See U.S. Department of Agriculture.

A genus of rod-shaped, gram-negative bacteria that are a common cause of food poisoning.

A small, self-splicing RNA molecule that accompanies several plant viruses, including tobacco ringspot virus.

A gene whose expression allows one to identify cells that have been transforrned or transfected with a vector containing the marker gene. (See B-Lactamase, Kanr.)

Pollen of one plant is transferred to the female part of the same plant or another plant with the same genetic makeup.

During DNA duplication, each strand of a parent DNA molecule is a template for the synthesis of its new complementary strand. Thus, one half of a preexisting DNA molecule is conserved during each round of replication.

Francis Crick's seminal concept that genetic information exists as a linear DNA code; DNA and protein sequence are colinear.

A unique (single-copy) DNA sequence used as a mapping landmark on a chromosome.

The process where two cells (gametes) fuse to form one hybrid, fertilized cell. See Asexual reproduction, Gamete, Hybrid.

The biochemical events that conduct the signal of a hormone or growth factor from the cell exterior, through the cell membrane, and into the cytoplasm. This involves a number of molecules, including receptors, pro- teins, and messengers.

The process of introducing spe- cific base-pair mutations into a gene.

Short RNA transcripts of 100-300 bp that associate with proteins to form small nuclear ribonucleoprotein particles (snRNPs), which participate in RNA processing. (See RNA.)

See Small nuclear RNA.

Any nongerm cell that composes the body of an organism and which possesses a set of multiploid chromosomes (diploid in most organisms). (See Gamete, Somatic cell gene therapy.)

The repair or replacement of a defective gene within somatic tissue. (See Somatic cell.)

See Human growth hormone.

See Southern hybridization.

A procedure in which DNA restriction fragments are transferred from an agarose gel to a nitrocellulose filter, where the denatured DNA is then hybridized to a radioactive probe (blotting). (See Hybridization.)

A classification of related organisms that can freely interbreed.

A form taken by certain microbes that enables them to exist in a dormant stage. It is an asexual reproductive cell. See Asexual reproduction, Dormant.

The plateau of the growth curve after log growth, during which cell number remains constant. New cells are produced at the same rate as older cells die. (See Growth phase.)

A protruding, single-stranded nucleotide se- quence produced when a restriction endonuclease cleaves off center in its recognition sequence.

See Termination codon.

Reaction conditions--notably temperature, salt, and pH--that dictate the annealing of single-stranded DNA/DNA, DNA/RNA, and RNA/RNA hybrids. At high stringency, duplexes form only between strands with perfect one-to-one complementarity; lower stringency allows annealing between strands with some degree of mismatch between bases.

A plasmid that only replicates along with the main bacterial chromosome and is present as a single copy, or at most several copies, per cell. (See plasmid.)

The scientific tradition that stresses the relationship between a physical structure and its function, for example, the related disciplines of anatomy and physiology.

See Sequence-tagged site.

The process of tranferring a cloned DNA fragment from one vector to another. (See Cloning.)

A vaccine composed of a purified antigenic determinant that is separated from the virulent organism. (See Vaccine, Enzyme.)

The predominant in vivo form of plasmid, in which the plasmid is coiled around histone-like proteins. Supporting proteins are stripped away during extraction from the bacterial cell, causing the plasmid molecule to supercoil around itself in vitro. (See Plasmid.)

A group of neighboring genes on a chromosome that tend to be inherited together and sometimes are functionally related.

The soluble liquid &action of a sample after centrifugation or precipitation of insoluble solids.

The close association of two or more dissimilar organisms where both receive an advantage from the association. See Commensalism, Parasitism

The pairing of homologous chromosome pairs during prophase of the first meiotic division, when crossing over occurs.