排序方式: 共有63条查询结果,搜索用时 78 毫秒
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Michael Hrncir Veronika M. Schmidt Dirk Louis P. Schorkopf Stefan Jarau Ronaldo Zucchi Friedrich G. Barth 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2006,192(8):879-887
An element common to the recruitment communication of eusocial bees (honey bees, stingless bees and bumble bees) are pulsed thorax vibrations generated by successful foragers within the nest. In stingless bees, foragers vibrate during the unloading of the collected food. In the present study on Melipona seminigra we demonstrate that during trophallactic contacts, the food receivers are directly vibrated by the foragers. As a consequence, both the temporal structure and the main frequency component of the forager’s vibrations are directly passed on to the receiver. The vibrations are attenuated by about 17 dB on their way from the forager’s thorax (velocity amplitude of the vibrations: ∼70 mm/s) to the receiver’s thorax (∼10 mm/s), the main amount of attenuation (about 12 dB) occurring during transmission from the head of the forager to that of the receiver. Vibrations conducted through the substrate between the forager and food receiver are comparatively small with velocity amplitudes of 0.3 mm/s. Possible ways of perception and the advantages of vibration transmission by direct contact within the recruitment context are discussed. 相似文献
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Shawn M. Aarde Rylee M. Genner Haley Hrncir Arthur P. Arnold James D. Jentsch 《Genes, Brain & Behavior》2021,20(1):e12685
Determining the mechanisms by which the sex-chromosome complement (SCC) affects learning, attention, and impulsivity has implications for observed sex differences in prevalence, severity, and prognosis of psychiatric/neurodevelopmental disorders and syndromes associated with sex-chromosome aneuploidy. Here, Four Core Genotypes (FCG) mice were evaluated in order to assess the separable and/or interacting effects of gonads (testes vs. ovaries) and their secretions and/or SCC (XX vs. XY) acting via non-gonadal mechanisms on behavior. We tested FCG mice on a reversal-learning task that enables the quantification of aspects of learning, attention and impulsivity. Across testing phases (involving the initial acquisition of a spatial discrimination and subsequent reversal learning), overall error rate was larger in XY compared with XX mice. Although XX and XY groups did not differ in the total number of trials required in order to reach a preset performance criterion, analyses of reversal error types showed more perseverative errors in XY than XX mice, with no difference in regressive errors. Additionally, prepotent-response latencies during the reversal phase were shorter in XY males, as compared with both XX gonadal males and females of either SCC, and failures to sustain the observing response were more frequent in XY mice than XX mice during the acquisition phase. These results indicate that SCC affects the characteristic pattern of response selection during acquisition and reversal performance without affecting the overall learning rate. More broadly, these results show direct effects of the SCC on cognitive processes that are relevant to psychiatric/neurodevelopmental disorders and syndromes associated with sex-chromosome aneuploidies. 相似文献
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Soraya M Kazuma Marcela F Cavalcante Andréia ER Telles Andrea Queiroz Maranh?o Dulcineia SP Abdalla 《MABS-AUSTIN》2013,5(5):763-775
The in vivo modified forms of low-density lipoprotein (LDL) are important for the formation of foam cells and as mediators of the immuno-inflammatory process involved in the progression of atherosclerosis. Electronegative LDL, LDL(-), is a LDL subfraction with pro-inflammatory properties that is present in human blood. To investigate possible atheroprotective effects, an anti-LDL(-) single-chain variable fragment (scFv) was expressed in the methylotrophic yeast Pichia pastoris and its activity was evaluated in vitro against macrophages and in experimental atherosclerosis in Ldlr-/- mice. The recombinant 2C7 scFv was produced in a yield of 9.5 mg of protein/L. The specificity and affinity of purified 2C7 scFv against LDL(-) was confirmed by ELISA. To assess the activity of 2C7 scFv on foam cell formation, RAW 264.7 macrophages were exposed to LDL(-) in the presence or absence of 2C7 scFv. The 2C7 scFv inhibited the uptake of LDL(-) by macrophages in a dose-dependent manner, and internalization of LDL(-) by these cells was found to be mediated by the CD36 and CD14 receptor. In addition, compared with untreated cells, lipid accumulation in macrophages was decreased, and the expression of Cd36, Tlr-4 and Cox-2 was downregulated in macrophages treated with 2C7 scFv. Importantly, compared with untreated mice, the treatment of Ldlr-/- mice with 2C7 scFv decreased the atherosclerotic lesion area at the aortic sinus. In conclusion, our data show that 2C7 scFv inhibits foam cell formation and atherosclerotic plaque development by modulating the expression of genes relevant to atherogenesis. These results encourage further use of this antibody fragment in the development of new therapeutic strategies that neutralize the pro-atherogenic effects of LDL(-). 相似文献
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Sery Gonedelé Bi Didier P Sokouri Kouakou Tiékoura Oulo Alla N?Nan Marcel Lolo Félix Gnangbé Assanvo SP N?Guetta 《Bioinformation》2014,10(11):671-678
Cête d׳Ivoire continues to have the highest HIV-1 prevalence rate in West Africa, although the infection number is in constant
decline. The external envelope protein of the viruses is a likely site of selection, and responsible for receptor binding and entry into
host cells, and therefore constitutes an ideal region with which to investigate the evolutionary processes acting on HIV-1. In this
study, we analyse 189 envelope glycoprotein V3 loop region sequences of viruse isolates from 1995 to 2009, from HIV-1 untreated
patients living in Cête d׳Ivoire, to decipher the temporal relationship between disease diversity, divergence and selection. Our
analyses show that the nonsynonymous and synonymous ratio (dN/dS) was lower than 1 for viral populations analysed within 15
years, which showed the sequences did not undergo adequate immune pressure. The phylogenetic tree of the sequences analysed
demonstrated distinctly long internal branches and short external branches, suggesting that only a small number of viruses
infected the new host cell at each transmission. In addition to identifying sites under purifying selection, we also identified neutral
sites that can cause false positive inference of selection. These sites presented form a resource for future studies of selection
pressures acting on HIV-1 enν gene in Cête d׳Ivoire and other West African countries. 相似文献
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