Cloning and expression of glucose regulated protein 78 (GRP78) in Fenneropenaeus chinensis

Endoplasmic Reticulum Stress and Its Impact on Adipogenesis: Molecular Mechanisms Implicated

Endoplasmic reticulum (ER) stress plays a pivotal role in adipogenesis, which encompasses the differentiation of adipocytes and lipid accumulation. Sustained ER stress has the potential to disrupt the signaling of the unfolded protein response (UPR), thereby influencing adipogenesis. This comprehensive review illuminates the molecular mechanisms that underpin the interplay between ER stress and adipogenesis. We delve into the dysregulation of UPR pathways, namely, IRE1-XBP1, PERK and ATF6 in relation to adipocyte differentiation, lipid metabolism, and tissue inflammation. Moreover, we scrutinize how ER stress impacts key adipogenic transcription factors such as proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBPs) along with their interaction with other signaling pathways. The cellular ramifications include alterations in lipid metabolism, dysregulation of adipokines, and aged adipose tissue inflammation. We also discuss the potential roles the molecular chaperones cyclophilin A and cyclophilin B play in adipogenesis. By shedding light on the intricate relationship between ER stress and adipogenesis, this review paves the way for devising innovative therapeutic interventions.

Full-Length Transcriptome Reconstruction Reveals the Genetic Mechanisms of Eyestalk Displacement and Its Potential Implications on the Interspecific Hybrid Crab (Scylla serrata ♀ × S. paramamosain ♂)

Simple Summary

The eyestalk is a key organ in crustaceans that produces neurohormones and regulates a range of physiological functions. Eyestalk displacement was discovered in some first-generation (F1) offspring of the novel interspecific hybrid crab (Scylla serrata ♀ × S. paramamosain ♂). To uncover the genetic mechanism underlying eyestalk displacement and its potential implications, high-quality transcriptome was reconstructed using single-molecule real-time (SMRT) sequencing. A total of 37 significantly differential alternative splicing (DAS) events (17 up-regulated and 20 down-regulated) and 1475 significantly differential expressed transcripts (DETs) (492 up-regulated and 983 down-regulated) were detected in hybrid crabs with displaced eyestalks (DH). The most significant DAS events and DETs were annotated as being endoplasmic reticulum chaperone BiP and leucine-rich repeat protein lrrA-like isoform X2. In addition, the top ten significant gene ontology (GO) terms were related to the cuticle or chitin. Overall, this study highlights the underlying genetic mechanisms of eyestalk displacement and provide useful knowledge for mud crab (Scylla spp.) crossbreeding.

Abstract

The lack of high-quality juvenile crabs is the greatest impediment to the growth of the mud crab (Scylla paramamosain) industry. To obtain high-quality hybrid offspring, a novel hybrid mud crab (S. serrata ♀ × S. paramamosain ♂) was successfully produced in our previous study. Meanwhile, an interesting phenomenon was discovered, that some first-generation (F1) hybrid offspring’s eyestalks were displaced during the crablet stage I. To uncover the genetic mechanism underlying eyestalk displacement and its potential implications, both single-molecule real-time (SMRT) and Illumina RNA sequencing were implemented. Using a two-step collapsing strategy, three high-quality reconstructed transcriptomes were obtained from purebred mud crabs (S. paramamosain) with normal eyestalks (SPA), hybrid crabs with normal eyestalks (NH), and hybrid crabs with displaced eyestalks (DH). In total, 37 significantly differential alternative splicing (DAS) events (17 up-regulated and 20 down-regulated) and 1475 significantly differential expressed transcripts (DETs) (492 up-regulated and 983 down-regulated) were detected in DH. The most significant DAS events and DETs were annotated as being endoplasmic reticulum chaperone BiP and leucine-rich repeat protein lrrA-like isoform X2. In addition, the top ten significant GO terms were related to the cuticle or chitin. Overall, high-quality reconstructed transcriptomes were obtained for the novel interspecific hybrid crab and provided valuable insights into the genetic mechanisms of eyestalk displacement in mud crab (Scylla spp.) crossbreeding.

Transcriptome analysis endoplasmic reticulum-stress response in Litopenaeus vannamei hemocytes

Numerous studies have proved that endoplasmic reticulum (ER)-stress is an important cause of aquatic animal diseases. Therefore, for effectively preventing and controlling aquatic animal diseases, a systematic and in-depth understanding of the environmental stress response in aquatic animals is necessary. In present study, the influence of ER-stress in Litopenaeus vannamei was investigated using Illumina HiSeq based RNA-Seq. Comparing to the cDNA library of hemocytes treated with DMSO in L. vannamei, 286 unigenes were significantly upregulated and 473 unigenes were significantly down-regulated in the Thapsigargin treated group. KEGG analysis indicated that the differentially expressed genes (DEGs) are mainly related to ER-stress, immune as well as metabolism. Besides the classical ER-stress response pathways, the regulation of cell cycle and DNA replication are also important measures of ER-stress response. It has been suggested that the influence of ER-stress on immune genes might be an important factor in environmental stress inducing shrimp disease. Our investigation exhibited that immune-related DEG Prophenoloxidase activating enzyme 2 (LvPPAE2) roled in anti-pathogen immunity of shrimp. This study provides a solid foundation for uncovering the environmental adaptation response and especially its relationship with L. vannamei immune system.

Sensitivity of Zebrafish Embryogenesis to Risk of Fotemustine Exposure

Several anthropogenic products in wastewater are considered a threat to the aquatic environment. In addition to common industrial pollutants, levels of pharmaceuticals have been increasingly found in the environment in recent years, which may present a strong risk to the aquatic species that live there. The constant consumption of biologically active chemicals for human health has been matched by an increase in the leaking of these compounds in natural habitats over the last two decades. This study is aimed at evaluating the developmental toxicity of fotemustine in the ecological environment. Zebrafish embryos were exposed to doses of 25, 50 and 100 µg/mL from 4 h post-fertilization to 120 h. This study confirms that fotemustine exposure at 50 and 100 µg/mL affects the survival and hatching rate, morphology score and body length. Additionally, it significantly disturbs the antioxidant defense system and increases ROS in zebrafish larvae. From the molecular point of view, fotemustine exposure strongly induces apoptosis, endoplasmic reticulum stress (ERS) and the Wnt signaling pathway.

Characterization, Stress Response and Functional Analyses of Giant River Prawn (Macrobrachium rosenbergii) Glucose-Regulated Protein 78 (Mr-grp78) under Temperature Stress and during Aeromonas hydrophila Infection

Simple Summary

Glucose-regulated protein 78 (grp78) is classified as a member of the Hsp70 subfamily. This protein functions as a key factor in signal transduction associated with the unfolded protein response (UPR) in the endoplasmic reticulum (ER) during cellular stress and protects against cell damage caused by toxic chemicals, oxidative stress, Ca²⁺ depletion, programmed cell death and various infectious conditions. To investigate this crucial mechanism in giant river prawn (Macrobrachium rosenbergii), we analyzed the biological function of prawn grp78 at the molecular level in this study. The regulation of this gene was intensively analyzed under normal bacterial infection and heat/cold-shock inductions. A functional analysis of this gene under heat and infectious stress conditions was performed by gene knockdown. The information obtained in the current study clearly indicates the crucially significant roles of grp78 in the cellular stress responses of the target experimental animal under various stress conditions.

