Article Concepts
Which animal groups have evolved to have high-resolution eyesight?
vertebrates, arthropod, cephalopod
Did they find that apoptosis played a role in eye morphogenesis? How did they reach this conclusion?
No, TUNEL
Where did the researchers obtain the squid?
Marine Biological Laboratory,Woods Hole, MA
What is the purpose or question this paper is addressing?
The purpose of this paper is to understand the evolution of photoreceptive organs
Did their data suggest that notch signalling is required for photoreceptor cell differentiation in the squid retina? How did they reach this conclusion?
Yes, DAPT-treated embryos
How did they determine how Notch signaling impacts retina formation?
DAPT treatment
Why does this study use Doryteuthis pealeii as the model organism?
Cephalopods have the largest and most complex invertebrate nervous system and Doryteuthis pealeii has long been the subject of neurobiological and neurophysiological research.
What region (expressing Pax6, Pax2, and Six3) gives rise to the lens, cornea and iris?
The lip placode
What method was used to determine that the cells within the placode were the only ones to incorporate into the retina? How does this method work?
BrdU-- BrdU is incorporated into replicating DNA and can be detected using anti-BrdU antibodies
What are the two contradicting views/theories of the evolution of photoreceptive organs?
1. Vertebrate and cephalopod eyes have similar optical strategies, yet, evolved independently and 2. that photoreceptive organs have shared ancestry through the Notch signaling pathway (Drosophila and vertebrates)
Outline the development of the squid eye using figures 1 & 2.
Ex: stage 16: formation of bilateral placodes before epiboly is complete. stage 18: placodes internalized when lup of cells form around periphery of placode and progressively closes. Stage 21: optic vessel formed from periphery of placode closing and fusing centrally fusing.
Why did they use Rhodopsin as a photoreceptor cell marker?
Lack of Rhodopsin expression in DAPT-treated embryos suggests loss of differentiated photoreceptors which indicates that Notch signaling is required for photoreceptor cell differentiation