Centrosome-dependent exit of cytokinesis in animal cells

As an organelle coupling nuclear and cytoplasmic divisions, the centrosome is essential to mitotic fidelity, and its inheritance could be critical to understanding cell transformation. Investigating the behavior of the centrosome in living mitotic cells, we documented a transient and remarkable postanaphase repositioning of this organelle, which apparently controls the release of central microtubules from the midbody and the completion of cell division. We also observed that the absence of the centrosome leads to defects in cytokinesis. Together with recent results in yeasts, our data point to a conserved centrosome-dependent pathway that integrates spatial controls into the decision of completing cell division, which requires the repositioning of the centrosome organelle.     

Defining lipid transport pathways in animal cells

A new technique for studying the metabolism and intracellular transport of lipid molecules in living cells based on the use of fluorescent lipid analogs is described. The cellular processing of various intermediates (phosphatidic acid and ceramide) and end products (phosphatidylcholine and phosphatidylethanolamine) in lipid biosynthesis is reviewed and a working model for compartmentalization during lipid biosynthesis is presented.     

How viruses enter animal cells

Viruses replicate within living cells and use the cellular machinery for the synthesis of their genome and other components. To gain access, they have evolved a variety of elegant mechanisms to deliver their genes and accessory proteins into the host cell. Many animal viruses take advantage of endocytic pathways and rely on the cell to guide them through a complex entry and uncoating program. In the dialogue between the cell and the intruder, the cell provides critical cues that allow the virus to undergo molecular transformations that lead to successful internalization, intra-cellular transport, and uncoating.     

Immobilization of animal cells in microgranules and microcapsules

The methods of animal cell immobilization in chitozan microcapsules and alginate polyethylene glycol microgranules and their in vitro maintenance are presented. Hybridoma SS-3 cells remained viable for at least 20 days and capable of producing IgG immunoglobulins, which penetrate through an alginate-chitosan membrane.     

Virus-directed protein synthesis in different animal and human cells

The relative proportions of viral gene products (viral proteins) that are synthesized in different types of animal cells infected with the same RNA virus inoculum were compared. The relative rates of synthesis of the various virus proteins late in infection were remarkably constant regardless of cell type infected. This was true in cell lines that produced only small amounts of virus and virus proteins, as well as in those that gave large yields of viruses and virus proteins.     

动物细胞大规模培养技术研究进展

利用动物细胞大规模培养技术可生产多种生物制品,为提高细胞活力和细胞生长密度,采用有多种添加成分的无血清培养基培养细胞,选择既有利于细胞生长又可提高培养细胞密度的微载体和条件温和、易操作、气体交换速度快的生物反应器,在线监控细胞生存环境和生理活动,减少培养过程中培养基的抑制因素,从而给细胞提供更好的生存环境;另外通过向细胞中导入抗凋亡基因,可减缓细胞凋亡的发生,提高细胞活性和蛋白产量;此外,在动物细胞大规模培养过程中,利用多孔微载体能高效、大量地增殖细胞,具有良好的应用前景.     

猪口蹄疫病毒对三种动物细胞嗜性的研究

将猪FMDV毒株(O/GD/MSH/86)分别适应牛肾细胞(Bovinekidney,MD-BK)、幼仓鼠肾细胞(Babyhamsterkidney,BHK-21)和猪肾细胞(Porcinekidney,PK-15),研究了FMDV在宿主细胞上的嗜性。结果发现,该毒株在MD-BK细胞上不产生细胞病变(CPE),从细胞液中也未检测到病毒,而在BHK-21和PK-15细胞上能够稳定产生CPE。可见,猪FMDVO/GD/MSH/86毒株不能在MD-BK细胞上增殖,而在BHK-21和PK-15细胞上则增殖较好。     

Establishment of four functional, clonal strains of animal cells in culture

The single-cell plating technique was used to develop four clonal cell lines that perform organ-specific functions after being serially cultured for prolonged periods. These strains include steroid-secreting Leydig cells, melanomacells that form pigment, and two strains from a hormone-secreting rat pituitary tumor. One of the cell lines from the pituitary tumor secretes growt hormone, while another line derived from the same tumor secretes a substance similar to adrenocorticotropic hormone.     

Eimeria tenella: cultivation of the asexual stages in cultured animal cells

Eimeria tenella, an intracellular protozoan parasite of the cecal epithelium of chickens, developed asexually in monolayer cultures of mammalian fibroblasts, mammalian epithelial cells, and avian fibroblasts mintained under various mediums at 41 degrees C. Sexual stages of the parasite were not seen. Established cell lines and secondary cell cultures were equally suitable for cultivation of the parasite.     

Cortical unit activity in desynchronized sleep

Bursts of unit firing associated with surface positive electroencephalogram waves and rapid eye movements account for the mean increase in discharge rate in desynchronized sleep over that of the synchronized phase. Firing rate begins to change toward the value it will assume in desynchronized sleep in the minute before the usual electrographic criteria of desynchronized sleep are present.     

Quantitative imaging of nitrogen fixation by individual bacteria within animal cells

Biological nitrogen fixation, the conversion of atmospheric nitrogen to ammonia for biosynthesis, is exclusively performed by a few bacteria and archaea. Despite the essential importance of biological nitrogen fixation, it has been impossible to quantify the incorporation of nitrogen by individual bacteria or to map the fate of fixed nitrogen in host cells. In this study, with multi-isotope imaging mass spectrometry we directly imaged and measured nitrogen fixation by individual bacteria within eukaryotic host cells and demonstrated that fixed nitrogen is used for host metabolism. This approach introduces a powerful way to study microbes and global nutrient cycles.     

Partitioning of the matrix fraction of the Golgi apparatus during mitosis in animal cells

The Golgi apparatus is partitioned during mitosis in animal cells by a process of fragmentation, dispersal, and reassembly in each daughter cell. We fractionated the Golgi apparatus in vivo using the drug brefeldin A or a dominant-negative mutant of the Sar1p protein. After these treatments, Golgi enzymes moved back to the endoplasmic reticulum, leaving behind a matrix of Golgi structural proteins. Under these conditions, cells still entered and exited mitosis normally, and their Golgi matrix partitioned in a manner very similar to that of the complete organelle. Thus, the matrix may be the partitioning unit of the Golgi apparatus and may carry the Golgi enzyme-containing membranes into the daughter cells.     

Cortical correlated of auditory localization

Responses were recorded simultaneously from a number of electrodes on the auditory cortex of one hemisphere of cats. Response amplitudes at different electrodes reached maxima and minima at different real or apparent locations of a click stimulus.     

Cortical mechanisms of human imitation

How does imitation occur? How can the motor plans necessary for imitating an action derive from the observation of that action? Imitation may be based on a mechanism directly matching the observed action onto an internal motor representation of that action ("direct matching hypothesis"). To test this hypothesis, normal human participants were asked to observe and imitate a finger movement and to perform the same movement after spatial or symbolic cues. Brain activity was measured with functional magnetic resonance imaging. If the direct matching hypothesis is correct, there should be areas that become active during finger movement, regardless of how it is evoked, and their activation should increase when the same movement is elicited by the observation of an identical movement made by another individual. Two areas with these properties were found in the left inferior frontal cortex (opercular region) and the rostral-most region of the right superior parietal lobule.     

Evaluation of the methods for studying interactions between bacterial and animal cells

This paper presents the results of a comparative evaluation of methods for studying interactions between bacterial cells and erythrocytes, as well as a sample preparation procedure which makes it possible to study cell structure without any disturbances of the natural architectonics.