The performance of fungal xylan-degrading enzyme preparations in elemental chlorine-free bleaching for Eucalyptus pulp

Cellulase-free xylan-degrading enzyme preparations from Acrophialophora nainiana, Humicola grisea var. thermoidea and two Trichoderma harzianum strains were used as bleaching agents for Eucalyptus kraft pulp, prior to a chlorine dioxide and alkaline bleaching sequence. In comparison to the control sequence (performed without xylanase pretreatment), the sequence incorporating enzyme treatment was more effective. Removal of residual lignin was indicated by a reduction in kappa number. Overall, enzyme preparations from T. harzianum were marginally more effective in reducing pulp viscosity and chlorine chemical consumption and improving the brightness of the kraft pulp. However, the highest reduction in pulp viscosity was mediated by the xylanase preparation from A. nainiana. Xylanase pretreatment compares very favorably with that of chemical pulping. Journal of Industrial Microbiology & Biotechnology (2002) 28, 204–206 DOI: 10.1038/sj/jim/7000227 Received 27 April 2001/ Accepted in revised form 03 November 2001     

mTOR activates the VPS34–UVRAG complex to regulate autolysosomal tubulation and cell survival

Lysosomes are essential organelles that function to degrade and recycle unwanted, damaged and toxic biological components. Lysosomes also act as signalling platforms in activating the nutrient‐sensing kinase mTOR. mTOR regulates cellular growth, but it also helps to maintain lysosome identity by initiating lysosomal tubulation through a process termed autophagosome‐lysosome reformation (ALR). Here we identify a lysosomal pool of phosphatidylinositol 3‐phosphate that, when depleted by specific inhibition of the class III phosphoinositide 3‐kinase VPS34, results in prolonged lysosomal tubulation. This tubulation requires mTOR activity, and we identified two direct mTOR phosphorylation sites on UVRAG (S550 and S571) that activate VPS34. Loss of these phosphorylation sites reduced VPS34 lipid kinase activity and resulted in an increase in number and length of lysosomal tubules. In cells in which phosphorylation at these UVRAG sites is disrupted, the result of impaired lysosomal tubulation alongside ALR activation is massive cell death. Our data imply that ALR is critical for cell survival under nutrient stress and that VPS34 is an essential regulatory element in this process.     

Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger

Background  

Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction [1]. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation [2–4]. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.     

Evolution of androgen-regulated mRNA expression in mouse kidney

To gain information on the evolution of mammalian gene expression patterns, we studied the androgen-inducible expression of three kidney mRNAs in several mouse species (genus Mus). The RP2, ornithine decarboxylase, and beta-glucuronidase mRNAs have each evolved independently, in that the pattern of variation among species is unique for each. This suggests a role for gene-specific, cis-acting genetic elements. Relationships between the regulatory phenotypes and the species phylogeny suggest that the variations in hormone-inducible mRNA expression were generated by a series of independent mutations that occurred in specific lineages, resulting in modifications of the progenitor phenotype. Alternatively, the variations may have preexisted within the progenitor population as polymorphisms that were fixed during establishment of individual lineages. Thus, significant alterations in the androgen-regulated mRNA phenotype have occurred either prior to or during speciation within the Mus genus. These alterations are presumed to be in regulatory sequences that control the expression of the corresponding genes and their response to testosterone; as such, they should be useful in further studying the genetic determinants of gene expression and its evolution.