The mitochondrial 60-kDa heat shock protein in marine invertebrates: biochemical purification and molecular characterization

Comparison of Physicochemical Characteristics and Macrophage Immunostimulatory Activities of Polysaccharides from Chlamys farreri

To address the structure-activity relationship of Chlamys farreri polysaccharides on their immunostimulatory efficacy, two polysaccharides (CFP-1 and CFP-2) were extracted from Chlamys farreri by hot water extraction, and separated through column chromatography. The isolated CFPs were chemically analyzed to clarify their physicochemical characteristics and cultured with murine macrophage RAW264.7 cells, in order to evaluate their immunostimulatory efficacy. Despite the fact that both CFP-1 and CFP-2 were mainly comprised of glucose lacking the triple-helix structure, as revealed through preliminary physicochemical analyses, obvious differences in regard to molecular weight (Mw), glucuronic acid content (GAc) and branching degree (BD) were observed between CFP-1 and CFP-2. In in vitro immunostimulatory assays for macrophage RAW264.7 cells, it was demonstrated that CFP-2 with larger Mw, more GAc and BD could evidently promote phagocytosis and increase the production of NO, IL-6, TNF-α and IL-1β secretion, by activating the expression of iNOS, IL-6, TNF-α and IL-1β genes, respectively. Hence, CFP-2 shows great promise as a potential immunostimulatory agent in the functional foods and nutraceutical industry, while CFP-1, with lower molecular weight, less GAc and BD, displays its weaker immunostimulatory efficacy, based on the indistinctive immunostimulatory parameters of CFP-1.

Molecular characteristics of a novel HSP60 gene and its differential expression in Manila clams (Ruditapes philippinarum) under thermal and hypotonic stress

The Manila clam Ruditapes philippinarum inhabits the intertidal zone and must therefore tolerate broad fluctuations in water temperature and salinity. Heat shock protein 60 (HSP60) is an evolutionarily conserved, multi-functional protein that plays a significant role in protecting organisms from harmful stress conditions. We cloned the R. philippinarum HSP60 (RpHSP60) gene and analyzed its transcriptional responses to thermal and low-salinity stresses. The complete sequence of RpHSP60 cDNA was 1777 nucleotides, containing a 1728-bp open reading frame encoding a polypeptide of 576-amino acids, with a calculated molecular mass of 61.25 kDa and predicted isoelectric point of 5.08. Comparisons of amino acid sequences and three-dimensional structures of HSP60 revealed that RpHSP60 was highly conserved in the signature HSP60-family domains. RpHSP60 mRNA was detected in all the tested tissues of R. philippinarum, with the highest expression levels in hemocytes. We measured RpHSP60 mRNA levels in the gills under thermal and low-salinity stresses using quantitative real-time reverse transcription-polymerase chain reaction. Following the thermal challenge, RpHSP60 mRNA was significantly upregulated at 6 h, and then progressively downregulated under high-temperature stress (30 °C), while only slight fluctuations were observed under low-temperature stress (-1 °C). Under low-salinity (17 ppt) stress, RpHSP60 mRNA levels were significantly increased at 3, 72, and 96 h (P < 0.05). These results suggest that HSP60 of R. philippinarum may play important roles in responding to high-temperature and low-salinity stresses.

Interaction of heat shock protein 60 (HSP60) with microRNA in Chinese mitten crab during Spiroplasma eriocheiris infection