Abstract

The endoplasmic reticulum (ER) is an organelle important for several functions of cellular physiology. This study identified the giant river prawn’s glucose-regulated protein 78 (Mr-grp78), which is important for ER stress mechanisms. Nucleotide and amino acid analyses of Mr-grp78, as compared with other species, revealed the highest similarity scores with the grp78 genes of crustaceans. An expression analysis by quantitative RT-PCR indicated that Mr-grp78 was expressed in all tissues and presented its highest expression in the ovary (57.64 ± 2.39-fold), followed by the gills (42.25 ± 1.12), hindgut (37.15 ± 2.47), thoracic ganglia (28.55 ± 2.45) and hemocytes (28.45 ± 2.26). Expression analysis of Mr-grp78 mRNA levels under Aeromonas hydrophila induction and heat/cold-shock exposure was conducted in the gills, hepatopancreas and hemocytes. The expression levels of Mr-grp78 in these tissues were highly upregulated 12 h after bacterial infection. In contrast, under heat- and cold-shock conditions, the expression of Mr-grp78 was significantly suppressed in the gills at 24–96 h and in the hepatopancreas at 12 h (p < 0.05). A functional analysis via Mr-grp78 gene knockdown showed that Mr-grp78 transcription in the gills, hepatopancreas and muscle strongly decreased from 6 to 96 h. Furthermore, the silencing of this gene effectively increased the sensitivity of the tested prawns to heat- and pathogenic-bacterium-induced stress. The results of this study clearly demonstrate the significant functional roles of Mr-grp78 in response to both temperature and pathogen treatments.

Endoplasmic reticulum unfolded protein response modulates the adaptation of Trachemys scripta elegans in salinity water

Trachemys scripta elegans, as a freshwater invasive species, can survive and lay eggs in brackish water, which may lead to the expansion of its potential invasion range due to freshwater salinization. Our previous studies have shown that high salinity leads to the accumulation of serum lipid content, which may induce endoplasmic reticulum stress (ERS) in the turtle. To better understand whether ERS is triggered by salinity, and in turn whether the turtles promote the protection mechanism, we exposed the turtles to the freshwater (CK), 5‰ salinity water (S5) and 15‰ salinity water (S15), and sampled at 6 h, 24 h and 30 d. 13 differentially expressed genes (DEGs) related to ERS pathways were found in the comparison of CK vs. S15 by transcriptomics analysis. Then, the mRNA and protein expression of ERS and its related activation pathways were further investigated. ERS marker glucose regulated protein 78 kD (GRP78) increased significantly (p < 0.05) in both the transcript and protein levels after exposure to 15‰ salinity water, which clearly indicated that salinity could induce ERS in T. s. elegans. Meanwhile, the three unfolded protein response (UPR) including transducers protein kinase RNA (PKR)-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α) and activating transcription factor-6 (ATF6) were promoted by salinity, suggesting that the turtle might promote physiological process to eliminate damaged cells and cope with unfolded proteins accumulation induced by ERS. Our results provide new insight into the mechanism of salinity adaptation in T. s. elegans and salt-tolerant biological invasion.

Planarians (Platyhelminthes)-An Emerging Model Organism for Investigating Innate Immune Mechanisms

An organism responds to the invading pathogens such as bacteria, viruses, protozoans, and fungi by engaging innate and adaptive immune system, which functions by activating various signal transduction pathways. As invertebrate organisms (such as sponges, worms, cnidarians, molluscs, crustaceans, insects, and echinoderms) are devoid of an adaptive immune system, and their defense mechanisms solely rely on innate immune system components. Investigating the immune response in such organisms helps to elucidate the immune mechanisms that vertebrates have inherited or evolved from invertebrates. Planarians are non-parasitic invertebrates from the phylum Platyhelminthes and are being investigated for several decades for understanding the whole-body regeneration process. However, recent findings have emerged planarians as a useful model for studying innate immunity as they are resistant to a broad spectrum of bacteria. This review intends to highlight the research findings on various antimicrobial resistance genes, signaling pathways involved in innate immune recognition, immune-related memory and immune cells in planarian flatworms.

Comparative proteomic and transcriptomic analysis reveals high pH-induced expression signatures of Chinese shrimp Fenneropenaeus chinensis

pH has a great impact on the distribution, growth, behavior, and physiology in many aquatic animals. The comparison of proteomics between normal and high pH stress samples was successfully achieved using iTRAQ proteomic analysis to screen key response proteins and pathways. After high pH stress, 124 upregulated and 41 downregulated proteins were identified. The higher expression levels of proteins like citrate synthase, glutathione S-transferase, glutathione peroxidase, and cytochrome c oxidase are associated with oxidative stress and mitochondrial dysfunction. The upregulation of glucose-regulated protein 78 indicated that the endoplasmic reticulum stress is induced by high pH stress. There were significant upregulation expressions of V-type H⁺-ATPase, Na⁺, K⁺-ATPase, 14-3-3 protein, as well as ATP-binding cassette transmembrane transporters after high pH exposure, which indicating their important roles in response to high pH stress. The abundance of proteins involved in protein glycosylation, oxidative pentose phosphate pathway, protein export, and glutathione metabolism were found enriched in high pH group than in control group. Quantitative proteomic profiling and integrated analysis with transcriptomic data provide new insights into the mechanisms underlying the molecular response to high pH stress in Fenneropenaeus chinensis.

Cloning and characterization of chst11 from Procambarus clarkii involved in the host immune response of white spot syndrome virus and Aeromonas hydrophila

Carbohydrate sulfotransferases 11 (chst11) is one of the enzymes that synthesize chondroitin sulfate (CS), which has extensive immune functions in vitro and plays a critical role in mediating the infection of host by pathogenic microorganisms. However, whether it has immune functions in crayfish is still poorly understood. In our previous study of transcriptome, chst11 was differentially expressed in susceptible individuals and resistant individuals of Procambarus clarkii after white spot syndrome virus (WSSV) injection. Thus, in this study, the sequence of chst11 was obtained from P. clarkii for the first time and analyzed, and the expression pattern of chst11 was investigated. Besides, the purified recombinant protein of chst11 effect in protection in WSSV infection was explored. The full length of chst11 was 1536 bp with an 831-bp open reading frame (ORF), which encoding 276 amino acids residues with a calculated molecular mass of 33.1 kDa. The chst11 contains a Sulfotransfer_2 domain, one N-glycosylation site and three O-glycosylation sites. Phylogenetic analysis results showed that chst11 had the highest similarity to Penaeus vannamei (79.93%). The expression pattern of chst11 in different tissues indicated that chst11 was expressed highest in gut, gill and hypodermis, lowest in testicular duct, periesophageal nerve and hemocytes. The chst11 had different expression patterns in different tissues when the crayfish was challenged by WSSV, Aeromonas hydrophila and CpG ODN. Recombinant chst11 protein significantly reduced the amount of WSSV copy number in hepatopancreas at 6 h and 12 h post injection compared to the control group injected with bovine serum albumin (BSA). It was found that chst11 protein enhanced the expression of peroxinectin, proPO in hepatopancreas and midgut and the C-type lectin (ctl) in hemocytes and hepatopancreas. Intramuscularly injection of juvenile crayfish with chst11 protein decreased 60% mortality compared to the control group with BSA. This study is the first report on the antiviral function of chst11 in the immune system of crustacean.

