Morphology,cell-cell interactions,and migratory activity of IAR-2 epithelial cells transformed with the <Emphasis Type="Italic">RAS</Emphasis> oncogene: Contribution of cell adhesion protein E-Cadherin

The destruction of stable cell-cell adhesion and the acquisition of the ability to migrate are consistent stages of neoplastic evolution of tumor cells of epithelial origin. We studied the morphological and migration characteristics of epithelial cells of IAR1162 and IAR1170 clones derived from a mixed culture of N-RasV12 oncogene-transformed IAR-2 cell line. It was found that the oncogenic RAS can cause two types of morphological changes in IAR-2 epithelial cells. Cells of one type (IAR1162 clones) underwent epithelial-mesenchymal transition: they stopped to express E-cadherin, acquired fibroblast-like morphology, and did not form tight junctions. Cells of the other type (IAR1170 clones) retained a morphology close to the morphology of nontransformed progenitor cells, assembled E-cadherin-based adherens junctions and tight junctions, and formed a monolayer in confluent culture. However, in both IAR1162 and IAR1170 cells, the oncogenic RAS caused the destruction of marginal actin bundle and the reorganization of cell-cell adherens junctions. RAS-transformed IAR1162 and IAR1170 epithelial cells acquired the ability to migrate on a flat substrate as well as through narrow pores in membranes of migration chambers. A videomicroscopic study of transformed epithelial cell cultures demonstrated the instability of cell-cell contacts and the independent nature of cell migration. IAR1170 epithelial cells, which had E-cadherin-based adherens junctions, were also able to move as a group (collective migration). 1162D3 cells, which lost the ability to express endogenous E-cadherin as a result of Ras-transformation, were transfected with a plasmid carrying the CDH1. As a result of transfection, clones of cells with different levels of expression of exogenous E-cadherin were obtained. The high level of expression of exogenous E-cadherin in transformed epithelial cells led to a decrease in the rate of migration on a two-dimensional substrate of the cells that were in contact with neighboring cells but almost had no effect on the migration of single cells, at the same time increasing the number of cells that migrated through the pores in migration chambers. Thus, the destruction of marginal actin bundle and the change in the spatial organization of cell-cell adherens junctions, irrespective of the presence or absence of E-cadherin, was accompanied by destruction of stable cell-cell adhesion and the appearance of cell motility in Ras-transformed epithelial cells. The retaining of E-cadherin in cell-cell adhesion junctions affects the motility of transformed epithelial cells and plays an important role in their collective migration.     

Gold nanoparticles disturb nuclear chromatin decondensation in mouse sperm in vitro

The effect of gold nanoparticles on mouse epididymal sperm has been studied using the model system of nuclear chromatin decondensation in vitro. It is shown that the treatment of gametes, preliminary membrane-freed by sodium dodecyl sulfate, in the mediums containing gold nanoparticles (with diameter ∼2.5 nm) in concentrations 1.0 × 10¹⁵ or 0.5 × 10¹⁵ particles/ml and following incubation in dithiothreitol solution (DTT) resulted in failure of chromatin decondensation process and nucleus structure. We conclude that gold nanoparticles possess spermatotoxicity. The mechanism of cytotoxic effect of gold nanoparticles may be related with their interaction with molecules of double-helix DNA. The model system studied in this research is applicable for further investigations of cytotoxic effects of nanoparticles of different origin and made of different metals.     

Community of aquatic insects in forest-steppe lakes of Baraba (<Emphasis Type="Italic">South of West Siberia</Emphasis>)

This paper gives unique data on the ecology of aquatic insects inhabiting lakes in the Baraba forest-steppe region of West Siberia, where the lakeside zone is represented by thick reeds. It is shown that reeds, along with other lake biotopes, are an optimal habitat for many hydrobionts and especially for larvae of the orders Odonata and Diptera.     

An improved flat embedding technique for immunoelectron microscopy

Immunocytochemical staining has been widely used for localizing various hormonal antigens, protein markers and putative neurotransmitters in tissues. Immunostained sections can be examined light microscopically and specific areas selected for electron microscopic study.     

