E . Mayrand et al. J. Exp. Mar. Biol. Ecol. 255 2000 37 –49
41
Individual MC 2 mean MC
day 60 at ration X day 25 at ration X
]]]]]]]]]]]]]]] G
5
day 60 – day 25
Number of days The variation in protein:DNA ratio and DNA content per ml of merus as well as growth
rates for the whole dry digestive gland were calculated in the same way. 2.5. Statistics
The number of observations was 44 for all variables except proteins n 543. Statistical tests were conducted with the following nine variables: muscle growth rate,
temporal variation in protein:DNA ratio, DNA content per ml of merus and the whole dry mass of digestive gland, RNA:DNA ratio, PFK, LDH, CS, and CCO activity per ml
of merus. Normality was tested using Lilliefors’ test. To attain normality, the RNA:DNA ratio was log transformed. The other variates were untransformed. The relationships
between the variates were assessed by listwise Pearson’s simple correlation. Partial correlations coefficients were also computed to evaluate the relationship between two
variables when the seven others were held constant. Partial F-test was used to determine if the coefficients were significantly different from 0. We used this approach to
discriminate between the respective effects of muscle growth rate and nutritional status on the variates which were tested as potential indicators of growth. To allow comparison
with the literature, simple and partial correlation coefficients between muscle growth rate and the enzyme activity expressed per g of protein, mg of DNA and g of dry muscle
were calculated.
3. Results
21
Muscle growth rates G ranged from 20.732 to 0.915 mg dry muscle ml merus
21
day . Changes in muscle cell size Dprotein:DNA, as estimated by the change in
protein:DNA ratio per day, varied from 214.586 to 15.772. Variation in muscle cell
21 21
number DDNA was estimated by the change in mg of DNA ml merus day
and ranged from 20.500 to 0.750. The growth rate of the digestive gland varied from
21
20.050 to 0.052 g dry tissue day .
Muscle growth rate was based on changes in the number of muscle cells, as indicated by the positive simple and partial correlation between G and DDNA Table 1 and Fig.
1. An increase in muscle cell size was accompanied by higher levels of cellular machinery available for protein synthesis, as shown by the significant positive
correlation between Dprotein:DNA and log RNA:DNA ratio Table 1 and Fig. 2.
Muscle growth rate was positively correlated with the activity of PFK per ml of merus, while the variation in muscle cell size matched the PFK and CS activity per ml of
merus Table 1 partial correlations, Fig. 3. Significant negative simple correlations were noted between muscle growth rate and the enzyme activity expressed per g of protein
PFK, LDH, CS, CCO, per mg of DNA CCO, and per g of dry muscle PFK, LDH, CS, CCO, as shown in Table 2. However, none of these relationships was significant
42 E
. Mayrand et al. J. Exp. Mar. Biol. Ecol. 255 2000 37 –49 Table 1
Pearson’s correlation between the physiological variables measured in male snow crabs 25 and 60 days after
a
moult
G DDNA
DP:D Ddig. gl.
R:D PFK
LDH CCO
CS G
0.645 0.661
0.709 0.377
0.400 0.660
DDNA 0.465
0.399 20.401
0.506 0.503
0.469 0.618
DP:D 0.681
0.362 Ddig.gl.
0.556 0.396
0.311 R:D
0.508
PFK 0.335
0.388 0.483
0.600 0.675
LDH 0.374
0.627 CCO
0.468 0.617
CS 0.347
0.491 0.425
a
Upper right: r values for simple correlation, df541. Lower left: in bold r values for partial correlation, df534. Only significant r values are given. P ,0.05, P ,0.01, P ,0.001. G: muscle growth rate in
21 21
21 21
mg dry tissue ml merus day
; DDNA: variation in muscle cell number, in mg DNA ml merus day
;
21
DP:D: variation in muscle cell size, in protein:DNA day ; Ddig. gl.: digestive gland growth rate, in g dry
21 21
tissue day ; R:D: log RNA:DNA ratio. Enzyme activities are expressed in Units ml of merus
. The RNA:DNA ratio is log transformed, the other variates are untransformed.
Fig. 1. Muscle growth rate versus variation in the number of muscle cells as estimated by changes in the DNA content per ml of merus per day in C
. opilio.
E . Mayrand et al. J. Exp. Mar. Biol. Ecol. 255 2000 37 –49
43
Fig. 2. Variation in muscle cell size versus the RNA:DNA ratio in muscle of C . opilio.
Fig. 3. Muscle growth rate versus phosphofructokinase activity per ml of merus in C . opilio.
44 E
. Mayrand et al. J. Exp. Mar. Biol. Ecol. 255 2000 37 –49 Table 2
a
Pearson’s correlation coefficients between muscle growth rate G and the enzyme activity
21 21
21
Enzymes Activity g protein
Activity mg DNA Activity g dry mass
Simple Partial
Simple Partial
Simple Partial
PFK 20.310
0.068 20.051
20.030 20.341
20.273 LDH
20.361 20.071
20.247 20.026
20.395 20.034
CCO 20.317
20.144 20.326
20.126 20.508
20.131 CS
20.317 0.009
20.031 20.076
20.293 20.265
a
Simple and partial coefficients are given. Partial correlation coefficients are computed between muscle growth rate and a given enzyme activity with the other seven variates kept constant. P ,0.05, P ,0.01,
P ,0.001. n 543, df541 for simple correlations and 34 for partial correlations.
when partial correlation coefficients were computed, holding the seven other variates constant.
Somatic growth and the nutritional status, as represented by changes in the digestive gland dry mass, varied together as shown by the positive simple and partial correlations
between G and Ddigestive gland Table 1 and Fig. 4. It is noteworthy that the significant relationships between Ddigestive gland and the PFK and CS activity per ml
of merus did not hold when partial correlations were computed.
Fig. 4. Muscle growth rate versus the digestive gland growth rate in C . opilio.
E . Mayrand et al. J. Exp. Mar. Biol. Ecol. 255 2000 37 –49
45
4. Discussion
