Articles: Department of Biological Sciences
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Item 16S-rRNA-based analysis of bacterial diversity in the gut of fungus-cultivating termites (Microtermes and Odontotermes species)(Springer Netherlands, 2013-08-14) Makonde, Huxley M.; Boga, Hamadi I.; Mwirichia, Romano K.; Mackenzie, Lucy; Göker, Markus; Klenk, Hans-PeterThe interaction between termites and their gut symbionts has continued to attract the curiosity of researchers over time. The aim of this study was to characterize and compare the bacterial diversity and community structure in the guts of three termites (Odontotermes somaliensis, Odontotermes sp. and Microtermes sp.) using 16S rRNA gene sequencing of clone libraries. Clone libraries were screened by restriction fragment length polymorphism and representative clones from O. somaliensis (100 out of 330 clones), Odontotermes sp. (100 out of 359 clones) and Microtermes sp. (96 out 336 clones) were sequenced. Phylogenetic analysis indicated seven bacterial phyla were represented: Bacteroidetes, Spirochaetes, Firmicutes, Proteobacteria, Synergistetes, Planctomycetes and Actinobacteria. Sequences representing the phylum Bacteroidetes (>60 %) were the most abundant group in Odontotermes while those of Spirochaetes (29 %) and Firmicutes (23 %) were the abundant groups in Microtermes. The gut bacterial community structure within the two Odontotermes species investigated here was almost identical at the phylum level, but the Microtermes sp. had a unique bacterial community structure. Bacterial diversity was higher in Odontotermes than in Microtermes. The affiliation and clustering of the sequences, often with those from other termites’ guts, indicate a majority of the gut bacteria are autochthonous having mutualistic relationships with their hosts. The findings underscore the presence of termite-specific bacterial lineages, the majority of which are still uncultured.Item 454 Pyrosequencing‑based assessment of bacterial diversity and community structure in termite guts, mounds and surrounding soils(2015-09) Makonde, Huxley M.; Mwirichia, Romano; Osiemo, Zipporah; Boga, Hamadi I.; Klenk, Hans‑PeterTermites constitute part of diverse and economically important termite fauna in Africa, but information on gut microbiota and their associated soil microbiome is still inadequate. In this study, we assessed and compared the bacterial diversity and community structure between termites’ gut, their mounds and surrounding soil using the 454 pyrosequencing-based analysis of 16S rRNA gene sequences. A wood-feeder termite (Microcerotermes sp.), three fungus-cultivating termites (Macrotermes michaelseni, Odontotermes sp. and Microtermes sp.), their associated mounds and corresponding savannah soil samples were analyzed. The pH of the gut homogenates and soil physico-chemical properties were determined. The results indicated significant difference in bacterial community composition and structure between the gut and corresponding soil samples. Soil samples (Chao1 index ranged from 1359 to 2619) had higher species richness than gut samples (Chao1 index ranged from 461 to 1527). The bacterial composition and community structure in the gut of Macrotermes michaelseni and Odontotermes sp. were almost identical but different from that of Microtermes and Microcerotermes species, which had unique community structures. The most predominant bacterial phyla in the gut were Bacteroidetes (40–58 %), Spirochaetes (10–70 %), Firmicutes (17–27 %) and Fibrobacteres (13 %) while in the soil samples were Acidobacteria (28–45 %), Actinobacteria (20–40 %) and Proteobacteria (18–24 %). Some termite gut-specific bacterial lineages belonging to the genera Dysgonomonas, Parabacteroides, Paludibacter, Tannerella, Alistipes, BCf9-17 termite group and Termite Treponema cluster were observed. The results not only demonstrated a high level of bacterial diversity in the gut and surrounding soil environments, but also presence of distinct bacterial communities that are yet to be cultivated. Therefore, combined efforts using both culture and culture-independent methods are suggested to comprehensively characterize the bacterial species and their specific roles in these environments.Item Advances in the development of molecular genetic tools for Mycobacterium tuberculosis(Elsevier, 2018-07) Chiranjibi, Chhotaray; Yaoju, Tan; Mugweru, Julius; Islam, Md Mahmudul; Hameed, H.M. Adnan; Wang, Shuai; Lu, Zhili; Wang, Changwei; Li, Xinjie; Tan, Shouyong; Liu, Jianxiong; Zhang, TianyuMycobacterium tuberculosis, a Gram-positive bacterium of great clinical relevance, is a lethal pathogen owing to its complex physiological