The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Yiping Luo - One of the best experts on this subject based on the ideXlab platform.
-
effect of meal size on the Specific Dynamic Action of the juvenile snakehead channa argus
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2012Co-Authors: Qianqian Wang, Wen Wang, Qingda Huang, Yurong Zhang, Yiping LuoAbstract:The effect of meal size on the Specific Dynamic Action (SDA) of the juvenile snakehead (Channa argus) was assessed at 25 °C. The fish were fed with test diets at meal sizes of 0.5, 1, 2, 3, 4, and 5% body mass and the postprandial oxygen consumption rate was determined at 1-h intervals until it returned to the pre-prandial level. The peak metabolic rate increased from 237.4 to 283.2 mg O(2) kg(-1) h(-1) as the relative meal size increased from 0.5% to 3% and leveled off at 4% and 5%. Factorial metabolic scope increased from 1.53 to 1.99 and SDA duration increased from 11.7 to 32.3h as the relative meal size increased from 0.5% to 5%. The relationship between SDA duration (D) and relative meal size (M) was described as: D=4.28 M+10.62 (r(2)=0.752, P<0.05, n=50). The energy expended on SDA increased while the SDA coefficient decreased with increasing meal size. The results of the present study suggest that the snakehead may adopt different feeding strategies when taking in different amounts of food.
-
Effect of meal size on the Specific Dynamic Action of the juvenile snakehead (Channa argus).
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2011Co-Authors: Qianqian Wang, Wen Wang, Qingda Huang, Yurong Zhang, Yiping LuoAbstract:The effect of meal size on the Specific Dynamic Action (SDA) of the juvenile snakehead (Channa argus) was assessed at 25 °C. The fish were fed with test diets at meal sizes of 0.5, 1, 2, 3, 4, and 5% body mass and the postprandial oxygen consumption rate was determined at 1-h intervals until it returned to the pre-prandial level. The peak metabolic rate increased from 237.4 to 283.2 mg O(2) kg(-1) h(-1) as the relative meal size increased from 0.5% to 3% and leveled off at 4% and 5%. Factorial metabolic scope increased from 1.53 to 1.99 and SDA duration increased from 11.7 to 32.3h as the relative meal size increased from 0.5% to 5%. The relationship between SDA duration (D) and relative meal size (M) was described as: D=4.28 M+10.62 (r(2)=0.752, P
-
Specific Dynamic Action in two body size groups of the southern catfish (Silurus meridionalis) fed diets differing in carbohydrate and lipid contents
Fish physiology and biochemistry, 2008Co-Authors: Yiping Luo, X. J. XieAbstract:Specific Dynamic Action (SDA), the energy costs associated with meal digestion and assimilation, is generally affected by body size and food composition. We assessed the postprandial metabolic response and calculated SDA in two size groups of the southern catfish (Silurus meridionalis), each fed one of two diets, high lipid or high carbohydrate, at a meal size of 4% the body mass. Using a continuous-flow respirometer, we determined the oxygen consumption rate at 2-h intervals until the postprandial oxygen consumption rate returned to the prefeeding level. None of the parameters (resting metabolic rate, Rpeak, factorial ratio, time-to-peak, duration, energy expended on SDA, or SDA coefficient) were significantly affected by diet nor was there an interAction between diet and body mass. Rpeak and energy expended on SDA for the whole fish body were significantly higher in the larger fish than the smaller one in both dietary treatments, whereas no significant effect of body size was found in mass Specific values. Factorial ratio (range 3.41 to 3.60), peak time (range 9.6 to 12.7 h), SDA coefficient (range 9.36 to 10.36%), and SDA duration (range 62.0 to 71.0 h) did not significantly differ between body size groups. These results suggest that in S. meridionalis the percentage of assimilated energy allocated to SDA may be independent of the body mass.
-
Effects of temperature on the Specific Dynamic Action of the southern catfish, Silurus meridionalis.
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2007Co-Authors: Yiping Luo, X. J. XieAbstract:Abstract Specific Dynamic Action (SDA), the energy expended on all physiological processes that is associated with meal digestion and assimilation, is strongly affected by temperature. We assessed the effects of temperature on the postprandial metabolic response and calculated SDA of the southern catfish, Silurus meridionalis . The fish was fed with experimental diets at a meal size of 4% body mass, and by using an 8-chamber, continuous-flow respirometer the oxygen consumption rate was determined at a 2 h interval until the postprandial oxygen consumption rate returning to the preprandial level, at four different temperatures. The energy expended on SDA (SDA E ) were 2.71, 3.07, 3.16, and 3.62 kJ, the SDA coefficients (energy expended on SDA quantified as a percentage of the digestible energy content of the meal) were 7.70, 9.44, 10.36, and 11.12%, and the peak metabolic rates ( R peak ) of SDA were 3.48, 4.31, 5.96, and 7.30 mg O 2 h − 1 , at 17.5, 22.5, 27.5, and 32.5 °C respectively. The relationships between those parameters and temperature were: SDA E = 1.74 + 0.0559 T ( n = 26, r 2 = 0.676), SDA coefficient = 4.10 + 0.223 T ( n = 26, r 2 = 0.726), and R peak = − 1.34 + 0.264 T ( n = 26, r 2 = 0.896). The SDA durations showed a slow–fast–slow tendency of decrease with increasing temperature, and were 88.00, 85.71, 67.71, and 66.50 h at 17.5, 22.5, 27.5 and 32.5 °C respectively. Two separate peaks appeared during the SDA response at 17.5 °C, and it might be due to a rapid startup of the mechanical process with a lag of the biochemical process, which suggested that the peaks of “mechanical component” and “biochemical component” of SDA might be separated when temperature was low enough.
J Buchanan - One of the best experts on this subject based on the ideXlab platform.
-
The energetic consequence of Specific Dynamic Action in southern bluefin tuna Thunnus maccoyii.
Journal of Experimental Biology, 2007Co-Authors: Q P Fitzgibbon, R S Seymour, D Ellis, J BuchananAbstract:The effect of feeding on the rate of oxygen consumption ( Ṁ O2) of four groups of three southern bluefin tuna Thunnus maccoyii (SBT) was examined in a large static respirometer at water temperatures of 18.2-20.3°C. Six feeding events of rations between 2.1-8.5% body mass (% M b) of Australian sardines ( Sardinops neopilchardus ) were recorded (two of the groups were fed twice). Before feeding, fish swam between 0.71 and 1.4 body lengths s-1 ( BL s-1) and the routine metabolic rate (RMR) was 366±32.5 mg kg-1 h-1 (mean ± s.e.m.). For all trials, Ṁ O2 was elevated post feeding, presumably as a result of Specific Dynamic Action (SDA). Swimming velocity was also elevated post feeding for periods similar to that of Ṁ O2 (between 20-45 h, longest for the largest rations). Post feeding swimming velocity increased to between 0.87-2.6 BL s-1 and was also dependent on ration consumed. It is suggested that the purpose of increased post-feeding swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. Peak post-prandial Ṁ O2 increased linearly with ration size to a maximum of 1290 mg kg-1 h-1, corresponding to 2.8 times the RMR. When converted to its energy equivalent, total magnitude of SDA was linearly correlated with ration size to a maximum of 192 kJ kg-1 h-1, and as a proportion of gross energy ingested (SDA coefficient), it averaged 35±2.2%. These results demonstrate that, although the factorial increase of SDA in SBT is similar to that of other fish species, the absolute energetic cost of SDA is much higher. These results support the contention that tuna are energy speculators, gambling high rates of energy expenditure for potentially higher rates of energy returns. The ration that southern bluefin tuna require to equal the combined metabolic costs of SDA and RMR is estimated in this study to be 3.5% M b of Australian sardines per day.
-
The energetic consequence of Specific Dynamic Action in southern bluefin tuna Thunnus maccoyii.
The Journal of experimental biology, 2007Co-Authors: Q P Fitzgibbon, R S Seymour, D Ellis, J BuchananAbstract:The effect of feeding on the rate of oxygen consumption (M(O2)) of four groups of three southern bluefin tuna Thunnus maccoyii (SBT) was examined in a large static respirometer at water temperatures of 18.2-20.3 degrees C. Six feeding events of rations between 2.1-8.5% body mass (%M(b)) of Australian sardines (Sardinops neopilchardus) were recorded (two of the groups were fed twice). Before feeding, fish swam between 0.71 and 1.4 body lengths s(-1) (BL s(-1)) and the routine metabolic rate (RMR) was 366+/-32.5 mg kg(-1) h(-1) (mean +/- s.e.m.). For all trials, M(O2) was elevated post feeding, presumably as a result of Specific Dynamic Action (SDA). Swimming velocity was also elevated post feeding for periods similar to that of M(O2) (between 20-45 h, longest for the largest rations). Post feeding swimming velocity increased to between 0.87-2.6 BL s(-1) and was also dependent on ration consumed. It is suggested that the purpose of increased post-feeding swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. Peak post-prandial M(O2) increased linearly with ration size to a maximum of 1290 mg kg(-1) h(-1), corresponding to 2.8 times the RMR. When converted to its energy equivalent, total magnitude of SDA was linearly correlated with ration size to a maximum of 192 kJ kg(-1) h(-1), and as a proportion of gross energy ingested (SDA coefficient), it averaged 35+/-2.2%. These results demonstrate that, although the factorial increase of SDA in SBT is similar to that of other fish species, the absolute energetic cost of SDA is much higher. These results support the contention that tuna are energy speculators, gambling high rates of energy expenditure for potentially higher rates of energy returns. The ration that southern bluefin tuna require to equal the combined metabolic costs of SDA and RMR is estimated in this study to be 3.5%M(b) of Australian sardines per day.
