Y. Palti et al., Comparative study of biochemical and nonspecific immunological parameters in two tilapia species (Oreochromis aureus and O-mossambicus), ISR J AQUA, 51(4), 1999, pp. 148-156
Oreochromis aureus and O. mossambicus were compared in a preliminary study
of differences in levels of blood biochemical and nonspecific immunological
parameters before and after exposure to acute stress, which was induced by
air exposure for 10 min. Two experiments were conducted. In the first expe
riment comparisons were performed after two weeks of acclimation ("base-lin
e" level), after stress, and for stress response. The latter was calculated
for each fish by subtracting the level after stress exposure from the base
-line level. Significant differences (p<0.01) were identified between speci
es at the base-line level in total plasma cholesterol and total protein lev
els. Glucose concentration was significantly different after stress and in
stress response. Significant differences between species were also identifi
ed in respiratory burst activity of phagocytes after stress and in cerulopl
asmin activity after stress. No significant correlation was identified betw
een body weight and each of the parameters tested, indicating that the diff
erences detected in immunological parameters were not related to the notabl
e size difference between the two groups used in this study. The significan
t differences in total cholesterol and protein were confirmed in the second
experiment. Significant differences (p<0.05) were also detected in levels
of albumin, globulin, lactate dehydrogenase, calcium, total bilirubin and t
riglycirides, which were measured by autoanalyzer, and in alpha, beta 2, an
d IgM globulins, %beta1 and %IgM, which were separated and measured by agar
ose gel electrophoresis. Wide variation was detected within O. aureus in so
me of the parameters examined. A larger sample size should be used to learn
if the differences are large enough to produce segregating O. aureus famil
ies for genetic analysis of those parameters. The differences identified su
ggest that hybrid families from the two species can be used to construct a
segregating population for genetic analysis of immunological traits and str
ess response in tilapia.