MacKenna Roberts, Progress Educational Trust
26 August 2007
[BioNews, London]
A study has found that exposure to the 'harsh' cool-white fluorescent lighting commonly used in fertility clinics, research labs and most office environments could be particularly damaging to an embryo's healthy development. A joint team of researchers in Hawaii and Japan conducted the study on mouse embryos and found that certain types of light exposure are more damaging to embryo development than others.The study also indicates that mammalian embryos, which develop in dark wombs, lack a protective mechanism that other animals, such as amphibious frogs or fish which lay external eggs, possess in order to cope with exposure to light. These results were published last week in the Proceedings of the National Academy of Sciences of the United States of America.
Sunlight and cool-white fluorescent office light, which is blue-white in appearance, were the most detrimental to the mice embryo development while warm-white light, which is typically used to illuminate homes and residential environments and has a yellow-white colour, was significantly less damaging, according to Dr. Ryuzo Yanagimachi, a retired reproductive biology specialist involved with the University of Hawaii study in collaboration with Manami Takenaka and Toshitaka Horiuchi of the Prefectural University of Hiroshima. They found that even reducing light-exposure to ten seconds for direct sunlight and to a few minutes for blue-white light, still caused damage to the embryos in the study.
It appears that the light stimulus triggers a stress response in the embryos that hampers their healthy development. When exposed to light, the embryos produced increased levels of radical oxygen which is toxic to cellular development, explained Dr. Yanagimachi. He added that the study has lent support to his belief that light is a neglected environmental factor in embryo development.
The researchers suggest that labs which deal with human and animal embryos would improve their success in embryo development if they (1) replace 'harsh' office lighting with 'softer' warm-white light bulbs for illumination, thereby reducing damage to reproductive materials when they are unavoidably exposed to light in the lab, and (2) generally attempt to minimise light exposure as much as possible during each stage of embryo development that is manipulated outside of the uterus including during egg extraction, sperm insemination and fertilisation.
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Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.