Glossary

In stainless steel, the same as its maximum depth of enrichment, unless a surface iron layer is present in which case the chromium enrichment layer is calculated as the maximum depth of enrichment minus the thickness of the surface iron oxide layer.

Body produced by fusion of the heterochromatic regions of the chromosomes in the polytene tissues (e.g., the salivary glands) of certain Diptera.

One of the serially aligned beads or granules of a eukaryotic chromosome, resulting from local coiling of a continuous DNA thread.

The loss of part of a chromosome’s DNA.

Chromosome segments that have been turned 180 degrees. The gene sequence for the segment is reversed with respect to rest of the chromosome.

1. A single DNA molecule, a tightly coiled strand of DNA, condensed into a compact structure in vivo by complexing with accessory histones or histone-like proteins.2. A group of nuclear bodies containing genes which are largely responsible for the differentiation and activity of a eukaryotic cell; one of the bodies into which the nucleus resolves itself at the beginning of mitosis and from which it is derived at the end of mitosis. Chromosomes contain most of the cell’s DNA. Chromosomes exist in pairs in eukaryotes – one paternal (from the male parent) and one maternal (from the female parent). Each eukaryotic species has a characteristic number of chromosomes. Bacterial and viral cells contain only a single chromosome, consisting of a single or double strand of DNA or, in some viruses, RNA, without histones.

A change in the gross structure of a chromosome, usually causing severely deleterious effects in the organism. They are often due to an error in pairing during the crossing-over stage of meiosis. The main types of chromosome mutation are translocation, duplication, deletion and inversion.

Attachment of certain fluorescent dyes to targeted parts of the chromosome. Used as a diagnostic for particular diseases, e.g. types of leukemia.

A designation for the short arm of a chromosome.

A designation for the long arm of a chromosome.

A technique that identifies overlapping cloned DNA fragments that form one continuous segment of a chromosome. These fragments can be generated either by random shearing or by partial digestion with a four-base-pair cutter such as Sau3A. A series of colony hybridizations is then carried out, starting with some cloned fragment which has already been identified and which is known to be in the region encompassed by the overlapping clones. This identified fragment is used as a probe to pick out clones containing adjacent sequences. These are then used as probes themselves to identify clones carrying sequences adjacent to them and so on. At each round of hybridization one “walks” further along the chromosome from the initial fragment.

Occurring over a long time

Contact with a substance that occurs over a long time (more than one year).

Chemical Hazards Science Branch (CFSAN)

Criminal Investigator

Chemical Ionization

Clinical Investigator

Configuration Item

Continuous Infusion

Critical Infrastructure and Key Resources

Chemical Industries Association (United Kingdom)

Central Intelligence Agency (United States)

Corporate Integrity Agreement

Component Impact Assessment

Computer Incident Advisory Capability (U.S. Department of Energy)