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dc.contributor.authorVan Heerden, Daléne
dc.date.accessioned2009-02-18T06:08:25Z
dc.date.available2009-02-18T06:08:25Z
dc.date.issued2005
dc.identifier.urihttp://hdl.handle.net/10394/847
dc.descriptionThesis (Ph.D. (Zoology))--North-West University, Potchefstroom Campus, 2005
dc.description.abstractSuid-Afrika het beperkte waterhulpbronne, wat tot gevolg het dat die beskikbare water van baie hoe kwaliteit moet wees. Ongelukkig word die kwaliteit van ons hulpbronne deur antropologiese impakte bedreig. Tot baie onlangs het roetine monitering van natuurlike akwatiese stelsels slegs die fisieschemiese eienskappe in ag geneem. Biologiese monitering is egter baie voordelig omdat dit die algemene integriteit van akwatiese sisteme reflekteer. Dit kan soms en baie goeie aanduiding gee van die langtermyn-effek van korttermyn-impakte. Die doel van hierdie studie was om die effek van koper op sekere aspekte van visfisiologie gedurende laboratoriumblootstellings te ondersoek. Dieselfde parameters is ook in vis wat in riviere in die Noordwes Provinsie voorkom, gemeet om te bepaal of daardie parameters as moontlike biomerkers van hoe omgewingskopervlakke gebruik kan word. Gedurende die laboratoriumblootstellings (4 en 24 uur blootstelling, gevolg deur en 48 uur herstelperiode) op reenboogforel (Oncorhynchusmykiss), bloukurper (Oreochromis mossambicus) en vleikurper (Ti/apiasparrmanit)is die volgende resultate verkry: (1) Kieuskade, soos aangedui deur 'n verhogmg in &e gemiddelde epiteeldikte in sekondGre heulamellae (H,,) het na kort blootstehng aan hoe kopervlakke in a1 drie visspesies voorgekom. Die reaksie van 0. mossambi~zsa nd T. spamanii was minder intens en effe sta&ger as &i van 0. mykiss. Die verhogmg in epiteeldikte in die kieue het tot gevolg dat die vis hipoksiese toestande ondervind, soos aangedui deur die opeenhoping van Hipoksie-induseerbare faktor-la (HIF-la) in die heue van 0. mykh vroeg in &e blootstellingstydperk. Die epiteeldikte het egter na &e 48 uur herstelperiode weer verminder; (2) Induksie van metallotionien geenuitdruklung het tydens die blootstellingstydperk in &e heue van a1 drie visspesies voorgekom en weer na die 48 uur herstelperiode vlakke naby aan &e van kontrolevisse bereik. Die induksie in die lileuweefsel van was na 4 uur blootstelling in 0. mykiss en 0. mossambi~ws reeds statisties beduidend hoer as in kontrolevisse. Geen induksie is in die lewenveefsel van enige van &e visspesies aangetref nie; (3) Alhoewel koper by die water van blootstehngstenks gevoeg is, was daar geen beduidende koperakkumulasie in &e kieu- en lewenveefsel van enige van &e visspesies nie. Visse wat in Boskopdam, Potchefstroom gevang is het 'n hoer graad van heuskade gehad as in Klerkskraaldam, wat verklaar word deur die kopervlakke in &e visheue. Daar was egter geen beduidende verslul in &e metallotionieninduksie in &e lewer en heue van die visse van enige van die opnamepersele nie. Volgens 'n meervoudge regressie, kan die variasie in beide heu- en lewenveefsel deur die teenwoordigheid van kadmium by die persele verklaar word. Daar kan uit bogenoemde resultate afgelei word dat die graad van verdiklung van kieuepiteel 'n baie sensitiewe respons gedurende koperblootstelling is. Die tegniek is ook baie goedkoop en maklik om te gebruik. Metallotionieninduksie is 'n duurder tegniek en minder sensitief waneer &t in &e omgewing gebruik word. Dit is egter baie sensitief gedurende laboratoriumblootstellings aan koper. Hipoksie-induseerbare faktor-la proteinakkumulering kan moonthk 'n baie sensitiewe indikator van hipoksie, veroorsaak deur die verhogmg in die diffusie-afstand tussen bloed en water, in 0. mykiss wees. Die anthggaam teen Hipoksie-induseerbare faktor-la (HIF-la) in die Tilapia-agtige visse moet nog geoptimaliseer word. ABSTRACT During the laboratory exposures (4 and 24 h exposure with 48 h recovery after the exposure) on rainbow trout (Oncorhynchus mykiss), Mozambique tilapia (Oreocbromis mossambim~) and banded tilapia (TiIapia spamanil) the following observations were made: (1) Gdl damage, as indicated by an increase in the arithmetic epithelial thickness of secondary gll lamellae (H,,), occurred after short term exposure to high levels of copper in all three fish species. 0. mossambim and 7'. spamanii had slower and/ less intense responses to higher levels of copper than 0. mykiss. The increase in epithelial thickness in glls causes the fish to experience hypoxia, as indicated by the accumulation of Hypoxia inducible factor-la (HIF-la) in the glls of 0. mykiss, (2) Induction in metallothionein gene expression occurred in all three fish species, with levels in 0. mykiss and 0reo~-bromis mossambicus gdls being significantly higher than control values after only 4 h of exposure. Again T. qamanii reacted slower. No significant induction in metallothionein gene expression was detected in the liver of any of the species; (3) Although copper was added to the water of experimental tanks, there were no significantly higher levels of copper in glls and liver from any of the exposed animals at any time during the experiments. During the field based stuhes it was detected that fish from Boskop Dam, Potchefstroom had a higher degree of gll damage than fish from Klerkskraal Dam, Potchefstroom, which was explained by the levels of copper in the @s. There were no significant trends in either gll or liver metallothionein levels between any of the field sites, although accorhng to a multiple regression cadmium was indcated to have a influence on the metallothionein levels measured in fish from the selected sites. It could be concluded that determining the degree of thickening of gill epithelium is a sensitive indicator of the overall response of fish to especially copper exposure during this study. The technique is easy and inexpensive to use. Metallothionein gene expression is more expensive, and probably not sensitive enough when lower levels of metals are found in rivers. It is, however, very sensitive in experimental situations, under controlled circumstances. Although the accumulation of HIF-la promises to be a sensitive indicator of hypoxia, caused by the increased water-to-blood barrier due to increased gill epithelial thickness in 0. mykiss, properly working antibody against HIF-la in the Tilapiines still need to be investigated.
dc.publisherNorth-West University
dc.subjectBiomarkersen
dc.subjectMetallothioneinen
dc.subjectGill damageen
dc.subjectHypoxia-inducible factor-1α (HIF-1α) --en
dc.subjectCopperen
dc.subjectRainbow trouten
dc.subjectMozambique tilapiaen
dc.subjectBanded tilapiaen
dc.subjectOncorhynchus mykissen
dc.subjectTilapia sparrmaniien
dc.titleFish health, condition and biomarkers : a mechanistic and environmental perspective on copper pollutionen
dc.typeThesisen
dc.description.thesistypeDoctoral


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    This collection contains the original digitized versions of research conducted at the North-West University (Potchefstroom Campus)

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