排序方式: 共有29条查询结果,搜索用时 15 毫秒
1.
Summary In addition to mitochondrion-desmosome complexes, peroxisome-desmosome complexes were present in mouse hepatocytes. The latter complexes consisted of a desmosome which was flanked on one or both sides by a peroxisome. Occasional desmosomes were confronted on one side by a peroxisome and on the other by a mitochondrion. It is suggested that the association between organelles and desmosomes is fortuitous, and that no functional significance can be inferred from this association.This work was supported in part by grants from the Heart Association of Northeastern Ohio, Inc., by grant 3C179 from the Cleveland Foundation, by American Cancer Society Institutional Grant In-57-H, and by grant 5 SO1 FR05335-09 from the National Institutes of Health. The expert technical assistance of Merry A. Hetrick and Jeanne Luschin is acknowledged. 相似文献
2.
-Oxidation enzymes were detected both in the mitochondria and microbodies of Arum maculatum L. spadices and Brassica napus L. seeds. It is apparent that the mitochondrial membrane barrier, which remains intact after sucrose-density-gradient centrifugation, prevents rapid access of acyl-GoA substrates to matrix oxidation tes. Thus intact mitochondria showed little -oxidation enzyme activity. Rupturing of the mitochondrial membrane allowed rapid access of acyl CoAs to matrix sites. Consequently, in ruptured mitochondria, high -oxidation enzyme activities were measured.C. Masterson thanks the Science and Engineering Research Council for the award of a postgraduate student maintenance grant. D.R. Thomas and C. Wood thank their relatives for continuing financial support. The authors also thank West Cumberland Farmers Ltd., Hexham, UK for their gift of oilseed rape seeds. 相似文献
3.
Summary Microbodies are ubiquitous organelles in fungal cells, occurring in both vegetative hyphae and spores. They are bounded by a single membrane and may contain a crystalloid inclusion with subunits spaced at regular intervals. Typically, they contain catalase which reacts with the cytochemical stain 3,3-diaminobenzidine to yield an electron-opaque product, urate oxidase,l--hydroxy acid oxidase andd-amino acid oxidase. Their fragility and the necessity to disrupt the tough fungal cell wall before isolating them make them difficult to isolate. Analysis of enzymes in purified or partially purified microbodies from fungi indicates that they participate in fatty acid degradation, the glyoxylate cycle, purine metabolism, methanol oxidation, assimilation of nitrogenous compounds, amine metabolism and oxalate synthesis. In organisms where microbodies are known to contain enzymes of the glyoxylate cycle, they are known as glyoxysomes; where they are known to contain peroxidatic activity, they are known as peroxisomes. In some cases microbodies contain enzymes for only a portion of a pathway or cycle. Thus, they must be involved in metabolic cooperation with other organelles, particularly mitochondria. The number, size and shape of microbodies in cells, their buoyant density and their enzyme contents may vary with the composition of the medium; their proliferation in cells is regulated by the growth environment. The isolation from the same organism of microbodies with different buoyant densities and different enzymes suggests strongly that more than one type of microbody can be formed by fungi. 相似文献
4.
5.
Summary. Division and partitioning of microbodies (peroxisomes) of the green alga Klebsormidium flaccidum, whose cells contain a single microbody, were investigated by electron microscopy. In interphase, the rod-shaped microbody
is present between the nucleus and the single chloroplast, oriented perpendicular to the pole-to-pole direction of the future
spindle. A centriole pair associates with one distal end of the microbody. In prophase, the microbody changes not only in
shape, from a rodlike to a branched form, but also in orientation, from perpendicular to parallel to the future pole-to-pole
direction. Duplicated centriole pairs are localized in close proximity to both distal ends of the microbody. In metaphase,
the elongated microbody flanks the open spindle, with both distal ends close to the centriole pair at either spindle pole.
