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991.
992.
Clair Bennison Nicola Hemmings Jon Slate Tim Birkhead 《Proceedings. Biological sciences / The Royal Society》2015,282(1799)
Sperm competition, in which the ejaculates of multiple males compete to fertilize a female''s ova, results in strong selection on sperm traits. Although sperm size and swimming velocity are known to independently affect fertilization success in certain species, exploring the relationship between sperm length, swimming velocity and fertilization success still remains a challenge. Here, we use the zebra finch (Taeniopygia guttata), where sperm size influences sperm swimming velocity, to determine the effect of sperm total length on fertilization success. Sperm competition experiments, in which pairs of males whose sperm differed only in length and swimming speed, revealed that males producing long sperm were more successful in terms of (i) the number of sperm reaching the ova and (ii) fertilizing those ova. Our results reveal that although sperm length is the main factor determining the outcome of sperm competition, complex interactions between male and female reproductive traits may also be important. The mechanisms underlying these interactions are poorly understood, but we suggest that differences in sperm storage and utilization by females may contribute to the outcome of sperm competition. 相似文献
993.
994.
995.
John R Glossop Richard D Emes Richard D Emes Nicola B Nixon Nicola B Nixon Kim E Haworth Kim E Haworth Jon C Packham Jon C Packham Peter T Dawes Peter T Dawes Anthony A Fryer Anthony A Fryer Derek L Mattey Derek L Mattey William E Farrell William E Farrell 《Epigenetics》2014,9(9):1228-1237
Changes to the DNA methylome have been described in patients with rheumatoid arthritis (RA). In previous work, we reported genome-wide methylation differences in T-lymphocyte and B-lymphocyte populations from healthy individuals. Now, using HumanMethylation450 BeadChips to interrogate genome-wide DNA methylation, we have determined disease-associated methylation changes in blood-derived T- and B-lymphocyte populations from 12 female patients with seropositive established RA, relative to 12 matched healthy individuals. Array data were analyzed using NIMBL software and bisulfite pyrosequencing was used to validate array candidates. Genome-wide DNA methylation, determined by analysis of LINE-1 sequences, revealed higher methylation in B-lymphocytes compared with T-lymphocytes (P ≤ 0.01), which is consistent with our findings in healthy individuals. Moreover, loci-specific methylation differences that distinguished T-lymphocytes from B-lymphocytes in healthy individuals were also apparent in RA patients. However, disease-associated methylation differences were also identified in RA. In these cases, we identified 509 and 252 CpGs in RA-derived T- and B-lymphocytes, respectively, that showed significant changes in methylation compared with their cognate healthy counterparts. Moreover, this included a restricted set of 32 CpGs in T-lymphocytes and 20 CpGs in B-lymphocytes (representing 15 and 10 genes, respectively, and including two, MGMT and CCS, that were common to both cell types) that displayed more substantial changes in methylation. These changes, apparent as hyper- or hypo-methylation, were independently confirmed by pyrosequencing analysis. Validation by pyrosequencing also revealed additional sites in some candidate genes that also displayed altered methylation in RA. In this first study of genome-wide DNA methylation in individual T- and B-lymphocyte populations in RA patients, we report disease-associated methylation changes that are distinct to each cell type and which support a role for discrete epigenetic regulation in this disease. 相似文献
996.
Experimental manipulation of tail ornament size affects the hematocrit of male barn swallows (Hirundo rustica) 总被引:2,自引:0,他引:2
Nicola Saino José Javier Cuervo Marco Krivacek Florentino de Lope Anders Pape Møller 《Oecologia》1997,110(2):186-190
Ornamental tail feathers of male barn swallows (Hirundo rustica) confer an advantage in sexual selection because long-tailed males are preferred by females. However, the size of tail ornaments
exceeds the natural selection optimum and males are predicted to pay an energetic cost for flying, directly related to tail
length. An increase in hematocrit is an adaptive response to enhance oxygen uptake, for example during periods of intense
locomotory activity. In this study, we analyzed the effect of experimental manipulation of tail length on the hematocrit of
male barn swallows from an Italian and a Spanish population. We predicted that the natural decrease in hematocrit during the
breeding season would be reduced by experimental elongation and enhanced by experimental shortening of tail ornaments. The
results showed that the decrease in hematocrit was significantly different among tail treatments, and tail-elongated males
had the smallest hematocrit reduction. In Italy, the hematocrit of tail-elongated males did not change after tail manipulation,
while that of two control groups and tail-shortened males decreased. A comparatively high hematocrit in males with experimentally
enlarged tail ornaments may be a response to increased energetic requirements and, hence, to oxygen demands for flying imposed
by their tail morphology.
Received: 22 June 1996 / Accepted: 23 October 1996 相似文献
997.
