Detection of ß-exotoxin synthesis in Bacillus thuringiensis using an easy bioassay with the nematode Caenorhabditis elegans.

UNLABELLED: The insecticidal activity of Bacillus thuringiensis is owing to the action of Cry and Cyt proteins. In addition to the synthesis of insecticidal proteins, some strains are able to synthesize ß-exotoxin, which is highly toxic to humans. In this regard, it is very important to have a simple method to detect ß-exotoxin to avoid the commercial production of this type of strains. In this work, we developed a simple and fast method, using the nematode Caenorhabditis elegans to detect indirectly the synthesis of ß-exotoxin by B. thuringiensis strain. Using this assay, we detected that ~60% of Mexican native strains (i.e. LBIT-471, 491, 492, 497, 507, 511, 515, 536 and 537) were toxic to the nematode (44-97% mortalities) and their ß-exotoxin (ßEx(+) ) production, including a positive control (NRD-12), was confirmed by HPLC. In addition, the negative controls (ßEx(-) ) LBIT-436 (HD-1) and LBIT-438 and also the native strains LBIT-499, 500, 521, 522, 533 and 542, did not show a detrimental effect against nematodes larvae, neither the synthesis of ß-exotoxin as determined by HPLC. Finally, we did not find a correlation between B. thuringiensis strains with similar plasmid patterns and the ß-exotoxin production. SIGNIFICANCE AND IMPACT OF THE STUDY: In this work, we implemented a qualitative and fast bioassay using the nematode Caenorhabditis elegans to detect the production of ß-exotoxin in different strains of Bacillus thuringiensis. We show that this assay is useful to detect ß-exotoxin in B. thuringiensis with high reliability, helping to discriminate strains that could not be used as bioinsecticides because of their putative risk to humans. Data show that qualitative bioassay with nematodes is a potential alternative to fly larvae bioassays, and correlated with the determination of ß-exotoxin by HPLC.

SNCA, MAPT, and GSK3B in Parkinson disease: a gene-gene interaction study.

BACKGROUND AND PURPOSE: Recent evidence suggests that variation in the SNCA, MAPT, and GSK3B genes interacts in affecting risk for Parkinson disease (PD). In the current study, we attempt to validate previously published findings, evaluating gene-gene interactions between SNCA, MAPT, and GSK3B in association with PD. METHODS: Three Caucasian PD patient-control series from the United States, Ireland, and Norway (combined n = 1020 patients and 1095 controls) were genotyped for SNCA rs356219, MAPT H1/H2-discriminating SNP rs1052553, and GSK3B rs334558 and rs6438552. RESULTS: Our findings indicate that as previously reported, the SNCA rs356219-G allele and MAPT rs1052553 (H1 haplotype) were both associated with an increased risk of PD, whilst contrary to previous reports, GSK3B variants were not. No pair-wise interaction was observed between SNCA, MAPT, and GSK3B; the risk effects of SNCA rs356219-G and MAPT rs1052553-H1 were seen in a similar manner across genotypes of other variants, with no evidence suggesting synergistic, antagonistic, or deferential effects. CONCLUSIONS: In the Caucasian patient-control series examined, risk for PD was influenced by variation in SNCA and MAPT but not GSK3B. Additionally, those three genes did not interact in determining disease risk.