Biochemical evaluation and molecular docking assessment of Cymbopogon citratus as a natural source of acetylcholine esterase (AChE)- targeting insecticides

Acetylcholinesterase (AChE) has been an effective target for insecticide development which is a very important aspect of the global fight against insect-borne diseases. The drastic reduction in the sensitivity of insects to AChE-targeting insecticides like organophosphates and carbamates have increased the need for insecticides of natural origin. In this study, we used Drosophila melanogaster as a model to investigate the insecticidal and AChE inhibitory potentials of Cymbopogon citratus and its bioactive compounds. Flies were exposed to 100 and 200 mg/mL C. citratus leaf extract for a 3-h survival assay followed by 45 min exposure for negative geotaxis and biochemical assays. Molecular docking analysis of 45 bioactive compounds of the plant was conducted against Drosophila melanogaster AChE (DmAChE). Exposure to C. citratus significantly reduced the survival rate of flies throughout the exposure period and this was accompanied by a significant decrease in percentage negative geotaxis, AChE activity, catalase activity, total thiol level and a significant increase in glutathione-S-transferase (GST) activity. The bioactive compounds of C. citratus showed varying levels of binding affinities for the enzyme. (+)-Cymbodiacetal scored highest (?9.407 kcal/mol) followed by proximadiol (?8.253 kcal/mol), geranylacetone (?8.177 kcal/mol), and rutin (?8.148 kcal/mol). The four compounds occupied the same binding pocket and interacted with important active site amino acid residues as the co-crystallized ligand (1qon). These compounds could be responsible for the insecticidal and AChE inhibitory potentials of C. citratus and they could be further explored in the development of AChE-targeting insecticides.     

Geoadditive latent variable modeling of count data on multiple sexual partnering in Nigeria

The 2005 National HIV/AIDS and Reproductive Health Survey (NARHS) in Nigeria provides evidence that multiple sexual partnering increases the risk of contracting HIV and other sexually transmitted diseases. Therefore, partner reduction is one of the prevention strategies to accomplish the Millenium Development Goal of halting and reversing the spread of HIV/AIDS. We consider the numbers of girlfriends, casual, and commercial partners of heterosexual men, reported in the NARHS study, as observed indicators of their latent attitude toward multiple partnering. To explore the influence of risk factors on this latent variable, we extend semiparametric methodology for latent variable models with continuous and categorical indicators to include count indicators. This allows us to simultaneously analyze linear and nonlinear effects of covariates, such as sociodemographic factors and knowledge about HIV/AIDS, on attitude toward multiple sexual partnering, which in turn influences the observable count indicators. The results provide insights for policy makers who are aiming to reduce the spread of HIV and AIDS among the Nigerian populace through partner reduction.     

Phytosterols and triterpenes from Morinda lucida Benth (Rubiaceae) as potential inhibitors of anti-apoptotic BCL-XL,BCL-2, and MCL-1: an in-silico study

Deregulation of the normal cellular apoptotic function is a fundamental element in the etiology of most cancers and the anti-apoptotic B cell lymphoma 2 (BCL?2) protein family is known to play crucial role in the regulation of this function. Overexpression of this protein family has been implicated in some cancers, such that agents that could inhibit their over-activity are now being explored for anticancer drug development. A number of studies have revealed the anticancer potential of Morinda lucida-derived extracts and compounds. In search of more inhibitors of this anti-apoptotic protein family from plant resources, 47 compounds, identified in Morinda lucida Benth (Rubiaceae) were screened for their inhibitory activities against BCL-XL, BCL-2, and MCL-1 by molecular docking using BINDSURF, while binding interactions of the top compounds were viewed with PyMOL. Druglikeness and Absorption–Distribution–Metabolism–Excretion (ADME) parameters of the top 6 compounds from docking study were evaluated using SuperPred webserver. Results revealed that out of the 47 compounds, 2 triterpenes (ursolic acid and oleanolic acid) and 4 phytosterols (cycloartenol, campesterol, stigmasterol, and β-sitosterol) have higher binding affinities for the selected BCL-2 proteins, compared to known standard inhibitors; these compounds also fulfill oral drugability of Lipinski rule of five. Therefore, since these Morinda lucida-derived phytosterols and triterpenes show high binding affinity toward the selected anti-apoptotic proteins and exhibited good drugability characteristics, they qualify for further study on drug development against cancers characterized by overexpression of this family of protein.     

