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Constant lens fiber cell thickness in fish suggests crystallin transport to denucleated cells

Kozłowski, Tomasz M. LU and Kröger, Ronald H.H. LU (2019) In Vision Research 162. p.29-34
Abstract

The crystalline lens of the vertebrate eye grows throughout life. This growth may be enormous in fish, while the lens must be functional from larva to adult. During growth, the fiber cells of the lens must increase the concentration of specific proteins (crystallins) in the cytoplasm to increase refractive index. However, the bulk of the fiber cells in a vertebrate lens are denucleated and have no organelles to synthesize proteins. To study how this problem is solved, we first measured lens fiber cell thickness in the Nile tilapia, a teleost fish. In the lenses from 25 fish, in two size groups, fibers were considerably thinner than in other vertebrates. Fiber thickness was about constant along the radius of the lens and the same between... (More)

The crystalline lens of the vertebrate eye grows throughout life. This growth may be enormous in fish, while the lens must be functional from larva to adult. During growth, the fiber cells of the lens must increase the concentration of specific proteins (crystallins) in the cytoplasm to increase refractive index. However, the bulk of the fiber cells in a vertebrate lens are denucleated and have no organelles to synthesize proteins. To study how this problem is solved, we first measured lens fiber cell thickness in the Nile tilapia, a teleost fish. In the lenses from 25 fish, in two size groups, fibers were considerably thinner than in other vertebrates. Fiber thickness was about constant along the radius of the lens and the same between the size groups. Since our results provided no evidence for shrinkage of lens fiber cells with growth (expected if protein concentration is increased by expelling water) we included eight additional teleost species to elucidate the mechanism by which the cells increase crystallin concentration. In all species, fiber cell thickness was about constant throughout the lens, with species-specific values. The changes in fiber cell thickness expected from an increase in crystallin concentration by removal of water were modeled. Shrinkage in cell thickness by up to 66% would have been necessary to reach the required crystallin concentration. We conclude that crystallin concentration in denucleated lens fiber cells is increased by transport of proteins from synthetically competent cells in the periphery of the lens.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Crystalline lens, Development, Fiber cells, Lens anatomy, Modeling, Refractive index
in
Vision Research
volume
162
pages
6 pages
publisher
Elsevier
external identifiers
  • scopus:85069607782
  • pmid:31278970
ISSN
0042-6989
DOI
10.1016/j.visres.2019.06.008
language
English
LU publication?
yes
id
e8fbe31a-69b5-499c-b0ea-12813434c57c
date added to LUP
2019-08-02 15:19:29
date last changed
2020-02-19 05:37:28
@article{e8fbe31a-69b5-499c-b0ea-12813434c57c,
  abstract     = {<p>The crystalline lens of the vertebrate eye grows throughout life. This growth may be enormous in fish, while the lens must be functional from larva to adult. During growth, the fiber cells of the lens must increase the concentration of specific proteins (crystallins) in the cytoplasm to increase refractive index. However, the bulk of the fiber cells in a vertebrate lens are denucleated and have no organelles to synthesize proteins. To study how this problem is solved, we first measured lens fiber cell thickness in the Nile tilapia, a teleost fish. In the lenses from 25 fish, in two size groups, fibers were considerably thinner than in other vertebrates. Fiber thickness was about constant along the radius of the lens and the same between the size groups. Since our results provided no evidence for shrinkage of lens fiber cells with growth (expected if protein concentration is increased by expelling water) we included eight additional teleost species to elucidate the mechanism by which the cells increase crystallin concentration. In all species, fiber cell thickness was about constant throughout the lens, with species-specific values. The changes in fiber cell thickness expected from an increase in crystallin concentration by removal of water were modeled. Shrinkage in cell thickness by up to 66% would have been necessary to reach the required crystallin concentration. We conclude that crystallin concentration in denucleated lens fiber cells is increased by transport of proteins from synthetically competent cells in the periphery of the lens.</p>},
  author       = {Kozłowski, Tomasz M. and Kröger, Ronald H.H.},
  issn         = {0042-6989},
  language     = {eng},
  pages        = {29--34},
  publisher    = {Elsevier},
  series       = {Vision Research},
  title        = {Constant lens fiber cell thickness in fish suggests crystallin transport to denucleated cells},
  url          = {http://dx.doi.org/10.1016/j.visres.2019.06.008},
  doi          = {10.1016/j.visres.2019.06.008},
  volume       = {162},
  year         = {2019},
}