General Biology

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The Application of the Enzyme Linked immunosorbent Assay (Elisa) In t'he Sehodiagnosis of Schistosoniasis
(Addis Ababa University, 1980-06) Taticheff, Seyoum; Melamed, M.D. (PhD)
A description of the schistosome parasite and its life cycle, its immunology and the fact that the parasite causes a disease of world-wide significance is made. The existing distribution of schistosomiasis in Ethiopia and its recorded vectors and the possibility that the disease may rapidly be coming a public health threat is mentioned. As possible tools for the sero-diagnosis of schistosomiasis, short accounts of the skin test, the indirect immuno-fluorescence test, the complement fixation test and the radio-immunoassay are gi ven. '['he enzyme linked immunosorben t assay (ELISA) as a promising diagnostic method has been elaborated '['he primary objective of this study was the assessement of ELISA as a sero-epidemiologic tool for schistosomiasis. In this study, samples from S .mansoni and- S .haematob.iill!! endemic areas and samples from non-endemic area were used. ~ljicroscopic examination of stool and/or urine ELISA on blood samples and skin tests for schistosomiasis were done. ELISA with a sensitivity of 86.86 to 96% and a specificity or 80 to 81% was preferred as a sero-diagnostic method for schistosomiasis from: the conventional microscopy where sensitivity was 101'1 and from the intradermal test which showed poor specifici ty (40% posi ti vi ty was observed in" non-endemi c area).
An Eco-Physiological Study of Cultivated Barleys in welmera
(Addis Ababa University, 1980-06) Asfaw Zemede; Berhan Tewolde (PhD); Egziabher Gebre (PhD)
In eco-physiological studies, problems that originate from field , , observations aretack~d both through field work and laboratory studies. This paper presents e study made on the eco-physiology of barley (Hordeum Sect. Cerealia Ands.) cultivars cultivated in Welmera, Shoa. Field studies, i.e. observations, discussions with farmers,· seed,; plant and soil sample collections and laboratory experiments and analyses, i. e. pot experiments in the greenhouse on 9 barley cuI ti vars each cultivar planted in the 9 soils from the areas where the cultivars Vlere collected and mechanical and chemical analyses of the soils were carried out in the years 1979 and 1980. The data gathered were subjected to various statistical treatments, 1'he results showed that there are wide differences both among the 9 soils and among the 8 cultivars of barley which were successfully grown. One cultivar failed because of poor germination, The differences observed among the soils were both physical and chemical, some being more fertile and hence more suitable for most cultivars while a few were extremely poor and unsuitable for most cultivars except those that appeared to be specially adapted. The barley cultivars studied showed wide differences in their responses to these soils and their distribution within Vlelmera appeared to be largely a resul t of the differences in edaphic factorcs. Soil physical condi tiona, level of the available forms of cationic nutrients and some important anions, ego phosphorus, and toxic heavy metals appeared to have stroncor impact on the pGrformancHu of barley cultivars than other factorso Tl~ climatic and the socio-economic factors also seenl to have some role, but of a smaller magnitude, in determining cultivar distribution within the area studied.. The soils based on their fertility in decreasinc order were Foeta, North of Holetta,_ Suba Road, Berfeta 2, 'ilelmera Choke, I'lachacha 2\ Wachacha I, Bedi and Berfeta 1. Several specific hypotheses were generated and the need for further studies shown: - Baleme requires a soil 101'1 in clay and high in calcium carbonate, Kesele requires a soil with 101'1 cl~y and high sand contents, Netch Gebs is sensitive to heavy metal toxicity, Semereta is sensitive to both physical, requiring soils with clay content createI' than about 26%, and chemical conditions of soils, i.e. it is an indicater of overall fertility of soils, Enat Hetch Gebs requires soils with high proportion of exchangeable magnesium to exchangeable calcium, Keye Gebs requires soils that are rich in nutrients, Mouga requires soils that are well drained and rich in nutrients and Senef-Kollo requires soils with high exchangeable cations particularly exchangeable calcium and magnesium.
