Mosaic 35,X/36,XY karyotype and intersex in a red panda (Ailurus fulgens fulgens).

A zoo-bred Himalayan red panda (Ailurus fulgens fulgens) was diagnosed as a presumptive intersex on clinical examination at 4-mo-of-age. The phenotype was predominantly female but showed a large anogenital distance and bilateral ischial swellings. Based on cytogenetic evaluation, the karyotype was mos35,X/36,XY, with 50% of each cell type. A grossly normal uterus and oviducts were seen with laparoscopic examination, while the gonads were smooth-surfaced, with a ramifying vascular pattern. On histopathologic examination the bulk of the gonads consisted of clumps of poorly differentiated cells, with just a thin rim of ovarian tissue under the region covered by the fimbriae of the oviduct.

Equine cytogenetics: role in equine veterinary practice.

The prognostic use of karyotyping in equine breeding has been recommended since 1976. Specimens used and laboratory methods are described. The system of karyotype evaluation is explained together with a glossary of terms. The principal aberrations in horses are defined. The present state of knowledge in cytogenetics in horses is reviewed dealing with infertility in the mare, where sex chromosomes give clear indication of problems; the situation with respect to anomalies found in stallions and hermaphroditism is explained coupled with recent concepts of chromosomal roles in reproduction. The future potential for the application of cytogenetics in equine practice is explained in regard to the advanced techniques and knowledge in the human parallel field. It is concluded that karyotyping is an essential tool in the evaluation of reproductive problems in practice and should be used more frequently in future.

Sex chromosome mosaicism and infertility in mares.

From the standpoint that cytogenetic screening in mares is seldom necessary as an aid to diagnosis of the gonadal dysgenesis syndrome, a series of double-blind trials were conducted to test the proposal that present practice failed to explore the potential for cytogenetics in clinical practice. It was demonstrated that diagnoses of infertility might be made where mares were found to be of normal phenotype by clinical examination. Such mares were found to be gonosmic mosaics. One stallion had a polymorphism of the X chromosome and had poor conception rates. It was demonstrated that the true value of chromosome testing in clinical stud practice has previously been misinterpreted and underestimated.

Congenital structural brain defects in the deaf dalmatian.

Deafness in dalmatian dogs in known to be congenital. It has been reported that the condition is manifested in structural defects of the sensitive lamina of the organ of Corti. In a study of deaf puppies, examined as they became available, this was found to be in doubt. Moreover, a characteristic gross reduction of area was found in the structure of the acoustic cortex in affected puppies. Extension of the morphometric studies further showed that the acoustic pathways were generally attenuated in keeping with the changes in the cortex. Consideration is given to the probability that the condition develops centrally rather than peripherally. Thus instead of the central components failing to develop because of lack of evocative stimulus from the end organ it is envisaged that the peripheral organ regresses because of incomplete innervation by central outgrowth.

Loss of secretion in mouse-human hybrids need not be due to the loss of a structural gene.

Three cloned mouse-human lines (B1-29, E2-42, and A2-31) secreting human immunoglobulin (Ig) were obtained from a fusion between the mouse myeloma line NS-1 and human tonsillar lymphocytes stimulated in vitro with pokeweed mitogen. One line, B1-29, has continued to secrete human IgG for a period of 2 yr in culture. This line was recloned three times to give a panel of secreting and nonsecreting subclones. Most of the nonsecreting subclones had also lost surface Ig. The structural genes for human Ig heavy chains have been provisionally assigned to chromosome 14, which also encodes the enzyme nucleoside phosphorylase. Human nucleoside phosphorylase was detected in all secreting and nonsecreting B1-29 subclones, indicating the presence of human chromosome 14. The retention of chromosome 14 in nonsecreting clones implied that the structural genes for human Ig were A2-31 and E2-42, which had stopped secreting, an attempt was made to restimulate the secreting of human Ig with mitogens A2-31 was unique among the cell lines examined, in that chromosome 14 could not be detected by an isoenzyme marker. Lipopolysaccharide, at an optimum dose of 10 micrograms/ml, restimulated these nonsecreting hybrid lines to secrete human IgG in levels up to 0.7 micrograms/ml. Loss of Ig secretion may not therefore be caused by loss of Ig structural genes.

