Biological Sciences
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Item 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., FredrickHealth 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.Item 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. OgollaHerbals 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.Item 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, FredrickThe 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.Item 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, FredrickThe 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.Item 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., OtienoMushrooms 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.Item 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, FrancisBackground: 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.Item 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, AdielDumpsite 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.Item 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.Item Action and variation potential electrical signals in higher plants(African Journal of Biological Sciences, 2021) Ndung’u, Ruth Wairimu; Kamweru, Paul Kuria; Kirwa, Abraham TuweiThis 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.Item Synergistic Evaluation of Selected Plant Extracts on Potency of Pyrethrins against the Maize Weevil, Sitophilus zea-mais (MOTSCH.)(Merit Res. J. Agric. Sci. Soil Sci., 2020) Michura, Anne Jerotich Garry; Magana, Adiel; Ochieng, Ombaka; Gachoka, KennedyThe interest in utilization of botanical insecticides, particularly essential oils have become increasingly relevant in the control of insect pests. Many plant products and their bioactive compounds with repellent, antifeeding or insecticidal activity against stored product insect pests have been reported however, their levels of control are still wanting. The major issue is that the oil yields obtained are low, unstable and high costs involved in production to use on a commercial scale. Use of these oils in combinations or in formulations with botanical actives as synergists or stabilizers, may make them economically viable insecticides. The present study focussed on evaluating plant extracts (Black pepper seeds, Nutmeg seeds, coriander leaves and roots) as potential synergists in formulations with pyrethrins for possible use in protection of stored grains against Sitophilus zea-mais. Full dose response and synergism experiments were carried out on S. zea-mais at four concentrations of synergists at ratio 1:1 (synergist: pyrethrins) Topical application of synergist/ formulation on S. zea-mais was done in triplicate using Factorial Design in a completely Randomized Design layout. Experiments were conducted under controlled laboratory conditions of 27 ± 2OC and 60 ± 5%RH with normal day light hours. Probit analysis was used to determine the lethal concentration (LC) of pyrethrins and ANOVA was used to obtain the mean mortality differences of S. zea-mais at P ≤ 0.05. LC20 value for pyrethrins was found to be 2,200 ppm. In formulations of synergist: pyrethrins, coriander leaves extract (CLHE), Nutmeg seed extract (NMHE) and Black pepper seed methanol extract (BPSME) were statistically significant (P ≤ 0.05) 24 h after exposure. PBO registered higher percentage (83.33 ± 12.02%) mortality followed by CLHE (46.67 ± 3.33%), BPSME (43.33 ± 6.67%). BPSME and NMHE co-toxicity values were below 20 and -20 respectively while in PBO, BPSHE and CLHE values were above 20. Plant extracts BPSHE and CLHE and PBO synergized the toxicity of pyrethrins in all concentrations over 72 h exposure duration with co-toxicity factors above 100. BPSME was shown to be an additive in the formulation and only a synergist at 20,000ppm while NMHE was antagonistic to pyrethrins. Increasing the concentration of a plant extract did not correspond to increased efficacy of the formulation. Efficacy of the synergist- pyrethrins formulations at lower concentrations can be economically viable since average percentage mortalities will not be different from that of higher concentrations when time of interaction is prolonged. It is recommended that BPSHE and CLHE can be synergists to pyrethrins when formulations are exposed to insects for 72 h durationItem Screening of Plant Extracts Possessing Methylenedioxyphenyl (MDP) Group as Potential Synergists in Insecticide Formulations using the Maize Weevil, Sitophilus Zea-mais (Motsch.)(Merit Research Journals, 2020) Michura, A.J.G; Magana, A.; Ombaka, O.; Gachoka, K.Synergists are compounds that are either negligibly toxic or non-toxic to insects when applied on their own, but enhance the efficacy of an insecticide. Many insects are able to detoxify insecticide molecules and survive their application. Early studies found that most methylene-dioxyphenyl (MDP) agents themselves possess relatively low intrinsic toxicity, but strongly influence the actions of other xenobiotic in mammals and insects. The current commercial synergist, Piperonyl butoxide (PBO), though effective as a synergist, is not classified as an organic product in many countries. With the current focus on decreasing environmental contamination and increasing demand for organic products, a natural compound for use as a synergist would be ideal. Searches for effective synergists have not yet yielded many compounds that have the viability equivalent to that of PBO. This paper screened plant extracts possessing MDP rings as potential synergists in insecticides formulations using the maize weevil, Sitophilus zea-mais. Dose-mortality experiments were carried out on S. zea-mais at four concentrations of synergists. Topical application of synergist on S. zea-mais was done in triplicate in a CRD. Experiments were conducted under controlled laboratory conditions of 27 ± 2OC and 60 ± 5%RH with normal daylight hours. Analysis of Variance (ANOVA) was used to obtain the mean mortality differences of S. zea-mais at P ≤ 0.05 while Duncan’s Multiple Range Test (DMRT) was used to rank significant concentration means within a synergist. Black pepper seed hexane extract (BPSHE) and PBO after 48 h exposure were statistically significant (P ≤ 0.05) with the average percentage mortalities of 10% and 20% at 10,000 ppm and 20,000 ppm respectively, while PBO and Coriander leaves hexane extract (CLHE) were significant P ≤ 0.05 after 72 h. PBO was the most toxic synergist (36.67 ± 3.33%) followed by CLHE (26.67 ± 3.43%) at 20,000 ppm. It can be concluded that the plant extracts tested and statistically significant at a particular exposure time can be used to replace the standard PBO in insecticide formulations since their inherent toxicity is low. At a higher concentration (20,000 ppm) PBO was the most toxic synergist which could be contributing to the toxicity of insecticide when used in formulations.Item Physicochemical Proprieties of Pond Water in the Economic Stimulus Programme (ESP) Fish Ponds in Tharaka-Nithi County, Kenya(International Journal of Interdisciplinary Research and Innovations, 2020) Kibaara, David Ithigi; Magana, Adiel Micheni; Githae, Eunice Wmamu; Ombaka, OchiengIn an effort to attain food security, Kenya has embraced aquaculture as one of its strategies. From 2009, the Government established thousands of fish ponds through the Economic Stimulus Programme (ESP). TharakaNithi County was one of the places covered by the ESP and has 95% of its total ponds under the programme, stocked with the Nile tilapia (Oreochromis niloticus). Physicochemical properties of water influence overall pond productivity and fish yields. The ponds in Tharaka-Nithi County have suffered low production, the average production remaining at <30% of potential, with reports of stunting and frequent fish mortalities. This study aimed to investigate the physicochemical properties of the pond water in the county. Using the randomized complete block design (RCBD), the study area was divided into three zones whereby 27 fish ponds were studied. Chemical analysis was done according to the APHA Standard Methods and data analyzed using the one-way ANOVA. The Statistical Package for the Social Sciences (SPSS) Version 22.0 was used for correlations and regression analyses. Significant differences (p ˂ 0.05) were found in water temperature, dissolved oxygen, transparency, pH and conductivity among ponds in the three zones. Water temperatures, ammonia and PO4-P concentrations were outside the recommended range for optimum O. niloticus growth. Occasionally, DO and pH were outside those suitable for optimum tilapia growth, which could explain the frequent fish deaths and low aquaculture production. Regular monitoring of physicochemical parameters is recommended. These findings will be used by relevant government agencies and fish farmers to enhance fish production.Item 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´, PetraDibenzylbutyrolactone-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.Item Spider silk: A natural marvel of mechanical and structural strength(African Journal of Biological Sciences, 2021-10) Kuria, K.; G., JaneThe spider silk fibers have unique high performance properties that make it a desirable model for artificial fibers and its performance under benign conditions has important implications for biomimicry. It has tensile