21 results on '"Jackson M. Muema"'
Search Results
2. Isoliensinine from Cissampelos pariera rhizomes exhibits potential gametocytocidal and anti-malarial activities against Plasmodium falciparum clinical isolates
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Jackson M. Muema, James M. Mutunga, Meshack A. Obonyo, Merid N. Getahun, Ramadhan S. Mwakubambanya, Hoseah M. Akala, Agnes C. Cheruiyot, Redemptah A. Yeda, Dennis W. Juma, Ben Andagalu, Jaree L. Johnson, Amanda L. Roth, and Joel L. Bargul
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Isoliensinine ,Gametocytes ,Plasmodium transmission-blocking ,Cissampelos pariera ,Malaria control ,Natural product ,Arctic medicine. Tropical medicine ,RC955-962 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background The unmet demand for effective malaria transmission-blocking agents targeting the transmissible stages of Plasmodium necessitates intensive discovery efforts. In this study, a bioactive bisbenzylisoquinoline (BBIQ), isoliensinine, from Cissampelos pariera (Menispermaceae) rhizomes was identified and characterized for its anti-malarial activity. Methods Malaria SYBR Green I fluorescence assay was performed to evaluate the in vitro antimalarial activity against D6, Dd2, and F32-ART5 clones, and immediate ex vivo (IEV) susceptibility for 10 freshly collected P. falciparum isolates. To determine the speed- and stage-of-action of isoliensinine, an IC50 speed assay and morphological analyses were performed using synchronized Dd2 asexuals. Gametocytocidal activity against two culture-adapted gametocyte-producing clinical isolates was determined using microscopy readouts, with possible molecular targets and their binding affinities deduced in silico. Results Isoliensinine displayed a potent in vitro gametocytocidal activity at mean IC50 gam values ranging between 0.41 and 0.69 µM for Plasmodium falciparum clinical isolates. The BBIQ compound also inhibited asexual replication at mean IC50 Asexual of 2.17 µM, 2.22 µM, and 2.39 µM for D6, Dd2 and F32-ART5 respectively, targeting the late-trophozoite to schizont transition. Further characterization demonstrated a considerable immediate ex vivo potency against human clinical isolates at a geometric mean IC50 IEV = 1.433 µM (95% CI 0.917–2.242). In silico analyses postulated a probable anti-malarial mechanism of action by high binding affinities for four mitotic division protein kinases; Pfnek1, Pfmap2, Pfclk1, and Pfclk4. Additionally, isoliensinine was predicted to possess an optimal pharmacokinetics profile and drug-likeness properties. Conclusion These findings highlight considerable grounds for further exploration of isoliensinine as an amenable scaffold for malaria transmission-blocking chemistry and target validation.
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- 2023
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3. Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions
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Jackson M. Muema, Joel L. Bargul, Meshack A. Obonyo, Sospeter N. Njeru, Damaris Matoke-Muhia, and James M. Mutunga
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Human pathogen transmission-blocking ,Natural products ,Arthropod disease vectors ,Disease control ,Anti-infectives ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.
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- 2022
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4. Discovery of the vector of visceral leishmaniasis, Phlebotomus (Artemievus) alexandri Sinton, 1928, in Kenya suggests complex transmission dynamics
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Steve Kiplagat, Jandouwe Villinger, Collins K. Kigen, Kevin O. Kidambasi, Jackson M. Muema, Stephie M. Mwangi, Maureen Wangari, Damaris Matoke-Muhia, Daniel K. Masiga, and Joel L. Bargul
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Phlebotomus alexandri ,Sand flies ,Sergentomyia ,Leishmania ,Cutaneous leishmaniasis ,Visceral leishmaniasis ,Infectious and parasitic diseases ,RC109-216 - Abstract
Visceral and cutaneous leishmaniasis are endemic to specific regions due to the ecological preferences of phlebotomine sand flies and Leishmania spp. transmission. Sand fly entomological data in northern Kenya are scarce due to limited studies and neglect of leishmaniasis. The aim of this study was to investigate: (i) sand fly diversity and distribution; (ii) occurrence of Leishmania DNA within sand flies; and (iii) blood-meal sources of sand flies in Laisamis, northern Kenya. We conducted an entomological survey during February and March of 2021 in five areas of Laisamis sub-county using standard CDC light traps. A total of 1009 sand flies (394 male and 615 female) were morphologically identified, and representative samples verified by PCR amplification and sequencing of the cytochrome c oxidase subunit 1 (cox1) gene. Similarly, we identified blood-meal sources and Leishmania DNA in female sand flies by PCR amplicon sequencing of the vertebrate cytochrome b (cyt b) gene and internal transcribed spacer 1 (ITS1) of the 28S rRNA gene, respectively. Sergentomyia clydei (59.8%) was the most abundant sand fly species. Though collected mainly from one locality (Tirgamo), 14.8% of samples belonged to Phlebotomus (Artemievus) alexandri Sinton, 1928. We detected DNA of Leishmania major in 5.19% of Ph. alexandri, whereas Leishmania adleri DNA was detected in S. clydei (7.51%), Sergentomyia squamipleuris (8.00%), and Sergentomyia africanus (8.33%). Nine of 13 blood-fed sand flies had obtained blood from humans, of which 33.3% had L. major DNA. Both Ph. alexandri and S. clydei primarily fed on humans and could potentially be involved in the transmission of cutaneous leishmaniasis. The findings of this study contribute to the understanding of sand fly vector populations and their potential to transmit leishmaniasis in the area.
