The variation of photoperiodic adult diapause was studied in Drosophila auraria strains originating in Japan at latitudes from 33.8 to 43.1°N. All the differently-located geographical strains showed a photoperiodic diapause. The critical daylength of these strains fell between 12 and 14h. The diapause intensity increases with an increase in latitudes. The duration of diapause was shorter at a photoperiod of 12 or 6h than at one of 10 or 8h in all the strains. This is because the photoperiod of 12 or 6h is less effective as a stimulus for the maintenance of diapause.
Fifty seven strains of KUSE (Kyoto University Scientific Expedition to The Karakoram and Hindukush) collection and three laboratory strains of Aegilops squarrosa were examined with respect to α-amylase isozymes of germinating seed. Seven zymogram patterns were identified, each of which consisted of a few isozyme bands most probably specified by the genes on chromosome 6D and only one by the gene on chromosome 7D. Among varieties of Ae. Squarrosa, var. typica was most variable, followed by var. strangulata. Variation in α-amylase isozymes, as in the other various characters, was most concentrated in the region of Gorgan, in decreasing order being the regions of Pahlavi, Tabriz and Tehran, and no variation in the other regions. From comparison of the zymograms between tetra- and hexaploid wheat, a particular zymogram pattern of α-amylase, Ams 3 was concluded as the one expected in the D genome donor to the main line of descent of hexaploid wheat. Ams 3 located most predominantly in the region of Gorgan, extending westwards along the south coast of Caspian sea up to Derbent, Caucasus. Therefore, it is most reasonable to consider that birthplace of hexaploid wheat should be extended to the south-east coast-land of Caspian sea from the area including south-west Caspian coast region and Transcaucasus, which the previous authors have indicated. On the other hand, discussion about independent origin of ssp. macha was made in view of the variant zymogram pattern.
Effect of high temperature on meiotic homologous chromosome pairing of common wheat was examined. According to the experimental results, constant high temperature of 30°C significantly reduced homologous pairing compared with 15, 20 and 25°C, and such effect was recognized only when the PMCs of some limited stage immediately before premeiotic S phase were exposed to the temperature. Besides, the high temperature did not affect the pairing of both arms of an isochromosome (1A-long-arm) at all. It was strongly suggested from these results that (1) high temperature of 30°C disturbs the process of pairing at a step which controls premeiotic inter-homologues attraction, creating such a situation as homologues are spatially kept away each other, and (2) this step may closely be connected with a peculiar stage sensitive to the high temperature. A similarity of acting mechanism among high temperature, colchicine and Ph allele was also discussed.
A new regulatory mutant, KA231 (ilvC8 brnQ4 liv-231), derepressed in the transport of branched-chain amino acids was isolated from a transport-defective mutant, CE5 (ilvC8 brnQ4) of Salmonella typhimurium LT2. Kinetic analysis of isoleucine and leucine transports indicated that activities of the high-affinity and the low-affinity-(1) systems of KA2313, an Ilv+ transductant of KA231, were increased 1.3- to 2.5-fold over the levels of KA204 (brnQ4). The activity of specific binding protein(s) found in the periplasmic space of KA2313 cells was also increased several-fold. Glycyl-L-leucine was able to repress both the transport and the binding activities of KA2313, but the extent of repression was weaker than that of repression induced in wild-type strain. Nature of liv-231 mutation distinct from another regulatory mutation, gleR, is discussed.
The integration of the λ phage genome in the absence of site specific recombination was investigated. An int through red gene deleted λgalbio transducing phage was infected onto gal through uvrB gene deleted E. coli cells of rec+ or recA. Rare lysogens were selected as the gal+ transductants on minimal agar which contains galactose as a sole carbon source. All of the gal+immλ+ transductants examined carried prophage genomes within the host chromosomes. The integration of λgal bio phage genome into the rec+ host seemed to occur about 300 times more efficiently than in the recA strain. Approximate chromosomal locations of these prophage genomes were mapped by mating experiments. Eight independently isolated gal+rec+ lysogens were all found to have the prophage genomes near the nalA gene. Among nine independently isolated gal+recA lysogens, eight lysogens had the prophage genomes near the lac gene and the remaining one near the rac gene. The prophage gene order was examined in the three rec+ and four recA lysogens by deletion mapping and all of the λgal bio genomes present within these lysogens were found to have been integrated by the crossover occurring somewhere between J and gal of the transducing phage genome. General properties of these lysogens were examined.
