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Volume 66 (1991)
- Issue 6 Pages 669-
- Issue 5 Pages 535-
- Issue 4 Pages 367-
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Volume 66, Issue 4
Displaying 1-13 of 13 articles from this issue
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REVIEW
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Motoo KIMURA1991 Volume 66 Issue 4 Pages 367-386
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSIn sharp contrast to the Darwinian theory of evolution by natural selection, the neutral theory claims that the overwhelming majority of evolutionary changes at the molecular level are caused by random fixation (due to random sampling drift in finite populations) of selectively neutral (i.e., selectively equivalent) mutants under continued inputs of mutations. The theory also asserts that most of the genetic variability within species at the molecular level (such as protein and DNA polymorphism) are selectively neutral or very nearly neutral and that they are maintained in the species by the balance between mutational input and random extinction. The neutral theory is based on simple assumptions, enabling us to develop mathematical theories based on population genetics to treat molecular evolution and variation in quantitative terms. The theory can be tested against actual observations. Neo-Darwinians continue to criticize the neutral theory, but evidence for it has accumulated over the last two decades. The recent outpouring of DNA sequence data has greatly strengthened the theory. In this paper, I review some recent observations that strongly support the neutral theory. They include such topics as pseudoglobin genes of the mouse, αA-crystallin genes of the blind mole rat, genes of influenza A virus and nuclear vs. mitochondrial genes of fruit flies. I also discuss such topics as the evolution of deviant coding systems in Mycoplasma, the origin of life and the unified understanding of molecular and phenotypic evolution. I conclude that since the origin of life on Earth, neutral evolutionary changes have predominated over Darwinian evolutionary changes, at least in number.
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ARTICLES
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Hiroshi MATSUBAYASHI, Yoshiko N. TOBARI, Samuel H. HORI1991 Volume 66 Issue 4 Pages 387-397
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSThe Om(2D)63 mutants were mutagenized by γ-ray irradiation and DEB feeding. A total of nine revertants were recovered and characterized; eight revertants were homozygous-lethal expressing no appreciable abnormality in cuticular pattern and central nervous system, and all failed to complement the lethality with each other. Two of the eight expressed embryonic lethality and were associated with cytologically detectable deletions including the putative Om(2D) locus, while four were associated with rearrangements in a region distal to the insertion sites of the tom elements. No rearrangement was detected in the remaining two by Southern blot analysis. One of the nine revertants was homozygous-viable with wild-type eyes and was associated with a reciprocal translocation with the break points at 48B in 2R (Om(2D) locus) and 96A in 3R. Based on these data, it is concluded that interaction between the region comprised of a single complementation group of the recessive lethal and the inserted tom elements seems to be responsible for the Om(2D) mutant phenotype. In addition, two induced dominant enhancers specific to Om(2D)63 were identified; both mapped on chromosome 2.
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Masayo KUBOTA, Yukiko YAMAZAKI, Akira ISHIHAMA1991 Volume 66 Issue 4 Pages 399-409
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSFive hundred fifty DNA fragments 100-500 base pairs in length were cloned from total chromosomal DNA of Escherichia coli, each capable of promoting the synthesis of β-lactamase when inserted upstream of the ampC structural gene without its own promoter in a promoter-probe plasmid. All clones in this library of putative promoters were classified based on the level of resistance to ampicillin, which ranged from 10 to more than 1,500 μg/ml. Most of the higher levels of drug resistance (more than 1,000 μg/ml) were due not only to an increase in gene expression but also to an increase in plasmid copy number. The DNA fragments which produced the highest level of drug resistance all mapped at 5.7 min on the E. coli chromosome and shared the same nucleotide sequence. In these fragments, a strong promoter was found, which carries an up stream AT-rich sequence in addition to -35 and -10 signals of the promoter consensus.
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Sumiko NARISE, Takashi NARISE1991 Volume 66 Issue 4 Pages 411-420
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSTwo chemical substances isolated from adult flies of Drosophila melanogaster differently affected the emigration activity of genetically different strains. These substances were identified as palmitic acid and oleic acid, respectively. Chemical and biological comparisons of the natural and authentic compounds showed them to be identical. The behavior response was dependent on the concentration of these fatty acids.
The two chemical substances are excreted by adult flies, both male and female, but the emigration activity of one strain was affected by only palmitic acid and that of the other strain, by only oleic acid.
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Hironori KATAYAMA, Tetsuo SASAKUMA, Yasunari OGIHARA1991 Volume 66 Issue 4 Pages 421-431
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSTo compare the gene order of chloroplast genome among monocotyledonous plants, we constructed a physical map of chloroplast DNA (cpDNA) of onion (Allium cepa L. cv. Shounan red, 2n=16) with four restriction endonucleases, PstI, SalI, XhoI, and SmaI. The cpDNA of Allium cepa was found to be a circular molecule with a total size of ca. 155 kb and containing two inverted repeats of 26 kb each that disrupt the rest of the molecule into small (ca. 16 kb) and large (ca. 86 kb) single copy regions. The endonuclease recognition sites of the physical map were confirmed by Southern hybridizations of total onion cpDNA with homologous and heterologous probes. 16 genes were localized on the physical map of the onion cpDNA. Genome structure of onion cpDNA was similar in terms of genome size and gene order of cpDNA to that of tobacco cpDNA, differing from the cpDNA structure of gramineous plants.
