Effect of Winter and Summer Temperatures on Some Physiological Parameters in an Egyptian Lizard (Novoeumeces Schneiderii)

Effect of Winter and Summer Temperatures on Some Physiological Parameters in an Egyptian Lizard (Novoeumeces schneiderii)

Abd El-Baset M.A. Abd El Reheem

Zoology Department Faculty of Science, Al-Azhar University, Assuit, Egypt

Abstract: The aim of the present study to investigate differences between winter and summer temperatures on some adaptive physiological properties, particularly, thermoregulation, metabolic enzymes and osmolallity. We focused on thermoregulation of this animal particularly cloacal temperature, blood biochemical compounds of osmolallity. And the metabolic enzymes as, citrate synthase (CS), a key enzyme of the Krebs cycle; lactate dehydrogenase (LDH) a key enzyme of as part of the anaerobic glycolytic pathway and also measured cytochrome C oxidase (CCO), part of the aerobic electron transport chain , these enzymes were measured in muscle and blood at winter and summer temperatures in a reptile (the Egyptian lizard, Novoeumeces schneiderii). The results indicated that it is of outmost physiological interest to note that although ambient temperatures in winter group was 8.0 °C, cloacal temperature- which represents body core temperature- did not decrease remarkably beyond about 14.6°C which seems to be the lower limit and 16.4°C the high limit with mean 15.5±0.9°C; of body temperature range of change in winter group of this lizard. On the other hand, under high ambient temperature, however, ranging from 30°C to 35 °C, it was clear that the body temperature of this lizard is quite closely, to the ambient temperature and the lower limit body temperature is 31.5°C with the high limit is 33.5°C and mean 32.5±1°C .The results indicated that there were significant differences in daily body temperatures between winter and summer body temperatures and fluctuated significantly more in winter compared with summer. This lizard compensated for lower winter temperatures by increasing enzyme activities in muscle, and the activities of cytochrome C oxidase and lactate dehydrogenase and citrate synthase were significantly greater in winter compared with summer at all assay temperatures in the muscle. On the other hand, blood metabolic enzymes activities (cytochrome C oxidase and lactate dehydrogenase and citrate synthase) were significantly decreased in winter compared with summer. Also the results indicate that highly significant decreased of blood osmolallity in summer temperatures compared with increased blood osmolallity in winter temperatures

Key words: thermoregulation, enzymes, osmolallity

INTRODUCTION thermal physiology[23]. Behavioural adjustments enable many diurnal species of reptile to maintain high and Reptiles often regulate their body temperature to stable body temperatures in the face of fluctuations in attain the preferred body temperature (PBT),which is environmental temperatures[6,37]. The importance of the temperature the animals select when placed in body temperature regulation is seen to lie in cage containing a range of different temperatures from maximising the rates of temperature-sensitive hot to cold .It is assumed , however , that PBT is the physiological functions[24]. The rates of chemical optimum temperature for the animal physiological reactions, including those catalysed by enzymes, are process[5]. The ability of ectotherm to attain or maintain dependent on the energetic state of the compounds a particular body temperature is largely dependent upon involved, which in turn is strongly influenced by its realized and potential rates of thermal exchange temperature. The rates of most physiological processes with the environment[34].The PBT shows interspecific are, therefore, a direct function of the temperature of variations and seems to affect by other environmental the organism. Thermoregulation that includes high parameters, season and time of the day[33,7]. The metabolic heat production combined with effective concept that reptiles regulate their body temperature by insulation often allows endotherms to maintain an behavioural means, such as shuttling between sun and elevated body temperature within a narrow range[28]. shade, has become widely accepted in vertebrate The low metabolic rates of reptiles make metabolic heat

