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Mate choice is favored by indirect selection if choosy females mate with males of high genetic quality. We believe, however, that testing hypotheses about indirect selection has been constrained by how we conceptualize and therefore empirically measure male genetic quality. Here, we argue that genetic quality is the breeding value of an individual for total fitness. We can therefore learn little about genetic quality from measures of only a few fitness components. We explain breeding value for total fitness, drawing on concepts from life-history theory and quantitative genetics, and suggest how approaches incorporating these insights might result in empirical progress. 相似文献
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Perni RB Pitlik J Britt SD Court JJ Courtney LF Deininger DD Farmer LJ Gates CA Harbeson SL Levin RB Lin C Lin K Moon YC Luong YP O'Malley ET Rao BG Thomson JA Tung RD Van Drie JH Wei Y 《Bioorganic & medicinal chemistry letters》2004,14(6):1441-1446
The alpha-ketoamide warhead (e.g., 15) was found to be a practical replacement for aliphatic aldehydes in a series of HCV NS3.4A protease inhibitors. Structure-activity relationships and prime side optimization are discussed. 相似文献
166.
In agreement with previous data in the literature, our results indicate that serotonin, a monoamine neurotransmitter, can also regulate cell proliferation, cell movements and cell differentiation. We have recently shown that serotonin is required for embryonic heart development. Genetic ablation of the 5-HT2B receptor leads to partial embryonic and postnatal lethality with abnormal heart development. Similar molecular mechanisms seem to be involved in adult cardiomyocytes since mutant mice surviving to adulthood display a dilated cardiomyopathy. Furthermore this receptor appears to be involved in survival of cardiomyocytes. The 5-HT2B receptor is also implicated in systemic hypertension. Furthermore, mice with pharmacological or genetic ablation of 5-HT2B receptor are totally resistant to hypoxia-induced pulmonary hypertension, indicating that this receptor is regulating the pathologic vascular proliferation leading to this disease. Underlying mechanisms are still to be discovered. 相似文献
167.
Siemer A Masip M Carreras N García-Ortega L Oñaderra M Bruix M Del Pozo AM Gavilanes JG 《Biological chemistry》2004,385(12):1165-1170
Asparagine 54 of alpha-sarcin is a conserved residue within the proteins of the ribotoxin family of microbial ribonucleases. It is located in loop 2 of the protein, which lacks repetitive secondary structure elements but exhibits a well-defined conformation. Five mutant variants at this residue have been produced and characterized. The spectroscopic characterization of these proteins indicates that the overall conformation is not changed upon mutation. Activity and denaturation assays show that Asn-54 largely contributes to protein stability, and its presence is a requirement for the highly specific inhibitory activity of these ribotoxins on ribosomes. 相似文献
168.
Under mild conditions (Lewis acid/solvent/room temperature), the reaction of unprotected glucose, deoxyribose or xylose with hydroxylalkylthymine gives selectively nucleoside analogs with a spacer arm between sugar and base moiety. Experimental conditions (Lewis acid, solvent) for this new strategy leading to nucleoside analogs synthesis are discussed. 相似文献
169.
Optimization of the preparation of aqueous suspensions of waxy maize starch nanocrystals using a response surface methodology 总被引:7,自引:0,他引:7
Response surface methodology was used to investigate the effect of five selected factors on the selective H(2)SO(4) hydrolysis of waxy maize starch granules. These predictors were temperature, acid concentration, starch concentration, hydrolysis duration, and stirring speed. The goal of this study was to optimize the preparation of aqueous suspensions of starch nanocrystals, i.e., to determine the operative conditions leading to the smallest size of insoluble hydrolyzed residue within the shortest time and with the highest yield. Therefore empirical models were elaborated for the hydrolysis yield and the size of the insoluble residues using a central composite face design involving 31 trials. They allowed us to show that it was possible to obtain starch nanocrystals after only 5 days of H(2)SO(4) hydrolysis with a yield of 15 wt % and having the same shape as those obtained from the classical procedure after 40 days of HCl treatment, with a yield of 0.5 wt %. 相似文献
170.
Sanna V Kirschvink N Gustin P Gavini E Roland I Delattre L Evrard B 《AAPS PharmSciTech》2004,5(2):17-23
The purpose of this research was to investigate the effects of processing conditions on the characteristics of solid lipid
microparticles (SLM) with a potential application as carriers for pulmonary administration. Compritol (5.0% wt/wt) SLM dispersions
were prepared by rotor-stator homogenization, at different surfactant concentrations and emulsification times. The SLM were
characterized, in terms of morphology and size, after lyophilization and sterilization by autoclaving process. In vivo assessment
was carried out in rats by intratracheal instillation of either placebo or SLM dispersion, and by bronchoalveolar lavage for
cytological analysis. Mean particle size of 4 to 5 μm was achieved using 0.3% and 0.4% (wt/wt) of emulsifier (Poloxamer 188)
and emulsification times of 2 and 5 minutes. The particles showed spherical shape and smooth surface. The morphology of microparticles,
the size, and the size distribution were not substantially modified after lyophilization and sterilization. Total cell counts
showed no significant differences between placebo and SLM 0.5% or 2.5% groups. Regarding cytology, percentage of polymorphonuclear
neutrophils and macrophages did not significantly differ between groups. These results suggest that a single intratracheal
administration of the SLMs does not induce a significant inflammatory airway response in rats and that the SLMs might be a
potential carrier for encapsulated drug via the pulmonary route. 相似文献