Cloning and expression of a heat shock protein (HSP) 90 gene in the haemocytes of Crassostrea hongkongensis under osmotic stress and bacterial challenge

Understanding the molecular mechanism of arsenic and ammonia toxicity and high-temperature stress in Pangasianodon hypophthalmus

The current investigation explores the mechanisms of ammonia and arsenic toxicity, along with high-temperature stress, which other researchers rarely addressed. Pangasianodon hypophthalmus was exposed to low doses of ammonia and arsenic (1/10th of LC50, 2.0 and 2.68 mg L-1, respectively) and high temperature (34 °C) for 105 days. The following treatments were applied: control (unexposed), arsenic (As), ammonia (NH3), ammonia + arsenic (NH3 + As), ammonia + temperature (NH3 + T), and NH3 + As + T. Cortisol levels significantly increased with exposure to ammonia (NH3), arsenic (As), and high temperature (34 °C) compared to the unexposed group. Heat shock protein (HSP 70), inducible nitric oxide synthase (iNOS), and metallothionein (MT) gene expressions were notably upregulated by 122-210%, 98-122%, and 64-238%, respectively, compared to the control. Neurotransmitter enzymes (acetylcholine esterase, AChE) were significantly inhibited by NH3 + As + T, followed by other stressor groups. The apoptotic (caspase, Cas 3a and 3b) and detoxifying (cytochrome P450, CYP P450) pathways were substantially affected by the NH3 + As + T group. Immune (total immunoglobulin, Ig; tumor necrosis factor TNFα; and interleukin IL) and growth-related genes (growth hormone, GH; growth hormone regulator, GHR1 and GHRβ; myostatin, MYST and somatostatin, SMT) were noticeably upregulated by NH3 + As + T, followed by other stress groups, compared to the control group. Weight gain %, protein efficiency ratio, feed efficiency ratio, specific growth rate, and other growth attributes were significantly affected by low doses of ammonia, arsenic, and high-temperature stress. Albumin, total protein, globulin, A:G ratio, and myeloperoxidase (MPO) were highly affected by the As + NH3 + T group. Blood profiling, including red blood cells (RBC), white blood count (WBC), and hemoglobin (Hb), were also impacted by stressor groups compared to the control group. Genotoxicity, as DNA damage, was significantly higher in groups exposed to NH3 + As + T (89%), NH3 + T (78%), NH3 (73), NH3 + As (71), and As (68%). The bioaccumulation of arsenic was substantially higher in liver and kidney tissues. The present study contributes to understanding the toxicity mechanisms of ammonia and arsenic, as well as high-temperature stress, through different gene expressions, biochemical attributes, genotoxicity, immunological status, and growth performance of P. hypophthalmus.

A Review on the Involvement of Heat Shock Proteins (Extrinsic Chaperones) in Response to Stress Conditions in Aquatic Organisms

Heat shock proteins (HSPs) encompass both extrinsic chaperones and stress proteins. These proteins, with molecular weights ranging from 14 to 120 kDa, are conserved across all living organisms and are expressed in response to stress. The upregulation of specific genes triggers the synthesis of HSPs, facilitated by the interaction between heat shock factors and gene promoter regions. Notably, HSPs function as chaperones or helper molecules in various cellular processes involving lipids and proteins, and their upregulation is not limited to heat-induced stress but also occurs in response to anoxia, acidosis, hypoxia, toxins, ischemia, protein breakdown, and microbial infection. HSPs play a vital role in regulating protein synthesis in cells. They assist in the folding and assembly of other cellular proteins, primarily through HSP families such as HSP70 and HSP90. Additionally, the process of the folding, translocation, and aggregation of proteins is governed by the dynamic partitioning facilitated by HSPs throughout the cell. Beyond their involvement in protein metabolism, HSPs also exert a significant influence on apoptosis, the immune system, and various characteristics of inflammation. The immunity of aquatic organisms, including shrimp, fish, and shellfish, relies heavily on the development of inflammation, as well as non-specific and specific immune responses to viral and bacterial infections. Recent advancements in aquatic research have demonstrated that the HSP levels in populations of fish, shrimp, and shellfish can be increased through non-traumatic means such as water or oral administration of HSP stimulants, exogenous HSPs, and heat induction. These methods have proven useful in reducing physical stress and trauma, while also facilitating sustainable husbandry practices such as vaccination and transportation, thereby offering health benefits. Hence, the present review discusses the importance of HSPs in different tissues in aquatic organisms (fish, shrimp), and their expression levels during pathogen invasion; this gives new insights into the significance of HSPs in invertebrates.

Sub-chronic exposure of Oreochromis niloticus to environmentally relevant concentrations of smaller microplastics: Accumulation and toxico-physiological responses

This study assesses the accumulation and toxic effects of environmentally relevant concentrations (0.01, 0.1 and 1 mg/L) of polystyrene MPs (1 µm) in Oreochromis niloticus (Nile tilapia) for 14 days. The results showed that 1 µm PS-MPs accumulated in the intestine, gills, liver, spleen, muscle, gonad and brain. RBC, Hb and HCT showed a significant decline, while WBC and PLT showed a significant increase after the exposure. Glucose, total protein, A/G ratio, SGOT, SGPT and ALP showed significant increments in 0.1 and 1 mg/L of PS-MPs treated groups. The increase in cortisol level and upregulation of HSP70 gene expression in response to MPs exposure indicate MPs-mediated stress in tilapia. MPs-induced oxidative stress is evident from reduced SOD activity, increased MDA levels and upregulated P53 gene expression. The immune response was enhanced by inducing respiratory burst activity, MPO activity and serum TNF-α and IgM levels. MPs exposure also led to down-regulation of CYP1A gene and decreased AChE activity, GNRH and vitellogenin levels, indicating the toxicity of MPs on the cellular detoxification mechanism, nervous and reproductive systems. The present study highlights the tissue accumulation of PS-MP and its effects on hematological, biochemical, immunological and physiological responses in tilapia with low environmentally relevant concentrations.

Seasonality in Synergism with Multi-Pathogen Presence Leads to Mass Mortalities of the Highly Endangered Pinna nobilis in Greek Coastlines: A Pathophysiological Approach

Mortalities of Pinna nobilis populations set at risk the survival of the species from many Mediterranean coastline habitats. In many cases, both Haplosporidium pinnae and Mycobacterium spp. are implicated in mass mortalities of P. nobilis populations, leading the species into extinction. In the context of the importance of these pathogens' role in P. nobilis mortalities, the present study investigated two Greek populations of the species hosting different microbial loads (one only H. pinnae and the second both pathogens) by the means of pathophysiological markers. More specifically, the populations from Kalloni Gulf (Lesvos Island) and from Maliakos Gulf (Fthiotis), seasonally sampled, were chosen based on the host pathogens in order to investigate physiological and immunological biomarkers to assess those pathogens' roles. In order to determine if the haplosporidian parasite possesses a major role in the mortalities or if both pathogens are involved in these phenomena, a variety of biomarkers, including apoptosis, autophagy, inflammation and heat shock response were applied. The results indicated a decreased physiological performance of individuals hosting both pathogens in comparison with those hosting only H. pinnae. Our findings provide evidence for the synergistic role of those pathogens in the mortality events, which is also enhanced by the influence of seasonality.

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.