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- 2023
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5. In vitro cytotoxicity of Aspilia pluriseta Schweinf. extract fractions
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Sospeter N. Njeru and Jackson M. Muema
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Vero cells ,Medicinal/herbal plants ,Traditional/folk medicine ,MTT assay ,Selectivity index ,Phytochemicals ,Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Objectives We and others have shown that Aspilia pluriseta is associated with various biological activities. However, there is a lack of information on its cytotoxicity. This has created an information gap about the safety of A. pluriseta extracts. As an extension to our recent publication on the antimicrobial activity and the phytochemical characterization of A. pluriseta root extracts, here we report on cytotoxicity of tested solvent fractions. We evaluated the potential cytotoxicity of these root extract fractions on Vero cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results We show that all solvent extract fractions (except methanolic solvent fractions) had cytotoxic concentration values that killed 50% of the Vero cells (CC50) greater than 20 µg/mL and selectivity index (SI) greater than 1.0. Taken together, we demonstrate that, A. pluriseta extract fractions’ earlier reported bioactivities are within the acceptable cytotoxicity and selective index limits. This finding scientifically validates the potential use of A. pluriseta in the discovery of safe therapeutics agents.
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- 2021
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6. Antimicrobial activity, phytochemical characterization and gas chromatography-mass spectrometry analysis of Aspilia pluriseta Schweinf. extracts
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Sospeter N. Njeru and Jackson M. Muema
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Tuberculosis ,Mycobacterium tuberculosis ,Drug resistance ,Phytochemicals ,Fatty acid alkyl esters ,Alkanes ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Aspilia pluriseta is associated with various bioactivities, although with limited scientific justification. In this study, we evaluated the antimicrobial activity, and characterized the phytochemicals of root extracts of A. pluriseta aimed at validating its therapeutic potential. We used BACTEC MGIT™ 960 system to test for antitubercular activity, disc-diffusion together with the microdilution method to evaluate antimicrobial activities and qualitative phytochemical tests together with gas chromatography-mass spectrometry (GC-MS) analysis to determine the phytochemicals that associated with A. pluriseta extracts activity. We show that methanolic crude extract (at 1 g/mL) had high Mycobacterium tuberculosis (MTB) inhibitory activity (0 growth unit) and considerable potency against Escherichia coli (11.7 mm), Staphylococcus aureus (9.0 mm), and Candida albicans (7.7 mm). All the extract fractions exerted remarkable antimycobacterial activities with minimum inhibitory activity of between 6.26 – 25 μg/mL. The highest antimicrobial activity of petroleum ether and dichloromethane fraction was against E. coli at inhibition zone diameters of 8.3 mm, and 8.0 mm, respectively, while ethyl acetate fraction was against S. aureus with an inhibition zone of 8.7 mm. Methanolic fraction exhibited broad-spectrum activity against 87.5% of the tested microbes (inhibition zones 6.3–8.3 mm). Furthermore, we qualitatively detected terpenoids, alkaloids, and phenolics such as flavonoids, and anthraquinones in extract fractions. GC-MS analysis detected an abundance of fatty acid esters, 2-hydroxy-1-(hydroxymethyl) ethyl ester-hexadecanoic acid, and 2,3-dihydroxy propyl ester-octadecanoic acid and four alkanes. Taken together, we show that A. pluriseta extract fractions (especially ethyl acetate and methanolic fractions) have strong selective antitubercular activity, and thus, we scientifically validate the use of A. pluriseta as a potential source for the discovery of novel antitubercular agents.
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- 2020
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7. Antennal Enriched Odorant Binding Proteins Are Required for Odor Communication in Glossina f. fuscipes
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Souleymane Diallo, Mohd Shahbaaz, JohnMark O. Makwatta, Jackson M. Muema, Daniel Masiga, Alan Christofells, and Merid N. Getahun
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Glossina sp. ,odorant-binding proteins ,gene expression ,structural properties ,molecular docking ,dsRNAi ,Microbiology ,QR1-502 - Abstract
Olfaction is orchestrated at different stages and involves various proteins at each step. For example, odorant-binding proteins (OBPs) are soluble proteins found in sensillum lymph that might encounter odorants before reaching the odorant receptors. In tsetse flies, the function of OBPs in olfaction is less understood. Here, we investigated the role of OBPs in Glossina fuscipes fuscipes olfaction, the main vector of sleeping sickness, using multidisciplinary approaches. Our tissue expression study demonstrated that GffLush was conserved in legs and antenna in both sexes, whereas GffObp44 and GffObp69 were expressed in the legs but absent in the antenna. GffObp99 was absent in the female antenna but expressed in the male antenna. Short odorant exposure induced a fast alteration in the transcription of OBP genes. Furthermore, we successfully silenced a specific OBP expressed in the antenna via dsRNAi feeding to decipher its function. We found that silencing OBPs that interact with 1-octen-3-ol significantly abolished flies’ attraction to 1-octen-3-ol, a known attractant for tsetse fly. However, OBPs that demonstrated a weak interaction with 1-octen-3-ol did not affect the behavioral response, even though it was successfully silenced. Thus, OBPs’ selective interaction with ligands, their expression in the antenna and their significant impact on behavior when silenced demonstrated their direct involvement in olfaction.
