Quantitative trait locus mapping reveals conservation of major and minor loci for powdery mildew resistance in four sources of resistance in mungbean [Vigna radiata (L.) Wilczek]

Powdery mildew (PM) is a common and serious disease of mungbean [Vigna radiata (L.) Wilczek]. A few quantitative trait loci (QTL) for PM resistance in mungbean have been reported. The objective of this study was to locate QTL for PM resistance in two resistant accessions V4718 and RUM5. Simple sequence repeat markers were analyzed in an F₂ population from a cross between Kamphaeng Saen 1 (KPS1; susceptible to PM) and V4718 (resistant to PM), and in F₂ and BC₁F₁ populations from a cross between Chai Nat 60 (CN60; susceptible to PM) and RUM5 (resistant to PM). Progenies of 134 F_2:3 and F_2:4 lines derived from KPS1 × V4718, and 190 F_2:3 and 74 BC₁F_1:2 lines derived from CN60 × RUM5 and CN60 × (CN60 × RUM5), respectively, were evaluated for response to PM under field conditions. Multiple interval mapping identified a major QTL on linkage group (LG) 9 and two minor QTL on LG4 for the resistance in V4718, and detected two major QTL on LG6 and LG9 and one minor QTL on LG4 for the resistance in RUM5. Comparative linkage analysis of the QTL for PM resistance in this study and in previous reports suggests that the resistance QTL on LG9 in V4718, RUM5, ATF3640 and VC6468-11-1A are the same locus or linked. One QTL on LG4 is the same in three sources (V4718, RUM5 and VC1210A). Another QTL on LG6 is the same in two sources (RUM5 and VC6468-11-1A). In addition, one QTL in V4718 on LG4 appears to be a new resistance locus. These different resistance loci will be useful for breeding durably PM-resistant mungbean cultivars.     

Improving the antibacterial activity and selectivity of an ultra short peptide by hydrophobic and hydrophilic amino acid stretches

The principle of amino acid stretches tagged at the C terminal of Luecrocin I, which is an ultra-short antibacterial peptide, by tryptophan and arginine or lysine has been reported. The choice of amino acid type at each stretch position depends on the hydrophobic and hydrophilic regions visualized in the helical wheel pattern of Luecrocin I. Oligopeptide tagging should also consider the properties such as positive charge, hydrophobicity, the content of hydrophobic amino acids, polar angle, the properly hydrophilic and hydrophobic facets. Amidation at C terminal and lysine substitute for arginine can increase selectivity between mammalian cells (hemolytic and MTT assay) and bacterial cells tested. KT2 and RT2 which have 53% hydrophobic residues, 7 positive charges, 160° polar angle, ?0.02 (KT2) and ?0.04 (RT2) hydrophobicity were effective against S. typhi DMST 22842, S. epidermidis ATCC 12228, E. coli ATCC 25922 and V. cholerae non-O1, non-O139. The SEM images implied that the antibacterial mechanism of RT2 and KT2 may depend on concentration rather than time. Finally, RT2 and KT2 can be new antibacterial agents or may be further developed for alternative antibiotics.     

Bacterial Overexpression of Recombinant Heteroscorpine-1 (rHS-1), a Toxin from Heterometrus laoticus Scorpion Venom: Trends for Antibacterial Application and Antivenom Production

Heteroscorpine-1 (HS-1) was identified as a member of the scorpine family. HS-1 shows insecticidal activities, exhibiting a low median lethal dose (LD₅₀) in mealworm (Tenebrio molitor L.) and inhibitory activities against Bacillus subtilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa. In this study, a recombinant HS-1 (rHS-1) was produced by overexpression in E. coli. A large yield of product was obtained. The structure of purified rHS-1 was confirmed through mass spectrometry. Both anti-crude venom and anti-rHS-1 antibodies specifically recognized rHS-1, suggesting its structural similarity. Reactivated rHS-1 caused roughening and blebbing of bacterial cell surfaces. It showed higher activity than that of pre-refolded protein. Antisera raised against a partially purified and mis- or unfolded peptide can inhibit relevant bioactivity.     

