Search PubMed⌕ Search

Biomedical subjects

M Barbier

Publications and source records attributed to M Barbier.

At least 37 records · Page 2Linked to original sources
PubMed1979

The diversity of marine sterols and the role of algal bio-masses; from facts to hypothesis.

Modern analytical methods have revealed the great variety of marine sterols, which possess many different side chains and unsaturation patterns. Such biochemical transformations require well-defined mechanistic pathways, and there must be some 'Raison d'Etre' for a situation which has withstood evolution and adaptive changes. However, in this area, insufficient and sometimes not very substantial experimental work has made it difficult to see correlations, and hence to form a solid hypothesis. A review is now presented in which the molecules dissolved in sea water, or found in marine organisms are considered with particular reference to algal production, and to the bio-ecological significance of the main sterols.

Animals↗
PubMed1979

[In vitro inhibition of tRNA methyltransferases by queen substance, a pheromone of queen honeybees].

The Queen Substance 1, a pheromone of the queen Honeybee Apis mellifica is an in vitro inhibitor of E. coli B tRNA methylations. This activity is not specific of the methylase source, as inhibitions have been observed with preparations from queen honeybee ovaries, Rat liver or a Mouse plasmocytoma 1-adenine methylase. These results, together with preceding ones concerning t, t-farnesyl-acetone 3, are discussed.

Animals↗
PubMed1977

[Fucosterol-24,28-epoxide, an intermediate in the oxidative biodegredation of fucosterol to cholesterol by the cricket (Locusta migratoria (R. and F.)].

beta-Sitosterol 1 is metabolised to cholesterol 5 by phytophagous insects. It has been previously shown that fucosterol-24,28 epoxide 3 is transformed into 5 in Locusta migratoria, desmosterol 4 being an intermediate. It is now established that locusts transform [3-3H]fucosterol propionate into the corresponding labelled epoxide 3, recovered as such or as an oxazoline derivative 11.

Animals↗
PubMed1977

[Inhibition of biological methylations by t,t-farnesylacetone, a constituant of the androgenic gland of the male crab, 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).

Animals↗
PubMed1977

[Methylation of tRNA in Carcinus maenas gonadal cultures: inhibition by purified androgenic gland extract].

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.

Animals↗
PubMed1977

[Forefoot reconstruction. The frequency and importance of the toe and metatarsal formula (author's transl)].

The forefoot reconstruction as a routine treatment, is increasing in significance, not only in treating polyarthritic patients, but also after numerous surgical failures in treating halux valgus or hammer toes. Far from being a simple operation, the reconstruction requires an exact knowledge of the physiopathology of the foot. Special attention should be given to the digital and metatarsal formula. Based on an analysis of 200 forefoot reconstructions, the advantages and the disadvantages of the various methods are discussed. For the first time in the German speaking countries, the frequency of occurrences of the different digitial and metatarsal formulas has been compiled in tables from an examination of 500 forefeet.

Adult↗
PubMed1977

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.

Animals↗
PubMed1976

[The track pheromone of the termite Schedorhinotermes lamanianus (Sjöstedt)].

The trail pheromone of the African Termite Schedorhinotermes lamanianus has been investigated. It consists of two active components: an unsaturated fatty alcohol probably in C14 and a corresponding esterified fraction. The interconversion of the two by acetylation-saponification has been demonstrated. However, it is not yet known whether the ester occurs naturally as an acetate or not. A carbonyl derivative, biologically inactive, has also been isolated; its reduction with NaBH4 leads to an active alcohol of same Rf value as the preceding one.

Animals↗
PubMed1976

[The marine diatom Chaetoceros simplex calcitrans Paulsen and its environment. Effects of light and ultraviolet irradiation on the biosynthesis of fatty acids].

In continuous light (24/24 h) or with a 12/24 h photophase, the title diatom synthesizes the same total amount of fatty acids. But the photophase considerably increases some of them: C 18:2 (+535%), C 17:2 (+422%), C 17:0 (+97%), C 19:0 (+97%), C 17:1 (+72%). Adding ultraviolet irradiations to the two mentioned conditions of light also increases the total amount of fatty acids and induces the biosynthesis of the C 20:0. The results are discussed.

Animals↗
PubMed1976

[Biological methylations in the crab Carcinus maenas; in vitro inhibition by a fraction purified from androgen gland extracts].

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.

Animals↗
PubMed1975

[Biosynthesis of phorcabiline, blue-green biliary pigment of Actias selene (Lepidoptera, Attacidae)].

The blue-green bile pigments of Actias selene (Attacidae) have been investigated at different stages of its development. Coproporphyrinogen-14-C, protoporphyrin-IX3-H, and pterobilin-14-C, injected to larvae are metabolised into phorcabilin I, the main neopterobilin in this animal. It is concluded that phorcabilin I is a bile pigment of the IX gamma series and that pterobilin is its direct precursor. A method for the preparation of labelled protoporphyrin from quail egg-shell is reported.

Age Factors↗
PubMed1975

Transfer of the methyl group of methionine to choline and to tRNA in the honeybee Apis mellifica L.

Contrary to some previous reports on the absence of biological transmethylation reactions in some insect species, the transfer of the methyl group of methionine-methyl 14C leading to choline and to methylated bases in tRNA was shown in the honeybee Apis mellifica. The addition of antibiotics to the food of the insect does not diminish the incorporation of radioactivity, proving that intestinal bacteria are not responsible for the methylation reactions observed.

Animals↗
PubMed1975

[Polychromatism in eggshell or domestic quail (Coturnix coturnix japonica). IV. Porphyrin biosynthesis in uteri of phenotypes belonging to the dominant form].

With the introduction of delta-aminolevulinic acid, uterin extracts, in vitro, can synthesize porphyrins (uroporphyrin, 62%; coproporphyrin, 27%; and protoporphyrin, 11%). At the stage where the uterus contains a white egg, various phenotypes in the dominant form are capable of synthesizing with the introduction of delta-aminolevulinic acid, the same quantity of porphyrins. These results are interpreted, assuming the existence of differences in the activity of the enzymes involved during the laying cycle.

Aminolevulinic Acid↗