1,721,024 research outputs found
Nuclear proteins and the onset of cell proliferation in root meristems of Pisum sativum: QP47 a novel acidic protein
No full textA protein named QP47 has been purified from quiescent nuclei of root meristems of Pisum sativum, and used to prepare a polyclonal antibody. Immunolocalization of this protein with fluorescent probes revealed a nuclear distribution of thread-like structures. However, the relationship between the distribution of QP47 immunofluorescence and the structural organization of the chromatin required further investigation. The decrease in content of this protein in the nuclei of embryo cells seems to be correlated with the transition from quiescence to proliferation. QP47 degradation seems to depend upon an increase in the state of its phosphorylation. This protein is not present in normally proliferating cells, or in cells whose cell proliferation has been arrested by starvation or differentiation. It is hypothesized that QP47 may be required specifically during the quiescent period for specific structural organization of the chromatin
Feasibility of organophosphorus pesticide screening in waters with a cholinesterase inhibition test
No full textSpatial arrangement of the fibres in developing and mature endocarp of Luffa cylindrica Roem.
No full textLuffa cylindrica bears peculiar pepo-like fruits, which are characterised by a fibrous endocarp. Mature endocarps, so far utilised as a "vegetable sponge", are the object of studies for packing devices. By means of scanning, flluorescence and confocal microscopes, we investigated the arrangement and composition of the fibres in Luffa endocarps at different developmental stages in order to explain their functional properties
Low concentration of LatB dramatically changes the microtubule organization and the timing of vegetative nucleus/generative cell entrance in tobacco pollen tubes
No full textLow concentration of LatB inhibits not only the actin polymerization, but also induces profound alteration of MT distribution in pollen tubes of Nicotiana tabacum. The short randomly oriented MTs in the apical and subapical regions, became organized as bundles forming subapical rings or basket-like structures, surrounding the apex. Moreover, the depolymerization of AFs in the cortical regions of the apex and subapical region affects the timing of entrance of the vegetative nucleus and generative cell into the pollen tube
The presence of a p53-like protein during pea seed maturation and germination
No full textThe mechanisms that allow monitoring of DNA damage and the activation of repair systems in plants are poorly known. In mammalian cells the tumor suppressor protein p53 plays an important role in the checkpoint pathway induced by DNA damage. In this work, me investigated the presence and distribution of the p53-like protein in pea root tip nuclei and its role during early germination in relation to DNA damage. In pea seed, PFGE and TdT assays show that DNA fragmentation occurs during maturation and dry seed storage, and that this DNA fragmentation is repaired at the beginning of germination before the onset of proliferation. In the same seeds, the p53-like protein was found during maturation and germination. Immunoblotting characterization of this protein led to the identification of a single specific protein of about 94 kDa, more abundant at the beginning of the hydration process than in actively cycling cells. Furthermore, the p53-like protein revealed different nuclear distribution patterns, probably in relation to the formation of DNA fragments in dry seeds, and to the reactivation of repair mechanisms during early germination. These data suggest that the presence of a p53-like protein in quiescent or proliferating, pea embryo is related to DNA damage, and serves for the maintenance of genetic information and the development of normal seedlings
Localization of a nuclear protein (QP47) in cells of embryonic meristems during seed maturation and germination and its distribution among crop plants.
No full textClathrin-dependent and independent endocytic pathways in tobacco protoplasts revealed by labelling with charged nanogold
No full textPositively charged nanogold was used as a probe to trace the internalization of plasma membrane (PM) domains carrying negatively charged residues at an ultrastructural level. The probe revealed distinct endocytic pathways within tobacco protoplasts and allowed the morphology of the organelles involved in endocytosis to be characterized in great detail. Putative early endosomes with a tubulo-vesicular structure, similar to that observed in animal cells, are described and a new compartment, characterized by interconnected vesicles, was identified as a late endosome using the Arabidopsis anti-syntaxin family Syp-21 antibody. Endocytosis dissection using Brefeldin A (BFA), pulse chase, temperature- and energy-dependent experiments combined with quantitative analysis of nanogold particles in different compartments, suggested that recycling to the PM predominated with respect to degradation. Further experiments using ikarugamycin (IKA), an inhibitor of clathrin-dependent endocytosis, and negatively charged nanogold confirmed that distinct endocytic pathways coexist in tobacco protoplasts
Leaf morphology and carbon isotope discrimination values in eyebane (Euphorbia maculata L.)
No full textWithin the Euphorbiaceae, there are species belonging to the C3, C4 and CAM photosynthetic groups. Leaf anatomy and ultrastructure together with carbon isotope discrimination measurements indicated that Euphorbia maculata L., grown and collected in an urban area, is a C4 species ascribable to the NADP-ME photosynthetic type
Cyclin-dependent kinase-like proteins in pea nuclei: their presence and role in cell proliferation
No full textAlthough many putative cdk (cyclin-dependent kinase) homologue genes have been identified in higher plants, their function and involvement in cell proliferation are still unclear. In this work we investigated the presence and distribution of cdk-like proteins in root tip meristem nuclei at different germination times (before, during, and after the onset of cell proliferation) and in nuclei of differentiated leaves. Nuclear cdk-like proteins were found in the root meristem throughout seed germination with a higher amount in actively proliferating cells, but were not detected in differentiated leaf. Characterization of the detected pea cdk-like proteins by immunoblotting led to the identification of two specific principal proteins of 33.2 and 34 kDa with the cdk conserved motif PSTAIRE. The p33.2 protein was also recognized by the anti-human p33(cdk2) antibody, suggesting that the p33.2 and p34 proteins could be pea homologues of human p33(cdk2) and p34(cdk1), involved in the G(1)-S and G(2)-M transitions, respectively. Additional analysis of pea cdk protein localization has shown partial localization of these proteins at DNA replication sites during the G(1) to S transition. These microscopical and biochemical data support the hypothesis that, in pea nuclei as in mammals, many PSTAIRE-cdks are present with different functions related to cell proliferation, one of which is probably involved in the control of the G(1)-S transition
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