NRU :: Browsing by Author "Masembe, C."

Browsing by Author "Masembe, C."

Now showing 1 - 9 of 9

East African pigs have a complex Indian, Far Eastern and Western ancestry
(Animal genetics, 2015) Noce, A.; Amills, M.; Manunza, A.; Muwanika, V.; Muhangi, D.; Aliro, T.; Mayega, J.; Ademun, R.; Egbhalsaied, S.; Mercad, A.; Masembe, C.
In this study, we have characterized the mitochondrial diversity of 81 swine from Uganda. Median-joining network analysis of D-loop sequences from these individuals and others characterized in previous studies allowed us to determine that Ugandan pigs cluster with populations from the West (Europe/North Africa), Far East and India. In addition, partial sequencing of the Y-chromosome UTY locus in 18 Ugandan domestic pigs revealed the segregation of a single HY1 lineage that has a cosmopolitan distribution. A Western and Far Eastern ancestry for East African pigs had been already reported, but this is the first study demonstrating an additional contribution from the Indian porcine gene pool. This result is consistent with the high frequency of zebuine alleles in cattle from East Africa. The geographic coordinates of East Africa, at the crossroads of many trading routes that, through the ages, linked Europe, Africa and Asia, might explain the rich and complex genetic heritage of livestock native to this area.
Geometric Morphometrics of Geographic and Host-Associated Population Variations of Bactrocera Invadens in Uganda
(AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA, 2014) Isabirye, B.E.; Masembe, C.; Nankinga, C. K.; Muyinza, H.; Akol, A. M.
Fruit flies (Diptera: Tephritidae) are among the most economically important pests of edible fruits worldwide. Because of the cryptic nature of most species in Bactrocera complex, it is not clear whether allopatric and host associated speciation has taken course among B. invadens populations in the different zones in Uganda. This would be important in the design of efficient management strategies. The morphological variation of 3 allopatric and host-associated populations of B. invadens was studied using Euclidean distance matrix analysis and variance structure coordinate system geometric morphometrics techniques. Size and shape were analyzed throughout 15 landmarks for 360 specimens after symmetrization process. Host type significantly affected wing size and shape (P = 0.0001), with CVA showing host population discrimination with very high degree of population classification (95.03%) accuracy. Mango wings were significantly smaller than tropical almond, but the former did not significantly differ with guava. Similarly, mean wing size and shape among the three zones differed significantly (P = 0.000). B. invadens from the WMHF had relatively bigger wings, while the NMF recorded the smallest wings. CVA discriminant functions showed a very high degree of zonal population classification (95.48%) accuracy. LVC population wing shape was significantly different from NMF (P = 0.000) and WMHF (P = 0.000), while the latter two were also different (P = 0.000). There were significant differences in allometry and developmental instability fluctuating asymmetry among fruit hosts in the order: mango > guava > almonds. The results have added to the evidence that geographic and host-associated adaptation can produce reproductive isolation and produce ecotypes. The ability of B. invadens to undergo rapid ecological evolutionary radiations might affect the efficiency of common control methods, and our results should help to recast fruit fly management strategies.
Modeling the Potential Geographical Distribution and Ecological Niche of Selected Fruit Fly (Diptera: Tephritidae) Species in Uganda
(Journal of Plant and Pest Science, 2015) Isabirye, B.E.; Masembe, C.; Akol, A.M.; Muyinza, H.; Rwomushana, I.; Nankinga, C.K.
Despite their overwhelming economic importance, efforts to assess the distribution of fruit flies (Diptera: Tephritidae) in Uganda have been minimal. Consequently, in this study, potential geographical distributions and climatic envelopes of 10 selected fruit fly species were modeled. Two presence-only predictive models namely, Maxent and Bioclim, were run using 19 bioclimatic parameters at a resolution of 30 arc seconds. New detections and existing records of fruit flies were used in the model. The climatic profiles of the selected fruit flies were described and the relative importance of the bioclimatic variables was explored. There was a close agreement between the two models about the distribution and suitability patterns matching the main fruit agro ecological zones. Precipitation (PC-1 = 61.4190%) and temperature (PC-2 = 29.214%) significantly shaped fruit fly niches across the country. Central and mid north zones provided the most suitable niches, while the western, northeastern and areas around Albert Nile were characterized as marginally suitable. The models were mostly robust in performance (AUC: 0.815 – 0.974), with model test performance ranging from random (C. capitata: 0.486) to excellent (C. cosyra: 0.965). Predicted marginal sites, such as higher altitude zones matched negative areas of the models, which reflected higher model prediction abilities. These results provide an initial insight into the bioclimatic tolerance ranges of fruit flies in Uganda and should assist in identification of sites for future sampling efforts and fruit fly management planning.
Oviposition Preference and Offspring Performance in Phytophagous Fruit Flies (Diptera: Tephritidae): The African Invader, Bactrocera invadens
