Department of Biological and Environmental Sciences

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Reorganization of cytoskeleton during surfactant secretion in lung type II cells: a role of annexin II
(Elsevier, 2003) Singh, Taran K.; Abonyo, B. O.; Narasaraju, Telugu A.
The secretion of lung surfactant requires the movement of lamellar bodies to the plasma membrane through cytoskeletal barrier at the cell cortex. We hypothesized that the cortical cytoskeleton undergoes a transient disassembly/reassembly in the stimulated type II cells, therefore allowing lamellar bodies access to the plasma membrane. Stabilization of cytoskeleton with Jasplakinolinde (JAS), a cell permeable actin microfilament stabilizer, caused a dose-dependent inhibition of lung surfactant secretion stimulated by terbutaline. This inhibition was also observed in ATP-, phorbol 12-myristate 13-acetate (PMA)- or Ca2 + ionophore A23187-stimulated surfactant secretion. Stimulation of type II cells with terbutaline exhibited a transient disassembly of filamentous actin (F-actin) as determined by staining with Oregon Green 488 Phalloidin. The protein kinase A inhibitor, H89, abolished the terbutaline-induced F-actin disassembly. Western blot analysis using anti-actin and anti-annexin II antibodies showed a transient increase of G-actin and annexin II in the Triton X-100 soluble fraction of terbutaline-stimulated type II cells. Furthermore, introduction of exogenous annexin II tetramer (AIIt) into permeabilized type II cells caused a disruption in the cortical actin. Treatment of type II cells with N-ethylmaleimide (NEM) resulted in a disruption of the cortical actin. NEM also inhibited annexin II’s abilities to bundle F-actin. The results suggest that cytoskeleton undergoes reorganization in the stimulated type II cells, and annexin II tetramer plays a role in this process. D 2003 Elsevier Inc. All rights reserved.
Syntaxin 2 and SNAP-23 are required for regulated surfactant secretion
(2014) Abonyo, B. O.; Wang, Pengcheng; Lin Liu
The secretion of lung surfactant in alveolar type II cells is a complex process involving the fusion of lamellar bodies with the plasma membrane. This process is somewhat different from the exocytosis of hormones and neurotransmitters. For example, it is a relatively slower process, and lamellar bodies are very large vesicles with a diameter of approximately 1 microm. SNARE proteins are the conserved molecular machinery of exocytosis in the majority of secretory cells. However, their involvement in surfactant secretion has not been reported. Here, we showed that syntaxin 2 and SNAP-23 are expressed in alveolar type II cells. Both proteins are associated with the plasma membrane, and to some degree with lamellar bodies. An antisense oligonucleotide complementary to syntaxin 2 decreased its mRNA and protein levels. The same oligonucleotide also inhibited surfactant secretion, independent of secretagogues. A peptide derived from the N-terminus of syntaxin 2 or the C-terminus of SNAP-23 significantly inhibited Ca(2+)- and GTPgammaS-stimulated surfactant secretion from permeabilized type II cells in a dose-dependent manner. Furthermore, introduction of anti-syntaxin 2 or anti-SNAP-23 antibodies into permeabilized type II cells also inhibited surfactant release. Our results suggest that syntaxin 2 and SNAP-23 are required for regulated surfactant secretion.
Modulation of eotaxin-3 (CCL26) in alveolar type II epithelial cells
(2007)
Airway epithelial inflammation associated with emphysema, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and asthma is regulated in part by alveolar type II cell chemokine signaling. Data suggest that resident lung cells use CCR3, CCR5 and CCR2 chemokine receptor/ligand systems to regulate the profile of leukocytes recruited in disease-associated inflammatory conditions. Thus studies were designed to test whether alveolar type II cells possess a Th1-activated CCR5-ligand system that modulates the Th2-activated CCR3/eotaxin-2 (CCL24), eotaxin-3 (CCL26) chemokine systems. The A549 alveolar type II epithelial-like cell culture model was used to demonstrate that alveolar type II cells constitutively express CCR5 which may be upregulated by MIP-1alpha (CCL3) whose expression was induced by the Th1 cytokines IL-1beta and IFN-gamma. Selective down-regulation of CCL26, but not CCL24, was observed in CCL3 and IL-4/CCL3 stimulated cells. Down-regulation was reversed by anti-CCR5 neutralizing antibody treatment. Thus, one mechanism through which Th1-activated CCCR5/ligand pathways modulate Th2-activated CCR3/ligand pathways is the differential down-regulation of CCL26 expression. Results suggest that the CCR3 and CCR5 receptor/ligand signaling pathways may be important targets for development of novel mechanism-based adjunctive therapies designed to abrogate the chronic inflammation associated with airway diseases.
