排序方式: 共有242条查询结果,搜索用时 234 毫秒
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Reis AH Almeida-Coburn KL Louza MP Cerqueira DM Aguiar DP Silva-Cardoso L Mendes FA Andrade LR Einicker-Lamas M Atella GC Brito JM Abreu JG 《Developmental biology》2012,365(2):350-362
Cholesterol-rich membrane microdomains (CRMMs) are specialized structures that have recently gained much attention in cell biology because of their involvement in cell signaling and trafficking. However, few investigations, particularly those addressing embryonic development, have succeeded in manipulating and observing CRMMs in living cells. In this study, we performed a detailed characterization of the CRMMs lipid composition during early frog development. Our data showed that disruption of CRMMs through methyl-β-cyclodextrin (MβCD) cholesterol depletion at the blastula stage did not affect Spemann's organizer gene expression and inductive properties, but impaired correct head development in frog and chick embryos by affecting the prechordal plate gene expression and cellular morphology. The MβCD anterior defect phenotype was recapitulated in head anlagen (HA) explant cultures. Culture of animal cap expressing Dkk1 combined with MβCD-HA generated a head containing eyes and cement gland. Together, these data show that during Xenopus blastula and gastrula stages, CRMMs have a very dynamic lipid composition and provide evidence that the secreted Wnt antagonist Dkk1 can partially rescue anterior structures in cholesterol-depleted head anlagen. 相似文献
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Marúcia Irena Medeiros Amorim Íris Ferrari Marcelo de Oliveira Bahia Patrícia Danielle Lima Lima Plínio Cerqueira dos Santos Cardoso Andr Salim Khayat Isabel Rosa Cabral Rommel Rodríguez Burbano 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2008,652(2):204-207
Sources of light beams such as white fluorescent light, are present in our daily life to meet the needs of life in the modern world. This study was conducted with the objective of determining the possible genotoxic, cytotoxic and aneugenic effects caused by this agent in different stages of the cell cycle (G0/early G1, S, and late G2), using different cytogenetic parameters (sister chromatid exchanges––SCE, chromosome aberrations––CA, and detection of aneugenic effects) in lymphocytes from temporary cultures of human peripheral blood. WFL showed a genotoxic effect in vitro, expressed by an increase in the frequency of SCE's, regardless of the cell cycle stage. However, no increase in the frequency of CAs was observed. In addition, disturbances in cell cycle kinetics and chromosomal segregation were also observed. Taken together, such data may contribute to a better understanding and a different management in the use of phototherapy for some pathological conditions. 相似文献
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Amorim MI Ferrari I Bahia Mde O Lima PD Cardoso PC Khayat AS Cabral IR Burbano RR 《Mutation research》2008,652(2):204-207
Sources of light beams such as white fluorescent light, are present in our daily life to meet the needs of life in the modern world. This study was conducted with the objective of determining the possible genotoxic, cytotoxic and aneugenic effects caused by this agent in different stages of the cell cycle (G0/early G1, S, and late G2), using different cytogenetic parameters (sister chromatid exchanges--SCE, chromosome aberrations--CA, and detection of aneugenic effects) in lymphocytes from temporary cultures of human peripheral blood. WFL showed a genotoxic effect in vitro, expressed by an increase in the frequency of SCE's, regardless of the cell cycle stage. However, no increase in the frequency of CAs was observed. In addition, disturbances in cell cycle kinetics and chromosomal segregation were also observed. Taken together, such data may contribute to a better understanding and a different management in the use of phototherapy for some pathological conditions. 相似文献
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Fragmentation gradients differentially affect the species range distributions of four taxonomic groups in semi‐deciduous Atlantic forest 下载免费PDF全文
