Biological Sciences

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Tomato Cultivation and Farmers’ Knowledge on Selected Foliar Fungal Diseases in Agro- Ecological Zones of Kirinyaga County, Kenya
(Asian Journal of Agricultural and Horticultural Research, 2022) Ogolla, F. O.; Onyango, B.; Muraya, M. M.
Diseases are hindrance to tomato production in Kirinyaga County, Kenya. However, information on farmer’s knowledge about tomato diseases to warrant pesticide usage is scanty. Further, there is information gap on disease predisposing factor such as varietal choice and seed source. This study assessed the tomato farmers’ socio characteristic, varieties grown, seed source and knowledge of selected foliar fungal disease among tomato farmers in agro-ecological zones (AEZs) of Kirinyaga County. A cross sectional survey design that in cooperated purposive sampling and snowballing approaches was adopted in the study. Data were collected from 120 tomato farmers using structured questionnaires. A chi square (Ӽ2) test was used to examine the association between different variables at α= 0.05 using SAS version 9.4. No significant association (p > 0.05) was observed between gender of farmers and AEZ. Nonetheless, there were more men (83.33%) than women (16.67%). Terminator F1 variety was popular among farmers (25%). No significance (p > 0.05) association was observed between source of tomato planting material and AEZs. However, Agrovet was a popular seed source among farmers (40%). The reasons for choosing a particular tomato variety was significantly (p < 0.05) associated with the AEZ with 40.83% of farmers preferring tomato varieties with good marketability traits such as fruit size. Farmers’ knowledge of causative agent of early blight, late blight and Septoria leaf spot was significantly (p < 0.05) associated with AEZs. The source of farmer’s knowledge on tomato foliar fungal diseases was not significantly (p > 0.05) associated with AEZ. However, farming experiences was a popular source of knowledge (51.67%) among farmers. Inability of some farmers to identify tomato diseases negates the efforts on disease management in tomato production in Kirinyaga County. Therefore, measures such as coordinated education on tomato diseases is necessary to empower farmers on disease causes and identification to enhance disease management and improve tomato yields in Kirinyaga County in Kenya.
Pupal productivity of larval habitats of Aedes aegypti in Msambweni, Kwale County, Kenya
(Parasitology Research, 2023-01-23) Alawih S. Mwakutwaa1 · Harun N. Ngugi2 · Bryson A. Ndenga3 · Amy Krystosik4 · Moses Ngari5 · Laila U. Abubakar6 · Shadrack Yonge1 · Uriel Kitron7 · A. Desiree LaBeaud4 · Francis M. Mutuku
Aedes aegypti is an important vector of several arboviruses including dengue and chikungunya viruses. Accurate identifcation of larval habitats of Ae. aegypti is considered an essential step in targeted control. This study determined Ae. aegypti productivity in selected larval habitats in Msambweni, Kwale County, Kenya. Three sequential larval habitat surveys were conducted. The frst survey was habitat census (baseline) through which 83 representative larval habitats were identifed and selected. The second and third surveys involved estimating daily productivity of the 83 selected larval habitats for 30 consecutive days during a wet and a dry season, respectively. Of 664 larval habitats examined at baseline, 144 larval habitats (21.7%) were found to be infested with Ae. aegypti larvae. At baseline, majority (71%) of the pupae were collected from two (2/6) larval habitat types, tires and pots. Multivariate analysis identifed habitat type and the habitat being movable as the predictors for pupal abundance. During the 30-day daily pupal production surveys, only a few of the habitats harbored pupae persistently. Pupae were found in 28% and 12% of the larval habitats during the wet and dry seasons, respectively. In the wet season, drums, tires, and pots were identifed as the key habitat types accounting for 85% of all pupae sampled. Three habitats (all drums) accounted for 80% of all the pupae collected in the dry season. Predictors for pupal productivity in the wet season were habitat type, place (whether the habitat is located at the back or front of the house), habitat purpose (use of the water in the habitat), and source of water. Although the multivariate model for habitat type did not converge, habitat type and habitat size were the only signifcant predictors during the dry season. Drums, pots, and tires were sources of more than 85% of Ae. aegypti pupae, reinforcing the “key container concept.” Targeting these three types of habitats makes epidemiological sense, especially during the dry season.
