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排序方式: 共有170条查询结果,搜索用时 15 毫秒
1.
The effect of feeding endophyte infected tall fescue seed on reproductive performance in female rats 总被引:1,自引:0,他引:1
D R Varney M Ndefru S L Jones R Newsome M R Siegel P M Zavos 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1987,87(1):171-175
Female Sprague-Dawley rats (Rattus norvegicus) were randomly assigned to diets containing mixtures of rat chow and tall fescue (Festuca arundinacea) seed with 0, 5, 10, 20 and 40% infection levels of Acremonium coenophialum to assess the effect of the diets on the reproductive potential of rats. Rats fed 40% infected seed had decreased body weight, decreased mean percent body weight of uteri, failed to maintain normal estrous cycles and were unable to become pregnant. Animals fed a diet of 20% infected fescue seed had extended estrous cycles. There were no significant differences among the 0, 5 and 10% dietary treatments. 相似文献
2.
D R Varney C J Kappes S L Jones R Newsome M R Siegel P M Zavos 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1988,89(2):315-320
1. Female Sprague-Dawley rats (Rattus norvegicus) were randomly assigned to various dietary treatments containing: (1) 100% Purina rodent chow, ad libitum; (2) same as 1, but restricted to daily intake of 7; (3) 50% rodent chow (w/w) and 50% endophyte-free tall fescue (Festuca arundinacea) seed; (4) same as 3, but restricted to intake of 5; (5) 50% rodent chow, 25% endophyte-free tall fescue seed and 25% endophyte-infected (Acremonium coenophialum) tall fescue seed; (6) 50% rodent chow, 12.5% endophyte-free and 37.5% endophyte-infected tall fescue seed; and (7) 50% rodent chow and 50% endophyte infected tall fescue seed. 2. Average daily feed intakes and average daily weight gains decreased with higher levels of endophyte infected seed. 3. Frequency of litter production was affected by all endophyte-infected containing diets. 4. Conception was reduced only in dietary treatment (7). 5. Litter weights, number of pups per litter and weight per pup were proportionally reduced as higher levels of infected seed were incorporated in the ingested diets. 相似文献
3.
M. C. Johnson D. L. Dahlman M. R. Siegel L. P. Bush G. C. M. Latch D. A. Potter D. R. Varney 《Applied microbiology》1985,49(3):568-571
The presence of an endophytic fungus, Acremonium coenophialum, in tall fescue (Festuca arundinacea) deterred aphid feeding by Rhopalosiphum padi and Schizaphis graminum. Both species of aphid were unable to survive when confined to endophyte-infected tall fescue plants. Feeding deterrents and toxic factors to R. padi and Oncopeltus fasciatus, large milkweed bug, were primarily associated with a methanol extract obtained when endophyte-infected tall fescue seed was serially extracted with hexane, ethyl acetate, and methanol. The concentrations of pyrrolizidine alkaloids were determined to be 30 to 100 times greater in the methanol extract than in the hexane and ethyl acetate extracts. 相似文献
4.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
5.
E L Murphy K F Varney N T Miyasaki R J Moore J I Umekubo A N Watanabe H Khayam-Bashi 《The Western journal of medicine》1993,158(5):480-483
The epidemiology of human T-lymphotropic virus type I (HTLV-I) infection is not well defined in Japanese Americans. This impairs using approaches that could reduce viral transmission and monitor carriers for the disease. Using enzyme-linked immunosorbent assay and p21e recombinant Western blot testing, HTLV-I antibody was measured in unlinked samples from Japanese-American patients at 4 physicians'' offices in San Francisco, California. Of 442 patients, 4 (0.9%; 95% confidence interval 0.25%, 2.3%) were confirmed seropositive, all with an HTLV-I rather than an HTLV-II pattern on Western blot. Seroprevalence was highest among the issei or immigrant generation (3/230 or 1.3%) compared with the second-generation nisei (1/191 or 0.5%) or third-generation sansei (0 of 17). Prevalence did not differ by age or sex, although the number of positive subjects in each subgroup was small. Of 88 patients with familial origins in endemic areas of southern Japan, none were seropositive. In this sample of Japanese Americans, HTLV-I seroprevalence was lower than in residents of endemic southern Japan but higher than among American blood donors. The prevalence was most similar to that in nonendemic areas of Japan. The public health implications of HTLV-I infection among Japanese Americans are discussed. 相似文献
6.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
7.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
8.
