Biological detoxification of the mycotoxin deoxynivalenol and its use in genetically engineered crops and feed additives

Deoxynivalenol (DON) is the major mycotoxin produced by Fusarium fungi in grains. Food and feed contaminated with DON pose a health risk to humans and livestock. The risk can be reduced by enzymatic detoxification. Complete mineralization of DON by microbial cultures has rarely been observed and the activities turned out to be unstable. The detoxification of DON by reactions targeting its epoxide group or hydroxyl on carbon 3 is more feasible. Microbial strains that de-epoxidize DON under anaerobic conditions have been isolated from animal digestive system. Feed additives claimed to de-epoxidize trichothecenes enzymatically are on the market but their efficacy has been disputed. A new detoxification pathway leading to 3-oxo-DON and 3-epi-DON was discovered in taxonomically unrelated soil bacteria from three continents; the enzymes involved remain to be identified. Arabidopsis, tobacco, wheat, barley, and rice were engineered to acetylate DON on carbon 3. In wheat expressing DON acetylation activity, the increase in resistance against Fusarium head blight was only moderate. The Tri101 gene from Fusarium sporotrichioides was used; Fusarium graminearum enzyme which possesses higher activity towards DON would presumably be a better choice. Glycosylation of trichothecenes occurs in plants, contributing to the resistance of wheat to F. graminearum infection. Marker-assisted selection based on the trichothecene-3-O-glucosyltransferase gene can be used in breeding for resistance. Fungal acetyltransferases and plant glucosyltransferases targeting carbon 3 of trichothecenes remain promising candidates for engineering resistance against Fusarium head blight. Bacterial enzymes catalyzing oxidation, epimerization, and less likely de-epoxidation of DON may extend this list in future

Research on Social Media User Suicide Influencing Factors, Active Recognition and Intervention

With the development of Internet, more and more people express their own feeling on the social media, including suicide declaration, which create new opportunity for the identifying, preventing and intervening of suicide high risk group. The influencing factors of suicide behavior are numerous, mainly including internal and external factors. Internal factors include biological factors, mental disorders and psychological factors; external factors include negative life events, family factors, social environment factors and cultural factors. Systematic intervention of Internet is used to establish an automatic identification and assessment of suicide ideation in social media, and a mental psychotherapy with many other psychotherapies. Through timely intervention and referral, systematic intervention and continuous care intervention process, social media users can eliminate suicide idea and reduce suicide probability. At present, researchers pay more attention to the development process and mechanism of suicidal behavior. In the future, it will be necessary to establish Internet suicide intervention system and study the effect of different psychological intervention on Internet suicide. &copy; 2019, Springer Nature Switzerland AG.</p