Primitive organisms

Some of the earlier cytologists maintained that bacteria were very primitive organisms devoid of nuclei and consisting simply of cytoplasm, granules, and vacuoles. This view was based on their failure to observe a nucleus in a bacterial cell. Others held the view that the nuclear material was present in a diffuse form throughout the cytoplasm. Still others believed that the whole cell should be regarded... 

Fig. 5.3. The proposed free metallome profiles of a primitive organism after the synthesis of ring chelates (8), free metallome , combined or total metallome. Arrows (up) indicate the elevation due to the chelates and arrows (down) indicate pumping out.

RNAi probably evolved initially in primitive organisms in order to protect their genomes from viruses, transposons and additional insertable genetic elements, and to regulate gene expression. The RNAi pathway was first discovered in plants, but it is now known to function in most, if not all, eukaryotes. 

We also know that a considerable enrichment of prebiotic moieties may have come from submarine vents and other hydrothermal sources (see, for example, Miller and Bada, 1988 Holm and Andersson, 1998 Stetter, 1998). Let s start with the 1979 discovery of deep-sea vents with black smokers, which are associated with an extraordinary abundance of the most phylogenetically primitive organisms on Earth. This ecosystem is sulphur based, and is distinct from the more familiar, photosynthetically-based ecosystem that dominates Earth s surface. Corliss et al. (1981) were struck by the richness of the vent biota, based on chemosynthesis, and proposed that these were the origin of life. 

Fig. 2. An evolution diagram illustrating a suggestion of common ancestry of some present-day organisms. The essential features of present-day photosynthesis may have originated in the prebiotic era and is preserved in its most primitive form in (at least some) present-day phototrophs. The heterotrophs may have developed parallel with the aerobic nonphotosynthetic bacteria, some l to 1.5 x 109 years after the emergence of the cyanobacteria. The eukaryotic photosynthetic organisms developed much later, perhaps some 1.5 to 0.5 x 109 years ago. The archaebacteria are primitive organisms that seem to have no evolutionary relation with the present prokaryotes.21 Little is known about their energy metabolism. Tentatively, they are considered as a very early form of cellular life.

Several hypotheses of the possible relationship between the deposition of the cherty iron formation and the activity of various primitive organisms have been defined and repeatedly proofs have been offered to support the occurrence of definite biota. In fact, some indication is available for the assumption, that life was abundant at the time and place of deposition of the BIF and that iron formations themselves were deposited as a result of biological processes. It is presumed in this context, that iron-bacteria reacted with the oxygen acceptor Fe2 + in solution and then deposited the trivalent and/or trivalentdivalent iron as precipitated compounds along with other residues resulting from biomass. All these components... 

We humans tend to have a rather exalted opinion of ourselves, and that attitude can color our perception of the biological world. In particular, our attitude about what is higher and lower in biology, what is an advanced organism and what is a primitive organism, naturally... 

ABSTRACT The Myxomycetes (true slime molds) are an unusual group of primitive organisms that may be assigned to one of the lowest classes of eukaryotes. As their fruit bodies are very small and it is very difficult to collect much quantity of slime molds, few studies have been made on the chemistry of myxomycetes. Cultivation of the plasmodium of myxomycetes in a practical scale for natural products chemistry studies is known only for very limited species such as Physarum polyeephalum. We recently studied the laboratory-cultivation of myxomycetes and several species have been successfully cultured in agar plates. Chemical constituents of cultured plasmodia of several species of myxomycetes of the genera Didymium and Physarum were examined to obtain several sterols, new lipid, or pyrroloiminoquinone derivatives. Previous studies on the chemistry of the secondary metabolites of myxomycetes by other groups are also described here. 

The Myxomycetes (true slime molds) are an unusual group of primitive organisms that may be assigned to one of the lowest classes of eukaryote [2]. In the assimilative phase of their life cycle (Figure 1)... 

This link between the sense of smell and reproductive activity not only goes back to the most primitive organisms but is also deeply embedded in the unconscious mind of all higher animals including humans. Research into human biology has shown that if the neural link between the nasal receptor cells and the pituitary is broken, sexual interest and function may be greatly impaired. 

However, despite the outstanding achievements of evolutionary biochemistry, many problems still await solution. Among these unsolved and relatively little-investigated problems of evolutionary biochemistry, there are the role of phosphorus compounds in chemical evolution, which preceded the appearance of life on Earth, and the evolution of phosphorus metabolism from primitive organisms to contemporary living creatures. 

Werner, H. (1978a). The syncretic character of primitive organization. In S. S. Barten and M. B. Franklin (eds.), Developmental processes Heinz Werner s selected writings, vol. 1 General theory and perceptual experience (pp. 41-64). New York International Universities Press. 

Fivefold symmetry appears frequently among primitive organisms. Examples are shown in Figure 2-19. They have fivefold rotation axes and intersecting (vertical) symmetry planes as well. The symmetry class of the starfish is 5 m. This starfish consists of ten congruent parts, with each pair related by a symmetry plane. The whole starfish is unchanged either by 360°/5 = 12° rotation around the rotation axis, or by mirror reflection through the symmetry planes which intersect at... 

Many primitive organisms have the shape of the pentagonal dodecahedron. As will be seen later, pentagonal symmetry used to be considered forbidden in the world of crystal structures. Belov [82] suggested that the pentagonal symmetry of primitive organisms represents their... 

Subsequent to the original quest for vitamin B12 (1), driven by medicinal purposes mainly, further investigations on the natural corrinoids laid bare the central roles of the Bi2-coenzymes in the metabolism of microorganisms, in particular. These primitive organisms uniquely possess the capacity to build up the complex B12 structure in nature, in which they may vary the constitution of the nucleohde ftmchon in a species-specihc way (Figure 2). The cobalt-corrins, in turn, have been proposed to be structural and functional renmants of early (primihve) forms of life, where presumably, central metabolic processes could rely considerably on organometalhc chemistry at cobalt and nickel centers. ... 

In the thermodynamic analysis it has already been mentioned that oxidation of the sulfide ion is possible at lower partial pressure of oxygen than in the case of oxidation of ferrous iron, and both these reactions are irreversible in the presence of even mere traces of free O2. Therefore the suggestion of Cloud and Licari (1968) and Cloud (1969), that primitive organisms could have used electron donor reactions of the type ... 

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