Thirty nine strains of 24 Vicia species representing the main sections of the genus, have been analyzed for their isozyme patterns by disc electrophoresis of leaf and cotyledon extracts. The enzyme systems studied were amylase, esterase, glutamate oxaloacetic transaminase (GOT), indo-phenol oxidase (IPO). Comparing the zymograms obtained, one can arrive at the following conclusions: There are many bands common to species, series of sections and, in contrast, there are some bands differentiating between certain taxonomic categories. Such characterizing bands and patterns do not feature any clear general phylogenetic trend or systematic correlation. The enzymatic similarity does not necessarily correspond with the taxonomic relationships. GOT show lesser polymorphism, compared with amylase and esterase. The latter systems might be helpful in identifying species or strains. Species which are polymorphic in many other characters reveal also enzymatic polymorphism. Other possible correlations are briefly discussed, with a special note on the evolutionary implications of such a study in Vicia.
A total of 20 species in the Drosophila montium subgroup has been cytologically examined. All species show similar basic pattern of metaphase karyotype. The most extensive variations in metaphase chromosome configurations have been observed in the Y and 4th (dot) chromosomes while the X chromosome is slightly variable. Interspecific karyotype differentiation is largely due to the acquisition of different amounts of heterochromatin.
Hybridization tests among the available strains of three sibling species of the D. kikkawai complex were performed. All cases of intraspecific crosses were successful. All interspecific crosses involving D. bocki were completely unsuccessful; however, interspecific crosses between D. kikkawai and D. leontia in mass mating involving as many as 20-30 pairs in most cases were successful, producing variable numbers of F1 offspring. Fertility tests of F1 progeny revealed that the F1 males were completely sterile while the F1 females were fertile when backcrossed to the males of parental types, yielding considerable numbers of offspring. The data suggest that D. bocki is the most genetically isolated, although all are morphologically indistinguishable. D. bocki and D. leontia are found existing sympatrically. Although D. kikkawai and D. leontia are occurring sympatrically, the former species has so far not been found to coexist with D. bocki. D. kikkawai and D. leontia differ in gene sequences in chromosome 2L, 2R and 3L and most extensively in the X chromosome. Nevertheless, chromosomes 3R and 4 do not show any differences in gene order among the species. D. kikkawai is polymorphic for a sequence (3LB) which appears to be fixed in D. leontia, indicating that they have diverged recently from a common ancestor.
Cytogenetical studies on interspecific F1 hybrids between Brassicacampestris and B. oleracea were carried out. Hybrid plants were produced by the culture in vitro of excised ovaries. Three types of F1 hybrids were obtained in the cross between diploid B. campestris, and diploid and autotetraploid B. oleracea. The first type plants had 19 chromosomes in root tip cells. The second type plants had 38 chromosomes which were presumably raised by spontaneous chromosome doubling during embryo development. The third type plants had 28 chromosomes which were produced by the cross, diploid B. campestris× autotetraploid B. oleracea. Mode of the chromosome configurations at the first meiotic division of the first type hybrids was 9II+1I (44.7%). Frequency of tri-, tetra- and pentavalents was 38.6%, 10.3% and 1.3%, respectively. Tetra- and pentavalents were observed for the first time in the present experiment. Chromosome configurations at meiosis of the second type hybrids were mostly 19II (86.7% and 80.0% in two plants). The mode of chromosome configurations at meiosis of the third type hybrids was 9II+10I (40.9%). Frequency of tri- and tetravalents was 38.1% and 1.2%, respectively. Tetravalents were observed for the first time in the present experiment.
Fibroin large subunit of a parent strain of silkworm was shown to give a single band on SDS-polyacrylamide gel electrophoresis. From the mobility of the band, fibroin large subunits from various parent strains of silkworm were classified into three groups, that is, fast (F), moderate (M), and slow (S) moving groups. On the other hand, the large subunit from the hybridized silkworm obtained by the cross between two parent strains of silkworm exhibited two bands having slightly different mobilities, which were the same to those of its parent silkworms, respectively. By carrying out F1 hybridization and backcrossing of the F1 with each of their parents, it was concluded that the alleles which control the fibroin phenotype are codominant each other.
Glucose 6-phosphate dehydrogenase was purified to a homogeneous state from Drosophila melanogaster imagoes made homozygous for the X chromosome of a mutant male which showed two bands of enzyme activity on polyacrylamide gels as well as from Oregon R flies similarly made homozygous which showed only one major band, and their properties were compared with respect to molecular weight, pH optimum, specific activity, Km values and sensitivity to p-chloromercuribenzoate, MgCl2, dehydroepiandrosterone, heat and anti-Oregon R glucose 6-phosphate dehydrogenase antibody. The fast and slow bands of mutant enzyme had molecular weights of 115, 000 and 283, 000, respectively, while the wild-type enzyme had a molecular weight of 120, 000. Treatment with sodium dodecyl sulfate cleaved the three enzymes into a subunit having a molecular weight of 69, 000. This suggests that the slow and fast bands of the mutant enzyme represent tetramers and dimers of single polypeptides, respectively. Since the mobility of the fast mutant enzyme was the same as that of wild-type enzyme, it is inferred that the mutation resulted in a change of the quaternary structure of enzyme, without affecting its net charge in this particular instance. The mutant enzyme was more heat-stable than the wild-type enzyme, but they did not differ in other respects. 6-Phosphogluconate dehydrogenase was also purified to a homogeneous state from the wild and mutant flies. No difference was found between the two strains of flies with respect to several parameters used.
When the seeds of 27 soybean varieties were exposed to gamma-rays, distinct varietal differences in the frequency of chromosome aberrations were found at the first root tip mitosis. The varieties tested could be divided into resistant and sensitive groups. F2 seeds from crosses between resistant and sensitive varieties were irradiated and from the frequency distribution of chromosome aberrations it was concluded that the intervarietal differences were controlled mainly by a single recessive gene rs1 which had been detected by Takaki and Yamashita to control the degree of seedling growth inhibition in both seed and growing plant irradiations.
Intra-specific variations of the courtship song (inter-pulse interval: ipi) of Drosophila melanogaster and D. simulans males were investigated. The variation among strains was small in D. melanogaster (31.3-34.8 msec), whereas it was much larger in D. simulans (42.8-56.8msec). The average ipi was 32.8msec for D. melanogaster and 49.1msec for D. simulans, and the distributions between the two sibling species were non-overlapping. However, the ipi itself plays less important role for the success of mating.
Mutagenic effect of AF-2 in higher plants was examined with heterozygotic maize and soybean. Mutagenicities of AF-2 were observed with higher concentrations than 0.0001μg/ml and 0.0005μg/ml in soybean and maize, respectively.