Impacts of tea polyphenols on growth, antioxidant capacity and immunity in juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed high-lipid diets

The experiment aimed to investigate the alteration of tea polyphenols (TP) in growth and immunity for hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed high-lipid diets. Six concentrations of TP (0, 0.01, 0.02, 0.04, 0.08, 0.16%, named TP1 (basic diet control), TP2, TP3, TP4, TP5, TP6) were supplied in isonitrogenous (51%) and isolipidic (16.7%) experimental diets. These diets were fed to the juvenile grouper (8.68 ± 0.22 g) for 8 weeks. The results showed that dietary TP significantly increased the weight gain rate and specific growth rate (P < 0.05), compared with the control group. The protein efficiency ratio in TP4 group was significantly higher than that of the control group (P < 0.05). TP supplement in high-lipid diets increased antioxidant capacity in the serum (CAT, GSH-Px, T-AOC) and liver (SOD, CAT, GSH-Px, T-AOC). Additionally, dietary TP decreased oxidative stress (ROS, MDA) and improved immunity (ACP, AKP, LYS, IgM) in the liver. The histology of hepatic tissue indicated that dietary TP alleviated pathological symptoms caused by high-lipid diets. Compared with the control group, appropriate dietary TP significantly up-regulated expression of sod, cat, gsh-px, nrf2, keap1, hsp70, hsp90, myd88, tnfα and down-regulated expression of tlr22, il8, il1β, il10 in the liver (P < 0.05). In the head kidney, expression of myd88, il1β, tnfα and il6 were significantly up-regulated and expression of tlr22 and il10 were significantly down-regulated by dietary TP (P < 0.05). After the challenge of Vibrio harveyi, survival rate in higher doses of TP group (TP4 ∼ TP6) was evidently higher, compared with the control group. In conclusion, TP supplement in high-lipid diets improved antioxidant capacity and enhanced immunity of grouper. We speculate that TP may play the role of an immunostimulant, enhancing immunity and disease resistance by cytokine-medicated immune responses. Based on the second-order regression, 0.092-0.106% tea polyphenols were recommended in juvenile grouper high-lipid diets.

The positive effects of dietary inositol on juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) fed high-lipid diets: Growthperformance, antioxidant capacity and immunity

The objective of the present research was to assess the influence of inositol supplementation on growth performance, histological morphology of liver, immunity and expression of immune-related genes in juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu). Hybrid grouper (initial weight 6.76 ± 0.34 g) were fed isonitrogenous and isolipidic diets (16%) with various inositol levels of 0.17 g/kg (J1, the control group), 0.62 g/kg (J2), 1.03 g/kg (J3), 1.78 g/kg (J4), 3.43 g/kg (J5), 6.59 g/kg (J6), respectively. The growth experiment lasted for 8 weeks. The results indicated that dietary inositol had a significant promoting effect on final mean body weight of the J5 and J6 groups and specific growth rate (SGR) of the J3, J4, J5 and J6 groups (P < 0.05). In the serum, superoxide dismutase (SOD) of the J4 group became significantly active compared with that of the control group (P < 0.05), while aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (AKP) activities in the inositol-treated groups showed distinctly decreased compared with those of the control group (P < 0.05). In the liver, dietary inositol could significantly increase the activities of SOD, catalase (CAT), lysozyme (LYZ) and the contents of total antioxidative capacity (T-AOC) and immunoglobulin M (IgM) (P < 0.05), and distinctly reduce the content of malondialdehyde (MDA) as well as reactive oxygen species (ROS) (P < 0.05). Compared with the control group, the damaged histological morphology of the liver was relieved and even returned to normal after an inositol increase (0.4-3.2 g/kg). In the liver, the remarkable up-regulation of SOD, CAT, glutathione peroxidase (GPX), heat shock protein70 (HSP70) and heat shock protein90 (HSP90) expression levels were stimulated by supply of inositol, while interleukin 6 (IL6), interleukin 8 (IL8) and transforming growth factor β (TGF-β) expression levels were down-regulated by supply of inositol. In head kidney, the mRNA of toll-like receptor 22 (TLR22), myeloid differentiation factor 88 (MyD88) and interleukin 1β (IL1β) expression levels were significantly down-regulated (P < 0.05), which could further lead to remarkable down-regulation of IL6 and tumor necrosis factor α (TNF-α) expression (P < 0.05). These results indicated that high-lipid diets with supply of inositol promoted growth, increased the antioxidant capacity, and suppressed the inflammation of the liver and head kidney by inhibiting the expression of pro-inflammation factors (IL6, IL8, TGF-β and TNF-α). In conclusion, these results indicated that dietary inositol promoted growth, improved antioxidant capacity and immunity of hybrid grouper fed high-lipid diets. Based on SGR, broken-line regression analysis showed that 1.66 g/kg inositol supply was recommended in high-lipid diets of juvenile grouper.

Molecular Cloning of Heat Shock Protein 60 (SpHSP60) from Schizothorax prenanti and the Gene Expressions of Four SpHSPs during Lipopolysaccharide (LPS) Infection

Heat shock proteins (HSPs) play a key role in anti-stress and immune processes and are associated with autoimmune diseases. In order to explore the immunological role of HSPs from Schizothorax prenanti (S. prenanti), SpHSP60 was cloned for the first time in this study, and the gene expressions of SpHSP27, SpHSP60, SpHSP70 and SpHSP90 in the hepatopancreas, head kidney, hindgut and spleen were analyzed by quantitative real-time PCR (qPCR) after treatment with lipopolysaccharide (LPS). The open reading frame of the SpHSP60 gene (GenBank accession number ON245159) is 1728 bp. It encodes a protein of 575 amino acids. Its C-terminus is a highly conserved and repeated glycine sequence, which is an important cofactor in ATP binding. Compared with the control group, most of the SpHSPs were significantly upregulated in the tissues examined at 12 or 24 h after LPS challenge. The most abundant expression of SpHSP70 was found in the head kidney at 24 h after LPS injection, followed by SpHSP27 in the spleen at 24 h; both of these SpHSPs displayed strong expression under the LPS stresses, about 20–70 fold more than that of SpHSP60 and SpHSP90. The temporal expression patterns of the four SpHSP genes were different in the four tissues examined. Taken together, the results suggest that SpHSP27, SpHSP60, SpHSP70 and SpHSP90 participate in innate immunity stimulated by LPS, and the response intensity of the SpHSPs was organ-specific, indicating they could provide early warning information against bacterial infection. The findings in our study will contribute to better understanding the biological processes and important roles of SpHSPs involved in defending against pathogenic bacterial challenge.

Genome-wide identification and low-salinity stress analysis of the Hsp70 gene family in swimming crab (Portunus trituberculatus)

No genome-wide identification and expression analysis have been performed on the heat shock protein 70 (Hsp70) gene family, which is essential to key cellular processes and responses to environmental change, in decapods. In the present study, we identified nine members of the Hsp70 gene family within the genome of swimming crab (Portunus trituberculatus) and provided insights into their response to long-term low-salinity stress. Results demonstrated that gene structure and motifs are conserved among members of this gene family in P. trituberculatus. Under low-salinity stress, the expression of this gene family in the gill of P. trituberculatus showed that hsc70l.2 was significantly upregulated, hyou1 was significantly downregulated. The hsc70l.4 was not expressed. Furthermore, selection test on duplicated genes showed a negative selection on hsc70l.1, hsc70l.2, hsc70l.3, and hsc70l.4, suggesting functional redundancy. This may be the first study that systematically identified and analyzed the Hsp70 gene family in decapods. These results can provide fundamental data for the biological research of P. trituberculatus and enhance understanding of the biological function of Hsp70 in crustaceans adapting to salinity changes.

