''Phycomyces blakesleeanus'' is a filamentous

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

in the Order

Mucorales The Mucorales is the largest and best studied order of zygomycete fungi. Members of this order are sometimes called pin molds. The term mucormycosis is now preferred for infections caused by molds belonging to the order Mucorales. Systematics ...

of the phylum

Zygomycota Zygomycota, or zygote fungi, is a former division or phylum of the kingdom Fungi. The members are now part of two phyla: the Mucoromycota and Zoopagomycota. Approximately 1060 species are known. They are mostly terrestrial in habitat, living i ...

or subphylum Mucoromycotina. The spore-bearing sporangiophores of ''Phycomyces'' are very sensitive to different environmental signals including light, gravity, wind, chemicals and adjacent objects. They exhibit phototropic growth: most ''Phycomyces'' research has focused on sporangiophore

photobiology Photobiology is the scientific study of the beneficial and harmful interactions of light (technically, non-ionizing radiation) in living organisms. The field includes the study of photophysics, photochemistry, photosynthesis, photomorphogenesis, vis ...

, such as

phototropism Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hor ...

and photomecism ('light growth response'). Metabolic, developmental, and photoresponse mutants have been isolated, some of which have been genetically mapped. At least ten different genes (named ''madA'' through to ''madJ'') are required for phototropism. The ''madA'' gene encodes a protein related to the White Collar 1 class of photoreceptors that are present in other fungi, while ''madB'' encodes a protein related to the White Collar 2 protein that physically bind to White collar 1 to participate in the responses to light. ''Phycomyces'' also exhibits an avoidance response, in which the growing sporangiophore avoids solid objects in its path, bending away from them without touching them, and then continuing to grow upward again. This is believed to result from an unidentified "avoidance gas" that is emitted by the growing zone of the sporangiophore. This gas would concentrate in the airspace between the ''Phycomyces'' and the object. This higher concentration would be detected by the side of the sporangiophore's growing zone, which would grow faster, causing the sporangiophore to bend away. ''Phycomyces blakesleeanus'' became the primary organism of research of the Nobel laureate

Max Delbrück Max Ludwig Henning Delbrück (; September 4, 1906 – March 9, 1981) was a German–American biophysicist who participated in launching the molecular biology research program in the late 1930s. He stimulated physical science, physical scientist ...

starting in the 1950s, when Delbrück decided to switch from research on bacteriophage and bacteria to ''P. blakesleeanus''. A genetic linkage map was developed for ''P.blakesleeanus''. This genetic map was constructed from 121 progeny of a cross between two wild type isolates and involved 134 markers. The markers were mostly PCR-based restriction fragment length polymorphisms. Zygospores are the sexual structures of ''P. blakesleeanus'' in which the diploid zygote is formed and meiosis is presumed to take place. The data from this cross provided supporting evidence for meiosis during zygospore development. Image:Phycomyces_blakesleeanus1.jpg, ''Phycomyces blakesleeanus'' asexual sporangium Image:Phycomyces_blakesleeanus3.jpg, ''Phycomyces blakesleeanus'' gametangia

References

External links

Phycomyces at Zygomycetes.org
* * ttp://www.fgsc.net/scripts/catalogDetails.asp?CatNum=157 Phycomyces strainsat the FGSC {{Taxonbar, from=Q15632547 Zygomycota Fungi described in 1925