1H-NMR study of the metabolome of an exceptionally anoxia tolerant vertebrate, the crucian carp (Carassius carassius)

The crucian carp (Carassius carassius) can tolerate anoxia for days to months, depending on the temperature. In this study, we applied ¹H-NMR-based metabolomics to polar extracts of crucian carp brain, heart, muscle and liver samples obtained from fish exposed to either control normoxic conditions, acute anoxia (24 h), chronic anoxia (1 week) or reoxygenation (for 1 week following chronic anoxia) at 5 °C. Spectra of the examined tissues revealed changes in several energy-related compounds. In particular, anoxic stress resulted in decreased concentrations of phosphocreatine (muscle, liver) and glycogen (liver) and ATP/ADP (liver, heart and muscle) and increased concentrations of lactate (brain, heart, muscle) and beta-hydroxybutyric acid (all tissues). Likewise, increased concentrations of inhibitory compounds (glycine, gamma-amino butyric acid or GABA) and decreased concentrations of excitatory metabolites (glutamate, glutamine) were confirmed in the anoxic brain extracts. Additionally, a decrease of N-acetylaspartate (NAA), an important neuronal marker, was also observed in anoxic brains. The branched-chain amino acids (BCAA) valine/isoleucine/leucine increased in all anoxic tissues. Possibly, this general tissue increase can be due to an inhibited mitochondrial function or due to protein degradation/protein synthesis inhibition. In this study, the potential and strength of the ¹H-NMR is highlighted by the detection of previously unrecognized changes in metabolites. Specifically, myo-inositol substantially decreased in the heart of anoxic crucian carp and anoxic muscle tissue displayed a decreased concentration of taurine, providing novel insights into the anoxia responses of the crucian carp.     

Metallothionein-bound cadmium in the gut of the insect Orchesella cincta (Collembola) in relation to dietary cadmium exposure

Metallothionein is considered to be a potential biomarker for heavy metal exposure in the terrestrial environment. However, limited information is available on metallothioneins from insects, a major class of terrestrial invertebrates. In this study we have quantified metallothioneins in the springtail Orchesella cincta by determining metallothionein-bound cadmium after separation of these proteins using gel filtration and reversed phase chromatography from total body homogenates of animals dietary exposed to different concentrations of cadmium. Furthermore, we have studied in more detail where cadmium and metallothionein-bound cadmium is located within this animal. The concentration of metallothionein-bound cadmium increases with the exposure concentration in the same way as the total internal concentration. Both reach a plateau at an exposure concentration of approximately 1.0 μmol Cd/dry food. Cadmium is primarily located within the gut of O. cincta and isolation of metallothionein from this organ gives results identical to isolations from total bodies. Based on this results an estimation of the metallothionein level at the highest exposure concentration results in a concentration of about 115 μg metallothionein/g fresh gut. The O. cincta metallothionein gives the possibility of using this protein as a biomarker for heavy metal exposure in soil insects.     

Effects of subchronic alternating cadmium exposure on dopamine turnover and plasma levels of prolactin, GH and ACTH

This study was undertaken to analyze if the effects of subchronic alternating cadmium exposure on pituitary hormone secretion are mediated by changes in dopamine turnover in an age dependent way or are directly correlated to cadmium accumulation at the hypothalamic-pituitary axis. Male rats were treated sc. from day 30 to 60 (prepubertal period) or from day 60 to 90 (adult age) of life, with cadmium chloride (CdCl₂) at a dose of 0.5 and 1.0 mg kg^–1 bw, every 4th day in an alternate schedule, starting with the smaller dose. Dopamine (DA) turnover, expressed as the ratio of acid 3,3-dihidroxifenil acetic (DOPAC)/DA in various hypothalamic areas, the plasma levels of prolactin, growth hormone (GH) and adrenocorticotropic hormone (ACTH), and cadmium accumulation in the hypothalamus and pituitary were studied. Prepubertal cadmium exposure decreased DA content in all hypothalamic areas studied, although its turnover was not modified. A decrease in plasma ACTH levels with no changes in plasma prolactin and GH levels were found. Cadmium did not accumulate in pituitary while it increased in the hypothalamus. Metal exposure during adulthood decreased DA content in mediobasal and posterior hypothalamus, and its turnover in posterior hypothalamus and median eminence. It decreased plasma prolactin and ACTH levels but not those of GH. Cadmium concentration increased in both hypothalamus and pituitary. These results suggest that cadmium exposure produces age dependent changes on the secretory mechanisms of the pituitary hormones studied, related to the selective accumulation of the metal at both hypothalamic and hypophyseal level changes. However the effects of the metal are not mediated by dopamine.     

