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67 巻, 4 号
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REVIEW
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Ko SHIMAMOTO1992 年 67 巻 4 号 p. 273-290
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーProtoplasts are versatile tools for genetic manipulation of plant cells. The ability of genetically modified protoplasts to differentiate into complete plants offers novel experimental systems in various fields of plant biology. Among major graminaceous species (cereals), rice is the only one in which wellestablished protoplast system is available. By using protoplasts as an experimental system, we have obtained and characterized various mutations some of which are being used for breeding new varieties. Somatic hybrids of rice and wild Oryza species were generated and cytoplasmic male sterility of an indica rice was transferred to japonica rice by cell fusion. Most importantly, an efficient method of genetic transformation was developed which opened up a new area of research in rice. Variously modified genes can be now introduced and expressed in transgenic rice and various mutations were generated by introduced transposable elements, Ac/Ds. Initial attempts on genetic engineering of rice has also begun. These suggest that rice can be a model cereal in which genetic as well as reverse-genetic approaches can be taken for various basic and applied studies.
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ARTICLES
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Shin TOGASHI, Ryu UEDA, Manabu TAKAHISA, Misa MIKUNI, Kanae KONDO, Tad ...1992 年 67 巻 4 号 p. 291-297
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーDrosophila yakuba, a member of melanogaster subgroup being free of P element, acquired resistance to an antibiotic neomycin by the transformation utilizing P element. In this species, the transformation frequency was comparable to that of D. melanogaster. Further, the occurrence of 8 base pairs duplication upon the insertion of the element was confirmed. These facts suggest that the P element could be inserted into the genome in the same manner, even in D. yakuba. Any consensus for preferential insertion could not be found on the nucleotide sequence as in D. melanogaster. However, it is noticeable that a series of the short palindromic stretches was common around the insertion sites in both species. It suggests that a structural feature of DNA plays a role as a landmark for P element insertion.
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Yoshihiko TSUMURA, Kihachiro OHBA1992 年 67 巻 4 号 p. 299-308
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーGenetic variation and geographical diversity of five natural populations of Cryptomeria japonica in western Japan were investigated for nine allozyme loci. Genetic variation of this species was somewhat lower than the other coniferous species. Most of the variation was attributable within population (98.16%) rather than between populations (1.84%). The GST value was only .0156 and genetic distances between populations were also small, averaging .0062. These results indicate that natural Cryptomeria forests in western Japan have maintained relatively middle genetic variation, comparing with the other conifer species, but these populations were not genetically differentiated each other.
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Akira KANAZAWA, Wataru SAKAMOTO, Masahiro NAKAGAHRA, Koh-ichi KADOWAKI ...1992 年 67 巻 4 号 p. 309-319
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーDistribution of four kinds of mitochondrial plasmid-like DNAs, Bl, B2, B3 and B4 was investigated by Southern analysis using 85 accessions of cultivated rice (Oryza sativa L.). The frequencies of these molecules found in cultivars differed from each other. The mitochondrial genome were categorized into nine types according to their presence or absence. They were found mostly in ecospecies Indica, a few in Javanica, and not found in Japonica. The result indicated the polymorphic and monomorphic patterns of the mitochondrial genomic organization within Indica and Japonica cultivars, respectively. Quantitative variation was found among four kinds of mitochondiral plasmid-like DNAs, suggesting that these molecules were unequally distributed or replicated during the process of mitochondrial division.
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Soon Tae KWON, Kiyoharu OONO1992 年 67 巻 4 号 p. 321-334
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーRice (Oryza sativa L. var. Nipponbare) seeds, seedlings and suspension callus were subjected to powerful gravity stress ranging from 150,000 g to 450,000 g. Suspension callus and dehulled seeds showed 32% and 15% survival rates, respectively, after gravity treatment at 450,000 g for 6 hours, whereas all the seedlings died. Seedlings became increasingly sensitive to gravity stress as the growth stage advanced. The suspension callus, which gradually recovered viability during subculture under normal conditions, were used to analyze the protein patterns and in vitro translation products of poly(A)+RNA. Some 3 to 4 newly synthesized proteins and in vitro translation products were identified using two-dimensional electrophoresis, while 5 to 24 proteins disappeared during the treatment, demonstrating that rice suspension callus respond to gravity stress by producing new mRNA and their proteins. In addition, some newly synthesized proteins which resulted from gravity effects were maintained in the surviving cells during continuous growth on solid medium. There was an increase in the survival rate of suspension callus from the strong gravity stress as a result of treatment with 200 g/l sucrose, 10-5 M ABA or 5 g/l NaCl. This suggests that in addition to changes in protein patterns, another protection mechanism associated with some physiological changes is involved in the survival of rice suspension callus after gravity stress.
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Soon Tae KWON, Shoshi KIKUCHI, Kiyoharu OONO1992 年 67 巻 4 号 p. 335-348
発行日: 1992年
公開日: 2005/10/18
ジャーナル フリーRice (Oryza sativa L. var. Nipponbare) suspension callus was exposed to gravity stress at 450,000 g for 2 hours, after which poly(A)+RNA was isolated and a cDNA library was constructed. Three different gravity specific cDNAs, namely, GSC 128, GSC 233 and GSC 381 of 0.67, 0.60 and 0.68 kilobase pairs and transcripts of 1.9, 1.6 and 2.0 kb, respectively, were isolated by differential screening and Northern hybridization. The maximum level of transcript was achieved after 4 hours of exposure to gravity at 450,000 g for GSC 128, 2 hours for GSC 233 and 8 hours for GSC 381 followed by a gradual decrease to undetectable levels with the extension of gravitation time. Callus (GSC 128), shoot and callus (GSC 381) and root and callus (GSC 233) specific expression of transcripts was identified. Although the protection of callus by treatment with ABA, kinetin and sucrose extended the period of expression of mRNA in suspension callus after gravity exposure, the expression of gravity-inducible mRNA was exclusively regulated by the degree of callus viability or survival after the stress. In addition, we demonstrated that the level of GSC 381 transcript was markedly increased by exposing the cell to periodical gravity stress, suggesting that this mRNA is expressed and translated into special proteins which are closely related to the survival of the cell against gravity stress. The sequence of GSC 233 and GSC 381, consisting of 417 and 531 base pairs of the longest open reading frames, encode polypeptides with calculated molecular weights of 15.29 and 19.47 kDa, respectively. A sequence homology search against a data bank revealed that GSC 233 and GSC 381 differed from other stress inducible genes in terms of the coding sequence and expression characteristics.
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