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Changshun SHAO, Nobuo TAKAGI1991 Volume 66 Issue 4 Pages 433-447
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSKaryotypes and X chromosome inactivation were studied in embryos obtained from female mice carrying T(X ;4)37H translocation on day 6 to 8 of gestation by a BrdU-acridine orange method. A total of 18 different karyotypes were found in 477 embryos examined: 90.0% embryos were products expected from 2:2 alternate or adjacent 1 disjunction. 3:1 and adjacent 2 disjunctions accounted for approximately 8.0% and 0.7% conceptuses, respectively. In the embryo proper of balanced T37H/ + conceptuses, inactivation was random with respect to the normal X and the larger translocation X (4X) chromosome. In all the cells with the 4X inactive, the late replication apparently did not spread to the attached autosomal portion, although black/brown coat variegation implies spreading of inactivation into the autosomal region. The X chromosome segment deprived of the inactivation center remained active in all the cells examined and it exerted deleterious effects on embryonic or fetal development. Observation in embryos having two maternally derived X chromosomes showed that they were indeed resistant to inactivation in early extraembryonic cell lineages, and two copies of active X chromosomes in the trophectoderm fatally affected embryonic development due to inability to form the extraembryonic ectoderm and ectoplacental cone from the polar trophectoderm. In unbalanced X aneuploids the X chromosomes with the deletion were preferentially inactivated due to strong selection against nullisomy X.
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Nobumichi INOMATA1991 Volume 66 Issue 4 Pages 449-460
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSCrossability was examined in the F2, B1 and hybrid plants, and the somatic chromosomes of their progenies were investigated. The F2 and B1 plants were obtained in the self- and open pollinations, and in the F1 hybrids backcrossed to both parents, respectively. The hybrid plants were obtained in the cross between F1 hybrids and diploid Brassica oleracea, and between F1 hybrids and B. napus. All F1 hybrids were produced by ovary culture in vitro in the cross between B. campestris and B. oleracea, and between B. campestris and autotetraploid B. oleracea. The plants examined were classified into three types. The first type had 29 chromosomes in root tip cells, and the second had 38 chromosomes. The third type of plants was the plants having chromosomes other than 29 or 38 chromosomes. Many different types of aneuploids were obtained in open pollination of the F2, B1 and hybrid plants, in the progenies of the F2, B1 and hybrid plants crossed to B. campestris, and B. napus. It was suggested that the different types of normal egg cell with one by one or little by little chromosome addition might be produced, and that some specific chromosome or chromosome group might increase or decrease the crossability in aneuploid production. It might be considered that there were genes related to fertility. It might be possible that the genes of B. campestris and B. oleracea could exchange reciprocally. Further selection had to be done for the production of a new type crop of B. napus which had been reported in a previous paper.
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Tetsuo ITOH, Sohei KONDO1991 Volume 66 Issue 4 Pages 461-469
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSThe variety T219 of Glycine max (soybean) has a wild-type chlorophyll development gene Y11 and its allele y 11. Seeds from autogamous T219 plants produce dark green (Y11Y11), light green (Y 11y11) and yellow (y11 y11) seedlings. Upon irradiation of dry seeds with X rays, the frequency of light-green mosaics on y11 y11 simple leaves was about twice as high as that of dark-green mosaics on Y11y11 simple leaves. For the explanation of the two-fold difference in mutability, we propose that both the light-green and the dark-green mosaics are caused by reversion of y11 to Y11, as the number of target gene y11 per cell in the y 11y11 tissue is twice that in the Y 11y11 tissue. Somatic reversion of the y11 gene was induced, in either y11 y11 or Y11y11 plants by 14 MeV neutrons and by fission neutrons at a rate about 20 times higher than that by X rays, suggesting that the reversions result from deletion mutations. To explain the occurrence of the reversion by deletions, we assume that the y11 gene is a complex gene made of a transposable element inserted at the Y 11 locus and that the reversion resulted from the deletion of the inserted transposon. The phenotype of the y11 gene shares many similarities with those of Xantha genes mapped at several loci in barley and tomato.
