Planarian flatworms have come under intense study for their renowned ability to regenerate any missing body part. Split one in two and it will regenerate as two separate individuals.
Now this species may take on a starring role as a model system for studying eye development and eye diseases in vertebrates, including humans.
Whitehead Institute researchers identified 600 active genes in the planarian eye, among them genes involved in eye development and others associated with age-related macular degeneration and Usher syndrome, a disorder that causes progressive retinal degradation.
The compound eyes of fruit flies are the most thoroughly studied invertebrate eyes, owing to the short fly life cycle and a library of well-described eye-related genes in fruit flies. However planarians present a new genetic system, with an eye based on one optic cup lined with pigment cells.
Such vision loss can have a significant impact on people’s daily lives, such as affecting their ability to read or drive a car
One of the key genes identified in planarian eye development is the transcription factor ovo, which activates the expression of many other genes as the eye forms. Until now ovo had been associated with neural tube and germ cell development in other organisms, but not with the eye. In planarians, ovo is vital for eye for regeneration and eye maintenance in the adult, and is also active in eye development in the embryo.
Researchers have found that when ovo is experimentally turned off, planarians with head amputations cannot regenerate their eyes and eyes of otherwise normal adult planarians vanish after a couple months.
Researchers said the ability to study diverse model species has distinct benefits, and this has been demonstrated by the discovery of a critical role for ovo.
