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Selected AbstractsOrbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue , I. A sample of systems with components' masses between 1 and 2 M,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009K. G. He, miniak ABSTRACT We derive the absolute physical and orbital parameters for a sample of 18 detached eclipsing binaries from the All-Sky Automated Survey (ASAS) data base based on the available photometry and our own radial velocity (RV) measurements. The RVs are computed using spectra we collected with the 3.9-m Anglo-Australian Telescope (AAT) and its University College London Echelle Spectrograph (UCLES), and the 1.9-m Radcliffe telescope and its Grating Instrument for Radiation Analysis with a Fibre-Fed Echelle (GIRAFFE) at the South African Astronomical Observatory (SAAO). In order to obtain as precise RVs as possible, most of the systems were observed with an iodine cell available at the AAT/UCLES and/or analysed using the two-dimensional cross-correlation technique (TODCOR). The RVs were measured with TODCOR using synthetic template spectra as references. However, for two objects we used our own approach to the tomographic disentangling of the binary spectra to provide observed template spectra for the RV measurements and to improve the RV precision even more. For one of these binaries, AI Phe, we were able to the obtain an orbital solution with an RV rms of 62 and 24 m s,1 for the primary and secondary, respectively. For this system, the precision in M sin3i is 0.08 per cent. For the analysis, we used the photometry available in the ASAS data base. We combined the RV and light curves using phoebe and jktebop codes to obtain the absolute physical parameters of the systems. Having precise RVs, we were able to reach ,0.2 per cent precision (or better) in masses in several cases but in radii, due to the limited precision of the ASAS photometry, we were able to reach a precision of only 1 per cent in one case and 3,5 per cent in a few more cases. For the majority of our objects, the orbital and physical analysis is presented for the first time. [source] Developmental changes in cell proliferation in the auditory midbrain of the bullfrog, Rana catesbeianaDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2006Andrea Megela Simmons Abstract We examined patterns of cell proliferation in the auditory midbrain (torus semicircularis) of the bullfrog, Rana catesbeiana, over larval and early postmetamorphic development, by visualizing incorporation of 5-bromo-2,-deoxyuridine (BrdU) in cycling cells. At all developmental stages, BrdU-labeled cells were concentrated around the optic ventricle. BrdU-labeled cells also appeared within the torus semicircularis itself, in a stage-specific manner. The mitotic index, quantified as the percent of BrdU-positive cells outside the ventricular zone per total cells available for label, varied over larval development. Mitotic index was low in hatchling, early larval, and late larval stages, and increased significantly in deaf period, metamorphic climax, and froglet stages. Cell proliferation was higher in metamorphic climax than at other stages, suggesting increased cell proliferation in preparation for the transition from an aquatic to an amphibious existence. The change in mitotic index over development did not parallel the change in the total numbers of cells available for label. BrdU incorporation was additionally quantified by dot-blot assay, showing that BrdU is available for label up to 72 h postinjection. The pattern of change in cell proliferation in the torus semicircularis differs from that in the auditory medulla (dorsal medullary nucleus and superior olivary nucleus), suggesting that cell proliferation in these distinct auditory nuclei is mediated by different underlying mechanisms. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1212,1224, 2006 [source] Cell proliferation in the Rana catesbeiana auditory medulla over metamorphic developmentDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2006Judith A. Chapman Abstract During metamorphic development, bullfrogs (Rana catesbeiana) undergo substantial morphological, anatomical, and physiological changes as the animals prepare for the transition from a fully-aquatic to a semi-terrestrial existence. Using BrdU incorporation and immunohistochemistry, we quantify changes in cell proliferation in two key auditory brainstem nuclei, the dorsolateral nucleus and the superior olivary nucleus, over the course of larval and early postmetamorphic development. From hatchling through early larval stages, numbers of proliferating cells increase in both nuclei, paralleling the overall increase in total numbers of cells available for labeling. Numbers of proliferating cells in the superior olivary nucleus decrease during the late larval and deaf periods, and significantly increase during metamorphic climax. Proliferating cells in the dorsolateral nucleus increase in number from hatchling to late larval stages, decrease during the deaf period, and increase during climax. In both nuclei, numbers of proliferating cells decrease during the postmetamorphic froglet stage, despite increases in the number of cells available for label. Newly generated cells express either glial- or neural-specific phenotypes beginning between 1 week and 1 month post-BrdU injection, respectively, while some new cells express ,-aminobutyric acid within 2 days of mitosis. Our data show that these auditory nuclei dramatically up-regulate mitosis immediately prior to establishment of a transduction system based on atmospheric hearing. