Wise Young
11-19-2006, 06:47 PM
Nobody I know has ever seen a nudibranch without a sudden intake of breath...
http://www.divegallery.com/blue_dorid3.jpg
http://www.divegallery.com/chromodo.htm
They are the most breathtaking animals in the world. Nudibranchs are "sea slugs" and there are over 3000 described species. They belong to a larger family of creatures called opisthobranchs that are sort of like big snails without shells, with sizes that range from 6-600 mm. Yes, you read right. 600 mm is 2 feet long! Nudibranchs are the most colorful creatures on earth (Source (http://en.wikipedia.org/wiki/Nudibranch)). Inhabitants of coral reefs, nudibranchs live from the greatest depths penetrated by SCUBA divers to shallow waters by the seashore. They feed on algae, sponges, and other food of the sea.
http://www.nudibranch.com.au/images/4441.jpg
http://www.nudibranch.com.au/madangensis.jpg
http://www.cybereef.com/seaslugs/JPEGs/greenspot_spongenudie_lg.jpg
http://www.ianskipworth.com/photo/pcd2075/tambja_verconis_17_4.jpg
Although not quite as pretty as the nudibranchs, one family of opisthobranchs is called Aplysiidae and these are among the most studied of all sea creatures, because of Eric Kandel's work on their nervous system showing the mechanisms of memory and behavior. Aplysia are called "sea hares", perhaps because of two protruberances that look like rabbit ears. Aplysia can grow to become veritable giants, reaching sizes of 300 mm. A good friend of mine Arnold Kriegstein was a student of Eric Kandel and he studied the Aplysia california. we did our PhD theses together at the Marine Biological Laboratory where he successfully hatched and grew Aplysia for the first time in captivity, enabling the subsequent successful large-scale cultivation of these creatures for science.
http://www.brembs.net/learning/aplysia/aplysia.jpg
http://www.brembs.net/learning/aplysia/aplysia.html
Like other opisthobranchs, aplysia are hermaphrodites and can fertilized each other. It is sort of a dirty mottled brown color and has HUGE neurons that neuroscientists love to study. When disturbed, they injet a cloud of reddish-purple ink (Source (http://www.sahs.uth.tmc.edu/brainsurf/aplysia1.html)). What Eric Kandel showed was that these animals not only have complex behavior but can remember what had happened to them. So, if you touch an aplysia lightly on the tail, it will contract its tail. However, if you touch it again, it will contract its tail faster and more strongly. It is capable of associating different stimuli with memories. The best thing about the Aplysia is that all its giant neurons have been individually identified and named.
The National Institutes of Health (NIH) and the University of Miami has an Aplysia facility that was originally located at the Marine Biological Laboratory in Woods Hole and is operated under a contract from the Hughes Foundation (Source (http://www.rsmas.miami.edu/groups/sea-hares/)). In Florida, they are able to grow red algae, the main food of Aplysia, year around for the sea hares. I still remember Arnold Kriegstein feeding the aplysia day after day in Woods Hole and am proud that the work led to this successful use of Aplysia to detail the mechanisms of memory and behavior that eventually led to Eric Kandel's Nobel Prize. Eric Kandel and his students are still studying the Aplysia (Source (http://www.learnmem.org/cgi/content/abstract/13/3/397)). Arnold Kriegstein is now the head of the stem cell institute at UCSF and one of the world's experts on neural stem cells.
The giant neurons of the Aplysia are amazing. They are so big, you can see them with your bare eyes. They are big enough to stick electrodes into and study individually (Source (http://www.jgp.org/cgi/reprint/60/5/519.pdf)). They are big enough so that one can study the genetic regulation of individual cells. It is possible to inject genes into the neurons individually and observe their responses (Source (http://www3.interscience.wiley.com/cgi-bin/abstract/109698529/ABSTRACT?CRETRY=1&SRETRY=0)). Each of the giant neurons contain as much as 0.2 microgram of DNA each, about 200,000 more DNA that other cells. In other words, the DNA must have replicated up to 16 times (Source (http://www.sciencemag.org/cgi/content/abstract/172/3980/278)). The neurons are light sensitive (Source (http://www3.interscience.wiley.com/cgi-bin/abstract/109698529/ABSTRACT?CRETRY=1&SRETRY=0)).
