This is important for scientists and non-scientists alike. You might be surprised at how many people do not know someone who is blind or has gone through a blinding disease. You might be further surprised at how many scientists that are engaged in vision research do not really know what its like to have gone through vision loss or have similarly interacted with someone who is going blind. As I’ve said before in The Judgment Of Solomon post, “Every scientist studying vision and diseases affecting vision should have the opportunity to spend time with those who have lost sight. It is important for people in the sciences to sit down and talk with those affected by the disease they study.”
The subject of this short, Mark has a cone/rod dystrophy due to a defect in the ABCA4 gene, which codes for an ATP-binding cassette transporter family. Kris Palczewski’s group has shown that these defects ultimately cause a buildup of all trans retinal in the outer segments of the photoreceptors and leads to likely oxidative damage, cell stress and photoreceptor toxicity. This photoreceptor toxicity then ultimately results in photoreceptor cell death and blindness.
Jun Yang‘s lab focuses on the molecular mechanisms of hereditary retinal degenerative diseases, focusing specifically on the mechanisms of a set of inherited diseases in Usher Syndrome where people go blind and deaf due to defects in the cytoskeleton of photoreceptors in the eye and hair cells in the ear. She explores the cell biology of photoreceptors with mouse models of Usher Syndrome and a combination of approaches in molecular and cellular biology, biochemistry, electrophysiology, behavior and microscopy.Continue reading “Portrait of Vision Scientist: Jun Yang”
Jiang Li will be delivering a seminar, Intraflagellar Transport (IFT) Essential For Photoreceptor Connecting Cilium/Axoneme Formation and Maintenance on Tuesday, August 19th, 2014 in the John A. Moran Eye Center auditorium.
A light-sensitive photoreceptor outer segment (OS) is a modified primary cilium and communicates with the inner segment (IS) through a “connecting cilium” (CC), a structure equivalent to the transition zone of primary cilia. Anterograde intraflagellar transport (IFT) has been implicated in protein trafficking of photoreceptor sensory cilia. IFT is a bidirectional ciliary trafficking pathway conserved between invertebrates and vertebrates with heterotrimeric (KIF3) and homodimeric (KIF17) kinesin-II as anterograde motors. To differentiate anterograde IFT func,on in photoreceptor development and survival, we generated embryonic retina-specific and postnatal tamoxifen-induced deletions of KIF3a, and germline deletions of KIF17. In embryonic retina-specific Kif3a knockout mouse, basal bodies docked to the cortex of mutant photoreceptors but failed to form CC and OS. Rhodopsin, cone pigments and other OS proteins were retained in the knockout photoreceptor IS. In contrast, tamoxifen- induced deletion of Kif3a in adult mouse led to slowly progressing photoreceptor degeneration due to the inability of photoreceptors to maintain their mature axonemes. Rhodopsin and cone pigments trafficked to OS up to 3 weeks post- induction. Once fully mature, the Kif3a knockout photoreceptor axonemes were unable to be maintained and disintegrated slowly. Germline deletion of KIF17 affected neither axoneme structure nor photoreceptor morphology/function, thereby excluding an essential role of KIF17 in photoreceptor IFT. Our results demonstrate that IFT is not required for rhodopsin transport to the OS. Rather, anterograde IFT mediated by KIF3a, but not by KIF17, participates in photoreceptor transition zone (PTZ)/axoneme formation and maintenance.
There are species of shark that are bioluminescent and have evolved ocular structures designed to detect faint light patterns in the deep ocean produced by other bioluminescent sharks that live at depths from 600 to 3,000 feet in the mesopelagic zone where very little sunlight reaches.
These eyes as expected, have visual adaptations optimized for this environment. Julien Claes, the lead authors of a new study notes that “There are about 50 different shark species that are able to produce light”. Given that there are 50 separate bioluminescent species of shark, one might expect some visual system specializations and indeed there are. Everything from higher rod densities to descriptions of bioluminescent specializations used for communication and specialized transparencies in the upper socket of the eye to help adjust illumination. Continue reading “Glowing Sharks Have Unusual Eyes”
This video by brusspup on Youtube shows a series of moving white circles that travel in straight lines… the trick is the illusion of circular motion through relative timing of the linear motion. Well done.