ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00973.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—This review has been collectively written. The contribution of the authors is mentioned for each part. References have been grouped at the end of the review. The objective of this review is to outline the principle of the method for electron microscopy, to emphasize the major applications and recent developments of this technique for DNA detection and finally to compare this technique with some other methods of DNA detectio

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00974.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—The Feulgen‐like osmium ammine‐SO2method developed by Cogliati and Gautier (CR Acad Sci Ser D1973, 276, 3041–3044) stains the DNA at the ultrastructural level. Compared to several other techniques for detecting DNA, this method remains the only one revealing the configuration of the DNA molecules within the cell whatever their compactness. In the present article we summarize the results we obtained with the osmium ammine method in the study of the fate of viral genomes along the infectious cycles in several DNA virus infected cells including adenovirus, herpes simplex virus, simian virus 40 and poxvirus. The results are discussed in relation to the replicative and transcribing activities of vi

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00975.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—Ultra‐thin sections ofChironomussalivary glands were stained in a non‐Feulgen procedure with osmium ammine‐B and imaged at several electron energy‐loss windows. For two types of RNP‐containing structures (ieBalbiani ring granules and endoplasmic reticulum), a significant spatial correlation was observed between stain distribution and net phosphorus distribution. Non‐Feulgen osmium ammine‐B staining does not require the use of ultra‐thin sections and can approximate the distribution of nuclei

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00976.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—Dinoflagellate protists constitute an original eukaryotic phylum and have an ancestor in common with ciliates. They are important tools in studies of structure and function of the nucleus because they present a mixing of prokaryotic characteristics such as chromatin devoid of histones and nucleosomes, eukaryotic characteristics such as the presence of a nuclear membrane, nucleoli and AgNOR‐like proteins and original characteristics of their own. Among them are the permanent compaction of the chromosomes, the presence of a nuclear envelope during the whole cell cycle, rare bases in their DNA, as well as an original mitosis. We have studied the distribution of the nuclear argyrophilic proteins (AgP) in three genera of Dinoflagellates (Prorocentrum, CrypthecodiniumandAmphidinium) by means of light microscopy (LM) and electron microscopy (EM), using cytochemical silver staining and immunocytochemical reactions following various preparation procedures. By means of the silver staining reaction, we determined by LM the distribution of nucleoli in the three non‐synchronized cell populations and localized by EM the presence of AgP. These are always found in the nucleolar fibrillo‐granular compartment (FG) and partly in the chromosomes and in the nucleolar UCh (unwound region of the nucleolar chromosome corresponding to the NOR); the chromosomes and the UCh are always stained inP micans, under special conditions inC cohniibut never inA carterae. To determine whether these nucleolar and chromosomal proteins are similar or different, we modified the conditions of the silver staining reaction by acidic, alkaline or enzymatic pretreatments and changes in the reaction's temperature. Our results suggested that these proteins belong to different groups. We have characterized one of these proteins using a mammalian anti‐B23 Ab inP micanscells. Positive labeling was mostly detected in chromosomes and UCh and in a smaller amount in the nucleolar FG and G compartments, co‐locating with end‐products of the silver staining reaction. This suggests that: i) one among the dinoflagellate chromosomal AgP is analogous to the B23 mammalian protein; and ii) this B23‐like protein is probabl

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00977.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—Thein situdistribution of phosphorus in perichromatin granules (PCGs), and in the surrounding nucleoplasm was investigated in rat liver cells by means of electron spectroscopic imaging of unstained preparations. A 2–3 nm fibril containing high concentration of phosphorus was found to be the main substructural feature of the PCGs revealed in the maps of phosphorus. This fibril is folded within the PCG with no apparent order. Fibrils of similar diameter and phosphorus content were also found in both the halo surrounding the PCG and dispersed in the nucleoplasm. Some of such fibrils are in continuity with those occurring within PCGs. Sometimes these fibrils are grouped forming a stalk connecting the PCG to chromatin. Some stalked PCGs are U‐shaped or kidneyshaped, resembling Balbiani ring granules in the process of formation as observed inChironomussalivary gland cell nuclei. The external fibrils are interpreted as perichromatin fibrils considered to be precursors of

