Characterization of Basal and Morphine-Induced Histamine Release in the Rat Periaqueductal Gray

Abstract: Previous studies have shown that antinociceptive doses of systemic morphine increase extracellular histamine (HA) levels in the rat periaqueductal gray (PAG), although the cellular origin of basal and morphine-induced HA release in the PAG is unknown. Treatment with α-fluoromethylhistidine (FMH; 100 mg/kg, i.p.), the irreversible inhibitor of histidine decarboxylase, decreased basal HA release by a maximum of 80% and prevented morphine-induced HA release in the PAG. In addition, perfusion of this area with the sodium channel blocker tetrodotoxin (10⁻⁶ M ) decreased basal HA release by a maximum of 57% from baseline levels. When the perfusion medium was modified by substitution of magnesium for calcium, extracellular HA levels in the PAG decreased by a maximum of 72%, and morphine-induced HA release was prevented. Thioperamide (5 mg/kg, i.p.), an H₃ antagonist, increased HA release in the PAG to a maximum of 249% within the first 30–60-min period. Taken together, these results suggest that basal and morphine-induced HA release in the rat PAG have a neuronal origin.     

Studies on the effects of intracerebral actinomycin D implants on estrogen-induced receptivity in rats

Ovariectomized female rats were injected with estrogen and progesterone and actinomycin D was implanted into different brain areas. Implants of actinomycin D inhibited estrogen-induced lordosis behavior when applied to the preoptic region within 12 hr of estrogen treatment regardless of whether the interval between implantation and testing was 29, 38, or 68 hr. Implants 21 hr after estrogen treatment were ineffective. Attempts to localize the site of action showed that implants into the preoptic region were effective even when the implant cannulae did not pierce the ventricles, that implants into the caudate nucleus were ineffective even if the cannulae pierced the lateral ventricles, and that implants into the third ventricle were highly effective in inhibiting lordosis behavior.     

Intersexuality in the mysid Neomysis integer

Intersexuality is described in Neomysis integer (Leach), apparently the first occurrence among the Mysidacea. Seven out of 13,700 specimens examined were masculinized females possessing elongated fourth pleopods, a male secondary sexual characteristic. Each masculinized female appeared to have reproduced as a normal female; there was no evidence of testicular tissue.     

SEEDLING GROWTH STUDIES OF EARLY-RIPENING PEACHES. I. INTERRELATIONSHIP BETWEEN EMBRYO MATURITY,GROWTH SUBSTANCES AND SEEDLING GROWTH

Weaver , Gerald M., and L. Fredric Hough . (Rutgers, The State Univ., New Brunswick, N. J.) Seedling growth studies of early-ripening peaches. I. Interrelationship between embryo maturity, growth substances and seedling growth. Amer. Jour. Bot. 46(10): 718–724. Illus. 1959.—Peach fruits of ‘Raritan Rose’ were harvested 75, 83, 91, 99 and 107 days after full bloom. Embryos were excised, and cultured on artificial media. Growth responses following 8 wk. cold treatment varied considerably with embryo maturity. No correlation existed between seedling survival and the initial responses of shoots. Root growth of 83-day embryos exceeded that of all other stages of maturity. This was reflected in maximum seedling survival and vigor. Initial shoot growth was greatest from embryos harvested at 91 days and at maturity (107 days), but all shoots developed into rosettes which may expand slightly or develop normally from axillary buds. Bioassays of growth substances suggest a strong correlation between early shoot development and auxin concentration. Root growth-responses appeared to be correlated with a promotor-inhibitor balance. The results of wheat coleoptile assays of embryo extracts chromatographed in an isopropanol: ammonia: water solvent (8:1:1) suggest the presence of three growth promotors, in greatest concentration at Rf 0.70, but also at Rf values 0.10 and 0.30. Two growth inhibitors were present in embryo tissue at Rf values 0.27 and 0.96, the former decreasing in concentration with increasing embryo maturity.     

Dihydrolipoamide dehydrogenase from the halophilic archaebacterium Haloferax volcanii: characterization and N-terminal sequence.

Dihydrolipoamide dehydrogenase, a flavin disulfide reductase, has been purified and characterized from Haloferax volcanii. The enzyme is a dimer of relative mass 128,000, with an optimal activity at pH 9.0 in 1 M NaCl. Following reduction with its substrate, dihydrolipoamide, the enzyme is inactivated through covalent bond formation with the trivalent arsenical p-aminophenyl arsenoxide. The amino acid composition and the amino acid sequence of the first 49 residues of the N-terminus have been determined.