Variance and potential niche separation of microbial communities in subseafloor sediments off Shimokita Peninsula, Japan.

Subseafloor pelagic sediments with high concentrations of organic matter form habitats for diverse microorganisms. Here, we determined depth profiles of genes for SSU rRNA, mcrA, dsrA and amoA from just beneath the seafloor to 363.3 m below the seafloor (mbsf) using core samples obtained from the forearc basin off the Shimokita Peninsula. The molecular profiles were combined with data on lithostratigraphy, depositional age, sedimentation rate and pore-water chemistry. The SSU rRNA gene tag structure and diversity changed at around the sulfate-methane transition zone (SMTZ), whereas the profiles varied further with depth below the SMTZ, probably in connection with the variation in pore-water chemistry. The depth profiles of diversity and abundance of dsrA, a key gene for sulfate reduction, suggested the possible niche separations of sulfate-reducing populations, even below the SMTZ. The diversity and abundance patterns of mcrA, a key gene for methanogenesis/anaerobic methanotrophy, suggested a stratified distribution and separation of anaerobic methanotrophy and hydrogenotrophic or methylotrophic methanogensis below the SMTZ. This study provides novel insights into the relationships between the composition and function of microbial communities and the chemical environment in the nutrient-rich continental margin subseafloor sediments, which may result in niche separation and variability in subseafloor microbial populations.

Discriminative detection and enumeration of microbial life in marine subsurface sediments.

Detection and enumeration of microbial life in natural environments provide fundamental information about the extent of the biosphere on Earth. However, it has long been difficult to evaluate the abundance of microbial cells in sedimentary habitats because non-specific binding of fluorescent dye and/or auto-fluorescence from sediment particles strongly hampers the recognition of cell-derived signals. Here, we show a highly efficient and discriminative detection and enumeration technique for microbial cells in sediments using hydrofluoric acid (HF) treatment and automated fluorescent image analysis. Washing of sediment slurries with HF significantly reduced non-biological fluorescent signals such as amorphous silica and enhanced the efficiency of cell detachment from the particles. We found that cell-derived SYBR Green I signals can be distinguished from non-biological backgrounds by dividing green fluorescence (band-pass filter: 528/38 nm (center-wavelength/bandwidth)) by red (617/73 nm) per image. A newly developed automated microscope system could take a wide range of high-resolution image in a short time, and subsequently enumerate the accurate number of cell-derived signals by the calculation of green to red fluorescence signals per image. Using our technique, we evaluated the microbial population in deep marine sediments offshore Peru and Japan down to 365 m below the seafloor, which provided objective digital images as evidence for the quantification of the prevailing microbial life. Our method is hence useful to explore the extent of sub-seafloor life in the future scientific drilling, and moreover widely applicable in the study of microbial ecology.

Kidney disease quality of life of Japanese dialysis patients who desire administration of sildenafil and the treatment of erectile dysfunction using sildenafil.

Erectile dysfunction (ED) is common among patients on dialysis therapy. In the present study, we attempted administration of sildenafil to Japanese patients undergoing dialysis. In order to diagnose ED before prescribing sildenafil, we assessed the hemodialysis patients who desired sildenafil by using the five items version of the International Index of Erectile Function (IIEF-5). In addition, the characteristics of the quality of life in Japanese hemodialysis patients who desired sildenafil were assessed using the kidney disease quality of life (KDQOL). To all 37 male subjects (mean age of 53.8 +/- 10.4 years) attending the Outpatient Hemodialysis Unit at Atsugi Clinic (Atsugi City, Japan), it was explained by their primary doctor that the treatment of ED with sildenafil was possible. As a result, 10 patients (27.0%) desired the treatment. For eight patients, ED was diagnosed by IIEF-5 prior to prescription of sildenafil. The mean IIEF-5 scores were 6.13 +/- 4.67 points. Sildenafil was prescribed to five patients (three diabetic, two non-diabetic) and sexual function was improved in three cases. The main adverse effect was found to be ventricular arrhythmia in one case. As for KDQOL, the group desiring sildenafil showed significantly high values in Dialysis Staff Encouragement and Patient Satisfaction. Among the other nine dialysis patients (five diabetic, four non-diabetic; mean age of 58.1 +/- 8.9 years) who visited the ED department of Ishida Hospital (Asahikawa City, Japan), sildenafil was effective for all non-diabetic patients (100%) and for only one diabetic patient (20%). Among all 14 patients at Atsugi Clinic and Ishida Hospital, sildenafil efficacy rates were 83.3% for non-diabetic patients and 37.5% for diabetic patients. Non-diabetic patients without the side-effects were all responders for the sildenafil treatment. The patients who relied on the dialysis staff and were more satisfied with the general treatment in the dialysis institute desired the administration of sildenafil under the present circumstances wherein the dialysis population had few experiences of sildenafil treatment. Diabetic status is thought to be a negative factor for the response of sildenafil treatment in dialysis patients.