Identification, evolution and expression analyses of mapk gene family in Japanese flounder (Paralichthys olivaceus) provide insight into its divergent functions on biotic and abiotic stresses response

Mitogen-activated protein kinase (MAPK) are a series of serine/threonine protein kinases showing evolutionary conservation, which can be activated by many stimulus signals and then transfer them from cell membrane to nucleus. MAPKs regulate a variety of biological processes, such as apoptosis, hormone signaling and immune response. In this study, 14 putative mapk genes in Japanese flounder were identified, and their basic physical and chemical properties were characterized. Phylogenetic analysis showed that mapk genes were divided into three main subfamilies, including ERK, JNK and the p38 MAPK. Selection pressure analysis revealed they were evolutionarily-constrained and undergone strong purifying selection. Gene structure and conserved protein motif comparison suggested high levels of conservation in members of mapk gene family. The expression patterns were further investigated in each embryonic and larval development stages and different tissues. In addition, RNA-seq analyses after bacteria and temperature stresses suggested mapk genes had different expression patterns. Three mapk genes showed significant differences in response to E. tarda challenge and five were induced significantly after temperature stress, indicating their potential functions. This systematic analysis provided valuable information for further understanding of the regulation mechanism of mapk gene family under different stresses in Japanese flounder.

Effect of temperature on food consumption, immune system, antioxidant enzymes, and heat shock protein 70 of Channa punctata (Bloch, 1793)

The impact of water temperature on the physiology of Channa punctata (Bloch, 1793) was evaluated in the present study. Fish were acclimated at 25 ± 1 °C and then exposed at six different temperatures: 10, 15, 20, 25, 30, and 35 °C. C. punctata exposed at 10, 15, and 20 °C showed 30, 21, and 11% reduced food consumption, respectively compared to 25 °C. Significantly higher respiratory burst and myeloperoxidase activities were found in fish exposed at 20 and 25 °C after 12 h of exposure compared to other treatments. Nitric oxide synthase was significantly higher at 25 °C after 12 h and at 25 and 30 °C exposed fish after 7 days compared to others. The reduced glutathione level was significantly higher at 25 °C compared to other treatments after 7 days of exposure. The thiobarbituric acid reactive substances level was minimum at 25 °C. Significantly lower antioxidant enzymes, catalase, glutathione peroxidase, and glutathione S-transferase were found in gills of fish exposed at 25 °C compared to others in both samples. The highest antioxidant enzyme levels were found at 10 °C. Heat shock protein (Hsp) 70 levels were significantly lower in liver and muscle of fish exposed at 25 °C compared to other treatments. The Hsp level was significantly higher at 35 and 30 °C exposed fish compared to others after 12 h, and the level reduced after 7 days in these treatments. Thermal stress affects food consumption rate, immune system, antioxidant enzymes, and enzyme systems in fish. The elevated Hsp70 level serves as a biomarker of stress in C. punctata. Graphical Abstract.

Immune and physiological responses of mud crab (Scylla paramamosain) under air exposure

The immune and physiological responses of mud crab (Scylla paramamosain) under air exposure were studied. The results showed that air exposure increased plasma activities of AST, ALT, ALP. There was a significant increase in glucose (GLU) and malondialdehyde (MDA) levels after air exposure. The transcript levels of SOD, CAT, HSP90, HSP70, p53, and hypoxia-inducible factor-1 (HIF-1) were induced by air exposure. Furthermore, caspase-3 transcript significantly increased at 48 and 72 h, while it significantly decreased at 96 h and 120 h under air exposure. These results suggested that oxidative stress occurred in the prolonged period of air exposure. HIF-1 and p53 signaling pathways played an important role under air exposure.

Cloning and expression of three heat shock protein genes in the gills of Cherax quadricarinatus responding to bacterial challenge

Cherax quadricarinatus is seriously affected by multiple types of pathogens, including bacteria and viruses, and has been widely transplanted around the world. Heat shock proteins (Hsps) are a group of molecular chaperones that play important roles in promoting the proper refolding and blocking the aggregation of denatured proteins. In this study, CqHsp60, CqHsp70 and CqHsp90 from C. quadricarinatus were cloned, and their expression patterns were analysed. The CDS (coding sequence) lengths of the CqHsp60, CqHsp70 and CqHsp90 genes were 1731 bp, 1932 bp and 2199 bp, encoding 576, 643 and 732 amino acids, respectively. CqHsp60 was 99.13%, 98.78% and 88.63% identical to the corresponding sequences of Cherax cainii, Cherax destructor and Eriocheir sinensis, respectively. CqHsp70 showed 99.84%, 92.73% and 91.58% identity to the corresponding sequences of C. cainii, C. destructor and E. sinensis, while CqHsp90 was 98.25%, 98.51% and 91.41% identical with those of C. cainii, C. destructor and E. sinensis, respectively. The expression patterns of the three CqHsps were different between males and females. CqHsp60 and CqHsp70 exhibited the highest expression in the hepatopancreas of males and the gonads of females, and CqHsp90 presented the highest expression in the gonads of males and hepatopancreas of females. After pathogenic inoculation, the death trend of C. quadricarinatus at different time points was the same in association with different pathogens, with most deaths occurring within 6 h post-inoculation. The trend of CqHsp transcription at different time points was the same among the groups treated with Vibrio alginolyticus, Vibrio parahemolyticus and Aeromonas hydrophila, exhibiting upregulation first and then downregulation. The expression of CqHsp60 and CqHsp70 in the gills of living C. quadricarinatus was less than 3.5 times that in the PBS group, but in the gills of dead C. quadricarinatus under A. hydrophila inoculation, its expression was more than 5-9 times that in the PBS group. CqHsp90 expression changed dramatically in the V. alginolyticus, V. parahemolyticus and A. hydrophila groups, in which it exceeded 50 times the level in the PBS group. These results indicated that CqHsps could induce the activation of the immune system within a short time and that CqHsp90 could be used as a more effective molecular biomarker than CqHsp70 and CqHsp60 in a pathogenic bacterium-polluted environment.

Effects of thermal stress on mortality and HSP90 expression levels in the noble scallops Chlamys nobilis with different total carotenoid content

The noble scallop Chlamys nobilis is an economically important marine bivalve cultivated in the southern sea of China since the 1980s. Unfortunately, mass mortality of this scallop species often occurs in summer. The present study was conducted to investigate whether the expression of heat shock protein 90 (HSP90) and level of carotenoids could enhance high-temperature stress resistance in scallop. First, the HSP90 homolog of C. nobilis (designated CnHSP90) was identified and cloned. The complete cDNA sequence of CnHSP90 was 2631 bp, including a 2181-bp open reading frame (ORF) encoding a 726 amino acid polypeptide with five HSP90 family signatures, and sharing high homology with members of the HSP90 family. CnHSP90 was ubiquitously expressed in all examined tissues including the intestine, kidney, adductor, mantle, gill, and gonad, with the highest in the gonad. Golden and brown scallops, which contain significantly different total carotenoid content (TCC), were subjected to acute thermal challenge, and the LTE50 (semi-lethal temperature at 36 h heat shock) and LTI50 (semi-lethal time after heat shock) as well as the correlation between CnHSP90 gene expression and TCC were determined. The LTE50 of golden scallop (32.14 °C) was higher than that of brown scallops (31.19 °C), with longer LTI50 at all tested temperatures, indicating that golden scallops were more resistant to thermal stress than brown scallops. Similarly, the mRNA expression levels of CnHSP90 in gill of golden scallops were significantly higher (P < 0.05) than that of brown scallops at 6, 12, 24, and 36 h, with a strong positive correlation between CnHSP90 expression level and TCC. This suggests that both carotenoids and HSP90 levels could improve thermal resistance in the noble scallops.

