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In C. elegans, the yolk (green) provides the oocyte with polyunsaturated fatty acids, which control sperm (red) recruitment to the site of fertilization.p1143
Correct organization of a polarised microtubule array is vital for eukaryotic cells. Microtubule organizing centers (MTOCs) are generally believed to have an essential role in this process. However, two papers published in this issue have demonstrated that in fission yeast, interphase microtubules can self-organize in anucleate cells lacking any authentic MTOC.
The forkhead box O (FOXO) family of transcription factors regulate cell stress, cell cycle and cell death pathways. Their activities can be modulated by multiple posttranslational modifications, including phosphorylation and acetylation. A recent study adds a new twist to FOXO regulation, showing that coupled ubiquitination and deubiquitination of FOXO may be important for cellular responses to oxidative stress.
Atg5 has been previously characterized as a protein specifically required for autophagy, a lysosomal catabolic pathway for proteins and organelles. However, it has now been shown that, in addition to its role in the formation of autophagosomes, an Atg5 fragment produced by calpain cleavage has pro-apoptotic properties.
Understanding how self-renewal and pluripotency — two key characteristics of stem cells — are controlled may allow generation of stem cell lines from somatic tissues, thus avoiding the ethically contentious need to derive them from embryos. A step forward in this understanding was recently taken by two teams, who exploited recombinant retroviruses in gain-and-loss of function experiments to characterize candidate transcription factors with the potential to regulate 'stemness'.
A functional bipolar spindle is indispensible for the accurate segregation of chromosomes at mitosis. The centrosomal protein and polo-like kinase-1 (Plk1) substrate Kizuna (Kiz), has now been shown to have a novel function in maintaining spindle-pole integrity and spindle bipolarity.