Performance and microbial community analysis of two-stage process with extreme thermophilic hydrogen and thermophilic methane production from hydrolysate in UASB reactors

The two-stage process for extreme thermophilic hydrogen and thermophilic methane production from wheat straw hydrolysate was investigated in up-flow anaerobic sludge bed (UASB) reactors. Specific hydrogen and methane yields of 89 ml-H₂/g-VS (190 ml-H₂/g-sugars) and 307 ml-CH₄/g-VS, respectively were achieved simultaneously with the overall VS removal efficiency of 81% by operating with total hydraulic retention time (HRT) of 4 days . The energy conversion efficiency was dramatically increased from only 7.5% in the hydrogen stage to 87.5% of the potential energy from hydrolysate, corresponding to total energy of 13.4 kJ/g-VS. Dominant hydrogen-producing bacteria in the H₂-UASB reactor were Thermoanaerobacter wiegelii, Caldanaerobacter subteraneus, and Caloramator fervidus. Meanwhile, the CH₄-UASB reactor was dominated with methanogens of Methanosarcina mazei and Methanothermobacter defluvii. The results from this study suggest the two stage anaerobic process can be effectively used for energy recovery and for stabilization of hydrolysate at anaerobic conditions.     

Enhanced cytotoxicity without internuclear spread of adenovirus upon cell fusion by measles virus glycoproteins

The efficiency of viruses in cancer therapy is enhanced by proteins that mediate the fusion of infected cells with their neighbors. It was reported that replication-competent adenovirus particles can spread between nuclei within fusion-generated syncytia. To assess this conjecture, we generated fusogenic adenoviruses that express a balanced ratio of the F and H glycoproteins of measles virus. The viruses displayed enhanced cytotoxicity but largely unchanged replication efficiencies compared to a nonfusogenic virus. Most notably, the virus genomes did not spread through fusion-generated multinuclear cells. Hence, adenovirus replication in syncytia remains largely restricted to initially transduced nuclei.     

Genetic variation,population structure and identification of yellow catfish, <Emphasis Type="Italic">Mystus nemurus</Emphasis> (C&;V) in Thailand using RAPD,ISSR and SCAR marker

Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure of four subpopulations of Mystus nemurus in Thailand. The 7 RAPD and 7 ISSR primers were selected. Of 83 total RAPD fragments, 80 (96.39%) were polymorphic loci, and of 81 total ISSR fragments, 75 (92.59%) were polymorphic loci. Genetic variation and genetic differentiation obtained from RAPD fragments or ISSR fragments showed similar results. Percentage of polymorphic loci (%P), observed number of alleles, effective number of alleles, Nei’s gene diversity (H) and Shannon’s information index revealed moderate to high level of genetic variations within each M. nemurus subpopulation and overall population. High levels of genetic differentiations were received from pairwise unbiased genetic distance (D) and coefficient of differentiation. Mantel test between D or gene flow and geographical distance showed a low to moderate correlation. Analysis of molecular variance indicated that variations among subpopulations were higher than those within subpopulations. The UPGMA dendrograms, based on RAPD and ISSR, showing the genetic relationship among subpopulations are grouped into three clusters; Songkhla (SK) subpopulation was separated from the other subpopulations. The candidate species-specific and subpopulation-specific RAPD fragments were sequenced and used to design sequence-characterized amplified region primers which distinguished M. nemurus from other species and divided SK subpopulation from the other subpopulations. The markers used in this study should be useful for breeding programs and future aquacultural development of this species in Thailand.     

