African Journal of Biological Sciences

1-14

Authors: Mudde, B., Miano D. W., Olubayo, F. M., Asea, G., Kilalo, D.C., Kwemoi, D. B., Adriko, J., Ssekiwoko, F., Male, A. and Kiggundu, A.

Maize lethal necrosis (MLN) disease is caused when maize plants become coinfected with Maize chlorotic mottle virus (MCMV) and potyviruses notably Sugarcane Mosaic Virus (SCMV). Apart from maize, little is known about susceptibility of weed species and cultivated crop species usually growing in proximity with maize to MLN viruses in Uganda. The common weeds and crop plants were mechanically inoculated with combined sap from MCMV and SCMV infected maize plants. Samples were tested for MLN causing viruses by Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA) and Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). The weeds that were susceptibility to MCMV were Digitaria abyssinica, Eleusine africana and Roetboellia cochinchinensis; while those susceptible to SCMV were Pennisetum purpureum, Panicum maximum and Roetboellia cochinchinensis. The cultivated crops were susceptible only to MCMV and included cassava (Manihot esculenta), groundnut (Arachis hypogaea) and bean (Phaseolus vulgaris). Common weeds and cultivated crops growing close to maize in Uganda have differential susceptibility to MLN causing viruses and can act as reservoirs of MLN causing viruses. It is critical to identify non MLN hosts in cultivated crops for crop rotation and early weeding to reduce on MLN virus inoculum in cropping systems.

24-31

Authors: Ngetha Edwin, Julia Khayeli Akhwale and Romano Mwirichia

Lake Magadi is an alkaline saline Lake in Kenya, which lies on the Great Eastern Rift valley. Although the lake is characterized by extremes of salt, pH and temperature, it supports diverse groups of cyanobacteria. In this study, we used different media to isolate novel groups of cyanobacteria. We recovered 11 isolates affiliated to the orders Chroococcales, Oscillatoriales, Pleurocapsales and Nostocales. Isolates affiliated to Chroococcidiopsis species had similarity values below 90% to currently characterized taxa indicating that these could be completely new phylotypes. This taxon has not been isolated before from the soda lake indicating the power of molecular techniques in identifying novel cyanobacterial taxa. Only two of the recovered isolates had 99% similarity to known organisms. Previous studies have mainly relied on microscopic examination and identification, which can lead to misidentification and subsequent assignment of an organism to the wrong taxon. The recovered isolates are a useful resource of more studies on taxonomy and secondary metabolite production.

42-57

Authors: Augustine W. Mwandya

The impacts of human related activities on trophic structure of mangrove associated fish species, was investigated by sampling fish in mangrove creeks. Trophic organization and stable isotope signatures (δ13C and δ15N) of fish in undisturbed mangrove creeks were compared with clear-cut areas of mangrove and reservoirs for saltworks and fish farms constructed after mangrove clearing. Results showed significantly higher densities, species numbers, diversity (H’) and numbers of trophic groups in undisturbed sites compared to disturbed sites. Overall, omnivorous fish comprised the most abundant feeding guild, which dominated in the cleared sites followed in order by the uncleared sites and reservoirs. The zoobenthivores/piscivores was the most diverse group, with the highest species richness in the undisturbed areas. Multivariate analysis showed that assemblage structure of omnivores in the reservoirs was separated from those in uncleared and cleared sites, while zoobenthivores/piscivores differed between uncleared sites and disturbed areas. Stable isotope ratios of δ13C and δ15N values in fish muscles indicated significant diet shifts between undisturbed and disturbed mangrove creek systems, although the effects were species-specific. The findings suggest that mangrove deforestation combined with land-use changes, has a greater impact on the trophic structure of fish in mangrove creeks than mangrove deforestation only.

68-75

Authors: Callixte Yadufashije, Ange Yvette Uwitonze, Yvonne Manizabayo and Thierry Habyarimana

Background: Helicobacter pylori (H. pylori) is a small, spiral-shaped bacterium that lives in the surface of the stomach and duodenum. More than half of the world’s population is colonized with H. pylori in the gastric mucosa which is the major cause of chronic gastritis, peptic ulcer and also the most important etiological factor responsible for the duodenal and gastric ulcer and has an important role in the pathogenesis leading to gastric cancer. Objectives: The objectives of this study was to determine the prevalence of H. pylori among gastritis patients at Nemba district hospital, to compare sex prevalence level of H. pylori among gastritis patients and determine the prevalence of H. pylori among gastritis patients according to the age of gastritis patients. Methods: This study involved 140 patients with gastritis who attended Nemba district hospital from August to October 2018. The samples were collected and H. pylori rapid test strip was performed for all patients to diagnose H. pylori among gastritis patients. Results: Findings of the study showed that the prevalence of H. pylori infection was found to be significantly high among female participants than male participants. Despite high prevalence in females, the findings showed that there was no statistical significance of sex with H. pylori infection (χ2 = 0.6 and p > 0.05, p = 0.1). On basis of age, the prevalence of H. pylori infection was found to be high among participants and the prevalence increase between young age and old age. Results show that there was statistical significance between age and H. pylori infection with χ2 = 1.2 and p > 0.05, p = 0.04. the group of individuals with that ≥ 45 years old were more affected compared to other age groups and the prevalence of H. pylori infection was increased in older patients than younger patients. Our study showed an overall prevalence of H. pylori among gastritis patients was (45.7% n = 140). Conclusion: H. pylori infection is terrible burden of public health and affect people of all age and sex. H. pylori infection was significantly high in females and significance was found in age group of patients. Number of people are carrier of this terrible bacterium, thus hospitals are recommended to carry out early diagnosis to avoid later complication of infection.