Gene library

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A gene library , including genomic library , DNA library or gene bank , houses the entire genome of an organism in the form of defined DNA fragments on vectors in single-cell carrier organisms or phages . These carrier organisms are used to store and replicate the fragments for the purpose of molecular biological studies.

Creation of a gene library

When creating a gene library, fragments of the complete genome of a specific organism are usually first produced by enzymatic digestion of genomic DNA with restriction enzymes . Each fragment contains one or more genes and is introduced separately into a unicellular organism ( E. coli , S. cerevisiae or others) or phages via a so-called vector . This process is also known as transformation or transduction . Along with its own reproduction by cell division, the unicellular organism multiplies the inserted DNA fragment and forms a colony on the appropriate nutrient medium . A corresponding number of colonies are generated and cultivated in the laboratory which are required to accommodate the entire genome of an organism, fragmented into individual colonies.

The size of the fragments depends significantly from those used for cloning vectors from. The capacity (maximum detectable fragment size) of the vectors relative to the total size of the genome is usually very small. Today, YACs and BACs are used because these vector types allow a rather large fragment size of up to about 150 kbp and 300 kbp, respectively. This allows the human genome of roughly 3,200,000 kbp to be accommodated in a little more than 10,000 or 20,000 fragments. This is a huge improvement over previous methods which still had to split the human genome into 35 kbp or even 17 kbp fragments. The DNA fragments can also be introduced into phages , but their uptake capacity is much lower (max. 25 kbp) than that of the aforementioned vectors.

Once the gene library has been created, a required DNA fragment can be duplicated by bringing the cells of the corresponding colony to a suitable culture medium to multiply. The DNA fragment can be re-isolated from the carrier organism using special molecular biological techniques. The organism used for storage and replication is lysed, the released DNA is chemically purified and the introduced vector with the DNA fragment is isolated from the host DNA ( plasmid preparation ). In the laboratory, the colonies are usually marked so that it is known which position in the genome the hosted fragment corresponds to. However , the position of the DNA fragment (and thus of the genes it contains) in the genome can be checked at any time by hybridization or by sequencing and comparing the DNA sequence obtained using a DNA sequence database (e.g. GenBank ).

Genebank crops

In 2007 there were around 1400 state-controlled public seed libraries worldwide, which are known as “genebanks for cultivated plants”. The world's largest safe especially for seeds and seedlings 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 , seeds from all over the world are to be safely stored in permafrost , protected from natural disasters, epidemics or even a nuclear war.

The deposit is being built by the Norwegian government in cooperation with the World Trust Fund for Cultivated Plants Diversity , a UN-affiliated foundation that is also sponsored by the German government and the Bill & Melinda Gates Foundation . The main aim of the initiative is to preserve the 21 most important crops such as rice, maize, wheat, potatoes, apples, cassava, taro and coconut and their huge variety of varieties as completely as possible. Rare cultivars that are important for farmers in developing countries are primarily bunkered. The safe should hold several million seed samples.

The German "Genebank Cultivated Plants" goes back to a foundation in the war year 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 greenhouse.

In post-war Germany, a comparable state "seed library" was set up in West Germany at the Federal Research Center for Agriculture in Braunschweig , which initially carried out a successful initiative under Dieter Bommer , then under Manfred Dambroth to collect old regional varieties of various types of useful plants and wild plants. As part of the reunification, this collection was handed over to the newly founded Leibniz Institute for Plant Genetics and Crop Plant Research in Gatersleben . In 2007, more than 150,000 samples of seeds and plants from over 3,000 species of crops and almost 800 types of plants were stored in cold stores and evaluated, characterized and documented by replicating them.

See also

Web links

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  • M. Leipold, S. Tausch, C. Reisch, P. Poschlod: Genebank for wild plant seeds - Bavaria ark for the preservation of floristic biodiversity. UmweltSpezial, 2019, Bavarian State Office for the Environment, Augsburg, 66 p. (PDF 9.5 MB)
  • Manfred G. Raupp: Requirements for an agricultural database. Situation analysis for the "Ispflanz" working group at the University of Munich Weihenstephan. Stutensee / Staffort 1976.
  • Manfred G. Raupp: Thoughts on the situation in German agriculture, its further development and the consequences for activities in the field of seeds, genetic engineering and industrial raw materials. Ciba-Geigy, Frankfurt 1985.
  • S. Tausch, M. Leipold, C. Reisch, P. Poschlod: Genebank Bayern Arche - a contribution to the permanent protection of endangered plant species in Bavaria. In: Nature concerns. Volume 37, No. 1, 2015, pp. 82-91. (PDF 0.7 MB)
  • Nicole C. Karafyllis (Ed.): Theories of the living collection. Plants, microbes and animals as biofacts in gene banks. Alber, Freiburg 2018 ( Life Sciences in Dialogue Vol. 25) ISBN 978-3-495-48975-8

Individual evidence

  1. ↑ Nicole C. Karafyllis, Uwe Lammers: Big data in small doses. The history of the West German gene bank for cultivated plants 'Braunschweig Genetic Resources Collection' (1970-2006) and its biofacts. In: History of Technology. Volume 84, No. 2, 2017, pp. 163-200, doi: 10.5771 / 0040-117X-2017-2 .