(International Research Journal of Horticulture, 2013) Akol, A. M.; Masembe, C.; Isabirye, B.E.; Kukiriza, C. K.; Rwomushana, I.
Behavioral choices have been hypothesized to reflect fine-tuned evolutionary adaptation by the preference-performance hypothesis (PPH), which states that female insects will evolve to oviposit on hosts on which their offspring fare best. The extent to which this is true in the African invader, Bactrocera invadens (Diptera: Tephritidae) was assessed in this study. Five host-plant species: Terminalia catappa (Combretaceae), Persea americana (Lauraceae), Psidium guanjava (Myrtaceae), Mangifera indica (Anacardiaceae), and Citrus sinensis (Rutaceae), and 11 mango varieties: Tommy, Zillatte, Keitt, Kent, Kagogwa, Apple, Palvin, Dodo, Kate, Biire and Glen, were tested for their conformity to the PPH. The fruits were incubated, larvae reared, and the adults maintained on an artificial diet in the laboratory. There was significant variability in host species (P = 0.038) and variety (P = 0.015) preference in the orders: T.catappa > P.guanjava > M. indica > C. sinensis > P.americana; while Glen & Biire and Zillate & Tommy were the most and least preferred varieties, respectively. Offspring performance (development rate, survival, weights and sex ratio) differed significantly and followed a very similar trend only that for fruit species P.americana performed better than C. sinensis. The relationship between host preference and the offspring performance measures showed strong support for the PPH with overall coefficient of determination of 75.4% (P = 0.000) and 65% (P = 0.003) for host species and varieties, respectively. This study has generally increased the knowledge on the role of host species and varieties on the biology of the pest and re-affirmed the growing credence that host-specific variation in adult performance has an important role in shaping host preference of phytophagous insects, as proposed by PPH.
Practices in the pig value chain in Uganda; implications to African swine fever transmission
(Livestock research for rural development, 2014) Muhangi, D.; Masembe, C.; Berg, M.; Ståhl, K.; Ocaido, M.
Uganda has the largest pig industry in eastern Africa, with majority of farmers still smallholders. African swine fever (ASF) is arguably one of the major constraints in the region, where it is considered endemic. Although the sylvatic cycle exists here, the pig-pig cycle of transmission is more important. The pig value chain is one critical area where there is need for study of the role it plays in the spread of ASF. In this study, different practices and their association with the transmission of ASF within and between farms were investigated on 101 pig farms in Uganda. Practices by 30 traders in pigs and pig products (slaughter slab, pork butchery and roasted pork restaurant operators) were investigated in the districts of Kabarole, Mityana, Moyo, Mukono, Soroti, and Tororo. Key informant interviews with the District Veterinary Officers (DVOs) about pig trade, pig slaughter infrastructure, ASF status and its Management in the districts were conducted as well between May-November 2011. Questionnaires were administered to both pig farmers and the traders.Twenty six percent of the farmers reported having had the disease on the farm in the last one year.Although none of the risk factors was statistically significant for ASF outbreaks, results demonstrated presence of potential risk factors for ASF on the farms and the rest of the pig value chain.
Prevalence Estimates of Antibodies Towards Foot-and-Mouth Disease Virus in Small Ruminants in Uganda
(Transboundary and emerging diseases, 2009) Balinda, S. N.; Tjørnehøj, K.; Muwanika, V. B.; Mwiine, F. N.; Ayebazibwe, C.; Masembe, C.; Siegismund, H. R.; Alexandersen, S.
Foot-and-mouth disease (FMD) is endemic in Uganda with control strategies focusing on vaccination of cattle, while small ruminants are largely ignored. In order for Uganda to establish effective control strategies, it is crucial that the epidemiology of the disease is fully understood. This study summarizes results of serological investigations of sheep and goats for antibodies to FMDV from four districts in 2006 following an FMD outbreak in the region and from an attempted comprehensive random sampling in two districts in 2007. Antibodies were quantified and serotyped using competitive ELISA for antibodies towards non-structural proteins (NSP) and structural proteins towards serotype O, and blocking ELISA for antibodies towards the seven serotypes of FMD virus (FMDV). In 2006, sheep and goats in Bushenyi and Isingiro districts were free from antibodies towards FMDV, while herds in Kasese and Mbarara districts excluding Kahendero village were all positive for antibodies towards NSP and SP-O. In 2007, mean prevalence estimates of antibodies towards FMDV NSP was 14% in goats and 22% in sheep in Kasese district, while Bushenyi was still free. The difference between these two districts probably reflects different levels of FMDV challenge attributed to the variation in exposure rates which again in part may be as a result of the differing husbandry practices. Contrary to 2006, with clear antibodies towards serotype O, the serotype-specificity of the antibodies was less clear in 2007, as antibodies towards both serotype O and SAT serotypes were identified. Our results show that goats and sheep are infected during FMD outbreaks, and that they may be useful for determining the serotype of FMD outbreaks in Uganda, if they are sampled shortly after an outbreak.
Prevention and Control of African Swine Fever in the Smallholder Pig Value Chain in Northern Uganda: Thematic Analysis of Stakeholders’ Perceptions
