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SINET: Ethiopian Journal of Science

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Volume 24, No. 2 (December 2001)
Abstracts

RESEARCH ARTICLES

REGULARITY THEOREM FOR FUNCTIONS THAT ARE EXTREMAL TO PALEY INEQUALITY

Seid Mohammed

Department of Mathematics, Faculty of Science, Addis Ababa University

PO Box 1176, Addis Ababa, Ethiopia, E-mail: [email protected] 

ABSTRACT: In this paper we study the asymptotic behavior of functions that are extremal to the inequality introduced by Paley (1932) via a normal family of subharmonic functions.

Key words/phrases: Subharmonic, characteristic function, lower order, Pólya peaks, *-function.

 

APPLICATION OF ISOTOPE AND WATER BALANCE APPROACHES FOR THE STUDY OF THE HYDROGEOLOGICAL REGIME OF THE BISHOFTU CRATER LAKES, ETHIOPIA

Seifu Kebede, Tenalem Ayenew and Mohammed Umer

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

ABSTRACT: The major Ethiopian rift lakes have been studied for various purposes in the last few decades. However, crater lakes situated elsewhere in the country are some of the poorly understood hydrologic systems. This study focuses on quantifying the groundwater fluxes and assessment of the hydrogeological regime of the Bishoftu Crater Lakes using conventional water balance and stable environmental isotope (2h and 18o) techniques. The convenient geological setting of these lakes has provided a suitable base for determining groundwater exchange rates using stable isotopes coupled with hydrologic balance. The result indicates that these lakes have highly variable groundwater fluxes. Evaporation and groundwater fluxes are the major components of the hydrologic balance. Unlike the other lakes, lake Hora appears to have extremely low groundwater outflow. The lakes are highly evaporated with respect to the present day precipitation. Other groundwater and surface water sources are relatively depleted in the heavy isotopes. The isotope and hydrochemical signature indicates that the circulation of groundwater and recharge is fast and the regional groundwater flow direction is from north to south.

Key words/phrases: Crater lakes, Ethiopian rift, groundwater, isotopes, water balance

NUMERICAL GROUNDWATER FLOW MODELING OF THE CENTRAL MAIN ETHIOPIAN RIFT LAKES BASIN

Tenalem Ayenew

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

ABSTRACT: A three dimensional steady-state finite difference numerical groundwater flow model (modflow) was used to study the groundwater-surface water interactions in the Central Main Ethiopian Rift lakes basin. Special emphasis is given to quantifying the groundwater fluxes and the subsurface hydraulic connection of the rift valley lakes. The result shows that despite the geographic proximity of the lakes the groundwater flux is highly variable, mainly owing to geologic factors. The net groundwater flux ranges from 7,011 m 3 /day for Lake Abiyata to 651,022 m 3/day for Lake Shala. The groundwater flow converges from all sides of the basin to the center of the rift where the lakes are clustered, and ultimately to the terminal Lake Shala. Local, intermediate and regional flow systems were identified. The direction and magnitude of the faults have strong bearing on the occurrence and movement of the groundwater. The major flow systems and groundwater flux into the lakes are controlled strongly by rift faults.

Key words/phrases: Groundwater flow, groundwater modeling, hydrogeology, Rift lakes, water balance

 

Attachment study of Agrobacterium tumefaciens to tef [Eragrostis tef (Zucc.) Trotter], yam spp., and Tobacco (Nicotiana tabaccum L.) explant

Frew Mekbib 1, Vicky Buchanan-Wollaston 2 and Sinclair H. Mantell 2

1 Department of Plant Sciences, Alemaya University

PO Box 138, Dire Dawa, Ethiopia, E-mail: [email protected] 

2 University of London, Wye College, Nr Ashford, TN25 25AH, Wye, uk

ABSTRACT: Agrobacterium tumefaciens attachment as a factor in transformation was investigated in tef (Eragrostis tef) zygotic embryos, seeds, seedlings, leaf bases and embryogenic callus; leaf discs of yam species (Dioscorea bulbifera, Dioscorea caynensis and Dioscorea alata); and leaf discs of tobacco (Nicotina tabaccum). Cocultivation was made with A1030(pCOPA10), A1030(pEB122), A1030(pTBl08), A1030(pIB422), A1030(virA:Tn5) and A281(pTiBO542). Attachment and fibrils were observed associated in all strains, species, plants and explant used. Even though attachment is observed in intact and wounded plants, preferential attachment was observed around the wound area of explants. Uniformity with bacteria binding was obtained with acetosyringone treatment. The strains used equally bound to tef and yam in the same way as they did to tobacco which was a positive control. Thus, tef and yam, like that of tobacco fit all the criteria for Agrobacterium attachment.

