Birds and neotropical mistletoes: effects on seedling recruitment

Two groups of neotropical mistletoes differ in fruit structure and consequently in the manner their seeds are deposited by avian frugivores. Birds defecate seeds of one group in clumps, but deposit seeds of the other group singly by regurgitation. A significant proportion of adult plants of both species were found growing alone, indicating a higher mortality with seed clumping.     

Isolation of methanogens from Arabian sea sediments and their salt tolerance

Abstract Sea sediments in tropical regions have been less studied for methanogenesis and methanogens present therein. Three species of methanogens viz. Methanobacterium bryantii, Methanococcus voltae and Methanosarcina barkeri were isolated from Arabian sea sediments collected near the west coast of India. Maximum methane was formed by M. voltae at 3.0% (w/v) NaCl and other two methanogens at 0.06% (w/v) NaCl. M. bryantii and M. barkeri tolerated 2.5 and 3.0% (w/v) NaCl respectively due to which these methanogens must have survived in salt conditions of the sea sediments.     

Evaluation of PAHs concentration and cancer risk assessment on human health in a roadside soil: A case study

Abstract

An explanatory study was carried out to divulge the sources, contamination level of different classes of Polycyclic Aromatic Hydrocarbons (PAHs) distribution and the impact of vehicular traffic on the roadside soil by assessing incremental lifetime cancer risk at each site to understand the potential health risk of nearby residents along the National Highway-2 Delhi–Kolkata India. Comparison of the cancer risk assessment was performed using Monte Carlo simulation for the entire study area. The results revealed 90% cancer risk value of 6.40?×?10^?5 and 6.5?×?10^?5 for children and adults, respectively, whereas, without simulation the Total Cancer Risk (TCR) for adults was 6.925?×?10^?5 and 6.220?×?10^?5 for children, observed maximum at the location (S5). The dilemma of risk assessment indicating profoundly contaminated soil. Comparison of PAHs concentration with the background values of PAHs ranged from 1.478 to 27.493?mg kg^?1. The (IP/BgP) ratio specified that the PAHs content of the highway roadside sample is preponderate by diesel vehicle emission, biomass combustion and coal combustion. The study clearly revealed and advocated the influence of organic and inorganic pollution, which aggravates and causes health issues to the nearby inhabitants. This study could also be advantageous to similar consequences seen elsewhere in the world.     

Preparation of protoplasts from the cyanobacterium Spirulina platensis and a novel viability assay

A method is described for the isolation of protoplasts from the cyanobacterium Spirulina platensis using an elite strain (S.pl. FT 06) selected after screening. Trichomes of the cyanobacterium were treated with lysozyme (0.1%) for 28 h at room temperature in 0.03 mol l^-1 phosphate buffer (pH 6.8) with 0.5 mol l^-1 mannitol as the osmoticum. This resulted in an 80% yield of protoplasts. Cells were intact in their fine structure and viable as evidenced by a rapid and efficient viability assay using a novel mixture of fluorescein diacetate and calcofluor white.     

Simulating natural light and temperature cycles in the laboratory reveals differential effects on activity/rest rhythm of four Drosophilids

Recent studies under semi-natural conditions have revealed various unique features of activity/rest rhythms in Drosophilids that differ from those under standard laboratory conditions. An additional afternoon peak (A-peak) has been reported for Drosophila melanogaster and another species D. malerkotliana while D. ananassae exhibited mostly unimodal diurnal activity. To tease apart the role of light and temperature in mediating these species-specific behaviours of four Drosophilid species D. melanogaster, D. malerkotliana, D. ananassae, and Zaprionus indianus we simulated gradual natural light and/or temperature cycles conditions in laboratory. The pattern observed under semi-natural conditions could be reproduced in the laboratory for all the species under a variety of simulated conditions. D. melanogaster and D. malerkotliana showed similar patterns where as D. ananassae consistently exhibited predominant morning activity under almost all regimes. Z. indianus showed clearly rhythmic activity mostly when temperature cycles were provided. We find that gradually changing light intensities reaching a sufficiently high peak value can elicit A-peak in D. melanogaster, D. malerkotliana, and D. ananassae even at mild ambient temperature. Furthermore, we show that high mid-day temperature could induce A-peak in all species even under constant light conditions suggesting that this A-peak is likely to be a stress response.     

Impacts of hydrophobicity and ionicity of phendione-based cobalt(II)/(III) complexes on binding with bovine serum albumin

Abstract

For efficient designing of metallodrugs, it is imperative to analyse the binding affinity of those drugs with drug-carrying serum albumins to comprehend their structure–activity correlation for biomedical applications. Here, cobalt(II) and cobalt(III) complexes comprising three phendione ligands, [Co(phendione)₃]Cl₂ (1) and [Co(phendione)₃]Cl₃ (2), where, phendione = 1,10-phenanthroline-5,6-dione, has been chosen to contrast the impact of their hydrophobicity and ionicity on binding with bovine serum albumin (BSA) through spectrophotometric titrations. The attained hydrophobicity values using octanol/water partition coefficient method manifested that complex 1 is more hydrophobic than complex 2, which could be attributed to lesser charge on its coordination sphere. The interaction of complexes 1 and 2 with BSA using steady state fluorescence studies revealed that these complexes quench the intrinsic fluorescence of BSA through static mechanism, and the extent of quenching and binding parameters are higher for complex 2. Further thermodynamics of BSA-binding studies revealed that complexes 1 and 2 interact with BSA through hydrophobic and hydrogen bonding/van der Waals interactions, respectively. Further, UV–visible absorption, circular dichroism and synchronous fluorescence studies confirmed the occurrence of conformational and microenvironmental changes in BSA upon binding with complexes 1 and 2. Molecular docking studies have also shown that complex 2 has a higher binding affinity towards BSA as compared to complex 1. This sort of modification of ionicity and hydrophobicity of metal complexes for getting desirable binding mode/strength with drug transporting serum albumins will be a promising pathway for designing active and new kind of metallodrugs for various biomedical applications.

Communicated by Ramaswamy H. Sarma