Reziproke Translokation 60, XY, t (10; 11) (41; 14) beim Rind

Fatal Outcome in a Newborn Calf Associated with Partial Trisomy 25q and Partial Monosomy 11q, 60,XX,der(11)t(11;25)(q11;q14∼21)

A newborn calf of the Agerolese cattle breed underwent clinical cytogenetic investigation because of hyperflexion of the forelimbs, red eyes and the inability to stand. Anamnesis revealed that the mother, phenotypically normal, carried a chromosomal aberration. The newborn died after 2 weeks, and no remarkable alterations were found by the veterinarian on postmortem examination. The mother was a carrier of a reciprocal balanced translocation rcp(11;25)(q11,q14∼21) detected after a cytogenetic investigation in 2011; however, the analysis of the newborn revealed a different chromosomal aberration with partial trisomy of chromosome 25 and partial monosomy of chromosome 11. In fact, the results showed both chromosomes 25, one chromosome 11 and only one long derivative chromosome (der11). FISH analysis, performed using BAC clones, confirmed the chromosomes and their regions involved. Finally, both the localization of the breakpoints on band q11 (centromere) of chromosome 11 and band q14-21 of chromosome 25, and the complete loss of the der25 identified the aberration as an unbalanced translocation 60,XX,der(11)t(11;25)(q11;q14∼21). A comparison with human chromosomes was also performed to search for similarities and possible genes involved in order to study their effects, thus extending the knowledge of these aberrations by case reports.

A 4/21 tandem fusion in cattle

A tandem fusion involving chromosome 4 and chromosome 21 of the bovine karyotype, is described in a newborn Holstein-Friesian heifer which was also a blood chimera exhibiting female cells of normal bovine karyotype and male cells with a 59, XY + tan (4:21). The rearranged chromosome was a dicentric and the longest acrocentric in the male cells. Apart from the features characteristic of the freemartin condition, no other phenotypic abnormalities were detected in the heifer calf. Since the heifer and other calves of the herd were not eartagged at birth, 20 newborn bull calves of the same age in the herd were analyzed in an attempt to identify the male born co-twin to the heifer. However, this effort proved unsuccessful, probably because the co-twin had died in utero or was erroneously included among the calves sent to the slaughter house.

Embryo quality and andrological study of two subfertile bulls versus five control bulls with normal fertility

Andrological studies and embryo morphology evaluation of superovulated cows were performed on 2 randomly selected subfertile dairy bulls whose semen was used for artificial insemination and on 5 control bulls with normal fertility. Neither sperm motility studies, nor sperm morphology or testicular measurements differed between the subfertile and the control bulls. Altogether 315 ova were recovered from 41 superovulated cows inseminated with semen collected from either the subfertile or the normal control bulls. The spermatozoa of one of the 2 subfertile bulls was shown to have a decreased ability to fertilize superovulated ova, while the other subfertile animal, the bull with the lowest no-return rate, was found by chromosome analysis to have a reciprocal translocation (60, XY, rcp 20:24), causing embryonic death. We suggest that subfertile bulls should not be used in commercial embryo transfer programs nor in artificial insemination and that andrological studies on subfertile bulls with good sperm motility should include evaluation of 6- to 7-day-old ova from superovulated cows to determine if the fertilization rate is normal or impaired. A chromosome analysis should also be performed when a subjertile bull has a normal fertilization rate of ova.