A Comparative Study on the Effect of Gulein Three Areas: Sendafa , Debre Berhan and Fiche
(Addis Ababa University, 1980-06) Kifle, Anketsebrhan; W. Yohannes, Legesse (PhD)
Samples were collected from the three sites: Sendafa, Debte Ilerhan and Fiche to study changes induced by "Guie" practice. 'l'he chemical and physical changes as well as the growth of barley in these soils was compared for the three sites. The laboratory study involved the determinations for particle size distribution, the ignition experiment, the determination for changes in orga~ic carbon, total nitrogen, available phosphorous, pH, eleotrical conductivity, carbonates, the exchangeable c~tions, the cation exchange capacity properties of the soils.' Plant analysis for percent nitl'ogen and percent phosphorous was determined for barley grown in the greenhouse experiment. In the Greenhouse experiment the height of barley plants was recorded as well as the counts on emergence, heading and fresh and dry weights and weed score was done to evaluate the differences between the three sites. The results from the laboratory and greenhouse studies showed similar variations among the treatments of the three sites. 'rhe interior heap layers exposed to high temperatures both the negative and positive effeots from "Guie" practice. The main positive effects were found to be the increase in available phosphorous and the change from find to sand sized particles. In contrast the main negative effects were found to be the losses in organic carbon and total nitrogen. The growth study in the greenhouse experiment also showed variations only among the treatments. The best growth was found to be in the mixed treatment where optimum condition was a.ttained by mixing all the different Guie affec ted and unaffec ted soils .•
A Comparative Study on the Effect of “Guie” in Three Areas: Sendafa, Debre Berhan and Fiche
(Addis Ababa,University, 1980-06) Kifle, Anketsbrhan; Bekele, Taye
Samples were collected from the three sites: Sendafa. Debre Berhan and Fiche to Study Changes induced by ‘’Guie” Practice. the Chemical and Physical Changes as well as the growth of barley in These Soils was Compared for three Sites
Identification of Stereotypes and Assessment of Multiple Drug Resistance in 360 Shigella Isolates
(Addis Ababa,University, 1980-06) Gebre, Afeworki
Three hundred and sixtyur ban and rural Shi gellae isol ates were analysed in r espec t t o scr ogr oupins , ser otypinS , biochemotyping and drug resistance . S. f l exne r i (50 . 55~ ) was mos t common , f ollowed by S dysente riue ( 32. 78%), S boydii ' ( 11 . 39% ) and S- sonnei ( 5 .28 %). I s olation r ates of dysente nriac , S- flexneria and S' sonnei we r e comparable in r ur al and urban areas , except f or S. boydii which is more common in urban areus (si gni fic a n t at P=O. 05 ) .
An Ecological Study of the Montane Grassland Vegetation in Wolmera Woreda
(Addis Ababa,University, 1980-07) Woldu, Zerihun; Berhan, Tewolde
A study of the grasslands in wolmera wereda was made from August 1979 to Octobr 1979.one hundred And twenty stands were systemat ically sampld and the occurece of 118 pl specis in t e stands rcorded . 'orne envir o mental factor s e r e r ecorded and soi l sampls collec e •
An Ecological Study of the Montane Grassland Vegetation in Wolmera
(Addis Ababa,University, 1980-07) Woldu, Zerihun
A study of grasslands in wolmera wereda was made from August 1979 to october1979.one hundred and twenty stands were Stands recorded
A S'l'udy on the STructure of a Hon'fane Forest - the Menagesha State Forbst
(Addis Ababa University, 1980-07) Demissew Sebsebe; Berhan Tewolde (PhD)
