Scientists Debunk Myth that Pearls come from "Grains of Sand"

30pearls.jpg

Here's a picture supporting Doug's position on parasites.

Again, these are what I loosely refer to as "double pearls". First formed as singles, then concreted together.

Definitely a treat to find 30 pearls in one mussel.
 
Great Photo of the Mussel pearls...and it looks quite tasty!!! We've also found "rosaries" of pearls in the mantle just like Dave's, and they do fuse together and form "grape" clusters. Unfortunately, this year's natural pearl harvest was very small and not that interesting...except for the natural pearl we sent to Granada, Spain, for analysis...a unique specimen. Hope our friends in Spain will be able to find some interesting information from it.

In case you haven't seen it...Weird Natural Pearl (1) [640x480].jpg
 
In case you haven't seen it...

Beautiful pearl Doug! How many mm or carats is that?

...and it looks quite tasty!!!

Okay, you made me post food again!

These are juvenile mussels (2-3 inches) marinated in balsamic vinegar, double virgin olive oil, cilantro, onions and garlic.

Sometimes I shake mussels in ground Cheese Ritz and shallow fry them in light oil.
 

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Oh My God! Those mussels look delicious!!! I will have to try your recipe Dave!

Can't really remember the pearl's specs, but what really was amazing of the pearl is that it had 3 phases: calcitic, aragonitic and proteinic, and in the calcitic area it had aragonitic "inclusions" (looked a bit like embedded opals). It is the weirdest pearl -natural or cultured- I have ever seen. If Valeria sees this post maybe she can help us by sending the pearl's specs. It may help scientists understand some of the mysteries of biomineralization...
 
what really was amazing of the pearl is that it had 3 phases: calcitic, aragonitic and proteinic, and in the calcitic area it had aragonitic "inclusions" (looked a bit like embedded opals). It is the weirdest pearl -natural or cultured- I have ever seen.

Half nacreous, half foliated... that is wierd. It's as though the cells morphed into a different structure as the sac developed.
 
Exactly! Something really weird happened in that pearl sac.
 
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Here's a picture supporting Doug's position on parasites.

Again, these are what I loosely refer to as "double pearls". First formed as singles, then concreted together.

Definitely a treat to find 30 pearls in one mussel.

Just today I found a Pteria sterna pearl oyster with 121 small (0.9 to 3.5 mm) natural pearls...all of them embedded in the mantle. The shell of the oyster had extensive damage caused by drill-mussels. The photos...follow:

Natural Pearls 009 [640x480].jpgNatural Pearls 015 [640x480].jpgImage229 [640x480].jpg
 
3 phases: calcitic, aragonitic and proteinic, and in the calcitic area it had aragonitic "inclusions" (looked a bit like embedded opals). It is the weirdest pearl -natural or cultured- I have ever seen. If Valeria sees this post maybe she can help us by sending the pearl's specs. It may help scientists understand some of the mysteries of biomineralization...

I've observed similar structures (left side image) in Mytilus c. thanks to our friends in Granada, Spain. Over time, the inclusions overlap like shingles on a roof.
 

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Yes Caitlin, we do get many of those tiny ones. Hard to drill...but we have made some "pav?" style jewelry pieces with them. We keep storing them until we have 10 kilos or more, then we'll figure out what to do with them. Any ideas?
 
Send them to India to be drilled.

Anyone here who knows a good drilling place in India? I have some abalone seed pearls, really tiny, and that was where i was told to send them.
 
I don't consider myself to be the last word or anything close. But, being Biologists we have always wondered at Life's amazing strategies, patterns, shapes, etc. Life is simply MAGNIFICENT. But we are also Engineers and we wonder and tinker: how does the animal do that? Can we fool it? Can we make it do our will?

Along these lines, I wonder whether oysters have a way of recognizing invaders and whether their natural response is to induce nacre secretion for encapsulation of the invader. At least some reports indicate that mussels, snails and abalone can increase shell thickness in response to pathogens. This may be a response akin to nacre secretion for natural pearl production. I remember I looked it up some time ago and found that at least some mollusks can adjust shell thickness within 1-2 generations when exposed to high levels of pathogens. I don't have the original references to it anymore, but a short time of response in my opinion would rule out natural selection and suggest that some molluscs have a monitoring system, whose activation may result in upregulation of secretion of shell material. This makes sense as mussels and oysters cannot simply swim away when exposed to parasites. The obvious conclusion for me would be that there are signaling mechanisms in place that can upregulate nacre secretion when needed. Therefore, once the signal(s) are known , they could be used to artificially induce pearl production, perhaps by coating nuclei with the signaling molecule.

Some report on the presence of an immune system:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039611/

Shell thickness:
http://evolution.berkeley.edu/evolibrary/news/060901_mussels
http://www.int-res.com/abstracts/meps/v276/p115-123/

This may also sound familiar:
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=144863
 
The oyster's immune system is very simple -and this is very fortunate, else the grafting of tissue would be as complicated as with Humans- but it is indeed there. The monitoring system cannot be discarded, it is quite in place: the oysters have chemo-receptors and their primitive nervous system helps them to recognize a physical threat.

The "regulator" or system in charge of the defensive mechanism for "attackers" are HORMONAL. And there lies the problem of lab-culture (tissue culture) of pearls: to be able to identify and then synthesize these hormones. To do so...it is quite costly with present technology. So, it seems we are always worrying about others Hormones (aren't we???), be them oysters, Humans or pets. ;)
 
I agree that the signal inside the cell is hormonal. But I am having some evil thoughts about turning natural pearl production into something unnatural. Could it be that some of the parasites and pathogens that invade molluscs have a chitin outer layer? Then, just commercially available chitin coated beads may be helpful in stirring up that immune system. I am asking, because labs that study biomineralization use polysaccharides in the process. A search of Pubmed with "nacre and chitin" turned up some articles of which one is linked below:

http://www.ncbi.nlm.nih.gov/pubmed/20397648
 
Of course there is also a natural source of chitin that may also be willing to produce proteins, such as the N16, Pif80, and Pif97 proteins mentioned in the article: Budding yeast. It may be hard to form that cake into perfect beads, but since Chinese pearl farmers use muck for "nucleation".... Sorry, I have to stop the craziness and get back to work.
 
labs that study biomineralization use polysaccharides in the process.

They claim conchiolin induces aragonite. I'm not so sure, insomuch as it only has an affinity for calcium carbonate and provides a water-tight barrier so mineralization can take place. But let's say it is true, then it's probably only in the presence of mantle epithelial cells.

The conchiolin coated bead would calcify, but thats about all. There's a big difference between bodily fluid and pallial fluid. As Doug says, these cells are regulated by hormones, and not as a single function, but in very complexed combinations.

The pallial group of epithelial cells simply do not appear spontaneously where none are present.

In my studies, more than 99% of natural pearls occur in the mantle and/or extrapallial space, irrespective of the cause. Pearls from the body mass of mussels are very rare. When I do find them, they are most often proteinaceous or calcareous, rarely nacreous.
 
I should note this paper. http://www.daveleblanc.ca/pdf/Checa_2000_Periostracum_and_shell_formation.pdf

Checa alludes to the same thing. I've observed "spherules" in similar folds of the periostracum, but then again I am not convinced these give rise to pearls as a single factor in every instance. It seems more likely, perforations made in the mantle by these serve as a point of entry for parasites.
 
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