Purification and characterization of laccase isozymes from the white-rot basidiomycete Ganoderma lucidum

Ganoderma lucidum, a medicinal white-rot basidiomycete, produces many laccase isozymes in liquid culture. Three laccase isozymes (GaLc 1, 2, 3) have been purified 32.4-fold from the crude enzyme protein through anion exchange chromatography, preparative gel electrophoresis, and electroelution. Their estimated molecular weights are 65-68 kDa, and they contain 7-10% N-linked carbohydrates. The three isozymes have identical N-terminal amino acid sequences: G-I-G-P-T. The optimum pH and temperature both for each isozyme singly and the isozyme mixture are pH 3.5 and 20 degrees C, respectively. One isozyme (GaLc 3) is quite stable at pH 4.0-10.0, and shows good stability when incubated at temperatures lower than 40 degrees C. The Km values of GaLc 3 for o-tolidine and 2,2'-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) are 401.6 microM and 3.7 microM respectively, and the Vmax of GaLc 3 for these substrates is 0.0198 OD min(-1) unit(-1) and 0.0142 OD min(-1) unit(-1), respectively.     

SWIMMING EXERCISE STIMULATES NEURO-GENESIS IN THE SUBVENTRICULAR ZONE VIA INCREASE IN SYNAPSIN I AND NERVE GROWTH FACTOR LEVELS

In this study, we investigated the effects of 8-weeks of swimming exercise on neurogenesis in the subventricular zone (SVZ) and on the levels of nerve growth factor (NGF) and synapsin I protein in the olfactory bulb (OB) of adult rats at a series of relevant time points (2 days, 1 week, 2 weeks, 4 weeks, 3 months, and 6 months). Ninety-six male Sprague Dawley rats were divided into 2 groups: (1) a control group (COG; n = 48, n = 8 for each time point) and (2) a swimming exercise group (SEG; total n = 48; n = 8 for each time point). SEG performed swimming exercise for 5 days per week over a period of 8 weeks. We found that the number of 5-bromo-2’-deoxyuridine-5’-monophosphate (BrdU)- and doublecortin (DCX)-positive cells was significantly higher in SEG than in COG at all time points (Day 2, Week 1, Week 2, Week 4, Month 3, and Month 6; p < 0.001). Furthermore, NGF and synapsin I protein levels were significantly higher in SEG on Day 2, and Weeks 1, 2, and 4 than in COG (p < 0.05 for each time point). Our findings suggest that regular swimming exercise in adult rats increases neurogenesis, neuronal survival, and neuronal maintenance in the SVZ; furthermore, swimming exercise increases the levels of NGF and synapsin I in the OB.     

Distinct gene expression signatures during development of distant metastasis

Using cDNA microarrays, we have conducted a systematic characterization of global gene expression in v-raf or v-raf/v-myc transformed rat liver epithelial (RLE) cell lines exhibiting both non-metastatic and metastatic phenotypes. Seven transformed cell lines were compared with the non-transformed parental RLE cell. The hierarchical clustering analysis of gene expression profiles revealed two groups reflecting the in vivo metastatic potential of the cells. Surprisingly, one non-metastatic cell line T1 was co-clustered with metastatic cell lines, suggesting that T1 underwent significant genetic changes. The T1 cell line was further compared against all the metastatic cell lines in order to reveal the critical genes required for metastatic conversion but not expressed in the T1. These data demonstrated that expression of genes involved in apoptosis and immune cell homing were altered in all metastatic cell lines. Survival of both intravasated cells in circulation systems and extravasated cells in a new tissue environment might be critical for the final step in the metastatic process. Our study provides gene expression signatures consistent with two critical events in the metastatic process, namely, the acquisition of early homing capacity and increased survival potential of the tumor cells.