Journal article
Retinal temporal resolution and contrast sensitivity in the parasitic lamprey Mordacia mordax and its non-parasitic derivative Mordacia praecox
The Journal of Experimental Biology, Vol.220(7), pp.1245-1255
2017
Abstract
Lampreys and hagfishes are the sole extant representatives of the early agnathan (jawless) vertebrates. We compared retinal function of fully metamorphosed, immature Mordacia mordax (which are about to commence parasitic feeding) with those of sexually mature individuals of its non-parasitic derivative M. praecox. We focused on elucidating the retinal adaptations to dim-light environments in these nocturnally active lampreys, using electroretinography to determine the temporal resolution (flicker fusion frequency, FFF) and temporal contrast sensitivity of enucleated eyecups at different temperatures and light intensities. FFF was significantly affected by temperature and light intensity. Critical flicker fusion frequency (cFFF, the highest FFF recorded) of M. praecox and M. mordax increased from 15.1 and 21.8 Hz at 9°C to 31.1 and 36.9 Hz at 24°C, respectively. Contrast sensitivity of both species increased by an order of magnitude between 9 and 24°C, but remained comparatively constant across all light intensities. Although FFF values for Mordacia spp. are relatively low, retinal responses showed a particularly high contrast sensitivity of 625 in M. praecox and 710 in M. mordax at 24°C. This suggests selective pressures favour low temporal resolution and high contrast sensitivity in both species, thereby enhancing the capture of photons and increasing sensitivity in their light-limited environments. FFF indicated all retinal photoreceptors exhibit the same temporal response. Although the slow response kinetics (i.e. low FFF) and saturation of the response at bright light intensities characterise the photoreceptors of both species as rod-like, it is unusual for such a photoreceptor to be functional under scotopic and photopic conditions.
Details
- Title
- Retinal temporal resolution and contrast sensitivity in the parasitic lamprey Mordacia mordax and its non-parasitic derivative Mordacia praecox
- Authors/Creators
- R.E. Warrington (Author/Creator) - The University of Western AustraliaN.S. Hart (Author/Creator) - Macquarie UniversityI.C. Potter (Author/Creator) - Murdoch UniversityS.P. Collin (Author/Creator) - The University of Western AustraliaJ.M. Hemmi (Author/Creator) - The University of Western Australia
- Publication Details
- The Journal of Experimental Biology, Vol.220(7), pp.1245-1255
- Publisher
- Company of Biologists
- Identifiers
- 991005544935807891
- Copyright
- © 2017. Published by The Company of Biologists Ltd
- Murdoch Affiliation
- School of Veterinary and Life Sciences; Centre for Fish and Fisheries Research
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- Citation topics
- 1 Clinical & Life Sciences
- 1.36 Ophthalmology
- 1.36.212 Genetic Retinopathies
- Web Of Science research areas
- Biology
- Zoology
- ESI research areas
- Biology & Biochemistry