X. J. Xie - One of the best experts on this subject based on the ideXlab platform.
-
Effects of waterborne cadmium exposure on growth performance, Specific Dynamic Action, and energy budget of southern catfish Silurus meridionalis
Aquaculture, 2019Co-Authors: X. J. XieAbstract:Abstract This study investigated the effect of waterborne cadmium (Cd) exposure on the growth performance, Specific Dynamic Action (SDA), and energy budget of southern catfish (Silurus meridionalis). S. meridionalis was exposed to various Cd concentrations (0–500 μg L−1) for 8 weeks. The Specific growth rate (SGR), apparent digestibility, protein apparent digestibility, SDA parameters, and components of energy budgets were then determined. Compared to the control group, SGR was significantly reduced upon Cd exposure at 250 μg L−1 and 500 μg L−1. Compared to the control group, the experimental groups (62.5–500 μg L−1) showed significantly lower total feed intake and feed conversion efficiency. The apparent digestibility and protein apparent digestibility was significantly decreased in the 250 μg L−1 and 500 μg L−1 experimental groups compared to the control group. A significantly lower peak metabolic rate, SDA, and SDA coefficient were observed in the 250 μg L−1 and 500 μg L−1 experiment groups compared to the control group. The ratio of growth energy to assimilation energy in the 62.5–500 μg L−1 experimental groups was significantly lower than that of the control group. There was a significant increase in the ratio of metabolic energy to assimilation energy in Cd exposed groups compared to the control group. These results indicate that waterborne Cd exposure decreased the protein apparent digestibility, resulting in decreased SDA and SDA coefficient. Waterborne Cd exposure resulted in increased proportion of excretion energy and feces energy in S. meridionalis, whereas assimilation energy was reduced. Moreover, for assimilation energy, the energetic proportion for metabolism was increased, whereas the energetic proportion for growth was reduced
-
Specific Dynamic Action in two body size groups of the southern catfish (Silurus meridionalis) fed diets differing in carbohydrate and lipid contents
Fish physiology and biochemistry, 2008Co-Authors: Yiping Luo, X. J. XieAbstract:Specific Dynamic Action (SDA), the energy costs associated with meal digestion and assimilation, is generally affected by body size and food composition. We assessed the postprandial metabolic response and calculated SDA in two size groups of the southern catfish (Silurus meridionalis), each fed one of two diets, high lipid or high carbohydrate, at a meal size of 4% the body mass. Using a continuous-flow respirometer, we determined the oxygen consumption rate at 2-h intervals until the postprandial oxygen consumption rate returned to the prefeeding level. None of the parameters (resting metabolic rate, Rpeak, factorial ratio, time-to-peak, duration, energy expended on SDA, or SDA coefficient) were significantly affected by diet nor was there an interAction between diet and body mass. Rpeak and energy expended on SDA for the whole fish body were significantly higher in the larger fish than the smaller one in both dietary treatments, whereas no significant effect of body size was found in mass Specific values. Factorial ratio (range 3.41 to 3.60), peak time (range 9.6 to 12.7 h), SDA coefficient (range 9.36 to 10.36%), and SDA duration (range 62.0 to 71.0 h) did not significantly differ between body size groups. These results suggest that in S. meridionalis the percentage of assimilated energy allocated to SDA may be independent of the body mass.
-
Effects of temperature on the Specific Dynamic Action of the southern catfish, Silurus meridionalis.