The Influence of Communication Messages on Adoption of Contagious Bovine Pleuropneumonia (CBPP) Vaccine among Arid and Semi-Arid Lands (ASAL) Pastoralists in Keny
(International journal of communication and public relation, 2023-04-18) Virginia Wangari Ndungu, Professor Hellen K. Mberia, Dr Kyalo Wa Ngula and Dr Joseph Othieno
Purpose: The purpose was to establish influence of communication messages on adoption of Contagious Bovine Pleuropneumonia (CBPP) Vaccine among Arid and Semi-Arid Lands (ASAL) pastoralists in Kenya. Messages were studied under parameters of inoculation site, benefits, required frequency of vaccination and side effects. The focus on the vaccine messaging was informed by the slow pace of adoption of live T1 vaccines currently being used to eradicate CBPP in Kenya. Diffusion of innovation and social learning theories were used to support the study. Methodology: Study population were pastoralists in Narok South Sub County. 468 respondents inclusive of qualitative and quantitative samples where 440 responded to questionnaire, 24 in focus group discussions, and 4 in key informant interviews participated. Multi stage, purposive, simple random, systematic and stratified sampling techniques were then employed to come up with respondents. Statistical Package for Social Scientists (SPSS) version 20.0 was used to analyze data, which was presented using regression coefficients and ANOVA. Findings: CBPP messaging influenced respondents to vaccinate although some had more influence than others. Messages on inoculation site, benefits, required frequency of vaccination side effects and communal vaccinations were important for the survival of their cattle and significantly influenced the decisions of respondents to vaccinate against the disease. Moreover, messages helped them to know important information details such as vaccination venues, and costs of vaccination and availability of the veterinary officers. CBPP vaccine messages attributes were key in the success of influencing respondents. However, the messaging ran into already held misinformation by some pastoralists confirming earlier study that vaccination rate was at 20-60% because some skipped the exercise. Unique Contribution to Theory, Practice and Policy: CBPP vaccine messages and attributes significantly influenced CBPP vaccinations decisions among pastoralists. This study validated diffusion of innovation and social learning theories that innovation-decision process is essentially an information seeking and processing activity in which an individual is motivated to reduce uncertainty about the advantages and disadvantages of the innovation. For policy and practice, this study recommends development of communication plans, and packaging of CBPP vaccine messages for dissemination in the ASALs where disease is prevalent. Considering that CBPP is a trans-boundary disease, these plans and messages could be harmonized across ASAL counties to enable consistency and coherence
Development of High-Throughput Sample Preparation Procedures for the Quantitative Determination of Aflatoxins in Biological Matrices of Chickens and Cattle Using UHPLC-MS/MS
(Toxins, 2023-01-03) Siegrid De Baere 1,* , Phillis E. Ochieng 1,2 , David C. Kemboi 1,3,4, Marie-Louise Scippo 2 , Sheila Okoth 5 , Johanna F. Lindahl 6,7,8 , James K. Gathumbi 3 , Gunther Antonissen 1,9 and Siska Croubels 1
: Aflatoxins (AFs) frequently contaminate food and animal feeds, especially in (sub) tropical countries. If animals consume contaminated feeds, AFs (mainly aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), G2 (AFG2) and their major metabolites aflatoxin M1 (AFM1) and M2 (AFM2)) can be transferred to edible tissues and products, such as eggs, liver and muscle tissue and milk, which ultimately can reach the human food chain. Currently, the European Union has established a maximum level for AFM1 in milk (0.05 µg kg−1 ). Dietary adsorbents, such as bentonite clay, have been used to reduce AFs exposure in animal husbandry and carry over to edible tissues and products. To investigate the efficacy of adding bentonite clay to animal diets in reducing the concentration of AFB1, AFB2, AFG1, AFG2, and the metabolites AFM1 and AFM2 in animal-derived foods (chicken muscle and liver, eggs, and cattle milk), chicken and cattle plasma and cattle ruminal fluid, a sensitive and selective ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method has been developed. High-throughput sample preparation procedures were optimized, allowing the analysis of 96 samples per analytical batch and consisted of a liquid extraction using 1% formic acid in acetonitrile, followed by a further clean-up using QuEChERS (muscle tissue), QuEChERS in combination with Oasis® Ostro (liver tissue), Oasis® Ostro (egg, plasma), and Oasis® PRiME HLB (milk, ruminal fluid). The different procedures were validated in accordance with European guidelines. As a proof-of-concept, the final methods were used to successfully determine AFs concentrations in chicken and cattle samples collected during feeding trials for efficacy and safety evaluation of mycotoxin detoxifiers to protect against AFs as well as their carry-over to animal products.
A Machine Learning-Based Prediction of Malaria Occurrence in Kenya
(American Journal of Theoretical and Applied Statistics, 2024-08-20) Dennis Muriithi* , Victor Wandera Lumumba , Mark Okongo
For many years’ malaria has been a health public concern in Kenya as well as many parts of Africa and other parts of the world. The purpose of this study is to develop and evaluate a supervised machine learning model to predict malaria occurrence (final malaria test results) in Kenya. The study investigated twelve predictor variables on the outcome variable (malaria test results), where five machine learning models namely; k-nearest neighbors, support vector machines, random forest, tree bagging, and boosting, were estimated. During the model evaluation, random forest emerged as the best overall model in the classification and prediction of final malaria test results. The model attained a higher classification accuracy of 97.33%, sensitivity of 71.1%, specificity of 98.4%, balanced accuracy of 84.7% and an area under the curve of 98.3%. From the final model, the presence of plasmodium falciparum emerged most important feature, followed by region, endemic zone and anemic level. The feature with the least importance in predicting final malaria test results was having mosquito nets. In conclusion, employing Machine learning algorithms enhances early detection, optimizing resource allocation for interventions, and ultimately reducing the incidence and impact of malaria in the Kenya. The study recommends allocation of resources and funds to areas with the presence of plasmodium falciparum, region susceptible to malaria, endemic zones and anemic prone areas.
