Anti-leucocyte antibodies and embryonic mortality in embryo transferred cows

Cows carrying unrelated transferred embryos (ET) produced anti-leucocyte serum antibodies (aLA) more often than cows carrying their own embryos. Cows carrying the ET showed a higher frequency of cytotoxic reactions against leucocytes from 40-60 randomly chosen cows than individuals carrying their own embryos. The percentage of animals with aLA was higher in cows carrying their second or third transferred embryo than in those with their first transferred embryo. There was no change in the frequency of cytotoxic reactions with repeated pregnancies from transferred embryos. There was no difference in the toxicity of aLA in normal pregnant cows and those carrying transferred embryos. Embryonic mortality (EM) of 35, 73 and 88% was noted during pregnancies from the first, second and third successful ET, respectively. Mortality of 48% occurred in the first pregnancy following an unsuccessful ET. Embryonic mortality of 31% occurred in cows simultaneously carrying their own and a transferred embryo. A direct relationship between the presence of aLA and EM in recipients was not proved. Other fertility problems may lead to EM in cows subjected to repeated transfer of foreign embryos.     

Further evidence for a silent allele in the transferrin locus of the horse

A silent allele in the transferrin locus (Tf) was observed in a Thoroughbred mare and in five of her offspring from three different matings. Evidence for the silent allele was obtained by quantitative immunodiffusion studies.     

Use of partially engorged female ticks as laboratory animals in microbiological research

Abstract. Partially engorged female ticks were used as laboratory animals in microbiological research. The ticks, which were inoculated intracoelomally, became a convenient substrate for the detection of viruses, rickettsiae and protozoal parasites. This research concerned the isolation of newly recovered micro-organisms, the study of development, structure and distribution of microbial agents in ticks, and the study of their interaction with other pathogens or symbionts during mixed infection in a tick body. The isolation and maintenance of Rickettsiella phytoseiuli , the organism not of tick-borne origin, was achieved. For use in Central Europe the tick Dermacentor reticulatus is recommended for the above investigations.     

Exposure of N-acetylglucosamine decreases early in dexamethasone-induced apoptosis in thymocytes, demonstrated by flow cytometry using wheat germ agglutinin and pokeweed mitogen.

In the present paper we describe changes in the exposure of oligosaccharides containing N-acetylglucosamine (Glc-NAc) during apoptosis of mouse thymocytes. The structures containing this sugar were probed with fluorescein isothiocyanate-labelled lectins, wheat germ agglutinin and pokeweed mitogen in flow cytometric assays. Both lectins bind to structures containing Glc-NAc. The present report describes experiments in which two different dual-staining techniques were used to simultaneously identify apoptotic cells and measure their lectin exposure. In these experiments, we observed an early and substantial decrease in the exposure of Glc-NAc-containing structures associated with the onset of apoptosis, before or simultaneously with phosphatidylserine exposure. This was followed by an increase in the exposure of Glc-NAc-containing structures after longer incubation times, when a large proportion of cells was demonstrated to have fragmented DNA. These results provide evidence for major changes in the structure of plasma membrane oligosaccharides during apoptosis. The initial decrease may be a by-product of the hydrolysis of glycosphingolipids to yield ceramide for apoptotic signalling or a deliberate process related to the removal of cell adhesion signalling structures, associated with the separation of the apoptotic cell from its neighbours. The later increase in Glc-NAc-containing structures may be the result of the incorporation of internal membranes into the plasma membrane or a deliberate production of prophagocytic signals by a still-functioning Golgi apparatus.