Mitotic chromosomes are compacted laterally by KIF4 and condensin and axially by topoisomerase IIα

© 2012 Samejima et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication dateMitotic chromosome formation involves a relatively minor condensation of the chromatin volume coupled with a dramatic reorganization into the characteristic "X" shape. Here we report results of a detailed morphological analysis, which revealed that chromokinesin KIF4 cooperated in a parallel pathway with condensin complexes to promote the lateral compaction of chromatid arms. In this analysis, KIF4 and condensin were mutually dependent for their dynamic localization on the chromatid axes. Depletion of either caused sister chromatids to expand and compromised the "intrinsic structure" of the chromosomes (defined in an in vitro assay), with loss of condensin showing stronger effects. Simultaneous depletion of KIF4 and condensin caused complete loss of chromosome morphology. In these experiments, topoisomerase IIα contributed to shaping mitotic chromosomes by promoting the shortening of the chromatid axes and apparently acting in opposition to the actions of KIF4 and condensins. These three proteins are major determinants in shaping the characteristic mitotic chromosome morphology

Some pioneers of European human genetics

Some of the pioneers of human genetics across Europe are described, based on a series of 100 recorded interviews made by the author. These interviews, and the memories of earlier workers in the field recalled by interviewees, provide a vivid picture, albeit incomplete, of the early years of human and medical genetics. From small beginnings in the immediate post-World War 2 years, human genetics grew rapidly across many European countries, a powerful factor being the development of human cytogenetics, stimulated by concerns over the risks of radiation exposure. Medical applications soon followed, with the recognition of human chromosome abnormalities, the need for genetic counselling, the possibility of prenatal diagnosis and later, the applications of human molecular genetics. The evolution of the field has been strongly influenced by the characters and interests of the relatively small number of founding workers in different European countries, as well as by wider social, medical and scientific factors in the individual countries

Human genetics in troubled times and places

Abstract The development of human genetics world-wide during the twentieth century, especially across Europe, has occurred against a background of repeated catastrophes, including two world wars and the ideological problems and repression posed by Nazism and Communism. The published scientific literature gives few hints of these problems and there is a danger that they will be forgotten. The First World War was largely indiscriminate in its carnage, but World War 2 and the preceding years of fascism were associated with widespread migration, especially of Jewish workers expelled from Germany, and of their children, a number of whom would become major contributors to the post-war generation of human and medical geneticists in Britain and America. In Germany itself, eminent geneticists were also involved in the abuses carried out in the name of ‘eugenics’ and ‘race biology’. However, geneticists in America, Britain and the rest of Europe were largely responsible for the ideological foundations of these abuses. In the Soviet Union, geneticists and genetics itself became the object of persecution from the 1930s till as late as the mid 1960s, with an almost complete destruction of the field during this time; this extended also to Eastern Europe and China as part of the influence of Russian communism. Most recently, at the end of the twentieth century, China saw a renewal of government sponsored eugenics programmes, now mostly discarded. During the post-world war 2 decades, human genetics research benefited greatly from recognition of the genetic dangers posed by exposure to radiation, following the atomic bomb explosions in Japan, atmospheric testing and successive accidental nuclear disasters in Russia. Documenting and remembering these traumatic events, now largely forgotten among younger workers, is essential if we are to fully understand the history of human genetics and avoid the repetition of similar disasters in the future. The power of modern human genetic and genomic techniques now gives a greater potential for abuse as well as for beneficial use than has ever been seen in the past