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181.
Change in the activity of lectins in cell structure of winter wheat crown under the action of low-temperature hardening and fusicoccin 总被引:2,自引:0,他引:2
Haemagglutinating activity was determined in cell walls and total cell organelles of crown cells of Winter wheat (Triticum aestivum L. ) plants. The effect of fusicoccin (FC) was investigated using fractions obtained from plants hardened for 7 days at 2 degrees C and from untreated plants. FC concentration (5x10(-7) m) increased the frost resistance of the plants. The temporal pattern of lectin activity during hardening could be described by a single-peak curve. In the cell wall fraction, the highest activity manifested itself after one-day hardening, and in the fraction of organelles it peaked after five-days hardening. The carbohydrate specificity of lectins also changed during hardening; cell wall lectins completely lost their capacity for interaction with uridine diphosphoglucose, glucose 6-phosphate, D-galactosamine, and N-acetylglucosamine and the lectins of organelles retained some affinity only for amino sugars. After hardening the test plants, the activity of the lectins increased substantially in the cell walls and plastids, decreased in the nuclei, and was practically flat in mitochondria and microsomes. Consequently, low temperature and FC with their antistress effect improved frost resistance and stimulated the activity of the lectins of some cell structures of the tillering node of winter wheat. A similar action of low temperature and FC in increasing the activity of lectins of plastids was found. Further information was obtained on the subcellular localization of lectins providing additional information on their possible participation in the development of frost resistance of winter wheat. 相似文献
182.
183.
MARIA A. RUDZINSKA 《The Journal of eukaryotic microbiology》1974,21(5):721-728
SYNOPSIS. Young organisms of Tokophrya infusionum starved for several hr, are best suited for a study of the fine structure of this organism including the distribution of its organelles. Acid phosphatase was localized by a combined electron microscopy and cytochemical approach using modified Gomori methods. The enzyme was found in small dense bodies, spheroid vesicles, missile-like bodies, rough-surfaced endoplasmic reticulum, residue and autophagic vacuoles. The small dense bodies are thought to be primary lysosomes since electron micrographs show a) a continuity between the membrane of the rough-surfaced endoplasmic reticulum and that of the dense bodies and b) a connection between the contents of both structures when the dense bodies form from the endoplasmic reticulum. 相似文献
184.
Abstract: 45 Ca2+ uptake measurements were performed on intact and osmotically lysed synaptosomes from rat brain to study the possible influence of prostaglandins (PGs) on Ca2+ movements into and within the nerve endings. The K+ -induced 45 Ca2+ uptake of intact synaptosomes was not influenced by several inhibitors of PG synthesis. 45 Ca2+ uptake in lysed synaptosomal preparations was promoted by ATP and seemed to be largely attributable to mitochondria, as it was inhibited by mitochondrial poisons. This Ca2+ uptake was strongly reduced by PG synthesis inhibitors but also by PG precursor fatty acids. Both PG synthesis inhibitors and precursors, according to their relative efficacy in blocking Ca2+ uptake, were able to induce Ca2+ efflux from preloaded intrasynaptosomal organelles. The PGs E2 , F2α , D2 , and thromboxane B2 were without effect on 45 Ca2+ uptake in lysed synaptosomal preparations. On the basis of our results it does not seem likely that PGs influence Ca2+ availability by modulating Ca2+ fluxes into or within the nerve endings. The observed inhibitory effects of PG synthesis inhibitors and precursors on the intrasynaptosomal Ca2+ uptake might be due to unspecific impairment of mitochondrial functions. 相似文献
185.
Edward K. Novak Frederick Wieland Gerald P. Jahreis Richard T. Swank 《Biochemical genetics》1980,18(5-6):549-561
Melanosomes and lysosomes share structural and biosynthetic properties. Three mouse pigment mutants, ruby-eye, ruby-eye-2-J, and maroon, have abnormally high concentrations of kidney lysosomal enzymes. Concentrations of kidney nonlysosomal enzymes and of liver and serum lysosomal enzymes are normal. By light microscopy the mutants have normal kidney lysosome morphology. It does not appear that the mutant genes cause an increased rate of production of lysosomes since the increased kidney -glucuronidase concentration is not accompanied by a corresponding increase in rate of synthesis. The common defect in all mutants is a decreased rate of secretion of lysosomal enzymes from kidney into urine. Eight mouse pigment mutants are now known which affect both melanosome and lysosome function. They should serve as useful models for the study of the biogenesis, structure, and processing of these and other subcellular organelles.This work was supported in part by United States Public Health Service Research Grant GM-19521 and by National Science Foundation Grant PCM77-24804. E. K. N. was supported in part by United States Public Health Service Grant GM07093-03. F. W. was a high school student in the summer program supported by National Science Foundation Grant SP177-26980. 相似文献
186.
