CHROMOSOME CHANGES IN CELL CULTURE INDUCED BY MYCOPLASMA INFECTION

First sex modification case in equine cloning

Somatic cell nuclear transfer (SCNT) is an asexual reproductive technique where cloned offspring contain the same genetic material as the original donor. Although this technique preserves the sex of the original animal, the birth of sex-reversed offspring has been reported in some species. Here, we report for the first time the birth of a female foal generated by SCNT of a male nuclear donor. After a single SCNT procedure, 16 blastocysts were obtained and transferred to eight recipient mares, resulting in the birth of two clones: one male and one female. Both animals had identical genetic profiles, as observed in the analysis of 15-horse microsatellite marker panel, which confirmed they are indeed clones of the same animal. Cytogenetic analysis and fluorescent in situ hybridization using X and Y specific probes revealed a 63,X chromosome set in the female offspring, suggesting a spontaneous Y chromosome loss. The identity of the lost chromosome in the female was further confirmed through PCR by observing the presence of X-linked markers and absence of Y-linked markers. Moreover, cytogenetic and molecular profiles were analyzed in blood and skin samples to detect a possible mosaicism in the female, but results showed identical chromosomal constitutions. Although the cause of the spontaneous chromosome loss remains unknown, the possibility of equine sex reversal by SCNT holds great potential for the preservation of endangered species, development of novel breeding techniques, and sportive purposes.

Chromosome abnormality in a human TCGF-dependent T-lymphocyte culture generated against autologous melanoma cells in vitro

Six T-cell growth promoting factor (TCGF)-dependent T-cell cultures and phytohemagglutinin-stimulated peripheral blood lymphocytes from a patient with metatastic malignant melanoma were karyotyped. Three of the TCGF-dependent cultures were noncloned, started after in vitro sensitization against autologous malignant melanoma cells in tissue culture. A fourth was a subculture of one of these. The two remaining T-cell cultures were generated by in vitro sensitization of the same individual's lymphocytes against allogeneic Epstein-Barr virus-transformed B-cell lines. One of the cultures (AV7) and its subculture (AV/LDP39) showed a 17q+ anomaly in 100% of metaphases studied. All other TCGF-dependent T-cell cultures and fresh blood lymphocytes had normal karyotypes. The possible mode of origin of the abnormality and its significance are discussed.

Role of adenine in pathogenesis of Mycoplasma pneumoniae infections of tracheal epithelium

Adenine sulfate and several related compounds were evaluated for their ability to retard the cytotoxic effect which normally accompanies M. pneumoniae infections of hamster tracheal explants. Adenine sulfate, at the 0.01 mM level, was found to exert a significant protective effect. Little or no ciliostasis or loss of cell viability was detectable when organ cultures were infected with 10(7) CFU of virulent M. pneumoniae in the presence of the adenine supplement. Mycoplasmas grew in broth and on plastic surfaces in the presence of adenine, and no significant diminution of growth rate or cell yield was detectable. Organisms adhered to the tracheal epithelial surface regardless of the presence or absence of adenine. When explants were incubated in the presence of 14C-(8)-adenine, rinsed, and then infected with M. pneumoniae, the adenine label could be recovered from the mycoplasmas 20 h after the infection. These data are compatible with the known nucleic acid requirement of mycoplasmas and with a model which ascribes a role for purine/pyrimidine competition and/or depletion in the infective process.

Cytogenetically marked clones in human fibroblasts cultured from normal subjects

Clones of cytogenetically abnormal cells have been recognized in fibroblasts cultured from normal human adult skin. No such clones have been observed in human embryo skin fibroblasts cultured in the same way. Although the culture conditions may have played some part in the emergence of these clones, it is possible that the abnormal cells from which the clones were derived were present in vivo.