Theses and Dessertations

GENETIC DIVERSITY AND POPULATION STRUCTURE IN Trichilia emetica Vahl. IN WESTERN KENYA

Wed, 01 Jan 2025 00:00:00 GMT

GENETIC DIVERSITY AND POPULATION STRUCTURE IN Trichilia emetica Vahl. IN WESTERN KENYA SIRMA, ELIAS Trichilia emetica Vahl. Commonly known as Natal Mahogany (Family: Meliaceae) is a multipurpose tree of high ecological and socio-economic value across sub-Saharan Africa. In Kenya, however, its genetic resources remain largely uncharacterized. Current knowledge focuses mainly on ethno medicinal uses, photochemistry, and propagation biology, with no molecular data available to describe its genetic diversity or population structure. Without molecular information, it is difficult to determine whether populations are genetically connected or isolated, whether inbreeding is occurring, or whether genetic erosion is already underway. Although T. emetica is globally classified as Least Concern, localized population declines in Kenya indicate that its genetic base may already be narrowing, reducing its adaptability to environmental change. This lack of molecular insight is a major barrier to designing evidence-based conservation, restoration, and domestication strategies. This study sought to (i) characterize phenotypic variation of T. emetica using eight quantitative morphological traits across six natural populations in western Kenya and (ii) determine the genetic diversity and population structure of six natural populations of T. emetica in western Kenya using Inter-Simple Sequence Repeat (ISSR) markers. A total of 120 leaf samples were collected from Bungoma, Kakamega, Kisumu, Siaya, Vihiga, and Nandi counties. The morphological analysis revealed substantial variation across populations, with tree height, diameter at breast height, crown diameter, flower length, seeds per fruit, seed length, and seed dry weight differing significantly (p < 0.05). Variation within populations (67.33%) exceeded that among populations (32.67%), and clustering consistently distinguished Nandi as a separate group, Bungoma–Kakamega as another, and Kisumu–Siaya–Vihiga as a third. At the molecular level, 171 fragments were amplified, 162 of which were polymorphic, corresponding to a polymorphism rate of 94.65%. Diversity indices revealed Nei’s gene diversity (H) of 0.34 and Shannon’s index (I) of 0.51, with Nandi exhibiting the highest diversity and Kisumu–Siaya the lowest. Analysis of Molecular Variance (AMOVA) indicated that 65% of the genetic variation was distributed within populations and 35% among them. Principal coordinates analysis and Nei’s genetic distance dendrograms confirmed three genetic clusters, with Nandi being genetically isolated. This study is one of the first to assess the genetic diversity of T. emetica in Kenya, demonstrates that the species maintains considerable diversity despite fragmentation. Therefore, conservation strategies should prioritize in situ protection of genetically distinct populations such as Nandi, while safeguarding all populations to preserve intra-population diversity. Ex-situ measures, including representative sampling for seed banks and nurseries, are recommended to complement in situ strategies. Future research should expand to other ecological zones and integrate adaptive trait analyses to support domestication, breeding, and sustainable utilization of this valuable species.

MOLECULAR PHYLOGENY, PHYTOCHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES OF SELECTED KENYAN POPULATIONS OF DODONAEA VISCOSA (SAPINDACEAE)

