Strain differences in illumination-dependent structural changes at mouse photoreceptor ribbon synapses.
Photoreceptor cells encode light signals over a wide range of intensities with graded changes in their membrane potential. At their highly specialized ribbon synapses they transmit the signals to the postsynaptic neurons by the tonic release of glutamate, which is continuously adjusted to changes in light intensity. Such a level of performance requires adaptive mechanisms, and it is suggested that illumination-dependent changes in ribbon shape and size are one of these adaptive processes. In this study we compared structural properties of synaptic ribbons under various illumination conditions between three mouse strains: the pigmented C57BL/6 and the two albino strains Balb/c and B6(Cg)-Tyr(c-2J) /J (coisogenic to C57BL/6). In addition, electroretinograms (ERGs) recorded in the same groups were compared. In the C57BL/6 mouse a change in illumination did not result in structural alterations of the synaptic ribbon. Similarly, in the B6(Cg)-Tyr(c-2J) /J mouse only minor structural changes were detected. In contrast, the state of adaptation had a large influence on the ribbon structure of the Balb/c mouse. The ERG recordings showed only small functional differences between C57BL/6 and B6(Cg)-Tyr(c-2J) /J mice, but the retinal function of Balb/c mice was strongly compromised. We conclude that illumination-dependent changes of photoreceptor ribbon structure differ between strains and thus cannot be regarded as a general mechanism for light adaptation.
Department of Biology, Animal Physiology, FAU Erlangen-Nuremberg, 91058 Erlangen, Germany.
Michaela
M
Fuchs
Anna
A
Sendelbeck
Jenny
J
Atorf
Jan
J
Kremers
Johann Helmut
JH
Brandstätter
D000221:Adaptation, Ocular; D000818:Animals; D003623:Dark Adaptation; D004596:Electroretinography; D005071:Evoked Potentials / Q000528:radiation effects; D005136:Eye Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D008029:Lighting; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008855:Microscopy, Electron, Scanning; D014442:Monophenol Monooxygenase / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D012160:Retina / Q000166:cytology*; D013569:Synapses / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure
C113688:Bsn protein, rat; C486016:Ctbp2 protein, rat; D005136:Eye Proteins; D009419:Nerve Tissue Proteins; D014442:Monophenol Monooxygenase