Yuichi Tanabe

Steroid hormone synthesis and secretion by testes, ovary, and adrenals of embryonic and postembryonic ducks

To elucidate the relationship between steroidogenesis and sex differentiation or sexual development in the birds, plasma LH, testosterone, 17 beta-estradiol, progesterone, corticosterone and cortisol, testicular and ovarian testosterone, 17 beta-estradiol and progesterone, and adrenal corticosterone, cortisol, progesterone, and testosterone concentrations from 15- to 26-day-old embryonic and 1- to 14-day-old postembryonic male and female ducks were determined by radioimmunoassays. Plasma LH level was high in embryos and decreased after hatching in both sexes. Both plasma testosterone and 17 beta-estradiol concentrations were statistically higher in female embryos than in male embryos, while sex differences were not observed in plasma progesterone, corticosterone, or cortisol concentrations. Both plasma corticosterone and cortisol reached a peak at hatching, and decreased thereafter. Testicular and ovarian testosterone, 17 beta-estradiol, or progesterone was much higher in female embryos than in male embryos. Adrenal corticosterone, cortisol, progesterone, and testosterone concentrations reached a peak 1 day after hatching, and decreased thereafter in both sexes. These results indicate that duck embryonic ovary is much more active in production and secretion of sex steroid hormones than the embryonic testes. It is suggested that the sex of the avian species is basically male having homozygoty of sex chromosomes (ZZ), and that estrogens secreted by the embryonic ovary have important roles in female sex differentiation. Very high levels of corticosterone and cortisol either in plasma or adrenals observed shortly after hatch suggest that corticosteroids have an important role in hatching of ducks to adapt themselves to a new environment.

Apolipoprotein E and H Polymorphisms in Mongolian Buryat: Allele Frequencies and Relationship with Plasma Lipid Levels

AbstractA Buryat population consisting of seven tribal groups in eastern Mongolia has been screened to determine the frequency distribution of different apolipoprotein E and H alleles (APOE and APOH, genes) coding for common isoforms and their association with quantitative plasma lipid levels. Allele frequencies at the APOE locus in 125 healthy Buryat aged 17 to 73 years were highest for APOE*3 (0.804), followed by APOE*4 (0.164) and APOE*2 (0.032). The APOH locus had high frequencies of APOH*2 (0.912) and APOH*3 (0.088). APOH*1 was not detected. No significant differences were observed in the overall APOE allele frequencies between the Buryat and the Siberian Evenki, Inuits, and Indians in Asia, or with some European whites. The frequency distribution of the overall APOH alleles of the Buryat was similar to that of the Japanese in Asia. Overall plasma lipid levels of the Buryat (males aged 20 to 73 years, females aged 21 to 64 years) were considerably lower, comparable to those of the Evenki. The APOE*4/E*3 males had significantly high total- and LDL-cholesterol levels compared with the APOE*3/E*3 males (p < 0.025 and p < 0.01, respectively). No significant effects of the APOH genotypes on any of the plasma lipid levels were ob- served. In particular, our data regarding APOE suggest that the Buryat are genetically close in allele frequencies to the Evenki and Inuits, but differ from them in the association of genotype APOE*4/E*3 with cholesterol levels.

β-Globin Gene Cluster Haplotype Frequencies in Khalkhs and Buryats of Mongolia

ABSTRACT β-globin gene cluster haplotype frequencies of 169 Khalkhs and 145 Buryats were estimated, and their characteristics were compared with those of Evenkis, Oroqens, Koreans, Japanese, and three Colombian Amerindian groups. The present study suggests that Colombian Amerindians diverged first from Asian populations and then Buryats diverged from other Asian populations.

Apolipoprotein E polymorphism and plasma lipid levels in Native Mongolian sheep.

Apolipoprotein E (apoE) phenotypes weredetermined in 199 unrelated native sheep (Khalkhas line)of Central Mongolia, using a polyacrylamide gelisoelectric focusing-immunoblotting technique, and theplasma lipid levels in different phenotypes wereassayed enzymatically. Twenty-eight phenotypes wereidentified in this sheep. In addition to all thepreviously detected seven apoE variants composing thephenotypes, four new variants were discovered, which werecalled E8, E9, E10, and E11. From the population data,these were found to be genetically controlled by fourcodominant alleles, designated APOE8,APOE9, APOE10,and APOE11, based on the same modeof inheritance as in the seven variants. These alleleswere detected at a low frequency, in the range of 0.005to 0.0126. The Khalkhas sheep differed mostsignificantly from the Baruwal and Lampuchhre sheep of Nepaland the Vietnamese sheep with respect to the allelefrequencies found in some Asian local sheep previouslyexamined. Type 1/1 and/or 2/7 sheep had significantly higher plasma levels of total cholesterol andlow-density lipoprotein cholesterol than type 7/7 sheep(P < 0.05 and/or P <0.02).

A procedure for the determination of plasma thyroxine in farm animals

ラジオステレオアッセイ法による家畜の血漿中サイロキシン測定を行なうため,抽出条件の検討を行ない次の結論を得た.1) 血漿中サイロキシンの抽出溶媒としては,アルコールとケトンの類が優れているが,なかでも蛋白凝固力,蒸発除去の難易などを考慮すると血漿の2-3倍量のエタノール使用が最適である.2) 血漿に2倍量のエタノールを加えてサイロキシンを抽出した場合,抽出液にサイロキシン結合能を有する血漿蛋白質が混入した.この混入蛋白質が血漿中サイロキシン測定値を負にする主因と考えられる.3) 抽出液中の混入蛋白質は,抽出液を乾固後エタノールで再抽出する方法でほとんど除去され,サイロキシン結合能も失なわれる.すなわち,再抽出法によって蛋白質混入による血漿中サイロキシン測定値の低下は防止される.4) 抽出液の蒸発乾固によってはサイロキシンの散逸は起こらない.