Comprehensive Molecular Interaction Studies to Construe the Repellent/Kill Activity of Geraniol During Binding Event Against Aedes aegypti Proteins.

Aedes aegypti is an etiological agent for dengue, chikungunya, zika, and yellow fever viruses. With the advent of the use of natural alternatives as repellents, their precise mode of action during the event of binding is still unclear. Geraniol is one such bioactive natural that has been previously shown to have some insecticide properties. Thus, the present study aimed to understand the mechanism of the binding event of geraniol with the whole proteome of A. aegypti. Twenty protein target categories were shortlisted for the mosquito, wherein the proteins were downloaded with respect to the reference proteome. Conserved domain analysis was performed for the same using the CDD search tool to find the proteins that have common domains. 309 proteins were modeled using RaptorX standalone tool, and validated using Ramachandran plots from SAVES v6.0 from ProCheck. These modeled and validated proteins were then docked against geraniol, using POAP software, for understanding the binding energies. The top 3 best-docked complexes were then analyzed for their stabilities and event of binding via 100 ns simulation studies using DESMOND's Maestro environment. The docking results showed that the geraniol-voltage-gated sodium channel had the best energy of - 7.1 kcal/mol, followed by geraniol-glutathione-S-transferase (- 6.8 kcal/mol) and geraniol-alpha esterase (- 6.8 kcal/mol). The simulations for these 3 complexes revealed that several residues of the proteins interacted well with geraniol at a molecular level, and all three docked complexes were found to be stable when simulated (RMSD: 16-18 Å, 3.6-4.8 Å, 4.8-5.6 Å, respectively). Thus, the present study provides insights into the mechanism of the binding event of geraniol with the major A. aegypti targets, thereby, assisting the use of geraniol as a natural repellent.

High concentrations of membrane-fed ivermectin are required for substantial lethal and sublethal impacts on Aedes aegypti.

BACKGROUND: With widespread insecticide resistance in mosquito vectors, there is a pressing need to evaluate alternatives with different modes of action. Blood containing the antihelminthic drug ivermectin has been shown to have lethal and sub-lethal effects on mosquitoes. Almost all work to date has been on Anopheles spp., but impacts on other anthropophagic vectors could provide new options for their control, or additional value to anti-malarial ivermectin programmes. METHODS: Using dose-response assays, we evaluated the effects of ivermectin delivered by membrane feeding on daily mortality (up to 14 days post-blood feed) and fecundity of an Indian strain of Aedes aegypti. RESULTS: The 7-day lethal concentration of ivermectin required to kill 50% of adult mosquitoes was calculated to be 178.6 ng/ml (95% confidence intervals 142.3-218.4) for Ae. aegypti, which is much higher than that recorded for Anopheles spp. in any previous study. In addition, significant effects on fecundity and egg hatch rates were only recorded at high ivermectin concentrations (≥ 250 ng/ul). CONCLUSION: Our results suggest that levels of ivermectin present in human blood at current dosing regimes in mass drug administration campaigns, or even those in a recent higher-dose anti-malaria trial, are unlikely to have a substantial impact on Ae. aegypti. Moreover, owing to the strong anthropophagy of Ae. aegypti, delivery of higher levels of ivermectin in livestock blood is also unlikely to be an effective option for its control. However, other potential toxic impacts of ivermectin metabolites, accumulation in tissues, sublethal effects on behaviour, or antiviral action might increase the efficacy of ivermectin against Ae. aegypti and the arboviral diseases it transmits, and require further investigation.

ZnO-SiO2 nanohybrid decorated sustainable geopolymer retaining anti-biodeterioration activity with improved durability.

