Arctigenin, a natural compound, activates AMP-activated protein kinase via inhibition of mitochondria complex I and ameliorates metabolic disorders in ob/ob mice

AIMS/HYPOTHESIS

Arctigenin is a natural compound that had never been previously demonstrated to have a glucose-lowering effect. Here it was found to activate AMP-activated protein kinase (AMPK), and the mechanism by which this occurred, as well as the effects on glucose and lipid metabolism were investigated.

METHODS

2-Deoxyglucose uptake and AMPK phosphorylation were examined in L6 myotubes and isolated skeletal muscle. Gluconeogenesis and lipid synthesis were evaluated in rat primary hepatocytes. The acute and chronic effects of arctigenin on metabolic abnormalities were observed in C57BL/6J and ob/ob mice. Changes in mitochondrial membrane potential were measured using the J-aggregate-forming dye, JC-1. Analysis of respiration of L6 myotubes or isolated mitochondria was conducted in a channel oxygen system.

RESULTS

Arctigenin increased AMPK phosphorylation and stimulated glucose uptake in L6 myotubes and isolated skeletal muscles. In primary hepatocytes, it decreased gluconeogenesis and lipid synthesis. The enhancement of glucose uptake and suppression of hepatic gluconeogenesis and lipid synthesis by arctigenin were prevented by blockade of AMPK activation. The respiration of L6 myotubes or isolated mitochondria was inhibited by arctigenin with a specific effect on respiratory complex I. A single oral dose of arctigenin reduced gluconeogenesis in C57BL/6J mice. Chronic oral administration of arctigenin lowered blood glucose and improved lipid metabolism in ob/ob mice.

CONCLUSIONS/INTERPRETATION

This study demonstrates a new role for arctigenin as a potent indirect activator of AMPK via inhibition of respiratory complex I, with beneficial effects on metabolic disorders in ob/ob mice. This highlights the potential value of arctigenin as a possible treatment of type 2 diabetes.

Endotoxin tolerance attenuates liver ischemia/reperfusion injury by down-regulation of interleukin-1 receptor-associated kinase 4 in kupffer cells

AIM

The aim of this study was to study the role of interleukin-1 receptor-associated kinase 4 (IRAK-4) in the formation of endotoxin tolerance (ET) in liver ischemia/reperfusion (I/R) injury.

METHODS

Animals were randomly divided into 3 groups: control group, I/R group, and ET group. Liver morphological changes were observed using optical microscopy with hematoxylin eosin (HE) staining. Alanine aminotransferase (ALT) was quantified to measure liver functional injury. The messenger RNA (mRNA) and protein expressions of IRAK-4 in Kupffer cells (KCs) isolated from recipients were detected using real-time polymerase chain reaction (PCR) and Western blot, respectively. The activities of NF-κB and the supernatant levels of tumor necrosis factor-alpha (TNF-α), IL-10 were assayed using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Endotoxin preconditioning improved hepatic tissue injury as indicated by morphological analysis, whereas serum ALT levels were significantly decreased at various times (P < .05); concurrently, the expression of IRAK-4 and TNF-α in KCs was down-regulated (P < .05) and the secretion of IL-10 was enhanced (P < .05); NF-κB DNA-binding activity of KCs was also significantly inhibited by endotoxin preconditioning (P < .05).

CONCLUSION

Endotoxin preconditioning attenuated the liver I/R injury caused by transplantation. The expression of IRAK-4 in KCs may play an important role in the formation of ET.

Fsp27 promotes lipid droplet growth by lipid exchange and transfer at lipid droplet contact sites

The lipid droplet–associated protein Fsp27 mediates lipid droplet growth by promoting directional lipid transfer from smaller to larger lipid droplets.

Lipid droplets (LDs) are dynamic cellular organelles that control many biological processes. However, molecular components determining LD growth are poorly understood. Genetic analysis has indicated that Fsp27, an LD-associated protein, is important in controlling LD size and lipid storage in adipocytes. In this paper, we demonstrate that Fsp27 is focally enriched at the LD–LD contacting site (LDCS). Photobleaching revealed the occurrence of lipid exchange between contacted LDs in wild-type adipocytes and Fsp27-overexpressing cells but not Fsp27-deficient adipocytes. Furthermore, live-cell imaging revealed a unique Fsp27-mediated LD growth process involving a directional net lipid transfer from the smaller to larger LDs at LDCSs, which is in accordance with the biophysical analysis of the internal pressure difference between the contacting LD pair. Thus, we have uncovered a novel molecular mechanism of LD growth mediated by Fsp27.

