Cloning and expression analysis of heat shock cognate 70 gene promoter in tiger shrimp (Penaeus monodon)

Effects of acute and chronic chromium stress on the expression of heat shock protein genes and activities of antioxidant enzymes in larvae of Orthetrum albistylum

The dragonfly species Orthetrum albistylum, can accumulate heavy metals from its aquatic environment and thus serves as a biological indicator for monitoring and evaluating water quality. Heat shock proteins (HSPs) play important biological roles in resistance to various types of environmental stress. The full-length cDNA sequences of the heat shock cognate (hsc) 70 and heat shock protein (hsp) 70 genes were cloned from O. albistylum larvae. Relative levels of expression of hsc70 and hsp70 in the head, epidermis, midgut, and adipose tissue were measured by qRT-PCR after chronic and acute contamination of 5-8 instar larvae with chromium (Cr) solution, and under control conditions. Activities of superoxide dismutase (SOD) and catalase (CAT) in chronically contaminated larvae were also measured. Phylogenetic analysis revealed that the cloned hsc70 and hsp70 genes were highly homologous to known HSP70 family members reported in other insects. The mRNA levels of hsc70 and hsp70 did not differ significantly in various larval tissues. Under chronic chromium stress, hsc70 and hsp70 expression were upregulated to a maximum and then downregulated; hsp70 mRNA levels were higher than those of hsc70 at all concentrations of chromium. Under acute chromium stress, hsc70 expression was inhibited at low chromium concentrations and upregulated at chromium concentrations higher than 125 mg/L. However, hsp70 expression was higher than that in the control group and markedly higher than that of hsc70. Changes in SOD and CAT activities displayed consistent trends for different chronic chromium concentrations, first increasing and then decreasing over time. Collectively, these findings demonstrated the response of the HSP family of genes and antioxidant enzymes following exposure to heavy metal stress, as well as their potential applicability as biomarkers for monitoring environmental pollutants.

A genome-wide screening of the 70 kDa heat shock protein (HSP70) genes in the rotifer Brachionus plicatilis sensu stricto with a characterization of two heat-inducible HSP70 genes

The 70 kDa heat shock proteins (HSP70s) and the constitutive members of the HSP70 family (heat shock cognates; HSC70s) play essential roles in various biological processes. The number of hsp70/hsc70 in the database is rapidly increasing because of their importance and the automatic annotation of newly sequenced genomes. However, accumulating evidence indicates that neither hsp70 nor hsc70 forms a monophyletic gene family, raising the need to reconsider the annotation strategy based on the traditional concept of the inducible HSP70 and constitutive HSC70s. The main aim of this study is to establish a systematic scheme to annotate hsp70-like genes taking the latest phylogenetic insights into account. We cloned two hsp70s from the rotifer Brachionus plicatilis sensu stricto (s.s.), an emerging model in evolutionary genetics, and conducted a genome-wide screening of B. plicatilis s.s. hsp70s using the two sequences as queries. A total of 15 hsp70-like genes were found, and 7 of them encoded distant members of the HSP70 family, the function of which largely remains unknown. Eight canonical hsp70s were annotated according to a recently proposed nomenclature based on the molecular evolution: e.g., HSP70cA1/B1 for the cytosolic lineage, HSP70er1 for the endoplasmic reticulum lineage, and HSP70m1 for the mitochondrial lineage. The two cloned hsp70s, HSP70cB1 and HSP70cB2, ubiquitously increased their mRNA levels up to 7.5 times after heat treatment as assessed by semi-quantitative PCR, real-time PCR, and in situ hybridization. This systematic screening incorporating a reasonable update to the annotation strategy would provide a useful example for future HSP70 studies, especially those in non-traditional model organisms.

The Role of the Heat Shock Cognate Protein 70 Genes in Sex Determination and Differentiation of Chinese Tongue Sole (Cynoglossus semilaevis)

Fish sex determination can be affected by environmental temperature. This process relies on temperature-sensitive proteins such as heat shock proteins (HSPs). Our previous work found that heat shock cognate proteins (HSCs) may participate in high-temperature associated sex reversal of Chinese tongue sole (Cynoglossus semilaevis). However, the role of hsc genes in responding to high temperature and affecting sex determination/differentiation remains unclear. Here, by using C. semilaevis as model, we identified hsc70 and hsc70-like. hsc70 was abundant in the gonads with a testicular-higher expression at all gonadal development stages except for 6 months post fertilization (mpf). Intriguingly, hsc70-like showed higher expression in testes from 6 mpf on. Both long-term heat treatment during the temperature-sensitive sex-determining period and short-term heat stress at the end of this period caused different expression of hsc70/hsc70-like between sexes. The dual-luciferase assay results also suggested that these genes can respond to high temperature rapidly in vitro. Heat treatment of C. semilaevis testis cells overexpressed with hsc70/hsc70-like could affect the expression of sex-related genes sox9a and cyp19a1a. Our results indicated that hsc70 and hsc70-like were key regulators linking external high-temperature signals with sex differentiation in vivo and provide a new idea for understanding the mechanism by which high temperature affects sex determination/differentiation in teleosts.

