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Systematics of the enigmatic kathablepharids, including EM characterization of the type species, Kathablepharis phoenikoston, and new observations on K-remigera comb. nov.

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PROTIST 1999年第1期150卷 43-59页

作者： Clay, B Kugrens, P Colorado State Univ Dept Biol Ft Collins CO 80523 USA

The colorless flagellate Kathablepharis has consisted of five species based on light microscopic studies, and the ultrastructure of the type species, Kathablepharis phoenikoston, is described for the first time. The heterotrophic, marine flagellate Leucocryptos consisted of two species, but additional ultrastructural details for one of these, Kathablepharis remigera comb, nov. (= Leucocryptos remigera Vors), indicates that it should be transferred to Kathablepharis. The cellular structure of these two species is similar to previously studied kathablepharids. However, there is variation in the feeding apparatus and cytoskeleton. The feeding apparatus of both species has a cytostome, a cytostomal ring, and cytopharyngeal rings. The cytoskeleton consists of inner microtubular arrays and outer or sub-pellicular microtubular arrays. in addition, several features of the flagellar apparatus are described for K. phoenikoston and K. remigera. The ultrastructure of these two species is compared with other kathablepharids to evaluate their taxonomy and phylogeny. We classify Kathablepharis and Leucocryptos in the family Kathablepharididae incertae sedis.

关键词：细胞骨架/超微结构进化摄食行为鞭毛/超微结构显微镜检查电子扫描原生动物/细胞学原生动物/超微结构动物

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Tropomyosin isoform 5b is expressed in human erythrocytes: implications of tropomodulin-TM5 or tropomodulin-TM5b complexes in the protofilament and hexagonal organization of membrane skeletons

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BLOOD 2000年第4期95卷 1473-1480页

作者： Sung, LA Gao, KM Yee, LJ Temm-Grove, CJ Helfman, DM Lin, JJC Mehrpouryan, M Univ Calif San Diego Dept Bioengn La Jolla CA 92093 USA Univ Calif San Diego Ctr Genet Mol La Jolla CA 92093 USA Univ Arizona Dept Nutr Sci Tucson AZ 85721 USA Cold Spring Harbor Lab Cold Spring Harbor NY 11724 USA Univ Iowa Dept Biol Sci Iowa City IA 52242 USA

The human erythrocyte membrane skeleton consists of hexagonal lattices with junctional complexes containing F-actin protofilaments of approximately 33-37 nm in length. We hypothesize that complexes formed by tropomodulin, a globular capping protein at the pointed end of actin filaments, and tropomyosin (TM), a rod-like molecule of approximately 33-35 nm, may contribute to the formation of protofilaments, We have previously cloned the human tropomodulin complementary DNA and identified human TM isoform 5 (hTM5), a product of the gamma-TM gene, as one of the major TM isoforms in erythrocytes, We now identify TM5b, a product of the alpha-TM gene, to-be the second major TM isoform, TM5a, the alternatively spliced isoform of the (U-TM gene, which differs by 1 exon and has a weaker actin-binding affinity, however, is not present. TM4, encoded by the delta-TM gene, is not present either. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, hTM5 comigrated with the slower TM major species in erythrocyte membranes, and hTM5b comigrated with the faster TM major species. TM5b, like TM5, binds strongly to tropomodulin, more so than other TM isoforms, The 2 major TM isoforms, therefore, share several common features: They have 248 residues, are approximately 33-35 nm long, and have high affinities toward F-actin and tropomodulin. These common features may be the key to the mechanism by which protofilaments are formed. Tropomodulin-TM5 or tropomodulin-TM5b complexes may stabilize F-actin in segments of approximately 33-37 nm during erythroid terminal differentiation and may, therefore, function as a molecular ruler. TM5 and TM5b further define the hexagonal geometry of the skeletal network and allow actin-regulatory functions of TMs to be modulated by tropomodulin, (C) 2000 by The American Society of Hematology.

