Occurrence of two different reciprocal translocations in the same litter of domestic pigs

Abstract

A translocation designated t(9p+ 11 q -) was found in a boar producing small litters but having a normal sexual behaviour and a normal semen picture. Investigation of one of his litters revealed, in addition to t(9p+ 11q-) in two individuals, another translocation designated rcp(1p-;8q+) in all offspring. The latter translocation had been transmitted from the dam. Both translocations concerned greatly unequal-sized chromosome segments but only rcp(1p–;8q+) could be demonstrated to be truly reciprocal. The breakages of both translocations had occurred in RBA-positive bands of telomeric and centromeric segments. These observations support the hypothesis that aberrations occur non-randomly in chromosomes and chromosome segments of the pig karyotype. Embryonic studies indicated that probably only one chromosomally unbalanced gametic product, der(11)t(9p+;11q-), can survive implantation. The t(9p+; 11q-) effected a reduced litter size of approximately 50 % in the proband and it was also assumed, although evidence was lacking, that rcp(1p-;8q+) implied impaired fertility for the carriers. Newborns had either normal or balanced heterozygous karyotype.