Phylogenetic annotation of Drosophila melanogaster heat shock protein 70 genes

The traditional classification of stress-inducible 70 kDa heat shock protein (Hsp70) and heat shock cognate (Hsc70) requires a revision because of a recent finding that neither of them constitutes a monophyletic gene family. Here we inferred a phylogenetic relationship among Drosophila melanogaster Hsp70 family members. D. melanogaster Hsp70 family members were separated into four known metazoan Hsp70 lineages: cytosolic A, cytosolic B, endoplasmic reticulum, and mitochondria. Hsc70s sporadically distributed in the phylogenetic tree, indicating their paraphyletic origin. Detailed sequence inspection found several motifs that support the phylogenetic analysis. Taken together, we propose new aliases of D. melanogaster Hsp70 family members based on their evolutionary history.

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

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

The transcriptional factor GATA-4 negatively regulates Hsp70 transcription in Crassostrea hongkongensis

To better explore the application potential of heat shock protein Hsp70s in diverse areas including biomonitoring, a further investigation of the details of the regulatory mechanism governing Hsp70 transcription is required. A transcriptional factor ChGATA-4 that displayed affinity to the ChHsp70 promoter of Crassostrea hongkongensis was isolated and identified by DNA affinity purification as well as mass spectrometry analysis. The ChGATA-4 cDNA is 2162 bp in length and the open reading frame encodes a polypeptide containing 482 amino acids with a conserved zinc finger domain. The over-expression of ChGATA-4 significantly inhibited the expression of ChHsp70 promoter in heterologous HEK293T cells. However, the depletion of ChGATA-4 mRNA by RNAi technique resulted in significant increase of ChHsp70 transcription in oyster hemocytes. The RT-PCR results demonstrated that the transcription of both ChHsp70 and ChGATA-4 were induced by heat, Cd, or NP (Nonyl phenol) stress. This suggested a potential correlation between ChHsp70 and ChGATA-4 in the stress-mediated genetic regulatory cascade. This study demonstrated that ChGATA-4 acts in a negative manner in controlling ChHsp70 transcription in C. hongkongensis and promotes to further understand the mechanisms leading Hsp70 transcription.

Cloning of a new HSP70 gene from western flowerthrips, Frankliniella occidentalis, and expression patterns during thermal stress

Frankliniella occidentalis (Pergande) is an invasive pest that endangers a wide variety of horticultural and agronomic crops. HSP70 is the most important member of the heat shock protein (HSP) family and plays an important role in insect thermal tolerance. In this study, a new gene encoding HSP70 from F. occidentalis, Fohsp706, was selected from the F. occidentalis transcriptome exposed to thermal stress (40 °C) and cloned by RT-PCR and RACE. Further characterization indicated that Fohsp706 localizes to the cytoplasm and does not contain introns. Quantitative real-time reverse transcriptase PCR indicated that Fohsp706 expression was significantly up-regulated by thermal stress; furthermore, there were significant differences in Fohsp706 expression in adults and second instar nymphs after heat stress. Our results indicated that Fohsp706 contributes to thermotolerance in F. occidentalis and provides another example of how this pest adapts to unfavorable environmental conditions.

Responses of HSP70 Gene to Vibrio parahaemolyticus Infection and Thermal Stress and Its Transcriptional Regulation Analysis in Haliotis diversicolor

Heat-shock protein 70 (HSP70) is a molecular chaperone that plays critical roles in cell protein folding and metabolism, which helps to protect cells from unfavorable environmental stress. Haliotis diversicolor is one of the most important economic breeding species in the coastal provinces of south China. To date, the expression and transcriptional regulation of HSP70 in Haliotis diversicolor (HdHSP70) has not been well characterized. In this study, the expression levels of HdHSP70 gene in different tissues and different stress conditions were detected. The results showed that the HdHSP70 gene was ubiquitously expressed in sampled tissues and was the highest in hepatopancreas, followed by hemocytes. In hepatopancreas and hemocytes, the HdHSP70 gene was significantly up-regulated by Vibrio parahaemolyticus infection, thermal stress, and combined stress (Vibrio parahaemolyticus infection and thermal stress combination), indicating that HdHSP70 is involved in the stress response and the regulation of innate immunity. Furthermore, a 2383 bp of 5'-flanking region sequence of the HdHSP70 gene was cloned, and it contains a presumed core promoter region, a CpG island, a (TG)39 simple sequence repeat (SSR), and many potential transcription factor binding sites. The activity of HdHSP70 promoter was evaluated by driving the expression of luciferase gene in HEK293FT cells. A series of experimental results indicated that the core promoter region is located between -189 bp and +46 bp, and high-temperature stress can increase the activity of HdHSP70 promoter. Sequence-consecutive deletions of the luciferase reporter gene in HEK293FT cells revealed two possible promoter activity regions. To further identify the binding site of the key transcription factor in the two regions, two expression vectors with site-directed mutation were constructed. The results showed that the transcriptional activity of NF-1 site-directed mutation was significantly increased (p < 0.05), whereas the transcriptional activity of NF-κB site-directed mutation was significantly reduced. These results suggest that NF-1 and NF-κB may be two important transcription factors that regulate the expression of HdHSP70 gene.