Corresponding Author: Abd El-Baset M.A. Abd El Reheem, Zoology Department, Faculty of Science, Al-Azhar University, Assuit, Egypt. E.mail: [email protected] 73 J. Appl. Sci. Res., 5(1): 73-81, 2009 production negligible, and regulation of body seasonal fluctuations in thermal conditions[13], and temperature is achieved by behavioural means such as winter body temperatures, even of tropical crocodiles, microhabitat selection[23] and behavioural posturing[37]. for example, are several degrees below summer In addition, many reptiles can alter rates of heat averages, with the animals nonetheless remaining exchange with the environment by increasing or active[39,20]. decreasing heart rate and peripheral blood flow during heating or cooling, respectively[38,34]. However, it is also MATERIALS AND METHODS possible that animals respond to changing thermal environments by changing their biochemical Animals: The present study was carried out on twenty characteristics rather than attempting to maintain stable Egyptian Lizard gold skink; Orange-tailed skink; Umm body temperatures[14,21]. Phenotypic changes in response El Haiyat old name (Eumeces schneiderii) new name t o v a r i a t i o n i n e n v i r o n m e n ta l c o n d i t i o n s (Novoeumeces schneiderii) .which mostly found in the (acclimatisation) may confer selective advantages by Mediterranean Coastal Desert of Egypt and Sinai Siwa counteracting environmentally induced declines in Oasis and mountains of southern Sinai . This attractive performance[50,25]. Acclimatisation is thought to occur skink inhabits sandy desert with relatively dense particularly in response to long-term changes in vegetation .It digs shallow burrows but occasionally environmental conditions, such as to seasonal or occupies empty rodent burrows).This animal hibernates latitudinal variation[36,49]. Temperature influences some in the winter and hides into superficial burrows where organism functions strongly and others weakly[29]. In it spends the cold winter months[35]. This work was addition, there may be differences in metabolic enzyme achieved in the laboratory under low (winter) and high activities among closely related species living at ( s u m m e r ) t e m p e r a t u r e s , t h e a m b i e n t different latitudes[32]. A number of varieties of enzymes temperatures(laboratory) were ranged from 8.0 to have been observed in the blood of reptiles. Kaplan 15.0°C with means 11.5±3.5°C in winter and ranged and Timmons[26] working on Uromastyx hardwickii; from 30 to 35°C with mean 32.5±2.5°C in summer Taylorand Jacobson[46] working on tortoise; Chauhan[10] .The studied animals were put in a cage so designed as working on Hemidactylus faviviridis and Uromatyx to facilitate handling of the animal and to give it hardikii and Abd El-Reheem[1] working on Uromastyx freedom to move and eat. The lizards divided into two aegyptius, they reported that enzymes activity levels in groups, each group has ten animals. blood appeared to show general trend to increase during the activity period compared with hibernated Measurement of Cloacal Temperature: Cloacal p e r i o d o f t h e s e r e p t i l e s . M e t a b o l i c temperature records were obtained from ten animals in acclimation/acclimatisation may occur at the each group. Cloacal temperature was measured with ultrastructural level, such as in mitochondrial numbers special thermistor, equipped with certain kind of probe or cristae density[45,21], or by changes in enzyme for measuring cloacal temperature. The probe was activity[14]. Enzyme activity may be altered in response inserted to suitable length into the rectum for three to temperature by changing rates of transcription and minutes. The insertion of probe was carefully enzyme concentrations[15,42] or by expressing allozymes introduced with little screwing motion. Cloacal and isozymes with different thermal sensitivities[27,16]. temperature was measured every week at 8:0 am for 14 Metabolic enzyme activities were downregulated during weeks. winter hibernation compared with the preceding, warmer activity period in a turtle (Chrysemys picta Blood Collection: Blood was collecting from the marginata) living at mid to high latitudes[30]. orbital sinus of the eyes at the end of each week. To Depression in enzyme activity during winter dormancy measurement some metabolic enzymes in blood as may result from a combination of low temperatures and (Lactate dehydrogenase (LDH); Citrate synthase (CS) anoxic conditions[44]. Other than during winter and Cytochrome C oxidase (CCO) in blood .Hemolysis hibernation, reptiles are thought not to acclimatise must be avoided because of high lactate dehydrogenase biochemically but, instead, to thermoregulate (LDH) in red cells. Serum should be used for the assay behaviorally or become inactive when environmental since heparin; oxalate and EDTA reportedly inhibit conditions preclude the attainment of `preferred' body LDH activity. Blood is drawn into a plain tube and temperatures[17,18]. Many reptiles, however, are active at allowed to clot. Serum is separated promptly within 30 seasonally varying body temperatures[39,20], and it is minutes from the clot by any conventional method, conceivable that reptiles too could gain selective avoiding contamination from red cell LDH. Serum advantages from regulating biochemical capacities in enzymes showed be determined at the same time when response to changing environmental conditions. Semi- taken from the animals. Fourteen blood samples were aquatic species, in particular, experience pronounced collected from each animal.

