Variation in genome-wide mutation rates within and between human families

J.B.S. Haldane proposed in 1947 that the male germline may be more mutagenic than the female germline. Diverse studies have supported Haldane's contention of a higher average mutation rate in the male germline in a variety of mammals, including humans. Here we present, to our knowledge, the first direct comparative analysis of male and female germline mutation rates from the complete genome sequences of two parent-offspring trios. Through extensive validation, we identified 49 and 35 germline de novo mutations (DNMs) in two trio offspring, as well as 1,586 non-germline DNMs arising either somatically or in the cell lines from which the DNA was derived. Most strikingly, in one family, we observed that 92% of germline DNMs were from the paternal germline, whereas, in contrast, in the other family, 64% of DNMs were from the maternal germline. These observations suggest considerable variation in mutation rates within and between families.     

近断层地震动对高层建筑结构抗震性能的影响

近断层地震地面运动区别于远场地震,具有滑冲效应特性和向前方向性效应特性.其中,具有单方向速度脉冲和阶跃式永久位移的滑冲效应对长周期结构影响较大.取1999年Turkey地震中台站SKR带有滑冲效应的近断层地震记录作为输入获得弹性和弹塑性反应谱,并详细分析具有不同大小线性特征周期的单自由度体系从线性发展到非线性的整个过程中滑冲效应的作用.以某典型的钢筋混凝土剪力墙高层建筑结构为例,具体研究近断层地震滑冲效应对结构抗震性能的影响.结果表明,近断层地震滑冲效应除了对较长周期的高层结构抗震性能具有不利影响之外,对可能产生较大非线性变形的短周期结构的影响同样不可忽视.     

Scorpions are a food item of American black bears in Sonora, Mexico

The remains of the scorpion Diplocentrus peloncillensis Francke were found in 7 scats of black bears ( Ursus americanus ) collected in the Sierra de San Luis, Sonora, Mexico. The collection data and previously reported black bear population estimates for the study area suggested that, although scorpions are not a large part of black bear diets in Sonora, feeding on scorpions is not restricted to a single individual or family unit and is apparently a relatively common behavior in the population. Also, the discovery of D. peloncillensis in Sonora represents a new country record.     

Carapace ontogeny of the bromeliad dwelling ostracod Elpidium bromeliarum Müller, 1880 (Crustacea: Ostracoda)

Ostracods have discontinuous development, marked by ecdyses, and determinate growth. Ontogenetic studies have suggested a pattern of nine postembryonic stages (eight juvenile phases and the adult) for the main freshwater ostracod superfamilies Cypridoidea, Cytheroidea and Darwinuloidea. However, cases of a supposed extra moult in the adult stage have been proposed for some ostracod species, which would amount to 10 postembryonic growth stages. One such example is Elpidium bromeliarum Müller, 1880, a cytheroidean that inhabits tank-bromeliads. The present study is aimed at investigating the ontogenetic development of E. bromeliarum using width and length measurements, as well as carapace and appendage morphology in order to test the existing hypothesis of an additional growth stage in adults of this species. Our results revealed nine postembryonic growth stages (eight juvenile and the adult), with sexual dimorphism beginning its expression in the last juvenile stage. Thus, the ontogenetic development of E. bromeliarum agrees with the overall pattern observed for podocopid ostracods and the hypothesis of 10 postembryonic growth stages was not corroborated. We argue that the inability to differentiate juveniles from adults, or different species from one another, may have misled to the assumption of an additional moult in E. bromeliarum.