From: Damien Broderick (d.broderick@english.unimelb.edu.au)
Date: Thu Sep 12 2002 - 22:41:33 MDT
At 11:50 AM 9/12/02 -0400, Rafal wrote:
>Additionally, there is about 90% attrition of embryos during (especially
>early) pregnancy. This works also in cloning, explaining the low success
>rate of this procedure. If the natural process works only in one in ten,
>then the 1/100 success rate of cloning is not that bad.
>
>Presumably, we could develop an assay for gene expression patterns in the
>preimplantation embryo (e.g. do RT-PCR with universal primers on a single
>cell from the embryo, and then a microarray test for the right mRNA's), and
>apply some additional selection to weed out the abnormal ones before
>pregnancy begins. With total genome sequencing of the nuclear donor cells
>(you take a small sample of the cells right before nuclear transfer) we
>could even weed out genetic defects before cloning begins. Such a procedure,
>which might become possible in the next ten years if the Perlegen project
>works out, would be safer than natural procreation.
Today, children, we'll talk about human reproduction. No sniggering,
please. Yes, we are speaking of S-E-X, but today's lesson will not deal
with smut. We'll discuss how babies are made.
To make a baby we need a Mummy, who provides a big fat ovum crammed with
food and DNA and energy-making mitochondria which she got from her own
Mummy, and a Daddy, who puts in a tiny little chunk of DNA coded either
male or female. Finally, we have an Optimist. This medical specialist is
known in California as a Clinical Optimalizator, but we Aussies consider
that a bit of a wank. Speaking of wanking, that is how we get hold of
Daddy's DNA sperm. It's rather harder to obtain Mummy's eggs, because first
a slice of her stored ovary tissue has to be thawed out.
The cells from Mummy and Daddy each contain 22 strings of nearly identical
instructions for starting a baby, plus the sex-making string. In the bad
old days, these messages written in DNA were often garbled in places, like
a buggy computer program. Babies begun with really messy code--nine out of
every ten--aborted spontaneously or died long before they were born. Once a
medical cure for damaged code was found, nearly all the babies that got
started went on to become people. The Pope banned the evil sin of "bestial
congress", which was reproductive S-E-X as animals do it. So many souls
were being lost! Today, only criminals risk making babies the dangerous,
godless old way.
This is where the Optimist comes in. She sorts through Mummy's and Daddy's
cells with a gene chip and picks out those with the fewest bad mutations.
Then she pops in a pair of safe artificial auxosomes to proof-read any
remaining errors, correct mangled instructions, and add those optimal extra
genes that help us resist infection and mental illness, think really fast,
and live for a very long time without getting old and silly. She could
choose whether the baby is a boy or girl, but that's illegal, of course.
Damien Broderick
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