Academic nonsense! (scientific info on thiamine/thiaminase)

[aSnakeLovinBabe]

This is all very interesting!!! At least I can understand it but I am not sure everyone will.... I am still going to stick with the safest plan of action and avoid thiaminase altogether.

[k2l3d4]

Ok... can some one translate the first page into laymans talk..... ?

[guidofatherof5]

Ok... can some one translate the first page into laymans talk..... ?

I think I got it.

Fish are friends, not food!

[Stefan-A]

Hee hee... Well, I just happened to see this when I looked up those other studies...

A Method for Measuring Total Thiaminase Activity in Fish Tissues
Zajicek, JL, et al.
Journal of Aquatic Animal Health vol. 17, no. 1, pp. 82-94. Mar 2005.
(Paraphrasing here, of course...)
1. Pulverize the fish you want to test and make an extract in buffer solution.
2. Add a known amount of radioactive thiamine and let stand 10 min.
3. Add ethyl acetate. Thiazole, one of the breakdown products of thiamine, is soluble in the organic solvent ethyl acetate while whole thiamine is not.
4. Measure the amount of radioactivity in the ethyl acetate. This tells you how much radioactive thiazole is there, from which you can calculate how much radioactive thiamine must have been broken down in 10 minutes, from which you can calculate how much thiaminase there must have been in your fish.

It seems that older assays were variants of this same general method (find a way to measure the amount of breakdown product created in a known time period). They just made some technical improvements that should give more accurate results.

EDIT: This is why if you look at any of these studies, they all talk about "thiaminase activity" - none of them is measuring the literal number of thiaminase enzyme molecules in the fish. What matters practically speaking is how much thiamine gets broken down between the time the fish dies and the time it gets to the predator's intestine, not how many enzyme molecules it takes to do that.

Thanks. I figured it would be done that way, but I wasn't sure.

[DrKate]

Ok... can some one translate the first page into laymans talk..... ?

I know I'm the kind of person who needs to get all the details before I feel comfortable with an issue like this. If you feel the same way and really want to understand this stuff I'm happy to give a shot at explaining anything that's not clear, and I'm sure there are other folks here who could help out too, so please just ask.

But I have to say I really really don't think an intimate understanding of the way thiaminase works is truly necessary for taking good care of your snakes!! If you'd rather not know, please - don't worry about it! Just play it safe and avoid goldfish and minnows, and pay no attention to the rest of this nonsense.

[Stefan-A]

But I have to say I really really don't think an intimate understanding of the way thiaminase works is truly necessary for taking good care of your snakes!!

I don't care if I need it, I want it.

[GradStudentLeper]

Anybody know if spottails specifically are the "shiners" sold as feeders and bait?

No, they are in a different genus.

That last study I posted, on the forage species in the Great Lakes, found that thiaminase levels in some fish go UP with the amount of thiamine they contain (I didn't post that part).

You should have posted that initially.

Coincidentally... I don't think too many wild garters are consuming platies or guppies. Definitely mosquitofish, but not other species of livebearers.

No, they are not. We dont have them native here. In the wild they will basically be eating shad, sunfish, small perch, catfish etc. In some parts of their range they might eat trout fry (where those are introduced, I know T. atratus does that, and it decouples their population dynamics from their native frog prey, thus allowing their populations, while still feeding on frogs, to overshoot what the frogs can sustain. Those poor mountain yellow legged frogs... first Chitrid, then Apparant Competition/Hyperpredation by trout)

In any event, it has also been found that a bacterial infection may be (at least partially) responsible for increasing the amount of Thiaminase in alwives.

Honeyfield, DC., Hinterkopf, JP., Brown SB. 2002. Isolation of thiaminase-positive bacteria from alewife. Transactions of the American Fisheries Society, 131(1):171-175.

I think I got it.

Fish are friends, not food!

No, only certain kinds of fish are our friends...

Unfortunately, a search through Web of Science wielded no results for the dietary thiamine needs of snakes. I will broaden my search to include other reptiles later.

[DrKate]

You should have posted that initially.

I didn't find it until later. And it doesn't change the take-home message. But for completeness' sake I'll revise:

CORRECTION! Thiaminase content may or may not correlate with thiamine content. In some species, in some populations, in some years, at some times of the year, fish with more thiamine also have more thiaminase (Tillitt study on Lake Michigan forage species). In other species, in other populations, in other years, and at other times of the year, there is no relationship between the amount of thiamine and the amount of thiaminase in the fish (Tillitt again, and also Fitzsimons study on ten alewife populations).

The point remains valid: the situation is obviously hugely variable, cannot be solved 100% by changing what you feed the feeders (as Zephyr was asking), and means that feeder fish sold at different stores, even if they're the same species, might provide very different amounts of thiamine.

In any event, it has also been found that a bacterial infection may be (at least partially) responsible for increasing the amount of Thiaminase in alwives.

Do you believe it? It's an honest question - I didn't save any of the citations, but when I looked at studies of thiaminase-producing bacteria in alewives the results seemed inconsistent (didn't always find bacteria where they found thiaminase). If the studies you read had really solid results, that would be interesting.

But even if thiaminase-producing bacteria in the gut are the root cause, and not the fish themselves... Thiaminase has been documented in so many fish (including goldfish and fatheads!), some at even higher level than in alewives, that it must be a very widespread bacterium. I would think it still has to be a concern for commercially produced feeder fish.

This is digressing a bit, but incidentally, thiaminase-producing bacteria have also been found in the digestive tracts of some people with chronic thiamine deficiency!

Bacterial synthesis and destruction of thiamine
Hayashi, R
Nutrition Reviews vol 15, no 3, pp 65-67, March 1957
"K. Shibata and S. Chang (Vitamins (Japan) 1, 209 (1948)) observed the disappearance of 10 mg. of thiamine introduced by enema into the sigmoidal colon of a patient with habitual constipation and beriberi [beriberi is the name for thiamine deficiency in people]. They succeeded in recovering from the feces of the patient a potent thiaminase."

Thiamin status of a Melanesian population
Duffy, P, et al.
American Journal of Clinical Nutrition, Vol 34, 1584-1592, August 1981
"In addition, preliminary results are reported to indicate the presence of thiaminase I activity and thiaminase I producing bacteria in fecal samples from both the Torres Strait Island population and hospital patients."

[DrKate]

Coincidentally... I don't think too many wild garters are consuming platies or guppies. Definitely mosquitofish, but not other species of livebearers.

Sorry, I wasn't trying to suggest that they do - I did say "prey," but I just meant food in general, including store-bought feeder fish for captive snakes. Sorry to be confusing! (I doubt many wild garters are eating the marine species of silversides that are sold frozen, either!)

[DrKate]

Unfortunately, a search through Web of Science wielded no results for the dietary thiamine needs of snakes. I will broaden my search to include other reptiles later.

Ooh! That gave me an idea... Anyone out there inspired to take on Corporate America? Or at least, call up Rep-Cal or one of those companies and ask them how they got their reference values for the contents of their vitamin powder? If you ask nice, they may actually be willing to tell you where they got their info. We're specifically interested in the thiamine content for the purposes of this thread, but if they do have references on the complete nutritional requirements of snakes (or reptiles more generally) that would be way cool.