Evaluation of immunological response in shrimp Penaeus vannamei submitted to low temperature and air exposure

The objective of this study is to explore the immune response of the shrimp Penaeus vannamei to low temperature and air exposure during the mimic waterless transportation. Shrimp were cold shocked at 13 °C for 3 min, then exposed to air at 15 °C for 12 h, and finally revived in water at 25 °C. Hemocyte structure remained intact with only slight distortions of some organelles and nuclear membrane under the stress. Phenoloxidase (PO), lysozyme (Lys) and gamma-glutamyl transferase (GGT) activities, glutamine (Gln) content and relative mRNA expressions of prophenoloxidase (proPO), β-1,3-glucan binding protein (LGBP), ferrin (Fer) and glucose regulated protein 78 (GRP 78) increased and reached peak levels after 3 h-9 h of air exposure, and then decreased to relatively stable levels in the prolonged period of air exposure. The total hemocyte count (THC) and gene expressions of proPO, Fer and LGBP at the end of waterless storage were significantly lower (p < 0.05) than those in fresh shrimp while no significant difference (p ≥ 0.05) was found between revived and fresh shrimp in PO, Lys, GGT activities, Gln content and gene expression level of GRP 78. Of all the hemocytes, the percentage of semi granular cells (SGC) and granular cells (GC) significantly decreased after 6-9 h of storage, while hyaline cells (HC) dramatically increased after 9 h of storage to compensate the loss of SGC and GC. Results suggested that the low temperature and air exposure caused significant immunological response to the shrimp, but the damages to the immune system were partly reparable.

Sequence and expression analysis of HSP70 family genes in Artemia franciscana

Thus far, only one gene from the heat shock protein 70 (HSP70) family has been identified in Artemia franciscana. Here, we used the draft Artemia transcriptome database to search for other genes in the HSP70 family. Four novel HSP70 genes were identified and designated heat shock cognate 70 (HSC70), heat shock 70 kDa cognate 5 (HSC70-5), Immunoglobulin heavy-chain binding protein (BIP), and hypoxia up-regulated protein 1 (HYOU1). For each of these genes, we obtained nucleotide and deduced amino acid sequences, and reconstructed a phylogenetic tree. Expression analysis revealed that in the juvenile state, the transcription of HSP70 and HSC70 was significantly (P < 0.05) higher in a population of A. franciscana selectively bred for increased induced thermotolerance (TF12) relative to a control population (CF12). Following non-lethal heat shock treatment at the nauplius stage, transcription of HSP70, HSC70, and HSC70-5 were significantly (P < 0.05) up-regulated in TF12. In contrast, transcription of the other HSP70 family members in A. franciscana (BIP, HYOU1, and HSPA4) showed no significant (P > 0.05) induction. Gene expression analysis demonstrated that not all members of the HSP70 family are involved in the response to heat stress and selection and that especially altered expression of HSC70 plays a role in a population selected for increased thermotolerance.

Xiaoaiping Induces Developmental Toxicity in Zebrafish Embryos Through Activation of ER Stress, Apoptosis and the Wnt Pathway

The aim of the study was to determine the developmental toxicity of the traditional Chinese medicine Xiaoaiping (XAP) and to investigate its underlying mechanism of action. Zebrafish embryos were incubated with 0.4, 0.8, 1.2, and 1.6 mg/mL XAP. Endpoints such as mortality, hatching rate, malformation, body length, morphology score, swimming behavior, histological changes, reactive oxygen species (ROS) production, total superoxide dismutase (T-SOD) activity, and the mRNA expression of genes related to oxidative stress, endoplasmic reticulum (ER) stress, apoptosis, and the Wnt pathway were evaluated. Our results demonstrated that XAP exposure increased mortality and malformation and reduced the hatching rate. XAP resulted in severe malformation, including swim bladder deficiency, yolk retention, pericardial edema, and tail curvature. Histopathological analysis showed that XAP induced liver, heart and muscle injury. High doses (≥1.2 mg/mL) of XAP notably decreased the locomotor capacity of zebrafish. ROS generation was remarkably increased and T-SOD activity was decreased, confirming that oxidative stress was induced by XAP. The mRNA expression levels of ER stress-related genes (chop, hspa5, hsp90b1, and perk), apoptosis-related genes (caspase-3, bax, and p53) and wnt11 were significantly upregulated by XAP exposure. The expression levels of the oxidative stress-related genes (cat, sod1, and gstp2), Wnt pathway-related genes (β-catenin, wnt3a, and wnt8a) and bcl-2 initially increased and then decreased as the XAP exposure dose increased. In conclusion, we provide evidence for the first time that XAP can induce dose-related developmental toxicity, and ER stress, apoptosis and the Wnt pathway participate in the toxicity regulation.

Identification of Litopenaeus vannamei BiP as a novel cellular attachment protein for white spot syndrome virus by using a biotinylation based affinity chromatography method

White spot syndrome virus (WSSV) is a dangerous threat to shrimp farming that also attacks a wide range of crustaceans. Knowledge of the surface protein-protein interactions between the pathogen and host is very crucial to unraveling the molecular pathogenesis mechanisms of WSSV. In this study, LvBiP (Litopenaeus vannamei immunoglobulin heavy-chain-binding protein) was identified as a novel WSSV binding protein of L. vannamei by a biotinylation based affinity chromatography method. By using pull-down and ELISA assays, the binding of recombinant LvBiP to WSSV was proved to be specific and ATP- dependent. The interaction was also confirmed by the result of co-immunoprecipitation assay. Immunofluorescence studies revealed the co-localization of LvBiP with WSSV on the cell surface of shrimp haemocytes. Additionally, LvBiP is likely to play an important role in WSSV infection. Treatment of gill cellular membrane proteins (CMPs) with purified rLvBiP and antibody that specifically recognizes LvBiP, led to a significant reduction in the binding of WSSV to gill CMPs. In the in vivo neutralization assay, rLvBiP and anti-LvBiP polyclonal antibody partially blocked the infection of WSSV. Taken together, the results indicate that LvBiP, a molecular chaperon of the HSP70 family, is a novel host factor involved at the step of attachment of the WSSV to the host cells and a potential candidate of therapeutic target.

Identification and functional characterization of unfolded protein response transcription factor ATF6 gene in kuruma shrimp Marsupenaeus japonicus

Activating transcription factor 6 (ATF6) pathway is the key branch of unfolded protein response (UPR). In this study, a homolog of ATFα from Marsupenaeus japonicus (MjATF6) was identified using genome sequencing and characterized, so as to investigate the role of ATF6 pathway in anti-viral immunity of M. japonicus. The cDNA of MjATF6 obtained was 1008 bp in length, with an open reading frame (ORF) of 849bp, which had encoded a putative of 283 amino acid proteins. Results of qRT-PCR showed that MjATF6 was distributed in all the six tested tissues, with the higher expression level being seen in hemocytes and hepatopancreas. Furthermore, MjATF6 expression would be up-regulated from 1 day to 7 day under white spot syndrome virus (WSSV) challenge. In comparison, RNA interference-induced MjATF6 knockdown had resulted in a lower 7-day cumulative mortality of M. japonicus in the presence of WSSV infection. Additionally, our results also revealed that less VP28 mRNA was extracted from hemocytes or hepatopancreas of MjATF6 knockdown shrimp than that from the control. Taken together, these results have confirmed that ATF6 pathway is vital for WSSV replication, and that UPR in M. japonicus may facilitate WSSV infection.