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00978.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—The purpose of the present study was to investigate potential modulations of endothelial cells of the bovine corpus luteum (CL) during pregnancy. Luteal endothelia of pregnant and non‐pregnant cows were isolated and purity of cultures was verified by flow cytometric quantification of three independent endothelial markers (von Willebrand factor, angiotensin converting enzyme,Bandeiraea simplicifoliaagglutinin I ligands). Different cellular parameters including light and electron microscopical investigation of morphology and growth characteristics as well as quantification of cellular lectin binding sites were compared. Extensive heterogeneity between luteal endothelial cells in pregnant and non‐pregnant animals could be demonstrated, reflected in functional attributes like angiogenic activity, ultrastructural characteristics and the quantitative expression of cellular carbohydrates. Two different morphological types of cells (‘cobblestone growth pattern’ and ‘arcuate growth pattern’) were isolated from the CL of pregnancy as well as from the cyclic CL. Spontaneous angiogenic activities, including cellular migration in band‐like structures and formation of ring‐like structures, were observed in endothelial cells isolated from the CL of pregnant cows exclusively. This strongly suggests that microvascular luteal endothelium of pregnant animals, in contrast to the one of non‐pregnant animals, is able to produce quantitatively and/or qualitatively specific angiogenesis factor(s). Heterogeneity between luteal endothelial cells in the pregnant and non‐pregnant animal could also be demonstrated by quantification of lectin (Bandeiraea simplicifoliaagglutinin I, concanavalin A,Dolichos biflorusagglutinin,Ulex europaeusagglutinin I, wheat germ agglutinin) binding sites: quantitative expression of specific endothelial cell surface carbohydrates could be correlated to be status of pregnancy, thus emphasizing the actual need of quantificat

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00979.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—Intestinal biopsies from patients having genetic disorders of lipoprotein assembly and secretion, such as abetalipoproteinemia (ABL) or Anderson's disease (AD), contain large amounts of lipids which are accumulated in the enterocytes. Determination of the intracellular sites in which the lipids accumulate and to which apolipoproteins the lipids are bound would help to identify the defects in these diseases and further elucidate the mechanisms by which lipoprotein assembly and secretion occur normally. Ultrastructural immunogold labeling, however, is hampered by the poor preservation of the lipids accumulated in the enterocytes of these patients. We have used routine electron microscopy (fixation and ultra‐thin sectioning) along with three methods for immunogold labeling of lipid‐laden enterocytes; ultrathin cryosectioning, low temperature freeze substitution with embedding in Lowicryl K4M, and ultra‐low temperature freeze substitution with embedding in Lowicryl HM20, to establish a protocol for investigating the intestinal tissue from these patients. Ultracryosectioning, while preserving the overall morphology of the lipid laden enterocytes, did not preserve the lipid content and the immunogold labeling of apolipoprotein B (ApoB) appeared dislocated. Freeze substitution and low temperature embedding in Lowicryl K4M, in contrast, appeared to better preserve the lipid and lipoprotein structures; however, the antigenicity of both apoAI and apoB appeared to be lost and no specific labeling could be obtained. Freeze substitution and embedding in Lowicryl HM20 best preserved the lipid and lipoprotein structures while maintaining apoprotein antigenicity. In conclusion, immunogold labeling of apolipoproteins on lipid structures in the lipid‐laden enterocytes of patients with ABL and AD is best obtained by freeze substitution and embedding in Lowi

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00980.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Summary—The morphogenesis of hydrogenosomes in several trichomonad species (Tritrichomonas foetus, Trichomonas vaginalis, Tritrichomonas suis, Trichomonas gallinae, Tritrichomonas augustaandMonocercomonassp) was investigated by transmission electron microscopy of thin sections and freeze‐fracture replicas of whole cells or the isolated organelle. Close proximity, and even continuity, between endoplasmic reticulum and hydrogenosomes was observed. Structures were seen connecting hydrogenosomes to each other and to cytoplasmic structures. Morphological evidence is presented showing that in all the trichomonads here studied, hydrogenosomes, like mitochondria, may divide by two distinct processes: segmentation and partition. In the segmentation process, the hydrogenosome grows, becoming enlongated with the appearance of a constriction in the central portion. Microfibrillar structures appear to help the furrowing process, ending with a total fission of the organelle. In the partition process, the division begins by an invagination of the inner hydrogenosome membrane, forming a transversal septum, separating the organelle matrix into two compartments. We suggest that myelin‐like structures seen either in close contact with or in the vicinity of the hydrogenosomes may be a source of membrane lipids for hydrogenosome g

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1996.tb00981.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY