Biological Sciences

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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.
Action and variation potential electrical signals in higher plants
(African Journal of Biological Sciences, 2021) Ndung’u, Ruth Wairimu; Kamweru, Paul Kuria; Kirwa, Abraham Tuwei
This review evaluates the types of electrical signals (ESs) in plants, generation and propagation of various ESs, their ways of transmission within the plant body and their corresponding physiological significance. It also outlines abiotic factors, e.g., light, temperature, water content as stimuli on the electrical potential (EP) of the plants. The paper also summarizes a review of the effects of ESs on photosynthesis, the mechanisms of the effects, and its physiological role in plants. Local irritations of plants induce various photosynthetic responses including fast and long-term inactivation of photosynthesis and its activation. The paper also reviews the concept of plant energy harvesting. The measurement techniques used for ESs in plants including extracellular measurement and intracellular measurement are also reviewed. A brief summary of the applications of these methods for investigating ES in plants is also given.
Agrobiodiversity conservation enhances food security in subsistence-based farming systems of Eastern Kenya
(2016-09-15) Mburu, Simon Wambui; Koskey, Gilbert; Kimiti, Jacinta Malia; Ombori, Omwoyo; Maingi, John M.; Njeru, Ezekiel Mugendi
Background Globally, there is great concern about expanding agricultural activities due to their impact in the conservation of agrobiodiversity. African continent is known for its richness in biodiversity. In Kenya, there is a continuous unabated expansion of agriculture into natural habitats due to demographic and economic pressures posing a significant threat to biodiversity. Therefore, there is a need to study biodiversity loss and its regain through practices in agricultural landscapes. In this study, we assessed the status of agrobiodiversity and its contribution to food security in four agroecological zones of Eastern Kenya. Sixty households were sampled from two selected agroecological zones (upper and lower midland zones) in Embu and Tharaka-Nithi counties. Structured questionnaires and checklists were used to collect the data. Results Thirty-nine crop species were identified dominated by vegetables, fruits, legumes and cereals with relative densities of 28.8, 20.5, 18.3 and 8.3 %, respectively. Embu Lower Midland and Tharaka-Nithi Lower Midland zones had relatively higher crop species richness of 243 and 240, respectively, and Shannon–Wiener diversity indices (H′) of 3.403 and 3.377, respectively, compared with Embu Upper Midland and Tharaka-Nithi Upper Midland zones with species richness of 229 and 207, respectively, and H′ of 3.298 and 3.204, respectively. Conclusions Households from lower midland zones with high crop diversity and richness were more food secure compared with those from the Upper Midland zones with low crop diversity and richness. These findings suggest that farm production systems with high agrobiodiversity contributed more toward food security among smallholder farmers in the selected sites.
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.
Behavioral patterns and responses to human disturbance of wild somali ostrich in Samburu, Kenya
(2016) Mutiga, MaricianoIguna 1; Muoria, Paul Kimata 2; Kotut, Kiplagat 1; Karuri, Hannah Wangari 1
Somali ostrich has suffered a drastic decline in its population and range mainly due to hunting over the years for meat, skin and feathers. Urgent conservation measures should therefore be taken to reverse this trend particularly in their current population stronghold, the Samburu landscape. In this range, the magnitude and consequences of human disturbance on the ostrich has not been established. The aim of this study was therefore to investigate the behavioural patterns and assess the impacts of human disturbance to the bird. Focal animal sampling was used to establish ostrich‟s behavioural activity budget while the magnitude of human disturbance was assessed by determining and comparing flight initiation distances in the protected and partially protected areas. Somali ostrich spent most of their diurnal time in feeding and moving, and are more sensitive to human disturbance in the protected areas than they are in the partially protected areas. The results of this study imply that the ratite does not differ in behavioural patterns from other extant ostrich species and human disturbance is not posing a significant threat to its survival within Samburu landscape. Further studies are recommended for better understanding of the conservation status of the newly published species.
Biological control of desert locust (Schistocerca gregaria Forskål)
(CAB International, 2021) Githae, Eunice W.; Kuria, Erick K.
