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排序方式: 共有360条查询结果,搜索用时 375 毫秒
71.
72.
Sheila Adela Villa‐Cedillo Martha Patricia Nava‐Hernndez Adolfo Soto‐Domínguez Jos Anselmo Hernndez‐Ibarra Jos Juan Perez‐Trujillo Odila Saucedo‐Crdenas 《Cell biology international》2019,43(6):706-714
Early exposure to lead (Pb) has been associated with an elevated risk of developing neurodegenerative diseases. There is evidence that neuronal damage in chronic Pb exposure can be caused by the convergence of glial damage. Apoptosis may be a possible mechanism of Pb‐induced cell death in the central nervous system. We tested cellular damage and apoptosis in the spinal cord of Wistar rats treated with Pb. Twelve rats were divided into two groups (n = 6): the control group was treated with only drinking water and the other group received 500 ppm of Pb acetate. After 3 months of Pb treatment, all animals were euthanized and spinal cords were extracted. Morphology was evaluated by Nissl and Kluver‐Barrera stainings. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Specific antibodies were used to evaluate Pb damage in oligodendrocytes, astrocytes, and microglia. A large number of apoptotic bodies was observed in the white matter of the Pb‐treated group. The Pb‐treated group also showed a reduced number of neurons and oligodendrocytes but had an increased number of astrocytes compared with the nontreated group. Our results demonstrate that chronic Pb treatment induces neurodegeneration, demyelination, and astrogliosis in the rat spinal cord. 相似文献
73.
de la Fuente R Parra MT Viera A Calvente A Gómez R Suja JA Rufas JS Page J 《PLoS genetics》2007,3(11):e198
In most eutherian mammals, sex chromosomes synapse and recombine during male meiosis in a small region called pseudoautosomal region. However in some species sex chromosomes do not synapse, and how these chromosomes manage to ensure their proper segregation is under discussion. Here we present a study of the meiotic structure and behavior of sex chromosomes in one of these species, the Mongolian gerbil (Meriones unguiculatus). We have analyzed the location of synaptonemal complex (SC) proteins SYCP1 and SYCP3, as well as three proteins involved in the process of meiotic recombination (RAD51, MLH1, and γ-H2AX). Our results show that although X and Y chromosomes are associated at pachytene and form a sex body, their axial elements (AEs) do not contact, and they never assemble a SC central element. Furthermore, MLH1 is not detected on the AEs of the sex chromosomes, indicating the absence of reciprocal recombination. At diplotene the organization of sex chromosomes changes strikingly, their AEs associate end to end, and SYCP3 forms an intricate network that occupies the Y chromosome and the distal region of the X chromosome long arm. Both the association of sex chromosomes and the SYCP3 structure are maintained until metaphase I. In anaphase I sex chromosomes migrate to opposite poles, but SYCP3 filaments connecting both chromosomes are observed. Hence, one can assume that SYCP3 modifications detected from diplotene onwards are correlated with the maintenance of sex chromosome association. These results demonstrate that some components of the SC may participate in the segregation of achiasmate sex chromosomes in eutherian mammals. 相似文献
74.
Animal models are key in biomedical research as a proof of concept to study complex processes in a physiological context. Despite the small yet crucial role animals play in fundamental and applied research, the value of animal research is recurrently undermined. Lack of openness and transparency encourages misconceptions, which can have a dramatic negative impact on science and medicine. Research centres should use all available resources to ensure that relevant details about their use of animals in research are readily accessible. More concerted efforts by professional advocacy groups devoted to informing about the benefits of biomedical animal research are also crucial. The European Animal Research Association acts as an umbrella organisation providing support to national advocacy groups and coordinating actions in countries in which no advocacy group exists. 相似文献
75.
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77.
Amara I Odena A Oliveira E Moreno A Masmoudi K Pagès M Goday A 《Plant & cell physiology》2012,53(2):312-329
LEA (late embryogenesis abundant) proteins participate in plant stress tolerance responses, but the mechanisms by which protection occurs are not fully understood. In the present work the unfolded proteins from maize dry embryos were analyzed by mass spectrometry. Twenty embryo proteins were identified, and among them 13 corresponded to LEA-type proteins. We selected three major LEA proteins, Emb564, Rab17 and Mlg3, belonging to groups 1, 2 and 3, respectively, and we undertook a comparative study in order to highlight differences among them. The post-translational modifications of native proteins were analyzed and the anti-aggregation properties of recombinant Emb564, Rab17 and Mgl3 proteins were evaluated in vitro. In addition, the protective effects of the LEA proteins were assessed in living cells under stress in Escherichia coli cells and in Nicotiana bentamiana leaves agroinfiltrated with fluorescent LEA-green fluorescent protein (GFP) fusions. Protein visualization by confocal microscopy indicated that cells expressing Mg3-GFP showed reduced cell shrinkage effects during dehydration and that Rab17-GFP co-localized to leaf oil bodies after heat shock. Overall, the results highlight differences and suggest functional diversity among maize LEA groups. 相似文献
78.