1H-NMR study of the metabolome of a moderately hypoxia-tolerant fish, the common carp (Cyprinus carpio)

All 20.000 different fish species vary greatly in their ability to tolerate and survive fluctuating oxygen concentrations in the water. Especially fish of the genus Carassius, e.g. the crucian carp and the goldfish, exhibit a remarkable tolerance to limited/absent oxygen concentrations. The metabolic changes of anoxia-tolerant crucian carp were recently studied and published. Contrary to crucian carp, the hypoxia-tolerant common carp cannot survive a complete lack of oxygen (anoxia). Therefore, we studied the ¹H-NMR-based metabolomics of brain, heart, liver and white muscle extracts of common carp, subjected to anoxia (0 mg O₂ l^?1) and hypoxia (0.9 mg O₂ l^?1) at 5 °C. Specifically, fish were exposed to normoxia (i.e. 9 mg O₂ l^?1; controls 24 h, 1 week and 2 weeks), acute hypoxia (24 h), chronic hypoxia (1 week) and chronic hypoxia (1 week) with normoxic reoxygenation (1 week). Additionally, we also investigated the metabolic responses of fish to anoxia for 2 h. Both anoxia and hypoxia significantly changed the tissue levels of standard energy metabolites as lactate, glycogen, ATP/ADP and phosphocreatine. Remarkably, anoxia induced increased lactate levels in all tissues except for the heart whereas hypoxia resulted in decreased lactate concentrations in all tissues except for brains. Furthermore, hypoxia and anoxia influenced amino acids (alanine, valine/(iso)leucine) and neurotransmitters levels (GABA, glutamate). Lastly, we also detected ‘other’ i.e. previously not reported compounds to play a role in the present context. Scyllo-inositol levels changed significantly in heart, liver and muscle, providing novel insights into the anoxia/hypoxic responses of the common carp.     

Bioremediation of cadmium induced renal toxicity in Rattus norvegicus by medicinal plant Catharanthus roseus

Cadmium is the second most hazardous metals with bio-concentration factor (BCF)?>?100 Although WHO permitted cadmium concentration in drinking water is 0.005?mg/L, yet the reality is far above to this limit because of industrial utility of this metal. Oral exposure of cadmium to human results in dreadful symptoms of metabolic disorders especially in liver and kidneys. Endogenous protection could be supported by some exogenous herbal supplement (viz., Catharanthus roseus in this case) to overcome the toxic effects. Present Study has been designed to find out the functional renal changes under the effect of cadmium and Catharanthus roseus in the model organism albino rats. Cadmium significantly (p?>?0.01) increases the level of nitrogenous waste (Urea, BUN, Uric Acid and Creatinin), while decreases the serum protein profile in acute and sub-acute sets. Urea concentration of control ranged from 16.56 to 17.72?mg/dl while that of Group-B and D were 19.84 to 20.87?mg/dl and 17.56 to 17.59?mg/dl respectively. Similarly uric acid concentration ranged in control form 6.98 to 8.01?mg/dl in group-B from 7.58 to 10.25?mg/dl, in Group-D 8.02 to 8.59?mg/dl respectively. Creatinin concentration ranged in control 0.57 to 0.65?mg/dl, in group-B 0.97 to 1.02?mg/dl, in group-D – 0.95 to 0.98?mg/dl respectively.These results might be due to altered filtration rate of kidney because of protein disruption. The studies conclude the efficient nephro-protection offered by Catharanthus roseus extract against Cadmium toxicity.     

Heavy metal intracellular balance and relationship with metallothionein induction in the liver of carp after contamination by silver,cadmium and mercury following or not pretreatment by zinc

Determination of metal levels (copper, zinc, cadmium, silver and mercury) in soluble and insoluble fractions of liver homogenates has been performed after 7 days exposure of carps (Cyprinus carpio) to moderate concentrations of cadmium, silver and mercury in water. Metallothionein (MT) levels have been quantified by a polarographic method before and after the contamination and a subsequent decontamination phase (7 days). The influence of pretreatment by zinc (7 days) has also been evaluated. MT level variations have been interpreted as having regard to inter-related flows of metal between subcellular fractions. Special interest has been focused on heat-stable compound (HSC)-bound heavy metal flows within the cytosol, taking in account that MT is the major component of these ligands. Our data showed differences between the ability of metals to bind cytosolic ligands and HSCs, and their respective potency for MT induction in liver. Regardless of pretreatment, mercury gave the highest increase of liver MT, but the MT level decreased during the decontamination step, especially after pretreatment by zinc. Cadmium and silver gave similar increases, but a significant difference with the control appeared only after the decontamination step with cadmium, while 1 week of contamintion was enough for silver. However, silver binding with MT was achieved only by the end of the decontamination step, while cadmium depicted the highest ratio for HSC-bound toxic metals after the contamination. Our experimental conditions gave the following order of potency for MT induction in liver: mercury silver > cadmium > zinc. Results are discussed comparatively with data obtained with carp gills.     