Heat shock protein 60 from the Chinese mitten crab Eriocheir sinensis (EsHSP60) was previously identified in relation to Spiroplasma eriocheiris infection by isobaric tags for relative and absolute quantitation labelling followed by liquid chromatography-tandem mass spectrometry. In the present study, to validate the immune function of this protein, the cDNA of the EsHSP60 gene was cloned. Various crab tissues were assessed using real-time PCR, which showed that EsHSP60 transcription occurred in all tissues examined. The expression profiles of EsHSP60 in haemolymph at transcription and protein levels when infected with S. eriocheiris were investigated by real-time PCR and Western blot analysis, respectively. A significant increase of EsHSP60 transcription and protein expression appeared post-injection in response to S. eriocheiris infection when compared to the control group. The double-luciferase reporter gene assay showed that the microRNA PC-533-3p interacted with the 3'-untranslated region of EsHSP60 and inhibited the translation of EsHSP60. The expression profiles of PC-533-3p during S. eriocheiris infection were also investigated by real-time PCR. However, the change tendency of PC-533-3p was opposite to that of the EsHSP60 after S. eriocheiris challenge. These data indicate that the EsHSP60 proteins may play an important role in mediating the immune responses of E. sinensis to an S. eriocheiris challenge.

Silver nanoparticles and dissolved silver activate contrasting immune responses and stress-induced heat shock protein expression in sea urchin

Using immune cells of sea urchin Strongylocentrotus droebachiensis in early development as a model, the cellular protective mechanisms against ionic and poly(allylamine)-coated silver nanoparticle (AgNPs; 14 ± 6 nm) treatments at 100 μg L^-1 were investigated. Oxidative stress, heat shock protein expression, and pigment production by spherulocytes were determined as well as AgNP translocation pathways and their multiple effects on circulating coelomocytes. Sea urchins showed an increasing resilience to Ag over time because ionic Ag is accumulated in a steady way, although nanoAg levels dropped between 48 h and 96 h. A clotting reaction emerged on tissues injured by dissolved Ag (present as chloro-complexes in seawater) between 12 h and 48 h. Silver contamination and nutritional state influenced the production of reactive oxygen species. After passing through coelomic sinuses and gut, AgNPs were found in coelomocytes. Inside blood vessels, apoptosis-like processes appeared in coelomocytes highly contaminated by poly(allylamine)-coated AgNPs. Increasing levels of Ag accumulated by urchins once exposed to AgNPs pointed to a Trojan-horse mechanism operating over 12-d exposure. However, under short-term treatments, physical interactions of poly(allylamine)-coated AgNPs with cell structures might be, at some point, predominant and responsible for the highest levels of stress-related proteins detected. The present study is the first report detailing nano-translocation in a marine organism and multiple mechanisms by which sea urchin cells can deal with toxic AgNPs. Environ Toxicol Chem 2017;36:1872-1886. © 2016 SETAC.

Heavy metals induce oxidative stress and trigger oxidative stress-mediated heat shock protein (hsp) modulation in the intertidal copepod Tigriopus japonicus

Heat shock proteins (hsps) are induced by a wide range of environmental stressors including heavy metals in aquatic organisms. However, the effect of heavy metals on zooplankton at the molecular level remains still unclear. In this study, we measured the intracellular reactive oxygen species (ROS) level and the antioxidant enzyme activities for 96 h after exposure to five heavy metals: arsenic (As), cadmium (Cd), copper (Cu), silver (Ag), and zinc (Zn) in the intertidal copepod Tigriopus japonicus. Activities of the antioxidant enzymes were highly elevated in metal-exposed copepods, indicating that heavy metals can induce oxidative stress by generating ROS, and stimulate the involvement of antioxidant enzymes as cellular defense mechanisms. Subsequently, transcriptional changes in hsp gene families were further investigated in the metal-exposed groups for 96 h. The ROS level and glutathione (GSH) content were significantly increased in Ag-, As-, and Cu-exposed copepods, while they were only slightly elevated in Cd- and Zn-exposed groups. Based on the numbers of significantly modulated hsp genes and their expression levels for 96 h, we measured the effect of heavy metals to stress genes of T. japonicus in the following order: Cu > Zn > Ag > As > Cd, implying that Cu acts as a stronger oxidative stress inducer than other heavy metals. Of them, the expression of hsp20 and hsp70 genes was substantially modulated by exposure to heavy metals, indicating that these genes would provide a sensitive molecular biomarker for aquatic monitoring of heavy metal pollution.