Eosinophil activation and T lymphocyte infiltration in allergen-induced late phase skin reactions and classical delayed-type hypersensitivity. 总被引:7,自引:0,他引:7
M Gaga A J Frew V A Varney A B Kay 《Journal of immunology (Baltimore, Md. : 1950)》1991,147(3):816-822
T lymphocyte infiltration is a well documented feature of classical delayed-type hypersensitivity (DTH) reactions. Recently, we have shown that T lymphocytes and activated (EG2+) eosinophils accumulate in the allergen-induced late phase skin reaction (LPR). To compare the kinetics and phenotypic composition of these T lymphocyte responses, LPR and DTH reactions of comparable induration size were induced in atopic subjects. In addition, DTH and LPR were compared between atopic and nonatopic subjects. In atopic individuals, allergen challenge elicited a perivascular influx of T lymphocytes that was predominantly CD4+. Eosinophil accumulation and activation were also prominent. There was no cellular response to allergen challenge in the nonatropic group. In both groups, DTH responses showed an intense T cell infiltrate which was more dense and dispersed than in the LPR. CD4+ T cells predominated but at 48 h CD8+ numbers were also significantly increased. In DTH, total leukocyte numbers (CD45+) were increasing at 48 h, whereas in the LPR, cell numbers reached a plateau between 24 and 48 h. T cell activation (shown by expression of IL-2R) was more prominent in DTH. Endothelial expression of HLA-DR was increased in both LPR and DTH, implying the local release of inflammatory cytokines in both reactions. Small but significant numbers of activated eosinophils (EG2+) were detected in atopics and non-atopics at 24 h in DTH but not at 48 h. These findings suggest that the allergen-induced LPR induced in atopic subjects is, at least in part, a form of cell-mediated hypersensitivity but with T cell kinetics that differ from classical DTH. 相似文献
9.
Kristen M. Varney Alexandre M. J. J. Bonvin Marzena Pazgier Jakob Malin Wenbo Yu Eugene Ateh Taiji Oashi Wuyuan Lu Jing Huang Marlies Diepeveen-de Buin Joseph Bryant Eefjan Breukink Alexander D. MacKerell Jr Erik P. H. de Leeuw 《PLoS pathogens》2013,9(11)
We have previously reported on the functional interaction of Lipid II with human alpha-defensins, a class of antimicrobial peptides. Lipid II is an essential precursor for bacterial cell wall biosynthesis and an ideal and validated target for natural antibiotic compounds. Using a combination of structural, functional and in silico analyses, we present here the molecular basis for defensin-Lipid II binding. Based on the complex of Lipid II with Human Neutrophil peptide-1, we could identify and characterize chemically diverse low-molecular weight compounds that mimic the interactions between HNP-1 and Lipid II. Lead compound BAS00127538 was further characterized structurally and functionally; it specifically interacts with the N-acetyl muramic acid moiety and isoprenyl tail of Lipid II, targets cell wall synthesis and was protective in an in vivo model for sepsis. For the first time, we have identified and characterized low molecular weight synthetic compounds that target Lipid II with high specificity and affinity. Optimization of these compounds may allow for their development as novel, next generation therapeutic agents for the treatment of Gram-positive pathogenic infections. 相似文献
10.
The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice 下载免费PDF全文
S Gohin A Carriero C Chenu AA Pitsillides TR Arnett M Marenzana 《Cell biochemistry and function》2016,34(2):52-62
There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd. 相似文献