Protista

In spite of the profound diversity in siderochrome structure observed throughout the kingdom Protista, some connecting links are clearly discernible. In addition to the already noted frequent use of the small... 

Robert Richards If you look at the Generelle Morphologie der Organis-men, which is the 1866 book, as he says the roots for Protista, for plants, and for animals have different foundations. 

Most of the naturally occurring chelating agents are substituted hydroxamates which are produced by a variety of protista so that iron(III) subsequently becomes available for biochemical processes. Neilands (73) has suggested that the hydroxamates facilitate the transport of iron across cell membranes. The distribution of hydroxamates in the biosphere appears limited. However, if there was a wider distribution of hydroxamates in the environment then the management of actinide wastes could become a problem of horrifying dimensions if these chelators facilitated the transport of actinides across cell membranes. 

In addition to the hydroxamates there are other low molecular weight species produced by protista which chelate iron. In general, these chelators contain the 2,3-dihydroxybenzoyl moiety, such as 2,3-dihydroxy-N-benzoyl-Z,-serine, 2,3-dihydroxy-N-benzoylthreonine, 2,3-dihydroxy-N-benzoyl-glycine, and enterochelin (84). 

An interesting and important example of an animal poison is paralytic shellfish poison (PSP). This chemical, which is also known as saxitoxin and by several other names as well, is found in certain shellfish. But it is not produced by shellfish it is rather a metabolic product of certain marine microorganisms (Protista). These microorganisms are ingested by the shellfish as food, and their poison can remain behind in the shellfish s tissue. Paralytic shellfish poison is not a protein, but a highly complex organic chemical of most unusual molecular structure. 

Bernard C, Simpson AGB, Patterson DJ (2000) Some free-living flagellates (protista) from anoxic habitats. Ophelia 52 113-142... 

Walker G, Simpson AGB, Edgcomb V, Sogin ML, Patterson DJ (2001) Ultrastructural identities of Mastigamoeba punctachora, Mastigamoeba simplex and Mastigella com-mutans and assessment of hypotheses of relatedness of the pelobionts (Protista). Eur J Protistol 37 25-49... 

KINGDOM PROTISTA (incl. Thallophyta, Protozoa, Cellulares, Sporophyta)... 

For convenience all of the phyla of the Monera, Protista, and Phyta are included ... 

PROTIST A unicellular nucleate organism a primitive type or relatively primitive type, of organism always having nucleate cells it may be distinctly animal-like, distinctly plant-like, or they may have characteristics ordinarily associated with both plants and animals any member of the kingdom Protista. 

Psilocybin is a naturally occurring hallucinogen. It exerts neurotoxic effects similar to LSD and has a chemical structure similar to the neurotransmitter serotonin in the human brain. Psilocybin is found as an indole alkaloid (nitrogen-containing organic base) in the fungal (Protista) kingdom. Often it is accompanied by the related alkaloids, psilocin, baeocystin, and norbaeocystin. 

There were 37 distinct enzymes that contain molybdenum or tungsten known by the end of 1997. The enzymes are diverse in function, broadly distributed, and include oxidases, reductases, dehydrogenases, a transhydroxylase, and a hydratase. The Mo enzymes are found in eubacteria, archae, protista, fungi, plants, and animals (including humans) and are essential for respiration and carbon and nitrogen assimilation. Several of the enzymatic substrates and products are key components in the nitrogen, sulfur, selenium, carbon, and arsenic cycles and have major biological and environmental impact. 

Figure 1.1 Evolutionary scheme proposed by C. R. Woese and G. E. Fox. Protista are defined as any eukaryotic organism not included in Animalia, Fungi, or Plantae.

Protista One to multicelled, eukaryotic Algae, Amoeba, Paramecium... 

In 1866, Ernst Haeckel proposed a phylogenetic tree where the first forms of life were cells without a nucleus (which he called Monera), which later generated nucleated cells (Protista), which in turn gave rise to all multicellular organisms. Already in 1883, Schimper proposed that chloroplasts had once been free-living bacteria that happened to be incorporated, by a kind of symbiosis, into some eukaryotes, and from 1905 to 1930 this hypothesis was not only reproposed but also extended to mitochondria by Mereschowsky, by Portier and by Wallin. 

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