74 J. Appl. Sci. Res., 5(1): 73-81, 2009

Tissue Samples: At the end of each week tissue dehydrogenase (LDH), citrate synthase (CS) and samples were collected from all captured animals by cytochrome C oxidase (CCO), which are active in punch biopsy at the side of the tail scales posterior to anaerobic glycolysis, the Krebs cycle and the electron the vent. transport chain, respectively measured by using Voet and Voet[47] cited by Seebachers et al.[42]. Enzyme Detrmination of Tissue Enzymes: To determine the activity was determined with a U V /visible activity LDH; SC and CCO activity in tissue used spectrophotometer equipped with a temperature- Sigma diagnostics reagents for in vitro) enzymes controlled cuvette holder, capable of accurately activity calculated as (units /g wet tissue). The measuring absorbance at 340nm. activities of lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome c oxidase (CCO), which Determination Items Serum Osmolality (mmol/l): are active in anaerobic glycolysis, the Krebs cycle and The items serum osmolality as glucose, urea and the electron transport chain, respectively measured by sodium: (glucose and urea were determined according using Voet and Voet[47] cited by Seebachers et al.[42]. to the method of Bergmeyer[9] and Patton and Enzyme activity was determined with a UV/ Crouch[31] which expressed as mmol-1.All determinations spectrophotometer equipped with a temperature- were done calorimetrically using kits of Boehringer controlled cuvette holder, capable of accurately using spectrophotometer. Sodium concentration mmol/l measuring absorbance at 340nm. Calculations of was determined by flame photometry. enzyme activity were based on the linear portions of the reaction rates, and enzyme activity was expressed Osmolality mmol/l: was calculated by using the as unit g–1 wet tissue. One unit is equivalent to 1 µmol equation =2 [Na] + [urea] + [glucose] according to substrate transformed min–1 . Muscle tissue (0.05–0.1 g) Walmsley and white[48]. was homogenized in nine volumes of extraction buffer (pH 7.5), consisting of 50 mmol l–1 imidazole / HCl, 2 Statistical Analysis: The obtained data were compared –1 –1 mmol l MgCl2, 5 mmol l ethylene diamine tetra- by analysis of variance (ANOVA) with season acetic acid (EDTA), 1 mmol l–1 reduced glutathione (summer and winter), as factors. Individual means were and 1% Triton X-100, and tissue was kept on ice compared by Student t-test were preformed. Values are during homogenisation. LDH activity was determined given as means ±Standard deviation using program by following the absorbance of NADH at 340nm. The SPSS. The statistical method according to Sokal and assay medium was 100 mmol l–1 potassium phosphate Rahif[43]. (KH2PO4/K2PO4) buffer (pH 7.0), 0.16 mmol l–1 NADH and 0.4 mmol l–1 pyruvate. The millimolar RESULTS AND DISCUSSION extinction coefficient of NADH is 6.22 CS activity was measured as the reduction of DTNB [5, 5' dithiobis-(2- Cloacal Temperatures: In order to study the effect of nitrobenzoic) acid] at 412 nm. The assay was temperature on activities of metabolic enzymes and conducted in 100 mmol l–1 Tris/HCl, pH 8.0, 0.1 mmol thermoregulation, we first had to study the body l–1 DTNB, 0.1mmol l–1 acetyl CoA and 0.15 mmol l–1 temperatures, changes in metabolism and changers in oxaloacetate. Control assays (in which oxaloacetate was the activities of the enzymes during winter and summer omitted) were performed to quantify any transfer of temperatures. The results indicated that, mean ambient sulfhydryl groups to DTNB other than that caused by temperatures, °C were recorded one times for each CS activity. The millimolar extinction coefficient of week at 8 a.m. for 14 weeks experimental period in DTNB is 14.1.The oxidation of reduced cytochrome c winter and summer groups. Ambient temperature, under by CCO was measured at 550 nm against a reference which animals of winter group were kept, revolves of 0.05 mmol l–1 cytochrome c oxidised with 50 µmol around about 10.5°C which ranged from 8°C.to l–1 K2F (CN) 6. The assays were performed in 100 15.0°C.,with mean 11.5±3.5°C .While ambient –1 –1 mmol l KH 2PO 4/K 2PO 4, pH 7.5 and 0.05 mmol l temperatures under which animals of summer group cytochrome c reduced with sodium hydrosulphide were kept, revolves around about 32.3°C and ranged

(Na2S2O 4). Excess sodium hydrosulphide was removed from 30.to 35°C, with mean 32.5±2.5°C. Mean weekly by bubbling air through the solution. The millimolar body temperatures of this lizard in winter 15.5± 0.9°C extinction coefficient of cytochrome c is 19.1. while, mean body temperatures in summer were 32.5±1.0°C table 1and3. Careful inspection of table Determination of Serum Enzymes: To determine the 1and3 would ultimately reveals that under ambient activity LDH; SC and CCO activity in serum used temperatures ranging from 8 to 15 °C in the winter (Sigma diagnostics kits for in vitro and enzymes group; cloacal temperature of Lizard ranged from activity calculated as (mmol-1 ). The activities of lactate 14.6°C to 16.4°C in winter group, and the body