Post-transcriptional silencing of CCR3 downregulates IL-4 stimulated release of eotaxin-3 (CCL26) and other CCR3 ligands in alveolar type II cells
(2008) Taka, Equar; Errahali, Younes J.; Abonyo, B. O.; Heiman, Ann S.
Trafficking and inflammation in airway diseases are, in part, modulated by members of the CC chemokine family, eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26), which transduce signals through their CCR3 receptor. In this context, we hypothesized that transfecting alveolar type II epithelial cells with CCR3-targeted siRNA or antisense (AS-ODN) sequences will downregulate cellular synthesis and release of the primary CCR3 ligands CCL26 and CCL24 and will modulate other CCR3 ligands. The human A549 alveolar type II epithelium-like cell culture model was used for transfection and subsequent effects on CCR3 agonists. siRNAs were particularly effective. PCR showed a 60–80% decrease in mRNA and immunoblots showed up to 75–84% reduction of CCR3 in siRNA treated cells. CCR3-siRNA treatments reduced IL-4 stimulated CCL26 release and constitutive CCL24 release by 65% and 80%, respectively. Release of four additional CCR3 agonists RANTES, MCP-2, MCP-3 and MCP-4 was also significantly reduced by CCR3-siRNA treatments of the alveolar type II cells. Activation of eosinophils, assessed as superoxide anion generation, was reduced when eosinophils were treated with supernatants of A549 cells pretreated with CCR3-targeted siRNAs or AS-ODNs. Collectively, the data suggest that post-transcriptional regulation of CCR3 receptors may be a potential therapeutic approach for interrupting proinflammatory signaling.
Cytokine-stimulated human lung alveolar epithelial cells release eotaxin-2 (CCL24) and eotaxin-3 (CCL26)
(Mary Ann Liebert, Inc, 2005) Heiman, Ann S.; Abonyo, B. O.; Darling-Reed, Selina F.; Alexander, Marilyn S.
Asthma is a complex inflammatory disease characterized by a prolonged underlying airway inflammation resulting from cytokine-orchestrated signaling between many types of cells, including airway epithelial cells. Trafficking, recruitment, and activation of cells in airway disease are, in part, modulated by the newly discovered CC subfamily of chemokines, eotaxin (CCL11), eotaxin-2 (CCL24) and eotaxin-3 (CCL26), which transduce signals by acting as agonists for the CCR3 receptor. The specific cytokine stimuli that modulate CCL24 and CCL26 release in airway epithelial cells remain poorly defined. Thus, human 549 alveolar type II epithelium-like cells were stimulated singly and with combinations of 1–100 ng/ml tumor necrosis-factor- (TNF- ), interleukin-1 (IL-1), and IL-4, cytokines known to be elevated in the airways of asthmatics. Release of CCL11, CCL24, and CCL26 was quantified by ELISA, and CCR3 receptors monitored by immunocytochemistry and FACS analysis. Results suggest that epithelial cells release CCL11 during the first 24 h of stimulation, in contrast to a significant increase in CCL24 and CCL26 release after 24–48 h of stimulation. Differential release of the eotaxins in response to cytokine combinations was noted. The alveolar type II epithelial cells were found to possess constitutive CCR3 receptors, which increased after proinflammatory cytokine stimulation. The airway epithelium CCR3 receptor/eotaxin ligand signal transduction system may be an important target for development of novel mechanism-based adjunctive therapies designed to interrupt the underlying chronic inflammation in allergic and inflammatory disorders.
CCL26-targeted siRNA treatment of alveolar type II cells decreases expression of CCR3-binding chemokines and reduces eosinophil migration: implications in asthma therapy
(2009) Errahali, Younes J.; Taka, Equar; Abonyo, B. O.; Heiman, Ann S.