Towards a better understanding of allograft-induced stress response in the pearl oyster Pinctada fucata martensii: Insights from iTRAQ-based comparative proteomic analysis

Implantation of a spherical nucleus into a recipient oyster is a critical step in artificial pearl production. The implanted nucleus is known to trigger cellular stress responses at several levels, yet the molecular mechanism underpinning physiological adaptation of the pearl oysters to nucleus implantation is still poorly understood. In this study, we took advantage of the iTRAQ-based proteomics and LC-MS/MS approach to look into allograft induced gene regulation at the protein expression level in the pearl oyster Pinctada fucata martensii, across a period of 30 days following nucleus implantation. A wide variety of proteins, including a group of immune-related proteins such as E3 ubiquitin-ligase and heat shock proteins, exhibited differential expression in response to the surgical operation. Further comparisons between different sampling points revealed that GO terms including "translation" and "oxidation-reduction process" and KEGG pathways including "glycolysis/gluconeogenesis" and "pyruvate metabolism" were significantly enriched at several time points, indicating the important roles of these molecular events in the stress response of pearl oysters to nucleus implantation. In addition, considerable discrepancy between protein expression level and gene transcript abundancy was identified, as only a few genes showed at least 2-fold expression changes at both proteomic and transcriptomic levels. The result implies that post-transcriptional gene regulation for the key proteins may represent an important aspect of allograft-induced stress response in the pearl oysters. Taken together, the data obtained would contribute to a deeper understanding of the molecular mechanisms enabling stress adaptation of the pearl oysters in response to nucleus implantation.

Expression pattern of heat shock protein 90AB (HSP90AB) and stress-inducible protein 1 (Stip1) during spermatogenesis of mudskipper Boleophthalmus pectinirostris

Heat shock protein 90 (HSP90), which functions as a molecular chaperone, plays an important role in reproduction and cellular defense. Among the HSP90 family, HSP90AB is an important isoform. Stress-inducible protein 1 (Stip1) acts as a co-chaperone that mediates interactions with HSP90 and appears to be a player in spermatogenesis and stress response. However, the functions of both HSP90 and Stip1 during spermatogenesis and heat stress response in Boleophthalmus pectinirostris remain unknown. We investigated mRNA expression patterns of HSP90AB and Stip1 under heat stress conditions. The results showed that mRNA levels of HSP90AB and Stip1 were significantly upregulated in the gill and liver tissues, indicating that HSP90AB and Stip1 appear to play roles in protection against heat stress. Then we cloned the complete cDNA of HSP90AB and Stip1, which have product lengths of 2546 and 2652 bp, respectively. The predicted secondary and tertiary structures of B. pectinirostris. HSP90AB and Stip1 contain conserved domains. We investigated the expression patterns of HSP90AB and Stip1 in different tissues by quantitative real-time polymerase chain reaction, HSP90AB and Stip1 were found to be ubiquitously expressed in all major tissues and exhibited varying expression levels, indicating that HSP90AB and Stip1 have conserved biological functions. HSP90AB and Stip1 were found to be strongly expressed in the testis, indicating their special roles in this organ. We also tracked the dynamic locations of germinal cells using in situ hybridization. Results from in situ hybridization and immunofluorescence localization showed that both mRNA transcripts and proteins of HSP90AB and Stip1 were ubiquitously expressed in spermatocytes, spermatids, and spermatozoa, indicating that HSP90AB and Stip1 are both involved in spermatogenesis.

The GRP94 gene of Yesso scallop (Patinopecten yessoensis): Characterization and expression regulation in response to thermal and bacterial stresses

The 94-kDa glucose-regulated protein (GRP94) belonging to the HSP90 family is an endoplasmic reticulum (ER) chaperone. It plays critical roles in ER quality control, and has been implicated as a specialized immune chaperone to regulate both innate and adaptive immunity. In this study, we identified and characterized a GRP94 gene (PyGRP94) from Yesso scallop (Patinopecten yessoensis). The protein sequence of PyGRP94 is highly conserved with its homologs in vertebrates, with a signal sequence in N-terminal, an ER retrieval signal sequence in C-terminal and a HATPase_c domain. Expression analysis suggests that PyGRP94 transcripts in early embryos are maternally derived and the zygotic expression is started from D-shaped larvae. This gene is also expressed in almost all the adult tissues examined except smooth muscle, with the highest expression level in hemocytes. Besides, PyGRP94 was demonstrated to be induced by heat shock and both Gram-positive (Micrococcus luteus) and Gram-negative (Vibrio anguillarum) bacterial infection, with much more dramatic changes being observed after V. anguillarum challenge. Our results suggest the involvement of PyGRP94 in response to thermal stress, and that it might play an important role in the innate immune defense of scallop.

Effect of tributyltin chloride (TBT-Cl) exposure on expression of HSP90β1 in the river pufferfish (Takifugu obscurus): Evidences for its immunologic function involving in exploring process

HSP90β1 (known as glyco-protein 96, GP96) is a vital endoplasmic reticulum (ER) depended chaperonin among the HSPs (heat shock proteins) family. Furthermore, it always processes and presents antigen of the tumor and keeps balance for the intracellular environment. In the present study, we explored the effect of tributyltin chloride (TBT-Cl) exposure on HSP90β1 expression in river pufferfish, Takifugu obscurus. The full length of To-HSP90β1 was gained with 2775 bp in length, with an ORF (open reading frame) encoding an 803 aa polypeptide. A phylogenetic tree was constructed and showed the close relationship to other fish species. The HSP90β1 mRNA transcript was expressed in all tissues investigated with higher level in the gill and liver. After the acute and chronic exposure of TBT-Cl, the To-HSP90β1 mRNA transcript significantly was up-regulated in gills. Moreover, the histology study indicated the different injury degree of TBT-Cl in liver and gill. Immunohistochemistry (IHC) staining results implied the cytoplasm reorganization after TBT-Cl stress and the function of immunoregulation for To-HSP90β1 to TBT-Cl exposure. All the results indicated that HSP90β1 may be involved in the resistance to the invasion of TBT-Cl for keeping autoimmune homeostasis.

