Journal of ultrastructure research最新文献_第10页

Polymorphism of reconstituted human epidermal keratin filaments: Determination of their mass-per-length and width by scanning transmission electron microscopy (STEM) 重组人表皮角蛋白丝的多态性:扫描透射电镜(STEM)测定其单位长度和宽度

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80010-1

Andreas Engel , Riva Eichner , Ueli Aebi

{"title":"Polymorphism of reconstituted human epidermal keratin filaments: Determination of their mass-per-length and width by scanning transmission electron microscopy (STEM)","authors":"Andreas Engel , Riva Eichner , Ueli Aebi","doi":"10.1016/S0022-5320(85)80010-1","DOIUrl":"10.1016/S0022-5320(85)80010-1","url":null,"abstract":"<div><p>We have determined the mass-per-length (MPL) and the width of unstained freeze-dried reconstituted human epidermal keratin filaments by scanning transmission electron microscopy (STEM). Filaments were reassembled from keratins extracted from four different sources: cultured human epidermal cells (CHEC), human callus (CAL), and the living layers (LL) and stratum corneum (SC) of normal human epidermis. MPL histograms of all four keratin filament types could be fitted by a superposition of two or three Gaussians, with their respective major peaks located between 17 and 20 kDa/nm. We interpreted the multiple MPL peaks to represent different polymorphic forms of the reconstituted filaments. The number of subunits per filament cross section calculated from MPL peak positions, average subunit molecular weight, and an axial repeat of the subunits within the filament of 46.5 nm revealed an average difference between polymorphic variants of 7.5 ± 0.9 subunits. These data suggest that reconstituted human epidermal keratin filaments are made of two to four 8-stranded “protofibrils” (i.e., made of two laterally aggregated 4-stranded protofilaments), in agreement with earlier observations. The average widths of unstained freeze-dried keratin filaments were larger than those of negatively stained filaments: 12.6 nm (9.6 nm) for CHEC, 12.3 nm (9.7 nm) for CAL, 11.6 nm (8.3 nm) for LL, and 11.3 nm (7.9 nm) for SC keratin filaments, with the values in brackets corresponding to negatively stained samples. Assuming the MPL to be proportional to the square of the filament width, there is a good correlation between the MPL and width measurements both for filaments within a given type as well as among those reconstituted from different types of keratin extracts.</p></div>","PeriodicalId":17593,"journal":{"name":"Journal of ultrastructure research","volume":"90 3","pages":"Pages 323-335"},"PeriodicalIF":0.0,"publicationDate":"1985-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0022-5320(85)80010-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13563343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 80

Cell wall and plasma membrane architecture of Butyrivibrio spp. 丁酸弧菌的细胞壁和质膜结构。

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80006-X

T. Dibbayawan, G. Cox, K. Y. Cho, D. Dwarte

引用次数: 6

Cell wall and plasma membrane architecture of Butyrivibrio spp. 丁酸弧菌的细胞壁和质膜结构。

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80006-X

Teresa Dibbayawan , Guy Cox , K. Yip Cho , Dennis M. Dwarte

引用次数: 8

High-resolution electron microscope and computed images of human tooth enamel crystals 人类牙釉质晶体的高分辨率电子显微镜和计算机图像

