A critical view to explanations for the maximal value of 50 % of genetic recombination

The maximal value of 50 % of genetic recombination (RF = recombination fraction) between two linked gene loci has been explained by two models: (i) the restriction of crossovers to only two of the four chromatids of a tetrad (tetrad model); (ii) the limit of the occurrence of an odd number of crosso...

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Autores principales:	VALENZUELA,CARLOS Y, PÉREZ-ALZOLA,PATRICIA, SANTOS,MANUEL J
Lenguaje:	English
Publicado:	Sociedad de Biología de Chile 2001
Materias:	50 % recombination tetrads odd-even crossovers SCE
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000000015
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spelling	oai:scielo:S0716-078X20010000000152001-06-27A critical view to explanations for the maximal value of 50 % of genetic recombinationVALENZUELA,CARLOS YPÉREZ-ALZOLA,PATRICIASANTOS,MANUEL J 50 % recombination tetrads odd-even crossovers SCE The maximal value of 50 % of genetic recombination (RF = recombination fraction) between two linked gene loci has been explained by two models: (i) the restriction of crossovers to only two of the four chromatids of a tetrad (tetrad model); (ii) the limit of the occurrence of an odd number of crossovers between two loci, when the expected number of crossovers tends to infinite (odd-even model). This article shows that (i) is wrong. If tetrads were responsible for the maximal 50 % RF, sister chromatid exchanges (SCE) should display a maximal 100 % RF. In mammalian CHO cells we found that SCE yield a maximal 50 % recombination. Also, we demonstrated that the maximal 50 % RF for tetrads occurs because the sum of odd order coefficients in the binomial distribution is equal to the sum of even order coefficients. At the end of meiosis the two chromatids of a chromosome that receives K crossovers are separated. Then K breaks should distribute into two chromatids. Thus, the expected number of breaks per chromatid distributes, when K is large, in 50 % of chromatids having an even number of breaks (RF = 0) and 50 % having an odd number (RF = 1), irrespective of tetrads, hexads, octads or more complex meiotic chromosome configurationsinfo:eu-repo/semantics/openAccessSociedad de Biología de ChileRevista chilena de historia natural v.74 n.1 20012001-03-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000000015en10.4067/S0716-078X2001000000015
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	50 % recombination tetrads odd-even crossovers SCE
spellingShingle	50 % recombination tetrads odd-even crossovers SCE VALENZUELA,CARLOS Y PÉREZ-ALZOLA,PATRICIA SANTOS,MANUEL J A critical view to explanations for the maximal value of 50 % of genetic recombination
description	The maximal value of 50 % of genetic recombination (RF = recombination fraction) between two linked gene loci has been explained by two models: (i) the restriction of crossovers to only two of the four chromatids of a tetrad (tetrad model); (ii) the limit of the occurrence of an odd number of crossovers between two loci, when the expected number of crossovers tends to infinite (odd-even model). This article shows that (i) is wrong. If tetrads were responsible for the maximal 50 % RF, sister chromatid exchanges (SCE) should display a maximal 100 % RF. In mammalian CHO cells we found that SCE yield a maximal 50 % recombination. Also, we demonstrated that the maximal 50 % RF for tetrads occurs because the sum of odd order coefficients in the binomial distribution is equal to the sum of even order coefficients. At the end of meiosis the two chromatids of a chromosome that receives K crossovers are separated. Then K breaks should distribute into two chromatids. Thus, the expected number of breaks per chromatid distributes, when K is large, in 50 % of chromatids having an even number of breaks (RF = 0) and 50 % having an odd number (RF = 1), irrespective of tetrads, hexads, octads or more complex meiotic chromosome configurations
author	VALENZUELA,CARLOS Y PÉREZ-ALZOLA,PATRICIA SANTOS,MANUEL J
author_facet	VALENZUELA,CARLOS Y PÉREZ-ALZOLA,PATRICIA SANTOS,MANUEL J
author_sort	VALENZUELA,CARLOS Y
title	A critical view to explanations for the maximal value of 50 % of genetic recombination
title_short	A critical view to explanations for the maximal value of 50 % of genetic recombination
title_full	A critical view to explanations for the maximal value of 50 % of genetic recombination
title_fullStr	A critical view to explanations for the maximal value of 50 % of genetic recombination
title_full_unstemmed	A critical view to explanations for the maximal value of 50 % of genetic recombination
title_sort	critical view to explanations for the maximal value of 50 % of genetic recombination
publisher	Sociedad de Biología de Chile
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000000015
work_keys_str_mv	AT valenzuelacarlosy acriticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination AT perezalzolapatricia acriticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination AT santosmanuelj acriticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination AT valenzuelacarlosy criticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination AT perezalzolapatricia criticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination AT santosmanuelj criticalviewtoexplanationsforthemaximalvalueof50ofgeneticrecombination
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A critical view to explanations for the maximal value of 50 % of genetic recombination

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