The anti-stresses capability of GRP78 in Penaeus monodon: Evidence from in vitro and in vivo studies

Glucose-regulated protein 78 (GRP78) is an important member of the heat shock protein 70 (HSP70) family, which plays important roles in the response to stimulation from various external environmental stimuli. In this study, the full-length cDNA of GRP78 (PmGRP78) was cloned from Penaeus monodon. The qRT-PCR analysis showed that PmGRP78 was ubiquitously expressed in all the tested shrimp tissues, and the expression pattern of PmGRP78 in the gill and hepatopancreas tissues after a pH challenge, osmotic stress, and heavy metal exposure was also detected. A chaperone activity assay was performed to study the function of PmGRP78, and the results showed that the recombinant PmGRP78 possesses biological activity and could protect alcohol dehydrogenase (ADH) from denaturing in vitro. To further explore the role played by PmGRP78 in vivo, RNA interference (RNAi) technology was adopted to silence the expression of PmGRP78 in P. monodon, and a cumulative mortality rate assay was carried out. In conclusion, we inferred that PmGRP78 may play important roles in the defence against environmental stresses in P. monodon.

Induction of stress- and immune-associated genes in the Indian meal moth Plodia interpunctella against envenomation by the ectoparasitoid Bracon hebetor

Envenomation is an important process in parasitism by parasitic wasps; it suppresses the immune and development of host insects. However, the molecular mechanisms of host responses to envenomation are not yet clear. This study aimed to determine the transcription-level responses of the Indian meal moth Plodia interpunctella against envenomation of the ectoparasitoid Bracon hebetor. Quantitative real-time reverse-transcription PCR was used to determine the transcriptional changes of 13 selected genes, which are associated with development, metabolism, stress, or immunity, in the feeding and wandering fifth instar larvae over a 4-day period after envenomation. The effects of envenomation on the feeding-stage larvae were compared with those of starvation in the transcriptional levels of the 13 genes. Most selected genes were altered in their expression by either envenomation or starvation. In particular, a heat shock protein, hsp70, was highly upregulated in envenomated larvae in both the feeding and wandering stages as well as in starved larvae. Further, some genes were upregulated by envenomation in a stage-specific manner. For example, hsp25 was upregulated after envenomation in the feeding larvae, but hsp90 and an immune-associated gene, hemolin, were upregulated in the wandering larvae. However, both envenomation and starvation resulted in the downregulation of genes associated with development and metabolism. Taken together, P. interpunctella upregulated stress- and immune-responsive genes, but downregulated genes associated with development and metabolism after envenomation. This study provides important information for understanding the molecular mechanisms of host responses to parasitism.

Transcriptome analysis of the unfolded protein response in hemocytes of Litopenaeus vannamei

In this study, Litopenaeus vannamei was injected with double-stranded RNA (dsRNA) against L. vannamei immunoglobulin heavy chain binding protein (LvBip) to activating UPR in the hemocytes, shirmps injected dsRNA against enhanced green fluorescence protein (eGFP) as control group. And genes expression in hemocytes of then were analyzed using Illumina Hiseq 2500 (PE100). By comparing the analyzed results, 1418 unigenes were significantly upregulated, and 596 unigenes were significantly down-regulated upon UPR. Analysis of the differentially expressed genes against known databases indicated that the distribution of gene pathways between the upregulated and down-regulated genes were substantially different. A total of 208 genes of UPR system were obtained, and 69 of them were differentially expressed between the two groups. Results also showed that L. vannamei UPR was involved in various metabolic processes, such as glycometabolism, lipid metabolism, amino acid metabolism, and nucleic acid metabolism. In addition, UPR was emgaged in immune-assicoated signaling pathways, such as NF-κB signaling pathway, NOD-like receptor signaling pathway, Hippo signaling pathway, p38 MAPK signaling pathway and Wnt signaling pathway in L. vannamei. These results improved our current understanding of the L. vannamei UPR, and highlighted its importance in cell homeostasis upon environmental stress.

Grass carp (Ctenopharyngodon idella) ATF6 (activating transcription factor 6) modulates the transcriptional level of GRP78 and GRP94 in CIK cells

ATF transcription factors are stress proteins containing alkaline area-leucine zipper and play an important role in endoplasmic reticulum stress. ATF6 is a protective protein which regulates the adaptation of cells to ER stress by modulating the transcription of UPR (Unfolded Protein Response) target genes, including GRP78 and GRP94. In the present study, a grass carp (Ctenopharyngodon idella) ATF6 full-length cDNA (named CiATF6, KT279356) has been cloned and identified. CiATF6 is 4176 bp in length, comprising 159 nucleotides of 5'-untranslated sequence, a 1947 nucleotides open reading frame and 2170 nucleotides of 3'-untranslated sequences. The largest open reading frame of CiATF6 translates into 648 aa with a typical DNA binding domain (BRLZ domain) and shares significant homology to the known ATF6 counterparts. Phylogenetic reconstruction confirmed its closer evolutionary relationship with other fish counterparts, especially with Zebrafish ATF6. RT-PCR showed that CiATF6 was ubiquitously expressed and significantly up-regulated after stimulation with thermal stress in all tested grass carp tissues. In order to know more about the role of CiATF6 in ER stress, recombinant CiATF6N with His-tag was over-expressed in Rosetta Escherichia coli, and the expressed protein was purified by affinity chromatography with Ni-NTA His-Bind Resin. In vitro, gel mobility shift assays were employed to analyze the interaction of CiATF6 protein with the promoters of grass carp GRP78 and GRP94, respectively. The result has shown that CiATF6 could bind to these promoters with high affinity by means of its BRLZ mainly. To further study the transcriptional regulatory mechanism of CiATF6, Dual-luciferase reporter assays were applied. Recombinant plasmids of pGL3-GRP78P and pGL3-CiGRP94P were constructed and transiently co-transfected with pcDNA3.1-CiATF6 (pcDN3.1-CiATF6-nBRLZ, respectively) into C. idella kidney (CIK) cells. The result has shown that CiATF6 could activate CiGRP78 and CiGRP94 promoters.

Molecular Mechanisms of White Spot Syndrome Virus Infection and Perspectives on Treatments

Since its emergence in the 1990s, White Spot Disease (WSD) has had major economic and societal impact in the crustacean aquaculture sector. Over the years shrimp farming alone has experienced billion dollar losses through WSD. The disease is caused by the White Spot Syndrome Virus (WSSV), a large dsDNA virus and the only member of the Nimaviridae family. Susceptibility to WSSV in a wide range of crustacean hosts makes it a major risk factor in the translocation of live animals and in commodity products. Currently there are no effective treatments for this disease. Understanding the molecular basis of disease processes has contributed significantly to the treatment of many human and animal pathogens, and with a similar aim considerable efforts have been directed towards understanding host-pathogen molecular interactions for WSD. Work on the molecular mechanisms of pathogenesis in aquatic crustaceans has been restricted by a lack of sequenced and annotated genomes for host species. Nevertheless, some of the key host-pathogen interactions have been established: between viral envelope proteins and host cell receptors at initiation of infection, involvement of various immune system pathways in response to WSSV, and the roles of various host and virus miRNAs in mitigation or progression of disease. Despite these advances, many fundamental knowledge gaps remain; for example, the roles of the majority of WSSV proteins are still unknown. In this review we assess current knowledge of how WSSV infects and replicates in its host, and critique strategies for WSD treatment.