Hsp60 in caudal fin regeneration from Paramisgurnus dabryanus: molecular cloning and expression characterization

Heat shock protein 60 (Hsp60) is a kind of highly conserved immunogenic molecule involved in a wide range of biochemical processes in response to external stressors. Its multifunction in regulating immune responses and modulating signal pathway interests us in investigating its role in fin regeneration that has become an excellent and interesting model for studying the molecular basis of morphogenesis. We firstly clarified basical process and crucial period of caudal fins regeneration in Paramisgurnus dabryanus by histological analysis. Then we cloned full-length cDNA of hsp60 from P. dabryanus (designated as PdHsp60) by RACE method. The cDNA contains a 124 bp 5'UTR, a 1731 bp open reading frame (ORF) encoding 576 amino acids and a 510 bp 3'UTR (Accession no.: KF544774). The phylogenetic tree shows that the PdHsp60 fits within the hsp60 clade. And quantitative RT-PCR detected the PdHsp60 began to increase rapidly its expression at 1 dpa and reached its peak at 2 dpa. Next, spatial distribution analysis of PdHsp60 in fins showed that PdHsp60 located mainly in the deeper lay of regenerated epidermis when PdHsp60 expressed most. After the PdHsp60 had been cloned into the pET-32a vector, SDS-PAGE and Western blotting analysis confirmed that the PdHsp60 protein was efficiently expressed in Escherichia coli BL21. These findings have revealed that PdHsp60, a highly conserved gene related to the innate immune system and stress response during vertebrate evolution, is involved in response to wounding stimulation--in the formation of wound epidermis which occurs as the first phase of fin regeneration after fin amputation in caudal fin regeneration.

Characterization and expression of SpHsp60 in hemocytes after challenge to bacterial, osmotic and thermal stress from the mud crab Scylla paramamosain

Hsp60 play a crucial role in the process of pathogenic and protective immune responses and is implicated in autoimmune disease. In order to understand the environmental response and immune response of this gene, we cloned a Hsp60 (SpHsp60) gene from the mud crab Scylla paramamosain, localized SpHsp60 in hemocytes by in situ hybridization, and detected the expression of SpHsp60 after stresses in relation to three housekeeping genes (β-actin, 18S rRNA and GAPDH). The full-length of the SpHsp60 cDNA was found to be 2424 bp. The predicted ORF encoded a protein of 576 amino acids with a predicted molecular mass of 61.19 kDa and a theoretical isoelectric point (pI) of 5.46. It shared high scoring identity 95% with the swimming crab Portunus trituberculatus. In situ hybridization assay showed that a higher expression occurred in the granular and semigranular cells when compared to the hyaline hemocytes. It suggested that SpHsp60 was mainly contributed from the granular and semigranular cells in hemolymph. The expression level of SpHsp60 in hemocytes showed a clear time-dependent pattern during the 96 h after stimulated by Vibrio alginolyticus. During this experiment the gene was induced and the highest expression level was observed at 3 h. The significantly up-regulated expression and rapid response of SpHsp60 indicated that the crabs were sensitive to bacterial challenge. After osmotic stress, the expression of SpHsp60 in hemocytes showed that this gene was induced by the high salinity (30‰) and the crabs had its adaptive responses to high salinity, when compared to the normal salinity (15‰). SpHsp60 mRNA expression in hemocytes was analyzed after thermal stress at 6 h, the highest and the lowest expression levels of SpHsp60 were observed at 36 and 32 °C, respectively. This study demonstrated that SpHsp60 was easily induced at the higher temperatures. Based on our research, SpHsp60 participate in innate immune and environmental response of S. paramamosain. It could be used as a biomarker to test the stress caused by the local aquaculture environment.