The microbody further elongates in telophase and divides after septum formation (cytokinesis) has started. The association
between the centrioles and both distal ends of the microbody is maintained throughout mitosis, resulting in the distal ends
of the elongated microbody being fixed at the cellular poles. This configuration of the microbody may be favorable for faithful
transmission of the organelle during cell division. After cytokinesis is completed, the microbody reverts to the perpendicular
orientation by changing its shape. Microtubules radiating from the centrosomes flank the side of the microbody throughout
mitosis. The close association of centrosomes and microtubules with the microbody is discussed in respect to the partitioning
of the microbody in this alga.
Correspondence: H. Hashimoto, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba,
Meguro-ku, Tokyo 153-8902, Japan.
Present address: M. Honda, Department of Computational Biology, Graduate School of Frontier Sciences, University of Tokyo,
Kashiwa, Chiba, Japan. 相似文献
6.
Leão-Helder AN Krikken AM Gellissen G van der Klei IJ Veenhuis M Kiel JA 《FEBS letters》2004,577(3):491-495
ATG genes are required for autophagy-related processes that transport proteins/organelles destined for proteolytic degradation to the vacuole. Here, we describe the identification and characterisation of the Hansenula polymorpha ATG21 gene. Its gene product Hp-Atg21p, fused to eGFP, had a dual location in the cytosol and in peri-vacuolar dots. We demonstrate that Hp-Atg21p is essential for two separate modes of peroxisome degradation, namely glucose-induced macropexophagy and nitrogen limitation-induced microautophagy. In atg21 cells subjected to macropexophagy conditions, sequestration of peroxisomes tagged for degradation is initiated but fails to complete. 相似文献
7.
A new procedure was used to purify the peroxisomal matrix enzyme hydroxypyruvate reductase (HPR) from green leaves of pumpkin (Cucurbita pepo L.) and spinach (Spinacia oleracea L.). Monospecific antibodies were prepared against this enzyme in rabbits. Immunoprecipitation of HPR from watermelon (Citrullus vulgaris Schrad.) yielded a single protein with a subunit molecular weight of 45 kDa. Immunohistochemical labeling of HPR was found exclusively in watermelon microbodies. Isolated polyadenylated mRNA from light-grown watermelon cotyledons was injected into Xenopus laevis oocytes. The heterologous in-vivo translation product of HPR exhibited the same molecular weight as the immunoprecipitate from watermelon cotyledons, indicating the lack of a cleavable extra sequence. The watermelon HPR translated in oocytes was imported into isolated glyoxysomes from castor bean (Ricinus communis L.) endosperm and remained resistant to proteolysis after the addition of proteinase K. The HPR did not change its apparent molecular weight during sequestration; however, it may have changed its conformation.Abbreviations HPR
hydroxypyruvate reductase
- PMSF
phenylmethylsulfonyl fluoride
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis 相似文献
8.
Visualization of the microbody division inCyanidioschyzon merolae with the fluorochrome brilliant sulfoflavin 总被引:1,自引:0,他引:1
M. Miyagishima R. Itoh K. Toda H. Takahashi H. Kuroiwa T. Kuroiwa 《Protoplasma》1998,201(1-2):115-119
Summary A novel procedure is described for fluorescence staining of microbodies, which can be applied quickly and easily. We developed this technique of microbody staining with the unicellular red algaCyanidioschyzon merolae. Cyanidioschyzon merolae only contains a single chloroplast, mitochondrion, and microbody per cell, and the mitotic cycle and the organelle division cycle are easily synchronized. Knowing that the concentration of H2O2 in the microbody is higher than it is in the cytosol and other cell components, we attempted to visualize the microbody by using fluorescence microscopy to detect H2O2. Brilliant sulfoflavin (BSF), used for detecting Fe2+ in analytical chemistry, fluoresces when it reacts with Fe2+ and H2C2. We were able to specifically stain microbodies with BSF, under acidic conditions (pH 3.0 or pH 2.5) with blue-light excitation. Using this procedure, we observed division of the microbody and the effect of aphidicolin on the microbody. We also discovered that microbody division is regulated by the cell nucleus and follows division of the cell nucleus. 相似文献
9.