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80004-6

E.F. Brès , J.C. Barry , J.L. Hutchison

{"title":"High-resolution electron microscope and computed images of human tooth enamel crystals","authors":"E.F. Brès , J.C. Barry , J.L. Hutchison","doi":"10.1016/S0022-5320(85)80004-6","DOIUrl":"10.1016/S0022-5320(85)80004-6","url":null,"abstract":"<div><p>The structure of human enamel crystallites has been studied at a near atomic level by high-resolution electron microscopy. Electron micrographs have been obtained from crystallites present in human enamel with a structure resolution of 0.2 nm in the [0001], [1̄21̄0], [12̄13], [1̄100] and [45̄10] zone axes directions. In most cases it was possible to match the experimental images with images calculated using the atomic positions of mineral hydroxyapatite. However, in some cases a discrepancy between calculated and experimental image detail was observed in the <em>c</em> direction of the [1̄21̄0] and the [1̄100] images. This shows: (i) a structural heterogeneity of the crystals, and (ii) a loss of hexagonal symmetry of the structure. The resolution required to distinguish individual atomic sites in the different zones has been determined, and this will provide a useful basis for future work. As the determination of the “real structure” of biological crystals is of prime importance for the study of calcification mechanisms (crystal growth), biological properties and destructive phenomena of calcified tissues (i.e., dental caries and bone resorption).</p></div>","PeriodicalId":17593,"journal":{"name":"Journal of ultrastructure research","volume":"90 3","pages":"Pages 261-274"},"PeriodicalIF":0.0,"publicationDate":"1985-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0022-5320(85)80004-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14134814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 18

Morphogenesis of Sonchus yellow net virus in cowpea protoplasts 豆黄网病毒在豇豆原生质体中的形态发生

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80007-1

Nikolai A.M. van Beek , Dick Lohuis, Jeanne Dijkstra, Dick Peters

引用次数: 36

Morphogenesis of Sonchus yellow net virus in cowpea protoplasts 黄网病毒在豇豆原生质体中的形态发生

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80007-1

N. V. Beek, D. Lohuis, J. Dijkstra, D. Peters

引用次数: 35

Spermatozoa of Saldid bugs (Insecta, Hemiptera, Leptopodomorpha) 沙虫的精子(昆虫亚目，半翅目，细翅目)

Journal of ultrastructure research Pub Date : 1985-03-01 DOI: 10.1016/S0022-5320(85)80008-3

B. Afzelius, R. Dallai, P. Lindskog

引用次数: 15

Spermiogenesis ofLacerta vivipara 活莱塞塔精子生成

Journal of ultrastructure research Pub Date : 1985-02-01 DOI: 10.1016/0889-1605(85)90110-7

J.L. Courtens , A. Depeiges

{"title":"Spermiogenesis ofLacerta vivipara","authors":"J.L. Courtens , A. Depeiges","doi":"10.1016/0889-1605(85)90110-7","DOIUrl":"https://doi.org/10.1016/0889-1605(85)90110-7","url":null,"abstract":"<div><p>To the common aspects of spermiogenesis in Reptilia, several new organelles are described in the lizard. One or two nuclear pouches, formed by the invagination of the nuclear envelope, contain a substance similar to that of the perinuclear substance. They are formed near the acrosome and follow an helical pathway at the surface of the nucleus. The pouches could be driven by a nuclear ribbon made of six to seven microtubules engaged in the mouth of each pouch. The perinuclear substance, transported by the pouches, is deposited near the posterior part of the nucleus. The evolution of the nuclear pores, and the attachment of the chromatin to the nuclear envelope suggest that the chromatin is twisted inside the nucleus, following the displacement of the nuclear pouches. Adjacent pouches are separated by a lamellar plate, possibly originating from a modified mitochondrion. Untwisting of the nucleus and chromatin is evident at the time the manchette is present. The chromatin fibers become coarser and are progressively aligned parallel to the nuclear axis. The midpiece of the flagellum is very short; it wears 15 mitochondria disposed into three crowns. The ribs of the fibrous sheet are synthesized from the posterior part of the flagellum, anteriorly. A tegosomial sheet is described. It is composed of lipidic droplets that are injected between the two nuclear membranes, prior to the spermiation. A classification of the steps of spermiogenesis is proposed.</p></div>","PeriodicalId":17593,"journal":{"name":"Journal of ultrastructure research","volume":"90 2","pages":"Pages 203-220"},"PeriodicalIF":0.0,"publicationDate":"1985-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0889-1605(85)90110-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72213177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 23

Ciliary resorption and membrane retrieval during morphogenesis in the ciliateEufolliculina uhligi 纤毛虫形态发生过程中纤毛吸收和膜修复

Journal of ultrastructure research Pub Date : 1985-02-01 DOI: 10.1016/0889-1605(85)90105-3