Wed, 01 Jan 2025 00:00:00 GMT

MOLECULAR PHYLOGENY, PHYTOCHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES OF SELECTED KENYAN POPULATIONS OF DODONAEA VISCOSA (SAPINDACEAE) LANGAT, PHILEMON The family Sapindaceae is diverse, with four subfamilies. The genus Dodonaea (Sapindaceae) is endemic to Australia and widespread in Kenya in various habitats. There are two varieties found in Kenya. The taxonomic relationship between them is quite confusing. The two have many ethnomedicinal uses. Microbial organisms cause several diseases in plants and animals and with time, have developed resistance to most conventional drugs. The phytochemical components of plants haave specific pharmacological effects on the human body and exert their therapeutic value. Secondary metabolites isolated from plants are also important in chemotaxonomy. This study provided a phylogenetic analysis that included nucleotide frequency and substitution rates, base composition disparity index and evolutionary divergence. Eleven Kenyan populations of Dodonaea viscosa had their ribulose-bisphosphate carboxylase (rbcL) and internally transcribed spacer 1 (ITS1) genes extracted and Sanger sequenced. They were aligned by MUSCLE (codons) and exported to MEGA 11 and PhyloSuite for analysis. Phylogeny was constructed using ML and ITOL used to edit the cladograms. Prior to phylogenetic analysis a nucleotide BLAST of the sequence genes was done to identify the closest ancestor of Dodonaea viscosa. The sequences were also subjected to analysis by PCA. An analysis of phytochemical constituents of DCM: CH3OH leaf extract was conducted on Gazi 1C population. The agar well diffusion method was used to determine the antimicrobial activity, while antidiabetic activity was carried out on Swiss albino rats. Data on antidiabetic activity were organized in excel tables and analyzed using ANOVA, and paired sample t-test. Graphical method was used to analyze data on antimicrobial activity. From the phylogenetic analyses, a narrow genetic distance exists amongst the Kenyan populations of Dodonaea viscosa. The PCA showed more variations in the Dodonaea populations studied using the rbcL gene compared to using the ITS1 gene. Phytochemical analysis identified 4 compounds from the leaves, which supplemented the bulk of data for chemotaxonomic analysis. This study revealed that the crude extract of Dodonaea viscosa was antidiabetic as it lowered blood sugar in STZ induced diabetic rats. Likewise, the crude extract showed antibacterial and antifungal activities, as evidenced by the inhibition zones, except in Escherichia coli. The antidiabetic activity of the roots and leaves of various populations did not differ significantly, at P-value of >0.05. Variance between the populations was also not statistically different, as the P-value was 0.742. More antidiabetic activity was observed in the reference drug, followed by the plant extract at a dose of 400 mg/kg bwt, with the lowest activity at 200 mg/kg bwt. Similarly, more antimicrobial activity was observed from the positive controls (Amoxicillin and Apron), followed by the plant extracts. More studies targeting other gene areas with different primers are recommended to establish a full relationship between the Dodonaea viscosa Kenyan populations. There is a need for more bioassays on the compounds isolated from this study to determine the biological potential of this widely distributed plant.

TAXONOMIC STUDY OF THE Cyperus dives DELILE COMPLEX IN EAST AFRICA

Wed, 01 Jan 2025 00:00:00 GMT

TAXONOMIC STUDY OF THE Cyperus dives DELILE COMPLEX IN EAST AFRICA TALLAM, RUTH Cyperus dives complex comprises four taxa: Cyperus alopecuroides Rottb, Cyperus dives Delile, Cyperus imbricatus Retz and Cyperus exaltatus Retz; whose taxonomic recognition varies among different authors. This study investigated the morphological variation within and between taxa in the complex in the East African region. Herbarium Specimens deposited at the East African Herbarium (EA) and Makerere University Herbarium (MUH) were examined. Morphometric data on gross morphology was collected and analysed using Cluster, Principal Component, Discriminant and Univariate analyses, using the GenStat statistical package version 2014 by VSN International Ltd. Data on distribution patterns were gathered from herbarium specimen labels and Gazetteers consulted where coordinates details were missing. Arc Map10.42 software was used to generate map to identify where various taxa within the complex are located. Examination of achenes using the scanning electron microscope (SEM) was also done. In Principal Component Analysis (PCA), the first axis accounted for 38.4% of the total character variation. Here C. imbricatus formed a distinct group; with the other three taxa exhibiting considerable overlap. Cluster analysis followed the same pattern for the 39 OTUs studied; where C. imbricatus formed a very distinct cluster, with the other three taxa showing high levels of intermixing to form one large cluster. Discriminant analysis also reveals a clear separation between C. imbricatus and the other three along root 2 while in univariate analysis it showed significant levels of statistical difference with the other three species in most of the characters used in the analysis. Based on these analyses C. imbricatus is clearly distinct from the rest of the taxa in the complex. Variations seen across the taxa were mostly in respect of length of the nutlet, stigma, filament and anther. Also, the leaf sheath width and inflorescence length. Based on these results, it can be concluded that, Cyperus dives complex consists of one distinct species (C. imbricatus) and three variables (C. alopecuroides, C. exaltatus and C. dives) that should be considered for ranking at the infraspecific level. The distribution patterns of the taxa within the complex are apparently based on their ecological preferences with some overlaps in the distribution, whereas the presumed distinct species showed a wide distribution and altitude range among all the taxa.

