Unsolved Problems in Reef Chemistry #1 Snail Shell Coiling

Scott Weinrich · May 11, 2018

Randy Holmes-Farley said:
How could the location of the mirror impact whether something is chiral?

In flatland, chirality would be defined in only 2 dimensions. There is no third axis about which a reflection could occur.

cracker · May 11, 2018

interesting subject. Perhaps it's the orientation of the eggs when laid? one or two are set opposite of the others ?

Randy Holmes-Farley · May 11, 2018

Scott Weinrich said:
In flatland, chirality would be defined in only 2 dimensions. There is no third axis about which a reflection could occur.

lol OK, I live and think in 3 dimensions

cmcoker · May 11, 2018

Seems like I read somewhere the odd shell orientation had difficulty breeding with the normal shell orientation snails.

Found that article https://www.npr.org/sections/thetw...rare-snail-finds-romance-after-global-search

Mark Gray · May 11, 2018

Very Interesting I never thought about it, maybe if you dosed vodka on the night the snails breed just a thought

Scott Weinrich · May 11, 2018

Randy Holmes-Farley said:
lol OK, I live and think in 3 dimensions

Haha! Fair enough. It's just difficult to depict the 3d equivalent.

swebb · May 11, 2018

https://phys.org/news/2010-12-snails-shells-left-survive-snake.html
Here is an interesting article that I came across a couple of weeks ago describing a snail species in Japan that are put under pressure by snakes that are much better at catching the snails that curl to the right, dextral snails. This has led to a much larger amount of snails ending up in the opposite position, sinistral snails, surviving which has led to a much larger position of this orientation than other places. The article also states that a single gene is responsible for the snail in the orientation of the shell. It still does not answer the original question of how the snail shell originally curled in only one way, but it is interesting how snails can change the direction of their spirals in a relatively short amount of time.

Dawgvet · May 11, 2018

I found this article:

Snail shell coiling programmed by protein patterning

https://www.eurekalert.org/pub_releases/2013-05/bc-ssc052413.php

"In order to find out why some gastropods have straight and some have coiled shells researchers from the University of Tokyo looked at the pattern of Dpp during shell growth. Dpp was first identified in fruit flies where it is necessary for the correct development of limbs, wings and other organs - decapentaplegic describes the 15 things missing in the absence of the gene dpp. Dpp is also found in the shell gland of gastropods, an early structure which begins to form a developing shell. However its presence in the mantle, which takes over shell production as the animal develops, was unknown.

In all four animals tested, limpets Patella vulgata and Nipponacmea fuscoviridis, and the right-hand coiled pond snail Lymnaea stagnalis along with a sinistral coiled lab-developed snail, dpp expression matched shell shape. There was also a Dpp protein gradient spreading away from this which was also symmetrical in limpets but had left/right asymmetry for the pond snails, matching the handedness of shell coiling."

Also, isn't an "opposite" chirality within a species a recessive gene?

Dawgvet · May 11, 2018

And here is the full journal article that I mentioned above:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3680195/

Chuk · May 12, 2018

I always thought it was followings one of the logarithmic ratios (golden ratio, silver ratio, etc) because by definition they are self scaling and therefore most efficient use of material because the animal never had to change growth patterns. I heard that in a bio class sometime way back when. I didnt even know this was disputed, neat write-up.

Randy Holmes-Farley · May 13, 2018

Thanks so much for all the great discussions and links folks!

It's a nice break from alkalinity problems.

Randy Holmes-Farley · May 13, 2018

I was out for a Mother's Day walk through the Boston Public Garden today, and came across this guy. I wonder what determined it's orientation? lol

Dawgvet · May 13, 2018

I think there might have been some electrical forces causing a shearing effect.

Randy Holmes-Farley · May 13, 2018

Dawgvet said:
I think there might have been some electrical forces causing a shearing effect.

lol, probably.

klp · May 14, 2018

JoshuaRock said:
I loved this post. I was only able to read every 4th word or so but I couldn’t stop reading the whole thing. Things like this are interesting. Like did Adam and Eve have belly buttons.

No belly buttons. Made not born. I find it interesting also.

Randy Holmes-Farley · May 16, 2018

Scott Weinrich said:
I am not making that assumption. If we are talking about proteins, then basically all amino acids have the same orientation. How is an opposite chirality protein going to be consistently produced when it relies on a point mutation of an opposite chirality amino acid? There would need to be a unique codon for the opposite enantiomer. I am not aware of unique codon for specific enantiomers of amino acids.

Just a follow up, I came across this paper while looking for something else for work, where a single point mutation changes the chirality of bacterial flagella rotation. So it does happen...

A Little Switch: Alternative Domain Conformations Control Bacterial Flagella Rotation Direction
http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001480

"The flagella of E. coli move the bacterium in one of two ways. When they spin counterclockwise, the cell is propelled forward in a straight line. When they spin clockwise, the bacterium tumbles in place, ultimately pointing in some new, random direction, ready for another straight-line run."

"They identified a key residue in the HAMP structure that stabilized the inhibitory state, and showed that mutation of this residue could flip the HAMP into the alternative conformation and ‘‘turn on’’ the activity of the protein."

taricha · May 16, 2018

I love that the discussion in the article about the search for the origin of preferred chirality sounds in almost every way like the physics discussions around how symmetries broke the way they did. (Matter vs antimatter didn't quite split even etc)

Scott Weinrich · May 16, 2018

Randy Holmes-Farley said:
Just a follow up, I came across this paper while looking for something else for work, where a single point mutation changes the chirality of bacterial flagella rotation. So it does happen...

A Little Switch: Alternative Domain Conformations Control Bacterial Flagella Rotation Direction
http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001480

"The flagella of E. coli move the bacterium in one of two ways. When they spin counterclockwise, the cell is propelled forward in a straight line. When they spin clockwise, the bacterium tumbles in place, ultimately pointing in some new, random direction, ready for another straight-line run."

"They identified a key residue in the HAMP structure that stabilized the inhibitory state, and showed that mutation of this residue could flip the HAMP into the alternative conformation and ‘‘turn on’’ the activity of the protein."

Oh yeah, I know that chirality at the molecular definitely can result in chirality in higher level structures (particularly for things like the molecular motors that drive flagella). I just don't think chirality on a molecular level is the source of ALL chirality in higher level structures.

Randy Holmes-Farley · May 17, 2018

Scott Weinrich said:
Oh yeah, I know that chirality at the molecular definitely can result in chirality in higher level structures (particularly for things like the molecular motors that drive flagella). I just don't think chirality on a molecular level is the source of ALL chirality in higher level structures.

OK.