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Displaying publications 21 - 33 of 33 in total

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Expression and characterization of anticoagulant activity of salivary protein alALP from Asian tiger mosquito Aedes albopictus

Li XP, Lin D, Zhang Y, Chen SQ, Bai HQ, Zhang SN, et al.

Trop Biomed, 2020 Mar 01;37(1):116-126.
PMID: 33612723

Several bioactive molecules isolated from the saliva of blood-sucking arthropods, such as mosquitoes, have been shown to exhibit potential anticoagulant function. We have previously identified a 30kDa allergen named Aegyptin-like protein (alALP), which is highly homologous to Aegyptin, from the salivary glands of female Aedes albopictus (Asian tiger mosquito). In this study, we identified the conserved functional domain of alALP by using bioinformatic tools, and expressed the His-tagged alALP recombinant protein in sf9 insect cells by generation and transfection of a baculoviral expression plasmid carrying the fulllength cDNA of alALP. We purified this recombinant protein and examined its function on the inhibition of blood coagulation. The results showed that the purified His-alALP prolonged the Activated Partial Thromboplastin Time (APTT), Prothrombin Time (PT) and Thrombin Time (TT) in vitro as well as the Bleeding Time (BT) in vivo, which suggest that alALP could be a novel anticoagulant.

Matched MeSH terms: Insect Proteins/genetics
Fulltext Molecular phylogeny of Orthetrum dragonflies reveals cryptic species of Orthetrum pruinosum

Yong HS, Lim PE, Tan J, Ng YF, Eamsobhana P, Suana IW

Sci Rep, 2014 Jul 03;4:5553.
PMID: 24989852 DOI: 10.1038/srep05553

Dragonflies of the genus Orthetrum are members of the suborder Anisoptera, family Libellulidae. There are species pairs whose members are not easily separated from each other by morphological characters. In the present study, the DNA nucleotide sequences of mitochondrial and nuclear genes were employed to elucidate the phylogeny and systematics of Orthetrum dragonflies. Phylogenetic analyses could not resolve the various subfamilies of the family Libellulidae unequivocally. The nuclear 28S rRNA gene is highly conserved and could not resolve congeneric species of Orthetrum. Individual mitochondrial genes (COI, COII, and 16S rRNA) and combination of these genes as well as the nuclear ITS1&2 genes clearly differentiate morphologically similar species, such as the reddish species pairs O. chrysis and O. testaceum, and the bluish-coloured species O. glaucum and O. luzonicum. This study also reveals distinct genetic lineages between O. pruinosum schneideri (occurring in Malaysia) and O. pruinosum neglectum (occurring north of Peninsular Malaysia from India to Japan), indicating these taxa are cryptic species.

Matched MeSH terms: Insect Proteins/genetics
Haplotype-habitat associations of Coptotermes gestroi (Termitoidae: Rhinotermitidae) from mitochondrial DNA genes

Cheng S, Thinagaran D, Mohanna SZ, Noh NA

Environ Entomol, 2014 Aug;43(4):1105-16.
PMID: 24915136 DOI: 10.1603/EN13318

Coptotermes gestroi (Wasmann) or the Asian subterranean termite is a serious structural pest in urban settlements in Southeast Asia that has been introduced to other parts of the world through human commerce. Although mitochondrial DNA markers were previously used to shed light on the dispersal history of the Asian subterranean termite, there were limited attempts to analyze or include populations of the termite found in the wild in Southeast Asia. In this study, we analyzed the 16S ribosomal RNA (16S rRNA) and cytochrome c oxidase subunit 1 (cox1) genes of Asian subterranean termite colonies found in mangrove swamps, beach forests, plantations, and buildings in semi-urban and urban areas to determine the relationship between colonies found in the wild and the urban habitat, and to investigate the possibility of different ecotypes of the termite in Peninsular Malaysia. Our findings show that the 16S rRNA haplotypes recovered from this study clustered into eastern, western, and southern populations of the termite, while the cox1 haplotypes were often specific to an area or site. The 16S rRNA and cox1 genes or haplotypes showed that the most abundant haplotype occupied a wide range of environments or habitats. In addition, the cox1 tree showed evidence of historical biogeography where basal haplotypes inhabited a wide range of habitats, while apical haplotypes were restricted to mangrove swamps and beach forests. Information on the haplotype-habitat association of C. gestroi will enable the prediction of habitats that may harbor or be at risk of invasion in areas where they have been introduced.