CHARACTERIZATION OF SANDFLY POTENTIAL VECTORS AND RESERVOIR HOSTS OF CUTANEOUS LEISHMANIASIS AND THEIR HABITATS IN BUNGOMA COUNTY, KENYA

Wed, 01 Jan 2025 00:00:00 GMT

CHARACTERIZATION OF SANDFLY POTENTIAL VECTORS AND RESERVOIR HOSTS OF CUTANEOUS LEISHMANIASIS AND THEIR HABITATS IN BUNGOMA COUNTY, KENYA MULONGA, WEKESA JOB Cutaneous leishmaniasis (CL), a neglected tropical disease caused by Leishmania parasites and transmitted by sandfly vectors, is a significant health concern in Bungoma County, and other Kenyan leishmaniasis-endemic counties. The present study aimed to characterize the distribution and ecological attributes of habitats of sandfly vectors and reservoir hosts of CL. The research objectives included: determining sandfly species diversity and abundance in identified sandfly habitats, evaluating the effects of temperature, relative humidity, and altitude on sandfly occurrence, analyzing soil characteristics in sandfly habitats for their physical and chemical properties, determining the association of sandfly populations and plant species populations in the study area, and evaluating the relationship between potential vertebrate reservoir hosts populations and sandfly populations in the study area. Sandflies were collected from their habitats using CDC light traps, dissected and identified morphologically between January 2021 and December 2022. Species diversity and evenness was analyzed using the Shannon-Weinner’s diversity index. A total of 6,156 sandflies were captured, with Phlebotomus pedifer accounting for 94%, P. elgonensis 0.5%, and Sergentomyia species 5.5%of the collections. Environmental factors, including temperature (21– 29°C), relative humidity (75-90%) and altitude (1,506–3,100 masl), were significant (P < 0.05) determinants of sandfly distribution. The correlation between soil properties and sandfly abundance was non-significant. Plant species diversity index (3.14 H’) and vertebrate diversity index (2.06 H’) indicated strong association with sandfly abundance, highlighting ecological drivers of the vector populations. The study concluded that Phlebotomus pedifer is the dominant sandfly vector species of CL in Bungoma County; while it is the people who go to the vector habitats (caves) who get bitten and become infected with CL. These findings underscore the need for habitat- specific interventions, such as environmental management to control sandfly populations in caves to reduce the transmission of CL in the study area and other similar regions.

ANTIBIOTIC SUSCEPTIBILITY AND PREVALENCE OF Staphylococcus aureus IN DIABETIC WOUNDS AMONG PATIENTS AT MOI TEACHING AND REFFERAL HOSPITAL, KENYA

Wed, 01 Jan 2025 00:00:00 GMT

ANTIBIOTIC SUSCEPTIBILITY AND PREVALENCE OF Staphylococcus aureus IN DIABETIC WOUNDS AMONG PATIENTS AT MOI TEACHING AND REFFERAL HOSPITAL, KENYA OGUDA, OWUOR DOMNIC The frequent source of deferred healing processes in wounds is Staphylococcus aureus worldwide. Diabetic wounds in diabetic patients contribute to delayed healing due to antibacterial resistance, which has caused a lot of suffering and a low quality of life for patients. This study investigated the prevalence, possible risk factors, and antimicrobial susceptibility profile of S. aureus isolated from diabetic wounds of patients attending Moi Teaching and Referral Hospital (MTRH). It involved purposive sampling; patients with diabetic wound infections who were willing to participate in the study were selected. The study included Type 2 Diabetes patients aged 13 years and above, who presented at the MTRH diabetic clinic during the study, and had not used antibiotics for any reason. The study targeted 156 diabetic patients attending MTRH. A questionnaire was administered to collect socio-demographic data. Wound swabs were aseptically collected and cultured on blood agar, then sub-cultured on Mannitol Salt Agar to isolate S. aureus. It was further identified by catalase and coagulase tests. Determination of antimicrobial susceptibility was by the Agar disk diffusion method. The occurrence of S. aureus in diabetic wounds was significantly (p=0.025) influenced by the sex of patients attending the diabetic clinic at MTRH. However, age (p=0.6503), underlying conditions (p=0.8437), previous hospitalization (p=0.808), previous antibiotic use (p=0.6874), marital status (p=0.118), and the level of education (p=0.192) do not significantly predispose the wounds of diabetic patients attending an outpatient diabetic clinic at MTRH to S. aureus. 31 samples were positive for S. aureus. An instance of intermediate sensitivity 26 (10.48%) was shown by S. aureus isolated in this study, with 72 (29.03%) resistance to antibiotics. However, most of the isolates were vulnerable to the test antibiotics. A higher number of S. aureus isolates were susceptible to Cefoxitin (96.77%) and Clindamycin (80.65%), with lesser susceptibility to Ampicillin (25.81%). A prevalence of 19.87%, Cefoxitin being effective against most of the S. aureus isolates, and a significant relation between sex and occurrence of S. aureus in diabetic wounds were established. Early surveillance and screening to detect any presence of MRSA in diabetic wounds and the susceptibility profile of S. aureus in diabetic wounds of patients attending the diabetic clinic at MTRH is recommended. Re- evaluation of the use of Ampicillin should also be taken into consideration to prevent widespread antibiotic resistance. Female diabetic patients should take more precautions to prevent any traumatic injury, which could lead to diabetic wound infections.