关键词：氨基酸序列载体蛋白质类/血液载体蛋白质类/化学克隆分子细胞骨架/超微结构红细胞膜/超微结构红细胞/代谢红系祖细胞/代谢红系祖细胞/超微结构微丝蛋白质类/血液微丝蛋白质类/化学分子序列数据蛋白质亚型/血液蛋白质亚型/化学蛋白质亚型/遗传学重组蛋白质类/化学重组蛋白质类/代谢序列比对序列同源性氨基酸原肌球调节蛋白质原肌球蛋白/血液原肌球蛋白/化学原肌球蛋白/遗传学动物人类大鼠

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Helicobacter pylori induces formation of stress fibers and membrane ruffles in AGS cells by rac activation

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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 2000年第1期269卷 247-253页

作者： Palovuori, R Perttu, A Yan, Y Karttunen, R Eskelinen, S Karttunen, TJ Oulu Univ Dept Pathol FIN-90401 Oulu Finland Oulu Univ Dept Microbiol FIN-90401 Oulu Finland Oulu Univ Bioctr Oulu FIN-90401 Oulu Finland

Helicobacter pylori induces signaling cascades leading to changes in cytoskeleton and an inflammatory response. Information on the morphological changes and cytoskeletal rearrangements induced by attachment of the bacterium is contradictory and signal transduction pathways are not well known. Since rho family of small GTPases is known to mediate cytoskeletal response to various extracellular stimuli, and is also involved in several other important signal transduction pathways, we have investigated the role of rac and cdc42 in H. pylori-induced cytoskeletal changes in cultured carcinoma AGS cells. AGS cells grown with serum expressed actin filaments in the form of short stress fibers and thin network at the edges, which were depolymerized by removal of serum. In serum-starved cells both type I and type II strains of H. pylori induced formation of actin filaments and lamellipodia-like structures. Microinjection of active rac induced similar changes, but injection of inactive rac prevented the effects of H. pylori, while active or inactive cdc42 did not have any significant effect. Cytoskeletal effects of H. pylori were inhibited by actinomycin D, but not completely by cycloheximide. These results indicate that rac activation is involved in signal transduction cascade leading to cytoskeletal reorganization induced by H. pylori and that gene activation and synthesis of new proteins is necessary in this process. (C) 2000 Academic Press.

关键词：肌动蛋白类/代谢细菌黏附/生理学放线菌酮/药理学细胞骨架/药物作用细胞骨架/代谢细胞骨架/超微结构更生霉素/药理学螺杆菌幽门/致病力蛋白质合成抑制药/药理学信号传导胃肿瘤/代谢胃肿瘤/微生物学胃肿瘤/病理学肿瘤细胞培养的 cdc42GTP结合蛋白质/代谢 racGTP结合蛋白质类/代谢人类

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Redistribution of cytochrome c precedes the caspase-dependent formation of ultracondensed mitochondria, with a reduced inner membrane potential, in apoptotic monocytes

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AMERICAN JOURNAL OF PATHOLOGY 1999年第2期155卷 607-618页

作者： Dinsdale, D Zhuang, JG Cohen, GM MRC Toxicol Unit Leicester LE1 9HN Leics England

Apoptosis was induced in human monocytic THP,I cells by the use of chemicals with disparate mechanisms of action. Apoptotic cells were characterized by a reduced inner mitochondrial membrane potential, increased cytosolic cytochrome c, ultracondensed mitochondria, condensed chromatin, cytoplasmic inclusions of beta-actin, and fragmentation of the Golgi apparatus. hll of these changes, except the release of cytochrome c, were prevented by caspase inhibition. Cells were separated into two populations, with either normal or lon inner mitochondrial membrane potential, using fluorescence-activated cell sorting. Ultracondensed mitochondria were observed only in the cells with low inner mitochondrial membrane potential, whereas noncondensed mitochondria were found in the cells with a normal inner mitochondrial membrane potential. We have demonstrated a sequence of related biochemical and ultrastructural changes, commencing with the release of mitochondrial cytochrome c, followed by activation of caspases and a reduction of inner mitochondrial membrane potential. These changes involved the formation of ultracondensed but not swollen mitochondria, Thus the release of mitochondrial cytochrome c was not the result of the mitochondrial permeability transition, reduction of inner mitochondrial membrane potential, or rupture of the outer mitochondrial membrane. Discontinuities in the outer membrane of ultracondensed mitochondria may, hen-ever, facilitate the further release of caspase-activating proteins, thereby amplifying the apoptotic process.

