University of Saskatchewan

About: University of Saskatchewan is a education organization based out in Saskatoon, Saskatchewan, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 25021 authors who have published 52579 publications receiving 1483049 citations. The organization is also known as: USask.

The sirodesmin biosynthetic gene cluster of the plant pathogenic fungus Leptosphaeria maculans.

Abstract: Sirodesmin PL is a phytotoxin produced by the fungus Leptosphaeria maculans, which causes blackleg disease of canola (Brassica napus). This phytotoxin belongs to the epipolythiodioxopiperazine (ETP) class of toxins produced by fungi including mammalian and plant pathogens. We report the cloning of a cluster of genes with predicted roles in the biosynthesis of sirodesmin PL and show via gene disruption that one of these genes (encoding a two-module non-ribosomal peptide synthetase) is essential for sirodesmin PL biosynthesis. Of the nine genes in the cluster tested, all are co-regulated with the production of sirodesmin PL in culture. A similar cluster is present in the genome of the opportunistic human pathogen Aspergillus fumigatus and is most likely responsible for the production of gliotoxin, which is also an ETP. Homologues of the genes in the cluster were also identified in expressed sequence tags of the ETP producing fungus Chaetomium globosum. Two other fungi with publicly available genome sequences, Magnaporthe grisea and Fusarium graminearum, had similar gene clusters. A comparative analysis of all four clusters is presented. This is the first report of the genes responsible for the biosynthesis of an ETP.

Soft X-ray spectromicroscopy beamline at the CLS: Commissioning results

Abstract: The soft X-ray spectromicroscopy beamline (SM) at the Canadian Light Source (CLS) is a dedicated spectromicroscopy facility, consisting of an elliptically polarized undulator (EPU), a beamline based on a collimated PGM optimized for 100–2000 eV range and two end stations: scanning transmission X-ray microscope (STXM) and roll-in X-ray photoemission electron microscope (X-PEEM, from Elmitec GmbH). The overall system has achieved its design parameters with an on-sample flux of ∼108 ph/s@R=3000, 0.5 A in STXM and ∼1012 ph/s@R=3000, 0.5 A in the PEEM, in each case at a spatial resolution exceeding 40 nm. It can also provide an energy resolving power above 10,000. A careful EPU calibration procedure enables advanced polarization measurements.