Sea squirts new model for Alzheimer's

Sea squirts are perhaps a seemingly unlikely model for Alzheimer’s disease, but scientists have made a breakthrough in researching the disease after sea squirt tadpoles were used to test an experimental anti-plaque forming drug.

In fact, sea squirts – Ciona intestinalis – are thought to be our closest invertebrate relatives and share all the genes needed for the development of Alzheimer’s plaques in humans. These plaques are characteristic of the disease and the best hope for curing or slowing down the disease is to target the build up.
“Because of their small genome size, simple body plan organisation and rapid development, sea squirts have long been recognised as an excellent model to study early developmental mechanisms” said Bob Zeller, San Diego State University (SDSU) biology professor.
“By adding the ability to examine simple genetically encoded behaviours, we’re hoping to establish sea squirts as a more direct model for human neurodegenerative diseases such as Alzheimer’s disease,” he continued.
Zeller and his colleague Mike Virata were able to model the disease in sea squirt tadpoles. They dosed the tadpoles with a mutant protein found in human families with hereditary Alzheimer’s and observed the aggressive development of plaques in the tadpole’s brains.  They were then able to reverse the plaque development by treating them with an experimental anti-plaque forming drug.
All other invertebrates that have been tested could not process the plaque-forming protein, and vertebrates take too long to make plaques. The researchers’ results make it a real possibility that sea squirts are an excellent model for testing drugs to fight Alzheimer’s.
Sea squirts, or tunicates, are marine organisms with a soft body inside a hard outer tunic. They attach themselves to one spot on an underwater structure and suck in water through one siphon – filtering out small plants to eat – and squirt out the water through another siphon.