Agglutination activity of algal extracts against spermatozoa of the fish Diplodus sargus L.

Spermatozoa from the fish Diplodus sargus L. were agglutinated by seaweed extracts. Three interaction types were observed: head to head, tail to tail and head to tail. There was not singular agglutination for each algal species tested. Of all algal extracts, 16% of brown algae and 3% of red algae, showed agglutinating activity. In the brown algae, the maximum agglutinating activity was shown by Fucus serratus (1:256), whereas in the red algae the maximum agglutinating activity was shown by Polyneura halliae (1:32). None of the green algae assayed showed agglutinating activity. Some algal extracts can recognize specific binding sites on the spermatozoa membrane. In the inhibition assay, four carbohydrates showed inhibition activity in the case of Fucus spiralis: 1-β-