Stem cells and neuroblasts derived from mouse embryos undergo repeated asymmetric cell divisions, generating neural lineage trees similar to those of invertebrates. In Drosophila, unequal distribution of Numb protein during mitosis produces asymmetric cell divisions and consequently diverse neural cell fates. We investigated whether a mouse homologue m-numb had a similar role during mouse corti...

BACKGROUND Successful cell duplication requires orderly progression through a succession of dramatic cell-cycle events. Disruption of this precise coupling can compromise genomic integrity. The coordination of cell-cycle events is thought to arise from control by a single master regulator, cyclin:Cdk, whose activity oscillates. However, we still know very little of how individual cell-cycle eve...

The problem studied in this paper arises from a simple practical problem: how to divide a cake among the children attending a birthday p a r t y i n s u c h a way that each c hild gets the same amount o f c a k e and (perhaps more important to them) the same amount of icing. Let S be a convex set contained in the (xx y)-plane. In mathematical terms, a c a k e C with base S is a solid containing...

BACKGROUND AND PURPOSE Lumbar zypapophyseal joints are innervated by the medial branch of the posterior lumbar ramus. The aim of this work was to describe the precise course of the medial ramus on axial CT scans and to define a precise location for its selective infiltration. METHODS Lumbar spines of two cadavers were first dissected to assess the route of the L1-L5 posterior ramus. Thirty lu...

Immediately following fertilisation in Drosophila and many other arthropods, the embryo undergoes a series of rapid syncytial nuclear divisions. These divisions are driven by maternally supplied components and occur in the absence of zygotic transcription. Unlike typical cell divisions, these divisions alternate between S and M phases, resulting in cell cycles that last only from 10 to 25 min. ...

Tissue replenishment from stem cells follows a precise cascade of events, during which stem cell daughters first proliferate by mitotic transit amplifying divisions and then enter terminal differentiation. Here we address how stem cell daughters are guided through the early steps of development. In Drosophila testes, somatic cyst cells enclose the proliferating and differentiating germline cell...

Systems composed of activity choices that interact in nonsimple ways can allow firms to create and sustain a competitive advantage. However, in complex systems, decision makers may not always have a precise understanding of the exact strength of the interaction between activities. Likewise, incentive and accounting systems may lead decision makers to ignore or misperceive interactions. This pap...

Animal tissue development relies on precise generation and deployment of specific cell types into tissue sub-structures. Understanding how this process is regulated remains a major challenge of biology. In many tissues, development progresses through a sequence of dividing progenitor cells, each with decreasing potency, that balance their growth and differentiation. Dividing progenitor cells th...

Meiosis in mammalian oocytes includes two asymmetric meiotic divisions that result in extrusion of the first and second polar bodies (PBI and PBII, respectively). Fyn, an Src family kinase (SFK), colocalizes with filamentous actin (F-actin) at the meiotic cleavage furrow area of mouse oocytes. In this paper, these studies are extended to rat oocytes. Furthermore, inhibition of Fyn decreased the...