The Chinese skink ( Eumeces chinensis) is sexually dimorphic in both body size and head size,and males are the larger.A comprehensive analysis of the ecological and evolutionary sources of sex differences in growth an...The Chinese skink ( Eumeces chinensis) is sexually dimorphic in both body size and head size,and males are the larger.A comprehensive analysis of the ecological and evolutionary sources of sex differences in growth and size of head requires a detailed understanding of growth trajectories during ontogeny.Here,we pay particular attention to the point during ontogeny at which males and females diverge.Hatchlings (newly emerged young) and juveniles smaller than 70 mm SVL do not exhibit sexual dimorphism in head size,whereas males and females larger than 70mm SVL begin to diverge.The sexual dimorphism in head size is much more pronounced in adults than in juveniles sharing this character.Adult females partition relatively less resources into head growth but more into carcass growth,thereby leaving a larger space for eggs so as to increase reproductive output.Adult males,on the contrary,partition relatively more resources into head growth,thereby increasing their reproductive success and enhancing their ability to defend predators.Skinks at different ontogenetic stages slightly differ in food niche width and breadth.However,no direct evidence shows a substantial contribution of the divergence in head size to the segregation of food niche between males and females.Our results indicate that sexual selection is the main evolutionary source of sexual dimorphism in body and head sizes in E.chinensis .展开更多
文摘酰胺质子转移(amide proton transfer,APT)成像基础为细胞内游离蛋白及多肽酰胺质子与自由水中的氢质子发生交换,肿瘤恶性程度越高,细胞内游离蛋白质及多肽含量越多,APT信号增高。本文汇总APT成像诊断直肠癌的国内外相关文献,希望将APT成像用于直肠癌临床早期诊断及疗效评估,提高直肠癌患者生存率。国内外文献研究APT成像诊断直肠癌主要集中在以下几个方面:评估直肠癌组织学分级,预测直肠癌化疗疗效,预测大鼠肉瘤病毒癌(Kirsten rat sarcoma,KRAS)基因是否突变,预测直肠癌侵袭性。与常规MRI序列相比,APT成像可以无创性预测直肠癌侵袭性,进一步观察分子生物学改变。APT成像目前最常用于脑部肿瘤,空腔脏器所含成分复杂,因此临床应用受限,故本文汇总相关文献,探索人为均匀磁场方法,将APT成像这一反映蛋白质代谢的分子生物学检查方法用于直肠癌,开辟APT成像临床应用新领域。
文摘The Chinese skink ( Eumeces chinensis) is sexually dimorphic in both body size and head size,and males are the larger.A comprehensive analysis of the ecological and evolutionary sources of sex differences in growth and size of head requires a detailed understanding of growth trajectories during ontogeny.Here,we pay particular attention to the point during ontogeny at which males and females diverge.Hatchlings (newly emerged young) and juveniles smaller than 70 mm SVL do not exhibit sexual dimorphism in head size,whereas males and females larger than 70mm SVL begin to diverge.The sexual dimorphism in head size is much more pronounced in adults than in juveniles sharing this character.Adult females partition relatively less resources into head growth but more into carcass growth,thereby leaving a larger space for eggs so as to increase reproductive output.Adult males,on the contrary,partition relatively more resources into head growth,thereby increasing their reproductive success and enhancing their ability to defend predators.Skinks at different ontogenetic stages slightly differ in food niche width and breadth.However,no direct evidence shows a substantial contribution of the divergence in head size to the segregation of food niche between males and females.Our results indicate that sexual selection is the main evolutionary source of sexual dimorphism in body and head sizes in E.chinensis .
