homeosis


Also found in: Dictionary, Medical, Wikipedia.

Homeosis

The formation of a normal plant or animal body structure or organ in place of another at an abnormal site. Examples of homeosis (also called homeotic transformation) are most obvious in insect appendages, where an appendage that is characteristic of one segment, for example the antennae on an insect head segment, are transformed into insect legs that normally develop only on trunk segments. Similar examples of homeotic transformations can also occasionally be found in vertebrates where lumbar vertebrae are transformed into thoracic vertebrae which then extend into rib processes, or in floral organs where petals are transformed into sepals. Homeotic transformations rarely occur in nature in living organisms, and are due to genetic defects in a class of proteins called homeotic proteins, the products of homeotic genes. Homeotic transformations may also be induced in the laboratory by the accidental or deliberate manipulation of homeotic gene expression so that homeotic proteins are produced in the wrong place or at the wrong time in developing plants and animals. See Cell differentiation, Developmental biology, Developmental genetics, Gene action, Mutation

homeosis

[‚hō·mē′ō·səs]
(biology)
References in periodicals archive ?
Homeosis in floral development of Sanguinaria canadensis and S.
Floral development and homeosis in Actaea rubra (Ranunculaceae).
The best-known example of homeosis in plants is the replacement of one kind of floral organ by another.
A good example of partial homeosis is the development of male flowers on the heteromorphic inflorescences in Neptunia pubescens (Leguminosae).
Although most studies of homeosis in plants focus on its role in floral morphological evolutionary changes (e.
In many cases, the developmental changes explained with heterochrony can also be interpreted by homeosis (Jordan & Anthony, 1993).
Homeosis and heterotopy are therefore overlapping concepts: complete homeosis is simply heterotopy.
Other development-related mechanisms, such as homeosis and heterotopy, are important causes of evolutionary morphological change.