Changes in ultrastructure and cytochemistry of the agarophyte Gracilaria domingensis (Rhodophyta, Gracilariales) treated with cadmium

The agarophyte macroalgae Gracilaria domingensis (Kützing) Sonder ex Dickie is widely distributed along the Brazilian coast. While this species produces agarana, it is more important in the human diet. Therefore, the present study aimed to evaluate the biological effects of cadmium on its morphology and cellular organization. To accomplish this, the effects of cadmium in apical segments of G. domingensis were examined in vitro. Over a period of 16 days, the segments were cultivated and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m^?2 s^?1, with cadmium treatments in doses of 100, 200 and 300 μM. The samples were processed for light, transmission and scanning electron microscopy. Histochemical analyses included Toluidine Blue for acidic polysaccharides, Coomassie Brilliant Blue for total protein, and Periodic Acidic Schiff for neutral polysaccharides. In all cadmium treatments, cytochemical analysis showed 1) metachromatic granulation in vacuole and lenticular thickness of the cell wall, 2) a higher concentration of cytoplasmic organelles, and 3) an increase in the number of floridean starch grains. Cadmium also caused changes in the ultrastructure of cortical and subcortical cells, including increased cell wall thickness and vacuole volume, as well as the destruction of chloroplast internal organization and increased number of plastoglobuli. In addition, treated plants showed a gradual increase in surface roughness, apparently the result of cadmium absorption. Taken together, these findings strongly suggested that cadmium negatively affects the agarophyte G. domingensis, posing a threat to the vitality of this plant species as a supplement in the human diet.     

Short-term low-salinity response in lead-exposed lobsters, Homarus americanus (Milne Edwards)

The only effect attributable solely to lead exposure (50μg·l^?1, 30 days) in lobsters, Homarusamericanus (Milne Edwards), was decreased pentose shunt activity (G6PDH) in the antennal gland, which contained the greatest concentration of lead taken up by the tissues analyzed. Similarly-exposed lobsters were subsequently held for 2 days in clean, aerated sea water at either ambient or low salinity (27 or 17%., respectively), after which time the lead concentration in the antennal gland had dropped by one-third and G6PDH had returned to control values. Low-salinity effects far outnumbered lead-induced effects and were found primarily in the tail muscle, corroborating findings in an earlier study with cadmium. In that earlier study, cadmium produced more metabolic disturbance than did the lead exposure reported here. Lead exposure at low salinity abolished several normal hyposaline reactions seen in control animals.     

Cytochemical study of carp neutrophil granulocytes after acute exposure to cadmium

The aim of this study was determination of metabolical changes in neutrophil granulocytes of common carp (Cyprinus carpio L.) after acute exposure to cadmium chloride. Cytochemical examination of neutrophil granulocytes was performed on 20 control and 20 experimental specimens of 1‐ to 2‐year‐old common carp after 96 h of exposure to cadmium chloride in a concentration of 12.5 mg L^?1. We detected an increase of glycogen and lipid content and a decrease of peroxidase and alkaline phosphatase content in neutrophil granulocytes of the experimental group of carp when compared with the control group.     

Experimental studies on the cadmium accumulation in the cestode Moniezia expansa (Cestoda: Anoplocephalidae) and its final host (Ovis aries)

The tapeworm Moniezia expansa and naturally infected sheep were investigated with respect to their cadmium accumulation. Cadmium chloride (CdCl₂, 0.2 g) was added to 10 ml of distilled water and administered orally to the sheep every day for a period of 1 week. The cadmium content of M. expansa was lower than that in the liver tissues of sheep, although this difference was not significant. The highest mean cadmium concentrations were found in the liver of sheep infected with M. expansa (24.5 ± 11.5 mg kg⁻¹ dry weight). The mean cadmium concentration measured in M. expansa was 21.5 ± 19.2 mg kg⁻¹ dry weight, which was 31 and 1.5 times higher than levels determined in the muscle and kidney of the host, respectively, but 0.9 times lower than levels determined in the liver of host. Sheeps with M. expansa infection always had higher cadmium concentrations in the tissues (with the exception of the blood) than their uninfected conspecifics.     

