New species of dictyostelid cellular slime moulds from Australia

2008 ◽  
Vol 21 (1) ◽  
pp. 50 ◽  
Author(s):  
John C. Landolt ◽  
James C. Cavender ◽  
Steven L. Stephenson ◽  
Eduardo M. Vadell

During the 2001–2006 field seasons, samples for isolation of dictyostelid cellular slime moulds were collected at several localities in Queensland, the Northern Territory, Western Australia and Victoria. The majority of these samples were collected from the soil–litter layer on the ground, but some additional samples were obtained from the layer of organic matter (‘canopy soil’) associated with the bases of vascular epiphytes on the trunks and branches of trees in the tropical forests of northern Queensland. Many of the forms recovered from these samples could be assigned to described taxa, including such cosmopolitan species as Dictyostelium mucoroides, Polysphondylium pallidum, P. violaceum and D. giganteum. However, several others appear to represent new species, and eight of these (D. boomeransporum, D. flexuosum, D. granulosum, D. myxobasis, D. radiculatum, D. rotatum, P. australicum and P. stolonicoideum) are described herein. The large number of apparently undescribed forms suggests that the dictyostelid biota of Australia is relatively distinct when compared with that of any other continent.


1956 ◽  
Vol 33 (4) ◽  
pp. 645-657
Author(s):  
B. M. SHAFFER

1. A study has been made of acrasin, the agent inducing chemotaxis in the amoebae of cellular slime moulds. 2. A method has been developed for subjecting sensitive amoebae to a fluctuating gradient set up by an artificial source that can be renewed at intervals of as little as a few seconds with fresh test solution. 3. Amoebae orient to a gradient maintained with the cell-free liquid freshly obtained from the immediate surroundings of a natural source. 4. Acrasin solution as secreted loses its activity very rapidly at room temperature. 5. A highly active stable solid is obtained by drying methanolic culture extracts; it resists boiling and exposure to acids and alkalis. Its solubility decreases rapidly in passing up the alcohol series. 6. The original instability has been shown to be due to the presence of another extracellular slime-mould product, possibly an enzyme; it, unlike acrasin, cannot pass rapidly across a dialysis membrane, is heat labile, and can be precipitated by ammonium sulphate. 7. The advantages of the organism's itself inactivating acrasin are considered. 8. Some of the advantages of a source's releasing acrasin in pulses are discussed; but it is not essential for orientation for it to do so. 9. Sensitive amoebae not only are oriented by an acrasin solution but are caused to secrete acrasin: this is the basis of a chemotactic relay system.



1992 ◽  
Vol 96 (8) ◽  
pp. 670-672 ◽  
Author(s):  
Steven L. Stephenson ◽  
John C. Landolt


2003 ◽  
Vol 31 (3) ◽  
pp. 719-722 ◽  
Author(s):  
A.G. McDonald

Of the many examples of oscillatory kinetic behaviour known, several are briefly reviewed, including those of glycolysis, the peroxidase–oxidase reaction and oscillations in cellular calcium concentration. It is shown that simple mathematical models employing allosteric rate laws are sufficient to explain the instability of the steady state and the appearance of sustained oscillations. The cAMP-signalling systems of cellular slime moulds and the dynamics of intracellular calcium oscillations illustrate the importance of such oscillophores to inter- and intra-cellular communication and differentiation.





Nature ◽  
1966 ◽  
Vol 209 (5028) ◽  
pp. 1152-1152 ◽  
Author(s):  
HOWARD M. SNYDER ◽  
COSTANTSE CECCARINI


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