Evaluation of the relationship between the 14-3-3ε protein and LvRab11 in the shrimp Litopenaeus vannamei during WSSV infection

The 14-3-3 proteins interact with a wide variety of cellular proteins for many diverse functions in biological processes. In this study, a yeast two-hybrid assay revealed that two 14-3-3ε isoforms (14-3-3ES and 14-3-3EL) interacted with Rab11 in the white shrimp Litopenaeus vannamei (LvRab11). The interaction of 14-3-3ε and LvRab11 was confirmed by a GST pull-down assay. The LvRab11 open reading frame was 645 bp long, encoding a protein of 214 amino acids. Possible complexes of 14-3-3ε isoforms and LvRab11 were elucidated by in silico analysis, in which LvRab11 showed a better binding energy score with 14-3-3EL than with 14-3-3ES. In shrimp challenged with the white spot syndrome virus (WSSV), the mRNA expression levels of LvRab11 and 14-3-3ε were significantly upregulated at 48 h after challenge. To determine whether LvRab11 and binding between 14-3-3ε and LvRab11 are active against WSSV infection, an in vivo neutralization assay and RNA interference were performed. The results of in vivo neutralization showed that LvRab11 and complexes of 14-3-3ε/LvRab11 delayed mortality in shrimp challenged with WSSV. Interestingly, in the RNAi experiments, the silencing effect of LvRab11 in WSSV-infected shrimp resulted in decreased ie-1 mRNA expression and WSSV copy number. Whereas suppression of complex 14-3-3ε/LvRab11 increased WSSV replication. This study has suggested two functions of LvRab11 in shrimp innate immunity; (1) at the early stage of WSSV infection, LvRab11 might play an important role in WSSV infection processes and (2) at the late stage of infection, the 14-3-3ε/LvRab11 interaction acquires functions that are involved in immune response against WSSV invasion.

Evaluation of probiotic characteristics and whole genome analysis of Pediococcus pentosaceus MR001 for use as probiotic bacteria in shrimp aquaculture

The development of non-antibiotic and environmentally friendly agents is a key consideration for health management in shrimp aquaculture. In this study, the probiotic potential in shrimp aquaculture of Pediococcus pentosaceus MR001, isolated from Macrobrachium rosenbergii, was investigated by means of feeding trial and genetic characterization. In the feeding trial, dietary supplementation with P. pentosaceus MR001 significantly increased weight gain and digestive enzyme activity (p < 0.05) in shrimp, Litopenaeus vannamei. The intestinal histology showed that shrimp given the probiotic diet had healthier guts than the control group. Also, the immune gene expression and the survival rate in the treatment group were significantly increased when compared with the control group. The genetic characteristics of P. pentosaceus strain MR001 were explored by performing whole-genome sequencing (WGS) using the HiSeq 2500 platform and PacBio system, revealing the complete circular genome of 1,804,896 bp. We also identified 1789 coding genes and subsequently characterized genes related to the biosynthesis of bacteriocins, stress resistance, and bile tolerance. Our findings suggest that insights in the functional and genetic characteristics of P. pentosaceus strain MR001 could provide opportunities for applications of such strain in shrimp diet supplementation.

Copper and zinc differentially affect root glutathione accumulation and phytochelatin synthase gene expression of Rhizophora mucronata seedlings: Implications for mechanisms underlying trace metal tolerance

Mangroves are susceptible to contamination due to their proximity to shores and human activities. Exposure to excessive trace metals can disturb their physiological functions and may eventually lead to death. Rhizophora mucronata is a common species growing in the mangrove forests of Thailand. Previous studies have shown that seedlings of R. mucronata are tolerant of trace metal and that they accumulate a large metal content in their root tissue. However, knowledge of their tolerance mechanisms is still lacking. To elicit the role of metal detoxification and sequestration by phytochelatins (PC) in the roots of R. mucronata seedlings, the impacts of Cu and Zn exposure were assessed on 1) physiological characteristics 2) the concentration of glutathione (GSH), a precursor of PC and 3) the level of the transcripts encoding phytochelatin synthase (PCS), the key enzyme for PC biosynthesis. Seedlings of R. mucronata were exposed to Cu and Zn in a hydroponic experiment (200 mg Cu or Zn/L in 1/4× Hoagland solution containing 8‰ NaCl, single addition). We found that both trace metals were largely accumulated in the roots. Only Cu-treated seedlings showed a decrease in the photosynthetic efficiency, in line with observed toxicity symptoms (i.e. bent stems and slight wilting of leaves). Metal accumulation, however, did not induce oxidative stress in the roots as indicated by similar level of total reactive species and lipid peroxidation across treatments. The GSH content in the roots exposed to Cu was significantly reduced while no change was observed in Zn-exposed roots. Coordinated semi-quantitative PCR and RT-qPCR revealed pcs down-regulation in Cu-treated roots, whereas Zn-treated roots showed a down-regulation on day 1 and a subsequent recovery on day 5. Failure of detoxification and sequestration of excess Cu due to GSH limitation and down-regulation of pcs may lead to the phytotoxic effects observed in Cu-treated plants. Our results suggest that both GSH and PC play an important role in trace metal tolerance in R. mucronata seedlings.

Treatment with (L.) Less. leaf ethanol extract alleviates liver injury in multiple low-dose streptozotocin-induced diabetic BALB/c mice

Hyperglycemia-induced oxidative stress and inflammation are hallmarks of liver damage in diabetes mellitus. Accumulating evidence has demonstrated that Pluchea indica leaf ethanol extract (PILE) possesses strong antioxidant and anti-inflammatory properties. However, studies of its effects on liver damage in streptozotocin (STZ)-induced diabetic animals remain insufficient. To the best of our knowledge, the present study was the first to illustrate that PILE mitigated liver injury in STZ animals. Mice were first pretreated with PILE at either 50 mg/kg (PILE 50) or 100 mg/kg (PILE 100) 2 weeks prior to the induction of hyperglycemia by multiple low doses of STZ. The mice were then fed with PILE 50 or PILE 100 for 4 or 8 weeks, following which liver weight, pathological changes, oxidative stress parameters, inflammation-related markers and caspase-mediated apoptosis were measured at each time point. Untreated STZ mice exhibited abnormal increases in liver weight and severe pathological changes. However, PILE 100 reduced the severity of the STZ-induced diabetic phenotype at both time points. A significant decrease in the levels of superoxide dismutase and catalase, in addition to an increase in malondialdehyde, were observed in the livers of untreated STZ mice, all of which were significantly reversed by treatment with PILE 100 for 8 weeks. Western blot analysis revealed reduced levels of liver inflammatory markers, including interleukin-6, tumor necrosis factor-α, NF-κB p65, transforming growth factor-β1 and protein kinase C following PILE 100 treatment. Additionally, changes in the levels of apoptotic markers indicated that PILE 100 significantly attenuated caspase-9 and -3 expression, whilst preserving that of the Bcl-2 protein. In conclusion, the present study revealed that PILE alleviates hyperglycemia-induced liver injury by normalizing the various mediators of oxidative stress, inflammation and apoptosis.