Long-term outcomes after laparoscopic total mesorectal excision for advanced rectal cancer

PURPOSE

The aim of this study was to evaluate the long-term outcomes of laparoscopic total mesorectal excision in the treatment of advanced rectal cancer in a randomised population.

METHODS

Between 2001 and 2005, 125 patients (70 males, 55 females, mean age 55.5 (standard deviation (SD) 11) years, range 25 - 81 years) with rectal cancer were evaluated and prospectively followed up in our hospital (mean follow-up 42 (SD 23 months, range 5 - 113 months). The 5-year overall survival rate, 5-year disease-free survival rate and recurrence rate were analysed.

RESULTS

There were 54 cases of cancer defined as UICC stage II and 68 cases defined as stage III. Of these cases, 22 were localised to the upper rectum, 50 to the middle rectum and 53 to the lower rectum. The 5-year overall survival rates were 71.3% and 51% among the stage II and the stage III patients, respectively. The 5-year disease-free survival rates were 59.2% and 45.4% among the stage II and the stage III cancer patients, respectively. The overall recurrence rate was 16.8% (local recurrence rate 11.25%, distant recurrence rate 8%). Multivariate analysis showed that age and size were independent predictors of overall survival (p=0.006 and p<0.001 for stage II and stage III patients, respectively).

CONCLUSIONS

Our results suggest good long-term outcomes of laparoscopic surgery in the treatment of rectal cancer. However, this technique should be used with caution in older patients and patients with larger tumours.

Antimicrobial activity of butyrate glycerides toward Salmonella Typhimurium and Clostridium perfringens

The antimicrobial activities of n-butyric acid and its derivatives against Salmonella Typhimurium and Clostridium perfringens were studied. n-Butyric acid and its derivatives (monobutyrin and a mixture of mono-, di-, and tri-glycerides of butyric acid) were added at different concentrations (ranging from 250 to 7,000 mg/kg to a media inoculated with either Salmonella Typhimurium or C. perfringens. The antimicrobial activity of butyric acid against C. perfringens was measured at 2 bacterium concentrations and 2 inoculations involving ambient aerobic or anaerobic conditions. The most effective antimicrobial activity for Salmonella Typhimurium was observed with n-butyric acid, with 90% inhibition rate at a concentration of 1,500 mg/kg. Although minimal inhibition for Salmonella Typhimurium was observed with butyric acid glycerides, lipase addition to a mixture of mono-, di-, and triglycerides of butyric acid increased (P < 0.01) antimicrobial activity of these derivatives. Antimicrobial activity of butyric acid and its derivative against C. perfringens was higher when using a moderate initial inoculation concentration (10(5)) compared with a higher initial concentration (10(7)) of this bacterium. At a lower inoculation of C. perfringens (10(5)), >90% inhibition rate by all butyric acid glycerides was observed with prior aerobic inoculation at 2,000 mg/kg, whereas using anaerobic inoculation, only 50% monobutyrin maintained >90% inhibitory effect at 3,000 mg/kg. The antimicrobial effect of monobutyrin against C. perfringens was generally higher (P < 0.01) for 50% monobutyrin than for 100% monobutyrin. Either a mixture of butyric acid derivatives or 50% monobutyrin decreased (P < 0.01) C. perfringens in a media containing intestinal contents whereas only 50% monobutyrin decreased (P < 0.01) Salmonella Typhimurium within a media containing cecal contents from mature Leghorns. These results show that n-butyric acid and 50% monobutyrin could be used to control Salmonella Typhimurium or C. perfringens in poultry species.

Expression of glucocorticoid-induced tumor necrosis factor receptor ligand in rat graft after liver transplantation

BACKGROUND

Costimulation between the glucocorticoid-induced tumor necrosis factor receptor and its ligand (GITRL) breaks immunologic tolerance induced by regulatory T cells. The purpose of this research was to examine the involvement of GITRL during rat liver transplantation, the survival of which depends on interactions between regulatory T cells and Kupffer cells (KCs).

METHODS

Recipients were divided into 2 groups: The allograft group underwent orthotopic liver transplantation from male Lewis to Brown Norway (BN) rats and the isograft group, BN-to-BN liver transplantation. We evaluated 2-week survival rates, histologic changes, as well as serum and supernatant levels of tumor necrosis factor-α (TNF-α); GITRL, and TNF-α expressions in the graft, and GITRL expression by graft-derived KCs.

