Induction of heat-shock (stress) protein gene expression by selected natural and anthropogenic disturbances in the octocoral Dendronephthya klunzingeri

Deciphering temporal gene expression dynamics in multiple coral species exposed to heat stress: Implications for predicting resilience

Coral reefs are facing unprecedented threats due to global climate change, particularly elevated sea surface temperatures causing coral bleaching. Understanding coral responses at the molecular level is crucial for predicting their resilience and developing effective conservation strategies. In this study, we conducted a comprehensive gene expression analysis of four coral species to investigate their long-term molecular response to heat stress. We identified distinct gene expression patterns among the coral species, with laminar corals exhibiting a stronger response compared to branching corals. Heat shock proteins (HSPs) showed an overall decreasing expression trend, indicating the high energy cost associated with sustaining elevated HSP levels during prolonged heat stress. Peroxidases and oxidoreductases involved in oxidative stress response demonstrated significant upregulation, highlighting their role in maintaining cellular redox balance. Differential expression of genes related to calcium homeostasis and bioluminescence suggested distinct mechanisms for coping with heat stress among the coral species. Furthermore, the impact of heat stress on coral biomineralization varied, with downregulation of carbonic anhydrase and skeletal organic matrix proteins indicating reduced capacity for biomineralization in the later stages of heat stress. Our findings provide insights into the molecular mechanisms underlying coral responses to heat stress and highlight the importance of considering species-specific responses in assessing coral resilience. The identified biomarkers may serve as indicators of heat stress and contribute to early detection of coral bleaching events. These findings contribute to our understanding of coral resilience and provide a basis for future research aimed at enhancing coral survival in the face of climate change.

Characterizing transcriptomic responses to sediment stress across location and morphology in reef-building corals

Anthropogenic activities increase sediment suspended in the water column and deposition on reefs can be largely dependent on colony morphology. Massive and plating corals have a high capacity to trap sediments, and active removal mechanisms can be energetically costly. Branching corals trap less sediment but are more susceptible to light limitation caused by suspended sediment. Despite deleterious effects of sediments on corals, few studies have examined the molecular response of corals with different morphological characteristics to sediment stress. To address this knowledge gap, this study assessed the transcriptomic responses of branching and massive corals in Florida and Hawai'i to varying levels of sediment exposure. Gene expression analysis revealed a molecular responsiveness to sediments across species and sites. Differential Gene Expression followed by Gene Ontology (GO) enrichment analysis identified that branching corals had the largest transcriptomic response to sediments, in developmental processes and metabolism, while significantly enriched GO terms were highly variable between massive corals, despite similar morphologies. Comparison of DEGs within orthogroups revealed that while all corals had DEGs in response to sediment, there was not a concerted gene set response by morphology or location. These findings illuminate the species specificity and genetic basis underlying coral susceptibility to sediments.

Transcriptional response of the calcification and stress response toolkits in an octocoral under heat and pH stress

Up to one-third of all described marine species inhabit coral reefs, but the future of these hyperdiverse ecosystems is insecure due to local and global threats, such as overfishing, eutrophication, ocean warming and acidification. Although these impacts are expected to have a net detrimental effect on reefs, it has been shown that some organisms such as octocorals may remain unaffected, or benefit from, anthropogenically induced environmental change, and may replace stony corals in future reefs. Despite their potential importance in future shallow-water coastal environments, the molecular mechanisms leading to the resilience to anthropogenically induced stress observed in octocorals remain unknown. Here, we use manipulative experiments, proteomics and transcriptomics to show that the molecular toolkit used by Pinnigorgia flava, a common Indo-Pacific gorgonian octocoral, to deposit its calcium carbonate skeleton is resilient to heat and seawater acidification stress. Sublethal heat stress triggered a stress response in P. flava but did not affect the expression of 27 transcripts encoding skeletal organic matrix (SOM) proteins. Exposure to seawater acidification did not cause a stress response but triggered the downregulation of many transcripts, including an osteonidogen homologue present in the SOM. The observed transcriptional decoupling of the skeletogenic and stress-response toolkits provides insights into the mechanisms of resilience to anthropogenically driven environmental change observed in octocorals.

