chim-, chimer- +

(Greek: khimaira, fabled monster; unreal, fantastic, imaginary, fanciful, unrealistic; however, in medical and other scientific fields, characterized by two or more genetically distinct cell types in one organism)

blood group chimerism
Having two stable, genetically distinct lines of blood cells, which can often be distinguished based on differences in blood group antigens.

In humans, this usually rises when blood cells from one dizygous twin mixes with the co-twin in utero; the organ in a woman’s body where babies develop before birth.

Chimera
One of the most fearsome creatures in Greek mythology; as a fire-breathing female monster, she resembled a lion in the forequarters (lion's head), a goat in the midsection (goat's body), and a dragon in the hindquarters or a snake's tail.

Some works of art also showed a goat's head coming up from her back; in fact, the original meaning of chimaira was "young she goat".

The Chimera destroyed everything in her path until Bellerophon (a mythical Greek hero of Corinth), astride his winged horse Pegasus, attacked her from above and killed her with a multitude of arrows.

By the sixteenth century, the chimera had become a symbol of "incongruity and of unrestrained fancy".

Currently, chimera refers to "an unreal or unrealizable creature of the imagination".

—Compiled from information located in
Webster's Word Histories; Merriam-Webster, Inc., Publishers;
Springfield, Massachusetts; 1989; pages 105-106.
chimera, chimaera (s) (noun); chimeras, chimaeras (pl)
1. Something that exists only in the imagination or is a creation of the imagination; an impossible and foolish fancy; and so it is not possible in reality: Economic stability in our country has become a chimera.
An impossible and foolish imagination.
© ALL rights are reserved.

Go to this Word A Day Revisited Index
for a list of additional Mickey Bach illustrations.

2. In biology, an organism; especially, a cultivated plant, containing tissues from at least two distinct genetic types, often because of grafting; consisting of two or more genetically distinct cell types, produced as a result of mutation, transplantation, or grafting; the fusing of different embryos, or other similar processes: The fraternal twins were not chimeras as their blood types were different from each other.
3. In experimental embryology, the individual produced by grafting an embryonic part of one animal onto the embryo of another animal, either of the same or of different species: There was excitement in the laboratory when a successful chimera from the experimental transplant was announced.
4. A person who, or an organism which, has received a transplant of genetically and immunologically different tissue; such as, bone marrow: The multi stage process resulted in the successful transplant of bone marrow; the chimera who received the transplant is beginning to recover.

Human chimeras were first discovered with the introduction of blood typing when it was found that some people had more than one blood type.

Most of them proved to be "blood chimeras" or non-identical twins who shared a blood supply in the uterus.

chimeral (adjective), more chimeral, most chimeral
1. A reference to being imaginary, fanciful, unreal, or visionary: The religious leader presented a future chimeral paradise to his followers.
2. Relating to being wildly fanciful or highly unrealistic: The politician suggested a chimeral plan to improve the economy, which was considered ridiculous by the others who were on the committee.
3. A description of an organism that is composed of genetically different tissues, either naturally or as a result of laboratory procedures: The farmer had a chimeral goat that was more like a sheep than a goat.
Merely imaginary; an unrealistic idea.
© ALL rights are reserved.

Usually an imaginary or an unrealistic idea.
© ALL rights are reserved.

Go to this Word A Day Revisited Index
for a list of additional Mickey Bach illustrations.

chimeraplast (s) (noun), chimeraplasts (pl)
A synthetic molecule made up of both RNA (nucleic acid found in all living cells) and DNA (molecule that encodes genetic information in the nucleus of cells) which is used in gene repair.

Chimeraplasts are made to match the patient's sequence of base pairs (the molecular building blocks of DNA), except in one area, the area of the mutation (the change) that is responsible for the gene defect where the chimeraplasts have the correct sequence of base pairs in the DNA.

The chimeraplasts are designed to attach to the patient's DNA and to activate the DNA repair system, a system that cells normally use to correct mistakes they make in replicating their DNA.

The patient's DNA repair system is tricked into treating the chimeraplast as the correct version of the DNA and changing the patient's gene to match the chimeraplast; and so, correcting the mutation.

chimeraplasty
A method of gene therapy based on the use of a molecule called a chimeraplast, a synthetic blend of DNA and the related molecule RNA, to trick the patient's own cells to remedy a gene defect.
chimeric (adjective)
1. Being imaginary or unreal.
2. In genetics, a reference to or relating to a chimera or to chimerism; that is, containing two or more genetically distinct cell types.
3. Composed of parts which are of different origins that are seemingly incompatible.
chimeric plasmid
In genetics, a plasmid which has received new DNA sequences that enable it to contain two connected DNA sequences; one of which represents the original plasmid molecule.
chimeric protein
A protein consisting of a mixture of sequences from different sources.
chimerical (adjective), more chimerical, most chimerical
1. An unfounded, unrealizable dream: Lucy had a chimerical desire to become a famous pianist and to tour the world.
2. Imaginary concepts or irrational ideas and proposals: There are too many politicians who have chimerical thoughts of developing economic stability in the nation.

Some hypothetical ideas are nothing more than foolish views; so, when people refer to a chimerical scheme, it is regarded as being unrealistic and won't work because it is considered to be a fantastic figment of someone's imagination.

Merely imaginary; an unrealistic idea.
© ALL rights are reserved.

Fanciful or in one's imagination.
© ALL rights are reserved.

Go to this Word A Day Revisited Index
for a list of additional Mickey Bach illustrations.

chimerism
1. In bone marrow, a transplantation in which bone marrow and host cells exist compatibly without any signs of graft-versus-host rejection disease.
2. A condition or state of containing two or more genetically distinct cell types.

In humans, chimerism results from any organ transplant other than that between identical twins or from the mixture of blood cells between dizygous twins (either of two twins who developed from two separate fertilized eggs) in the uterus before birth.

A dizygotic twin refers to either of the "fraternal" twins who has shared a common uterine environment with its twin which is a result of a different fertilized ovum.

heterologous chimera
In experimental genetics, a chimera which is formed by cells or tissues from two different species.
homologous chimera
A chimera formed by cells or tissues from organisms of the same species but with a different genotype.

It exists in humans most commonly when the blood of dizygous twins mixes in utero (the organ in a woman’s body where babies develop before birth).

isologous chimera
A chimera that is formed by cells or tissues from two different organisms which have the same genotype.

Such a case is difficult to recognize in humans; however, it might occur when the blood of monozygous twins (identical twins that originate from a single fertilized egg) mixes in utero; or the hollow muscular organ in the pelvic cavity of a female, in which the embryo (baby) is nourished and develops before birth.

radiation chimera, irradiation chimera
1. An organism displaying immunologic characteristics of both host and donor following whole-body radiation to neutralize an immune response to the donor's cells, as in a bone marrow graft.
2. A medical patient who has been subjected to whole body irradiation to lower immune responses to foreign donor cells and therefore has the immunological characteristics of both host and donor after a bone marrow graft from the antigenically different donor.