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- 2021
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8. Prospects for malaria control through manipulation of mosquito larval habitats and olfactory-mediated behavioural responses using plant-derived compounds
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Jackson M. Muema, Joel L. Bargul, Sospeter N. Njeru, Joab O. Onyango, and Susan S. Imbahale
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Malaria ,Vector control ,Anopheline mosquitoes ,Plant-derived compounds ,Larval habitat manipulation ,Mosquito functional ecology ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Malaria presents an overwhelming public health challenge, particularly in sub-Saharan Africa where vector favourable conditions and poverty prevail, potentiating the disease burden. Behavioural variability of malaria vectors poses a great challenge to existing vector control programmes with insecticide resistance already acquired to nearly all available chemical compounds. Thus, approaches incorporating plant-derived compounds to manipulate semiochemical-mediated behaviours through disruption of mosquito olfactory sensory system have considerably gained interests to interrupt malaria transmission cycle. The combination of push-pull methods and larval control have the potential to reduce malaria vector populations, thus minimising the risk of contracting malaria especially in resource-constrained communities where access to synthetic insecticides is a challenge. In this review, we have compiled information regarding the current status of knowledge on manipulation of larval ecology and chemical-mediated behaviour of adult mosquitoes with plant-derived compounds for controlling mosquito populations. Further, an update on the current advancements in technologies to improve longevity and efficiency of these compounds for field applications has been provided.
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- 2017
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9. Molecular characterization of pathogenic African trypanosomes in biting flies and camels in surra-endemic areas outside the tsetse fly belt in Kenya
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Merid N. Getahun, Jandouwe Villinger, Joel L. Bargul, Jackson M. Muema, Abel Orone, John Ngiela, Peter O. Ahuya, Rajinder K. Saini, Baldwyn Torto, and Daniel K. Masiga
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Insect Science ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
10. Transmission of 'Candidatus Anaplasma camelii' to mice and rabbits by camel-specific keds, Hippobosca camelina
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Joel L. Bargul, Mark Carrington, Kevin O Kidambasi, Jandouwe Villinger, Daniel K. Masiga, Robert S. Copeland, Merid N. Getahun, Jackson M. Muema, Bargul, Joel L [0000-0001-8573-6807], Copeland, Robert S [0000-0003-4865-5412], Muema, Jackson M [0000-0002-5713-5067], Apollo - University of Cambridge Repository, Villinger, Jandouwe [0000-0002-5097-6605], Bargul, Joel L. [0000-0001-8573-6807], Copeland, Robert S. [0000-0003-4865-5412], and Muema, Jackson M. [0000-0002-5713-5067]
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Veterinary medicine ,Anaplasmosis ,Physiology ,animal diseases ,RC955-962 ,Rickettsiales ,Disease Vectors ,Pathology and Laboratory Medicine ,Biochemistry ,law.invention ,Rodent Diseases ,Mice ,Camels ,law ,Arctic medicine. Tropical medicine ,Medicine and Health Sciences ,Pathogen ,Polymerase chain reaction ,Animal Management ,Mammals ,biology ,Eukaryota ,Agriculture ,Animal Models ,Anaplasmataceae ,Bacterial Pathogens ,Body Fluids ,Nucleic acids ,Infectious Diseases ,Blood ,Experimental Organism Systems ,Ribosomal RNA ,Medical Microbiology ,Vertebrates ,Leporids ,Livestock ,Seasons ,Rabbits ,Public aspects of medicine ,RA1-1270 ,Pathogens ,Anatomy ,Research Article ,Cell biology ,endocrine system ,Cellular structures and organelles ,Anaplasma ,Camelus ,Research and Analysis Methods ,Microbiology ,parasitic diseases ,medicine ,Animals ,Non-coding RNA ,Microbial Pathogens ,Bacteria ,business.industry ,Diptera ,Public Health, Environmental and Occupational Health ,Organisms ,Biology and Life Sciences ,biology.organism_classification ,medicine.disease ,bacterial infections and mycoses ,Kenya ,Camelina ,Vector (epidemiology) ,Amniotes ,Animal Studies ,Earth Sciences ,RNA ,bacteria ,business ,Zoology ,Ribosomes - Abstract
Funder: uk’s foreign, commonwealth & development office, Funder: swedish international development cooperation agency, Funder: swiss agency for development and cooperation, Funder: federal democratic republic of ethiopia, Funder: government of the republic of kenya, Anaplasmosis, caused by infection with bacteria of the genus Anaplasma, is an important veterinary and zoonotic disease. Transmission by ticks has been characterized but little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence of Anaplasma spp. in camels in northern Kenya and whether the hematophagous camel ked, Hippobosca camelina, acts as a vector. Camels (n = 976) and > 10,000 keds were sampled over a three-year study period and the presence of Anaplasma species was determined by PCR-based assays targeting the Anaplasmataceae 16S rRNA gene. Camels were infected by a single species of Anaplasma, ‘Candidatus Anaplasma camelii’, with infection rates ranging from 63–78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10–29% of camel keds harbored ‘Ca. Anaplasma camelii’ acquired from infected camels during blood feeding. We determined that Anaplasma-positive camel keds could transmit ‘Ca. Anaplasma camelii’ to mice and rabbits via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by microscopic observation in blood smears and by PCR. Transmission of ‘Ca. Anaplasma camelii’ to mice (8–47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential of H. camelina as a vector of anaplasmosis. This key finding provides the rationale for establishing ked control programmes for improvement of livestock and human health.
