Myxogastria - Characteristics and Life Cycle - Plasmodium

Plasmodium

The second trophic phase begins with the development of the plasmodium. The multinucleated organism now absorbs via phagocytosis as many nutrients as possible. These are bacteria, protists, dissolved substances, moulds, higher fungi and small particles of organic material. This enables the cell to undergo enormous growth. The nucleus divides multiple times, and the cell soon becomes visible to the naked eye and usually has a surface area – depending on the species – up to one square metre; however, in 1987 one artificially cultivated cell of Physarum polycephalum attained a surface area of 5.5 sq m. Myxogastria species have numerous nuclei in their trophic plasmodium phase; the small, non-veined proto-plasmodia have between 8 and 100 nuclei, while large, veined meshworks have between 100 and 10 million nuclei. All of these remain part of a single cell, which has a viscous, slimy consistency and may be transparent, white or brightly coloured in orange, yellow or pink.

The cell has chemotactic and negative phototactic capabilities in this phase, meaning that it is able to move towards nutrients and away from dangerous substances and light. The movements originate in the grainy cytoplasm, which streams by pulsation in one direction within the cell. In this way the cell reaches a speed of up to 1000 µm per second – the speed in plant cells is 2 to 78 µm per second. A resting state, the so-called sclerotium, may occur in this phase. The sclerotium is a hardened, resistant form composed of numerous "macrocysts", which enable the myxogastria to survive in adverse conditions, for example during winter or dry periods, in this phase.

  • Fruit bodies of the myxogastria
  • Sporangia (pediculated) of Trichia decipiens

  • Plasmodiocarp of Hemitrichia serpula

  • Aethalium of Enteridium lycoperdon

  • Pseudo-aethalium of Lindbladia tubulina

Read more about this topic:  Myxogastria, Characteristics and Life Cycle