Enzymatic synthesis of alkyl beta-D-xylosides by transxylosylation and reverse hydrolysis

The Trichoderma reesei beta-xylosidase (EC 3.2.1.37) is used to catalyze the production of alkyl beta-D-xyloside. Two general methods of production are tested and compared using the same enzyme: transglycosylation and reverse hydrolysis. Using both methods, primary, secondary, and tertiary alcohols are studied as acceptors. In kinetically controlled process (transglycosylation), the chosen donor is methyl beta-D-xyloside and primary, secondary, and tertiary alkyl alcohols are accepted. In the equilibrium-controlled synthesis, the donor is xylose whereas acceptors are only primary and secondary alcohols. The influence of the donor concentration is investigated in both processes. The yields of the kinetically controlled reactions are higher compared with those of the equilibrium-controlled synthesis. The specificity of the beta linkage is confirmed by proton nuclear magnetic resonance ((1)H NMR) analysis. (c) 1994 John Wiley & Sons, Inc.     

The gene coding for the α1 subunit of the skeletal dihydropyridine receptor (Cchl1a3=mdg) maps to mouse Chromosome 1 and human 1q32

Using both chromosomal in situ hybridization and molecular techniques, we report the genetic localization of the gene coding for the alpha 1 subunit of the skeletal slow Ca²⁺ current channel/DHP receptor gene (Cchl1a3) on human Chromosome (Chr) 1 (1q31–1q32 region) and on mouse Chr 1 region (F-G). On the basis of single-strand conformation polymorphism (SSCP-PCR) analysis in an interspecific backcross, we have determined that the Cchl1a3=mdg (muscular dysgenesis) locus is very closely linked to the myogenin (Myog) locus.     

Aging of cylinders excised from pulp tissues of the ;golden delicious' apple

Aging cylinders excised from `Golden Delicious' apple (Pyrus malus L.) pulp, like the intact fruit, exhibit some characteristic phenomena such as rise in respiration (climacteric), ethylene synthesis, enzymic changes, and increase in ribosomes and mRNA. Aging of cylinders of pulp tissues may offer a useful physiological tool for the study of maturation and senescence.     

Polyribosomes from Pear Fruit: II. CHANGES OCCURRING IN PULP TISSUES DURING RIPENING AND SENESCENCE

Detailed analyses of polysome profiles from lyophilized pulp tissues of pear fruits (Pyrus communis L. cv. Passe-Crassane) at different stages of ripening and senescence, and estimates of the amount of polysomal-associated mRNA, lead to the conclusions that during senescence (ripening), the ripening and the over-ripening processes can clearly be separated and respectively linked to the first and the second increase in the large mRNA species. Ethylene synthesis which occurs at the beginning of a normal ripening at 15°C after a cold storage or an ethephon treatment is related to an increase in mRNA and ribosomal material found only in pulp tissues. Finally, we suggest that in the pear fruit, the sequence of events which occurs during senescence (ripening) is initiated by two systems which regulate ethylene biogenesis, and that the first system is efficient only at low temperatures (from 0 to 4°C).     

Exonic Splicing Mutations Are More Prevalent than Currently Estimated and Can Be Predicted by Using In Silico Tools

The identification of a causal mutation is essential for molecular diagnosis and clinical management of many genetic disorders. However, even if next-generation exome sequencing has greatly improved the detection of nucleotide changes, the biological interpretation of most exonic variants remains challenging. Moreover, particular attention is typically given to protein-coding changes often neglecting the potential impact of exonic variants on RNA splicing. Here, we used the exon 10 of MLH1, a gene implicated in hereditary cancer, as a model system to assess the prevalence of RNA splicing mutations among all single-nucleotide variants identified in a given exon. We performed comprehensive minigene assays and analyzed patient’s RNA when available. Our study revealed a staggering number of splicing mutations in MLH1 exon 10 (77% of the 22 analyzed variants), including mutations directly affecting splice sites and, particularly, mutations altering potential splicing regulatory elements (ESRs). We then used this thoroughly characterized dataset, together with experimental data derived from previous studies on BRCA1, BRCA2, CFTR and NF1, to evaluate the predictive power of 3 in silico approaches recently described as promising tools for pinpointing ESR-mutations. Our results indicate that ΔtESRseq and ΔHZ_EI-based approaches not only discriminate which variants affect splicing, but also predict the direction and severity of the induced splicing defects. In contrast, the ΔΨ-based approach did not show a compelling predictive power. Our data indicates that exonic splicing mutations are more prevalent than currently appreciated and that they can now be predicted by using bioinformatics methods. These findings have implications for all genetically-caused diseases.