In order to have a better management for existing forests, and to reafforest devegetated areas an ecological study of forests is indispensable. Menagesha State Forest which is one of the few remaining forests in Central ~thiopia was chosen for such a study. In the Nenagesha State E'orest, 50 stands were chosen by systematic sampling. All the plants found in each stand were recorded and in all 60 species of plants were identified. Soil samples from the surface, 10, 20, 30, 40, 50, and 60 cm. depths were taken and analysed in the laboratory for conductivity, pH, cations (calcium, magnesium, potassium and sodium). Heasurements of slope, aspect and altitude were taken in the field. The 50 stands were classified using the Association Analysis technique in the University of Nanchester Hegional Computer Centre, resulting in 16 groups of stands (A, B, C, D, E, F, G, H, I, J, K, L, M, N, 0 and P). I!:ach group of stands was compared with all other groups of stands to see whether there are statistically significant variations in their environmental factors (conductivity, pH, cations, slope and altitude) between them using the t-test. The results of the t-test showed that there are two more or less distinct categories of vegetation. The first category identified by + Erica arbore~ include group of stands that have a poor nutrient status, a deeper soil, and a flatter habitat than the group of stands in the - Eri.£!', category. The - ].;rica group of stands have soils that are relatively nutrient rich and have shallower depths. This group of stands also occupy steeper slopes than + t:ric,! category. Based on the findings of the study it is suggested that the conservation of tho forest has to continue; the nutrient poor + Erica areas could have improved nutrient stands if shrubs including Kolfa (Hukeguracha) followed by Hae~ lanceolata and/or Carissa edulis that tend to increase soil nutrients are planted, and planting conifers whicll increase rates of nutrient loss is avoided.
An Ecological Study of the Hontane Grassland Vegetation in Holmzra Horeda
(Addis Ababa University, 1980-07) Woldu Zerihun; Berhan Tewolde (PhD)
A study of the erasslands in \/olmera \Iereda was made from A August 1979 to October 1979. One hundred and twenty stands were systematically sampled and the occurence of 118 plant species in the stands recorded. Some environmental factors were recorded and soil samples collected. Computations of the clas~ification of the vegetation using the Association Analysis Technique was made at the University of Manchester Regional Computer Center. Four distinct vegetation types were tentatively identified from the dendrogram at higher levels of the classificatory hierarchy and were statistically tested for significant contrasts. Gradients of soil pH, conductivity, hue, and cation content are positively correlated with a decreasing drainago gradient and these are negatively corrclatod with an increasing grazing gradient.
A Palynological- Taxonomic Study of the Genus Asystasia and A Plynological Study of Some Related Genera.. In the Acanthaceae
(Addis Ababa University, 1982-06) kelbessa, Ensermu; Hedberg, Prof. Olov
The pollen morphology of ni neteen s pec i es of Acanthaceae : nine of A5ystneia and ten of five other genera ha ve been inves tigated usinG l i ght and/or electron mic roscope s . The five gener a Gr a p tophyllurn , Jacobini a, Jus t i c i a , Mackays and ~~~ cun be sepa r ated fr om each other by the number and characte r of a pertur es , exine st r at ifi cat i on and/or by the natur e of the " trem" a r ea". The study has r evealed tha t the pollen gr ains of the ge nus H6yst ns i a a r e th r ee - pora te and the surfa ces a r e provi ded with nine colpoid streaks . The sexine i s smooth. The spec i es can be separ ated from each other by the di ffe rence i n the pr omine nce of the colpoi d s treaks and by the nature of t he sexi nUQue region a r ound the por e . A detailed study of the pa n- t r opi c al spec i es ~ . gangetica (L . ) T. hnders . has r esulted in its s ubdivis i on into two geogr aphic a l s ubspec i es on the basi s of corolla and s tyle and s t i gma l engths . It i s also s uppor ted by poll en s i ze and seed morphol ogy . The subspec i es with long coroll a a nd s tyle and s tigma i s desi gna t ed as subs p . gpnget ica and the one with shor t corol la and style and sti gma 6ubsp . mic r antha . The distribution of both taxa i s i llustr ated .