Huang M Sanchez-Moreiras AM Abel C Sohrabi R Lee S Gershenzon J Tholl D 《The New phytologist》2012,193(4):997-1008
Flowers have a high risk of pathogen attack because of their rich nutrient and moisture content, and high frequency of insect visitors. We investigated the role of (E)-β-caryophyllene in floral defense against a microbial pathogen. This sesquiterpene is a common volatile compound emitted from flowers, and is a major volatile released from the stigma of Arabidopsis thaliana flowers. Arabidopsis thaliana lines lacking a functional (E)-β-caryophyllene synthase or constitutively overexpressing this gene were challenged with Pseudomonas syringae pv. tomato DC3000, which is a bacterial pathogen of brassicaceous plants. Flowers of plant lines lacking (E)-β-caryophyllene emission showed greater bacterial growth on their stigmas than did wild-type flowers, and their seeds were lighter and misshapen. By contrast, plant lines with ectopic (E)-β-caryophyllene emission from vegetative parts were more resistant than wild-type plants to pathogen infection of leaves, and showed reduced cell damage and higher seed production. Based on in vitro experiments, (E)-β-caryophyllene seems to act by direct inhibition of bacterial growth, rather than by triggering defense signaling pathways. (E)-β-Caryophyllene thus appears to serve as a defense against pathogens that invade floral tissues and, like other floral volatiles, may play multiple roles in defense and pollinator attraction. 相似文献
79.
Garcia-Martin A Kwa LG Strohmann B Robert B Holzwarth AR Braun P 《The Journal of biological chemistry》2006,281(15):10626-10634
Chlorophyll is attached to apoprotein in diastereotopically distinct ways, by beta- and alpha-ligation. Both the beta- and alpha-ligated chlorophylls of photosystem I are shown to have ample contacts to apoprotein within their proteinaceous binding sites, in particular, at C-13 of the isocyclic ring. The H-bonding patterns for the C-13(1) oxo groups, however, are clearly distinct for the beta-ligated and alpha-ligated chlorophylls. The beta-ligated chlorophylls frequently employ their C-13(1) oxo in H-bonds to neighboring helices and subunits. In contrast, the C-13(1) oxo of alpha-ligated chlorophylls are significantly less involved in H-bonding interactions, particularly to neighboring helices. Remarkably, in the peripheral antenna, light harvesting complex (LH2) from Rhodobacter sphaeroides, a single mutation in the alpha-subunit, introduced to eliminate H-bonding to the beta-bacteriochlorophyll-B850, which is ligated in the "beta-position," results in significant thermal destabilization of the LH2 in the membrane. In addition, in comparison with wild type LH2, the expression level of the LH2 lacking this H-bond is significantly reduced. These findings show that H-bonding to the C-13(1) keto group ofbeta-ligated (bacterio)-chlorophyll is a key structural motif and significantly contributes to the stability of bacteriochlorophyll proteins in the native membrane. Our analysis of photosystem I and II suggests that this hitherto unrecognized motif involving H-bonding to beta-ligated chlorophylls may be equally critical for the stable assembly of the inner core antenna of these multicomponent chlorophyll proteins. 相似文献
80.
Alberto Viera Juan Luis Santos María Teresa Parra Adela Calvente Rocío Gómez Roberto de la Fuente José Ángel Suja Jesús Page Julio S. Rufas 《Chromosoma》2009,118(5):575-589
We have analyzed in a true bug, Graphosoma italicum (Pentatomidae, Hemiptera), the temporal and functional relationships between recombination events, synapsis progression,
and SMC1α and SMC3 cohesin axis maturation throughout the male first meiotic prophase. The localization of the histone variant
histone H3 trimethylated at lysine 9 at chromosome ends has allowed us to determine the association of these heterochromatic
domains through prophase I stages. Results highlighted that cohesins provide to be good markers for synapsis progression since
the formation, morphology, and development of the SMC1α and SMC3 cohesin axes resemble the synaptonemal complex dynamics and,
also, that in this species the initiation of recombination precedes synapsis. In addition, we have carried out an accurate
cytological characterization of the diffuse stage, which takes place after pachytene, and also analyzed the presence of the
cohesin subunits, SMC1α and SMC3, and the recombinase RAD51 at this stage. The mechanisms underlying the absence of SMC1α
and SMC3 axes from the diffuse stage onwards are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献