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2007Co-Authors: Yiping Luo, X. J. XieAbstract:Abstract Specific Dynamic Action (SDA), the energy expended on all physiological processes that is associated with meal digestion and assimilation, is strongly affected by temperature. We assessed the effects of temperature on the postprandial metabolic response and calculated SDA of the southern catfish, Silurus meridionalis . The fish was fed with experimental diets at a meal size of 4% body mass, and by using an 8-chamber, continuous-flow respirometer the oxygen consumption rate was determined at a 2 h interval until the postprandial oxygen consumption rate returning to the preprandial level, at four different temperatures. The energy expended on SDA (SDA E ) were 2.71, 3.07, 3.16, and 3.62 kJ, the SDA coefficients (energy expended on SDA quantified as a percentage of the digestible energy content of the meal) were 7.70, 9.44, 10.36, and 11.12%, and the peak metabolic rates ( R peak ) of SDA were 3.48, 4.31, 5.96, and 7.30 mg O 2 h − 1 , at 17.5, 22.5, 27.5, and 32.5 °C respectively. The relationships between those parameters and temperature were: SDA E = 1.74 + 0.0559 T ( n = 26, r 2 = 0.676), SDA coefficient = 4.10 + 0.223 T ( n = 26, r 2 = 0.726), and R peak = − 1.34 + 0.264 T ( n = 26, r 2 = 0.896). The SDA durations showed a slow–fast–slow tendency of decrease with increasing temperature, and were 88.00, 85.71, 67.71, and 66.50 h at 17.5, 22.5, 27.5 and 32.5 °C respectively. Two separate peaks appeared during the SDA response at 17.5 °C, and it might be due to a rapid startup of the mechanical process with a lag of the biochemical process, which suggested that the peaks of “mechanical component” and “biochemical component” of SDA might be separated when temperature was low enough.
-
Effect of feeding level and feeding frequency on Specific Dynamic Action in Silurus meridionalis
Journal of Fish Biology, 2005Co-Authors: X. J. Xie, Z. D. CaoAbstract:The effect of feeding level (F L ; 0.5 to 4% dry diet mass per wet fish body mass) and feeding frequency (once every 4 days to twice per day) on postprandial metabolic response was investigated in southern catfish Silurus meridionalis at 27.5° C. The results showed that there was no significant difference in the Specific Dynamic Action (SDA) coefficient among the groups of different feeding levels (P > 0.05). The duration increased from 26.0 to 40.0 h and the peak metabolic rate increased from 207.8 to 378.8 mg O 2 kg -1 h -1 when the feeding level was increased from 0.5 to 4%. The relationship between the peak metabolic rate (Rp, mg O 2 kg -1 h -1 ) and F L could be described as: Rp = 175-4 + 47.3 F L (r 2 = 0.943, n = 40, P < 0.001). The relationship between the SDA duration (D, h) and F L could be described as D = 30.97F L 0.248 (r 2 = 0.729, n = 40, P < 0.001).
-
Effect of dietary composition on Specific Dynamic Action in southern catfish Silurus meridionalis Chen
Aquaculture Research, 2005Co-Authors: X. J. Xie, Z. D. CaoAbstract:The effect of dietary macronutrient composition on Specific Dynamic Action (SDA) in southern catfish Silurus meridionalis Chen juveniles (39.0±2.8 g) was studied. A control diet (40% protein, 10% lipid and 15% carbohydrate) was the optimal dietary profile for growth in this catfish according to a previous study. Based on this, two diets were formulated by substituting protein and lipid for one another, referred to as LPHL (30% P:15% L) and HPLL (50% P:5% L), and two diets were formulated by substituting protein and carbohydrate for one another, referred to as LPHC (30% P:30% C) and HPLC (50% P:0% C). The results showed that dietary composition affected the peak metabolic rate, duration and SDA coefficient. The peak metabolic rate in the LPHC group (211.5 mgO2 kg−1 h−1) was significantly lower than catfish in the control (265.2 mg O2 kg−1 h−1) and the HPLC (257.7 mg O2 kg−1 h−1) group. The SDA duration in the control group (26.8 h) was significantly shorter than those of the HPLL (38.0 h), LPHC (33.8 h) and HPLC (33.8 h) groups. The SDA coefficient in the LPHL group (11.1%) was significantly lower than those of the control and the other groups (13.2–15.4%). The results suggest that in southern catfish, the SDA response to dietary carbohydrate is similar to that of dietary protein, and that the SDA may not be affected solely by an increase in the amount of protein ingested, but may be influenced by interAction of other dietary components.