Human activities often cause habitat fragmentation and how forest fragments affect species range distributions has implications for ecology and conservation. However, few studies have considered communities within the same landscape. Here, we analyzed metacommunity structure to determine the range distributions for species in four taxonomic groups (amphibians, birds, social wasps, and trees) in a patchy landscape of semi‐deciduous Atlantic forest in southwestern Brazil. Although trees are a key component of the environment for animals in forested patches, the ranges of bird, wasp, and amphibian species did not change in concert with the species ranges of trees. The species ranges of amphibians and social wasps were unaffected by fragmentation gradients and exhibited independent distribution patterns (i.e., random structure). In contrast, birds and trees exhibited range turnover along different fragmentation gradients, indicating that species show idiosyncratic responses to abiotic factors (i.e., Gleasonian structure). For birds, some less‐resilient species occurred only in fragments with a large area of native vegetation at a radius of 5 km from the center of the sampled forest fragments, whereas other more stress‐tolerant species occurred only in sites with small areas of native vegetation. For trees, some later succession species (e.g., animal‐dispersed seeds) occurred only in fragments with high connectivity, whereas earlier‐recruiting species (e.g., wind‐dispersed seeds) occurred in fragments with low connectivity. Thus, determining the effects of human‐modified landscapes on species range distributions, even within the same landscape, might not be a trivial task. 相似文献
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Coccoid Form of Helicobacter pylori as a Morphological Manifestation of Cell Adaptation to the Environment 下载免费PDF全文
N. F. Azevedo C. Almeida L. Cerqueira S. Dias C. W. Keevil M. J. Vieira 《Applied microbiology》2007,73(10):3423-3427
After characterization of preferred conditions for Helicobacter pylori survival in the sessile state, it was observed that the bacterium transforms from spiral to coccoid under mild circumstances, whereas under extreme ones it is unable to undergo shape modification. This strongly supports the view that transformation into the coccoid form is an active, biologically led process, switched on by the bacterium as a protection mechanism. 相似文献
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Antonio Cerqueira Alberto Martín Catherine E. Symonds Junko Odajima Pierre Dubus Mariano Barbacid David Santamaría 《Molecular and cellular biology》2014,34(8):1452-1459
The Cip/Kip family, namely, p21Cip1, p27Kip1, and p57Kip2, are stoichiometric cyclin-dependent kinase inhibitors (CKIs). Paradoxically, they have been proposed to also act as positive regulators of Cdk4/6-cyclin D by stabilizing these heterodimers. Loss of p21Cip1 and p27Kip1 reduces Cdk4/6-cyclin D complexes, although with limited phenotypic consequences compared to the embryonic lethality of Cdk4/6 or triple cyclin D deficiency. This milder phenotype was attributed to Cdk2 compensatory mechanisms. To address this controversy using a genetic approach, we generated Cdk2−/−
p21−/−
p27−/− mice. Triple-knockout mouse embryonic fibroblasts (MEFs) displayed minimal levels of D-type cyclins and Cdk4/6-cyclin D complexes. p57Kip2 downregulation in the absence of p21Cip1 and p27Kip1 aggravated this phenotype, yet MEFs lacking all Cip/Kip proteins exhibited increased retinoblastoma phosphorylation, together with enhanced proliferation and transformation capacity. In vivo, Cdk2 ablation induced partial perinatal lethality in p21−/−
p27−/− mice, suggesting partial Cdk2-dependent compensation. However, Cdk2−/−
p21−/−
p27−/− survivors displayed all phenotypes described for p27−/− mice, including organomegalia and pituitary tumors. Thus, Cip/Kip deficiency does not impair interphasic Cdk activity even in the absence of Cdk2, suggesting that their Cdk-cyclin assembly function is dispensable for homeostatic control in most cell types. 相似文献
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Gabriel C. Grenho L. Cerqueira F. Medeiros R. Dias A. M. Ribeiro A. I. Proença M. F. Fernandes M. H. Sousa J. C. Monteiro F. J. Ferraz M. P. 《Mycopathologia》2019,184(6):775-786
Mycopathologia - Candida can adhere and form biofilm on biomaterials commonly used in medical devices which is a key attribute that enhances its ability to cause infections in humans. Furthermore,... 相似文献