Studies on hybridization between a Barbary ram (Ammotragus lervia) and domestic ewes (Ovis aries) and nanny goats (Capra hircus).

Six nanny goats and 9 ewes were inseminated with Barbary semen and 4-5 days after insemination 16 hybrid embryos were recovered: 14 were transferred to ewes or nanny goats. Survival of embryos was monitored by return to service after transfer, peripheral plasma progesterone values and by examination at laparotomy. None of the Barbary ram x ewe embryos transferred to 4 ewes and 4 nanny goats or the Barbary ram x nanny goat embryos transferred to ewes survived. Of the 4 nanny goat recipients of Barbary rm x nanny goat embryos one had a resorbed fetus at 7 weeks after transfer, one was pregnant at 7 weeks but failed to produce a young and a third produced a healthy male 155 days after the transfer oestrus. The karyotype of the hybrid was 2n = 59XY, characterized by a single metacentric chromosome.

An autosomal centric fusion translocation in the Red Poll breed in Australia.

The karyotype 2n = 59,XY,t:1/29 was found in two pure bred Red Poll bulls originating from stock imported from Britain. Orthodox stained and G-banded karyotypes of the condition in this breed are presented for the first time. Non-return rates for one bull suggest no impairment of fertility when selected for artificial insemination. However, in a related herd infertility has become a serious problem. It is suggested that selection pressure does not operate to eliminate the translocation and that caution should be exercised in the use of animals.

The Giemsa banding pattern of the Australian Swamp Buffalo (Bubalus bubalis): chromosome homology with other bovidae.

A Giemsa banding method was used to obtain preparations from which a G-band idiogram for the chromosomes of the Australian Swamp Buffalo (Bubalus bubalis) was constructed. Comparison with the G-banding patterns for goat, sheep, and ox chromosomes showed a remarkably close similarity individual paris, banding pattern homologies for the buffalo metacentric autosomes being identifiable among the acrocentric autosomes of the other species. However, the goat and sheep lacked a comparable autosome to the buffalo 10, the buffalo lacked an autosome comparable to the ox 12, the acrocentric X chromosome of the buffalo banded most closely to the goat X and was least like the ox. The buffalo Y chromosome was unlike its counterpart in the other species. The results are in keeping with the previously expressed view of evolution within the Bovidae by a Robertsonian mechanism modified by the apparent absence of one pari of autosomes from the buffalo and of a different pari from sheep and goats.

Bos taurus Y chromosome of Africander cattle and the development of improved breeds for the tropics.

The Africander has anatomical and other characteristics of an animal of approximately 3/4 Bos indicus heredity. The fact that these cattle carry the Bos taurus Y chromosome supports this view and indicates that the local cattle in South Africa would have been crossed with one or more Bos taurus bulls. Droughtmaster and Braford cattle retain the Bos indicus Y chromosome because Bos indicus instead of Bos taurus bulls were used to establish these taurindicus breeds. Contrary to some assumptions, an approximate tenfold increase in productivity of cattle was made during the 18th and 19th centuries due to improvements in disease control, nutrition and genetic improvement. What is now needed is the development of taurindicus breeds combining to the maximum possible extent the disease resistance and hardiness of Bos indicus with the early maturity and productivity of Bos taurus cattle. In addition, the ravages of disease and the seasonal variations of food supply need to be overcome in tropical areas.

Chromosomes of cattle: present clinical status and promise.

Current information on cytogenetics in veterinary medicine is presented as a resume for the veterinarian in cattle practice; previous reviews of the subject are recorded. The literature depicting the recognised chromosome abnormalities in cattle is breifly reviewed. It is suggested that chromosome screening already has a role to play in the economics of cattle production.