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Ea: Eucytobionta (1/3)



The typical cell structure of Eucytobionta, the clade comprising all the complex, multicellular life of planet Ea, the local equivalent of Earth's Eukarya. Also see Ean biochemistry.

« Complexity and organization are nested endlessly in lower and lower scales, far beyond our reach... Every smear of blood proclaims the power of its Maker; every drop of sewage sings the glory of the One. » – Yakub of Lilongwe, Mere Humanity

Shared features of Eucytobiontan cells include:
● A haploid protonucleus (i.e., carrying a single copy of each gene), sequestered at the center of the cell, where genetic information is stored over the long term in the form of enol-PNA; in sexual unicellular organisms, such as many Pogonocyta, additional protonuclei may be exchanged between cells.
● One or more massively polyploid paranuclei (carrying from 50 to over 200 copies of each gene), where gene expression and protein synthesis occurs, through remarkably Earth-like mechanisms. The more flexible and reactive keto-PNA is found here, and the massive redundancy dampens the effects of harmful mutations. New paranuclei are generated from the protonucleus before cell division. Monokaryotes have lost all their paranuclei, whereas the largest Pogonocytes may have hundreds.
● The astrosome, also called stellate body or Jariwala's organ, a multi-lobed vacuole located at the center of the cell. The water-filled lobular projections stabilize the cell structure, keep organelles in their place, and trace paths for the movement of vesicles. The astrosomal membrane is also the main metabolic organ, as it uses sunlight or chemical energy to create a proton gradient between the cytoplasm and the vacuole's interior from which useful energy can be harvested, much like the mitochondrial membrane in Earth's eukaryotes.
● The red body or erythrosome, a flattened organelle analogous to our Golgi apparatus, involved in the processing and secretion of proteins and TPP. The red color is probably due to iron complexes that assist with the reduction of TPP chains. In many unicellular organisms it can be visible as a dark-colored ribbon.
● The corpuscula, a number of dark-coloured vesicles filled with alkaline granules whose function is not yet clear. They are probably involved in the cell's metabolism and defense as reservoirs of enzymes in a crystalline form. Most Ean prokaryotes have corpuscula as well: some, such as Prasinobacteriales, use them for photosynthesis, whereas in Acanthobacillus they contain exotoxins used against predation.
● An elastic cell net formed by bundles of elastic, highly hydrophobic polypeptides passing between the two layers of the cell membrane. This sheath, similar to that found in the prokaryotic Commicutes, protects the cell from osmotic shock opposing both excessive intake and loss of water. In Ostracophyta and other unicellular Eucytobionts, the net is impregnated with minerals or crystalline polymers to form a protective shell.
Undulipodia (distinguished, as on Earth, in cilia and flagella according to their size and abundance) seem to be extensions of the cell net, held into place by a trans-membrane protein ring. The whole structure is formed by parallel elastic fibers, and bends in one direction as the respective fiber contracts. The contraction is likely controlled by a chemical signal conveyed by vesicles to the contracting fiber's root in the basal ring.

Summa Planetaria, "Eucytobionta#Synapomorphies", revision 315/T51Cyy4nS4
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EVLWNS's avatar
Very very cool. You rarely ever find alternate/specular cellular biologies.