Induction of calli from rice (strain A-58) and soybean (cv. Harosoy) protoplast mixtures treated by polyethyleneglycol (PEG) was successful and hybrid calli were able to be identified and selected by the observation of a blackish purple pigment of fravonoids in the rice calli and a softness in the soybean calli. However, the blackish purple pigment of hybrid calli disappeared rapidly after one or two subcultures. The peroxidase and esterase isozyme band patterns of all hybrid calli after several subcultures were that of soybean callus. From these results, it can be supposed that rice chromosomes are rapidly eliminated, while soybean nuclear genome may be retained in the hybrid calli. During subcultures of the hybrid calli, yellow, green and white calli have been segregated. The soybean calli were usually yellow, but sometimes turned green. The rice calli were a blackish purple which was so unstable that whitish yellow calli were often obtained. When all these calli were transferred onto the medium containing 1-naphthaleneacetic acid (NAA) and kinetin, the whitish yellow calli of rice and the white calli segregated from the hybrids did not usually turn green. Nevertheless the segregated white calli occasionally produced green parts in a mosaic pattern during long term cultures. On the other hand, soybean calli, and yellow and green calli segregated from the hybrids became green or remained green. Analysis of Fraction I protein showed that the segregated green calli have soybean chloroplasts, while the white calli have both of rice and soybean chloroplasts. Therefore, it may be considered that the segregated green calli have mainly soybean nuclei and soybean chloroplasts, while the white calli have soybean nuclei, and rice and soybean chloroplasts in a mosaic pattern.
Males of Drosophila melanogaster bearing various X chromosome segmental aneuploidies were tested for sensitivity/resistance to the male killing action of the Sex Ratio Organism (SRO). It was found that there is no region on the X chromosome which makes, when duplicated, males resistant to the SRO. A region which makes hetero-deficient females sensitive to the SRO also was not found. Searches for a gene (s) that can give males resistance to the SRO action were made using the X chromosomes continuously mutagenized for seven successive generations, the second and third chromosomes obtained from a natural population (100 lines), and the cytoplasm of 100 isofemale lines and twenty-two mass lines from various natural populations. No such genes were recovered. A possible reason for the failure of recovering such a gene is discussed.
With the highly polymorphic Est-α locus of Drosophila virilis, enquiry was made into its genetic structure. Electrophoresed were 1.47×106 progeny raised from heterozygous females comprising thirty-two varieties of genotypes. In this study, 65 mutants were found to occur. Fifty-nine of these covered the full range of variation commonly observed in natural populations in Japan, whereas the remaining six were rather novel and in possession of new alleles not formerly recorded. Such a novelty in the behavior of the relevant genes may be understood as to indicate the occurrence of intragenic recombination. It has been suggested that the gene in question has some specific recombination sites, the regions of some intervening inert parts of genes (introns) or, if any, coding regions (exons) having a possible, specific base sequence where recombination is unaccompanied with base correction of the unpaired bases. Granting that intragenic recombination chiefly occurs within the region of introns, the most probable model is discussed to satisfactorily explain these results.
We have examined the chromosomes of Hynobius takedai. The karyotype (2n=56) is characterized by the absence of a medium-sized telocentric pair and, in this respect, H. takedai resembles the forms from northeastern Japan (H. lichenatus from Iwate Pref., H. nigrescens, and northern populations of H. tokyoensis) but differs from southwestern forms (H. abei, H. nebulosus and southern population of H. tokyoensis). H. takedai is also distinct from all previously studied species in the presence of 6 meta- or submetacentric and 9 telocentric microchromosome pairs. Karyotypic relationships among forms of the lichenatus and nebulosus groups are discussed.
Certain chromosomes of Aegilops sharonensis (2n=14, S1S1) and Ae. longissima (2n=14, S1S1), wild species related to wheat (Triticum), have been known to be retained selectively in durum and common wheats by their gametocidal action that is exerted exclusively on gametes lacking the Aegilops chromosome. Three of such gametocidal chromosomes from Ae. sharonensis and two from Ae. longissima, collected from different sources, were studied on their cytological features, homoeology, and interrelation. One of the Ae. sharonensis and one of the Ae. longissima chromosomes had similar N-banding patterns, which resembled that of wheat chromosome 2B, and were homoeologous to the group 2 wheat chromosomes. The other gametocidal chromosomes, which had been proved or speculated to be in homoelogous group 4, had N-banding patterns relatively similar to wheat chromosome 4A; the two Ae. sharonensis chromosomes could not be distinguished by the N-banding. In double monosomic additions of common wheat with the gametocidal chromosomes of the same homoeology, gametes carrying either or both of the alien chromosome became fertile, and in those with non-homoeologous gametocidal chromosomes, only the gametes carrying the alien chromosome of homoeologous group 4 were functional. Thus, it became clear that there were two types of gametocidal chromosomes each in Ae. sharonensis and Ae. longissima.
With the aim of elucidating the origin and the route of transmission of enterovirus 70 (EV70), we constructed a phylogenetic tree using the base sequence variation deduced from the oligonucleotide map of the virus genomes of 16 strains isolated between 1971 and 1981 in different parts of the world. For this purpose, we estimated the evolutionary rate of EV70, taking advantage of the fact that the dates of isolation of the strains are precisely known. Furthermore, the divergence times between viruses were estimated using base sequence variation, the evolutionary rate and the sampling times of the strains. The phylogenetic tree and the divergence times between the branches were estimated simultaneously by UPGMA. The phylogenetic tree constructed is in good agreement with epidemiological evidences of EV70, indicating the valid estimation of the tree. It is also shown that the evolutionary rate of EV70 is extremely rapid and constant.
The karyotypes of two closely related species of mustelids, the Japanese ermine (Mustela erminea nippon) and the least weasel (M, nivalis namiyei), were compared by means of the G-and C-banding methods. A high degree of G-band homology was observed between the chromosome arms of the two species, except for the faintly stained (G-negative) regions in the short arms of the pairs Nos. 1 to 5 of the least weasel (W1 to W5). These G-negative regions were found to correspond to the deeply stained C-heterochromatin, as reported previously (Obara 1982, 1984). The present results confirmed the previous notion that the karyotype of the least weasel has derived from the ancestral one similar to that found in the ermine mainly through duplication of C-heterochromatin, Robertsonian fusion and tandem translocation.