Short-term spatiotemporal biomarker changes in oysters transplanted to an anthropized estuary in Southern Brazil

Estuarine ecosystems are increasingly being affected by pollution caused by anthropogenic activities. In this study, Crassostrea gasar oysters were transplanted and maintained for seven days at three sites (S1, S2, and S3) in the Laguna Estuarine System (LES)-situated in southern Brazil-that has been exposed to multiple anthropic stresses. On the basis of the concentrations of metal and organic pollutants in oysters, we identified marked spatial variations in pollutant levels, with S3 showing the highest concentration of Ag, Fe, Ni, Zn, and total polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and linear alkylbenzenes (LABs), followed by S2 and S1. Along with the concentrations of pollutants, a set of biomarkers was analyzed. Oysters maintained at S3 showed enhanced protective defenses in gills, as observed by the increased levels of superoxide dismutase (SOD-like) and heat shock protein 90 (HSP90-like) transcripts and catalase (CAT) activity, concomitant with reduced lipid peroxidation (MDA) levels. Decreased antioxidant activities together with increased MDA levels are indicative of the digestive gland being more susceptible to pollutant-induced oxidative damage. Oysters transplanted into LES showed lower levels of cytochrome P450 transcripts (CYP356A1-like and CYP2AU1), and decreased glutathione S-transferase (GST) enzyme activity, suggesting lower biotransformation capacity. By integrating information regarding the concentration of metal and organic pollutants with that of molecular as well as biochemical biomarkers, our study provides novel insights into pollutant exposure and the potential biological impacts of such exposure on estuarine organisms in southern Brazil.

The past, present, and future of coral heat stress studies

The global loss and degradation of coral reefs, as a result of intensified frequency and severity of bleaching events, is a major concern. Evidence of heat stress affecting corals through loss of symbionts and consequent coral bleaching was first reported in the 1930s. However, it was not until the 1998 major global bleaching event that the urgency for heat stress studies became internationally recognized. Current efforts focus not only on examining the consequences of heat stress on corals but also on finding strategies to potentially improve thermal tolerance and aid coral reefs survival in future climate scenarios. Although initial studies were limited in comparison with modern technological tools, they provided the foundation for many of today's research methods and hypotheses. Technological advancements are providing new research prospects at a rapid pace. Understanding how coral heat stress studies have evolved is important for the critical assessment of their progress. This review summarizes the development of the field to date and assesses avenues for future research.

Physiological resilience of a temperate soft coral to ocean warming and acidification

Atmospheric concentration of carbon dioxide (CO2) is increasing at an unprecedented rate and subsequently leading to ocean acidification. Concomitantly, ocean warming is intensifying, leading to serious and predictable biological impairments over marine biota. Reef-building corals have proven to be very vulnerable to climate change, but little is known about the resilience of non-reef-building species. In this study, we investigated the effects of ocean warming and acidification on the antioxidant enzyme activity (CAT-catalase, and GST-glutathione S-transferase), lipid peroxidation (using malondialdehyde, MDA-levels as a biomarker) and heat shock response (HSP70/HSC70 content) of the octocoral Veretillum cynomorium. After 60 days of acclimation, no mortalities were registered in all treatments. Moreover, CAT and GST activities, as well as MDA levels, did not change significantly under warming and/or acidification. Heat shock response was significantly enhanced under warming, but high CO2 did not have a significant effect. Contrasting to many of their tropical coral-reef relatives, our findings suggest that temperate shallow-living octocorals may be able to physiologically withstand future conditions of increased temperature and acidification.

Immune response of the bay scallop, Argopecten irradians, after exposure to the algicide palmitoleic acid

Palmitoleic acid (PA) is an effective algicide against the toxin-producing dinoflagellate Alexandrium tamarense; however, its effects on the immune system of the edible bay scallop Argopecten irradians are unclear. Therefore, we investigated the effects of PA on the immune response in A. irradians by assessing total haemocyte counts (THC), alkaline phosphatase activity (ALP), nitrite oxide (NO), glutathione (GSH), and lactate dehydrogenase (LDH) levels, as well as the expression of immune-related genes (FREP, PGRP, HSP90, MnSOD, and Cu/ZnSOD) at various hours post-exposure (hpe) to the compound. THC decreased in PA-treated groups, whereas ALP increased significantly in all of the PA treatment groups at 3 hpe, after which it significantly decreased. The LDH and NO levels were significantly enhanced in the high and medium concentration group. Notably, the GSH level increased in all PA treatment groups at each time interval. Our study revealed that after treatment with different concentrations of PA, variable effects on the expression of genes involved in the immune system response were observed. The results of our study demonstrate that immersing scallops in PA at effective concentrations could result in differential effects on immune system responses and expression of immune-related genes. Specifically, PA may disrupt the endocrine system or affect signal transduction pathways in the scallops. Therefore, the present study highlights the potential risk of using the PA as an algicide to control algal bloom outbreaks in the marine environment.

