Amazing stuff!
"Cephalopods are capable of some truly impressive behaviors. They can quickly process information to transform shape, color, and even texture, blending in with their surroundings. They can also communicate with one another, show signs of spatial learning, and use tools to solve problems. They are so smart they even get bored and start making mischief. ...
These marine animals, which include octopus, squid, and their cuttlefish cousins, have the most complex brains of any invertebrates on the planet. ...
These marine animals, which include octopus, squid, and their cuttlefish cousins, have the most complex brains of any invertebrates on the planet. ...
Researchers ... describe in a new study how they used a new live-imaging technique to watch neurons being created in squid embryos almost in real-time. They were then able to track those cells through the development of the nervous system in the retina.
They were surprised to discover that these neural stem cells behaved very much like those in vertebrates during nervous-system development. The results suggest that while vertebrates and cephalopods diverged from one other 500 million years ago, the process by which both developed big brains was similar. In addition the way the cells act, divide, and are shaped may essentially follow a kind of blueprint required for this kind of nervous system. ..."
From the highlights and abstract:
"Highlights
• Retinal progenitor cells in the squid undergo interkinetic nuclear migration
• Progenitor, post-mitotic, and differentiated cells are transcriptionally defined
• Notch signaling may regulate both retinal cell cycle and cell fate in the squid
Summary
Coleoid cephalopods, including squid, cuttlefish, and octopus, have large and complex nervous systems and high-acuity, camera-type eyes. These traits are comparable only to features that are independently evolved in the vertebrate lineage. The size of animal nervous systems and the diversity of their constituent cell types is a result of the tight regulation of cellular proliferation and differentiation in development. Changes in the process of development during evolution that result in a diversity of neural cell types and variable nervous system size are not well understood. Here, we have pioneered live-imaging techniques and performed functional interrogation to show that the squid Doryteuthis pealeii utilizes mechanisms during retinal neurogenesis that are hallmarks of vertebrate processes. We find that retinal progenitor cells in the squid undergo nuclear migration until they exit the cell cycle. We identify retinal organization corresponding to progenitor, post-mitotic, and differentiated cells. Finally, we find that Notch signaling may regulate both retinal cell cycle and cell fate. Given the convergent evolution of elaborate visual systems in cephalopods and vertebrates, these results reveal common mechanisms that underlie the growth of highly proliferative neurogenic primordia. This work highlights mechanisms that may alter ontogenetic allometry and contribute to the evolution of complexity and growth in animal nervous systems."
Graphical abstract
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