Desert locust (Schistocerca gregaria Forskål) is one of the most serious agricultural pests in the world due to its voracity, speed of reproduction, and range of flight. We discuss the current state of knowledge on its biological control using microorganisms and botanical extracts. Metarhizium flavoviride was among the first fungus to be recognized as a bio-control agent against desert locust in the laboratory and field conditions. Nevertheless, its oil formulation adversely affected nontarget organisms, hence led to further research on other microorganisms. Metarhizium anisopliae var. acridum (syn. Metarhizium acridum) is an environmentally safer bio-pesticide that has no measurable impact on non-target organisms. However, there are various shortcomings associated with its use in desert locust control as highlighted in this review. Bacterial pathogens studied were from species of Bacillus, Pseudomonas, and Serratia. Botanical extracts of 27 plant species were tested against the locust but showed varied results. Azadirachta indica and Melia volkensii were the most studied plant species, both belonging to family Meliaceae, which is known to have biologically active limonoids. Out of the 20 plant families identified, Apiaceae was the most represented with a frequency of 21%. However, only crude botanical extracts were used and therefore, the active ingredients against desert locust were not identified. Through a comprehensive research, an integrated pest management strategy that incorporates these bio-controls would be a realistic option to control desert locust infestations.
A botanical inventory and diversity assessment of Mt. Marsabit forest, a sub-humid montane forest in the arid lands of northern Kenya
(Blackwell Publishing Ltd, 2007) Githae, Eunice W. 1,2; Chuah-Petiot, Mins 2; Mworia, John K. 2; Odee, David W. 1*
A botanical inventory and diversity of trees, shrubs (‡5 cm diameter at breast height [dbh]), herbs, climbers and lianas was assessed in plots (154) of 20 · 5 m in Mt. Marsabit forest, northern Kenya. We recorded 52 species of trees and shrubs, twelve species of herbs and six species of climbers and lianas. They belonged to 35 families and 64 genera. Rubiaceae was the richest family with nine species followed by Euphorbiaceae (six), Oleaceae (five), Rutaceae (four), Capparaceae, Labiatae and Leguminosae (three each). The rest of the families were represented by one or two species. Rinorea convallarioides (Bak.f.) Eyles ssp. Marsabitensis Grey-Wilson (Violaceae), an endemic species, and Drypetes gerrardii Hutch. (Euphorbiaceae), were the two most important species, accounting for more than third of the combined importance value. Species diversity indices were 2.735 (Shannon–Wiener), 0.88 (Simpson’s) and 0.296 (Evenness). There was a strong evidence of disturbance arising from anthropogenic and wildlife foraging activities. This inventory has affirmed Mt. Marsabit forest as a unique habitat for several endemic, rare, threatened or vulnerable plant species, which should be conserved.
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.
Characteristics of Waste Pickers in Nakuru and Thika Municipal Dumpsites in Kenya
(Journal of Applied Science and Technology, 2019-08-21) Kariuki, Joseph Maina; Bates, Margaret; Magana, Adiel
Dumpsite waste picking is prevalent in many developing countries of which Kenya is one. Waste pickers play an important role in waste recycling by recovering and providing materials to the waste recycling industry. Aim: The purpose of the study was to characterise the demographic and socio-economic factors of waste pickers in Nakuru and Thika municipal dumpsites. Study Design: The research design was a cross-sectional social survey and the sample size was 167. Place and Duration of Study: The study was carried out in the largest dumpsite in Nakuru and Thika towns found in Nakuru and Kiambu counties respectively. Methodology: The data was collected by use of structured questionnaire. The data was analysed using the Statistical Package for Social Sciences. Analysis was by frequency tables, χ2 test and ttest at 95% level of confidence. Results: The results show that there was parity by gender in Nakuru but in Thika the proportion of females was much higher than that of males. There was significant association between age and site of operation with waste pickers in Thika being on average younger than in Nakuru (χ = 12.605, d.f. = 3, p = 0.006). Waste pickers in Thika had on average attained a higher level of education than in Nakuru (χ2 = 12.352, d.f. = 3, p = 0.006). Most of the waste pickers (96%) only picked from exclusively from the dumpsite. Waste pickers in Thika spent an average of 10.26±0.23 hours daily in waste picking which was significantly higher (t=-3.709, n=160, p<.001) than at Nakuru (8.97±0.27 hours). The mean number of years of waste picking in Thika was significantly less than in Nakuru (t=4.627, d.f.=158, p<.001). Conclusion: In conclusion, waste pickers play an important role in waste recycling, with waste picking supporting hundreds of waste pickers in the study area, who are important in integrated waste management and need to be understood, appreciated and supported.
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.
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.
Ecological restoration of pastoral landscapes in the drylands of East Africa
(Journal of Dryland Agriculture, 2021-01-26) Githae, E. W.; Mutiga, I. M.
