Date: Mon, 26 Apr 1999 01:11:26 +0100
From: Chris Lees <chrislees@easynet.co.uk>
To: memetics@mmu.ac.uk
Subject: Re: Darwin and Lamarck
I sent this once but it does not seem to have got through.
Perhaps it was too long. Some listservs bounce mails over
a certain size. This is part 1.
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Jake wrote :
> If you are thinking about some other idea
> as "Lamarkianism" then I would be interested to know what you are talking
> about.
You don't deserve this Jake, but i find it difficult to bear grudges,
and
I can spare you a few mouseclicks, in the interests of bona fide
science.
Like I said, I think there was clear evidence for epigenetic inheritance
found maybe twenty or more years ago. Why mainstream science refused
to acknowledge that evidence, is a question in its own right. Until I
know a
better answer, I suspect scientism, a blinkered compliance to orthodox
ideology, the antithesis of true scientific open-mindedness.
Chris.
http://easyweb.easynet.co.uk/~chrislees/Epilogus/epilogus1.html
--------------------------------------
> Epigenetic Inheritance NS 28 Nov 98 27
>
> I M A G I N E aliens from Outer Space announcing that they had engineered
> lasting alterations into the human race. The changes are going to make our
> children, and our children's children, smaller, weaker and easier to
> control. But grassroots resistance is fierce, and soon technicians are
> working round the clock to screen millions upon millions of human genomes in
> an effort to weed out anyone whose genes show signs of alien tinkering.
>
> A mystery swiftly unfolds. The human genes appear to be untouched, yet
> downsized babies are born in ever-increasing numbers. Then, just when it
> looks like our number's up, the aliens take pity and decide to reveal their
> biotechnical knowhow. "There's more to heredity than DNA," an alien boffin
> begins ...
>
> Back in the real world, molecular biologists now sequencing DNA as part of
> the multimillion-dollar human genome project will finish the job in a few
> years. Yet masters of the genome we won't be. A spate of mysterious
> observations made by Earthling scientists suggest that those alien boffins
> are right-that there is a lot more to heredity than DNA. just as cells
> inherit genes, they a ' Iso inherit a set of instructions that tell the
> genes when to become active, in which tissue and to what extent. This much
> is uncontroversial. Without this "epigenetic" instruction manual,
> multicellular organisms would be impossible. Every cell, whether it's a
> liver cell or a skin cell, inherits exactly the same set of genes, and it is
> the manual, which has different instructions for different cell types, that
> allows the cell to develop its distinctive identity.
>
> Established theory has it that the instruction manual is wiped clean during
> the formation of sperm and egg cells, ensuring that all genes are equally
> available, until the embryo starts to develop specific tissues. But
> outlandish evidence now suggests that changes in the epigenetic instruction
> manual can sometimes be passed from parent to offspring. These findings have
> even inspired some biologists to suggest that changes in the manual passed
> down through the generations could provide a way for populations of animals
> to quickly adapt to their environment, creating a fast-track supplement to
> the more sedate Darwinian selection.
>
> Speculation aside, one thing is certain. "Bizarre things are going on that
> we are just beginning to get a handle on," says Marcus Pembrey, a clinical
> geneticist at the Institute of Child Health in London. ,R Consider the
> pregnant Dutch women who starved during the famine of the Second World War.
> Not unexpectedly, thev had small babies. Far more surprisingly, those babies
> went on to have small babies, even though the postwar generation was well
> fed and no genes had been tinkered with. Then there are the perplexing
> findings in mice and rats. Give just one generation of male rats a drug
> called alloxan, which decreases the body's sensitivity to the hormone
> insulin, and their offspring and their offspring's offspring become
> progressively more prone to diabetes. Expose mice to high doses of morphine
> and the damage to the nervous system persists in their descendants. And one
> injection of the thyroid hormone thyroxine into a newborn rodent permanently
> depresses levels of both that hormone and thyroid stimulating hormone-and
> levels remain low in the next generation, too. Many of these observations
> are decades old and have long been relegated to the scrap heap of
> unexplained and inconvenient findings. They trouble geneticists, because
> they seem to fly in the face of classical genetics, even smacking of
> Lamarckian inheritance, the discredited notion that animals actively acquire
> characteristics and pass them on to their offspringby Lamarck's reckoning,
> body builders would beget muscle-bound babies. In fact, the way mammals are
> built should stop a parent's environment having any direct impact on its
> offspring's genes. The sperm and eggs are packed away in ovaries and testes
> from very early in development. VVhile other cells become specialised,
> turning genes on and off to create the different tissues of the body, these
> "germ" cells remain quietly sequestered, shielded from the environment,
> until called upon to pass their still pristine genes on to the next
> generation. So it's not surprising that scientists have tried to explain
> away the disturbing aftermath of the Dutch famine and the results of the
> mice and rat experiments with more conventional reasoning. Did the first
> generation of small babies suffer some strange hormonal imbalance which,
> when they reached adulthood, affected the growth of their infants in the
> womb? Or in the case of the rodent experimentswhich passed down the male
> line, toowere the experiments just plain suspect? No firm conclusions were
> ever reached, but doubts lingered. "It has become difficult for people to
> think of heredity as involving non-genetic material," says Steven Rose, a
> biologist at Britain's Open University in Milton Keynes. The research has
> continued, he p says, but epigenetic research "remains cr semi-underground.
> You're not supposed ti to talk about it". That, however, could h be about to
> change. Last year, Wolf Reik, s a molecular biologist at the Babraham p
> Institute outside Cambridge, and his h colleagues at the Free University in
> Berlin, i stumbled upon the best evidence yet that 9 epigenetic changes can
> pass from one gen c eration of mammals to the next. Reik's main interest is
> in an epigenetic c phenomenon called "imprinting". Genes ti exist in pairs,
> one from the mother, one ti from the father. And whereas most t genes in
> animals such as mice and e humans behave in exactly the same way regardless
> of which parent they come from, imprinted genes are different. In some
> cases, an imprinted gene is activated only if it is inherited from the
> father; in other cases, only if it comes from the mother. No one knows quite
> how this process works, but clearly some sort of "mark" must persist through
> the generations to tell the offspring's cells which genes to re-imprint.
> While much about imprinted genes remains a mystery, initial studies suggest
> that they often help to regulate the growth of the fetus, and that they are
> marked for shutdown by small, molecular clusters called methyl groups
> ("Where did you get your brains?" Nezv Scientist, 3 May 1997, p 34). The
> methyl groups both block transcription-the first step in gene
> activation-and, by binding certain proteins, help to fold the DNA into
> tight, inaccessible coils. Other control mechanisms, still poorly
> understood, are also at work. But however they work, the existence of
> imprinted genes demonstrates that, each generation, not all genes are wiped
> totally clean of their epigenetic marks. Last year, Reik and his colleagues
> found clues to the identity of genes that potentially, at least, carry
> epigenetic information with them as they move from parents to offspring.
> First, the researchers discovered that some genes become methylated if you
> move the nucleus from a just-fertilised mouse embryo into the egg of a mouse
> of a different strain that had had its nucleus removed, and then put the
> newly manufactured embryo into the womb of another mouse and let it develop
> normally. The resulting mouse pups were also noticeably smaller. By
> measuring the amount of protein in the livers, brains and hearts of these
> mice, Reik was able to show that two genes had been shut down: a gene for a
> liver protein called major urinary protein (MUP) and a gene for a protein
> made in the cells lining the nose, called olfactory marker protein (OMP).
> Although the DNA sequence of each gene remained unchanged, they had been
> methylated.
>
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