Establishing New Sites of Polarization by Microtubules

SummaryBackgroundMicrotubules (MTs) participate in the spatial regulation of actin-based processes such as cytokinesis and cell polarization [1]. The fission yeast Schizosaccharomyces pombe is a rod-shaped cell that exhibits polarized cell growth at cell tips. MT plus ends contact and shrink from the cell tips and contribute to polarity regulation.ResultsHere, we investigate the effects of changing cell shape on MTs and cell-polarization machinery. We physically bend fission yeast cells by forcing them into microfabricated femtoliter chambers. In these bent cells, MTs maintain a straight axis and contact and shrink from cortical sites at the sides of cells. At these ectopic sites, polarity factors such as bud6p, for3p (formin), and cdc42p are recruited and assemble actin cables in a MT-dependent manner. MT contact at the cortex induces the appearance of a bud6p dot within seconds. The accumulation of polarity factors leads to cell growth at these sites, when the MT-associated polarity factor tea1p is absent. This process is dependent on MTs, mal3p (EB1), moe1p (an EB1-binding protein), and for3p but, surprisingly, is independent of the tea1p-tea4p pathway.ConclusionsThese studies provide a direct demonstration for how MTs induce actin assembly at specific locations on the cell cortex and begin to identify a new pathway involved in this process. MT interactions with the cortex may be regulated by cortical-attachment sites. These findings highlight the crosstalk between cell shape, polarity mechanisms, and MTs responsible for cell morphogenesis

Формування передумов соціально-політичних конфліктів в українському суспільстві періоду трансформації

У статті на основі емпіричних показників всеукраїнського моніторингового дослідження, проведеного в 1994-2004 рр. Інститутом соціології НАН України з’ясовуються і аналізуються групи факторів, що детермінували появу соціально-політичних конфліктів в сучасному українському суспільстві, зумовили їх природу та характер розвитку.The article empirical indicators nationwide monitoring study conducted in 1994-2004 in the Institute of Sociology of NAS of Ukraine researched and analyzed a group of factors that determinuvaly emergence of socio-political conflicts in modern Ukrainian society, led to their nature and character development

Smoking and alcohol by HPV status in head and neck cancer : A Mendelian Randomization Study

Peer reviewe

Communication and Cognition in Primate Group Movement

We here review the communicative and cognitive processes underpinning collective group movement in animals. Generally, we identify 2 major axes to explain the dynamics of decision making in animal or human groups or aggregations: One describes whether the behavior is largely determined by simple rules such as keeping a specific distance from the neighbor, or whether global information is also factored in. The second axis describes whether or not the individual constituents of the group have overlapping or diverging interests. We then review the available evidence for baboons, which have been particularly well studied, but we also draw from further studies on other nonhuman primate species. Baboons and other nonhuman primates may produce specific signals in the group movement context, such as the notifying behavior of male hamadryas baboons at the departure from the sleeping site, or clear barks that are given by chacma baboons that have lost contact with the group or specific individuals. Such signals can be understood as expressions of specific motivational states of the individuals, but there is no evidence that the subjects intend to alter the knowledge state of the recipients. There is also no evidence for shared intentionality. The cognitive demands that are associated with decision making in the context of group coordination vary with the amount of information and possibly conflicting sources of information that need to be integrated. Thus, selective pressures should favor the use of signals that maintain group cohesion, while recipients should be selected to be able to make the decision that is in their own best interest in light of all the available information