CHARACTERIZATION OF SELECTED KENYAN COWPEA CULTIVARS FOR TOLERANCE TO ACIDITY

Wed, 01 Jan 2025 00:00:00 GMT

CHARACTERIZATION OF SELECTED KENYAN COWPEA CULTIVARS FOR TOLERANCE TO ACIDITY SANG, JANETH Acid soils are normally deficient in available phosphorus and have high levels of soluble aluminium. Crops vary in sensitivity to acidity and associated stresses. Kenyan varieties of cowpea have not been tested for tolerance to acidity and phosphorus deficiency. This study was conducted to assess the response of selected cowpea cultivars to acidity and aluminium stress under laboratory and field conditions. A total of nine cowpea cultivars namely UOE-COWPEA-1, UOE-COWPEA-2, UOE-COWPEA-3, UOE-COWPEA-4, UOE-COWPEA-5, KENKUNDE-1, K-80, M-66 and KVU-27-1, were screened in culture solution containing 0 µM and 185 µM AlCl 3 at a pH of 4.3 and four which showed a greater ability to modify the culture solution pH and a higher relative net root length were further evaluated in the field. pH values of the culture solution were taken daily for a period of six days without adjustment. Root and shoot lengths were measured and recorded after six days. The field experiment were laid out in RCBD, where the two main plots were either limed (4 t/ha) or not limed. The treatments were phosphorus (TSP) (0.06 t/ha), lime, phosphorus plus lime and control (-P, -L) and four cowpea cultivars; UOE-COWPEA-2, KVU 27-1, K-80 and KENKUNDE-1 were grown for a duration of four months. Soil samples were analyzed prior to and after planting. Plant height, total number of leaves per plant, total number of branches per plant, leaf area per plant, plant biomass, number of pods per plant, pod length, number of seeds per pod, 100 seed weight and seed yield per plant were assessed using standard procedures. The nine cowpea cultivars screened increase the pH of the culture solution as the days progressed. The increase in the culture solution pH could be due to cowpea cultivars secreting chelating agents that reduce H + thereby increasing the culture solution pH and reducing Al toxicity. UOE-COWPEA-4 cultivar grown at 185 µM Al was the most tolerant with higher relative net root length (75.6%) while UOE-COWPEA-1 cultivar was the most Al sensitve (63.7%). Lime increased the soil pH from 5.23 to 6.37 while both P+L increased soil P to the maximum of 28.93 mg/kg with K-80 cultivar. UOE-COWPEA-2 produced the greatest number of leaves (52) and number of pods per plant (59) while K-80 yielded the highest total seed weight per plant (42g) with KENKUNDE-1 recording the greatest number of seeds per pod (12) all under phosphorus plus lime treatment. UOE-COWPEA- 2, UOE-COWPEA-4, UOE-COWPEA-5, K-80 and KEN-KUNDE-1 cultivars that showed greater promise in modifying the pH, superior growth and yield attributes, could be grown in acidic soils. The cultivars can be tested further to establish their stability in alleviating acidity.