Corals from the Persian/Arabian Gulf as models for thermotolerant reef-builders: prevalence of clade C3 Symbiodinium, host fluorescence and ex situ temperature tolerance

Corals in the Arabian/Persian Gulf endure summer temperatures of up to 36°C, making them ideal subjects to study the mechanisms underlying thermal tolerance. Unexpectedly, we found the "generalist" Symbiodinium clade C3 to be the prevalent symbiont among seven coral species from Abu Dhabi (UAE) waters. Moreover, C3 represented the only dominant symbiont type in Porites spp. from this region. The "thermotolerant" symbionts D1a and C15 were not encountered, indicating that the association with these symbionts cannot be the sole reason for the heat tolerance of Gulf corals. The association of Porites lobata with specific symbiont types (C3 vs. C15) in samples from habitats with very different temperature regimes (Abu Dhabi vs. Fiji) remained unaffected by laboratory culture. During temperature stress experiments specimens from both locations strongly downregulated green fluorescent protein (GFP)-like pigments. However, the Abu Dhabi samples were less prone to bleaching and showed lower mortality.

Molecular cloning of heat shock protein 60 (PtHSP60) from Portunus trituberculatus and its expression response to salinity stress

Heat shock protein 60 (HSP60) is a highly conserved and multi-functional molecular chaperone that plays an essential role in both cellular metabolism and stress response. Portunus trituberculatus is an important marine fishery and aquaculture species, and water salinity condition influenced its artificial propagations significantly. In order to investigate the function of P. trituberculatus HSP60 against osmotic stress, P. trituberculatus HSP60 gene was firstly cloned. The full-length cDNA of PtHSP60 contains 1,743 nucleotides encoding 577 amino acids with a calculated molecular weight of 61.25 kDa. Multiple alignments indicated that the deduced amino acid sequences of PtHSP60 shared a high level of identity with invertebrate and vertebrate HSP60 sequence including shrimp, fruit fly, zebrafish, and human. The expression profiles of PtHSP60 at mRNA and protein levels under salinity treatment were investigated by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. It was found that the mRNA transcripts of PtHSP60 gene varied among different tissues under normal salinity conditions, and the antennal gland showed the highest expression level among the tissues tested. As for low salinity challenge, the mRNA expression of PtHSP60 gene was higher in the gill and appendicular muscle compared with other tissues, and gill and hypodermis represented the higher gene expressions during the hyperosmotic stress, which indicated that those tissues were salinity-sensitive tissues. In addition, salinity challenges significantly altered the expression of PtHSP60 at mRNA and protein level in a salinity- and time-dependent manner in P. trituberculatus gill tissue. The results indicate that PtHSP60 played important roles in mediating the salinity stress in P. trituberculatus.

Global transcriptome profiling of the pine shoot beetle, Tomicus yunnanensis (Coleoptera: Scolytinae)

Background

The pine shoot beetle Tomicus yunnanensis (Coleoptera: Scolytinae) is an economically important pest of Pinus yunnanensis in southwestern China. Developed resistance to insecticides due to chemical pesticides being used for a long time is a factor involved in its serious damage, which poses a challenge for management. In addition, highly efficient adaptation to divergent environmental ecologies results in this pest posing great potential threat to pine forests. However, the molecular mechanisms remain unknown as only limited nucleotide sequence data for this species is available.

Methodology/Principal Findings

In this study, we applied next generation sequencing (Illumina sequencing) to sequence the adult transcriptome of T. yunnanensis. A total of 51,822,230 reads were obtained. They were assembled into 140,702 scaffolds, and 60,031 unigenes. The unigenes were further functionally annotated with gene descriptions, Gene Ontology (GO), Clusters of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genome (KEGG). In total, 80,932 unigenes were classified into GO, 13,599 unigenes were assigned to COG, and 33,875 unigenes were found in KO categories. A biochemical pathway database containing 219 predicted pathways was also created based on the annotations. In depth analysis of the data revealed a large number of genes related to insecticides resistance and heat shock protein genes associated with environmental stress.

Conclusions/Significance

The results facilitate the investigations of molecular resistance mechanisms to insecticides and environmental stress. This study lays the foundation for future functional genomics studies of important biological questions of this pest.

