Orientation of cell division is a vital aspect of tissue morphogenesis and growth. Asymmetric divisions generate cell fate diversity and epithelial stratification, whereas symmetric divisions contribute to tissue growth, spreading, and elongation. Here, we describe a mechanism for positioning the spindle in symmetric cell divisions of an embryonic epithelium. We show that during the early stage...

In an earlier paper it was suggested that a knowledge of the elastic-stress variation in the neighborhood of an angular corner of an infinite plate would perhaps be of value in analyzing the stress distribution at the base of a V-notch. As a part of a more general study, the specific case of a zero-angle notch, or crack, was carried out to supplement results obtained by other investigators. Thi...

Symmetric and asymmetric divisions are important for self-renewal and differentiation of stem cells during neurogenesis. Although cerebellar granule neurogenesis is controlled by sonic hedgehog (SHH) signaling, whether and how this process is mediated by regulation of cell division modes have not been determined. Here, using time-lapse imaging and cell culture from neuronal progenitor-specific ...

In the homeostatic state, adult stem cells divide either symmetrically to increase the stem cell number to compensate stem cell loss, or asymmetrically to maintain the population while producing differentiated cells. We have investigated the mode of stem cell division in the testes of Drosophila melanogaster by lineage tracing and confirm the presence of symmetric stem cell division in this sys...

If G is a connected graph, then HA(G) = ∑ u6=v(deg(u) + deg(v))/d(u, v) is the additively Harary index and HM (G) = ∑ u6=v deg(u) deg(v)/d(u, v) the multiplicatively Harary index of G. G is an apex tree if it contains a vertex x such that G − x is a tree and is a k-apex tree if k is the smallest integer for which there exists a k-set X ⊆ V (G) such that G − X is a tree. Upper and lower bounds o...

Let G be a finitely generated residually finite group and let an(G) denote the number of index n subgroups of G. If an(G) ≤ nα for some α and for all n, then G is said to have polynomial subgroup growth (PSG, for short). The degree of G is then defined by deg(G) = limsup log an(G) log n . Very little seems to be known about the relation between deg(G) and the algebraic structure of G. We derive...

In this paper a set of de nitions describing general real number representation sys tems is presented Our purpose is to nd a su ciently wide model de nition including classical systems signed digit notation linear numeration systems p adic numbers symmetric level index arithmetic but speci c enough to make it possible to build some practical results We focuse on the redundancy property and the ...

Overexpression of ABCG2 is considered a major mechanism of cancer drug resistance. Recent studies have shown that ABCG2 can regulate the switch between symmetric and asymmetric cell division in adult stem cells; however, the relationship between ABCG2 and cell division in drug-resistant cancer cells remains to be determined. In the present study, we demonstrated that ABCG2 is involved in the ce...