Matched MeSH terms: Insect Proteins/genetics
First molecular genotyping of insensitive acetylcholinesterase associated with malathion resistance in Culex quinquefasciatus Say populations in Malaysia

Low VL, Chen CD, Lim PE, Lee HL, Lim YA, Tan TK, et al.

Pest Manag Sci, 2013 Dec;69(12):1362-8.
PMID: 23404830 DOI: 10.1002/ps.3512

Given that there is limited available information on the insensitive acetylcholinesterase in insect species in Malaysia, the present study aims to detect the presence of G119S mutation in the acetylcholinesterase gene of Culex quinquefasciatus from 14 residential areas across 13 states and a federal territory in Malaysia.

Matched MeSH terms: Insect Proteins/genetics*
First description of the male of Phlebotomus betisi Lewis and Wharton, 1963 (Diptera: Psychodidae)

Khadri MS, Depaquit J, Bargues MD, Ferté H, Mas-coma S, Lee HL, et al.

Parasitol Int, 2008 Sep;57(3):295-9.
PMID: 18378490 DOI: 10.1016/j.parint.2008.01.003

The male of Phlebotomus (Larroussius) betisi is described from Malayan caves. Several males have been caught in association with P. betisi females. Males and females have been associated by ecology, biogeography, morphology and molecular biology (homology of the ND4 mtDNA sequences).

Matched MeSH terms: Insect Proteins/genetics
Mitochondrial DNA analyses reveal low genetic diversity in Culex quinquefasciatus from residential areas in Malaysia

Low VL, Lim PE, Chen CD, Lim YA, Tan TK, Norma-Rashid Y, et al.

Med Vet Entomol, 2014 Jun;28(2):157-68.
PMID: 23848279 DOI: 10.1111/mve.12022

The present study explored the intraspecific genetic diversity, dispersal patterns and phylogeographic relationships of Culex quinquefasciatus Say (Diptera: Culicidae) in Malaysia using reference data available in GenBank in order to reveal this species' phylogenetic relationships. A statistical parsimony network of 70 taxa aligned as 624 characters of the cytochrome c oxidase subunit I (COI) gene and 685 characters of the cytochrome c oxidase subunit II (COII) gene revealed three haplotypes (A1-A3) and four haplotypes (B1-B4), respectively. The concatenated sequences of both COI and COII genes with a total of 1309 characters revealed seven haplotypes (AB1-AB7). Analysis using tcs indicated that haplotype AB1 was the common ancestor and the most widespread haplotype in Malaysia. The genetic distance based on concatenated sequences of both COI and COII genes ranged from 0.00076 to 0.00229. Sequence alignment of Cx. quinquefasciatus from Malaysia and other countries revealed four haplotypes (AA1-AA4) by the COI gene and nine haplotypes (BB1-BB9) by the COII gene. Phylogenetic analyses demonstrated that Malaysian Cx. quinquefasciatus share the same genetic lineage as East African and Asian Cx. quinquefasciatus. This study has inferred the genetic lineages, dispersal patterns and hypothetical ancestral genotypes of Cx. quinquefasciatus.

Matched MeSH terms: Insect Proteins/genetics
Three Taxa in One: Cryptic Diversity in the Black Fly Simulium nobile (Diptera: Simuliidae) in Southeast Asia

Low VL, Takaoka H, Pramual P, Adler PH, Ya'cob Z, Chen CD, et al.