A Palyological- Taxonomic Study of the: Genus Asystmlia and A Palynological S'rully of Some related Genera in the Acanthaceae
(Addis Ababa University, 1982-06) Kelbessa, Ensermu; Hedberg, 0lov (Professor)
The pollen morphology of nineteen species of Acanthaceael nine of AsystaEia and ten of five other genera have been investigated using light and/or electron microscopes. The five genera Graptophyllum, Jacobinia, Just;'cia, Hacka~ and styll~~ can be separated from each other by the number and character of apertures, exine stratification and/or by the nature of the "trema area". l'he study has revealed that the pollen grains of the genus Asystasia are three-porate and the surfaces are provided with nine colpoid streaks. The sexine is smooth. The species can be. separated from each other by the difference in the prominence of the colpoid streaks and by the nature of the sexinuous region around the pore. A detailed study of the pan-tl'opical species Ii. gangetica (L.) T. Anders. has resulted in its subdivision into two geographical subspecies on the basis of corolla and style and stigma lengths. It is also supported by pollen size and seed morphology. The subspecies with long corolla and style and stigma is designated as subsp. gangetica and the one with short corolla and style and stigma subsp. micrantha. The distribution of both taxa is illustrated.
The Effect of Different Soils on the Gorwth and Yield of Some TEf Cultivars
(Addis Ababa University, 1982-06) Isak Sirak; Berhan Tewolde (PhD)
Observation of yields of tef tested in national yield trials (NYT) at different sites and at different times have given variable results. It ~/aS assumed that differences in the tef yields ~Iere probably due to environmental factors. Therefore, eleven cultivars (of 1980-81 in the NYT) were seeded on six different soils, collected from different places, in plastic pots ",ith a capacity of 2 kilograms in a randomized complete design in two blocks and qrown in a areen house where environmental conditions such as humidity, sunshine hours, temperature, were identical for all the treatments. The pots containing the plants were watered as required with distilled water until the olants achieved physiological maturity. During the growth period, various parameters such as height, tiller number, days to heading were recorded and quantified. After harvest dry weight and seed weight of cultivars \~ere measured. The data obtained were subjected to various statistical analyses. The results indicated that. the tested tef cultivars adapted better in soils dominated by silt along with aC'equate quantities of available nitrogen and potassium.
The .in and Vivo Nitrate Reeducates Activity in Tef (Eragrostis Tef (Zucc.) Trotter) Under Different Assay Conditions
(Addis Ababa University, 1982-06) Negash, Legsse; Zeleke, Asfaw ( PhD)
The presence, substrate inducibility and regulations of the enzyme nitrate reductase (NADH: Nitrate Oxidoreductase, . . E.C. 1.6.6 .• 1)(NR) of both dark-grown and light-grown tef plants (Eragrostis ~ (Zucc.) 'rrotter) were studied. The relative merits of the in vivo and in vitro methods of assay for the enzyme were evaluated. Major factors affecting nitrate reductase activity and the distribution of the enzyme in both the dark- and light-grown plants were investigated. Nitrate and urea induced the formation of nitrate reductase in 5-day-old dark-grown tef plants; and the activity of the enzyme was predominantly associated with the roots. In the glasshouse-grown plants, however, both the ammonia-type and the nitrate-type nitrogen sources elicited NR activity although nitrate was still superior in enzyme induction; and the leaves were found to be the major centeres for nitrate reduction. A pH of 7.6 was found to be optimal for an in vivo NR activ~ty of tissue obtained from leaves of light-grown tef plants. Diurnal variations in NR activity were observed, with peak activity at mid-day, suggesting that the enzyme is under the control of light •. Logging tef plants for 11 days after 10 days of maturation did not substantially affect the enzyme activity. It was observed that tef seedlings discriminate between ammonium and nitrate during their early stages of development by preferentially assimilating the former when given in combination with the latter. These findings suggest that tef plants can, at least at their early stages of development, successfully withstand reductive soil conditions.
