Cnidarians Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

such as

Hydra Hydra generally refers to: * Lernaean Hydra, a many-headed serpent in Greek mythology * ''Hydra'' (genus), a genus of simple freshwater animals belonging to the phylum Cnidaria Hydra or The Hydra may also refer to: Astronomy * Hydra (constel ...

have become attractive model organisms to study the

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity desc ...

. However, despite long-term efforts, stably

transgenic animals Genetically modified animals are animals that have been genetically modified for a variety of purposes including producing drugs, enhancing yields, increasing resistance to disease, etc. The vast majority of genetically modified animals are at the ...

could not be generated, severely limiting the functional analysis of

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

s. For analytical purposes, therefore, an important technical breakthrough in the field was the development of a transgenic procedure for generation of stably transgenic lines by embryo

microinjection Microinjection is the use of a glass micropipette to inject a liquid substance at a microscopic or borderline macroscopic level. The target is often a living cell but may also include intercellular space. Microinjection is a simple mechanical pro ...

Uses

Hydra polyps are small and transparent which makes it possible to trace single cells

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...

. In addition, transgenic Hydra provide a ready system for generating

gain-of-function Gain-of-function research (GoF research or GoFR) is medical research that genetically alters an organism in a way that may enhance the biological functions of gene products. This may include an altered pathogenesis, transmissibility, or host ran ...

phenotypes. With the use of transgenes producing dominant-negative versions of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s, one should be able to obtain loss-of-function phenotypes as well. Current technology allows generation of reporter constructs using promoters of various Hydra genes fused to

fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

proteins. Since transgenic Hydra lines have become an important tool to dissect molecular mechanisms of development, a “Hydra Transgenic Facility” has been established at the Christian-Albrechts-University of Kiel (Germany).

References

{{no footnotes, date=April 2010 * Wittlieb J, Khalturin K, Lohmann JU, Anton-Erxleben F and Bosch TCG (2006): ''Transgenic Hydra allow in vivo tracking of individual stem cells during morphogenesis.'' Proc. Natl. Acad. Sci. USA 103;16: 6208-6211 * Khalturin K, Anton-Erxleben F, Milde S, Plötz C, Wittlieb J, Hemmrich G and Bosch TCG (2007): ''Transgenic stem cells in Hydra reveal an early evolutionary origin for key elements controlling self-renewal and differentiation.'' Developmental Biology, Volume 309, Issue 1, Pages 32–44 * Siebert S, Anton-Erxleben F and Bosch TCG (2008): ''Cell type complexity in the basal metazoan Hydra is maintained by both stem cell based mechanisms and transdifferentiation.'' Dev. Biol. 313: 13-24 * Milde S, G Hemmrich, F Anton-Erxleben, K Khalturin, J Wittlieb, and TCG Bosch (2009): ''Characterization of taxonomically-restricted genes in a phylum-restricted cell type.'' Genome Biol. 10(1):R8

External links

Transgenic Hydra facility
at the University of Kiel (Germany) Genetically modified organisms Molecular biology Hydridae