A Machine Learning-Based Prediction of Malaria Occurrence in Kenya
(American Journal of Theoretical and Applied Statistics, 2024-08-20) Dennis Muriithi* , Victor Wandera Lumumba , Mark Okongo
The purpose of this study is to develop and evaluate a supervised machine learning model to predict malaria occurrence (final malaria test results) in Kenya. The study investigated twelve predictor variables on the outcome variable (malaria test results), where five machine learning models namely; k-nearest neighbors, support vector machines, random forest, tree bagging, and boosting, were estimated. During the model evaluation, random forest emerged as the best overall model in the classification and prediction of final malaria test results. The model attained a higher classification accuracy of 97.33%, sensitivity of 71.1%, specificity of 98.4%, balanced accuracy of 84.7% and an area under the curve of 98.3%. From the final model, the presence of plasmodium falciparum emerged most important feature, followed by region, endemic zone and anemic level. The feature with theleast importance in predicting final malaria test results was having mosquito nets. In conclusion, employing Machine learning algorithms enhances early detection, optimizing resource allocation for interventions, and ultimately reducing the incidence and impact of malaria in the Kenya. The study recommends allocation of resources and funds to areas with the presence of plasmodium falciparum, region susceptible to malaria, endemic zones and anemic prone areas.
Screening of Antimicrobial Activity of Poly Herbal Extracts against Bacterial Pathogens Causing Gastroenteritis in Tharaka Nithi County, Kenya
(South Asian Journal of Research in Microbiology, 2023-04-27) Mbithe P. Kiteme a* , Benson O. Onyango b , Eric C. Njagi c and Fredrick O. Ogolla
Herbals have been used for decades to treat gastrointestinal infections across the world, including in Tharaka-Nithi County, Kenya. Crude extracts from herbs have long been prescribed by traditional healers for treatment of typhoid, cholera, and shigellosis. However, the effectiveness of extracts obtained using different extraction solvents such as methanol, acetone, and hexane have not fully been evaluated. This study aimed at evaluating the effect of solvents (Ethanol, hexane, and methanol) on the yield of crude extract from plants (Erythrinna abyssinica, Aspilia pluriseta, Vangueria infausta, Ficus sycomorus, and Carissa edulis), assessing the effect of the solvents on extracted active metabolites, and determining the effect of these solvents on extract’s against Vibrio cholerae, Shigella flexneri, and Salmonella typhimuriumi and, Escherichia coli that served as a model organism for screening plant extracts against Gram-negative bacteria. Crude extracts were obtained by soaking dried ground plant parts in individual solvents, which were then concentrated by a rotary evaporator. The phytochemical screening to detect plant metabolites was done qualitatively. Bioassays to analyze the efficacy of the plant crude extracts against the microbes were carried out in 4×3×3×5 factorial experiment laid out in a completely randomized design. The determination of bioactivity of herbal extracts was carried out using minimal inhibition concentration and minimum bactericidal concentration methods. Data obtained on the bioactivity assay (Count of the bacteria colony forming units) was analyzed using the Kruskal-Wallis test at α = 0.05, and medians were compared by the Wilcoxon rank sum test in Scientific Analysis System version 9.4. Methanol solvent produced higher quantities of crude extracts for all the herbal samples used with, Vangueria infausta producing the highest extract (5.06g). Most phytochemicals were present in Methanolic extracts compared to hexane and acetone extracts. There was a significant (p < 0.05) difference in the bioactivity of different herbal plants against bacterial pathogens at different concentrations of crude extract. The efficacy of plant extract increased progressively from 100ppm to 1000ppm concentration. Methanol is recommended for use in the extraction of f medicinal plant extracts as it leads to improved potency as compared to hexane and acetone.
Analyzing the Risks in Highway Projects Using the Markov Chain Approach
(sciepub, 2018-12-05) DM,Obare,M M,Muraya
Theissuesassociatedtohighwayprojectsusuallyaffectaspectslikenatureoftheproject,costandtime. Riskeventsthatarenotusualalwaysgiverisetopositiveornegativefeedbackandnormallycausevariationsfrom project designs especially inclined to risk construction projects. However, more investigations have been done on riskmanagementassociatedtohighwayprojects,thereislimitedliteraturemoresototheriskoftheproject.These projectscanbeoverseenundersomedubiousconditionbyapplyingtheriskmanagementtechnique.Theaimofthis research was to demonstrate pertinence of the Markov Chain approaches in diminishing the risks of the highway projectsbyutilizationofdatafromtheprojects.OtherCommonlyutilizedproceduresdon'tinvestigatepotentialrisks successfully and subsequently the utilization of Markov chains. This project has made utilization of the Markov chainproceduretoevaluatetheshortandlong-termpotentialrisks.Thisresearchprojectutilizedriskdataacquired fromexpertsthroughquestionnaires.ThedatawasthenanalyzedutilizingtheOctavesoftware.
