Department of Biological Sciences

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

2026-06-11T07:30:30Z

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.

EFFECT OF MULTIVITAMINS ON THE FERTILITY O F NEEM (Azadirachta indica) TREATED LABORATORY FEMALE ALBINO RATS ( Rattus norvegicus)

2026-06-11T06:45:00Z

EFFECT OF MULTIVITAMINS ON THE FERTILITY O F NEEM (Azadirachta indica) TREATED LABORATORY FEMALE ALBINO RATS ( Rattus norvegicus) MINAGE, ZAINAB Azadirachta indica (Neem) is a widely used medicinal plant valued for its therapeutic properties, particularly in regions with limited access to conventional healthcare. It has been reported to exert antifertility effects by altering reproductive hormones in animals, yet the potential modulatory effects of multivitamin supplementation remain unclear. This study investigated the dose-dependent impact of neem leaf extract on reproductive hormones in female albino rats and assessed whether multivitamins could mitigate these effects. Mature neem leaves were collected from Christ Is The Answer Ministries (CITAM) Kisumu church compound and the University of Eldoret. Forty female albino rats sourced from Maseno University were acclimatized for one month under controlled conditions (22–25°C, 12-hour light/dark cycle). Twenty-four healthy, sexually mature rats were randomly assigned to eight treatment groups. Ethanol-extracted neem preparations were administered orally, with and without multivitamins, for 28 days. Post-treatment, blood serum samples were analyzed for follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estrogen using ELISA at Moi Teaching and Referral Hospital. Data were analyzed using one-way ANOVA, Tukey’s post hoc test, and regression analysis, with significance set at p<0.05. Results showed dose-dependent suppression of reproductive hormones by neem. FSH decreased from 8.27±0.35 in the negative control to 3.27±0.21 ng/mL in the highest neem dose (100 mg/kg), which was not significantly different in the positive control group (3.03±0.15 ng/mL). LH declined from 6.17±0.35 ng/mL in the negative control to 2.90±0.20 ng/mL (Neem100), versus 2.57±0.21 ng/mL in the positive control group. Estrogen levels fell from 52.59±2.55 pg/mL in the negative control to 13.53±1.25 pg/mL in Neem100, while controls and positive control had comparable levels (50.97±1.36 pg/mL). Multivitamin supplementation (done at the dosage of one pill per 70kg of body weight per day) partially reversed these suppressive effects of neem, increasing FSH to 5.87±0.15 ng/mL, LH to 5.13±0.15 ng/mL, and estrogen to 54.33±1.17 pg/mL in the Neem100+MV group. One-way ANOVA revealed highly significant differences among treatment groups for FSH (F 0.05(4,10) =181.67, p<0.0001), LH (F0.05(4,10) =88.24, p<0.0001), and estrogen (F0.05(4,10) =306.53, p<0.0001). Correlation analysis showed a very strong positive correlation between FSH and LH (r=0.992, p<0.0001), while estrogen exhibited weak, non-significant correlations with FSH and LH. In conclusion, neem leaf extract exerts potent contraceptive effects through dose-dependent suppression of reproductive hormones, with multivitamin supplementation partially mitigating these effects. These findings highlight the importance of understanding interactions between traditional herbal remedies and nutritional supplements and warrant further investigation into long-term outcomes and mechanisms.

IMPACT OF WATER QUALITY AND ANTIMICROBIAL RESISTANCE ON THE PATHOGENS OF FARMED FISH (Oreochromis niloticus) IN UASIN GISHU COUNTY, KENYA

