African Journals Online
SINET: Ethiopian Journal of Science

Volume 25, No. 2 (December 2002)
Abstracts

PLANT COMMUNITY ANALYSIS AND ECOLOGY OF AFROMONTANE AND TRANSITIONAL RAINFOREST VEGETATION OF SOUTHWESTERN ETHIOPIA

Kumelachew Yeshitela ¹ and Tamrat Bekele ²

¹ Forest Genetic Resources Conservation ProjectInstitute of Biodiversity Conservation and Research, PO Box 30726Addis Ababa, Ethiopia, E-mail: [email protected] 

² Department of Biology, Faculty of Science, Addis Ababa University, PO Box 3434, Addis Ababa, Ethiopia, E-mail: [email protected] 

ABSTRACT: The plant communities of the forests of southwestern Ethiopia were described based on floristic analysis of the data collected between February 1995 and May 1996. Floristic analysis is based on the cover-abundance values of both woody and herbaceous species. Plant community-environment relationship was assessed based on topographic and some soil physical and chemical characteristics. A total of 101 relevés were analysed at altitudes between 1050 and 2550 m a.s.l. (metres above sea level), and a total of 139 species of vascular plants were identified. Nine plant community types were described. Most of these show significant variations for most of the environmental parameters studied. The species in the forest were phytogeographically related to the Afromontane, Guineo-Congolean or Guineo-Congolean linking species.

Key words/phrases: Afromontane, classification, Ethiopia, plant community, transitional rainforest

THE MATING SYSTEM OF SESBANIA SESBAN (L.)MERR. (LEGUMINOSAE)

Girma Gebremariam ¹, Sileshi Nemomissa ², Abebe Demissie ³ and Jean Hanson ¹

¹ International Livestock Research Institute (ilri), PO Box 5689Addis Ababa, Ethiopia, E-mail: [email protected] 

² Department of Biology, Faculty of Science, Addis Ababa University, PO Box 3434, Addis Ababa, Ethiopia

³ Biodiversity Conservation and Research Institute, PO Box 30726, Addis Ababa, Ethiopia

ABSTRACT: The mating system of Sesbania sesban was studied using one natural population and two cultivated populations. A large number of progeny (600) was assayed from each population for one polymorphic locus of Malate dehydrogenase (Mdh). The level of out-crossing in the studied populations ranged from 40–100%. The genotype frequencies were in agreement with those of the Hardy-Weinberg expected genotype proportions as in randomly mating populations at P < 0.05. The floral structure and the pollen shedding behaviour of the flowers of S. sesban could favour cross-pollination and/or self-pollination depending on the circumstances. Self-pollination usually occurs late in the flowering period when pollinators fail to visit the flowers. Such a “delayed selfing” facilitates out-crossing in the presence of appropriate pollinators under natural conditions, but confers a selective advantage where pollinators are limiting. The results indicated that S. sesban could be self-fertilized in the absence of pollinators or could out-cross with other heterozygous individuals in the neighboring population when suitable pollinators are available. S. sesban exhibits “facultative xenogamy” or “delayed selfing” and is a mixed mating species.

Key words/phrases: Allozymes, delayed selfing, Hardy-Weinberg equilibrium, malate dehydrogenase, mixed mating system

VARIATION AND ASSOCIATION ANALYSIS IN GRASS PEA (LATHYRUS SATIVUS L.)

