Hydrolysis of histones by horse urinary kallikreins

Summary Horse urinary kallikrein was shown to hydrolyze histones from calf thymus and chicken nuclei erythrocytes. The hydrolysis is inhibited by benzamidine and hyposulfite but not by soy-bean trypsin inhibitor; horse plasma kallikrein also produces this hydrolysis.Work supported by grants from Projeto BIOQ/FAPESP (São Paulo), FINEP (Rio) and CNPq (Rio).Fellow from CNPq, from Instituto Biológico (São Paulo).     

Conservation of hotspots for recombination in low-copy repeats associated with the NF1 microdeletion

Several large-scale studies of human genetic variation have provided insights into processes such as recombination that have shaped human diversity. However, regions such as low-copy repeats (LCRs) have proven difficult to characterize, hindering efforts to understand the processes operating in these regions. We present a detailed study of genetic variation and underlying recombination processes in two copies of an LCR (NF1REPa and NF1REPc) on chromosome 17 involved in the generation of NF1 microdeletions and in a third copy (REP19) on chromosome 19 from which the others originated over 6.7 million years ago. We find evidence for shared hotspots of recombination among the LCRs. REP19 seems to contain hotspots in the same place as the nonallelic recombination hotspots in NF1REPa and NF1REPc. This apparent conservation of patterns of recombination hotspots in moderately diverged paralogous regions contrasts with recent evidence that these patterns are not conserved in less-diverged orthologous regions of chimpanzees.     

The promise of induced pluripotent stem cells in research and therapy

The field of stem-cell biology has been catapulted forward by the startling development of reprogramming technology. The ability to restore pluripotency to somatic cells through the ectopic co-expression of reprogramming factors has created powerful new opportunities for modelling human diseases and offers hope for personalized regenerative cell therapies. While the field is racing ahead, some researchers are pausing to evaluate whether induced pluripotent stem cells are indeed the true equivalents of embryonic stem cells and whether subtle differences between these types of cell might affect their research applications and therapeutic potential.     

下雨的味道从何而来

正有人凭借雨前的味道可以预知暴风雨的来临,骆驼凭借雨后的味道可以找到绿洲。那么,下雨的味道究竟是什么样的?如果有人声称能靠嗅觉预测暴雨,他可不是在夸口。不同的天气有不同的味道,嗅觉灵敏的人能分辨出这些味道。人们可以用鼻子嗅出大旱,也能闻到夏初的超级雷暴雨——事实上,干旱过后的雨水味道比平时更浓烈些。那么,夏日的雨究竟是什么味道?