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 August 2009-30 September 2009

This article documents the addition of 238 microsatellite marker loci and 72 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Adelges tsugae, Artemisia tridentata, Astroides calycularis, Azorella selago, Botryllus schlosseri, Botrylloides violaceus, Cardiocrinum cordatum var. glehnii, Campylopterus curvipennis, Colocasia esculenta, Cynomys ludovicianus, Cynomys leucurus, Cynomys gunnisoni, Epinephelus coioides, Eunicella singularis, Gammarus pulex, Homoeosoma nebulella, Hyla squirella, Lateolabrax japonicus, Mastomys erythroleucus, Pararge aegeria, Pardosa sierra, Phoenicopterus ruber ruber and Silene latifolia. These loci were cross-tested on the following species: Adelges abietis, Adelges cooleyi, Adelges piceae, Pineus pini, Pineus strobi, Tubastrea micrantha, three other Tubastrea species, Botrylloides fuscus, Botrylloides simodensis, Campylopterus hemileucurus, Campylopterus rufus, Campylopterus largipennis, Campylopterus villaviscensio, Phaethornis longuemareus, Florisuga mellivora, Lampornis amethystinus, Amazilia cyanocephala, Archilochus colubris, Epinephelus lanceolatus, Epinephelus fuscoguttatus, Symbiodinium temperate-A clade, Gammarus fossarum, Gammarus roeselii, Dikerogammarus villosus and Limnomysis benedeni. This article also documents the addition of 72 sequencing primer pairs and 52 allele specific primers for Neophocaena phocaenoides.     

The anticalmodulin effect of aflatoxin B1 on purified erythrocyte Ca2+-AtPase

The genotoxic carcinogen aflatoxin B₁ (AFB₁) inhibited the calmodulin-stimulated membrane-bound (Ca²⁺Mg²⁺)-ATPase. Using the purified enzyme, 12 nmoles per ml of AFB₁ caused maximum inhibition of 28% and 50%, of the acidic phospholipid-stimulated and calmodulin-activated Ca²⁺-ATPase activity respectively. Treatment of red cell ghosts with increasing concentrations of Triton X-100, a non-ionic detergent caused a progressive loss of both the basal and calmodulin-stimulated Ca²⁺-ATPase activity. The activity of the phospholipid-free, detergent-solubilized enzyme was almost fully restored by phosphatidyl serine (PS) and its sensitivity to calmodulin was restored in the presence of phosphatidyl choline (PC). Analysis of the results obtained using varying concentrations of ATP shows that AFB₁ did not affect the Km and Vmax of the unstimulated enzyme whereas these parameters were reduced by about 75% and 50%, respectively, in the presence of calmodulin. Using the product of limited proteolysis by trypsin i.e. the 90 kDa fragment which still retains its calmodulin binding-domain and the 76 kDa fragment which has lost this domain, kinetic studies on the enzyme activity revealed that AFB₁ inhibited the calmodulin-activated 90 kDa fragment by about 50% while the 76 kDa was not affected at all by the toxin and calmodulin. The toxin had no significant affect on the basal activity of the 90 kDa limited proteolysis fragment of the enzyme. These observations suggest that AFB₁ inhibits the activated Ca²⁺-ATPase by binding to an important site in the calmodulin-binding domain of the enzyme. It seems likely that the toxin binds to tryptophan in the calmodulin-binding domain, thus causing a reduction in the rate at which this domain can interact with Ca²⁺-calmodulin or acidic phospholipids. The implication of these observations is that Ca²⁺-extrusion and other calmodulin-activated enzymes and processes may be slowed down during prolonged exposure to AFB₁ because of its anticalmodulin effect.Abbreviations ATP adenosine 5-triphosphate - EGTA ethylenglycolbis (-aminoethylether) N,N-tetraacetic acid - Hepes 4-(2 hydroxyethyl)-1-piperazine ethanesulphonic acid - AFB₁ aflatoxin B₁ - PMSF phenylmethylsulfonylfluoride - TLCK N--p-tosyl-L-lysine chloromethyl ketone - PC phosphatidycholine - PS phosphatidylserine - PI phosphatidyl inositol - DPG diphosphatidyl glycerol - SDS sodium dodecyl sulphate - Tris-HCl Tris (hydroxymethyl)aminomethane hydrochloride     

