Cytogenetic studies in a canine mammary tumor.

In a 9-year-old female dog (Basset Artesian Normand) with a mammary adenocarcinoma, cytogenetic evaluation of tumor cells showed a chromosome number of 76 in most metaphases (95%). The following abnormalities were found: symmetric metacentric chromosomes 1 and 6, centric fusion 3/38, a marker X-chromosome (Xmar) and a biarmed small marker chromosome (mar). In the remaining metaphases (5%) there were additional biarmed marker chromosomes present.

Circulating immune cells and immune complexes in peripheral blood of healthy and of bovine leukemia virus-infected cows and lymphosarcomatous calves.

The peripheral blood (lymphocytes and immune complexes (IC) from 20 healthy cows, 5 healthy calves, 10 bovine leukemia virus-infected cows and 4 lymphosarcomatous calves was investigated using 4 different immunological techniques. A highly significant increase in the percentage of surface immunoglobulin (SIg)-bearing peripheral blood lymphocytes of persistent lymphocytosis-cows could be demonstrated while the percentage was decreased in the lymphosarcomatous calves. Percentages of spontaneous sheep red blood cells(SRBC)-rosettes (E-rosettes) were not elevated. Antibodies to bovine leukemia virus-antigen were detected in the sera (immuno-diffusion test) of all the leukotic cows but not of the lymphosarcomatous calves. Although there seems to be an increased level of IC in the advanced stage, as compared to the beginning of the disease, there was no statistically significant difference in comparison with the control individuals. In the lymphosarcomatous calves as well as in the leukemic cows there was no statistical difference in the IC values between diseased animals and controls.

Polymorphisms of NORs and Heterochromatin in the Horse and Donkey.

Chromomycin A3 (CMA3) banding in mitotic sets of the Equidae horse and donkey were used to demonstrate both constitutive heterochromatin and R-banding. Intra and Interindividual variation In the size of the heterochromatic blocks was observed In many cases. CMA3-posittve telomeric heterochromatin blocks appeared on several chromosomes of the horse and donkey. Some of them were especially spectacular in the donkey. A sequential silver NOR-chromomycin A3/distamycln A-DAPI (CDD) staining procedure led to the detection of the localization of active nucleolus-organizing regions (NORs) and to the identification of chromosomes. The data revealed individual specific NOR patterns in both species.

In vitro fertilization and cleavage of bovine oocytes matured in medium supplemented with estrous cow serum.

Bovine follicular oocytes were matured in TCM 199 supplemented with: (1) fetal calf serum (FCS, 20% v/v), Luteinizing Hormone (LH, 10 ug/ml), and Estradiol-17-beta (E(2), 1 ug/ml) in Experiment 1; (2) 20% cow serum recovered at standing estrus (Experiment 2); or (3) 20% FCS (Experiment 3). Maturation, fertilization, and initial cleavage development were evaluated at 16 and 48 h after in vitro insemination. The proportions of oocytes fertilized after maturation in the presence of added hormones (78.5%, Experiment 1) or estrous serum (71.3%, Experiment 2) were significantly higher (p < 0.01) than after use of FCS alone (39.3%, Experiment 3). Cleavage of zygotes within 48 h post-insemination differed significantly (p < 0.01) between maturation treatments, 27.3%, 75.5% and 6.6% for Experiments 1, 2, and 3, respectively. Results demonstrate a beneficial influence of estrous cow serum, characterized by an elevated concentration of LH, on bovine oocyte maturation in vitro.

Cytogenetic studies in a canine malignant melanoma.

In a 13-year-old, male rough-haired Dachshund with a malignant melanoma, cytogenetic evaluation of tumour cells showed hyperdiploidy (79 to 81 chromosomes) in 50 per cent of the metaphases. Several bi-armed chromosomes (centric fusions, one isochromosome and two unidentified markers) were observed.

Characterisation of complex karyotype changes in two canine bone tumours.