Molecular characterization of two novel molecular chaperones in bacterial-challenged Apostichopus japonicus

Molecular chaperones of 78 kDa glucose-regulated protein (GRP78) and protein disulfide isomerase (PDI) are involved in protein folding and assembly in the endoplasmic reticulum (ER). Increasing evidences also suggest that these two molecules play an important role in immune response. In the present study, we cloned and characterized GRP78 and PDI genes from Apostichopus japonicus by RNA-seq and RACE approaches (designated as AjGRP78 and AjPDI, respectively). The AjGRP78 cDNA was of 2355bp including an open reading frame (ORF) of 2013 bp encoding a protein of 670 amino acids with three heat shock protein 70 (HSP70) family signatures. AjGRP78 contained a 23-amino acid signal peptide at the N-terminus and a HDEL motif at the C-terminus, which supported the location of the protein in the ER. The full length cDNA of AjPDI was of 1893 bp with a 5' untranslated region (UTR) of 153 bp, a 3' UTR of 228 bp and an ORF of 1512 bp encoding a protein of 503 amino acids. A 17-amino acid signal peptide, two thioredoxin domains with two active sites of CGHC, and KDEL retention signal were totally conserved in the deduced amino acid of AjPDI. Phylogenic analysis and multiple alignments have shown that both genes shared remarkably higher degree of structural conservation and sequence identities with other counterparts from invertebrates and vertebrates, further supporting that the two proteins were novel members of molecular chaperone family. Spatial expression analysis revealed that AjGRP78 mRNA transcripts were dominantly expressed in the tentacle, while AjPDI mRNA levels were abundant in the muscle, intestine and respiratory trees. For Vibrio splendidus challenged sea cucumber, the peak expression of AjGRP78 and AjPDI mRNAs in coelomocytes were detected at 24h with 1.73-fold increase and at 6h with 1.83-fold increase compared with the control group, respectively. Similarly, a significant increase in the relative mRNA levels of AjGRP78 and AjPDI was also identified in 1 μg mL(-1) LPS exposed primary cultured coelomocytes. These results collectively suggested that AjGRP78 and AjPDI were ER chaperones of A. japonicus, of which expression is induced upon bacterial infection.

The novel white spot syndrome virus-induced gene, PmERP15, encodes an ER stress-responsive protein in black tiger shrimp, Penaeus monodon

By microarray screening, we identified a white spot syndrome virus (WSSV)-strongly induced novel gene in gills of Penaeus monodon. The gene, PmERP15, encodes a putative transmembrane protein of 15 kDa, which only showed some degree of similarity (54-59%) to several unknown insect proteins, but had no hits to shrimp proteins. RT-PCR showed that PmERP15 was highly expressed in the hemocytes, heart and lymphoid organs, and that WSSV-induced strong expression of PmERP15 was evident in all tissues examined. Western blot analysis likewise showed that WSSV strongly up-regulated PmERP15 protein levels. In WSSV-infected hemocytes, immunofluorescence staining showed that PmERP15 protein was colocalized with an ER enzyme, protein disulfide isomerase, and in Sf9 insect cells, PmERP15-EGFP fusion protein colocalized with ER -Tracker™ Red dye as well. GRP78, an ER stress marker, was found to be up-regulated in WSSV-infected P. monodon, and both PmERP15 and GRP78 were up-regulated in shrimp injected with ER stress inducers tunicamycin and dithiothreitol. Silencing experiments showed that although PmERP15 dsRNA-injected shrimp succumbed to WSSV infection more rapidly, the WSSV copy number had no significant changes. These results suggest that PmERP15 is an ER stress-induced, ER resident protein, and its induction in WSSV-infected shrimp is caused by the ER stress triggered by WSSV infection. Furthermore, although PmERP15 has no role in WSSV multiplication, its presence is essential for the survival of WSSV-infected shrimp.

eIF2α of Litopenaeus vannamei involved in shrimp immune response to WSSV infection

The alpha subunit of Eukaryotic Initiation Factor 2 (eIF2α) is a key translation regulator that plays an important role in cellular stress responses, which including virus infection. To investigate whether WSSV infection can activate the PERK-eIF2α pathway, the eIF2α in shrimp Litopenaeus vannamei, designed as LveIF2α, was analyzed. The LveIF2α, a 332-amino acid polypeptide, shares a high degree of similarity with eIF2α from other species, having two eIF2α protein signatures at the 13-88 aa and 192-243 aa. The WSSV challenge experiment showed that the protein level of the total LveIF2α was decreased after infection, while the phosphorylation of LveIF2α has no significant change, which indicated that the phosphorylation ratio of LveIF2α was increased after infection. Furthermore, inhibitor treatment led to a significant decrease of WSSV loads. Moreover, the Binding immunoglobulin protein (BiP), an endoplasmic reticulum (ER) stress sensor, and PERK were also investigated during virus infection and it was shown that they were both up-regulated. Taken together, these results suggested that WSSV infection can induce ER stress and activated the unfolded protein response (UPR), and the PERK-eIF2α pathway is important for innate immune during WSSV infection in shrimp.

The complex evolutionary dynamics of Hsp70s: a genomic and functional perspective

Hsp70 molecular chaperones are ubiquitous. By preventing aggregation, promoting folding, and regulating degradation, Hsp70s are major factors in the ability of cells to maintain proteostasis. Despite a wealth of functional information, little is understood about the evolutionary dynamics of Hsp70s. We undertook an analysis of Hsp70s in the fungal clade Ascomycota. Using the well-characterized 14 Hsp70s of Saccharomyces cerevisiae, we identified 491 orthologs from 53 genomes. Saccharomyces cerevisiae Hsp70s fall into seven subfamilies: four canonical-type Hsp70 chaperones (SSA, SSB, KAR, and SSC) and three atypical Hsp70s (SSE, SSZ, and LHS) that play regulatory roles, modulating the activity of canonical Hsp70 partners. Each of the 53 surveyed genomes harbored at least one member of each subfamily, and thus establishing these seven Hsp70s as units of function and evolution. Genomes of some species contained only one member of each subfamily that is only seven Hsp70s. Overall, members of each subfamily formed a monophyletic group, suggesting that each diversified from their corresponding ancestral gene present in the common ancestor of all surveyed species. However, the pattern of evolution varied across subfamilies. At one extreme, members of the SSB subfamily evolved under concerted evolution. At the other extreme, SSA and SSC subfamilies exhibited a high degree of copy number dynamics, consistent with a birth–death mode of evolution. KAR, SSE, SSZ, and LHS subfamilies evolved in a simple divergent mode with little copy number dynamics. Together, our data revealed that the evolutionary history of this highly conserved and ubiquitous protein family was surprising complex and dynamic.