Indel marker analysis of putative stress-related genes reveals genetic diversity and differentiation of rice landraces in peninsular Thailand

Genetic assessment of rice landraces is important for germplasm evaluation and genetic resource utilization. Rice landraces in peninsular Thailand have adapted to unique environmental stresses over time and have great significance as a genetic resource for crop improvement. In this study, rice landraces derived from rice research centers and farmers from different areas of peninsular Thailand were genetically assessed using 16 polymorphic InDel markers from putative stress-related genes. A total of 36 alleles were obtained. The average PIC value was 0.27/marker. The F_ST varied from 0.46 to 1.00. Genetic diversity was observed both within and between populations. AMOVA indicated that genetic variations occurred mainly between populations (70%) rather than within populations (30%). The dendrogram, population structure, and PCoA scatter plot clearly demonstrated the differentiation of the two major groups, i.e., landraces from upland and lowland rice ecosystems. The unique alleles of Indel1922, -2543, -6746, -7447 and -8538, which lie in genes encoding putative WAX2, heavy metal-associated domain-containing protein, GA20ox2, PTF1, and PLETHORA2, respectively, were only found in rice from upland ecosystems. Putative WAX2, GA20ox2, and PLETHORA2 are likely related to drought and salt stress. Our findings demonstrate the diversity of landraces in peninsular Thailand. The preservation of these landraces should be facilitated with effective markers to maintain all variant alleles and to protect the genetic diversity. Indel1922, -2543, -6746, -7447 and -8538 have the potential to differentiate upland rice from lowland rice. Furthermore, Indel1922, -6746 and -8538 might be effective markers for drought and salt tolerance.

Penaeus monodon GILT enzyme restricts WSSV infectivity by reducing disulfide bonds in WSSV proteins

Gamma-interferon-inducible lysosomal thiol reductase (GILT) is involved in the adaptive immune response via its effects on major histocompatibility complex (MHC)-restricted antigen presentation. In addition to antigen presentation, GILT exerts its antiviral activity by reducing disulfide bonds in proteins involved in viral infection and assembly, thereby inhibiting viral envelope-mediated infection and viral progeny production. In black tiger shrimp, Penaeus monodon GILT (PmGILT) was cloned and characterized, and found to be involved in the shrimp innate immune response and to exert neutralizing activity against white spot syndrome virus (WSSV) infection. However, the anti-WSSV mechanism of PmGILT in the shrimp innate immune response has not been defined. To explore the anti-WSSV activity of PmGILT, a yeast 2-hybrid (Y2H) assay was performed to identify WSSV proteins targeted by PmGILT. The assay revealed 4 potential PmGILT-interacting WSSV proteins: WSSV002, WSSV164, WSSV189, and WSSV471. Three of these 4 WSSV proteins (WSSV002, WSSV164 and WSSV189) were successfully produced and confirmed to interact with PmGILT in in vitro pull-down assays. WSSV189 and WSSV471 were previously identified as structural proteins, whereas WSSV164 is an immediate-early protein which has anti-melanization activity, and WSSV002 is an unknown. Because of the thiol reductase activity of PmGILT, WSSV164 and WSSV189, both of which are cysteine-containing WSSV proteins, were chosen for disulfide bond reduction assays. PmGILT reduced intrachain disulfide bonds in both WSSV proteins, suggesting that PmGILT exerts its anti-WSSV activity via its thiol reductase activity to disrupt the WSSV protein complex and restore the melanization activity of PmproPO1 and PmproPO2.

Phosphoproteome Profiling of Isogenic Cancer Cell-Derived Exosome Reveals HSP90 as a Potential Marker for Human Cholangiocarcinoma

The northeastern region of Thailand is well known to have a high incidence and mortality of cholangiocarcinoma (CCA). Protein phosphorylation status has been reported to reflect a key determinant of cellular physiology, but identification of phosphoproteins can be a problem due to the presence of phosphatase. Exosomes are stable toward circulating proteases and other enzymes in human blood and can be recognized before the onset of cancer progression. Here an in vitro metastatic model of isogenic CCA cells is used to provide insight into the phosphorylation levels of exosomal proteins derived from highly invasive cells. Gel-based and gel-free proteomics approaches are used to reveal the proteins differentially phosphorylated in relation to tumor cell phenotypes. Forty-three phosphoproteins are identified with a significant change in phosphorylation level. Phos-tag western blotting and immunohistochemistry staining are then employed to validate the candidate phosphoproteins. Heat shock protein 90 is successfully confirmed as being differentially phosphorylated in relation to tumor malignancy. Importantly, the aberrant phosphorylation of exosomal proteins might serve as a promising tool for the development of a biomarker for metastatic CCA.

Tolerance Mechanisms to Copper and Zinc Excess in Rhizophora mucronata Lam. Seedlings Involve Cell Wall Sequestration and Limited Translocation

Rhizophora mucronata is a common mangrove growing in habitats subjected to heavy metal (HM) contamination. Understanding their physiological responses to copper (Cu) and zinc (Zn) excess and underlying tolerance mechanisms is crucial to assess impacts of metal pollution on mangrove community. Seedlings were treated with Cu or Zn (0, 50 or 100 mg per plant) by means of a single addition. At day 3 and 7, Cu and Zn accumulation, photosynthetic efficiency, superoxide dismutase and peroxidase activity, non-protein thiols, reactive oxygen species and lipid peroxidation in roots and leaves were measured. R. mucronata restricted Cu and Zn translocation, thus accumulated HM mainly in roots while kept the leaves unaffected. However, high root HM did not induce oxidative stress nor anti-oxidative defense as HM were largely deposited in cell wall. We concluded that HM tolerance strategies of R. mucronata seedlings are exclusion and restriction of translocation to the vital photosynthetic tissue.

Ethanolic extracts of Pluchea indica (L.) leaf pretreatment attenuates cytokine-induced β-cell apoptosis in multiple low-dose streptozotocin-induced diabetic mice

Loss of β-cell mass and function is a fundamental feature of pathogenesis for type 1 and type 2 diabetes. Increasing evidence indicates that apoptosis is one of the main mechanisms of β-cell death in both types. Ethanolic extracts of Pluchea indica leaf (PILE) have been reported to possess blood glucose lowering actions in vivo. Nevertheless, further study is required to determine the underlying mechanisms. In this report, we have investigated the preventive effects of PILE on multiple low doses of streptozotocin (MLDS)-induced β-cell apoptosis. Mice were pre-treated with PILE at 50 mg/kg (PILE 50) or 100 mg/kg (PILE 100) for 2 weeks before streptozotocin (STZ) stimulation, and the treatment continued for 4 or 8 weeks. Results revealed that PILE 100 mice exhibited improved blood biochemistry, maintained a higher body weight, had decreased hyperglycemia, and restored islet architectures compared to non-treated STZ mice. Significantly, PILE 100 decreased levels of inflammatory response markers interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interlukin1-β (IL-1β), concomitant with the inhibition of caspase-3, caspase-8, capsepase-9, phosphorylation of signal transducer and activator of transcription 1 (pSTAT1), nuclear factor-κBp65 (NF-κBp65), and inducible nitric oxide synthase (iNOS). Additionally, survival and proliferative ability of β-cells was mediated by up-regulated Bcl-2 and Ki67, respectively. These results provide strong evidence that pretreatment with PILE 100 effectively attenuated STZ-induced diabetes-related symptoms and these effects could be associated with the inhibition of cytokine-induced β-cell apoptosis.

Fly-ash as a low-cost material for isolation of phosphoproteins

Metal oxide affinity chromatography (MOAC) is one of the most commonly used techniques for selective isolation phosphoproteins and phosphopeptides. This technique is capable of capturing the phosphorylated biomolecules through the affinity of the phosphoryl group for metal oxides/hydroxides. Fly-ash (FA), a by-product of coal-combustion power plants, is primarily composed of oxides of silicon and metals, among which iron and titanium. A number of studies have demonstrated the potential of these metal oxides for phosphoprotein and phosphopeptide enrichment. FA is annually produced over hundred million tons worldwide and generally considered as hazardous waste. It is thus of great importance to enhance its utilization. Here we present the first demonstration of the utility of FA as a low-cost MOAC material for the enrichment of phosphoproteins. With an FA-microcolumn, phosphoproteins can be successfully sequestered from other proteins. FA-microcolumns are shown to be simple, cheap and selective devices for phosphoprotein enrichment from a small volume of mixtures.