Abundance of 24-methylenecholesterol in traditional African rice as an indicator of resistance to the African rice gall midge, Orseolia oryzivora Harris & Gagné

Rice production is of great importance to food security in Nigeria. The African rice gall midge (AfRGM), Orseolia oryzivora Harris & Gagné, is a major pest of lowland rice in Nigeria and many other Africa countries. Current management efforts are directed at integrating host plant resistance with biological agents. The type and abundance of some phytochemicals are known to affect resistance in host plants, so in this study we measured rice culm hardness, rice culm stickiness and the type and quantity of phytosterols in rice cultivars, and investigated the effects of these factors on resistance to the AfRGM. The study was conducted at 24 ± 2°C, 60 ± 5% relative humidity, and a 12 h light : 12 h dark photoperiod. Three rice cultivars were studied: one Oryza glaberimma cultivar, Tog 7442 (resistant), and two O. sativa cultivars, Cisadane (tolerant) and ITA 306 (susceptible). We found no significant differences in culm hardness and stickiness among the cultivars tested. Using gas chromatography (flame ionization detection) analysis, we identified four major phytosterols: campesterol, 24‐methylenecholesterol, stigmasterol and β‐sitosterol. 24‐Methylenecholesterol was the most abundant sterol in the resistant O. glaberimma cultivar (79.20 μg), whereas β‐sitosterol was most abundant in the two susceptible O. sativa cultivars (Cisadane, 71.27 μg; ITA 306, 66.37 μg). The comparatively high concentration of 24‐methylenecholesterol in this cultivar of O. glaberimma may be an indicator of resistance to AfRGM.     

Characterization of a novel simian immunodeficiency virus (SIVmonNG1) genome sequence from a mona monkey (Cercopithecus mona)

A novel simian immunodeficiency virus (SIV) sequence has been recovered from RNA extracted from the serum of a mona monkey (Cercopithecus mona) wild born in Nigeria. The sequence was obtained by using novel generic (degenerate) PCR primers and spans from two-thirds into the gag gene to the 3' poly(A) tail of the SIVmonNG1 RNA genome. Analysis of the open reading frames revealed that the SIVmonNG1 genome codes for a Vpu protein, in addition to Gag, Pol, Vif, Vpr, Tat, Rev, Env, and Nef proteins. Previously, only lentiviruses infecting humans (human immunodeficiency virus type 1 [HIV-1]) and chimpanzees (SIVcpz) were known to have a vpu gene; more recently, this has also been found in SIVgsn from Cercopithecus nictitans. Overall, SIVmonNG1 most closely resembles SIVgsn: the env gene sequence groups with HIV-1/SIVcpz env sequences, whereas the pol gene sequence clusters closely with the pol sequence of SIVsyk from Cercopithecus albogaris. By bootscanning and similarity plotting, the first half of pol resembles SIVsyk, whereas the latter part is closer to SIVcol from Colobus guereza. The similarities between the complex mosaic genomes of SIVmonNG1 and SIVgsn are consistent with a shared or common lineage. These data further highlight the intricate nature of the relationships between the SIVs from different primate species and will be helpful for unraveling these associations.     

