Genet. Sel. Evol. 36 (2004) 123-137
DOI: 10.1051/gse:2003055

Estimation of the proportion of genetically unbalanced spermatozoa in the semen of boars carrying chromosomal rearrangements using FISH on sperm nuclei

Alain Pinton^a, Alain Ducos^a and Martine Yerle<sup>b

a</sup>  UMR INRA-ENVT Cytogénétique des populations animales, École nationale vétérinaire de Toulouse, 23, chemin des Capelles, 31076 Toulouse Cedex 3, France
^b  Laboratoire de génétique cellulaire, Institut national de la recherche agronomique, Auzeville BP 27, 31326 Castanet-Tolosan Cedex, France

(Received 12 March 2003; accepted 23 May 2003)

Abstract
Many chromosomal rearrangements are detected each year in France on young boars candidates for reproduction. The possible use of these animals requires a good knowledge of the potential effect of the rearrangements on the prolificacy of their mates. This effect can be estimated by an accurate determination of the rate of unbalanced spermatozoa in the semen of boars which carry the rearrangements. Indeed, these spermatozoa exhibiting normal fertilizing ability are responsible for an early embryonic mortality, and then, for a decrease of the litter sizes. The "spermFISH" technique, i.e. fluorescent in situ hybridization on decondensed sperm heads, has been used on several occasions in Man, in this perspective. In livestock species, this method was formerly used mainly for semen sexing purposes. We used it, for the first time, to estimate the rates of imbalance in the semen of four boars carrying chromosomal rearrangements: two reciprocal translocations, rcp(3;15)(q27;q13) and rcp(12;14)(q13;q21), as well as two independent cases of trisomy 18 mosaicism. The rates of unbalanced gametes were relatively high for the two reciprocal translocations (47.83% and 24.33%, respectively). These values differed from the apparent effects of the rearrangements estimated using a limited number of litters: a decrease in prolificacy of 23% (estimation obtained using the results of 6 litters) and 39% (57 litters), respectively for the 3/15 and 12/14 translocations. The imbalance rates were much lower for the trisomy mosaics (0.58% and 1.13%), suggesting a very moderate effect of this special kind of chromosomal rearrangement.

Key words: reciprocal translocation / trisomy mosaic / gamete / fluorescent in situ hybridization / chromosome

Correspondence and reprints: a.ducos@envt.fr

© INRA, EDP Sciences 2004