Two dogs developed osteosarcomas. In both cases, the cytogenetic analysis revealed the presence of numerically and structurally altered karyotypes. The chromosome ranges were 90 to 99 and 65 to 67, respectively. Centric fusions frequently identified were 1/3, 1/30 and 2/9 in one case, 3/19, 12/18 and 13/17 in the other.

Characterisation of complex karyotype changes in a canine thyroid adenoma.

A 14-year-old German shepherd dog developed an alveolar adenoma of the thyroid. The cytogenetic evaluation of the tumour cells showed two ranges of chromosome numbers. Centric fusions 2/32, 5/26, 6/11, 8/11, 9/23 and 14/31 were G-band identified in this complex change of karyotype.

Mithun cross siri hybrids: cyto- and immunogenetic examinations and characterisation of abnormal spermatogenesis.

Cytogenetic studies of the mithun (Bos frontalis), the siri (Bos indicus) and their hybrids, as well as histological examinations of testes and epididymis of siri and hybrids were undertaken to throw further light on male hybrid infertility and interspecies incompatibility, in order to facilitate the possible development of a stable interspecies crossbreed which would be similar to the highly profitable jatsum, the female mithun cross siri hybrid. In both species there are distinct centromeric heteromorphisms which should provide a rich source of genetic markers for tracing chromosomes in controlled hybrid programmes. The nucleolar organisers in the F1 hybrids were derived from both parents, in contrast to other interspecies hybrids where the nucleolar organisers of one species tend to be suppressed by the other. This indicates a relatively close relationship between mithun and siri and supports the prospect of success for developing a stable crossbreed. Transferrins which may also be a useful source of genetic markers were identified and differences between siris and mithuns noted, especially in the D-bands. No A-bands were found in the siris and no E-bands in the mithuns. Whether this is a breed or species characteristic will have to be confirmed by examination of more animals. The findings on blood groups and haemoglobins, including differences between the two species, were similar to results obtained previously. In meiosis the sex vesicles were intact which indicates that infertility and incompatibility factors should be located in autosomes. In cytogenetic and histological examinations the testes of the siris were comparable to those of European cattle, while in all hybrids spermatogenetic activity was deficient although there were great differences between and within generations. While the exact mechanism of this diversity is not known at this stage, it should make it possible to select for increased male hybrid fertility which would be a prerequisite for developing a stable interspecies crossbreed. This selection would be facilitated by correlating infertility and incompatibility with genetic profiles and markers. A mithun cross siri crossbreed would also serve as a model for other interspecies breeding.

Analysis of complex cytogenetic alterations in three canine mammary sarcomas.

Cells of mammary sarcomas in three dogs were analysed cytogenetically. In an osteoidsarcoma, hyperdiploidy with a range of 92 to 98 chromosomes, and several structural aberrations (for example, a derivative chromosome 1, isochromosome 13 and several bi-armed markers) were observed. Isochromosome 13 was also present in a case of an osteoidchondrosarcoma. In a case of chondro-osteosarcoma both hypodiploidy with a chromosome range of 60 to 66 and hyperdiploidy with a range of 115 to 128 and several centric fusions were observed.

Chromosomal hyperdiploidy in a feline sarcoma.

An eight-year-old male cat developed a sarcoma. The cytogenetic evaluation of the tumour cells showed the presence of hyperdiploidy (range 40 to 46 chromosomes). This hyperdiploidy was encountered in all the cells examined. Extra-chromosomes numbers C1, C2, B4, D4 and E3 were mainly responsible for the hyperdiploid chromosomal complements. There was a high incidence of monosomy E3.

Cytogenetic variation between four cases of feline fibrosarcoma.

Short term cultures of four feline fibrosarcomas were analysed cytogenetically. There was marked genetic heterogeneity between the four cats, each showing a different clonal abnormality. The aberrations detected were one deleted B2, one marker F1 and two reciprocal translocations, t (A2q; E3q) and t (A1q; B4p).

Cytogenetic analyses of four solid tumours in dogs.

