Variability of Behaviour of Aggregating Cellular Slime Moulds

1957 ◽  
Vol s3-98 (44) ◽  
pp. 393-406
Author(s):  
B. M. SHAFFER
Keyword(s):  
Life Cycle ◽  
Environmental Conditions ◽  
The Third ◽  
Slime Moulds ◽  
Large Numbers ◽  
Wide Range ◽  
Cellular Slime ◽  
High Degree ◽  
Cellular Slime Moulds ◽  
Geometrical Relationships

1. A description is given of the development of certain structures--centre, stream, and ring--formed by the amoebae of four species of Dictyostelium and Polysphondyliumduring aggregation, and of the outcome of experimentally cutting a stream, recombining lengths of stream in simple geometrical relationships, and excising a centre. 2. In all cases there is a high degree of intraspecific variation in behaviour, and it is not possible to predict, except in terms of rough probability, what the future course of development will be. 3. An amoeba at this stage of the life cycle can exist in one of four main states. In the first, it is unaggregated and cannot react chemotactically; in the second, it is unaggregated but can react; in the third, it is in a stream moving towards a centre or has properties similar to those of a stream cell; and in the fourth, it is in a centre and nearly stationary. Though an enormous variety of patterns may be produced by large numbers of interacting amoebae, their behavioural repertory may be considered, without too much simplification, to be restricted to approaching these four states in various sequences and at various rates. 4. Most of these sequences can be observed over a wide range of environmental conditions. Changes in humidity produce the greatest effect: the drier the culture, the stronger the drift from the first state to the fourth. 5. It is suggested that variability is occasioned by the simplicity of the mechanisms controlling development.

scholarly journals Cell Mixtures of Different Species and Strains of Cellular Slime Moulds

Development ◽  
1958 ◽  
Vol 6 (2) ◽  
pp. 346-356
Author(s):  
John Tyler Bonner ◽  
Marcia Shaw Adams
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Fruiting Body ◽  
Slime Moulds ◽  
Cellular Slime ◽  
Common Observation ◽  
Cellular Slime Moulds

The cellular slime moulds have, in their life history, a period of feeding of separate independent amoebae which subsequently stream together (by a process involving chemotaxis) to central collection points. Each of the resulting cell-masses differentiates into a fruiting body; in most species there is a delicate tapering celluose stalk which surrounds the large vacuolate stalk-cells, and an apical sorus containing a considerable quantity of individually encapsulated spore-cells. There are a number of distinct and easily recognizable species and, moreover, it is a common observation (see Raper, 1951) that different isolates from the soil of any one species may have small but identifiable characteristics. It was found, for instance, in a previous study (Bonner & Shaw, 1957) that some strains under given environmental conditions formed a very long stalk, that is, delayed the process of spore differentiation, while others show rapid spore differentiation and correspondingly short stalks.

Acrasin, the Chemotactic Agent in Cellular Slime Moulds

1956 ◽  
Vol 33 (4) ◽  
pp. 645-657
Author(s):  
B. M. SHAFFER
Keyword(s):  
Room Temperature ◽  
Dialysis Membrane ◽  
Relay System ◽  
Highly Active ◽  
Slime Moulds ◽  
Cellular Slime ◽  
Set Up ◽  
Cellular Slime Moulds ◽  
Extracellular Slime ◽  
Do So

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.

Vertebrates as vectors of cellular slime moulds in temperate forests

1992 ◽  
Vol 96 (8) ◽  
pp. 670-672 ◽  
Author(s):  
Steven L. Stephenson ◽  
John C. Landolt
Keyword(s):  
Temperate Forests ◽  
Slime Moulds ◽  
Cellular Slime ◽  
Cellular Slime Moulds

Implications of enzyme kinetics

2003 ◽  
Vol 31 (3) ◽  
pp. 719-722 ◽  
Author(s):  
A.G. McDonald
Keyword(s):  
Calcium Concentration ◽  
Calcium Oscillations ◽  
Rate Laws ◽  
Sustained Oscillations ◽  
Slime Moulds ◽  
Cellular Slime ◽  
The Many ◽  
Oxidase Reaction ◽  
Signalling Systems ◽  
Cellular Slime Moulds

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.

Interspecific Spore Inhibition in the Cellular Slime Moulds

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

Studies on Eimeria praecox Johnson, 1930, in the chicken

Parasitology ◽  
1967 ◽  
Vol 57 (2) ◽  
pp. 351-361 ◽  
Author(s):  
P. L. Long
Keyword(s):  
Small Intestine ◽  
Life Cycle ◽  
Small Dose ◽  
Technical Assistance ◽  
Host Immunity ◽  
Single Exposure ◽  
Three Generations ◽  
Large Numbers ◽  
High Degree ◽  
First Time

E. praeox has been isolated in Britain for the first time and is similar in regard to its oocyst size, prepatent time, life-cycle and the development of host immunity to the reports of Tyzzer et al. (1932). Oocysts had mean dimensions of 20·4 × 17·45 μm and the first oocysts were discharged 83½ h after infection.Oocyst production and life-cycle studies suggest that at least three generations of schizogony precede gametogony and that at least one further generation of schizogony is needed to explain the oocyst reproduction resulting from a small dose of oocysts. Young chickens 1½–3 weeks of age were not such suitable hosts as older chickens (6 weeks) and the reproduction of the parasite was seriously reduced when large numbers (e.g. 105, 106) were used to infect chickens. A high degree of resistance to reinfection occurred after a single exposure to infection.Sporozoite infections of the caeca or cloaca resulted in the infection of the usual small intestine site; there was no development at the site of inoculation and attempts to infect the embryo allantois did not succeed.I wish to thank Dr M. Elaine Rose for the surgery required for the caecal infections, for her interest throughout and for help with the manuscript; Dr R. F. Gordon for help with the manuscript and permission to publish and Mr B. J. Millard for skilled technical assistance.

Sign in / Sign up

Export Citation Format

Share Document