The East African drylands cover about 47% of the land surface and host about 20 million people. Rural people living in the drylands are mainly pastoralists who depend on livestock for both economic and social well-being. During the dry season, pastoralists apply strategic mobility to access grazing resources efficiently. However, this strategy has experienced change and constraints due to various demographic- and climate-related challenges. Pastoral lands have been cleared for large-scale agriculture while pastoralists have shifted towards agro-pastoralism. This has eroded many dryland trees and forests leading to environmental degradation. This review discusses important indigenous trees that can be utilized in ecological restoration of drylands as well as providing ecosystem goods and services. These include trees for gums and resins (Acacia, Commiphora and Boswellia), indigenous fruit trees (IFTs) (Adansonia digitata, Tamarindus indica and Balanites aegyptiaca), trees for wood (Melia volkensii and Terminalia brownie) and fodder (Acacia tortilis and Faidherbia albida). They are not only drought-tolerant but also have minimal disruption to the ecosystem. Various dryland restoration strategies and constraints are also discussed. For successful establishment, seedling planting should be integrated with other appropriate practices such as natural regeneration, silviculture and enrichment planting for sustainable dryland management.
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.
Effector gene vap1based DGGE fingerprinting to assess variation within and among Globodera species and populations.
(2019-11-12) Nuaima, Rasha Haj 1 , 2; Mwangi, James M. 3; Kiewnick, Sebastian 3; Heuer, Holger 1
Population-level genetic tools to study the epidemiology of potato cyst nematodes (PCN) are needed to evaluate their adaptive potential and validate management strategies. The effector gene vap1 is essential in early infection by PCN. We expected high allelic variation due to diversifying selection. A technique was developed specifically to amplify vap1 fragments of PCN, and electrophoretically separate variants in a denaturing gradient (DGGE). Sequenced gene variants differed in intron as well as exon regions. Siblings were more similar in vap1 pattern than juveniles from different cysts. Nearly all juveniles analysed had unique patterns with up to ten or five vap1 variants for Globodera pallida or G. rostochiensis, respectively. Patterns differed significantly among populations, with similarities increasing from between-species, within-species to within-pathotype comparisons. In conclusion, the method is suitable to determine the similarity of heterogeneous PCN populations for studies on their temporal change and spread.
Effects of Auxin and Source of Explants on Callus Induction of Tropical Maize
(2012) Omer, Rasha Adam; Matheka, Jonathan M.; uno, Steven R.; li, bdelbagi M. A; Kuria, Eric; Masiga, Clet; Mugoya, Charles; Machuka, Jesse
Induction of callus from explants is a critical process in regeneration, micropropagation and transformation of plants. Formation of callus from plant tissues on culture is affected by different factors. This study sought to establish the effect of genotype, source of explants and auxin concentration on callus induction from different Sudanese maize genotypes (222F, Hudiba-1, 441, Giza-2, PR5655 and Mojtamma-45). Callus induction of the six maize varieties was investigated using mature embryos, leaf disks and shoot tips as explants and different concentrations of the auxin; 2,4-dichlorophenoxyacetic acid (2,4-D), ranging from 0 to 10 mg L-1. The highest callus, induction frequency was observed in shoot tips while the lowest was observed in mature embryos. Leaf disks gave a higher callus induction frequency than mature embryos and lower than shoot tips. Concentrations of 2,4-D of 2 mg L-1 gave the highest callus induction for most genotypes while 0 and 10 mg L-1 gave the lowest callus induction for all the genotypes.
Effects of dibenzylbutyrolactone lignans arctigenin and trachelogenin on the motility of isolated rat ileum
(Elsevier, 2022) Koech, Peter Kiplang’at; Boldizsar, Imre; Dobolyi, Arpad; Varro´, Petra
Dibenzylbutyrolactone-type lignans are phenolic compounds of medical importance. The purpose of the study was to determine the effects of two such lignans, arctigenin and trachelogenin on the motility of isolated rat ileum and obtain indications on their mechanism of action. They were isolated from Arctium lappa and Cirsium arvense, respectively, which have been used traditionally to treat gastrointestinal disorders. 1–1.5 cm long segments of distal ileum were obtained from adult male Wistar rats. The intestinal segments were suspended vertically in a well-aerated organ-bath according to Magnus mounting method. The intestinal motility was monitored for 30 min before treatment to obtain the baseline, followed by treatment with 1 µM, 10 µM, 20 µM and 40 µM concentrations of arctigenin and 0.5 µM, 1 µM, 10 µM and 20 µM of trachelogenin concentrations. The amplitude, tone, and period of spontaneous contractions were measured after 15 and 30 min of treatment. To investigate their mechanism of action, cholinergic, glutamatergic, adrenergic antagonists and compounds inhibiting nitric oxide synthase and L-type calcium channels were also tested. Arctigenin and trachelogenin decreased the frequency of contractions in a dose-dependent manner. At the concentration of 20 µM and 40 µM of trachelogenin and arctigenin, respectively, there was a marked alteration in spontaneous contraction pattern with an observable increase in the period time. This activity was comparable to 0.5 µM nifedipine (L-type calcium channel blocker) treatment. Our results demonstrate relaxant effect of arctigenin and trachelogenin on the ileum motility that may be mediated by L-type calcium ion channel blockade.