characteristics and development of drug resistance. Several molecular genetic tools have been developed in the past few decades to study this microorganism. These tools have been instrumental in understanding how M. tuberculosis became a successful pathogen. Advanced molecular genetic tools have played a significant role in exploring the complex pathways involved in M. tuberculosis pathogenesis. Here, we review various molecular genetic tools used in the study of M. tuberculosis. Further, we discuss the applications of clustered regularly interspaced short palindromic repeat interference (CRISPRi), a novel technology recently applied in M. tuberculosis research to study target gene functions. Finally, prospective outcomes of the applications of molecular techniques in the field of M. tuberculosis genetic research are also discussed.Item Agro-morphological characterization of horned melon (Cucumis metuliferus) accessions from selected agro-ecological zones in Kenya(Australian Journal of crop science, 2020-09) Owino, Marline H.; Gichimu, Bernard M.; Muturi, Phyllis W.Morphological characterization of genotypes is fundamental in providing information on their genetic status to guide on their conservation and improvement. The objective of this study was to determine agro-morphological diversity within horned melon in Kenya. The study was carried out in two seasons at the University of Embu in Kenya. The study characterized 19 horned melon accessions collected from different agro-ecological zones in Eastern, Central and Western regions in Kenya. The experiment was laid out in a randomized complete block design with three replications. Morphological characterization of the accessions was based on melon descriptors from International Plant Genetic Resources Institute (IPGRI) with slight modifications. Significant differences were observed in all the quantitative traits except the number of branches and main vine length. However, qualitative variations were only observed in fruit shape, rind colour and seed shape. Principle Component Analysis (PCA) showed that fruit weight, main vine length and days to maturity had the highest contribution to the observed diversity. Cluster analysis separated the accessions into seven groups with between classes diversity of 79.20% and within classes diversity of 20.80%. The diversity observed can be exploited by plant breeders for genetic improvement of the crop.Item Agro-Morphological Characterization of Kenyan Slender Leaf (Crotalaria brevidens and C. ochroleuca) Accessions(Hindawi, 2020-04) Mwakha, Fridah A.; Gichimu, Bernard M.; Neondo, ohnstone O.; Kamau, Peter K.; Odari, Eddy O.; Muli, Joshua K.; Budambula, NancySlender leaf (Crotalaria spp) is among the indigenous and underutilized vegetables in Kenya whose production is limited to the Western and Coastal regions of the country. For a long time, this crop has been neglected in terms of research and genetic improvement. *ere is therefore scanty information on its morphological diversity and agronomic performance, hence the need for this study. Field experiments were carried out for two seasons in October to December 2018 and March to May 2019. *e experiments were laid out in Randomized Complete Block Design with 29 accessions and replicated three times. Both qualitative and quantitative data were recorded from the accessions based on the Crotalaria descriptors. Quantitative data were subjected to analysis of variance using XLSTAT Version 2019, and accession means were separated using Student’s Newman Keuls test at 95% level of confidence. Both qualitative and quantitative data were subjected to multivariate cluster analysis, and a dendrogram was constructed using the unweighted pair-group method with arithmetic average. *e principal component analysis was conducted to obtain information on the importance of the characters. Significant variation in agro-morphological traits was found within and between the two species. Cluster analysis grouped the accessions into seven major classes with a between-classes diversity of 75.13% and a within-classes diversity of 24.87%. *is study sets the basis for genetic improvement of slender leaf in Kenya since the observed diversity can be exploited in selection for intraspecific and interspecific hybridization.Item Amino acid neurotoxins in feathers of the Lesser Flamingo, Phoeniconaias minor(Elsevier, 2013-01) Metcalf, J.S.; Banack, S.A.; Kotut, Kiplagat; Krienitz, L.; Codd, G.A.The Lesser Flamingo (Phoeniconaias minor) is known to use cyanobacteria (primarily Arthrospira) as a major food source in the East African Rift Valley lakes. Periodically, mass mortalities have occurred, associated with the