Proteomic profiling of healthy and diseased hybrid soft corals Sinularia maxima × S. polydactyla

Emerging diseases of marine invertebrates have been implicated as one of the major causes of the continuing decline in coral reefs worldwide. To date, most of the focus on marine diseases has been aimed at hard (scleractinian) corals, which are the main reef builders worldwide. However, soft (alcyonacean) corals are also essential components of tropical reefs, representing food, habitat and the 'glue' that consolidates reefs, and they are subject to the same stressors as hard corals. Sinularia maxima and S. polydactyla are the dominant soft corals on the shallow reefs of Guam, where they hybridize. In addition to both parent species, the hybrid soft coral population in Guam is particularly affected by Sinularia tissue loss disease. Using label-free shotgun proteomics, we identified differences in protein expression between healthy and diseased colonies of the hybrid S. maxima × S. polydactyla. This study provided qualitative and quantitative data on specific proteins that were differentially expressed under the stress of disease. In particular, metabolic proteins were down-regulated, whereas proteins related to stress and to symbiont photosynthesis were up-regulated in the diseased soft corals. These results indicate that soft corals are responding to pathogenesis at the level of the proteome, and that this label-free approach can be used to identify and quantify protein biomarkers of sub-lethal stress in studies of marine disease.

Induction of hsp70, hsp90, and catalase activity in planarian Dugesia japonica exposed to cadmium

The hsp70 and hsp90 expression patterns and catalase (CAT) activity in the freshwater planaria Dugesia japonica exposed to cadmium (Cd) under laboratory conditions were investigated. Planaria were exposed to a range of Cd concentrations (0–150 μg Cd/L) for 24 h. The expression levels of hsp70 and hsp90 were determined by relative quantitative real-time polymerase chain reaction. Within the overall dose range in the experiment, the expression level of hsp70 and the activity of CAT in D. japonica were altered significantly. Hsp70 was induced in D. japonica upon Cd exposure concentrations as low as 9.375 μg Cd/L. No significant effect on the expression level of hsp90 was observed. Our findings demonstrated that stress gene hsp70, but not hsp90, was responsive to Cd contamination in D. japonica. CAT activity was significantly induced at concentrations of 18.75, 37.5, and 75 μg Cd/L after 24-h exposure. We recommend that the use of hsp70 as a biomarker should be complemented by evidence of changes in other parameters, such as CAT activity, in D. japonica.

Sub-lethal coral stress: detecting molecular responses of coral populations to environmental conditions over space and time

In order for sessile organisms to survive environmental fluctuations and exposures to pollutants, molecular mechanisms (i.e. stress responses) are elicited. Previously, detrimental effects of natural and anthropogenic stressors on coral health could not be ascertained until significant physiological responses resulted in visible signs of stress (e.g. tissue necrosis, bleaching). In this study, a focused anthozoan holobiont microarray was used to detect early and sub-lethal effects of spatial and temporal environmental changes on gene expression patterns in the scleractinian coral, Montastraea cavernosa, on south Florida reefs. Although all colonies appeared healthy (i.e. no visible tissue necrosis or bleaching), corals were differentially physiologically compensating for exposure to stressors that varied over time. Corals near the Port of Miami inlet experienced significant changes in expression of stress responsive and symbiont (zooxanthella)-specific genes after periods of heavy precipitation. In contrast, coral populations did not demonstrate stress responses during periods of increased water temperature (up to 29°C). Specific acute and long-term localized responses to other stressors were also evident. A correlation between stress response genes and symbiont-specific genes was also observed, possibly indicating early processes involved in the maintenance or disruption of the coral-zooxanthella symbiosis. This is the first study to reveal spatially- and temporally-related variation in gene expression in response to different stressors of in situ coral populations, and demonstrates that microarray technology can be used to detect specific sub-lethal physiological responses to specific environmental conditions that are not visually detectable.

