Chemical interactions at noble metal nanoparticle surfaces - catalysis, sensors and devices

In this paper, a summary of some of the recent research efforts in our laboratory on chemical interactions at noble metal nanoparticle surfaces is presented. The article is divided into five sections, detailing with (i) interactions of simple halocarbons with gold and silver nanoparticle surfaces at room temperature by a new chemistry and the exploitation of this chemistry in the extraction of pesticides from drinking water, (ii) interaction of biologically important proteins such as Cyt c, hemoglobin and myoglobin as well as a model system, hemin with gold and silver nanoparticles and nanorods forming nano-bio conjugates and their surface binding chemistry, (iii) formation of polymer-nano composites with tunable optical properties and temperature sensing characteristics by single and multi-step methodologies, (iv) nanomaterials-based flow sensors and (v) composites of noble metal nanoparticles and metallic carbon nanotubes showing visible fluorescence induced by metal-semiconductor transition

Effect of Testosterone on Insulin Stimulated IRS1 Ser Phosphorylation in Primary Rat Myotubes—A Potential Model for PCOS-Related Insulin Resistance

Polycystic ovary syndrome (PCOS) is characterized by a hyperandrogenic state and frequently develops skeletal muscle insulin resistance. We determined whether testosterone adversely affects insulin action by increasing serine phosphorylation of IRS-1(636/639) in differentiated rat skeletal muscle myotubes. The phosphorylation of Akt, mTOR, and S6K, downstream targets of the PI3-kinase-IRS-1 complex were also studied.Primary differentiated rat skeletal muscle myotubes were subjected to insulin for 30 min after 16-hour pre-exposure to either low (20 ng/ml) or high (200 ng/ml) doses of testosterone. Protein phosphorylation of IRS-1 Ser(636/639), Akt Ser(473), mTOR-Ser(2448), and S6K-Thr(389) were measured by Western blot with signal intensity measured by immunofluorescence.Cells exposed to 100 nM of insulin had increased IRS-1 Ser(636/639) and Akt Ser(473) phosphorylation. Cells pre-exposed to low-dose testosterone had significantly increased insulin-induced mTOR-Ser(2448) and S6K-Thr(389) phosphorylation (p<0.05), and further increased insulin-induced IRS-1 Ser(636/639) phosphorylation (p = 0.042) compared to control cells. High-dose testosterone pre-exposure attenuated the insulin-induced mTOR-Ser(2448) and S6K-Thr(389) phosphorylation.The data demonstrated an interaction between testosterone and insulin on phosphorylation of intracellular signaling proteins, and suggests a link between a hyperandrogenic, hyperinsulinemic environment and the development of insulin resistance involving serine phosphorylation of IRS-1 Ser(636/639). These results may guide further investigations of potential mechanisms of PCOS-related insulin resistance

Toxicity of some heavy metals to copepods <i>Acartia spinicauda</i> and <i>Tortanus forcipatus</i>

382-383Copper was most toxic to the species tested followed by cadmium and zinc. The estuarine species. Acartia spinicauda was more sensitive to the toxicants that the marine species Tortanus forcipatus. The 48 hr LC50 values are presented

Maturation of the penaeid prawn Metapenaeus moyebi in Mandovi estuary, Goa

151-152Metapenaeus moyebi contributed a good share of penaeid prawn population in the Mandovi estuary of Goa throughout the year. Both males and females of this species with fully mature gonads were observed in the estuary, suggesting possible spawning in the estuary

Zooplankton composition of the Kalpeni and Agatti atolls, Lakshadweep archipelago

151-154Composition of zooplankton in the lagoons was quite different from that of the sea and to a large extent, was independent of oceanic influence. While copepods were dominant in the sea, meroplankton, particularly brachyuran zoeae constituted the largest group in the lagoons. Zooplankton standing stock was lower in the lagoons as compared to the sea. Among copepods, calanoids showed higher abundance in the sea whereas harpacticoids and cyclopoids dominated the Kalpeni and Agatti lagoons respectively. Several striking similarities were observed in the zooplankton composition between the coral and coastal lagoons

Thermocline & Zooplankton distribution

262-265Distribution of zooplankton above and below the thermocline layer was studied in Feb. 1979 from the Andaman Sea. Zooplankton biomass and groups like Chaetognatha, Appendicularia, Decapoda. Thaliacea and Euphausiacea showed, higher aggregation above the thermocline layer. While many of the species showed the same trend. Ostracoda and many of the less common species were usually in greater abundance below the thermocline. Thermocline acted as a barrier in vertical movements in some species. Vertical migration of zooplankton in relation to discontinuity layer is discussed

Zooplankton Abundance of the Andaman Sea

258-261Zooplankton biomass and abundance of major groups from the Andaman Sea in February 1979 are presented. Average zooplankton biomass is 5.6 ml/100 m3 and is generally poor compared to reported values from east and west coasts of India. Copepoda forms the dominant component followed by Chaetognatha and Tunicata Estimates of zooplankton biomass to dry weight and to organic carbon content are made. The average standing crop of zooplankton is 288.8 mg Cm2 for the upper 200 m column