Sexual dimorphism in Grp78 and Hsp90A heat shock protein expression in the estuarine copepod Eurytemora affinis

Aquatic organisms are constantly exposed to both natural and anthropogenic stressors. Under stress conditions, they elicit a cellular stress response, involving heat shock proteins (HSPs). HSPs are essential to protect proteins against aggregation and to help in the folding of native proteins or refolding of damaged ones. Because of their conservation among taxons and their inducibility after environmental/chemical stress, HSPs are commonly used as ecological and ecotoxicological biomarkers. However, the appropriate use of such molecular tools requires the investigation of the influence of biotic factors on their basal levels. As a first step in biomarker characterization, the present study aims to evaluate the impact of the reproductive cycle on the expression of the two major HSPs, Grp78 and Hsp90A in the estuarine copepod Eurytemora affinis. The constitutive expression of both genes in males was weak when compared to female levels suggesting gender-specific stress tolerance. Transcript levels gradually increased during oogenesis and maximal levels were recorded in ovigerous females. The present data support the view that the reproductive condition of individuals has to be considered as a confounding factor in stress evaluation by HSP quantification.

ATF4 (activating transcription factor 4) from grass carp (Ctenopharyngodon idella) modulates the transcription initiation of GRP78 and GRP94 in CIK cells

GRP78 and GRP94, belong to GRP (glucose-regulated protein) family of endoplasmatic reticulum (ER) chaperone superfamily, are essential for cell survival under ER stress. ATF4 is a protective protein which regulates the adaptation of cells to ER stress by modulating the transcription of UPR (Unfolded Protein Response) target genes, including GRP78 and GRP94. To understand the molecular mechanism of ATF4 modulates the transcription initiation of CiGRP78 and CiGRP94, we cloned ATF4 ORF cDNA sequences (CiATF4) by homologous cloning techniques. The expression trend of CiATF4 was similar to CiGRP78 and CiGRP94 did under 37 °C thermal stress, namely, the expression of CiATF4 was up-regulated twice at 2 h post-thermal stress and at 18 h post recovery from thermal stress. In this paper, CiATF4 was expressed in BL21 Escherichia coli, and the expressed protein was purified by affinity chromatography with the Ni-NTA His-Bind Resin. On the basis of the cloned CiGRP78 and CiGRP94 cDNA in our laboratory previously, we cloned their promoter sequences by genomic walking approach. In vitro, gel mobility shift assays revealed that CiATF4 could bind to CiGRP78 and CiGRP94 promoter with high affinity. Subsequently, the recombinant plasmid of pGL3-CiGRPs and pcDNA3.1-CiATF4 were constructed and transiently co-transfected into Ctenopharyngodon idella kidney (CIK) cells. The impact of CiATF4 on CiGRP promoter sequences were measured by luciferase assays. These results demonstrated that CiATF4 could activate the transcription of CiGRP78 and CiGRP94. What's more, for better understanding the molecular mechanism of CiATF4 modulate the transcription initiation of CiGRP, three mutant fragments of CiGRP78 promoter recombinant plasmids (called CARE-mut/LUC, CRE1-mut/LUC and CRE2-mut/LUC) were constructed and transiently co-transfected with CiATF4 into CIK cells. The results indicated that CRE or CARE elements were the regulatory element for transcription initiation of CiGRP78. Between them, CRE element would play more important role in it.

Transcriptome analysis of the initial stage of acute WSSV infection caused by temperature change

White spot syndrome virus (WSSV) is the most devastating virosis threatening the shrimp culture industry worldwide. Variations of environmental factors in shrimp culture ponds usually lead to the outbreak of white spot syndrome (WSS). In order to know the molecular mechanisms of WSS outbreak induced by temperature variation and the biological changes of the host at the initial stage of WSSV acute infection, RNA-Seq technology was used to analyze the differentially expressed genes (DEGs) in shrimp with a certain amount of WSSV cultured at 18°C and shrimp whose culture temperature were raised to 25°C. To analyze whether the expression changes of the DEGs were due to temperature rising or WSSV proliferation, the expression of selected DEGs was analyzed by real-time PCR with another shrimp group, namely Group T, as control. Group T didn't suffer WSSV infection but was subjected to temperature rising in parallel. At the initial stage of WSSV acute infection, DEGs related to energy production were up-regulated, whereas most DEGs related to cell cycle and positive regulation of cell death and were down-regulated. Triose phosphate isomerase, enolase and alcohol dehydrogenase involved in glycosis were up-regulated, while pyruvate dehydrogenase, citrate synthase and isocitrate dehydrogenase with NAD as the coenzyme involved in TCA pathway were down-regulated. Also genes involved in host DNA replication, including DNA primase, DNA topoisomerase and DNA polymerase showed down-regulated expression. Several interesting genes including crustin genes, acting binding or inhibiting protein genes, a disintegrin and metalloproteinase domain-containing protein 9 (ADAM9) gene and a GRP 78 gene were also analyzed. Understanding the interactions between hosts and WSSV at the initial stage of acute infection will not only help to get a deep insight into the pathogenesis of WSSV but also provide clues for therapies.

Molecular cloning and expression analysis of a cytosolic heat shock protein 70 gene from mud crab Scylla serrata

Heat shock protein 70s (Hsp70s) play important roles in resisting environmental stresses and stimulating innate immune system. To understand the immune defense mechanisms of Scylla serrata, a full-length cytosolic Hsp70 cDNA of S. serrata (designated as SSHsp70) was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) coupled with rapid amplification of cDNA ends (RACE). The full-length of SSHsp70 cDNA was 2235 bp, with a 5' untranslated region of 105 bp, a 3' untranslated region of 174 bp, and an open reading frame of 1956 bp encoding a polypeptide of 651 amino acids with an estimated molecular mass of 71.3 kDa and an estimated isoelectric point of 5.55. The cloned SSHsp70 belonged to a cytosolic Hsp70 family. Three typical Hsp70 signature motifs were detected in SSHsp70 by InterPro analysis. Quantitative PCR (qPCR) was used to detect tissue distribution and mRNA expression levels of SSHsp70 under different stress conditions. The obviously high levels of SSHsp70 transcript were in hemocyte, heart, hepatopancreas and gill, whereas low levels were detected in muscle, eyestalk, stomach, and gut. In different temperature treatments, the expression levels of SSHsp70 in low or high temperatures were higher than those in temperate temperature. In pathogen challenge treatments, the mRNA expression level of SSHsp70 reached a maximum level after 18 h and then dropped progressively. In different salt concentration treatments, the mRNA expression level of SSHsp70 had a minimum level at 25‰ salt concentration and high expression levels at high or low salt concentration. In different nitrite concentration treatments, the mRNA expression level of SSHsp70 increased progressively with the increase of nitrite concentration. The results confirmed Hsp70 could be used as a tool for evolution and phylogenetic analysis, a kind of potential biomarker, and a disease resistance factor used in application.