strengths comparable to steel and some are nearly as elastic as rubber on a weight to weight basis. The spider spins its silk at ambient temperatures, low pressures and with water as solvent. Spiders are ectotherms and the ambient temperature affects the spinning speed and the mechanical and structural properties of the silk spun. The high cytocompatibility and low immunogenicity of spider silk fibers make them well suited for biomaterial products such as nerve conduits. Spider silk proteins have been shown to be soluble in ionic liquids, thus once soluble, they can be processed into new biomaterials such as films, gels, porous sponges, bone tissue engineering. The spider silk chains with a fixed molecular weight decreases exponentially with the UV irradiation time, since UV irradiation causes the chemical bonds in the protein chains to undergo cleavage. This paper reviews related literature on the spider silk spinning process, conditions and their effects on structure, mechanical properties of spider silk and its resistance to UV degradation. As a bonus, a brief review of the biotechnological production of recombinant spider silk us presented.Item 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.Item 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.Item Nitrogen Fixation by Natural Populations of Acacia Senegal in the Drylands of Kenya Using 15N Natural Abundance(Taylor and Francis Online, 2013-06-24) Githae, Eunice W.; Gachene, Charles K.K.; Njoka, Jesse T.; Omondi, Stephene F.Nitrogen (N) fixation was estimated for three Acacia senegal (L.) (A. senegal) Willd. varieties (A. senegal var. senegal, kerensis, and leiorhachis) growing naturally in different sites in the dryland areas of Kenya. The quantities of N2 fixed were estimated by the 15N natural abundance method, using leaves as the sampling material. Balanites aegyptiaca (B. aegyptiaca) was selected as the reference species growing in the same area. Soil samples were also collected under A. senegal trees for nodule assessment. Leaf 15N natural abundance values (δ15N) were significantly different between A. senegal and B. aegyptiaca. These values averaged 6.35, 4.67, and 3.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively, and were lower than those of the adjacent reference species. There were also significant differences in the amount of N2 fixed (% Ndfa) among the varieties. A. senegal var. senegal showed the highest levels of N2 fixation with a mean of 36% while A. senegal var. kerensis and leiorhachis had equal estimates of 25%. However, no nodules were observed in the collected soil samples. Leaf N values were significantly different among the varieties with a mean of 2.73, 2.46, and 4.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively. This study shows that the three varieties of A. senegal are able to fix N2 in their natural ecosystems and the differences could probably be due to soil properties and nutrient availability under the different environments. The species can hence be utilized as plantations in agriculture and land rehabilitation programs.Item Soil physicochemical properties under Acacia senegal varieties in the dryland areas of Kenya(2011-08) Eunice, G. W.; Charles, K.K.; Jesse, T. N.Acacia senegal is a multipurpose drought-tolerant tree or shrub legume and is commonly used in agroforestry systems in sub-Saharan Africa for gum arabic production and soil fertility improvement. Despite its wide distribution in Kenya, there has not been exhaustive evaluation on the effects of the extant varieties (kerensis, leiorhachis and senegal) on soil properties under their canopies for sustainable utilization of the species. Three sites in the drylands of Kenya representing the three varieties were selected for assessment. Soil samples were collected under tree canopies at a depth of 0 to 25 cm and were compared with the soils from the open canopies. There were significant differences in soil physicochemical properties among the three varieties (P< 0.01). Soil nutrients under the canopies were higher than in the open canopies mainly due to effects of litter accumulation. The three varieties have beneficial effects on soil nutrient status in their natural ecosystems and would most likely improve crop productivity in agroforestry systems as well as enhance herbage productivity in the rangelands. The varieties growing under different soil types may have an effect on their gum Arabic production and quality.Item 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.Item Status of Opuntia invasions in the arid and semi-arid lands of Kenya(CAB Reviews, 2018-03) 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.