Chromosomal location of genes for fertility-restoration, awnlessness, spelta-type ear and red coleoptile color of Triticum spelta var. duhamelianum, an effective fertility- restorer for the timopheevi cytoplasm, was determined by monosomic analysis. The results can be summarized as follows:
T. spelta var. duhamelianum carries a dominant fertility-restoring gene Rf₃ on its chromosome 1B. Chromosome 7D exerts a weak suppressing effect to this gene. Awnlessness is mainly due to an epistatic inhibitor B₁ in chromosome 5A, while chromosome 6D has a promoting effect on awn development. As to the ear type, chromosome 5A carries a spelta gene q₁, whereas chromosomes 2D and 3D possess some modifiers to this gene. Red coleoptile color is produced by genes in chromosomes 7A and 7D, while five other chromosomes, 2A, 2B, 2D, 3B and 6A, carry weak suppressors.

抄録全体を表示

An anomalous sex-chromosome constitution was observed by chance in a case of phenotypically normal female golden hamster. Bone marrow metaphases of this animal showed 44 chromosomes with a karyotype which was indistinguishable in general appearance from that of the normal male. Two tentative interpretations were made for the sex-determining mechanism of the present specimen: one is the XY constitution in which the Y chromosome had lost its male factors due to the interchange of genetic materials between the X and the Y at the time of meiotic segregation, and the other deals with a partial short arm deletion in one of the two X chromosomes.

抄録全体を表示

A recessive visible mutant, rbl was found in Kofu-Katsunuma natural populations of Drosophila melanogaster. It was frequently extracted from the same natural population and its equilibrium frequency in the population was assumed to be 0.04. The locus of rbl was determined to be 82.3 on the right arm of second chromosome and the mutant gene linked often with an heterotic inversion, In(2L)B, on the left arm. The homozygous flies for rbl had lower viability, developmental rate, productivity and fecundity than normal heterozygous flies. However, rbl heterozygous flies showed remarkable heterosis in productivity and fecundity though they were neutral in viability and developmental rate. In such a relation we may see the mechanism of persistent of rbl gene in natural populations. The role of inversion, In(2L)B, was assumed to enchance the heterosis of rbl gene or its closely linked genes at least in the cis-phase.

抄録全体を表示

1. Comparisons were made of DNA content per nucleus in common wheat, artificially synthesized 6x wheat, its parental species and three analyzers.
2. DNA content per nucleus in the D genome analyzer was the lowest, B genome had a little lower DNA content than A genome, but the difference between the last two was not significant.
3. Ssp. strangulata had a significantly higher DNA value than var. typica of the same species, Ae. squarrosa.
4. Two strains of synthesized 6x wheat, ABD No. 1 and ABD No. 13, have nuclear DNA equal to the sum of the DNA contents of their respective parents. Nuclear DNA content of cultivated common wheat (Chinese Spring) is quite the same as that of synthesized 6x wheat, especially ABD No. 13.
5. In three subspecies of T. aestivum, vulgare, spelta and macha no significant difference was found in DNA content per nucleus.
6. Based on the above facts, the following conclusion may be reasonably drawn as far as wheat and its relatives are concerned:
a) Appreciable changes of DNA content might have resulted from chromosome aberrations accumulated in the course of genome differentiation of a common primitive genome at the diploid level.
b) The three different genomes, once established, have been appreciably stable and kept the amount of DNA constant either in diploid or polyploid condition.

抄録全体を表示

The in vitro effect of 4-nitropyridine 1-oxide (4NPO) and its reductive erivatives on the transforming DNA in Bacillus subtilis was investigated. Among six compounds used, only 4-hydroxylaminopyridine 1-oxide (4HAPO) was effective to inhibit the transforming activity of DNA. The inhibition took place only in the presence of air.
This led to a conclusion that 4HAPO itself is not the ultimate compound in the inhibition process of the transforming DNA but an oxidation product possibly of free radical character may be primarily responsible for this event.

抄録全体を表示

The segregation frequency of the stw³ second chromosome in the male, when made heterozygous with second chromosome of the cn bw stock, was found to be dependend upon the sex chromosome constitution. This finding argues for a critical re-examination of previous viability estimations which used D. melanogaster as the experimental organism.

抄録全体を表示

1. 前報において, タバコの葯を組織培養すると, カルスおよび四分子期の花粉から芽が分化することを報告した. カルスから発生した芽はたいてい細長い半透明の葉を備えた矮性の畸型植物で, 大多数は移植前後に枯死した. 四分子期の花粉から発生したと推定される芽は順調に発育して開花期に達した.
2. 3個の葯から発生した成体53株について染色体数を調査した結果, 49株が半数体, 3株が2倍体であった. 残りの1株はカルスから発生したと思われる矮性の畸型植物で, 染色体数の調査はできなかった.
3. 半数体のタバコに心止を行ない, 葉腋にコルヒチンを処理したところ, 染色体数の倍加した花はたいてい側枝の頂花または頂花とその周辺の数花に現われ, その後に咲く花は半数性を示した. 供試した34株中の24株から2倍性種子が得られた.

抄録全体を表示