(Frontiers in veterinary science, 2021) Aliro, T.; Chenais, E.; Odongo, W.; Okello, D. M.; Masembe, C.; Ståhl, K.
African swine fever (ASF) is endemic in Uganda and considered a major constraint to pig production. In the absence of a vaccine, biosecurity is key for ASF prevention and control. To improve prevention and control on farm and community level there is need for more knowledge on current application of biosecurity practises, and better understanding of how pig value chain actors perceive prevention and control. To achieve this, a qualitative interview study involving focus group discussions (FGD) was conducted with actors from the smallholder pig value chain in northern Uganda. Six villages were purposively selected based on previous outbreaks of ASF, preliminary perceived willingness to control ASF, and the representation of several different value chain actors in the village. Results indicated that biosecurity practises such as basic hygiene routines including safe carcass handling, minimising direct and indirect contacts between pigs or between pigs and people, trade restrictions and sharing of disease information were implemented in some of the villages. Thematic analysis based on grounded theory revealed six categories of data relating to ASF prevention and control. Together these categories form a logical framework including both enablers and hindrances for ASF prevention and control. In summary participants mostly had positive perceptions of ASF biosecurity, describing measures as effective. Participants further possessed knowledge of ASF and its transmission, some of which was in line with known scientific knowledge and some not. Nevertheless, participants were hindered from preventing and controlling ASF due to biosecurity costs and a need to prioritise family livelihood over disease transmission risks, incompatibility of current biosecurity practises with local culture, traditions and social contexts and finally lack of access to veterinarians or, occasionally, low-quality veterinary services. The constraints could be addressed by applying participatory processes in designing biosecurity measures to ensure better adaptation to local cultural and social contexts.
Serotype Specificity of Antibodies against Foot-and-Mouth Disease Virus in Cattle in Selected Districts in Uganda
(Transboundary and Emerging Diseases, 2010) Mwiine, F. N.; Ayebazibwe, C.; Mukani, W. Olaho; Alexandersen, S.; Balinda, S. N.; Masembe, C.; Okurut, A. R. Ademun; Christensen, L. S.; Sørensen, K. J.
Uganda had an unusually large number of foot-and-mouth disease (FMD) outbreaks in 2006, and all clinical reports were in cattle. A serological investigation was carried out to confirm circulating antibodies against foot-and-mouth disease virus (FMDV) by ELISA for antibodies against non-structural proteins and structural proteins. Three hundred and forty-nine cattle sera were collected from seven districts in Uganda, and 65% of these were found positive for antibodies against the non-structural proteins of FMDV. A subset of these samples were analysed for serotype specificity of the identified antibodies. High prevalences of antibodies against non-structural proteins and structural proteins of FMDV serotype O were demonstrated in herds with typical visible clinical signs of FMD, while prevalences were low in herds without clinical signs of FMD. Antibody titres were higher against serotype O than against serotypes SAT 1, SAT 2 and SAT 3 in the sera investigated for serotype-specific antibodies. Only FMDV serotype O virus was isolated from one probang sample. This study shows that the majority of the FMD outbreaks in 2006 in the region studied were caused by FMDV serotype O; however, there was also evidence of antibodies to both SAT 1 and SAT 3 in one outbreak in a herd inside Queen Elizabeth national park area.
Threats posed by xenoestrogenic chemicals to the aquatic ecosystem, fish reproduction and humans: a review
(African Journal of Aquatic Science, 2020) Badamasi, I.; Odong, R.; Masembe, C.
Xenoestrogens mimic and interfere with natural functions of oestrogens and adversely affect fish reproduction. Pesticides, plastics, wastewaters and pharmaceuticals are sources of xenoestrogens, and are carried through surface runoffs to water bodies at concentration levels that are harmful to aquatic organisms. Fish absorb xenoestrogens through ingestion of contaminated food items, respiratory gills and dermal contact. Xenoestrogens bioaccumulate in fish tissues, eliciting various reproductive abnormalities, e.g. males may abnormally produce vitellogenins and present with reduced sperm counts, whereas females experience reduced fecundity and hatchability of eggs. Through the food web, xenoestrogens biomagnify in fish predators, e.g. seals and humans, which in turn risk suffering from reproductive malfunctions. Studies of adverse impact of xenoestrogens on fish have mainly been limited to developed countries, yet fish are a major food and trade commodity for developing sub-Saharan African countries. This review serves as a basis for research on adverse impacts of xenoestrogens on fish reproduction, and other consumers of aquatic organisms in Lake Victoria. The lake receives high levels of pollutants from untreated or poorly-treated domestic and industrial wastes and agro-chemicals. Control of xenoestrogens requires concerted effort from multistakeholders to undertake activities such as surveillance, advocacy, legislation and biodegradation to minimise their adverse impacts.

Browsing by Author "Masembe, C."

Results Per Page

Sort Options