Exposure-dose-response of Tellina deltoidalis to metal-contaminated estuarine sediments: 1. Cadmium spiked sediments

Cadmium is a ubiquitous environmental metal contaminant with an affinity for biological membranes; it can enter cells by facilitated transport and it binds therein to various biomolecules and affects membrane system function. The relationship between cadmium exposure, dose and response was investigated in the benthic, deposit feeding, marine bivalve Tellina deltoidalis, using 28 day microcosm spiked cadmium exposures. Tissue cadmium reached steady state with the exposure concentration. Half the accumulated cadmium was detoxified and with increased exposure more was converted into metal rich granules. Most biologically active cadmium was in the mitochondrial fraction, with up to 7320-fold cadmium increases in exposed organisms. Cadmium exposed T. deltoidalis generally had reduced glutathione peroxidase enzyme activity. An increase in total glutathione concentrations, due to a build up of oxidised glutathione, was indicated by the reduced to oxidised glutathione ratio. All cadmium exposed T. deltoidalis had reduced total antioxidant capacity that corresponded with increased lipid peroxidation, lysosomal destabilisation and micronuclei frequency. Clear exposure-dose-response relationships have been demonstrated for T. deltoidalis exposed to cadmium-spiked sediments, supporting this organism's suitability for laboratory or in situ evaluation of sediment cadmium toxicity.     

Water pH and metabolic parameters in silver catfish (Rhamdia quelen)

This study evaluated the effects of an acute change in water pH (from pH 7.5 to 4.0, 5.0, 6.0, 7.5, 8.0 or 9.0) on several biochemical parameters in juveniles of the silver catfish, Rhamdia quelen. Ammonia levels decreased in the liver and increased in the muscle with increasing water pH. In the kidney, lower ammonia levels were observed at neutral pH. An increase in water pH decreased the glucose, glycogen and lactate levels in the liver and kidney (except for glycogen levels in the kidney and lactate levels in the liver, which presented lower levels at neutral pH). In muscle, the glucose and glycogen levels decreased with increasing water pH, whereas lactate levels tended to be lower at neutral pH. Gill and kidney Na⁺/K⁺-ATPase activities tended to increase in alkaline water, and the highest value was observed in fish exposed to pH 9.0. The optimal levels of the analyzed biochemical parameters occurred at neutral pH. In conclusion, exposure to acidic and alkaline pH changes the metabolic parameters of silver catfish as well as gill Na⁺/K⁺-ATPase activity.     

Inhibitory effects of cadmium on carbonic anhydrase activity and ionic regulation of the estuarine crab Chasmagnathus granulata (Decapoda,Grapsidae)

This work was aimed at evaluating the gill carbonic anhydrase (CA) activity of the estuarine crab Chasmagnathus granulata exposed in vivo to cadmium, at different salinities. The in vivo effect of the specific inhibitor acetazolamide (AZ) was also assayed. Besides, the inhibition of CA activity by different heavy metals (cadmium, copper, zinc) and AZ were evaluated under in vitro conditions. For the in vivo assays, adult males were acclimated to salinities of 2.5 or 30‰. The corresponding 96-h LC₅₀ of cadmium was 2.69 mg l⁻¹ at 2.5‰, and >50 mg l⁻¹ at 30‰. Cadmium only caused a significant lower CA activity than control at 2.5‰. EC₅₀ for CA inhibition was estimated to be 1.59 mg l⁻¹ at 2.5‰. Statistical differences in Na⁺ hemolymphatic levels (P<0.05) were only detected at 2.5‰, between 0 and 1.25 mg l⁻¹ of cadmium, but no statistical differences were observed for Cl⁻ levels at any assayed salinity. As CA inhibition registered at 2.5‰ was followed by only changes in Na⁺ concentration, it is likely that cadmium exposure could differentially affect ions permeability, among others factors. The concentrations that inhibited in vitro 50% of enzymatic activity (IC₅₀) were 2.15×10⁻⁵, 1.62×10⁻⁵, 3.75×10⁻⁶ and 4.4×10⁻¹⁰ M for cadmium, copper, zinc and AZ, respectively. The comparison with IC₅₀ values of other aquatic species, indicates a higher CA sensitivity for C. granulata to pollutants.     