Pupal productivity of larval habitats of Aedes aegypti in Msambweni, Kwale County, Kenya
(Parasitology Research, 2023-01-23) Mwakutwaa, Alawih S.; Ngugi, Harun N.; Ndenga, Bryson A.; Krystosik, Amy; Ngari, Moses; Abubakar, Laila U.; Yonge, Shadrack; Kitron, Uriel; LaBeaud, A. Desiree; Mutuku, Francis M.
Aedes aegypti is an important vector of several arboviruses including dengue and chikungunya viruses. Accurate identification of larval habitats of Ae. aegypti is considered an essential step in targeted control. This study determined Ae. aegypti productivity in selected larval habitats in Msambweni, Kwale County, Kenya. Three sequential larval habitat surveys were conducted. The first survey was habitat census (baseline) through which 83 representative larval habitats were identified and selected. The second and third surveys involved estimating daily productivity of the 83 selected larval habitats for 30 consecutive days during a wet and a dry season, respectively. Of 664 larval habitats examined at baseline, 144 larval habitats (21.7%) were found to be infested with Ae. aegypti larvae. At baseline, majority (71%) of the pupae were collected from two (2/6) larval habitat types, tires and pots. Multivariate analysis identified habitat type and the habitat being movable as the predictors for pupal abundance. During the 30-day daily pupal production surveys, only a few of the habitats harbored pupae persistently. Pupae were found in 28% and 12% of the larval habitats during the wet and dry seasons, respectively. In the wet season, drums, tires, and pots were identified as the key habitat types accounting for 85% of all pupae sampled. Three habitats (all drums) accounted for 80% of all the pupae collected in the dry season. Predictors for pupal productivity in the wet season were habitat type, place (whether the habitat is located at the back or front of the house), habitat purpose (use of the water in the habitat), and source of water. Although the multivariate model for habitat type did not converge, habitat type and habitat size were the only significant predictors during the dry season. Drums, pots, and tires were sources of more than 85% of Ae. aegypti pupae, reinforcing the “key container concept.” Targeting these three types of habitats makes epidemiological sense, especially during the dry season
Transcriptomic and Physiological Analyses Reveal Potential Genes Involved in Photoperiod-Regulated β-Carotene Accumulation Mechanisms in the Endocarp of Cucumber (Cucumis sativus L.) Fruit
(MDPI, 2022-10-21) Obel, Hesbon Ochieng; Cheng, Chunyan; Tian, Zhen; Njogu, Martin Kagiki; Li, Ji; Du, Shengli; Lou, Qunfeng; Zhou, Junguo; Yu, Xiaqing; Ogweno, Joshua Otieno; Chen, Jinfeng
The accumulation of carotenoids in plants is a key nutritional quality in many horticultural crops. Although the structural genes encoding the biosynthetic enzymes are well-characterized, little is known regarding photoperiod-mediated carotenoid accumulation in the fruits of some horticultural crops. Herein, we performed physiological and transcriptomic analyses using two cucumber genotypes, SWCC8 (XIS-orange-fleshed and photoperiod-sensitive) and CC3 (white-fleshed and photoperiod-non-sensitive), established under two photoperiod conditions (8L/16D vs. 12L/12D) at four fruit developmental stages. Day-neutral treatments significantly increased fruit β-carotene content by 42.1% compared to short day (SD) treatments in SWCC8 at 40 DAP with no significant changes in CC3. Day-neutral condition elevated sugar levels of fruits compared to short-day treatments. According to GO and KEGG analyses, the predominantly expressed genes were related to photosynthesis, carotenoid biosynthesis, plant hormone signaling, circadian rhythms, and carbohydrates. Consistent with β-carotene accumulation in SWCC8, the day-neutral condition elevated the expression of key carotenoid biosynthesis genes such as PSY1, PDS, ZDS1, LYCB, and CHYB1 during later stages between 30 to 40 days of fruit development. Compared to SWCC8, CC3 showed an expression of DEGs related to carotenoid cleavage and oxidative stresses, signifying reduced β-carotene levels in CC3 cucumber. Further, a WGCNA analysis revealed co-expression between carbohydrate-related genes (pentose-phosphatase synthase, β-glucosidase, and trehalose-6-phosphatase), photoperiod-signaling genes (LHY, APRR7/5, FKF1, PIF3, COP1, GIGANTEA, and CK2) and carotenoid-biosynthetic genes, thus suggesting that a cross-talk mechanism between carbohydrates and light-related genes induces β-carotene accumulation. The results highlighted herein provide a framework for future gene functional analyses and molecular breeding towards enhanced carotenoid accumulation in edible plant organs.
