Picozoa

Picomonas judraskeda

The Picozoa are in 2013 newly described strain of heterotrophic protozoa from the domain of eukaryotes. They are the smallest forms freely in the water floating creatures are large, between half and 3.8 microns ( micrometers) and come in large numbers and density in all oceans before.

History of discovery and detection

End of the 90s should be clarified in the European project " Picodiv ", which occur in the picoplankton organisms. Two years were to sample in the Atlantic, taken in the Mediterranean, off Scotland, Alaska and Norway. Picozoa found mainly in the nutrient-poor areas of cold coastal seas, where they may constitute up to 50 percent of the biomass.

Picozoa are so small that they are barely visible in the light microscope as a living being. The detection achieved using the 18S r gene from which the 18S rRNA is read. It is a component of the ribosome and the 18S version is a clear evidence of a eukaryotic origin. Since the 18S rRNA mutated slightly over long periods of time, evolutionary family trees can be constructed with their help.

The samples found in the sea, unknown 18S rRNA sequences showed that the Picozoa must be placed in a previously unknown class. It has been suggested that it is algae- like organisms, but they are more closely related to any known eukaryote class. To the sequences of the oligonucleotides were designed and using the FISH technique, organisms can be made visible. The Picozoa contain a small round organelle with phycobiliproteins, why was originally believed that they could be photosynthetically active.

2013 was described from the group Picomonas judraskeda, the first and only kind described. The type was determined using a fluorescent mitochondrial marker from a seawater sample that was collected before the harbor of Helgoland at a depth of 5 meters, isolated as part of a doctoral thesis and then cultured in the laboratory. As in the studies no evidence for the presence of plastids, cell organelles of plants and algae, could be detected, it is assumed that the unicellular heterotrophs feed. Simultaneously with the type genus, family, order and class have been described and previously known as Picobiliphytes or Biliphyta creatures described as a new strain Picozoa.

Features

The Picozoa be as heterotrophic, marine, pikoplanktonische ( the cells fit through a 3 micron membrane filter) protists diagnosed, usually by one of the two characteristic sequences of nuclear -encoded SSU rDNA 5'GCG TGA TGC CAA AAT CCG3 ' ( PICOBI01 ) or 5' ATA TGC CCG TCA AAC CGT3 ' ( PICOBI02 ) are marked.

The determined at Picomonas judraskeda other features, including the split into two hemispheres cell, the two flagella and the jerky movement cycle will not be used for diagnosis of the new strain, as it is not sure if they can be found again in other species. However, scientists suspect that this will be the case for most of the features.

System

A phylogenetic analysis, in which a total of 104 eukaryotic taxa were examined from almost all supergroups ( were missing only the excavata ), the Picozoa could not allocate one of the known systematic supergroups of Eukaryota. Within the Picozoa can be a great genetic diversity detected and tentatively can be 12 different clades.