Biologically relevant effects of mRNA amplification on gene expression profiles

Background  

Gene expression microarray technology permits the analysis of global gene expression profiles. The amount of sample needed limits the use of small excision biopsies and/or needle biopsies from human or animal tissues. Linear amplification techniques have been developed to increase the amount of sample derived cDNA. These amplified samples can be hybridised on microarrays. However, little information is available whether microarrays based on amplified and unamplified material yield comparable results.     

Production of medium-chain-length PHA in octanoate-fed enrichments dominated by Sphaerotilus sp.

Medium-chain-length polyhydroxyalkanoate (mcl-PHA) production by using microbial enrichments is a promising but largely unexplored approach to obtain elastomeric biomaterials from secondary resources. In this study, several enrichment strategies were tested to select a community with a high mcl-PHA storage capacity when feeding octanoate. On the basis of analysis of the metabolic pathways, the hypothesis was formulated that mcl-PHA production is more favorable under oxygen-limited conditions than short-chain-length PHA (scl-PHA). This hypothesis was confirmed by bioreactor experiments showing that oxygen limitation during the PHA accumulation experiments resulted in a higher fraction of mcl-PHA over scl-PHA (i.e., a PHA content of 76 wt% with an mcl fraction of 0.79 with oxygen limitation, compared to a PHA content of 72 wt% with an mcl-fraction of 0.62 without oxygen limitation). Physicochemical analysis revealed that the extracted PHA could be separated efficiently into a hydroxybutyrate-rich fraction with a higher M_w and a hydroxyhexanoate/hydroxyoctanoate-rich fraction with a lower M_w. The ratio between the two fractions could be adjusted by changing the environmental conditions, such as oxygen availability and pH. Almost all enrichments were dominated by Sphaerotilus sp. This is the first scientific report that links this genus to mcl-PHA production, demonstrating that microbial enrichments can be a powerful tool to explore mcl-PHA biodiversity and to discover novel industrially relevant strains.     

Increase of the production of tumor necrosis factor in endotoxin shock in mice presensitized with sera of tumor-bearing mice or tumor cell factor]

We investigated the phenomenon of increased sensitivity of tumor-bearing mice to endotoxin shock. I/V administration of sera from tumor (EL-4, B16, R815, MOPC-315) bearers or tumoral culture media into intact mice caused the increased sensitivity to lethal action of LPS plus GMDP. Production of TNF in above mice was also significantly increased under the influence of LPS plus GMDP. Sensitivity induced factors in tumor bearing mice sera have mol. weight more than 50 kDa. This action was partially abolished by indomethacin.