Transcriptome Analysis of Epithelioma Papulosum Cyprini Cells Infected by Reovirus Isolated from Allogynogenetic Silver Crucian Carp

The present study aimed to identify differentially expressed genes (DEGs) and major signal transduction pathways that were related to the immune response of epithelioma papulosum cyprinid (EPC) cells to reoviruses isolated from allogynogenetic silver crucian carp. The study also lays a theoretical foundation for the pathogenesis and immunity of the reovirus, which is helpful to the breeding of cyprinids fish. Reovirus infected and uninfected EPC cells were analyzed by using a new-generation high-throughput sequencing technology. DEGs were identified, annotated, and classified, and the signal pathways involved in the response to reovirus infection were identified by using bioinformatics tool. The data were assembled into 92,101 contigs with an average length of 835.24 bp and an N50 value of 1432 nt. Differential expression analysis of all the genes identified 3316 DEGs at a false discovery rate (FDR) of <0.01 and a fold-change of ≥3, of which 1691 were upregulated genes, 1625 were downregulated, and about 305 were immune-related genes. Gene Ontology (GO) enrichment analysis resulted in the annotation of 3941 GO terms, including 2719 biological processes (37,810 unigenes), 376 cell components (7943 unigenes), and 846 molecular functions (11,750 unigenes). KEGG metabolic pathway analysis matched the DEGs from pre-and post-infection EPC cells to 193 pathways, of which 35 were immune-related, including the Toll-like receptor, cytokine-cytokine receptor interaction, and the JAK-STAT signaling pathways.

HSP60 and HSP90β from blunt snout bream, Megalobrama amblycephala: Molecular cloning, characterization, and comparative response to intermittent thermal stress and Aeromonas hydrophila infection

Heat shock proteins (HSPs) play critical roles in the process of anti-stress and immunity and are implicated in autoimmune diseases. In order to understand the comparative stress responses of HSP60 and HSP90β under intermittent thermal stress and Aeromonas hydrophila infection, we cloned their full-length cDNAs from Megalobrama amblycephala liver, predicted their secondary and tertiary structure, and examined their tissue-specific expression patterns. The full length of HSP60 and HSP90β cDNAs indicated that they included all signature sequences of corresponding protein families. They showed high homology to their counterparts in other species, and were consistent with the known classification of fishes based on phylogenetic analysis. HSP60 showed the highest expression in head-kidney, brain, and gill, while HSP90β presented higher in hindgut, liver, and brain. Significant mRNA expression differences were determined between HSP60 and HSP90β in tissues of bladder, liver, heart, and gill. During thermal stress and recovery phase, the highest expression of them were observed at the first recovery for 2 d and 1 d, respectively. The expression between them were extremely significant difference during the first recovery and second stress period. After A. hydrophila infection, their expressions were extremely significantly upregulated. The significant upregulation and rapid response indicated that they were sensitive to thermal stress and bacterial challenge. This study demonstrated that HSP60 and HSP90β might participate in innate immune and environmental responses of M. amblycephala. It indicated that they could be used as biomarkers to test the stress caused by local aquaculture environment.

The oyster immunity

Oysters, the common name for a number of different bivalve molluscs, are the worldwide aquaculture species and also play vital roles in the function of ecosystem. As invertebrate, oysters have evolved an integrated, highly complex innate immune system to recognize and eliminate various invaders via an array of orchestrated immune reactions, such as immune recognition, signal transduction, synthesis of antimicrobial peptides, as well as encapsulation and phagocytosis of the circulating haemocytes. The hematopoietic tissue, hematopoiesis, and the circulating haemocytes have been preliminary characterized, and the detailed annotation of the Pacific oyster Crassostrea gigas genome has revealed massive expansion and functional divergence of innate immune genes in this animal. Moreover, immune priming and maternal immune transfer are reported in oysters, suggesting the adaptability of invertebrate immunity. Apoptosis and autophagy are proved to be important immune mechanisms in oysters. This review will summarize the research progresses of immune system and the immunomodulation mechanisms of the primitive catecholaminergic, cholinergic, neuropeptides, GABAergic and nitric oxidase system, which possibly make oysters ideal model for studying the origin and evolution of immune system and the neuroendocrine-immune regulatory network in lower invertebrates.

Effect of tributyltin on antioxidant ability and immune responses of zebrafish (Danio rerio)

Tributyltin (TBT) is a toxic compound released into aquatic ecosystems through antifouling paints. This study was designed to examine the effects of TBT on antioxidant ability and immune responses of zebrafish (Danio rerio). Three hundred sixty healthy zebrafish were randomly grouped into four groups and exposed to different doses of TBT (0, 1, 10 and 100ngL^-1). At the end of 8 weeks, the fish were sampled, and antioxidant capability, immune parameters and immune-related genes were assessed. The results showed that with an increase in TBT dose, the concentration of malonaldehyde in the liver was significantly increased (p<0.05), whereas the activities of total superoxide dismutase, catalase and glutathione peroxidase were significantly decreased (p<0.05) compared to the control. The activity and expression of lysozyme and the content of immunoglobulin M were significantly decreased compared to those of the fish exposed to 0ngL^-1 TBT (p<0.05). However, the expression of the HSP70, HSP90, tumor necrosis factor-α(TNF-α), interleukins (IL-1β, IL-6), and nuclear factor-kappa B p65 (NF-κ B p65) genes were all enhanced with an increase in TBT dose. The results indicated that TBT induced oxidative stress and had immunotoxic effects on zebrafish.

Molecular characterization and expression analysis of Hsp90 in Schizothorax prenanti

Aquatic animals suffer from various environmental stresses because the aquatic environment is a very complex system. To monitor the health status of fish, Hsp90 a potential early warning marker was determined in Schizothorax prenanti after infection with a bacterium. In this study, we cloned Hsp90 from S. prenanti for the first time. The full-length cDNA sequence of SpHsp90 was 2663 bp, contains an open reading frame of 2181 bp, and has a gene encoding 726 amino acids, an estimated molecular mass of 83.38 kDa, and a theoretical isoelectric point of 4.91. The SpHsp90 amino acid sequence has five conserved HSP90 family signatures and shares 87.0-95.5 % identity with other vertebrates. Phylogenetic analysis and structure comparison indicated that SpHsp90 should be a β isoform of the HSP90 family. SpHsp90 was ubiquitously expressed in all examined tissues, and the highest level of expression was in the kidney. After Streptococcus agalactiae infection, the level of SpHsp90 expression had significant changes (P < 0.05) in the hepatopancreas, spleen, kidney, and blood. The expression increased to the highest level at 6 h in the blood and at 24 h in the hepatopancreas, spleen, and kidney. The results suggested that the SpHsp90 gene could be induced by S. agalactiae in S. prenanti and that SpHsp90 may be involved in resistance to bacterial infection and provide an early warning information. The kidney is the most suitable for detecting SpHsp90 after bacterial infection.

A novel biomarker for marine environmental pollution of HSP90 from Mytilus coruscus

Heat shock protein 90 (HSP90) is a conserved molecular chaperone contributing to cell cycle control, organism development and the proper regulation of cytosolic proteins. The full-length HSP90 cDNA of Mytilus coruscus (McHSP90, KT946644) was 2420bp, including an ORF of 2169bp encoding a polypeptide of 722 amino acids with predicted pI/MW 4.89/83.22kDa. BLASTp analysis and phylogenetic relationship strongly suggested McHSP90 was a member of HSP90 family, and it was highly conserved with other known HSP90, especially in the HSP90 family signatures, ATP/GTP-Binding sites and 'EEVD' motif. The mRNA of McHSP90 in haemolymph was upregulated in all treatments including Vibrio alginolyticus and Vibrio harveyi challenge, metals stresses (copper and cadmium) and 180 CST fuel exposure. All the results implied the expression of McHSP90 could be affected by Vibrio challenge and environmental stress, which might help us gain more insight into the molecular mechanism of HSP against adverse stresses in mollusca.