Nicola Maruotti Addolorata Corrado Anna Neve Francesco Paolo Cantatore 《Journal of cellular physiology》2013,228(7):1428-1432
Wnt signaling plays a key role in several physiological and pathological aspects. Even if Wnt signal was first described more than 20 years ago, its role in systemic effects, such as angiogenesis and vascular disorders, bone biology, autoimmune diseases, neurological diseases, and neoplastic disorders, was only recently emerged through the use of animal and in vitro models. Moreover, Wnt signaling inhibitors, such as DKK‐1, may be advantageously considered targets for the treatment of several diseases, including osteoporosis, vascular diseases, inflammatory diseases, neurological diseases, and cancer. Nevertheless, further studies are required to provide a complete understanding of this complex signaling pathway, and especially of its role in human diseases, considering the possible advantageous effects of Wnt signaling inhibitors on the progression of disease conditions. J. Cell. Physiol. 228: 1428–1432, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
998.
Nicola Tannenbaum 《American anthropologist》1984,86(4):927-942
Sahlins's "Chayanov's Rule"–the more consumers each worker has to support the more work each worker does-has characterized Chayanov's analysis for most anthropologists. I examine the relationship between the consumer/worker ratio and product per worker for the Shan community of Thongmakhsan in northwestern Thailand. Since there is no systematic relationship between these variables even when the population is divided into production strategy groups, I go on to examine the relationship between Sahlins's "Chayanov's Rule" and Chayanov's own analysis. In conclusion I raise the issue of the continuing identification of Chayanov with "Chayanov's Rule" and consider a number of possible reasons for this. 相似文献
999.
Activation of granulocyte cytotoxic function by purified mouse colony-stimulating factors 总被引:15,自引:0,他引:15
A F Lopez N A Nicola A W Burgess D Metcalf F L Battye W A Sewell M Vadas 《Journal of immunology (Baltimore, Md. : 1950)》1983,131(6):2983-2988
Highly purified mouse colony-stimulating factors (CSF) were tested for their effect on neutrophil cytotoxic function in a homologous antibody-dependent cell-mediated cytotoxicity (ADCC) assay in which TNP-coupled mouse thymoma cells coated with mouse anti-TNP antibodies were used as targets, and purified normal mouse bone marrow neutrophils or induced peritoneal neutrophils were used as effector cells. Biochemically pure granulocyte-macrophage (GM)- and granulocyte (G)-CSF enhanced the cytotoxic activity of neutrophils obtained from both sources, allowing them to kill target cells at low antibody concentrations. Furthermore, GM- and G-CSF showed an additive effect, suggesting either the presence of separate receptors for GM- and G-CSF or of separate subsets of neutrophils. Induced peritoneal neutrophils showed a higher level of basal cytotoxic activity than did bone marrow neutrophils, suggesting neutrophil activation in vivo, but both reached similar levels of cytotoxicity upon maximal stimulation with CSF. In addition, CSF was found to be cross-reactive between mouse and human species in their enhancement of neutrophil cytotoxicity. By testing purified mouse CSF on human neutrophils, it could be shown that G-CSF and GM-CSF are functionally distinct molecules, because only G-CSF enhanced ADCC by human neutrophils. These experiments show that the purified factors that control the production of neutrophils by progenitor cells in vitro also activate differentiated neutrophils to carry out their cytotoxic activity in a more effective manner. 相似文献
1000.
Marcella Maddaluno Gianluca Grassia Maria Vittoria Di Lauro Antonio Parisi Francesco Maione Carla Cicala Daniele De Filippis Teresa Iuvone Angelo Guglielmotti Pasquale Maffia Nicola Mascolo Armando Ialenti 《PloS one》2012,7(10)
Bindarit, a selective inhibitor of monocyte chemotactic proteins (MCPs) synthesis, reduces neointimal formation in animal models of vascular injury and recently has been shown to inhibit in-stent late loss in a placebo-controlled phase II clinical trial. However, the mechanisms underlying the efficacy of bindarit in controlling neointimal formation/restenosis have not been fully elucidated. Therefore, we investigated the effect of bindarit on human coronary smooth muscle cells activation, drawing attention to the phenotypic modulation process, focusing on contractile proteins expression as well as proliferation and migration. The expression of contractile proteins was evaluated by western blot analysis on cultured human coronary smooth muscle cells stimulated with TNF-α (30 ng/mL) or fetal bovine serum (5%). Bindarit (100–300 µM) reduced the embryonic form of smooth muscle myosin heavy chain while increased smooth muscle α-actin and calponin in both TNF-α- and fetal bovine serum-stimulated cells. These effects were associated with the inhibition of human coronary smooth muscle cell proliferation/migration and both MCP-1 and MCP-3 production. The effect of bindarit on smooth muscle cells phenotypic switching was confirmed in vivo in the rat balloon angioplasty model. Bindarit (200 mg/Kg/day) significantly reduced the expression of the embryonic form of smooth muscle myosin heavy chain, and increased smooth muscle α-actin and calponin in the rat carodid arteries subjected to endothelial denudation. Our results demonstrate that bindarit induces the differentiated state of human coronary smooth muscle cells, suggesting a novel underlying mechanisms by which this drug inhibits neointimal formation. 相似文献