scholarly journals OBSERVATIONS ON THE FOOD REACTIONS OF ACTINOPHRYS SOL

1928 ◽  
Vol 54 (6) ◽  
pp. 485-502 ◽  
Author(s):  
JAMES BURDINE LOOPER
Keyword(s):  
Actinophrys Sol

Microtubule-organizing centres and assembly of the double-spiral microtubule pattern in certain heliozoan axonemes

1981 ◽  
Vol 50 (1) ◽  
pp. 259-280
Author(s):  
J.C. Jones ◽  
J.B. Tucker
Keyword(s):  
Nuclear Envelope ◽  
Surface Membrane ◽  
Cold Treatment ◽  
Dense Material ◽  
Microtubule Assembly ◽  
Central Nucleus ◽  
Spiral Pattern ◽  
Microtubule Organizing Centres ◽  
Double Spiral ◽  
Actinophrys Sol

The double-spiral microtubule pattern is established by a self-linkage procedure when axopodial axonemes reassemble after cold treatment in multinucleate Echinosphaerium nucleofilum and mononucleate Actinophrys sol. Nuclei are related spatially to axoneme morphogenesis in both organisms but in rather different ways. Microtubules grow out in all directions from discrete clumps of dense material situated close to nuclei in E. nucleofilum as axonemal assembly begins. Each clump acts as a microtubule-organizing centre (MTOC) in so far as it is associated spatially with the assembly of microtubules for a single axoneme. The dense material spreads along the sides of a developing axoneme for several micrometers, where it probably promotes further microtubule assembly as the double-spiral pattern is established. Pattern is generated as microtubules that are randomly oriented to begin with become more closely juxtaposed and aligned with each other. There are indications that juxtaposition is brought about by the contractile action of a filamentous meshwork that interconnects the microtubules. Final positioning and alignment appears to be accomplished by a ‘zippering’ together of adjacent portions of microtubules that proceeds in both directions along the lengths of developing axonemes as self-linkage is effected. Considerable numbers of more or less radially oriented microtubules remain and project from the surface membrane of the single central nucleus during cold treatment of A. sol. Additional tubules assemble and become associated similarly with the nuclear envelope immediately after cold treatment. Initially these microtubules are not arranged in a double-spiral pattern, which is subsequently generated by procedures similar to those outlined above for E. nucleofilum. It is suggested that the surface of the nuclear envelope may act as an MTOC.

Cytokinesis in the Heliozoan Actinophrys Sol

1974 ◽  
Vol 16 (3) ◽  
pp. 499-517
Author(s):  
C. D. OCKLEFORD
Keyword(s):  
Electron Microscopy ◽  
Daughter Cell ◽  
Culture Medium ◽  
Cytochalasin B ◽  
Pole Model ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Antimitotic Drugs ◽  
Actinophrys Sol ◽  
Low Temperature Treatments

A study of cytokinesis in the heliozoan Actinophrys sol has been made using low-temperature treatments, antimitotic drugs, cytochalasin B, light microscopy and electron microscopy. It reveals that microtubular axopodia remain extended during cell division and play a major role in it. Data indicate that when organisms are attached to the bases of culture dishes the normal locomotive mechanism of the presumptive daughter cells pulls them apart. However, when Actinophrys are floating freely in their culture medium, they are still able to undertake division. In this situation interactions between axopodia from opposite daughter cell bodies appear to facilitate the movement apart of the prospective daughter cells. The present study and other published accounts indicate that a type of cytokinesis exists which is not explicable in terms of the ‘contractile ring’ or ‘fusing vesicle’ theories. To account for these observations a ‘barge pole’ model of division is suggested.

Translations: Description of Actinophrys Sol

1853 ◽  
Vol s1-1 (1) ◽  
pp. 25-34
Author(s):  
A. KÖLLIKER
Keyword(s):  
Actinophrys Sol

Responses of the Heliozoon Actinophrys Sol to Prey, to Mechanical Stimulation, and to Solutions of Proteins and Certain Other Substances

1960 ◽  
Vol 37 (2) ◽  
pp. 407-416
Author(s):  
J. A. KITCHING
Keyword(s):  
Body Surface ◽  
Tap Water ◽  
The Body ◽  
Albumin Solution ◽  
Egg Albumin ◽  
Other Substances ◽  
Γ Globulins ◽  
Skin Formation ◽  
Actinophrys Sol

1. Various flagellates and small ciliates stick to the axopods of Actinophrys. Contact with the base of an axopod or with the body surface leads to the outgrowth of a food funnel, by which the prey is ultimately surrounded. 2. If a fine probe or micropipette touches the body surface or the base of an axopod, a small cup may grow out over it, investing it closely, but the instrument is soon released. A squirt of tap water from a micropipette may also provoke the outgrowth of a small lobe or cup, or local pinocytosis. 3. Contact with, or a squirt from, a micropipette containing a solution of egg albumin provokes a more extensive reaction. The micropipette usually becomes invested extensively. The micropipette is drawn into the body and held there for up to an hour. 4 Immersion in egg albumin solution leads to a temporary spreading and lobulation of the axopod bases, and later a ‘skin’ may separate from the body surface. Skin formation is more pronounced in serum albumin solution, and may also be induced by γ-globulins and gelatin. 5. On treatment in vivo with toluidine blue or thionine a violet layer in the body surface separates as a pinkish violet or violet skin, leaving the body surface unstained. 6. There is evidence that the skin-forming substance is associated directly or indirectly with the maintenance of cell shape.

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