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- 2021
11. Transmission of ‘CandidatusAnaplasma camelii’ to laboratory animals by camel-specific keds,Hippobosca camelina
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Merid N. Getahun, Joel L. Bargul, Jackson M. Muema, Ogola Kk, Robert S. Copeland, Mark Carrington, Jandouwe Villinger, and Daniel K. Masiga
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Veterinary medicine ,Hippobosca ,biology ,Stomoxys ,Louse ,biology.organism_classification ,medicine.disease_cause ,medicine.disease ,Anaplasmataceae ,biology.animal ,Vector (epidemiology) ,Infestation ,medicine ,Anaplasma ,Anaplasmosis - Abstract
Anaplasmosis, caused by infection with bacteria of the genusAnaplasmais an important veterinary and zoonotic disease. The characterization of transmission has concentrated on ticks and little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence ofAnaplasmaspp. in camels in northern Kenya and whether the hematophagous camel ked,Hippobosca camelina, acts as a vector. Camels (n =976) and > 10,000 keds were sampled over a three-year study period and the presence ofAnaplasmaspecies was determined by PCR-based assays targeting theAnaplasmataceae16S rRNA gene. Camels were infected by‘CandidatusAnaplasma camelii’occurring from 63 - 78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10 - 29% of camel keds harbored ‘Ca. Anaplasma camelii’ acquired from infected camels during blood feeding. We determined whetherAnaplasmapositive camel keds could transmit ‘Ca. Anaplasma camelii’ to small laboratory animals via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by both direct detection in blood smears and subsequent molecular identification by PCR. Transmission of ‘Ca. Anaplasma camelii’ to mice (8 - 47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential ofH. camelinaas a vector of anaplasmosis. This key finding provides the basis for establishing ked control programmes for improvement of livestock and human health.Author summaryHematophagous flies such as Tabanids andStomoxys, among other biting flies, are mechanical transmitters of various pathogens such as African trypanosomes andAnaplasmaspecies. However, little is known about the role of common camel-specific biting keds (also known as camel flies or louse flies, genusHippobosca) in pathogen transmission. Keds inflict painful bites to access host blood, and in the process may transmit bacterial hemopathogens frequently detected in both camels and their keds. We confirmed by experimental blood-feeding, gene amplification, and amplicon sequencing that camel keds can transmit “CandidatusAnaplasma camelii” from naturally-infected camels to healthy mice and rabbits. The high prevalence of camel anaplasmosis throughout the year in northern Kenya could be explained by the infestation camel-specificH. camelina, whose capacity as efficient fliers, unlike ticks, promotes disease transmission and maintenance within and among camel herds. Although this study focused on the transmission ofAnaplasmasp. by camel keds, it is possible that other hemopathogens could also be transmitted by these flies through a similar mechanism. Notably, in the absence of their preferred hosts, keds occasionally bite humans and other vertebrates they come across in order to acquire bloodmeals, and in the process could transmit zoonotic pathogens.
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- 2021
12. Antennal Enriched Odorant Binding Proteins Are Required for Odor Communication in Glossina f. fuscipes
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Daniel K. Masiga, JohnMark O. Makwatta, Alan Christofells, Jackson M. Muema, Mohd Shahbaaz, Merid N. Getahun, and Souleymane Diallo
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0301 basic medicine ,Arthropod Antennae ,Male ,Octanols ,Tsetse Flies ,Odorant binding ,lcsh:QR1-502 ,odorant-binding proteins ,Olfaction ,Molecular Dynamics Simulation ,Receptors, Odorant ,Biochemistry ,lcsh:Microbiology ,Article ,03 medical and health sciences ,0302 clinical medicine ,Gene expression ,Glossina sp ,Animals ,Amino Acid Sequence ,RNA, Small Interfering ,Molecular Biology ,Sensillum ,Antenna (biology) ,structural properties ,Binding Sites ,biology ,fungi ,Tsetse fly ,molecular docking ,dsRNAi ,biology.organism_classification ,Cell biology ,Animal Communication ,Molecular Docking Simulation ,030104 developmental biology ,Odor ,gene expression ,Insect Proteins ,Female ,RNA Interference ,Sequence Alignment ,030217 neurology & neurosurgery ,Function (biology) - Abstract
Olfaction is orchestrated at different stages and involves various proteins at each step. For example, odorant-binding proteins (OBPs) are soluble proteins found in sensillum lymph that might encounter odorants before reaching the odorant receptors. In tsetse flies, the function of OBPs in olfaction is less understood. Here, we investigated the role of OBPs in Glossina fuscipes fuscipes olfaction, the main vector of sleeping sickness, using multidisciplinary approaches. Our tissue expression study demonstrated that GffLush was conserved in legs and antenna in both sexes, whereas GffObp44 and GffObp69 were expressed in the legs but absent in the antenna. GffObp99 was absent in the female antenna but expressed in the male antenna. Short odorant exposure induced a fast alteration in the transcription of OBP genes. Furthermore, we successfully silenced a specific OBP expressed in the antenna via dsRNAi feeding to decipher its function. We found that silencing OBPs that interact with 1-octen-3-ol significantly abolished flies’ attraction to 1-octen-3-ol, a known attractant for tsetse fly. However, OBPs that demonstrated a weak interaction with 1-octen-3-ol did not affect the behavioral response, even though it was successfully silenced. Thus, OBPs’ selective interaction with ligands, their expression in the antenna and their significant impact on behavior when silenced demonstrated their direct involvement in olfaction.