Four solid tumours (one haemangiopericytoma, one haemangioendothelioma, one spindle-cell sarcoma and one mammary carcinoma) in dogs were analysed cytogenetically. In the haemangiopericytoma, an additional small chromosomal segment was present. Very complex changes including centric fusions and symmetric meta-centrics 1, 6, 10 and 12 were conspicuous in the highly unbalanced karyotype of the haemangioendothelioma. Complex changes, particularly many centric fusions and a tandem translocation 4/14, were features of the spindle-cell sarcoma. One centric fusion and a symmetric metacentric 13 were present in the mammary carcinoma.

Trisomy D2 in a feline neurofibroma.

An eight-year-old female cat developed a skin neurofibroma. The cytogenetic evaluation of the tumour cells showed the presence of a high percentage (16.4 per cent) of trisomic cells. The trisomy concerned chromosome number D2.

Karyotyping, red blood cell and haemoglobin typing of the mithun (Bos frontalis), its wild ancestor and its hybrids.

In Bhutan in remote parts of the Himalayas the mithun (Bos frontalis) has been used probably for centuries in an ingenious system for crossbreeding with domestic cattle which results in highly profitable hybrid females. The hybrid males are infertile and so far no stable crossbreed has been developed. Genetic analyses reported in this paper support the view that the gaur is the wild ancestor of the mithun. Both have only 58 chromosomes in contrast to 60 in cattle and also different, hitherto undescribed haemoglobins and blood groups which would justify the revision of the present classification of the subfamily Bovinae. If, with the aid of modern genetic methods, a stable crossbreed could be developed, dairy and beef production in Bhutan and many climatically similar areas could benefit greatly. Because of its remarkable size the mithun may, in the hands of enterprising breeders, also make a useful genetic contribution to beef production elsewhere.

Genetic characterisation of the mithun (Bos frontalis) and studies of spermatogenesis, blood groups and haemoglobins of its hybrids with Bos indicus.

The mithun (Bos frontalis) and its hybrids with Bos indicus were studied to provide further cytogenetic information which might throw light on the mechanisms of the male hybrid infertility and facilitate the establishment of a stable crossbreed. It was shown that compared with conventional cattle the mithun has a homozygous, species specific 2/27 centric fusion which reduced the diploid chromosome number from 60 to 58. This provided further proof that Robertson translocation-type rearrangements have been the major source of interspecies karyotype differences in the evolution of the Bovidae. In the mithun there was also significant polymorphism between centromeres of non-homologous chromosomes and there was heteromorphism between several homologous chromosomes which could possibly serve as useful genetic markers for breeding programmes. In F1 hybrids spermatogenesis progressed to a relatively advanced stage, without going so far as to produce spermatozoa. In back crosses to B indicus spermatogenesis progressed further so that spermatozoa could be seen, though not as numerous as in normal bulls. In most hybrids there were haemoglobin bands which corresponded either to Hb A or Hb B of cattle but were much wider. It was shown that these were a combination of Hb Mi derived from the mithun and Hb A or Hb B derived from B indicus. In a few hybrids there were only Hb Mi. In these cases Hb Mi had been present in both parents and proved that the dam was not a pure siri. The possible mechanism of hybrid male infertility is discussed including faults in the epistatic gene effect between chromosomes and changes in the degree of association of centromeric regions in interspecies hybrids. It is suggested that additional cytogenetic examination of blood lymphocytes and especially of testicles would help the understanding of the fertility barriers of hybrid males and would make a breeding programme for a stable crossbreed possible.

Cytogenetic characterization of the Madin-Darby bovine kidney cell line.

The permanent bovine cell line, Madin-Darby bovine kidney, was cytogenetically analyzed. Chromosomal staining indicated 52 metaphase chromosomes with variations from 49 to 54. The isochromosomes 5, 12, and 13, and centric fusions between chromosomes 1 and 26, 9 and 11, 9 and 24, 17 and 25, 18 and 23, 20 and 24, and 24 and 27 were considered marker chromosomes.