Cleft palate associated with an unbalanced karyotype in piglets sired by a heterozygous carrier boar with a balanced constitutional reciprocal translocation.

The progeny of a commercial (Landrace x Duroc) x Large White boar contained a number of piglets with cleft palates. Chromosomal analyses of five affected piglets showed that they all had an identical unbalanced karyotype with partial monosomy of chromosome 16 and partial trisomy of chromosome 3, whereas the normal piglets in the litters had balanced karyotypes. The chromosomal imbalance was the direct result of a constitutional balanced reciprocal translocation carried by their heterozygote sire, described, according to the standard nomenclature, as t(3;16)(q23;q22).

Chromosomal abnormalities in hypoprolific boars.

Four new chromosomal rearrangements are reported in the domestic pig: 3 reciprocal translocations, rcp(4;12)(p13;q13) in a crossbred boar, rcp(1;7)(q17;q26) in a Large White purebred boar, rcp(1;6)(q17;q35) in a purebred synthetic paternal line boar, and a pericentric inversion inv(2)(p13q11) in a crossbred boar. The 1/7 reciprocal translocation and the pericentric inversion were detected in animals that had sired small litters. The effect of the 1/7 translocation was accurately determined: -4.5 piglets born per litter, i.e. -36%. Both the 1/6 and 1/7 reciprocal translocations were of maternal origin. All the chromosomal rearrangements were highlighted using GTG and/or RBG banding techniques. Chromosome painting experiments were also carried out to confirm the proposed hypotheses for the three reciprocal translocations.

A new reciprocal translocation in a subfertile bull.

Three bulls of the Montbéliarde breed that exhibited fertility rates lower than 30% following more than 400 artificial inseminations were examined. Semen quality (sperm motility and morphology) from these bulls was normal. Fertilizing ability estimated from in vitro embryo production results was studied for two of them. In vitro production rate was very low for one bull (A) and normal for the other (B). Cytogenetic analyses were carried out on the three bulls using chromosome banding techniques. These analyses revealed a reciprocal translocation (12;17)(q22;q14) in bull B. Based on family analyses, the hypothesis of a de novo origin of this rearrangement is proposed.

Five new cases of reciprocal translocation in the domestic pig.

Five new cases of reciprocal translocation in the domestic pig are described. Three of them, rep(3;5)(p1.3;q2.3), rep(6;13)(p1.5;q4.1) and rep(13;17)(q4.1;q1.1) were found in boars with decreased litter size. The remaining two were identified in animals karyotyped before reproduction: a young boar, rep(4;6)(q2.1;q2.8), and a gilt, rep(2;14)(q1.3;q2.7). A parental origin by inheritance of the translocations was established in cases 1, 4, and 5. A decrease in prolificacy of 43% and 34% was estimated in cases 1 and 3, respectively.

Nine new cases of reciprocal translocation in the domestic pig (Sus scrofa domestica L.).

Nine pigs with decreased litter size or sired by boars with decreased litter size were found to be reciprocal translocation carriers. Four Large White animals (two females and two males) demonstrated translocations involving chromosomes 1 and 9 (1p-;9p+), 11 and 13 (11q+;13q-), 3 and 13 (3;13)(p1.5;q3.1), and 15 and 17 (15;17)(q1.3;q2.1). Two Large White x Pietrain terminal boars demonstrated translocations involving chromosomes 11 and 16 (11;16)(p1.4;q1.4), and 6 and 14 (6;14)(q2.7;q2.1). The (9;15)(p2.4;q1.3) and (6;16)(q1.1;q1.1) translocations were found in a Large White x French Landrace boar, and in a commercial male line boar with decreased litter size, respectively. A Gascon breed boar with reduced prolificacy also had an abnormal karyotype, namely 38 XY, rcp(1;6)(q1.2;q2.2). Reduction in prolificacy was estimated accurately in cases 3, 5, 6, 7, and 9 (35%, 30%, 35%, 41%, and 56%, respectively). Rcp(1;6)(q1.2;q2.2) and rcp(6;16)(q1.1;q1.1) seemed to have been of de novo origin.

Characterization of reciprocal translocations in pigs using dual-colour chromosome painting and primed in situ DNA labelling.

We report the use of dual-colour chromosome painting to determine the exact nature of certain chromosome rearrangements observed in the pig (Sus scrofa domestica). The chromosomal abnormalities were detected by GTG- and RBG-banding techniques. The initially proposed interpretations were: (1) rcp(6;13)(p1.5;q4.1); (2) rcp(11;16)(p1.4;q1.4); (3) rcp(6;16)(p1.1;q1.1); (4) rcp(13;17)(q4.1;q1.1); (5) rcp(6;14)(q2.7;q2.1); (6) rcp(3;5)(p1.3;q2.3); (7) rcp(2; 14)(q1.3;q2.7); (8) rcp(15;17)(q1.3;q2.1). Hybridizations were carried out with biotin- and digoxigenin-labelled probes obtained by priming authorizing random mismatches polymerase chain reaction (PARM-PCR) amplification of porcine flow-sorted chromosomes. In some cases, i.e. (1), (4), (5), (6), (7) and (8), the fluorescence in situ hybridization (FISH) results allowed confirmation of the interpretations proposed with classical cytogenetic methods. Chromosome painting proved the reciprocity of the translocation in cases (1), (6) and (8), whereas modifications of the formula were proposed for case (2). Primed in situ DNA labelling (PRINS) experiments have also been carried out in case (3) using a primer specific for the centromeres of acrocentric chromosomes (first experiment) or a primer specific for the centromeres of a subset of meta- and submetacentric chromosomes including chromosome 6 (second experiment). It allowed us to demonstrate that the breakpoints occurred in the centromeric region of chromosome 16 and in the p. arm of chromosome 6, just above the centromere.

Chromosomal evolution in gazelles.

The chromosomes of nine gazelle species and two other Antilopinae species (Antidorcas marsupialis and Antilope cervicapra) were prepared from fibroblast cultures. G- and C-band karyotypes were constructed, and when possible, autosomal arms were numbered according to the cattle standard karyotype. Diploid chromosome numbers ranged from 30 to 58. Based on band similarity, chromosome-arm homoeologies were extensive, whereas shared homoeologous biarmed chromosomes were rare. Therefore evolution in this genus could have occurred mainly by speciation following monobrachial homoeology of centric fusions. X to autosome translocations were common in the whole genus. Furthermore, chromosome Y was also involved in an autosome translocation in gazelles from the subgenus Nanger and in Gazella thomsoni and G. rufifrons. Based on these karyotypic data a phylogenetic tree is proposed. This phylogenetic reconstruction confirms most of the taxonomic relationships obtained by morphological analyses for this group of species. The main novelties are the proximity of G. rufifrons and G. thomsoni and the inclusion of Antilope cervicapra in the gazelle group.