In order to investigate the phylogenetic status of the Okhotsk people that were distributed in northern and eastern Hokkaido as well as southern Sakhalin during the fifth to the thirteenth centuries, DNA was carefully extracted from human bone and tooth remains excavated from archaeological sites. The hypervariable region 1 sequences of the mitochondrial DNA (mtDNA) control region were successfully amplified and 16 mtDNA haplotypes were identified from 37 individuals of the Okhotsk people. Of the 16 haplotypes found, 6 were unique to the Okhotsk people, whereas the other 10 were shared by northeastern Asian people that are currently distributed around Sakhalin and downstream of the Amur River. The phylogenetic relationships inferred from mtDNA sequences showed that the Okhotsk people were more closely related to the Nivkhi and Ulchi people among populations of northeastern Asia. In addition, the Okhotsk people had a relatively closer genetic affinity with the Ainu people of Hokkaido, and were likely intermediates of gene flow from the northeastern Asian people to the Ainu people. These findings support the hypothesis that the Okhotsk culture joined the Satsumon culture (direct descendants of the Jomon people) resulting in the Ainu culture, as suggested by previous archaeological and anthropological studies.

In order to further understand the genetic status of the Okhotsk people, who were distributed in southern coastal regions of the Okhotsk Sea during the 5th-13th centuries, nucleotide variations in the hypervariable region (HVR) and the coding regions of mitochondrial DNA (mtDNA) were analyzed. Targeting the coding regions provides reliable genetic information even from ancient DNAs that may have suffered post-mortem damage. MtDNA haplogroups of 38 individuals were classified according to mtDNA lineages known in northeastern Asian people. Comparisons of mtDNA haplogroup frequencies between the Okhotsk people and other Asian populations revealed that the genetic structures of the Okhotsk people are very similar to those of populations currently living around lower regions of the Amur River and the Ainu of Hokkaido. The results support our previous study on molecular phylogeny of mtDNA HVR 1 sequences, and strongly suggest that the Okhotsk people originated around the lower regions of the Amur River and became an intermediate of gene flow from the continental Sakhalin people to the Ainu.

Human earwax is classified into wet and dry types, which are determined by a single-nucleotide polymorphism in the adenosine triphosphate-binding cassette, sub-family C11 (ABCC11) gene locus. To investigate the allele frequencies of the ABCC11 locus within ancient populations on the Northern Japanese island of Hokkaido, amplified product-length polymorphisms were analyzed for 50 specimens of the Okhotsk people and 35 specimens of the Jomon and Epi-Jomon people excavated from various archaeological sites of Hokkaido. Of these specimens, 31 Okhotsk and 19 Jomon/Epi-Jomon samples were genotyped successfully. Frequencies of the wet-type allele in the Jomon/Epi-Jomon people, considered a major ancestor of the Ainu, were higher than those of other Northeastern Asian populations, including the modern Ainu. By contrast, in the Okhotsk people, believed to originate from East Siberia, frequencies of the dry-type allele were relatively higher than those in the Ainu and Jomon/Epi-Jomon people. These results suggest that gene flow from the Northeastern Asian Continent to descendants of the Jomon/Epi-Jomon people of Hokkaido through the Okhotsk people occurred, resulting in the establishment of the Ainu.

The reduction of formaldehyde by ammonium carbonate was examined in cadavers and in vitro. Formaldehyde concentrations in the air (10 cm above human cadavers) and in various cadaveric tissues were measured with or without perfusion of ammonium carbonate solution into formaldehyde-fixed cadavers. Air samples were monitored using Kitagawa gas detector tubes. For measurement of formaldehyde in tissues, muscles and organs were cut into small pieces and tissue fluids were separated out by centrifugation. These specimen fluids were diluted, supplemented with 3-methyl-2-benzothiazolinone hydrazone hydrochloride and quantified by spectrophotometry. In five cadavers without ammonium carbonate treatment, the formaldehyde concentrations in the air above the thorax and in various tissue fluids were 1.2-3.0 p.p.m. and 0.15-0.53%, respectively. Arterial reperfusion of saturated ammonium carbonate solution (1.0, 1.5 or 2.0 L) into five formaldehyde-fixed cadavers successfully reduced the formaldehyde levels, both in the air (0.5-1.0 p.p.m.) and in various tissue fluids (0.012-0.36%). In vitro experiments demonstrated that formaldehyde concentrations decreased, first rapidly and then gradually, with the addition of ammonium carbonate solution into fluids containing formaldehyde. It was confirmed that formaldehyde reacted with the ammonium carbonate and was thereby changed into harmless hexamethylenetetramine. The application of ammonium carbonate solution via intravascular perfusion and, if necessary, by infusion into the thoracic and peritoneal cavities, injection into muscles and spraying on denuded tissues can be anticipated to reduce formaldehyde to satisfactorily low levels in cadaveric tissues and, consequently, in the air, which may provide safe and odorless dissecting rooms.

To investigate the genetic characteristics of the ancient populations of Hokkaido, northern Japan, polymorphisms of the ABO blood group gene were analyzed for 17 Jomon/Epi-Jomon specimens and 15 Okhotsk specimens using amplified product-length polymorphism and restriction fragment length polymorphism analyses. Five ABO alleles were identified from the Jomon/ Epi-Jomon and Okhotsk people. Allele frequencies of the Jomon/Epi-Jomon and Okhotsk people were compared with those of the modern Asian, European and Oceanic populations. The genetic relationships inferred from principal component analyses indicated that both Jomon/Epi-Jomon and Okhotsk people are included in the same group as modern Asian populations. However, the genetic characteristics of these ancient populations in Hokkaido were significantly different from each other, which is in agreement with the conclusions from mitochondrial DNA and ABCC11 gene analyses that were previously reported.