Geopolymer, consists of industrial by-product fly ash, and alkaline activator, possesses similar strength along with durability like conventional cement composite, is an alternative construction substantial of Portland cement in current scenario. Corrosion of the concrete materials resulted mainly from the chemical degradation. Besides chemical degradation, biogenic-deterioration is also another alarming issue especially in the sewer systems, bridge piers, several pipelines and offshore platforms and the need to act on it is long-standing. In this study, application of zinc oxide-silica nanohybrid based sustainable geopolymer (GMZnO-Si) has been investigated for the development of a sustainable, anti-biodeteriorate cementitious material having significant mechanical strength and durability. Initially, zinc oxide nano-rods (ZnO NRs) have been synthesized and spherical silica nanoparticles were decorated on the surface of ZnO NRs. The ZnO-SiO2 composite was characterized by various techniques (FTIR, XRD, FESEM, EDS, TEM, and XPS). Ambient temperature cured GMZnO-Si mortar was further explored in terms of mechanical strength, durability, mechanistic anti-microbial (E. coli, S. aureus, A. niger) influences. Mechanical properties of GMZnO-Si are found significantly higher than that of control samples. MIC, MBC, and MFC results demonstrate enhanced anti-microbial efficacy of GMZnO-Si. Inner permeability assay, reactive oxygen species generation and microscopic images of cell wall rupture and DNA damage studies supported the detailed understanding of anti-microbial activities. These experimental findings suggest that incorporation of ZnO-SiO2 hybrid in geopolymer will pave the way for biodeterioration resistant concrete with enhanced mechanical and structural behaviour.

Comparative Bio-Efficacy and Synergism of New Generation Polyfluorobenzyl and Conventional Pyrethroids Against Culex quinquefasciatus (Diptera: Culicidae).

Intensive exposure to insecticides has resulted in the evolution of insecticide resistance in the mosquitoes. We tested the bio-efficacy of two Culex quinquefasciatus Say (Diptera: Culicidae) laboratory strains differentially bio-responsive to pyrethroids to understand the comparative efficacy of different polyfluorobenzyle and conventional pyrethroid molecules and the role of piperonyl butoxide (PBO) in synergizing these molecules in increased tolerance of mosquitoes to these molecules. We have taken deltamethrin (α-cyano pyrethroid with phenoxybenzyl moiety); permethrin (phenoxybenzyl pyrethroid without an α-cyano group); transfluthrin, dimefluthrin, metofluthrin, and meperfluthrin (polyfluorinated benzyl compounds); and prallethrin (modified cyclopentadienone compound) for this study. We found higher bio-efficacy in dimefluthrin, metofluthrin, and meperfluthrin compared with transfluthrin against tested mosquito strains. We found that transfluthrin exhibited synergism with PBO, which supports the hypothesis that P450 enzymes could play a role in the detoxification process of transfluthrin, which was earlier not believed. However, other polyfluorobenzyl pyrethroids with a 4-(methoxymethyl) phenyl capping in the tetrafluorobenzyl ring (dimefluthrin, metofluthrin, and meperfluthrin) exhibit greater synergism with PBO compared with transfluthrin. Further study is required to understand the mechanism for higher synergistic ratios in polyfluorobenzyl pyrethroids with 4-(methoxymethyl) phenyl moiety and ascertain the possible involvement of novel mechanisms that may involve in developing resistance. This is the first report of comparative bio-efficacy of multiple polyfluorobenzyl pyrethroids and PBO synergism against mosquitoes.

Iron Oxide NPs Facilitated a Smart Building Composite for Heavy-Metal Removal and Dye Degradation.

Due to the growing population, drought, and the contamination of conventional water sources, the need for clean water is rising worldwide with high demand. The application of nanomaterials for water purification can provide a better water quality, by eliminating toxic metals and also decomposing organic contaminants. Exploitation of industrial coal-burned byproduct, fly ash, through nanomodification has been developed in this exertion for the treatment of wastewater along with heavy-metal remediation and dye degradation. The fly ash was sintered at 1000 °C with addition of hydrothermally synthesized iron oxide nanoparticles to make a cementitious composite (FA10C) using an alkali activator (NaOH + Na2SiO3) at ambient temperature. Chemical investigations of the fly ash and the FA10C composites were done by X-ray fluorescence techniques. Analysis of FA10C by X-ray diffraction, Fourier transform infrared, field emission scanning electron microscopy, energy-dispersive spectrometry, and dynamic thermal analysis/thermogravimetric techniques revealed that nanodimensioned rod-shaped mullite formation and its interlocking textures enhance the strength of the building composite. Furthermore, the cementitious composite (FA10C) has been used as an adsorbent to remove heavy metals (lead, chromium, cadmium, copper) and carcinogenic dyes (methylene blue, Congo red, and acid red-1) from their aqueous solutions. The mineralogical features of the composite FA10C and its adsorption capacities/efficiencies were studied by systematic investigation of different parameters, and the adsorption data have been analyzed using Langmuir isotherm. The experimental findings suggest that the iron oxide nanoparticles facilitated fly ash can be implemented as a substitute cementitious composite (greenhouse effect) in construction technology being an energy-saving, low cost, and eco-friendly process in adsorbent manufacturing.