Gtaphylogocous Aureus from Surgigal Departments of Hosptals I Naddis Ababa Staff Carriage Rates, Environmental Contamination and Antibiograms
(Addis Ababa University, 1982-06) Tewodros, Wezenet; Gedebou, Messele (PhD)
Six hundred strains of Staph;zlococ£~ aur:::.us were isolated from the Black Lion Teaching Htispital Surgical Department environment (353), from the nose, wrist and arm skin of surgical staff of six selected hospitals in Addis Ababa (161) , and a non~hospital population (86). Out of 454 surgicnl staff examined, 139 00.6%) were nasal carriers and 22 (51%) of 43 nasal carriers also ," carried the organism on their skin. Carrier rates among different catesories of surgical staff varied; the hichest rate was amoni; surGeons (56%). The non-hospital population comprised 328 students, and 2i.6% of them were nasal carriers. Of 55 non-hospital nasal carriers 15 (27%) were found to carry the or;:;anism on their wrist skin, '1.'he carrier rate of the non~hospital population was significantly lower (F( 0,01) than that of the hospital population. 'rhe rate was hiGher in males than in females in hospitals, but not in the non-hospital population. The environment of operating rooms and surgical wards of Black Lion Teaching Hospital was highly contaminated wi th StaI?h:.. ~eus , Over 75% of air samples and 3'/% of dust ._, • I samples were posltlve, -VIII~ .The non-hospital isolates were much more sensitive to antibiotics than the hospital isolates. Over 96% of nonhospital isolates were sensitive to nine antibiotics, but only 37% and 74% were sensitive to penicillin and tetracycline respectively. About 90% of all isolates were sensitive to clindamycin, cephalothin, gentamicin, kanamycin and trimethoprim-sulfamethoxazole, and none was resistant to vancomycin. The majority of hospital staphylococci, 87% of surGical staff isolates and 60% of environmental isolates were resistant to penicillin, and over 60% of both types of isolates resistant to tetracycline. About 94% and 88% of hospital and non-hospital staphylococci, respectively, were resistant to at least one antibiotic. Multiple resistance among non-hospital staphylococci was remarkably lower (2.3%) than that of hospital isolates (over 37%). Different types of antibiograms were detected: 66 among environmental, 36 amons suro;ical staff, and 6 among non-hospital isolates. These varied between resistance to one and to nine antibiotics. Combined resistance to penicillin and tetracycline was the most frequent pattern. The findings were compared with other reports from Ethiopia and elsewhere. Based on the present study and other similar recent reports·from Addis Ababa, tile need for strict antibiotic policy, continued surveillance, assignment of infection officers and maintenance of cleanliness of the hospital environment have been stressed.
A Preliminary Study of the Fungal Flora of Ethiopian Cereal Grains with Special Ehphasis on the Prevalence of Toxicogenic Groups
(Addis Ababa University, 1982-06) Abate Dawit; Abegaz Berhanu (PhD)
The in Vivo and in Vitro Nitrate Reductase Activity in Tef (Eragrostis Tef (Zucc.) Trotter under Different Assay Conditions
(Addis Ababa,University, 1982-06) Negash, Legesse
the presence , substrate ind cibility and regulatios of the enzyme ni trate reductase ( NADH : Nitrate Oxidored case , E . C. 1.6. 6.• )(NR) of b o h ark- grown and l igh - gro n tef plants ( Eragr osti s te f (Zucc . ) Trotter) were st died . The relat ive merits of the in vivo and i n vitr o methods of assay for t he en zyme we r e ev a l uated . Major fac ors affecting n i t r a e r educta se act ivit y and the distr ibution of the e zyme in both t h e dark- and light- grown plants wer e investigated .