Heat shock cognate 70 gene in Haliotis diversicolor: responses to pathogen infection and environmental stresses and its transcriptional regulation analysis

Heat shock cognate 70 (HSC70) is a class of highly conserved proteins which functions as a molecular chaperon, participates in tolerance processes, and is involved in protein folding, degradation, targeting, translocation, and protein complex remodeling. In this study, the mRNA expression level of the Haliotis diversicolor HSC70 (HdHSC70) gene was detected by quantitative real-time PCR in different tissues and under different stresses. The results showed that the HdHSC70 gene was ubiquitously expressed in seven selected tissues. The highest expression level was detected in gills (P < 0.05). The expression level of the HdHSC70 gene was significantly upregulated by thermal stress, hypoxia stress, Vibrio parahaemolyticus infection, and combined thermal and hypoxia stress. The upregulation occurred at the early stage of stress. These results indicated that the HdHSC70 is an important component in the immune system of H. diversicolor and is involved in the early stress response. Meanwhile, 5'-flanking region sequence (2013 bp) of the HdHSC70 gene was cloned; it contains a putative core promoter region, heat shock element, CpG, and transcription elements including NF-1, Sp1, Oct-1, interferon consensus sequence binding protein (ICSBP), etc. In HEK 293T cells, the 5'-flanking region sequence is able to drive expression of the enhanced green fluorescent protein (EGFP), proving its promoter function. The promoter activity increased after high-temperature treatment, which may be the immediate reason why the expression of the HdHSC70 gene was significantly upregulated by thermal stress. After the ICSBP-binding site was mutated, we found the luciferase activity significantly reduced, which suggested that the ICSBP-binding site has a certain enhancement effect on the activity of the HdHSC70 promoter.

Expression of heat shock proteins (HSPs) in Aedes aegypti (L) and Aedes albopictus (Skuse) (Diptera: Culicidae) larvae in response to thermal stress

Climatic changes are responsible, to a certain extent for the occurrence and spread of arboviral pathogens world over. Temperature is one of the important abiotic factors influencing the physiological processes of mosquitoes. Several genes of heat shock protein (HSP) families are known to be expressed in mosquitoes, which aid in overcoming stress induced by elevated temperature. In order to understand expression of HSP family genes in the Andaman population of Aedes aegypti and Aedes albopictus, we used quantitative real-time polymerase chain reaction (qPCR) to examine expression levels of HSPs in response to thermal stress under laboratory and in actual field conditions. HSP genes AeaHsp26, AeaHsp83 and AeaHsc70 were examined by comparing relative transcript expression levels at 31°C, 33°C, 34°C, 37°C and 39°C respectively. Enhanced up-regulation of HSPs was evident in third instar larvae of Ae. aegypti with rise in water temperatures (31°C, 33°C, 34°C) in the containers in the nature and thermally stressed (37°C and 39°C) in laboratory conditions. In Ae. albopictus up-regulation of HSPs was observed in field conditions at 34°C only and when thermally treated at 37°C, while down regulation was evident in larvae subjected to thermal stress in laboratory at 39°C. Data on expression levels revealed that larvae of Ae. aegypti was tolerant to thermal stress, while Ae. albopictus larvae was sensitive to heat shock treatment. Statistical analysis indicated that AeaHsp83 genes were significantly up-regulated in Ae. aegypti larvae after 360min exposure to high temperature (39°C). The difference in expression levels of AeaHsp26, AeaHsc70 and AeaHsp83 genes in Ae. albopictus larvae was statistically significant between different exposure temperatures. All of these genes were significantly up-regulated at 37°C. These results indicate that AeaHsp26, AeaHsc70 and AeaHsp83 are important markers of stress and perhaps function as proteins conferring protection and enhance survival of the Andaman population of both the Aedine species. Biological implications of these findings could impact the vector competencies.

Diversity of cytosolic HSP70 Heat Shock Protein from decapods and their phylogenetic placement within Arthropoda

The 70kDa heat shock proteins (HSP70) are considered the most conserved members of the HSP family. These proteins are primordial to the cell, because of their implications in many cellular pathways (e. g., development, immunity) and also because they minimize the effects of multiple stresses (e. g., temperature, pollutants, salinity, radiations). In the cytosol, two ubiquitous HSP70s with either a constitutive (HSC70) or an inducible (HSP70) expression pattern are found in all metazoan species, encoded by 5 or 6 genes (Drosophila melanogaster or yeast and human respectively). The cytosolic HSP70 protein family is considered a major actor in environmental adaptation, and widely used in ecology as an important biomarker of environmental stress. Nevertheless, the diversity of cytosolic HSP70 remains unclear amongst the Athropoda phylum, especially within decapods. Using 122 new and 311 available sequences, we carried out analyses of the overall cytosolic HSP70 diversity in arthropods (with a focus on decapods) and inferred molecular phylogenies. Overall structural and phylogenetic analyses showed a surprisingly high diversity in cytosolic HSP70 and revealed the existence of several unrecognised groups. All crustacean HSP70 sequences present signature motifs and molecular weights characteristic of non-organellar HSP70, with multiple specific substitutions in the protein sequence. The cytosolic HSP70 family in arthropods appears to be constituted of at least three distinct groups (annotated as A, B and C), which comprise several subdivisions, including both constitutive and inducible forms. Group A is constituted by several classes of Arthropods, while group B and C seem to be specific to Malacostraca and Hexapoda/Chelicerata, respectively. The HSP70 organization appeared much more complex than previously suggested, and far beyond a simple differentiation according to their expression pattern (HSC70 versus HSP70). This study proposes a new classification of cytosolic HSP70 and an evolutionary model of the distinct forms amongst the Arthropoda phylum. The observed differences between HSP70 groups will probably have to be linked to distinct interactions with co-chaperones or other co-factors.

