Functional properties of the retina in a cave-dwelling moth (Triphosa dubitata)

Jamski pedic (Triphosa dubitata, Linnaeus 1758) je vešča, ki večino svojega življenja preživi v jami. Pri zimskem (hibernirajočem) stadiju smo pričakovali redukcijo strukture in funkcionalnih lastnosti mrežnice. Z uporabo histoloških (svetlobna mikroskopija) in elektrofizioloških metod (ERG, znotrajcelične meritve z ostro elektrodo) in primerjavo s poletnim stadijem drugih vrst vešč smo raziskali zgradbo očesa in lastnosti omatidijev, temperaturno odvisnost hitrosti očesa ter pasivne električne lastnosti membrane, hitrost, informacijsko kapaciteto in spektralno, polarizacijsko ter intenzitetno občutljivost fotoreceptorjev jamskega pedica. Pri zimskem stadiju jamskega pedica nismo opazili zmanjšanja rabdoma ali funkcionalnosti fotoreceptorjev. Hitrost fotoreceptorjev (kotna frekvenca) in informacijska kapaciteta sta primerljivi z drugimi nočnimi vrstami. Pri sorodnih vrstah je hitrost vida naraščala s temperaturo, vendar le do ~ 30 ␃. Spektralni vrh dolgovalovnih fotoreceptorjev je pri zimskem stadiju jamskega pedica pri 505 nm, v primerjavi z ostalimi veščami, ki imajo vrh pri ~520 nm. Fotoreceptorji vešč v predelu dorzalnega obroča imajo visoko polarizacijsko občutljivost in spektralni vrh v zelenem delu spektra, kar je prilagoditev na detekcijo vzorca polarizirane svetlobe tudi ponoči. Fotoreceptorji s potencialno visoko polarizacijsko občutljivostjo so prisotni tudi v distalnem delu običajne mrežnice. Pri jamskem pedicu smo opazili, da oko vsebuje manj omatidijev kot faset. Slika na mrežnici pedica je torej podvzorčena, kar je najbrž prilagoditev na manj ostro sliko v superpozicijskem očesu in izdatno prostorsko sumacijo na ravni optičnih internevronov.The Tissue (Triphosa dubitata, Linnaeus 1758) is a moth, which spends most of its adult lifetime in caves. In its winter (hybernating) stage we expected a reduction of structural and functional properties of the retina. We used histological (light microscopy) and electrophysiological methods (ERG, intracellular sharp electrode recordings) to determine the properties of tissue\u27s compound eye and ommatidia, temperature dependence of photoreceptor response, spectral, polarisation and absolute sensitivity, corner frequency, information capacity and passive electric properties of the photoreceptor membrane. The results have been supplemented with electrophysiological measurements on other moth species. In the Tissue, we didn\u27t find any observable reduction of rhabdom size and functional properties of the photoreceptors. The corner frequency and information capacity of tissue photoreceptors are comparable to other nocturnal species. In related species the speed of vision was increased with the temperature, but only up to ~30 °C. The absorption peak of the main photoreceptors in the tissue is at 505 nm, compared to ~520 nm in other moths. Moth photoreceptors in the dorsal rim area have high polarisation sensitivity and absorption peak in the green, which is an adaptation to the detection of celestial pattern of polarisation by night. Photoreceptors with potentially high polarisation sensitivity are present also in distal parts of the main retina. The eye of the tissue seems to have less ommatidia than facets. The image on the retina is thus undersampled, which is probably an adaptation to poorly focussed image in the superposition eye and extensive spatial summation at the level of the visual interneurons