The effects of planktivorous fishes on the plankton community in a eutrophic lake

Stocking silver carp, a phytoplankton feeder, and bighead carp, an omnivorous plankton feeder, into an eutrophic lake at high densities caused a dramatic change in the lake ecosystem.Microcystis, which had been dominant in summer and a main food of the fishes decreased markedly, and green algae smaller than 10 μm then became dominant. Consequently, chlorophyll-a per unit area decreased slightly, while the rate of production was higher than that in the previous years. As the total density of the fishes increased (from 0.09 to 0.11 fish m⁻²), the growth of silver carp was retarded, while that of bighead carp increased.Microcystis, was unable to become dominant due to increased grazing pressure by the fishes, and small green algae became dominant. The lake conditions thus became more favourable for zooplankters which selectively consumed small green algae, and accordingly, the production of zooplankton rose. Bighead carp consumed more animal food, which they assimilate at a higher rate than plant food, and grew better in spite of the fact that the fish density increased. The feeding rate of silver carp was greatly reduced because the green algae were too small to ingest, and the fish therefore grew poorly. Results of a computer simulation of a model consisting of five compartments, representing the blue-green algae, green algae, zooplankton, silver and bighead carp, support the food-web change observed in the lake.     

Measurement of chronic toxicity using the opossum shrimpMysidopsis bahia

The chronic toxicity of silver and endosulfan to the opossum shrimpMysidopsis bahia was determined using continuous-flow bioassays. The 28-day bioassays measured survival, fecundity, and growth (length and weight measurements). Maximum acceptable toxicant concentrations (MATC) were estimated from measured toxicant concentrations. MATC values were similar using either brood size or growth as a criterion for sublethal effects. As an alternative to the determination of fecundity impairment, measurement of growth reduction in response to exposure to toxicants may provide a useful tool in the assessment of chronic toxicity inMysidopsis life-cycle bioassays.     

Effect of plant growth regulators on evolution of ethylene and methane by different explants of chickpea

Shoot tips, cotyledonary nodes and hypocotyls of chickpea (Cicer arietinum L.) were grown on 3 media: plant induction medium (PIM), callus induction medium (CIM), and shoot induction medium (SIM). Maximum growth and differentiation was seen in PIM, whereas minimum was observed in CIM. Shoot tips which differentiated to multiple shoots evolved negligible amounts of ethylene. Maximum ethylene evolution was recorded by hypocotyls in PIM. Ethylene appears to have stimulatory effect on shoot bud differentiation in cotyledonary nodes. But in hypocotyls, increased ethylene inhibited growth and differentiation. Calli on media containing only auxin (PIM) evolved significantly more ethylene, whereas those on media with cytokinin (SIM) evolved more methane. Callus forming explants like cotyledonary nodes and hypocotyls evolve more ethylene than shoot tips. This revised version was published online in August 2006 with corrections to the Cover Date.     

Gold Toning Improves the Visualization of Nucleolar Organizer Regions in Paraffin Embedded Tissues

A modification of the silver colloid technique for staining nucleolar organizer regions in paraffin embedded tissues is described. This modification involves the application of a gold toning step with subsequent gold reduction, if necessary, following incubation of sections in the standard silver colloid solution. Silver stained nucleolar organizer regions (AgNORs) in toned sections are more sharply delineated when compared to untoned controls. in high grade tumors the addition of the toning step results in significantly higher AgNOR counts due to the ability to discriminate more easily individual AgNORs in argyrophilic aggregates within the nucleus. It is recommended, because of enhanced visualization, that this modification of the silver colloid technique be used in studies involving quantification of AgNORs in tissue sections.     