Cloning and differential expression of five heat shock protein genes associated with thermal stress and development in the polyphagous predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae)

In order to explore the role of heat shock proteins (Hsps) during thermal stress and development in the predatory mite Neoseiulus cucumeris (Oudemans), we cloned and characterized five full-length Hsp genes. We investigated the expression levels of these genes by quantitative real-time PCR. The five genes characterized here were NcHsp90, NcHsp75, NcHsp70, NcHsp60, and NcHsp40. These Hsps showed high sequence conservation and had greatest identity with heat shock proteins of Metaseiulus occidentalis and other mite and insect species. All five NcHsp genes showed changes in their levels of expression during development. Higher levels of expression were observed in adult females than in adult males, but there were no significant changes between pre-oviposition and post-oviposition stages in the females. NcHsp90, NcHsp75, and NcHsp70 expression levels were up-regulated after a heat shock, and the increases in NcHsp75 and NcHsp70 expression levels were maintained for at least 3 h. Up-regulation of NcHsp60 and NcHsp40 was not detected after 1 h at a high temperature (35-45 °C); however, a significant down-regulation was observed after 3 h heat exposure at 35 °C and 3 h recovery at 25 °C. Cold shock treatment (-5 to 15 °C) for 1 h did not acute elicit changes in the expression levels of any of the genes. At 5 °C, the expression levels of NcHsp90 significantly increased after 6 or 24 h exposure compared to the levels after 1 h exposure. Thus, expression of Hsp genes in N. cucumeris reflected developmental changes, sexual difference, and variable induced response to thermal stress. Increased expression of Hsps might protect N. cucumeris individuals under extreme temperature conditions. Therefore, it may be possible to enhance the thermal tolerance of commercially available N. cucumeris using temperature acclimation. Treatment at 35 °C should be suitable for such acclimation.

Differential regulation of hsp70 genes in the freshwater key species Gammarus pulex (Crustacea, Amphipoda) exposed to thermal stress: effects of latitude and ontogeny

Temperature is one of the main abiotic factors influencing the distribution and abundance of organisms. In the Rhône River Valley, populations of the crustacean Gammarus pulex are distributed along a 5 °C thermal gradient from the North to the South of the valley. In this present work, we investigated the heat shock response of G. pulex according to latitudinal distribution (northern vs. southern populations) and ontogeny (adults vs. embryos from early stages). We isolated two isoforms (one constitutive hsc70 and one inducible hsp70) of heat shock proteins 70 (HSP70) and quantitatively compared their amounts of mRNA after heat shocks, using real-time PCR. Whereas the hsc70 (constitutive) gene did not vary between the two populations, a significant effect of the population was observed on the expression of the hsp70 (inducible) gene in adult specimens. The northern population of amphipods showed a greater magnitude of induction and a 2 °C lower onset temperature when compared to the southern population, suggesting that the northern population is more affected by elevated temperature than the southern one. We demonstrated that the expression of hsp70 may play a crucial role in the persistence of biogeographical patterns of G. pulex, since it reflects the natural distribution of this species along the latitudinal thermal gradient. A differential regulation of hsc70 gene was also observed according to the ontogenetic stage, with a switch from heat inducible in early life stages to constitutively and highly expressed in adults. These findings demonstrate the importance of considering the entire life cycle to better understand the adaptive response to thermal stress.

Phenotypic plasticity of HSP70s gene expression during diapause: signs of evolutionary responses to cold stress among Soybean Pod Borer populations (Leguminivora glycinivorella) in Northeast of China

The soybean pod borer (Leguminivora glycinivorella Matsumura) successfully survives the winter because of its high expression of 70-kDa heat shock proteins (HSP70s) during its overwintering diapause. The amount of HSP70s is different under different environmental stresses. In this study, inducible heat shock protein 70 and its constitutive heat shock cognate 70 were cloned by RT-PCR and RACE. These genes were named Lg-hsp70 and Lg-hsc70, respectively. Gene transcription and protein expression after cold stress treatment (5°C to −5°C) were analyzed by western blotting and by qRT-PCR for four populations that were sampled in the northeast region of China, including Shenyang, Gongzhuling, Harbin and Heihe, when the soybean pod borer was in diapause. As the cold shock temperature decreased, the levels of Lg-HSP70s were significantly up-regulated. The amount of cold-induced Lg-HSP70s was highest in the southernmost population (Shenyang, 41°50′N) and lowest in the northernmost population (Heihe, 50°22′N). These results support the hypothesis that the soybean pod borer in the northeast region of China displays phenotypic plasticity, and the accumulation of Lg-HSP70s is a strategy for overcoming environmental stress. These results also suggest that the induction of HSP70 synthesis, which is a complex physiological adaptation, can evolve quickly and inherit stability.

Genomic organization and promoter analysis of a transcriptional repressor gene from Fenneropenaeus chinensis

In this study, we cloned and sequenced genomic sequences from a Fenneropenaeus chinensis transcriptional repressor gene, FcTR. The FcTR gene is 2,671 bp in length and has four exons and three introns. The 873 bp promoter contains several transcription factor binding sites, including a TATA box and a cyclic AMP-responsive element. Promoter deletion analysis using a luciferase reporter gene identified regulatory elements. Challenge with white spot syndrome virus increased expression from the promoter-deletion constructs. These results suggest that FcTR might play an important role in the shrimp immune response.