Assessing the effects of polychlorinated biphenyls (Aroclor 1254) on a scleractinian coral (Stylophora pistillata) at organism, physiological, and molecular levels

Polychlorinated biphenyls (PCBs) are a group of widespread contaminants, and accumulation of PCBs has been observed in corals in the field. However, the toxic effects of PCBs on corals have not been investigated. In this study, we tested short and long term toxicity of Aroclor 1254, a commercial PCB mixture, on the scleractinian coral Stylophora pistillata. Coral nubbins were incubated in either control seawater or seawater dosed with PCBs (approximately 300ng/L) for 96h. The effect of PCB exposure on coral gene expression at 4h post exposure was tested with the suppression subtractive hybridization (SSH) and quantitative PCR methods. Photosystem II activity of the zooxanthellae was measured at 96h. After the exposure, nubbins were moved into clean seawater and their survival and growth were observed for another 50 days. All nubbins survived during the exposure and the following 50-d recovery period. Photosystem II activity and coral growth were not affected by PCB exposure in this study. Fifty-four clones were sequenced for gene expression analysis, and 15% of these sequences were identified, including genes involved in general stress response, peptide metabolism, cellular receptor, cytoskeleton organization, membrane trafficking, and oxidative stress response. However, the quantitative PCR did not show significant difference in the five selected genes. In conclusion, acute exposure of S. pistillata to Aroclor 1254 at 300ng/L did not affect coral survival, photosynthesis or growth but may alter the expression of certain genes involved in various important cellular functions. The nubbin technique proved to be an efficient approach to simultaneously characterize the impact of PCBs on the corals at multiple biological levels.

Expression pattern of heat shock protein 90 gene of humphead snapper Lutjanus sanguineus during pathogenic Vibrio harveyi stress

The full-length cDNA of heat shock protein 90 (HSP90) of humphead snapper Lutjanus sanguineus, designated as rsHSP90, was cloned by rapid amplification of complementary (c)DNA ends (RACE) techniques with the primers designed from the known expressed sequence tag (EST) sequence identified from the subtracted cDNA library of the head kidney of L. sanguineus. Sequence analysis showed that the full-length cDNA of rsHSP90 was 2745 bp, containing a 5' terminal untranslated region (UTR) of 99 bp, a 3' terminal UTR of 471 bp and an open reading frame (ORF) of 2175 bp encoding a polypeptide of 725 amino acids. On the basis of the deduced amino acid sequence, the theoretical molecular mass of rsHSP90 was calculated to be 83·18 kDa with an isoelectric point of 4·79. Moreover, five classical HSP90 family signatures were found in the amino acids sequence of rsHSP90 by PredictProtein. Basic local-alignment search-tool (BLAST) analysis revealed that the amino acids sequence of rsHSP90 had the highest similarity of 97% when compared with other HSP90s. Fluorescent real-time quantitative reverse-transcription (RT)-PCR was used to examine the expression pattern of rsHSP90 in eight kinds of tissues and organs of L. sanguineus challenged with Vibrio harveyi. There was a clear time-dependent expression pattern of rsHSP90 in head kidney, spleen and thymus after bacterial challenge and the expression of messenger (m)RNA reached the maximum level at the time points of 9, 15 and 24 h, respectively. The up-regulated mRNA expression of rsHSP90 in L. sanguineus after bacterial challenge indicated that rsHSP90 was inducible and might be involved in immune response.

Impact of metals on histopathology and expression of HSP 70 in different tissues of Milk fish (Chanos chanos) of Kaattuppalli Island, South East Coast, India