Key words/phrases: Acetosyringone, Agrobacterium tumefaciens, plant-bacterial attachment, tef, scanning electron microscopy

STUDIES OF RHIZOBIUM INOCULATION AND FERTILIZER TREATMENT ON GROWTH AND PRODUCTION OF FABA BEAN (VICIA FABA) IN SOME 'YIELD-DEPLETED' AND 'YIELD SUSTAINED' REGIONS OF SEMIEN SHEWA

Ayneabeba Adamu 1, Fassil Assefa 1 , Asfaw Haile Mariam 2 and Endashaw Bekele 1

1 Department of Biology, Faculty of Science, Addis Ababa University

PO Box 1176, Addis Ababa, Ethiopia, E-mail: [email protected] 

2 National Soil Laboratory, Ethiopian Agricultural Research Organization

PO Box 2003, Addis Ababa, Ethiopia

ABSTRACT: The failure of faba bean production in some regions of Semien Shewa necessitated a research for a possible explanation and solution to reverse the problem. Two regions with a failure in pulse production of faba bean for five to ten years i.e.'yield-depleted' Molale and Mehal Meda, and two regions that are still capable of producing faba bean i.e. 'yield-sustained' Ankober and Keyt were selected. Comparative assessments of their nutritional factors, rhizobial type, rhizobial density, and inoculation and fertilizer treatments with respect to their soil types were undertaken. The soil analyses showed that 'yield-depleted' areas were generally characterized by a medium to high concentration of nitrogen (0.1—0.2%), a low content of phosphorus (3—6 ppm) and potassium, a high concentration of calcium and magnesium, and a lower population density of rhizobia (10 1—10 2 g-1 soil). The results also showed that shoot length, shoot dry matter, and nodule fresh weight were significantly affected (p=0.01) by soil type and different inoculation and fertilizer treatments. Although growth parameters, in general, were improved by different treatments, shoot dry matter and nitrogen contents were not significantly affected in 'yield-sustained' regions as compared to 'yield-depleted' ones. The results also showed that the comparative symbiotic effectiveness of the indigenous strains and the type exotic strain (reference strain) Tal 1397N was not different. It did not also show significant difference on the above mentioned growth parameters with different treatments. This indicates that the indigenous strains are equally effective in nitrogen accumulation provided that the problems of other limiting nutritional factors can be alleviated in the soil. This suggests that combined inoculation and fertilizer treatments can improve growth and reverse production of pulses in 'yield depleted' regions of Semien Shewa.

Key words/phrases: Faba bean, fertilizer and inoculation treatments, growth-related parameters, indigenous and exotic rhizobia, Semien Shewa

AN ECOLOGICAL STUDY OF THE VEGETATION OF GAMBELLA REGION, SOUTHWESTERN ETHIOPIA

Tesfaye Awas 1, Tamrat Bekele 2 and Sebsebe Demissew 2

1 Institute of Biodiversity Conservation and Research

PO Box 30726, Addis Ababa, Ethiopia

2 The National Herbarium, Department of Biology, Faculty of Science

Addis Ababa University PO Box 3434, Addis Ababa, Ethiopia

E-mail: [email protected] 

ABSTRACT: The vegetation of Gambella Region, southwestern Ethiopia, has been studied through five field trips made between October 14, 1995 and October 10, 1996. Systematic sampling method was used to select homogenous vegetation stands. Cover/abundance data was recorded for all plants from a total of 58 relevès. For each relevè, environmental data on topographic factors (altitude and slope), and soil from a depth of 0—10 cm (topsoil) and 40—50 cm (subsoil) were collected. The soil samples were analyzed for pH, texture, cation exchange capacity, organic carbon, total nitrogen, available phosphorus, exchangeable potassium and sodium. The species and relevès were classified using a fortran computer program twinspan and seven major plant communities were described. Five plant communities were found to have phytogeographical affinity to the Sudanian vegetation type while two are affiliated to the Guineo-Congolian vegetation type of Africa. Comparison of the community types was made using anova to find whether there are statistically significant variations in environmental factors.