To examine the usefulness of ovule culture for the production of intergeneric or interspecific hybrids in Brassica and Raphanus, experiments were carried out in 1978 and 1979. Ten to 20 days after pollination, ovules were inoculated on basic White's (1963) agar medium supplemented with 150ml/l coconut milk, 2.5mg/l naphthaleneacetic acid (NAA) and 2.5mg/l kinetin. Germinated embryos were transferred to basic Murashige and Skoog's (1962) medium supplemented with 0.5mg/l NAA and 2.5mg/l kinetin. After being cultured on filter paper bridges sustained by Murashige and Skoog's (1962) liquid medium, seedlings were transferred to pots. Of 14 cross combinations tested in 1978, 5 combinations gave hybrids by ovule culture, among which 4 combinations did not produce hybrids by the usual crossing method. In 1979, cultures were focused on the crosses between the B. campestris and the B. oleracea groups. The ovule culture was superior to the embryo and ovary cultures in terms of the production rate of hybrids, when B. oleracea was used as the female parent. When B. oleracea was used as the male parent, the ovule culture gave a better result than the embryo culture, but was less effective than the ovary culture. The way to improve the yield of hybrids was discussed.
Electrophoretic survey of Id-1 alleles in the Japanese wild mouse, Mus musculus molossinus, revealed the existence of four alleles, Id-1a, Id-1b, Id-1c and Id-1d. Two alleles, Id-1c and Id-1d, are not present in European and American wild mouse populations, had overall frequencies of .138 and .006, respectively, in the Japanese mouse. The Id-1b allele was most frequent (.782) and Id-1a was relatively rare (.074). Geographically, the northern populations possess mostly Id-1b allele (.985), while Id-1a, Id-1b, and Id-1c alleles are common in the southern regions. This geographical distribution can be explained by the multiple migration hypothesis of the wild mouse into Japan through two southern routes. This explanation is partly supported by the presence of Id-1c allele in the Asian house mice from the Philippines and Thailand.
A female LEW (Lewis) strain rat with the chromosome mosaic consisting of two types was originally obtained; from this rat offspring with the normal and the inversion pair no. 1 (+/i) were obtained. By use of the latter rats, the segregation of the inversion pair no. 1 was examined by the following combination of matings; inversion heterozygous females and normal males (+/i_??_×+/+_??_), its reciprocal (+/+_??_×+/i_??_), and female and male inversion heterozygotes (+/i_??_× +/i_??_). Inversion heterozygotes and homozygotes were segregated in their offspring as we expected, but the number of inversion homozygotes was slightly smaller than the expected one, although there is no significant difference. Based on the litter size in the offspring, the fertility of the inversion heterozygotes and homozygotes were examined. The litter size from the inversion heterozygotes was slightly smaller than the control, but that from the inversion homozygotes was not different from the control one. This means that the fertility of the Norway rat with inversion pair no. 1 was normal.
Further characterization of Lhr gene, which rescues the lethal hybrid of D. melanogaster and D. simulans, was made using several mutants of D. melanogaster. It was known that hybrids carrying the Y chromosome of D. simulans are lethal without exception, that is, hybrids carrying X chromosome of D. simulans are all viable except a female hybrid of female simulans and male melanogaster. Lhr rescues all the lethal hybrids carrying simulans Y (=hybrids without carrying simulans X). Brief discussion on the character of hybrid lethality between the two species and how the Lhr works are presented.
Mature and immature oocytes of D. melanogaster were found to show no significant difference in their sensitivity to the induction of dumpy mutations by X-rays. Genetic analysis of the recovered dumpy mutants suggested that the majority were produced without apparent breakage. Uniform sensitivity of mature and immature oocytes to X-ray-induction of point mutations may be inferred from these findings.