Multiple xylanases of Cellulomona fimi are encoded by distinct genes

Cellulomonas fimi genomic DNA encoding xylanase activity has been cloned and expressed in Escherichia coli. As judged by DNA hybridization and restriction analysis, twelve xylanase-positive clones carried a minimum of four different xylanase (xyn) genes. The encoded enzymes were devoid of cellulase activity but three of the four bound to Avicel.     

Residue Histidine 50 Plays a Key Role in Protecting α-Synuclein from Aggregation at Physiological pH

α-Synuclein (αSyn) aggregation is involved in the pathogenesis of Parkinson disease (PD). Recently, substitution of histidine 50 in αSyn with a glutamine, H50Q, was identified as a new familial PD mutant. Here, nuclear magnetic resonance (NMR) studies revealed that the H50Q substitution causes an increase of the flexibility of the C-terminal region. This finding provides direct evidence that this PD-causing mutant can mediate long range effects on the sampling of αSyn conformations. In vitro aggregation assays showed that substitution of His-50 with Gln, Asp, or Ala promotes αSyn aggregation, whereas substitution with the positively charged Arg suppresses αSyn aggregation. Histidine carries a partial positive charge at neutral pH, and so our result suggests that positively charged His-50 plays a role in protecting αSyn from aggregation under physiological conditions.     

Methods Involving Light Variation for Isolation of Cyanobacteria: Characterization of Isolates from Central Australia

We report the isolation of organisms belonging to a range of cyanobacterial genera from the remote arid region of central Australia, together with a preliminary characterization of their temporal modes of nitrogen fixation. We rendered unialgal Dermocarpa and Myxosarcina spp. (Section II organisms), LPP group B: type X (Section III), and Scytonema and Nostoc spp. (Section IV). We developed an isolation procedure based on a combination of published methods and applicable to a broad spectrum of cyanobacterial genera. We found light intensity to be a critical variable in our methodology; it was also an important determinant of the proportions of different organisms growing in stable mixtures.