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Volume 31, Issue 8-9
Displaying 1-5 of 5 articles from this issue
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Warren H. LEONARD, D. W. ROBERTSON, H. O. MANN1956 Volume 31 Issue 8-9 Pages 229-240
Published: 1956
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSPlant height inheritance is reported for three crosses between short-stemmed barley varieties. So far as possible, the parent, varieties, F1, and F2 generations were grown during the same season in such a manner as to reduce to a minimum the effect of environment on plant height. Height measurements were made on the parents, as well as on the progenies of crosses, grown under comparable field conditions in 1950, 1951, and 1953.
Two complementary factor pairs appear to control plant height in two crosses that involve short or semi-brachytic varieties, viz., Baitori No. 10×Brachytic No. 119, and Katano×Brachytic No. 119. Transgressive segregation for plant height was observed in the F1 and F2 generations in each case. The plant types recovered in the field included those of normal (tall) height and the parental forms. Based on the assumption of a lethal or semi-lethal double recessive or double dwarf class, the F2 data afforded a good fit to a calculated 9:6:0 or 9:3:3:0 ratio. One family of the Baitori No. 10×Brachytic No. 119 cross was grown in the F3 generation in order to verify the F2 genotypes. The data afforded a poor fit to a calculated 1:4:4:6:0 ratio, because of too many plants in the homozygous tall class. With the exception of the double dwarf class, all expected classes were obtained. The existence of the postulated double dwarf class was verified in another F2 family of the same cross grown in the greenhouse. The data for these crosses indicate the action of two independent gene pairs with complementary effects on plant height, with each parent dominant for one height factor but recessive for the other.
It is suggested that tall versus short (Uzuz) and non-brachytic versus brachytic (Brbr) were the two gene pairs involved in this study. Testers were not available to verify the presence of the uz gene.View full abstractDownload PDF (1225K) -
Tatsuo ISHIKAWA, Nobunori TANAKA1956 Volume 31 Issue 8-9 Pages 241-249
Published: 1956
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe spontaneous reversion frequency of homocysteine requiring strain (4-24) of Ustilago maydis was determined as 23×10-5 per sporidium on the minimal media supplemented with 1×10-5mg/ml methionine. This genetic block in the biochemical pathway between cystathionine and homocysteine has been elucidated as due to one genic step. In contrast to the current opininon, the reversion in the present strain, now observed, does not take place in one step but step by step through two distinct transient steps. It reverted in sequence of 4-24→PRT 1→PRT 2→CRT; where PRT and CRT denoted respectively, partial reversion type and complete reversion type. It is noted that the two transient types, PRT 1and PRT 1, are as stable as the original strain.
Studies of the growth rate of these reversion types have shown that the present partial reversion is explicable by the leakage, the mechanism of which, however, is not yet settled in the present experiments.View full abstractDownload PDF (1250K) -
Ryuhei TAKAHASHI, Jiro HAYASHI1956 Volume 31 Issue 8-9 Pages 250-258
Published: 1956
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSA study was made of the genetic behaviors of some crosses involving the genes for uzu and brachytic characters, with particular reference to the effects of these dwarf genes upon various characters of different types that segregated from these crosses. As the results, it was confirmed that, in spite of the close similarity in their effects, the gene, uz, for uzu character and br for brachytic one were inherited independently, and that an extraordinary dwarf type, called br-uz, arised as their complementary action. Both of the dwarf genes exerted diminutive effects upon the sizes of various plant parts examined, but the magnitude of effects varied considerably with plant parts. Comparison of the uzu and brachytic-type segregates in a few crosses has revealed that the uzu gene may be rather superior at least under our growing condition to the brachytic gene from agricultural point of view. It appears that the diminutive effects of uz and br on various characters in br-uz are on the whole additive, but it may be safe not to draw such a general conclusion as to their complementary action.View full abstractDownload PDF (1517K) -
Masanaka TERADA, Isamu KONDO, Tomokazu OGAWA1956 Volume 31 Issue 8-9 Pages 259-265
Published: 1956
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS1) Recently we have found an interesting plaque dissociation phenomenon in some viral strains of S. gallinarum (Akita strain) phage and S. sendai (S. 71 strain) phage. These viruses were called as s type virus.
2) The pure stock of s type virus forms the so-called sector type plaques on Sg or PA. The subculture from this sector type plaque gives the mixture of a majority of original sector type plaques and several non sector type plaques whenever Sg or PA is used as indicator bacterium.
3) Furthermore in the subculture from the latter (non sector type) plaque we can obtain the pure stock of the r type virus which always gives only the r type plaques without any sector on Sg or PA. And this segregant r type virus shows no tendency to revert to the original s type virus.
4) Besides the unique pattern of this dissociation phenomenon, it is considered to be very interesting that the occurrence of this specific phenomenon can be detected on indicators Sg and PA but not on PK and Pl.
5) Two speculations were put into consideration for the explanation of the genesis of this curious phenomenon.
One is the assumption of a mutable gene locus in these s type viruses……(a).
Another is that of a partial diploid structure which differs in various points from the so-called residual heterozygote reported by Hershey……(b).
(6) Through several recombination analyses we have obtained some experimental data supporting the latter speculation (b). In other words we prefer to consider that these s type viruses have a somewhat heterozygous and partial diploidic structure in their gene constitution.
However, we do not want to leave the impression that we insist upon considering speculation (b) as the only possibility. It is our hope that we may someday fully investigate the genesis of this phenomenon through the study of this interesting virus material, e. g., the analysis of the segregant from newly formed sector type virus.View full abstractDownload PDF (1015K) -
Francis J. RYAN1956 Volume 31 Issue 8-9 Pages 266-278
Published: 1956
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSRecent work on allelism and pseudoallelism, especially with microorganisms, is discussed. It is concluded that the functional gene may be divisible into smaller mutable and recombinable components. The position effect observed with pseudoalleles can be caused, therefore, by mutations with the smaller genetic sub-units of the functional gene. Although the hypothesis of pseudoallelism between genes with different functions is not incompatible with the notion that functional units are subdivisible, no critical evidence is as yet at hand compelling this interpretation of the pseudoallelic position effect.View full abstractDownload PDF (1395K)
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