Wuletaw Tadesse¹ and Endashaw Bekele ²

1 Adet Research Centre P.O. Box 08, Bahir Dar, EthiopiaE-mail: [email protected] 

2 Department of Biology, Faculty of Science, Addis Ababa UniversityPO Box 1176, Addis Ababa, Ethiopia

ABSTRACT: The study was conducted on 50 landrace populations of grass pea at Adet Research Center, Ethiopia, using randomised complete Block design in three replications to determine morphological variability and character associations. Evaluations were made on plant and yield characters from eight plants tagged randomly from each plot. The data were subjected to Analysis of Variance (anova), heritability, correlation and cluster analyses. Higher mean and cv values were recorded for most of the agronomic traits for populations collected from Gondar region and the higher altitude group (>2500 m) indicating the presence of high genetic diversity in this region and altitude group. Phenotypic coefficient of variation (pcv) was slightly higher than genotypic coefficient of variation (gcv) for all the characters studied signifying that genotypic factors exerted reasonable effect in estimating the variation. The wide difference between pcv (22.4%) and gcv (13.0%) for seed yield per plant indicated the complexity of this trait and the important role of other factors such as environment in influencing yield potential in addition to the genetic factors. The strong positive association of pods per plant, 100 seed weight and primary branches per plant with seed yield indicated the possibility of selecting lines for yield improvement based on these characters at the very early stage of the grass pea breeding program.

Key words/phrases: Correlation grass pea, heritability, Lathyrus sativus, variation

HIND LIMB BONES AND LOCOMOTION INTHE OLD WORLD MONKEYS

Solomon Yirga*

Department of Biology, Faculty of Science, Addis Ababa UniversityPO Box 1176, Addis Ababa, Ethiopia

ABSTRACT: A functional morphological study of the hind limbs of 49 species of cercopithecids reveals their respective positional behaviour. The result of the principal component analysis, based on sixty indices of the hind limb bones brings Colobus, Cercopithecus (including Miopithecus and Allenopithecus), Cercocebus,and Lophocebus, together, separating them from Macaca, Papio and Theropithecus in the first component. In the second component, colobinae are distinctly separated from the rest, with mangabeys being closest to them. The first component is interpreted to represent the adaptation to the substrata of locomotion, namely, arboreality and terrestriality; and the second their positional behaviour.

Key words/phrases: Functional morphology, hind limb, Old World monkeys, principal component analysis, quadrupedalism

THE GEOTECTONIC EVOLUTION OF THE WESTERN ETHIOPIAN SHIELD

Teklewold Ayalew¹ and Timothy E. Johnson²

¹ Department of Geology and Geophysics, Faculty of Science, Addis Ababa University, PO Box 40105, Addis Ababa, Ethiopia, E-mail: [email protected] 

² Institute for Mineralogy and Petrology, Karl-Franzens University, A-8010 Graz, Austria, E-mail: [email protected] 

ABSTRACT: The western Ethiopian Shield comprises three lithotectonic units. The Birbir domain, an assemblage of mafic to felsic intrusive and extrusive rocks and mainly volcanogenic sedimentary rocks, is enclosed between the dominantly orthogneissic Baro and Geba domains. The earliest recorded deformation event (D1) resulted in the formation of a subhorizontal gneissosity within the gneissic terranes which was synchronous with an early upper amphibolite-facies metamorphic peak (M1) at 800–770 Ma which locally caused partial melting. All terrains were subsequently deformed in the D2 event which was the result of severe E-W crustal shortening. An anticlockwise P-T-t path is implied. Subsequent D3 deformation was concentrated within mylonitised domain boundaries which record major transcurrent movement. These structures were reactivated and suffered fluid incursion resulting in isotopic reequilibration at 635–580 Ma. A second metamorphic event, M2, related to crustal thickening and consequent granite genesis, occurred after the cessation of D3 shearing. Bulk chemical analyses show that the metamorphosed plutonic and volcanic rocks of the Birbir domain are predominantly calc-alkaline and similar to those generated by subduction in modern magmatic arcs. They belong in part to the low-K series, suggesting an oceanic environment. The evolution of the region can be explained in terms of the melting of a subducting slab, intrusion, metamorphism and the formation of an oceanic island arc complex. Continued plate convergence caused severe east-west shortening and basin closure. Further attenuation gave rise to transcurrent shearing, fluid influx, a second thermal event and accretion of microcontinents.

