Animal cloning
See cloning.

Animal genetic resources databank
A databank that contains inventories of farm animal genetic resources and their immediate wild relatives, including any information that helps to characterize these resources.

Animal genome (gene) bank
A planned and managed repository containing animal genetic: resources. Repositories include the environment in which the genetic resource has developed, or is now normally found (in situ) or facilities elsewhere (ex situ - in vivo or in vitro) For in vitro, ex situ genome bank facilities, germplasm is stored in the form of one or more of the following: semen, ova, embryos and tissue samples.

Anion
A negatively charged ion; opposite: cation

Anneal
The pairing of complementary DNA or RNA sequences, via hydrogen bonding, to from a double-stranded polynucleotide. Most often used to describe the binding of a short primer or probe.

Annealing
1. The process of heating (de-naturing step) and slowly cooling (re-maturing step) double-standard DNA to allow the formation of hybrid or complementary strands of DNA or of DNA and RNA.
2. A generic term used to denote a heat treatment wherein the microstructrure and, consequently, the properties of a material are altered. Frequently; refers to heat treatment whereby a cold-worked metal is softened by allowing it to recrystallize.

Antagonism
An interaction between two organisms (e.g., moulds or bacteria) in which the growth of one is inhibited by the other. cf synergism.

Antagonist
A compound that inhibits the effect of an agonist in such a way that the combined biological effect of the two becomes smaller than the sum of their individual effects.

Anther culture
The aseptic culture of anthers for the production of haploid plants' from microspores. See androgenesis; gynogenesis; parthenogenesis.