Neurons of the Aplysia also regenerate (Source (http://icb.oxfordjournals.org/cgi/content/abstract/28/4/1099)) and many scientists have been studying how they do so and the genes that regulate regeneration of neurons. Incidentally, the regenerated systems are functional. For example, the regeneration of the part of the nervous system that is responsible for buccal (mouth) motor system has been studied extensively (Source (http://jn.physiology.org/cgi/content/abstract/73/1/39)). Their peripheral nerves regenerate. For example, if their pedal (foot) nerves are cut, the nerves will regenerate (Source (http://jeb.biologists.org/cgi/content/abstract/198/10/2067)). One interesting finding from Aplysia is that an enzymed called cholinesterase (which breaks down acetyl choline) plays an important role in regeneration (Source (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0F-3S138V4-2W&_coverDate=02%2F03%2F1997&_alid=491323451&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=4861&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0d2e35bb67447bb115fe10002435b563)). Conditioning lesions also enhance regeneration. Studies now are beginning to suggest that acetylcholinesterase plays an important role in mammalian regeneration and development (Source (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1566359)).
The role of serotonin in both long-term and short-term memory was first discovered in the Aplysia (Source (http://home.comcast.net/~john.kimball1/BiologyPages/M/Memory.html)). Likewise, serotonin plays an important role in learning (Source (http://home.comcast.net/~john.kimball1/BiologyPages/M/Memory.html)). This work by Eric Kandel led not only to a Nobel Prize in 2000 (Kandel's Nobel Lecture (http://nobelprize.org/nobel_prizes/medicine/laureates/2000/kandel-lecture.html)) but the identification of new drugs and therapeutic targets for memory.
So, this lowly sea slug is a big player in neuroscience.
Wise.
http://www.divegallery.com/blue_dorid3.jpg
http://www.divegallery.com/chromodo.htm
They are the most breathtaking animals in the world. Nudibranchs are "sea slugs" and there are over 3000 described species. They belong to a larger family of creatures called opisthobranchs that are sort of like big snails without shells, with sizes that range from 6-600 mm. Yes, you read right. 600 mm is 2 feet long! Nudibranchs are the most colorful creatures on earth (Source (http://en.wikipedia.org/wiki/Nudibranch)). Inhabitants of coral reefs, nudibranchs live from the greatest depths penetrated by SCUBA divers to shallow waters by the seashore. They feed on algae, sponges, and other food of the sea.
http://www.nudibranch.com.au/images/4441.jpg
http://www.nudibranch.com.au/madangensis.jpg
http://www.cybereef.com/seaslugs/JPEGs/greenspot_spongenudie_lg.jpg
http://www.ianskipworth.com/photo/pcd2075/tambja_verconis_17_4.jpg
Although not quite as pretty as the nudibranchs, one family of opisthobranchs is called Aplysiidae and these are among the most studied of all sea creatures, because of Eric Kandel's work on their nervous system showing the mechanisms of memory and behavior. Aplysia are called "sea hares", perhaps because of two protruberances that look like rabbit ears. Aplysia can grow to become veritable giants, reaching sizes of 300 mm. A good friend of mine Arnold Kriegstein was a student of Eric Kandel and he studied the Aplysia california. we did our PhD theses together at the Marine Biological Laboratory where he successfully hatched and grew Aplysia for the first time in captivity, enabling the subsequent successful large-scale cultivation of these creatures for science.
http://www.brembs.net/learning/aplysia/aplysia.jpg
http://www.brembs.net/learning/aplysia/aplysia.html
Like other opisthobranchs, aplysia are hermaphrodites and can fertilized each other. It is sort of a dirty mottled brown color and has HUGE neurons that neuroscientists love to study. When disturbed, they injet a cloud of reddish-purple ink (Source (http://www.sahs.uth.tmc.edu/brainsurf/aplysia1.html)). What Eric Kandel showed was that these animals not only have complex behavior but can remember what had happened to them. So, if you touch an aplysia lightly on the tail, it will contract its tail. However, if you touch it again, it will contract its tail faster and more strongly. It is capable of associating different stimuli with memories. The best thing about the Aplysia is that all its giant neurons have been individually identified and named.