Key words/phrases: Ethiopia, Gambella Region, phytogeographic affinity, phytosociology, plant communities

 

HOST RANGE DETERMINATION OF TSETSE FLY GLOSSINA MORSITANS SUBMORSITANS BY BLOODMEAL ANALYSIS IN THE UPPER DIDESSA RIVER VALLEY (WESTERN ETHIOPIA)

Habtamu Belete 1, Getachew Tikubet 2, Beyene Petros 3 and E.K. Kang'ethe 4

1 Department of Microbiology and Parasitology, Faculty of Medicine

Addis Ababa University, PO Box 22442 code 1000, Addis Ababa, Ethiopia

E-mail: [email protected] 

2 icipe-Ethiopia Collaborative Project, PO Box 3853, Addis Ababa, Ethiopia

3 Department of Biology, Faculty of Science, Addis Ababa University

PO Box 1176, Addis Ababa, Ethiopia

4 Department of Public Health, Pharmacology and Toxicology

University of Nairobi, PO Box 29053, Nairobi, Kenya

ABSTRACT: Enzyme linked immunosorbent assay (elisa) was employed to determine the rate of digestion of blood proteins ingested by teneral and non-teneral laboratory reared Glossina morsitans morsitans at different time intervals after feeding. This test showed that non-teneral flies digested the species distinguishing bloodmeal components faster than tenerals. At 48 hr post-feeding, the bloodmeal donor was identifiable in 87.5% of the teneral tsetse and 55.5% of non-teneral tsetse flies. Among 160 bloodmeals of G. m. submorsitans collected from the upper Didessa river valley 54.4% (87/160) were with identifiable hosts, of which warthog accounted for about 52.9 (46/87) of meals, whereas human and buffalo blood accounted for about 21.8% (19/87) and 12.6% (11/87) of the meals, respectively. Others like giraffe, goat, cattle and elephant accounted for few bloodmeals. Thus warthog appeared to be the major host for G. m. submorsitans in the study area.

Key words/phrases: Bloodmeal, elisa, Ethiopia, Glossina, Traypanosomosis

 

Food and feeding habits of the catfish, BAGRUS DOCMAK (FORSSKAL, 1775) (Pisces:Bagridae) in Lake Chamo, Ethiopia

Hailu Anja 1 and Seyoum Mengistou 2

1 Awassa College of Teachers’ Education, PO Box 115, Awassa, Ethiopia

2 Department of Biology, Faculty of Science, Addis Ababa University 
PO Box 1176, Addis Ababa, Ethiopia, E-mail: [email protected] 

ABSTRACT: The natural food of the catfish Bagrus docmak was studied from February 1995 to February 1996 in Lake Chamo, Ethiopia. The stomach contents of a total of 534 fish samples, ranging in size from 33—99 cm fork length (LF) and 500—17400 g in total weight (WT) were investigated. The diet of B. docmak was composed of insects (larvae, nymphs and adults), aquatic snails and different fish species such as Synodontis schall, Labeo horie, Oreochromis niloticus, Barbus sp. and Hydrocynus forskalii. Juvenile B. docmak (< 40 cm LF) ingested more insects than fish while older fish were largely piscivorous, with fish constituting more than 98% of their diet by weight. S. schall was the most important prey and occurred in more than 81% of all the stomachs of large B. docmak. The prey:predator (S. schall:B. docmak) length ratio varied between 1:2 and 1:6. The feeding habit of B. docmak in Lake Chamo is compared with that of other tropical African lakes that have similar ichthyofauna.

Key words/phrases: Bagrus docmak, Ethiopia, Lake Chamo, prey:predator ratio, Synodontis schall

BREEDING SEASON, MATURATION AND FECUNDITY OF OREOCHROMIS NILOTICUS L. (PISCES: CICHLIDAE) IN LAKE CHAMO, ETHIOPIA

Yirgaw Teferi 1, Demeke Admassu 2 and Seyoum Mengistou 2

1 National Fisheries and other Living Aquatic Resources Research Centre

earo, PO Box 64, Sebeta, Ethiopia

2 Department of Biology, Faculty of Science, Addis Ababa University

PO Box 1176, Addis Ababa, Ethiopia

ABSTRACT: The reproductive biology of Oreochromis niloticus in Lake Chamo, Ethiopia was studied from samples collected every month for a period of thirteen months between March 1996 and March 1997. A total of 1349 fish ranging in size from 125 to 610 mm total length (tl) were caught using gill nets (120, 140, 200 and 240 mm, stretched mesh). The mean monthly gonadosomatic index (gsi) of the males ranged from 0.21 to 0.61 whereas that of females ranged from 0.75 to 1.61. Higher gsi values were observed between March and June for females and between March and May for males. The pattern of gonad development for both sexes was more or less similar. Ripe males occurred at high frequency (ranged: 39—60%) between March and May whereas high frequency of ripe females (ranged: 47—53%) occurred between March and June. Thus, it was concluded that O. niloticus in Lake Chamo spawns throughout the year with peak breeding activity between March and June. The smallest sexually mature female was 385 mm tl, whereas the male was 395 mm tl. However, the 50% maturity length was about 420 mm tl for both sexes. O niloticus were all mature above 500 mm tl. Mean fecundity of O. niloticus was 2493 ± 300, N = 209 (ranged: 390—540 mm tl and 1300—2650 g total weight). The smallest count was 1047 (fish length = 420 mm tl) whereas the largest was 4590 (fish length = 510 mm tl). In general, fecundity of O. niloticus in Lake Chamo was linearly related to total length (F = 201.85tl — 6801), total weight (F = 1.91tw — 1197.8) and gonad weight (F = 55.59gw + 467.2).

