Cytogenetic and blood group studies of sheep/goat chimaeras.

Aggregation chimaeras were composed of quarter (or 1 cell) contributions from 4-cell blastocysts of sheep or goats, or of an 8-cell blastocyst of one species enveloped in three 8-cell blastocysts of the other. Gestation was in sheep or goat recipient females. Of the 10 living animals born, 3 were identified as interspecific chimaeras by body conformation and coat type among the 7 quarter/quarter aggregations and 1 among the 3 giant aggregates. Interspecific chimaerism was identified by cytogenetic study of umbilicus and blood lymphocytes respectively of 2 of these, one from each type of aggregate. Intraspecific sex chimaerism was found in 3 other animals; 2 were of giant aggregate origin, but the 1 of quarter/quarter origin must have acquired it by placental anastomosis with a twin conceptus. Tests using species-specific monoclonal antibodies and electrophoretic separation of haemoglobins and isoenzymes demonstrated sheep and goat erythrocytes in one giant aggregate chimaera; their relative proportions and those of the blood lymphocytes changed over a period of 31 months from approximately 60% goat and 40% sheep to more than 90% sheep. The plasma transferrins and amylases did not show similar relative changes from their predominantly goat-like character and, by implication, neither did their tissues of origin.

Cytogenetic studies of 1-29 translocation carrying cows and their embryos.

An examination has been made of embryos from infertile 1-29 translocation carrying heifers. Cytogenetic measurements of C-banded chromosomes from these cattle, together with those from fertile 1-29 cows, have been made and compared with those from normal karyotypes. There are relative differences between normal animals and translocation carriers in the ratios of total to C-banded material throughout the karyotypes: their possible effects on mitosis and meiosis are discussed. Of the embryos recovered from the infertile heifers, one did not survive transplantation and others had various indications of inviability.

Chromosome mapping in cattle using mouse myeloma/calf lymph node cell hybridomas.

A study correlating the presence of bovine isozymes in mouse myeloma/calf hybridomas with specific banded chromosomes of their bovine complement has enabled tentative assignments to be made of the bovine isozyme locus for peptidase C (PEP C) to chromosome 5 and the syntenic group lactate dehydrogenase B/peptidase B (LDH B/PEP B) to chromosome 19. There was some evidence for the association of LDH A with one of the last seven small pairs (23-29) of the complement and of superoxide dismutase 1 (SOD 1) with chromosome 13.

Specific bovine monoclonal antibody produced by a re-fused mouse/calf hybridoma.

Hybridomas made by fusing NSO (subline NSI Ag 4-1) mouse myeloma cells with lymph node cells from a calf immunized with sheep red blood cells failed to maintain antibody secretion in culture. However, when two of these hybridomas were selected in 8-azaguanine and then re-fused with immunized calf lymph node cells, several lines were obtained that secreted bovine Ig. One cloned line, producing bovine IgG1 (strongly lytic in the presence of rabbit complement and presumed to be an anti-Forssman) was maintained in culture for five months. Cytogenetic studies confirmed that the mouse/calf hybridomas lost bovine chromosomes as they proliferated, but that re-fusion increased the bovine complement from a mean of 5 (2 n) to 11 (2 n) bovine chromosomes per cell. It is proposed that the selected hybridoma lines may be suitable fusion partners for the production of further monoclonal bovine antibodies.

Culture of sheep X mouse hybridoma cells in vitro.

Hybridomas were made between NS1/1-Ag4-1 mouse myeloma cells and spleen and lymph node cells from a sheep immunized with sheep red cells (RBC). The hybrid colonies grew well in culture but there was a substantial loss of sheep chromosomes. No hemolytic or agglutinating antibodies were detected in the culture supernatants after the 17th day following fusion, but immunofluorescence tests indicated that a few of the cells may have been expressing sheep IgG. Cytogenetic comparison of cells grown with and without HAT medium provided evidence that the enzyme HGPRT is located on the X chromosome of sheep as it is in man and mouse. Hybridoma isozyme patterns of esterase, G6PD, 6PGD, NP, LDH and SOD tested between the 63rd and 71st day of culture were like those of NS1; NP and LDH also showed zones that probably came from the sheep component.

A cytogenetic study of a Barbary sheep (Ammotragus lervia) x domestic goat (Capra hircus) hybrid.

An account is given of stillborn male twins born to a female Saanen goat (Capra hircus) and a Barbary ram (Ammotragus lervia). The cytogenetics of the cultured hybrid cells are described and attention is drawn to the high proportion of cells which lacked one chromosome.

Two intersex dogs with mosaicism.

Two intersex dogs with various degrees of mosaicism in the somatic tissues are described. Normal female cells as well as Y-bearing cells with aneuploidy and other abnormalities were involved. In the Red setter an ovarian cortex had developed in mosaic gonads with 8 and 10% of Y-bearing cells. Slight masculinization of the medullae corresponded with some external virilization. These observations support the existence of a threshold proportion of Y-bearing cells for testicular differentiation. Fragments of chromatin in 36% or fewer of the cells in the Cocker spaniel may have been translocated Y-chromosome material.

A chimaeric calf with XY/XXY mosaicism and intersexuality.

A Friesian calf with an elongated urethra and without a vulva was born twin to a dead bull calf. Red cell chimaerism and XY/XY/XXY lymphocytes were found in the blood, XX/XXY mosaicism was found in the skin and the minute gonads which some showed signs of early testicular development.

Sex chromosome chimaerism and the transmission of blood group genes by tetraparental rams.

A previously published study of 4 rams, 3 of them tetraparental chimaeras, has been extended. All were born subsequent to transplantation of separated blastomeres into intact 4--8-cell embryos which were transferred to recipient ewes. All were phenotypically normal males. Study of blood lymphocytes and red cell antigens showed that two were XX/XY chimaeras, one an XY/XY chimaera. Chimaerism was not identified in the 4th animal. The new data show that the previously reported decline in proportions of red cells derived from the one cell line has continued, although the proportions of lymphocytes entering mitosis in culture have remained nearly constant. A decline of potassium concentration in the red cells of one animal and of transferrin type in another also continued. Analysis of blood types in the offspring of the 4 rams revealed that both cell lines of the XY/XY chimaera must have produced functional spermatozoa whereas the genes transmitted by the remaining 3 rams gave evidence of spermatozoa from one cell line only.