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The Role of Viral Infection in Inducing Variability in Virus-Free Progeny in Tomato

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Journal of Integrative Plant Biology 2009年第5期51卷 476-488页

作者： Liliana Marii Gheorghe Chiriac Institute of Genetics and Plant Physiology Academy of Sciences of Moldova

The effect of virus-host interactions on subsequent generations is poorly understood. The evaluation of the effects of viral infection on inheritance of quantitative traits in the progeny of infected plants and elucidation of a possible relationship between chiasma frequency in the infected plants and variability of traits in the progeny were investigated. The current study involved genotypes of four intraspecific hybrids of tomato （Solanum lycopersicum L.）, their parental forms and two additional cultivars. Used as infection were the tobacco mosaic virus （TMV） and potato virus X （PVX）. The consequences of the effect of viral infection were evaluated based on chromosome pairing in diakinesis and/or by examining quantitative and qualitative traits in the progeny of the infected tomato plants. Tomato plants infected with TMV ＋ PVX were found to differ in chiasma frequency per pollen mother cell or per bivalent. Deviations have been observed for genotypes of both F1 hybrids and cultivars. At the same time, differences in mean values of the traits under study have only been found for progeny populations （F2-F4） derived from virus-infected F1 hybrids, but not in the case of progeny of the infected cultivars. The rate of recombinants combining traits of both parents increased significantly （2.22-8.24 times） in progeny populations of hybrids infected with TMV＋PVX. The above suggests that the observed effects could be the result of modification of recombination frequencies that can be manifested in heterozygous hybrids and make small contributions to variability in cases of ＇homozygous＇ tomato genotypes （i.e. cultivars）.

关键词： chiasma recombination Solanum lycopersicum traits variability viral infection.

Toward a Multi-Layered Chiasme-Focused Topology: A Reading of Merleau-Ponty's Later Writings

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Frontiers of Philosophy in China 2020年第2期15卷 242-269页

作者： MA Lin School of Philosophy Renmin University of ChinaBeijing 100872China

This paper traces the genealogy of reversibility,chiasma,and chiasme in Merleau-Ponty's writings and offers a new characterisation of his later ontology in terms of a multi-layered chiasme-focused topology informed by subtle differences and interconnections among these *** need to grasp the significance of reversibility not only in terms of constant recoil and impossible overlap but also of its situatedness in the crisscrossing between Dasein and things,and between the inside/invisible and the outside/visible."chiasma" was initially introduced as a reference to the intersection of ***-Ponty deploys it to articulate macroscopic insights concerning the nature of philosophy and the interweaving connections between self,other,and the *** comparison,"reversibility" is primarily used to describe the microscopic bond between touching-touched and perceiving-perceived.I argue that,as Merleau-Ponty's ultimate choice of wording,"chiasme" incorporated the significance of both "reversibility" and "chiasma." A chiasme-focused topology that retains the significance of all three of the terms would serve to better convey the import of Merleau-Ponty's later ontology,which aims to dissolve and to re-configure our conceptions about being,body,self,and the other from within and from below.

关键词： Merleau-Ponty chiasma chiasme reversibility intertwining(entrelacs) ontology

Further evidence for the theory that crossover interference in Drosophila melanogasteris dependent on genetic rather than physical distance between adjacent crossover points

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Open Journal of Genetics 2013年第2期3卷 93-101页

作者： Petter Portin Laboratory of Genetics Department of Biology University of Turku Turku Finland

The effect of heat shock on certain meiotic parameters in Drosophila melanogaster was studied in the cv – v – f region of the X chromosome of females homozygous for the mus309 mutation, deficient in DNA double-strand break repair, or those of wild type. The heat shock in the wild females caused the frequencies of the single crossovers and double crossovers and all the map lengths to decrease while crossover interference remained unchanged. In the mus309 mutants all parameters, crossover interference included, remained unchanged despite the heat shock treatment. However, the mus309 mutation had a significant effect on all meiotic parameters both in the females not given the heat shock and in the heat shocked females with the exception that the recombination frequency of the v and f markers was the same in both genotypes in the females not given the heat shock. It seems that the heat shock treatment has an effect on crossing over which is independent on the mus309 gene and affecting the occurrence of crossing over itself. On the other hand, the mus309 gene has an effect on crossing over which is independent of the heat shock treatment and affects some precondition of crossing over. This precondition is probably the choice between two routes of the repair of double-strand DNA breaks known to be controlled by the mus309 gene. As explained in the discussion, the results are in accordance with the genetic models of interference in which interference depends on genetic distance between the crossover points, but in contradiction with physical models where interference is dependent on physical distance between the crossover points.

关键词： chiasma Chromosome Map Length Meiosis

Further evidence for the theory that crossover interference in Drosophila melanogasteris dependent on genetic rather than physical distance between adjacent crossover points

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Open Journal of Genetics 2012年第3期2卷 155-162页

作者： Petter Portin Laboratory of Genetics Department of Biology University of Turku Turku Finland

Effect of heat shock on certain meiotic parameters in Drosophila melanogaster was studied in the cv-v-f region of the X chromosome of females homozygous for mus309 mutation, deficient in DNA double-strand break repair, or being of wild type. The heat shock in the wild females caused that the frequencies of the single crossovers and all the map lengths decreased while the frequency of the double crossovers and crossover interference remained unchanged. In the mus309 mutants all parameters remained unchanged except that single crossovers in the cv-v interval were less frequent, and that crossover interference diminished. Thus, heat shock seems have two separate effects;one being independent on the mus309 gene and affecting the occurrence of crossing over itself, and the other being dependent on the mus309 gene and affecting some precondition of crossing over. This precondition is probably the choice between two routes of the repair of double-strand DNA breaks known to be controlled by the mus309 gene. The results are in accordance with the genetic models of interference in which interference depends on genetic distance between the crossover points, but in contradiction with physical models where interference is dependent on physical distance between the crossover points.

关键词： chiasma Chromosome Map Length Meiosis

Effect of temperature on crossing over in the mus309 mutant, deficient in DNA double-strand break repair, of Drosophila melanogastersuggests a mechanism for crossover interference

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Open Journal of Genetics 2011年第3期1卷 38-47页

作者： Petter Portin Laboratory of Genetics Department of Biology University of Turku

Crossing-over frequencies, crossover interference, recombination frequencies and map distances were compared in the cv-v-f region of the X chromosome of Drosophila melanogaster in females bearing either wild type 3rd chromosomes (control) or having the DNA double-strand break repair deficient mus309D2/mus309D3 mutant constitution in the 3rd chromosomes (experiment), and raised in three different temperatures viz. 18。C, 25。C and 29。C. In addition, the fecundity of the females was also measured. In the control crosses none of the mean values of the parameters measured was dependent on the temperature, whereas in the experimental crosses all the parameters, except for the frequency of true single crossovers in the cv-v interval, the recombination frequency of the v and f markers, and the coefficient of coincidence, changed due to the effect of temperature. When comparing the genotypes studied, a significant difference between them was observed in all the parameters measured, apart from the frequency of the true single cross-overs in the cv-v interval. These results support the counting number model of the mechanism of interference based on the genetic distance, but are in contradiction with the models based on physical distance.

关键词： chiasma Chromosome Map length Meiosis