cyanobacterial toxins (cyanotoxins), microcystins and anatoxin-a. Deposition of these cyanotoxins into P. minor feathers has been shown to occur, consistent with the presence of cyanotoxins in the livers, stomach and faecal contents after dietary intake. As cyanobacteria have been shown to also produce the neurotoxins β-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB), stored wing feathers, previously recovered from flamingos which had been exposed to microcystins and anatoxin-a and had subsequently died, were analysed for these neurotoxic amino acids. Trace amounts of BMAA were detected in extracts from Lake Nakuru flamingo feathers, with DAB also present at concentrations between 3.5 and 8.5 μg g(-1) dry weight in feathers from both lakes. Toxin recovery by solid-phase extraction of feather digests was tested with spiked deuterated BMAA and showed good recovery when analysed by LC-MS/MS (80-94%). This is the first report of these neurotoxic amino acids in birds. We discuss the origin and significance of DAB, alongside other cyanotoxins of dietary origin, in the feathers of the Lesser Flamingo.Item Amplicon-based assessment of bacterial diversity and community structure in three tropical forest soils in Kenya(Heliyon, 2022-11) Kenya, Eucharia U.; Kinyanjui, Grace; Kipnyargis, Alex C.; Kinyua, Franklin; Mwangi, Mary; Khamis, Fathiya; Mwirichia, Romano K.Forest soils provide a multitude of habitats for diverse communities of bacteria. In this study, we selected three tropical forests in Kenya to determine the diversity and community structure of soil bacteria inhabiting these regions. Kakamega and Irangi are rainforests, whereas Gazi Bay harbors mangrove forests. The three natural forests occupy different altitudinal zones and differ in their environmental characteristics. Soil samples were collected from a total of 12 sites and soil physicochemical parameters for each sampling site were analyzed. We used an amplicon-based Illumina high-throughput sequencing approach. Total community DNA was extracted from individual samples using the phenol-chloroform method. The 16S ribosomal RNA gene segment spanning the V4 region was amplified using the Illumina MiSeq platform. Diversity indices, rarefaction curves, hierarchical clustering, principal component analysis (PCA), and non-metric multidimensional scaling (NMDS) analyses were performed in R software. A total of 13,410 OTUs were observed at 97% sequence similarity. Bacterial communities were dominated by Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Acidobacteria in both rainforest and mangrove sampling sites. Alpha diversity indices and species richness were higher in Kakamega and Irangi rainforests compared to mangroves in Gazi Bay. The composition of bacterial communities within and between the three forests was also significantly differentiated (R ¼ 0.559, p ¼ 0.007). Clustering in both PCA and NMDS plots showed that each sampling site had a distinct bacterial community profile. The NMDS analysis also indicated that soil EC, sodium, sulfur, magnesium, boron, and manganese contributed significantly to the observed variation in the bacterial community structure. Overall, this study demonstrated the presence of diverse taxa and heterogeneous community structures of soil bacteria inhabiting three tropical forests of Kenya. Our results also indicated that variation in soil chemical parameters was the major driver of the observed bacterial diversity and community structure in these forests.Item Analysis of genetic diversity in Eucalyptus grandis (Hill ex Maiden) seed sources using inter simple sequence repeats (ISSR) molecular markers(Academic Journals, 2008-07-04) Okun, D.O.; Kenya, Eucharia U.; Oballa, P.O.; Odee, D.W.; Muluvi, G.M.Eucalyptus grandis is an economically important tree species that is native to the Australian continent and its northern neighbours, where it is grown primarily for its hard wood timber and pulp for paper industries. It is widely grown in tropical countries such as South Africa, Kenya, Angola, Ghana, and Zimbabwe. Five ISSR primers generated 41 scorable polymorphic bands which were used to analyse genetic diversity between and within the seed sources and for construction of neighbour-joining phenogram. Mean Genetic Diversity per each primer loci based on Nei (1987) statistics indicated significant genetic variation between seed sources with 26.4%, (Gst = 0.264) of the total variation attributed to differences between seed sources. The variation between populations could be due to ecological, geographical association and gene flow rates and hence they should be conserved to retain the full breadth of genetic variation of the species. Thus, ISSR-PCR technology is a reliable, rapid (high throughput) and cost effective marker system that can be used to study genetic variation and genetic relationships among E. grandis seed sources.Item Analysis of the cyanotoxins anatoxin-a and microcystins in Lesser Flamingo feathers.