Ciliate Ultrastructure: Some Problems in Cell Biology*

SYNOPSIS. Protozoology, along with other cell sciences, has profited immeasurably during the last 25 years from the application of electron microscopy and other new technics to studies of cell structure and function. Protozoa were among the first objects examined with the electron microscope in the 1940's and an extensive literature in protozoan ultrastructure has accumulated since then. Some examples of recent investigations of ciliate cortical ultrastructure are selected to illustrate the importance of protozoan studies to the development of fundamental concepts of cell biology. Ciliates are choice subjects for analysis of ciliary structure and motility and of myoneme contractility. Membrane-limited alveoli contribute to the structure of the characteristic ciliate pellicle and provide evidence of how multiple pellicular membranes may affect cell-surface activities. The striated fibrils and microtubules associated with ciliate kinetosomes resemble those of other cell types but are more highly organized; wherever they occur, these structures appear to be related to the development and maintenance of polarity and asymmetry of cells and organelles. Their stability and the precision of their arrangement in ciliates make them peculiarly suitable for the study of the properties and behavior of such fibrous organelles and also for investigation of the morphogenetic role of the kinetosome.     

复制衰老的分子生物学进展

对有关复制衰老分子生物学近年来的研究成果进行了综述,主要包括:1）复制衰老的特征及其与年龄衰老和肿瘤抑制的关系;2）Rb和p53基因及生长调节基因在复制衰老中的作用.     

The Virtual Cell Animation Collection: Tools for Teaching Molecular and Cellular Biology

A cell is a minifactory in which structures and molecules are assembled, rearranged, disassembled, packaged, sorted, and transported. Because cellular structures and molecules are invisible to the human eye, students often have difficulty conceptualizing the dynamic nature of cells that function at multiple scales across time and space. To represent these dynamic cellular processes, the Virtual Cell Productions team at North Dakota State University develops freely available multimedia materials to support molecular and cellular biology learning inside and outside the high school and university classroom.

This Education piece is part of the Education series.

     

沙冬青细胞与分子生物学研究进展

沙冬青是我国西北荒漠区唯一的常绿阔叶灌木,具有极强的抗逆性和特殊的医疗保健作用。本文从细胞学与遗传多样性、抗逆性分子基础与基因克隆和药用成分及作用机制方面对沙冬青的研究进展进行了综述,并提出了今后的重点研究方向。     

The Molecular Biology of Mammalian SIRT Proteins: SIRT2 Functions on Cell Cycle Regulation

Sir2, an NAD+-dependent protein deacetylase, extends the lifespan in diverse species from yeast to flies. Mammals have 7 homologues of Sir2, SIRT1-7, which affect aging and metabolism and which are potential targets for pharmacologic intervention. We identified SIRT2, which preferentially deacetylates tubulin and histone H4, as a down-regulated protein in gliomas due to its epigenetic aberration. We herein discuss the role of SIRT2 in the mitotic checkpoint function and show that it may be as a potential target of anti-cancer drugs.