Nonenzymatic RNA replication in a mixture of 'spent' nucleotides.

Nonenzymatic template-directed replication would have been affected by co-solutes in a heterogeneous prebiotic soup due to lack of enzymatic machinery. Unlike in contemporary biology, these reactions use chemically activated nucleotides, which undergo rapid hydrolysis forming nucleoside monophosphates ('spent' monomers). These co-solutes cannot extend the primer but continue to base pair with the template, thereby interfering with replication. We, therefore, aimed to understand how a mixture of 'spent' ribonucleotides would affect nonenzymatic replication. We observed the inhibition of replication in the mixture, wherein the predominant contribution came from the cognate Watson-Crick monomer, showing potential sequence dependence. Our study highlights how nonenzymatic RNA replication would have been directly affected by co-solutes, with ramifications for the emergence of functional polymers in an RNA World.

Prebiological Membranes and Their Role in the Emergence of Early Cellular Life.

Membrane compartmentalization is a fundamental feature of contemporary cellular life. Given this, it is rational to assume that at some stage in the early origins of life, membrane compartments would have potentially emerged to form a dynamic semipermeable barrier in primitive cells (protocells), protecting them from their surrounding environment. It is thought that such prebiological membranes would likely have played a crucial role in the emergence and evolution of life on the early Earth. Extant biological membranes are highly organized and complex, which is a consequence of a protracted evolutionary history. On the other hand, prebiotic membrane assemblies, which are thought to have preceded sophisticated contemporary membranes, are hypothesized to have been relatively simple and composed of single chain amphiphiles. Recent studies indicate that the evolution of prebiotic membranes potentially resulted from interactions between the membrane and its physicochemical environment. These studies have also speculated on the origin, composition, function and influence of environmental conditions on protocellular membranes as the niche parameters would have directly influenced their composition and biophysical properties. Nonetheless, the evolutionary pathways involved in the transition from prebiological membranes to contemporary membranes are largely unknown. This review critically evaluates existing research on prebiotic membranes in terms of their probable origin, composition, energetics, function and evolution. Notably, we outline new approaches that can further our understanding about how prebiotic membranes might have evolved in response to relevant physicochemical parameters that would have acted as pertinent selection pressures on the early Earth.

A time-efficient model of spreading health awareness which also provides good experiential learning to medical students.

Background: Although alcohol and tobacco are leading causes of mortality and morbidity, their use continues to be common. We hypothesized that awareness about this issue can be spread in a time-efficient way if health talks are conducted within hospital premises itself. Furthermore, this could potentially provide good experiential learning to medical students. Methods: In this longitudinal study, we implemented such an awareness activity and evaluated the outcome. Students who showed interest to volunteer were helped to develop an in-depth understanding of the issue, through detailed presentation and discussions. They conducted health talks near the wards, with patients and their relatives, after routine college hours. An iterative process was used to improve the health talk, based on self-reflection and formative feedback. A pre- and post-self-assessment of students regarding their knowledge and skills on this issue was obtained. A structured, anonymous questionnaire was administered to the audience before and after three of the educational talks. Results: In 29 days, our team of 24 students gave 21 health talks reaching out to 1090 rural people. Pre-post analysis of audience showed improvement in their awareness level and many developed the motivation to quit their addictions. Self-rating of students across all knowledge domains increased by at least 2 points (scale of 1-7) and across all skill domains, it increased by 3 points (P < 0.0001). Conclusion: This model of conducting health talks in hospital premises can enable us to spread health awareness effectively, in a time-efficient and cost-effective way. Furthermore, this model can prove to be a novel and effective academic tool for grooming medical students.

On-demand hydrogen generation using nanosilicon: splitting water without light, heat, or electricity.

We demonstrate that nanosize silicon (~10 nm diameter) reacts with water to generate hydrogen 1000 times faster than bulk silicon, 100 times faster than previously reported Si structures, and 6 times faster than competing metal formulations. The H(2) production rate using 10 nm Si is 150 times that obtained using 100 nm particles, dramatically exceeding the expected effect of increased surface to volume ratio. We attribute this to a change in the etching dynamics at the nanoscale from anisotropic etching of larger silicon to effectively isotropic etching of 10 nm silicon. These results imply that nanosilicon could provide a practical approach for on-demand hydrogen production without addition of heat, light, or electrical energy.