(Taylor & Francis, 2006) Metcalf, J.S.; Morrison, L.F.; Krienitz, L.; Ballot, A.; Krause, E.; Kotut, Kiplagat; Pütz, S.; Wiegand, C.; Pflugmacher, S.; Codd, G.A.Feathers from carcasses of the Lesser Flamingo (Phoeniconaias minor), which had died after ingesting cyanobacterial toxins (cyanotoxins) contained between 0.02 and 30.0 µg microcystin-LR equivalents per gram of feather according to HPLC and ELISA analysis of feather extracts. Anatoxin-a was detected less frequently in the Lesser Flamingo feathers, up to 0.8 µg anatoxin-a per gram of feather being recorded. When feathers from different body regions were analysed and compared for microcystins and anatoxin-a, wing feathers were found to contain the highest concentrations of these cyanotoxins, the order of concentration and frequency of analytical detection being wing > breast > head. Consistent with the presence of the microcystins and anatoxin-a in gut contents and the livers of the dead birds and negligible in vitro adsorption to feathers, the cyanotoxins associated with the feathers of the dead wild flamingos are inferred to be primarily of dietary originItem Annotations of novel antennae-expressed genes in male Glossina morsitans morsitans tsetse flies(Plos 1, 2022-08) Bwana, Billiah K.; Mireji, Paul O.; Obiero, George F.; Gakii, Consolata; Akoth, Modesta O.; Mugweru, Julius N.; Nyabuga, Franklin N.; Wachira, Benson M.; Bateta, Rosemary; Ng’ang’a, Margaret M.; Hassanali, AhmedTsetse flies use antennal expressed genes to navigate their environment. While most canonical genes associated with chemoreception are annotated, potential gaps with important antennal genes are uncharacterized in Glossina morsitans morsitans. We generated antennae-specific transcriptomes from adult male G. m. morsitans flies fed/unfed on bloodmeal and/or exposed to an attractant (ε-nonalactone), a repellant (δ-nonalactone) or paraffin diluent. Using bioinformatics approach, we mapped raw reads onto G. m. morsitans geneset from VectorBase and collected un-mapped reads (constituting the gaps in annotation). We de novo assembled these reads (un-mapped) into transcript and identified corresponding genes of the transcripts in G. m. morsitans gene-set and protein homologs in UniProt protein database to further annotate the gaps. We predicted potential protein-coding gene regions associated with these transcripts in G. m. morsitans genome, annotated/curated these genes and identified their putative annotated orthologs/homologs in Drosophila melanogaster, Musca domestica or Anopheles gambiae genomes. We finally evaluated differential expression of the novel genes in relation to odor exposures relative to no-odor control (unfed flies). About 45.21% of the sequenced reads had no corresponding transcripts within G. m. morsitans gene-set, corresponding to the gap in existing annotation of the tsetse fly genome. The total reads assembled into 72,428 unique transcripts, most (74.43%) of which had no corresponding genes in the UniProt database. We annotated/curated 592 genes from these transcripts, among which 202 were novel while 390 were improvements of existing genes in the G. m. morsitans genome. Among the novel genes, 94 had orthologs in D. melanogaster, M. domestica or An. gambiae while 88 had homologs in UniProt. These orthologs were putatively associated with oxidative regulation, protein synthesis, transcriptional and/or translational regulation, detoxification and metal ion binding, thus providing insight into their specific roles in antennal physiological processes in male G. m. morsitans. A novel gene (GMOY014237.R1396) was differentially expressed in response to the attractant. We thus established significant gaps in G. m. morsitans genome annotation and identified novel male antennae-expressed genes in the genome, among which > 53% (108) are potentially G. m. morsitans specific.Item Anti-inflammatory norhopanes from the root bark of Fagaropsis angolensis (Engl.) H.M.Gardner(Elsevier, 2020-06-17) Nyaga, Justine M.; Mukavia, Justus; Omosa, Leonidah Kerubo; Ngnitedemb, Vaderament Nchiozem; Omoled, Ruth; Bitchagnoc, Gabin Thierry M.; Spitellere, MichaelTwo new norhopane derivatives namely 3β,6β,22-trihydroxy-7β,11α-di[(4-hydroxybenzoyl)oxy]-21αH-24- norhopa-4(23)-ene (1) and 3β,6β,22-trihydroxy-7β-[(4-hydroxybenzoyl)oxy]-21αH-24-norhopa-4(23)-ene (2) together with two previously reported compounds, including