Genomic library

A gene library, genomic library, DNA library or library, houses the entire genome of an organism in the form of defined DNA sections on vectors in unicellular organisms carrier or phages. These carrier - organisms are used to store and distribution of the fragments for the purpose of molecular biological investigations.

When creating a gene library of fragments of the complete genome of a specific organism in general, by enzymatic digestion of genomic DNA with restriction enzymes, prepared first. Each fragment contains one or more genes, and is a separate so-called vector into a unicellular organism (E. coli, S. cerevisiae or other ) or phage introduced. This process is also referred to as transformation or transduction. Protozoa of the reproduced along with its own cell division, the multiplication by him inserted DNA fragment, and a colony formed on an appropriate culture medium. In the lab, many colonies are generated and cultured in accordance with required to sequence the entire genome of an organism, fragmented into single colonies to accommodate.

The size of the fragments depends largely on the vectors used for cloning. The capacity (maximum tangible fragment size ) of the vectors relative to the total size of the genome is very small in general. Today YACs and BACs are used, since these vector types quite a high fragment size of up to about 150 kbp and 300 kbp allow. So you can the human genome roughly 3,200,000 kbp in just over 10,000 and 20,000 fragments accommodate. This represents a vast improvement as compared to previous methods, in which the human genome had to be divided into 35 kbp or even 17 kbp fragments. The DNA fragments can also be incorporated into phage whose capacity is, however, much lower (maximum 25 kbp) than that of the aforementioned vectors.

If the gene library once created, a required DNA fragment can be amplified by the cells of the corresponding colony be placed on a suitable culture medium for propagation. By special techniques in molecular biology, the DNA fragment can be reisolated from the carrier body. Here, the used for storage and reproduction organism is lysed, the released DNA was chemically purified and the introduced vector containing the DNA fragment of the host DNA isolated ( Plasmid ). In the laboratory, colonies are usually marked so that it is known which position in the genome corresponds to the fragment harbored. The position of the DNA fragment, by hybridization or by sequencing and comparison of the DNA sequence obtained by a DNA sequence database (eg GenBank ) (and thus the genes it contains) but checked at any time in the genome.

→ see also: cDNA library

Genbank crops

Worldwide passed the one referred to as gene banks of the crop in 2007 approximately 1400 state-controlled public seed libraries. The world's largest Safe specifically for seed and planting of crops, the Svalbard Global Seed Vault is currently being built in Longyearbyen on Spitsbergen. Deep in the permanently frozen rock of the Arctic island, which is only about a thousand kilometers from the North Pole, will in future be stored in permafrost seed safely from around the world, protected from natural disasters, epidemics or even a nuclear war.

The deposit will be built by the Norwegian Government in cooperation with the World Trust Fund for crop diversity, a UN -affiliated foundation, which is also used by the Federal Government ( Germany ) and the Bill & Melinda Gates Foundation sponsored. The main objective of the initiative is as complete as possible preservation of the 21 most important crop species such as rice, maize, wheat, potatoes, apples, cassava, taro or coconut and their huge range of varieties. Primarily rare cultivars are stashed away that are important for farmers in developing countries is important. The safe should take several million seed samples.

The German " Genbank crops " goes on a foundation in the war back in 1943 which was then set up in Gatersleben. The main objective was the protection and conservation of the genetic diversity of agricultural and horticultural crop varieties in Germany by securing seeds and seedlings in cold stores and their maintenance is carried replica in the field and glasshouse.

In postwar Germany, a comparable state " seed library " was established at the Federal Agricultural Research Centre in Braunschweig in West Germany, which carried out a successful initiative for the collection of old regional landraces of various crop species and wild plants under Manfred Dambroth. As part of the reunification of this collection was transferred to the newly founded Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben. There, in 2007 more than 150,000 seeds and planting patterns were supported by more than 3000 crop varieties and nearly 800 species of plants in cold stores and evaluated by replica, characterized and documented.