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 per cent inhibition is obtained with about 10 μg of a purified fraction corresponding to 15 glands. With an enzymatic preparation from the ovaries, a 50 per cent inhibition of the tRNA methylase is observed with the purified extract from 4 glands.     

Studies of soluble rat liver mitochondrial acid ATPases: II. Structural and immunological properties of ATPase 1

We described previously the existence of a soluble ATPase activity in rat liver mitochondria [1]. The purification and catalytic properties have been described [2]. In a continuation of these experiments, we have studied the immunologic and structural properties of one molecular form of this enzyme: ATPase I.We have prepared the antiserum anti-ATPase I and demonstrated the purity of our enzyme preparation by immunodiffusion and immunoelectrophoresis. An immunohistochemical method also confirmed the localization of ATPase I in the soluble fraction of mitochondria.The molecular weight of ATPase I was measured by G 100 Sephadex gel filtration and was found to be 18,400; electrophoresis on polyacrylamide gels gave a value of 18,600. The pHi of ATPase I was found to be 7,2.Amino acid analysis showed high amounts of aspartic acid, glutamic acid, serine and glycine. The molecular weight calculated from the total amino acid residues was found to be 17,000.Alanine is the NH2 terminal amino acid.The peptide maps obtained after degrading ATPase I with cyanogen bromide or trypsin are in accordance with the methionine, lysine and arginine residues we found in the ATPase I molecule.ATPase I does not appear to be a glycoprotein.     

Presence de pollens d'Hamamelis (Hamamelidaceae,Angiospermae) dans le pliocene du Sud de la France

Pollen-analysis shows the presence of the genus Hamamelis in the pliocene flora of southern France. It contributesto the knowledge of the past distribution of taxa which are now extinct in western Europe.     

L'espece Pecopteris simoni (Zeiller, 1886–1888)sunonyme posterieur de Palaeoweichselia defrancei (Brongniart, 1828)

Recent examination of the type specimen of Pecopris simoni ZEILLER (1) leads to the conclusion of the identityof that species with Palaeoweichselia defrancei (BRONGNIART) (2), which is also confirmed by the stratigraphic occurence.     

Carbohydrate-peptide linkage in glycoproteins

The secondary structure of the peptide segment around the carbohydrate-peptide linkage in glycoproteins was predicted by using the Chou and Fasman determination. Such a study was carried out for 9 O-glycosidically linkages and 28 N-glycosidically linkages. In the case of O-glycosidically linkages, the residue Ser or Thr involved in the linkage always belongs to a β-turn. In the case of N-glycosidically linkages, 19 out of the 28 Asn studied belong to a β-turn. A predicted determination concerning the whole protein moiety of 9 glycoproteins in order to obtain some information concerning the spatial organization of the entire glycoprotein was carried out also. It seems that carbohydrate moiety takes place outside the glycoprotein.     

Apports de la palynologie a la connaissance du Pliocène du Roussillon (sud de la France)

The present study illustrates clearly how pollen analysis may be applied to stratigraphy from a botanical point of view. Within a chronologically reliable frame (Middle Pliocene for the marine deposits on the basis of Foraminifera record; two subzones for continental deposits on the basis of Mammals record: Hautimagne for Terrats fauna, Sète for Serrat-d'en-Vacquer fauna), palynology provides a good stratigraphical boundary: the extinction of the Taxodiaceae. In a remblayage area, it is established that a continental level is not necessarily younger than a marine one unless they are superposed. Many profiles are replaced according to the «progradation of the pliocene gulf of Roussillon. The boundary between marine and continental deposits cuts through the chronological line of the Taxodiaceae extinction. The flora investigated (93 taxa) is the first known for the Pliocene of this area. The extinction of the Taxodiaceae in southern France has a climatic cause: the setting in of a mediterranean rhythm (dry summers). This extinction is much older than the one which took place in Italy (Tiberian boundary) and in the Netherlands (Reuverian-Pretiglian boundary).     

Impairment of contractility associated with muscarinic supersensitivity in trachea isolated from diabetic rats: lack of correlation with ultrastructural changes or quinuclidinyl benzylate binding to lung membranes

Evolution of cholinergic response of rat isolated trachea was determined after various durations of diabetes (17, 40, 90, 150 and 210 days). Long-term diabetes was associated with both impairment of contractility and supersensitivity to cholinergic stimulation. However, the mechanism of these alterations remains to be determined, as response to field stimulation was not specifically altered while electron microscopy studies could not detect any significant change in the aspect of nerves, smooth muscle or epithelium. As well, binding studies of lung cholinergic receptors using the antagonist ligand [³H]-quinuclidinyl benzylate and the agonist carbachol did not detect any change in diabetic animals.     

Short and simple synthesis of (R)- and (S)-4-hydroxypentylaminoacetamide: both enantiomers of the (ω-1)-hydroxylated metabolite of milacemide

Both (R)- and (S)-4-hydroxypentylaminoacetamide have been synthesized by reductive amination of glycinamide on the γ-valerolactols corresponding to (R)- and (S)-γ-valerolactone, respectively. These enantiomeric lactones were readily obtained in high enantiomeric excess (ee) by enzymic porcine pancreatic lipase (PPL) kinetic resolution of rac-methyl γ-hydroxyvalerate. © 1992 Wiley-Liss, Inc.     

Purification of plant mitochondria by isopycnic centrifugation in density gradients of Percoll

Mitochondria from potato tubers have been separated from contaminating organelles and membrane vesicles on self-generated Percoll gradients and in a relatively short time. The Percoll-purified mitochondria devoid of carotenoids and galactolipids showed no contamination with intact plastids, microbodies, or vacuolar enzymes. Percoll-purified mitochondria exhibited intact membranes and a dense matrix. The intactness of purified mitochondrial preparations was ascertained by the measurement of KCN-sensitive ascorbate cyt c-dependent O₂ uptake. When compared with washed mitochondria, Percoll-purified mitochondria showed improved rates of substrate oxidation, respiratory control, and ADP:O ratios. The recovery of the cyt oxidase was 70–90% and on a cyt oxidase basis the rate of succinate oxidation by unpurified mitochondria was equal to that recorded for Percoll-purified mitochondria. The great flexibility of purification procedure involving silica sols was extended from mitochondria to the isolation of intact peroxisomes.