关键词：肌动蛋白类/代谢氨基酸氯甲基酮类/药理学细胞凋亡半胱氨酸天冬氨酸蛋白酶/代谢放线菌酮/药理学半胱氨酸蛋白酶抑制剂/药理学细胞色素c组/代谢细胞骨架/超微结构依托泊甙/药理学流式细胞术高尔基体/代谢免疫组织化学膜电位线粒体/代谢线粒体/超微结构单核细胞/代谢单核细胞/超微结构核酸合成抑制剂/药理学蛋白质合成抑制药/药理学肿瘤细胞培养的人类

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Sphingosine 1-phosphate stimulates fibronectin matrix assembly through a Rho-dependent signal pathway

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BLOOD 1999年第9期93卷 2984-2990页

作者： Zhang, QH Peyruchaud, O French, KJ Magnusson, MK Mosher, DF Univ Wisconsin Dept Med Madison WI 53706 USA Univ Wisconsin Dept Biomol Chem Madison WI 53706 USA

Fibronectin matrix assembly is a cell-dependent process mediated by cell surface binding sites for the 70-kD N-terminal portion of fibronectin. We have shown that Rho-dependent cytoskeleton reorganization induced by lysophosphatidic acid (LPA) or the microtubule-disrupting agent nocodazole increases fibronectin binding (Zhang et al, Mol Biol Cell 8:1415, 1997). Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid implicated in mitogenesis and cytoskeletal remodelling. Both LPA and S1P are present in increased amounts in serum as compared with plasma as a result of platelet activation. Addition of S1P to human osteosarcoma MG63 cells or human foreskin fibroblasts increased cell-mediated binding and assembly of fibronectin. MG63 cells expressed the Edg-2 and Edg-4 G-protein-coupled receptors for bioactive lipids, whereas foreskin fibroblasts expressed Edg-2, Edg-3, and Edg-4. The stimulatory effect of S1P on the binding of fibronectin or the N-terminal 70-kD fragment of fibronectin was dynamic and due to increases in both the number and affinity of binding sites. The stimulation of 70-kD fragment binding by nanomolar S1P, like stimulation of binding by LPA or nocodazole, was blocked by inactivation of Rho with C3 exotoxin but not by pertussis toxin-mediated inactivation of Gi. These results indicate a common signal pathway leading to control of cellular fibronectin matrix assembly by bioactive lipids generated during blood coagulation. (C) 1999 by The American Society of Hematology.

关键词：结合部位细胞分裂/药物作用细胞培养的细胞骨架/药物作用细胞骨架/生理学细胞骨架/超微结构细胞外基质/药物作用细胞外基质/生理学成纤维细胞/细胞学成纤维细胞/生理学纤连蛋白类/药物作用纤连蛋白类/生理学 GTP结合蛋白质类/代谢溶血磷脂酶/药理学溶血磷脂素类核蛋白质类/生物合成核蛋白质类/遗传学骨肉瘤紫杉酚/药理学肽碎片/代谢百白咳毒素受体细胞表面受体 G-蛋白偶联受体溶血磷脂酸信号传导/药物作用信号传导/生理学皮肤/细胞学鞘氨醇/类似物和衍生物鞘氨醇/药理学转录因子/生物合成转录因子/遗传学肿瘤细胞培养的毒力因子鲍特菌属/药理学锌指人类男(雄)性

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TREPONEMA-SUCCINIFACIENS SP-NOV, AN ANAEROBIC SPIROCHETE FROM THE SWINE INTESTINE

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ARCHIVES OF MICROBIOLOGY 1979年第3期122卷 231-239页

作者： CWYK, WM CANALEPAROLA, E UNIV MASSACHUSETTS DEPT MICROBIOL AMHERST MA 01003 USA

The morphology, the general physiological characteristics and the energy-yielding metabolism of an obligately anaerobic spirochete isolated from the colon of a swine were studied. EM showed that the helical spirochetal cells possessed an outer sheath, a protoplasmic cylinder and 4 periplasmic fibrils in a 2-4-2 arrangement. The spirochete grew in an atmosphere of N2 in prereduced media containing a carbohydrate, NaHCO3, rumen fluid, yeast extract, peptone, L-cysteine and inorganic salts. The spirochete fermented carbohydrates and required substrate amounts of CO2 (HCO3-) for growth. Amino acids were not fermented. Major fermentation products of cells growing with glucose as the substrate and in the presence of CO2 were acetate, formate, succinate and lactate. Small amounts of 2,3-butanediol, pyruvate and acetoin were also formed. Determinations of enzymatic activities in cell extracts and of radioactivity in products formed by growing cells from [1-14C]glucose indicated that this sugar was dissimilated to pyruvate via the Embden-Meyerhof pathway. The spirochetes used a coliform-type clastic reaction to metabolize pyruvate. Determinations of radioactivity in products formed from [14C]NaHCO3 indicated that CO2 was assimilated and used in succinate production. The guanine+cytosine content of the DNA was 36 mol%. This study indicates that this intestinal spirochete represents a new Treponema sp. It is proposed that the new species be named T. succinifaciens.