- Published
- 2021
13. Neurotoxic Zanthoxylum chalybeum root constituents invoke mosquito larval growth retardation through ecdysteroidogenic CYP450s transcriptional perturbations
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James M. Mutunga, Jackson M. Muema, Joel L. Bargul, Sospeter Ngoci Njeru, Meshack Obonyo, and George O. Asudi
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Zanthoxylum ,Insecticides ,Mosquito Control ,Aché ,Health, Toxicology and Mutagenesis ,Anopheles gambiae ,Linoleic acid ,Aedes aegypti ,Mosquito Vectors ,Palmitic acid ,chemistry.chemical_compound ,Sesamin ,Aedes ,parasitic diseases ,Animals ,Growth Disorders ,Larva ,biology ,Plant Extracts ,fungi ,General Medicine ,biology.organism_classification ,Acetylcholinesterase ,language.human_language ,Culex ,chemistry ,Biochemistry ,language ,Agronomy and Crop Science - Abstract
Intracellular effects exerted by phytochemicals eliciting insect growth-retarding responses during vector control intervention remain largely underexplored. We studied the effects of Zanthoxylum chalybeum Engl. (Rutaceae) (ZCE) root derivatives against malaria (Anopheles gambiae) and arbovirus vector (Aedes aegypti) larvae to decipher possible molecular targets. We report dose-dependent biphasic effects on larval response, with transient exposure to ZCE and its bioactive fraction (ZCFr.5) inhibiting acetylcholinesterase (AChE) activity, inducing larval lethality and growth retardation at sublethal doses. Half-maximal lethal concentrations (LC50) for ZCE against An. gambiae and Ae. aegypti larvae after 24-h exposure were 9.00 ppm and 12.26 ppm, respectively. The active fraction ZCFr.5 exerted LC50 of 1.58 ppm and 3.21 ppm for An. gambiae and Ae. aegypti larvae, respectively. Inhibition of AChE was potentially linked to larval toxicity afforded by 2-tridecanone, palmitic acid (hexadecanoic acid), linoleic acid ((Z,Z)-9,12-octadecadienoic acid), sesamin, β-caryophyllene among other compounds identified in the bioactive fraction. In addition, the phenotypic larval retardation induced by ZCE root constituents was exerted through transcriptional modulation of ecdysteroidogenic CYP450 genes. Collectively, these findings provide an explorative avenue for developing potential mosquito control agents from Z. chalybeum root constituents.
- Published
- 2021
14. Diversity and Molecular Characterization of Mosquitoes (Diptera: Culicidae) in selected ecological regions in Kenya
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Gladys Kemunto, Lucy Wamuyu, Jackson M. Muema, Moni Makanda, James M. Mutunga, and Joel L. Bargul
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0301 basic medicine ,chikungunya ,030231 tropical medicine ,Zoology ,Mosquito Vectors ,Biology ,medicine.disease_cause ,General Biochemistry, Genetics and Molecular Biology ,Dengue fever ,03 medical and health sciences ,0302 clinical medicine ,Aedes ,parasitic diseases ,Anopheles ,medicine ,Animals ,dengue fever ,Chikungunya ,General Pharmacology, Toxicology and Pharmaceutics ,Rift Valley fever ,Gene ,Phylogeny ,Genetic diversity ,General Immunology and Microbiology ,Phylogenetic tree ,Haplotype ,Outbreak ,General Medicine ,Articles ,medicine.disease ,Kenya ,3. Good health ,Culex ,030104 developmental biology ,Research Article - Abstract
Mosquitoes play a predominant role as leading agents in the spread of vector-borne diseases and the consequent mortality in humans. Despite reports on increase of new and recurrent mosquito borne-disease outbreaks such as chikungunya, dengue fever and Rift Valley fever in Kenya, little is known about the genetic characteristics and diversity of the vector species that have been incriminated in transmission of disease pathogens. In this study, mosquito species were collected from Kisumu city, Kilifi town and Nairobi city and we determined their genetic diversity and phylogenetic relationships. PCR was used to amplify the partial cytochrome oxidase subunit 1 (CO1) gene of mosquito samples. Molecular-genetic and phylogenetic analysis of the partial cytochrome oxidase subunit 1 (CO1) gene were employed to identify their relationship with known mosquito species. Fourteen (14) haplotypes belonging to genusAedes, nine (9) haplotypes belonging to genusAnophelesand twelve (12) haplotypes belonging to genusCulexwere identified in this study. Findings from this study revealed a potentially new haplotype belonging toAnophelesgenus and reported the first molecular characterization ofAedes cumminsiiin Kenya. Sequence results revealed variation in mosquito species from Kilifi, Kisumu and Nairobi. Since vector competence varies greatly across species as well as species-complexes and is strongly associated with specific behavioural adaptations, proper species identification is important for vector control programs.
