Formation and Stability of Prebiotically Relevant Vesicular Systems in Terrestrial Geothermal Environments.

Terrestrial geothermal fields and oceanic hydrothermal vents are considered as candidate environments for the emergence of life on Earth. Nevertheless, the ionic strength and salinity of oceans present serious limitations for the self-assembly of amphiphiles, a process that is fundamental for the formation of first protocells. Consequently, we systematically characterized the efficiency of amphiphile assembly, and vesicular stability, in terrestrial geothermal environments, both, under simulated laboratory conditions and in hot spring water samples (collected from Ladakh, India, an Astrobiologically relevant site). Combinations of prebiotically pertinent fatty acids and their derivatives were evaluated for the formation of vesicles in aforesaid scenarios. Additionally, the stability of these vesicles was characterized over multiple dehydration-rehydration cycles, at elevated temperatures. Among the combinations that were tested, mixtures of fatty acid and its glycerol derivatives were found to be the most robust, also resulting in vesicles in all of the hot spring waters that were tested. Importantly, these vesicles were stable at high temperatures, and this fatty acid system retained its vesicle forming propensity, even after multiple cycles of dehydration-rehydration. The remaining systems, however, formed vesicles only in bicine buffer. Our results suggest that certain prebiotic compartments would have had a selective advantage in terrestrial geothermal niches. Significantly, our study highlights the importance of validating results that are obtained under 'buffered' laboratory conditions, by verifying their plausibility in prebiotically analogous environments.

Incidence of cystoid macular oedema in diabetic patients after phacoemulsification and free radical link to its pathogenesis.

PURPOSE: Postoperative onset of cystoid macular oedema (CME) in diabetic patients after cataract surgery is a frequent problem in working-age adults worldwide. Here, we investigate the postoperative development of CME in diabetic patients after undergoing phacoemulsification with other ailing factors associated with CME. METHODS: This prospective study included 65 Type 2 diabetic patients with no diabetic retinopathy (DR), mild to moderate DR, moderate to severe DR and proliferative DR who underwent phacoemulsification surgery. Indirect ophthalmoscopy, fluorescein angiograms and optical coherence tomography were taken for a period of 8 weeks postoperatively to determine visual outcome and development of CME. Serum samples were collected for the measurement of antioxidants and reactive oxygen species (ROS) levels. RESULTS: Our data showed that CME occurred postoperatively in 47% without pre-existing DR and 55% of eyes with pre-existing DR (p<005). Positive association was noticed between morbid conditions, like hypertension (p<0.01) and diabetic nephropathy (p<0.05), and postoperative incidence of CME. The activity of antioxidant enzymes in patients with DR was found to be lower as compared with diabetic (D) patients, but catalase activity was recorded the maximum in these patients. The ROS activity was recorded highest in the serum samples of DR becoming CME positive. CONCLUSIONS: The present results suggest that after phacoemulsification, the chance of development of CME in DR is more as compared to D. Moreover, the development of CME is significantly associated with decrease in antioxidant levels, increased ROS activities, hypertension, diabetic nephropathy, and hyperlipidaemia.

Selective imaging of quorum sensing receptors in bacteria using fluorescent Au nanocluster probes surface functionalized with signal molecules.

Fluorescent ultrasmall gold clusters decorated with bacterial quorum sensing signal molecules, acyl homoserine lactone, are synthesized. These fluorescent probes are found to have emission in the near-infrared spectral region advantageous for bioimaging. Imaging studies using different strains of bacteria with and without acyl homoserine lactone receptors with the aid of confocal microscopy have shown that the probe interacts preferentially with cells possessing these receptors. This indicates that, with appropriate surface functionalization, the Au clusters can be used for receptor specific detection with enhanced selectivity.