β-Elimination coupled with strong cation-exchange chromatography for phosphopeptide analysis

RATIONALE

Since the last decade, mass spectrometry (MS) has become an essential technique for phosphoprotein analysis. Formidable analytical challenges of MS for phosphoprotein study are both the low abundance of phosphopeptides and the lack of an unambiguous diagnostic fragment ion for identification of phospho residues. These challenges can be met by a charge-based isolation of β-elimination products after tryptic digestion using diagonal strong cation-exchange chromatography.

METHODS

β-Elimination combined with diagonal strong cation-exchange chromatography (BE/2SCX) was used for the enrichment of phosphorylated peptides prior to a mass spectrometric analysis by liquid chromatography/ion trap tandem mass spectrometry (MS/MS). Bovine α-casein (≥70% purity) was used as a model protein.

RESULTS

Conditions for β-elimination were optimized to maximize the efficiency of the reaction. With a β-elimination, all four model phosphopeptides from enolase (yeast) were correctly identified. The application of the BE/2SCX enrichment strategy for the analysis of β-elimination products of α-casein (bovine) allowed the identification of 11 phosphorylated products.

CONCLUSIONS

The introduction of a BE/2SCX-based enrichment step prior to LC/MS/MS analysis of β-elimination products facilitates the identification of phosphopeptides. Copyright © 2016 John Wiley & Sons, Ltd.

Elevation of serum fortilin levels is specific for apoptosis and signifies cell death in vivo

Background

Billions of cells undergo apoptosis each day in the average normal adult. The ability to readily assess the degree of apoptosis in human diseases is hampered by the lack of sensitive and specific serum biomarkers of apoptosis. Fortilin is a novel prosurvival molecule that protects cells against various noxious stimuli. While fortilin is secreted into the extracellular space under certain conditions, the relationship between the serum concentration of fortilin and the presence and extent of apoptosis in vivo remains unknown.

Methods & results

Using a newly developed fortilin ELISA system, we show here that fortilin exists in the normal human and mouse circulation. We further demonstrate that fortilin serum levels are significantly elevated in patients with solid cancer, in response to anti-cancer chemo- or radiation therapy. The elevation of fortilin serum levels is more robust and sensitive than that of such previously-reported serum biomarkers of apoptosis as fragmented cytokeratin-18, cytochrome c, and nucleosomal DNA. In addition, targeted apoptotic liver damage induced by Jo2 anti-Fas (CD95) antibody consistently and significantly increased serum fortilin levels in C57BL/6J mice. Finally, when challenged by anti-human-Fas IgM antibody, Jurkat leukemic T cells apoptosed and released fortilin into the medium before plasma membrane integrity was compromised.

Conclusions

Taken together, these data suggest that serum fortilin levels reflect the degree and extent of apoptosis occurring in vivo.

General significance

Fortilin is a viable serum biomarker of in vivo apoptosis and can be utilized to noninvasively assess the status of in vivo apoptosis in humans.

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Ultra-sensitive fortilin ELISA has been developed. Fortilin circulates in blood.

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Fortilin serum levels become highly elevated after apoptosis-inducing therapy.

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Fortilin is more robust and sensitive than other serum apoptosis markers.

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Fortilin is actively secreted before plasma membrane becomes disrupted.

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Fortilin is an excellent serum biomarker of in vivo apoptosis.

Southeast Asian mouth-brooding Betta fighting fish (Teleostei: Perciformes) species and their phylogenetic relationships based on mitochondrial COI and nuclear ITS1 DNA sequences and analyses

Fighting fish species in the genus Betta are found in several Southeast Asian countries. Depending on the mode of paternal care for fertilized eggs and hatchlings, various species of the betta fish are classified as mouth brooders or nest builders whose members in turn have been grouped according to their similarities mainly in morphology. The mouth brooders as well as some nest builders involved in the present study include fishes discovered and identified subsequent to previous reports on species groupings and their positions on phylogenetic trees based on DNA sequences that differ from those used by us in this study. From the mitochondrial COI gene and nuclear ITS1 gene sequences and more accurate analyses we conclude that the following members of the mouth-brooding pairs, named differently previously, are virtually identical, viz the Betta prima-Betta pallida pair and Betta ferox-Betta apollon pair. The Betta simplex, hitherto believed to be one species, could possibly be genetically split into 2 distinct species. In addition, several other established type-locality fishes could harbor cryptic species as judged by genetic differences. Assignments of fish species to groups reported earlier may have to be altered somewhat by the present genetic findings. We propose here a new Betta fish phylogenetic tree which, albeit being similar to the previous ones, is clearly different from them. Our gene-based evidence also leads to assignments of some fishes to new species groups and alters the positions of some species on the new phylogenetic tree, thus implying different ancestral relationships.

Identification of gamma-interferon-inducible lysosomal thiol reductase (GILT) homologues in the fruit fly Drosophila melanogaster

Gamma-interferon-inducible lysosomal thiol reductase (GILT) has been demonstrated to be involved in the immune response to bacterial challenge in various organisms. However, little is known about GILT function in innate immunity. Drosophila has been commonly used as a model for the study of the innate immune response of invertebrates. Here, we identify the CG9796, CG10157, and CG13822 genes of fruit fly Drosophila melanogaster as GILT homologues. All deduced Drosophila GILT coding sequences contained the major characteristic features of the GILT protein family: the GILT signature CQHGX2ECX2NX4C sequence and the active site CXXC or CXXS motif. The mRNA transcript levels of the Drosophila GILT genes were up-regulated after Gram-negative bacteria Escherichia coli DH5α infection. Moreover, a bacterial load assay showed that over-expression of Drosophila GILT in fat body or hemocytes led to a low bacterial colony number whereas knock-down of Drosophila GILT in fat body or hemocytes led to a high bacterial colony number when compared to a wild-type control. These results indicate that the Drosophila GILTs are very likely to play a role in the innate immune response upon bacterial challenge of Drosophila host defense. This study may provide the basis for further study on GILT function in innate immunity.

Two new anti-apoptotic proteins of white spot syndrome virus that bind to an effector caspase (PmCasp) of the giant tiger shrimp Penaeus (Penaeus) monodon

White spot syndrome virus proteins WSSV134 and WSSV322 have been shown to bind with the p20 domain (residues 55-214) of Penaeus monodon caspase (PmCasp) protein through yeast two-hybrid screening. Binding was confirmed for the p20 domain and the full-length caspase by co-immunoprecipitation. WSSV134 is also known as the WSSV structural protein VP36A, but no function or conserved domains have been ascribed to WSSV322. Discovery of the caspase binding activity of these two proteins led to an investigation of their possible anti-apoptotic roles. Full-length PmCasp was confirmed to be an effector caspase by inducing apoptosis in transfected Sf-9 cells as assessed by DAPI staining. Using the same cell model, comparison of cells co-transfected with PmCasp and either WSSV134 or WSSV322 revealed that both of the binding proteins had anti-apoptotic activity. However, using the same Sf-9 protocol with anti-apoptosis protein-1 (AAP-1; also called WSSV449) previously shown to bind and inactivate a different effector caspase from P. monodon (Pm caspase) did not block apoptosis induced by PmCasp. The results revealed diversity in effector caspases and their viral protein inhibitors in P. monodon.

