Dependence of gibberellic acid-induced dark germination of lettuce seed on RNA synthesis

Gibberellicacid-induced dark germination of Grand Rapids lettude seed was completely inhibited by 6-azauracil and partly by 2-thiouracil. Other inhibitors of nucleic acid and protein synthesis used were without effect. Inhibition of gibberellic acid-induced dark germination was reversed by uracil but not by thymine, deoxycytidine and orotic acid. The results suggest that gibberellic acid-induced dark germination is dependent on RNA synthesis and not on DNA synthesis.Gibberellic acid-induced lettuce hypocotyl growth was inhibited by all the inhibiters of nucleic acid and protein synthesis used, including actinomycin D, puromycin, chloramphenicol and p-fluorophenylalanine.

Inhibition of lettuce seed germination and seedling growth by antimetabolites of nucleic acids, and reversal by nucleic acid precursors and gibberellic acid

Germination of White Paris lettuce seeds is inhibited by 2-thiouracil up to 24 hours. This inhibition is reversed by RNA precursors only. Seedling growth of lettuce is inhibited by 2-thiouracil and 5-fluorouracil; and white the effect of 2-thiouracil is counteracted by RNA precursors, inhibition due to 5-fluorouracil is not reversed significantly by any nucleic acid precursors. Possibly 2-thiouracil controls germination and seedling growth by interfering with RNA synthesis, while the effect of 5-fluorouracil is non-specific.In the presence of gibberellic acid, 5-fluorouracil and 2-thiouracil are relatively ineffective in causing inhibition of hypocotyl growth. Mechanism of gibberellic acid action remains obscure.

Repellency of Skin-Surface Lipids of Humans to Mosquitoes

Skin lipids obtained from the washings, in acetone or diethyl ether, of the foreheads or arms of humans are very repellent to female Aedes aegypti when evaluated in a dual-port olfactometer. By means of thin-layer chromatography, the repellent substances can be separated from nonrepellent material also present in skin lipids.

EVIDENCE FOR ‘LIPOPEPTIDE’, PHOSPHATIDYLETHANOLAMINE, AND PHOSPHATIDYLCHOLINE IN EXCISED TOMATO ROOTS

Evidence is presented for the existence of ‘lipopeptide’ in lipid extracted with ethanol: ether (3:1 v/v) from excised tomato roots grown in sterile culture. The amino acids released by acid hydrolysis of ‘purified’ lipid were identified by co-chromatography and color reaction with acidic and neutral ninhydrin reagent. They are cysteic acid, serine, glycine, aspartic acid, glutamic acid, glutamine, alanine, valine, leucine and/or isoleucine, and probably methionine and tyrosine. Arginine was detected on some chromatograms. Four unknown substances, three of which are ninhydrin-sensitive, were detected.Paper chromatographic fractionation of water-soluble substances in methanolyzates of 'purified' lipid failed to yield a distinct 'peptide' fraction but fractions high in ‘peptide’ also contained two of the four unknown substances.Glycerylphosphorylethanolamine and glycerylphosphorylcholine were detected in the methanolyzates. Glycerylphosphorylserine was not detected.