Genomic organization of the cytosolic manganese superoxide dismutase gene from the Pacific white shrimp, Litopenaeus vannamei, and its response to thermal stress

Cytosolic manganese superoxide dismutase (cMnSOD) is an important antioxidant enzyme which catalyzes the conversion of superoxides to oxygen and hydrogen peroxide in several organisms. In the Pacific white shrimp, Litopenaeus vannamei, three cMnSOD genes (LvcMnSOD1-3) have previously been characterized. Here, the genomic structure of LvcMnSOD2 and its mRNA expression in response to thermal stress was examined. Analysis of the nucleotide sequence demonstrated that LvcMnSOD2 is comprised of 2392 bp spanning from the ATG translation start site to the stop codon and contains six exons interrupted by five introns. The 5' region upstream of the LvcMnSOD2 gene contains several putative regulatory elements but lacks the accepted TATA sequence. The putative transcription factor binding elements that may be involved in LvcMnSOD2 mRNA expression level include activator protein-1 (AP-1), cAMP response element binding protein (CREB), upstream stimulatory factor (USF), CAAT-enhancer binding protein (C/EBP), nuclear factor-κB (NF-κB) and heat shock regulatory element (HSE). In addition, we compared the 5' upstream sequences of the LvcMnSOD2 gene between two shrimp strains that are resistant or susceptible to Taura syndrome virus (TSV), respectively, which revealed the absence of the USF and C/EBP elements at positions -2125 and -1986, respectively, in the TSV-susceptible shrimp line. Moreover, genomic variations between the two shrimp strains were detected in some of the putative C/EBP, USF, HSE and NF-κB transcription factor binding elements. That these genomic variations might be involved in the TSV resistance as well as in stress responses remains to be evaluated. The presence of 15 putative HSEs suggests that the expression of LvcMnSOD2 is regulated under thermal stress. Here, we found that in response to a 1 or 3 h thermal stress (35 °C), the mRNA expression levels of LvcMnSOD2 were significantly increased and then gradually decreased in the recovering phase at room temperature (25 °C) to control levels by 3 h after the heat shock. Thus, the antioxidant system may be induced to protect cells from the oxidative damage caused by thermal stress. The genomic organization of LvcMnSOD2 likely provides a clue to the mechanisms that might regulate the antioxidant defense pathway in shrimps and so potentially in marine invertebrates.

The new face of the old molecules: crustin Pm4 and transglutaminase type I serving as rnps down-regulate astakine-mediated hematopoiesis

Astakine is an important cytokine that is involved in crustacean hematopoiesis. Interestingly, the protein levels of astakine increased dramatically in plasma of LPS-injected shrimp while mRNA levels remained unchanged. Here, we investigated the involvement of astakine 3'-untranslated region (UTR) in its protein expression. The 3'-UTR of astakine down-regulated the expression of reporter protein but the mRNA stability of reporter gene was unaffected. We identified the functional regulatory elements of astakine 3'-UTR, where 3'-UTR242-483 acted as repressor. The electrophoresis mobility shift assay (EMSA), RNA pull-down assay and LC/MS/MS were performed to identify the protein association. We noted that crustin Pm4 and shrimp transglutaminase I (STG I) were associated to astakine 3'-UTR242-483, while two other proteins have yet to be revealed. Depletion of hemocytic crustin Pm4 and STG I significantly increased the protein level of astakine while astakine mRNA level remained unaffected. Lipopolysaccharide (LPS) stimulated the secretion of crustin Pm4 and STG I from hemocytes to plasma and increased the astakine level to stimulate the hemocytes proliferation. Altogether, we identified the shrimp crustin Pm4 and STG I as novel RNA binding proteins that play an important role in down-regulating astakine expression at post-transcriptional level and are crucial for the maintenance of hematopoiesis.

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.

Functional analysis of the promoter of the heat shock cognate 70 gene of the Pacific white shrimp, Litopenaeus vannamei

Current knowledge on cis-regulatory elements of immune genes of the Pacific white shrimp (Litopenaeus vannamei) is poor. In this study, we identified the promoter of the heat shock cognate protein 70 (HSC70) gene of L. vannamei (lvhsc70). The promoter activity of lvhsc70 promoter was analyzed in insect sf9 cell lines. First, the putative promoter sequence was proved to be able to drive the expression of reporter EGFP gene successfully. Then serial deletion experiments were conducted to investigate functional transcription elements in the promoter region. The results revealed that both positive and negative transcription elements existed in this region. These results are quite different from the previous report on the promoter of HSC70 gene in Penaeus monodon (pmhsc70), where only positive transcription elements were indicated. The sequences that are not conserved between the promoters of lvhsc70 and pmhsc70 might contribute to the differences. Finally, we tested the effect of a putative "NF-κb binding site" in the promoter and, surprisingly, found that deletion of this site would result in a significantly enhancement of the expression of reporter genes, while the underlying mechanisms remain unrevealed. Our results would provide supports for future studies to identify the functional transcription elements in the lvhsc70 promoter and to expand our knowledge on regulation of innate immune genes in penaeid shrimp.