- Published
- 2019
15. Antimicrobial activity, phytochemical characterization and gas chromatography-mass spectrometry analysis of Aspilia pluriseta Schweinf. extracts
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Jackson M. Muema and Sospeter Ngoci Njeru
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0301 basic medicine ,medicine.drug_class ,Phytochemicals ,Ethyl acetate ,Antimycobacterial ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Alkanes ,Anthraquinones ,medicine ,Tuberculosis ,Petroleum ether ,lcsh:Social sciences (General) ,lcsh:Science (General) ,Multidisciplinary ,Chromatography ,Mycobacterium tuberculosis ,Antimicrobial ,Terpenoid ,030104 developmental biology ,Phytochemical ,chemistry ,Drug resistance ,Fatty acid alkyl esters ,lcsh:H1-99 ,Gas chromatography–mass spectrometry ,030217 neurology & neurosurgery ,lcsh:Q1-390 - Abstract
Aspilia pluriseta is associated with various bioactivities, although with limited scientific justification. In this study, we evaluated the antimicrobial activity, and characterized the phytochemicals of root extracts of A. pluriseta aimed at validating its therapeutic potential. We used BACTEC MGIT™ 960 system to test for antitubercular activity, disc-diffusion together with the microdilution method to evaluate antimicrobial activities and qualitative phytochemical tests together with gas chromatography-mass spectrometry (GC-MS) analysis to determine the phytochemicals that associated with A. pluriseta extracts activity. We show that methanolic crude extract (at 1 g/mL) had high Mycobacterium tuberculosis (MTB) inhibitory activity (0 growth unit) and considerable potency against Escherichia coli (11.7 mm), Staphylococcus aureus (9.0 mm), and Candida albicans (7.7 mm). All the extract fractions exerted remarkable antimycobacterial activities with minimum inhibitory activity of between 6.26 – 25 μg/mL. The highest antimicrobial activity of petroleum ether and dichloromethane fraction was against E. coli at inhibition zone diameters of 8.3 mm, and 8.0 mm, respectively, while ethyl acetate fraction was against S. aureus with an inhibition zone of 8.7 mm. Methanolic fraction exhibited broad-spectrum activity against 87.5% of the tested microbes (inhibition zones 6.3–8.3 mm). Furthermore, we qualitatively detected terpenoids, alkaloids, and phenolics such as flavonoids, and anthraquinones in extract fractions. GC-MS analysis detected an abundance of fatty acid esters, 2-hydroxy-1-(hydroxymethyl) ethyl ester-hexadecanoic acid, and 2,3-dihydroxy propyl ester-octadecanoic acid and four alkanes. Taken together, we show that A. pluriseta extract fractions (especially ethyl acetate and methanolic fractions) have strong selective antitubercular activity, and thus, we scientifically validate the use of A. pluriseta as a potential source for the discovery of novel antitubercular agents.
- Published
- 2020
16. Green tea proanthocyanidins cause impairment of hormone-regulated larval development and reproductive fitness via repression of juvenile hormone acid methyltransferase, insulin-like peptide and cytochrome P450 genes in Anopheles gambiae sensu stricto
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Steven G. Nyanjom, Jackson M. Muema, Sospeter Ngoci Njeru, James M. Mutunga, and Joel L. Bargul
- Subjects
0301 basic medicine ,Life Cycles ,Anopheles gambiae ,lcsh:Medicine ,Gene Expression ,Disease Vectors ,Toxicology ,Pathology and Laboratory Medicine ,Mosquitoes ,Biochemistry ,0302 clinical medicine ,Larvae ,Cytochrome P-450 Enzyme System ,Gene expression ,Medicine and Health Sciences ,Insulin ,lcsh:Science ,Larva ,Multidisciplinary ,biology ,Insects ,Juvenile Hormones ,Phenotypes ,Infectious Diseases ,Toxicity ,Research Article ,Arthropoda ,030231 tropical medicine ,Biosynthesis ,Andrology ,03 medical and health sciences ,Anopheles ,Genetics ,Parasitic Diseases ,Animals ,Proanthocyanidins ,Dose-Response Relationship, Drug ,Tea ,lcsh:R ,Organisms ,Cytochrome P450 ,Biology and Life Sciences ,Methyltransferases ,biology.organism_classification ,Tropical Diseases ,Molecular biology ,Invertebrates ,Hormones ,Insect Vectors ,Malaria ,Species Interactions ,030104 developmental biology ,Juvenile hormone ,biology.protein ,lcsh:Q ,Vitellogenesis ,Hormone ,Developmental Biology - Abstract
Successful optimization of plant-derived compounds into control of nuisance insects would benefit from scientifically validated targets. However, the close association between the genotypic responses and physiological toxicity effects mediated by these compounds remains underexplored. In this study, we evaluated the sublethal dose effects of proanthocyanidins (PAs) sourced from green tea (Camellia sinensis) on life history traits of Anopheles gambiae (sensu stricto) mosquitoes with an aim to unravel the probable molecular targets. Based on the induced phenotypic effects, genes selected for study targeted juvenile hormone (JH) biosynthesis, signal transduction, oxidative stress response and xenobiotic detoxification in addition to vitellogenesis in females. Our findings suggest that chronic exposure of larval stages (L3/L4) to sublethal dose of 5 ppm dramatically extended larval developmental period for up to 12 days, slowed down pupation rates, induced abnormal larval-pupal intermediates and caused 100% inhibition of adult emergence. Further, females exhibited significant interference of fecundity and egg hatchability relative to controls (p < 0.001). Using reverse transcription quantitative polymerase chain reaction (RT-qPCR), our findings show that PA-treated larvae exhibited significant repression of AgamJHAMT (p < 0.001), AgamILP1 (p < 0.001) and AgamCYP6M2 (p < 0.001) with up-regulation of Hsp70 (p < 0.001). Females exposed as larvae demonstrated down-regulation of AgamVg (p = 0.03), AgamILP1 (p = 0.009), AgamCYP6M2 (p = 0.05) and AgamJHAMT (p = 0.02). Our findings support that C. sinensis proanthocyanidins affect important vectorial capacity components such as mosquito survival rates and reproductive fitness thus could be potentially used for controlling populations of malaria vectors.