The National Institutes of Health (NIH) and the University of Miami has an Aplysia facility that was originally located at the Marine Biological Laboratory in Woods Hole and is operated under a contract from the Hughes Foundation (Source (http://www.rsmas.miami.edu/groups/sea-hares/)). In Florida, they are able to grow red algae, the main food of Aplysia, year around for the sea hares. I still remember Arnold Kriegstein feeding the aplysia day after day in Woods Hole and am proud that the work led to this successful use of Aplysia to detail the mechanisms of memory and behavior that eventually led to Eric Kandel's Nobel Prize. Eric Kandel and his students are still studying the Aplysia (Source (http://www.learnmem.org/cgi/content/abstract/13/3/397)). Arnold Kriegstein is now the head of the stem cell institute at UCSF and one of the world's experts on neural stem cells.
The giant neurons of the Aplysia are amazing. They are so big, you can see them with your bare eyes. They are big enough to stick electrodes into and study individually (Source (http://www.jgp.org/cgi/reprint/60/5/519.pdf)). They are big enough so that one can study the genetic regulation of individual cells. It is possible to inject genes into the neurons individually and observe their responses (Source (http://www3.interscience.wiley.com/cgi-bin/abstract/109698529/ABSTRACT?CRETRY=1&SRETRY=0)). Each of the giant neurons contain as much as 0.2 microgram of DNA each, about 200,000 more DNA that other cells. In other words, the DNA must have replicated up to 16 times (Source (http://www.sciencemag.org/cgi/content/abstract/172/3980/278)). The neurons are light sensitive (Source (http://www3.interscience.wiley.com/cgi-bin/abstract/109698529/ABSTRACT?CRETRY=1&SRETRY=0)).
Neurons of the Aplysia also regenerate (Source (http://icb.oxfordjournals.org/cgi/content/abstract/28/4/1099)) and many scientists have been studying how they do so and the genes that regulate regeneration of neurons. Incidentally, the regenerated systems are functional. For example, the regeneration of the part of the nervous system that is responsible for buccal (mouth) motor system has been studied extensively (Source (http://jn.physiology.org/cgi/content/abstract/73/1/39)). Their peripheral nerves regenerate. For example, if their pedal (foot) nerves are cut, the nerves will regenerate (Source (http://jeb.biologists.org/cgi/content/abstract/198/10/2067)). One interesting finding from Aplysia is that an enzymed called cholinesterase (which breaks down acetyl choline) plays an important role in regeneration (Source (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0F-3S138V4-2W&_coverDate=02%2F03%2F1997&_alid=491323451&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=4861&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0d2e35bb67447bb115fe10002435b563)). Conditioning lesions also enhance regeneration. Studies now are beginning to suggest that acetylcholinesterase plays an important role in mammalian regeneration and development (Source (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1566359)).
The role of serotonin in both long-term and short-term memory was first discovered in the Aplysia (Source (http://home.comcast.net/~john.kimball1/BiologyPages/M/Memory.html)). Likewise, serotonin plays an important role in learning (Source (http://home.comcast.net/~john.kimball1/BiologyPages/M/Memory.html)). This work by Eric Kandel led not only to a Nobel Prize in 2000 (Kandel's Nobel Lecture (http://nobelprize.org/nobel_prizes/medicine/laureates/2000/kandel-lecture.html)) but the identification of new drugs and therapeutic targets for memory.
So, this lowly sea slug is a big player in neuroscience.
Wise.