Sandhoff disease in Cyprus: population screening by biochemical and DNA analysis indicates a high frequency of carriers in the Maronite community

In the last 15 years, four patients with the infantile form of Sandhoff disease were diagnosed in four different families in Cyprus (population 703,000, birth rate 1.7%). Three of these cases came from the Christian Maronite community (less than 1% of the population) and one from the Greek community (84% of the population). This relatively large number of patients prompted us to initiate an epidemiological study in order to establish the frequency of the mutant allele in Cyprus. Carrier detection was initially based on the measurement of beta-hexosaminidase A and B in both leucocytes and serum. Using the enzyme test, 35 carriers were identified among 244 random Maronite samples and 15 among 28 Maronites with a family history of Sandhoff disease, but only one carrier was found out of 115 random samples from the Greek community. In parallel to the biochemical screening, DNA studies were undertaken in one of the three Maronite patients and in a Greek carrier related to the Greek patient. These studies resulted in the identification of two novel mutations, a deletion of A at nt76 and a G to C transversion at position 5 of the 5'-splice site of intron 8, which have been published. We subsequently screened the carriers detected in the biochemical study for these two mutations using PCR-based tests. Of 50 Maronite carriers examined, 42 were found to have the nt76 deletion. Eight Maronite samples, designated carriers from the biochemical results, were negative for both mutations. It is possible that these individuals were incorrectly classified as carriers since their enzyme values are equivocal, although the presence of another mutation has not been excluded. Two Greek Cypriot carriers and two obligate Lebanese carriers were negative for both mutations. We conclude that there is a high frequency of Sandhoff disease carriers in the Maronite community of Cyprus, approximately 1 in 7, and that a single mutation predominates in this population.     

Immunohistochemical localization of cadherin and catenin adhesion molecules in the murine growth plate.

Mouse tibial growth plates were examined for the presence of adhesion molecules using immunohistochemistry and RT-PCR. All of the components of the classical cadherin/catenin complex (cadherin, alpha-, beta-, and gamma-catenin), as well as a heavy presence of p120, were identified in the murine growth plate. All of the major cadherins (1-5, 11, 13, and 15) were, for the first time, identified and localized in the murine growth plate. We have demonstrated that most of the cadherins and catenins reside in the zone of hypertrophy. Only alpha-catenin and E-, P-, R-, and VE-cadherin were found in all regions of the growth plate. The results for T-cadherin were inconclusive.     

Sclerotium rolfsii management in tomato using Aframomum melegueta,Ocimum gratissimum and Cymbopogon citratus

Tomato (Lycopersicon esculentum Mill.) is a popular fruit vegetable in Nigeria but production is low due to diseases, among the various disease problems associated with tomato production is southern blight caused by Sclerotium rolfsii. This study was carried out to evaluate the efficacy of Aframomum melegueta, Ocimum gratissimum and Cymbopogon citratus in vitro and in vivo. Infected tomato stems were obtained from the experimental plots of National Horticultural Research Institute, Nigeria. Cultural and morphological identification of the organism was done with the use of microscope. A. melegueta seeds, fresh leaves of O. gratissimum and C. citratus were used. The experiment was replicated three times, radial growth (mm) was measured for 5?days at an interval of 24?h. The in vivo experiment was conducted using the same extracts in a screen house and the experiment was laid out in triplicates in completely randomised design with the synthetic fungicide as control. Data collected were subjected to analysis of variance and significant means were separated using Fisher’s Least Significant Difference at P???0.05. The results showed that the extracts differed significantly (P???0.05) in their potential to inhibit the growth of S. rolfsii. The highest reduction (1.27?mm) in radial growth was obtained with 5% O. gratissimum extract while the least (4.63?cm) was recorded with the control. Disease severity and fruit yield varied among the treatments. The highest yield (170.6?g) was obtained on plants treated with 5% O. gratissimum extract and this was comparable with the yield (155.8?g) obtained on plants treated with funguforce.