Biodiversity of the Betta smaragdina (Teleostei: Perciformes) in the northeast region of Thailand as determined by mitochondrial COI and nuclear ITS1 gene sequences

In Thailand, there are currently five recognized species members of the bubble-nesting Betta genus, namely Betta splendens, B. smaragdina, B. imbellis, B. mahachaiensis and B. siamorientalis. In 2010, we indicated the possibility, based on COI barcoding evidence, that there might be two additional species, albeit cryptic, related to the type-locality B. smaragdina in some provinces in the northeast of Thailand. In the present study, after a more extensive survey of the northeast, and phylogenetic analyses based on COI and ITS1 sequences, the B. smaragdina group may be composed of at least 3 cryptic species members. The phylogenetic positions of these B. smaragdina group members in the bubble-nesting bettas' tree together with those of their congeners have been consolidated by better DNA sequence quality and phylogenetic analyses. With a better supported tree, the species statuses of B. siamorientalis and the Cambodian B. smaragdina-like fish, B. stiktos, are also confirmed.

Biosynthesis of 1,3-propanediol from recombinant E. coli by optimization process using pure and crude glycerol as a sole carbon source under two-phase fermentation system

The environmental and nutritional condition for 1,3-propanediol (1,3-PD) production by the novel recombinant E. coli BP41Y3 expressing fusion protein were first optimized using conventional approach. The optimum environmental conditions were: initial pH at 8.0, incubation at 37 °C without shaking and agitation. Among ten nutrient variables, fumarate, (NH₄)₂HPO₄ and peptone were selected to study on their interaction effect using the response surface methodology. The optimum medium contained modified Riesenberg medium (containing pure glycerol as a sole carbon source) supplemented with 63.65 mM fumarate, 3.80 g/L (NH₄)₂HPO₄ and 1.12 g/L peptone, giving the maximum 1,3-PD production of 2.43 g/L. This was 3.5-fold higher than the original medium (0.7 g/L). Two-phase cultivation system was conducted and the effect of pH control (at 6.5, 7.0 and 8.0) was investigated under anaerobic condition by comparing with the no pH control condition. The cultivation system without pH control (initial pH of 8.0) gave the maximum values of 1.65 g/L 1,3-PD, the 1,3-PD production rate of 0.13 g/L h and the yield of 0.31 mol 1,3-PD/mol crude glycerol. Hence, using crude glycerol as a sole carbon source resulted in 32 % lower 1,3-PD production from this recombinant strain that may be due to the presence of various impurities in the crude glycerol of biodiesel plant. In addition, succinic acid was found to be a major product during fermentation by giving the maximum concentration of 11.92 g/L after 24 h anaerobic cultivation.

β-thymosins and hemocyte homeostasis in a crustacean

Thymosin proteins are well known for their actin-binding activity. Thymosin beta 4 (Tβ4) has been associated with biological activities in tissue repair and cell migration via interaction with ATP-synthase in vertebrates, while the information of similar thymosin functions in invertebrates is limited. We have shown previously that ATP-synthase is present on the surface of crayfish hematopoietic tissue (HPT) cells, and that astakine 1 (Ast1, an invertebrate cytokine) was found to interact with this β-subunit of ATP synthase. Here, we identified five different β-thymosins from Pacifastacus leniusculus, designated Pl-β-thymosin1-5. The two dominant isoforms in brain, HPT and hemocytes, Pl-β-thymosin1 and 2, were chosen for functional studies. Both isoforms could bind to the β-subunit of ATP-synthase, and Pl-β-thymosin1, but not Pl-β-thymosin2, significantly increased extracellular ATP formation. Moreover, Pl-β-thymosin1 stimulated HPT cell migration in vitro and Ast1 blocked this effect. Pl-β-thymosin2 increased the circulating hemocyte number at an early stage after injection. Additionally, in vivo injection of Pl-β-thymosin1 resulted in significant reduction of reactive oxygen species (ROS) production in crayfish HPT whereas Pl-β-thymosin2 had a similar but transient effect. Both Pl-β-thymosins induced the expression of Ast1 and superoxide dismutase (SOD) transcripts, while silencing of endogenous Pl-β-thymosin 1 and 2 by RNAi resulted in significant reduction of the Ast1 and SOD transcripts. The diverse effects exhibited by Pl-β-thymosin1 and Pl-β-thymosin2 indicates that these proteins are involved in a complex interaction that regulates the hematopoietic stem cell proliferation and differentiation.

Astakine 2--the dark knight linking melatonin to circadian regulation in crustaceans

Daily, circadian rhythms influence essentially all living organisms and affect many physiological processes from sleep and nutrition to immunity. This ability to respond to environmental daily rhythms has been conserved along evolution, and it is found among species from bacteria to mammals. The hematopoietic process of the crayfish Pacifastacus leniusculus is under circadian control and is tightly regulated by astakines, a new family of cytokines sharing a prokineticin (PROK) domain. The expression of AST1 and AST2 are light-dependent, and this suggests an evolutionarily conserved function for PROK domain proteins in mediating circadian rhythms. Vertebrate PROKs are transmitters of circadian rhythms of the suprachiasmatic nucleus (SCN) in the brain of mammals, but the mechanism by which they function is unknown. Here we demonstrate that high AST2 expression is induced by melatonin in the brain. We identify RACK1 as a binding protein of AST2 and further provide evidence that a complex between AST2 and RACK1 functions as a negative-feedback regulator of the circadian clock. By DNA mobility shift assay, we showed that the AST2-RACK1 complex will interfere with the binding between BMAL1 and CLK and inhibit the E-box binding activity of the complex BMAL1-CLK. Finally, we demonstrate by gene knockdown that AST2 is necessary for melatonin-induced inhibition of the complex formation between BMAL1 and CLK during the dark period. In summary, we provide evidence that melatonin regulates AST2 expression and thereby affects the core clock of the crustacean brain. This process may be very important in all animals that have AST2 molecules, i.e. spiders, ticks, crustaceans, scorpions, several insect groups such as Hymenoptera, Hemiptera, and Blattodea, but not Diptera and Coleoptera. Our findings further reveal an ancient evolutionary role for the prokineticin superfamily protein that links melatonin to direct regulation of the core clock gene feedback loops.

Most living organisms are able to sense the time and in particular time of day by their internal clocks. So-called clock proteins control these internal clockworks. BMAL1 and CLK are two important clock proteins, which together form a complex that serves as a transcription factor and controls the production of diurnal proteins. These diurnal proteins, in turn, inhibit the formation of clock proteins so that the concentration of the different proteins in the cell oscillates back and forth throughout the day. External factors may affect the balance of clock proteins, and one such important factor is light. Melatonin is a darkness hormone produced in the brain of most animals during the night, and here we show that melatonin controls the formation of a protein named AST2 in crayfish. AST2 belongs to a group of proteins found in many arthropods, such as spiders, scorpions, crustaceans, and some insects, whose function has been unknown until now. Now we demonstrate that AST2 is induced by melatonin at night and then functions in the internal biological clock by preventing BMAL1 and CLK to form a complex. In this way, AST2 acts as a link between melatonin and the internal biological clock.

Characterization of a novel binding protein for Fortilin/TCTP--component of a defense mechanism against viral infection in Penaeus monodon

The Fortilin (also known as TCTP) in Penaeus monodon (PmFortilin) and Fortilin Binding Protein 1 (FBP1) have recently been shown to interact and to offer protection against the widespread White Spot Syndrome Virus infection. However, the mechanism is yet unknown. We investigated this interaction in detail by a number of in silico and in vitro analyses, including prediction of a binding site between PmFortilin/FBP1 and docking simulations. The basis of the modeling analyses was well-conserved PmFortilin orthologs, containing a Ca²⁺-binding domain at residues 76–110 representing a section of the helical domain, the translationally controlled tumor protein signature 1 and 2 (TCTP_1, TCTP_2) at residues 45–55 and 123–145, respectively. We found the pairs Cys59 and Cys76 formed a disulfide bond in the C-terminus of FBP1, which is a common structural feature in many exported proteins and the “x–G–K–K” pattern of the amidation site at the end of the C-terminus. This coincided with our previous work, where we found the “x–P–P–x” patterns of an antiviral peptide also to be located in the C-terminus of FBP1. The combined bioinformatics and in vitro results indicate that FBP1 is a transmembrane protein and FBP1 interact with N-terminal region of PmFortilin.