PHYTOCHEMICAL COMPOSITION, ANTIBACTERIAL AND ALLELOPATHIC ACTIVITIES OF Achyranthes aspera AND Tagetes minuta LEAF EXTRACTS

Wed, 01 Jan 2025 00:00:00 GMT

PHYTOCHEMICAL COMPOSITION, ANTIBACTERIAL AND ALLELOPATHIC ACTIVITIES OF Achyranthes aspera AND Tagetes minuta LEAF EXTRACTS JEPTOO, LOYCE Antibiotic resistance remains a significant global health concern to date, putting at risk treatment options. As a result, treatments can be expensive and ineffective. It is therefore necessary to look for new options like using plant extracts with antimicrobial properties. Achyranthes aspera and Tagetes minuta have been traditionally used to treat various diseases in many communities and may possess antibacterial and allelopathic properties. Weeds cause more crop losses than insects, pests and diseases combined however their antimicrobial and allelopathic properties have not received much attention. This research aimed to determine the phytochemical composition, antibacterial and allelopathic activities of Achyranthes aspera and Tagetes minuta. Leaves were identified from the farm fields of University of Eldoret, collected, placed in sample collection bags, then transported to the laboratory. The leaves were washed, shade dried then ground to semi-powdery form. Extraction was conducted using sterile distilled water and ethanol. Extracts were tested against Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 51299, Klebsiella pneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 by disc diffusion method in a Completely Randomized design with three replications. Ciprofloxacin was used as a positive control. Clear zones around the discs were recorded as inhibition zones in millimetres. Maize, millet, rice and sorghum seeds were dressed with extracts to establish their allelopathic activities by placing five surface sterilized seeds in each petri dish. Fifteen millilitres of extracts were used with distilled water set as a positive control. The design of the experiments was Completely Randomized with three replications. ANOVA was used to determine statistical significance at P ≤ 0.05. A. aspera and T. minuta extracts showed significant inhibitory effects with inhibition zones of ≥13 mm compared to ≥17 mm from ciprofloxacin. Bio-activity of extracts was highest on S. aureus followed by E. faecalis then P. aeruginosa then E. coli with least effect on K. pneumoniae. Plumule and radicle lengths of the test plants were also significantly affected with percentage reductions of ≥63%. Extracts were more detrimental on Rice followed by Maize then Sorghum with minimal effect on Millet. Millet recorded the highest germination percentage of 89.44% while rice had the lowest percentage at 67.78%, with Maize (87.50%) and sorghum (85.83%). Alkaloids, coumarins, flavonoids, phenols, quinones, saponins, tannins and terpenoids were present in extracts of both plants while Anthraquinones, glycosides and steroids existed only in A. aspera. This study concludes that A. aspera and T. minuta have remarkable antibacterial and allelopathic activities. There is therefore need to balance between controlling these plants which grow as weeds and maintaining them aimed at utilization for the development of newer antimicrobials and/or bio-control agents.

IMPACT OF PARASITOLOGICAL, CLINICAL AND RENAL-HEPATIC BIOMARKER RESPONSES IN CHILDREN BELOW FIVE-YEAR OLD COINFECTED WITH MALARIA AND HIV IN WESTERN KENYA

