Crossing the nuclear envelope: hierarchical regulation of nucleocytoplasmic transport

Transport of macromolecules between the nucleus and cytoplasm is a critical cellular process for eukaryotes, and the machinery that mediates nucleocytoplasmic exchange is subject to multiple levels of control. Regulation is achieved by modulating the expression or function of single cargoes, transport receptors, or the transport channel. Each of these mechanisms has increasingly broad impacts on transport patterns and capacity, and this hierarchy of control directly affects gene expression, signal transduction, development, and disease.     

Nuclear pores form de novo from both sides of the nuclear envelope

Nuclear pore complexes are multiprotein channels that span the double lipid bilayer of the nuclear envelope. How new pores are inserted into the intact nuclear envelope of proliferating and differentiating eukaryotic cells is unknown. We found that the Nup107-160 complex was incorporated into assembly sites in the nuclear envelope from both the nucleoplasmic and the cytoplasmic sides. Nuclear pore insertion required the generation of Ran guanosine triphosphate in the nuclear and cytoplasmic compartments. Newly formed nuclear pore complexes did not contain structural components of preexisting pores, suggesting that they can form de novo.     

Chromatin-independent nuclear envelope assembly induced by Ran GTPase in Xenopus egg extracts

The nuclear envelope (NE) forms a controlled boundary between the cytoplasm and the nucleus of eukaryotic cells. To facilitate investigation of mechanisms controlling NE assembly, we developed a cell-free system made from Xenopus laevis eggs to study the process in the absence of chromatin. NEs incorporating nuclear pores were assembled around beads coated with the guanosine triphosphatase Ran, forming pseudo-nuclei that actively imported nuclear proteins. NE assembly required the cycling of guanine nucleotides on Ran and was promoted by RCC1, a nucleotide exchange factor recruited to beads by Ran-guanosine diphosphate (Ran-GDP). Thus, concentration of Ran-GDP followed by generation of Ran-GTP is sufficient to induce NE assembly.     

Role of delayed nuclear envelope breakdown and mitosis in Wolbachia-induced cytoplasmic incompatibility

The bacterium Wolbachia manipulates reproduction in millions of insects worldwide; the most common effect is cytoplasmic incompatibility (CI). We found that CI resulted from delayed nuclear envelope breakdown of the male pronucleus in Nasonia vitripennis. This caused asynchrony between the male and female pronuclei and, ultimately, loss of paternal chromosomes at the first mitosis. When Wolbachia were present in the egg, synchrony was restored, which explains suppression of CI in these crosses. These results suggest that Wolbachia target cell cycle regulatory proteins. A striking consequence of CI is that it alters the normal pattern of reciprocal centrosome inheritance in Nasonia.     

试论生态农业的边界与科学技术原理

由于生态农业概念模糊,加之边界不清,生态学界对生态农业科学原理与技术总结不够,公众对生态农业理解有误,阻碍了生态农业产业发展。本研究通过总结、归纳和分析1982—2022年发表的相关文献,回顾了国内外生态农业提出的背景及其含义,分析了现代农业的9种主要形态及其特征,重新定义了生态农业的概念,厘清了生态农业的边界,提出了指导生态农业发展的理论体系与科学技术原理。并以山东省平邑县弘毅生态农场18年实践为例,实证了本研究提出的生态农业概念、理论与技术体系具有重要的应用与推广价值。     

黄河内蒙古河段冰凌研究与冰凌预报数据库系统的设计

在Ｗｉｎｄｏｗｓ操作平台上使用ＰｏｗｅｒＢｕｉｌｄｅrＶＢ编程语言设计黄河内蒙古河段冰凌研究与冰凌预报数据库系统的准则，功能及组成。该设计考虑了系统数据量大以及存储，查询等需求和系统升级的要求；系统具有数据间相互关系简单，层次少，能生成多种表格等特点。     

Unique envelope of a jellyfish ovum: the armed egg

The eggs of Bougainvillia multitentaculata are spawned with an envelope consisting of a single layer of cnidocvtes. The cnidocytes are surficial On eggs, cleavage stages, and young blastulae. During gastrulation, the cnidocytes are Incorporated intO the ectoderm and become an integral part of the planula.     

Particle nucleation in the tropical boundary layer and its coupling to marine sulfur sources

New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.