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31.
Xavier Roig Isabel S. Novella Ernest Giralt David Andreu 《Letters in Peptide Science》1994,1(1):39-49
Summary The conformation of a peptide that represents antigenic site A of foot-and-mouth disease virus strain C-S8c1 (residues 136–156 of VP1; YTASARGDLAHLTTTHARHLP) has been studied by circular dichroism and compared with three analogs that reproduce amino acid substitutions at position 146 (HisArg, Gln or Asp) which affect antibody recognition. Four other peptides, incorporating replacements at position 147 predicted to maintain (LeuIle, Nle and Ala) or disrupt (LeuGly) helical structure at this site, have also been studied. In aqueous solution or in 4 M urea, the spectra of all eight peptides were typical of aperiodic conformation and independent of concentration or pH. However, upon addition of solvents such as methanol or hexafluoroisopropanol, spectral patterns evidenced significant levels (ca. 50%) of helical structure. The single residue substitutions at positions 146 and 147 caused minor to significant variations in the calculated amount of -helix of the peptides. An attempt to relate these changes in helical content to the antigenic behaviour of the peptides towards five monoclonal antibodies elicited with virus and mapping at site A could not find any straightforward correspondence between the two sets of results. The parent peptide and its His146Arg analog were also analyzed by circular dichroism in the presence of the Fab fragment of SD6, a monoclonal antibody mapping at site A and much less reactive with viruses carrying the referred mutation. Although a peptide-antibody interaction was evident from spectral changes, careful inspection of the difference spectra (peptide-Fab minus Fab) of both peptides failed to detect any significant distinction between them that could be attributed to their different immunoreactivity. While these findings do not necessarily conflict with previous reports that the interaction of antigenic site A with antibodies is mediated to some extent by the adoption of a helix structure, they suggest that, at least for C-serotype viruses, other structural features in addition to a helical conformation are critically involved in antigenic recognition. 相似文献
32.
Russell B. Lingham Keith C. Silverman Gerald F. Bills Carmen Cascales Manual Sanchez Rosalind G. Jenkins Suzanne E. Gartner Isabel Martin Maria T. Diez Fernando Peláez Sagrario Mochales Yu-Lin Kong Richard W. Burg Maria S. Meinz Leeyuan Huang Mary Nallin-Omstead Scott D. Mosser Michael D. Schaber Charles A. Omer David L. Pompliano Jackson B. Gibbs Sheo B. Singh 《Applied microbiology and biotechnology》1993,40(2-3):370-374
Chaetomellic acids A and B, isolated from Chaetomella acutiseta, are specific inhibitors of farnesyl-protein transferase that do not inhibit geranylgeranyl transferase type 1 or squalene synthase. Chaetomellic acids A and B are reversible inhibitors, resemble farnesyl diphosphate and probably inhibit FPTase by substituting for farnesyl diphosphate. Chaetomellic acid production appears to be widespread within the genus Chaetomella.
Correspondence to: R. B. Lingham 相似文献
33.
34.
Over a period of 7 years the biology and phenotypic variability of Chusquea culeou were studied at 5 locations in cool temperate forests of southern Argentina. Excavated rhizomes had an average of 1.1 successful rhizome buds, and an average of 2.1 years elapsed between successive generations of rhizomes. Rhizome buds usually develop within the first four years after a rhizome forms. Height, volume and weight of a culm can be calculated from its diameter 1 m above the ground. Culm size, length of foliage leaf blades, and pattern of secondary branching differed among study sites. Dead culms were numerous and commonly remained erect for more than 7 years after dying. New culm shoots appear in spring and reach full size within a few months. Shoots can grow more than 9 cm/day. Less than half of the shoots survived a year; most were killed by moth larvae. Multiple primary branch buds emerge through the culm leaf sheaths in the second spring. The mean number of branch buds at mid-culm nodes varied between 34.8 and 81.5, and the mean number of primary branches was between 22.8 and 40.8. Number and length of branches, and number and length of foliage leaf blades at each node is related to the position of the node on a culm. Most branches grow about 3 cm and produce 1 to 3 foliage leaves annually. Foliage leaf blades generally live 2 years or more; few survive 6 years. Relative lengths of foliage leaf blades and their spacing along a branch permit recognition of annual cohorts.Both gregarious and sporadic flowering have been reported, and every year a few isolated plants flower and die. Length of the life cycle is unknown. Seedlings require up to 15 years to produce culms of mature size. Foliage branches may live more than 23 years, and culms may survive 33 years. Extensive loss of new shoots to predation suggests that gregarious flowering may be driven by a need to escape parasitism. C. culeou clumps expand slowly. Average annual rate of increase of the number of live culms in a clump was 4.6%. Methods of seed dispersal are undocumented. A dense stand of Chusquea culeou had an estimated phytomass of 179 tons/hectare (dry weight), 28% of which was underground. Net annual production was about 16 t/ha dry weight. 相似文献
35.