Wed, 01 Jan 2025 00:00:00 GMT

IMPACT OF PARASITOLOGICAL, CLINICAL AND RENAL-HEPATIC BIOMARKER RESPONSES IN CHILDREN BELOW FIVE-YEAR OLD COINFECTED WITH MALARIA AND HIV IN WESTERN KENYA ARAMBE, MAMBO FIDELIS Malaria and HIV remain major causes of morbidity and mortality among children under five years in sub-Saharan Africa. Their co-infection presents a compounded health challenge, particularly in Western Kenya where Plasmodium falciparum transmission and HIV prevalence are both high. This study aimed to determine the burden of parasitemia and host biomarker responses in children aged below five years co-infected with P. falciparum and HIV. A cross-sectional case-control study involving 138 children aged 6–59 months was conducted at Kakamega County General Teaching and Referral Hospital. Parasitological diagnosis was done by microscopy and rapid diagnostic tests, while biochemical assays evaluated renal and hepatic function. Children co-infected with malaria and HIV were generally younger than those with HIV mono-infection, suggesting that mother-to-child acquired HIV predisposes to increased malaria susceptibility and severity in early life. The co-infected group had significantly higher median parasitemia (1,870 parasites/µL; range: 1,806–80,025), indicating intense transmission. Female children were more affected than males, suggesting possible gender-based differences in exposure, careseeking behavior, or immune response. Renal markers serum creatinine, urea, and blood urea nitrogen were significantly elevated in the co-infected group, reflecting early renal impairment likely linked to immune complex deposition and microvascular obstruction. Hepatic markers ALT, AST, GGT, total and direct bilirubin were also markedly raised, indicating hepatocellular injury and cholestasis. Total protein, albumin, and globulins were significantly higher in co-infected children, suggesting polyclonal B-cell activation and hypergammaglobulinemia driven by chronic immune stimulation. Among the biochemical markers, LDH, creatinine, and ALP exhibited high sensitivity and specificity in predicting organ dysfunction, while GGT, bilirubin, and total protein demonstrated high sensitivity but lower specificity. Receiver Operating Characteristic (ROC) analyses showed modest predictive value (AUC 0.43–0.69) for these markers in identifying renal and hepatic dysfunction. The findings suggest that combining hepatic and renal markers could enhance diagnostic accuracy in co-infected children. P. falciparum and HIV co-infection in children under five years significantly disrupts renal and hepatic function, reflecting compounded immune and metabolic stress. Elevated creatinine, bilirubin, and transaminases indicate potential for these markers to serve as adjunct diagnostic and prognostic tools in endemic areas. The study underscores the need to integrate biochemical assessment into pediatric malaria management, especially in HIV-prevalent regions. Routine monitoring of renal and hepatic function is recommended for timely identification of co-infected children at risk of severe outcomes. Further longitudinal and multi-center studies should investigate the mechanistic pathways underlying biomarker alterations and validate context-specific diagnostic thresholds for clinical use.

CHARACTERIZATION OF CASSAVA (Manihot esculenta Crantz) GERMPLASM IN KENYA

Wed, 01 Jan 2025 00:00:00 GMT

CHARACTERIZATION OF CASSAVA (Manihot esculenta Crantz) GERMPLASM IN KENYA NYAMWAMU, CHARLES NYARANG’O Cassava (Manihot esculenta Crantz) is a crucial income crop and staple food crop, providing substantial carbohydrates for millions globally and supporting small-scale farmers in Kenya. Due to incorrect characterization of the phenotypic and genetic materials available, the gene pool for cassava in Kenya are frequently overestimated or underestimated. Therefore, this study sought to characterize cassava germplasm in Kenya. Specific objectives were to; characterize and delimit cassava germplasm based on their phenotypic traits, investigate the genetic diversity among the cassava germplasm using molecular markers and also to determine the cyanide concentration levels in leaves, peels and pulp among cassava germplasm in Kenya. A total of 131 cassava accessions were collected from 7 major purposefully selected cassava growing Counties in Kenya. Each cassava accession was represented by a single plant. This plant was divided into 3- 10 pieces and planted in single rows. Plants from this main plot were collected and planted in three sites. In each plot, three rows of five plants were planted. Data collection on phenotypic traits was done at 3, 6, 9 and 12 months. Twenty-one qualitative and four quantitative phenotypic data were collected and subjected to multivariate analysis. At a statistical significance of p≤0.05, the data was subjected to cluster analysis and dendogram construction. From the main plot, apical leaf samples from 40 proportionately sampled accessions were taken for evaluation of genetic diversity and population structure using start-codon-targeted (SCoT) molecular markers. Cluster analysis and dendogram development was done to establish the accessions' genetic variability. A total of 32 samples were processed for cyanide content analysis using picrate paper and spectrophotometric methods. In a field survey, 32 cassava sample accessions were randomly collected from various farms in Migori County for cyanide determination. Phenotypically, a dendrogram generated categorized these accessions into four clusters with Cluster 1, 2, 3 and 4 containing 72.5%, 16.0%, 3.1%, and 8.4% of the genotypes, respectively. Out of the 25 phenotypic traits assessed, 11 principal components accounted for 71.58% of the genetic variation. A total of 119 fragments were amplified, with 89.9% being polymorphic, indicating moderate genetic diversity. The dendrogram grouped the accessions into two clusters at a 0.35 genetic similarity coefficient. Moderate genetic variation among the accessions was revealed by SCoT markers. The study also revealed significant variations in cyanide levels across different cassava parts and accessions. The spectrophotometric method recorded average cyanide levels of 5.89 mg/L, 7.42 mg/L and 8.20 mg/L in leaves, peels and pulps respectively while the picrate paper method showed 3.13 mg/L, 5.44 mg/L, and 7.97 mg/L. The highest cyanide concentration was found in Nyarkadera leaves (26.93 mg/L), Kazanzwara peels (17.82 mg/L) and Nyatanga pulps (26.93 mg/L). The lowest levels were in Nyatanga-002, Nyakanyamkago, and Kasukali leaves (0.40 mg/L), Kasukali peels (1.19 mg/L) and Mzungu pulps (0.40 mg/L). Moderate positive correlations (r=0.547 and r=0.570) between cyanide concentrations in leaves and peels, and a strong positive correlation (r=0.936) in pulps was established. Thus, cassava germplasm in Kenya exhibits moderate diversity, with molecular data revealing clearer differentiation among this germplasm. In addition, the germplasm shows significant cyanide variation necessitating integrated genetic and biochemical breeding approaches. Thus, these results may assist breeders and farmers in optimizing cassava germplasm utilization, ultimately contributing to food security.