Maria Mulisch , Klaus Hausmann

{"title":"Ciliary resorption and membrane retrieval during morphogenesis in the ciliateEufolliculina uhligi","authors":"Maria Mulisch , Klaus Hausmann","doi":"10.1016/0889-1605(85)90105-3","DOIUrl":"https://doi.org/10.1016/0889-1605(85)90105-3","url":null,"abstract":"<div><p>In this study, two processes of ciliary resorption in the sessile heterotrich ciliate<em>Eufolliculina uhligi</em> are presented. (1) Prior to division,<em>E. uhligi</em> resorbs its oral apparatus. This occurs by the incorporation of axonemes of single cilia into the cytoplasm, and by the formation of a large vacuole, in which the membranellar cilia of the buccal cavity are enclosed. The cilia inside the vacuole are continuously resorbed. After some minutes, this vacuole divides into several smaller ones which accumulate in the opisthe. They are characterized by a progressive lamination and infolding of their membrane; the cilia inside the vacuole degenerate. Morphological similarities and dissimilarities to digestive vacuoles are discussed. (2) Transformation of the motile swarmer into the sessile cell includes lorica secretion as well as resorption of the anterior membraneller cilia. The lorica material is secreted by exocytosis. The vesicular membrane is incorporated into the plasma membrane. The cilia are resorbed by retraction of the axonemes or by lateral fusion with the plasmalemma. The fate of the additional plasma membrane has been studied using cationized ferritin as an exogeneous marker. It could be demonstrated, that at the sites of ciliary resorption and exocytosis plasma membrane is retrieved endocytotically via coated pits. Endocytosis is not restricted to the parasomal sacs, but also occurs at the septae between adjacent alveoli. The internalized membrane moves as small vesicles and/or flattened cisternae from the periphery toward the center of the cell. No fusion of these membraneous elements with secondary lysosomes has been observed 1 h after application of ferritin. The further fate of the internalized membrane is discussed.</p></div>","PeriodicalId":17593,"journal":{"name":"Journal of ultrastructure research","volume":"90 2","pages":"Pages 145-162"},"PeriodicalIF":0.0,"publicationDate":"1985-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0889-1605(85)90105-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72213140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

How to avoid compression: A model study of latex sphere grid sections 如何避免压缩:乳胶球网格截面的模型研究

Journal of ultrastructure research Pub Date : 1985-02-01 DOI: 10.1016/0889-1605(85)90104-1

Jean-Claude Je´sior

{"title":"How to avoid compression: A model study of latex sphere grid sections","authors":"Jean-Claude Je´sior","doi":"10.1016/0889-1605(85)90104-1","DOIUrl":"10.1016/0889-1605(85)90104-1","url":null,"abstract":"<div><p>The parameters which might play a role in the compression of plastic-embedded objects are studied. The compression is measured on spherical polystyrene latex particles, used as markers in the grid sectioning technique. By changing independently the hardness of the latex particles through a controlled electron irradiation and the hardness of the embedding medium, it is shown that compression is a local event depending only on the mechanical properties of the sectioned object and not on the properties of its surrounding materials. It is demonstrated on one hand that the intrinsic resin compression diminishes as resin hardness increases, and on the other hand that the latex compression can be completely eliminated after a preliminary irradiation by electrons (the electron-induced vulcanization is equivalent to a hardening). It is thus concluded that compression could be greatly reduced or eliminated if objects were sufficiently hardened during their preparation. Several preparation procedures for biological specimens are suggested. For comparison latex has also been irradiated 3½ days near a 25 000-Ci<sup>60</sup>Co gamma source and near the core of an 8-MW nuclear reactor: Neither of these irradiations was sufficient to produce a hardening equivalent to that of the electron irradiation.</p></div>","PeriodicalId":17593,"journal":{"name":"Journal of ultrastructure research","volume":"90 2","pages":"Pages 135-144"},"PeriodicalIF":0.0,"publicationDate":"1985-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0889-1605(85)90104-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15180327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22