Toyokazu Fukushima

Molecular weight heterogeneity of bovine serum transferrin

Cattle transferrin (Tf) was purified from serum of variant A and four bands were isolated. The peptide patterns of these bands when cleaved by proteases and by cyanogen bromide (BrCN) were compared, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Variant A displays two groups of molecules—large (L) and small (S)—on SDS-PAGE; the molecular weight of the L bands is 78,400±1700 and that of the S bands is 72,000±1700. However, S-band molecules could not be produced artificially by heat treatment of L bands in the presence of SDS and 2-mercaptoethanol. Since deglycosylated Tf also showed molecular weight heterogeneity, the sugar moieties of Tf other than sialic acids were not the cause of the heterogeneity. These results suggest that heterogeneity within a given variant is due to the presence of two kinds of molecule of different molecular weight. The peptide patterns of L and S bands produced by proteases and those produced by BrCN were distinctly different from each other. However, the stepwise degradation patterns of L and S bands resembled each other when treated with both chymotrypsin and BrCN. This suggests that L-band molecules differ from S-band molecules only in the presence of an additional carboxyl-terminal peptide.

Phylogenetical and ontogenetical studies on the molecular weight heterogeneity of bovine serum transferrin

Antitransferrin (Tf) rabbit serum was highly specific: it reacted with Tfs of ruminants, such as European breeds and Zebu breeds of cattle, Bali cattle, banteng, swamp and river types of water buffalo, anoa, goat, sheep, deer, antelope, camel, and giraffe, but did not react with serum of other non-ruminant species, such as pig, wild boar, hippopotamus, horse, rabbit, rat, chicken, etc. Electrophoresis of Tf and immunoglobulin G (IgG) complexes was carried out using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Within ruminants, the following species showed two Tf molecules on SDS-PAGE; European and Zebu cattle, Bali cattle, banteng, two types of water buffalo, and two species of anoa. Other ruminants, sheep, goat, deer, antelope, camel, and giraffe, etc., showed only one Tf molecule. The Tf heterogeneity in molecular weight was, thus, restricted to Bos, Bubalus, and Anoa. The molecular weight of Tf of water buffalo was slightly larger than that of cattle on the gel. The peptide pattern from cyanogen bromide cleavage of Tf of the water buffalo differed clearly from that of cattle. Fetal Tf showed only one molecule during development, but a newborn calf has two Tf molecules, (one large and one small) within 18 hr after birth. We suggest, therefore, that the small molecules formed during the last month of gestation. The peptide patterns of adult and fetal Tfs cleaved by cyanogen bromide differed with regard to the two large peptides; fetal Tf, lacking the second-largest peptide, had twice the amount of the largest peptide compared with adult Tf. From these results, we suggest that a change in peptide sequence occurs from the last month of gestation, when the largest peptide is degraded to the second largest. However, a Tf-like protein detected in the liver microsomal fraction has only one molecular size, both in adult and in fetal livers.

Autosomal genetic control of the activity of a new variant ornithine transcarbamylase in chicken kidney

The mode of inheritance of the gene for chick kidney ornithine transcarbamylase (OTC), found previously as a genetic variant, was investigated. White Leghorn B line males homozygous for the allele for the variant OTC gene were selected using the California Gray breed, having a near-absolute deficiency of the enzyme. Then further crosses of the two breeds were made. The mean value of the OTC level of F1 progeny was about 170 units. Chicks from the backcross generation were divided into two groups, of high activity and low activity, in a ratio of 1:1. F2 chicks were divided into three groups: one-fourth of the chicks were classified as a “super high” group, one-half were “high,” and the remaining one-fourth were “low” the mean values for OTC level were 356.7, 196.4, and 15.6 units, respectively. From these results, it was suggested that the variant OTC represents a simple autosomal incompletely dominant trait.