2026-06-10T11:59:30Z

IMPACT OF WATER QUALITY AND ANTIMICROBIAL RESISTANCE ON THE PATHOGENS OF FARMED FISH (Oreochromis niloticus) IN UASIN GISHU COUNTY, KENYA MUTAI, EDWIN Aquaculture is increasingly recognized as a sustainable strategy for meeting the rising global demand for protein, particularly in developing countries such as Kenya where capture fisheries are under pressure. Despite its potential, aquaculture growth is hindered by poor water quality and the emergence of microbial and parasitic infections that com- promise fish health, productivity, and ultimately farmer livelihoods. This study evaluated the impact of water quality on the diversity and prevalence of microbial and parasitic or- ganisms in cultured fish, and examined the antibiotic susceptibility of bacterial isolates from aquaculture systems in Uasin Gishu County, Kenya. A longitudinal survey was conducted from May 2023 to April 2024 across five farms and thirteen ponds. Monthly assessments of water quality parameters (temperature, pH, dissolved oxygen, turbidity, and nutrient concentrations) were performed following standard APHA protocols. Con- currently, fish samples were collected for microbial and parasitic screening. Bacteria were isolated through culture-based methods and identified morphologically and bio- chemically in accordance with Bergey’s Manual, while parasites were identified micro- scopically. Antibiotic susceptibility testing employed the Kirby–Bauer disc diffusion method using commonly applied antibiotics. Statistical analyses included chi-square tests for associations between infection prevalence and host/seasonal variables, one-way ANOVA to evaluate differences in water quality parameters, and logistic regression to determine significant predictors of infection. A total of 154 bacterial isolates were recov- ered, with Escherichia coli (34.8%) and Pseudomonas aeruginosa (21.7%) being most prevalent. Parasitic infestations, primarily protozoans and helminths, were concentrated in gills (p < 0.001) and showed significant seasonal variation, with peak prevalence during warmer months. Logistic regression revealed that organ type, bacterial species, and water quality parameters were significant predictors of infection (p < 0.05). Poor water quality, marked by low dissolved oxygen and elevated ammonia, was strongly associated with increased pathogen load. Importantly, several bacterial isolates exhib- ited multi-drug resistance, raising concerns about environmental contamination and the spread of antimicrobial resistance.This study provides critical insights into the complex interactions between water quality, pathogen diversity, and fish health in aquaculture systems. It demonstrates that disease occurrence is not random but is strongly influ- enced by environmental conditions and farming practices. The findings highlight the need for routine water quality monitoring, improved pond management, and the adop- tion of biosecurity measures to reduce infection risks. Furthermore, the detection of resistant bacteria underscores the urgency of promoting responsible antibiotic use to safeguard fish health and protect public health. Overall, the study emphasizes an inte- grated approach that combines environmental stewardship, sustainable husbandry prac- tices, and prudent health management to ensure the long-term viability of aquaculture in Uasin Gishu County and similar settings.

GENETIC DIVERSITY, CROSS PATHOGENICITY AND CONTROL OF BACTERIAL BLIGHT OF COWPEA USING BACILLUS SP. AND SELECTED BOTANICALS

2026-06-08T10:02:22Z

GENETIC DIVERSITY, CROSS PATHOGENICITY AND CONTROL OF BACTERIAL BLIGHT OF COWPEA USING BACILLUS SP. AND SELECTED BOTANICALS KIRAREI, EZRA Cowpea (Vigna unguiculata (L.) Walp.) is an economically important crop cultivated both for domestic and commercial purposes. It is one of the most resilient crops suited to arid and semi-arid areas. Cowpea production is affected by several diseases caused by phytopathogens. Bacterial blight caused by Xanthomonas axonopodis pv. vignicola has been reported in many cowpea producing areas causing reduction in both quality and quantity of the harvestable leaves and grains. However, in Kenya, the disease occurrence status has not been exhaustively documented, similar to the causal pathogen characterization and management using biological control agents and botanicals. This research conducted field surveys in farms from six counties representing different zones to analyse the disease occurrence levels. The identification of the pathogen was done by morphological and biochemical features as well as by analysis of 16S rDNA and its genetic diversity was determined using inter-simple sequence repeat markers. The pathogen cross pathogenicity was tested by inoculating other legumes (beans, soya bean, green gram, garden peas and lentils) with the most virulent isolate. Dual culture and inverted plate techniques were used to test bio-efficacy of the biological control agents and botanical extracts. Xanthomonas axonopodis pv. vignicola was confirmed as the causal pathogen in 48 farms out of 80 farms. The mean disease incidence was 44.89% across the sampled sites, being highest in Kakamega County (50.49%) and the least in Uasin Gishu County (33.57%). Xanthomonas axonopodis pv. vignicola isolates displayed slight variance in morphological and cultural characteristics on nutrient agar. The biochemical tests and analysis by blasting of sequence from 16S rDNA region confirmed Xanthomonas axonopodis pv. vignicola as the causal agent. The polymorphic information content ranged from 0.2384 to 0.4486, indicating genetic variations which was strongly correlated with the differences within populations. The pathogen, infection was observed in all the cowpea varieties tested and cross infection on soya bean and lentils. The percentage disease severity ranged between 25.83% to 51.67%, which was significantly higher in cowpea varieties. The bio-efficacy of selected bio-agents showed varying levels of percentage inhibition against X. axonopodis pv. vignicola, depending on the method and the duration of exposure. Bacillus subtilis displayed the highest antibacterial activity between 68.33% and 87.79% by dual culture technique and between 38.33% to 71.33% in inverted plate method over seventy-two hours. Bacillus amyloliquefaciens showed a statistically significant antibacterial activity between 45.00% and 76.12% in dual culture technique and between 45.00% and 73.89% by inverted plate method. Cyprofloxacin the antibiotic used for positive check, ethanolic extracts of neem, garlic and ginger inhibited X. axonopodis pv. vignicola by 56.3 mm, 38.5 mm, 30.8 mm and 25.0 mm respectively, but no potency was noted for Salvia nilotica. Genetic variations of Xanthomonas axonopodis pv. vignicola was noted from different regions of Kenya. This study showed that B. subtilis and B. amyloliquefaciens, neem, garlic and ginger extracts are useful biocontrol options in management of X. axonopodis pv. vignicola and therefore can be recommended for integration in the management of this pathogen in cowpea.