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Chiharu NAKAMURA, Kazue KASAI, Yoshiko KUBOTA, Chieko YAMAGAMI, Tohru ...1991 Volume 66 Issue 4 Pages 471-483
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSPhotosynthetic and respiratory characteristics were surveyed to evaluate cytoplasmic diversities in alloplasmic common wheats in which a nuclear genome of common wheat (Triticum aestivum L. cv. Chinese Spring (CS)) was combined with cytoplasms of Triticum and Aegilops species. The photosynthetic capacity (PSC) was measured based on the 13CO2-assimilation rate by infrared absorption spectrophotometry. A significant variation was found in PSC. The alloplasmic line with a cytoplasm of T. monococcum ssp. boeoticum which is unique in causing severe growth depression and male sterility when combined with CS nuclei showed more than 30% higher PSC than the euplasmic CS. A negative correlation was found between PSC and growth vigor of the euplasmic and alloplasmic lines. Respiratory electron flows and the cytochrome c oxidase (COX) activity were measured polarographically by an oxygen electrode. The cytochrome path activity, the COX activity and the alternative path capacity showed significant variations among the lines, irrespective of plant tissues studied. The alloplasmic line with T. monococcum cytoplasm showed chracteristic respiration in the alloplasmic line: It significantly increased the alternative path capacity and the COX activity in roots and leaves of 2-week-old plants. Moreover, the COX activity in the roots was negatively correlated with growth vigor among the lines. The results suggested that the aberrantly high COX activity might be related to the growth depression of the alloplasmic CS with T. monococcum cytoplasm.
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Kenji TANIGUCHI, Ryuso TANAKA1991 Volume 66 Issue 4 Pages 485-489
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSIn order to detect DNA replication in chromosomes of four plant species, Allium fistulosum (2n=16), Crepis capillaris (2n=6), Haplopappus gracilis (2n=4) and Chrysanthemum coronarium var. spatiosum (2n=18), an immunological technique using monoclonal anti-BrdU antibody was utilized. In this technique, HCl was used for denaturation and avidin-biotin complex for the immunological process. The replicating bands which appeared with this technique were of unusually high resolution.
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Tsuyoshi KAWASHIMA, Nobumoto MIYASHITA, Chenghuai WANG, Xinquao HE, Me ...1991 Volume 66 Issue 4 Pages 491-500
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSA new pattern was observed in the electrophoretic survey of the hemoglobin beta chain (Hbb) in Chinese wild mice, Mus musculus. The electrophoretic mobility of the major component of the new Hbb was identical to that of Hbbs on cellulose acetate plate, although it was almost identical to that of Hbbd or Hbbp on acrylamide gel. This suggests that the major component of Chinese Hbb has a unique primary structure. A minor component of the new Hbb was completely different from that of the other three Hbb haplotypes well known. These results indicate that the Hbb-b1 and Hbb-b2 of the new Hbb haplotype, assigned Hbbw1, are unique genes in their molecular structure. So far, Hbbw1 has been observed in northwestern China.
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Toshihiko IMAI, Sadao ICHIKAWA, Marie SANDA-KAMIGAWARA1991 Volume 66 Issue 4 Pages 501-511
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSVariation of spontaneous somatic pink mutation frequency was studied in the stamen hairs of Tradescantia KU 20 clone, a highly mutable blue/pink heterozygote. The spontaneous mutation frequency varied greatly from 4.03±1.21 to 120±7 and from 18.8±3.1 to 110±5 pink mutant events per 103 hairs when the plants were grown outdoors and in the greenhouse, respectively, being generally higher at lower temperature and also in the greenhouse than in outdoors. The spontaneous mutation frequency under controlled environmental conditions also varied from 3.06±0.37 to 40.8±3.1 pink mutant events per 103 hairs, showing a clearer negative correlation with temperature. It was found that the spontaneous mutation frequency under controlled environmental conditions increased when day/night temperature shifts were applied, especially with a 5°C shift than with 3°C shifts. The difference between the highest and the lowest mutation frequencies reached almost 40 times, and this clone was confirmed to be a temperature-sensitive mutable clone. A repair mechanism of DNA damages occurring spontaneously, which is more effective at higher temperature, thus presumably an enzymatic one, is very likely involved in the mutable nature of this clone.
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Sadao ICHIKAWA, Toshihiko IMAI, Atsushi NAKANO1991 Volume 66 Issue 4 Pages 513-525
Published: 1991
Released on J-STAGE: June 10, 2006
JOURNAL FREE ACCESSInduced somatic pink mutation frequencies in the stamen hairs of Tradescantia KU 20 clone, a blue/pink heterozygote highly mutable spontaneously at lower temperature, were studied after treating with relatively small doses of 60Co gamma rays (39 to 551 mGy or 3.9 to 55.1 rad), and were compared with those of two stable clones (non-mutable spontaneously), BNL 02 and KU 9, which are also blue/pink heterozygotes. It was found that the gamma-ray-induced mutation frequency in KU 20 clone was comparable (18.8 pink mutant events per 104 hair-cell divisions per Gy) to those in BNL 02 (12.2 and 21.2) and KU 9 (17.4) clones, when the spontaneous mutation frequencies of KU 20 clone were relatively low (at most about 5.7 and 2.3 times of BNL 02 and KU 9 clones, respectively). However, when the spontaneous mutation frequencies of KU 20 clone were much higher (up to about 65 and 27 times of BNL 02 and KU 9 clones, respectively), induced mutation frequency was significantly higher in KU 20 clone (58.8 pink mutant events per 104 hair-cell divisions per Gy) than in BNL 02 and KU 9 clones. The extent of increase in the gamma-ray-induced mutation frequency in the latter case was nevertheless very much less than the increase in the spontaneous mutation frequency, suggesting different mechanisms of initiation and repair of radiation-induced and spontaneous mutations.
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