Genetically controlled quantitative variation of ornithine transcarbamylase in the chick kidney

This experiment was made to show that the marked variation in ornithine transcarbamylase (OTC) activity observed within a chicken breed or among breeds is due to quantitative changes, not qualitative ones. The enzyme was partially purified from three different chicken breeds, the White Leghorn B line, the Cochin Bantam breed, and a commercial line named “G,” by the following steps: (i) extraction of OTC with Triton X-100 and cetyl-trimethylammonium bromide, (ii) heating, and (iii) salting-out column chromatography. No difference was shown immunologically, enzymologically, or physicochemically among the partially purified OTCs. The enzyme amount determined using anti-bovine OTC antiserum was related linearly to the enzyme activity either from the same chicken breed or from different breeds. These results suggest that marked variation in OTC activity reflects variation in the amount of enzyme synthesized in the kidney, and this is controlled by regulatory genes encoded on an autosome, not the structural gene.

Genetic control of ornithine transcarbamylase induction in chick kidney

After ornithine transcarbamylase (OTC) induction by egg-yolk feeding, OTC activity increases rapidly in chicks bearing an Ocbgene. This response to an egg yolk diet does not appear in chicks having no Ocbgene (showing low OTC activity). The chicks showing intermediate OTC activity also respond to the diet, but moderately. Crossing experiments revealed that OTC induction by egg yolk-diet feeding is inherited as a simple autosomal dominant trait. Since a chick develops during embryonic life by utilizing egg yolk from the yolk sac, the variation of OTC activity among chicken breeds and within a breed in 2-day-old chicks seems to depend on a genetically controlled difference of inducibility by egg yolk. The Ocbis an autosomal gene which controls the induction of OTC activity, but it is difficult to explain the consistent difference in OTC activity between sexes by involving this gene or this locus alone.

Comparison of renal ornithine transcarbamylase activities within different chicken breeds

Comparisons were made of the renal ornithine transcarbamylase (OTC) activities within different groups of chickens including Japanese native breeds. OTC activities varied markedly within these groups. The Cochin Bantam breed and White Leghorn B line had an especially high activity, about 400 units/g of kidney, in contrast to two Japanese native breeds, Japanese Game (white variety) and Banshuu Gashiwa, and the California Gray breed, which showed a very low activity, the values being almost undetectable. In crossing experiments using the California Gray breed as a tester strain, Cochin Bantam OTC represents a simple autosomal incompletely dominant trait similar to the White Leghorn B line OTC. Kinetic studies using partially purified OTC preparations from the White Leghorn B line and Cochin Bantam breed revealed that both enzymes were identical for a variety of enzymic characteristics. In light of these results, the physiological significance of chick kidney OTC is discussed.

The Effects of Two Stage Selection Based on Performance and Progeny Testing on the Genetic Gains

能力検定および後代検定の2段階にわたる選抜が各段階の対象形質(形質1;形質2)の遺伝的改良量に及ぼす影響をシミュレーション法により検討した.集団の大きさは1,000(雌雄各500)とし,第1段階選抜は形質1による個体選抜(選抜率は雄10%,雌40%),第2段階は形質2の後代の平均による選抜(選抜率は雄に対してのみ50%)を10世代にわたり実施した.両形質は2遺伝子群上の2対立遺伝子を持つ14遺伝子座に支配され,基礎集団の遺伝子頻度はいずれも0.5とした.相加的遺伝様式を想定して遺伝子型価を決定し,表型価は遺伝子型価に環境偏差(NID(0,σe2))を加え算出した.初期遺伝率(h210;h220)は0.6, 0.4および0.2を組合わせ,初期遺伝相関(rgo)は多面作用による0.16, 0, -0.16を設定した.したがって計27通りの選抜実験を実施し,両形質の累積改良量(ΔCG1;ΔCG2)を算出した.結果は第1あるいは第2段階選抜のみを行なった場合の10世代時の累積改良量を対照として%表示した.ΔCG1は中期までは対照区と大差はないが,後期にはrgoが低く,h220が高いほど低下した.ΔCG2は2形質の遺伝率と遺伝相関の組合わせにより異なり,rgoが正でh220が0.6の場合,ΔCG2は対照区に比べ低かったが(10世代において対照区の60～80%),h220が0.2では間接選抜反応が加わり大きなΔCG2(120～140%)を示した.逆にrgoが負の場合,ΔCG2は著しく低下し,最も高い場合でも40%(h210=0.2,h220=0.6)にとどまった.この傾向はh210が高いほど顕著で,h210=0.6では負のΔCG2さえ示した.rgoが0の場合のΔCG2は,初期には対照区と大差はないが,後期には低下し,rgoが正の場合と負の場合との中間を推移した.