Nitrogen fixation in Prochloron (Prochlorophyta) ascidian associations - is Prochloron responsible Issue 3 Volume 7 Endocytobiosis and Cell Research The nitrogen-fixing activity of some Prochloron-ascidian associatons in the Seychelles was measured by using the acetylene reduction method. Only encrusting forms of ascidians showed nitrogenase activity, which did not correlate with chlorophyll a contents in ascidians. Acetylene reduction associated with Prochloron suspensions pressed from ascidians did not correlate with Prochloron cell numbers or chlorophyll a levels in the samples. Prochloron-free pressates, but not isolated Prochloron, showed nitrogenase activity. These results indicate that nitrogen fixation in the Prochloron-ascidian associations in the Seychelles is not linked to the Prochloron symbionts. 253 - 258 1990 1984 jportal_jpjournal_00000006 2007-08-02T10:14:46.587Z 2010-12-16T12:05:28.988Z