Differential gene expression of the healthy conjunctiva during the day

  • Heba Alenezi
    Corresponding author at: School of Optometry and Vision Science, The University of New South Wales, Sydney 2033, NSW, Australia.
    School of Optometry and Vision Science, The University of New South Wales, Sydney 2033, NSW, Australia

    College of Applied Medical Science, Prince Sattam Bin Abdulaziz University, Al-Kharj 16278, Saudi Arabia
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  • Jerome Ozkan
    School of Optometry and Vision Science, The University of New South Wales, Sydney 2033, NSW, Australia
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  • Mark Willcox
    School of Optometry and Vision Science, The University of New South Wales, Sydney 2033, NSW, Australia
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  • Grant Parnell
    Centre for Immunology and Allergy Research, Westmead Institute for Medical Research, The University of Sydney, Sydney 2145, NSW, Australia
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  • Nicole Carnt
    School of Optometry and Vision Science, The University of New South Wales, Sydney 2033, NSW, Australia

    Centre for Vision Research, Westmead Institute for Medical Research, The University of Sydney, Sydney 2145, NSW, Australia

    Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
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      To determine if there is diurnal variation in gene expression in normal healthy conjunctival cells.


      Bulbar conjunctival swab samples were collected from four healthy subjects in the morning and evening of the same day. The two swab samples were taken from one eye of each participant, with a minimum of five hours gap between the two samples. RNA was extracted and analysed using RNA sequencing (RNA-Seq).


      A total of 121 genes were differentially expressed between the morning and the evening conjunctival samples, of which 94 genes were upregulated in the morning, and 27 genes were upregulated in the evening. Many of the genes that were upregulated in the morning were involved in defence, cell turnover and regulation of gene expression, while the genes upregulated in the evening were involved in signalling and mucin production.


      This study has identified several genes whose expression changes over the course of the day. Knowledge of diurnal variations of conjunctival gene expression provides an insight into the regulatory status of the healthy eye and provides a baseline for examining changes during ocular surface disease.


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