75 J. Appl. Sci. Res., 5(1): 73-81, 2009

Table 1: We ekly averages of ambient, cloacal temperatures (°C), blood glucose, urea, sodium and osm olality (mmol-1) of lizard Umm El –Hyaait (Novoeumeces schneiderii) in winter and summer. weeks Ambient Cloacal Blood glucose Blood Urea Sodium Osmolality temperatures °C temperatures °C mmol/L mmol/L mmol/L mmol/L ------Winter Summer Winter Summer Winter Summer winter Summer Winter summer Winter Summer 1 8 30 14.6 31.5 6.8 10.1 2.6 2.9 154 130 319 273 ------2 8.5 30 15.1 32.1 6.8 10.1 3 3.2 153 130 317 273 ------3 8.5 30.5 16.2 32.6 6.8 10.2 3.3 3.4 152 130 314 273 ------4 8.5 30 16.3 32.3 6.9 10.3 3.3 3.5 151 131 312 276 ------5 9 30.2 15.4 32.5 7 10.4 3.4 3.6 150 132 310 278 ------6 9 31 15.4 32.7 7 10.5 3.5 3.7 149 133 309 280 ------7 10 32 15.4 32.9 7.1 10.6 3.6 3.8 148 134 307 283 ------8 10 32 15.6 32.9 7.1 10.7 3.6 3.9 147 133 305 281 ------9 10.5 33 15.8 33 7.1 10.8 3.7 3.9 145 134 301 283 ------10 11.5 34 15.9 33 7.2 10.8 3.6 3.9 144 133 299 282 ------11 13.5 33 15.8 33.1 7.3 10.9 3.7 3.8 143 135 297 281 ------12 13.5 33 15.9 33.2 7.3 11.1 3.6 3.9 142 135 295 281 ------13 13.5 35 16 33.4 7.4 11.2 36.6 3.8 141 135 293 285 ------14 15 35 16.1 33.5 7.6 11.3 3.8 3.9 140 136 291 287 Means ±SD 11.5±3.5 32.5±2.5 15.5±0.9 32.5±1.0 7.2±0.4 10.7±0.6 3.2±0.6 3.4±0.5 147.1 ±7 133 ±3 305 ±14 280±7 Each value represented the means of 10 individual animals.

Table 2: Weekly averages of values for each enzyme, Lactate dehydrogenase (LDH); Citrate synthase (CS) and Cytochrome oxidase (CCO) in muscle (units/g tissues weight) and blood (mm ol-l ) during winter and summer of lizard Umm El –Hyaait( Novoeumeces schneiderii). Weeks Lactate dehydogenase LDH Citrate synthase CS Cytochrome oxidase CCO ------Blood mmol/L Muscle Units/g Blood mmol/L Muscle Units/g Muscle mmol/L Muscle Units/g ------winter summer winter summer winter summer winter summer winter summer winter summer 1 70 500 404 95 0.4 5 5.5 0.6 0.5 2.3 2.1 0.6 ------2 75 506 420 100 0.4 5.1 5.6 0.6 0.5 2.3 2.1 0.7 ------3 80 508 425 120 0.5 5.4 5.5 0.63 0.6 2.3 2.2 0.8 ------4 85 510 450 125 0.6 5.5 5.8 0.7 0.6 2.4 2.2 0.9 ------5 90 515 480 135 0.6 5.6 5.9 0.8 0.6 2.5 2.3 0.8 ------6 94 518 490 140 0.7 5.7 6.1 0.8 0.7 2.6 2.4 1 ------7 95 520 495 140 0.8 5.8 6.2 0.9 0.8 2.8 2.5 1.2 ------8 98 525 500 145 0.9 5.9 6.3 0.9 0.9 2.9 2.5 1.2 ------9 98 529 500 146 0.9 5.9 6.4 1 0.8 3 2.6 1.3 ------10 100 530 510 150 0.8 6 6.6 1.1 0.9 3.1 2.7 1.4 ------11 102 540 515 156 1 6.1 6.8 1.2 1 3.3 2.8 1.4 ------12 104 550 520 158 1.1 6.3 6.8 1.3 1.1 3.4 2.9 1.4 ------13 105 546 530 160 1.2 6.4 6.9 1.3 1.2 3.4 2.9 1.3 ------14 116 548 566 185 1.2 7 7.1 1.3 1.3 3.5 2.8 1.6 Means ±SD 93 ± 23 525 ± 25 485 ±81 140 ± 45 0.8 ± 0.4 6.0 ±1 6.3 ±0.8 0.94 ±0.3 0.9 ±0.4 3 ± 0.7 2.5 ± 0.4 1.1 ±0.5 Each reading representing the means of ten animals