Characteristics of Aedes aegypti adult mosquitoes in rural and urban areas of western and coastal Kenya
(PLOS ONE, 2017-12-19) Ndenga, Bryson Alberto; Mutuku, Francis Maluki; Ngugi, Harun Njenga; Omari, Mbakaya Joel; Aswani, Peter; Musunzaji, Peter Siema; Vulule, John; Mukoko, Dunstan; Kitron, Uriel; LaBeaud,Angelle Desiree
Aedes aegypti is the main vector for yellow fever, dengue, chikungunya and Zika viruses.Recent outbreaks of dengue and chikungunya have been reported in Kenya. Presence and abundance of this vector is associated with the risk for the occurrence and transmission of these diseases. This study aimed to characterize the presence and abundance of Ae. aegypti adult mosquitoes from rural and urban sites in western and coastal regions of Kenya. Presence and abundance of Ae. aegypti adult mosquitoes were determined indoors and outdoors in two western (urban Kisumu and rural Chulaimbo) and two coastal (urban Ukunda and rural Msambweni) sites in Kenya. Sampling was performed using quarterly human landing catches, monthly Prokopack automated aspirators and monthly Biogents-sentinel traps. A total of 2,229 adult Ae. aegypti mosquitoes were collected: 785 (35.2%) by human landing catches, 459 (20.6%) by Prokopack aspiration and 985 (44.2%) by Biogents-sentinel traps. About three times as many Ae. aegypti mosquitoes were collected in urban than rural sites (1,650 versus 579). Comparable numbers were collected in western (1,196) and coastal (1,033) sites. Over 80% were collected outdoors through human landing catches and Prokopack aspiration. The probability of collecting Ae. aegypti mosquitoes by human landing catches was significantly higher in the afternoon than morning hours (P<0.001), outdoors than indoors (P<0.001) and in urban than rural sites (P = 0.008). Significantly more Ae. aegypti mosquitoes were collected using Prokopack aspiration outdoors than indoors (P<0.001) and in urban than rural areas (P<0.001). Significantly more mosquitoes were collected using Biogents-sentinel traps in urban than rural areas (P = 0.008) and in western than coastal sites (P = 0.006). The probability of exposure to Ae. aegypti bites was highest in urban areas, outdoors and in the afternoon hours. These characteristics have major implications for the possible transmission of arboviral diseases and for the planning of surveillance and control programs.
Status of Opuntia invasions in the arid and semi-arid lands of Kenya
(CAB International 2018, 2018-03-21) Githae, Eunice W.
Invasive alien species (IAS) are among the leading threats to biodiversity, food security and human well-being. Opuntia (prickly pear cactus) is one of the most widespread and naturalized in the arid and semi-arid areas of Kenya, with extreme effects on rural livelihoods and the environment. However, comprehensive information on the status of invasion in the country is lacking, which is crucial for developing strategies for prevention and management. This paper, therefore, provides an overview of the interacting factors that influence its invasion in Kenya in terms of species diversity, pathways of introduction, negative impacts and the effectiveness of regulations and control measures. Seven invasive species of Opuntia are present in the country with the most abundant (O. stricta) being under biocontrol trial. These species have the same habitat preferences, physiological traits, negative impacts, introduction pathways and management options. Invasion is mainly attributed to changes in land use and consequent land degradation. Introduction pathways are largely intentional for ornamental purposes but unintentional at a local scale through escape from gardens and natural dispersal. The most applied methods of managing Opuntia are mechanical and chemical methods that are unsustainable and labour-intensive at large scale. Effective policies are therefore needed to prevent an increase in the significant negative impacts caused by IAS including those that have a limited distribution.
Socio-ecological impacts of invasive alien cactus (opuntia) in the rangelands of Narok county, Kenya
(Journal of Research in Forestry, Wildlife & Environment, 2017-12) Githae, E.W.; Magana, A. M.
Many cactus species have been introduced in the Kenyan rangelands and their subsequent spread have had devastating effects on the ecosystem services. Opuntia stricta is the most widespread and forms dense impenetrable thickets that negatively impact on rangeland livelihoods and resources. This study assessed the impact of O. stricta on rural livelihoods and their environment in Narok County. Data was collected using household surveys, key informant interviews and transect-walks. Results indicate that communities in the region are well aware of Opuntia invasion in the area, which has increased rapidly over the recent past and spreading to various ecosystems. The cause of spread was attributed to planting the species for various purposes, garden throw-outs and floods. More than 70% of the respondents perceived the species as undesirable with negative impacts only. The impacts include denied access to natural resources, reduced productivity and increased threat to livestock and human health. Pasture lands, farmlands and degraded lands were the most invaded areas. Chopping was the preferred method of management but was combined with other mechanical and chemical methods in order to be more effective. Appropriate interventions are suggested to mitigate the negative impacts and improve rural livelihoods and their environment.