Key words/phrases: Ethiopia, Lake Chamo, Oreochromis niloticus, reproduction

EFFECTS OF DIETARY CRUDE PROTEIN LEVEL ON THE DIGESTIBILITY OF NUTRIENTS, EXCRETION OF FECAL N AND URINARY N-FRACTIONS AND THE KINETICS OF 15N LABELED UREA IN GROWING MALE GOAT KIDS

Tegene Negesse 1, M. Rodehutscord 2 and E. Pfeffer 3

1 Department of Animal Production and Rangeland Management

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

2 Institute of Nutrition Sciences, University of Halle-Wittenberg

06099 Halle, Germany

3 Institute of Animal Nutrition, Bonn University, D-53115 Bonn, Germany

ABSTRACT: A feeding trial was conducted with 16 male Saanen kids (4 kids/treatment) weighing 19.0 ± 1.8 kg in the middle of which they were subject to a metabolism trial and kept in cages for 14 days for a quantitative 10 days collection of excreta. Kids were fed a constant amount of the four diets formulated out of molassessed wheat straw [55 g crude protein (cp) per kg dry matter (dm)] and pelleted concentrates having 87, 117, 144 and 176 g cp/kg dm. They were injected about 100 mg of 15N-labeled urea into the jugular vein at the beginning of the collection period. Nutrient digestibility, fecal N and urinary N-fractions, N and 15N balances were measured; irreversible loss (il) of urea from the body urea pool (bup) and the kinetics of N in the body calculated. Increasing dietary cp increased digestibility of organic matter (om) from 71% to 80% and of crude fiber (cf) from 28% to 58%; excretion of fecal N by 56%; of urea N by 93%; proportion of N of urea, allantoin, creatinine, uric acid plus hypoxanthine in urinary N from 31% to 66%, 12% to 22%, 3% to 12%, and by 1.7%, respectively; irreversible iron (il) of N from 1.98 to 12.24 g/d; transfer of urea to gastro-intestinal tract (git) from 1.58 to 6.69 g/d (i.e., equivalent to 80% to 55% of il); recycling of the degraded urea N to metabolic pool from 1.22 to 6.12 g/d; but it has decreased the proportion of retained N of bup origin from 38 to 30% and excretion of urinary non-urea N from source other than bup was constant. Excretion of urea is the mechanism by which goat kids adapt to variable supply of dietary protein. Excretion of fecal N was more closely related to dm intake, while that of urea N to dietary cp level and of purine derivatives (pd) to digestible om intake.

Key words/phrases: Goat kids, 15N kinetics, N-metabolism, protein, urea 

Short communication

THE POTENTIAL MUTAGENIC EFFECT OF THE LEACHATES OF RURAL SOLID WASTE LANDFILL ON ALLIUM CEPA (L.)

Bakare, A. A. Adekunle

Genetics and Cell Biology Unit, Department of Zoology, University of Ibadan

Ibadan, Nigeria, E-mail: [email protected] 

ABSTRACT: The potential mutagenic effect of raw and simulated leachate from a rural refuse dump site at "Odo Oba", in South-West Nigeria, on Allium cepa was evaluated. Roots of Allium at about 2—3 cm long were treated with 1%, 2.5%, 5%, 10% and 25% concentrations of the leachate samples for 24 hr. These were then used to prepare slides for the observation of chromosomal aberrations and frequency of mitotic division. Different types of chromosomal aberrations were induced and this was significant at P < 0.05 level at all doses tested except at 1% concentration of the simulated leachate. There was also reduction in the number of cells dividing at the tested concentrations when compared with the control. The observed effects may be provoked by genotoxic chemicals found in the leachate samples. This finding may be useful in the practical aspects of waste management and for the assessment of the hazardous effects of the chemicals in the leachate from solid waste dumpsites.

Key words/phrases: Allium cepa, chromosomal aberration, mitotic index, mutagenicity, rural refuse leachate