RESULTS

TNF-α levels were increased in plasma and in the supernates of KCs during allograft transplantation compared with isograft liver transplantation (P <.05). The expressions of TNF-α and GITRL in liver grafts were increased during acute rejection. Furthermore, the expression of GITRL on KCs derived from allografts was increased compared with isografts (P < .05).

CONCLUSION

GITRL expression on KCs may mediate acute rejection in liver transplantation.

Establishment and characterization of a new cell line derived from kidney of grouper, Epinephelus akaara (Temminck & Schlegel), susceptible to Singapore grouper iridovirus (SGIV)

A marine fish cell line derived from the kidney of red-spotted grouper, Epinephelus akaara, designated as EAGK was established and characterized. The EAGK cells multiplied well in Leibovitz's L-15 medium containing 10% foetal bovine serum at 25 °C and have been subcultured for more than 90 passages. Karyotyping, chromosomal typing and ribosomal RNA (rRNA) genotyping analysis revealed that EAGK had a modal diploid chromosome number of 82 and was a fibroblast cell line originated from grouper. A severe cytopathic effect was observed in EAGK cells incubated with Singapore grouper iridovirus (SGIV), but not with soft-shelled turtle iridovirus, viral nervous necrosis virus or spring viraemia of carp virus. SGIV replication was further confirmed by immunofluorescence, electron microscopy and virus titre determination. Bright fluorescence was observed after transfection with fluorescent protein reporter plasmids, indicating that EAGK cells can be used to identify gene functions in vitro. In addition, the cell organelles including mitochondria and endoplasm reticulum changed and aggregated around virus factories after SGIV infection, suggested that the EAGK cell line could be an important tool for investigation of iridovirus-host interactions.

Efficacy of detoxification of deoxynivalenol-contaminated corn by Bacillus sp. LS100 in reducing the adverse effects of the mycotoxin on swine growth performance

Biodetoxification of mycotoxins is a novel strategy to control mycotoxicoses in animals. Bacillus sp. LS100, which transforms deoxynivalenol (DON) to a less toxic chemical de-epoxy DON (DOM-1), was evaluated for its efficacy in reducing the adverse effects of DON on swine growth performance. A feeding trial was conducted in growing pigs with four treatments: (1) corn meal without detectable DON served as control (Non-toxic Corn); (2) Fusarium-infected corn giving a toxic diet containing 5 µg DON g(-1) (Toxic Corn); (3) Toxic Corn detoxified with Bacillus sp. LS100 giving a detoxified diet containing 5 µg DOM-1 g(-1) (LS100-De-toxic Corn); (4) Non-toxic Corn treated with Bacillus sp. LS100 serving as bacterial control (LS100-Non-toxic Corn). During 9 days of exposure to the treatments, pigs on Toxic Corn showed a significant reduction in daily feed consumption, daily weight gain and feed efficiency by 29, 48 and 29%, respectively, compared to pigs on Non-toxic Corn. These parameters of the pigs fed LS100-De-toxic Corn diet were 45, 82 and 32% greater, respectively, than those of pigs fed Toxic Corn diet, and were similar to those pigs fed Non-toxic Corn and LS100-Non-toxic Corn diets. There were no significant differences between the treatments of LS100-Non-toxic Corn and Non-toxic Corn diets, implying that the bacterial isolate might not have significantly affected nutrition and palatability of the feed or had negative effects on the pig's feeding performance. The results have proved that microbial detoxification of DON in contaminated feed can eliminate negative effects of the mycotoxin, and the pre-feeding detoxification approach may be applied in the livestock industry.

Glutamine induces heat shock protein 70 expression via O-GlcNAc modification and subsequent increased expression and transcriptional activity of heat shock factor-1

BACKGROUND

Glutamine (Gln) has been shown to induce heat shock protein (HSP) expression and to attenuate lipopolysaccharide (LPS)-mediated cardiovascular dysfunction, but the underlying mechanisms are not fully clear. We tested the hypothesis that protection by Gln-induced HSP70 expression is due to enhanced O-linked β-N-acetylglucosamine (O-GlcNAc) modification levels and subsequent increases in the levels of endonuclear heat shock protein factor-1 (HSF-1) expression and HSF-1 transcriptional activity in LPS-treated cardiomyocytes.