Genome-Wide Identification of GASA Gene Family in Ten Cucurbitaceae Species and Expression Analysis in Cucumber
(MDPI, 2022-08-22) Zhang, Kaijing; Hu, Yuchao; Yang, Dekun; Yan, Congsheng; Li, Nanyang; Li, Ziang; Njogu, Martin Kagiki; Wang, Xing; Jia, Li
Gibberellic acid-stimulated in Arabidopsis (GASA), a unique small molecular protein of plants, plays an essential role in plant growth and development. The GASA family genes have been identified and studied in many plants. However, the identification of GASA gene family in Cucurbitaceae species has not been reported yet. Therefore, in this study, based on the available genome information on the Cucurbitaceae species, the GASA family genes in 10 Cucurbitaceae species including cucumber (Cucumis sativus), watermelon (Citrullus lanatus), melon (Cucumis melo), pumpkin (Cucurbita moschata), wax gourd (Benincasa hispida), sponge gourd (Luffa cylindrica), bottle gourd (Lagenaria siceraria), bitter gourd (Momordica charantia), chayote (Sechium edule), and snake gourd (Trichosanthes anguina) were identified with bioinformatics methods. To understand the molecular functions of GASA genes, the expression pattern analysis of cucumber GASA family genes in different tissues and stress responses were also analyzed. The results showed that a total of 114 GASA genes were identified in the 10 Cucurbitaceae species, which were divided into three subfamilies. Synteny analysis of GASA genes among cucumber, Arabidopsis and rice showed that nine cucumber GASA genes were colinear with 12 Arabidopsis GASA genes, and six cucumber GASA genes were colinear with six rice GASA genes. The cis-acting elements analysis implied that the cucumber GASA genes contained many cis-elements associated with stress and hormone response. Tissue-specific expression analysis of cucumber GASA family genes revealed that only the CsaV3_2G029490 gene was lowly or not expressed in all tissues, the CsaV3_3G041480 gene was highly expressed in all tissues, and the other seven GASA genes showed tissue-specific expression patterns. Furthermore, nine cucumber GASA family genes exhibited different degrees of regulatory response under GA, abiotic and biotic stresses. Two cucumber GASA genes, CsaV3_3G042060 and CsaV3_3G041480, were differentially expressed under multiple biotic and abiotic stresses, which indicated that these two GASA genes play important roles in the growth and development of cucumber.
Medicinal Plants Used for Treatment of Gastrointestinal Infections in Tharaka-Nithi County
(International Journal of Pathogen Research, 2022-08-22) Kiteme M., Purity; Onyango O., Benson; Njagi C., Eric; Ogolla O., Fredrick
Health care is a basic need to humans which can only be achieved with medicines with high efficacy against disease causing pathogens. Globally, gastrointestinal infections are major health concern particularly to travelers since over 60% visiting tropical and subtropical regions develop diarrhea. Herbal plants have been used for decades to treat gastrointestinal infections globally including Tharaka-Nithi County in Kenya. However, there is little information on the demography of herbalist and the plants used in treatment of gastrointestinal infections such as typhoid, cholera and shigellosis. A cross sectional survey was carried out involving thirty herbalists to assess their demographic data and to establish herbs commonly used to treat typhoid, cholera and shigellosis in Tharaka-Nithi County. Data collected was subjected to Chi square test of association and descriptive statistics and presented in percentages. There were more male herbalists (65.52%) in the study than female herbalist (34.48%). Most of the herbalist (65.52%) were aged above 70 years. There was a significant (p < 0.05) association between herbalists’ level of education and age (X 2 (6, N = 30) = 17.349, p = 0.008). Most herbalists were found to have below primary education level 58.62%. Aloe vera, Aspilia pluriseta, Ficus sycomorus and Physalis peruviana were identified as commonly used plants for treatment of cholera with Aspilia pluriseta being most preferred (27%) by herbalist above the age of 70 years. Vangueria infausta, Eucalyptus globulus, Carissa edulis and Erythrina abysinnica were commonly used for treatment of shigellosis with Eucalyptus globulus being most preferred (58.6%) by herbalist above the age of 70 years. Erythrina abysinnica, Carissa edulis, Vangueria infausta and Eucalyptus globulus were commonly used for treatment of typhoid while 50.0% of herbalist above the age of 70 preferred Erythrina abysinnica. Most of the herbalists had below primary education level. In conclusion, herbal medicine is mostly dispensed by older people in Tharaka-Nithi County in Kenya. Different herbal plants are used in the treatment of cholera, shigellosis and typhoid.