关键词：厌氧生活抗菌药/药理学碳水化合物代谢二氧化碳/代谢细胞骨架/超微结构抗药性微生物发酵肠/微生物学丙酮酸盐类/代谢猪/微生物学术语表密螺旋体属/分类密螺旋体属/生理学密螺旋体属/超微结构动物

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Ultrastructural analysis of Phytomonas species from Euphorbia pinea reveals trans-cytoplasmic filaments 10 nm in diameter

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PARASITOLOGY RESEARCH 2000年第10期86卷 843-850页

作者： Page, AM Lagnado, JR Southampton Gen Hosp Biomed Imaging Unit Southampton SO16 6YD Hants England Univ London Royal Holloway & Bedford New Coll Sch Biol Sci Div Biochem Egham TW20 0EX Surrey England

Phytomonas sp. derived from Euphorbia pinea are digenetic plant trypanosomes that are transmitted by the squashbug Stenocephalus agilis and exist exclusively as promastigotes. The stable sub-pellicular microtubular array, the flagellar axoneme and the paraflagellar rod represent the major cytoskeletal components common to all trypanosomes. The work described in this paper examines in detail the ultrastructural morphology of the organism and highlights a number of novel structural features, and in particular, the presence of some detergent-resistant proteins which take the form of bundles of trans-cytoplasmic filaments of ca, 10 nm in diameter, seen in cells from both log- and stationary-phase cultures. The ultrastructural morphology and immunological cross-reactivity of these filaments are described, and their relationship to filamentous bundles previously reported in stationary-phase cultures of Crithidia fasciculata and to intermediate filaments of animal cells is discussed.

关键词：短膜虫属/超微结构细胞骨架/超微结构大戟科/寄生虫学植物疾病/寄生虫学原虫蛋白质类/分离和提纯锥虫亚目/超微结构动物

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Birth of piglets after transfer of embryos cryopreserved by cytoskeletal stabilization and vitrification

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BIOLOGY OF REPRODUCTION 2000年第3期62卷 564-570页

作者： Dobrinsky, JR Pursel, VG Long, CR Johnson, LA USDA ARS Germplasm & Gamete Physiol Lab Beltsville MD 20705 USA USDA ARS Gene Evaluat & Mapping Lab Beltsville MD 20705 USA

Pig embryos suffer severe sensitivity to hypothermic conditions, which limits their ability to withstand conventional cryopreservation. Research has focused on high lipid content of pig embryos and its role in hypothermic sensitivity, while little research has been conducted on structural damage. Documenting cytoskeletal disruption provides information on embryonic sensitivity and cellular response to cryopreservation. The objectives of this study were to document microfilament (MF) alterations during swine embryo vitrification, to utilize an MF inhibitor during cryopreservation to stabilize MF, and to determine the developmental competence of cytoskeletal-stabilized and vitrified pig embryos. Vitrified morulae/early blastocysts displayed MF disruptions and lacked developmental competence after cryopreservation;hatched blastocysts displayed variable MF disruption and developmental competence. Cytochalasin-b did not improve morula/early blastocyst viability after vitrification;however, it significantly (P < 0.05) improved survival and development of expanded and hatched blastocysts. After embryo transfer, we achieved pregnancy rates of almost 60%, and litter sizes improved from 5 to 7.25 piglets per litter. This study shows that the pig embryo cytoskeleton can be affected by vitrification and that MF depolymerization prior to vitrification improves blastocyst developmental competence after cryopreservation. After transfer, vitrified embryos can produce live, healthy piglets that grow normally and when mature are of excellent fecundity.

