O-glycosylation of dipeptides using β-galactosidase activity of Achatina achatina digestive juice

Summary Enzymatic O-glycosylation of dipeptide derivatives containing a serine residue in the N or C terminal position and alanine or glycine as the second amino acid was achieved using the transgalactosylation activity of -galactosidase from the Achatina achatina digestive juice. Reactions were performed with lactose as glycosyl donor and the dipeptide ethyl (or methyl) esters N-protected by a benzyloxycarbonyl group (Z) as glycosyl acceptors. Yields of galactosyl-dipeptide derivatives were much higher than those obtained with the E.coli -galactosidase as catalyst.     

The human T-cell receptor gamma variable pseudogeneV10 is a distinctive marker of human speciation

The nucleotide sequence data reported in this paper have been submitted to the EMBL/GenBank/DDBJ nucleotide sequence databases and have been assigned the accession numbers X86 558 and X86 709–X86 723     

Effect of sulphate on photosynthesis in greenhouse–grown tomato plants

Sulphate accumulates in the rhizosphere of plants grown in hydroponic systems. To avoid such sulphate accumulation and promote the use of environmentally sound hydroponic systems, we examined the effects of four sulphate concentrations (0.1, 5,2, 10.4 and 20.8 m M ) on photosynthesis, ribulose-l,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activities and related physiological processes in greenhouse–grown tomato plants ( Lycopersicon esculentum Mill. cv. Trust). The lowest sulphate concentration (0.1 m M ) significantly decreased photosynthetic capacity (P_c) and Rubisco activities on a leaf area basis. This result was supported by our data for dry matter per plant, which was low for plants in the 0.1 m M treatment. The photosynthesis-related variables such as leaf conductance, chlorophyll and soluble protein were lowest for the 0.1 m M treatment. Both total Rubisco activity and the activated ratio were reduced with this treatment. However, Rubisco activities expressed per g of protein or per g of chlorophyll were not significantly affected. These results suggest that sulphur deficiency depressed P_c– by reducing the amount of both Rubisco and chlorophyll and by causing an inactivation of Rubisco. The ratio of organic sulphur vs organic nitrogen (S/N) in plants of the 0.1 m M treatment was far below the normal values. This low S/N ratio might be accountable for the negative effect of low sulphate on P_c and plant growth. P_c and dry matter were not affected until sulphate concentration in the nutrient solution reached a high level of 20.8 m M .     

Advantages of the scanning ion microscopy for mapping halogen corticoids in normal and transformed cells in culture

Summary— The intra-cellular distribution of eight halogen glucocorticoids was investigated by ion microscopy in two cellular varieties of cultured non-cancer cells (fibroblast 3T3) and cancer cells (human breast tumor cells MCF-7). Two types of ion microscopy helped to determine this distribution, a direct imaging ion microscope (SMI 300) with low spatial resolution, and a scanning ion microscope (IMS4F), featuring high resolution, serving to obtain maps representing the intra-cellular distribution of the fluorine elements and drugs present in these monolayer cultured cells. The fluorine images representative of the drugs containing fluorine showed that these drugs are essentially concentrated in the cell nuclei. In these nuclei, the distribution of these drugs is different from that of heterochromatin and of the nucleolus.     

Familial Site-specific Ovarian Cancer Is Linked to BRCA1 on 17q12-21

In a study of nine families with “site-specific” ovarian cancer (criterion: three or more cases of epithelial ovarian cancer and no cases of breast cancer diagnosed at age <50 years) we have obtained evidence of linkage to the breast-ovarian cancer susceptibility gene, BRCA1 on 17q12-21. If the risk of cancer in these families is assumed to be restricted to the ovary, the best estimate of the proportion of families linked to BRCA1 is .78 (95% confidence interval .32–1.0). If predisposition to both breast and ovarian cancer is assumed, the proportion linked is 1.0 (95% confidence interval .46–1.0). The linkage of familial site-specific ovarian cancer to BRCA1 indicates the possibility of predictive testing in such families; however, this is only appropriate in families where the evidence for linkage to BRCA1 is conclusive.     

Involvement of an N-Acetylglucosaminidase in Autolysis of Propionibacterium freudenreichii CNRZ 725

Propionibacterium freudenreichii plays an important role in Swiss cheese ripening (it produces propionic acid, acetic acid, and CO₂). Moreover, autolysis of this organism certainly contributes to proteolysis and lipolysis of the curd because intracellular enzymes are released. By varying external factors, we determined the following conditions which promoted autolysis of both whole cells and isolated cell walls of P. freudenreichii CNRZ 725: (i) 0.1 M potassium phosphate buffer (pH 5.8) at 40°C and (ii) 0.05 to 0.1 M KCl at 40°C. We found that early-exponential-phase cells possessed the highest autolytic activity. It should be emphasized that the pH of Swiss cheese curd (pH 5.5 to 5.7) is near the optimal pH which we determined. Ultrastructural observations by electron microscopy revealed a 16-nm-thick homogeneous cell wall, as well as degradation of the cell wall that occurred concomitantly with cell autolysis. In the presence of 0.05 M potassium chloride, there was a great deal of isolated cell wall autolysis (the optical density at 650 nm decreased 77.5% ± 7.3% in 3 h), and one-half of the peptidoglycan material was released. Finally, the main autolytic activity was due to an N-acetylglucosaminidase activity.     

Effect of ischemia/reperfusion sequence on cytosolic iron status and its release in the coronary effluent in isolated rat hearts

The hypothesis that oxygen-derived free radicals play an important role in myocardial ischemic and reperfusion injury has received a lot of support. In the presence of catalytic amounts of transition metals such as iron, superoxide anions, and hydrogen peroxide can be transformed into a highly reactive hydroxyl radical °OH (Haber-Weiss reaction). In view of this, we have undertaken this study to investigate whether iron is involved in the reperfusion syndrome and therefore could aggravate free radicals injury. Coronary effluent iron concentrations and cardiac cytosolic iron levels were evaluated in rat hearts subjected to an ischemia/reperfusion sequences. In the case of total ischemia, iron concentration in coronary effluents peaked immediately in the first sample collected upon reperfusion. However, in the case of partial ischemia, iron concentration in coronary effluents peaked rather exclusively during ischemia period. Cardiac cytosolic iron level augmented significantly after 30 min of total ischemia and non significantly in the other ischemia protocols compared to perfused control hearts. It also appears that the iron released is not protein-bound, and could therefore have a marked catalytic activity. The results of the present study suggest that in the oxygen paradox, iron plays an important role in inducing alterations during reoxygenation.