hemocyanin/copper question

[cuttlegirl]

If the hemocyanin molecule has copper in it, do cephalopods need a source of copper to replenish their blood? I was thinking that we need iron so that we don't become anemic and iron is part of the hemoglobin molecule. Does it have something to do that we have blood cells and cephalopods don't?

Just wondering since copper is toxic to many marine inverts and crustaceans and cephs have hemocyanin...

Probably just me thinking too much again...

 

[William Tyson]

very good question, i would like to know the answer?

 

[Jean]

I would assume that what they need they can extract from the environment, but too much is bad!!! Even in humans we can get iron overload disease!

J

 

[monty]

If the hemocyanin molecule has copper in it, do cephalopods need a source of copper to replenish their blood? I was thinking that we need iron so that we don't become anemic and iron is part of the hemoglobin molecule. Does it have something to do that we have blood cells and cephalopods don't?

Just wondering since copper is toxic to many marine inverts and crustaceans and cephs have hemocyanin...

Probably just me thinking too much again...

I've been wondering about that, too. I found some references at some point I posted in another thread... I don't think I found any solid answers, but see Copper... Is it really that deadly?

 

[Nancy]

I remember looking it up once. Seawater does have a very slight amount of copper in it, much less than in our drinking water, for instance.

Nancy

 

[Fujisawas Sake]

The oceans have a good supply of heavy metal. So does my CD collection.

 

[Fujisawas Sake]

Okay okay okay... bad joke back there. I doubt that hemocyanin has a per capita huge amount of copper anyway. Ceph blood isn't as efficient an O2 carriers as hemoglobin, and this may be due to using copper as the main metal.

You know what's really interesting? Some chitons actually use hemoglobin.

 

[monty]

You know what's really interesting? Some chitons actually use hemoglobin.

sheesh! You come back in town, and within an hour you've hit me with 2 "everything you know is wrong" facts!

 

[Fujisawas Sake]

Kid you not.. Hemoglobin in their foot muscles. Wonders never cease, eh?

 

[monty]

Kid you not.. Hemoglobin in their foot muscles. Wonders never cease, eh?

The questions that came to mind (which I'm just cut-and-pasting from my livejournal blathering about it) once I had found my jaw on the floor were:

This presumably implies a lot of evolutionary weirdness: did hemoglobin arise before the mollusc/vertebrate divergence? Did the chitons somehow steal the gene for it from vertebrates? did it develop independently? Why don't other molluscs use it? It's been theorized that one reason fish outcompeted cephalopods was that they had better O2 transport via hemoglobin; if molluscs can use it, it seems like there should have been immense pressure for fast molluscs like cephs to use it, while an almost-sessile critter like a chiton seems like an unlikely candidate for needing better oxygen transport in its blood... of course, it appears that some cephs that use hemocyanin have abilities to live active lives in very low oxygen content water layers, so probably they have done some trick to improve hemocyanin or at least work around its limitations.

Apparently, hemoglobin is much more prevalent than I thought in non-insect invertebrates-- see http://jeb.biologists.org/cgi/content/abstract/201/8/1085
it's in bivalves, too, apparently.

 

[hallucigenia]

I think tubeworms have hemoglobins too, for that matter. Weird ones, in fact, 'cause they have to deal with sulfides. ::checks Wikipedia:: In fact, it seems that hemoglobins occur in all kingdoms...huh. Go figure.

 

[Fujisawas Sake]

True ... hemoglobins are found in the Animalia, Fungi, Plantae, and Protista. Though the Monerans or Archeae are not my bag yet.

I think you hit the nail right on the head though - hemoglobinS being the key word... There are multiple forms of hemoglobins, and their occurence in the animalia, let alone in the phyla of life on Earth cannot be pinned down to one specific genome. This may be the ultimate case of independent evolution; hemoglobins may have arisen multiple times across time.

Hemogoblins are much more ordered globular proteins which seem to work better in cells. Given that many molluscs, while eucoelomate, have a relatively open circulatory structure, perhaps their entire physiology has adapted to low oxygen/near hypoxic conditions and they don't yet require an evolutionary shift toward more efficient O2 conduction.

Its a thought...

 

[Fujisawas Sake]

What if the hemocyanin is the result of a sort of limit to the "Genotypic Plasticity" of the cephalopods? I mean, what if they simply don't carry the gene or expression of the gene would cause a cascade of trouble for cephs?

 

[cuttlegirl]

I found a reference that hemoglobin in mollusks is related to resistance to drying out (which would make sense for chiton exposed at low tide...). I can only access the abstract though...

http://www.springerlink.com/content/wk4584230t316247/


Also here is another article on hemoglobin in invertebrates.
http://cat.inist.fr/?aModele=afficheN&cpsidt=13868538

 

[hallucigenia]

Try this.
http://www.springerlink.com/content/wk4584230t316247/fulltext.pdf
It cites Planorbis corneus, a water snail, as a hemoglobin-containing mollusk...it seems to do a lot better in drying conditions than their example hemocyanin user, Rapana thomasiana ("top shell").
Other one in translation I've put up on my webspace here , because I think it's pretty heavily walled-off otherwise. It seems to agree with cuttlegirl even more strongly, claiming that hemoglobin's useful for tide-level mollusks because of buffering effects on blood acidity during oxygen deficiency.