NOREPINEPHRINE AND DOPAMINE CONTENT OF LARVAE AND SPAT OF THE PACIFIC OYSTER, CRASSOSTREA GIGAS

Abstract

Oyster larvae and spat of varying ages were homogenized and analyzed for catecholamine content using high-performance liquid chromatography with electrochemical detection. Norepinephrine (NE) and dopamine (DA) were found in appreciable quantities, with more DA present than NE. The presence of epinephrine was equivocal. Norepinephrine levels were low in young larvae (0.062 ± 0.035 pg/µg protein), then increased to an intermediate level (0.517 ± 0.031 pg/µg protein) for most of the larval period and finally increased again just before metamorphosis to 1.08 ± 0.09 pg/µg protein. Dopamine levels in the corresponding larval groups did not change significantly, with 11.5 ± 1.9, 8.58 ± 0.98, and 7.47 ± 0.92 pg DA/µ protein, respectively. The levels of NE (1.00 ± 0.04 pg/µg protein) and DA (7.13 ± 0.29 pg/µg protein) present in spat following metamorphosis were not significantly different from the pre-metamorphic values. The presence of NE in oyster larvae at the time of metamorphosis supports the hypothesis of a role for endogenous NE in mediating metamorphosis.

In hemocytes from Mytilus galloprovincialis Lmk., treatment with corticotropin or growth factors conditions catecholamine release

“…However, dopamine concentration in tissues of C. gigas is higher than that of noradrenaline [18], and the situation is the same in other molluscs [8,11,14,34]. According to Lacoste et al [18], stress generates rises in noradrenaline and dopamine concentration in the hemolymph of C. gigas, which coincides with various studies showing the presence of these catecholamines in other molluscs [12,33,[49][50][51][52][53], including bivalves [8,9,34,54,55]. However, Pani and Croll [17] do not find noradrenaline in the hemolymph of the scallop Placopecten magellanicus.…”

Development of the larval nervous system of the gastropod Ilyanassa obsoleta

“…In addition, catecholaminergic foot cells have been suggested to be involved in sensing settlement cues during metamorphosis (Croll et al, 1997). Support for the role of catecholamine cells in metamorphosis has been shown in both gastropods (Pires et al, 2000b) and bivalves (Coon and Bonar, 1986). Furthermore, similarly located cells have also been found to be responsive to the chemical cues inducing metamorphosis in the heterobranch Onchidoris bilamellata (Arkett et al, 1989).…”

The gastropod nervous system in metamorphosis

“…It may be that these chemical compounds are instead involved in the central neural response to the natural inducer (Hirata and Hadfield, 1986). In fact, dopamine (and norepinephrine) have been detected in appreciable quantity in the larvae of the pacific oyster (Coon and Bonar, 1986).…”