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71.
Rowan O. Martin Lovelater Sebele Ann Koeslag Odette Curtis Fitsum Abadi Arjun Amar 《Oikos》2014,123(12):1457-1468
In a rapidly changing world understanding the capacity of populations to adapt to novel environments is increasingly urgent. Timing of breeding can be a highly flexible trait and adjustments in this trait can potentially buffer populations from climate change and facilitate the colonisation of new environments. Recent range‐expansions into novel climatic regimes provide a valuable opportunity to investigate the implications of plasticity in timing of breeding for population processes. Black sparrowhawks have recently colonised the Cape Peninsula of South Africa where they experience dramatically different weather patterns to those in their historical range. These include a total reversal in the rainfall regime, with the majority of rain falling in the winter as opposed to the summer months. We investigate the breeding phenology of black sparrowhawks in relation to both regional and local climate variation and, using a long‐term dataset, explore the implications of phenological shifts for reproductive success and population growth following colonisation. In the recently colonised Cape Peninsula the breeding season began up to three months earlier than within their historical range and these early breeding attempts produced more offspring. Population models suggested that this adjustment assisted the colonisation of the Cape Peninsula, reducing the probability of extinction by 23%. Contrary to expectations, we found little support for the hypothesis that black sparrowhawks were responding to local variation in rainfall. We suggest that shifts in breeding phenology may be driven in part by other novel processes, such as interspecific competition for nest sites and lower temperatures during late summer. These results provide insight into the processes that facilitated the colonisation of a novel climatic regime highlighting the potential role of a diverse range of factors. 相似文献
72.
Dima Abi-Abdallah Eric Chauvet Latifa Bouchet-Fakri Alain Bataillard André Briguet Odette Fokapu 《Biomedical engineering online》2006,5(1):11-12
Background
Present developments in Nuclear Magnetic Resonance (NMR) imaging techniques strive for improved spatial and temporal resolution performances. However, trying to achieve the shortest gradient rising time with high intensity gradients has its drawbacks: It generates high amplitude noises that get superimposed on the simultaneously recorded electrophysiological signals, needed to synchronize moving organ images. Consequently, new strategies have to be developed for processing these collected signals during Magnetic Resonance Imaging (MRI) examinations. The aim of this work is to extract an efficient reference signal, from an electrocardiogram (ECG) that was contaminated by the NMR artefacts. This may be used for image triggering and/or cardiac rhythm monitoring. 相似文献73.
Valérie Turcot Luigi Bouchard Geneviève Faucher André Tchernof Yves Deshaies Louis Pérusse Alexandre Bélisle Simon Marceau Simon Biron Odette Lescelleur Laurent Biertho Marie‐Claude Vohl 《Obesity (Silver Spring, Md.)》2011,19(2):388-395
Severely obese subjects with the metabolic syndrome (MS) have higher dipeptidyl peptidase‐4 (DPP4) expression in their visceral adipose tissue (VAT) compared to obese individuals without MS. We tested the hypothesis that methylation level of CpG sites in the DPP4 promoter CpG island in VAT was genotype‐dependent and associated with DPP4 mRNA abundance and MS‐related phenotypes. The VAT DNA was extracted in 92 severely obese premenopausal women undergoing biliopancreatic derivation for the treatment of obesity. Women were nondiabetic and none of them used medication to treat MS features. Cytosine methylation rates (%) of 102 CpG sites in the DPP4 CpG island were assessed by pyrosequencing of sodium bisulfite‐treated DNA. Methylation rates were >10% for CpG sites 94–102. Their mean methylation rate (%Meth94–102) was different between genotypes for DPP4 polymorphisms rs13015258 (P = 0.001), rs17848915 (P = 0.0004), and c.1926 G>A (P = 0.001). The %Meth94–102 correlated negatively with DPP4 mRNA abundance (r = ?0.25, P < 0.05) and positively with plasma high‐density lipoprotein (HDL) cholesterol concentrations (r = 0.22, P < 0.05), whereas DPP4 mRNA abundance correlated positively with plasma total‐/HDL‐cholesterol ratio (r = 0.25; P < 0.05). In the VAT of nondiabetic severely obese women, genotype‐dependent methylation levels of specific CpG sites in the DPP4 promoter CpG island were associated with DPP4 gene expression and variability in the plasma lipid profile. Higher DPP4 gene expression in VAT and its relationship with the plasma lipid profile may be explained by actually unknown DPP4 biological effect or, to another extent, may also be a marker of VAT inflammation known to be associated with metabolic disturbances. 相似文献
74.
