Isolation of microsatellite loci in the Capricorn silvereye,Zosterops lateralis chlorocephalus (Aves: Zosteropidae)

The Capricorn silvereye (Zosterops lateralis chlorocephalus) is ideally suited to investigating the genetic basis of body size evolution. We have isolated and characterized a set of microsatellite markers for this species. Seven out of 11 loci were polymorphic. The number of alleles detected ranged from two to five and observed heterozygosities between 0.12 and 0.67. One locus, ZL49, was found to be sex‐linked. This moderate level of diversity is consistent with that expected in an isolated, island population.     

Determinants of growth-promoting activity reside in the A-domain of insulin-like growth factor I

A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins.     

Repair of single nucleotide DNA mismatches transfected into mammalian cells can occur by short-patch excision

Synthetic DNA linkers containing a single mismatched nucleotide (C:A) are repaired without bias at high efficiency when introduced into mammalian cells on a SV40 shuttle vector. From the pattern of repair in vectors containing multiple linkers, it appears that DNA synthesis following mismatch excision can replace a length of DNA as short as 40 nucleotides. Furthermore, results from the introduction of linker molecules containing combinations of single-strand nicks suggest that transient unsealed nicks do not drive the direction of mismatch repair in mammalian cells, as has previously been proposed.     

18-Substituted steroids. Part 15. 6 beta-Hydroxylation of aldosterone by liver

6 beta-Hydroxyaldosterone and 6 beta-hydroxy-17-isoaldosterone, characterized by high-field NMR studies, are among the major polar metabolites formed from aldosterone by incubation with rat liver slices or microsomal fraction. It is uncertain at present whether the 17-iso product results from an enzymatic or a chemical inversion of configuration. Periodate degradation of the 6 beta-hydroxyaldosterone gave 6 beta-hydroxyaldosterone gamma-lactone, identical with a synthetic sample.     

Behavioural, biochemical and histological effects of trimethyltin (TMT) induced brain damage in the rat.

To assess the nature and extent of behavioural, biochemical and histological changes induced by trimethyltin (TMT), rats were treated with a single injection of TMT over a dose range of 6, 7 and 8 mg/kg i.p. Behavioural observations were performed at a minimum of 21 days after the administration of TMT. The behavioural consequences of TMT were hyperactivity in the open-field test, increased locomotor activity and deficits in passive and active avoidance behaviour, T-maze alternation and Morris Water Maze behaviour. The behavioural changes were dose dependent and were accompanied by a degree of pathological damage to the hippocampal pyramidal cells which was particularly apparent at the highest dose. The main biochemical effects of TMT involved deficits in the serotonergic and GABA-ergic systems and a decrease in M1 and M2 binding sites in the hippocampus. These results suggest that the toxic interaction of TMT with the hippocampus and other limbic brain regions may be responsible for its effect on learning and memory.     

Structural basis of anthracycline selectivity for unilamellar phosphatidylcholine vesicles: an equilibrium binding study

Fluorescence anisotropy titration was used to determine the equilibrium binding affinities of several anthracycline antitumor antibiotics for sonicated dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) vesicles at 27.5 degrees C. Eight daunomycin analogues, all differing from the parent by one structural change in the aglycon portion of the molecule, as well as four anthracycline congeners modified in the amino sugar were studied. Double-reciprocal plots were used to determine overall binding affinities (K). It was shown that structural changes in both the aglycon and amino sugar portions of the daunomycin molecule strongly modulated K values for DMPC and DPPC bilayers. For modifications in the aglycon portion of an anthracycline, a correlation between drug hydrophobicity and membrane affinity was observed. The number of binding sites per phospholipid molecule (n) and the apparent association constant (Kapp) where K = nKapp, were determined at several temperatures for adriamycin, daunomycin, and carminomycin. The n values were found to be independent of temperature for fluid-phase DMPC or solid-phase DPPC bilayers. The Kapp values (25 degrees C) ranged from (0.82-4.4) X 10(5) M-1 for DMPC vesicles to (4.4-7.3) X 10(5) M-1 for DPPC vesicles. Although the Kapp values for the three drugs were similar for a particular bilayer, major differences were noted in the values of n and, therefore, in the overall vesicle affinities (nKapp). van't Hoff plots showed that anthracycline binding was exothermic; in all cases but one binding was accompanied by a decrease in entropy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Preservation of ischemic myocardial tissue with an antagonist of vasoconstrictor eicosanoids

A new antagonist of the vasoconstrictor eicosanoids, L-640,035, was studied in a standardized model of myocardial ischemia (MI) in anesthetized cats. This eicosanoid antagonist was not found to exert any overt hemodynamic action in cats subjected to a sham myocardial ischemia protocol. However, the antagonist markedly reduced the S-T segment of the electrocardiogram when administered 30 min after permanent occlusion of the left coronary artery. Moreover, circulating activities of the marker enzyme creatine kinase (CK) were markedly attenuated by L-640,035 3-5 h after the onset of MI. This was verified by cardiac biopsies 5 h post-MI since myocardial CK activities decreased much less in treated MI cats than in MI cats receiving only the vehicle for L-640,035 (i.e., ethanol). The active metabolite of the antagonist in biological fluids (i.e., L-636,499) markedly antagonized the vasoconstrictor actions of endoperoxide and thromboxane analogs, but not of noneicosanoids in isolated perfused coronary arteries.