Subject: Re: Planarians, RNA, memory, cannibalism & knowlege

From: [email-masked] (Rosemary Hoffman)
Date: Wed, 20 Oct 1993 22:57:12 GMT

In article <[email-masked]> [email-masked]
(Michael Levin) writes:
>    I recently ran across some papers (maybe 10 years old or so)
>talking about the following experiments: in an attempt to prove that
>memory was "encoded" by RNA, some people took planarians, taught them
>various things, ground them up, and fed them to other planarians which
>were able to learn those things much faster. RNAse inhibited this
>process. It looked like several crucial experiments were not done, but
>still - it looked interesting. Does anyone know what happenned to this
>field of research? Is it dead? If so, why? If not, any recent
>references? They even had their own quasi-journal called "The Worm
>Runner's Digest". Please reply to [email-masked].
>

This may be a scientific urban legend.  I remember hearing about this back
in the dark ages (ca. 1960-70) when I was in college and grad school.

Rosemary Hoffman

The opinions expressed are all mine and not those of my employer - thank
goodness!

---

From: [email-masked] (Stephen Matheson)
Date: 21 Oct 1993 01:16:49 GMT

>From article <[email-masked]>,

> This may be a scientific urban legend.

Hardly.  Indeed, it is one of the most delightful sagas in scientific
history (IMNSHO).  The following is quoted from "Biochemical Aspects
of Memory Mechanisms" by Steven P.R. Rose, in _Applied Neurochemistry_,
A.N. Davison & J. Dobbing, eds., F.A. Davis Co., Philadelphia, 1968.

  Historically, the earliest of these studies were performed with the
  flatworm *planaria*; these will not be discussed here at all, partly
  because of a dispute over the reliability of the type of conditioning
  used in the experiments (which involve training a flatworm, which
  characteristically reacts to light by elongating, and to shock by 
  contracting, to contract in response to the light instead) and
  partly because virtually all the claims earlier made for flatworms
  have now been made for mammalian systems as well...

  So far as the mammalian experiments are concerned, several groups
  of workers in 1964-1965 claimed to have been able to transfer a
  learned response -- for example, the correct path in a maze or
  the association of the sound of a `click' or the flashing of a 
  light with the presentation of food -- between one rat and another
  using a phenol-extracted preparation of RNA from the brain of the
  trained animals.  One group went so far as to claim inter-species
  transfer...  Attempts to replicate these experiments, however,
  proved unsuccessful.  It was then suggested that the `transfer
  factor' might be some nonRNA contaminant of the phenol extract
  of the brain, and two groups...have now made more extensive studies
  of such potential contaminants.

He went on to analyze and critique the data, which was brand new
at the time.  His skepticism is apparent.

Numerous references to the planarian controversy, which raged up to
and around 1966, are given; here are 2 which seem to be representative:
  Hartry, A.L. et al. (1964) Planaria: memory transfer through
      cannabalism re-examined.  Science 146:274-275.
  Jacobson, A.L. et al. (1966) Planarians and memory.
      Nature 209:599-601.

The most recent reference to the whole memory-transfer business
that I could find was in _Basic Neurochemistry_, 4th edition,
Siegel et al., eds., Raven Press, NY, 1989.  p. 924.
In it, Bernard Agranoff writes, "The claims in the 1960s of memory
transfer via injection of RNA or of protein have long since
subsided for want of evidence."

He notes that there has been a recent study (1986) suggesting that
one of the "memory transfer" substances was actually an enkephalin-
like peptide (Wilson, D., Scotophobin resurrected as a neuropeptide,
Nature 320:313-314).

One last source to check: Tsukada & Agranoff, _Neurobiological
Basis of Learning and Memory_, Wiley, NY, 1980.
--

Steve Matheson   Program in Neuroscience   University of Arizona
[email-masked]