Isolation of the detoxification enzyme EgP450 from an oil palm EST library

CONTEXT

Sequencing of cDNA clones from plant tissue to generate expressed sequence tags (ESTs) is an effective tool for gene discovery. Together with powerful bioinformatics tools, EST sequences allow the prediction of functions of putative bioactive compounds that can later be confirmed.

OBJECTIVE

To isolate a detoxification enzyme from an EST library from the oil palm (Elaeis guineensis Jacq. Arecaceae).

METHODS

In total, 750 clones from an oil palm cDNA library were randomly sequenced and analyzed. A clone homologous to cytochrome P450 monooxygenases (P450) was selected from the list of highly expressed genes. The full-length cDNA of P450 from E. guineensis (EgP450) was generated and transformed into a bacterial host to produce recombinant protein. A 3D model of EgP450 was generated and used in a molecular docking analysis to screen for target herbicide substrates. Finally, the detoxification activity of EgP450 was confirmed by an herbicide tolerance test with rice seedlings.

RESULTS AND DISCUSSION

The full-length EgP450 has an open reading frame (ORF) of 1515 bp that encodes a protein of 505 amino acids. Docking analysis showed that EgP450 bound to phenylurea-like herbicides such as isoproturon, chlortoluron and fluometuron. The herbicide tolerance test demonstrated that the presence of EgP450 protected the rice seedlings from the killing action of the phytotoxic agent isoproturon.

CONCLUSIONS

The gene EgP450 was detected in the roots and stems of oil palm tissues, and its recombinant product was shown to protect rice seedlings from exogenous herbicides of the phenylurea family.

Identification and expression analysis of two splice variants of the 14-3-3 epsilon from Litopenaeus Vannamei during WSSV infections

The 14-3-3 epsilon (14-3-3ε) is a member of the 14-3-3-protein family claimed to play important roles in many biological processes. In this study, two alternative 14-3-3 epsilon mRNAs, designated as 14-3-3EL and 14-3-3ES were identified from the shrimp L. vannamei. The 14-3-3EL isoform contains an insertion of 48 nucleotides by intron retention in the pre-mRNA of 14-3-3ε. While the 14-3-3ES occurred after being fully spliced. Using the yeast two hybrid method, the pattern of dimer formation by the two alternative 14-3-3ε isoforms revealed that the shrimp 14-3-3ε formed both homodimers and heterodimers. Both 14-3-3ε transcript variants were constitutively expressed in all shrimp tissues tested but the level of the 14-3-3ES isoform was always lower. However, after white spot syndrome virus (WSSV) infection, the expression level of the two transcript variants changed. At 48 h after infection, expression of 14-3-3EL mRNA increased significantly in the gill and muscle tissue whereas the expression 14-3-3ES increased only in muscle. It was of interest that in the lymphoid organ, there was a significant down-expression of both transcript variants. From these results we suggest that 14-3-3EL and 14-3-3ES might be related to different cellular processes that are modulated during virus infection.

Stimulating the immune response of Litopenaeus vannamei using the phagocytosis activating protein (PAP) gene

High mortality in the shrimp farming industry is caused by several pathogens such as white spot syndrome virus (WSSV), yellow head virus (YHV) and Vibrio harveyi (V. harveyi). A PAP (Phagocytosis activating protein) gene able to activate phagocytosis of shrimp hemocytes was cloned into the eukaryotic expression vector phMGFP. In vitro expression was confirmed by transfection of PAP-phMGFP into CHO (Chinese Hamster Ovary) cells and the expression of the Green Fluorescent Protein (GFP) was observed. In order to activate the phagocytic activity of shrimp, 20, 40 and 80 μg/shrimp of this PAP-phMGFP vector were injected into Litopenaeus vannamei muscle. After challenged with WSSV, 40 μg/shrimp produced the highest relative percent survival (77.78 RPS). Analysis for the expression of the GFP gene in various tissues showed the expression mostly in the hemolymph of the immunized shrimp. The expression level of PAP and proPO (Prophenoloxidase) gene were highest at 7 days after immunization. This agreed with the efficiency of protection against WSSV that also occurred 7 days after immunization with the highest RPS of 86.61%. However there was no protection 30 days after immunization. Hemocytes of shrimp injected with PAP-phMGFP had 1.9 folds and 3 folds higher percentage phagocytosis and phagocytic index than the shrimp injected with PBS. Accordingly, copies of WSSV reduced in the PAP-phMGFP injected shrimp. In addition, PAP-phMGFP also protected shrimp against several pathogens: WSSV, YHV and V. harveyi, with RPS values of 86.61%, 63.34% and 50% respectively. This finding shows that the immune cellular defense mechanisms in shrimp against pathogens can be activated by injection of PAP-phMGFP and could indicate possible useful ways to begin to control this process.

Shrimp laminin receptor binds with capsid proteins of two additional shrimp RNA viruses YHV and IMNV

Laminin receptor (Lamr) in shrimp was previously proposed to be a potential receptor protein for Taura syndrome virus (TSV) based on yeast two-hybrid assays. Since shrimp Lamr bound to the VP1 capsid protein of TSV, we were interested to know whether capsid/envelope proteins from other shrimp viruses would also bind to Lamr. Thus, capsid/envelope encoding genes from 5 additional shrimp viruses were examined. These were Penaeus stylirostris densovirus (PstDNV), white spot syndrome virus (WSSV), infectious myonecrosis virus (IMNV), Macrobrachium rosenbergii nodavirus (MrNV), and yellow head virus (YHV). Protein interaction analysis using yeast two-hybrid assay revealed that Lamr specifically interacted with capsid/envelope proteins of RNA viruses IMNV and YHV but not MrNV and not with the capsid/envelope proteins of DNA viruses PstDNV and WSSV. In vitro pull-down assay also confirmed the interaction between Lamr and YHV gp116 envelope protein, and injection of recombinant Lamr (rLamr) protein produced in yeast cells protected shrimp against YHV in laboratory challenge tests.

Shrimp Pm-fortilin inhibits the expression of early and late genes of white spot syndrome virus (WSSV) in an insect cell model

Fortilin plays an important role in anti-apoptotic mechanisms and cell proliferation in many eukaryotic organisms. This work confirmed previous reports that Sf9 can support the replication of white spot syndrome virus (WSSV) genomic material by using immunohistochemistry with a specific antibody to detect the immediate early gene 1 (ie1) and by amplification of WSSV DNA and mRNA products. Using this insect-cell model system, we show that overexpression of Pm-fortilin in Sf9 cells inhibited the expression of WSSV early genes and late genes (WSSV-DNA polymerase, VP15 and VP28) but not an immediate early gene ie1. This is the first time that an insect cell line has been used to demonstrate interaction between a shrimp gene and genes of a shrimp virus.

