Ingestion of food pellets containing Escherichia coli overexpressing the heat-shock protein DnaK protects Penaeus vannamei (Boone) against Vibrio harveyi (Baumann) infection

Heat Shock Proteins (Hsps) in Cellular Homeostasis: A Promising Tool for Health Management in Crustacean Aquaculture

Heat shock proteins (Hsps) are a family of ubiquitously expressed stress proteins and extrinsic chaperones that are required for viability and cell growth in all living organisms. These proteins are highly conserved and produced in all cellular organisms when exposed to stress. Hsps play a significant role in protein synthesis and homeostasis, as well as in the maintenance of overall health in crustaceans against various internal and external environmental stresses. Recent reports have suggested that enhancing in vivo Hsp levels via non-lethal heat shock, exogenous Hsps, or plant-based compounds, could be a promising strategy used to develop protective immunity in crustaceans against both abiotic and biotic stresses. Hence, Hsps as the agent of being an immune booster and increasing disease resistance will present a significant advancement in reducing stressful conditions in the aquaculture system.

Can heat shock protein 70 (HSP70) serve as biomarkers in Antarctica for future ocean acidification, warming and salinity stress?

The Antarctic Peninsula is one of the fastest-warming places on Earth. Elevated sea water temperatures cause glacier and sea ice melting. When icebergs melt into the ocean, it “freshens” the saltwater around them, reducing its salinity. The oceans absorb excess anthropogenic carbon dioxide (CO2) causing decline in ocean pH, a process known as ocean acidification. Many marine organisms are specifically affected by ocean warming, freshening and acidification. Due to the sensitivity of Antarctica to global warming, using biomarkers is the best way for scientists to predict more accurately future climate change and provide useful information or ecological risk assessments. The 70-kilodalton (kDa) heat shock protein (HSP70) chaperones have been used as biomarkers of stress in temperate and tropical environments. The induction of the HSP70 genes (Hsp70) that alter intracellular proteins in living organisms is a signal triggered by environmental temperature changes. Induction of Hsp70 has been observed both in eukaryotes and in prokaryotes as response to environmental stressors including increased and decreased temperature, salinity, pH and the combined effects of changes in temperature, acidification and salinity stress. Generally, HSP70s play critical roles in numerous complex processes of metabolism; their synthesis can usually be increased or decreased during stressful conditions. However, there is a question as to whether HSP70s may serve as excellent biomarkers in the Antarctic considering the long residence time of Antarctic organisms in a cold polar environment which appears to have greatly modified the response of heat responding transcriptional systems. This review provides insight into the vital roles of HSP70 that make them ideal candidates as biomarkers for identifying resistance and resilience in response to abiotic stressors associated with climate change, which are the effects of ocean warming, freshening and acidification in Antarctic organisms.

Pandanus tectorius fruit extract promotes Hsp70 accumulation, immune-related genes expression and Vibrio parahaemolyticus tolerance in the white-leg shrimp Penaeus vannamei

Plants and herbal extracts are indispensable for controlling the spread of disease-causing bacteria, including those that infect aquatic organisms used in aquaculture. The use of plant or herbal extract is expected to be safe for aquatic animals and less harmful to the environment, as opposed to conventional therapeutic alternatives such as antibiotics that promote the occurrence of potential antibiotic-resistant bacteria when used improperly. The efficacy of Pandanus tectorius fruit extract in the regulation of Hsp70 expression, pro-phenoloxidase (ProPO), peroxinectin, penaeidin, crustin and transglutaminase, all immune peptides essential for Vibrio tolerance in white leg shrimp, Penaeus vannamei, was investigated in this study, which included the determination of the safety levels of the extract. Tolerance of shrimp against Vibrio parahaemolyticus, a pathogenic bacteria that causes Acute Hepatopancreas Necrosis Disease (AHPND), was assessed on the basis of median lethal dose challenge survival (LD50 = 10⁶ cells/ml). Mortality was not observed 24 h after exposure of 0.5-6 g/L of the fruit extract, indicating that P. tectorius was not toxic to shrimp at these concentrations. A 24-h incubation of 2-6 g/L of the fruit extract increased shrimp tolerance to V. parahaemolyticus, with survival doubled when the maximum dose tested in this study was used. Concomitant with a rise in survival was the increase in immune-related proteins, with Hsp70, ProPO, peroxinectin, penaeidin, crustin and transglutaminase increased 10, 11, 11, 0.4, 8 and 13-fold respectively. Histological examination of the hepatopancreas and muscle tissues of Vibrio-infected shrimp primed with P. tectorius extract revealed reduced signs of histopathological degeneration, possibly due to the accumulation of Hsp70, a molecular chaperone crucial to cellular protein folding, tissue repair and immune response of living organisms, including Penaeid shrimp.