- Published
- 2017
17. Prospects for malaria control through manipulation of mosquito larval habitats and olfactory-mediated behavioural responses using plant-derived compounds
- Author
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Sospeter Ngoci Njeru, Susan S Imbahale, Joab O. Onyango, Jackson M. Muema, and Joel L. Bargul
- Subjects
0301 basic medicine ,Mosquito Control ,media_common.quotation_subject ,Ecology (disciplines) ,030231 tropical medicine ,Phytochemicals ,Larval habitats ,Review ,Biology ,Pheromones ,lcsh:Infectious and parasitic diseases ,03 medical and health sciences ,0302 clinical medicine ,Anopheline mosquitoes ,Malaria transmission ,parasitic diseases ,medicine ,Disease Transmission, Infectious ,Animals ,Humans ,lcsh:RC109-216 ,Disease burden ,media_common ,Ecology ,business.industry ,Longevity ,medicine.disease ,Vector control ,Larval habitat manipulation ,Biotechnology ,Malaria ,030104 developmental biology ,Infectious Diseases ,Vector (epidemiology) ,Insect Repellents ,Plant-derived compounds ,Parasitology ,Mosquito functional ecology ,Integrated vector management ,Malaria control ,business - Abstract
Malaria presents an overwhelming public health challenge, particularly in sub-Saharan Africa where vector favourable conditions and poverty prevail, potentiating the disease burden. Behavioural variability of malaria vectors poses a great challenge to existing vector control programmes with insecticide resistance already acquired to nearly all available chemical compounds. Thus, approaches incorporating plant-derived compounds to manipulate semiochemical-mediated behaviours through disruption of mosquito olfactory sensory system have considerably gained interests to interrupt malaria transmission cycle. The combination of push-pull methods and larval control have the potential to reduce malaria vector populations, thus minimising the risk of contracting malaria especially in resource-constrained communities where access to synthetic insecticides is a challenge. In this review, we have compiled information regarding the current status of knowledge on manipulation of larval ecology and chemical-mediated behaviour of adult mosquitoes with plant-derived compounds for controlling mosquito populations. Further, an update on the current advancements in technologies to improve longevity and efficiency of these compounds for field applications has been provided.
- Published
- 2016
18. Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae
- Author
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Sospeter Ngoci Njeru, Rose Marubu, Céline Colombier, and Jackson M. Muema
- Subjects
0301 basic medicine ,Veterinary medicine ,Insecticides ,Anopheles gambiae ,030231 tropical medicine ,Biology ,Asteraceae ,Agerantum conyzoides ,Toxicology ,Growth disruption ,03 medical and health sciences ,0302 clinical medicine ,Larvicidal activity ,parasitic diseases ,Anopheles ,medicine ,Juvenile ,Animals ,Larva ,fungi ,General Medicine ,medicine.disease ,biology.organism_classification ,Vector control ,Malaria ,Anopheles gambiae s.s ,Mosquito control ,Anopheles arabiensis ,030104 developmental biology ,Phytochemical ,Complementary and alternative medicine ,Toxicity ,Instar ,Research Article - Abstract
Background Vector control remains the mainstay to effective malaria management. The negative implications following persistent application of synthetic insecticides geared towards regulation of mosquito populations have necessitated prospection for ecofriendly effective chemistries. Plant-derived compounds have the potential to control malaria-transmitting mosquito populations. Previously, Agerantum conyzoides extracts have demonstrated toxicity effects on disease-transmitting mosquitoes. However, their efficacy in controlling Afrotropical malaria vectors remains unclear. Herein, the toxicity and growth disruption activities of crude methanolic leaf extract of A. conyzoides on Anopheles gambiae sensu stricto and An. arabiensis larvae were assessed. Methods Late third (L3) instars of An. gambiae s.s and An. arabiensis larvae were challenged with increasing doses of crude methanolic extract of A. conyzoides. The larval mortality rates were recorded every 24 h and the LC50 values determined at their associated 95% confidence levels. ANOVA followed by Post-hoc Student-Newman-Keuls (SNK) test was used to compare results between treatment and control groups. Phytochemical profiling of the extract was performed using standard chemical procedures. Results Treatment of larvae with the methanolic extract depicted dose-dependent effects with highest mortality percentages of ≥ 69% observed when exposed with 250 ppm and 500 ppm for 48 h while growth disruption effects were induced by sublethal doses of between 50–100 ppm for both species. Relative to experimental controls, the extract significantly reduced larval survival in both mosquito species (ANOVA, F(8,126) = 43.16776, P
- Published
- 2016
19. Potential of Camellia sinensis proanthocyanidins-rich fraction for controlling malaria mosquito populations through disruption of larval development
- Author
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James M. Mutunga, Joel L. Bargul, Sospeter Ngoci Njeru, Steven G. Nyanjom, and Jackson M. Muema
- Subjects
0301 basic medicine ,Veterinary medicine ,030231 tropical medicine ,Green tea extract ,Biology ,Camellia sinensis ,03 medical and health sciences ,0302 clinical medicine ,Larvicidal activity ,Botany ,parasitic diseases ,medicine ,Proanthocyanidins ,Anopheles gambiae (sensu stricto) ,Larva ,Research ,fungi ,medicine.disease ,Vector control ,Anopheles arabiensis ,030104 developmental biology ,Infectious Diseases ,Parasitology ,Proanthocyanidin ,Vector (epidemiology) ,Instar ,Malaria - Abstract
