排序方式: 共有21条查询结果,搜索用时 281 毫秒
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How reversible is adaptive evolution? Studies of microbes give mixed answers to this question. Reverse evolution has been little studied in sexual populations, even though the population genetics of sexual populations may be quite different. In the present study, 25 diverged replicated populations of Drosophila melanogaster are returned to a common ancestral environment for 50 generations. Here we show that reverse evolution back to the ancestral state occurs, but is not universal, instead depending on previous evolutionary history and the character studied. Hybrid populations showed no greater tendency to undergo successful reverse evolution, suggesting that insufficient genetic variation was not the factor limiting reverse evolution. Adaptive reverse evolution is a contingent process which occurs with only 50 generations of sexual reproduction. 相似文献
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目的:建立高效液相色谱法测定二十五味珊瑚丸中西红花苷含量的方法。方法:采用HPLC法,色谱柱:Dionex C18柱(250mm×4.60mm,5um);流动相为甲醇-水(52:48),流速为0.8ml/min,检测波长为440nm,柱温为25℃;进样量10μl;用标准曲线法定量,测定二十五味珊瑚丸中西红花苷含量。结果:西红花苷Ⅰ在33μg~330μg范围内与峰面积呈良好的线性关系(r=0.9999),西红花苷Ⅱ在62μg~310μg范围内与峰面积呈良好的线性关系(r=0.9998),平均回收率为103.73%,RSD为1.68%(n=6)。结论:本方法操作简单、重现性好,可用于测定二十五味珊瑚丸中西红花苷Ⅰ&Ⅱ含量。 相似文献
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Fábio G. Teixeira Miguel M. Carvalho Nuno Sousa António J. Salgado 《Cellular and molecular life sciences : CMLS》2013,70(20):3871-3882
The low regeneration potential of the central nervous system (CNS) represents a challenge for the development of new therapeutic strategies. Mesenchymal stem cells (MSCs) have been proposed as a possible therapeutic tool for CNS disorders. In addition to their differentiation potential, it is well accepted nowadays that their beneficial actions can also be mediated by their secretome. Indeed, it was already demonstrated, both in vitro and in vivo, that MSCs are able to secrete a broad range of neuroregulatory factors that promote an increase in neurogenesis, inhibition of apoptosis and glial scar formation, immunomodulation, angiogenesis, neuronal and glial cell survival, as well as relevant neuroprotective actions on different pathophysiological contexts. Considering their protective action in lesioned sites, MSCs’ secretome might also improve the integration of local progenitor cells in neuroregeneration processes, opening a door for their future use as therapeutical strategies in human clinical trials. Thus, in this review we analyze the current understanding of MSCs secretome as a new paradigm for the treatment of CNS neurodegenerative diseases. 相似文献
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Trond Roger Oskars Constantine Mifsud Manuel António E. Malaquias 《Journal of Natural History》2017,51(27-28):1593-1608
Atys jeffreysi is a heterobranch Cephalaspidea gastropod belonging to the family Haminoeidae occurring in the Mediterranean Sea, Madeira and Canary archipelagos. Nearly nothing is known about the internal anatomical features of this species. In this paper we redescribe the species A. jeffreysi based on fine anatomical work and scanning electron microscopy. DNA barcodes are provided for the first time for A. jeffreysi and A. macandrewii, the only two species of the genus native in the Mediterranean Sea. The genetic distance (COI uncorrected p-distance) between them is estimate at 21.6%. A Bayesian molecular phylogeny based on the gene marker cytochrome c oxidase subunit I (COI) including all sequences available of the genera Aliculastrum, Liloa and Atys species did not support a sister relationship between the two Mediterranean species and suggests that they are more closely related to distinct Indo-West Pacific lineages. The complex systematics of the genus Atys is briefly discussed. 相似文献
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目的:研究FGFR2IIIc及其突变型腺病毒对小鼠乳腺癌的作用。方法:确定腺病毒颗粒Ad、Ad-FGFR2IIIc及Ad-FGFR2IIIcS252W感染4T1细胞的最佳MOI,并通过RT-PCR检测外源目的基因的表达。建立BALB/c小鼠的4T1乳腺癌模型,在此模型上原位注射重组腺病毒颗粒治疗17天,观察其对小鼠肿瘤的作用。结果:当MOI=60时腺病毒对4T1细胞的感染率可达到95%以上,RT-PCR结果显示,FGFR2IIIc和FGFR2IIIcS252W可在4T1细胞中成功表达。与对照组和Ad组比较,Ad-FGFR2IIIc对小鼠肿瘤无明显作用,Ad-FGFR2IIIcS252W能显著减缓小鼠肿瘤体积和质量的增长。结论:FGFR2IIIc对BALB/c小鼠4T1乳腺癌无显著作用,FGFR2IIIcS252W能够显著抑制BALB/c小鼠4T1乳腺癌的生长。 相似文献
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