The underlying infl ammation present in chronic airway diseases is orchestrated by increased expression of CC chemokines that selectively recruit leukocyte populations into the pulmonary system. Human CCL26 signals through CC chemokine receptor 3 (CCR3), is dramatically upregulated in challenged asthmatics, and stimulates recruitment of eosinophils (EOSs) and other leukocytes. CCL26 participates in regulation of its receptor CCR3 and modulates expression of a variety of chemokines in alveolar type II cells. Utilizing the A549 alveolar type II epithelial cell culture model, we carried out studies to test the hypothesis that CCL26-siRNA treatment of these cells would ameliorate Th2-driven release of the eotaxins and other CCR3 ligands that would, in turn, decrease recruitment and activation of EOSs. Results demonstrate that CCL26-siRNA treatments decreased interleukin4-induced CCL26 and CCL24 expression by > 70%. CCL26-directed small-interfering RNA (siRNA) treatments signifi cantly decreased release of CCL5 (RANTES), CCL15 (MIP-1δ), CCL8 (MCP-2), and CCL13 (MCP-4). In bioactivity assays it was shown that EOS migration and activation were reduced up to 80% and 90%, respectively, when exposed to supernatants of CCL26-siRNA-treated cells. These results provide evidence that CCL26 may be an appropriate target for development of new therapeutic agents designed to alleviate the underlying infl ammation associated with chronic diseases of the airways.
Characterization of -soluble n-ethylmaleimide–sensitive fusion attachment protein in alveolar type ii cells implications in lung surfactant secretion
(2002) Abonyo, B. O.; Wang, Pengcheng; Narasaraju, Telugu A.; Rowan III, William H.; Zimmerman, Un-Jin; Lin Liu
N-ethylmaleimide–sensitive fusion protein (NSF) and soluble NSF attachment protein (α-SNAP) are thought to be soluble factors that transiently bind and disassemble SNAP receptor complex during exocytosis in neuronal and endocrine cells. Lung surfactant is secreted via exocytosis of lamellar bodies from alveolar epithelial type II cells. However, the secretion of lung surfactant is a relatively slow process, and involvement of SNAP receptor and its cofactors (NSF and α-SNAP) in this process has not been demonstrated. In this study, we investigated a possible role of α-SNAP in surfactant secretion. α-SNAP was predominantly associated with the membranes in alveolar type II cells as determined by Western blot and immunocytochemical analysis using confocal microscope. Membrane-associated α-SNAP was not released from the membrane fraction when the cells were lyzed in the presence of Ca2+ or Mg2+ATP. The alkaline condition (0.1 M Na2CO3, pH 12), known to extract peripheral membrane proteins also failed to release it from the membrane. Phase separation using Triton X-114 showed that α-SNAP partitioned into both aqueous and detergent phases. NSF had membrane-bound characteristics similar to α-SNAP in type II cells. Permeabilization of type II cells with β-escin resulted in a partial loss of α-SNAP from the cells, but cellular NSF was relatively unchanged. Addition of exogenous α-SNAP to the permeabilized cells increased surfactant secretion in a dose-dependent manner, whereas exogenous NSF has much less effects. An α-SNAP antisense oligonucleotide decreased its protein level and inhibited surfactant secretion. Our results suggest a role of α-SNAP in lung surfactant secretion.
Autoregulation of ccl26 synthesis and secretion in a549 cells: a possible mechanism by which alveolar epithelial cells modulate airway inflammation
(2005) Abonyo, B. O.; Alexander, M. S. Alexander; Heiman, A. S.
