Setting The Record Straight On Squid Antioxidants
    By Danna Staaf | March 15th 2012 12:07 PM | 8 comments | Print | E-mail | Track Comments
    About Danna

    Cephalopods have been rocking my world since I was in grade school. I pursued them through a BA in marine biology at the University of California...

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    Thanks to my awesome brother, I have now acquired and read the full text of the paper I blogged about yesterday: "Purification and in vitro antioxidative effects of giant squid muscle peptides on free radical-mediated oxidative systems."

    I was promptly horrified by the authors' two-sentence background about the animals whose skin they were studying:
    Giant squid (Dosidicus gigas) is a cephalopod of the Ommastrephes genus and found in abundance in some parts of the world. This species is not much studied in depth due to its large soft mantel and low economic value.
    WHERE TO START. First, Dosidicus gigas is not a giant squid, but that almost goes without saying on this blog. Second, Dosidicus is the animals' genus and gigas is its species; it cannot belong to the genus Ommastrephes, because it already has its own genus, thank you very much.

    Third, the species is "not much studied in depth"? I did a Google Scholar search for Dosdicus gigas and got 2,180 results. Ommastrephes bartramii, a fellow member of the family Ommastrephidae, yields only 609 results. 

    Fourth, "mantel" is the shelf above your fireplace for family pictures; "mantle" is the body of a squid (and every other mollusc--the snails in your garden have mantles, too). 

    And fifth--"low economic value"?! The fishery for Dosidicus is the biggest squid fishery in the world (and bigger than a lot of fish fisheries).

    BUT BUT BUT. Let us put my horrification* in perspective. I am a cephalopodiatrist, so of course I know these things. I am not a biochemist. When I used hydrophobia instead of hydrophobicity, biochemists everywhere probably winced in pain.

    Scientists can be just as ignorant as non-scientists of science that occurs outside their primary field of research. Witness my hopeless confusion yesterday over how hydrophobic amino acids could be better than other amino acids at scavenging free radicals. I assumed that the authors didn't know either, when actually they did know a lot more than I understood--just not everything.

    As I have learned (largely thanks to the Linus Pauling Institute, though I poked through other sources as well), free radicals can cause oxidative damage in two situations: among things that are soluble in water (hydrophilic), and among lipids and things that are soluble in lipids (hydrophobic).

    So antioxidants come in two useful flavors: hydrophilic and hydrophobic. Vitamin C is an example of a hydrophilic antioxidant, as you know if you've ever dissolved Emergen-C in a glass of water. Vitamin E, by contrast, is an oily, lipid-friendly, hydrophobic antioxidant. Oxidative damage to lipids is especially problematic because every cell in your body has a membrane, and every membrane is made of lipids. Damage to the lipids can break open the membrane and kill the cell. Ouch!

    For this and other reasons, lipid oxidation was the whole focus of Rajapakse and colleagues' research into squid skin peptides. These scientists were explicitly testing the ability of these peptides to ameliorate lipid damage, so it's quite sensible that a greater abundance of hydrophobic amino acids would make the peptides more lipid-friendly and able to help. It's just the exact details of the chemical reactions that are still a little blurry.

    Hurrah, I'm slightly less ignorant than I was yesterday!

    Science: fighting ignorance, one scientist at a time.

    * It seems I am all about the inappropriate noun forms this week.


    I am amused by the phrase "fish fisheries". Seems that catching squid should really be called a squidery, or maybe a molluscery.

    Danna Staaf
    I'm going to be a Lorite and point out that this was mentioned a little over a year ago here, several paragraphs down. ;)
    I thought it sounded familiar. But apparently you haven't started doing it. (-:

    Scientists can be just as ignorant as non-scientists of science that occurs outside their primary field of research.

    And for those who did not wince in pain when a professional scientist displayed ignorance of basic classification:

    Kings Play Chess Only for Goodness' Sake

    King = Kingdom = group of similar phyla
    Play = Phylum = group of similar classes etc
    Chess = Class
    Only = Order
    For = Family
    Goodness = Genus
    Sake = species

    And if that mnemonic made you wince in pain, well, it is from the mind of a chemist!

    Danna Staaf
    And "for" is for Family, of course! I learned "Kings Play Chess On Funky Green Squares" but it's the same idea. =)
    Thx. I type too fast ! Correction made.

    I see no fault in that.  But it reminds me of what our Latin teacher told us, many years ago:

    One is well aware that in botanical nomenclature, the specific name horridus  indicates that the plant is covered in bristles or spikes.  This is the original Latin meaning of the word.  So something horrendum would cause one’s hair to stand on end, hence the derived meaning referring to the emotional effect.

    We were doing the story of Camilla, a fearsome maiden warrior from book XI of Virgil’s Aeneid.  It contains the line

    Turnus ad haec, oculos horrenda in virgine fixus

    which explained means “Turnus (the hero on the losing side) [said] to this one (Camilla), his eyes fixed on the horrendous virgin ...”

    though our teacher suggested that, rather than saying that Camilla was in any way horrid, it would better be translated as “the bristling virgin” (maybe she was bristling with martial fury against the invading Trojans).

    Or (I wonder) could it mean that she was so scary, she made his hair stand on end?

    Robert H. Olley / Quondam Physics Department / University of Reading / England
    Danna Staaf
    I think your interpretation (of how scary Camilla is) is the better one!