Screening of Antimicrobial Activity of Poly Herbal Extracts against Bacterial Pathogens Causing Gastroenteritis in Tharaka Nithi County, Kenya
(South Asian Journal of Research in Microbiology, 2023-04-27) Mbithe P. Kiteme; Benson O. Onyango; Eric C. Njagi; Fredrick O. Ogolla
Herbals have been used for decades to treat gastrointestinal infections across the world, including in Tharaka-Nithi County, Kenya. Crude extracts from herbs have long been prescribed by traditional healers for treatment of typhoid, cholera, and shigellosis. However, the effectiveness of extracts obtained using different extraction solvents such as methanol, acetone, and hexane have not fully been evaluated. This study aimed at evaluating the effect of solvents (Ethanol, hexane, and methanol) on the yield of crude extract from plants (Erythrinna abyssinica, Aspilia pluriseta, Vangueria infausta, Ficus sycomorus, and Carissa edulis), assessing the effect of the solvents on extracted active metabolites, and determining the effect of these solvents on extract’s bioactivity against Vibrio cholerae, Shigella flexneri, and Salmonella typhimuriumi and, Escherichia coli that served as a model organism for screening plant extracts against Gram-negative bacteria. Crude extracts were obtained by soaking dried ground plant parts in individual solvents, which were then concentrated by a rotary evaporator. The phytochemical screening to detect plant metabolites was done qualitatively. Bioassays to analyze the efficacy of the plant crude extracts against the microbes were carried out in 4×3×3×5 factorial experiment laid out in a completely randomized design. The determination of bioactivity of herbal extracts was carried out using minimal inhibition concentration and minimum bactericidal concentration methods. Data obtained on the bioactivity assay (Count of the bacteria colony forming units) was analyzed using the Kruskal-Wallis test at α = 0.05, and medians were compared by the Wilcoxon rank sum test in Scientific Analysis System version 9.4. Methanol solvent produced higher quantities of crude extracts for all the herbal samples used with, Vangueria infausta producing the highest extract (5.06g). Most phytochemicals were present in Methanolic extracts compared to hexane and acetone extracts. There was a significant (p < 0.05) difference in the bioactivity of different herbal plants against bacterial pathogens at different concentrations of crude extract. The efficacy of plant extract increased progressively from 100ppm to 1000ppm concentration. Methanol is recommended for use in the extraction of medicinal plant extracts as it leads to improved potency as compared to hexane and acetone.
Effect of pH, Carbon and Nitrogen Sources on Antibiotic Production by Actinomycetes Isolates from River Tana and Lake Elementaita, Kenya
(Asian Journal of Research in Biochemistry, 2023-08-04) O. Shikuku, Bonface; Kiruki, Silas; Kuria, Eric; Mayo, Domnic; O. Ogolla, Fredrick
The escalating concern over antibiotic resistance and its profound impact on public health have underscored the urgent need to explore alternative reservoirs of antimicrobial agents. In this regard, Actinomycetes have emerged as a compelling area of investigation due to their remarkable capacity to produce bioactive compounds. Therefore, this study sought to investigate the influence of pH and various carbon and nitrogen sources on the antibacterial activity of Actinomycetes isolates collected from Lake Elementaita and River Tana. By examining the effects of these factors, we aimed to gain insights into the optimization of growth conditions and nutrient availability to enhance the production of bioactive compounds with potent antibacterial properties. The Actinomycetes isolates used in this study were from Lake Elementaita and River Tana, known for their diverse ecological characteristics and potential as sources of bioactive compounds. The isolates were subjected to morphological, biochemical, and molecular techniques to ensure accurate identification. To assess the antibacterial activity of the Actinomycetes isolates, they were tested against E. coli using the agar well diffusion method. The independent variables examined in this study were pH levels (4, 7, and 9) as well as different carbon sources (fructose and sucrose) and nitrogen sources (urea and sodium nitrate). The diameter of the inhibition zones served as the dependent variable. The data collected on the effects of pH and nutrients on the inhibition zones of Actinomycetes isolates were subjected to statistical analysis. One-way ANOVA was performed to assess significant differences in antibacterial activity among the isolates under different carbon and nitrogen preference. Mean values were compared using the LSD test at a significance level (α) of 0.05. Furthermore, the Kruskal-Wallis test was utilized to analyze the pH preferences of the Actinomycetes isolates at a significance level (α) of 0.05. The results showed that pH significantly influenced the bioactivity of the Actinomycetes isolates, with pH 7 exhibiting the highest inhibition zones against E. coli. The isolates displayed varied antibacterial activities depending on the carbon and nitrogen sources provided. Sucrose was the most preferred carbon source, followed by fructose, while urea was the preferred nitrogen source, followed by sodium nitrate. The study concluded that pH and nutrient availability play crucial roles in determining the antibacterial activity of Actinomycetes isolates. Other than contributing to our in-depth understanding of the factors influencing the antimicrobial potential of Actinomycetes, the results of this study highlight the importance of optimizing growth conditions and nutrient availability to enhance the production of bioactive compounds with potent antibacterial properties. Further investigations and exploration of Actinomycetes from diverse environments are recommended to discover new bioactive molecules for combating antibiotic resistance.