Identification of a heat shock cognate protein 70 gene in Chinese soft-shell turtle (Pelodiscus sinensis) and its expression profiles under thermal stress

The heat shock cognate protein 70 (Hsc70) is a member of a 70-kDa heat shock protein (HSP70) family that functions as molecular chaperones. In this study, a novel Hsc70 gene from Chinese soft-shelled turtle (Pelodiscus sinensis) (tHsc70) was identified. The tHsc70 full-length complementary DNA (cDNA) is 2272 bp long with a 1941-bp open reading frame (ORF) encoding 646 amino acids. Three characteristic signature regions of the HSP70 family, two major domains of an adenosine triphosphate (ATP)/guanosine triphosphate (GTP) binding domain (ABD), and a substrate-binding domain (SBD) were present in the predicted tHsc70 amino acid sequence. The tHsc70 gene was expressed in Escherichia coli BL21 and the expression product reacted with the anti-Hsc70 mouse monoclonal antibody by Western blotting. Homology analysis revealed that tHsc70 shared identity from 53.9% to 87.7% at the nucleotide level, and 49.1% to 99.5% at the amino acid level with the known Hsc70s. Phylogenetic analysis showed that tHsc70 was clustered together with the Hsc70 gene of another reptile species (Alligator mississippiensis). The tHsc70 was expressed in the liver, lung, heart, and skeletal muscle. The expression patterns of tHsc70 messenger RNA (mRNA) differed among different tissues under different durations of heat stress at 40 °C. Adaptation at 25 °C for 1 h after heat stress was also different among tissues and length of heat stress. Irrespective of different profiles of expression under heat stress, tHsc70 may play roles in protecting turtles from thermal stress.

Molecular characterization of heat shock protein 70 gene transcripts during Vibrio harveyi infection of humphead snapper, Lutjanus sanguineus

In the present study, heat shock cognate 70 (HSC70) and inducible heat shock protein 70 (HSP70) gene of humphead snapper, Lutjanus sanguineus, were cloned by rapid amplification of cDNA ends (RACE) technique with the primers designed from the known expressed sequence tags (ESTs) identified from the subtracted cDNA library of the head kidney of humphead snapper. BLAST program analysis indicated that both HSC70 and HSP70 shared high homology with their counterparts in other species. However, the homology between HSC70 and HSP70 is only 82.5% identity. Phylogenetic trees were constructed by the neighbor-joining method, and the results suggested that both HSC70 and HSP70 could be used for phylogenetic analysis at order levels. The expression profiles of HSC70 and HSP70 were measured by fluorescent real-time RT-PCR after Vibrio harveyi infection. Our results suggested that both HSC70 and HSP70 could be induced by V. harveyi challenge. However, the expression pattern of HSP70 showed some differences compared with that of HSC70. Original level of HSP70 in head kidney was lower than that of HSC70. The expression of HSP70 could increase faster and last longer than that of HSC70 and maintain a high level from the time point of 6-15 h. Our results suggested that the rapid transcriptional upregulation of HSC70 and HSP70 in response to V. harveyi infection might be important for the survival of humphead snapper.

Expression pattern of heat-shock cognate 70 gene of humphead snapper, Lutjanus sanguineus (Cuvier), infected by Vibrio harveyi

The heat-shock cognate 70 (HSC70) gene of humphead snapper, Lutjanus sanguineus, designated as ByHSC70, was cloned by rapid amplification of cDNA ends (RACE) with the primers designed from the known expressed sequence tag (EST) identified from the subtracted cDNA library of the head kidney of humphead snapper. The full-length cDNA of ByHSC70 is 2313 bp, containing a 5' terminal untranslated region (UTR) of 96 bp, a 3' terminal UTR of 267 bp, and an open reading frame (ORF) of 1950 bp encoding a polypeptide of 650 amino acids with a theoretical molecular weight of 71.21 kDa and an estimated isoelectric point (pI) of 5.08. ByHSC70 contained three classical HSP70 family signatures. BLAST analysis showed that the amino acid sequence of ByHSC70 had the highest similarity of 99% when compared with other HSC70s. Fluorescent real-time quantitative RT-PCR was used to examine the expression of ByHSC70 gene in eight kinds of tissues/organs of humphead snapper after challenge with Vibrio harveyi. There was a clear time-dependent expression pattern of ByHSC70 in head kidney, spleen and thymus after bacterial challenge, and the expression of mRNA reached a maximum level at 9, 6 and 24 h post-infection and then returned to control levels after 15, 24 and 36 h, respectively. Our results suggest that HSC70 is an important component in the immune system of humphead snapper, its their rapid transcriptional upregulation in response to V. harveyi infection might be important for survival of humphead snapper.

Thermotolerance and hsp70 heat shock response in the cold-stenothermal chironomid Pseudodiamesa branickii (NE Italy)

To better understand the physiological capability of cold-stenothermal organisms to survive high-temperature stress, we analyzed the thermotolerance limits and the expression level of hsp70 genes under temperature stress in the alpine midge Pseudodiamesa branickii (Diptera Chironomidae). A lethal temperature (LT(100)) of 36°C and a lethal temperature 50% (LT(50)) of 32.2°C were found for the cold-stenothermal larvae after short-term shocks (1 h). Additional experiments revealed that the duration of the exposure negatively influenced survival, whereas a prior exposure to a less severe high temperature generated an increase in survival. To investigate the molecular basis of this high thermotolerance, the expression of the hsp70 gene family was surveyed via semi-quantitative reverse transcription-polymerase chain reaction analysis in treated larvae. The constitutive (hsc70) and inducible (hsp70) forms were both analyzed. Larvae of P. branickii showed a significant up-regulation of inducible hsp70 gene with increasing temperatures and an over-expression of both hsp70 and hsc70 by increasing the time of exposure. Different from that was shown in many cold-stenothermal Antarctic organisms, P. branickii was able to activate hsp70 genes transcription (equal to heat shock response) in response to thermal stress. Finally, the unclear relationship between hsp70 expression and survival led us to surmise that genes other than hsp70 and other processes apart from the biochemical processes might generate the high thermaltolerance of P. branickii larvae. These results and future high-throughput studies at both the transcriptome and proteome level will improve our ability to predict the future geographic distribution of this species within the context of global warming.