Abonyo, B. O., M. S. Alexander, and A. S. Heiman. Autoregulation of CCL26 synthesis and secretion in A549 cells: a possible mechanism by which alveolar epithelial cells modulate airway inflammation. Am J Physiol Lung Cell Mol Physiol 289: L478 –L488, 2005. First published April 29, 2005; doi:10.1152/ajplung.00032.2005.— Eotaxins (CCL11, CCL24, CCL26) originating from airway epithelial cells and leukocytes have been detected in bronchoalveolar lavage of asthmatics. Although the alveolar epithelium is the destination of uncleared allergens and other inflammatory products, scanty information exists on their contribution to the generation and regulation of the eotaxins. We envisioned a state whereby alveolar type II cells, a known source of other inflammatory proteins, could be involved in both the production and regulation of CCL24 and CCL26. Herein, we demonstrated that all three eotaxins are constitutively expressed in A549 cells. IL-4 and IL-13 stimulated a concentration-dependent secretion of CCL24 and CCL26. The cytokines did not act synergistically. Cycloheximide and actinomycin D abrogated IL-4- and IL13-dependent CCL26 but not CCL24 secretion. Both IL-13 and IL-4 stimulated CCL26 synthesis that was inhibited in a concentrationdependent manner by CCL26 but not CCL24. Only CCL26 reduced expression of CCR3 receptors by 30 – 40%. On the other hand, anti-CCR3 pretreatment reduced IL-4 IL-13-dependent CCL26 secretion, implying autoregulation. A CCR3-specific antagonist (SB328437) significantly decreased IL-4-dependent synthesis and release of CCL26. Eosinophils treated with medium from IL-4-stimulated A549 cells preincubated with anti-CCL26 showed a marked decrease of superoxide anion production compared with anti-CCL24 treated. These results suggest that CCL26 is a major eotaxin synthesized and released by alveolar epithelial cells and is involved in autoregulation of CCR3 receptors and other eotaxins. This CCL26-CCR3 ligandreceptor system may be an attractive target for development of therapeutics that limits progress of inflammation in airway disease
Biodegradation of carbofuran in soils within Nzoia River Basin, Kenya
(Journal of Environmental Science and Health, 2015-04-06) Onunga, Daniel O.; Owino, Isaac; Ngigi, Anastacia; Osogo, Aggrey; Orata, Francis; Getenga, Zachary; were, Hassan
Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) has been used within the Nzoia River Basin (NRB), especially in Bunyala Rice Irrigation Schemes, in Kenya for the control of pests. In this study, the capacity of native bacteria to degrade carbofuran in soils from NRB was investigated. A gram positive, rod-shaped bacteria capable of degrading carbofuran was isolated through liquid cultures with carbofuran as the only carbon and nitrogen source. The isolate degraded 98% of 100-μg mL−1 carbofuran within 10 days with the formation of carbofuran phenol as the only detectable metabolite. The degradation of carbofuran was followed by measuring its residues in liquid cultures using high performance liquid chromatography (HPLC). Physical and morphological characteristics as well as molecular characterization confirmed the bacterial isolate to be a member of Bacillus species. The results indicate that this strain of Bacillus sp. could be considered as Bacillus cereus or Bacillus thuringiensis with a bootstrap value of 100% similar to the 16S rRNA gene sequences. The biodegradation capability of the native strains in this study indicates that they have great potential for application in bioremediation of carbofuran-contaminated soil sites.
Antimicrobial Coumarins from the Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes), from Kenya
(International Journal of Medicinal Mushrooms, 2016-01-01) Baraza, Lilechi D.; Wekesa, Wekesa; Korir, Cheruiyot Jackson; Juma, Fredrick B.; Ochieno, Dennis; Wairimu, Kamau R.; Osogo, Aggrey; Heydenreich, Matthias
Pleurotus ostreatus has been widely used as food because of its nutritional and medicinal properties. These have been attributed to the presence of macronutrients, minerals, vitamins, and amino acids, among other secondary metabolites. There are, however, few reports on the antimicrobial activities of different classes of purified compounds from P. ostreatus. This led to the current study, the objective of which was to chemically characterize the antibiotic activities of P. ostreatus against selected human pathogenic bacteria and endophytic fungi. Chemical structures were determined using spectroscopic methods and by comparison with values of related structures reported in the literature. Pure compounds from P. ostreatus were tested in vitro against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and endophytic fungi (Pencillium digitatum and Fusarium proliferatum). A new compound, (E)-5,7-dimethoxy-6-(3-methylbuta-1,3-dienyl)-2H-chromen-2-one (5-methoxy-(E)-suberodiene) (compound 2), along with ergosterol (compound 1) and 5,7-dimethoxy-6-(3-methylbut-2-enyl)-2H-chromen-2-one (toddaculin; compound 3), were isolated from the fruiting bodies of P. ostreatus. The growth of S. aureus, F. proliferatum, and P. digitatum colonies was inhibited in media containing compound 2, with minimum inhibitory concentrations closely comparable to those of conventional antibiotics.