Histological and Immunohistochemical studies were carried out to document the possible impact of heavy metal contamination in different tissues of Chanos chanos. Heavy metals such as Cu, Pb, Zn, Cd, Mn and Fe were predominant in water, sediment and biota of Kaattuppalli Island and varied significantly between two different sites. Histological changes such as swelling of muscle fiber and break down of muscle bundles were noted in the muscle. Similarly gill filament cell proliferation, increase in intercellular spaces and primary and secondary lamellar epithelium were evident in gills. The hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish collected from polluted site compared to that from the less polluted site. The impact of pollution was also assessed in different tissues by immunohistochemistry using primary antibody (mouse monoclonal HSP70 antibody 1:2000) and secondary antibody (HRP conjugated antibody) for expression of stress protein. Immunostaining analysis showed expression of HSP70 with high intensity in the tissues of fish collected from polluted site compared to less polluted sites. Further, HSP70 positive cells were analyzed from six locations per fish tissue section. One-way analysis of variance (ANOVA) followed by least significant difference (LSD) was used to check if the expression was significant. Results indicate that the values are statistically significant at the two different sampling sites (P<0.05).

Assembled catalog of immune-related genes from allogeneic challenged corals that unveils the participation of vWF-like transcript

While reef-building corals portray highly complex and specific allorecognition responses, still, no available synthesis on historecognition at the molecular level exists for this group of organisms. Here, we present the first subtractive library of expressed sequence tags (ESTs) from allogeneic challenged coral (Stylophora pistillata) colonies revealing the differential expression of a wide range of immune-related genes. 1760 unique ESTs were clustered and assembled into 230 contigs and 1530 singlets with 28% that showed homology (E-value < or =0.005) to known database sequences, of which 16% (n=80) homologues were identified as immune-relevant genes, encoding for stress proteins, pattern recognition receptors and complement proteins, proteases, cell adhesion proteins, cytokine related proteins, programmed cell death and proteasome-associated proteins. Transcripts that were subjected to quantitative RT-PCR, further supported the library data. In situ hybridization analyses elucidated specific and enhanced expressions of von Willebrand factor-like transcript during S. pistillata allogeneic rejection. Availability of such genome-wide expression tools may lead to significant advances in the research of coral historecognition and comparative immunology.

Cloning of an orange-spotted grouper Epinephelus coioides heat shock protein 90AB (HSP90AB) and characterization of its expression in response to nodavirus

The heat shock proteins (HSPs) family which consists of HSP90, HSP70, and low molecular mass HSPs are involved in chaperone activity. Here, we report the cloning and characterization of HSP90AB gene from orange-spotted grouper, Epinephelus coioides. The full-length of grouper HSP90AB was 727 amino acids and possessed an ATPase domain as well as an evolutionarily conserved molecular chaperone. The HSP90AB-green fluorescent protein fusion protein was evenly distributed in the cytoplasm. Immunohistochemistry (IHC) and real-time polymerase chain reaction (PCR) analyses indicated that the expression of grouper HSP90AB was marginally increased following nodavirus infection. Grouper E. coioides that received HSP90 inhibitor geldanamycin (GA) showed an increase in HSP90AB expression and growth of nodavirus supporting nodavirus replication.

Molecular characterization and induction of heat shock protein 90 in the Antarctic bivalve Laternula elliptica

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that plays a key role in protein synthesis, folding, denaturation prevention, and signal transduction. We cloned the complete complementary DNA (cDNA) sequence of the Laternula elliptica HSP90. The full-length cDNA was 2,823 bp in size and contained an open reading frame of 2,190 bp that was translated into 729 amino acids with a calculated molecular weight of 83.4 kDa. The deduced amino acid sequence of HSP90 showed the highest homology to Haliotis tuberculata HSP90 (83%). Reverse-transcriptase polymerase chain reaction analysis revealed the presence of HSP90 transcripts in all of the tissues examined. We also studied the transcriptional expression pattern of HSP90 exposed to thermal stress with real-time polymerase chain reaction. The relative expression level of HSP90 messenger RNA was upregulated and peaked at 12 h in the digestive gland and at 24 h in the gills, then dropped progressively.

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.