76 J. Appl. Sci. Res., 5(1): 73-81, 2009

Table 3: Means ±standard deviation of the parameters of lizard (Novoeumeces schneiderii) under winter and Summer temperatures and the student t-test of these parameters. Parameters Means ±Standard deviation Student-t- test Calculated ------Winter Summer Ambient temperatures °C 11.5±3.5 32.5±2.5 80.73** ------Cloacal temperatures °C 15.5 ±0.9 32.5 ±1 153.43** ------Glucose mmol/L 7.2 ±0.4 10.7 ±0.6 78.123** ------Urea mmol/L 3.2±0.6 3.4 ±0.5 10.617** ------Sodium mmol/L 147 ±7 133 ±3 7.906** ------Osmolality mmol/L 305 ±14 280 ±7 7.278** ------Lactate dehydrogenase in blood mmol/L 93 ±23 525 ±25 245.9** ------Lactate dehydrogenase in muscle units /g tissue 485 ±81 140 ±45 56.553** ------Citrate synthase in blood mmol/L 0.8 ±0.4 6 ±1 67.551** ------Citrate synthase in muscle units/g 6.3 ±0.8 0.94 ±0.3 71.089** ------Cytochrome oxidase in blood mmol/L 0.9 ±0.4 3 ±0.7 37.07** ------Cytochrome oxidase in muscle units/g 2.4 ±0.5 1.1 ±0.5 5.093** Degree of freedom =13, Each value represented as the means of 14 reading of 10 animals. (**) indicated that highly significant temperature increased in winter group from ambient hand, the changes in the activities of these enzyme temperature by 5±0.9°C. On the other hand, under exhibited a significant increase in the activities of all ambient temperatures ranging from 30 to 35°C in the three enzymes of muscle samples in winter group summer group; cloacal temperatures ranged from 31.5to than in summer group sample stable. 33.5°C. From statistical point there are highly It is of outmost physiological interest to note that significant decreased body temperatures in winter although ambient temperatures in winter group as low compared with body temperature in summer of this 8.5°C, and high 15°C, cloacal temperature- which lizard, and daily body temperatures fluctuated represents body core temperature- did not decrease significantly more in winter compared with summer. remarkably beyond about 14.6°C which seems to be the lower limit of body temperature range of change in Changes in Serum Osmolality Constituents: The winter group, and did not increased above 16.4°C, this results in Table (1and3) indicated that, highly observation defies the common concept that the body significant increased of blood osmolallity in winter temperature of ectothermic animals of which this lizard temperatures according to the increased of sodium is member-follows closely the prevailing ambient concentration while decreased of glucose and urea temperatures. Under high ambient temperature, compared with summer group. On the other hand, the however, ranging from 30 to 35°C, it was clear that results indicated that highly significant differences the body temperature of this lizard is quite closely. The decreased of blood osmolallity in summer temperatures results agree with Avery[5,7,34] they observed that according to the decreased of blood sodium reptiles often regulate their body temperature to attain concentration, while increased of blood glucose and the preferred body temperature and they attributed to urea compared with winter temperatures. increased metabolic heat production and the changes in circulation in winter group than summer group. The Change in Serum and Tissue Enzymes: The activities ability of ectotherm to attain or maintain particular of serum and tissues metabolic enzymes (Lactate body temperature is largely dependent upon its realized dehydrogenase (LDH); Citrate synthase (CS) and and potential rates of thermal exchange with Cytochrome C oxidase (CCO) in table(2and3) showed environment to reach the optimum temperature of the variability during winter than summer. The pattern of reptile for the physiological process. In the same miner, variation exhibited significant decreased in the Hertz et al.[23,12,3] . Reported that the notion of preferred activities of all three enzymes in blood of winter or selected body temperatures should be employed with group than in blood of summer group .On the other caution, because there may not be a single species

77 J. Appl. Sci. Res., 5(1): 73-81, 2009

