Research on Practice Problems and Strategies for Professional Master's Degree Candidates for Agriculture

Taking the practice status of professional master’s degree candidates for agriculture in Anhui Agricultural University as an example,this paper analyzes the key factors affecting the practical training of graduate students in this major,and puts forward some strategies for improving the practice quality of professional master’s degree candidates.In terms of training professional master’s degree candidates,it is considered that agricultural colleges and universities should start with collaborative education,supervision and assessment mechanism,practice content and form,make full use of a large number of agricultural enterprise resources owned by colleges and universities and a good cooperation foundation in enterprises,so as to achieve the purpose of improving the practice quality of professional master’s degree candidates.

Regulation of protein thermal stability and its potential application in the development of thermo-attenuated vaccines

The coronavirus disease 2019(COVID-19)pandemic has highlighted the importance of developing novel vaccines.An ideal vaccine should trigger an intense immune reaction without causing significant side effects.In this study we found that substitution of tryptophan located in the cores of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)protein structures with certain smaller amino acids resulted in variants with melting temperatures of 33-37℃.An enzyme activity assay indicated that the proteolytic activity of the main proteinase(3CLpro)decreased sharply when the environmental temperature exceeded the melting temperature,implying that other protein variants may lose most of their functions under the same conditions.This finding suggests that a virus variant containing engineered proteins with melting temperatures of 33-37℃ may only be functional in the upper respiratory tract where the temperature is about 33℃,but will be unable to invade internal organs,which maintain temperatures above 37℃,thus making it possible to construct temperature-sensitive attenuated vaccines.

Tea picking point detection and location based on Mask-RCNN

The accurate identification,detection,and segmentation of tea buds and leaves are important factors for realizing intelligent tea picking.A tea picking point location method based on the region-based convolutional neural network(R-CNN)Mask-RCNN is proposed,and a tea bud and leaf and picking point recognition model is established.First,tea buds and leaf pictures are collected in a complex environment,the Resnet50 residual network and a feature pyramid network(FPN)are used to extract bud and leaf features,and preliminary classification and preselection box regression training-performed on the feature maps through a regional proposal network(RPN).Second,the regional feature aggregation method(RoIAlign)is used to eliminate the quantization error,and the feature map of the preselected region of interest(ROI)is converted into a fixed-size feature map.The output module of the model realizes the functions of classification,regression and segmentation.Finally,through the output mask image and the positioning algorithm the positioning of the picking points of tea buds and leaves is determined.One hundred tea tree bud and leaf pictures in a complex environment are selected for testing.The experimental results show that the average detection accuracy rate reaches 93.95%and that the recall rate reaches 92.48%.The tea picking location method presented in this paper is more versatile and robust in complex environments.

The PilZ domain of MrkH represents a nove ）NA binding motif

MrkH is the first characterized c-di-GMP related transcrip- tional regulator which affects type 3 fimbrial expression in response to cellular c-di-GMP level, and thus plays an important role in the biofilm formation of Klebsiella pneu- moniae （Murphy and Clegg, 2012; Wilksch et al., 2011）. However, how MrkH recognizes c-di-GMP and the target DNA sequence remains obscure.