Spatial modeling of sorghum (sorghum bicolor) growing areasin Kenyan arid and semi-arid lands
(Elixirpublishers : Agriculture, 2014-01-10) Kigen, Charles; Ochieno, Dennis; Muoma, John; Shivoga, William; Konje, Martha; Onyando, Zedekiah; Soi, Benard; Makindi, Stanley; Kisoyan, Philip; Mironga, John
Sorghum (Sorghum bicolor) is an important African cereal crop and is listed among Africa’s lost crops but is now gaining popularity as other cereals are declining in production due to climatic change. To promote food security, many researchers and policy makers are shifting the focus on production of sorghum. In Kenya, sorghum is primarily grown in ASALs whose suitability is climatic factors but the extent is not known. This paper modeled the potential sorghum suitable areas of current and the years 2050 and 2080 climatic periods. The sorghum location data were downloaded from GENESYS and Kenya Agricultural Research Institute while climate data was from world climate database website. Analysis was done using Maxent and DIVA-GIS softwares. The model generated an excellent AUC of 0.97 and the suitable areas in the future are shown to expand in both 2050 and 2080 climatic periods though not in same magnitude. The main variables contributing more than 10 % of change in suitability areas in decreasing order are precipitation of wettest period, temperature seasonality (STD * 100), precipitation of warmest quarter, and precipitation of driest month. The generated information will guide the policy makers and stakeholders in making informed decisions with regard to the efforts of re-introduction and promotion of sorghum production in ASALs.
Effects of N and K fertilization of sugarcane (Saccharum oficinarum) on acrisols in western Kenya
(Elixirpublishers : Agriculture, 2014-01-01) Mutonyi, J.; Shibairo, Solomon .I.; Chemining’wa, G.N.; Olubayo, F.O.; Nyongesa, Hillary; Konje, Martha
Sugarcane fertilization in Kenyan plantations is largely concentrated on Nitrogen and Phosphorus. Use of Potassium, secondary nutrients and micronutrients is altogether missing. Recent soil analysis results indicate that soils in the Mumias Sugar zone of western Kenya that accounts for 50-60 % of national production are K- deficient. In examining the quality factor in sugarcane payment systems as envisaged in recent legislation, adoption of balanced nutrition by inclusion of K would help improve sugar cane productivity and enhance sugar recovery. This paper reports the effect of K, N and their interaction on sugarcane yield and juice quality on acrisols. Four experiments were established in several locations from 2009-2011. The treatments included a factorial combination of four rates of K at 0, 60, 120 and 180 kg/ha K2O and four rates of N at 0, 46, 92 and 138 kg/ha N. Recommended basal phosphate was included in every plot at 92 kg/ha P2O5. Each experiment was harvested after 18 months of growth. Results showed significant responses to K and N. Agronomic efficiency was higher in plots supplied with K along with N. Nitrogen and K2O application rates that produced optimum cane yields were: N = 46kg/ha and K2O = 60 kg/ha; however, economically profitable rates were N = 46-92 kg/ha and K2O at 60 kg/ha. Productivity gains did not offset costs when rates were higher than 120 kg/ha of K2O and 138 kg/ha of N. The results imply that the inclusion of K in the sugar cane fertilization regime at Mumias will be beneficial. An initial rate of 60kg/ha K2O (2 bags of 50 kg muriate of potash is recommended on soils with K-deficiency. There were strong indications that with K fertilization the current N recommendation of 120 – 150 kg N/h
Sugarcane response to liming, manuring and inorganic fertilizers on acid acrisols in Western Kenya
(International Journal of Recent Scientific Research, 2014-01-01) Mutonyi, J.; Shibairo, Solomon .I.; Chemining’wa, G.N.; Olubayo, F.M.; Kenya, N.C.O.; Nyongesa, Hillary
Effects of agricultural lime, organic manure and selected inorganic fertilizers on sugarcane growth, yield and quality were determined in four trials conducted from 2009-2011 on acid acrisols in western Kenya. Predominantly grown sugarcane variety CO 945 was used in all experiments that were laid out in a randomized complete block design with three replications. The treatments comprised absolute control (no manure, no fertilizer), compost (18 t/ha), compost (18 t/ha+100 kg/ha diammonium phosphate (DAP) + 100 kg/ha Urea), standard practice (200 kg DAP + 200 kg Urea), agricultural lime (3 t/ha + 200 kg/ha DAP + 200 kg/ha Urea), agricultural lime (3 t/ha + 100 kg/ha DAP + 100 kg/ha Urea), Mavuno NPK (350 kg/ha + 200 kg/ha Urea) and Single Super Phosphate (SSP 450 kg/ha + 200 kg/ha Urea). Soil analysis results generally indicated low levels of pH, total nitrogen, phosphorus, potassium, calcium, magnesium, organic carbon and C.E.C in all