Characterization of heat shock protein 70 in the red claw crayfish (Cherax quadricarinatus): evidence for its role in regulating spermatogenesis

Heat shock protein 70 (HSP70) is a member of molecular chaperones and is important for reproductive biological processes in eukaryotes. In this regard, a full length HSP70 comprised of 2366 nucleotides from the red claw crayfish Cherax quadricarinatus (CqHSP70) was characterized, which with an open-reading frame of 1959 bp encoded 652 amino acid residues. Its mRNA transcript expression in the testes was measured by real-time quantitative PCR. CqHSP70 mRNA transcripts were detected in all organs especially high in the testes. Furthermore, the greatest transcript levels were found during the spermatogonial preparation phase, while the lowest levels were found during the resting stage of the reproductive cycle. In addition, its distribution in the testes was determined by Western blot and immunohistochemistry. Western blot results revealed a single immunoreactive band with an estimated molecular mass of 70 kDa in different phases of testes development. The strongest immunolabeling positive signal was found in spermatogonia, with lower positive staining in secondary spermatocytes, and weak or absent level in the mature sperm. Interestingly, CqHSP70 was mainly located in the cytoplasm of sperm cells. Thus, our results indicate that CqHSP70 is an essential protein in spermatogenesis, with a crucial reproductive function during sperm maturation in invertebrates.

The molecular characterization and expression of heat shock protein 90 (Hsp90) and 26 (Hsp26) cDNAs in sea cucumber (Apostichopus japonicus)

The heat shock proteins (HSPs) are a family of proteins whose expression is enhanced in response to environmental stressors. The Apostichopus japonicus hsp90 and hsp26 genes were cloned using expressed sequence tag and rapid amplification of cDNA ends techniques. The full-length cDNA of Aphsp90 and Aphsp26 contains 3,458 and 1,688 nucleotides encoding 720 and 236 amino acids, respectively. Multiple alignments indicated that the deduced amino acid sequences of ApHsp90 and ApHsp26 shared a high level of identity with Hsp90 and small SHPs (sHSPs) sequences of zebrafish, ant, acorn worms, etc., and shared identical structural features with Hsp90 and sHSPs. The expression profiles of these two genes under heat treatment were investigated by real-time quantitative PCR. It was found that the messenger RNA (mRNA) transcripts of the two A. japonicus genes varied among different tissues under normal conditions and heat shock, and that the mRNA expression of the two genes was higher in the intestine compared to other tissues. Heat shock significantly elevated the expression of Aphsp90 and Aphsp26 mRNA in a temperature- and time-dependent manner. The results indicate that Aphsp90 and Aphsp26 played important roles in mediating the environmental stress in A. japonicus.

Expression of HSP60 and HSP70 in white shrimp, Litopenaeus vannamei in response to bacterial challenge

In the present study, cDNA encoding a heat shock protein 60 (LvHSP60) gene in Litopenaeus vannamei was cloned using a combination of homology and rapid amplification of cDNA end (RACE) methods. The full length of the LvHSP60 cDNA was found to be 2379bp, with a 1737bp open reading frame. The translated amino acid sequence consisted of 579 residues with a calculated molecular mass of 60.8kD and an isoelectronic point (pI) of 5.97. Comparison of the deduced amino acid sequence showed that it has high identity (85-89%) with HSP60/chaperonins from insects and mammals. Quantitative real-time PCR and Western blot analysis were carried out to investigate the expression patterns and distribution profiles of LvHSP60 before and after stimulation with the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Vibrio alginolyticus. LvHSP60 mRNA was found to be both constitutive and inducible, and was highly expressed in haemocytes and almost all tissues examined, including muscle, stomach, heart, hepatopancreas and gill tissue, but it was less strongly expressed in the intestine. The expression analysis revealed that LvHSP60 was significantly up-regulated in the gills, hepatopancreas and haemocytes after bacterial challenge. Transcription of LvHSP70 was also induced in haemocytes and the hepatopancreas after different bacteria injection. Subsequent flow cytometry analysis showed that the concentration of Ca(2+) ions increased significantly within bacteria-challenged haemocytes by 1.5h after injection. The results indicate that LvHSP60 and LvHSP70 may play important roles in mediating the immune responses of L. vannamei to bacterial challenge, and that the Ca(2+) signalling transduction pathway may be involved in the initiation of the shrimp's immune responses in early stages of infection.

