genetic background to certain eye mutants

[Steve Shaw]

I don't know if this is the best place to ask the primitive question below, but if not could someone please give me an opinion where to look? I've only recently started with Drosophila so am not too familiar with how to get such information, and could not find anything on the question here in FlyBase -- but maybe I missed it.

I'd like to know what is the general genetic background of some Bloomington-origin mutants, if this info is not lost in the mists of time. In this case I'm interested in three mutants in which photoreceptor output from the compound eye is blocked, though through different mechanisms in each. Specifically I'm interested in: tan (t[1], BDSC stock number 130), ebony (e[1], but it's probably really e[4] according to a post on FlyBase by Kevin Cook; BDSC #1658), and Hdc (not hdc) (actually a white-eyed version -- ours apparently is w[1118]; Mi{ET1}Hdc[MB07212], BDSC # 25260).

Is it possible to find out if each (or any) of these has an Oregon R or Canton S background, or some other background? Or are the t[1] and e[1] stocks in particular too ancient to ferret this out, or perhaps established even before the founding of the Oregon R, Canton S, etc., lines?
Steve Shaw,
Dalhousie University, Canada

[Josh Goodman]

Hi Steve,

I recommend contacting the Bloomington Stock Center via email and asking them.

http://flystocks.bio.indiana.edu/

Cheers,
Josh

[Steve Shaw]

Thanks Josh: I actually did send a request to BSC in parallel to this, and just got a reply. In essence ebony and tan are so old and have likely been crossed many times into diverse stocks, before Oregon R and similar lines were even established, that the background is not really knowable or intelligible at this point. This matched one of my guesses, but I thought also perhaps that it might have become the practice to cross such mutations into a known stock like Oregon R to maintain them -- apparently not.
A related, larger question to me as an extreme novice is why people insist on using such established stock lines in the first place. For instance, someone here is using Canton S wild type for electron microscopy, apparently because others elsewhere have done behavioral studies using the same line, and apparently wanted uniformity. But none of these lines are clones, and will not be homozygous for most genes either, so no two Canton S flies pulled out of even the same vial will be identical at most loci -- so isn't the quest for uniformity illusory? I can see that some recessive lethal mutations may have been uncovered and eliminated in a long-established line, but would that be a big problem anyway? I must be missing something by way of overall explanation of the advantage.
By contrast, long-inbred lines may accumulate errors that would be largely purged by natural selection in a large wild population: it is the practice for some insects maintained in the lab to add wild-caught stock frequently to maintain the vigor of the colony which otherwise deteriorates. This seems like the opposite of choosing to use Canton S or another long established line. So as I said, I think I'm missing something.
Regards,
Steve

Hi Steve,
I recommend contacting the Bloomington Stock Center via email and asking them.
http://flystocks.bio.indiana.edu/
Cheers,
Josh