Fosmid library end sequencing reveals a rarely known genome structure of marine shrimp Penaeus monodon

Background

The black tiger shrimp (Penaeus monodon) is one of the most important aquaculture species in the world, representing the crustacean lineage which possesses the greatest species diversity among marine invertebrates. Yet, we barely know anything about their genomic structure. To understand the organization and evolution of the P. monodon genome, a fosmid library consisting of 288,000 colonies and was constructed, equivalent to 5.3-fold coverage of the 2.17 Gb genome. Approximately 11.1 Mb of fosmid end sequences (FESs) from 20,926 non-redundant reads representing 0.45% of the P. monodon genome were obtained for repetitive and protein-coding sequence analyses.

Results

We found that microsatellite sequences were highly abundant in the P. monodon genome, comprising 8.3% of the total length. The density and the average length of microsatellites were evidently higher in comparison to those of other taxa. AT-rich microsatellite motifs, especially poly (AT) and poly (AAT), were the most abundant. High abundance of microsatellite sequences were also found in the transcribed regions. Furthermore, via self-BlastN analysis we identified 103 novel repetitive element families which were categorized into four groups, i.e., 33 WSSV-like repeats, 14 retrotransposons, 5 gene-like repeats, and 51 unannotated repeats. Overall, various types of repeats comprise 51.18% of the P. monodon genome in length. Approximately 7.4% of the FESs contained protein-coding sequences, and the Inhibitor of Apoptosis Protein (IAP) gene and the Innexin 3 gene homologues appear to be present in high abundance in the P. monodon genome.

Conclusions

The redundancy of various repeat types in the P. monodon genome illustrates its highly repetitive nature. In particular, long and dense microsatellite sequences as well as abundant WSSV-like sequences highlight the uniqueness of genome organization of penaeid shrimp from those of other taxa. These results provide substantial improvement to our current knowledge not only for shrimp but also for marine crustaceans of large genome size.

Cloning and characterization of a hsp70 gene from Asiatic hard clam Meretrix meretrix which is involved in the immune response against bacterial infection

In the present study, a 71.43 kDa heat shock protein cDNA was cloned from Asiatic hard clam Meretrix meretrix. The cDNA was 2292 bp, containing an open reading frame (ORF) of 1959 bp, which encodes a protein of 652 amino acids with a theoretical molecular weight of 71.43 kDa and an isoelectric point of 5.32. Based on the amino acid sequence analysis and phylogenetic analysis, this hsp70 cDNA is a member of cytoplasmic hsc70 (constitutive genes) subfamily in the hsp70 family, and is designated as MmeHsc71. Quantitative RT-PCR was carried out to compare the spatial and temporal expression patterns of MmeHsc71 in the mRNA level between control clams and Vibrio parahaemolyticus-infected clams. Spatially, MmeHsc71 mRNA was found in all tested tissues, including foot, hepatopancreas, mantle and gill. MmeHsc71 mRNA expression level in hepatopancreas and gill displayed a significant increase in vibrio-challenged clams at 24h post-infection compared to control clams (P < 0.05). Temporally, there was a significant increase of MmeHsc71 mRNA level in hepathopancreas of vibrio-challenged clams compared to control clams at 6, 12, and 24h post-challenge, respectively. The result of quantitative immunofluorescence also indicated that there was obvious increase of MmeHsc71 in hepatopancreas of vibrio-challenged clams compared to control clams in protein level at 24h post-infection. The results suggested that MmeHsc71 may play an important role in mediating the immune responses of M. meretrix to bacterial challenge.

Expression of AeaHsp26 and AeaHsp83 in Aedes aegypti (Diptera: Culicidae) larvae and pupae in response to heat shock stress

Immature mosquito development and survival of adults are highly sensitive to environmental temperature, which can alter gene expression during the mosquito life-cycle. To further understand how heat shock proteins are developmentally expressed in mosquitoes, we subjected first instar larvae, 16-h old pupae and female of Aedes aegypti (L.) (Diptera: Culicidae) to heat shock treatment for 0, 15, 30, 60, and 180 min at 23 and 42 degrees C. The heat shock protein genes AeaHsp26, AeaHsp83, and AeaHsc70 were examined by comparing relative transcript expression levels at 42 degrees C compared with 23 degrees C. Upregulated transcripts from heat shock treatment at 42 degrees C and control were further confirmed and quantified by quantitative real-time polymerase chain reaction. Data revealed that first instar larvae were more sensitive to heat shock treatment than pupae and adults (i.e., relative AeaHsp26 expression levels in larvae were 10-fold greater than in the females. AeaHsp83 expression levels in larvae, pupae and adults were upregulated 2- to 50-fold greater by heat shock treatment at 42 degrees C compared with 23 degrees C. AeaHsc70 expression levels in larvae, pupae and adults, however, were upregulated less than AeaHsp26 and AeaHsp83 at the higher temperature. Statistical analysis indicated that AeaHsp26 and AeaHsp83 genes were significantly upregulated in Ae. aegypti larvae and pupae after 15, 30, 60, and 180 min exposure to high temperature (42 degrees C). The current study has shown that AeaHsp26 and AeaHsp83 are important markers of stress and may function as critical proteins to protect and enhance survival of Ae. aegypti larvae and pupae.

