Slime mold Dictyostelium discoideum

These studies demonstrate the general mechanism of synchronization of biochemical systems, which I expect to be operative in even more complex systems, such as the mitochondrial respiration or the periodic activity of the slime mold Dictyostelium discoideum. As shown in a number of laboratories under suitable conditions mitochondrial respiration can break into self-sustained oscillations of ATP and ADP, NADH, cytochromes, and oxygen uptake as well as various ion transport and proton transport functions. It is important to note that mitochondrial respiration and oxidative phosphorylation under conditions of oscillations is open for the source, namely, oxygen, as well as with respect to a number of sink reactions producing water, carbon dioxide, and heat. 

As described in Box 11-C, the ameboid cells of the slime mold Dictyostelium discoideum are attracted to nutrients such as folic acid during their growth stage. Later, as the cells undergo developmental changes they become attracted by pulses of cyclic AMP.330 Occupancy of 7-helix receptors for cAMP on the outer plasma membrane appears to induce methylation of both proteins and phospholipids and a rise in cytosolic Ca2+ and changes in the cytoskeleton that result in preferential extension of the actin-rich pseudopods toward the chemoattractant.331... 

Isolation of a 2-acetamido-2-deoxy-D-galactose-binding protein from a slime mold, Dictyostelium discoideum, was reported by Rosen and coworkers.779,780 Affinity chromatography on Sepharose 4B, followed by... 

The most important compounds from this class are undoubtedly 3,6-anhydrofuranoses. Fura-nodictine A and B (produced by cellular slime mold Dictyostelium discoideum) showing neuronal differentiation activity [54] are good examples. These interesting derivatives may be conveniently obtained from the open-chain sugars. For example, synthesis of furanodictine A was realized from compound 85 obtained from D-arabinose in a few well-defined steps as shown inO Fig. 19 [55]. 

Enzymatic deamination of the naturally occurring pteridin-6-yl acyclo C-nucleosides biopterin (615), dictypterin (616), o-neopterin (618), and d-monapterin (620) with pterin deaminase from the slime mold Dictyostelium discoideum caused their conversion to the corresponding lumazin-6-yl 2,4-dioxopyrazino[2,3-d]pyrimidin-6-yl acyclo C-nucleosides biolumazine (672), dictyolumazine (673), D-neolumazine (674), and D-monalumazine (675), respectively (94MI2) (Scheme 174). 

Orellanine (0.4 mM) inhibited photosynthesis in Lemna minor,without affecting the chloroplast electron transport chain [107], It inhibited growth of Escherichia coli and the slime mold Dictyostelium discoideum [108]. Orellanine (and orelline 17) suppressed the toxicity of aluminum ions on the fungus Mycena seplenlrionalis, via formation of a 16(or 17J-A1+3 complex [109]. The phototransformation of 16 to 17 has been described [110]. 

Bonner, J.T. 1947. Evidence for the formation of cell aggregates by chemotaxis in the development of the slime mold Dictyostelium discoideum. J. Exp. Zool. 106 1-26. 

Goldbeter, A. J.L. Martiel. 1985. Birh5dhmicity in a model for the cyclic AMP signaling system of the slime mold Dictyostelium discoideum. FEBS Lett. 191 149-53. 

CjHiiNsOj, Mr 237.22. The (l J ,2 S) form (L-erythro form) form ale yellow cryst., mp. 250-280 C (decomp.), [a]o-66 (0.1 m HCI), pK, 2.23, pK 2 7.89. In alkaline solution B. shows blue fluorescence. It is widely distributed in microorganisms, insects (e.g. in royaI jelly of queen bees), algae, amphibians, and mammals and is also found in urine. In metabolism tet-rahydro-B. acts as a cofactor for phenylalanine 4-monooxygenase (EC 1.14.16.1). B. is a growth factor for insects. The (l /, 2 /f) form (D-threo form) known as dictyopterin melts at >300 C and has pK , 2.20, pKa2 7.92. It occurs in the slime mold Dictyostelium discoideum. The biosynthesis starts from guanosine triphosphate. 

Rogers MJ, Ji XH, Russell RGG, Blackburn GM, Williamson MP, Bayless AV, Ebetino FH, Watts DJ (1994) Incorporation of bisphosphonates into adenine-nucleotides by amebas of the cellular slime-mold dictyostelium-discoideum. Biochem J 303 303-311... 

Taya et al. (1978) have reported that a cell-free system from the slime mold Dictyostelium discoideum catalyzes the condensation of DMAPP with AMP to produce isopentenyl adenine, a cytokinin. (An organic chemist would probably call this dimethylallyl adenine, but both terms are correct, and isopentenyl adenine is firmly established in the plant physiology literature.) They have emphasized that this is a direct synthesis, not involving nucleic acid breakdown, and suggest that the same system may operate in higher plants. 

Fungi Slime molds Dictyostelium discoideum Extracellular signal transmitter. Cell aggregation in response to chemotac-tic stimuli. 

One example of pattern formation in complex systems occurs in the life cycle of the cellular slime mold Dictyostelium discoideum. Figure 20.2 describes the life cycle of this species. Beginning as isolated amebas at the unicellular stage (a), they move in the surrounding medium, feed on such nutrients such as bacteria and proliferate by cell division. Globally speaking, they constitute a uniform system, inasmuch as their density (number of cells per square centimeter) is essentially constant. Suppose now that the amebas are starved in the laboratory this is induced deliberately, in Nature it may happen because of... 

Figure 20.2 Life cycle of the cellular slime mold Dictyostelium discoideum (Courtesy A. Goldbeter)...

Over the past 40 years, numerous modeling studies have focused on the cellular slime mold Dictyostelium discoideum. This is because D. discoideum provides an experimentally accessible and relatively simple system for studying key developmental processes like chemotaxis, cell sorting, and complex pattern formation. Early studies adopted continuous models [77-80]. More recent studies used elegant hybrid approaches that combined CA models and partial differential equations to model 2D and 3D problems involving aggregation and self-organization ofD. discoideum [81-84]. 

All these polyenoic fatly acids were of the all-cis configuration, although monoenoic fatty acids of the trans configuration have been detected in algae (Klenk et al., 1963). It will be noted that, with the exception of some fatty acids of the cellular slime mold Dictyostelium discoideum, these polyenoic fatty acids all have double bonds in the methylene-interrupted sequence. 

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