Shin-ya Miyagishima Ryuuichi Itoh Kyoko Toda Haruko Kuroiwa Mikio Nishimura Tsuneyoshi Kuroiwa 《Planta》1999,208(3):326-336
The proliferation cycle of the microbody was studied in the primitive red alga Cyanidioschyzon merolae, which contains one microbody per cell. Cells were synchronized with a dark/light cycle, and the morphology of the microbody
and its interaction with other organelles were observed three-dimensionally by fluorescence microscopy, transmission electron
microscopy, and computer-assisted three-dimensional reconstruction of serial thin sections. The microbody in interphase cells
is a sphere of 0.3 μm in diameter without a core. In M-phase, the microbody passes through a series of irregular shapes, in
the order rod, worm, branched, H-shaped and dumbbell, and symmetric fission occurs just before cytokinesis. The microbody
duplicates its volume in M-phase and three-dimensional quantitative analysis revealed that its surface area increases before
its volume does. The microbody touches the mitochondrion and the chloroplast throughout its proliferation cycle, except briefly
in interphase cells, winding around the divisional plane of the mitochondrion at one phase. Immunocytochemical labeling of
catalase as a marker of matrix proteins of the microbody revealed that the duplication of catalase occurs in tandem with the
volume increase. While no specific apparatus was identified in the microbody divisional areas, we identified an electron-dense
apparatus about 30–50 nm in diameter between the microbody and the mitochondrion that may play a role in segregating the daughter
microbodies. These results are the first characterization to show the morphological changes of one microbody in a one-microbody
alga without proliferation-inducing substrates, which have been used in many studies, and clearly show that two daughter microbodies
arise by binary fission of the pre-existing microbody.
Received: 11 November 1998 / Accepted: 22 December 1998 相似文献
10.
Shin-ya Miyagishima Ryuuichi Itoh Kyoko Toda Haruko Kuroiwa Tsuneyoshi Kuroiwa 《Planta》1999,207(3):343-353
The time courses of chloroplast and mitochondrial division and the morphological changes in the plastid-dividing ring (PD
ring) and mitochondrion-dividing ring (MD ring) during chloroplast and mitochondrial division were studied in Cyanidioschyzon merolae De Luca, Taddei and Varano. To accomplish this, chloroplast and cell division of living cells were continuously video-recorded
under light microscopy, and the morphological changes in the PD and MD rings were analyzed quantitatively and three-dimensionally
by transmission electron microscopy (TEM). Under the light microscope, the diameters of the chloroplast and the cell decreased
at uniform velocities, the speed depending on the temperature. To study in detail the sequential morphological change of the
mitochondrion in M phase and the contractile mechanism in the divisional planes of the chloroplast and the mitochondrion,
we observed the PD and MD rings, which are believed to promote contraction, under TEM, using the diameter of the chloroplast
as an index of the time. Three PD rings (an outer PD ring on the cytoplasmic face of the outer envelope, a middle PD ring
in the intermembrane space, and an inner PD ring on the stromal face of the inner envelope) were clearly observed, but only
the outer MD ring could be observed. The PD ring started to contract soon after it formed, while the contraction of the MD
ring did not occur immediately after formation, but was delayed until the contraction of the PD ring was almost complete.
Once the MD ring began to contract, the rate of decrease of its circumference was 4 times as high as that of the PD ring.
As the outer PD and MD rings contracted, they grew thicker and maintained a constant volume, while the thickness of the inner
PD ring did not change and its volume decreased at a constant rate with contraction. In the early stage of contraction, the
widths of the three PD rings increased in order, from the outer to the inner ring. With contraction, their widths changed
at different rates until they came to have much the same width. In cross-section, the MD ring was wider where it was next
to the chloroplast than at the opposite side, adjacent to the nucleus in the early stage of contraction. By the late stage,
the widths of the two sides became equal. In our observations, the microbody elongated along the outer MD ring and touched
the outer PD ring during contraction of the PD and MD rings. These results clearly revealed differences between the mode of
contraction of the outer, middle, and inner PD rings, and between the PD and the MD rings. They also revealed the coordinated
widening of the three PD rings, and suggested that the microbody plays a role in the contraction of the PD and MD rings.
Received: 1 July 1998 / Accepted: 1 September 1998 相似文献