Enhanced Utilization of Biotechnology Research and Development Innovations in Eastern and Central Africa for Agro-ecological Intensification
(Springer, 2014-07-16) Masiga, Clet Wandui; Mugoya, Charles; Ali, Rasha; et al
The Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA) through its Agrobiodiversity and Biotechnology Programme is enhancing the utilization of biotechnology research and development innovations in Eastern and Central Africa (ECA). We present successes in the application of biotechnology to enhance the productivity of cassava, sweet potato, banana, maize and sorghum in ECA. These products—drought tolerant maize, sorghum resistant to striga, as well as the technology for producing and distributing disease free planting materials of cassava, sweet potato and banana to farmers—are central for the agro-ecological intensification of farming systems in the central African highlands.
Factors enhancing the level of utilisation of research knowledge on ecosystems
(CABI, 2021-07) Eschen, R.; Mbaabu, P.K.; Ramamonjisoa, B.S.; Robledo-Abad, C.
The significant resource investment in research on ecosystems for development of the Global South does not necessarily result in high levels of research knowledge utilisation (RKU). Understanding the factors associated with various levels of RKU can inform funding agencies and researchers developing new projects. We applied a combination of a questionnaire survey and follow up interviews with members of research teams of multiple, broadly comparable projects to make an assessment of achieved RKU levels using a combination of quantitative statistical hypothesis testing and narrative description of survey responses. Research knowledge dissemination by members of the project team who work for non-academic institutions or champions, e.g. particularly motivated people that promote and facilitate implementation or adoption of the project results, and via television was associated with higher research knowledge utilization. By contrast, dissemination by members of the project team working for academic institutions and via peer-reviewed journals was associated with lower RKU. The achieved level of RKU was consistently lower than the targeted level of RKU across spatial scales. The discrepancy between the perceived level of RKU and the evidence provided by survey respondents indicates the need for better monitoring the utilisation of research knowledge in development pathways. Our results further suggest that three years project duration is too short to achieve high levels of RKU in socio-ecological systems. We recommend involvement of non-academic members of the project team in project design, leadership and dissemination for increasing RKU.
Genetic Characterization and Diversity of Rhizobium Isolated from Root Nodules of Mid-Altitude Climbing Bean (Phaseolus vulgaris L.) Varieties.
(2018-05-15) Koskey, Gilbert 1,; Mburu, Simon W. 1; Kimiti, Jacinta M. 2; Ombori, Omwoyo 3,; Maingi, John M. 1*; Njeru, Ezekiel M. 1
The increasing interest in the use of rhizobia as biofertilizers in smallholder agricultural farming systems of the Sub-Saharan Africa has prompted the identification of a large number of tropical rhizobia strains and led to studies on their diversity. Inoculants containing diverse strains of rhizobia have been developed for use as biofertilizers to promote soil fertility and symbiotic nitrogen fixation in legumes. In spite of this success, there is paucity of data on rhizobia diversity and genetic variation associated with the newly released and improved mid-altitude climbing (MAC) bean lines (Phaseolus vulgaris L.). In this study, 41 rhizobia isolates were obtained from the root nodules of MAC 13 and MAC 64 climbing beans grown in upper and lower midland agro-ecological zones of Eastern Kenya. Eastern Kenya was chosen because of its high production potential of diverse common bean cultivars. The rhizobia isolates were characterized phenotypically on the basis of colony morphology, growth and biochemical features. Rhizobia diversity from the different regions of Eastern Kenya was determined based on the amplified ribosomal DNA restriction analysis (ARDRA) of PCR amplified 16S rRNA genes using Msp I, EcoR I, and Hae III restriction enzymes. Notably, native rhizobia isolates were morphologically diverse and grouped into nine different morphotypes. Correspondingly, the analysis of molecular variance based on restriction digestion of 16S rRNA genes showed that the largest proportion of significant (p < 0.05) genetic variation was distributed within the rhizobia population (97.5%) than among rhizobia populations (1.5%) in the four agro-ecological zones. The high degree of morphological and genotypic diversity of rhizobia within Eastern Kenya shows that the region harbors novel rhizobia strains worth exploiting to obtain strains efficient in biological nitrogen fixation with P. vulgaris L. Genetic sequence analysis of the isolates and testing for their symbiotic properties should be carried out to ascertain their identity and functionality in diverse environments.

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