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Selected AbstractsClonal analysis of patterns of growth, stem cell activity, and cell movement during the development and maintenance of the murine corneal epitheliumDEVELOPMENTAL DYNAMICS, Issue 4 2002J. Martin Collinson Abstract Patterns of growth and cell movement in the developing and adult corneal epithelium were investigated by analysing clonal patches of LacZ -expressing cells in chimeric and X-inactivation mosaic mice. It was found that cell proliferation throughout the basal corneal epithelium during embryogenesis and early postnatal life creates a disordered mosaic pattern of LacZ+ clones that contrasts with patterns of proliferation and striping produced during the later embryonic stages of retinal pigmented epithelium development. The early mosaic pattern in the corneal epithelium is replaced in the first 12 postnatal weeks by an ordered pattern of radial stripes or sectors that reflects migration without mixing of the progeny of clones of limbal stem cells. In contrast to previous assumptions, it was found that maturation of the activity of limbal stem cells and the pattern of migration of their progeny are delayed for several weeks postnatally. No evidence was found for immigration of the progeny of stem cells until the 5th postnatal week. There are approximately 100 clones of limbal stem cells initially, and clones are lost during postnatal life. Our studies provide a new assay for limbal and corneal defects in mutant mice. © 2002 Wiley-Liss, Inc. [source] Mushroom bodies are not required for courtship behavior by normal and sexually mosaic DrosophilaDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2002Asami Kido Abstract To elucidate the effect of feminization of male Drosophila brain cells on courtship control, we performed a large scale screening of expression drivers that can suppress male-specific behavior with transformer gene expression. Two drivers caused essentially total courtship suppression. The expression pattern of these drivers did not show any correlation with the mushroom bodies or the antennal lobes, the regions that have been suggested to play important roles in courtship. Ablation of mushroom bodies using hydroxyurea treatment did not affect this courtship suppression. The ablation did not change either wild-type heterosexual behavior or bisexual behavior caused by transformer expression driven by the same drivers used in the previous studies to suggest the involvement of the mushroom bodies in courtship. Our results show that feminization of different nonoverlapping cells in other parts of the protocerebrum was sufficient to cause the same bisexual or suppressed-courtship phenotype. Thus, contrary to previous assumptions, the mushroom bodies are not required for the control of courtship. Present evidence supports its mediation by other distributed protocerebral regions. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 302,311, 2002 [source] The merging of community ecology and phylogenetic biologyECOLOGY LETTERS, Issue 7 2009Jeannine Cavender-Bares Abstract The increasing availability of phylogenetic data, computing power and informatics tools has facilitated a rapid expansion of studies that apply phylogenetic data and methods to community ecology. Several key areas are reviewed in which phylogenetic information helps to resolve long-standing controversies in community ecology, challenges previous assumptions, and opens new areas of investigation. In particular, studies in phylogenetic community ecology have helped to reveal the multitude of processes driving community assembly and have demonstrated the importance of evolution in the assembly process. Phylogenetic approaches have also increased understanding of the consequences of community interactions for speciation, adaptation and extinction. Finally, phylogenetic community structure and composition holds promise for predicting ecosystem processes and impacts of global change. Major challenges to advancing these areas remain. In particular, determining the extent to which ecologically relevant traits are phylogenetically conserved or convergent, and over what temporal scale, is critical to understanding the causes of community phylogenetic structure and its evolutionary and ecosystem consequences. Harnessing phylogenetic information to understand and forecast changes in diversity and dynamics of communities is a critical step in managing and restoring the Earth's biota in a time of rapid global change. [source] 5,-Reductase type 2 gene variant associations with prostate cancer risk, circulating hormone levels and androgenetic alopeciaINTERNATIONAL JOURNAL OF CANCER, Issue 4 2007Vanessa M. Hayes Abstract Controversy exists over the significance of associations between the SRD5A2 (5,-reductase type 2) polymorphisms, A49T and V89L, and risk of prostate cancer. These potentially functional polymorphisms may alter life-long exposure to androgens with subsequent effects on male health and aging. The aim of this study was to examine the association of these variants with prostate cancer risk, plasma hormone levels and androgenetic alopecia. Subjects include 827 cases and 736 controls from an Australian population-based case,control study of prostate cancer. Information on prostate cancer risk factors and patterns of balding were collected. Plasma levels of testosterone, 3,-diol glucuronide (3,-diolG), dehydroepiandrosterone sulfate, androstenedione, sex hormone-binding globulin and estradiol were measured for controls. No associations with the V89L polymorphism were found. Carriers of the rarer A49T A allele were at a 60% higher risk of prostate cancer (OR = 1.60; 95% CI 1.09,2.36; p = 0.02) and 50% lower risk of vertex and frontal balding (p = 0.03) compared with men homozygous for the more common G allele. Although we found little evidence of association between this variant and plasma levels of 5 measured androgens, circulating 3,-diolG levels were 34% lower in A49T A allele carriers (p < 0.0001). Our study provides evidence that the SRD5A2 A49T A variant is associated with an increased risk of prostate cancer, lower levels of circulating 3,-diolG and decreased risk of baldness. These findings raise important questions with respect to previous assumptions concerning hormonal influences on prostate cancer risk in ageing males. © 2006 Wiley-Liss, Inc. [source] Cranial Nonmetric Variation and Estimating Ancestry,JOURNAL OF FORENSIC SCIENCES, Issue 5 2009Joseph T. Hefner Ph.D. Abstract:, Historically, when predicting the ancestry of human skeletal remains, forensic anthropologists have not fully considered the variation within human populations, but instead have relied on a typological, experience-based approach. Unfortunately, reliance on observer experience has produced a method that is as much an art as it is a science. This research focuses on the frequency distribution and inter-trait correlations of 11 common morphoscopic traits to demonstrate that the experience-based approach to ancestry prediction is indeed an art that is unscientific, because it is unreplicable, unreliable, and invalid. Ten of 11 traits examined had frequency distributions with significant differences (p < 0.001) between groups, but the range in variation of these traits far exceeds previous assumptions. Such within group variation clearly demonstrates that extreme trait expressions are not reliable for estimating ancestry through visual observation alone, but instead that these traits should be analyzed within a statistical framework. [source] | ||||||||||