Characterization of Antibioticproducing Actinomycetes Isolated from River Tana and Lake Elementaita in Kenya
(Asian Journal of Research in Biochemistry, 2023-08-01) O. Shikuku, Bonface; Kiruki, Silas; Kuria, Eric; Mutembei, Martin; O. Ogolla, Fredrick
The rise of antibiotic-resistant bacteria has become a global health concern, necessitating the search for novel sources of antibiotics. Actinomycetes, a group of microorganisms, have been known for their ability to produce bioactive compounds with antimicrobial properties. This study aimed to isolate, identify, and characterize antibiotic-producing Actinomycetes from River Tana and Lake Elementaita. Samples were collected from the study sites, and Actinomycetes were isolated using serial dilution and spread plate techniques. The isolates were characterized based on their morphological and biochemical properties. Furthermore, their antibacterial activity against Escherichia coli, Staphylococcus aureus, and Salmonella typhi was evaluated using the agar well diffusion method. The zones of inhibition were measured (mm), and analysis was done to compare the activity of the isolates using Kruskal Wallis test and medians compared using Wilcoxon with Bonferroni correction at alpha = 0.05 in SAS version 9.4. Analysis of DNA sequences was done using the BLAST program and a phylogenetic tree was constructed using MEGA X version 11. Biochemical tests revealed positive results for catalase, indole, oxidase, and citrate utilization, while coagulase and methyl red tests were negative. In terms of antibacterial activity, 54.5% of the isolates showed activity against E. coli, 45.5% against S. aureus, and 45.5% against S. typhi. Isolate LEL2201 had significant (p < 0.05) higher zone of inhibition against S. aureus (inhibition zone of 25.0mm), while isolate RT2201 exhibited the highest activity against E. coli and S. typhi (inhibition zone of 8.5 mm and 8.6 mm, respectively). Molecular characterization through 16S rRNA gene sequencing identified the isolates as belonging to the Actinobacterium order. Phylogenetic analysis revealed their similarity to known Actinomycetes species including Actinomycetales bacterium, Streptomyces intermedius and Streptomyces flavomacrosporus from various countries. The findings of this study demonstrate the presence of antibiotic-producing Actinomycetes in River Tana and Lake Elementaita. Thus, further investigations are warranted to identify and characterize the specific antibacterial compounds produced by these isolates.
Molecular characterization of wood ear mushrooms [Auricularia sp.] from Kakamega Forest in Western Kenya
(Current Research in Environmental & Applied Mycology, 2016-03-30) B.O., Onyango; C. M., Mbaluto; C. S., Mutuku; D. O., Otieno
Mushrooms of the genus Auricularia, generally termed wood ear mushrooms are in high demand in Western Kenya due to their numerous medicinal and nutritional properties. Interventions to characterize and conserve the native wood ear mushrooms are necessary to mitigate possible extinction of this valuable bio-resource. Currently, the species richness and bio-geographical relatedness of the Kenyan native wood ears is not fully elucidated. This study used molecular sequence analysis of the internal transcribed spacer (ITS) and the 28S nuclear ribosomal large subunit (nLSU) genes in species delimitation of six strains of wood ear mushrooms native to Kakamega Forest. Phylogeny of both the ITS and nLSU gene regions showed that three strains clustered with Auricularia delicata while the other three strains clustered with Auricularia polytricha at bootstrap support values of above 97%. An intragenomic dichotomy appeared to occur in the Auricularia delicata strains based on the genetic distance of the nLSU gene sequences. The wood ear mushrooms identified from the Kakamega Forest strains were Auricularia delicata and Auricularia polytricha and not Auricularia auricula as previously reported. This rich biodiversity needs further exploration to widen the nutritional and medicinal base of the rural populace who depend on the mushrooms through conservation, cultivation and commercialization activities.
Status of Plasmodium Falciparum Resistance to Sulfadoxine Pyrimethamine in Kwale County, Kenya
(Epidemiology International, 2019-12) Kendi Mutwiri, Winfred; Gicheru, Michael; Kasili, Sichangi; T. Kimani, Francis; Makokha, Francis
Background: Malaria persists to be one of the major significant diseases in the world. A range of antimalarial drugs are readily accessible but management of the disease remains a problem. Despite the broadened spread of resistance to Sulfadoxine Pyrimethamine (SP), it still remains the suggested drug to treat and prevent malaria in expecting women and children below five years. This study sought to assess the current trend of SP resistance markers a decade after it was withdrawn as the first-line anti-malarial in Msambweni, Kwale County, Kenya. Materials and Methods: Smear-positive samples (N=134) collected from June 2013 cross-sectional study amid infants visiting Msambweni District Hospital were evaluated for mutations in dhfr and dhps genes. Extraction of DNA was done using Chelex method followed by PCR amplification of dhfr and dhps genes. Specific enzymes were used to cleave the successfully amplified DNA to establish the samples as either mutated or wild type. Results: Pfdhps/pfdhfr A437G/K540E/N51I/C59R/S108N quintuple mutant linked with SP-resistance did not change significantly (p=0.967). Conclusion: This survey proves fixation of key mutations in the Pfdhfr and Pfdhps genes conferring resistance to SP. Further research involving more samples and endemic sites need to be conducted to endow the stakeholders with information on the emergence and increase of SP resistance.

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