Cadmium effects on dopamine turnover and plasma levels of prolactin, GH and ACTH

This paper analyzes possible dopamine (DA) mediated cadmium effects on plasma levels of prolactin, growing hormone (GH) and adrenocorticotropic hormone (ACTH), and if these changes are related to metal accumulation. For that purpose, adult male rats were treated with 50 mg/L of CdCl₂ in the drinking water for one month. Plasma levels of prolactin, ACTH and GH were measured by specific double antibody radioimmunoassays. DA was measured by high performance liquid chromatography using electrochemical detection. Cadmium content in the tissues was measured by atomic absorption spectometry with graphite furnace. Analysis was performed by using a T-Student test. Metal exposure increased DA content (34.79±3.06vs. 18.2±2.88 pg/mg protein) and decreased its turnover (0.40±0.07vs. 0.75±0.06) in posterior hypothalamus. Cadmium also decreased DA turnover in median eminence (0.48±0.15vs. 1.50±0.63). Plasma levels of prolactin and GH decreased (2.4±0.11vs. 3.1±0.15 ng/mL and 5.37±0.05vs. 9.87±1.8 ng/mL respectively), while those of ACTH increased (2.73±0.14vs. 1.7±0.16 ng/mL). Cadmium concentration increased in both hypothalamus (4.88±0.34vs. 0.72±0.2 μg/g) and pituitary (22.82±4.57vs. 5.02±1.25 μg/g) after the metal exposure. These results suggest that cadmium effects on the secretion of these hormones are not mediated by dopamine and might be correlated to the metal accumulation at pituitary level.     

Low-salinity stress in the American lobster,Homarus americanus,after chronic sublethal exposure to cadmium: Biochemical effects

Lobsters(Homarus americanus) were exposed to cadmium (6μg l⁻¹, 30 days) in flowing seawater, then held for 7 days in aerated “clean ” seawater at either ambient (27 ‰) or low (17 ‰) salinity. Cadmium exposure alone (ambient salinity) induced a general elevation of enzyme activity (heart, antennal gland, and muscle MDH; heart LDH and GPI), despite the probability of some clearance of cadmium from body tissues during the “clean ” seawater holding period. Low-salinity alone (non-exposed lobsters) caused a decrease of enzyme activity (AAT, LDH, GPI, PK) in most tissues examined, except for tail muscle IDH, the activity of which was increased, and MDH, which was significantly elevated above ambient controls in all tissues except heart. Most low-salinity effects were observed in tail muscle, and most cadmium effects, in heart; low-salinity effects outnumbered cadmium stress by nine to four. In heart and tail muscle of cadmium-exposed lobsters held at low salinity, each of the two stresses apparently operated to nullify the other's effects. The most prominent single biochemical response to these sublethal stresses was the elevation of MDH activity. The ratio MDH: LDH gave the clearest indication of overall relative stress.     

Cadmium: tissue distribution and binding protein induction in the painted turtle, Chrysemys picta

The freshwater painted turtle, Chrysemys picta, was used to investigate (a) the distribution of an injected dose of ¹⁰⁹Cd in tissues over a period of 192 h (8 days) and (b) the effect of non-isotopic cadmium injection on tissue metal-binding protein levels. Cadmium is cleared from the blood with 9% remaining in the circulation at 192 h. ¹⁰⁹Cd is found in all tissues, but is accumulated preferentially in liver, kidney, pancreas, and gastrointestinal tract. The liver is the primary site of Cd accumulation, accounting for 46.4% of the injected dose by 192 h and the highest Cd concentration (cpm/mg tissue). Steroidogenic tissues and the oviduct accumulate significant amounts of ¹⁰⁹Cd and the isotope is present in yolk. An increase in tissue metal-binding protein level after non-isotopic CdCl₂ injection is consistent with ¹⁰⁹Cd distribution, in that metal-binding protein concentration after CdCl₂ injection is highest in liver, followed by pancreas and kidney with low, but with significant levels of cadmium-binding protein in gonads and steroid target organs. We conclude that the liver is the major site of storage after a single injection of isotopic cadmium and induction of a metal-binding protein may be an adaptive response to exposure to cadmium.     