–specific optimal body temperature. In addition the high osmolality and to upsetting the concentration present results in agreement with Guderley and St gradient between the body fluids and the environment, Pierre[2 1 ] found that many ectotherms change the low sodium and osmolality in summer group may biochemical capacities with seasonal acclimatisation or be occurs in the presence of a free intake water, in the thermal acclimation, and this ability may be the result activity of the lizard, thereby perform the important of their inability to compensate behaviorally for function of maintaining a constant osmolarity. If the environmental variation in homogeneous environments. osmolarity of plasma changes, it will affect the Our results also support the word by Seebacher and osmolarity of the tissue fluid and the cells will tend to Grigg[39] and Wilson and Franklin[49]. Seebacher et al.[42] shrink or smell and possibly burst. reported that body temperatures of ectotherms are often However, enzymes from all the principal energy- closely tied to environment temperature fluctuations, yielding pathways (glyolysis, gluconeogenesis, particularly to long-term, seasonal fluctuations as a tricarboxylic acid cycle, electron transport system, and result of the high rates of convective heat exchange in pentose shunt) have been identified in reptilian tissue environment. The results are conceivable, therefore, that .Although activities differ, reptiles exhibit a similar terrestrial ectotherms species experience seasonal general pattern of enzymatic distribution as do the fluctuations in body temperature and could gain similar other vertebrate classes. Enzymatic activities are ad vantages from biochemical /physio lo gical notorious for their sensitivity to condition of acclimatization and they are able to thermoregulate on preparation and analysis and cannot readily be a daily basis. In addition St Pierre and Boutilier[44] compared among different studies, few comparative reported that, metabolic acclimatisation may be investigations involving reptilian material haven been energetically expensive, used during increased rates of undertaken. The results indicated that metabolic transcription, so that the benefits of maintaining enzymes in blood of summer group are increased biochemical/physiological performance may by point to increased metabolism of this lizard, and this outweighed by the increased energetic costs, and increase of these metabolic enzymes may be released dormancy becomes the more advantageous response, from the muscle cells into the blood stream during particularly in extreme climates. activity of the lizard under summer temperatures The results indicated that when ambient .Another possible reason, at summer ,was the rutting temperature increased about thirty degrees centigrade in period ,which causes increased activity, high –glucose summer group, the osmolality of blood decreased in blood ,low-energy diet increased the urea according to the change of the items of blood concentration in the blood of the lizard ,in the summer osmolality. The increased in ambient temperatures the lizard high diet eaten food may have affected the group has activated the general and specific metabolism values in summer group and the high protein so that blood glucose and urea, were found increased catabolism that cause high urea in blood. The significantly of blood summer group, while sodium and differences in activity of the blood metabolic enzymes, osmolality decreased of this summer group compared an increase at summer followed by a decrease in with winter group. The increased in blood glucose winter, may be due to altered cell permeability in some concentration could be to the fact that, under activity organs containing it or changes in its overall induction (in summer group) conditions glucose is critically and release of metabolic enzymes from the muscles to needed in high concentrations as instaneous available the blood may have enhanced and increased activity, source of energy for intracellular metabolism. followed by increased use of metabolic enzymes ,thus Moreover, the modest increase in serum urea under increased protein catabolism in muscles, which resulted high ambient temperature group could be interpreted in elevated blood urea and excreted from the kidneys on bases that inspite of the tremendous increased in in summer group . protein metabolism producing urea ; prompt removal of The results show that during winter temperatures, this toxic material from circulating blood by efficient lizard capable of increasing the activity of muscle excretion maintained a fairly normal level of serum enzymes, presumably to compensate for the depressive urea under high ambient temperatures. On the other effect of lower body temperatures, with considerable hand, the observed noticeable decline of serum sodium subcutaneous fat stores. LDH is generally associated and osmolality under high ambient temperatures with cellular metabolic activity; such activity is comparing with group of low temperature. These inhibited under stress, especially temperatures. These results attributed to according to the fact that sodium data in agreement with Hertz et al.[23,12,3] they is the major cation of the extracellular fluid and interpreted increased muscle enzymes may have therefore the osmotic pressure of the extracellular is important implications for reptilian thermal physiology, largely governed by its sodium concentration leads to because acclimatisation of enzyme activity indicates

