Optional elements in the chloroplast DNAs of Chlamydomonas eugametos and C. moewusii: unidirectional gene conversion and co-conversion of adjacent markers in high-viability crossses

1996 ◽  
Vol 30 (4) ◽  
pp. 356-365 ◽  
Author(s):  
Johanne Bussières ◽  
Claude Lemieux ◽  
Robert W. Lee ◽  
M. Turmel
Keyword(s):  
Gene Conversion ◽  
Chlamydomonas Eugametos ◽  
High Viability ◽  
Co Conversion ◽  
Chloroplast Dnas

scholarly journals Characterization of Non-selected Intermolecular Gene Conversion in the Polyploid Haloarchaeon Haloferax volcanii

2021 ◽  
Vol 12 ◽  
Author(s):  
Daniel Wasser ◽  
Andreas Borst ◽  
Mathias Hammelmann ◽  
Katharina Ludt ◽  
Jörg Soppa
Keyword(s):  
Gene Conversion ◽  
Concerted Evolution ◽  
Antigenic Variation ◽  
Methanogenic Archaea ◽  
Carotenoid Biosynthesis ◽  
Haloferax Volcanii ◽  
Conversion Frequency ◽  
Co Conversion ◽  
Phenotype Analysis ◽  
Reciprocal Transfer

Gene conversion is defined as the non-reciprocal transfer of genetic information from one site to a homologous, but not identical site of the genome. In prokaryotes, gene conversion can increase the variance of sequences, like in antigenic variation, but can also lead to a homogenization of sequences, like in the concerted evolution of multigene families. In contrast to these intramolecular mechanisms, the intermolecular gene conversion in polyploid prokaryotes, which leads to the equalization of the multiple genome copies, has hardly been studied. We have previously shown the intermolecular gene conversion in halophilic and methanogenic archaea is so efficient that it can be studied without selecting for conversion events. Here, we have established an approach to characterize unselected intermolecular gene conversion in Haloferax volcanii making use of two genes that encode enzymes involved in carotenoid biosynthesis. Heterozygous strains were generated by protoplast fusion, and gene conversion was quantified by phenotype analysis or/and PCR. It was verified that unselected gene conversion is extremely efficient and it was shown that gene conversion tracts are much longer than in antigenic variation or concerted evolution in bacteria. Two sites were nearly always co-converted when they were 600 bp apart, and more than 30% co-conversion even occurred when two sites were 5 kbp apart. The gene conversion frequency was independent from the extent of genome differences, and even a one nucleotide difference triggered conversion.

scholarly journals Meiotic gene conversion tract length distribution within the rosy locus of Drosophila melanogaster.

Genetics ◽  
1994 ◽  
Vol 137 (4) ◽  
pp. 1019-1026 ◽  
Author(s):  
A J Hilliker ◽  
G Harauz ◽  
A G Reaume ◽  
M Gray ◽  
S H Clark ◽  
...  
Keyword(s):  
Gene Conversion ◽  
Length Distribution ◽  
P Element ◽  
Base Pairs ◽  
Tract Length ◽  
Meiotic Gene ◽  
Co Conversion ◽  
Optimal Value ◽  
Gene Conversion Tract ◽  
Conversion Tract

Abstract Employing extensive co-conversion data for selected and unselected sites of known molecular location in the rosy locus of Drosophila. we determine the parameters of meiotic gene conversion tract length distribution. The tract length distribution for gene conversion events can be approximated by the equation P(L > or = n) = phi n where P is the probability that tract length (L) is greater than or equal to a specified number of nucleotides (n). From the co-conversion data, a maximum likelihood estimate with standard error for phi is 0.99717 +/- 0.00026, corresponding to a mean conversion tract length of 352 base pairs. (Thus, gene conversion tract lengths are sufficiently small to allow for extensive shuffling of DNA sequence polymorphisms within a gene). For selected site conversions there is a bias towards recovery of longer tracts. The distribution of conversion tract lengths associated with selected sites can be approximated by the equation P(L > or = n/ selected) = phi n(1 - n + n/phi), where P is now the probability that a selected site tract length (L) is greater than or equal to a specified number of nucleotides (n). For the optimal value of phi determined from the co-conversion analysis, the mean conversion tract length for selected sites is 706 base pairs. We discuss, in the light of this and other studies, the relationship between meiotic gene conversion and P element excision induced gap repair and determine that they are distinct processes defined by different parameters and, possibly, mechanisms.

Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution

2020 ◽  
Vol 56 (27) ◽  
pp. 3851-3854 ◽  
Author(s):  
Xiaomin Chai ◽  
Hai-Hua Huang ◽  
Huiping Liu ◽  
Zhuofeng Ke ◽  
Wen-Wen Yong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Performance ◽  
Aqueous Media ◽  
Highly Efficient ◽  
Co Conversion

A Co-based complex displayed the highest photocatalytic performance for CO2 to CO conversion in aqueous media.

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