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

2026-06-03T09:02:35Z

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

2026-06-03T08:34:48Z

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

2026-06-03T07:25:46Z

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.

Genetic diversity and population structure of Trichilia emetica Vahl in western Kenya using ISSR markers

2026-05-28T09:00:35Z

Genetic diversity and population structure of Trichilia emetica Vahl in western Kenya using ISSR markers Sirma, Elias; Nyongesa, Benson; Dangasuk, Otto; Andiego, Ken Loss of habitat and land-use changes can alter genetic variation in tropical trees, un- derscoring the need for molecular information to support species conservation. Trichilia emetica is an indigenous multipurpose species in Kenya that is widely used in restora- tion programs, yet its genetic variability remains insufficiently documentedl. This study determined the genetic diversity and structure of T. emetica populations in western Ke- nya using 15 Inter-Simple Sequence Repeat (ISSR) markers. A total of 171 DNA frag- ments were produced, of which 94.65% were polymorphic. The overall, gene diversity was moderate (He=0.15; I=0.22), and diversity levels varied across populations. Rela- tively higher diversity was detected in Nandi (He=0.24; %P=78.31)) and Kakamega (He=0.18; %P=75.00), whereas Kisumu and Siaya showed comparatively lower esti- mates (He=0.10; %P=31.25%). Analysis of molecular variance (AMOVA) showed that most variation occurred within populations (65%) with moderate among population differ- entiation (ΦST=0.35, p<0.001). Six populations were grouped into three genetic clusters. These results provide a baseline for integrating genetic information into management deci- sions, including prioritizing relatively diverse populations for seed sourcing and applying targeted enrichment strategies in areas showing reduced diversity.

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

2026-05-09T12:27:12Z

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 sensitivity of bacterial isolates from farmed fish in Uasin Gishu County, Kenya

2026-04-22T09:02:36Z

Antibiotic sensitivity of bacterial isolates from farmed fish in Uasin Gishu County, Kenya Mutai, Edwin Kipyegon; Ngeiywa, Moses; Liti, Davi; Kosgei, Patricia Tarus The study was conducted with the aim of investigating the antibiotic sensitivity of bacterial isolates from farmed fish to commonly used antibiotics in Uasin Gishu County, Kenya, a region experiencing rapid aquaculture growth. Despite no direct antibiotic use in local fish farms, concerns over antimicrobial resistance (AMR) have emerged due to indirect exposure from integrated livestock-crop systems. A longitudinal study design was used to evaluate microbial infestations. Over a 12-month period, 468 fish samples from 13 ponds across five farms were examined, yielding 154 bacterial isolates representing 12 species, including Escherichia coli, Aeromonas species, Pseudomonas aeruginosa, Vibrio species and Flavobacterium columnare. Antibiotic susceptibility testing was conducted using six commonly used antibiotics: amoxicillin (AMX), erythromycin (ERY), cotrimoxazole (CT), doxycycline (DO), streptomycin (STR), and ciprofloxacin (CIP). Statistical analysis using Fisher’s exact test revealed significant interspecies resistance variation for AMX and ERY (p = 0.0005), while the other antibiotics showed consistent susceptibility across species. Principal Component Analysis (PCA) and heatmap analyses confirmed AMX and ERY as the primary drivers of resistance variation, particularly in E. coli, Aeromonas hydrophila and Streptococcus species, which showed resistance rates above 35 to 50%. Conversely, CIP, DO, and STR exhibited high effectiveness, with over 80% susceptibility in most isolates. The results suggest that indirect exposure through runoff, manure application, and effluent from livestock farming is likely promoting resistance. The findings of this study reveal that antibiotic use in surrounding agricultural systems, although not directly applied to fish, may be contributing to the development of resistant bacterial populations within aquaculture environments. This highlights a critical link between terrestrial and aquatic ecosystems, reinforcing the need for a One Health approach to antimicrobial stewardship. The results emphasize the importance of regular monitoring of antibiotic resistance patterns and adopting tailored antibiotic selection based on local data. Furthermore, the study underscores the necessity of improved waste management, enhanced farmer education, and strengthened biosecurity practices to curb the spread of resistant bacteria. Continued surveillance of antibiotic resistance in aquaculture is essential to ensure food safety, safeguard public health, and promote the sustainability of fish farming systems.