Receptor for Activated C Kinase-1 protein from Penaeus monodon (Pm-RACK1) participates in the shrimp antioxidant response

Cellular oxidative stress responses are caused in many ways, but especially by disease and environmental stress. After the initial burst of reactive oxygen species (ROS), the effective elimination of ROS is crucial for the survival of organisms and is mediated by antioxidant defense mechanisms. In this paper, we investigate the possible antioxidant function of Penaeus monodon Receptor for Activated C Kinase-1 (Pm-RACK1). When Pm-RACK1 was over-expressed in Escherichia coli cells or Spodoptera frugiperda (Sf9) insect cells exposed to H(2)O(2), it significantly protected the cells from oxidative damage induced by H(2)O(2). When recombinant Pm-RACK1 protein was expressed as a histidine fusion protein in E. coli and purified with a Ni(2+)-column it possessed antioxidant functions that protected DNA from metal-catalyzed oxidation. Shrimp (Penaeus vannamei) held at an alkaline pH had a much higher hepatopancreatic expression of Pm-RACK1 than in those held at pH 7.4. The exposure of shrimp to alkaline pH is also known to increase ROS production. These results provide strong evidence that Pm-RACK1 can participate in the shrimp antioxidant response induced by the formation of ROS.

WSSV: VP26 binding protein and its biological activity

White spot syndrome virus (WSSV) is one of the major causes of disease in the shrimp culture industry causing enormous economic losses. In this study, we displayed peptides from a cDNA library obtained from the hemolymph of shrimp infected with WSSV, on the surface of phage and screened for the peptides that interacted with the WSSV. One WSSV binding protein (WBP) gene was found to consist of 171 bp that had no matches in the NCBI database. This WBP was shown to bind to the VP26 protein of the WSSV by Western blotting. In addition, WBP reduced the binding of WSSV to shrimp haemocytes from 2.0 × 10(7)copies in the control to 6.0 × 10(2) after treatment with 80 μg of WBP. The survival rate of shrimp after WSSV were mixed with WBP at 80 μg, was 89% and the binding of WBP remained unchanged for at least 24h. Therefore, the results indicate that the WBP can bind to VP26 and inhibit the invasion of WSSV into host cells. This finding may introduce another future way to try to fight this disease in shrimp culture.

Cloning and characterization of pectate lyase from Hevea brasiliensis

Latex from the commercial Hevea brasiliensis contains 30-50% (w/w) of natural rubber (cis-1,4-polyisoprene), the raw material for the many products of the rubber industry. We have constructed a cDNA library from the latex of H. brasiliensis to investigate the expressed genes and molecular events in the latex. We have isolated two cDNAs from this library, Hb-PEL-1 and Hb-PEL-2 that could encode for pectate lyase enzymes (EC4.2.2.2). From their sequence analysis Hb-PEL-1 and Hb-PEL-2 encode for proteins of 393 and 323 amino acids, respectively. Comparison of these deduced amino acid sequences with other pectate lyase enzymes showed they contained the conserved NADPH, Ca(2+) and substrate binding sites and had a 74% identity to Arabidopsis thaliana pectate lyase. Only the Hb-PEL-1 recombinant protein expressed from Escherichia coli had enzymic activity which was Ca(2+) dependent. Interestingly, Hb-PEL-1 contained an extra internal peptide between amino acid residue 38-108 when compared to Hb-PEL-2 and this peptide was also present in other pectate lyase enzymes. The transcript of pectate lyase (Hb-PEL) in the latex of rubber tree at various times after the first tapping was quantified by real-time PCR using 18s genes as internal standard. Most transcripts were detected on the first day after tapping and then decreased with time. This indicates that the pectate lyase may be involved in either the release of latex by breaking down the laticifer wall or in the development of laticifers.

Identification of a receptor for activated protein kinase C1 (Pm-RACK1), a cellular gene product from black tiger shrimp (Penaeus monodon) interacts with a protein, VP9 from the white spot syndrome virus

A gene encoding a receptor for activated protein kinase C1 homolog has been isolated from the shrimp, Penaeus monodon (Pm-RACK1). The full length Pm-RACK1 cDNA has 957 bp, and an open reading frame encoding a protein of 318 amino acid residues. The protein contains seven WD40 repeats and shares approximately 78% identity with vertebrate RACK1. In adult shrimp, Pm-RACK1 transcripts were detected in all tissues. During WSSV infection, Pm-RACK1 was upregulated in hepatopancreas, stomach and hemocytes. We identified Pm-RACK1 as a specific cellular target protein for VP9, a nonstructural protein of WSSV. The interaction of these two proteins may be involved in mediating intracellular VP9 functions.

Identifications of SUMO-1 cDNA and its expression patterns in Pacific white shrimp Litopeanaeus vannamei

Small ubiquitin-like modifiers (SUMO) work in a similar way as ubiquitin to alter the biological properties of a target protein by conjugation. A shrimp SUMO cDNA named LvSUMO-1 was identified in Litopenaeus vannamei. LvSUMO-1 cDNA contains a coding sequence of 282 nucleotides with untranslated regions of 37 bp at 5'-end and 347 bp at 3'-end, respectively. The deduced 93 amino acids exhibit 83% identity with the Western Honeybee SUMO-1, and more than 65% homologies with human and mouse SUMO-1. LvSUMO-1 mRNA is expressed in most L. vannamei tissues with the highest level in hepatopancrease. The mRNA expression of LvSUMO-1 over development stages in L. Vammamei is distinguished by a low level in nauplius stage and relatively high level in postlarva stage with continuous expression until juvenile stage. The LvSUMO-1 protein and its conjugated proteins are detected in both cytoplasm and nucleus in several tissues. Interestingly, LvSUMO-1 mRNA levels are high in abdominal muscle during the premolt stage, wherein it has significant activities of protein degradation, suggesting its possible role in the regulation of shrimp muscle protein degradation.

Embryonic lethality of fortilin-null mutant mice by BMP-pathway overactivation

BACKGROUND

Fortilin negatively regulates apoptosis and is overexpressed in cancer. However, the role of fortilin in mammalian development is not clear.

METHODS AND RESULTS

In order to evaluate the physiological role of fortilin in vivo, we performed a targeted disruption of the fortilin gene in mice. Fortilin(+/-) mice have the ability to survive and exhibit normal growth, while fortilin(-/-) mice are embryonically lethal around the 3.5 days post-coital (dpc). Cultured blastocysts from fortilin(+/-) embryos undergo normal outgrowth to produce inner cell mass (ICM) and trophoblasts (TB), while ICM of fortilin(-/-) embryos either fails to outgrow or prematurely disintegrates. Mouse embryonic fibroblasts (MEF) derived from fortilin(+/-) embryos are more susceptible to noxious stimuli than are wild type embryos. It has been consistently shown in Xenopus embryos that the depletion of fortilin's message severely compromises the formation of neural tissue, even in the brain, while overexpression of fortilin induces the partial double body axis in embryos and is capable of blocking BMP4-induced transcription of Vent1, Vent2, and Msx1 genes. This suggests that fortilin is an inhibitor of the BMP pathway. Strikingly, when fortilin levels are reduced by siRNA, BMP4 causes MEF to undergo extensive DNA-fragmentation, while DNA fragmentation is minimal in the presence of fortilin. In addition, BMP4 induces more Msx2 in the absence of fortilin than in its presence. Furthermore, Msx2 overexpression causes MEF to undergo apoptotic cell death.

CONCLUSION

We conclude that in early phase of development, fortilin functions as an inhibitor of the BMP pathway. The presence of fortilin in the very early stages of development is required for the survival of embryos.

GENERAL SIGNIFICANCE

Abnormalities in the fortilin gene may be associated with early pregnancy loss.