Participatory role of zinc in structural and functional characterization of bioremediase: a unique thermostable microbial silica leaching protein.

A unique protein, bioremediase (UniProt Knowledgebase Accession No.: P86277), isolated from a hot spring bacterium BKH1 (GenBank Accession No.: FJ177512), has shown to exhibit silica leaching activity when incorporated to prepare bio-concrete material. Matrix-assisted laser desorption ionization mass spectrometry analysis suggests that bioremediase is 78% homologous to bovine carbonic anhydrase II though it does not exhibit carbonic anhydrase-like activity. Bioinformatics study is performed for understanding the various physical and chemical parameters of the protein which predicts the involvement of zinc encircled by three histidine residues (His94, His96 and His119) at the active site of the protein. Isothermal titration calorimetric-based thermodynamic study on diethyl pyrocarbonate-modified protein recognizes the presence of Zn(2+) in the enzyme moiety. Exothermic to endothermic transition as observed during titration of the protein with Zn(2+) discloses that there are at least two binding sites for zinc within the protein moiety. Addition of Zn(2+) regains the activity of EDTA chelated bioremediase confirming the presence of extra binding site of Zn(2+) in the protein moiety. Revival of folding pattern of completely unfolded urea-treated protein by Zn(2+) explains the participatory role of zinc in structural stability of the protein. Restoration of the λ max in intrinsic fluorescence emission study of the urea-treated protein by Zn(2+) similarly confirms the involvement of Zn in the refolding of the protein. The utility of bioremediase for silica nanoparticles preparation is observed by field emission scanning electron microscopy.

Fatty acid profiling and molecular characterization of some freshwater microalgae from India with potential for biodiesel production.

We determined the fatty acid compositions of six species of freshwater microalgae belonging to the Chlorophyta, which were isolated from freshwater bodies in Assam, India. All six microalgae -Desmodesmus sp. DRLMA7, Desmodesmus elegans DRLMA13, Scenedesmus sp. DRLMA5, Scenedesmus sp. DRLMA9 Chlorella sp. DRLMA3 and Chlorococcum macrostigmatum DRLMA12-showed similar fatty acid profiles 16:0, 16:4, 18:1, 18:2, and 18:3 as major components. We also compared fatty acid compositions during the late exponential and stationary growth phases of D. elegans DRLMA13 and Scenedesmus sp. DRLMA9 in BG11 medium. We observed enhanced percentages of total saturated and monounsaturated fatty acids with a concomitant decrease in polyunsaturated fatty acid content upon the prolonged cultivation of both microalgae. Distinct morphological features of microalgal isolates were determined by scanning electron microscopic (SEM) studies. An ornamented cell wall was found in D. elegans DRLMA13, which is characteristic of small spineless species of Desmodesmus. The isolated microalgae were further distinguished through analysis of internal transcribed spacer 2 (ITS2) secondary structures and compensatory base changes (CBCs). Analysis of CBCs showed the relatedness of Chlorella sp. DRLMA3 with other Chlorella-like organisms, but it does not belong to the clade comprising Chlorella sensu stricto, which includes Chlorella vulgaris. The CBC count between Scenedesmus sp. DRLMA9 and other species of Scenedesmus provides evidence that this isolate represents a new species.

Multiple insecticide resistance/susceptibility status of Culex quinquefasciatus, principal vector of bancroftian filariasis from filaria endemic areas of northern India.

