High frequency of-β-hexosaminidase deficiency in lymphoblastoid cell lines

The activity of seven lysosomal enzymes was determined in 25 lymphoblastoid cell lines. These lines included normal controls transformed with Epstein-Barr virus, Burkitt's lymphomas and other lymphomas with or without EBV genome.Four lines were deficient in total β-hexosaminidase activity. The deficiency was as severe as that of the variant O (Sandhoff's disease) of clinical β-hexosaminidase deficiency. The electrophoretic pattern was also similar to that observed in Sandhoff's disease.The possible mechanisms explaining the high frequency of β-hexosaminidase deficiency in lymphoblastoid cell lines are discussed.     

Spot position of rat liver ribosomal proteins by four different two-dimensional electrophoreses in polyacrylamide gel

Summary Separation of the proteins from rat liver 40S and 60S ribosomal subunits and polysomes was done in four different two-dimensional polyacrylamide gel electrophoresis systems. The first dimension was run at acidic or basic pH, the second dimension either with sodium dodecyl sulphate or at acidic pH in 18% acrylamide. The position of each individual protein of both subunits and polysomes was determined in each system. This identification resulted from a new method avoiding any previous purification of individual proteins. The new proposed uniform nomenclature for mammalian ribosomal proteins (McConkey et al. in press) was used for numbering the proteins in the four systems.     

Nouvelles formulations des regles ecologiques connues sous le nom de reegle de Bergmann et loi de Jordan: Amendments of the ecological rules known as Bergmann's and Jordan's rules

Measurements of populations of planktonic and micronektonicspecies from the Atlanto-mediterranean region (about 10,000specimens) have lead to improvements in Bergmann's rule relatingto the increase in size with latitude. There are three cases : Mediterranean specimens may be smaller(e.g. the mysid Eucopia hansent), equal to (e.g. the decapodcrustacean Gennadas elegans) or larger than Atlantic ones (e.g.the thecosomatous genus Cymbulia). All the species in the last group have their principal distributionin warm ocean waters. In the Atlantic, tropical species (e.g.the euphausiid Euphausia gibboides) decrease in size in thenorthern parts of their range while temperate species (e.g.the decapod crustacean Sergesles corniculum) decrease in sizetowards both the pole and the equator. The comparison with the number of vertebrae of fish, which increasesas does the size according to Jordan's rule, is interesting:though correct for cold water species (e.g. Merlucdus merluccius),this rule cannot be applied to warm water species (e.g. Merlucciussenegalensis). Thus, these rules must be corrected like this:- "a species reachesits maximal size in high, intermediate or low latitudes of itsarea if it has a boreal, temperate or tropical distribution"; - "the number of vertebrae increases with latitude for borealfish and decreases for tropical ones".     

Mode of action of a xylanase and its significance for the structural investigation of the branched l-arabino-d-glucurono-d-xylan from redwood (Sequoia sempervirens)

The substitution pattern of the water-soluble l-arabino-(4-O-methyl-d-glucurono)-d-xylan from redwood (Sequoia sempervirens) has been studied by enzymic degradation. Exhaustive hydrolysis by an endo-xylanase (EC 3.2.1.8) from a Basidiomycete Sporotrichum dimorphosporum left a residue accounting for 20% of the original d-xylan. In the dialyzable material, oligosaccharides having arabinose or 4-O-methylglucuronic acid residues attached to the non-reducing d-xylosyl end-group of xylobiose or xylotriose, respectively, were the smallest branched oligomers released. Action of the xylanase appears to involve a region of the polysaccharide backbone having three xylosyl residues. A mode of action is proposed that requires unsubstituted hydroxyl groups at C-2, C-3, and C-2′ of a xylobiosyl residue. The binding site seems to correspond to a shallow cavity. The composition and structure of the final residue of attack shows that the enzyme has no action when the xylosyl residues branched through O-2 are separated by only one, unsubstituted xylose residue. This pattern of action, the nature of the dialyzable products, and the production of a final residue in which the substituents are accumulated, suggest that the arabinosyl and glucosyl-uronic groups are irregularly distributed on the main chain of the xylan from redwood and that in some regions they are in close vicinity when not actually on adjacent xylosyl residues.     

