The occurrence of tributyltin (TBT) is reported in the coastal waters of a few selected sites in Peninsular Malaysia. Water, bivalves and sediment samples collected were analysed specifically for TBT using sensitive analytical methods which involved a solvent extraction procedure with appropriate clean-up followed by graphite furnace atomic absorption spectrometric measurements. The levels of TBT in the seawater in unexposed areas were found in the range from <3.4 to 20 ng litre(-1) as compared to coastal areas with high boat and ship activities where TBT levels in seawater were generally above 30 ng litre(-1), with the highest level found at 281.8 ng litre(-1). TBT levels in the tissues of random cockle and soft-shell clam samples from local markets were found in the range from <0.5 to 3.7 ng g(-1) wet weight. The levels of TBT found in green mussel samples both from the market (23.5 ng g(-1) wet weight) and those from a mussel farm (14.2 ng g(-1) wet weight) indicate slight accumulation of TBT. In sediments, TBT levels were found ranging from <0.7 ng g(-1) dry weight in unexposed coastal sites to as high as 216.5 ng g(-1) dry weight for a site within a port area.
Cucurbits are important crops in the world. However, leaf curl disease constrains their production. Here, begomovirus diversity and pathogenicity associated with the disease in Malaysia were studied based on 49 begomovirus-detected out of 69 symptomatic plants from seven cucurbit crops in 15 locations during 2016 and 2017. The presence of Squash leaf curl China virus (SLCCNV) and Tomato leaf curl New Delhi virus (ToLCNDV) were confirmed by virus detection by polymerase chain reaction, viral DNA sequence analysis and specific detection of the viral components. ToLCNDV Malaysian isolates were further distinguished into strains A, B, C and D. Virus co-infection was detected in bitter gourd, bottle gourd and squash. Among them, eight bitter gourd samples were detected without SLCCNV DNA-A. However, one bottle gourd and five squash samples were without ToLCNDV DNA-B. Pseudorecombination of ToLCNDV DNA-A and SLCCNV DNA-B was detected in two bitter gourd samples. The pathogenic viruses and pseudorecombinants were confirmed by agroinoculation. The viral DNA-B influencing on symptomology and host range was also confirmed. The results strengthen the epidemic of cucurbit-infecting begomovirus in Malaysia as well as Southeast Asia. Especially, the natural pseudorecombinant of begomovirus that extends host range and causes severe symptom implies a threat to crops.
Rachycentron canadum (cobia) is a marine fish species of high economic value in aquaculture due to its fast growth rate and good feed conversion efficacy. Regrettably, the industry has been affected by significant setbacks from high mortality due to diseases. Consequently, an improved perception of innate immunity correlated to each mucosal-associated lymphoid tissue (MALT) in teleost fish is necessary to understand hosts' response towards infections better. The utilization of polysaccharides in seaweed to stimulate the immune system has gathered unprecedented attention. The present study examined the immunostimulatory effects of Sarcodia suae water extracts (SSWE) on in vivo gill-, gut- and skin-associated lymphoid tissues (GIALT, GALT, and SALT) via immersion and oral ingestions. The GIALT genes (TNF-α, Cox2, IL-1β, IL-6, IL-8, IL-17 A/F1-3, IL-11, IL-12, IL-15, IL-18, MHCIa, IgM, and IgT) except IL-10 recorded positive upregulations in a dose-dependent manner post 24 h immersion in SSWE, indicating the algae extract contained bioactive compounds that could stimulate the immune genes. The upregulation of IL-12, IL-15, and IL-18 in the gills and hindgut post-SSWE immersion indicated that the extract could promote Th1-related responses in the MALTs. The modulation of immune gene expressions in the feeding trial was less potent than in the SSWE immersion. These findings indicated that the SSWE stimulated robust immune responses in both the GIALT and GALT of cobia. This suggests that the SSWE could be further explored as an effective immersive stimulant for fish, enhancing their immune system against pathogens.
Multidrug resistance in cancer cells arises from altered drug permeability of the cell. We previously reported activation of the Wnt pathway in ABCB1-overexpressed human uterus sarcoma drug-resistant MES-SA/Dx5 cells through active β-catenin and associated transactivation activities, and upregulation of Wnt-targeting genes. In this study, Wnt5A was found to be significantly upregulated in MES-SA/Dx5 and MCF7/ADR2 cells, suggesting an important role for the Wnt5A signaling pathway in cancer drug resistance. Higher cAMP response elements and Tcf/Lef transcription activities were shown in the drug-resistant cancer cells. However, expression of Wnt target genes and CRE activities was downregulated in Wnt5A shRNA stably-transfected MES-SA/Dx5 cells. Cell viability of the drug-resistant cancer cells was also reduced by doxorubicin treatment and Wnt5A shRNA transfection, or by Wnt5A depletion. The in vitro data were supported by immunohistochemical analysis of 24 paired breast cancer biopsies obtained pre- and post-chemotherapeutic treatment. Wnt5A, VEGF and/or ABCB1 were significantly overexpressed after treatment, consistent with clinical chemoresistance. Taken together, the Wnt5A signaling pathway was shown to contribute to regulating the drug-resistance protein ABCB1 and β-catenin-related genes in antagonizing the toxic effects of doxorubicin in the MDR cell lines and in clinical breast cancer samples.
Inappropriate c-MET signaling in cancer can enhance tumor cell proliferation, survival, motility, and invasion. Inhibition of c-MET signaling induces apoptosis in a variety of cancers. It has also been recognized as a novel anticancer therapy approach. Furthermore, reports have also indicated that constitutive expression of P-glycoprotein (ABCB1) is involved in the HGF/c-MET-related pathway of multidrug resistance ABCB1-positive human hepatocellular carcinoma cell lines. We previously reported that elevated expression levels of PKCδ and AP-1 downstream genes, and HGF receptor (c-MET) and ABCB1, in the drug-resistant MES-SA/Dx5 cells. Moreover, leukemia cell lines overexpressing ABCB1 have also been shown to be more resistant to the tyrosine kinase inhibitor imatinib mesylate. These findings suggest that chemoresistant cancer cells may also develop a similar mechanism against chemotherapy agents. To circumvent clinical complications arising from drug resistance during cancer therapy, the present study was designed to investigate apoptosis induction in ABCB1-overexpressed cancer cells using c-MET-targeted RNA interference technology in vitro and in vivo. The results showed that cell viability decreased and apoptosis rate increased in c-MET shRNA-transfected HGF/c-MET pathway-positive MES-SA/Dx5 and MCF-7/ADR2 cell lines in a dose-dependent manner. In vivo reduction of tumor volume in mice harboring c-MET shRNA-knockdown MES-SA/Dx5 cells was clearly demonstrated. Our study demonstrated that downregulation of c-MET by shRNA-induced apoptosis in a multidrug resistance cell line.