Application
of enzyme-linked immunosorbent assay for studying of reproduction in the
Manila clam Ruditapes philippinarum (Mollusca: Bivalvia)
I.
Quantifying eggs
K.I.
Park, K.-S. Choi-2004
Aquaculture, 241(1-4): 667-687
Abstract:
A
polyclonal antibody specific to Ruditapes philippinarum egg protein
(ME-ab) was developed to quantify clam eggs using an enzyme-linked
immunosorbent assay (ELISA). Western blots revealed that ME-ab reacted with
egg proteins of molecular masses 475, 84, and 40 kDa under non-reducing
conditions and 330, 96, 64, 50, and 31 kDa under reducing conditions. With
ELISA, ME-ab detected between 0.23 and 15 μg ml−1 of
clam egg protein; the number of eggs per clam was quantified by dividing the
weight of the total egg protein by the average weight per egg. Reproductive
output, expressed as the gonadosomatic index (GSI), was calculated as the
ratio of the egg weight to the total tissue weight. Seasonal changes in
reproductive output were measured in clams collected on a monthly basis from
Gomso Bay, Korea. Clam egg protein was detected during all months except
January. The monthly mean GSI varied from 0 (January) to 0.25 (August), and
the highest GSI (0.389) was recorded from a clam collected in late July.
ELISA indicated that clams in Gomso Bay spawned when the gonad accounted for
20% of the total tissue weight. The fecundity estimated from individual
clams before spawning ranged from 0.94 to 11.79 million eggs, with a mean of
4.15 million. In conclusion, the ELISA used in this study was a sensitive
and rapid method for quantifying eggs in individual clams and is considered
the method of choice for quantifying the reproductive output.
(School
of Applied Marine Science, Cheju National University, 1 Ara 1-Dong, Jeju
690-756, Republic of Korea, e-mail of K.-S. Choi: skchoi@cheju.ac.kr)