Search results for " segregation"
showing 10 items of 84 documents
The high rate of endoreduplication in the repair deficient CHO mutant EM9 parallels a reduced level of methylated deoxycytidine in DNA
2008
It has been recently proposed that hypomethylation of DNA induced by 5-azacytidine (5-azaC) leads to reduced chromatid decatenation that ends up in endoreduplication, most likely due to a failure in topo II function [S. Mateos, I. Domínguez, N. Pastor, G. Cantero, F. Cortés, The DNA demethylating 5-azaC induces endoreduplication in cultured Chinese hamster cells, Mutat. Res. 578 (2005) 33-42]. The Chinese hamster mutant cell line EM9 has a high spontaneous frequency of endoreduplication as compared to its parental line AA8. In order to see if this is related to the degree of DNA methylation, we have investigated the basal levels of both endpoints in AA8 and EM9, as well as the effect of ext…
Cue combination in a combined feature contrast detection and figure identification task
2006
AbstractTarget figures defined by feature contrast in spatial frequency, orientation or both cues had to be detected in Gabor random fields and their shape had to be identified in a dual task paradigm. Performance improved with increasing feature contrast and was strongly correlated among both tasks. Subjects performed significantly better with combined cues than with single cues. The improvement due to cue summation was stronger than predicted by the assumption of independent feature specific mechanisms, and increased with the performance level achieved with single cues until it was limited by ceiling effects. Further, cue summation was also strongly correlated among tasks: when there was …
Geographic variability of ecological niches of plant species: are competition and stress relevant?
2002
A species’ niche position may differ strongly between geographic regions, for instance due to the effect of competitors or ecophysiological stress. However, it is unclear whether such strong geographic niche variation is the rule or the exception. We compared the niche positions of plant species between central England and eastern central Europe (as available from the literature), using phylogenetically independent contrasts. We found that most species occupied similar niche positions in both regions. More importantly, we found that niche variation was not higher in species susceptible to competitive displacement. Nor was niche variation higher in species that reach the edge of their range …
Niche segregation of coexisting Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) constrains food web coupling in subarctic lakes
2012
SUMMARY 1. Generalist fish species are recognised as important couplers of benthic and pelagic food-web compartments in lakes. However, interspecific niche segregation and individual specialisation may limit the potential for generalistic feeding behaviour. 2. We studied summer habitat use, stomach contents and stable isotopic compositions of the generalist feeder Arctic charr coexisting with its common resource competitor brown trout in five subarctic lakes in northern Norway to reveal population-level and individual-level niche plasticity. 3. Charr and trout showed partial niche segregation in all five lakes. Charr used all habitat types and a wide variety of invertebrate prey including z…
Urban segregation and unemployment: A case study of the urban area of Marseille – Aix-en-Provence (France)
2018
International audience; In this paper, we study the effects of the spatial organization of the urban area of Marseille – Aix-en-Provence on unemployment there. More specifically, differences in the characteristics of the residential population induce urban stratification with the result that urban structure may affect the probability of employment. In order to evaluate the effects of spatial structure on unemployment, we implement a spatial probit model to reveal the employment probabilities of young adults still living with their parents. Our results support the hypothesis that living in or near a deprived neighborhood decreases the probability of employment.
The oxidizing agent tertiary butyl hydroperoxide induces disturbances in spindle organization, c-meiosis, and aneuploidy in mouse oocytes
1996
It has been recently proposed that a concomitant generation of oxidative stress of oocytes with increasing maternal age may be a major factor responsible for the age-related increase in aneuploid conceptions. As a preliminary step in the testing of this hypothesis, we need to confirm that oxidative stress in itself can induce errors in chromosome segregation. In order to achieve this goal, germinal vesicle (GV)-stage mouse oocytes from unstimulated ICR and (C57BL x CBA) F1 hybrid female mice were matured in vitro for 9 h for metaphase I (MI) oocytes or 16 h for metaphase II (MII) oocytes in the presence of varying concentrations of the oxidizing agent tertiary-butyl hydroperoxide (tBH). MII…
School choice criteria and school segregation in the city of Valencia
2022
El objetivo de este estudio es conocer cuáles son los patrones que intervienen en la elección de centro escolar y detectar los factores sociodemográficos, económicos y de localización que subyacen tras ellos. Para ello, se ha realizado una encuesta a la demanda potencial de los centros públicos que imparten el segundo ciclo de educación infantil en la ciudad de Valencia. Los resultados indican que el principal criterio de elección de centro escolar es la proximidad entre el hogar y el colegio, y que el modo de desplazamiento más utilizado es el peatonal. Sin embargo, los costes de desplazamiento y los medios utilizados están directamente relacionados con las características socioeconómicas …
SRC1: an intron-containing yeast gene involved in sister chromatid segregation
2001
Analysis of a three-member gene family in the yeast Saccharomyces cerevisiae has allowed the discovery of a new gene that comprises two contiguous open reading frames previously annotated as YML034w and YML033w. The gene contains a small intron with two alternative 5′ splicing sites. It is specifically transcribed during G2/M in the cell cycle and after several hours of meiosis induction. Splicing of the mRNA is partially dependent on NAM8 but does not vary during meiosis or the cell cycle. Deletion of the gene induces a shortening of the anaphase and aggravates the phenotype of scc1 and esp1 conditional mutants, which suggests a direct role of the protein in sister chromatid separation. Co…
Centrosome structure is very similar in eupyrene and apyrene spermatocytes ofEphestia kuehniella(Pyralidae, Lepidoptera, Insecta)
1997
Summary The higher Lepidoptera produce two types of sperm, eupyrene and apyrene. Eupyrene spermatozoa are fertile, while apyrene spermatozoa are anucleate and, therefore, sterile. Meiosis differs between the two developmental lines. One of the most obvious differences is the aberrant organization of the apyrene spindles. They possess fewer microtubules than eupyrene spindles and chromosome segregation is irregular. To determine whether micotubule nucleation is impaired in the aprene spindles, the present fine structure study concentrated on the centrosomes in both spermatocyte types. In addition, the presence of gamma-tubulin, a newly discovered tubulin isoform which is prevalent in centros…
Abnormal mitotic spindle assembly and cytokinesis induced by D-Limonene in cultured mammalian cells
2013
D-Limonene is found widely in citrus and many other plant species; it is a major constituent of many essential oils and is used as a solvent for commercial purposes. With the discovery of its chemotherapeutic properties against cancer, it is important to investigate the biological effects of the exposure to D-Limonene and elucidate its, as yet unknown, mechanism of action. We reported here that D-Limonene is toxic in V79 Chinese hamster cells in a dose-dependent manner. Moreover, to determine the cellular target of D-Limonene, we performed morphological observations and immunocytochemical analysis and we showed that this drug has a direct effect on dividing cells preventing assembly of mito…