Background Anopheles arabiensis and A. gambiae (sensu stricto) are the most prolific Afrotropical malaria vectors. Population control efforts of these two vectors have been hampered by extremely diverse larval breeding sites and widespread resistance to currently available insecticides. Control of mosquito larval stages using bioactive compounds of plant origin has the potential to suppress vector populations leading to concomitant reduction in disease transmission rates. In this study, we evaluated the efficacy of Camellia sinensis crude leaf extract and its fraction against the larvae of A. arabiensis and A. gambiae (s.s.). Methods Late third/early fourth instar larvae (L3/L4) of A. arabiensis and A. gambiae (s.s.) were exposed to increasing doses of C. sinensis leaf extract and its active fraction for 72 h, with mortality rates recorded every 24 h in both control and test groups. Ultra performance liquid chromatography electron spray ionization quadruple time of flight coupled with mass spectrometry (UPLC/ESI-Qtof/MS) was used to determine the main active constituents in the fraction. Results The major bioactive chemical constituents in the C. sinensis leaf extract were identified to be proanthocyanidins. The extract significantly interfered with larval survival and adult emergence in both species (ANOVA, F(5,24) = 1435.92, P
- Published
- 2016
20. Transmission of 'Candidatus Anaplasma camelii' to mice and rabbits by camel-specific keds, Hippobosca camelina.
- Author
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Joel L Bargul, Kevin O Kidambasi, Merid N Getahun, Jandouwe Villinger, Robert S Copeland, Jackson M Muema, Mark Carrington, and Daniel K Masiga
- Subjects
Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
Anaplasmosis, caused by infection with bacteria of the genus Anaplasma, is an important veterinary and zoonotic disease. Transmission by ticks has been characterized but little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence of Anaplasma spp. in camels in northern Kenya and whether the hematophagous camel ked, Hippobosca camelina, acts as a vector. Camels (n = 976) and > 10,000 keds were sampled over a three-year study period and the presence of Anaplasma species was determined by PCR-based assays targeting the Anaplasmataceae 16S rRNA gene. Camels were infected by a single species of Anaplasma, 'Candidatus Anaplasma camelii', with infection rates ranging from 63-78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10-29% of camel keds harbored 'Ca. Anaplasma camelii' acquired from infected camels during blood feeding. We determined that Anaplasma-positive camel keds could transmit 'Ca. Anaplasma camelii' to mice and rabbits via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by microscopic observation in blood smears and by PCR. Transmission of 'Ca. Anaplasma camelii' to mice (8-47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential of H. camelina as a vector of anaplasmosis. This key finding provides the rationale for establishing ked control programmes for improvement of livestock and human health.
- Published
- 2021
- Full Text
- View/download PDF
21. Green tea proanthocyanidins cause impairment of hormone-regulated larval development and reproductive fitness via repression of juvenile hormone acid methyltransferase, insulin-like peptide and cytochrome P450 genes in Anopheles gambiae sensu stricto.
- Author
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Jackson M Muema, Steven G Nyanjom, James M Mutunga, Sospeter N Njeru, and Joel L Bargul
- Subjects
Medicine ,Science - Abstract
Successful optimization of plant-derived compounds into control of nuisance insects would benefit from scientifically validated targets. However, the close association between the genotypic responses and physiological toxicity effects mediated by these compounds remains underexplored. In this study, we evaluated the sublethal dose effects of proanthocyanidins (PAs) sourced from green tea (Camellia sinensis) on life history traits of Anopheles gambiae (sensu stricto) mosquitoes with an aim to unravel the probable molecular targets. Based on the induced phenotypic effects, genes selected for study targeted juvenile hormone (JH) biosynthesis, signal transduction, oxidative stress response and xenobiotic detoxification in addition to vitellogenesis in females. Our findings suggest that chronic exposure of larval stages (L3/L4) to sublethal dose of 5 ppm dramatically extended larval developmental period for up to 12 days, slowed down pupation rates, induced abnormal larval-pupal intermediates and caused 100% inhibition of adult emergence. Further, females exhibited significant interference of fecundity and egg hatchability relative to controls (p < 0.001). Using reverse transcription quantitative polymerase chain reaction (RT-qPCR), our findings show that PA-treated larvae exhibited significant repression of AgamJHAMT (p < 0.001), AgamILP1 (p < 0.001) and AgamCYP6M2 (p < 0.001) with up-regulation of Hsp70 (p < 0.001). Females exposed as larvae demonstrated down-regulation of AgamVg (p = 0.03), AgamILP1 (p = 0.009), AgamCYP6M2 (p = 0.05) and AgamJHAMT (p = 0.02). Our findings support that C. sinensis proanthocyanidins affect important vectorial capacity components such as mosquito survival rates and reproductive fitness thus could be potentially used for controlling populations of malaria vectors.
- Published
- 2017
- Full Text
- View/download PDF
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