J Med Entomol, 2016 07;53(4):972-976.
PMID: 27208009

We access the molecular diversity of the black fly Simulium nobile De Mejiere, using the universal cytochrome c oxidase subunit I (COI) barcoding gene, across its distributional range in Southeast Asia. Our phylogenetic analyses recovered three well-supported mitochondrial lineages of S. nobile, suggesting the presence of cryptic species. Lineage A is composed of a population from Sabah, East Malaysia (Borneo); lineage B represents the type population from Java, Indonesia; and lineage C includes populations from the mainland of Southeast Asia (Peninsular Malaysia and Thailand). The genetic variation of lineage C on the mainland is greater than that of lineages A and B on the islands of Borneo and Java. Our study highlights the value of a molecular approach in assessing species status of simuliids in geographically distinct regions.

Matched MeSH terms: Insect Proteins/genetics
Fulltext Protein-protein interactions between A. aegypti midgut and dengue virus 2: two-hybrid screens using the midgut cDNA library

Tham HW, Balasubramaniam VR, Chew MF, Ahmad H, Hassan SS

J Infect Dev Ctries, 2015 Dec 30;9(12):1338-49.
PMID: 26719940 DOI: 10.3855/jidc.6422

INTRODUCTION: Dengue virus (DENV) is principally transmitted by the Aedes aegypti mosquito. To date, mosquito population control remains the key strategy for reducing the continuing spread of DENV. The focus on the development of new vector control strategies through an understanding of the mosquito-virus relationship is essential, especially targeting the midgut, which is the first mosquito organ exposed to DENV infection.
METHODOLOGY: A cDNA library derived from female adult A. aegypti mosquito midgut cells was established using the switching mechanism at the 5' end of the RNA transcript (SMART), in combination with a highly potent recombination machinery of Saccharomyces cerevisiae. Gal4-based yeast two-hybrid (Y2H) assays were performed against DENV-2 proteins (E, prM, M, and NS1). Mammalian two-hybrid (M2H) and double immunofluorescence assays (IFA) were conducted to validate the authenticity of the three selected interactions.
RESULTS: The cDNA library was of good quality based on its transformation efficiency, cell density, titer, and the percentage of insert size. A total of 36 midgut proteins interacting with DENV-2 proteins were identified, some involved in nucleic acid transcription, oxidoreductase activity, peptidase activity, and ion binding. Positive outcomes were obtained from the three selected interactions validated using M2H and double IFA assays.
CONCLUSIONS: The identified proteins have different biological activities that may aid in the virus replication pathway. Therefore, the midgut cDNA library is a valuable tool for identifying DENV-2 interacting proteins. The positive outcomes of the three selected proteins validated supported the quality of the cDNA library and the robustness of the Y2H mechanisms.

Matched MeSH terms: Insect Proteins/genetics
Mitochondrial Cytochrome Oxidase I Gene Sequence Analysis of Aedes Albopictus in Malaysia

Ismail NA, Dom NC, Ismail R, Ahmad AH, Zaki A, Camalxaman SN

J Am Mosq Control Assoc, 2015 Dec;31(4):305-12.
PMID: 26675451 DOI: 10.2987/moco-31-04-305-312.1

A study was conducted to establish polymorphic variation of the mitochondrial DNA encoding the cytochrome oxidase subunit 1 (CO1) gene in Aedes albopictus isolated from 2 hot spot dengue-infested areas in the Subang Jaya District, Malaysia. A phylogenetic analysis was performed with the use of sequences obtained from USJ6 and Taman Subang Mas (TSM). Comparison of the local CO1 sequences with a laboratory strain (USM), alongside reference strains derived from the GenBank database revealed low genetic variation in terms of nucleotide differences and haplotype diversity. Four methods were used to construct a phylogenetic tree and illustrate the genetic relationship of the 37 Ae. albopictus populations based on the CO1 sequences, namely neighbor-joining (NJ), maximum parsimony (MP), maximum likelihood (ML), and Bayesian method, which revealed a distinct relationship between isolates from USJ6 and TSM. Our findings provide new information regarding the genetic diversity among morphologically similar Ae. albopictus, which has not been reported to date.