MORPHOMERISTIC AND GENETIC CHARACTERIZATION OF Enteromius SPECIES (PISCES: CYPRINIDAE) FROM SELECTED RIVERS AND RESERVOIRS OF THE NORTH RIFT, KENYA

Mon, 01 Jan 2024 00:00:00 GMT

MORPHOMERISTIC AND GENETIC CHARACTERIZATION OF Enteromius SPECIES (PISCES: CYPRINIDAE) FROM SELECTED RIVERS AND RESERVOIRS OF THE NORTH RIFT, KENYA JEPLETING, HILDAH The Enteromius species of the family Cyprinidae, are known to have high genetic diversity and distinct population structure. They are widely distributed in rivers and reservoirs across Africa Because of the diversity in the group, accurated identification of species remains a big challenge, hampering their sustainable exploitation and management. The study was carried out to identify Enteromius species and perform the molecular characterization of select identified populations from the North Rift region, Kenya, a region where these species exist, but are poorly documented and therefore managed. Both morphomeristic and molecular techniques were used for species identification, while the D-loop region of the mitochondrial DNA was used to determine genetic diversity and population structure of populations. Sampling was carried out in man-made reservoirs and rivers across the region, from February to July 2018 using seine nets and an electrofisher. The captured fish were identified in the field using morphological characteristics, total length and standard length of each measured in cm and photographed. The fins were clipped and preserved in 90% ethanol for genetic analysis. Each fish sample was preserved in 10% formalin for laboratory analysis. Sixteen morphometric measurements and eleven meristic counts were done on each sample. The data was entered into Excel spreadsheet and then exported to PAST for Principle Component Analysis (PCA). Mann-whitney U test was used used to test for significance. Results on morphometric characteristics revealed clear separations of polygons of Enteromius species separating Enteromius species into four: Enteromius neumayeri, E. cercops, E. apleurogramma and E. paludinosus. The factor loadings analysis revealed that Standard Length (SL), Prepectoral Length (PPECL) and PrePelvic Length (PPELL) were the factors that clearly separated the four species. Principal component analysis (PCA) of the meristic data showed no clear separation of polygons of Enteromius species. However, the factor loadings established that mostly, the lateral line scales and caudal fin rays were significantly different within the four species. A total of 287 DNA sequences of the Cytochrome oxidase I region of mitochondrial DNA for species identification identified four fish species: Enteromius apleurogramma, E. cercops, E. neumayeri, and E. paludinosus. Enteromius neumayeri had seven clusters while E. apleurogramma had five clusters. Minimum spanning network showed two clusters for E. neumayeri and and one cluster for E. apleurogramma. Pairwise comparisons for FST values among E. neumayeri populations revealed significant differentiation in 27 out of 45 comparisons while in E. apleurogramma FST values were significantly different between the three sites, indicating that these populations were genetically differentiated. There was high genetic diversity of Enteromius species in North Rift selected rivers and reservoirs, with number of hapotypes ranging from 2 to 10, while haplotype diversity ranged from 0.1539 to 0.9082 Continual monitoring of Enteromius populations is essential to track changes of Enteromius species over time. Further studies should be conducted to determine the influence of environmental factors on the number of Enteromius species and their diversity in river and reservoir populations in North Rift region, Kenya which will help relevant bodies to develop population specific conservation strategies.