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41.
The effects of thyroid hormone and growth hormone on microsomal testosterone 7 alpha-hydroxylase, P-450a, were studied to understand the interaction of these hormone-mediated regulations in rats. In Western blots using anti-P-450a IgG, 1.7-fold higher content of P-450a was observed in livers of female than male adult rats, while no appreciable sex-related difference was detected in prepubertal rats and rats of 24 months of age. Treatment with n-propyl-2-thiouracil or thyroidectomy of male rats increased by 2-fold the hepatic content of P-450a, but neither regimen had a significant effect on the content in female rats. Levels of P-450a in both sexes of thyroidectomized rats were decreased by the supplementation of triiodothyronine (T3, 50 micrograms per kg, i.p. for 7 days) to levels similar to that observed in normal male rats. Hypophysectomy also caused an increase in microsomal P-450a content in male rats. Continuous infusion of human growth hormone, which mimicked the female secretion, further significantly increased the content in hypophysectomized rats to a level similar to that observed in normal female rats. In contrast, hepatic level of P-450a in hypophysectomized male and female rats was reduced by intermittent injection, which mimicked the male secretion. Clear suppression on the level of hepatic P-450a was also observed by the treatment of hypophysectomized rats with 5 or 50 micrograms/kg of T3 and of hGH-infused hypophysectomized rat with 50 micrograms/kg of T3.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
42.
Nitrogen control of Salmonella typhimurium: co-regulation of synthesis of glutamine synthetase and amino acid transport systems. 总被引:22,自引:9,他引:13 下载免费PDF全文
Nitrogen control in Salmonella typhimurium is not limited to glutamine synthetase but affects, in addition, transport systems for histidine, glutamine, lysine-arginine-ornithine, and glutamate-aspartate. Synthesis of both glutamine synthetase and transport proteins is elevated by limitation of nitrogen in the growth medium or as a result of nitrogen (N)-regulatory mutations. Increases in the amounts of these proteins were demonstrated by direct measurements of their activities, by immunological techniques, and by visual inspection of cell fractions after gel electrophoresis. The N-regulatory mutations are closely linked on the chromosome to the structural gene for glutamine synthetase, glnA: we discuss the possibility that they lie in a regulatory gene, glnR, which is distinct from glnA. Increases in amino acid transport in N-regulatory mutant strains were indicated by increased activity in direct transport assays, improved growth on substrates of the transport systems, and increased sensitivity to inhibitory analogs that are trnasported by these systems. Mutations to loss of function of individual transport components (hisJ, hisP, glnH, argT) were introduced into N-regulatory mutant strains to determine the roles of these components in the phenotype and transport behavior of the strains. The structural gene for the periplasmic glutamine-binding protein, glnH, was identified, as was a gene argT that probably encodes the structure of the lysine-arginine-ornithine-binding protein. Genes encoding the structures of the histidine- and glutamine-binding proteins are not linked to glnA or to each other by P22-mediated transduction; thus, nitrogen control is exerted on several unlinked genes. 相似文献
43.
Weixiao Lei Zefu Wang Man Cao Hui Zhu Min Wang Yi Zou Yunchun Han Dandan Wang Zeyu Zheng Ying Li Bingbing Liu Dafu Ru 《DNA research》2022,29(3)
Sophora japonica is a medium-size deciduous tree belonging to Leguminosae family and famous for its high ecological, economic and medicinal value. Here, we reveal a draft genome of S. japonica, which was ∼511.49 Mb long (contig N50 size of 17.34 Mb) based on Illumina, Nanopore and Hi-C data. We reliably assembled 110 contigs into 14 chromosomes, representing 91.62% of the total genome, with an improved N50 size of 31.32 Mb based on Hi-C data. Further investigation identified 271.76 Mb (53.13%) of repetitive sequences and 31,000 protein-coding genes, of which 30,721 (99.1%) were functionally annotated. Phylogenetic analysis indicates that S. japonica separated from Arabidopsis thaliana and Glycine max ∼107.53 and 61.24 million years ago, respectively. We detected evidence of species-specific and common-legume whole-genome duplication events in S. japonica. We further found that multiple TF families (e.g. BBX and PAL) have expanded in S. japonica, which might have led to its enhanced tolerance to abiotic stress. In addition, S. japonica harbours more genes involved in the lignin and cellulose biosynthesis pathways than the other two species. Finally, population genomic analyses revealed no obvious differentiation among geographical groups and the effective population size continuously declined since 2 Ma. Our genomic data provide a powerful comparative framework to study the adaptation, evolution and active ingredients biosynthesis in S. japonica. More importantly, our high-quality S. japonica genome is important for elucidating the biosynthesis of its main bioactive components, and improving its production and/or processing. 相似文献
44.
Lei Deng Yunyun Zeng Hui Liu Zixuan Liu Xuejun Liu 《Current issues in molecular biology》2022,44(5):2287
Drug-target interactions provide insight into the drug-side effects and drug repositioning. However, wet-lab biochemical experiments are time-consuming and labor-intensive, and are insufficient to meet the pressing demand for drug research and development. With the rapid advancement of deep learning, computational methods are increasingly applied to screen drug-target interactions. Many methods consider this problem as a binary classification task (binding or not), but ignore the quantitative binding affinity. In this paper, we propose a new end-to-end deep learning method called DeepMHADTA, which uses the multi-head self-attention mechanism in a deep residual network to predict drug-target binding affinity. On two benchmark datasets, our method outperformed several current state-of-the-art methods in terms of multiple performance measures, including mean square error (MSE), consistency index (CI), , and PR curve area (AUPR). The results demonstrated that our method achieved better performance in predicting the drug–target binding affinity. 相似文献
45.
QuangMinh Nguyen Arya Bagus Boedi Iswanto Geon Hui Son Uyen Thi Vuong Jihyun Lee JinHo Kang Walter Gassmann Sang Hee Kim 《Molecular Plant Pathology》2022,23(9):1390
During pathogenesis, effector proteins are secreted from the pathogen to the host plant to provide virulence activity for invasion of the host. However, once the host plant recognizes one of the delivered effectors, effector‐triggered immunity activates a robust immune and hypersensitive response (HR). In planta, the effector AvrRps4 is processed into the N‐terminus (AvrRps4N) and the C‐terminus (AvrRps4C). AvrRps4C is sufficient to trigger HR in turnip and activate AtRRS1/AtRPS4‐mediated immunity in Arabidopsis; on the other hand, AvrRps4N induces HR in lettuce. Furthermore, AvrRps4N‐mediated HR requires a conserved arginine at position 112 (R112), which is also important for full‐length AvrRps4 (AvrRps4F) processing. Here, we show that effector processing and effector recognition in lettuce are uncoupled for the AvrRps4 family. In addition, we compared effector recognition by lettuce of AvrRps4 and its homologues, HopK1 and XopO. Interestingly, unlike for AvrRps4 and HopK1, mutation of the conserved R111 in XopO by itself was insufficient to abolish recognition. The combination of amino acid substitutions arginine 111 to leucine with glutamate 114 to lysine abolished the XopO‐mediated HR, suggesting that AvrRps4 family members have distinct structural requirements for perception by lettuce. Together, our results provide an insight into the processing and recognition of AvrRps4 and its homologues. 相似文献
46.
Bingqing Xia Xurui Shen Yang He Xiaoyan Pan Feng-Liang Liu Yi Wang Feipu Yang Sui Fang Yan Wu Zilei Duan Xiaoli Zuo Zhuqing Xie Xiangrui Jiang Ling Xu Hao Chi Shuangqu Li Qian Meng Hu Zhou Yubo Zhou Xi Cheng Xiaoming Xin Lin Jin Hai-Lin Zhang Dan-Dan Yu Ming-Hua Li Xiao-Li Feng Jiekai Chen Hualiang Jiang Gengfu Xiao Yong-Tang Zheng Lei-Ke Zhang Jingshan Shen Jia Li Zhaobing Gao 《Cell research》2021,31(8):847-860
Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology 相似文献
47.
肉毒毒素(botulinum neurotoxin, BoNT)是人类已知毒性最强的蛋白质之一,可以引起肌肉松弛麻痹,严重时可导致死亡。肉毒毒素共分为7种血清型(BoNT/A-BoNT/G),根据氨基酸序列差异可进一步分为40多种亚型。肉毒毒素分子结构由3个基本结构域组成:重链羧基端细胞受体结合域、氨基端的易位域和轻链催化域。在运动神经元表面,受体结合域首先与聚唾液酸神经节苷脂结合,随后与突触囊泡蛋白2或突触囊泡结合蛋白结合形成双受体复合物。每种血清型的受体结合域都必须与其相应受体结合才能发挥作用。肉毒毒素的结构功能及其对宿主的作用一直都是研究热点。近年来,因受体结合域可以促进肉毒毒素与运动神经元膜特异性结合,而成为新的研究方向。本综述将概述不同血清型肉毒毒素与受体结合过程中受体结合域结构变化和结合位点差异。通过分析不同血清型及亚型的序列以及受体结合域结构特征,可以更好地了解细胞受体结合域的序列差异和功能,并为肉毒毒素的治疗策略提供新思路。 相似文献
48.
49.
从研究生"高级微生物学"课程的定位、研究生学习该课程的目的、知识背景差异及教学过程中的问题等方面分析了目前研究生"高级微生物学"教学中存在的问题。通过教学内容的优化、教材建设、教学方法改革、师资队伍建设以及建立师生交流平台等方面进行教学改革实践,取得了较好的教学效果。 相似文献
50.