The role of Pm-fortilin in protecting shrimp from white spot syndrome virus (WSSV) infection

Crustacean fortilin or the product of the translationally controlled tumor protein (TCTP) gene isolated from Penaeus monodon, is well conserved and has a Ca(++) binding domain. Pm-fortilin has anti-apoptotic properties and is present at high levels during the onset of viral infections in P. monodon. The possibility of using rFortilin to protect against white spot syndrome virus (WSSV) infection was tested. Injection of shrimp with rFortilin, after infection with WSSV, resulted in 80-100% survival and detection of very low levels of WSSV by PCR, whereas in moribund samples WSSV levels were very high. This result implies that injection of recombinant rFortilin decreases viral infection by an unknown mechanism, but probably by inhibiting viral replication. Using a yeast two-hybrid screen for cellular protein partners to rFortilin we identified an unknown protein that bound to fortilin. This is a novel polypeptide of 93 amino acids with a number of XPPX signature sequences that are often reported to have a function in antiviral peptides.

Morelloflavone blocks injury-induced neointimal formation by inhibiting vascular smooth muscle cell migration

BACKGROUND

In-stent restenosis, or renarrowing within a coronary stent, is the most ominous complication of percutaneous coronary intervention, caused by vascular smooth muscle cell (VSMC) migration into and proliferation in the intima. Although drug-eluting stents reduce restenosis, they delay the tissue healing of the injured arteries. No promising alternative anti-restenosis treatments are currently on the horizon.

METHODS

In endothelium-denudated mouse carotid arteries, oral morelloflavone-an active ingredient of the Thai medicinal plant Garcinia dulcis-significantly decreased the degree of neointimal hyperplasia, without affecting neointimal cell cycle progression or apoptosis as evaluated by Ki-67 and TUNEL staining, respectively. At the cellular level, morelloflavone robustly inhibited VSMC migration as shown by both scratch wound and invasion assays. In addition, morelloflavone prevented VSMCs from forming lamellipodia, a VSMC migration apparatus. Mechanistically, the inhibition by morelloflavone of VSMC migration was through its negative regulatory effects on several migration-related kinases, including FAK, Src, ERK, and RhoA. Consistently with the animal data, morelloflavone did not affect VSMC cell cycle progression or induce apoptosis.

RESULTS

These data suggest that morelloflavone blocks injury-induced neointimal hyperplasia via the inhibition of VSMC migration, without inducing apoptosis or cell cycle arrest.

GENERAL SIGNIFICANCE

We propose morelloflavone to be a viable oral agent for the prevention of restenosis, without compromising effects on the integrity and healing of the injured arteries.

Fortilin binds Ca2+ and blocks Ca2+-dependent apoptosis in vivo

Fortilin, a 172-amino-acid polypeptide present both in the cytosol and nucleus, possesses potent anti-apoptotic activity. Although fortilin is known to bind Ca2+, the biochemistry and biological significance of such an interaction remains unknown. In the present study we report that fortilin must bind Ca2+ in order to protect cells against Ca2+-dependent apoptosis. Using a standard Ca2+-overlay assay, we first validated that full-length fortilin binds Ca2+ and showed that the N-terminus (amino acids 1-72) is required for its Ca2+-binding. We then used flow dialysis and CD spectropolarimetry assays to demonstrate that fortilin binds Ca2+ with a dissociation constant (Kd) of approx. 10 mM and that the binding of fortilin to Ca2+ induces a significant change in the secondary structure of fortilin. In order to evaluate the impact of the binding of fortilin to Ca2+ in vivo, we measured intracellular Ca2+ levels upon thapsigargin challenge and found that the lack of fortilin in the cell results in the exaggerated elevation of intracellular Ca2+ in the cell. We then tested various point mutants of fortilin for their Ca2+ binding and identified fortilin(E58A/E60A) to be a double-point mutant of fortilin lacking the ability of Ca2+-binding. We then found that wild-type fortilin, but not fortilin(E58A/E60A), protected cells against thapsigargin-induced apoptosis, suggesting that the binding of fortilin to Ca2+ is required for fortilin to protect cells against Ca2+-dependent apoptosis. Together, these results suggest that fortilin is an intracellular Ca2+ scavenger, protecting cells against Ca2+-dependent apoptosis by binding and sequestering Ca2+ from the downstream Ca2+-dependent apoptotic pathways.

Automatic synchronization and distribution of biological databases and software over low-bandwidth networks among developing countries

Bioinformatics involves the collection, organization and analysis of large amounts of biological data, using networks of computers and databases. Developing countries in the Asia-Pacific region are just moving into this new field of information-based biotechnology. However, the computational infrastructure and network bandwidths available in these countries are still at a basic level compared to that in developed countries. In this study, we assessed the utility of a BitTorrent-based Peer-to-Peer (btP2P) file distribution model for automatic synchronization and distribution of large amounts of biological data among developing countries. The initial country-level nodes in the Asia-Pacific region comprised Thailand, Korea and Singapore. The results showed a significant improvement in download performance using btP2P--three times faster overall download performance than conventional File Transfer Protocol (FTP). This study demonstrated the reliability of btP2P in the dissemination of continuously growing multi-gigabyte biological databases across the three Asia-Pacific countries. The download performance for btP2P can be further improved by including more nodes from other countries into the network. This suggests that the btP2P technology is appropriate for automatic synchronization and distribution of biological databases and software over low-bandwidth networks among developing countries in the Asia-Pacific region.

AVAILABILITY

http://everest.bic.nus.edu.sg/p2p/

Cloning and characterization of a caspase gene from black tiger shrimp (Penaeus monodon)-infected with white spot syndrome virus (WSSV)

A black tiger shrimp (Penaeus monodon) caspase cDNA homologue (PmCasp) has been identified from a hemocyte library using a previously identified caspase homologue from the banana shrimp (Penaeus merguiensis) as a probe. The full-length PmCasp was 1202bp with a 954bp open reading frame, encoding 317 amino acids. The deduced protein contained a potential active site (QACRG pentapeptide) conserved in most caspases. It had 83% identity with caspase of P. merguiensis and 30% identity with drICE protein of Drosophila melanogaster, and it exhibited caspase-3 activity in vitro. PmCasp was cloned and expressed in Escherichia coli and a rabbit polyclonal antiserum was produced. In Western blots, the antiserum reacted with purified recombinant PmCasp and with lysates of E. coli containing the expressed plasmid. In crude protein extracts from normal shrimp, the antiserum reacted with 36 and 26kDa bands likely to correspond to inactive pro-caspase and its proteolytic intermediate form, respectively. PmCasp expression was measured in normal shrimp and in white spot syndrome virus (WSSV)-infected shrimp at 24 and 48h post-injection (p.i.) by semi-quantitative RT-PCR, Western blot analysis, and immunohistochemistry. Semi-quantitative RT-PCR analysis revealed up-regulation of PmCasp at 48h p.i. and expression remained high up to the moribund state. These results were supported by Western blot analysis showing increased PmCasp protein levels at 24 and 48h p.i. when compared to normal control shrimp. Immunohistochemical analysis of gills from the WSSV-infected shrimp revealed immunoreactivity localized in the cytoplasm of both normal and apparently apoptotic cells. In summary, a caspase-3 like gene is conserved in P. monodon and is up-regulated after WSSV infection.

