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Deletion Mutation
528
D e l e t i o n Mu t a t i o n
homozygosity in a living mouse. Two major strategies have been applied that can induce deletions in ES cells: one involves gene targeting and a Cre-lox protein-mediated intrachromosomal recombination, whereas the other involves exposing ES cells to radiation and selecting, in vitro, for chromosomal deletions. In both cases, mice can eventually be created from ES cells carrying deletions, so that panels of deletions, for fine-structure mapping of the entire genome in the mouse, will be available in the notso-distant future.
Further Reading
Rinchik EM and Russell LB (1990) Germline deletion mutations in the mouse: tools for intensive functional and physical mapping of regions for the mammalian genome. In: Davies K and Tilghman S (eds) Genome Analysis, vol. I. pp. 121±158. Plainview, NY: Cold Spring Harbor Laboratory Press. Silver LM (1995) Mouse Genetics: Concepts and Applications. Oxford: Oxford University Press.
See also: Chromosome Aberrations; Complementation Test; Embryonic Stem Cells; Restriction Fragment Length Polymorphism (RFLP)
Deletion Mutation Copyright ß 2001 Academic Press doi: 10.1006/rwgn.2001.2087
Deletion mutation results in the removal of one or more base pairs from a region of DNA. This can remove an entire gene or even a group of linked genes. Deletion is also referred to as `deficiency.' See also: Mutation; Mutagens
Demes K E Holsinger Copyright ß 2001 Academic Press doi: 10.1006/rwgn.2001.0320
Most widespread species are composed of many populations that are somewhat isolated from one another. A deme is one of these geographically localized populations. It is a group of individuals belonging to a single species occurring in one place at one time.
Table 1 parryae
Correlation in flower color of Linanthus
Distance
Correlation
25 feet 75 feet 250 feet 750 feet 0.5 mile 1.0 mile 1.5 miles 2.0 miles
0.899 0.875 0.817 0.723 0.599 0.505 0.115 0.096
In a species that is predominantly outbreeding, each deme is roughly panmictic. In a species that is predominantly inbreeding, demes are far from panmictic. In both cases, however, members of the same deme are generally part of a gene pool that does not include all members of the species. If there is no possibility of gene exchange between individuals in a particular place, as a result of strict asexual reproduction for example, then the individuals in that place do not form a deme. The defining property of a deme is that it consists of a group of interbreeding individuals. In a large, continuously distributed population, individuals that occur close together are more likely to mate than those that occur far apart. As a result of this isolation by distance the population is not panmictic, even if the individuals of which it is composed are predominantly outbreeding. Neither are there discrete, localized demes that are panmictic within themselves. Instead, such populations are composed of smaller, overlapping demes (genetic neighborhoods) within which mating occurs essentially at random. In Linanthus parryae, a small plant of the California desert, there is a polymorphism for flower color. Some individuals produce white flowers; others produce blue flowers. Epling and Dobzhansky sampled the frequency at 427 locations along approximately 200 miles of roadway in an area just north of the San Bernadino and San Gabriel mountains. They found that the frequency of blue-flowered individuals was highly correlated at distances of up to 1 mile, but that the correlation in frequency could not be distinguished from zero at distances of 1.5 and 2 miles (Table 1). Although hundreds of thousands of individuals occur in this area, Wright calculated that each deme consisted of only 15±25 individuals covering an area of 2±3 square feet. See also: Gene Pool; Isolation by Distance
D e l e t i o n Mu t a t i o n
homozygosity in a living mouse. Two major strategies have been applied that can induce deletions in ES cells: one involves gene targeting and a Cre-lox protein-mediated intrachromosomal recombination, whereas the other involves exposing ES cells to radiation and selecting, in vitro, for chromosomal deletions. In both cases, mice can eventually be created from ES cells carrying deletions, so that panels of deletions, for fine-structure mapping of the entire genome in the mouse, will be available in the notso-distant future.
Further Reading
Rinchik EM and Russell LB (1990) Germline deletion mutations in the mouse: tools for intensive functional and physical mapping of regions for the mammalian genome. In: Davies K and Tilghman S (eds) Genome Analysis, vol. I. pp. 121±158. Plainview, NY: Cold Spring Harbor Laboratory Press. Silver LM (1995) Mouse Genetics: Concepts and Applications. Oxford: Oxford University Press.
See also: Chromosome Aberrations; Complementation Test; Embryonic Stem Cells; Restriction Fragment Length Polymorphism (RFLP)
Deletion Mutation Copyright ß 2001 Academic Press doi: 10.1006/rwgn.2001.2087
Deletion mutation results in the removal of one or more base pairs from a region of DNA. This can remove an entire gene or even a group of linked genes. Deletion is also referred to as `deficiency.' See also: Mutation; Mutagens
Demes K E Holsinger Copyright ß 2001 Academic Press doi: 10.1006/rwgn.2001.0320
Most widespread species are composed of many populations that are somewhat isolated from one another. A deme is one of these geographically localized populations. It is a group of individuals belonging to a single species occurring in one place at one time.
Table 1 parryae
Correlation in flower color of Linanthus
Distance
Correlation
25 feet 75 feet 250 feet 750 feet 0.5 mile 1.0 mile 1.5 miles 2.0 miles
0.899 0.875 0.817 0.723 0.599 0.505 0.115 0.096
In a species that is predominantly outbreeding, each deme is roughly panmictic. In a species that is predominantly inbreeding, demes are far from panmictic. In both cases, however, members of the same deme are generally part of a gene pool that does not include all members of the species. If there is no possibility of gene exchange between individuals in a particular place, as a result of strict asexual reproduction for example, then the individuals in that place do not form a deme. The defining property of a deme is that it consists of a group of interbreeding individuals. In a large, continuously distributed population, individuals that occur close together are more likely to mate than those that occur far apart. As a result of this isolation by distance the population is not panmictic, even if the individuals of which it is composed are predominantly outbreeding. Neither are there discrete, localized demes that are panmictic within themselves. Instead, such populations are composed of smaller, overlapping demes (genetic neighborhoods) within which mating occurs essentially at random. In Linanthus parryae, a small plant of the California desert, there is a polymorphism for flower color. Some individuals produce white flowers; others produce blue flowers. Epling and Dobzhansky sampled the frequency at 427 locations along approximately 200 miles of roadway in an area just north of the San Bernadino and San Gabriel mountains. They found that the frequency of blue-flowered individuals was highly correlated at distances of up to 1 mile, but that the correlation in frequency could not be distinguished from zero at distances of 1.5 and 2 miles (Table 1). Although hundreds of thousands of individuals occur in this area, Wright calculated that each deme consisted of only 15±25 individuals covering an area of 2±3 square feet. See also: Gene Pool; Isolation by Distance