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Ultrastructure Features and Three-Dimensional Transmission Electron Tomography of Dhub Lizard (Uromastyx Aegyptia) Cornea and Its Adaptation to a Desert Environment

Published online by Cambridge University Press:  13 September 2016

Saeed Akhtar ,
Mousa Alkhalaf ,
Adnan A. Khan  and
Turki M. Almubrad
Saeed Akhtar*
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Mousa Alkhalaf
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Adnan A. Khan
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Turki M. Almubrad
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
*
*Corresponding author. [email protected]
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Abstract

We report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sections were observed with a JEOL 1400 transmission electron microscope. The cornea of the dhub lizard is very thin (~28–30 µm). The epithelium constitutes ~14% of the cornea, whereas the stroma constitutes 80% of the cornea. The middle stromal lamellae are significantly thicker than anterior and posterior stromal lamellae. Collagen fibril (CF) diameters in the anterior stroma are variable in size (25–75 nm). Proteoglycans (PGs) are very large in the middle and posterior stroma, whereas they are small in the anterior stroma. Three-dimensional electron tomography was carried out to understand the structure and arrangement of the PG and CFs. The presence of large PGs in the posterior and middle stroma might help the animal retain a large amount of water to protect it from dryness. The dhub corneal structure is equipped to adapt to the dry and hot desert environment.

Keywords

dhub lizardUromastyx aegyptialamellaeproteoglycanscollagen fibriltomography
Type
Biological Applications
Information
Microscopy and Microanalysis , Volume 22 , Issue 4 , August 2016 , pp. 922 - 932
Copyright
© Microscopy Society of America 2016 

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References

Akhtar, S., Alkatan, H., Kirat, O. & Almubrad, T. (2014). Ultrastructural and three-dimensional study of post-LASIK ectasia cornea. Microsc Res Tech 77(1), 91–98.Google Scholar
Akhtar, S., Alkatan, H.M., Kirat, O., Khan, A.A. & Almubrad, T. (2015). Collagen fibrils and proteoglycans of macular dystrophy cornea: Ultrastructure and 3D transmission electron tomography. Microsc Microanal 21, 666–679.Google Scholar
Atta, A., Ahmed, A., Ilyas, A. & Hashim, S.Z.Z. (2014). Lactate dehydrogenase like crystallin: A potentially protective shield for Indian spiny-tailed lizard (Uromastyx hardwickii) lens against environmental Stress? Protein J 33, 128–134.Google Scholar
Collin, S.P. & Collin, H.B. (2000). A comparative SEM study of the vertebrate corneal epithelium. Cornea 19, 218–230.Google Scholar
Da Silva, M.A.O., Bertelsen, M.F., Heegaard, S., Wang, T. & Nyengaard, J.R. (2014). The spectacle of the ball python (python regius): A morphological description. J Morphol 275, 489–496.CrossRefGoogle Scholar
El-Bakry, A.M. (2011). Comparative study of the corneal epithelium in some reptiles inhabiting different environments. Acta Zool (Stockholm) 92, 54–61.CrossRefGoogle Scholar
El-Sayyad, H.I.H., Khalifa, S.A., AL-Gebaly, A.S. & El-Mansy, A.A. (2014). Aging related changes of retina and optic nerve of Uromastyx aegyptia and Falco tinnunculus . ACS Chem Neurosci 5, 39–50.Google Scholar
Foureaux, G., Egami, M.I., Antoniazzi, M.M., Jared, C., Gutierre, R.C. & Smith, R.L. (2010). Rudimentary eyes of squamate fossorial reptiles (Amphisbaenia and Serpentes). Anat Rec 293, 351–357.Google Scholar
Funderburgh, J.L. (2000). Keratan sulfate: Structure, biosynthesis, and function. Glycobiology 10, 951–958.Google Scholar
Gendron, S.P. & Rochette, P.J. (2015). Modifications in stromal extracellular matrix of aged corneas can be induced by ultraviolet A irradiation. Aging Cell 14, 433–442.Google Scholar
Goldman, J.N. & Benedek, G.B. (1967). The relationship between morphology and transparency in the non-swelling corneal stroma of the shark. Invest Ophthalmol Vis Sci 6, 574–600.Google Scholar
Kolozsva´ri, L., Nógrádi, A., Hopp, B & Bor, Z. (2002). UV absorbance of the human cornea in the 240- to 400-nm range. Invest Ophthalmol Vis Sci 43, 2165–2168.Google Scholar
Komai, Y. & Ushiki, T. (1991). The three-dimensional organization of collagen fibrils in the human cornea and sclera. Invest Ophthalmol Vis Sci 32, 2244–2258.Google Scholar
Lewis, P.N., Pinali, C., Young, R.D., Meek, K.M., Quantock, A.J. & Knupp, C. (2010). Structural interactions between collagen and proteoglycans are elucidated by three-dimensional electron tomography of bovine cornea. Structure 18, 1–7.Google Scholar
Maurice, DM (1957). The structure and transparency of the cornea. J Physiol 136, 263–286.Google Scholar
McCall, A.S., Kraft, S., Edelhauser, H.F., Kidder, G.W., Lundquist, R.R., Bradshaw, H.E., Dedei, C.Z., Dionne, M.J., Clement, E.M. & Conrad, G.W. (2010). Mechanisms of corneal tissue cross-linking in response to treatment with topical riboflavin and long-wavelength ultraviolet radiation (UVA). Invest Ophthalmol Vis Sci 5, 129–138.Google Scholar
Parfitt, G.J., Pinali, C., Akama, T.O., Young, R.D., Nishida, K., Quantock, A.J. & Knupp, C. (2011). Electron tomography reveals multiple self-association of chondroitin sulphate/dermatan sulphate proteoglycans in Chst5-null mouse corneas. J Struct Biol 174, 536–541.Google Scholar
Parfitt, G.J., Pinali, C., Young, R.D., Quantock, A.J. & Knupp, C. (2010). Three-dimensional reconstruction of collagen–proteoglycan interactions in the mouse corneal stroma by electron tomography. J Struct Biol 170, 392–397.Google Scholar
Pcheliakov, V.F. (1979). Characteristics of the structure of the cornea of the reptilian eye. Arkh Anat Gistol Embriol 76(5), 86–91.Google Scholar
Scott, E., Oxford, C.R. & Hughes, E.W. (1981). Proteoglycan-collagen arrangements in developing rat tail tendon. An electron microscopical and biochemical investigation. Biochem J 195, 573–581.Google Scholar