METHODS

Primary cultures of neonatal rat cardiomyocytes were divided into control, LPS (4 μg/mL), Gln+LPS (Gln 5 mM+LPS 4 μg/mL), Gln+LPS+Alloxan (an O-linked-N-acetyl glucosamine transferase inhibitor, 1 mM) and Gln+LPS+PUGNAc (an O-GlcNAcase inhibitor; 100 μM) groups. After incubation for six hours, the levels of cardiomyocyte viability, lactate dehydrogenase (LDH) activity, O-GlcNAc modification, endonuclear HSF-1 expression, HSF-1 transcription activity and cellular HSP70 expression were measured in all groups.

RESULTS

There were no significant differences in cell viability among the five groups. LDH activity levels were much higher in the LPS group than in the control group, but they markedly decreased in the Gln+LPS group (P<0.05). Gln's protection in the Gln+LPS group was associated with a significant increase in the levels of O-GlcNAc modification, endonuclear HSF-1 expression, HSF-1 transcription activity and cellular HSP70 expression compared to the LPS group (P<0.05). The protective action by Gln in LPS-treated cardiomyocytes could either be mimicked by 1 μM PUGNAc or banished by 1 mM alloxan.

CONCLUSION

Gln induces HSP70 expression and attenuates LPS-induced cardiomyocyte damage. The molecular mechanism of Gln-induced HSP70 expression appears to be mediated via enhancement of O-GlcNAc modification and subsequently to increase levels of endonuclear HSF-1 expression and HSF-1 transcription activity.

A phase II, open-label, multicenter, prospective study of paclitaxel plus capecitabine with subsequent capecitabine maintenance therapy as first-line treatment for metastatic or recurrent gastric cancer

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Background: Paclitaxel has been shown to be effective in AGC. We assess the efficacy and safety of PX-X therapy as first-line treatment for metastatic or recurrent GC in a phase II, multicenter, prospective study.

Methods: Patients with previously untreated gastric adenocarcinoma, signed informed consent, target lesion(s), KPS ≥ 70 and adequate organ functions are eligible. Paclitaxel was given as 80 mg/m2 by 3-hour infusion day 1,8, capecitabine 1,000 mg/m2, BID, D1-14, Q3W. Cycles were repeated until progression or maximum 6 or AEs. Then the patients without progression began the second stage treatment as X with same dose/schedule until progression or AEs. PFS, RR, DCR, OS and AEs are the end points evaluated in this study.

Results: From 12/2006 to 4/2010, 195 patients (ITT) were enrolled in 21 centers, 1 patient was withdraw due to allergy to paclitaxel, 194 cases were PP. After median follow up of 16.2 months, 16 cases lost. In ITT, 119 pts progressed, 104 pts died. Mean cycles the patients completed was 5. CR and PR were achieved in 1.0% (2 pts) and 32.3% (63 pts) of pts (RR 33.3%), 75 pts had SD (38.5%), 25 pts (12.8%) progressed. PFS of ITT is 208 d (95% CI: 169.1-246.8) and estimated OS is 456 d (95%CI: 286.9-624.2). 45 pts continued to X after PX with good tolerance, median cycles accepted was 4, and OS was longer than 590 d. 23 patients accepted surgery after chemotherapy; the survival data have not been reached. After disease progression, 61 cases accepted second-line treatment, including oxaplatin/irinotecan-based chemotherapy, target therapy, and local therapy. AEs were mild and the grade 3/4 toxicities were leucopenia (13.8%), alopecia(13.3%), neutropenia (8.2%), fatigue (6.7%), nausea/vomiting (5.1%), HFS (5.1%), diarrhea(3.6%), neurotoxicity (3.1%), hepatic dysfuction (2.6%), and anaphylactic shock (0.5%). No treatment- related deaths were recorded in all patients.

Conclusions: PX-X as first-line treatment was promising in advanced gastric cancer. Further evaluation of this combination therapy is being carried on phase III clinical trial of ML22697.

No significant financial relationships to disclose.

