Crutch wrote:
> >> Can a 'clone' of yourself be manipulated to the opposite sex?
Hal wrote:
> >I would guess that
> >you might be able to turn a male into a female by removing the Y and
> >duplicating the X (maybe borrowing an X from another cell).
Damien replied:
> No. (We did this discussion a few weeks back.) Genomic imprinting means
> you need chromosomes from both sexes - even a female needs an X from mother
> and an X from father. Here's why:
> [...]
> Even before conception, genetic Darwinism is at work, labelling certain
> chunks of DNA - and not just in the sex chromosomes - to mark their origin
> in either mother's or father's germ cells, and to activate them only under
> particular circumstances. We need imprinted genes from both sex lines,
> since they do different jobs. That is one reason why radical hopes of
> creating an embryo by splicing together the haploid DNA of two spermatozoa
> (a baby with two genetic fathers) or two ova (a baby with two genetic
> mothers) won't work without very refined gene engineering, to the chagrin
> of some homosexual and lesbian couples. This, though, is not a futuristic
> gay utopia scenario - it was tried in 1984 using mice sperm and ova, and
> failed. In each case, a number of critical genes had been switched off in
> the DNA contributed by the two fathers or two mothers, so foetal
> development stalled. Mother-marked genes control early embryo growth, and
> the father-marked genes kick in with later development.
However, this experiment apparently was done with sex cells (sperm and eggs). It could be that this labelling as to mother/father is done only during meiosis, when the genes are split up so that only half end up in each sex cell. Conceivably the labels are lost during embryonic or fetal development (although this may not be likely). It would still be an interesting experiment to create a clone from a more mature cell, with duplicate copies of one X chromosome (or any other chromosome) rather than the two X chromosomes the cell starts with.
Have all clones so far been females? Is there any reason why males cannot be cloned?
Hal