不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响

为了揭示退化高寒草甸逆向转变的驱动因子，通过野外调查和室内分析相结合的方法探究了黄河源不同修复措施（施有机肥F、免耕补播N、施有机肥+免耕补播FN）处理高寒草甸植物群落特征、土壤理化性质和两者相关性的变化规律，阐明不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响。结果表明：免耕补播显著增加草甸物种丰富度指数（P<0.05）；施有机肥+免耕补播显著增加草甸植物盖度、总生物量、Shannon Wiener多样性指数和Pielous均匀度指数（P<0.05）。不同人工修复后草甸植物功能群地上、地下生物量变化趋势基本一致（除豆科）。和对照相比，莎草科，杂类草地上和地下生物量含量在N、FN处理分别降低83.04%、73.86%、30.43%、92.37%和96.51%、84.09%、85.68%、95.36%；禾本科地上和地下生物量含量在F、N和FN处理分别增加7.29%、23.45%、17.93%和6.04%、4.03%、10.52%；豆科地上生物量含量基本保持不变，地下生物量含量在F、N和FN处理分别降低24.43%、82.19%和42.61%。F显著增加土壤有机碳含量（P=0.033）；N显著降低土壤NO₃^--N含量（P=0.009）；FN显著降低土壤pH和增加土壤速效磷含量（P=0.024）；F和FN显著增加土壤含水量（P=0.000），N则显著降低土壤含水量（P=0.000）；F显著降低土壤容重（P=0.018）。相关性分析表明植物Shannon Wiener多样性和Pielous均匀度与土壤速效磷含量呈显著正相关（P=0.037；P=0.033），土壤有机碳和含水量与总生物量呈显著正相关（P=0.027；P=0.032），pH与盖度呈显著负相关（P=0.049）。冗余度分析结果表明土壤有机碳含量和含水量显著影响了植物群落结构特征，解释率分别为30.3%和19.7%。研究结果表明，因地制宜进行退化高寒草甸施有机肥+免耕补播修复措施，能够明显提高草地生产力，改善草甸植物群落及其土壤养分和水分环境。     

严重急性呼吸综合征冠状病毒2膜蛋白对宿主细胞pre-mRNA 3"UTR加工的影响

目的 研究严重急性呼吸综合征冠状病毒2（SARS-CoV-2）膜蛋白对宿主细胞mRNA前体（pre-mRNA）3"非翻译区（UTR）加工的影响。方法 本研究以人肺上皮细胞系A549为模型，利用瞬时转染在细胞内过表达SARS-CoV-2膜蛋白；利用RNA-Seq测序技术及生物信息学分析方法，系统性描绘宿主细胞选择性多聚腺苷酸化（alternative polyadenylation，APA）事件；Metascape数据库对发生显著APA变化的基因进行功能富集分析；RT-qPCR验证靶基因3"UTR长度变化；蛋白质免疫印迹（Western blot）检测目的蛋白表达水平。结果 SARS-CoV-2膜蛋白外源表达后宿主细胞内共813个基因发生显著APA变化。GO和KEGG分析显示，差异APA基因广泛参与有丝分裂细胞周期、调节细胞应激等生物过程，涉及病毒感染和蛋白质加工等。从中进一步筛选出AKT1基因，在IGV软件中显示3"UTR延长；RT-qPCR验证AKT1基因的3"UTR长度变化趋势；Western blot结果显示AKT1蛋白磷酸化水平增加。结论 SARS-CoV-2膜蛋白潜在影响宿主pre-mRNA的3"UTR加工，其中参与多种病毒性生物过程的AKT1基因 3"UTR延长，且其编码的蛋白质功能在细胞内被激活。     

The Structural Organization of the HMGB1 Nuclear Protein and Its Effect on the Formation of Ordered Supramolecular Complexes

Biophysics - HMGB1 is one of the key proteins of the cell. HMGB1 performs its main functions predominantly in the cell nucleus, as an essential component of DNA–protein and multiprotein...