Daxx from Pacific white shrimp Litopenaeus vannamei is involved in activation of NF-κB pathway

A Biofloc-Based Aquaculture System Bio-augmented with Probiotic Bacteria Bacillus tequilensis AP BFT3 Improves Culture Environment, Production Performances, and Proteomic Changes in Penaeus vannamei

Experiments were conducted to evaluate the probiotic effect of bio-augmented Bacillus tequilensis AP BFT3 on improving production, immune response, and proteomic changes of Penaeus vannamei reared in a biofloc system. Penaeus vannamei larvae (PL13) were stocked in 100-L tanks at a rate of 100 no per tank to study the effect of B. tequilensis AP BFT3 with and without biofloc (BFT-PRO and PRO). Control tanks devoid of probiotic strain were maintained in a clear water system. The growth and survival considerably increased in probiotic added biofloc reared shrimp than probiotic added clear water reared ones and control. Water quality significantly improved in probiotic added (PRO) and biofloc-probiotics (BFT-PRO) system than control. Microbiological investigations indicate increased heterotrophic bacterial load in BFT-PRO compared to the PRO and control. The quality of the isolated microbes was analyzed in terms of enzyme production, and an abundance of enzyme-producing bacterial population was observed in BFT-PRO shrimp. Immune-related genes were significantly upregulated in BFT-PRO shrimp, followed by the PRO and control. The proteomic data (2D gel electrophoresis and MALDI-TOF) of muscle tissue from the experimental animals identified 11 differentially expressed proteins. The Daxx OS and Lit v 1 tropomyosin was found upregulated in BFT-PRO shrimps. Downregulation of Na⁺/K⁺ATPase was observed in biofloc with probiotic-supplied groups. The findings revealed that the BFT system's efficacy could be improved through the addition of probiotics. The addition of B. tequilensis AP BFT3 as a probiotic in biofloc induced the expression of essential proteins, reducing contracting diseases during culture.

WSV152 induces apoptosis and promotes viral replication in Litopenaeus vannamei

Previous studies have indicated that white spot syndrome virus (WSSV) infection induces apoptosis in many shrimp organs. However, the mechanism by which WSSV causes host apoptosis remains largely unknown. In this study, we demonstrated the function of wsv152, the first mitochondrial protein identified as encoded by WSSV. Glutathione S-transferase pulldown and co-immunoprecipitation analysis revealed that wsv152 interacts with the shrimp mitochondrial protein cytochrome c oxidase 5a (COX5a), a subunit of the COX complex. We also found that wsv152 expression significantly increased the rate of apoptosis, suggesting a role of wsv152 in WSSV-induced apoptosis in shrimp. Knockdown of wsv152 in vivo led to downregulation of several apoptosis-related shrimp genes, including cytochrome c, apoptosis-inducing factor and caspase-3. Suppression of wsv152 also resulted in significant reductions in the number of WSSV genome copies in tissues and in the mortality of WSSV-infected shrimp. Together, these results suggest that wsv152 targets host COX5a and is associated with the expression profiles of apoptosis-related shrimp genes. Wsv152 is likely also involved in WSSV-induced apoptosis, thereby facilitating virus infection and playing a complex role in WSSV pathogenesis.

White spot syndrome virus (WSSV) infection impacts intestinal microbiota composition and function in Litopenaeus vannamei

Intestinal microbiota homeostasis is crucial to the health of host. Pathogen invasion results in dynamics of microbiota composition and structure, disrupting their function in maintaining host health. WSSV is the most prevalent viral pathogen and is able to cause extremely high mortality in Litopenaeus vannamei. However, the changes of intestinal microbiota induced by WSSV are yet to be elucidated. In this study, we analyzed and compared the microbiota of healthy and WSSV-challenged shrimp intestines. Though the richness and diversity of microbiota was barely affected by WSSV, the abundance of predominant phyla like Proteobacteria and Fusobacteria were upregulated significantly, while Bacteroidetes and Tenericutes were significantly decreased in WSSV-infected shrimps. At the genus level, significant increase was observed in Photobacterium, Propionigenium and Arcobacter, as well as significant decrease in Candidatus Bacilloplasma and Flavobacterium in WSSV-infected shrimps. Additionally, metagenomic predictions by PICRUSt suggested that the altered microbiota was mainly related to metabolism, human diseases, genetic information processing, environmental information processing and cellular processes. These results suggested that the invasion of WSSV could impact intestinal microbiota composition and function in L. vannamei.

Silencing of a Kazal-type serine proteinase inhibitor SPIPm2 from Penaeus monodon affects YHV susceptibility and hemocyte homeostasis

In shrimp, the Kazal-type serine proteinase inhibitors (KPIs) are involved in host innate immune defense system against pathogenic microorganisms. A five-Kazal-domain SPIPm2 is the most abundant KPIs in the black tiger shrimp Penaeus monodon and up-regulated in response to yellow head virus (YHV) infection. In this study, the role of SPIPm2 in YHV infection was investigated. The expression of SPIPm2 in hemocytes, gill and heart from 48-h YHV-infected shrimp was increased. The expression of SPIPm2 in hemocytes was significantly increased after 12 h of infection and gradually increased higher afterwards. Silencing of SPIPm2 by dsRNA interference resulted in the increased expression of different apoptosis-related genes, the increased expression of transcriptional factors of antimicrobial synthesis pathways, the reduction of circulating hemocytes in the shrimp hemolymph, and the increased susceptibility of the silenced shrimp to YHV infection. The activities of caspase-3 and caspase-7 in the hemocytes of SPIPm2-silenced shrimp was also increased by 5.32-fold as compared with those of the control shrimp. The results suggested that the SPIPm2 was involved in the hemocyte homeostasis.

Identification and characterization of an apoptosis-stimulating protein of p53 (ASPP) gene from Branchiostoma belcheri: Insights into evolution of ASPP gene family

The ASPP (apoptosis-stimulating protein of p53) protein family plays very key roles in apoptosis regulation, in both p53-dependent and p53-independent pathways. However, the ASPP homologous gene has not been identified in amphioxus to date. Here, we identified and characterized an ASPP gene from Branchiostoma belcheri (designed as AmphiASPP) and extensively studied its evolution and roles involved in innate immunity. The results showed that the amphioxus genome has an ASPP homolog gene with an ORF of 3285 bp, encoding 1094 amino acids which contains ANK repeats and SK3 domain. The evolutionary analyses indicated that the members of ASPP protein family might be present in a common ancestor of Nematostella vectensis and underwent positive selective in the evolutionary history. In addition, the amphioxus ASPP gene was ubiquitously and differentially expressed in five investigated tissues, and the amphioxus ASPP gene was involved in the innate immune response of LPS and LTA stimulation. Finally, bioinformatic analyses displayed that amphioxus ASPP protein could interact with REL protein by conserved binding sites compared with human ASPP2 protein, which seemed to further suggest that the amphioxus ASPP protein involve in innate immunity through NF-кB signaling pathway. Taken together, our findings provided an insight into the evolution and innate immunity function of the ASPP family.