National Institute of Oceanography, India

About: National Institute of Oceanography, India is a facility organization based out in Panjim, Goa, India. It is known for research contribution in the topics: Monsoon & Population. The organization has 4713 authors who have published 6927 publications receiving 174272 citations.

Biochemical diversification through foreign gene expression in bdelloid rotifers.

Abstract: Bdelloid rotifers are microinvertebrates with unique characteristics: they have survived tens of millions of years without sexual reproduction; they withstand extreme desiccation by undergoing anhydrobiosis; and they tolerate very high levels of ionizing radiation. Recent evidence suggests that subtelomeric regions of the bdelloid genome contain sequences originating from other organisms by horizontal gene transfer (HGT), of which some are known to be transcribed. However, the extent to which foreign gene expression plays a role in bdelloid physiology is unknown. We address this in the first large scale analysis of the transcriptome of the bdelloid Adineta ricciae: cDNA libraries from hydrated and desiccated bdelloids were subjected to massively parallel sequencing and assembled transcripts compared against the UniProtKB database by blastx to identify their putative products. Of ∼29,000 matched transcripts, ∼10% were inferred from blastx matches to be horizontally acquired, mainly from eubacteria but also from fungi, protists, and algae. After allowing for possible sources of error, the rate of HGT is at least 8%–9%, a level significantly higher than other invertebrates. We verified their foreign nature by phylogenetic analysis and by demonstrating linkage of foreign genes with metazoan genes in the bdelloid genome. Approximately 80% of horizontally acquired genes expressed in bdelloids code for enzymes, and these represent 39% of enzymes in identified pathways. Many enzymes encoded by foreign genes enhance biochemistry in bdelloids compared to other metazoans, for example, by potentiating toxin degradation or generation of antioxidants and key metabolites. They also supplement, and occasionally potentially replace, existing metazoan functions. Bdelloid rotifers therefore express horizontally acquired genes on a scale unprecedented in animals, and foreign genes make a profound contribution to their metabolism. This represents a potential mechanism for ancient asexuals to adapt rapidly to changing environments and thereby persist over long evolutionary time periods in the absence of sex.

Multi-component adsorption of Pb(II), Cd(II), and Ni(II) onto Egyptian Na-activated bentonite; equilibrium, kinetics, thermodynamics, and application for seawater desalination

Abstract: The adsorption potential of the Egyptian Na-activated bentonite (Na-AB) to remove Pb(II), Cd(II), and Ni(II) from synthetic ternary-ion solutions and contaminated seawater, was investigated for the first time. In this study, natural Egyptian Ca-bentonite was activated to Na-AB, which then was characterized using XRF, XRD, FT-IR, and BET. The adsorption process was strongly influenced by pH, contact time, adsorbent dose, metal concentration, agitation speed, and temperature. The isotherm equations due to Langmuir and Freundlich isotherm models showed good fits with the experimental data. Na-AB has a Langmuir monolayer capacity in a decreasing order of; Pb(II) (5.43 mg/g) > Cd(II) (3.14 mg/g) > Ni(II) (2.77 mg/g), these are considered high capacity values relative to the initial concentration (10 mg/L of each metal). The adsorption selectivity was interpreted by means of atomic radii, charge density and hydration enthalpy. The multi-component adsorption kinetics was more accurately described by pseudo-second-order model. The intraparticle diffusion model gave multi-linear curves, so more than one-step controlled the adsorption process. Activation energy was calculated as 17.54, 13.73, and 28.66 kJ mol −1 for Pb(II), Cd(II), and Ni(II) respectively, suggesting physical adsorption. Thermodynamic parameters at different temperatures (290–328) K showed that (i) Pb(II) adsorption was spontaneous and exothermic, (ii) Cd(II) adsorption was non-spontaneous and endothermic, (iii) Ni(II) adsorption was non-spontaneous and exothermic. Application study on polluted seawater, showed removal efficiency within range of 92–100% not only for Pb(II), Cd(II), and Ni(II) but also for other co-existing metals like Cu(II), Mn(II), Cr(III), and Zn(II).

Resonant Interactions between Planetary Waves

Abstract: In contrast to surface gravity waves, planetary waves can interact resonantly at the second order. Hence triplets of planetary waves may occur which are in resonance with each other. For simplicity the situation is studied first on a $\beta$ plane. The geometrical conditions for two waves to form a triplet with a given third wave are determined, and so also is the rate of energy transfer. Some conservation theorems are proved. The analysis allows for a non-zero horizontal divergence of the motion. For waves which cover a complete sphere it is shown that the resonant interactions between three different harmonic components take place, if at all, in the neighbourhoods of two latitude circles, situated symmetrically north and south of the equator.

Historical records of coastal eutrophication-induced hypoxia

Abstract: . Under certain conditions, sediment cores from coastal settings subject to hypoxia can yield records of environmental changes over time scales ranging from decades to millennia, sometimes with a resolution of as little as a few years. A variety of biological and geochemical indicators (proxies) derived from such cores have been used to reconstruct the development of eutrophication and hypoxic conditions over time. Those based on (1) the preserved remains of benthic organisms (mainly foraminiferans and ostracods), (2) sedimentary features (e.g. laminations) and (3) sediment chemistry and mineralogy (e.g. presence of sulphides and redox-sensitive trace elements) reflect conditions at or close to the seafloor. Those based on (4) the preserved remains of planktonic organisms (mainly diatoms and dinoflagellates), (5) pigments and lipid biomarkers derived from prokaryotes and eukaryotes and (6) organic C, N and their stable isotope ratios reflect conditions in the water column. However, the interpretation of these indicators is not straightforward. A central difficulty concerns the fact that hypoxia is strongly correlated with, and often induced by, organic enrichment caused by eutrophication, making it difficult to separate the effects of these phenomena in sediment records. The problem is compounded by the enhanced preservation in anoxic and hypoxic sediments of organic microfossils and biomarkers indicating eutrophication. The use of hypoxia-specific proxies, such as the trace metals molybdenum and rhenium and the bacterial biomarker isorenieratene, together with multi-proxy approaches, may provide a way forward. All proxies of bottom-water hypoxia are basically qualitative; their quantification presents a major challenge to which there is currently no satisfactory solution. Finally, it is important to separate the effects of natural ecosystem variability from anthropogenic effects. Despite these problems, in the absence of historical data for dissolved oxygen concentrations, the analysis of sediment cores can provide plausible reconstructions of the temporal development of human-induced hypoxia, and associated eutrophication, in vulnerable coastal environments.