Stofftransport in Rotalgen

Summary

Leucine-(U)-C¹⁴ applied to the midrib of a young phylloid of Delesseria sanguinea moves basipetally and acropetally and eventually appears in other phylloids of the same plant. The highest velocity of transport calculated was 63 cm/h. The pathway of movement seems to be the veins of the phylloids and the central core of the cauloid. Similar results had been obtained with Cystoclonium purpureum. Both algae belong to the Florideae with axial cells. Observations with the light microscope of veins of Delesseria revealed that the proposed conducting elements (up to 540 μm long) are interconnected by synapses having 1 to 4 “pit fields”, which occur as very thin parts of the wall. Single pit fields of the same structure occur in lateral walls, connecting two rows of conducting cells. The pit fields are mostly occluded by slime-like material staining yellow with iodine which is attached to one side of the synapsis. Conducting cells contain several nuclei and a small amount of threadlike, branched rhodoplasts; they are surrounded by starch cells. In cauloids which have overwintered, the starch cells are depleted of starch.