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Re: hormonal (or other) inhibition

Paul Kromholz writes:

> In the '60s a man named Merill s. Rose did some fascinating experiments on
>  inhibition in tadpoles.  He found that in an aquarium only one or two grew
>  well, and the rest were stunted and did not eat very much, in spite of an
>  abundance of food.  He found that the big ones produced something in the
>  water that inhibited feeding in the rest.  Water from the tank with the big
>  ones could be transferred to another tank, and it would inhibit tadpoles
>  there, too.  The water lost its inhibitory properties if it was heated to
>  over 50 degrees centigrade.  Interestingly, the inhibitory factor could be
>  filtered out of the water with ordinary filter paper, indicating it was not
>  something in solution, but particulate, possibly cells from the inhibitory
>  tadpoles.  At that point, just when it was really getting interesting, the
>  research ended.  A year went by, and then Professor Rose now working at a
>  different institution, I think,  published a paper on something else,
>  something dull and uninteresting.  Apparently the funding ran out for his
>  tadpole research.  I have never had the time to find if somebody else
>  continued that line of research.

There is a species of frog that lives in the Southwest US.  They lay their 
eggs in what amounts to not much more than rain puddles.  Because the puddles 
are relatively short-lived, the tadpoles don't have long to reach full 
development.  A few of each brood grow faster than their brethren, and become 
cannibalistic, eating their smaller siblings.  This excellent protien source 
allows them to mature within the limited time Mother Nature has allotted 
them.  In this instance, the inhibition of some to the advantage of the 
others offers an evolutionary advantage.  Although I am not familiar with 
Mr/Dr Rose, it is likely that this is the species he was studying.  In the 
long study of life in general, fish living in permanent water, like discus, 
are going to find no evolutionary advantage in this arrangement.  I still 
claim that these supposed growth-inhibition hormones are more urban legend 
than reality, unless someone can validly cite some research paper to the 
contrary.

Bob Dixon