The aim of this study was determine the effect of bradykinin receptor antagonism on MSU crystal-induced chemokine production and leukocyte recruitment. Mice were injected intraperitoneally with monosodium urate (MSU) crystals ± bradykinin B1- or B2 receptor antagonists, Des-Arg-HOE-140 and HOE-140, respectively. MSU crystal-induced chemokine production and leukocyte recruitment in the peritoneum were measured over 24h and B1 and B2 receptor expression on leukocytes and peritoneal membrane was determined by flow cytometry and fluorescence microscopy. Data analysis showed that only B2 receptor antagonism decreased monocyte and neutrophil infiltration 24 h post MSU crystal administration. Decreased leukocyte infiltration was associated with reduced monocyte (CCL2) chemokine levels. MSU crystal-induced damage to the surrounding visceral membrane was also attenuated in the presence of B2 receptor antagonism. Together, these data show that bradykinin receptor 2 plays a role in maintaining MSU crystal-induced leukocyte infiltration and membrane permeability and identify the B2 receptor as a potential therapeutic target for managing inflammation in gout. 相似文献
75.
76.
77.
Odette Szylit Michelle Durand L.P. Borgid H. Atinkpahoun F. Prieto J. Delort-Laval 《Animal Feed Science and Technology》1978,3(1):73-87
Three tropical tubers, raw or processed by steam-pelleting, were studied in the rumen in vitro or in the chicken in vivo in order to determine the effects of the nature and of the treatment of the tubers on urea utilization by rumen microflora, starch breakdown in the crop and the performance of growing chickens.Starch of cassava (Manihot utilissima) and of sweet potato (Ipomea batata) is characterised by an X-ray diffraction pattern of the A-type and is therefore similar to starch of cereals. In vitro these starches were well broken down in the presence of α-amylase from B. subtilis, and were good sources of energy for rumen microbial growth; in vivo they were completely digested by growing chickens. Compared to cassava, the fermentation of sweet potato in rumen and crop led to increased acidity. The cassava diet gave a better nitrogen retention and growth performance associated with higher food intake.In contrast, starch of yam (Dioscorea cayenensis) which is characterized by an X-ray diffraction pattern of the B-type, and by large granules like potato starch, was less susceptible to α-amylase and promoted lower microbial proteosynthesis in vitro. Starch from a yam diet was more slowly degraded in the crop and its overall digestibility was only 83%. Yam reduced feed intake and gave lower nitrogen retention and lower food conversion ratio and consequently poor growth.The steam-pelleting treatment increased starch availability and permitted better urea utilization by rumen microflora. It improved N retention and feed efficiency of chicken diets, although not significantly. The greatest effect of the treatment was observed with yam.In conclusion, the digestibility of a given starch seems to be related to its structure, characterized by the type of X-ray diffraction pattern, which could be a help in tuber selection for animal nutrition. Simple processing such as steam-pelleting may improve the nutritive value of a tuber, especially when its starch has a B-type crystallinity. 相似文献
78.
79.
H Jaafar O Gabriel-Robez C Ratomponirina J Boscher M Bonneau C P Popescu Y Rumpler 《Cytogenetics and cell genetics》1989,50(4):220-225
An electron microscopic study of synaptonemal complexes in two heterozygous fertile boars, one a carrier of a 4;14 reciprocal translocation and the second a carrier of this translocation associated with a 3;7 reciprocal translocation, is reported. The results showed heterologous pairing in almost all quadrivalents, as well as a lack of XY-quadrivalent association. This seemed to be a common feature of translocations in pigs, even if at least one acrocentric chromosome is involved, and may represent a significant meiotic mechanism that prevents spermatocyte loss, while the production of genetically unbalanced gametes leads to loss of progeny through abortion. 相似文献
80.
The effects of two bacterial pyrogens (gonococcus vaccine and E. coli lipopolysaccharide) on brain and CSF concentrations of the biogenic amines and their major metabolites were compared in rabbits. Both pyrogens induced a similar fever, but only the lipopolysaccharide elicited marked biochemical alterations. The main changes observed were: a decrease in the concentrations of acid metabolites of dopamine during the upward course of the first peak of fever; a decrease in the hypothalamic concentrations of noradrenaline at the second peak of fever; a general increase in the metabolites of biogenic amines around the second peak and during the fall of fever. The results led to the conclusion that no significant correlation exists between body temperature and brain amine levels in rabbits. The alterations observed could be a consequence of the fever itself when considered in terms of trauma to the organism. 相似文献