Microbial Fuel Cells Applied to the Metabolically-Based Detection of Extraterrestrial Life

Since the 1970's, when the Viking spacecrafts carried out experiments aimed to the detection of microbial metabolism on the surface of Mars, the search for nonspecific methods to detect life in situ has been one of the goals of astrobiology. It is usually required that the methodology can detect life independently from its composition or form, and that the chosen biological signature points to a feature common to all living systems, as the presence of metabolism. In this paper we evaluate the use of Microbial Fuel Cells (MFCs) for the detection of microbial life in situ. MFCs are electrochemical devices originally developed as power electrical sources, and can be described as fuel cells in which the anode is submerged in a medium that contains microorganisms. These microorganisms, as part of their metabolic process, oxidize organic material releasing electrons that contribute to the electric current, which is therefore proportional to metabolic and other redox processes. We show that power and current density values measured in MFCs using microorganism cultures or soil samples in the anode are much larger than those obtained using a medium free of microorganisms or sterilized soil samples, respectively. In particular, we found that this is true for extremophiles, usually proposed to live in extraterrestrial environments. Therefore, our results show that MFCs have the potential to be used to detect microbial life in situ.Comment: To be published in Astrobiolog

Pygo2 expands mammary progenitor cells by facilitating histone H3 K4 methylation

Recent studies have unequivocally identified multipotent stem/progenitor cells in mammary glands, offering a tractable model system to unravel genetic and epigenetic regulation of epithelial stem/progenitor cell development and homeostasis. In this study, we show that Pygo2, a member of an evolutionarily conserved family of plant homeo domain–containing proteins, is expressed in embryonic and postnatal mammary progenitor cells. Pygo2 deficiency, which is achieved by complete or epithelia-specific gene ablation in mice, results in defective mammary morphogenesis and regeneration accompanied by severely compromised expansive self-renewal of epithelial progenitor cells. Pygo2 converges with Wnt/β-catenin signaling on progenitor cell regulation and cell cycle gene expression, and loss of epithelial Pygo2 completely rescues β-catenin–induced mammary outgrowth. We further describe a novel molecular function of Pygo2 that is required for mammary progenitor cell expansion, which is to facilitate K4 trimethylation of histone H3, both globally and at Wnt/β-catenin target loci, via direct binding to K4-methyl histone H3 and recruiting histone H3 K4 methyltransferase complexes

Ten-year survival of Ugandan infants after myelomeningocele closure.

OBJECTIVE Myelomeningocele (MM) is a neural tube defect complicated by neurological deficits below the level of the spinal lesion and, in many cases, hydrocephalus. Long-term survival of infants treated for MM in a low- and middle-income country has never been reported. This retrospective cohort study reports 10-year outcomes and factors affecting survival for infants undergoing MM repair at CURE Children's Hospital of Uganda. METHODS Patients were traced by telephone or home visit. Survival was estimated using the Kaplan-Meier method. Multivariate survival was analyzed using the Cox proportional hazards model, investigating the following variables: sex, age at surgery, weight-for-age at surgery, motor level, and presence and management of hydrocephalus. RESULTS A total of 145 children underwent MM repair between 2000 and 2004; complete data were available for 133 patients. The probability of 10-year survival was 55%, with 78% of deaths occurring in the first 5 years. Most of the deaths were not directly related to MM; infection and neglect were most commonly described. Lesions at motor level L-2 or above were associated with increased mortality (HR 3.176, 95% CI 1.557-6.476). Compared with repair within 48 hours of birth, surgery at 15-29 days was associated with increased mortality (HR 9.091, 95% CI 1.169-70.698). CONCLUSIONS Infants in low- and middle-income countries with MM can have long-term survival with basic surgical intervention. Motor level and age at surgery were significant factors influencing outcome. Education of local health care workers and families to ensure both urgent referral for initial treatment and subsequent access to basic medical care are essential to survival