[Inhibition of biological methylations by t,t-farnesylacetone, a constituant of the androgenic gland of the male crab, Carcinus maenas]. / Inhibition de méthylations biologiques par ia t,t-farnésylacétone, constituant de la glande androgène du crabe mâle Carcinus maenas.

t, t-farnesylacetone 1 and hexahydrofarnesylacetone 2 have been previously identified in extracts from the androgenic gland of the male Crab Carcinus maenas. These compounds inhibit in vitro the methylation of E. coli B tRNA and of Calf thymus histones with S-adenosylmethionine methyl-14C as methyl donor and methylases from Crab testis. Rat liver or a 1-adenine methylase from a Mouse plasmocytoma (1 is approximately 200 times more active than 2).

[Methylation of tRNA in Carcinus maenas gonadal cultures: inhibition by purified androgenic gland extract]. / Méthylation du tRNA dans des cultures de gonades de Carcinus maenas: inhibition par un extrait purifié des glandes androgènes.

Subcultures of ovaries and testis of the crab Carcinus maenas have been performed in the presence of L-[Me-14C]methionine. Introduction in the medium of a chromatographically-purified liposoluble fraction from the androgenic glands of the same animal inhibits the biological methylation of the tRNA of the ovaries by 62%. The inhibition of methylation of five individual bases varies from 45% to 84%. No inhibition of tRNA methylation is observed under the same conditions with testis subcultures.

6,10,14-Trimethylpentadecan-2-one and 6,10,14-trimethyl-5-trans, 9-trans, 13-pentadecatrien-2-one from the androgenic glands of the male crab Carcinus maenas.

2 C18 isoprenoid ketones, hexahydrofarnesylacetone (1) and farnesylacetone (2) have been identified for the first time in lipid extracts from the androgenic glands of the male crab Carcinus maenas, using coupled gas chromatography-mass spectrometry. The 2 compounds prepared by synthesis, are biologically active, inhibiting the incorporation of 3H-leucine in Crustaceans ovaries subcultures.

[Biological methylations in the crab Carcinus maenas; in vitro inhibition by a fraction purified from androgen gland extracts]. / Méthylations biologiques chez le crabe Carcinus maenas; inhibition in vitro par une fraction purifiée extraite des glandes androgènes

Extracts from muscles, testis, seminal vesicles and ovaries of the Crab, Carcinus maenas, have been studied in vitro, in presence of [14C]-methyl S-adenosylmethionine, with an E. coli tRNA as methyl acceptor. The highest level of methylases is found in the testis. It has been reported previously that a purified fraction extracted from the androgenic glands of Carcinus maenas inhibits the vitellogenesis in ovaries. We now show that the same fraction inhibits tRNA methylation in an extract of testis as methylase; a 50% inhibition is obtained with about 10 mug of a purified fraction corresponding to 15 glands. With an enzymatic preparation from the ovaries, a 50% inhibition of the tRNA methylase is observed with the purified extract from 4 glands.

[Ciguatera: neurophysiological demonstration of toxicity of several ciquatoxic fractions]. / Ciguatera: mise en évidence neurophysiologique de la toxicité de diverses fractions ciguatoxiques

Raw extracts from one Polynesian, frequently ciguatera-inducing fish were submitted to fractional distillation by means of a chromatographic process using a silicic acid column. Three out of the seven fractions split this way exhibited either anticholinesterasic properties, or directly toxic properties at the muscle-cell level: fraction 5, which is not antagonized by atropine, presumably accounts for this direct action, as it competes with calcium at membrane sites. Fraction 6 appears to be more specially responsible for the anticholinesterasic action. It revealed a quaternary ammonium ion in its 6-2 sub-fraction. Fraction 7 shows the same properties as fraction 6, but on a smaller scale.