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Thread: Chimeras

  1. #1

    Chimeras

    I'm still fascinated by this. Another unique thing about these women is they can only bear male children. Now that I'm aware of them, I swear I can spot one lol. There is the old theory that more than 2 genders exist. Chimeras carry the DNA of two different individuals. They are essentially males with female reproductive organs. In the case of one of the woman on the show, some of the hairs plucked from her head and used for DNA analysis contained unrelated male DNA and some were female. What do you think about this phenomenon Dr. Young.

    http://sci.rutgers.edu/forum/showpos...7&postcount=18

    When two became one in the womb
    Mother and baby
    Some babies could have started life as twins


    Jane was a puzzle to doctors. She needed a kidney transplant, but her naturally conceived sons could not donate - because they were not biologically related.

    Tests eventually showed Jane was a chimera - her mother had been pregnant with non-identical twins who had fused together in the womb to make one person.

    It meant some parts of her are derived from one twin, and the rest from the other.

    Jane, 52, was seen by doctors at the Beth Israel Deaconess Medical Centre in Boston, Massachusetts.

    Medical staff had tested her three sons to see if they were a close enough tissue match to act as kidney donors.

    But New Scientist magazine reports genetic tests showed two of her sons could not be hers.

    'Male and female organs'

    Closer analysis found Jane was a tetragametic chimera - made up of two genetically distinct type of cells.

    The term chimera comes from the Greek word for a monster that was part lion, part goat and part serpent.

    She had one twin's cells in her blood, which showed up in the tissue-typing tests the scientists carried out. But in other tissues, including her ovaries, the other twin's genes dominated - explaining the initially mysterious test results.

    Embryo
    A single embryo can be formed from two sets of egg and sperm
    Jane's condition emerged by chance, and scientists say many other chimeras probably go through life unaware of their genetic make up.

    Some do display physical signs, however, such as having different coloured eyes.....
    http://news.bbc.co.uk/2/hi/health/3264467.stm
    Last edited by Wise Young; 11-12-2006 at 05:20 PM. Reason: edited in error

  2. #2

    Another interesting thing ...

    about the chimera which if you read explains hermaphroditism.

    Tetragametic chimerism is a less common cause of congenital chimerism. It occurs through the fertilization of two ova by two sperm, followed by the fusion of the zygotes and the development of an organism with intermingled cell lines. This happens at a very early stage of development, such as that of the blastocyst. Such an organism is called a tetragametic chimera as it is formed from four gametes — two eggs and two sperm. Put another way, the chimera is formed from the merger of two fraternal twins in a very early (zygote or blastocyst) phase. As such, they can be male, female, or hermaphroditic.

    <snip>

    Affected persons are identified by the finding of two populations of red cells or, if the zygotes are of opposite sex, ambiguous genitalia and hermaphroditism alone or in combination; such persons sometimes also have patchy skin, hair, or eye pigmentation (heterochromia). If the blastocysts are of the same sex, it can only be detected through DNA testing, although this is a rare procedure. Thus the phenomenon may be more common than currently believed. If the blastocysts are of opposite sex, genitals of both sexes are formed, either ovary and testis, or combined ovotestes, in one rare form of intersexuality, a condition previously known as true hermaphroditism. As of 2003, there were about 30-40 human cases in the literature, according to New Scientist.
    http://en.wikipedia.org/wiki/Chimera_(genetics)

    Some known hemaphrodites are either chastised or have been looked down on. How little we know at times.

    Raven

  3. #3
    I saw a really good story on TLC about this subject called
    "I am my own twin". Watch it if you can.

  4. #4
    Senior Member lynnifer's Avatar
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    That's where I learned about it as well ... reasonable doubt in DNA cases?
    Roses are red. Tacos are enjoyable. Don't blame immigrants, because you're unemployable.

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  5. #5
    Quote Originally Posted by antiquity
    I'm still fascinated by this. Another unique thing about these women is they can only bear male children. Now that I'm aware of them, I swear I can spot one lol. There is the old theory that more than 2 genders exist. Chimeras carry the DNA of two different individuals. They are essentially males with female reproductive organs. In the case of one of the woman on the show, some of the hairs plucked from her head and used for DNA analysis contained unrelated male DNA and some were female. What do you think about this phenomenon Dr. Young.

    http://sci.rutgers.edu/forum/showpos...7&postcount=18



    http://news.bbc.co.uk/2/hi/health/3264467.stm
    Sen, I am not sure what to think. While I was a medical student, I studied kids that were phenotypically female but genetically male, but they are not fertile. This is the first time that i have heard of tetragametic chimera in human. These things can and do happen in animals. For example, the most common species of African clawed toads (Xenopus Laevis) normally have four or more sets of chromosomes (e.g. tetraploid, octoploid, and even dodecaplooid). They provide a fascinating model of immunebiology (Source).

    Apparently, according to Wikipedia (Source), chimeric children are more likely from in vitro fertilization. Moreover, there is great interest in this phenomenon because of the tendency of embryonic stem cells to fuse and to form tetraploid or even octoploid cells. There are two well-known cases, i.e. Lydia Fairchild and Karen Keegan. Chimeras typically have immune tolerance to both sets of genes.

    There is another aspect of this that is fascinating. For some time now, I have been interested in the possibility of injecting stem cells into fetuses and seeing if the resulting adult becomes immune tolerate to the stem cells that were injected. This is a fascinating possibility because this means that a person might be induced to be tolerant of a stem cell line that can then be used to treat the person. This could solve the problem of stem cell sources.

    There is also the question of feto-maternal chimerism, i.e. the mother harboring the cells of fetuses that they had. Apparently, a majority of mothers carry the cells of their children in their body, implying that they have become somehow immune-tolerant of these cells. These mothers could potentially be recipients of stem cells donated by their children.

    Wise.

  6. #6
    Quote Originally Posted by Wise Young
    Sen, I am not sure what to think. While I was a medical student, I studied kids that were phenotypically female but genetically male, but they are not fertile. This is the first time that i have heard of tetragametic chimera in human. These things can and do happen in animals. For example, the most common species of African clawed toads (Xenopus Laevis) normally have four or more sets of chromosomes (e.g. tetraploid, octoploid, and even dodecaplooid). They provide a fascinating model of immunebiology (Source).

    Apparently, according to Wikipedia (Source), chimeric children are more likely from in vitro fertilization. Moreover, there is great interest in this phenomenon because of the tendency of embryonic stem cells to fuse and to form tetraploid or even octoploid cells. There are two well-known cases, i.e. Lydia Fairchild and Karen Keegan. Chimeras typically have immune tolerance to both sets of genes.

    There is another aspect of this that is fascinating. For some time now, I have been interested in the possibility of injecting stem cells into fetuses and seeing if the resulting adult becomes immune tolerate to the stem cells that were injected. This is a fascinating possibility because this means that a person might be induced to be tolerant of a stem cell line that can then be used to treat the person. This could solve the problem of stem cell sources.

    There is also the question of feto-maternal chimerism, i.e. the mother harboring the cells of fetuses that they had. Apparently, a majority of mothers carry the cells of their children in their body, implying that they have become somehow immune-tolerant of these cells. These mothers could potentially be recipients of stem cells donated by their children.

    Wise.
    Geez, is there anything you don't know? You should be contestant on Jeopardy.

  7. #7
    Quote Originally Posted by lynnifer
    reasonable doubt in DNA cases?
    Ooh, good question.

    C.

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