sites. The soils were classified as acrisols with sandy clay, clay loam and sandy clay loam texture and high bulk density in all sites. Emergence, tillering, stalk number, height, inter-node length, cane and sugar yields differed significantly (p < 0.05) among the treatments in all locations. Higher cane and sugar yields were consistently recorded in treatments where agricultural lime and compost were included. There was no difference in yield between treatments that received full or half dose of the recommended Nor P along with the lime and compost amendments. Juice quality was highest in the SSP+Urea treatment ranging from 13.58 - 14.43 % Pol and lowest in the compost treatment ranging from 11.43- 13.37 % Pol. Smut incidence was notable in the compost and control treatments. Agronomic efficiency was highest in treatments where compost and agricultural lime were included, ranging from 90.3 to 481.5 kg sugarcane/kg nutrient. Highest net returns and value cost ratios were also recorded in treatments with compost and agricultural lime. Results of this study clearly demonstrated that utilization of agricultural lime and organic compost along with inorganic fertilizers improved sugarcane yield with potential benefits of reduced dosage of N and P to 50% of the local recommendation.
The impacts of human activities on tree species richness and diversity in Kakamega Forest, Western Kenya
(Academic Journals : International Journal of Biodiversity and Conservation, 2014-06-01) Vuyiya, Esther; Konje, Martha; Tsingalia, Harrison; Obiet, Leonard; Kigen, Charles; Wamalwa, Stella; Nyongesa, Humphrey
Tropical rain forests are species rich ecosystems that are being depleted at very high rates through human encroachment. Kakamega forest is one of the heavily fragmented and disturbed tropical rain forests due to the high human population densities that surround the forest. The purpose of this study was to investigate the impact of human activities on tree species richness, diversity, canopy surface area and seedling density in Kakamega forest. The study was conducted in four sites within Kakamega forest: Handidi, Lukusi, Isecheno and KWS as a control site. The data was collected between June and December, 2011. Vegetation sampling was done in randomly selected sites within each study site using belt transects and quadrants. Within each transect, the number of tree species and seedlings were counted and the intensity of human disturbances assessed. Vegetation data were analyzed by two-way analysis of variance. Correlation and regression analysis were done between dependent and independent variables. Simpson’s diversity index was used to calculate tree species diversity in each study site. There were significant differences between species diversity, richness, canopy surface area and seedling density with distance from the forest edge. The study showed that there was negative impact of human activities (logging, grazing, debarking and charcoal burning) on tree species in the three study sites as compared to the control site. The results revealed a negative influence on the forest by human activities. The study recommended strict enforcement of the existing conservation laws concerning forest use by the local communities as well as formulating more integrated approach to the needs of local communities for natural resource use.
Forage availability and quality for the Impala (aepyceros melampus (brian) kathryh) of Impala sanctuary, Kenya
(International Journal of Recent Scientific Research, 2014-10-28) Obiet, Leonard; Konje, Martha; Muyekho, Francis; Danyuku, Esther; Kigen, Charles; Wamalwa, Stella; Kassily, Fredrick; Wabusya, Moses
Brian) Kathryh) in three ecosystems of the Impala sanctuary, Kenya was assessed during the wet and dry seasons. The grazing behavior of the impalas was observed to identify the preferred forage species and patterns grazing between seasons and ecosystems. Preferred grass species were sampled to determine percentage dry matter, neutral detergent fiber, acid detergent fibers, and Crude protein. Data was subjected to Analysis of Variance using SAS version 9.0. The results showed that impala sanctuary had 37 different grass species but Cynodon dactylon, Eragrostis curvula, Digitaris scalarum, Eleusine indica, Pennisetum setaceum and Hyparrhenia filipendula were most grazed on by the Impala. Grassland ecosystem had significantly high forage availability during the wet season, but in the dry season the marshes ecosystem was the one with the most nutritious forages. Grazing patterns varied with seasons, with most impalas preferring to graze in the grassland during the wet season and in the marshes during the dry season. The study suggests management practices that favor dominance of species that are most foraged in order to increase forage availability for the impalas in the sanctuary.
