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534 results on '"Zhang, Mengli"'

30. HAD-GAN: A Human-perception Auxiliary Defense GAN to Defend Adversarial Examples

Author

Yu, Wanting, Yu, Hongyi, Jiang, Lingyun, Zhang, Mengli, and Qiao, Kai

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Machine Learning, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

Adversarial examples reveal the vulnerability and unexplained nature of neural networks. Studying the defense of adversarial examples is of considerable practical importance. Most adversarial examples that misclassify networks are often undetectable by humans. In this paper, we propose a defense model to train the classifier into a human-perception classification model with shape preference. The proposed model comprising a texture transfer network (TTN) and an auxiliary defense generative adversarial networks (GAN) is called Human-perception Auxiliary Defense GAN (HAD-GAN). The TTN is used to extend the texture samples of a clean image and helps classifiers focus on its shape. GAN is utilized to form a training framework for the model and generate the necessary images. A series of experiments conducted on MNIST, Fashion-MNIST and CIFAR10 show that the proposed model outperforms the state-of-the-art defense methods for network robustness. The model also demonstrates a significant improvement on defense capability of adversarial examples.

Published
2019

41. SIRT5 deficiency suppresses mitochondrial ATP production and promotes AMPK activation in response to energy stress.

Author

Zhang, Mengli, Wu, Jian, Sun, Renqiang, Tao, Xiaoting, Wang, Xiaoxia, Kang, Qi, Wang, Hui, Zhang, Lei, Liu, Peng, Zhang, Jinye, Xia, Yukun, Zhao, Yuzheng, Yang, Yi, Xiong, Yue, Guan, Kun-Liang, Zou, Yunzeng, and Ye, Dan

Subjects
Mitochondria, Heart, Animals, Mice, Knockout, Humans, Mice, Cardiomegaly, Sirtuins, Adenosine Triphosphate, Enzyme Activation, Stress, Physiological, AMP-Activated Protein Kinases, HEK293 Cells, Knockout, Mitochondria, Heart, Stress, Physiological, General Science & Technology
Abstract

Sirtuin 5 (SIRT5) is a member of the NAD+-dependent sirtuin family of protein deacylase that catalyzes removal of post-translational modifications, such as succinylation, malonylation, and glutarylation on lysine residues. In light of the SIRT5's roles in regulating mitochondrion function, we show here that SIRT5 deficiency leads to suppression of mitochondrial NADH oxidation and inhibition of ATP synthase activity. As a result, SIRT5 deficiency decreases mitochondrial ATP production, increases AMP/ATP ratio, and subsequently activates AMP-activated protein kinase (AMPK) in cultured cells and mouse hearts under energy stress conditions. Moreover, Sirt5 knockout attenuates transverse aortic constriction (TAC)-induced cardiac hypertrophy and cardiac dysfunction in mice, which is associated with decreased ATP level, increased AMP/ATP ratio and enhanced AMPK activation. Our study thus uncovers an important role of SIRT5 in regulating cellular energy metabolism and AMPK activation in response to energy stress.

Published
2019

48. Functional Diversity and Engineering of the Adenylation Domains in Nonribosomal Peptide Synthetases.

Author

Zhang, Mengli, Peng, Zijing, Huang, Zhenkuai, Fang, Jiaqi, Li, Xinhai, and Qiu, Xiaoting

Abstract

Nonribosomal peptides (NRPs) are biosynthesized by nonribosomal peptide synthetases (NRPSs) and are widely distributed in both terrestrial and marine organisms. Many NRPs and their analogs are biologically active and serve as therapeutic agents. The adenylation (A) domain is a key catalytic domain that primarily controls the sequence of a product during the assembling of NRPs and thus plays a predominant role in the structural diversity of NRPs. Engineering of the A domain to alter substrate specificity is a potential strategy for obtaining novel NRPs for pharmaceutical studies. On the basis of introducing the catalytic mechanism and multiple functions of the A domains, this article systematically describes several representative NRPS engineering strategies targeting the A domain, including mutagenesis of substrate-specificity codes, substitution of condensation-adenylation bidomains, the entire A domain or its subdomains, domain insertion, and whole-module rearrangements. [ABSTRACT FROM AUTHOR]

Published
2024
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