Key words/phrases: Accretion, cratonisation, isotope systems, subduction, transcurrent movement

INTEGRATED GEOPHYSICAL INVESTIGATIONS TO STUDY THERMAL ZONES AT BOKU VOLCANIC CENTER, MAIN ETHIOPIAN RIFT

Tigistu Haile ¹, Tamiru Alemayehu ¹ and Shimelis Fisseha ²

¹ Department of Geology and Geophysics, Faculty of Science, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia, E-mail:[email protected] 

² Ethiopian Institute of Geological Surveys, Ministry of Mines, PO Box 2302, Addis Ababa, Ethiopia

ABSTRACT: This paper presents the results of electrical and magnetic surveys carried out over the Boku fumarole sites (Main Ethiopian Rift). On the basis of observed thermal manifestations, surface alterations and geophysical results we suggest that the Boku thermal field is a vapour-dominated, dry type geothermal system tapping heat from the shallow acidic magma chamber of Quaternary volcanic rocks of the Rift floor. The cap rock is formed by the self-sealing process through hydrothermal alterations of the Plio-Quaternary volcanic rocks in the area as witnessed by the surface manifestations of calcite and silica that are suggestive of such an environment. The aquifer system consists of the Quaternary Rift floor ignimbrites that are fractured intensively. The necessary supply for the replenishment of the reservoirs is derived from the closed basin system of the Nazareth watershed and/or from the large open irrigated grounds of the Wonji plantation. The investigations have clearly mapped the Quaternary faults that are the major tectonic structures for the passage of the deep-seated vapour to the surface, and the recharging of the geothermal reservoir.

Key words/phrases: Boku caldera, hydrothermal alterations, magnetic anomaly, vapour-dominated geothermal systems, vertical electrical sounding

THE CHEMICAL COMPOSITION OF THE EFFLUENT FROM AWASSA TEXTILE FACTORY AND ITS EFFECTS ON AQUATIC BIOTA

Zinabu Gebre-Mariam and Zerihun Desta

Faculty of Natural Sciences, Debub University, PO Box 5Awassa, Ethiopia, E-mail: [email protected] 

ABSTRACT: The chemical composition of the effluent from the Awassa textile factory was quantified and its effects on chlorophyll-a concentration and fish fry were examined. The effluent contained high concentrations of toxic heavy metals, and concentrations of about 70% of all the elements measured were higher (by 10 to 100 times) in effluent treated in ponds (biological lagoons) than straight from the factory, presumably due to concentration by evaporation. Chlorophyll-a concentration in lake water samples containing 10% and 20% textile effluent from the ponds increased by 5 to 1400% and 7 to 4000%, respectively, whereas the changes in the control were -24% to 433%. About 18% and 53% of the fish fry died within 12 hr in 10% and 20% pond effluent in lake water, respectively. The highest mean mortality level was about 64% in the 20% effluent treatment at 24 hr. It was concluded that the effluent treatment ponds of the factory do not efficiently reduce the chemicals in the discharge. The observed effects of the "treated effluent" on phytoplankton biomass and fish fry indicate the undesirable effects the effluent will have on Lake Awassa. It is recommended that an alternate waste disposal system for the textile factory be set up, with regular monitoring of its effectiveness, so as to avoid undesirable long-term changes to the lake.

Key words/phrases: Chemical composition, chlorophyll-a, fish fry, effluent, textile factory

MOLLUSCICIDAL EFFECTS OF ENDOD (PHYTOLACCA DODECANDRA) ON FASCIOLA TRANSMITTING SNAILS

Tadesse Eguale ¹and Getachew Tilahun ²

¹ National Animal Health Research Center, Ethiopian Agricultural Research Organization P.O.Box 04, Sebeta, Ethiopia, E-mail: [email protected] 

² Institute of Pathobiology, Addis Ababa University PO Box 1176, Addis Ababa, Ethiopia

ABSTRACT: A study was conducted to investigate the molluscicidal effects of crude water suspension of unripe green Endod (Phytolacca dodecandra) berries (Type 44) on different developmental stages of Lymnaea natalensis and Lymnaea truncatula. Concentration of 20 ppm for exposure period of 24 hours induced 100 % mortality in young L. natalensis and L. truncatula snails, while higher concentration was required for mature snails of both species. The LC₉₀ on L. natalensis with shell height of 5-9.8 mm., 10–2.9 mm. and 13–18.5 mm. was 19.8, 21.1, 22.8 ppm, respectively. With regards to L. truncatula the LC₉₀ for snails with a shell height of 3.4-5.4 mm and 5.7–8.2 mm was 19.5 and 21 ppm, respectively. Study on time-concentration relationship revealed that exposing snails for one hour required a concentration of 48.9 and 72.5 ppm in young (6–12.4 mm.) and adult (12.5–18.5 mm.) L. natalensis to cause 90% mortality, respectively. In the case of L. truncatula snails (4.5–7.4 mm) 54.5 ppm was needed to produce 90 % mortality. However, both snail species were killed at about a concentration of 20 ppm between 6 and 24 hours of exposure times.