Marisa Brini Lucia Pasti Carlo Bastianutto Marta Murgia Tullio Pozzan Rosario Rizzuto 《Luminescence》1994,9(3):177-184
We have recently developed a new method for monitoring Ca2+ concentrations in defined cell compartments. The cDNA encoding the Ca2+-sensitive photoprotein aequorin has been modified in order to include specific targeting sequences and expressed in eukaryotic cells; the recombinant protein, specifically located inside the cells, has allowed the direct study of mitochondrial and nuclear Ca2+ concentrations in living cells. The principles, and the application, of this new methodology are discussed in this article. 相似文献
187.
The biogenesis, organization and function of the rhoptries are not well understood. Antisera were prepared to synthetic peptides prepared as multiple antigenic peptides (MAPs) obtained from a Plasmodium yoelii merozoite rhoptry proteome analysis. The antisera were used in immunofluorescence and immunoelectron microscopy of schizont-infected erythrocytes. Twenty-seven novel rhoptry proteins representing proteases, metabolic enzymes, secreted proteins and hypothetical proteins, were identified in the body of the rhoptries by immunoelectron microscopy. The merozoite rhoptries contain a heterogeneous mixture of proteins that may initiate host cell invasion and establish intracellular parasite development. 相似文献
188.
Noizet M Harrabi F Vijayalakshmi M Galbraith D Thomas D Thomasset B 《Biotechnology journal》2008,3(3):392-402
The expression of a fusion protein formed between the avian infectious bronchitis virus M protein and the bacterial enzyme beta-glucuronidase (GUS) in plants promotes the formation of new organization of the endoplasmic reticulum in tobacco plants. This unusual organization of the membranes, never present in nontransformed plants, has been explained by the oligomerization of the GUS domains of the IBVM-GUS fusion proteins. These specific organized membranes could have broad implications for biotechnology since their formation could be used as a mechanism for retaining and accumulating resident proteins in specific and discrete membrane compartments. In this study, we have shown that the unusual organization of native membranes due to overexpression of the IBVM-GUS fusion gene in tobacco transgenic plants and calli is present at higher levels in plant cell suspensions than in plant tissues. In these cell suspensions, IBVM-GUS protein was continuously synthesized and accumulated throughout the cell culture. An enrichment of the chimeric IBVM-GUS protein corresponding to a five-fold increase in the microsomal fractions was achieved and the GUS enzyme did not show any modification on enzyme kinetics. However, the GUS activity could be differentially distributed in the fractions eluted at different pH suggesting differences in the surface topography of histidine residues for this recombinant GUS. 相似文献
189.
Structure and function of mammalian cilia 总被引:3,自引:1,他引:2
In the past half century, beginning with electron microscopic studies of 9 + 2 motile and 9 + 0 primary cilia, novel insights have been obtained regarding the structure and function of mammalian cilia. All cilia can now be viewed as sensory cellular antennae that coordinate a large number of cellular signaling pathways, sometimes coupling the signaling to ciliary motility or alternatively to cell division and differentiation. This view has had unanticipated consequences for our understanding of developmental processes and human disease. 相似文献
190.
Sant'Anna C Parussini F Lourenço D de Souza W Cazzulo JJ Cunha-e-Silva NL 《Histochemistry and cell biology》2008,130(6):1187-1198
Trypanosoma cruzi epimastigote forms concentrate their major protease, cruzipain, in the same compartment where these parasites store macromolecules
obtained from medium and for this ability these organelles were named as reservosomes. Intracellular digestion occurs mainly
inside reservosomes and seems to be modulated by cruzipain and its natural inhibitor chagasin that also concentrates in reservosomes.
T. cruzi mammalian forms, trypomastigotes and amastigotes, are unable to capture macromolecules by endocytosis, but also express cruzipain
and chagasin, whose role in infectivity has been described. In this paper, we demonstrate that trypomastigotes and amastigotes
also concentrate cruzipain, chagasin as well as serine carboxypeptidase in hydrolase-rich compartments of acidic nature. The
presence of P-type proton ATPase indicates that this compartment is acidified by the same enzyme as epimastigote endocytic
compartments. Electron microscopy analyzes showed that these organelles are placed at the posterior region of the parasite
body, are single membrane bound and possess an electron-dense matrix with electronlucent inclusions. Three-dimensional reconstruction
showed that these compartments have different size and shape in trypomastigotes and amastigotes. Based on these evidences,
we suggest that all T. cruzi developmental stages present lysosome-related organelles that in epimastigotes have the additional and unique ability of
storing cargo. 相似文献