Interaction between macrophages and Schistosoma mansoni schistosomula: Role of IgG peptides and aggregates on the modulation of β-glucuronidase release and the cytotoxicity against schistosomula

Discharge of lysosomal enzymes, measured by release of β-glucuronidase and cytotoxicity against Schistosoma mansoni schistosomula, was studied when rat macrophages were incubated in the presence of either IgG peptides, resulting from the cleavage of nonimmune IgG by parasitic proteases, or nonimmune aggregated IgG. With peptides, the macrophage activity showed a dramatic decrease while they were stimulated by IgG aggregates. In contrast, the synthesis of lymphocyte activating factor by macrophages was unaffected. The hydrolysis of IgG is carried out by two distinct enzymatic molecules released into the medium by the larvae. The mechanism by which nonimmune IgG peptides or aggregates inhibit or stimulate macrophage activity, regulated by both parameters indicated above, is discussed and is suggested as a general regulation mechanism for the macrophage activity required for parasite survival in the host.     

Mutations of Chinese Hamster Somatic Cells from 2-Deoxygalactose Sensitivity to Resistance

In Chinese hamster somatic cells, the spontaneous change of phenotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la Luria and Delbrück (1943) for four Chinese hamster cell strains derived from V79. The results are consistent with true mutational events. The mutation rates are in the range of 1 to 3.5 X 10(-5) per cell per generation. The relationship between the 2-deoxyglactose resistance and the galactokinase markers is discussed.     

Morphological and functional correlates of synchronous beating between embryonic heart cell aggregates and layers

We have examined correlations between morphological and functional evidence of cell coupling between aggregates of beating embryonic heart cells and underlying layers. Synchronously beating aggregate-layer pairs were compared with asynchronous pairs. Intracellular microelectrode studies demonstrated that asynchronously beating aggregate-layers could not be induced to beat synchronously by electrical stimulation of the aggregate, whereas 86% of synchronous instances showed propagation of stimulating current pulses from aggregate to layer. By freeze fracture we have found significant differences both in the number and in the total area of gap junctions between the aggregate-layer interfaces of synchronous and asynchronous preparations. The data suggest that synchronous beating is a reliable functional indication of effective ionic coupling, and requires a certain area and number of gap junction/cell.     

Interactions glycanne-protéine. Synthése des 4-méthylombelliféryl-(2-acétamido-2-désoxy-β-D-glucopyranoside), -DI-N-acétyl-β-chitobioside et -tri-N-acétyl-β-chitotrioside. Interaction de ces osides avec le lysozyme

4-Methylumbelliferyl 2-acetamido-2-deoxy-β-D-glucopyranoside, 2-acetamido-4-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-2-deoxy-β-D-glucopyranoside (di-N-acetyl-β-chitobioside), and O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→4)-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (tri-N-acetyl-β-chitotrioside) were obtained in good yield from the corresponding peracetylated glycosyl chlorides by condensation with the sodium salt of 4-methylumbelliferone in N,N-dimethylformamide. The trisaccharide glycoside is hydrolyzed by lysozyme and is, therefore, a convenient substrate for this enzyme; the 4-methylumbelliferone produced can be determined by the increase of the fluorescence intensity at 442 nm. The intensity of the fluorescence of 4-methylumbelliferyl tri-N-acetyl-β-chitotrioside is enhanced upon binding with lysozyme without modification of the position of the absorption maximum. The binding constant and the rate of hydrolysis of the trisaccharide glycoside by lysozyme are higher than those obtained with p-nitrophenyl tri-N-acetyl-β-chitotrioside.     

Gene silencing with RNA interference in the human pathogenic fungus Aspergillus fumigatus

Aspergillus fumigatus is an opportunistic pathogenic fungus which causes fatal invasive aspergillosis among immunocompromised patients. To obtain a better understanding of the key elements involved in A. fumigatus virulence and to identify possible drug targets, it is necessary to be able to generate gene-deletion strains. Unfortunately, the molecular techniques available do not include a rapid method to disrupt and identify essential genes. RNA interference, a process in which the presence of double-stranded RNA homologous to a gene of interest results in specific degradation of the corresponding message, has been successfully tested on A. fumigatus. We have shown that expression of double stranded RNA corresponding to portions of the ALB1/PKSP and FKS1 genes results in reduced mRNA levels for those genes, with phenotypic consequences similar to that of gene disruption. The two genes could also be subjected to simultaneous interference through expression of chimeric double-stranded RNA. Use of RNA interference in Aspergillus will allow easier examination of the phenotypic consequences of reducing expression of a gene of interest, especially for essential genes.