Q P Fitzgibbon - One of the best experts on this subject based on the ideXlab platform.
-
The energetic consequence of Specific Dynamic Action in southern bluefin tuna Thunnus maccoyii.
Journal of Experimental Biology, 2007Co-Authors: Q P Fitzgibbon, R S Seymour, D Ellis, J BuchananAbstract:The effect of feeding on the rate of oxygen consumption ( Ṁ O2) of four groups of three southern bluefin tuna Thunnus maccoyii (SBT) was examined in a large static respirometer at water temperatures of 18.2-20.3°C. Six feeding events of rations between 2.1-8.5% body mass (% M b) of Australian sardines ( Sardinops neopilchardus ) were recorded (two of the groups were fed twice). Before feeding, fish swam between 0.71 and 1.4 body lengths s-1 ( BL s-1) and the routine metabolic rate (RMR) was 366±32.5 mg kg-1 h-1 (mean ± s.e.m.). For all trials, Ṁ O2 was elevated post feeding, presumably as a result of Specific Dynamic Action (SDA). Swimming velocity was also elevated post feeding for periods similar to that of Ṁ O2 (between 20-45 h, longest for the largest rations). Post feeding swimming velocity increased to between 0.87-2.6 BL s-1 and was also dependent on ration consumed. It is suggested that the purpose of increased post-feeding swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. Peak post-prandial Ṁ O2 increased linearly with ration size to a maximum of 1290 mg kg-1 h-1, corresponding to 2.8 times the RMR. When converted to its energy equivalent, total magnitude of SDA was linearly correlated with ration size to a maximum of 192 kJ kg-1 h-1, and as a proportion of gross energy ingested (SDA coefficient), it averaged 35±2.2%. These results demonstrate that, although the factorial increase of SDA in SBT is similar to that of other fish species, the absolute energetic cost of SDA is much higher. These results support the contention that tuna are energy speculators, gambling high rates of energy expenditure for potentially higher rates of energy returns. The ration that southern bluefin tuna require to equal the combined metabolic costs of SDA and RMR is estimated in this study to be 3.5% M b of Australian sardines per day.
-
The energetic consequence of Specific Dynamic Action in southern bluefin tuna Thunnus maccoyii.
The Journal of experimental biology, 2007Co-Authors: Q P Fitzgibbon, R S Seymour, D Ellis, J BuchananAbstract:The effect of feeding on the rate of oxygen consumption (M(O2)) of four groups of three southern bluefin tuna Thunnus maccoyii (SBT) was examined in a large static respirometer at water temperatures of 18.2-20.3 degrees C. Six feeding events of rations between 2.1-8.5% body mass (%M(b)) of Australian sardines (Sardinops neopilchardus) were recorded (two of the groups were fed twice). Before feeding, fish swam between 0.71 and 1.4 body lengths s(-1) (BL s(-1)) and the routine metabolic rate (RMR) was 366+/-32.5 mg kg(-1) h(-1) (mean +/- s.e.m.). For all trials, M(O2) was elevated post feeding, presumably as a result of Specific Dynamic Action (SDA). Swimming velocity was also elevated post feeding for periods similar to that of M(O2) (between 20-45 h, longest for the largest rations). Post feeding swimming velocity increased to between 0.87-2.6 BL s(-1) and was also dependent on ration consumed. It is suggested that the purpose of increased post-feeding swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. Peak post-prandial M(O2) increased linearly with ration size to a maximum of 1290 mg kg(-1) h(-1), corresponding to 2.8 times the RMR. When converted to its energy equivalent, total magnitude of SDA was linearly correlated with ration size to a maximum of 192 kJ kg(-1) h(-1), and as a proportion of gross energy ingested (SDA coefficient), it averaged 35+/-2.2%. These results demonstrate that, although the factorial increase of SDA in SBT is similar to that of other fish species, the absolute energetic cost of SDA is much higher. These results support the contention that tuna are energy speculators, gambling high rates of energy expenditure for potentially higher rates of energy returns. The ration that southern bluefin tuna require to equal the combined metabolic costs of SDA and RMR is estimated in this study to be 3.5%M(b) of Australian sardines per day.
Edwin W. Taylor - One of the best experts on this subject based on the ideXlab platform.
-
Specific Dynamic Action in the shore crab, Carcinus maenas (L.), in relation to acclimation temperature and to the onset of the emersion response.
