Sucrose-Modulated Morphogenesis in Anagallis arvensis L.

Sucrose was found to have a modulating effect on the morphogenesisof Anagallis arvensis L. leaves cultured in a Murashige-Skoogmedium. Root formation and growth seem to be more independentthan other morphogenetic expressions. Roots formed without exogenoussugars at 25°C but sucrose seemed to be necessary at 32and 35°C. Sucrose at 3% improved shoot formation at 25°Cand had an inhibitory effect at 6%concentration and 35°C.Shoot growth (internode length) is inhibited by sucrose concentrationshigher than 3%. Sucrose could also replace light irradiancein regulating shoot and leaf growth. A higher sucrose concentration,than that required for roots and shoots formation, is necessaryfor flower and fruit formation, but sucrose could not replacethe photoperiod requirement for flowering in culture medium. (Received June 17, 1985; Accepted December 24, 1985)     

Amygdala kindled seizure stage is related to altered benzodiazepine binding site density

Benzodiazepine receptor binding was examined in rats at 3 stages of amygdaloid kindling (i.e., initial afterdischarge, Stage 3 and Stage 5) immediately or 24 hr after seizure. 3H-diazepam binding site density (Bmax) was significantly increased 24 hr after Stage 3 and Stage 5 kindled seizures in the hippocampus but not in the amygdala. There were no significant differences in the dissociation constants (KD) between kindled and control rats at any time point examined for either brain region. These results demonstrate that changes in benzodiazepine binding are observed with partial kindled seizures (i.e., Stage 3), indicating that generalized seizures are not prerequisite to increased benzodiazepine receptor site density.     

Improved Method for Isolating Synaptosomes from 11 Regions of One Rat Brain: Electron Microscopic and Biochemical Characterization and Use in the Study of Drug Effects on Nerve Terminal γ-Aminobutyric Acid in Vivo

A procedure is described for the rapid preparation of nerve ending particles (synaptosomes) from 11 regions of one rat brain. The synaptosomal fractions have been characterized by electron microscopy and determination of four marker enzymes, i.e., glutamate decarboxylase (GAD), acetylcholinesterase, succinate dehydrogenase, and glycerol 3-phosphate dehydrogenase. Comparison with a much lengthier standard (Ficoll-sucrose) preparation showed that the synaptosomal yield of the new procedure was substantially better as judged by both morphological evaluation and protein recovery. The improved synaptosome preparation was used for determination of regional gamma-aminobutyric acid (GABA) levels in synaptosomal fractions. The postmortem increase in GABA level during removal and dissection of brain tissue and homogenization and fractionation procedures could be minimized by rapid processing of the tissue at low temperatures and inclusion of the GAD inhibitor 3-mercaptopropionic acid (3-MP; 1 mM) in the homogenizing medium. The addition of GABA (0.2 mM) to the homogenizing medium did not alter the GABA levels in the synaptosomes, indicating that no significant redistribution of GABA occurred during subcellular fractionation in sodium-free media. Synaptosomal GABA levels determined in the 11 rat brain areas showed the same regional distribution as the GABA-synthesizing enzyme GAD. On the basis of these findings, it was suggested that the synaptosome preparation could be used to evaluate the in vivo effects of drugs on nerve terminal GABA. Treatment of rats with a convulsant dose of 3-MP (50 mg/kg i.p.) 3 min before decapitation significantly lowered synaptosomal GABA levels in olfactory bulb, hippocampus, thalamus, tectum, and cerebellum. The 3-MP-induced seizures and reduction of GABA levels could be prevented by administration of valproic acid (200 mg/kg i.p.) 15 min before the 3-MP injection. The data indicate that the improved synaptosome preparation offers a convenient method of preparing highly purified synaptosomes from a large number of small tissue samples and can provide useful information on the in vivo effects of drugs on regional GABA levels in nerve terminals.     

Reactions of sugar nitro-alkenes with acetoacetic esters

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-1-nitro-d-gluco-hept-1-enitol reacts with methyl acetoacetate in an unusual Michael reaction, giving the normal adduct (6), and a bicyclic derivative (9) that arises from quasi-dimerization of the former when a high concentration of the base is used. Acetylation of compound 9 gives the hydroxylamine O-acetate (10).From the reactions of 3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-nitro-d-galacto-hept-1-enitol with ethyl and tert-butyl acetoacetate, the normal adducts (7 and 8) were isolated. The structures of compounds 6 to 10 were established on the basis of their spectral properties (u.v., i.r., mass, and ¹H- and ¹³C-n.m.r.)     