Activating transcription factor 4 and X box binding protein 1 of Litopenaeus vannamei transcriptional regulated white spot syndrome virus genes Wsv023 and Wsv083

In response to endoplasmic reticulum (ER) stress, the signaling pathway termed unfolded protein response (UPR) is activated. To investigate the role of UPR in Litopenaeus vannamei immunity, the activating transcription factor 4 (designated as LvATF4) which belonged to a branch of the UPR, the [protein kinase RNA (PKR)-like ER kinase, (PERK)]-[eukaryotic initiation factor 2 subunit alpha (eIF2α)] pathway, was identified and characterized. The full-length cDNA of LvATF4 was 1972 bp long, with an open reading frame of 1299 bp long that encoded a 432 amino acid protein. LvATF4 was highly expressed in gills, intestines and stomach. For the white spot syndrome virus (WSSV) challenge, LvATF4 was upregulated in the gills after 3 hpi and increased by 1.9-fold (96 hpi) compared to the mock-treated group. The LvATF4 knock-down by RNA interference resulted in a lower cumulative mortality of L. vannamei under WSSV infection. Reporter gene assays show that LvATF4 could upregulate the expression of the WSSV gene wsv023 based on the activating transcription factor/cyclic adenosine 3', 5'-monophosphate response element (ATF/CRE). Another transcription factor of L. vannamei, X box binding protein 1 (designated as LvXBP1), has a significant function in [inositol-requiring enzyme-1(IRE1) - (XBP1)] pathway. This transcription factor upregulated the expression of the WSSV gene wsv083 based on the UPR element (UPRE). These results suggest that in L. vannamei UPR signaling pathway transcription factors are important for WSSV and might facilitate WSSV infection.

GRP78 from grass carp (Ctenopharyngodon idella) provides cytoplasm protection against thermal and Pb2+ stress

Glucose regulated protein (GRP) located in endoplasmic reticulum (ER) was a member of heat shock protein (Hsp) family. The protective mechanism adapted to ER stimuli was closely related to GRP. GRP78, known as BiP, was one of central regulator responded to stress in ER. Grass carp (Ctenopharyngodon idella) GRP78 (CiGRP78) was up-regulated in almost tissues, especially in liver, under heat shock (34 °C), cold stress (4 °C) or lead nitrate (0.25 mmol/L) stress. In order to understand the function of CiGRP78 in cellular protection, CiGRP78 ORF cDNA was inserted into the plasmid of pET-32a(+) or pEGFP-C1 respectively, then the recombinant plasmids were transformed or transfected into Escherichia coli cells, mouse myeloma cells (SP2/0) or grass carp kidney cells (CIK). In the cells, CiGRP78 was over-expressed following thermal, cold or Pb(2+) stress. Results showed that CiGRP78 not only contributed to protecting prokaryotic cells against thermal or cold extremes, but also played the same role in SP2/0 and CIK cells. After treatment with heat stress at 42 °C for 1 h, although the viability of the cells declined a lot, CIK cells with pEGFP-C1/CiGRP78 exhibited a higher survival rate (28%) than wild-type cells (7%) or cells with only pEGFP-C1 (5.1%). When the time lag extended to 2.5 h, the survival rates were 19%, 5.7%, 4.8% respectively. In addition, CiGRP78 would also provide a transient cytoplasm protection against Pb(2+) stress in a dose- and time-dependent manner. After treatment with lead nitrate at concentration of 10 μmol/L for 12 h, 24 h or 36 h, the survival rates of cells with pEGFP-C1 or wild-type cells were 46.7% or 46.7% (12 h), 25% or 22% (24 h), 10% or 11% (36 h) respectively. When the cells were treated with lead nitrate at the concentration of 25 μmol/L, the survival rates of cells with pEGFP-C1 or wild-type cells were 45.5% or 30% (12 h), 16.7% or 25% (24 h), 6.5% or 8% (36 h), respectively. CiGRP78 provided a distinct protection in CIK cells at the low concentration for 24 h. The survival rates of CIK cells with pEGFP-C1/CiGRP78 treated with lead nitrate at concentration of 10 μmol/L or 25 μmol/L were 65.9% or 58.8% respectively. When the cells were treated with lead nitrate at concentration of 50 μmol/L for 24 h, the survival rate of the CIK cells was only about 30%. If the process-time was extended to 36 h, CiGRP78 could not provide any cytoplasm protection for CIK cells.

Recent advances in researches on the innate immunity of shrimp in China

The annual production of shrimp culture in mainland of China has been over one million tons for several years. The major cultivated penaeidae species are Litopenaeus vannamei, Fenneropenaeus chinensis, Penaeus monodon and Marsupenaeus japonicus. Due to the importance of shrimp aquaculture in China, researchers have paid more attention to the molecular mechanism of shrimp disease occurrence and tried to develop an efficient control strategy for disease. This paper summarizes the research progress related to innate immunity of penaeid shrimp made in the last decade in Mainland China. Several pattern recognition receptors, such as lectin, toll, lipopolysaccharide and β-1,3-glucan binding protein (LGBP) and tetraspanin were identified. The major signal transduction pathways, including Toll pathway, IMD pathway, which might be involved in the immune response of shrimp, were focused on and most of the components in Toll pathway were identified. Also, cellular immune responses such as phagocytosis and apoptosis were regarded playing very important roles in anti-WSSV infection to shrimp. The molecules involved in the maintenance of the immune homeostasis of shrimp and the progress on molecular structure and pathogenic mechanism of WSSV were summarized. Therefore, the brief outline about the immune system of shrimp is drawn based on the recent data which will help us to understand the immune responses of shrimp to different pathogens.

Identification and characterization of Inositol-requiring enzyme-1 and X-box binding protein 1, two proteins involved in the unfolded protein response of Litopenaeus vannamei

The inositol-requiring enzyme-1 (IRE1)-X-box binding protein 1 (IRE1-XBP1) pathway is the key branch of the unfolded protein response (UPR). To investigate the role of the IRE1-XBP1 pathway in reducing environmental stress and increasing anti-viral immunity in Litopenaeus vannamei, homologues of IRE1 (designated as LvIRE1) and XBP1 (designated as LvXBP1) were identified and characterized. The full-length cDNA of LvIRE1 is 4908bp long, with an open reading frame (ORF) that encodies a putative 1174 amino acid protein. The full-length cDNA of LvXBP1 is 1746bp long. It contains two ORFs that encode putative 278 amino acid and 157 amino acid proteins, respectively. LvXBP1 mRNA has the predicted IRE1 splicing motifs CNG'CNGN located within the loop regions of two short hairpins. Sequencing of the splicing fragment induced by endoplasmic reticulum (ER)-stress showed a 3bp or 4bp frame shift from the predicted sites. The spliced form LvXBP1 (LvXBP1s) contained an ORF encodes a putative 463 amino acid protein. The reporter gene assays indicated that LvXBP1s activates the promoter of L. vannamei immunoglobulin heavy chain binding protein (LvBip), an important UPR effector. RT-PCR showed that LvXBP1 was spliced during the experiments. For heat shock treatment, the total LvXBP1 expression was increased and peaked at about 36h, whereas the percentages of the two isoforms were relatively stable. For the WSSV challenge, LvXBP1 was upregulated during the experiment and the percentage of the spliced form continuously declined after 18h of infection. Knock-down of LvXBP1 by RNA interference resulted in a lower cumulative mortality of L. vannamei under WSSV infection. Furthermore, the expression profiles of LvIRE1 and LvXBP1 in the gills, hemocytes, intestines, and hepatopancreas of the WSSV-challenged shrimp were detected using real-time RT-PCR. Taken together, these results confirm that the IRE1-XBP1 pathway is important for L. vannamei environmental stress resistance, suggest that L. vannamei IRE1-XBP1 may activated by WSSV and be annexed to serve the virus.

