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A simple method for the estimation of recombination frequencies and genetic distances

100%

Benito C., Gallego A.

Cellular and Molecular Biology Letters

2004

tom 09

nr 4A

617-634

We have developed an alternative approach to the maximum likelihood method for calculating recombination values and linkage intensities. This new method is simpler than those in current use in that it obviates the need for formulae and tables. Maximum likelihood methods imply the use of iterative procedures over highly complicated estimation equations (at least second degree polynomials), whereas simplified methods use single-step procedures involving simple linear equations. The proposed method uses the frequencies of the distinguishable phenotypes that came from the union of at least one recombinant gamete with another gamete. We performed Monte-Carlo simulations for various combinations of genetic distance and offspring size. The recombination values obtained using the new method were compared with those derived by the maximum likelihood method on both simulated and experimental data. They were found to be nearly identical. The observed distribution of the recombination frequency values does not differ significantly from the Normal distribution, except for extreme values of the mean, as the Skewedness and kurtosis coefficients do not differ from zero. Our method has a similar accuracy to the maximum likelihood methods for recombination frequencies smaller than 25 cM and the difference does not increase greatly for greater frequencies.

The molecular diversity of different isolates of Beauveria bassiana [Bals.] Vuill. as assessed using inter-microsatellites [ISSRs]

80%

Estrada M. E., Camacho M. V., Benito C.

Cellular and Molecular Biology Letters

2007

tom 12

nr 2

Inter-microsatellite PCR (ISSR-PCR) markers were used to identify and to examine the genetic diversity of eleven Beauveria bassiana isolates with different geographic origins. The variability and the phylogenetic relationships between the eleven strains were analyzed using 172 ISSR-PCR markers. A high level of polymorphism (near 80%) was found using these molecular markers. Seven different isolates showed exclusive bands, and ISSR primer 873 was able to distinguish between all the strains. The dendrogram obtained with these markers is robust and in agreement with the geographical origins of the strains. All the isolates from the Caribbean region were grouped together in a cluster, while the other isolates grouped in the other cluster. The similarity exhibited between the two clusters was less than 50%. This value of homology shows the high genetic variability detected between the isolates from the Caribbean region and the other isolates. ISSR-PCR markers provide a quick, reliable and highly informative system for DNA fingerprinting, and allowed the identification of the different B. bassiana isolates studied.

Ograniczanie wyników

2 Cellular and Molecular Biology Letters

2 Benito C.

1 Camacho M. V.

1 Estrada M. E.

1 Gallego A.

1 2007

1 2004

Wyniki wyszukiwania

A simple method for the estimation of recombination frequencies and genetic distances

The molecular diversity of different isolates of Beauveria bassiana [Bals.] Vuill. as assessed using inter-microsatellites [ISSRs]