Fusion of centromeres and star formatons at pachytene of Cajanus x Atylosia hybrids

A phenomenon where the centromeres of different bivalents fuse to form typical star-shaped configurations has been observed at the pachytene stage of three hybrids, Cajanus cajan Atylosia lineata, C. cajan A. sericea and C. cajan A. scarabaeoides. The frequency of certain bivalent combinations forming stars was found to be higher than others, thereby, indicating the non-random nature of this phenomenon. Although no hexavalents, octovalents or more than one quadrivalent per cell during diakinesis and metaphase-I were observed, as were to be expected on the basis of the data obtained on the number of arms involved in the star-formations and the number of stars per cell at pachytene, the possibility that these stars are the result of reciprocal translocations cannot be ruled out. A definite relationship between the number of cells showing these star formations at pachytene and the number of cells showing bivalent associations at diakinesis and metaphase I on the one hand, and between the number of arms involved the stars and the number of chromosomes involved in each association on the other, signify that these stars are forerunners of secondary associations

Hybridization and speciation in angiosperms: a role for pollinator shifts?

The majority of convincingly documented cases of hybridization in angiosperms has involved genetic introgression between the parental species or formation of a hybrid species with increased ploidy; however, homoploid (diploid) hybridization may be just as common. Recent studies, including one in BMC Evolutionary Biology, show that pollinator shifts can play a role in both mechanisms of hybrid speciation

The Effects of Aging on the Molecular and Cellular Composition of the Prostate Microenvironment

Advancing age is associated with substantial increases in the incidence rates of common diseases affecting the prostate gland including benign prostatic hyperplasia (BPH) and prostate carcinoma. The prostate is comprised of a functional secretory epithelium, a basal epithelium, and a supporting stroma comprised of structural elements, and a spectrum of cell types that includes smooth muscle cells, fibroblasts, and inflammatory cells. As reciprocal interactions between epithelium and stromal constituents are essential for normal organogenesis and serve to maintain normal functions, discordance within the stroma could permit or promote disease processes. In this study we sought to identify aging-associated alterations in the mouse prostate microenvironment that could influence pathology.We quantitated transcript levels in microdissected glandular-adjacent stroma from young (age 4 months) and old (age 20-24 months) C57BL/6 mice, and identified a significant change in the expression of 1259 genes (p<0.05). These included increases in transcripts encoding proteins associated with inflammation (e.g., Ccl8, Ccl12), genotoxic/oxidative stress (e.g., Apod, Serpinb5) and other paracrine-acting effects (e.g., Cyr61). The expression of several collagen genes (e.g., Col1a1 and Col3a1) exhibited age-associated declines. By histology, immunofluorescence, and electron microscopy we determined that the collagen matrix is abundant and disorganized, smooth muscle cell orientation is disordered, and inflammatory infiltrates are significantly increased, and are comprised of macrophages, T cells and, to a lesser extent, B cells.These findings demonstrate that during normal aging the prostate stroma exhibits phenotypic and molecular characteristics plausibly contributing to the striking age associated pathologies affecting the prostate