Key words/phrases: Endod, fascioliasis, Lymnaea natalensis, Lymnaea truncatula, Molluscicide

ANTI-BACTERIAL ACTIVITY OF PLUMBAGO ZEYLANICA L. ROOTS ON SOME PNEUMONIA CAUSING PATHOGENS

Hirut lemma 1, Asfaw Debella 1, Getachew Addis 1, Olaf Kunert 2, Aberra Geyid 1, Ferehiwot Teka 1 and Kidist Yersaw 1

¹ Ethiopian Health and Nutrition Research Institute, PO Box 1242, Addis Ababa, Ethiopia, E-mail: [email protected] 

² Institute of Pharmaceutical Chemistry, Karl-Franzens University of Graz, Graz, Austria

ABSTRACT: The anti bacterial activity of polar and non-polar extracts prepared from the roots of Plumbago zeylanica L. (Plumbaginaceae), a plant widely used in Ethiopian traditional medicine for various ailments were investigated using hole plate diffusion method against some pneumonia causing pathogens. The aqueous extract did not exhibit any activity while petroleum ether extract was found to have strong anti-bacterial effects as compared to the ethanol extract which showed a significant activity. Activity guided chromatographic purification of the petroleum ether extract led to the isolation of three compounds, of which the compound identified as 5-hydroxy-2-methyl-1, 4-naphthoquinone, plumbagin, found to be the active component on the tested microorganisms. Minimum inhibitory concentration value of this particular compound showed comparative activity resembling the commonly used broad spectrum antibiotic, tetracycline. The strong antibacterial effect of the petroleum ether extract is discussed to show that it was attributable to this compound rather than the other two that were found to have trace of activities.

Key words/phrases: Anti-bacterial activity, Minimum inhibitory concentration, Plumbago zeylanica, pneumonia

Short communication

MULTIPLE ANTIMICROBIAL RESISTANCE IN BACTERIAL ISOLATES FROM CLINICAL AND ENVIRONMENTAL SOURCES OF JIMMA HOSPITAL, SOUTH WEST ETHIOPIA

Zeleke Wolde Tenssay

Institute of Biodiversity Conservation and Research, PO Box 30726Addis Ababa, Ethiopia, e-mail:[email protected] 

ABSTRACT:. A total of 545 clinical specimens (pus, blood, urine, and stool) and environmental specimens (air sample, saline solution, nasal swabs etc) were cultured for isolation and identification of aerobic bacteria and antimicrobial susceptibility testing. Out of these, 356(65%) specimens yielded one or more bacterial strains. Frequent bacterial isolates were S. aureus (17%), coagulase-negative staphylococci (25%), Proteus species (10.%), Klebsiella species (8%), E. coli and Enterobacter species (14%). The antimicrobial susceptibility test result shows that all E. coli, Klebsiella, and Enterobacter species were resistant to ampicillin. Similarly 93% S. aureus, 88% coagulase-negative staphylococci were resistant to the same antimicrobial agent. Eighty five percent of Klebisiella, and 79% of E. coli were resistant to tetracycline. Almost all the isolates were found to be multiply resistant to the commonly used antimicrobials, ampicillin, tetracycline, chloramphenicol, and trimethoprim-sulphamethoxazole. Antimicrobial resistant strains of bacteria are increasing and may contribute to spread of serious infectious diseases. Therefore, to prevent and control infections by emerging antimicrobial resistant bacterial strains, measures such as strengthening clinical microbiology laboratory, emphasis on hygienic practices in hospital, and prudent use of existing antimicrobial agents are recommended.

Key words/phrases: Antimicrobial resistance, antimicrobial susceptibility, bacterial isolates, microorganisms