week for 70 days. Growth performances, including final body weight, specific growth rate, average daily growth and percentage of weight gain, were significantly improved by adding the MAL10 at levels up to 5 mL m3−1, which may be due to the proliferation of B cells in hepatopancreas of MAL10-treated shrimp. No significant differences in the total viable count and Vibrio-like count in the gut of shrimp were recorded by spread plate method. In the challenge test, shrimp reared in the water supplemented with MAL10 at levels of 1–5 mL m3−1 had significantly lower cumulative mortality after a challenge test with V. alginolyticus compared to shrimp reared in the control, W0.25 and W0.5 groups. Next-generation sequencing indicated that the relative distribution of phylum Proteobacteria in control (80.4%) was higher than the W (77.4%). The proportion of Vibrio was primarily dominant genera in the shrimp intestine and highest in the control group compared to the W group, followed by Spongiimonas, Motilimonas, Demequina, and Shewanella genera. Although there was no statistically significant difference, higher α-diversity indices were recorded in the W5-treated group than in the control group. Therefore, it is considered that MAL10 could be used as a natural alternative in shrimp aquaculture to reduce the risk of infectious disease caused by pathogenic Vibrio and improve the growth performance of white shrimp.

Histopathological of the hepatopancreas of Pacific white shrimp (Litopenaeus vannamei) infected by white feces disease

The high production of Pacific white shrimp (Litopenaeus vannamei) in Pidie Jaya impacts water quality decline around the ponds due to aquaculture waste. This condition causes shrimp to be susceptible to diseases, one of which is white feces disease (WFD). The objective of the study is to determine the level of hepatopancreatic damage caused by WFD through histopathological performance. Four shrimp samples were taken randomly from two semi-intensive ponds in Meurah Dua District, Pidie Jaya Regency, Aceh, Indonesia. The results showed that the histopathology in the hepatopancreas was severely damaged. The damages include vacuolization, fat degeneration, and necrosis in ponds with higher ammonia concentrations. According to pH, temperature, salinity, and ammonia concentrations, ponds near residential areas were more polluted than ponds far from residential areas. This condition is projected by the more damaged histopathological obstruction of the shrimp’s hepatopancreas.