search query: @supervisor Koskelainen, Ari / total: 34
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Author: | Vesterlund, Jenny |
Title: | Light adaptation in mouse cones |
Ljudadaptation i möss tappar Part 1 | |
Publication type: | Master's thesis |
Publication year: | 2009 |
Pages: | x, 61 Language: eng |
Department/School: | Elektroniikan, tietoliikenteen ja automaation tiedekunta |
Degree programme: | Elektroniikan ja sähkötekniikan tutkinto-ohjelma |
Main subject: | Lääketieteellinen tekniikka (Tfy-99) |
Supervisor: | Koskelainen, Ari |
Instructor: | Heikkinen, Hanna |
Electronic version URL: | http://urn.fi/urn:nbn:fi:tkk-012932 |
OEVS: | Electronic archive copy is available via Aalto Thesis Database.
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Location: | P1 Ark S80 | Archive |
Keywords: | cone light adaptation mice ERG alpha;- transducin knockout kon ljusadaptation moss ERG alpha: -transducin knockout |
Abstract (eng): | The rod photoreceptors are used for twilight vision and are saturated in daylight. Cones function in daylight and have not been found to saturate at any intensity available. Both rods and cones have the ability to regulate their operation as a function of the background illumination so as to extend their operational functioning range. General light adaptation manifestations can be observed as photoreceptor desensitization and photoresponse acceleration. In this study the function of cone light adaptation was studied. The electrophysiological changes in mouse cones caused by light adaptation were recorded as mass potential electroretinograms (ERG). The photoreceptor's response to light was pharmacologically isolated. In one case, the retinae were subjected to short stepped backgrounds (test flash applied 2 s after background onset) and in the othe case continuous backgrounds (test flash applied more than 2 min. after background onset). Characteristics of mouse cone light adaptation include retardation in time to maximum (tp) in both types of backgrounds. The sensitivity drop in the photoreceptors when subjected to increasingly stronger stepped background illumination was smaller than in the continuous background. The results obtained in these experimental conditions indicate that light adaptation functions differently in mouse cones compared to other species. Additionally, a mouse lacking functional rod phototransduction, due to targeted deletion of α transducin gene (Trα – / – ), was investigated in order to determine whether the Trα – / – mouse could be used as a model for cone phototransduction experiments. The photoresponse kinetics of the Trα – / – photoreceptors, though, were significantly retarded. Furthermore, the Trα – / – photoreceptors were somewhat more light sensitive than WT mouse cones, and highly more sensitive to adapting background illumination. |
Abstract (swe): | De fotoreceptorer, som kallas stavar, används för mörkersyn och är mättade i dagsljus. Den andra typen av receptor, tappen, funktionerar i dagsljus och man har inte funnit att den mättas vid någon tillgänglig ljusintensitet. Såväl stavar som tappar kan reglera sin funktion som en funktion av bakgrundsintensiteten. Detta för att kunna funktionera över ett större intensitetsspektrum. De allmänna karaktärsdragen för fotoreceptorernas ljusadaptation kan observeras som minskning i receptorns känslighet samt acceleration av fotosvaret. I denna studie har tapparnas ljusadaptation undersökts. De elektrofysiologiska förändringarna i möss tappar som beror på ljusadaptation registrerades som masspotential elektroretinogram (ERG). Fotoreceptorernas svar på ljus isolerades farmakologiskt. Näthinnorna utsattes antingen för bakgrundsillumination (icke kontinuerlig, stimulusljuset applicerades 2 s efter bakgrundsljuset tänts) eller kontinuerlig bakgrundsillumination (stimulusljuset applicerades 2 min efter bakgrundsljuset tänts). Resultaten indikerar att möss tappars ljusadaptation manifesteras som en retardation av tp (tid till maximum) i båda typerna av bakgrund. Resultaten från denna studie indikerar att ljusadaptationen fungerar olika i möss tappar jämfört med andra djurarters tappar. Därutöver undersöktes en mus, som saknade fungerande stav-fototransduktion (Trα – / – ), för att avgöra huruvida denna Trα – / – mus skulle kunna användas som en modell för experiment av tappars fototransduktionsfunktion. Fotosvaren var dock betydligt långsammare. Därtill var Trα – / – -fotoreceptorerna något mera ljuskänsliga jämfört med möss (av vild typ) samt betydligt mera känslig för adapterande bakgrundsillumination. |
ED: | 2009-10-19 |
INSSI record number: 38484
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