Adoptive Transfer of Lymphocytes and its Role in Protection against Schitosoma Mansoni Infection in Arvicanthus Species
(Addis Ababa,University, 1982-07) Mengestou, Seyoum; Belehu, Ayele (PhD)
Adoptive transfe r o f pr o t f!c tio n f rom i nf 'ctcd don or J.rvicanthus !.E. rats t o uninfec t ed r c cl pient~ was t!l ttt!mpted by va ~ y ing s omc pilram ~~b.! rs such a s the i ntl:ction pe riod o f donor r ats a nd the tine of tra ns f L; r r e l ati ve to c ha l ll.;nge . Concurre nt inve stigation o n t he e ffect of h~'~ r o l o g ous infec tion and fra ctio na tion o f c e ll s 11(l!:; ~lso carri(:d out. It wa s f ound tha t cPlls from 2 mo n th- lnfLctcd dono rs had high ability t o tra n s f c r r e sista ncl.! to rc:d,p i €..nt r ats while c el ls f r om 10 75 a nd 3 month- infL:ctcc' Jonor s s howed pa rtial a bi l ity and tho s e fr om 2 . 5 mo nth- infl:ctcd donors showed an une xpe cted inhi b i t ory e f fect on t ransfe r r e cipi e nts. Transfe rs d o ne c l o s e t o ch a ll L:ng~ nay c onfe r almo s t c omple t e i mmunity t o r e cipie nt rats , \0,:.':"_ Heterologous c e stode infe ction in t hes(! r-~ts appt:"!<'Ir t o play t!I s econdary r o l e in pro t ecting aguinst ,5 •• mansoni infe ctions, while it wa s a l so f ound t hat u nfr~Ltio n a t ed cells have mo r e ability t o tr n ~sf e r r c sis t~ n cc than fr actio na t ed ce lls . Po s s ible i~mun o l o gic a l me cha nisms involved dur i ng t hese e ve nts and the pr actica l s ignifica nce of thL: Hark arc briefly discuss ed .
Adoptive Transferor Lymphocytes And Its Role In Protecton Against Schist soma Manzoni Infection In Arvcicanthus Sp Rats
(Addis Ababa University, 1982-07) Nengestou, Seyoum; Belehu, Ayele (PhD)
adoptive transfer of protection from inducted donor acanthus !!l? rats to uninstructed recipients was attempted by va~yj.ng some parameters such as the inf8ction period of donor rats and the time of transfer relative to challenge. Concurrent investigation on the effect of.': 11ctorologous infection and fractionation of cells "idS also carried out. It ",as found that cells from 2 month .. ;.nf8ctcd donors had high ability to transfer resistance to recipient rats ) while cells f"om 1. 75 and 3 month-infected donors shO\.,ed partial abi Ii ty and those from 2.5 mont11",infected donors sho"led an unexpected inhibitory effect on transfer recipients. Transfers done close to challengu day confer almost complete immunity to recipient rCl"ts, \,:,.~, .. '" Heterologous cestode infection in these rc:ts appear to playa secondary role in protecting against Eo !~ansoni infections, ,.,hile it ",as also found that unfrilctionated cells have more ability to transfer resistance thul1 fractionated cells. Possible immunological mechanisms involvGd during these events ~nd the practical significance of the work are briefly discussed.
Comparative Studies on the Ecology of Bi0mphalaria Pfeifferi (Krauss, 1847) in Non Endehic and Endehic Areas of Schistosoma Hansoni (Sambon. 1907) in Ethiopia.
(Addis Ababa University, 1983-02) Lakew Mekuria; Tedla Shibru (PhD)
The region of Debre Berhan, Where schistosomiasis is not endemic, Vias compared with a' well established focusof S.mansoni, vlonji , with regard to climate, snail habitat s and snail differences in susceptibility and growth rate. In general rain and changes associated with it have influqnce on the snail yopulation but this does not account for the lack of endemic schistosomiasis. Snails from both areas were equally susceptible to infection with §.mansoni. The low mean temperature in Debre Berhan increased the incubation period of the parasite. Mortality rate of Debre Berhan snails was higher than th~£e of wonji snails while the growth rate was vice verSI1. Despite the relatively unfavourable conditions, the possibility of introduction of schistosomiasis to Debre Berhan as a result of environmental modifications that may bring changes in human activities can not be discounted.
The Effects of Hypoxia and Hypercapnia o n plasma Renin Activity in the Rabbit
(Addis Ababa University, 1983-05) Negatu, Zleleke; Okong'o, Owino (PhD)

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