Luisa F. Fanjul Isabel Marrero F. Estevez J. Gonzalez J. Quintana Pino Santana C. M. Ruiz De Galarreta 《Journal of cellular physiology》1993,155(2):273-281
In the present investigation, a hCG sensitive glycosyl-phosphatidylinositol (GPI) was isolated from cultured rat granulosa cells obtained from the ovaries of diethylstilbestrol (DES) implanted immature rats. The inositol-phosphoglycan (IPG) moiety of the GPI-lipid contains galactose, glucosamine, and myoinositol as demonstrated by metabolic labelling of granulosa cells for different time periods (5–96 h) with [3H]galactose, [3H]glucosamine, or [3H]myoinositol and treatment of the purified [3H]GPI with phosphatidylinositol-specific phospholipase C. Labelling equilibrium of the GPI-lipid was achieved after 24 h ([3H]galactose and [3H]myoinositol) or 72 h ([3H]glucosamine) incubation, whereas incorporation of other labelled carbohydrates tested ([3H]galactosamine, [3H]mannose, and [3H]sorbitol) was negligible throughout the time period studied. The glucosamine C-1 appears to be linked through a glycosidic bond to the myoinositol molecule of the IPG moiety as revealed by the generation of phosphatidylinositol (PtdIns) after nitrous acid deamination of dual labelled ([3H]glucosamine/[14C]palmitate or [3H]glucosamine/[14C]myristate) glycosyl-phosphatidylinositol. To investigate the fatty acid composition of the diacylglycerol (DAG) backbone of the GPI, granulosa cells were also labelled (5–72 hr) with [14C]linoleate, [3H]myristate, [3H]-oleate, [3H]palmitate, or [3H]stearate and the radioactivity associated with the purified glycosyl-phosphatidylinositol determined. Incorporation of [3H]palmitate and [3H]myristate into the GPI-lipid peaked after 8 h and 24 h of labelling, respectively, and both fatty acids were partially released after PLA2 treatment of the dual labelled ([3H]glucosamine/[14C]palmitate or [3H]glucosamine/[14C]myristate) GPI. In parallel experiments no significant incorporation of labelled stearate, oleate, or linoleic acid into the DAG backbone of the glycosylphosphatidylinositol could be detected. Granulosa cells were also labelled with [3H]glucosamine in the presence of FSH (30 ng/ml), cholera toxin (1 μg/ml), or the membrane permeable cAMP analog (but)2 cAMP (1 mM). Time related increases in GPI-labelling were apparent after 48 h and reached a maximum level (3-, 5-, and 7-fold for FSH, CT, and (but)2 cAMP, respectively) after 72 h in culture. In another set of experiments, granulosa cells were labelled for 72 h with [3H]glucosamine in the presence of (but)2cAMP (1 mM), TPA (10?7 M), or combination thereof. The effect of treatment with the membrane permeable cAMP analog on GPI labelling was prevented in the presence of TPA, whereas no differences in [3H]GPI content could be observed in untreated granulosa cells or cells cultured in the presence of the protein kinase C-activating phorbol ester alone. In cells differentiated with FSH (30 ng/ml for 3 days) to induce LH receptors, treatment with hCG (100 ng/ml) induced a rapid (60 sec) and transient (5 min) decrease in the GPI content, whereas no efect of the hormone on undifferentiated granulosa cells could be observed. The rapid effect elicited by hCG on GPI content and turnover may be an early transduction mechanism involved in the biological effects of LH/hCG in differentiated granulosa cells. © 1993 Wiley-Liss, Inc. 相似文献
36.
