Conjugation in Zygnemataceae:
Algae have sex too! (at least some of them, though who knows if they enjoy it?)
Amongst the Zygnemaceae, the process of conjugation consists of the joining together of the contents of two haploid cells from (usually) different filaments.
A: Conjugation in Spirogyra : these filaments were already conjugating when sampled (in early April) and show the typical results of scalariform ('ladderlike') conjugation
Two filaments lie parallel, and outgrowths from each filament
grow towards each other, then fuse to form a conjugation tube.
The dark oval shapes are diploid zygospores, formed after
nuclear fusion between the two haploid cells. They form in only one of
the two filaments.
Note that the centre filament has no zygospores: it appears to have donated all the contents of participating cells to the other filaments. See also the two cells in the upper filament which have not succeeded in conjugating: their tubes have not fused with the cell they contacted, as a cell from another filament got there first.
conjugation occurs between cells in the same filament:
This set of pictures of Mougeotia shows the early stages of the process: unfortunately they did not go on to complete the process in captivity.
Progressive development of geniculations ('knee bends') associated with lateral conjugation: this may be Mougeotia geniculata. The cell diameter is 32Ám.
These two pictures show the short rhizoid-like branches which grow out from one filament to make contact with another (not always successfully):
A general view of the filaments: