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41.
An immunodetection assay on Western blots has been used to determine the thiol proteinase content and composition in cysts from 12 populations of the brine shrimp Artemia. Our results showed no differences in the subunit composition of the thiol proteinase among cysts from eight bisexual strains and four parthenogenic strains, and confirmed an earlier finding that the proteinase is composed of two subunits of 25.9 and 31.5 kilodaltons. In contrast, we found that Artemia cysts from parthenogenic strains contain 17.1 ng/cyst of the thiol proteinase, while cysts from bisexual strains contain 8.2 ng/cyst of the thiol proteinase. Also, there was a good linear correlation (r = 0.863; p less than 0.001) between the thiol proteinase content and cyst mass. Embryo fractionation experiments showed that 82% of the thiol proteinase was in the cytosol, while 14 and 4%, respectively, were in the nuclei/yolk platelets and mitochondria/lysosome fractions. Measurements of the thiol proteinase content of developing Artemia embryos showed that the proteinase content was relatively constant during early development, suggesting that the activity of the thiol proteinase gene(s) may be constitutive and not developmentally regulated in Artemia embryos. 相似文献
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The lesions induced in Bacillus subtilis deoxyribonucleic acid (DNA) after treating bacterial cells (in vivo) and bacterial DNA (in vitro) with chloramine were studied biologically and physically. Single-strand breaks and a few double-strand scissions (at higher chloramine doses) accompanied loss of DNA-transforming activity in both kinds of treatments. Chloramine was about three times more efficient in vitro than in vivo in inducing DNA single-strand breaks. DNA was slowly chlorinated; the subsequent efficiency of producing DNA breaks was high. Chlorination of cells also reduced activity of endonucleases in cells; however, chlorinated DNA of both treatments was sensitized to cleavage by endonucleases. The procedure of extracting DNA from cells treated with chloramine induced further DNA degradation. Both treatments introduced a small fraction of alkali-sensitive lesions in DNA. DNA chlorinated in vitro showed further reduction in transforming activity as well as further degradation after incubation at 50 C for 5 h whereas DNA extracted from chloramine-treated cells did not show such a heat sensitivity. 相似文献
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Aaron Mendez-Bermudez Liudmyla Lototska Melanie Pousse Florent Tessier Oliver Croce Chrysa
M Latrick Veronica Cherdyntseva Joe Nassour Jiang Xiaohua Yiming Lu Corinne Abbadie Sarantis Gagos Jing Ye Eric Gilson 《Nucleic acids research》2022,50(13):7493
Cellular senescence triggers various types of heterochromatin remodeling that contribute to aging. However, the age-related mechanisms that lead to these epigenetic alterations remain elusive. Here, we asked how two key aging hallmarks, telomere shortening and constitutive heterochromatin loss, are mechanistically connected during senescence. We show that, at the onset of senescence, pericentromeric heterochromatin is specifically dismantled consisting of chromatin decondensation, accumulation of DNA breakages, illegitimate recombination and loss of DNA. This process is caused by telomere shortening or genotoxic stress by a sequence of events starting from TP53-dependent downregulation of the telomere protective protein TRF2. The resulting loss of TRF2 at pericentromeres triggers DNA breaks activating ATM, which in turn leads to heterochromatin decondensation by releasing KAP1 and Lamin B1, recombination and satellite DNA excision found in the cytosol associated with cGAS. This TP53–TRF2 axis activates the interferon response and the formation of chromosome rearrangements when the cells escape the senescent growth arrest. Overall, these results reveal the role of TP53 as pericentromeric disassembler and define the basic principles of how a TP53-dependent senescence inducer hierarchically leads to selective pericentromeric dismantling through the downregulation of TRF2. 相似文献
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Yu Shang Li Li Tengfei Zhang Qingping Luo Qingzhong Yu Zhe Zeng Lintao Li Miaomiao Jia Guoyi Tang Sanlin Fan Qin Lu Wenting Zhang Yuhan Xue Hongling Wang Wei Liu Hongcai Wang Rongrong Zhang Chan Ding Huabin Shao Guoyuan Wen 《PLoS pathogens》2022,18(6)
The development of thermostable vaccines can relieve the bottleneck of existing vaccines caused by thermal instability and subsequent poor efficacy, which is one of the predominant reasons for the millions of deaths caused by vaccine-preventable diseases. Research into the mechanism of viral thermostability may provide strategies for developing thermostable vaccines. Using Newcastle disease virus (NDV) as model, we identified the negative surface charge of attachment glycoprotein as a novel determinant of viral thermostability. It prevented the temperature-induced aggregation of glycoprotein and subsequent detachment from virion surface. Then structural stability of virion surface was improved and virus could bind to and infect cells efficiently after heat-treatment. Employing the approach of surface charge engineering, thermal stability of NDV and influenza A virus (IAV) vaccines was successfully improved. The increase in the level of vaccine thermal stability was determined by the value-added in the negative surface charge of the attachment glycoprotein. The engineered live and inactivated vaccines could be used efficiently after storage at 37°C for at least 10 and 60 days, respectively. Thus, our results revealed a novel surface-charge-mediated link between HN protein and NDV thermostability, which could be used to design thermal stable NDV and IAV vaccines rationally. 相似文献