Ancient Jomon genome sequence analysis sheds light on migration patterns of early East Asian populations

Funder: The excavation of the Ikawazu Jomon individual was supported by Grant-in-Aid for Scientific Research (B) (25284157) to YY. The Ikawazu Jomon genome project was organized by HI, and TH & HO who were supported by MEXT KAKENHI Grant Numbers 16H06408 and 17H05132, by Grant-in-Aid for Scientific Research on Innovative Areas (Cultural History of Paleoasia), and by Grant-in-Aid for Challenging Exploratory Research (23657167) and for Scientific Research (B) (17H03738). The Ikawazu Jomon genome sequencing was supported by JSPS KAKENHI Grant Number 16H06279 to ATo, and partly supported in the CHOZEN project in Kanazawa University, and in the Cooperative Research Project Program of the Medical Institute of Bioregulation, Kyushu University. Computations for the Ikawazu Jomon genome were partially performed on the NIG supercomputer at ROIS National Institute of Genetics.Abstract: Anatomically modern humans reached East Asia more than 40,000 years ago. However, key questions still remain unanswered with regard to the route(s) and the number of wave(s) in the dispersal into East Eurasia. Ancient genomes at the edge of the region may elucidate a more detailed picture of the peopling of East Eurasia. Here, we analyze the whole-genome sequence of a 2,500-year-old individual (IK002) from the main-island of Japan that is characterized with a typical Jomon culture. The phylogenetic analyses support multiple waves of migration, with IK002 forming a basal lineage to the East and Northeast Asian genomes examined, likely representing some of the earliest-wave migrants who went north from Southeast Asia to East Asia. Furthermore, IK002 shows strong genetic affinity with the indigenous Taiwan aborigines, which may support a coastal route of the Jomon-ancestry migration. This study highlights the power of ancient genomics to provide new insights into the complex history of human migration into East Eurasia

Improvement and recent applications of the Tohoku microbeam system

The microbeam system at Tohoku University has been applied to various fields since its installation and is mainly used for biological applications. The primary purpose of this work was to develop a 3D μ-CT, in which a microbeam is used as a monoenergetic point X-ray source. The second one was to develop a microbeam analysis system for biological samples. A beam spot of 0.4 × 0.4 μm2 at a beam current of several tens of pA has been produced. However, in our set-up, μ-PIXE/RBS analyses demand beam currents of ca. 100 pA, which restricts the spatial resolution to around 1 × 1 μm2. In order to get higher spatial resolution down to several hundred nm and higher beam current with a several μm resolution, a triplet lens system was designed and newly installed. This upgrade was carried out simultaneously with the recovery from the damage caused by the great east Japan earthquake. The triplet lens system has larger demagnification and was designed by adding a quadrupole lens to the existing doublet system. Although a beam spot size of 2 × 1 μm2 is currently obtained, it has not achieved the performance obtained by the previous doublet system. The doublet system has been recovered to its previous performance and is routinely applied to simultaneous μ-PIXE/RBS analysis in various fields. Recent applications of 3D-PIXE-μ-CT of toxic elements in single cells with the new microbeam system are presented