Does high-mobility-group non-histone protein HMG 1 interact specifically with histone H1 subfractions?

The interaction of the non-histone chromosomal protein HMG (high-mobility group) 1 with histone H1 subfractions was investigated by equilibrium sedimentation and n.m.r. sectroscopy. In contrast with a previous report [Smerdon & Isenberg (1976) Biochemistry 15, 4242--4247], it was found, by using equilibrium-sedimentation analysis, that protein HMG 1 binds to all three histone H1 subfractions CTL1, CTL2, and CTL3, arguing against there being a specific interaction between protein HMG 1 and only two of the subfractions, CTL1 and CTL2. Raising the ionic strength of the solutions prevents binding of protein HMG 1 to total histone H1 and the three subfractions, suggesting that the binding in vitro is simply a non-specific ionic interaction between acidic regions of the non-histone protein and the basic regions of the histone. Protein HMG 1 binds to histone H5 also, supporting this view. The above conclusions are supported by n.m.r. studies of protein HMG 1/histone H1 subfraction mixtures. When the two proteins were mixed, there was little perturbation of the n.m.r. spectra and there was no evidence for specific interaction of protein HMG 1 with any of the subfractions. It therefore remains an open question as to whether protein HMG 1 and histone H1 are complexed together in chromatin.     

Immunochemical studies of high mobility group non-histone chromatin proteins HMG 1 and HMG 2

Sera were raised to non-histone chromatin proteins HMG 1 and HMG 2. Immunoperoxidase staining localised these proteins on chromosomes during mitosis and indicated a cell cycle-related variation in these proteins during interphase. Some species differences in HMG 1 and HMG 2 were also observed.     

Species density and associations in Caribbean reef corals

The density of scleractinian corals on portions of two reefs in the Grenadine Islands, W. I. has been investigated by direct observation by SCUBA divers. Grid, transect, and random quadrat methods were compared with total samples to determine the precision and accuracy of these techniques. Transect methods were generally satisfactory provided at least 15% of a 400 m² total grid area was included in the sample. The data strongly indicated clumped distributions of all species, although numerical analysis does not indicate the distinct zones reported by other workers. Species associations based on Jaccard's coefficient and cluster analysis showed possible similarities in physical requirements, although few strong associations were found. Data based on 4 m² quadrats generally provided a more reliable estimate of species associations than did data based on 1 m² quadrats. It is suggested that surveys of these reef types may be better based on a number of parallel transects rather than a single transect, and that well-defined zones are more likely to be the exception than the rule.     

Relationships between platelet and plasma monoamine oxidase,plasma dopamine-B-hydroxylase,and urinary 3-methoxy-4-hydroxy phenylglycol

The activity of dopamine-B-hydroxylase in blood has recently been demonstrated to be under genetic control and to correlate closely with urinary catecholamine excretion. The results of the present study did not demonstrate any relationship between a major catecholamine metabolite in urine, 3-methoxy-4-hydroxy phenylglycol, and dopamine-B-hydroxylase activity in plasma, monoamine oxidase activity in platelets, or monoamine oxidase activity in plasma. Differences in the origin of urinary catecholamines and urinary 3-methoxy-4-hydroxy phenyglycol may be responsible for these divergent results.     

Mode of formation of cholesta-5,7-dien-3β-ol from cholest-5-en-3β-ol by larvae of Calliphora erythrocephala

1. The conversion of cholest-5-en-3beta-ol (cholesterol) into cholesta-5,7-dien-3beta-ol by axenic Calliphora erythrocephala larvae was demonstrated. 2. The transformation is probably direct (Delta(5)-->Delta(5,7)) and does not involve a Delta(0) intermediate (Delta(5)-->Delta(0)-->Delta(7)--> Delta(5,7)). 3. Delta(7)-bond formation involves the stereospecific elimination of the 7beta hydrogen atom. 4. The relative amounts of free and esterified sterols were determined in larvae grown on cholesterol as sole sterol source and on 5alpha-cholestan-3beta-ol supplemented with minimal amounts of cholesterol. 5. The significance of the results is assessed in relation to the probable role of cholesta-5,7-dien-3beta-ol as an intermediate in the biosynthesis of ecdysones.     

Unusual lesion morphology and skin test reaction for Mycobacterium avium complex in macaques

Three rhesus (Macaca mulatta) and one cynomolgus (M. fascicularis) monkey were euthanized because of positive reactions to intradermal tests with mammalian Old Tuberculin (mOT). All the animals had gross or microscopic lesions consisting of unitized macro- or microgranulomas with central necrosis, involving the lung or mesenteric lymph nodes. Small numbers of acid fast organisms were demonstrated in the lesions. Mycobacterium avium complex, serotype 2 was isolated from three of the cases. The cases were unusual because the lesion morphology and mOT hypersensitivity were more typical of mammalian tuberculosis than avian tuberculosis in monkeys.