A PCR-Based Survey of Methane-Cycling Archaea in Methane-Soaked Subsurface Sediments of Guaymas Basin, Gulf of California

The Guaymas Basin in the Gulf of California is characterized by active seafloor spreading, the rapid deposition of organic-rich sediments, steep geothermal gradients, and abundant methane of mixed thermogenic and microbial origin. Subsurface sediment samples from eight drilling sites with distinct geochemical and thermal profiles were selected for DNA extraction and PCR amplification to explore the diversity of methane-cycling archaea in the Guaymas Basin subsurface. We performed PCR amplifications with general (mcrIRD), and ANME-1 specific primers that target the alpha (α) subunit of methyl coenzyme M reductase (mcrA). Diverse ANME-1 lineages associated with anaerobic methane oxidation were detected in seven out of the eight drilling sites, preferentially around the methane-sulfate interface, and in several cases, showed preferences for specific sampling sites. Phylogenetically, most ANME-1 sequences from the Guaymas Basin subsurface were related to marine mud volcanoes, seep sites, and the shallow marine subsurface. The most frequently recovered methanogenic phylotypes were closely affiliated with the hyperthermophilic Methanocaldococcaceae, and found at the hydrothermally influenced Ringvent site. The coolest drilling site, in the northern axial trough of Guaymas Basin, yielded the greatest diversity in methanogen lineages. Our survey indicates the potential for extensive microbial methane cycling within subsurface sediments of Guaymas Basin

Survey of helium in soil gases of Long Valley, Califorina

Soil and water samples in and around the Long Valley geothermal area, Mono County, California, were collected and analyzed for helium by means of a modified mass spectrometer leak detector to see what relationship helium concentrations might have to geothermal features of the area, and to previously studied mercury anomalies in the area. Anomalously high concentrations of helium occurred over part of a major Sierra Nevada frontal fault and over other faults outside of the caldera. Anomalously low concentrations of helium occurred in several areas of high mercury concentrations, which were also areas of hydrothermal alteration. Quantities of helium exsolved from water samples did not fit any pattern

Progressive dopaminergic alterations and mitochondrial abnormalities in LRRK2 G2019S knock in mice

Mutations in the LRRK2 gene represent the most common genetic cause of late onset Parkinson’s disease. The physiological and pathological roles of LRRK2 are yet to be fully determined but evidence points towards LRRK2 mutations causing a gain in kinase function, impacting on neuronal maintenance, vesicular dynamics and neurotransmitter release. To explore the role of physiological levels of mutant LRRK2, we created knock in mice harboring the most common LRRK2 mutation G2019S in their own genome. We have performed comprehensive dopaminergic, behavioral and neuropathological analyses in this model up to 24 months of age. We find elevated kinase activity in the brain of both heterozygous and homozygous mice. Although normal at 6 months, by 12 months of age, basal and pharmacologically induced extracellular release of dopamine is impaired in both heterozygous and homozygous mice, corroborating previous findings in transgenic models over-expressing mutant LRRK2. Via in vivo microdialysis measurement of basal and drug- evoked extracellular release of dopamine and its metabolites, our findings indicate that exocytotic release from the vesicular pool is impaired. Furthermore, profound mitochondrial abnormalities are evident in the striatum of older homozygous G2019S mice, which are consistent with mitochondrial fission arrest. We anticipate the G2019S will be a useful pre-clinical model for further evaluation of early mechanistic events in LRRK2 pathogenesis and for second-hit approaches to model disease progression