a norhopane, 3β,6β,11α-trihydroxy-7β-[(4-hydroxybenzoyl) oxy]-24-norhopa-4(23),17(21)-diene (3) and a norneohopane, (21αH)-24-norneohopa-4(23), 22(29)-diene-3β,6β,7β-triol 7-caffeate (4) were isolated from the root bark of Fagaropsis angolensis. Elucidation of their structures was achieved by spectroscopic (NMR, IR and UV) and spectrometric (HRESIMS) data and by comparison of these data with those of related compounds in the literature. Compounds 1–4 were evaluated for their anti-inflammatory activity by measuring the levels of cytokines, IL-1β, IL-2, GM-CSF and TNF-α in lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMC). All tested compounds decreased secretion of IL-1β and TNF-α. Compounds 2 and 4 caused significant decrease of the production of IL-2, GM-CSF and TNF-α compared to the reference drug, ibuprofen. These findings showed that the root barks of F. angolensis are rich source of norhopane derivatives and further provide a scientific rationale of using this plant in Kenyan folk medicine to relieve pain.Item Anti-plasmodial Activity of Some Kenyan Medicinal Plant Extracts Singly and in Combination with Chloroquine(Wiley InterScience, 2004) Muregi, F.W.; Chhabra, S.C.; Njagi, Eliud N.; Lang’at, C.; Njue, Wilson N.; Orago, A.S.; Omar, S.A.; Ndiege, I.O.Sixty organic and aqueous extracts of eleven plants used for the control of malaria by local communities in Kisii District, Kenya were screened for in vitro anti-plasmodial activity. The plants selection was based on existing ethnobotanical information and interviews with local communities. The extracts were tested against chloroquine sensitive and resistant laboratory adapted strains of Plasmodium falciparum. The study revealed that 63.6% of the plants were active (IC50 ≤ 100 μg/mL). Extracts of four plants, Ekebergia capensis, Stephania abyssinica, Ajuga remota and Clerodendrum myricoides gave IC50 values below 30 μg/mL against both chloroquine sensitive and resistant P. falciparum strains. Combination of extracts of E. capensis and C. myricoides with chloroquine against the multi-drug resistant P. falciparum isolate (V1/S) revealed synergistic effect. The plants which showed activity may be useful as sources for novel anti-plasmodial compounds.Item Antibiotic resistance of bacteria isolated from Nairobi River(2006) Budambula, Nancy; Mwachiro, E.C.; Gitonga, N.M.This study aimed to evaluate the antibiotic resistance of bacteria isolated from six sites along the pollution gradient of Nairobi River. Bacteria were isolated by standard methods and grouped into 3 categories; enteric Gram negative bacteria, non enteric Gram negative bacteria and Gram positive bacteria. They were identified using standard biochemical techniques and API Kits. The bacteria were tested against 16 antibiotics using the disc agar diffusion technique. The highest incidence of antibiotic resistance was recorded with nystatin (80.0%), followed by trimethoprim (63.3%) and cephalothin (55.8%). The enteric Gram negative bacteria recorded the highest incidence of antibiotic resistance while Gram positive bacteria showed the least antibiotic resistance. Pollution by animal and human waste contributes to the bacterial load of aquatic ecosystems. Pollution enhances the incidence of antibiotic resistance, which is of medical concern.Item Antibiotic resistance of bacteria isolated from Nairobi River.(2006) Budambula, N.L.M.; Mwachiro, E.C.; Gitonga, N.M.;This study aimed to evaluate the antibiotic resistance of bacteria isolated from six sites along the pollution gradient of Nairobi River. Bacteria were isolated by standard Methods and grouped into 3 categories; enteric Gram negative bacteria, non enteric Gram negative bacteria and Gram positive bacteria. They were identified using standard biochemical techniques and API Kits. The bacteria were tested against 16 antibiotics using the disc agar diffusion technique. The highest incidence of antibiotic resistance was recorded with nystatin (80.0%), followed by trimethoprim (63.3%) and cephalothin (55.8%). The enteric Gram negative bacteria recorded the highest incidence of antibiotic resistance while Gram positive bacteria showed the least antibiotic resistance. Pollution by animal and human waste contributes to the bacterial load of aquatic ecosystems. Pollution enhances the incidence of antibiotic resistance, which is of medical concern.Item Antimicrobial Activity of Warbugia Ugandensis against Gramnegative Multi‐Drug resistant Bacteria(Jomo Kenyatta University of Agriculture and Technology, 2014) Budambula, N. L. M.The rise in antibiotic resistance has resulted in decreasing numbers of effective antimicrobial agents available to treat infections