Population status and conservation hotspots of Prunus Africana (Hook. F.) Kalkman in South Nandi Forest, Western Kenya
(Researchjournali’s Journal of Forestry, 2016-07-01) Koros, Hillary; Konje, Martha; Wambua, Margaret; Chesire, Christopher; Odeny, Dickens; Malombe, Itambo
Prunus africanais assessed as vulnerable globally by the International Union for Conservation of Nature. The conservation status is however general and under-illustrated. It lacks details on the actual threats that cause precarious spatial distribution of the population in certain localities such as South Nandi Forest, Western Kenya. This study assessed thepopulation structure of P. africanaby correlation of biometric variable including Diameter at Breast Height and height class distribution and regeneration with the diversity and frequency of threats in spatial context of the plant species. Stratified Random Sampling was used to establish three belttransects of 400 m by 2 km within the forest and 1 km buffer zone in farmlands. The measure of mean, spread, normal distribution and correlation of biometric variables of P. africana was analysed using PAST (Version 4.3). Population structure was summarised using histograms and bar charts. Frequency distribution table was used to analyse the number of incidence of the threats to P. africanaat plot level. T-test was used to test for differences in P. africanaparameters among transects. The spatial distribution model of P. africanain the forest and buffer zone was mapped using the maximum entropy suitability mapping methodas implemented in MAXENT software(Version 3.3.3k) and QGIS Brighton (version 2.6). Prunus africanapopulation was highly concentrated in North eastern part of the forest and surrounding farmlands with admirable number of mature individuals. The Diameter at Breast Height distribution ofP. africanain the forest showed unstable and intermittent population structure unlike a stable population in the surrounding farmlands. Although the seeds germinated profusely, there was poor establishment and survival.Key conservation threats were overgrazing, firewood collection, logging and charcoal burning. The study recommends both in-situand ex-situconservation measures.Keywords: multipurpose, overgrazing, regeneration, vulnerable
Indigenous knowledge, uses and conservation of prunus africana (hook. f.) kalkman in Nandi forests
(International Knowledge Sharing Platiform : JNSR, 2016-01-01) Koros, Hillary; Malombe, Itambo; Mwendwa, Kaleb; Jeruto, Pascaline; Agevi, Humphrey; Konje, Martha
Prunus africana is a multipurpose medicinal tree of worldwide fame in treatment of benign prostate cancer. However, the wild collection is no-longer sustainable due to overharvesting. In order to conserve the species, there is need to determine the status of the local community knowledge on uses and conservation measures to develop protocols for sustainable utilization and avert extinction of the species. Stratified random sampling was used to interview and administer questionnaires to 188 households and herbalists within a buffer zone of 1 km in South Nandi Forest. The study found that 99% of the locals were aware of the P. africana tree. Majority (82%) agreed that P. africana population was decreasing both in the forests and farmlands. Almost all parts of the P. africana were utilized for different purposes. Majority of the locals (66%) acquire P. africana products from the forest. Closer proximity to the forest and uncontrolled harvesting provides easier accessibility to P. africana for households use. The study concluded that P. africana is an important multipurpose medicinal tree to the local community and recommends enhanced planting and protection within and outside the forests to ensure posterity.
Heavy metal contamination at dumpsites at Eldoret, Kenya, in the Lake Victoria Basin
(Ajol: African Journal of Tropical Hydrobiology and Fisheries, 2018-06-01) Khatiebi, Sandra; siamba, Donald N.; Onyando, Zedekiah; Mulmbala, Chrispinus; Konje, Martha
This study assessed the heavy metals concentrations in municipal solid wastes at Eldoret Mwenderi dumpsites located at the shores of river Sosiani within the Lake Victoria Basin, Kenya. Concentrations of the three heavy metals analysed (lead, arsenic and cadmium) in water and leachate were higher than the WHO acceptable standards. Lead concentrations in solid wastes were slightly above East African acceptable standards but well above the US EPA compost standards. The wastes dumped in this site are not sorted and the dumpsite lacks a leachate collection and removal system. Lack of composite liners at the bottom and side of the dumpsite allow leachates to move into the ground water around the dumpsite. These metals are a potential threat to Lake Victoria and regular monitoring of ground and surface water of the surrounding area should be done to detect any heavy metals escaping the dumpsite.

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