May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Rod Nuclear Architecture and Vision in the Evolution of Mammals
Author Affiliations & Notes
  • L. Peichl
    Neuroanatomy, Max Planck Institute for Brain Research, Frankfurt am Main, Germany
  • I. Solovei
    Institute of Human Genetics, Ludwig-Maximilian University Munich, Planegg-Martinsried, Germany
  • C. Lanctôt
    Institute of Human Genetics, Ludwig-Maximilian University Munich, Planegg-Martinsried, Germany
  • S. Kösem
    Institute of Human Genetics, Ludwig-Maximilian University Munich, Planegg-Martinsried, Germany
  • B. Joffe
    Institute of Human Genetics, Ludwig-Maximilian University Munich, Planegg-Martinsried, Germany
  • T. Cremer
    Institute of Human Genetics, Ludwig-Maximilian University Munich, Planegg-Martinsried, Germany
  • Footnotes
    Commercial Relationships  L. Peichl, None; I. Solovei, None; C. Lanctôt, None; S. Kösem, None; B. Joffe, None; T. Cremer, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 1263. doi:https://doi.org/
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      L. Peichl, I. Solovei, C. Lanctôt, S. Kösem, B. Joffe, T. Cremer; Rod Nuclear Architecture and Vision in the Evolution of Mammals. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1263. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : We have analyzed the rod chromatin arrangement in a range of mammals to elucidate the role of rod nuclear architecture for vision. In many mammals, the nuclei of rods look different from those of other retinal neurons by conventional light microscopy. Because the arrangement of chromatin is pivotal for nuclear function and highly conserved in evolution, modifications of the nuclear structure in rods are highly interesting.

Methods: : The distribution of euchromatin (gene-rich, transcriptionally active) and heterochromatin (gene-poor, transcriptionally inactive) was assessed using 3D-FISH with probes for marker DNA sequences and antibodies against marker histone modifications. We studied nocturnal and diurnal rodents, artiodactyls, and primates.

Results: : In all retinal cells except rods, heterochromatin adjoined the nuclear envelope and the nucleolus, while euchromatin localized in the inner regions of the nucleus (conventional pattern). In contrast, the small rod nuclei of all studied nocturnal species had an inverted pattern with heterochromatin in the center and euchromatin as an outer shell. The rod nuclei of all diurnal species had the conventional pattern and were larger, irrespective of taxonomic position.

Conclusions: : We suggest that the conventional pattern was altered in mammalian rods to facilitate nocturnal vision. Nocturnal retinae have high rod densities and hence thick outer nuclear layers. At the same time they critically depend on efficient light transmission through the retina. Smaller rod nuclei reduce retinal thickness, possibly improving transmission. Biophysically, the inverted nuclei with their dense heterochromatin core also may serve as series of lenses wave-guiding the light to the outer segments. Based on the general view that early mammals were nocturnal, we propose that the inverted pattern arose early in mammalian evolution, and that the conventional pattern was re-acquired by mammals that secondarily re-adopted a diurnal life style.

Keywords: photoreceptors • retina: distal (photoreceptors, horizontal cells, bipolar cells) • comparative anatomy 
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