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source] Regenerative potential of human skeletal muscle during agingAGING CELL, Issue 2 2002Valérie Renault Summary In this study, we have investigated the consequences of aging on the regenerative capacity of human skeletal muscle by evaluating two parameters: (i) variation in telomere length which was used to evaluate the in vivo turn-over and (ii) the proportion of satellite cells calculated as compared to the total number of nuclei in a muscle fibre. Two skeletal muscles which have different types of innervation were analysed: the biceps brachii, a limb muscle, and the masseter, a masticatory muscle. The biopsies were obtained from two groups: young adults (23 ± 1.15 years old) and aged adults (74 ± 4.25 years old). Our results showed that during adult life, minimum telomere lengths and mean telomere lengths remained stable in the two muscles. The mean number of myonuclei per fibre was lower in the biceps brachii than in the masseter but no significant change was observed in either muscle with increasing age. However, the number of satellite cells, expressed as a proportion of myonuclei, decreased with age in both muscles. Therefore, normal aging of skeletal muscle in vivo is reflected by the number of satellite cells available for regeneration, but not by the mean number of myonuclei per fibre or by telomere lengths. We conclude that a decrease in regenerative capacity with age may be partially explained by a reduced availability of satellite cells. [source] Adhesion of perichondrial cells to a polylactic acid scaffoldJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2003Alexander Giurea Abstract The number of chondrogenic cells available locally is an important factor in the repair process for cartilage defects. Previous studies demonstrated that the number of transplanted rabbit perichondrial cells (PC) remaining in a cartilage defect in vivo, after being carried into the site in a polylactic acid (PLA) scaffold, declined markedly within two days. This study examined the ability of in vitro culture of PC/PLA constructs to enhance subsequent biomechanical stability of the cells and the matrix content in an in vitro screening assay. PC/PLA constructs were analyzed after 1 h, 1 and 2 weeks of culture. The biomechanical adherence of PC to the PLA scaffold was tested by subjecting the PC/PLA constructs to a range of flow velocities (0.25,25 mm/s), spanning the range estimated to occur under conditions of construct insertion in vivo. The adhesion of PC to the PLA carrier was increased significantly by 1 and 2 weeks of incubation, with 25 mm/s flow causing a 57% detachment of cells after 1 h of seeding, but only 7% and 16% after 1 and 2 weeks of culture, respectively (p > 0.001). This adherence was associated with marked deposition of glycosaminoglycan and collagen. These findings suggest that pre-incubation of PC-laden PLA scaffolds markedly enhances the stability of the indwelling cells. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Presumptive pre-sertoli cells express genes involved in cell proliferation and cell signalling during a critical window in early testis differentiationMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2007Aron T. Cory In mammals, the pre-Sertoli cell of the male genital ridge is the first cell type to display sex specific differentiation and differential gene expression. The genetic cascade driving the differentiationof pre-Sertoli cells and ultimately testis formationis beginning to be unravelled, but many questions remain. A better understanding of the transcriptome of pre-Sertoli cells immediately after sex determination is essential in order to further understand this differentiationprocess. A mouse model expressing Red Fluorescent Protein (RFP) under the control of a hybrid mouse/pig SRY promoter (HybSRYp-RFP) was used to purify cells from embryonic day 12.0 (e12.0) male genital ridges. To compare the transcriptomes of HybSRYp-RFP cell populations versus age matched whole female genital ridges, RNA was extracted and used to generate molecular probes that were hybridized onto Affymetrix Mouse Genome 430 2.0 micro-arrays. The expression of genes considered markers for pre-Sertoli cells, including Sox9, Mis, Dhh and Fgf9 were identified within the HybSRYp-RFP expressing cell population, while markers for germ cells (Oct4, SSEA-1) and endothelial cells (Ntrk3) were not identified. In contrast, markers for ovarian somatic cell expression, including Fst and Bmp2, were identified as overexpressed within the ovarian cell population. In a general fashion, genes identified as 2.5-fold over expressed in HybSRYp-RFP expressing cells coded notably for cell signalling and extra cellular proteins. The expression of Sox10, Stc2, Fgf18, Fgf13 and Wnt6 were further characterized via whole mount in situ hybridization (WISH) on male and female genital ridges between e11.5 and e14.5. Sox10, Fgf18, Fgf13 and Stc2 gene expression was detected within the male genital ridges while Wnt6 was found diffusely within both the male and female genital ridges. These data represent the earliest comprehensive microarray expression analysis of purified presumptive pre-Sertoli cells available to date. Mol. Reprod. Dev. 74: 1491,1504, 2007. © 2007 Wiley-Liss, Inc. [source] | ||||||||||