Selenium Deficiency Activates Heat Shock Protein Expression in Chicken Spleen and Thymus

Heat shock proteins (Hsps) are protective proteins present in nearly all species; they are used as biomarkers of various stress conditions in humans, animals, and birds. Selenium (Se) deficiency, which can depress the production of Hsps, can cause chicken tissue injuries. To investigate Hsp production, mRNA, and protein levels in Se-deficient chicken spleens and thymuses, a total of 180 1-day-old sea blue white laying hens (90 chickens/group) were harvested in two groups (the control group and the Se-deficient group) in 15, 25, 35, 45, and 55 days, respectively. The results showed that mRNA levels of Hsp27, Hsp40, Hsp60, Hsp70, and Hsp90 were significantly increased in the spleens and thymuses of the Se-deficient group compared to the control group. Further protein levels of Hsp60, Hsp70, and Hsp90 were also significantly increased in the spleen and thymus of the Se-deficient group compared to the control group. Meanwhile, the spleen expression ratio of Hsp40 mRNA level and Hsp70 protein level were higher in the Se-deficient group than other proteins. In the thymus, the Hsp90 mRNA level and Hsp60 protein expression level were the highest level in the Se-deficient group among other proteins. Based on these results, we concluded that Se deficiency could induce a protective stress response in chicken by means of promoting the mRNA and protein expression of Hsps, thus easing the effects of Se deficiency to some extent.

Identification of differentially expressed genes in Monochamus alternatus digested with azadirachtin

The pine sawyer beetle Monochamus alternatus Hope, a major forest insect pest, is the primary vector of the destructive forest pest pine wood nematode, Bursaphelenchus xylophilus. Azadirachtin, an active compound of neem, is biologically interesting because it represents a group of important, successful botanical pesticides. We provide insight into the molecular effects of azadirachtin on M. alternatus at the transcriptional level to provide clues about possible molecular-level targets and to establish a link between azadirachtin and insect global responses. We found that 920 and 9894 unique genes were significantly up- and down-regulated, respectively. We obtained expression patterns of the differentially expressed genes (DEGs), identifying 4247, 3488 and 7613 sequences that involved cellular components, molecular functions and biological processes, respectively, and showed that the DEGs were distributed among 50 Gene Ontology categories. The Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that the DEGs were enriched in 50 pathways. Detailed gene profile knowledge of the interaction of azadirachtin with M. alternatus should facilitate the development of more effective azadirachtin-based products against M. alternatus and other target Coleoptera. These results further enhance the value of azadirachtin as a potential insecticide of biological origin, as well as for other biological applications.

Characterization and comparison of proteomes of albino sea cucumber Apostichopus japonicus (Selenka) by iTRAQ analysis

Sea cucumber is a commercially important marine organism in China. Of the different colored varieties sold in China, albino sea cucumber has the greatest appeal among consumers. Identification of factors contributing to albinism in sea cucumber is therefore likely to provide a scientific basis for improving the cultivability of these strains. In this study, two-dimensional liquid chromatography-tandem mass spectrometry coupled with isobaric tags for relative and absolute quantification labeling was used for the first time to quantitatively define the proteome of sea cucumbers and reveal proteomic characteristics unique to albino sea cucumbers. A total of 549 proteins were identified and quantified in albino sea cucumber and the functional annotations of 485 proteins have been exhibited based on COG database. Compared with green sea cucumber, 12 proteins were identified as differentially expressed in the intestine and 16 proteins in the body wall of albino sea cucumber. Among them, 5 proteins were up-regulated in the intestine and 8 proteins were down-regulated in body wall. Gene ontology annotations of these differentially expressed proteins consisted mostly of 'biological process'. The large number of differentially expressed proteins identified here should be highly useful in further elucidating the mechanisms underlying albinism in sea cucumber.

Co-expression of heat shock protein (HSP) 40 and HSP70 in Pinctada martensii response to thermal, low salinity and bacterial challenges

Heat shock protein (HSP) 40 proteins are a family of molecular chaperones that bind to HSP70 through their J-domain and regulate the function of HSP70 by stimulating its adenosine triphosphatase activity. In the present study, a HSP40 homolog named PmHSP40 was cloned from the hemocytes of pearl oyster Pinctada martensii using EST and rapid amplification of cDNA ends (RACE) techniques. The full-length cDNA of PmHSP40 was 1251 bp in length, which included a 5' untranslated region (UTR) of 75 bp, an open reading frame (ORF) of a 663 bp, and a 3' UTR of 513 bp. The deduced amino acid sequence of PmHSP40 contains a J domain in the N-terminus. In response to thermal and low salinity stress challenges, the expression of PmHSP40 in hemocytes and the gill were inducible in a time-dependent manner. After bacterial challenge, PmHSP40 transcripts in hemocytes increased and peaked at 6 h post injection. In the gill, PmHSP40 expression increased, similar to expression in hemocytes; however, transcript expression of PmHSP40 was significantly up-regulated at 12 h post injection. Furthermore, the transcripts of PmHSP70 showed similar kinetics as that of PmHSP40, with highest induction during thermal, low salinity stress and bacterial challenges. Altogether these results demonstrate that PmHSP40 is an inducible protein under thermal, low salinity and bacterial challenges, suggesting its involvement in both environmental and biological stresses, and in the innate immunity of the pearl oyster.

The polymorphisms in the promoter of HSP90 gene and their association with heat tolerance of bay scallop

The heat shock protein 90 (HSP90) is a highly abundant and ubiquitous molecular chaperone which plays essential roles in many cellular processes. In the present study, the messenger RNA (mRNA) expressions of HSP90 after acute heat stress were investigated in two bay scallop populations (Argopecten irradians irradians and Argopecten irradians concentricus). The heat-resistant scallop A. i. concentricus, which is distributed in Zhanjiang, China, exhibited significantly higher induction of HSP90 compared with that of the heat-sensitive scallop A. i. irradians, which is distributed in Qinhuangdao, China. The promoter sequence of HSP90 gene from bay scallop (AiHSP90) was cloned, and the polymorphisms within this region were investigated by sequencing to analyze their association with heat tolerance. A total of six single nucleotide polymorphisms (SNPs), including -1167 T-C, -1023 A-C, -799 C-T, -774 A-G, -686 C-T, and -682 A-C, were identified in the amplified promoter region, and most of them affected the putative transcription factor binding sites except for locus -1167. All the six SNP sites were found to be associated with heat tolerance after Hardy-Weinberg equilibrium (HWE) and association analysis. Moreover, haplotypes CACACC and TCTATC were also found to be associated with heat tolerance based on the result of linkage disequilibrium and association analysis. The results provided insights into the molecular mechanisms underlying the thermal adaptation of different congener endemic bay scallops, which suggested that the increased heat tolerance of A. i. concentricus (compared with A. i. irradians) was associated with the higher expression of AiHSP90. Meanwhile, the six genotypes (-1167 TT, -1023 CC, -799 TT, -774 GG, -686 CC, and -682 AA) and two haplotypes (CACACC and TCTATC) could be used as potential markers for scallop selection breeding with higher heat tolerance.

