Abstract. Cytochrome P450s (P450s) involved in insecticide resistance reduce the effi cacy of insecticide-based vector control by rendering vector control ineffective. They are recorded in many species of vectors and have various constitutive and insecticide induction profi les. In this study, the isolation and prediction of the structure of a P450 from a strain of Aedes aegypti originating from Malaysia is reported. Quantitative mRNA expression of this gene and a previously reported P450, CYP4H28v2, in the devel opmental stages of the mosquito after exposure to sub-lethal concentrations of insecticides is also reported. The isolated P450, CYP4H31v2, is an allelic variant of CYP4H31 and contains several conserved motifs of P450s. The secondary structure of the protein is mostly made up of alpha helices and random coils. The tertiary structure was generated using homology modeling and was of good quality based on structure validation using protein structure assessment tools. CYP4H28v2 and CYP4H31v2 were differentially expressed in the developmental stages of the vector, with a signifi cantly increased expression in adult males. The genes were signifi cantly over-expressed in larvae exposed to deltamethrin and permethrin for 6 h. In the DDT-treated larvae, only CYP4H31v2 was signifi cantly over-expressed after a 6 h exposure. Under-expression of the genes was predominant in larvae treated with the organophosphates malathion and temephos. Though the functions of these P450s are unknown, their response to induction by exposure to insecticides indicates the likely involvement of these genes in insecticide tolerance.

Objective

To clone cytochrome P450 from Aedes aegypti (Ae. aegypti) and determine the characteristics using bioinformatics tools.

Methods

Cytochrome P450 of Ae. aegypti was amplified using polymerase chain reaction, cloned and sequenced. Evolutionary relationship of the sequence was inferred and bioinformatics tools were used to predict subcellular localisation, signal peptide, transmembrane helix, phosphorylation, O-glycosylation, secondary and tertiary structures of the deduced protein.

Results

Polymerase chain reaction rather amplified a cytochrome P450 pseudogene which was named CYP4H44P (GenBank accession number KF779932). The pseudogene has 1 537 nucleotides and an open reading frame of 335 amino acids containing cytochrome P450 motifs except the WxxxR motif. It is highly homologous to CYP4H28 and CYP4H28v2. Phylogenetic analysis and evolutionary divergence showe

Abstract. Synthetic insecticides and other xenobiotic compounds are usually used to abate the effects of insect pests/vectors of agricultural and medical importance by adversely affecting the insects. The xenobiotics are also capable of inducing the expression of detoxification genes such as the cytochrome P450 (CYP) gene in targeted insects like mosquitoes (Feyereisen, 2012). The high expression levels of CYPs in insecticide-resistant and exposed mosquitoes have been linked with a potential role in xenobiotic resistance. This study investigated the induction potential of leaf litter infusions and insecticides on the expressions of CYP4H28v2 and CYP4H31v2 in the dengue mosquito Aedes aegypti using Reverse Transcription-quantitative Polymerase Chain Reaction. Exposure of Ae. aegypti larvae to leaf litter infusions demonstrated that CYP4H28v2 and CYP4H31v2 were significantly induced by Lagerstroemia speciosa but not Ficus benjamina, Plumeria obtusa, Millettia pinnata and Pithecellobium dulce. None of the genes was significantly highly expressed in adult females exposed to d-allethrin and d-trans allethrin products. CYP4H28v2 was significantly induced in Ae. aegypti exposed to DDT, malathion and permethrin for both 5 and 10 min. DDT, malathion and permethrin significantly induced CYP4H31v2 only in Ae. aegypti exposed to the insecticides for 10 min. Exposure to the insecticides for 5 min displayed different levels of CYP4H31v2 expression with significantly higher (DDT-exposed) and lower (permethrin-exposed) levels in the mosquito. The results show that natural and synthetic xenobiotics can induce significant expression of CYP4H28v2 and CYP4H31v2 in the mosquito, indicating the potential role of the genes in mediating xenobiotic resistance. This may enhance the survival capabilities of the mosquito when in contact with phytotoxins of leaf litter in their natural ecosystem and synthetic insecticides in adulticide spray regimens.

Artificial neural network (ANN) is one of the most advanced technology fields, which allows the machine to learn from the examples in a manner similar to the human brain learning. ANN applied to many fields such as function approximation, data processing, classification, signal demodulation and much more. One of the main problems in the communication field is the effect of noise into the transmitted signal. In this thesis an Artificial Neural Network Demodulator (NND) to demodulate quadrature amplitude modulating signal (QAM) is proposed, this project attempts to develop communication systems by developing neural networks and machine learning. This project will help giving contribution to reduce the error bits, optimize the quality of received data and optimize (NNDs).

