[Objective] Mononychellus tanajoa is a mite speices recently invaded into China in 2008. Temperature is one of the most important ecological factors affecting the growth and reproduction of M. tanajoa. The objective o...[Objective] Mononychellus tanajoa is a mite speices recently invaded into China in 2008. Temperature is one of the most important ecological factors affecting the growth and reproduction of M. tanajoa. The objective of the current study was to reveal the effects of high temperature incubation on the activities of some protective enzymes in M. tanajoa at different growth stages. The results would contribute to the understanding of the adaptable distribution of M. tanajoa after its invasion into China, the mechanisms in its invasion, diffusion and ecological adaptation, and the monitor- ing, early warning and effective prevention of its damage. [Method] Six protective enzymes, Le. polyphenol oxidase （PPO）, peroxidase （POD）, ascorbate oxidase （AsA- POD）, catalase （CAT）, superoxide dismutase （SOD） and esterase （EST）, were cho- sen to study their activities after the mites at different growth stages were incubated at a extremely high temperature of 42 ~C for a certain period of time up to 24 h. The activities were measured by spectrophotometric endpoint assay method. [Results] Enzyme activities in M. tanajoa were affected by the high temperature incubation. However, differences in enzyme activity changes were found among different protec- tive enzymes and among different growth stages of M. tanajoa. Activities of PPO, POD, AsA-POD and CAT were significantly increased in the larval mites and female adult mites of M. tanajoa. CAT activity was significantly decreased in protonymph and deutonymph of M. tanajoa. Activities of PPO, POD and AsA-POD in protonymph and deutonymph showed no obvious difference from the control. [Conclusion] The activity changes of some protective enzymes in M. tanajoa following high-temperature treatment are part of its anti-stress reaction mechanism. In mite protonymph and deutonymph, activities of PPO, POD and AsA-POD are similar to the untreated con- trol which may be associated with the thermostability of M. tanajoa. It is concluded that, the long-time stress of extreme temperature may result in the increase of the thermostability of mite individuals, the enhancement of the population thermal stability and subsequently lead to rapid expansion of the population.展开更多
Objectives: To challenge the expiry dates of low concentration high purity mycotoxins standards. Literature Review: Aflatoxins (AFs) and Ochratoxin A (OTA) are persistent mycotoxins with adverse effects on humans. Myc...Objectives: To challenge the expiry dates of low concentration high purity mycotoxins standards. Literature Review: Aflatoxins (AFs) and Ochratoxin A (OTA) are persistent mycotoxins with adverse effects on humans. Mycotoxins standards are purchased to determine mycotoxin concentrations in food and may be stocked in some laboratories beyond expiry dates causing laboratories financial losses. Methods: Certified mycotoxins standards were purchased over the years from the same supplier at times and at other times from two different suppliers for quality control purposes. For AFs, six chromatographic runs for each of the mycotoxins standards were done to compare the difference among these standards having the following expiry dates (2008, 2012, 2013 and 2018). AFs standards purchased/obtained from two different suppliers in 2016 and expiring in 2018 were also compared. For OTA, the difference of concentration obtained between two years (2010 and 2018) was tested. All samples were run on a HPLC equipped with a fluorescence detector. Linearity of calibration curves and the points of lowest detection were determined for AFs components and for OTA from the unexpired mycotoxins standards. Results: At a 0.05 significance level and using non parametric tests, the statistical test revealed a p of 0.166, 0.153, 0.358 and 0.03 for B1, G1, B2 and G2 respectively among years for standards from same supplier and 0.037, 0.109, 0.182 and 0.182 for B1, G1, B2 and G2 respectively for unexpired standards from two different suppliers. For OTA, a p of 0.109 was obtained for standards of different expiry dates purchased from different suppliers. Conclusion: High purity low concentration mycotoxin standards purchased a decade ago (i.e. expired) did not differ from those purchased this current year (still valid). Hence, the expiry date can be renewed reducing the laboratories expenses. Manufacturers are urged to reconsider the expiry dates.展开更多