Molecular cloning, characterization and expression of heat shock protein 90 gene in the haemocytes of bay scallop Argopecten irradians

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that plays key roles in the folding, maintenance of structural integrity and regulation of a subset of cytosolic proteins. In the present study, the cDNA of Argopecten irradians HSP90 (designated AiHSP90) was cloned by the combination of homology cloning and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of AiHSP90 was of 2669 bp, including an open reading frame (ORF) of 2175 bp encoding a polypeptide of 724 amino acids with predicted molecular weight of 83.08 kDa and theoretical isoelectric point of 4.81. BLAST analysis revealed that AiHSP90 shared high similarity with other known HSP90s, and the five conserved amino acid blocks defined as HSP90 protein family signatures were also identified in AiHSP90, which indicated that AiHSP90 should be a cytosolic member of the HSP90 family. Fluorescent real-time quantitative PCR was employed to examine the expression pattern of AiHSP90 mRNA in haemocytes of scallops challenged by Gram-negative bacteria Vibrio anguillarum and Gram-positive bacteria Micrococcus luteus. In both bacterial challenged groups, the relative expression level of AiHSP90 transcript was up-regulated and reached maximal level at 9h after injection, and then dropped progressively to the original level at about 48 h post challenge. The results indicated that AiHSP90 was potentially involved in the immune responses against bacteria challenge in scallop A. irradian.

cDNA cloning and mRNA expression of heat shock protein 90 gene in the haemocytes of Zhikong scallop Chlamys farreri

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone contributing to the folding, maintenance of structural integrity and proper regulation of a subset of cytosolic proteins. The full-length cDNA of Zhikong scallop Chlamys farreri HSP90 (designated CfHSP90) was cloned by EST and rapid RACE techniques. It was of 2710 bp, including an open reading frame (ORF) of 2181 bp encoding a polypeptide of 726 amino acids with all the five HSP90 family signatures. BLAST analysis revealed that the CfHSP90 gene shared high similarity with other known HSP90 genes. Fluorescent real-time quantitative RT-PCR was used to examine the expression pattern of CfHSP90 mRNA in haemocytes of scallops exposed to Cd2+, Pb2+ and Cu2+ for 10 and 20 days, respectively. All the three heavy metals could induce CfHSP90 expression. There was a clear dose-dependent expression pattern of CfHSP90 after heavy metals exposure for 10 days or 20 days. Different concentrations of the same metal resulted in different effects on CfHSP90 expression. The results indicated that CfHSP90 responded to various heavy metal stresses with a dose-dependent expression pattern as well as exposure time effect, and could be used as a molecular biomarker in a heavy metal polluted environment.

Identification of cDNAs encoding HSP70 and HSP90 in the abalone Haliotis tuberculata: Transcriptional induction in response to thermal stress in hemocyte primary culture

Heat-shock proteins are a multigene family of proteins whose expression is induced by a variety of stress factors. This work reports the cloning and sequencing of HSP70 and HSP90 cDNAs in the gastropod Haliotis tuberculata. The deduced amino acid sequences of both HSP70 and HSP90 from H. tuberculata shared a high degree of homology with their homologues in other species, including typical eukaryotic HSP70 and HSP90 signature sequences. We examined their transcription expression pattern in abalone hemocytes exposed to thermal stress. Real-time PCR analysis indicated that both HSP70 and HSP90 mRNA were expressed in control animals but rapidly increased after heat-shock.

Expression of heat shock and cold shock proteins in the gorgonian Leptogorgia virgulata

In this study, we analyzed the response of the temperate, shallow-water gorgonian, Leptogorgia virgulata, to temperature stress. Proteins were pulse labeled with (35)S-methionine/cysteine for 1 h to 2 h at 22 degrees C (control), or 38 degrees C, or for 4 h at 12.5 degrees C. Heat shock induced synthesis of unique proteins of 112, 89, and 74 kDa, with 102, 98 and 56 kDa proteins present in the control as well. Cold shock from 22 degrees C-12.5 degrees C induced the synthesis of a 25 kDa protein, with a 44 kDa protein present in the control as well. Control samples expressed unique proteins of 38, and 33 kDa. Non-radioactive proteins expressed under the same conditions as above, as well as natural field conditions, were tested for reactivity with antibodies to heat shock proteins (HSPs). HSP60 was the major protein found in L. virgulata. Although HSP47, HSP60, and HSP104 were present in all samples, the expression of HSP60 was enhanced in heat stressed colonies, while HSP47 and HSP104 expression were greatest in cold shocked samples. Inducible HSP70 was expressed in cold-shocked, heat-shocked, and field samples. Constitutively expressed HSP70 was absent from all samples. The expression of HSP90 was limited to heat shocked colonies. The expression of both HSP70 and HSP104 suggests that the organism may also develop a stress tolerance response.