Green synthesis and physiochemical characterization of nickel oxide nanoparticles: Interaction studies with Calf thymus DNA

One of the most promising applications of nanomaterials is that of nanobiosensors, using biomolecules such as nucleic acids as receptors. This study aimed to synthesize nickel oxide nanoparticles (NiO NPs) by an environmentally friendly green synthesis, using the extract of the herb Coriandrum sativum (coriander). The synthesized NPs were characterized using UV–Visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, X‐ray photon spectroscopy, field emission scanning electron microscopy coupled with energy dispersive spectroscopy, dynamic light scattering, zeta potential and transmission electron microscopy. All results confirmed the synthesis of pure, spherical, positively charged NiO NPs of around 95 nm in diameter with prominent hydroxyl groups attached to the surface. Furthermore, interaction studies of synthesized NiO NPs with calf thymus DNA (CT DNA) were performed using UV–Visible spectroscopy, UV–thermal melting, circular dichroism, and fluorescence spectroscopy. CT DNA served as a substitute for nucleic acid biosensors. All experimental studies indicated that the NiO NPs bound electrostatically with CT DNA. These studies may facilitate exploring the potential of NiO NP–nucleic acid conjugated materials to be used as nanobiosensors for various applications, especially in pharmacological, epidemiological, and environmental diagnostic applications, and in detection.     

Redox‐modulated colorimetric detection of ascorbic acid and alkaline phosphatase activity with gold nanoparticles

Gold nanoparticles (AuNPs) exhibit characteristic absorption peaks in the ultraviolet visible region due to their special surface plasmon resonance effect. This characteristic absorption peak would change with the relative colour varying from wine red to orange‐yellow upon sequential addition of ascorbic acid (AA) into the mixture of AuNPs and Ag(I). Similar observations also could be found when the hydrolysis product of sodium l ‐ascorbyl‐2‐phosphate with alkaline phosphatase (ALP) was used as an alternative to AA. Results of structure characterization confirmed that the phenomena were due to the reduction of Ag(I) to Ag(0) on the surface of AuNPs and the formation of core‐shell AuNPs@Ag. Therefore, a colorimetric assay for rapid visual detection of AA and ALP based on redox‐modulated silver deposition on AuNPs has been proposed. Under the optimal experimental conditions, the absorbance variation ΔA_{522 nm}/A_{370 nm} of AuNPs was proportional to the concentration of AA (5–60 μmol/L) and ALP (3–18 U/L) with the corresponding detection limit of 2.44 μmol/L for AA and 0.52 U/L for ALP. The assay showed excellent selectivity towards AA and ALP. Moreover, the assay has been applied to detect AA and ALP activity in real samples with satisfying results.     

Assessment of the potential bactericide effect of self‐cleaning floors: a proposed protocol

The antibacterial properties of self‐cleaning coatings are based on bactericide nanoparticles (NPs). Ecotoxicity of these NPs have been assessed mostly in suspension, using standard bioassays. Here a protocol is proposed to test actual coating samples, using the Vibrio fischeri bioluminescence inhibition bioassay. The protocol was designed to test bactericide properties of specially coated PVC floors being used in hospital environments under quasinatural conditions, such as prolonged exposure or room temperature. To take into consideration that the light output of the bacteria under prolonged exposure naturally changes, a correction factor is proposed.     

Anti-cancer activity of biosynthesized silver nanoparticles using Avicennia marina against A549 lung cancer cells through ROS/mitochondrial damages

The biosynthesized Ag NPs was synthesized by using marine mangrove plant extract Avicennia marina. The synthesized Ag NPs was confirmed by various physiochemical characterization including UV-spectrometer and XRD analysis. In addition, the shape and of the synthesized Ag NPs was morphologically identified by SEM initially and TEM finally. After confirmation, the anti-cancer property of synthesized Ag NPs was confirmed at 50 µg/mL concentration against A549 lung cancer cells by MTT assay. Further, the ability to stimulate the ROS generation and mitochondrial membrane at the IC₅₀ concentration of Ag NPs was confirmed by fluorescence microscopy using DCFH-DA and rhodamine 123 dyes respectively. Finally, the result was concluded that the synthesized Ag NPs has improved anti-cancer activity against A549 cells at lowest concentration.