caused by multi‐drug resistant (MDR) bacteria. This has necessitated a search for new antimicrobial agents. Herbal remedies may offer alternative treatment options especially because they elicit little or no transferable resistance if used in optimal concentrations. This study evaluated the antimicrobial properties of W. ugandensis against eight multi drug resistant (MDR) Gram‐negative bacterial isolates. The herbal extracts were obtained using methanol as an organic solvent and water as an inorganic solvent. Determination of the Minimum Inhibitory Concentrations (MICs) and the sub‐lethal concentrations of the effective extracts was done using broth inoculation method followed by colony count. The test isolates were habituated in sub‐lethal extract concentrations (SLC) for 72 h to investigate effect on their sensitivity to conventional antibiotics. Methanol extracts from the root and stem‐bark of W. ugandensis were active against the test strains and their inhibitory effect was significantly different (p<0.05) from that of other extracts. We determined that the extracts had an inhibitory rather than a lytic (cidal) mode of action. The extracts from this plant had an effective MIC of 42 μg/ml and exhibited an inhibitory mode of action and did not elicit resistance to conventional antibiotics. Methanol extracts from the root and bark of this plant may provide potential sources for further development of alternative antimicrobial agents for the treatment of MDR infections.Item Antimicrobial activity of Warbugia ugandensis against gramnegative multi‐drug resistant bacteria(Jomo Kenyatta University of Agriculture and Technology, 2014) Budambula, Nancy; Kiiru, J.; Njire, M.M.The rise in antibiotic resistance has resulted in decreasing numbers of effective antimicrobial agents available to treat infections caused by multi‐drug resistant (MDR) bacteria. This has necessitated a search for new antimicrobial agents. Herbal remedies may offer alternative treatment options especially because they elicit little or no transferable resistance if used in optimal concentrations. This study evaluated the antimicrobial properties of W. ugandensis against eight multi drug resistant (MDR) Gram‐negative bacterial isolates. The herbal extracts were obtained using methanol as an organic solvent and water as an inorganic solvent. Determination of the Minimum Inhibitory Concentrations (MICs) and the sub‐lethal concentrations of the effective extracts was done using broth inoculation method followed by colony count. The test isolates were habituated in sub‐lethal extract concentrations (SLC) for 72 h to investigate effect on their sensitivity to conventional antibiotics. Methanol extracts from the root and stem‐bark of W. ugandensis were active against the test strains and their inhibitory effect was significantly different (p<0.05) from that of other extracts. We determined that the extracts had an inhibitory rather than a lytic (cidal) mode of action. The extracts from this plant had an effective MIC of 42 μg/ml and exhibited an inhibitory mode of action and did not elicit resistance to conventional antibiotics. Methanol extracts from the root and bark of this plant may provide potential sources for further development of alternative antimicrobial agents for the treatment of MDR infections.Item Antiplamodial Activity of some Kenyan medicinal plant extracts singly and in combination with Chloroquine(2004) Muregi, F.W.; Chabbra, S.C.; Njue, Wilson N.; Njagi, Eliud N.; Langa’t, C.; Ndiege, I.O.Sixty organic and aqueous extracts of eleven plants used for the control of malaria by local communities in Kisii District, Kenya were screened for in vitro anti-plasmodial activity. The plants selection was based on existing ethnobotanical information and interviews with local communities. The extracts were tested against chloroquine sensitive and resistant laboratory adapted strains of Plasmodium falciparum. The study revealed that 63.6% of the plants were active (IC50 < or = 100 microg/mL). Extracts of four plants, Ekebergia capensis, Stephania abyssinica, Ajuga remota and Clerodendrum myricoides gave IC50 values below 30 microg/mL against both chloroquine sensitive and resistant P. falciparum strains. Combination of extracts of E. capensis and C. myricoides with chloroquine against the multi-drug resistant P. falciparum isolate (V1/S) revealed synergistic effect. The plants which showed activity may be useful as sources for novel anti-plasmodial compounds.Item Archaeal Diversity in the Haloalkaline Lake Elmenteita in Kenya(Springer-Verlag, 2009-10-06) Mwirichia, Romano K.; Cousin, Sylvie; Muigai, Ann W.; Boga, Hamadi I.; Stackebrandt, ErkoA non-culture approach was used to study the archaeal diversity in Lake Elmenteita, Kenya. Five different sampling points were selected randomly within the lake. Wet sediments and water samples were collected from each sampling point. In addition, dry mud cake was collected from three points where the lake had dried. DNA was extracted from these samples and the 16S rRNA genes were amplified using primers described to be Domain-specific for Archaea. Eleven clone libraries were constructed using PCR-amplified 16S rRNA genes. A total of 1,399 clones were picked and analysed via ARDRA. 