关键词：胚泡/药物作用胚泡/免疫学细胞膜/药物作用细胞膜/超微结构低温保存/方法细胞松弛素B/药理学细胞骨架/超微结构胚胎移植受精体外产仔数微丝/药物作用微丝/超微结构妊娠率猪动物女(雌)性妊娠

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Pan1p, End3p, and Sla1p, three yeast proteins required for normal cortical actin cytoskeleton organization, associate with each other and play essential roles in cell wall morphogenesis

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MOLECULAR AND CELLULAR BIOLOGY 2000年第1期20卷 12-25页

作者： Tang, HY Xu, J Cai, MJ Natl Univ Singapore Inst Mol & Cell Biol Singapore 117609 Singapore

The EH domain proteins Pan1p and End3p of budding yeast have been known to form a complex in vivo and play important roles in organization of the actin cytoskeleton and endocytosis. In this report, we describe new findings concerning the function of the Pan1p-End3p complex. First, we found that the Pan1p-End3p complex associates with Sla1p, another protein known to be required for the assembly of cortical actin structures. Sla1p interacts with the first long repeat region of Pan1p and the N-terminal EH domain of End3p, thus leaving the Pan1p-End3p interaction, which requires the second long repeat of Pan1p and the C-terminal repeat region of End3p, undisturbed. Second, Pan1p, End3p, and Sla1p are also required for normal cell wall morphogenesis. Each of the Pan1-4, sla1 Delta, and end3 Delta mutants displays the abnormal cell wall morphology previously reported for the act1-1 mutant. These cell wall defects are also exhibited by wild-type cells overproducing the C-terminal region of Sla1p that is responsible for interactions with Pan1p and End3p. These results indicate that the functions of Pan1p, End3p, and Sla1p in cell wall morphogenesis may depend on the formation of a heterotrimeric complex. Interestingly, the cell wall abnormalities exhibited by these cells are independent of the actin cytoskeleton organization on the cell cortex, as they manifest despite the presence of apparently normal cortical actin cytoskeleton, Examination of several act1 mutants also supports this conclusion. These observations suggest that the Pan1p-End3p-Sla1p complex is required not only for normal actin cytoskeleton organization but also for normal cell wall morphogenesis in yeast.

关键词：肌动蛋白类/代谢载体蛋白质类/生物合成载体蛋白质类/遗传学细胞壁/遗传学细胞壁/代谢细胞壁/超微结构细胞支架蛋白质类细胞骨架/遗传学细胞骨架/代谢细胞骨架/超微结构真菌蛋白质类/生物合成真菌蛋白质类/遗传学基因表达调控真菌微丝蛋白质类酿酒酵母菌/遗传学酿酒酵母菌/代谢酿酒酵母菌/超微结构酿酒酵母蛋白质类

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Ultrastructural observations of astrocyte end-feet in the rat central nervous system

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JOURNAL OF NEUROCYTOLOGY 1998年第6期27卷 431-440页

作者： Nakazawa, E Ishikawa, H Gunma Univ Sch Med Dept Anat Maebashi Gumma 3718511 Japan

Astrocytic end-feet in the rat CNS were studied by thin-section electron microscopy. Astrocyte processes that enclose neuronal elements extended to blood vessels and the pia mater, where the processes expanded to form end-feet or glial limiting membranes. At the end-feet, cell junctions such as gap junctions and desmosome-like junctions were formed between the astrocyte processes. The end-foot plasma membrane facing the basal lamina was undercoated with electron-dense, layered materials, with an internal substructure of filamentous networks, with which bundles of glial filaments (GFs) appeared to be closely associated via fine filamentous structures, often showing a hemi-desmosome-like appearance. In specimens treated with Triton X-100. the internal substructure of the undercoat was better visualized and the association with GFs was well preserved. At the end-feet, some unique tubular structures were found in spatial relationship to the plasmalemmal undercoat. Plectin visualized by immunofluorescence was localized to astrocytes and their processes, especially at the end-feet facing the pia mater. Immunoelectron microscopy located plectin on fine filamentous structures lying between GFs and the plasmalemmal undercoat. These observations suggest that plasmalemmal undercoats at the astrocyte end-feet may serve as attachment sites of GFs to the plasma membrane and that plectin may be involved in such attachment.

关键词：星形细胞/代谢星形细胞/超微结构脑/代谢脑/超微结构细胞膜/超微结构中枢神经系统/代谢中枢神经系统/超微结构小脑/代谢小脑/超微结构细胞骨架/超微结构神经胶质原纤维酸性蛋白质/代谢免疫印迹法中间丝蛋白质类/代谢中间丝/超微结构显微镜检查荧光显微镜检查免疫电子微管/超微结构视神经/代谢视神经/超微结构网蛋白质大鼠 Wistar 动物大鼠

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