Physiological and biochemical zoology : PBZ, 2002Co-Authors: R.f. Robertson, J. Meagor, Edwin W. TaylorAbstract:The rate of oxygen uptake (MO(2)) of shore crabs following a period of fasting varied directly with acclimation temperature, with a Q(10) of 2.96 between 7 degrees and 15 degrees C and a Q(10) of 2.11 between 15 degrees and 22 degrees C. The factorial rise in MO(2) following a meal (Specific Dynamic Action [SDA]) ranged between 1.9 and 3.1 and varied with temperature, being highest at 15 degrees C and significantly lower at both 7 degrees and 22 degrees C, despite similar ration sizes in all groups. At 7 degrees C, the SDA coefficient and magnitude were significantly lower than at 15 degrees C, possibly due in part to the inhibition of protein synthesis. Both the time to peak and the duration of the SDA response were inversely related to temperature. SDA coefficients were inversely related to the amount of food consumed. The critical oxygen tension of inspired water (P(I)O(2)), which evoked the emersion response in fasted animals, increased with temperature and further increased at each temperature when the animals were fed. Thus, the threshold P(I)O(2) evoking the emersion response is directly related to relative metabolic oxygen demand in Carcinus.
-
Protein synthesis and Specific Dynamic Action in crustaceans: effects of temperature.
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2001Co-Authors: N.m. Whiteley, R.f. Robertson, J. Meagor, A.j. El Haj, Edwin W. TaylorAbstract:Temperature influences the Specific Dynamic Action (SDA), or rise in oxygen uptake rate after feeding, in eurythermal and stenothermal crustaceans by changing the timing and the magnitude of the response. Intra-Specific studies on the eurythermal crab, Carcinus maenas, show that a reduction in acclimation temperature is associated with a decrease in SDA magnitude, resulting from an increase in SDA duration but a decrease in peak factorial scope (the factorial rise in peak SDA over prefeeding values). Inter-Specific feeding studies on stenothermal polar isopods revealed marked differences in SDA response between the Antarctic species, Glyptonotus antarcticus and the Arctic species, Saduria entomon. Compared to S. entomon held at 4 and 13°C, the SDA response in G. antarcticus held at 1°C was characterised by a lower absolute oxygen uptake rate at peak SDA and an extended SDA duration. At peak SDA, whole animal rates of protein synthesis increased in proportion to the postprandial increase in oxygen uptake rate in the Antarctic and the Arctic species. Rates of oxygen uptake plotted against whole animal rates of protein synthesis gave similar relationships in both isopod species, indicating similar costs of protein synthesis after a meal, despite their differences in SDA response and thermal habitat.
-
Effects of temperature on Specific Dynamic Action and protein synthesis rates in the baltic isopod crustacean, Saduria entomon
Journal of Experimental Marine Biology and Ecology, 2001Co-Authors: R.f. Robertson, Andrew Clarke, A. J. El-haj, Edwin W. TaylorAbstract:The mean rate of oxygen consumption in fasted Saduriaentomon increased between 4°C and 13°C with a Q10 of 2.33. After feeding, rates of oxygen uptake increased significantly by two- to threefold at both temperatures. However, the magnitude of the ‘Specific Dynamic Action of food’ (SDA) response varied with temperature. At 4°C, the magnitude was 45.5±4.2 μmol, while at 13°C, magnitude was significantly higher at 62.8±6.5 μmol. In contrast, the duration of the response did not vary significantly with temperature in Saduria, with the consequence that the duration at 4°C was considerably shorter than that measured at this temperature from an Antarctic isopod in a parallel study, and the duration at 13°C was considerably longer than published values for temperate crustaceans at similar temperatures. Fasted rates of ammonia excretion increased with a Q10 of 4.74 between 4°C and 13°C. The increase after feeding was sevenfold at 4°C but only 2.6-fold at 13°C. Fasted O/N ratios for Saduria at 4°C were about twice those at 13°C. Fasted whole body protein synthesis rates (kS) increased with a Q10 of 2.61 between 4°C and 13°C. Whole body kS, measured at the peak of the SDA response, showed significant 2.7-and 1.9-fold increases at 4°C and 13°C, respectively, compared to fasted values, although the factorial rise at 13°C was reduced compared to 4°C. Alterations in kS rates after feeding at both temperatures resulted from significant increases in RNA activity (KRNA) alone. However, the increase in kS between 4°C and 13°C was accompanied by increases in both KRNA and RNA/protein ratio, a measure of the capacity for protein synthesis (CS).
