Isoelectric focusing of human red cell phosphoglucomutase

Summary A total of 637 individuals from the rural village of Keneba in The Gambia, West Africa, have been typed for red cell PGM using isoelectric focusing (pH 5–7) in polyacrylamide gels. Eight different phenotypes have been detected. The frequency of the four alleles at the PGM₁ locus was found to be PGM ₁ ¹⁺ 0.795, PGM ₁ ^1- 0.053, PGM ₁ ²⁺ 0.133, and PGM ₁ ^2- 0.019. A study of the PGM phenotypes in 89 families confirmed the simple Mendelian codominant inheritance of the four alleles. Comparative population data suggest that red cell PGM typing by isoelectric focusing might prove to be a useful genetic marker in anthropological studies.     

Allogeneic restriction of acquired antimicrobial resistance in the rat.

Allogeneic restriction of acquired antimicrobial resistance was demonstrated by infusing Listeria-immune thoracic duct lymphocytes (TDL) into syngeneic, semisyngeneic, or allogeneic recipients that had been infected i.v. with Listeria monocytogenes (LM). Syngeneic and semisyngeneic recipients enjoyed a high level of protection (3 to 5 log10 reduction in viable organisms within 64 hr, whereas allogeneic recipients were poorly protected (0.5 to 2.5 log10 reduction). Sharing one haplotype between TDL-donors and challenged recipients resulted in a 4- to 8-fold increase in the level of resistance transferred. Histoincompatibility reactions could be excluded as a cause of the observed allogeneic restriction. Therefore, it is likely that LM-immune TDL are unable to respond efficiently to the antigens of this organism in an allogeneic environment. But allogeneic immune TDL do confer a low level of protection that cannot be ascribed to B cell activity nor to GvH and/or HvG reactions. Evidence is provided that the modest protection afforded by allogeneic lymphocytes is conveyed by the same T cell subset that operates with much higher efficiency in genetically related rats.     

Long-term anaesthesia with alfentanil and midazolam for lung transplantation in the dog

An anaesthetic regime was developed for lung transplantation in the dog using a continuous infusion of alfentanil and midazolam. This combination of agents provided excellent analgesia and also produced loss of consciousness. Cardiovascular stability was well maintained over a 24-h period of anaesthesia following lung transplantation. Although no animals were allowed to recover from anaesthesia in the present series, the regime described is likely to be suitable for recovery anaesthesia, particularly since both of the agents used can be reversed with specific antagonists.     

THE BLOCKAGE OF AXOPLASMIC FLOW OF PROTEINS BY COLCHICINE AND CYTOCHALASINS A AND B

Abstract— Colchichine blocks axoplasmic flow of proteins in chicken sciatic nerve. The slow component is more effectively blocked than the fast. The colchicine effect on slow flow is independent of the time delay between colchicine injection and that of the [¹⁴C]-leucine used to measure flow, over a period extending from 2 h after to 9 days before the leucine. It is still effective, but to a lesser degree, after a period of 27 days. There is little effect on the fast component when the colchicine is administered after leucine. When given before leucine the effect is not pronounced up to a time interval of 1 day. Maximum blockage was obtained with longer intervals of up to 27 days. These results are discussed in relation to the involvement of the microtubules in both slow flow and rapid flow.
The effect of both cytochalasins A and B on slow and rapid protein flow has also been studied. Neither drug had any significant effect on slow flow. Cytochalasin A reduced the amount of protein flowing at the rapid rate to a small extent when administered 2 h before [¹⁴C]leucine. Cytochalasin B also caused a similar reduction and this effect was independent of dose over the ranges of doses used. The cytochalasin B diminished the incorporation of amino acid into protein in the spinal cord and it has been concluded that these results are due to a membrane effect which reduces uptake of amino acid rather than a direct effect on neurofilaments in the axons.     

Size-selective oviposition by parasitoids and the evolution of life-history timing in hosts: fixed preferences vs frequency-dependent host selection

The influence of size-selective oviposition behaviour by parasitoids on the evolution of life-history timing in their hosts was examined using an optimization model of a two-stage life history similar to a genetic algorithm. Host populations with varying durations of early-larval development were subjected to selection in scenarios where parasitoids had fixed preferences for oviposition on late-stage larvae, or those where parasitoid attack was dependent on the relative frequencies of the two life stages present in the population. Fixed preference for oviposition on late-stage larvae caused positive directional selection on the duration of early-larval development. Surviving individuals remained for as long as possible in the first stage of development in order to avoid parasitoid attack. Frequency-dependent parasitoid attack, in contrast, caused maintenance of variation in the duration of early-larval development. The influence of the fitness payoffs of different life stages on the plasticity of size-selective oviposition behaviour is discussed, as are possible implications of the model results for parasitoid-host population dynamics.