Update on proliferation-associated antibodies applicable to formalin-fixed paraffin-embedded tissue and their clinical applications 总被引:8,自引:0,他引:8
Summary This review provides an update on proliferation-associated antibodies applicable to immunohistochemical techniques in formalin-fixed
paraffin-embedded tissue. New insights into proliferating cell nuclear antigen (PCNA) and antibodies to PCNA are presented.
The characterization of the protein recognized by the Ki-67 antibody has enabled production of a new range of antibodies (monoclonal
and polyclonal) which have immunostaining profiles similar to those of the original antibody. A new proliferation-associated
antibody, KiS1, is described. The clinical applications of antibodies to PCNA in human material are summarized, and the limitations
of these studies are discussed. 相似文献
37.
Estaras Matias Ortiz-Placin Candido Castillejo-Rufo Alba Fernandez-Bermejo Miguel Blanco Gerardo Mateos Jose M. Vara Daniel Gonzalez-Cordero Pedro L. Chamizo Sandra Lopez Diego Rojas Adela Jaen Isabel de Armas Noelia Salido Gines M. Iovanna Juan L. Santofimia-Castaño Patricia Gonzalez Antonio 《Journal of physiology and biochemistry》2023,79(1):235-249
Journal of Physiology and Biochemistry - We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells.... 相似文献
38.
Andrew F. Feldman Daniel J. Short Gianotti Jianzhi Dong Isabel F. Trigo Guido D. Salvucci Dara Entekhabi 《Global Change Biology》2023,29(1):110-125
Vegetation cover creates competing effects on land surface temperature: it typically cools through enhancing energy dissipation and warms via decreasing surface albedo. Global vegetation has been previously found to overall net cool land surfaces with cooling contributions from temperate and tropical vegetation and warming contributions from boreal vegetation. Recent studies suggest that dryland vegetation across the tropics strongly contributes to this global net cooling feedback. However, observation-based vegetation-temperature interaction studies have been limited in the tropics, especially in their widespread drylands. Theoretical considerations also call into question the ability of dryland vegetation to strongly cool the surface under low water availability. Here, we use satellite observations to investigate how tropical vegetation cover influences the surface energy balance. We find that while increased vegetation cover would impart net cooling feedbacks across the tropics, net vegetal cooling effects are subdued in drylands. Using observations, we determine that dryland plants have less ability to cool the surface due to their cooling pathways being reduced by aridity, overall less efficient dissipation of turbulent energy, and their tendency to strongly increase solar radiation absorption. As a result, while proportional greening across the tropics would create an overall biophysical cooling feedback, dryland tropical vegetation reduces the overall tropical surface cooling magnitude by at least 14%, instead of enhancing cooling as suggested by previous global studies. 相似文献
39.
Opale Coutant Céline Jézéquel Karel Mokany Isabel Cantera Raphaël Covain Alice Valentini Tony Dejean Sébastien Brosse Jérôme Murienne 《Global Change Biology》2023,29(7):1741-1758
Freshwater ecosystems are among the most endangered ecosystem in the world. Understanding how human activities affect these ecosystems requires disentangling and quantifying the contribution of the factors driving community assembly. While it has been largely studied in temperate freshwaters, tropical ecosystems remain challenging to study due to the high species richness and the lack of knowledge on species distribution. Here, the use of eDNA-based fish inventories combined to a community-level modelling approach allowed depicting of assembly rules and quantifying the relative contribution of geographic, environmental and anthropic factors to fish assembly. We then used the model predictions to map spatial biodiversity and assess the representativity of sites surveyed in French Guiana within the EU Water Framework Directive (WFD) and highlighted areas that should host unique freshwater fish assemblages. We demonstrated a mismatch between the taxonomic and functional diversity. Taxonomic assemblages between but also within basins were mainly the results of dispersal limitation resulting from basin isolation and natural river barriers. Contrastingly, functional assemblages were ruled by environmental and anthropic factors. The regional mapping of fish diversity indicated that the sites surveyed within the EU WFD had a better representativity of the regional functional diversity than taxonomic diversity. Importantly, we also showed that the assemblages expected to be the most altered by anthropic factors were the most poorly represented in terms of functional diversity in the surveyed sites. The predictions of unique functional and taxonomic assemblages could, therefore, guide the establishment of new survey sites to increase fish diversity representativity and improve this monitoring program. 相似文献
40.