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.

Identification of genes differentially expressed during heat shock treatment in Aedes aegypti

Temperature is important for mosquito development and physiological response. Several genes of heat shock protein (HSP) families are known to be expressed in mosquitoes and may be crucial in responding to stress induced by elevated temperature. Suppression subtractive hybridization (SSH) was used to identify target transcripts to heat shock treatment in female Aedes aegypti. Subtraction was performed in both directions enriching for cDNAs differentially expressed between a non-heat shock control and heat shock treatment. Heat shock treatment of female Ae. aegypti was carried out for 1 h at 42 degrees C. Clones from differentially expressed genes were evaluated by sequencing. Target transcripts up-regulated by heat shock included five different HSP gene families and 27 other genes, such as cytochrome c oxidase, serine-type endopeptidase, and glutamyl aminopeptidase. Additionally, some novel genes, cytoskeleton and ribosomal genes, were found to be differentially expressed, and three novel up-regulated sequences belonging to a low-abundance class of transcripts were obtained. Up-regulated/down-regulated transcripts from heat shock treatment were further confirmed and quantified by quantitative real-time polymerase chain reaction (PCR). High temperatures can alter the gene expression of a vector mosquito population, and further characterization of these differentially expressed genes will provide information useful in understanding the genetic response to heat shock treatment, which can be used to develop novel approaches to genetic control.

Gene discovery from an ovary cDNA library of oriental river prawn Macrobrachium nipponense by ESTs annotation

The oriental river prawn, Macrobrachium nipponense, is an important crustacean species in aquaculture. However, early gonad maturity is a ubiquitous problem which devalues the product quality. While husbandry and nutritional management have achieved little success in tackling this issue, a molecular approach may discover the genes involved in reproduction and development, which will provide the basic knowledge on reproductive control. In this study, a high-quality cDNA library of prawn was constructed from the ovary tissue. A total of 3294 successful sequencing reactions yielded 3256 expressed sequence tags (ESTs) longer than 100 bp. The cluster and assembly analyses yielded 1514 unique sequences including 414 contigs and 1168 singletons. About 719 (47.49%) unique sequences were identified as orthologs of genes from other organisms. By sequence comparability analysis, 28 important genes including cathepsin B, chromobox protein, Cdc2, cyclin B, DEAD box protein and ADF/cofilin protein were expressed. These genes may be involved in reproductive and developmental functions in prawn. Peritrophin consisting of cortical rods was also found in this species. The identification of these EST sequences in M. nipponense would improve our understanding on the genes that regulate reproduction and development in prawn species. This study also lays the groundwork for development of molecular markers related to ovary development in other prawn species.

Ex vivo promoter analysis of antiviral heat shock cognate 70B gene in Anopheles gambiae

Background

The Anopheles gambiae heat shock cognate gene (hsc70B) encodes a constitutively expressed protein in the hsp70 family and it functions as a molecular chaperone for protein folding. However, the expression of hsc70B can be further induced by certain stimuli such as heat shock and infection. We previously demonstrated that the An. gambiae hsc70B is induced during o'nyong-nyong virus (ONNV) infection and subsequently suppresses ONNV replication in the mosquito. To further characterize the inducibility of hsc70B by ONNV infection in An. gambiae, we cloned a 2.6-kb region immediately 5' upstream of the starting codon of hsc70B into a luciferase reporter vector (pGL3-Basic), and studied its promoter activity in transfected Vero cells during infection with o'nyong-nyong, West Nile and La Crosse viruses.

Results

Serial deletion analysis of the hsc70B upstream sequence revealed that the putative promoter is likely located in a region 1615–2150 bp upstream of the hsc70B starting codon. Sequence analysis of this region revealed transcriptional regulatory elements for heat shock element-binding protein (HSE-bind), nuclear factor κB (NF-κB), dorsal (Dl) and fushi-tarazu (Ftz). Arbovirus infection, regardless of virus type, significantly increased the hsc70B promoter activity in transfected Vero cells.

Conclusion

Our results further validate the transcriptional activation of hsc70B during arbovirus infection and support the role of specific putative regulatory elements. Induction by three taxonomically distinct arboviruses suggests that the HSC70B protein may be expressed to cope with cellular stress imposed during infection.

A heat shock cognate 70 gene in the endoparasitoid, Pteromalus puparum, and its expression in relation to thermal stress

The Pphsc70 (heat shock cognate 70) gene was isolated from the endoparasitoid Pteromalus puparum and then characterized. The full-length cDNA was 2204 base pair (bp) and contained a single 1968 bp ORF that encoded a polypeptide of 656 amino acids with a predicted molecular mass of 71.28 kDa. Phylogenetic analysis based on Hsc70 amino acid sequences from fifteen insect species agreed with the present phylogeny. In addition, genomic DNA confirmed the presence of three introns located at the coding region as well as the 5'UTR. A significant elevation of Pphsc70 expression was observed following heat treatment, however, continued exposure to heat shock or recovery caused the expression of induced mRNA to gradually decline to levels that were significantly lower than those of control pupae (P < 0.05). In addition, a significant increase was observed in the emergence rate of pupae that were preheated at 40 degrees C and then exposed to 50 degrees C for 1 h when compared with the pupae that were not preheated, but instead directly exposed to 50 degrees C. Taken together, these results revealed that exposure to gradually increasing temperatures can enhance an insects thermo-tolerance.