Pleurotus ostreatus (the oyster mushroom) and other white rot filamentous basidiomycetes are key players in the global carbon cycle. P. ostreatus is also a commercially important edible fungus with medicinal properties and is important for biotechnological and environmental applications. Efficient gene targeting via homologous recombination (HR) is a fundamental tool for facilitating comprehensive gene function studies. Since the natural HR frequency in Pleurotus transformations is low (2.3%), transformed DNA is predominantly integrated ectopically. To overcome this limitation, a general gene targeting system was developed by producing a P. ostreatus PC9 homokaryon ⌬ku80 strain, using carboxin resistance complemented by the development of a protocol for hygromycin B resistance protoplast-based DNA transformation and homokaryon isolation. The ⌬ku80 strain exhibited exclusive (100%) HR in the integration of transforming DNA, providing a high efficiency of gene targeting. Furthermore, the ⌬ku80 strains produced showed a phenotype similar to that of the wild-type PC9 strain, with similar growth fitness, ligninolytic functionality, and capability of mating with the incompatible strain PC15 to produce a dikaryon which retained its resistance to the corresponding selection and was capable of producing typical fruiting bodies. The applicability of this system is demonstrated by inactivation of the versatile peroxidase (VP) encoded by mnp4. This enzyme is part of the ligninolytic system of P. ostreatus, being one of the nine members of the manganese-peroxidase (MnP) gene family, and is the predominantly expressed VP in Mn 2؉ -deficient media. mnp4 inactivation provided a direct proof that mnp4 encodes a key VP responsible for the Mn 2؉ -dependent and Mn 2؉ -independent peroxidase activity under Mn 2؉ -deficient culture conditions.

Polysaccharides are one of the most potent mushroom-derived substances exhibiting anti-inflammatory and immunomodulatory properties. The aims of the present study were to determine whether orally administered glucans from the edible mushroom Pleurotus pulmonarius could attenuate or prevent the development of experimental colitis in mice. Colonic inflammation was induced in mice by treatment with 3·5 % dextran sulfate sodium (DSS) for 18 d. Before or after DSS administration, mice were given hot water solubles (HWS) or mycelium extract (ME) (2 or 20 mg per mouse) daily in their food. Colonic damage was macroscopically and histologically evaluated. Inflammation was assessed by changes in colon length, TNF-a levels released by colonic samples in organ culture and myeloperoxidase (MPO) activity. mRNA levels of pro-inflammatory (IL-1b) and anti-inflammatory (IL-10) cytokines in colonic samples were determined by quantitative real-time RT-PCR. P. pulmonarius glucans attenuated and prevented the development of symptoms associated with DSS-induced colitis. High doses of HWS and ME blocked colon shortening, suppressed MPO activity and improved macroscopic score in all treatment groups. In addition, histological damage from colitis was reduced by HWS and ME at all doses. The tissue levels of TNF-a protein were significantly decreased and correlated with degree of inflammation and macroscopic score. All treatments significantly attenuated the increased DSS-mediated expression levels of IL-1b. We conclude that the different glucan preparations (HWS or ME) harvested from P. pulmonarius when orally administered to DSS-treated mice attenuate the development of colonic inflammation, suggesting putative clinical utility for these extracts in the treatment of colitis.

Intentional cultivation of a collaborative learning climate, formal inclusion of health care disparities curriculum, and commitment to fostering student body diversity are three routes by which PSOM has supported URM students. Additionally, recognizing the importance of building a diverse faculty and extending efforts to decrease the disproportionate burden and stereotype threat felt by URM students are institutional imperatives.