170 ARDRA patterns were unique and the respective clones were selected for sequencing. 149 clones gave analysable sequences. BLAST analysis showed that 49 belong to the Domain Archaea while the others were either chimera or affiliated to eukaryotic taxa. Comparative sequence analysis of archaeal clones affiliated them to a wide range of genera. The order Halobacteriales was represented by members of the genera Natronococcus, Halovivax, Halobiforma, Halorubrum, and Halalkalicoccus. The highest percentage (46%) of the clones, however, belonged to uncultured members of the Domain Archaea in the order Halobacteriales. The results show that the archaeal diversity in the lake could be higher than previously reported.Item Assessment of Clofazimine and TB47 Combination Activity against Mycobacterium abscessus Using a Bioluminescent Approach(American Society for Microbiology, 2020-02) Liu, Yang; Tan, Yaoju; Islam, Mahmudul M.; Cao, Yuanyuan; Lu, Xiaoyun; Zeng, Sheng; Hameed, H. M. Adnan; Zhou, Peipei; Cai, Xingshan; Wang, Shuai; Mugweru, Julius N.; Zhang, Guoliang; Yin, Huancai; Liu, Jianxiong; Nuermberger, Eric; Zhang, TianyuMycobacterium abscessus is intrinsically resistant to most antimicrobial agents. The emerging infections caused by M. abscessus and the lack of effective treatment call for rapid attention. Here, we intended to construct a selectable marker-free autoluminescent M. abscessus strain (designated UAlMab) as a real-time reporter strain to facilitate the discovery of effective drugs and regimens for treating M. abscessus. The UAlMab strain was constructed using the dif/Xer recombinase system. In vitro and in vivo activities of several drugs, including clofazimine and TB47, a recently reported cytochrome bc1 inhibitor, were assessed using UAlMab. Furthermore, the efficacy of multiple drug combinations, including the clofazimine and TB47 combination, were tested against 20 clinical M. abscessus isolates. The UAlMab strain enabled us to evaluate drug efficacy both in vitro and in live BALB/c mice in a real-time, noninvasive fashion. Importantly, although TB47 showed marginal activity either alone or in combination with clarithromycin, amikacin, or roxithromycin, the drug markedly potentiated the activity of clofazimine, both in vitro and in vivo. This study demonstrates that the use of the UAlMab strain can significantly facilitate rapid evaluation of new drugs and regimens. The clofazimine and TB47 combination is effective against M. abscessus, and dual/triple electron transport chain (ETC) targeting can be an effective therapeutic approach for treating mycobacterial infections.Item Assessment of Four Commercial Watermelon Cultivars and one Local Landrace for Their Response to Naturally Occurring Diseases Pests and Non-Pathogenic Disorders in Sub-Humid Tropical Conditions(Asian Research Publishing Network (ARPN), 2008-09) Gichimu, Bernard M.; Owuor, B.O; Dida, M. M.Four commercial watermelon cultivars available in Kenya and one local landrace were evaluated for their susceptibility/resistance to naturally occurring diseases, pests and non-pathogenic disorders. The accessions included three most common commercial watermelon cultivars in Kenya namely ‘Sugarbaby’, ‘Crimson Sweet’ and ‘Charleston Gray’; one newly introduced cultivar from United States namely ‘Yellow Crimson’; and one local landrace (GBK-043014) from Kakamega district in Western Kenya. No inoculation was done because the study targeted naturally occurring diseases, pests and non-pathogenic disorders. Disease rating was done when the most susceptible accession(s) was severely diseased. Data collected was subjected to analysis of variance (ANOVA) using SAS version 9.1 and differences declared significant at 5% level. The SAS procedure PRINCOMP was then used to perform a principle component (PC) analysis using severity scores and accessions plotted on two dimensions using the first two principle components (PC1 and PC2). Results demonstrated significant variation among accessions in susceptibility/resistance to various diseases, pests and non-pathogenic disorders that were observed.