Idengaku zasshi最新文献

In order to investigate the intraspecific variation of Prunus yedoensis (Someiyoshino) and interspecific relationship among P. yedoensis, P. lannesiana (Oshimazakura) and P. pendula (Edohigan), DNA fingerprinting study was conducted by using two different kinds of probes, M13 repeat sequence and (GACA)4 synthetic oligonucleotide. In this study, 68 plants of P. yedoensis grown in 46 prefectures in Japan were investigated. All the P. yedoensis individuals investigated showed the completely same banding pattern, indicating their clonal origin from a single plant. On the other hand, each of P. lannesiana and P. pendula individuals investigated showed a unique banding pattern, suggesting a considerable amount of genetic variation in these two species. About 90% of bands in DNA fingerprints of P. yedoensis were detected in either P. lannesiana or P. pendula. This result supports the hypothesis that P. yedoensis is an interspecific hybrid between P. lannesiana and P. pendula. From those results, it is concluded that P. yedoensis was produced only once through hybridization between P. lannesiana and P. pendula, and that this particular hybrid plant has been spread vegetatively all over Japan.

Some basic concepts of chiasma (including chiasma distribution, chiasma frequency, interstitial and terminal chiasmata, and chiasma interference) are reexamined theoretically in the light of gene shuffling, and a new method for chiasma analysis termed the chiasma graph is proposed. Chiasma graphs are developed for three mammals with greatly different chromosome numbers: Chinese hamster (with n = 11), mice (n = 20), and a dog (n = 39). The results demonstrate that interstitial chiasmata can contribute both to gene shuffling and to the binding of bivalents, but that so-called terminal chiasmata are in fact mostly achiasmatic terminal associations, the main function of which is to bind bivalents. For this reason, terminal chiasmata should be excluded when chiasma frequency is estimated. It is also demonstrated that interstitial chiasmata distribute on bivalents randomly and uniformly, except at the centromere and telomere. Interference distance fluctuates almost randomly above a minimum value equivalent to about 1.8% of total bivalent length at diakinesis. These results indicate that chiasma formation in mammals is principally a random event. The demonstrated minimum interference distance seems consistent with the polymerization model for chiasma formation. Some cytological aspects of crossing-over are discussed with reference to the minimum interaction theory for eukaryotic chromosome evolution.

Mating of Drosophila melanogaster is a stereotypically patterned behavior consisting of a fixed sequence of actions that is primarily under genetic control. Although courtship can be easily monitored and quantified, little is known about its neural basis. To obtain a better understanding of cellular and molecular mechanisms underlying courtship, we have isolated mutants that disrupt specific aspects of mating behavior. The croaker mutant was isolated from approximately 1,000 lines harboring single P-element insertions by screening for aberrant courtship song: croaker males often generate polycyclic pulse song while most of the song pulses are monocyclic in the wild-type. The mutant is also defective in flight. Intracellular recordings of excitatory junction potentials from larval body wall muscles and Ca++ action potentials from adult indirect flight muscles demonstrated that neuromuscular transmission and Ca++ electrogenesis in the muscle fibers are not impaired by the croaker mutation. To define the croaker gene molecularly, genomic DNA surrounding the P-element insertion site was cloned by plasmid rescue and subsequent screening of a cosmid library. Northern blotting with the genomic DNA probes detected three transcripts in the wild-type, which were not expressed in the croaker mutant.

High-voltage shock within a very short duration under the proper conditions causes cells to incorporate exogenous macromolecules. This technique, electroporation, has been widely used in recent years to transform many organisms. We determined optimum conditions for fission yeast transformation using this method. Of nineteen combinations of electric field strength and pulse time examined, 1.75 kV/0.2 cm, 4 msec pulse was found to provide approximately 4.0 x 10(5) transformants per micrograms of DNA. Other factors responsible for the transformation efficiency in fission yeast are also discussed.

LEC rats develop disorder of cooper metabolism and hepatitis similar to those of human Wilson's disease. We recently demonstrated that the gene responsible for hepatitis (hts) of LEC rats is homologous to Wilson's disease gene (WD). The present study showed a deletion of at least 90 base pair of WD cDNA in LEC rats, which corresponds to nucleotides 3981 to 4071 in human WD cDNA sequence. This deletion was linked with hepatic copper accumulation and hepatitis, and considered to be a primary mutation for hepatic disorder in the LEC rat. The WD gene was assigned to rat chromosome 16 at band q12.2-q12.4 by fluorescence in situ hybridization (FISH).

CA-repeat primed polymerase chain reaction (CAP-PCR), using degenerate primers which anneal at the ends of (CA)n sequences in eukaryotic genomes, was attempted to assess its potential to monitor the genomic polymorphisms in various animals. Three mammalian, three avian, one fish and one insect species were examined and all showed primer-specific DNA fingerprints by CAP-PCR. Polymorphic bands observed in a laboratory-bred vole family were segregated in Mendelian manner. The present CAP-PCR DNA fingerprinting therefore is a simple and useful method for examining genomic variations in most animals without prerequisite knowledge of DNA sequences.

We surveyed the geographical distribution of Hbb haplotypes of the house mouse, Mus musculus, in the former USSR and the northern part of China. Mice with the w1 haplotype were distributed from the coastal area of the Black Sea to the Maritime Province of Siberia in the former USSR and in the area north of the Yangtze River in China. Mice with the p haplotype were found in the areas surrounding those populated with the w1 haplotype mice. In the Maritime Province and the southern part of Siberia, the d haplotype was predominant. The correlation between the geographical variation of the Hbb haplotypes and the distribution of the Mus musculus subspecies in the eastern part of the Eurasian Continent, is discussed.

Intergeneric hybrids involving Oryza punctata (2n = 48, BBCC) with Leersia tisseranti (2n = 24), O. punctata with L. perrieri (2n = 24), O. latifolia (2n = 48, CCDD) with L. tisseranti and O. latifolia with L. perrieri were produced at frequencies varying from 0.11% to 0.23% of the pollinated spikelets. Plant morphologies of the hybrids strongly resembled the tetraploid Oryza species. Five hybrids obtained from the four cross-combinations had the expected chromosome number of 2n = 36 (trihaploid) in the somatic cells. The average meiotic chromosome pairings per cell were 0.23II + 35.58I + 0.14(1)/2I (dividing univalent) for O. punctata x L. tisseranti; 0.11II + 35.51I + 0.22(1)/2I for O. punctata x L. perrieri; 0.17II + 35.63I + 0.11(1)/2I for O. latifolia x L. tisseranti; and 0.25II + 35.49I + 0.15(1)/2I for O. latifolia x L. perrieri. From these results, it seems that most of the bivalents observed at MI with a low frequency had originated from the autosyndetic association of the chromosomes of O. punctata or O. latifolia. The results described above suggest that there is no genomic relationship between the parental species in each cross combination.