OBJECTIVE: To understand the insecticide resistance status of Culex quinquefasciatus Say (Diptera: Culicidae) (Cx. Quinquefasciatus) to deltamethrin, cyfluthrin, permethrin, lambdacyhalothrin, DDT and malathion in filarial endemic areas of Uttar Pradesh, India. METHODS: Insecticide susceptibility assays were performed on wild-caught adult female Cx. quinquefasciatus mosquitoes to deltamethrin (0.05%), cyfluthrin (0.15%), permethrin (0.75%), lambdacyhalothrin (0.05%), malathion (5.0%) and DDT (4.0%), the discriminating doses recommended by the World Health Organisation (WHO). RESULTS: The data showed that Cx. quinquefasciatus is highly resistant to DDT and malathion; the mortality was 28.33% and 27.5%, respectively and incipient resistance to synthetic pyrethroids (deltamethrin, cyfluthrin, permethrin, and lambdacyhalothrin), where mortality ranged from 95.83% in permethrin to 98.33% in cyfluthrin and lambdacyhalothrin. Knockdown times (KDT(50)) in response to synthetic pyrethroids varied significantly between different insecticides (P<0.01) from 31.480 min for permethrin to 21.650 for cyfluthrin. CONCLUSIONS: The results presents here provide the status report of the insecticide resistance/susceptibility of Cx. quinquefasciatus in major filaria endemic areas of northern India.

High-throughput approach to detection of knockdown resistance (kdr) mutation in mosquitoes, Culex quinquefasciatus, based on real-time PCR using single-labelled hybridisation probe/melting curve analysis.

BACKGROUND: Knockdown resistance (kdr) mutation (L1014F) is a well-defined mechanism of resistance to pyrethroids and DDT in many insect species. Sensitive detection of the mutations associated with resistance is a prerequisite for resistance management strategies. The authors have developed a new real-time molecular diagnostic assay based on SimpleProbe(®)/melting curve analysis for large-scale kdr genotyping in the wild population of Culex quinquefasciatus Say, the principal vector of bancroftian filariasis. Melting curve analysis is based on the thermal stability difference between matched and mismatched DNA duplexes. The application of SimpleProbe(®) chemistry in insects described here is novel in entomology research. RESULTS: The mosquitoes homozygous for knockdown-resistant and knockdown-susceptible allele showed melting peaks at 60.45 °C (±0.25) and 64.09 °C (±0.24) respectively. The heterozygous mosquitoes yielded both peaks at approximately 60.5 °C (±0.2) and 64.20 °C (±0.23). Among the 92 samples genotyped, 16 were found to be homozygous resistant, 44 homozygous susceptible and 32 heterozygous. Comparative assessments were made of all the reported methods for kdr genotyping. CONCLUSION: The present method is cheaper, faster, more reliable and versatile than other alternatives proposed in detecting correct kdr genotypes in mosquitoes. This is the first report using a single-labelled hybridisation probe to detect point mutations in insect populations.

Are Suicidal Phenomena in Children Different to Suicidal Phenomena in Adolescents? A Six-Year Review.

BACKGROUND: There has been little published about the nature and frequency of suicidal phenomena in children compared to that of adolescents. METHOD: Standardised information on all presentations with suicidal phenomena to the Children's University Hospital, Dublin from 2002 to 2008 were retrospectively analysed from a centralised database. RESULTS: During the time period of the study, 401 young people presented for assessment, of whom 21.9% (N = 88) were under 12 years of age. Children differed from adolescents in terms of gender distribution, method of self-harm, and risk factors present. CONCLUSION: Children under 12 are capable of displaying suicidal phenomena and differ considerably to adolescents in this regard.

Development of physiological resistance and its stage specificity in Culex quinquefasciatus after selection with deltamethrin in Assam, India.

The study investigated the development and stage specificity of physiological resistance to insecticides in a colony of Culex quinquefasciatus Say (Diptera: Culicidae) mosquitoes, which are vectors of bancroftian filariasis in India, after selection with deltamethrin. Resistance was selected by exposing the larvae to the concentration of deltamethrin that caused 50% mortality in the tested population (i.e., LC50). Under continuous selection pressure, the LC50 increased steadily in subsequent generations. The estimated LC50 for the F0 generation was 0.409 microg/L; the LC50 first displayed a substantial increase in the F5 generation (5.616 microg/L) and reached 121.902 microg/L in the F10 generation. The objective of this study was to establish a deltamethrin-resistant colony to develop a research programme that will study the evolution of physiological resistance patterns and stage-specific resistance responses in Cx. quinquefasciatus larvae and adults under laboratory conditions. An approximately 298-fold increase in resistance was recorded after 10 generations, as evidenced by the resistance ratio (RR50). The progress and effect of the selection pressure in the adult stage was monitored with the World Health Organisation (WHO) diagnostic test. The mortality, as observed using the WHO diagnostic test, declined significantly from the F5 generation (85%) onwards and the highest rate of survival (65%) was observed in the F10 generation.