Matched MeSH terms: Insect Proteins/genetics
Fulltext New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

Ang JXD, Kadir KA, Mohamad DSA, Matusop A, Divis PCS, Yaman K, et al.

Parasit Vectors, 2020 Sep 15;13(1):472.
PMID: 32933567 DOI: 10.1186/s13071-020-04345-2

BACKGROUND: Plasmodium knowlesi is a significant cause of human malaria in Sarawak, Malaysian Borneo. Only one study has been previously undertaken in Sarawak to identify vectors of P. knowlesi, where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak.
METHODS: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small subunit ribosomal RNA (SSU rRNA) gene of Plasmodium was sequenced, and the internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the mosquitoes were sequenced from the Plasmodium-positive samples for phylogenetic analysis.
RESULTS: Totals of 65 anophelines and 127 culicines were collected. By PCR, 6 An. balabacensis and 5 An. donaldi were found to have single P. knowlesi infections while 3 other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi. Phylogenetic analysis of the Plasmodium SSU rRNA gene confirmed 3 An. donaldi and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and some species of Plasmodium that could not be conclusively identified. Phylogenies inferred from the ITS2 and/or cox1 sequences of An. balabacensis and An. donaldi indicate that they are genetically indistinguishable from An. balabacensis and An. donaldi, respectively, found in Sabah, Malaysian Borneo.
CONCLUSIONS: Previously An. latens was identified as the vector for P. knowlesi in Kapit, central Sarawak, Malaysian Borneo, and now An. balabacensis and An. donaldi have been incriminated as vectors for zoonotic malaria in Lawas, northern Sarawak.

Matched MeSH terms: Insect Proteins/genetics
Fulltext Pyrethroid Resistance in Malaysian Populations of Dengue Vector Aedes aegypti Is Mediated by CYP9 Family of Cytochrome P450 Genes

Ishak IH, Kamgang B, Ibrahim SS, Riveron JM, Irving H, Wondji CS

PLoS Negl Trop Dis, 2017 01;11(1):e0005302.
PMID: 28114328 DOI: 10.1371/journal.pntd.0005302

BACKGROUND: Dengue control and prevention rely heavily on insecticide-based interventions. However, insecticide resistance in the dengue vector Aedes aegypti, threatens the continued effectiveness of these tools. The molecular basis of the resistance remains uncharacterised in many endemic countries including Malaysia, preventing the design of evidence-based resistance management. Here, we investigated the underlying molecular basis of multiple insecticide resistance in Ae. aegypti populations across Malaysia detecting the major genes driving the metabolic resistance.
METHODOLOGY/PRINCIPAL FINDINGS: Genome-wide microarray-based transcription analysis was carried out to detect the genes associated with metabolic resistance in these populations. Comparisons of the susceptible New Orleans strain to three non-exposed multiple insecticide resistant field strains; Penang, Kuala Lumpur and Kota Bharu detected 2605, 1480 and 425 differentially expressed transcripts respectively (fold-change>2 and p-value ≤ 0.05). 204 genes were commonly over-expressed with monooxygenase P450 genes (CYP9J27, CYP6CB1, CYP9J26 and CYP9M4) consistently the most up-regulated detoxification genes in all populations, indicating that they possibly play an important role in the resistance. In addition, glutathione S-transferases, carboxylesterases and other gene families commonly associated with insecticide resistance were also over-expressed. Gene Ontology (GO) enrichment analysis indicated an over-representation of GO terms linked to resistance such as monooxygenases, carboxylesterases, glutathione S-transferases and heme-binding. Polymorphism analysis of CYP9J27 sequences revealed a high level of polymorphism (except in Joho Bharu), suggesting a limited directional selection on this gene. In silico analysis of CYP9J27 activity through modelling and docking simulations suggested that this gene is involved in the multiple resistance in Malaysian populations as it is predicted to metabolise pyrethroids, DDT and bendiocarb.
CONCLUSION/SIGNIFICANCE: The predominant over-expression of cytochrome P450s suggests that synergist-based (PBO) control tools could be utilised to improve control of this major dengue vector across Malaysia.