The present work reports a facile approach to the one-pot solution growth of vertically

aligned, doped ZnO nanorod (NR) arrays by chemical bath deposition (CBD). The effects of

dopant ions on the final morphologies, electronic band structures and donor densities of

ZnO NRs were examined. With the introduction of dopants, the optical band gap energies

of the samples were reduced. The photoelectrochemical (PEC) water splitting performances

of the doped ZnO NRs were tested. When compared with pristine ZnO NRs, the doped ZnO

NRs demonstrated an improvement of at least 15% in the PEC water splitting activity. Nadoped ZnO NRs was the most efficient photoanode, where its photocurrent density was 2.1

times greater than that of pristine ZnO NRs. The mechanism for improved PEC performance was proposed

Abstract and figures

We performed a comprehensive study of trichomes considering the medicinal importance of the essential oils produced in glandular trichomes of Salvia aegyptiaca L. and lack of data about leaf trichome characteristics. Micromorphological and histochemical analyses of the trichomes of S. aegyptiaca were carried out using light and scanning electron microscopy. We report that the leaves contained abundant non-glandular unbranched trichomes and two types of glandular trichomes, peltate and capitate, on both leaf surfaces. The abaxial leaf side was covered with numerous peltate and capitate trichomes, while capitate trichomes were more abundant on the adaxial leaf side, where peltate trichomes were rarely observed. The non-glandular trichomes were unicellular papillae and multicellular, uniseriate, two-to-six-celled, erect or slightly leaning toward the epidermis. Peltate trichomes were composed of a basal cell, a short cylindrical stalk cell and a broad head of eight secretory cells arranged in a single circle. Capitate trichomes consisted of a one-celled glandular head, subtended by a stalk of variable length, and classified into two types: Capitate trichomes type I (or short-stalked glandular trichomes) and capitate trichomes type II (or long-stalked glandular trichomes). Histochemical tests showed that the secreted material in all types of S. aegyptiaca glandular trichomes was of a complex nature. Positive reactions to lipids for both types of glandular trichomes were obtained, with especially abundant secretion observed in peltate and capitate trichomes type II.

• Cereal and its products can be contaminated with fungi in the field, during drying, processing, transportation and subsequent storage, which may lead to secretion of mycotoxins under favourable condition. The aim of this study was the isolation and identification of some fungi associated with four kinds of Libyan food products of different trademarks. Twenty four (24) samples of couscous, macaroni, wheat flour and rice regularly used for human consumption by Libyan family were collected from local markets in the city of Alzawia, west of Tripoli, Libya. The results reveal isolation of 113 isolates belonging to nine genera: Penicillium, Aspergillus, Fusarium, Paecilomyces, Alternaria, Rhizopus, Mucor, Scopulariopsis and Cladosporum. Approximately 24 species were identified to belong to those isolated genera, several of which are known as main producer of mycotoxins especially A. flavus which are known to produce aflatoxins, Aspergillus niger, Aspergillus carbonarious, Penicillium chrysogenum and Penicillium verrucosum known to produce ochratoxin and Fusarium oxysporum and Fusarium chlamydosporum known to produce fumonisins and trichothecenes. Certainly, the occurrence of such types of mycotoxins can pose a health threatening risk for the consumer of those food items. Presence of these fungi in food products could be due to lack of good agriculture and food manufacturing practices throughout the food chain.
• Key words: Couscous, macaroni, wheat flour, rice, fungi, Libya.

Background

The use of mosquito coils is a common method of protection against mosquito bites and mosquito borne diseases. These coils are widely marketed and used by households in Malaysia to prevent mosquito associated problems.

Objective

To determine the bioefficacy of commercial d-allethrin and d-trans allethrin spatial repellents against the dengue vector Aedes aegypti.

Method

We evaluated the knockdown and mortality effects of spatial repellents containing d-allethrin (0.3% w/w) and d-trans allethrin (0.1% and 0.15% w/w) on Ae. aegypti in a Peet Grady Chamber, relative to a reference product (0.2% w/w d-allethrin).

Results

The spatial repellent containing 0.3% d-allethrin had the shortest knockdown times (KT₅₀ and KT₉₀) and these were significantly different from the other products including the reference coil except the 0.15% d-trans allethrin coil. The spatial repellent containing 0.3% d-allethrin elicited a mortality response of 96%, which was significantly different from the mortality response to the other coils, except for the 0.15% d-trans allethrin formulation.

Conclusions

Spatial repellents containing 0.3% d-allethrin or 0.15% d-trans allethrin had higher efficacies against Ae. aegypti than repellents containing 0.2% w/w d-allethrin or 0.1% d-trans allethrin and their use by households could offer better relief from Ae. aegypti

Abstract

Aims: In the present work, the Libyan wild-growing Thymus capitatus essential oil (EO) was evaluated for its biological properties.

Methods and results: Carvacrol (68.19%) and thymol (12.29%) were found to be the main compounds of the oil. Antioxidant properties, determined by 2,2-diphenylpicrylhydrazyl (DPPH) assay, revealed that IC50 values were 119, 403 and 105 μg ml(-1) for oil, thymol and carvacrol respectively. Microdilution method showed strong antibacterial and especially antifungal potential. Tetrazolium (MTT) colorimetric assay indicated moderate cytotoxicity towards human cell lines MRC-5, HCT 116 and HT-29 (IC50 = 30-150 μg ml(-1)). In adhesion-inhibition assay oil and main compounds reduced adhesion of Escherichia coli and Listeria monocytogenes on colon cells HT-29 (51 and 39% of inhibition against L. monocytogenes and E. coli respectively).

Conclusions: Essential oil of Th. capitatus showed moderate cytotoxic activity, together with excellent antimicrobial effect, in particular against fungi, and significant potential to reduce pathogen colonization in colon.