Binding of 5-methoxypsoralen to human serum low density lipoproteins

5-methoxypsoralen (5-MOP) binds to human serum low density lipoproteins (LDL) according to a two-step process. Scatchard analysis of the first step yields K = 1.4 × 10⁵ M^?1 and 4 binding sites. It involves the LDL apoprotein. The second step corresponds to a solubilization, in the lipidic core, of ? 45 molecules of 5MOP per LDL molecule. It is accompanied by a large blue shift of the 5MOP fluorescence. The ability of LDL to bind 5MOP and to carry it into various cells may explain some biological effects sometimes encountered during PUVA therapy.     

Purification of the 22000- and 20000-mol.wt. forms of human somatotropin and characterization of their binding to liver and mammary binding sites.

Quantitative data concerning the binding of 22000-mol.wt. human somatotropin and its 20000-mol.wt. variant are described using pregnant-rabbit liver and mammary-gland receptors. The purification and the complete chemical characterization of both human somatotropin and its 20000-mol.wt. variant is also presented. Contamination of the 20000-mol.wt.-variant preparation by 22000-mol.wt. hormone was found to be 0.5% by weight as measured in radioimmunoassay using monoclonal antibody. Labelling of human somatotropin and its 20000-mol.wt. variant using the Iodogen method is described as well as the characterization of the binding to pregnant-rabbit liver and mammary-gland receptor preparations. The maximum binding capacity of the 125I-labelled human somatotropin was between 50 and 60% to liver particulate receptor, whereas that of the 20000-mol.wt. variant was 30%. The specificity of binding of both forms to rabbit hepatic and mammary-gland receptor was found to be similar for both proteins in the same system. The affinity constants and capacity were respectively 0.7 X 10(10)M-1 and 815 fmol/mg of protein for human somatotropin and 0.6 X 10(10)M-1 and 1.250 fmol/mg of protein for the 20000-mol.wt. variant. These data suggest that both proteins behave as partial agonists to the receptors studied.     

Amber Mutants of Bacteriophages T3 and T7 Defective in Phage-directed Deoxyribonucleic Acid Synthesis

Amber mutants of the related phages T3 and T7 were isolated and tested for their ability to restore-as the wild type does-thymidine incorporation in ultraviolet (UV)-irradiated, UV-sensitive, nonpermissive host bacteria (Escherichia coli B(s-1)). Most amber mutants had this ability. However, in both T3 and T7, mutants unable to promote thymidine incorporation under these conditions were found and classified into two well-defined complementation groups: T3DO-A and T3DO-B, T7DO-A and T7DO-B. Infection of B(s-1) cells with representatives of groups DO-A had the following characteristics: (i) phage-directed uridine uptake in UV-irradiated cells was reduced to less than 20% of normal; (ii) breakdown of host deoxyribonucleic acid (DNA) was delayed and incomplete; (iii) no serum-blocking antigens appeared; (iv) no cell lysis occurred; (v) the ability to exclude the heterologous wild type was impaired. Amber mutants of the DO-B groups, infecting B(s-1), were able to: (i) promote an efficient phage-directed uridine uptake in UV-irradiated cells; (ii) bring about rapid breakdown of host DNA; (iii) synthesize serum-blocking antigens; (iv) lyse the host cells, generally after the normal latent period; (v) exclude efficiently the heterologous wild type. Although physiological similarities between the respective DO-A mutants or DO-B mutants of T3 and T7 were evident, no physiological cross-complementation occurred, and genetic crosses gave no evidence of genetic homologies between groups of T3 and T7.     

Talar articular facets (facies articulares talares) in human calcanei

The variations of the talar articular facets in 176 calcanei were studied and classified. Three types were considered: type A = calcanei with two articular facets for the talar head, with four subtypes; type B = calcanei with one articular facet for the talar head, and two subtypes, and type C = unique articular facies in the superior surface of the calcaneus for the talus. We found 53% (94 cases) type B calcanei and 46% (82 cases) type A calcanei. No calcanei of type C were seen.