Department of Biological Sciences

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.

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

Mon, 01 Dec 2025 00:00:00 GMT

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

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

Wed, 01 Jan 2025 00:00:00 GMT

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.

Improving aquaculture productivity in Uasin Gishu County, Kenya: Addressing pathogens, water quality, and management challenges

Sat, 01 Mar 2025 00:00:00 GMT

Improving aquaculture productivity in Uasin Gishu County, Kenya: Addressing pathogens, water quality, and management challenges Mutai, E. Kipyegon; Ngeiywa, M.M.Moses; Liti, D. Aquaculture in Uasin Gishu County, Kenya, has grown significantly due to government support, favorable climatic conditions, and an increasing demand for fish as a protein source. However, fish farming in the region faces severe challenges from pathogenic parasites and microbes, which significantly impact fish health and aquaculture productivity. Poor water quality, overcrowded ponds, and agricultural runoff exacerbate the proliferation of pathogens, including protozoan parasites (Ichthyophthirius multifiliis), monogeneans (Gyrodactylus species), bacterial pathogens (Aeromonas hydrophila, Edwardsiella tarda), and fungal infections (Saprolegnia species). These pathogens cause diseases that lead to high mortality rates, reduced productivity, and economic losses. This review synthesizes current research on fish pathogens in Uasin Gishu, contextualizing the findings within regional and global frameworks, and identifies critical gaps in disease management. It also proposes strategies to mitigate disease prevalence, improve water quality, and enhance aquaculture sustainability.

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.

Enhancing fisheries productivity through improved fish pond management in Uasin Gishu County, Kenya: A comprehensive review

Tue, 01 Jul 2025 00:00:00 GMT

Enhancing fisheries productivity through improved fish pond management in Uasin Gishu County, Kenya: A comprehensive review Kosgei, J. Patricia; Liti, David M; Chemoiwa, Emily J.; Mutai, Edwin K. Aquaculture is increasingly recognized as a cornerstone of global food security and economic development. However, its potential remains underexploited in many developing regions, including Uasin Gishu County in Kenya. This review synthesizes local and global research on the challenges and opportunities for enhancing fisheries productivity in the county through improved pond management practices. By examining production systems, water quality variables, and nutritional management, this review presents practical strategies for sustainable intensification of aquaculture in the region. The findings underscore the need for coordinated efforts among stakeholders to unlock the full potential of aquaculture in Uasin Gishu County, positioning it as a viable pathway toward rural development and long-term food security. The recommendations focus on capacity building, resource access, policy support, and integrated farming approaches aimed at improving productivity, profitability, and environmental sustainability.

Influence of Water Quality on Growth Dynamics of Nile Tilapia (Oreochromis niloticus) in Uasin Gishu Aquaculture Systems

Mon, 01 Dec 2025 00:00:00 GMT

Influence of Water Quality on Growth Dynamics of Nile Tilapia (Oreochromis niloticus) in Uasin Gishu Aquaculture Systems Kosgei, J. Patricia; Liti, M. David,; Mutai, K. Edwin; Chemoiwa, J. Emily Aquaculture in Uasin Gishu County, Kenya, supports food security and livelihoods but faces challenges from unstable water quality affecting Nile tilapia (Oreochromis niloticus) growth. This study examined the relationship between water quality and fish growth across five farms representing earthen, tank, and raised liner systems from May 2023 to April 2024. Physico-chemical parameters—dissolved oxygen (DO), temperature, pH, chemical oxygen demand (COD), and biological oxygen demand (BOD)—were measured at three-hour intervals, while fish growth was monitored monthly. Data were analyzed using ANOVA, Tukey’s HSD, and multiple regression to assess water quality effects on growth. Temperature (21–23 °C) was below the optimal 25–30 °C range; pH (8–9) was acceptable; DO occasionally dropped below 3 mg/L; and COD (32–95 mg/L) and BOD (33–103 mg/L) indicated organic loading. Significant differences occurred among farms for temperature, DO, COD, and BOD. Growth parameters derived from the von Bertalanffy Growth Function showed the best performance in raised liner systems, with Cheplaskei Farm A recording the highest growth (L∞ = 36.78 cm; W∞ = 630.02 g). COD and BOD were the strongest predictors of maximum growth rate. The findings emphasize the need for stable water quality management to enhance O. niloticus productivity and ensure sustainable aquaculture in the region.