Cadmium effects and accumulation in cultures ofProrocentrum micans (dinophyta)

Effects and accumulation of cadmium were studied in unialgal 10-1 batch-culture experiments with the dinoflagellateProrocentrum micans Ehrenberg. Tests were made using sterile filtered North Sea water enriched with nitrate and phosphate only in order to avoid disturbances by complex formation. Cadmium was added to the cultures in amounts of 100 to 0.13μg l⁻¹. In one series it was added at the start of the experiments and in a second one after a growth period of 1 week. Addition of only 1.2μg Cd l⁻¹ reduces multiplication rates and maximum cell densities of the algae. Not until 0.4μg Cd⁻¹ does growth correspond to that of the controls. Cadmium concentrations were measured, after filtration, in the culture medium and in the biomass by means of flameless AAS. The cadmium content in algae increased from 2.7μg g⁻¹ (dry weight) in controls to 500μg g⁻¹ (dry weight) in media containing 100μg Cd l⁻¹. Uptake occurred rapidly during the first few days of the experiments, slowed down somewhat during exponential growth stage, and increased during decay of the cultures. Cadmium content of culture media remained nearly constant (Series 1) or decreased only slowly during experimental time (Series 2). The highest concentration factor was measured in the controls. It decreased with increasing metal concentration in the medium and increased with experimental time. Structural modifications of the cells were visible after Lugol fixation only, indicating brittleness of the cell walls.P. micans has shown to be extremely sensitive to cadmium and to accumulate this metal.     

Oral cadmium exposure throughout puberty does not inhibit secretion of prolactin, GH and ACTH through dopamine metabolism changes in male rat

This work analyzed possible dopamine-mediated cadmium effects on plasma prolactin, GH and ACTH levels and if these changes were related to metal accumulation. Male rats were treated from day 30 to 60 of life with 50 mg/L of CdCl₂ in the drinking water. Cadmium exposure decreased the dopamine (DA) metabolism (DOPAC/DA ratio) in all brain areas studied, and plasma levels of prolactin, GH and ACTH were diminished. The cadmium concentration did not increase nor in hypothalamus nor in the pituitary after the metal exposure. These results suggest that cadmium inhibits the secretion of these pituitary hormones and this inhibitory effect is not mediated by dopamine or the degree of metal accumulation.     

Threonine Affects Intestinal Function,Protein Synthesis and Gene Expression of TOR in Jian Carp (Cyprinus carpio var. Jian)

This study aimed to investigate the effects of threonine (Thr) on the digestive and absorptive ability, proliferation and differentiation of enterocytes, and gene expression of juvenile Jian carp (Cyprinus carpio var. Jian). First, seven isonitrogenous diets containing graded levels of Thr (7.4–25.2 g/kg diet) were fed to the fishes for 60 days. Second, enterocyte proliferation and differentiation were assayed by culturing enterocytes with graded levels of Thr (0–275 mg/l) in vitro. Finally, enterocytes were cultured with 0 and 205 mg/l Thr to determine protein synthesis. The percent weight gain (PWG), specific growth rate, feed intake, feed efficiency, protein retention value, activities of trypsin, lipase and amylase, weights and protein contents of hepatopancreas and intestine, folds heights, activities of alkaline phosphatase (AKP), γ- glutamyl transpeptidase and Na⁺/K⁺-ATPase in all intestinal segments, glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities in hepatopancreas, and 4E-BP2 gene expression in muscle, hepatopancreas and intestinal segments were significantly enhanced by Thr (p<0.05). However, the plasma ammonia concentration and TOR gene expression decreased (p<0.05). In vitro, Thr supplement significantly increased cell numbers, protein content, the activities of GOT, GPT, AKP and Na⁺/K⁺-ATPase, and protein synthesis rate of enterocytes, and decreased LDH activity and ammonia content in cell medium (p<0.05). In conclusion, Thr improved growth, digestive and absorptive capacity, enterocyte proliferation and differentiation, and protein synthesis and regulated TOR and 4E-BP2 gene expression in juvenile Jian carp. The dietary Thr requirement of juvenile Jian carp was 16.25 g/kg diet (51.3 g/kg protein) based on quadratic regression analysis of PWG.     

Effects of acute exposure to cadmium (II) chloride and lead (II) chloride on the haematological profile of Oreochromis aureus (Steindachner)

1. Oreochromis aureus (Steindachner) was exposed to two concentrations of lead and cadmium for 24 hr and 1 week to assess the effects of these pollutants on haematological parameters.2. Plasma osmolality was found to be the most sensitive blood parameter, affected before other parameters changed.3. Cadmium appears to be more toxic to O. aureus than lead, having an adverse effect on blood parameters earlier than lead.4. In the earlier stages of toxicity cadmium appears to have a more pronounced effect on haemoglobin concentration than lead.5. Cadmium does not depress erythrocyte counts but lead does.