Chromosomal landing is a genetic technique used to identify and isolate clones in a genetic library. Chromosomal landing reduces the problem of analyzing large, and/or highly repetitive genomes by minimizing the need for chromosome walking. It is based on the principle that the expected average between-

marker The term Marker may refer to: Common uses * Marker (linguistics), a morpheme that indicates some grammatical function * Marker (telecommunications), a special-purpose computer * Boundary marker, an object that identifies a land boundary * Marke ...

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

s can be smaller than the average insert length of a clone library containing the gene of interest. From the abstract of : :The strategy of

chromosome walking Primer walking is a technique used to clone a gene (e.g., disease gene) from its known closest markers (e.g., known gene). As a result, it is employed in cloning and sequencing efforts in plants, fungi, and mammals with minor alterations. This te ...

is based on the assumption that it is difficult and time consuming to find DNA markers that are physically close to a gene of interest. Recent technological developments invalidate this assumption for many species. As a result, the mapping paradigm has now changed such that one first isolates one or more DNA marker(s) at a physical distance from the targeted gene that is less than the average insert size of the genomic library being used for clone isolation. The DNA marker is then used to screen the library and isolate (or 'land' on) the clone containing the gene, without any need for chromosome walking and its associated problems. Chromosome landing, together with the technology that has made it possible, is likely to become the main strategy by which

map-based cloning A genetic screen or mutagenesis screen is an experimental technique used to identify and select individuals who possess a phenotype of interest in a mutagenized population. Hence a genetic screen is a type of phenotypic screen. Genetic screens c ...

is applied to isolate both major genes and genes underlying quantitative traits in

plant Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

species.

References

{{reflist Molecular biology Genetic engineering

See also

References