Binding of shrimp cellular proteins to Taura syndrome viral capsid proteins VP1, VP2 and VP3

Viruses are a major cause of production losses in the world shrimp-farming industry. Despite this, little is known about viral-host interactions in shrimp due in part to the lack of continuous shrimp cell lines. Here, the yeast two-hybrid assay system was employed to study interactions between three Taura syndrome viral capsid proteins (VP1-VP3) and proteins from a cDNA library of the black tiger shrimp Penaeus monodon. VP1 interacted with beta-actin, elongation factor 1alpha (EF1alpha), lysozyme (Lys) and laminin receptor/ribosomal protein p40 (Lamr/p40) containing a putative palindromic laminin binding region LMWWML. VP2 interacted with beta-actin and EF1alpha, while VP3 bound to the same proteins as VP1 except for Lamr/p40. In vitro pull-down assays confirmed these interactions. The most interesting interaction was specific binding between VP1 and Lamr/p40 since Lamr/p40 has been identified as the mammalian cell receptor for several arthropod-borne viruses (arboviruses). A search of mosquito vector and Drosophila sequences at available databases revealed the presence of putative Lamr/p40 proteins with high homology to the Lamr/p40 from shrimp.

Penaeus monodon gene discovery project: the generation of an EST collection and establishment of a database

A large-scale expressed sequence tag (EST) sequencing project was undertaken for the purpose of gene discovery in the black tiger shrimp Penaeus monodon. Initially, 15 cDNA libraries were constructed from different tissues (eyestalk, hepatopancrease, haematopoietic tissue, haemocyte, lymphoid organ, and ovary) of shrimp, reared under normal or stress conditions, to identify tissue-specific genes and genes responding to infection and heat stress. A total of 10,100 clones were analyzed by single-pass sequencing from the 5' end. Clustering and assembling of these ESTs resulted in a total of 4845 unique sequences with 917 overlapping contigs and 3928 singletons. The redundancy of each cDNA library ranged from 13.4% to 61.3% with an overall redundancy of 61.1%. About half of these ESTs (2365 clones, 48.8%) showed significant homology (BLASTX, e-values <10(-4)) to known genes. A high proportion of P. monodon ESTs was most similar to the predicted protein sequences from various organisms, e.g. Homo sapiens (9%), Mus musculus (7%), Drosophila (6%), Gallus sp.(6%), and Anopheles (5%). Only 6% showed the highest similarity to other known genes from shrimp due to the limited sequence entries of the species in the public database. Several tissue-specific transcripts were identified as well as the candidate genes that may be implicated in the immune response. In addition, bioinformatic mining of microsatellites from the P. monodon ESTs identified 997 unique microsatellite containing ESTs in which 74 loci resided within the genes of known functions. Consequently, the P. monodon EST database was established. The EST sequence data and the BLAST results were stored and made available through a web-accessible database (). This EST database provides a useful resource for gene identification and functional genomic studies of shrimp.

Expression of bone morphogenetic proteins in normal human intramembranous and endochondral bones

Bone morphogenetic proteins (BMPs) are growth and differentiation factors that have been purified and widely accepted to be the most important regulators in the processes of bone formation. The aim of this study was to identify the BMPs that are expressed in normal human bone, and to investigate the specific pattern of BMP2-BMP9 expression in normal human intramembranous and endochondral bone to maintain homeostasis, as well as in ex vivo primary cell culture of human osteoblasts from intramembranous and endochondral bone. Semi-quantitative RT-PCR indicated that 2 types of bone of different embryological origin have distinct patterns of BMP expression. BMP3, 4, 7 and 8 were strongly expressed in normal intramembranous bone compared to endochondral bone, whereas BMP2 and 5 were highly expressed in endochondral bone. The expression of BMP9 and BMP15 in human bone was identified for the first time. From the very similar expression patterns of BMPs in fresh normal bone and ex vivo osteoblastic cell culture, it can be proposed that the different proportions of BMPs in normal human intramembranous and endochondral bone needed to maintain normal homeostasis.

Identification and characterization of syntenin binding protein in the black tiger shrimp Penaeus monodon

Shrimp exhibit a diverse response to viral infection that is manifested in drastic up- and down-regulations of a variety of genes. In our previous work, we identified syntenin of the shrimp Penaeus monodon (Pm) as a dynamic responder to white spot syndrome virus (WSSV) infection, its message being greatly upregulated in the acute phase of the infection. In order to further explore the link between Pm-syntenin and viral infection, we performed a yeast two-hybrid screening of a P. monodon cDNA library, using Pm-syntenin as bait. One of the molecules that specifically interacted with Pm-syntenin was the receptor-binding domain of alpha-2-macroglobulin (alpha2M). A GST pull-down assay showed that GST-alpha2M, but not GST alone, was capable of co-precipitating syntenin. Another GST pull-down assay showed that GST-syntenin, but not GST alone, was capable of co-precipitating alpha2M. In addition, mutant analyses showed that the N-terminal 131 amino acids of syntenin were both necessary and sufficient to bind the C-terminus receptor-binding domain of alpha2M. Furthermore, WSSV-infected Pm showed a significant upregulation of the alpha2M message, suggesting that both syntenin and its protein partner alpha2M are upregulated in the acute phase of a WSSV infection. Taken together with a previous report showing the co-localization of alpha2M and syntenin in the exosome of a dendritic cell line, it is likely that syntenin, through its interaction with alpha2M, plays an important role in the immune defense mechanisms of viral infections of shrimps.

Molecular cloning and expression of a mammalian homologue of a translationally controlled tumor protein (TCTP) gene from Penaeus monodon shrimp

White spot syndrome, caused by white spot syndrome virus (WSSV), is a deadly disease of shrimps, causing a catastrophic loss in shrimp industries worldwide. In order to investigate molecular response of shrimp haemocyte to WSSV infection, we performed subtraction hybridization of mRNAs from healthy and WSSV-infected haemocyte. One of the genes that were severely down-regulated in moribund WSSV-infected-haemocyte was translationally controlled tumor protein (TCTP) (or fortilin). Strikingly, while there was a slight difference in the amount of TCTP message between normal and early WSSV-infected shrimps, shrimps that exhibited severe symptoms uniformly had very little TCTP in their haemocyte. Taken together with the fact that TCTP functions as an anti-apoptotic protein in mammals, our data suggest that TCTP in shrimp protects WSSV-infected shrimps from death.

Antiapoptotic protein partners fortilin and MCL1 independently protect cells from 5-fluorouracil-induced cytotoxicity

Fortilin, a potent 172-amino acid antiapoptotic polypeptide (Li, F., Zhang, D., and Fujise, K. (2001) J. Biol. Chem. 276, 47542-47549), binds MCL1, a protein of the antiapoptotic Bcl-2 family. The fortilin-MCL1 interaction stabilizes and increases the half-life of fortilin but not necessarily of MCL1 (Zhang, D., Li, F., Weidner, D., Mnjoyan, Z. H., and Fujise, K. (2002) J. Biol. Chem. 277, 37430-37438). It is not known to what extent each protein depends on the other for its apoptotic activity. Here, we present evidence that fortilin and MCL1 are capable of functioning as antiapoptotic proteins independently of each other. Using a robust small interfering RNA (siRNA)-mediated gene silencing system developed in our laboratory, we analyzed the cytoprotective effects of fortilin and MCL1 together and apart in U2OS cell lines exposed to 5-fluorouracil (5-FU) in both monoclonal and polyclonal cell populations. When MCL1 was silenced by MCL1-targeted siRNA, fortilin was still able to protect cells from 5-FU-induced cytotoxicity in a dose-dependent manner. Conversely, when fortilin was silenced by fortilin-targeted siRNA, MCL1 was also able to protect cells from 5-FU-induced cytotoxicity in a dose-dependent manner. Together, these data clearly suggest that fortilin and MCL1 can exert their cytoprotective activities independently of each other. The silencing of fortilin and MCL1 did not qualitatively change the subcellular localization of MCL1 and fortilin, respectively. The biological significance of fortilin-MCL1 interaction may be that it increases cellular resistance to apoptosis by allowing MCL1, an independently antiapoptotic protein, to stabilize another independently antiapoptotic protein, fortilin.