LITAF and TNFSF15, two downstream targets of AMPK, exert inhibitory effects on tumor growth

Lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) α factor (LITAF) is a multiple functional molecule whose sequence is identical to the small integral membrane protein of the lysosome/late endosome. LITAF was initially identified as a transcription factor that activates transcription of proinflammatory cytokine in macrophages in response to LPS. Mutations of the LITAF gene are associated with a genetic disease, called Charcot-Marie-Tooth syndrome. Recently, we have reported that mRNA levels of LITAF and TNF superfamily member 15 (TNFSF15) are upregulated by 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK). The present study further assesses their biological functions. Thus, we show that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a pharmacological activator of AMPK, increases the abundance of LITAF and TNFSF15 in LNCaP and C4-2 prostate cancer cells, which is abrogated by small hairpin RNA (shRNA) or the dominant-negative mutant of AMPK α1 subunit. Our data further demonstrate that AMPK activation upregulates the transcription of LITAF. Intriguingly, silencing LITAF by shRNA enhances proliferation, anchorage-independent growth of these cancer cells and tumor growth in the xenograft model. In addition, our study reveals that LITAF mediates the effect of AMPK by binding to a specific sequence in the promoter region. Furthermore, we show that TNFSF15 remarkably inhibits the growth of prostate cancer cells and bovine aortic endothelial cells in vitro, with a more potent effect toward the latter. In conjuncture, intratumoral injection of TNFSF15 significantly reduces the size of tumors and number of blood vessels and induces changes that are characteristic of tumor cell differentiation. Therefore, our studies for the first time establish the regulatory axis of AMPK-LITAF-TNFSF15 and also suggest that LITAF may function as a tumor suppressor.

Part 5. Public health and air pollution in Asia (PAPA): a combined analysis of four studies of air pollution and mortality

BACKGROUND

In recent years, Asia has experienced rapid economic growth and a deteriorating environment caused by the increasing use of fossil fuels. Although the deleterious effects of air pollution from fossil-fuel combustion have been demonstrated in many Western nations, few comparable studies have been conducted in Asia. Time-series studies of daily mortality in Asian cities can contribute important new information to the existing body of knowledge about air pollution and health. Not only can these studies verify important health effects of air pollution in local regions in Asia, they can also help determine the relevance of existing air pollution studies to mortality and morbidity for policymaking and environmental controls. In addition, the studies can help identify factors that might modify associations between air pollution and health effects in various populations and environmental conditions. Collaborative multicity studies in Asia-especially when designed, conducted, and analyzed using a common protocol-will provide more robust air pollution effect estimates for the region as well as relevant, supportable estimates of local adverse health effects needed by environmental and public-health policymakers.

SPECIFIC OBJECTIVES

The Public Health and Air Pollution in Asia (PAPA*) project, sponsored by the Health Effects Institute, consisted of four studies designed to assess the effects of air pollution on mortality in four large Asian cities, namely Bangkok, in Thailand, and Hong Kong, Shanghai, and Wuhan, in China. In the PAPA project, a Common Protocol was developed based on methods developed and tested in NMMAPS, APHEA, and time-series studies in the literature to help ensure that the four studies could be compared with each other and with previous studies by following an established protocol. The Common Protocol (found at the end of this volume) is a set of prescriptive instructions developed for the studies and used by the investigators in each city. It is flexible enough to allow for adjustments in methods to optimize the fit of health-effects models to each city's data set. It provides the basis for generating reproducible results in each city and for meta-estimates from combined data. By establishing a common methodology, factors that might influence the differences in results from previous studies can more easily be explored. Administrative support was provided to ensure that the highest quality data were used in the analysis. It is anticipated that the PAPA results will contribute to the international scientific discussion of how to conduct and interpret time-series studies of air pollution and will stimulate the development of high-quality routine systems for recording daily deaths and hospital admissions for time-series analysis.

METHODS

Mortality data were retrieved from routine databases with underlying causes of death coded using the World Health Organization (WHO) International Classification of Diseases, 9th revision or 10th revision (ICD-9, ICD-10). Air quality measurements included nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with aerodynamic diameter < or = 10 microm (PM10), and ozone (O3) and were obtained from several fixed-site air monitoring stations that were located throughout the metropolitan areas of the four cities and that met the standards of procedures for quality assurance and quality control carried out by local government units in each city. Using the Common Protocol, an optimized core model was established for each city to assess the effects of each of the four air pollutants on daily mortality using generalized linear modeling with adjustments for time trend, seasonality, and other time-varying covariates by means of a natural-spline smoothing function. The models were adjusted to suit local situations by correcting for influenza activity, autocorrelation, and special weather conditions. Researchers in Hong Kong, for example, used influenza activity based on frequency of respiratory mortality; researchers in Hong Kong and Shanghai used autoregressive terms for daily outcomes at lag days; and researchers in Wuhan used additional smoothing for periods with extreme weather conditions.

