Molecular genetic analysis of remains of a 2,000-year-old human population in China-and its relevance for the origin of the modern Japanese population.

We extracted DNA from the human remains excavated from the Yixi site ( approximately 2,000 years before the present) in the Shandong peninsula of China and, through PCR amplification, determined nucleotide sequences of their mitochondrial D-loop regions. Nucleotide diversity of the ancient Yixi people was similar to those of modern populations. Modern humans in Asia and the circum-Pacific region are divided into six radiation groups, on the basis of the phylogenetic network constructed by means of 414 mtDNA types from 1, 298 individuals. We compared the ancient Yixi people with the modern Asian and the circum-Pacific populations, using two indices: frequency distribution of the radiation groups and genetic distances among populations. Both revealed that the closest genetic relatedness is between the ancient Yixi people and the modern Taiwan Han Chinese. The Yixi people show closer genetic affinity with Mongolians, mainland Japanese, and Koreans than with Ainu and Ryukyu Japanese and less genetic resemblance with Jomon people and Yayoi people, their predecessors and contemporaries, respectively, in ancient Japan.     

Colocalization of glucagon-like peptide and glucagon immunoreactivities in pancreatic islets and intestine of salmonids

Summary Pancreatic islets of salmon contain at least two peptides of the glucagon family: 29-amino acid glucagon and 31-amino acid glucagon-like peptide (GLP). Both peptides were recently isolated from the pancreatic islets of coho salmon and sequenced (Plisetskaya et al. 1986). Antibodies generated against these two peptides and against human glucagon were used as immunocytochemical probes to investigate whether glucagon and GLP are processed in the same, or in different cell types in the pancreatic islets and the gut of salmon. Two salmonid species, rainbow trout and coho salmon, were studied. All islet A-cells in the two species were immunoreactive toward both anti-salmon (s)-glucagon and anti-s-GLP. Similar colocalization of glucagon and GLP immunoreactivities was found in open-type endocrine cells in mucosae of the small intestine (including the pyloric coecae) and the large intestine close to the vent of rainbow trout. None of the antibodies stained mucosal cells of the body of the stomach. These results suggest that in the pancreas and the gut of salmonid fish the same cells produce both glucagon and GLP. These peptides are most likely the products of a single gene coding for the preproglucagon sequence.     

Physiological Structure of the Critical Photoperiod of Lemna paucicostata 6746

The critical day length or the length of the critical photoperiodfor the short-day duckweed, Lemna paucicostata 6746 is about14 h (Oota 1983). With the min-SD method, I found that not thewhole critical photoperiod but only its initial and terminalbrief fractions, called respectively the LI- and L2-phases,need be illuminated for a given day to be a noninductive day.Inversely, the darkened LI- and/or L2-phase makes the day inductive.The rest of the day can be either darkened or illuminated withoutmodifying the inductive or noninductive property of the day. Thus, the physiological structure of the critical photoperiodfor L. paucicostata 6746 closely resembles that of the criticalphotoperiod for the long-day duckweed, L. gibba G3 (Oota 1981). (Received May 24, 1983; Accepted September 21, 1983)     

Evidence against involvement of circadian floral rhythm in the critical daylength measurement in Lemna gibba G3

Using the min-LD method, light requirements of the L1- and L2-phasesof L. gibba G3 were found to be satisfied by only 5 min illuminationgiven respectively from CT 0:00 to 0:05 and from CT 11:55 to12:00. This rigorous time sense was displayed without any alterationeven in the presence of iron reagents, e.g., 10^–5 M o-phenanthroline,10^–5M,'-dipyridyl and 10–6 M kinetin, which completely eliminatedcircadian rhythmicity in reproductive (flower production) aswell as vegetative (frond production) response to a light pulsescanning a continuous dark period. Circadian rhythms of metabolicactivities, e.g., active K⁺ ion uptake and respiratory CO₂ output,were not changed at all by the iron reagents. These and relevantresults suggested that in this long-day duckweed, the circadianoscillator, probably located in the meristem and sensitive toiron deficiency, only modulates the frond and flower productionin the meristem and is not related to the critical daylengthmeasurement. (Received December 18, 1978; )     

Spectral dependence of the critical photoperiod in the long-day duckweed, Lemna gibba G3

Spectral dependence of the light sensitive L1- and L2-phasesof the critical photoperiod of Lemna gibba G3 was examined bythe min-LD method for wavelengths ranging from ca. 420 to 800nm. The L1-phase had a sharp peak of sensitivity at 650–680nm and a gentle slope of sensitivity ascending from 500 nm towardshorter wavelengths. The L2-phase showed remarkable sensitivityaround 750 nm and in the blue-violet regions (500 nm). Red/far-redphotoreversibility was confirmed for the LI-phase, but not forthe L2-phase. The properties of the light receptors involvedare discussed briefly. ¹Present address: National Institute for Basic Biology, Myodaiji,Okazaki 444, Japan. (Received May 14, 1979; )     

Female preference for temporal features of vocalization in the Japanese treefrog,Rhacophorus arboreus

Female preference for the different temporal features of advertisement calls by males was studied in the foam-nesting treefrog,Rhacophorus arboreus. Field observations showed that females were attracted to males making more calls, calling in more bouts of vocalization and leading choruses. In phonotactic experiments in the laboratory, however, females were attracted to vocalizations with more total notes while they were not attracted to chorus leaders. alphabetical order     

Extreme mtDNA homogeneity in continental Asian populations

Mitochondrial DNA (mtDNA) variation in continental Asia has not been well-studied. Here, we report mtDNA HV1 sequences for 84 Xi'an and 82 Changsha Han Chinese, 89 Honshu Japanese, and 35 Vietnamese. Comparison of these sequences with other Asian mtDNA sequences reveals high variability within populations, but extremely low differentiation among Asian populations. Correlations between genetic distance and geographic distance, based on mtDNA and Y chromosome variation, indicate a higher migration rate in females than in males. This may reflect patrilocality, as suggested previously, but another plausible hypothesis is that the demographic expansion associated with the spread of agriculture in Asia may be responsible for the extreme genetic homogeneity in Asia.