sound is radiated both as air-borne and as structure-borne; most sources produce both, thus various noise attenuation principles must be employed. Measures include: the replacement of components with quieter parts and material; the enclosure of particularly noisy components; the selection of quieter types of fan; the replacement of noisy compressed-air nozzles with quieter types; the choice of quieter transmission and cooling systems.
mature erythrocyte that lacks ribosomes and can be distinguished from immature, polychromatic erythrocytes by stains selective for ribosomes.
a gel-based laboratory procedure that locates mRNA sequences on a gel that are complementary to a piece of DNA used as a probe.
nuclear transfer is a type of cloning, a laboratory procedure in which a cell's nucleus is removed and placed into an oocyte with its own nucleus removed so the genetic information from the donor nucleus controls the resulting cell. Such cells can be induced to form embryos. This process was used to create the cloned sheep "Dolly".
a subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA). Thousands of nucleotides are linked to form a DNA or RNA molecule.
the cellular organelle in eukaryotes that contains most of the genetic material.
a change in the number of chromosomes from the normal number characteristic of the animals utilized. Used for identifying potential genotoxic substances.