Fluctuations in levels of various gangliosides in the different tracts of the oviduct of the frog (Rana esculenta) during the reproductive cycle.

The ganglioside content and pattern have been followed in the different tracts (rectus, convoluted and uterine) of the frog oviduct during the reproductive cycle. The main variations we observed are: a) average higher levels of ganglioside sialic acid in the preovulatory phase, with two peaks in March and April for the convoluted and rectus tract, respectively, and a more homogenous behaviour for the uterine tract; in all three tracts of the oviduct a minimum coincident with the ovulation has been found; b) a balanced presence of sulfolipids and gangliosides in the uterine tract: in fact sulfolipids, whose variations have been determined in a previous work, are higher when gangliosides are lower and vice versa, maintaining nearly constant the total negative charge due to these glycolipids; c) an alternate fluctuation of monosialo- and disialo-gangliosides in the preovulatory phase and a net trend toward the increase of monosialo- and the decrease of disialogangliosides in the postovulatory phase; trisialo-gangliosides are in general less represented and show less marked variations; d) the presence of particular gangliosides in particular moments of the reproductive cycle: Fuc-GM1, a fucosylated ganglioside, is higher than the more represented GM1 during the ovulation, while GD1 alpha, a ganglioside with a sialic acid residue linked to GalNAc, is steadily present in all three tracts after ovulation.(ABSTRACT TRUNCATED AT 250 WORDS)