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61.
Jackson T Clark S Berryman S Burman A Cambier S Mu D Nishimura S King AM 《Journal of virology》2004,78(9):4533-4540
Field isolates of foot-and-mouth disease virus (FMDV) have been shown to use three alphav integrins, alphavbeta1, alphavbeta3, and alphavbeta6, as cellular receptors. Binding to the integrin is mediated by a highly conserved RGD motif located on a surface-exposed loop of VP1. The RGD tripeptide is recognized by several other members of the integrin family, which therefore have the potential to act as receptors for FMDV. Here we show that SW480 cells are made susceptible to FMDV following transfection with human beta8 cDNA and expression of alphavbeta8 at the cell surface. The involvement of alphavbeta8 in infection was confirmed by showing that virus binding and infection of the transfected cells are inhibited by RGD-containing peptides and by function-blocking monoclonal antibodies specific for either the alphavbeta8 heterodimer or the alphav chain. Similar results were obtained with a chimeric alphavbeta8 including the beta6 cytodomain (alphavbeta8/6), showing that the beta6 cytodomain can substitute efficiently for the corresponding region of beta8. In contrast, virus binding to alphavbeta6 including the beta8 cytodomain (alphavbeta6/8) was lower than that of the wild-type integrin, and this binding did not lead to infection. Further, the alphavbeta6 chimera was recognized poorly by antibodies specific for the ectodomain of alphavbeta6 and displayed a relaxed sequence-binding specificity relative to that of wild-type integrin. These data suggest that the beta6 cytodomain is important for maintaining alphavbeta6 in a conformation required for productive infection by FMDV. 相似文献
62.
Population: a central concept for ecology? 总被引:4,自引:0,他引:4
Alan A. Berryman 《Oikos》2002,97(3):439-442
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Attenuation of the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis results in extended lifespan in many organisms
including mice. Conversely, GH transgenic mice have excess GH action and die prematurely. We have studied bovine (b) GH transgenic
mice (n = 9) and their wild type (WT) littermates (n = 8) longitudinally and have determined several age-related changes. Compared to WT mice, bGH mice lost fat mass, became
hypoglycemic and had lower insulin levels at older ages despite being hyperinsulinemic when young. To examine plasma protein
differences in bGH mice relative to controls, samples at 2, 4, 8, 12 and 16 months of age were analyzed by two-dimensional
gel electrophoresis followed by identification using mass spectrometry. We found several differences in plasma proteins of
bGH mice compared to controls, including increased apolipoprotein E (five isoforms), haptoglobin (four isoforms) and mannose-binding
protein-C (one out of three isoforms), and decreased transthyretin (six isoforms). In addition, clusterin (two out of six
isoforms) and haptoglobin (four isoforms) were up-regulated in bGH mice as a function of age. Finally, alpha-2 macroglobulin
(seven isoforms) was altered in an isoform-specific manner with two isoforms increased and two decreased in bGH mouse plasma
compared to controls. In conclusion, identification of these proteins suggests that bGH mice exhibit an increased inflammatory
state with an adverse lipid profile, possibly contributing to their diminished life expectancy. Also, these newly discovered
plasma proteins may be indicative or ‘biomarkers’ of a shortened lifespan. 相似文献
65.
Cuticle hydrolysis in four medically important fly species by enzymes of the entomopathogenic fungus Conidiobolus coronatus 下载免费PDF全文
M. I. BOGUŚ E. WŁÓKA A. WROŃSKA A. KACZMAREK M. KAZEK K. ZALEWSKA M. LIGĘZA ‐ ŻUBER M. GOŁĘBIOWSKI 《Medical and veterinary entomology》2017,31(1):23-35
Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus–cuticle interactions related to substrate utilization and resistance to host‐specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell‐free filtrate, for which activity of elastase, N‐acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N‐glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions. 相似文献
66.
It is well established that glucocorticoids elevate the production of fibroblast-pneumocyte factor (FPF), which induces type II cells to synthesize surfactant phospholipids. FPF, however, has not been identified and it is not clear whether it is a single factor or a complex mixture of factors. In this study it has been shown that, when lung fibroblasts are exposed to dexamethasone, the concentration of neuregulin-1β (NRG1β) in conditioned medium is elevated 2-fold (P < 0.05), even though NRG1β gene expression is unaffected. This, together with the finding that exposure of type II cells to NRG1β directly stimulates by 3-fold the rate of phospholipid synthesis (P < 0.05), suggests that NRG1β is a component of FPF that promotes lung development. 相似文献
67.
Sackmann-Sala L Berryman DE Munn RD Lubbers ER Kopchick JJ 《Obesity (Silver Spring, Md.)》2012,20(1):101-111
The widespread prevalence of obesity has lead to extensive research on white adipose tissue (WAT), which frequently uses the C57BL/6J mouse strain as a model. In many studies, results obtained in one WAT depot are often extrapolated to all WAT. However, functional differences among WAT depots are now becoming apparent. Thus, to identify the molecular mechanisms responsible for WAT depot-specific differences under "normal" conditions, four C57BL/6J mouse WAT depots (inguinal, mesenteric, epididymal, and retroperitoneal) were analyzed. Depot proteomic profiles, along with weights, protein contents, adipocyte sizes and oxidative stress were determined. Mesenteric WAT had almost twice the protein content of the other depots analyzed. Mean adipocyte size was highest in epididymal and lowest in mesenteric and inguinal depots. The proteome of inguinal WAT displayed low levels of enzymes involved in ATP generation, glucose and lipid metabolism, and antioxidant proteins. Higher levels of these proteins were observed in mesenteric and epididymal WAT, with variable levels in the retroperitoneal depot. Some of these proteins showed depot-specific correlations with plasma levels of insulin, leptin, and adiponectin. In agreement with the proteomic data, levels of the antioxidant protein heat shock protein β1 (HSPβ1) also were lower in inguinal WAT when analyzed by western blotting and immunohistochemistry. Also, lipid peroxidation products showed similar trends. Our results are consistent with lower triglyceride turnover and lower oxidative stress in inguinal than mesenteric and epididymal WAT. The observed WAT depot-specific differences provide clues as to the mechanisms leading to these depots' respective diverse functions. 相似文献
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