Increased light intensity induces heat shock protein Hsp60 in coral species

The effect of increased light intensity and heat stress on heat shock protein Hsp60 was examined in two coral species using a branched coral and a laminar coral, selected for their different resistance to environmental perturbation. Transient Hsp60 induction was observed in the laminar coral following either light or thermal stress. Sustained induction was observed when these stresses were combined. The branched coral exhibited comparatively weak transient Hsp60 induction after heat stress and no detectable induction following light stress, consistent with its susceptibility to bleaching in native environments compared to the laminar coral. Our observations also demonstrate that increased light intensity and heat stress exhibited a greater negative impact on the photosynthetic capacity of environmentally sensitive branched coral than the more resistant laminar coral. This supports a correlation between stress induction of Hsp60 and (a) ability to counter perturbation of photosynthetic capacity by light and heat stress and (b) resistance to environmentally induced coral bleaching.

Sublethal stress: Impact of solar UV radiation on protein synthesis in the copepod Acartia tonsa

Aquatic organisms respond to environmental challenges such as thermal stress with the rapid induction of highly conserved polypeptides known as stress proteins or heat shock proteins (Hsps). Solar ultraviolet radiation (UVR, 280-400 nm) is an important environmental stressor in marine ecosystems. Here, we present results of experiments conducted with the marine copepod Acartia tonsa to follow the de novo protein synthesis and measure the level of constitutive and inducible isoforms of the Hsp70 gene family of stress proteins after UV exposure. Animals were collected from Tampa Bay, Florida (USA), and exposed to solar radiation (full spectrum), UV-A (320-400 nm) and PAR (400-700 nm), or PAR only, for periods of 0.5-4 h. Controls were kept in the dark. Protein synthesis was robust under all treatments when the copepods were exposed to low solar radiation intensities. Conversely, high solar radiation intensities (both UV-B and UV-A) caused an overall suppression in the protein synthesis of the copepods with no detectable induction of stress-inducible isoforms of Hsps. Immunochemical assays (western blotting) showed that UVR increased levels (3.5-4-fold increase compared to the dark control) of the constitutively expressed 70 kDa heat-shock (Hsc70) protein in A. tonsa, without indication of inducible isoform upregulation.

Environmental sensing and response genes in cnidaria: the chemical defensome in the sea anemone Nematostella vectensis

The starlet sea anemone Nematostella vectensis has been recently established as a new model system for the study of the evolution of developmental processes, as cnidaria occupy a key evolutionary position at the base of the bilateria. Cnidaria play important roles in estuarine and reef communities, but are exposed to many environmental stressors. Here, I describe the genetic components of a "chemical defensome" in the genome of N. vectensis and review cnidarian molecular toxicology. Gene families that defend against chemical stressors and the transcription factors that regulate these genes have been termed a chemical defensome and include the cytochromes P450 and other oxidases, various conjugating enyzymes, the ATP-dependent efflux transporters, oxidative detoxification proteins, as well as various transcription factors. These genes account for about 1% (266/27,200) of the predicted genes in the sea anemone genome, similar to the proportion observed in tunicates and humans, but lower than that observed in sea urchins. While there are comparable numbers of stress-response genes, the stress sensor genes appear to be reduced in N. vectensis relative to many model protostomes and deuterostomes. Cnidarian toxicology is understudied, especially given the important ecological roles of many cnidarian species. New genomic resources should stimulate the study of chemical stress sensing and response mechanisms in cnidaria and allow us to further illuminate the evolution of chemical defense gene networks.