Atmospheric CH4 oxidation by Arctic permafrost and mineral cryosols as a function of water saturation and temperature.

The response of methanotrophic bacteria capable of oxidizing atmospheric CH4 to climate warming is poorly understood, especially for those present in Arctic mineral cryosols. The atmospheric CH4 oxidation rates were measured in microcosms incubated at 4 °C and 10 °C along a 1-m depth profile and over a range of water saturation conditions for mineral cryosols containing type I and type II methanotrophs from Axel Heiberg Island (AHI), Nunavut, Canada. The cryosols exhibited net consumption of ~2 ppmv CH4 under all conditions, including during anaerobic incubations. Methane oxidation rates increased with temperature and decreased with increasing water saturation and depth, exhibiting the highest rates at 10 °C and 33% saturation at 5 cm depth (260 ± 60 pmol CH4 gdw-1 d-1 ). Extrapolation of the CH4 oxidation rates to the field yields net CH4 uptake fluxes ranging from 11 to 73 µmol CH4  m-2 d-1 , which are comparable to field measurements. Stable isotope mass balance indicates ~50% of the oxidized CH4 is incorporated into the biomass regardless of temperature or saturation. Future atmospheric CH4 uptake rates at AHI with increasing temperatures will be determined by the interplay of increasing CH4 oxidation rates vs. water saturation and the depth to the water table during summer thaw.

An active atmospheric methane sink in high Arctic mineral cryosols.

Methane (CH4) emission by carbon-rich cryosols at the high latitudes in Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance. This work employs CH4 flux measurements in the field and under laboratory conditions to show that the mineral cryosols at Axel Heiberg Island in the Canadian high Arctic consistently consume atmospheric CH4. Omics analyses present the first molecular evidence of active atmospheric CH4-oxidizing bacteria (atmMOB) in permafrost-affected cryosols, with the prevalent atmMOB genotype in our acidic mineral cryosols being closely related to Upland Soil Cluster α. The atmospheric (atm) CH4 uptake at the study site increases with ground temperature between 0 °C and 18 °C. Consequently, the atm CH4 sink strength is predicted to increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrate that acidic mineral cryosols are a previously unrecognized potential of CH4 sink that requires further investigation to determine its potential impact on larger scales. This study also calls attention to the poleward distribution of atmMOB, as well as to the potential influence of microbial atm CH4 oxidation, in the context of regional CH4 flux models and global warming.

PSGR, a novel prostate-specific gene with homology to a G protein-coupled receptor, is overexpressed in prostate cancer.

PSGR, a new prostate tissue-specific gene with homology to the G protein-coupled odorant receptor gene family, has been identified. Here we report the characteristics of the predicted protein sequence of PSGR and its prostate tissue specificity and expression profile in human prostate cancer and matched normal tissues. Using multiple tissue Northern blots from over 50 different tissues, PSGR expression was restricted to human prostate tissues. Paired normal and tumor specimens from 52 primary prostate cancers, obtained by laser capture microdissection or manual microdissection, were analyzed for PSGR expression by semiquantitative and real-time PCR assays. The differential expression of PSGR between normal and tumor tissues was highly significant (P < 0.001), and 32 of 52 (62%) matched prostate specimens exhibited tumor-associated overexpression of PSGR. Of note, there was very little or no expression of PSGR in many normal specimens in comparison with the generally high expression of PSGR seen in matched tumor specimens. In situ hybridization assays showed restricted PSGR expression in the epithelial cells of the normal and tumor tissue sections. Restricted expression of PSGR in prostatic epithelial cells, overexpression of the PSGR in a significant percentage of prostate cancers, and the predicted protein sequence of PSGR with seven transmembrane domains provide a foundation for future studies evaluating the potential of PSGR as a prostate cancer gene expression marker and the utility of PSGR protein as a novel target for developing immunotherapeutic strategies for prostate cancer.

Multiple p53 protein isoforms and formation of oligomeric complexes with heat shock proteins Hsp70 and Hsp90 in the human mammary tumor, T47D, cell line.

At least eleven isoforms of p53 protein were observed in a human mammary tumor cell line. T47D. Comparative 33P and 35S incorporation analysis showed an equal distribution of P53 isoforms within cytoplasmic and nuclear compartments, although phosphorylation was unequal among isoforms and the most basic p53 species was unphosphorylated. Using a combination of immunoprecipitation with monoclonal antibodies for p53 and heat shock proteins Hsp70 & Hsp90, and two-dimensional gel electrophoretic analysis, T47D p53 protein oligomers were observed with several species of Hsp70 and Hsp90. The p53/Hsp70/Hsp90 aggregate dissociates after nuclear translocation. Immunoprecipitation of Hsp70 and Hsp90 using monoclonal antibodies showed formation of a heteroligomer between Hsp70 and Hsp90 in cytoplasm but not nucleus. This suggests these Hsp proteins can form a complex in the cytoplasm but undergo a conformational change after nuclear translocation such that Hsp/Hsp binding sites are no longer recognized. These data indicate T47D cells have multiple p53 precursor molecules probably at different stages of phosphorylation, and which may be sequestered from proteases by binding to Hsp proteins. Hsp proteins also can heterocomplex in the cytoplasm, also possibly as protection against protease degradation until bound to p53. After translocation, p53 is freed from Hsp proteins for binding to DNA where Hsp70 and Hsp90 are no longer able to form a nuclear complex probably rendering Hsp's labile to proteolysis.