Effects of cypermethrin on the hepatic transcriptome and proteome of the red claw crayfish Cherax quadricarinatus

Cypermethrin (CYP) is a synthetic pyrethroid broadly used for pest control, however, it is extremely toxic to aquatic organisms. To assess the toxicity of CYP in red claw crayfish Cherax quadricarinatus, transcriptional and proteomic approaches combining two-dimensional polyacrylamide gel electrophoresis and tandem mass spectrometry were used to compare the hepatic expression profiles. A total of 41,349 unigenes and 8839 differentially expressed genes (DEGs) were obtained, which were enriched in the process. The category of 779 (0.625 ng L^-1 CYP vs Con), 1963 (1.25 vs Con), and 2066 (1.25 vs 0.625) DEGs were screened. All findings suggested that CYP can induce antioxidant and biotransformation modulation variations in C. quadricarinatus to resist immunotoxicity and oxidative damages. The category of 196 (0.625 ng L^-1 CYP vs Con) specific proteins were differentially expressed: 24 proteins were upregulated, and 20 proteins were downregulated relative to CYP. Protein identification indicated the KEGG pathways of the human immunodeficiency virus 1 infection, insulin signaling pathway, and influenza A enriched. From the differential expression of the selected nine proteins, the increased Loc113824800, Rps19, Atp2, Rps10, Hsp40, Brafldraft_124327, and the decreased Loc117331934, Loc113213835, and Loc106806551 revealed. While for the verification of the eight genes in transcriptome and the above nine genes in proteomic, specifically, gpx5, ggt, loc106458463, chelonianin decreased in the 0.625 ng L^-1 CYP group. The transcripts of loc113816050, akr1d1 and gst, chelonianin and loc108675455 decreased and increased in the 1.25 ng L^-1 CYP group, respectively. The present study reflects the overall change in cellular structure and metabolism related to the resistance of pyrethroid insecticides.

Full-length transcriptome sequencing combined with RNA-seq analysis revealed the immune response of fat greenling (Hexagrammos otakii) to Vibrio harveyi in early infection

Fat greenling (Hexagrammos otakii) is an important commercial marine fish species cultured in northeast Asia, but its available gene sequences are limited. Vibrio harveyi is a causative agent of vibriosis in fat greenling and also causes severe losses to the aquaculture industry in China. In order to obtain more high-quality transcript information and investigate the early immune response of fat greenling against V. harveyi, the fish were artificially infected with V. harveyi, and five sampling points were set within 48 h. Iso-Seq combined with RNA-Seq were applied in the comprehensive transcriptome analysis of V. harveyi-infected fat greenling. Total 42,225 consensus isoforms were successfully extracted from the result of Iso-Seq, and more than 19,000 ORFs were predicted. In addition, total three modules were identified by WGCNA which significantly positive correlated to the infection time, and the KEGG analysis showed that the immune-related genes in these modules mainly enriched in TLR signaling pathway, NF-κB signaling pathway and Endocytosis. The activation of inflammation and endocytosis was the most significant characteristics of fat greenling immune response during the early infection. Based on the WGCNA, a series of high-degree nodes in the networks were identified as hub genes. The protein structures of cold-inducible RNA-binding protein (CIRBP), poly [ADP-ribose] polymerase 1 (PARP1) and protein arginine N-methyl transferase 1 (PRMT1) were subsequently found to be highly conserved in vertebrate, and the gene expression pattern of CIRBP, PARP1, PRMT1 and a part of TLR/NF-κB pathway-related genes indicated that these proteins might have similar biological functions in regulation of inflammatory response in teleost fish. The results of this study provided the first systematical full-length transcriptome profile of fat greenling and characterized its immune responses in early infection of V. harvey, which will serve as the foundation for further exploring the molecular mechanism of immune defense against bacterial infection in fat greenling.

HSP70 and HSP90 are involved in shrimp Penaeus vannamei tolerance to AHPND-causing strain of Vibrio parahaemolyticus after non-lethal heat shock

Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus carrying toxin-producing plasmid, has led to severe mortalities in farmed penaeid shrimp throughout Asia. Previous studies reported that a non-lethal heat shock (NLHS) could enhance disease tolerance in aquatic animals. Here, we investigate whether the NLHS could enhance the survival of shrimp Penaeusvannamei upon challenge with an AHPND-causing strain of V. Parahaemolyticus (VP_AHPND). Two NLHS conditions, acute and chronic NLHSs, were used. The former abruptly exposed the juveniles shrimp from 28 °C to 38 °C for 30 min only once whereas the latter exposed the shrimp to 38 °C for 5 min every day for 7 days. The treated shrimp were, then, challenged with VP_AHPND at day 3, day 7, and day 30 during the recovery time after the treatment. The results showed that the shrimp exposed to either acute or chronic NLHS had higher survival rate (>50%) than that of the non-heated shrimp control (20%) when they were challenged with VP_AHPND at day 3 recovery time. However, only those exposed to chronic NLHS showed the VP_AHPND protection at day 7 and day 30 recovery times. Furthermore, the qRT-PCR analysis revealed that the expression of heat shock proteins, LvHSP70, LvHSP90 as well as other immune-related genes, LvproPO and LvCrustin, were induced upon exposure of shrimp to chronic NLHS. Interestingly, gene silencing of LvHSP70 and LvHSP90 eliminated the VP_AHPND tolerance in the chronic NLHS shrimp and had decreasing PO activity suggesting that these LvHSPs played crucial roles in bacterial defense in shrimp. All together, we show for the first time that the NLHS enhance the shrimp tolerance to VP_AHPND infection and this is likely mediated by the induction of LvHSP70, LvHSP90 and subsequent activation of the proPO system.

Roles of Hsp70s in Stress Responses of Microorganisms, Plants, and Animals

Hsp70s (heat shock protein 70s) are a class of molecular chaperones that are highly conserved and ubiquitous in organisms ranging from microorganisms to plants and humans. Most research on Hsp70s has focused on the mechanisms of their functions as molecular chaperones, but recently, studies on stress responses are coming to the forefront. Hsp70s play key roles in cellular development and protecting living organisms from environmental stresses such as heat, drought, salinity, acidity, and cold. Moreover, functions of human Hsp70s are related to diseases including neurological disorders, cancer, and virus infection. In this review, we provide an overview of the specific roles of Hsp70s in response to stress, particularly abiotic stress, in all living organisms.