Heterogeneity in the biochemical characteristics of red blood cell hypoxanthine-guanine phosphoribosyl transferase from two unrelated patients with the lesch-nyhan syndrome

HGPRT from patient M. Y. (enzyme level 0.1% normal) retained a normal apparent K _m both for PRPP and for hypoxanthine and was inhibited by its product. The enzyme was, however, unstable at 50 C (43% of activity remaining after 1 hr) when compared with normal controls (81% of activity retained). The enzyme from patient J.D. (enzyme level 0.005% normal) was also unstable (32% of activity retained). Unlike for M.Y., however, all the other characteristics studied were also altered. The enzyme activity was enhanced rather than inhibited by its product (IMP), and the apparent K _m (hypoxanthine) could not be calculated due to the sigmoid nature of the curve. Obviously, there is marked heterogeneity in the nature of the biochemical lesion responsible for the Lesch-Nyhan syndrome in these patients, and this is discussed.This research was supported by the Medical Research Council of Canada (a Postdoctoral Fellowship to B.J.R. and Grant No. MA-4061 to J.L.H.) and by the Children's Hospital Research Foundation.     

Diet does not affect intercolonial fighting in Leptothoracine ants

Summary An experiment examined the effects of diet on brood rearing in colonies ofLeptothorax ambiguus andL. longispinosus and on fighting between colonies of the two species. Colonies fedDrosophila and honey reared more pupae than colonies fed the Bhatkar and Whitcomb (1970) diet. However, diet had no effect on intercolonial fighting.