Antibacterial activity of plasma from crocodile (Crocodylus siamensis) against pathogenic bacteria

ABSTRACT: BACKGROUND: The Siamese crocodile (Crocodylus siamensis) is a critically endangered species of freshwater crocodiles. Crocodilians live with opportunistic bacterial infection but normally suffer no adverse effects. They are not totally immune to microbial infection, but their resistance thereto is remarkably effective. In this study, crude and purified plasma extracted from the Siamese crocodile were examined for antibacterial activity against clinically isolated, human pathogenic bacterial strains and the related reference strains. METHODS: Crude plasma was prepared from whole blood of the Siamese crocodile by differential sedimentation. The crude plasma was examined for antibacterial activity by the liquid growth inhibition assay. The scanning electron microscopy was performed to confirm the effect of crude crocodile plasma on the cells of Salmonella typhi ATCC 11778. Effect of crude crocodile plasma on cell viability was tested by MTT assay. In addition, the plasma was purified by anion exchange column chromatography with DEAE-Toyopearl 650M and the purified plasma was tested for antibacterial activity. RESULTS: Crude plasma was prepared from whole blood of the Siamese crocodile and exhibited substantial antibacterial activities of more than 40% growth inhibition against the six reference strains of Staphylococcus aureus, Salmonella typhi, Escherichia coli, Vibrio cholerae, Pseudomonas aeruginosa, and Staphylococcus epidermidis, and the four clinical isolates of Staphylococcus epidermidis, Pseudomonas aeruginosa, Salmonella typhi, and Vibrio cholerae. Especially, more than 80% growth inhibition was found in the reference strains of Salmonella typhi, Vibrio cholerae, and Staphylococcus epidermidis and in the clinical isolates of Salmonella typhi and Vibrio cholerae. The effect of the crude plasma on bacterial cells of Salmonella typhi, a certain antibacterial material probably penetrates progressively into the cytoplasmic space, perturbing and damaging bacterial membranes. The effect of the crude plasma was not toxic by the yellow tetrazolium bromide (MTT) assay using a macrophage-like cell, RAW 264.7. The pooled four fractions, designated as fractions D1-D4, were obtained by column chromatography, and only fraction D1 showed growth inhibition in the reference strains and the clinical, human pathogenic isolates. CONCLUSIONS: The crude and purified plasma from the Siamese crocodile significantly showed antibacterial activity against pathogenic bacteria and reference strains by damage cell membrane of target bacterial cells. From the MTT assay, the Siamese crocodile plasma was not cytotoxic to the cells.     

Design and structure-activity relationships of potent and selective inhibitors of undecaprenyl pyrophosphate synthase (UPPS): tetramic, tetronic acids and dihydropyridin-2-ones

Based on a pharmacophore hypothesis substituted tetramic and tetronic acid 3-carboxamides as well as dihydropyridin-2-one-3-carboxamides were investigated as inhibitors of undecaprenyl pyrophosphate synthase (UPPS) for use as novel antimicrobial agents. Synthesis and structure-activity relationship patterns for this class of compounds are discussed. Selectivity data and antibacterial activities for selected compounds are provided.     

Declining Trend of Hepatitis A Seroepidemiology in Association with Improved Public Health and Economic Status of Thailand

Hepatitis A virus (HAV) is transmitted via the fecal-oral route from contaminated food or water. As part of the most recent survey of viral hepatitis burden in Thailand, we analyzed the current seroprevalence of HAV in the country and compared with data dating back to 1971. From March to October, 2014, a total of 4,260 individuals between one month and 71 years of age from different geographical regions (North = 961; Central = 1,125; Northeast = 1,109; South = 1,065) were screened for anti-HAV IgG antibody using an automated chemiluminescent microparticle immunoassay. Overall, 34.53% (1,471/4,260) possessed anti-HAV IgG antibody, and the age-standardized seroprevalence was 48.6%. Seroprevalence rates were 27.3% (North), 30.8% (Central), 33.8% (Northeast) and 45.8% (South) and were markedly lower than in the past studies especially among younger age groups. The overall trend showed an increase in the age by which 50% of the population were anti-HAV IgG antibody: 4.48 years (1971–1972), 6 (1976), 12.49 (1990), 36.02 (2004) and 42.03 (2014).This suggests that Thailand is transitioning from low to very low HAV endemicity. Lower prevalence of HAV correlated with improved healthcare system as measured by decreased infant mortality rate and improved national economy based on increased GDP per capita. The aging HAV immuno-naïve population may be rendered susceptible to potential HAV outbreaks similar to those in industrialized countries and may benefit from targeted vaccination of high-risk groups.