RESULTS AND DISCUSSION

For mortality due to all natural (nonaccidental) causes at all ages, the effects of air pollutants per 10-microg/m3 increase in concentration was found to be higher in Bangkok than in the three Chinese cities, with the exception of the effect of NO2 in Wuhan. The magnitude of the effects for cardiovascular and respiratory mortality were generally higher than for all natural mortality at all ages. In addition, the effects associated with PM10 and O3 in all natural, cardiovascular; and respiratory mortality were found to be higher in Bangkok than in the three Chinese cities. The explanation for these three findings might be related to consistently higher daily mean temperatures in Bangkok, variations in average time spent outdoors by the susceptible populations, and the fact that less air conditioning is available and used in Bangkok than in the other cities. However, when pollutant concentrations were incorporated into the excess risk estimates through the use of interquartile range (IQR), the excess risk was more comparable across the four cities. We found that the increases in effects among older age groups were greater in Bangkok than in the other three cities. After excluding data on extremely high concentrations of PM10 in Bangkok, the effect estimate associated with PM10 concentrations decreased in Bangkok (suggesting a convex relationship between risk and PM10, where risk levels off at high concentrations) instead of increasing, as it did in the other cities. This leveling off of effect estimates at high concentrations might be related to differences in vulnerability and exposure of the population to air pollution as well as to the sources of the air pollutant. IMPLICATIONS OF THE STUDY: The PAPA project is the first coordinated Asian multicity air pollution study ever published; this signifies the beginning of an era of cooperation and collaboration in Asia, with the development of a common protocol for coordination, data management, and analysis. The results of the study demonstrated that air pollution in Asia is a significant public health burden, especially given the high concentrations of pollutants and high-density populations in major cities. When compared with the effect estimates reported in the research literature of North America and Western Europe, the study's effect estimates for PM10 were generally similar and the effect estimates for gaseous pollutants were relatively higher. In Bangkok, however, a tropical city where total exposures to outdoor pollution might be higher than in most other cities, the observed effects were greater than those reported in the previous (i.e., Western) studies. In general, the results suggested that, even though social and environmental conditions across Asia might vary, it is still generally appropriate to apply to Asia the effect estimates for other health outcomes from previous studies in the West. The results also strongly support the adoption of the global air quality guidelines recently announced by WHO.

Establishment and characterization of a new marine fish cell line derived from red-spotted grouper Epinephelus akaara

A new marine fish cell line, EAGL, derived from the liver of red-spotted grouper Epinephelus akaara was established and characterized. The cells multiplied well in minimum essential medium (MEM) supplemented with 10% foetal bovine serum (FBS) at temperatures between 25 and 30° C. The growth rate of this cell line increased as the proportion of FBS increased from 5 to 20% at 25° C, with maximum growth at the concentration of 15 or 20% FBS. Morphologically, the cells were epithelial-like and the presence of pancytokeratin confirmed their epithelial origin. Chromosome analysis revealed that the modal chromosome number was 48. The susceptibility of the cell line to four fish viruses was tested. Significant cytopathic effect (CPE) was only observed in Singapore grouper iridovirus (SGIV)-infected cells, and the virus replication was further confirmed by immunofluorescence, electron microscopy and real-time reverse-transcription (RT)-PCR assay. When the cells were transfected with pEGFP-N3 plasmid, bright fluorescent signals were observed, suggesting that this cell line can be used for transgenic and genetic manipulation studies.

Differential profiles of gene expression in grouper Epinephelus coioides, infected with Singapore grouper iridovirus, revealed by suppression subtractive hybridization and DNA microarray

Suppression subtractive hybridization (SSH) was used to generate a subtracted cDNA library enriched with gene transcripts differentially expressed in the spleen of orange-spotted grouper Epinephelus coioides after 5 days of infection with Singapore grouper iridovirus (SGIV). In the forward and reverse-subtracted libraries, 260 and 153 non-redundant expressed sequence tags (EST), respectively, were identified. These annotated genes responding to SGIV infection were grouped into eight gene categories related to immunity, cell structure, transcription-translation, cell signalling, metabolism, mitochondrial proteins, ribosomal proteins and unknown or hypothetical proteins. A DNA microarray containing all the differentially expressed genes was constructed, and the gene expression patterns in different tissues were investigated in virus-infected E. coioides. Of these genes, four associated with the infection processes were identified and further investigated by quantitative real-time PCR. These results provide new insights into the molecular basis of host-pathogen interactions in E. coioides, and will help the development of control strategies against SGIV infection.