78 J. Appl. Sci. Res., 5(1): 73-81, 2009 that performance in reptiles may be less dependent on REFERENCES the animals attaining a `preferred' body temperature range than previously thought. Also the present study 1. Abd EL-Reheem, A.M.A., 2002. Effect of in accordance with those obtained by Christian Hibernation on some physiological parameters in andTracy[11,4,19,40,34] they reported that thermoregulation Uromastyx aegyptius. Al- Azhar. Bull.Sci., 13(1): in reptiles is often interpreted as the ability of animals 205-216. to behaviorally maintain near-constant body 2. Aleksiuk, M., 1971. An isoenzymic basis for temperatures in the face of biotic and abiotic instantaneous cold compensation in reptiles: constraints. The present study indicated, that it may not Lactate dehydrogenase kinetics in Thamnophiss be sufficient to base conclusions about there sirtalis. Comp. Biochem. Physiol., 40B: 671-681. cytochrome c oxidase activity more regulatory ability 3. Andrews, R.M., F.R. Méndez-de la Cruz, M. of reptiles entirely on behavioral patterns may be Villagrán-Santa Cruz and F. Rodriguez- Romero, tem p o rally co nfo und ed b ecause b io chem ical 1999. Field and selected body temperatures of the acclimatisation may change thermal optima. On the lizards Sceloporus aeneus and Sceloporus contrary, optimal body temperatures may be plastic and bicanthalis. J. Herpetol., 33: 93 -100. change with acclimatisation, reflecting a shift in the 4. Angilletta, M.J., 2001. Thermal and physiological thermal dependency of physiological processes, this constraints on energy assimilation in a widespread lizard (gold skind Umm El Haiyat). The results lizard (Sceloporus undulatus). Ecology, 82: indicated that significantly elevated in activity of citrate 3044-3056. synthase and cytochrome c oxidase in muscle of winter 5. Avery, R.A., 1979. Lizards- A study in lizards compared with in summer lizards at all study thermoregulation. Janim. Ecol., 40: 351-365. temperatures. The mechanisms responsible for the 6. Avery, R.A., 1982. Field studies of body acclimatisation response in mitochondrial enzymes temperatures and thermoregulation. In Biology of appear, therefore, to differ for citrate synthase and the Reptilia, vol. 12 (ed. C. Gans and F.H. Pough), cytochrome c oxidase. Citrate synthase in muscle 93-166. New York. Academic Press. explain the seasonal changes in activity marked 7. Bashandy, M.A., I.S. Kawashti, and A.M.A. Abd modifications of membrane lipids are known to occur El -Reheem, 1996. Influence of low and high during seasonal acclimatisation of ectotherms[22], and ambient temperatures on thermoregulation of a such changes are likely to modify the activity and poikilothermic and homoeothermic animals. J. thermal sensitivity of membrane-bound enzymes[45,21]. Egypt. Ger. Soc. Zool., Comparative physiology, An increase in enzyme concentration[32] or changes in 21A: 253-269. mitochondrial density and/or characteristics[45,21] could 8. Beall, R.J. and C.A. Privitera, 1973. Effects of also intervene. As for cytochrome c oxidase, the cold exposure on cardiac metabolism of the turtle activity of lactate dehydrogenase was significantly Chrysemys picta. Am. J. Physiol., 224: 411-435. elevated in winter animals, but lactate dehydrogenase 9. Bergmeyer, H.V., 1974. Methods of enzymatic analysis of glucose .Verlage chemic. Associated also had a greater Q 10 value in winter than in summer[42]. Aleksiuk[2] has measured the activity of press. New Yourk, 1192. lactate dehydrogenase in skeletal muscle from northern 10. Chauhan, N.B., 1987. Comparative account on the role of isocitrate dehydrogenase and malic enzyme and southern forms of the garter snake and reported in the pre anal gland metabolism of two lizards. J. that this enzyme from the northern animals displays a Anim. Morpl. Physio., 34: 99-106. compensatory shift below 20 which involves an 11. Christian, K.A. and C.R. Tracy, 1981. The effects increased affinity for the substrate ,but from the of the thermal environment on the ability of southern animals show a similar shift below 28 ºc, hatchling Galapagos land iguanas to avoid which in this case is caused by a decreased in predation during dispersal. Oecologia, 49: 218-223. activation energy at low temperatures and believes that 12. Christian, K.A. and B.W. Weavers, 1996. the thermal shifts in total LDH activity are able due to Thermoregulation of monitor lizards in Australia: differing subunit activities. Beall and Privitera[8] found an evaluation of methods in thermal biology. Ecol. that an increased affinity between enzyme and substrate Monogr., 66: 139 -157. with decreasing temperature for cardiac lactate 13. Costanzo, J.P., J.D. Litzgus, J.B. Iverson and R.E. dehydrogenase in turtle, such relationships tend to Jr. Lee, 2000. Seasonal changes in physiology and counteract thermal effects on velocity, resulting in development of cold hardiness in the hatchling relatively stable rates of enzymatic catalysis over a painted turtle Chrysemys picta. J. Exp. Biol., 203: wide thermal range. It is conceivable therefore, that 3459 -3470. terrestrial reptiles experience seasonal fluctuations in 14. Crawford, D.L., V.A. Pierce and J.A. Segal, 1999. body temperature and could gain similar advantages Evolutionary physiology of closely related Taxa: from biochemical acclimatisation despite the fact that analyses of enzyme expression. Am. Zool., 39: they are able to thermoregulation a daily basis. 389-400.