Effects of fructooligosaccharide on immune response, antioxidant capability and HSP70 and HSP90 expressions of blunt snout bream (Megalobrama amblycephala) under high ammonia stress

This study aimed to determine the effects of fructooligosaccharide (FOS) on immune response, antioxidant capability and HSP70 and HSP90 mRNA expressions of blunt snout bream (Megalobrama amblycephala) under high ammonia stress. A total of 360 fish were randomly distributed into three groups (each with four replicates) and were fed three levels of FOS (0, 0.4 and 0.8 %) for 8 weeks. After the feeding trial, 24 fish per tank were exposed to ammonia at 10 mg L(-1). After stress, plasma cortisol and glucose levels of fish fed 0.4 % FOS were all significantly lower than that of the control group at 6 and 3 h, respectively. Plasma lysozyme and alternative complement pathway (ACH50) activities as well as nitrogen monoxide (NO) levels all increased significantly with the maximum levels being attained at 6, 6 and 3 h, respectively. Thereafter, these parameters all decreased significantly. In addition, fish fed 0.4 % FOS showed higher immune parameters under stress compared with that of control group. In addition, liver superoxide dismutase and catalase activities of fish fed 0.4 % FOS were both significantly higher than that of the control group before and after stress, while the opposite was true for malondialdehyde content. After stress, the expression of HSP70 and HSP90 of fish fed FOS was significantly higher than that of the control group at 6 and 12 h, respectively. After 12 h stress, the cumulative mortality of fish fed FOS was significantly lower than that of the control. The results indicated that the supplementation of 0.4 % FOS could increase the nonspecific immunity, antioxidant capacity and HSP70 and HSP90 expression of blunt snout bream and enhance its resistance to high ammonia stress.

Biological activity of selenorganic compounds at heavy metal salts intoxication

Possible mechanisms of the antitoxic action of organoselenium compounds in heavy metal poisoning have been considered. Heavy metal toxicity associated with intensification of free radical oxidation, suppression of the antioxidant system, damage to macromolecules, mitochondria and the genetic material can cause apoptotic cell death or the development of carcinogenesis. Organic selenium compounds are effective antioxidants during heavy metal poisoning; they exhibit higher bioavailability in mammals than inorganic ones and they are able to activate antioxidant defense, bind heavy metal ions and reactive oxygen species formed during metal-induced oxidative stress. One of promising organoselenium compounds is diacetophenonyl selenide (DAPS-25), which is characterized by antioxidant and antitoxic activity, under conditions including heavy metal intoxication

Molecular cloning, characterization and expression analysis of three heat shock responsive genes from Haliotis diversicolor

In this study, molecular characterization and expression of three heat shock responsive genes were analyzed as indicators to understand the mechanism of heat shock response of small abalone Haliotis diversicolor under stresses. The full length cDNA of heat shock transcriptional factor 1 (HdHSF1), heat shock factor binding protein 1(HSBP1), and heat shock protein 90 (HdHSP90) are 1548 bp, 809 bp, and 2592 bp respectively, encoding a protein of 515 aa, 75 aa, and 728 aa respectively. Real time quantitative PCR analysis revealed that these three genes are constitutively expressed in 7 selected tissues. The expression level of HdHSF1 in gills was higher than that in other tissues (p < 0.05). The highest expression level of HdHSBP1 was detected in hemocytes. The highest expression level of HdHSP90 was in the digestive tract and colleterial gland. The HdHSF1 expression level in the gills was up-regulated significantly (p < 0.05) after thermal stress and hypoxia exposure respectively. On the contrary, HdHSBP1 was down-regulated both in gills and hemocytes after thermal stress and the same as in gills after hypoxia stress. HdHSP90 expression level was also up-regulated in gills and hemocytes after both thermal and hypoxia stresses. These results indicated that these three heat shock responsive genes play important roles in response to thermal and hypoxia stress.

Proteomic analysis of sulfur-nitrogen-carbon removal by Pseudomonas sp. C27 under micro-aeration condition

Pseudomonas sp. C27 is a facultative autotrophic bacterium (FAB) that can effectively conduct mixotrophic and heterotrophic denitrifying sulfide removal (DSR) reactions under anaerobic condition using organic matters and sulfide as electron donors. Micro-aeration was proposed to enhance DSR reaction by FAB; however, there is no experimental proof on the effects of micro-aeration on capacity of denitrifying sulfide removal of FAB on proteomic levels. The proteome in total C27 cell extracts was observed by two-dimensional gel electrophoresis. Differentially expressed protein spots and specifically expressed protein spots were identified by MALDI TOF/TOF MS. We identified 55 microaerobic-responsive protein spots, representing 55 unique proteins. Hierarchical clustering analysis revealed that 75% of the proteins were up-regulated, and 5% of the proteins were specifically expressed under micro-aerobic conditions. These enzymes were mainly involved in membrane transport, protein folding and metabolism. The noted expression changes of the microaerobic-responsive proteins suggests that C27 strain has a highly efficient enzyme system to conduct DSR reactions under micro-aerobic condition. Additionally, micro-aeration can increase the rates of protein synthesis and cell growth, and enhance cell defensive system of the strain.

Expression of heat shock protein 90 genes during early development and infection in Megalobrama amblycephala and evidence for adaptive evolution in teleost

Heat shock protein 90 (HSP90) are highly conserved molecular chaperones, playing a pivotal role in cellular progress. In this study, we reported the characterization of the Hsp90α and Hsp90β genes in Megalobrama amblycephala, the expression profiling during early development, in various healthy tissues and in response to bacterial infection, and the assessment of their adaptive evolution. The Hsp90α cDNA contains an open reading frame (ORF) of 2193 bp encoding 731 amino acids and the Hsp90β cDNA has an ORF of 2184 bp encoding 728 amino acids. Using quantitative real-time PCR (qRT-PCR) analysis, the mRNA of both Hsp90α and Hsp90β reached the highest level at 15th day post-hatch. Using qRT-PCR and Western blot, both Hsp90α and Hsp90β were widely expressed in various healthy tissues and significantly higher in blood than in other tissues. Expression of both Hsp90α and Hsp90β were up-regulated upon bacterial infection and reached the peak level at 4 h post infection. Site model analysis indicated that one positive selection site (T717) in Hsp90α was found, while no positive selection site was observed in Hsp90β. Branch-site model test showed that there were adaptively evolutionary evidences in the branches of Salmoniformes and Gasterosteiformes for Hsp90α gene, and in the branch of Salmoniformes for Hsp90β gene.

Molecular characterization and expression analysis of four cathepsin L genes in the razor clam, Sinonovacula constricta

Cathepsin L (CTSL) is a lysosomal cysteine protease involved in immune responses in vertebrates. However, few studies exist regarding the role of cathepsin L in bivalves. In this study, we isolated and characterized four cathepsin L genes from the razor clam Sinonovacula constricta, referred to as CTSL1, CTSL2, CTSL3 and CTSL4. These four genes contained typical papain-like cysteine protease structure and enzyme activity sites with ERWNIN-like and GNFD-like motifs in the proregion domain and an oxyanion hole (Gln) and a catalytic triad (Cys, His and Asn) in the mature domain. Expression analysis of the four transcripts revealed a tissue-specific pattern with high expression of CTSL1 and CTSL3 in liver and gonad tissues and high expression of CTSL2 and CTSL4 in liver and gill tissues. During the developmental stages, the four transcripts showed the highest expression in the juvenile stage; however, CTSL3 had a much higher expression level than the other three transcripts during embryogenesis. The four transcripts showed significant changes in expression as early as 4 h or 8 h after infection with Vibrio anguillarum. The fact that bacterial infection can induce expression of the four CTSL transcripts suggests that these transcripts are important components of the innate immunity system of the clam.