Matched MeSH terms: Insect Proteins/genetics
Fulltext CPB1 of Aedes aegypti interacts with DENV2 E protein and regulates intracellular viral accumulation and release from midgut cells

Tham HW, Balasubramaniam VR, Tejo BA, Ahmad H, Hassan SS

Viruses, 2014 Dec;6(12):5028-46.
PMID: 25521592 DOI: 10.3390/v6125028

Aedes aegypti is a principal vector responsible for the transmission of dengue viruses (DENV). To date, vector control remains the key option for dengue disease management. To develop new vector control strategies, a more comprehensive understanding of the biological interactions between DENV and Ae. aegypti is required. In this study, a cDNA library derived from the midgut of female adult Ae. aegypti was used in yeast two-hybrid (Y2H) screenings against DENV2 envelope (E) protein. Among the many interacting proteins identified, carboxypeptidase B1 (CPB1) was selected, and its biological interaction with E protein in Ae. aegypti primary midgut cells was further validated. Our double immunofluorescent assay showed that CPB1-E interaction occurred in the endoplasmic reticulum (ER) of the Ae. aegypti primary midgut cells. Overexpression of CPB1 in mosquito cells resulted in intracellular DENV2 genomic RNA or virus particle accumulation, with a lower amount of virus release. Therefore, we postulated that in Ae. aegypti midgut cells, CPB1 binds to the E protein deposited on the ER intraluminal membranes and inhibits DENV2 RNA encapsulation, thus inhibiting budding from the ER, and may interfere with immature virus transportation to the trans-Golgi network.

Matched MeSH terms: Insect Proteins/genetics
Detection of the A302S Rdl mutation in fipronil bait-selected strains of the German cockroach (Dictyoptera: Blattellidae)

Ang LH, Nazni WA, Kuah MK, Shu-Chien AC, Lee CY

J Econ Entomol, 2013 Oct;106(5):2167-76.
PMID: 24224261

Extensive usage and heavy reliance on insecticides have led to the development of insecticide resistance in the German cockroach, Blattella germanica (L.). Six field-collected strains of B. germanica from Singapore were used to investigate resistance to fipronil and dieldrin. The three strains (Boat Quay, Cavenagh Road, and Ghimmoh Road) with greatest resistance to fipronil were subjected to selection with fipronil bait up to the F5 generation. Synergism assay and molecular detection of a target site mutation were used to elucidate the mechanism of fipronil resistance in these strains. With the exception of the Cavenagh Road strain, all parental strains were susceptible to dieldrin. This strain exhibited resistance to dieldrin and fipronil with resistance ratios of 4.1 and 3.0, respectively. Piperonyl butoxide and S,S,S-tributylphosphorotrithioate were antagonistic toward fipronil toxicity in all strains. Bait selection significantly increased fipronil and dieldrin resistance in the three chosen strains, either in topical bioassay or bait evaluations. There was a significant positive relationship [y = (6,852.69 +/- 1,988.37) x - (708.93 +/- 1,226.28), where x = fipronil toxicity and y = dieldrin toxicity] between dieldrin and fipronil resistance levels, indicating significant cross-resistance between the insecticides. High frequencies of individuals possessing the Rdl gene mutation were found in the F5 generation of the three strains selected with fipronil bait. The synergism assays indicated that monooxygenase and esterase were not involved in fipronil resistance in the strains studied herein. The A302S Rdl mutation was the major mechanism contributing to fipronil and dieldrin resistance in these strains.

Matched MeSH terms: Insect Proteins/genetics

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