Re: LD50 FOR FRUIT FLIES

[FRAMEP@ORAU.GOV]

Andy 

>As I recall from my brief exposure (no pun intended) to radiation 
>biology in the late 1950s, Drosophila melanogaster were favored
>radiation research organisms because they had unusually large
>chromosomes.  If this is correct, did this make them somewhat more
>sensitive than others.  The findings of BNL's gamma  source exposed
>forest in the 1960s led to this conclusion with regard to evergreens,
>compared to other trees (as was evident downwind from Chernobyl.

This may be true. But I believe Drosophila were primarily favored
because  their mutations had been well characterized, they are easy to
obtain and grow, they have a short life cycle and they can maintain a
high population density.  Unless I am mistaken, their chromosome volume
and radiosensitivity are fairly typical for insects.  They do have one
particular type of large chromosome however: the polytene
chromosomes of the salivary glands.  Because of their beautiful banded
structure, pictures of these chromosomes are always showing up in
texts. Perhaps this is what you are thinking of.

Forgive me for ranting on, but I did a little reading about this last night and
the stuff is fascinating: I think it was Arnold Sparrow at Brookhaven who
was primarily responsible for demonstrating that in plants the  larger the
volume of the interphase chromosomes (actually the volume of the
nucleus divided by the number of chromosomes), the more radiosensitive
the plant.  It seemed that no matter what the species, an average
absorption of 2-4 MeV per chromosome was lethal. Unfortunately, I
found nothing that related radiosensitivity in animals to chromosomal
volume. I'd be very interested in hearing from someone who can provide
some info on this.

By the way, there was an article by Daniel Lang in a March 1957 issue
of the New Yorker or Saturday Evening Post (I'm guessing) called "A
Stroll through the Garden" It was about the gamma garden (not the
gamma forest) at Brookhaven and it referred to a significant theft of
apples from irradiated trees. They brought in the police but no one was
ever caught. The Brookhaven folk speculated that someone couldn't
resist the garden's forbidden fruit. Since you are from Brookhaven and
admit a brief exposure to radiation biology in the late 50's, might you be
that thief? If so, was it that taste of the forbidden fruit that led you down
your life of sin?

Best wishes

Paul