Development of physiological resistance and its stage specificity in Culex quinquefasciatus after selection with deltamethrin in Assam, India

The study investigated the development and stage specificity of physiological resistance to insecticides in a colony of Culex quinquefasciatus Say (Diptera: Culicidae) mosquitoes, which are vectors of bancroftian filariasis in India, after selection with deltamethrin. Resistance was selected by exposing the larvae to the concentration of deltamethrin that caused 50 percent mortality in the tested population (i.e., LC50). Under continuous selection pressure, the LC50 increased steadily in subsequent generations. The estimated LC50 for the F0 generation was 0.409 μg/L; the LC50 first displayed a substantial increase in the F5 generation (5.616 μg/L) and reached 121.902 μg/L in the F10 generation. The objective of this study was to establish a deltamethrin-resistant colony to develop a research programme that will study the evolution of physiological resistance patterns and stage-specific resistance responses in Cx. quinquefasciatus larvae and adults under laboratory conditions. An approximately 298-fold increase in resistance was recorded after 10 generations, as evidenced by the resistance ratio (RR50). The progress and effect of the selection pressure in the adult stage was monitored with the World Health Organisation (WHO) diagnostic test. The mortality, as observed using the WHO diagnostic test, declined significantly from the F5 generation (85 percent) onwards and the highest rate of survival (65 percent) was observed in the F10 generation.

Molecular analysis of knock down resistance (kdr) mutation and distribution of kdr genotypes in a wild population of Culex quinquefasciatus from India.

OBJECTIVE: To investigate the presence of knock down resistance (kdr) mutation, its frequency distribution in the principal vector of bancroftian filariasis, Culex quinquefasciatus from northeastern India, and to relate kdr genotypes with susceptibility and/or resistance to DDT and deltamethrin in this vectors. METHODS: Adult female mosquitoes were collected by aspiration from human dwellings in two villages, Benganajuli and Rikamari, and two military establishments, Field Units I and II. Insecticide susceptibility tests were performed following WHO methods with 4% DDT and 0.05% deltamethrin. Molecular identification of kdr mutation and genotyping of kdr locus was performed by allele-specific PCR (AS-PCR) and direct sequencing in a subset of samples. RESULTS: Mosquitoes were resistant to DDT and showed 11.9-41.2% mortality, whereas the knock down bioassay for deltamethrin suggests complete susceptibility to this insecticide in all study sites except Benganajuli. The result of AS-PCR confirmed the presence of three genotypes: susceptible (SS), resistant (RR) and heterozygous (SR) in the population. Genotype frequencies at kdr locus for DDT-resistant individuals conformed with the Hardy-Weinberg proportion, whereas DDT and deltamethrin susceptible individuals differed significantly (P < 0.05). The efficacy of AS-PCR in detecting the correct genotype was not encouraging. CONCLUSIONS: This is the first report from India on kdr genotyping in C. quinquefasciatus, and it confirms the occurrence of kdr allele in this vector in northeastern India. This finding has serious implications for the filariasis control programmes in India.

Parasitosis: a study among Nepali children in the district of Darjeeling.

A cross-sectional study carried out among 370 school-going children of the Nepali community, aged 5-10 years, in the Siliguri subdivision of Darjeeling district revealed the prevalence of parasitic infestation to be 51.4 per cent of which 28.2% and 23.2% had single and multiple parasitism respectively. In the group of single parasitism, A. lumbricoides was the commonest infestation (31.73%) and in multiple parasitisms, A. lumbricoides and T. Trichiura combination was found to be the most prevalent (36.05%). A significant statistical association was observed in the decrease of worm infestation rate among children with the increasing educational status of their mothers. The study also revealed that 19.73% and 18.91% of the mothers had no knowledge about mode of transmission and prevention of worm infestation respectively.