基金Supported by Special Fund for Cassava Technology System Fund (CARS-12-hncq)the Central-level Public Welfare Research Institutes for Basic R & D Operations (No.2011h-zs1J014,No.2009hzs1J013)+1 种基金Agricultural Public Welfare Industry-specific (200903034-5)Science and Technology Program Project of Hainan Province (ZDXM20100022,ZDXM20110032)~~
文摘[Objective] Mononychellus tanajoa is a mite speices recently invaded into China in 2008. Temperature is one of the most important ecological factors affecting the growth and reproduction of M. tanajoa. The objective of the current study was to reveal the effects of high temperature incubation on the activities of some protective enzymes in M. tanajoa at different growth stages. The results would contribute to the understanding of the adaptable distribution of M. tanajoa after its invasion into China, the mechanisms in its invasion, diffusion and ecological adaptation, and the monitor- ing, early warning and effective prevention of its damage. [Method] Six protective enzymes, Le. polyphenol oxidase （PPO）, peroxidase （POD）, ascorbate oxidase （AsA- POD）, catalase （CAT）, superoxide dismutase （SOD） and esterase （EST）, were cho- sen to study their activities after the mites at different growth stages were incubated at a extremely high temperature of 42 ~C for a certain period of time up to 24 h. The activities were measured by spectrophotometric endpoint assay method. [Results] Enzyme activities in M. tanajoa were affected by the high temperature incubation. However, differences in enzyme activity changes were found among different protec- tive enzymes and among different growth stages of M. tanajoa. Activities of PPO, POD, AsA-POD and CAT were significantly increased in the larval mites and female adult mites of M. tanajoa. CAT activity was significantly decreased in protonymph and deutonymph of M. tanajoa. Activities of PPO, POD and AsA-POD in protonymph and deutonymph showed no obvious difference from the control. [Conclusion] The activity changes of some protective enzymes in M. tanajoa following high-temperature treatment are part of its anti-stress reaction mechanism. In mite protonymph and deutonymph, activities of PPO, POD and AsA-POD are similar to the untreated con- trol which may be associated with the thermostability of M. tanajoa. It is concluded that, the long-time stress of extreme temperature may result in the increase of the thermostability of mite individuals, the enhancement of the population thermal stability and subsequently lead to rapid expansion of the population.
文摘Objectives: To challenge the expiry dates of low concentration high purity mycotoxins standards. Literature Review: Aflatoxins (AFs) and Ochratoxin A (OTA) are persistent mycotoxins with adverse effects on humans. Mycotoxins standards are purchased to determine mycotoxin concentrations in food and may be stocked in some laboratories beyond expiry dates causing laboratories financial losses. Methods: Certified mycotoxins standards were purchased over the years from the same supplier at times and at other times from two different suppliers for quality control purposes. For AFs, six chromatographic runs for each of the mycotoxins standards were done to compare the difference among these standards having the following expiry dates (2008, 2012, 2013 and 2018). AFs standards purchased/obtained from two different suppliers in 2016 and expiring in 2018 were also compared. For OTA, the difference of concentration obtained between two years (2010 and 2018) was tested. All samples were run on a HPLC equipped with a fluorescence detector. Linearity of calibration curves and the points of lowest detection were determined for AFs components and for OTA from the unexpired mycotoxins standards. Results: At a 0.05 significance level and using non parametric tests, the statistical test revealed a p of 0.166, 0.153, 0.358 and 0.03 for B1, G1, B2 and G2 respectively among years for standards from same supplier and 0.037, 0.109, 0.182 and 0.182 for B1, G1, B2 and G2 respectively for unexpired standards from two different suppliers. For OTA, a p of 0.109 was obtained for standards of different expiry dates purchased from different suppliers. Conclusion: High purity low concentration mycotoxin standards purchased a decade ago (i.e. expired) did not differ from those purchased this current year (still valid). Hence, the expiry date can be renewed reducing the laboratories expenses. Manufacturers are urged to reconsider the expiry dates.