A heat shock protein 90 β isoform involved in immune response to bacteria challenge and heat shock from Miichthys miiuy

Heat shock protein 90 (HSP90) is highly conserved molecular chaperone that plays a critical role in cellular stress response. In this study, we reported the identification and functional analysis of a heat shock protein 90 gene from miiuy croaker (designated Mimi-HSP90). Mimi-HSP90 contained five conserved HSP90 protein family signatures and shared 89.6%-99.5% similarity with other known HSP90 β isoform. Homology analysis and structure comparison further indicated that Mimi-HSP90 should be β isoform member of the HSP90 family. The molecular evolutionary analysis showed that HSP90 was under an overall strong purifying select pressure among fish species. Mimi-HSP90 gene was constitutively expressed in ten examined tissues, and the expression level of liver was higher than in other tissues. The expression level of Mimi-HSP90 gene under bacterial infection and heat shock were analyzed by real-time quantitative RT-PCR, resulted in significant changes in liver, spleen, and kidney tissues. The purified recombinant pET-HSP90 protein was used to produce the polyclonal antibody in mice. The specificity of the antibody was determined by Western blot analysis. All results suggested that Mimi-HSP90 was involved in thermal stress and immune response in miiuy croaker.

Heat shock protein genes (hsp20, hsp75 and hsp90) from Pieris rapae: molecular cloning and transcription in response to parasitization by Pteromalus puparum

Most molecular work on the roles of heat shock proteins (hsps) in host-parasite interaction has focused on vertebrates, rather than invertebrates. Here the full length complementary DNA (cDNA) sequences of three hsp genes (hsp20, hsp75 and hsp90) were amplified from Pieris rapae, and their transcriptional responsiveness to parasitization by the endoparasitic wasp Pteromalus puparum were investigated. The cDNA sequence analysis of hsp20, hsp75 and hsp90 revealed open reading frames of 531, 2 328 and 2 157 bp in length, which encode proteins with calculated molecular weights of 19.5, 75.48 and 82.7 kDa, respectively. The comparison of amino acid sequences showed that P. rapae hsp20 shared highly divergent homology to that of other insects, while hsp75 and hsp90 showed high homology to their counterparts of other species. The expression analysis indicated that these three genes were influenced in response to parasitization by P. puparum. The hsp20 transcripts in parasitized pupae were higher compared to non-parasitized pupae. The expression of hsp75 and hsp90 were down-regulated following parasitization. The results indicate that hsps are involved in host-parasitoid interactions.

Research progress on the mollusc immunity in China

The economical and phylogenic importance of mollusc has led an increasing number of investigations giving emphasis to immune defense mechanism. This review discusses the advances in immunological study of mollusc in China, with special reference to dominant aquaculture species over the past decades. As an invertebrate group, molluscs lack adaptive immunity and consequently they have evolved sophisticated strategies of innate immunity for defense against pathogens. This review aims to present the various immunologically significant pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), lectins, lipopolysaccharide and β-1, 3-glucan binding protein (LGBP), scavenger receptors (SRs) employed by mollucans. This work also highlights immune proteolytic cascade, TLR signaling pathway and an extensive repertoire of immune effectors including antimicrobial peptide, lysozyme, antioxidant enzyme and heat shock protein. Further, the review presents the preliminary progress made on the catecholaminergic neuroendocrine system in scallop and its immunomodulation function to throw light into neuroendocrine-immune regulatory network in lower invertebrates.

The protection of selenium against cadmium-induced cytotoxicity via the heat shock protein pathway in chicken splenic lymphocytes

Cadmium (Cd) is a heavy metal that poses a hazard to animal health due to its toxicity. Selenium (Se) is an important nutritional trace element. However, the potential protective effects of Se against Cd-induced toxicity remain to be elucidated. To investigate the cytotoxicity of Cd on bird immunocytes in vitro and the protective effects of Se against exposure to Cd, chicken splenic lymphocytes received Cd (10⁻⁶ mol/L), Se (10⁻⁷ mol/L), and the mixture of 10⁻⁷ mol/L Se and 10⁻⁶ mol/L Cd and were incubated for 12 h, 24 h, 36 h, 48 h, respectively. The transcription of heat shock protein (HSP) 27, HSP40, HSP60, HSP70 and HSP90 mRNA was tested by fluorescence quantitative PCR. The results showed that the mRNA expression of HSPs exposed to 10⁻⁶ mol/L Cd showed a sustained decrease at 12–48 h exposure. A statistically significant increase in the mRNA expression of HSPs in the case of Se group was observed, as compared to the control group of chicken splenic lymphocytes. Concomitantly, treatment of chicken splenic lymphocytes with Se in combination with Cd enhanced the mRNA expression of HSPs which were reduced by Cd treatment. This indicated that the protective effect of Se against the toxicity of Cd might, at least partially, be attributed to stimulation of the level of HSPs.

Identification of genes potentially related to biomineralization and immunity by transcriptome analysis of pearl sac in pearl oyster Pinctada martensii

Pearl oyster Pinctada martensii is cultured for production of pearl in China. It needs to implant a mantle graft cut from a donor oyster and a seed nucleus into the gonad of the host oyster to produce a pearl. Pearl sac surrounding the nucleus is formed by the proliferation of the implanted mantle graft from the outer mantle epithelial cells in the host oyster. The pearl sac is responsible for production of a cultured pearl. A comprehensive transcriptome analysis on pearl sac will help to understand the mechanism on pearl formation and immune response of host oyster after nucleus implantation. In the present study, 39,400,004 reads were produced from the pearl sac using RNA-sequence technology and then assembled into 102,762 unigenes. More than 22.4% of these unigenes were possibly involved in approximately 219 known signaling pathways. A total of 37,188 unigenes were annotated based on sequences similarities with known proteins. Fifty-one biomineralization-related unigenes and 268 immune-related unigenes were not previously detected in P. martensii. The un-annotated unigenes may be some genes specifically existed in P. martensii. These annotated or un-annotated unigenes in the present studies were valuable for the future investigation on molecular mechanism of pearl formation and immune response of the species.

Stress-induced HSP70 from Musca domestica plays a functionally significant role in the immune system

As important molecular chaperones, members of the 70kDa heat shock protein (HSP70) family play essential roles in stress tolerance and innate immunity in organisms. The full-length complementary DNA (cDNA) of a novel inducible HSP70, named as MdHSP70, was isolated from Musca domestica. The cDNA clone consisted of 2411 bp with a 1956 bp open reading frame which encodes 651 amino acids. Using real-time quantitative polymerase chain reaction (qPCR), we investigated the transcriptional profile of the gene under heat shock, cadmium stress and in response to bacteria. Increased expression of MdHSP70 was observed in response to both heat shock and Cd stress. The expression of MdHSP70 was significantly induced by Escherichia coli or Staphylococcus aureus stimulation. Larvae were fed bacteria expressing dsRNA targeting the MdHSP70 gene. Our results showed high mortality in larvae treated with dsRNA of MdHSP70 at heat shock, Cd stress and bacterial invasion, suggesting that MdHSP70 is potentially involved in the stress and immune responses of the house fly and perhaps contributes to protection against cellular injury.