Health risk assessment via consumption of Pb and Cd contaminated vegetables collected from fresh markets in the lower north of Thailand

This study aimed to investigate the Pb and Cd contamination and health risk assessment for population via consumption of vegetables sold in fresh markets around the lower north of Thailand. The concentrations of Pb and Cd in various vegetables such as root/tuber, stem, inflorescence, fruit, and leaf vegetables were analyzed using an atomic absorption spec-trophotometer. Human health risks of these metals in vegetables were assessed based on target hazard quotient (THQ). The results indicated that more than 80% of the Pb and Cd in almost all vegetable samples exceeded the maximum allowable concentration by National Food Institute criteria with an average range of 0.96–3.39 and 0.48–1.40 mg/kg, respectively. The estimated daily intakes (EDI) of Pb and Cd via dietary consumption of vegetables were between 0.001–0.010 and 0.002–0.008 mg/kg/d, respectively. All EDIs of Pb contaminated vegetables were higher than the reference dose recommended by the USEPA except for leaf edible vegetables, while all EDIs of Cd contaminated vegetables were higher than the reference dose recommended by the USEPA. THQ indicated that the consumption of Pb contaminated root/tuber, stem, inflorescence, and fruit edible vegetables and Cd contaminated leaf vegetable for the local population in the lower north of Thailand could be a severe health risk problem.     

The antigenic anatomy of SARS-CoV-2 receptor binding domain

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Identification of quantitative trait loci associated with powdery mildew resistance in mungbean using ISSR and ISSR-RGA markers

To identify the powdery mildew (PM) resistance gene in mungbean, inter-simple sequence repeat (ISSR) markers and newly developed ISSR-anchored resistance gene analog (ISSR-RGA) markers were evaluated. When F_2:7 and F_2:8 recombinant inbred line populations derived from a cross between CN72 (susceptible cultivar in Thailand) and V4718 (resistant line from Asian Vegetable Research and Development Center) were evaluated for PM resistance under field conditions, the PM resistance gene from V4718 was found to be inherited as a single major gene. Fifteen out of 75 ISSR primers produced 27 DNA bands putatively associated with PM resistance in bulk segregant analysis (BSA). Ten ISSR primers were combined with four RGA primers homologous to the nucleotide-binding site and kinase domains of resistance (R) genes to generate 40 ISSR-RGA primer combinations. When these 40 ISSR-RGA primer combinations and 10 corresponding ISSR primers were used in BSA, 873 ISSR and 756 ISSR-RGA loci were amplified. Fifty-two of 756 ISSR-RGA loci were new, and 11 of these 23 ISSR-RGA loci were putatively associated with the PM resistance. Simple linear regression confirmed that 5 of the 27 ISSR markers and 3 of the 11 ISSR-RGA markers were significantly associated with the PM resistance gene. When these eight ISSR and ISSR-RGA markers were used for quantitative trait loci (QTL) analysis, multiple interval mapping identified a major QTL, qPMC72V18-1, explaining up to 92.4% of the phenotypic variation, flanked by I42PL229 and I85420 markers at the distance of 4 and 9 cM, respectively. These results suggest that ISSR and ISSR-RGA markers are highly efficient tools for mapping PM resistance gene in mungbean. The markers closely linked to the PM resistance gene will be useful for future marker-assisted selection to develop mungbean varieties resistant to PM.     

Molecular Characterization of Clostridium botulinum Isolates from Foodborne Outbreaks in Thailand, 2010

Background

Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010.

Methodology/Principal Findings

A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1–B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2).

Conclusion/Significance

This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.     

Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera

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Evaluation of salt tolerance at the seedling stage in rice genotypes by growth performance, ion accumulation, proline and chlorophyll content

Aims

The objectives of this study were to evaluate salt tolerance level of rice genotypes using the well-established screening criteria; the salt injury score, survival percentage and ratio between Na⁺ and K⁺, as well as the contents of proline and chlorophyll, and to identify the relationship between salt tolerance and physiological characters.

Methods

One hundred and six rice genotypes were grown in hydroponic solutions subjected to salt stress and evaluated for salt tolerance ability and the physiological parameters. Multivariate cluster analysis was performed based on salinity tolerance scores (ST scores; score 1 being the most tolerant, score 9 the most sensitive), survival percentage and Na⁺/K⁺ ratio.

Results

ST scores based on salt injury symptoms were negatively correlated with survival percentage and chlorophyll concentration in the stressed seedlings but positively correlated with Na⁺/K⁺ ratio and proline content. Rice genotypes were classified into five salt tolerance groups: tolerant (T), moderately tolerant (MT), moderately sensitive (MS), sensitive (S) and highly sensitive (HS). The means of ST scores were significantly different among the five tolerance groups indicating that the ST score was the most reliable index for identifying salt tolerance. The means of Na⁺/K⁺ ratio and proline content in stressed seedlings were distinctively different between the extreme T and HS groups, but the means among the intermediate groups (MT, MS and S) were not significantly different. Chlorophyll content, on the other hand, was not related to the levels of salt tolerance.

Conclusions

In addition to the commonly used Na⁺/K⁺ ratio, proline content is suggested to be another useful criterion to differentiate salt-tolerant from salt-sensitive rice. This study also identified several Thai improved and local cultivars with the level of salt tolerance and physiological characters comparable to Pokkali, the standard salt-tolerant donor and may be utilized as alternative sources of salt tolerance alleles.