79 J. Appl. Sci. Res., 5(1): 73-81, 2009

15. Crawford, D.L. and D.A. Powers, 1992. 29. Norton, S.F., Z. Eppley and B.D. Sidell, 2000. Evolutionary adaptation to different thermal Allometric scaling of maximal enzyme activities in environments via transcriptional regulation. Mol. the axial musculature of striped bass, Morone Biol. Evol., 9: 806-813. saxatillis (Walbaum). Physiol. Biochem. Zool., 73: 16. Fields, P.A. and G.N. Somero, 1997. Amino acid 819 -828. sequence differences cannot fully explain 30. Olson, J.M., 1987. The effects of seasonal interspecific variation in thermal sensitivities of acclimatization on metabolic-enzyme activities in gobiid fish A4-lactate dehydrogenases (A4-LDHS). the heart and pectoral muscle of painted turtles J. Exp. Biol., 200: 1839 -1850. Chrysemys picta marginata. Physiol. Zool., 60: 17. Grant, B.W., 1990. Trade-offs in activity time and 149 -158. physiological performance for thermoregulating 31. Patton C.J. and C.R. Crouch, 1977. Anal Chem. desert lizards, Sceloporus merriami. Ecology, 71: 49: cited from pamphlet of urea determination kit. 2323 -2333. 32. Pierce V.A. and Crawford D.L. (1997). Phylogenetic analysis of glocolytic enzyme 18. Grant, B.W. and A.E. Dunham, 1988. Thermally expression. Science 275: 256 -259. imposed time constraints on the activity of the 33. Saber, S.A., 1989. Ecological studies on reptiles desert lizards, Sceloporus merriami. Ecology, 69: from the Eastern desrt .Ph.D Thesis, Faulty of 167 -176. science Al Azhar University, Egypt. 19. Grbac, I. and D. Bauwens, 2001. Constraints on 34. Saber, S.A. and A.M.A. AbdEl-Reheem, 2003. temperature regulation in two sympatric Podarcis Ecophysiological means of thermoregulation of lizards during autumn. Copeia, 2001: 178 -186. montepelier snake, Malpolon monspessulana, from 20. Grigg, G.C., F. Seebacher, L.A. Beard and D. El Burullus protected area, Egypt. Al- Azhar Morris, 1998. Thermal relations of very large Bull.of Science Proceeding of 5th int.Sci.Conf. crocodiles, Crocodylus porosus, free-ranging in a March: 333-344. naturalistic situation. Proc. R. Soc. Lond. B., 265: 35. Saleh, M.A., 1997. Amphibians and reptiles of 1793 -1799. Egypt. Publication national Biodiversity Unit no. 6. 21. Guderley, H. and J. St. Pierre, 2002. Going with 36. Scheiner, S.M., 1993. Genetics and evolution of the flow or life in the fast lane: contrasting phenotypic plasticity. Ann. Rev. Ecol. Syst., 24: mitochondrial responses to thermal change. J. Exp. 35-68. Biol., 205: 2237-2249. 37. Seebacher, F., 1999. Behavioural postures and the 22. Hazel, J.R., 1995. Thermal adaptation in biological rate of body temperature change in wild freshwater membranes: Is homeoviscous adaptation the crocodiles, Crocodylus johnstoni. Physiol. explanation? Annu. Rev. Physiol., 57: 19 -42. Biochem. Zool., 72, pp. 57-63. 23. Hertz, P.E., R.B. Huey and R.D. Stevenson, 1993. 38. Seebacher, F. and C.E. Franklin, 2001. Control of Evaluating temperature regulation by field active heart rate during thermoregulation in the ectotherms: the fallacy of the inappropriate heliothermic lizard Pogona barbata: importance of question. Am. Nat., 142: 796 -818. cholinergic and adrenergic mechanisms. J. Exp. 24. Huey, R.B., 1982. Temperature, physiology, and Biol., 204: 4361 -4366. the ecology of reptiles. In Biology of the Reptilia, 39. Seebacher, F. and G.C. Grigg, 1997. Patterns of 12(ed. C. Gans and F. H. Pough): 25-91. New body temperature in wild freshwater crocodiles, York: Academic Press. Crocodylus johnstoni: thermoregulation versus 25. Johnston, I.A. and G.K. Temple, 2002. Thermal thermoconformity, seasonal acclimatisation, and the plasticity of skeletal muscle phenotype in effect of social interactions. Copeia, 549 -557. ectothermic vertebrates and its significance for 40. Seebacher, F. and G.C. Grigg, 2001. Social interactions compromise thermoregulation in locomotory behaviour. J. Exp. Biol., 205: crocodiles Crocodylus johnstoni and Crocodylus 2305-2322. porosus. In Crocodilian Biology and Evolution (ed. 26. Kaplan, H.M. and E.H. Timmons, 1976. Blood G.C. Grigg, F. Seebacher and C.E. Franklin), 310- chemistry in frogs and Turtles. Aad.Sec., 69(1): 316. Chipping Norton: Surrey Beatty and Sons. 108-113. 41. Seebacher, F., G.C. Grigg and L.A. Beard, 1999. 27. Lin, J. and G.N. Somero, 1995. Thermal adaptation C r o c o d i l e s a s d i n o s a u r s : b e h a v i o u r a l of cytoplasmic malate dehydrogenases of eastern thermoregulation in very large ectotherms leads to pacific barracuda (Sphyraena spp): the role of high and stable body temperatures. J. Exp. Biol., differential isoenzyme expression. J. Exp. Biol., 202: 77 -86. 198: 551-560. 42. Seebacher, F., H. Guderley, R.M. Elsey and P. 28. Lovegrove, B.G., G. Heldmaier and T. Ruf, 1991. Trosclair, 2003. Seasonal acclimatisation of muscle Perspectives of endothermic revisited: the metabolic enzymes in a reptile (Alligator endothermic temperature range. J. Therm. Biol., mississippiensis). J. Experimental biology, 206: 15: 185-197. 1193-1200.

80 J. Appl. Sci. Res., 5(1): 73-81, 2009

43. Sokal, R.R. and F.J. Rahif, 1981. The principles 47. Voet, D. and J.G. Voet, 1995. Biochemistry. New and practice of statistics in biological research 2nd York: Wiley and Sons. ed. Freean. W. company san Franciso. 48. Walmsley, R.N. and G.H. White, 1994. Text book 44. St Pierre, J. and R.G. Boutilier, 2001. Aerobic of A guide to diagnostic clinical chemistry .third capacity of frog skeletal muscle during hibernation. Physiol. Biochem. Zool., 74: 390-397. edition. Oxford Blackwell scientific publications. 45. St Pierre, J., P.M. Charest and H. Guderley, 1998. 20-49. Relative contribution of quantitative and qualitative 49. Wilson, R.S. and C.E. Franklin, 2000. Inability of changes in mitochondria to metabolic compensation adult Limnodynastes peronii (Amphibia: Anura) to during seasonal acclimatisation of rainbow trout thermally acclimate locomotor performance. Comp. Oncorhynchus mykiss. J. Exp. Biol., 201: Biochm. Physiol., A 127: 21-28. 2961-2970. 50. Wilson, R.S. and C.E. Franklin, 2002. Testing the 46. Taylor, R.W. and E.R. Jacobson, 1982. Hematology and serum chemistry of the Gopher beneficial acclimation hypothesis. Trends Ecol. Tortosise, Comp. Biochem., 72(2): 425-428. Evol., 17: 66-70.