This results in the development of an organism with intermingled cell lines. This condition occurs through the fertilization of two separate ova by two sperm, followed by aggregation of the two at the blastocyst or zygote stages. Tetragametic chimerism is a form of congenital chimerism. Tetragametic chimerism African violets exhibiting chimerism Artificial chimerism Chimeric trait distribution by generationĪrtificial chimerism refers to examples of chimerism that are intentionally produced by humans, either for research purposes or commercial purposes. In this species, the queens have arisen from fertilized eggs with a genotype of RR (Reproductive x Reproductive), the sterile female workers show a RW arrangement (Reproductive x Worker), and the males instead of being haploid as is usually the case for ants also display a RW genotype, but for them the egg R and the sperm W do not fuse so they develop as a chimera with some cells carrying an R and others carrying a W genome. It has been shown that yellow crazy ants are obligate chimeras, the first known such case. See also: Yellow crazy ant § Reproduction Each genotype functions independently in terms of reproduction, but the different intra-organism genotypes behave as a single large individual in terms of ecological responses like growth. Four distinct genotypes have been found in a single individual, and there is potential for even greater genetic heterogeneity. Sponges Ĭhimerism has been found in some species of marine sponges. This process allows for sperm to be in constant supply when the female produces an egg, so that the chimeric fish is able to have a greater number of offspring. Once fused to a female, the males will reach sexual maturity, developing large testicles as their other organs atrophy. In this case, they will all be consumed into the body of the larger female angler. Sometimes in this process, more than one male will attach to a single female as a symbiote. While this attachment has become necessary for the male's survival, it will eventually consume him, as both anglerfish fuse into a single hermaphroditic individual. The male, less than an inch in length, bites into her skin and releases an enzyme that digests the skin of both his mouth and her body, fusing the pair down to the blood-vessel level. Using strong olfactory (or smell) receptors, the male searches until it locates a female anglerfish. Once the male achieves adulthood, it begins its search for a female. Symbiotic chimerism in anglerfish Ĭhimerism occurs naturally in adult Ceratioid anglerfish and is in fact a natural and essential part of their life cycle. Some level of chimerism occurs naturally in the wild in many animal species, however in some cases may be a required (obligate) part of their life cycle. See also: Mosaic (genetics) § History Natural and obligate chimerism For example, transplantation of bone marrow often determines the recipient's ensuing blood type. Īnother way that chimerism can occur in animals is by organ transplantation, giving one individual tissues that developed from a different genome. In contrast, an individual where each cell contains genetic material from two organisms of different breeds, varieties, species or genera is called a hybrid. Normally, genetic chimerism is not visible on casual inspection however, it has been detected in the course of proving parentage. In plant chimeras, however, the distinct types of tissue may originate from the same zygote, and the difference is often due to mutation during ordinary cell division. Animal chimeras are produced by the merger of two (or more) embryos. In animals and human chimeras, this means an individual derived from two or more zygotes, which can include possessing blood cells of different blood types, and subtle variations in form ( phenotype). Two-colored rose chimeraĪ genetic chimerism or chimera ( / k aɪ ˈ m ɪər ə/ ky- MEER-ə or / k ɪ ˈ m ɪər ə/ kim- EER-ə) is a single organism composed of cells with more than one distinct genotype. Not to be confused with Chimera (mythology).
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