Molecular characterization and mRNA expression of grp78 and hsp90A in the estuarine copepod Eurytemora affinis

The present study aimed to develop a method of quantification of heat shock protein transcript levels in the estuarine copepod Eurytemora affinis. For that, the full-length cDNA of the 78-kDa glucose-regulated protein (Ea-grp78) and the cytosolic 90-kDa heat shock protein (Ea-hsp90A) from this species have been cloned. These cDNA revealed, respectively, 2,370 and 2,299 bp with 1,971 and 2,124 bp open reading frames encoding 656 and 707 amino acids. Main features, sequence identities and phylogenetic analysis with other species were described. Then, the expression profiles were analysed using reverse transcription/real-time quantitative PCR method from copepods subjected to different thermic and osmotic stresses in laboratory, and from copepods directly sampled into the natural population of the Seine Estuary (France) along a salinity gradient. Thermic shock (7.5°C, 22.5°C and 30°C during 90 min) significantly induced increases of transcript quantities ranged between 1.7- and 19.7-fold the levels observed in control conditions (15°C). Hypo- and hyper-osmotic shocks (salinities of 1 and 30 during 90 min) caused a 2-fold induction of Ea-hsp90A transcript level in comparison to controls (salinity of 15) whereas no significant change was measured for Ea-grp78. On the other hand, similar expression profiles were observed for the two transcripts after 72 h of exposition to salinities of 1 and 25 with a significant 2-fold induction observed for the lower salinity. To finish, strong expression inductions of both Ea-grp78 and Ea-hsp90A genes were observed in field copepods sampled at low salinity during the campaigns of June 2009 and May 2010. These results tend to show that the low salinity and the increase of temperature seem to have a synergic effect on stress condition of copepods.

The expression of prophenoloxidase mRNA in red swamp crayfish, Procambarus clarkii, when it was challenged

The expression of the prophenoloxidase (proPO) gene was investigated in nine tissues of red swamp crayfish Procambarus clarkii, by real-time PCR after challenges by CpG oligodeoxynucleotide (ODN), Aeromonas hydrophila and white spot syndrome virus (WSSV). The results can be summarized as follows: (i) the expression level of the proPO gene in haemocytes was highest among nine studied tissues before the challenge; (ii) the expression of proPO increased in all studied tissues after stimulation by CpG ODN and WSSV, and also increased in all tissues, except the ovary, after the A. hydrophila challenge; (iii) the whole expression profiles were different, suggesting that different immune mechanisms may exist for crayfish that are resistant to WSSV and A. hydrophila, although the expression in haemocytes was similar before and after the WSSV and A. hydrophila challenges.

Identification of a novel inducible cytosolic Hsp70 gene in Chinese shrimp Fenneropenaeus chinensis and comparison of its expression with the cognate Hsc70 under different stresses

The heat shock protein 70 (Hsp70) family is widely expressed in eukaryotic cells as the major chaperone protein. In this study, the full-length complementary DNA (cDNA) of a novel inducible cytosolic Hsp70 family member (FcHsp70) was cloned from Fenneropenaeus chinensis. FcHsp70 full-length cDNA consists of 2,511 bp with a 1,890-bp open reading frame encoding 629 amino acids. Three Hsp70 protein family signatures, IDLGTTYS, IIDLGGGTFDVSIL, and IVLVGGSTRIPKVQK, were found in the predicted FcHsp70 amino acid sequence. Phylogenetic analysis showed that FcHsp70 was categorized together with the inducible HSP70s reported in other crustaceans. Compared to the previously identified cognate Hsp70 (FcHsc70) in F. chinensis, the expression of FcHsp70 showed quite different expression profiles when the shrimp were subjected to different stresses including heat shock and heavy metal treatments. Under heat shock treatment, the expression of FcHsp70 showed much higher up-regulation than FcHsc70. Copper treatment also induced higher up-regulation of FcHsp70 than FcHsc70. Cadmium treatment did not induce the expression of FcHsp70, but caused down-regulation of FcHsc70. The different expression profiles of FcHsp70 and FcHsc70 in shrimp may indicate their different reactions to different stresses. Therefore, Hsp70 or Hsc70 could be developed as a biomarker to indicate different stresses in shrimp.

Triggers of the HSP70 stress response: environmental responses and laboratory manipulation in an Antarctic marine invertebrate (Nacella concinna)

The Antarctic limpet, Nacella concinna, exhibits the classical heat shock response, with up-regulation of duplicated forms of the inducible heat shock protein 70 (HSP70) gene in response to experimental manipulation of seawater temperatures. However, this response only occurs in the laboratory at temperatures well in excess of any experienced in the field. Subsequent environmental sampling of inter-tidal animals also showed up-regulation of these genes, but at temperature thresholds much lower than those required to elicit a response in the laboratory. It was hypothesised that this was a reflection of the complexity of the stresses encountered in the inter-tidal region. Here, we describe a further series of experiments comprising both laboratory manipulation and environmental sampling of N. concinna. We investigate the expression of HSP70 gene family members (HSP70A, HSP70B, GRP78 and HSC70) in response to a further suite of environmental stressors: seasonal and experimental cold, freshwater, desiccation, chronic heat and periodic emersion. Lowered temperatures (-1.9 degrees C and -1.6 degrees C), generally produced a down-regulation of all HSP70 family members, with some up-regulation of HSC70 when emerging from the winter period and increasing sea temperatures. There was no significant response to freshwater immersion. In response to acute and chronic heat treatments plus simulated tidal cycles, the data showed a clear pattern. HSP70A showed a strong but very short-term response to heat whilst the duplicated HSP70B also showed heat to be a trigger, but had a more sustained response to complex stresses. GRP78 expression indicates that it was acting as a generalised stress response under the experimental conditions described here. HSC70 was the major chaperone invoked in response to long-term stresses of varying types. These results provide intriguing clues not only to the complexity of HSP70 gene expression in response to environmental change but also insights into the stress response of a non-model species.

Comparison of gene expression profiles of Fenneropenaeus chinensis challenged with WSSV and Vibrio

Microarray technique was used to analyze the gene expression profiles of shrimp when they were challenged by WSSV and heat-inactivated Vibrio anguillarum, respectively. At 6 h post challenge (HPC), a total of 806 clones showed differential expression profile in WSSV-challenged samples, but not in Vibrio-challenged samples. The genes coding energy metabolism enzyme and structure protein were the most downregulated elements in 6 h post WSSV-challenged (HPC-WSSV) tissues. However, a total of 155 clones showed differential expression in the Vibrio-challenged samples, but not in WSSV-challenged samples. Serine-type endopeptidase and lysosome-related genes were the most upregulated elements in tissues 6 h post Vibrio challenge (HPC-Vibrio). Totally, 188 clones showed differential expression in both 6 and 12 HPC-WSSV and HPC-Vibrio samples. Most of the differentially expressed genes (185/188) were downregulated in the samples of 12 HPC-WSSV, whereas upregulated in the samples at 6 and 12 HPC-Vibrio and 6 HPC-WSSV. The expression profiles of three differentially expressed genes identified in microarray hybridization were analyzed in hemocytes, lymphoid organ, and hepatopancreas of shrimp challenged by WSSV or Vibrio through real-time PCR. The results further confirmed the microarray hybridization results. The data will provide great help for us in understanding the immune mechanism of shrimp responding to WSSV or Vibrio.