Dietary ascorbic acid deficiency in guinea pigs: No effect on ethanol preference,spiroperidol binding,or monoamine oxidase activity

Ascorbic acid levels are commonly reported to be decreased in alcoholics. Although this deficiency could be due to dietary factors, there is evidence that ascorbic acid may be involved in the metabolism and acute effects of ethanol, possibly related to the pathogenesis of alcoholism. Therefore, we examined ethanol preference in guinea pigs receiving an ascorbate deficient $\text{vs}$ a normal diet. Brain and spleen ascorbic acid levels were dramatically decreased, but ethanol preference was not altered by the acute dietary deficiency of this vitamin. In addition, an acute stressor (cold water swim), alone or in combination with ascorbate deficiency, had no effect on ethanol preference. At termination of the experiment, two measures of brain aminergic function (MAO activity and ³H-spiroperidol binding), purportedly altered by ethanol or ascorbic acid or both, were not associated with tissue ascorbate levels.     

Absorption of ascorbic acid and ascorbic sulfate and ascorbate metabolism in common carp (Cyprinus carpio L.)

Summary Ascorbate metabolism was analyzed in fasted common carp and carp offered diets lacking ascorbic acid or supplemented with ascorbic acid (AA) or ascorbic sulfate (AS). Ascorbic acid and ascorbic sulfate were analyzed in the contents collected from various parts of the digestive tract. The major site of the dietary ascorbate absorption was located in the first 20% of the anterior intestine region (58.7±10.2%), whereas absorption increased to 94.3±1.9% (in the whole gut). Considerable secretion of ascorbate into the initial part of the intestine was found (71 g AA · g^-1 dry food) in fish offered the diet lacking ascorbate, but this amount was completely reabsorbed in the following portions of the intestine. AS was concentrated in the contents of the digestive tract and the external marker method revealed no absorption of AS from the intestine. In fish fed the AA-supplemented diet, the concentration of ascorbate in plasma, hepatopancreas, kidney, intestine, spleen, and brain was significantly (P<0.01) higher than in similar tissues from the other groups, suggesting that ascorbic sulfate hydrolysis was ineffective. Small amounts of AS were found in the intestine and spleen of fish fed a diet supplemented with AS. Ascorbate analysis in the whole fish allowed the estimate of the catabolic rate of fasting and scorbutic-diet-fed fish, which amounted to 0.7% and 1.46% daily of the ascorbate body pool, respectively. There was no indication that ascorbic sulfate sulfohydrolase activity was induced in hepatic, kidney, or intestinal tissue of fish offered a diet with AS in comparison to other groups. It seems unlikely that cyprinid fish are able to utilize ascorbic sulfate as a vitamin C source, and thus resemble scurvy-prone mammals in this respect.Abbreviations AA ascorbic acid - AS ascorbic sulfate - TCA trichloroacetic acid - PCA perchloric acid - EDTA ethylenediaminetetraacetate dihydrate - DNPH dinitrophenyl hydrazine - ASS-ase ascorbic sulfate sulfohydrolase - AR-ase arylsulfatase - NCS p-nitrocatechol sulfate - DHA-rase dehydroascorbate reductase - DHA dehydroascorbic acid - GSH glutathione - G-6-Pase glucose-6-phosphate dehydrogenase - G-6-P glucose-6-phosphate     

Ascorbic acid uptake in guinea pig intestinal mucosa

Cellular accumulation of ascorbic acid was investigated in vitro in distal intestinal mucosa of guinea pig. With ¹⁴C-ascorbic acid present at 8 μM/L in the bathing media, tissue/media (T/M) concentration ratios of at least 5 were routinely achieved. Recently absorbed ascorbic acid appeared to be free in solution in the cellular fluid in that it diffused from tissue exposed to poisons with a disappearance half-time of approximately 10 minutes. Ascorbic acid uptake was highly dependent on the presence of sodium in the bathing media; total Tris substitution resulted in a 97% decrease in uptake. Also, metabolically depleted tissue did not accumulate ascorbic acid against a concentration gradient. Uptake of ¹⁴C-ascorbic acid from a bathing solution concentration of 8 μM/L was reduced 67% in the presence of 0.8 mM/L nonlabeled ascorbic acid. Recently absorbed ¹⁴C-ascorbic acid moved more rapidly back into the lumen when the luminal solution contained nonlabeled ascorbic acid (5 mM) than when it contained mannitol (5mM). This demonstration of counter transport substantiates a carrier mechanism in the brush border.     

Effect of ascorbic acid on neurochemical, behavioral, and physiological systems mediated by catecholamines

Ascorbic acid, at concentrations below that normally present in the brain, inhibited the dopamine-sensitive adenylate cyclase $\text{in}$$\text{vitro}$. Ascorbate had no effect on the norepinephrine-sensitive adenylate cyclase. To study the $\text{in}$$\text{vivo}$ effect of ascorbic acid on central dopaminergic systems, mice (C57 B1/6J) were injected with pharmacological doses (2 g/kg) of ascorbate, which produced a significant elevation in brain ascorbate concentration. Injecting the mice with ascorbate (2 g/kg) blocked the amphetamine-induced (15 mg/kg) increase in stereotype behavior which has been reported to be mediated by dopaminergic neural systems. Ascorbate had no effect on the amphetamine-induced locomotor activity thought to be mediated by norepinephrine systems. Ascorbate (1 g/kg) attenuated apmorphine-induced hypothermia in this same strain of mice. This demonstrates the specific neurochemical, physiological, and behavioral alterations in dopaminergic systems produced by ascorbic acid and suggests possible therapeutic uses for ascorbate in conditions involving functional dopamine excess.     

Effect of dietary chromium supplementation on meat nutritional quality and antioxidant status from broilers fed with Camelina-meal-supplemented diets

Poultry meat is a valuable source of nutrients and the enrichment with health-promoting substances such as polyunsaturated fatty acids (n-3 PUFA) is an important factor for consumers’ choice. Camelina meal (Camelina sativa) is an animal feedstuff used to achieve this goal, but the administration of n-3 PUFA-enriched diets in broiler nutrition can accelerate the oxidative processes in meat leading to a decreased quality of final product. The aim of this study was to investigate the effect of the organic Cr as chromium picolinate (CrPic) on meat quality, fatty acid profile of fat and oxidative stability of meat from broilers fed supplemented dietary Camelina meal. An experiment was conducted on 240 Ross 308 broiler chicken aged 14 days which were assigned to 6 dietary treatments in a randomized complete block design with a 2 × 3 factorial arrangement. Within the treatment arrangement two concentrations of Camelina meal (0% and 3%) and three concentrations of Cr³⁺ (0, 200 and 400 μg/kg) were used. Dietary treatments were: (1) Control diet (C) containing a corn–soybean diet with no added Camelina meal or Cr³⁺; (2) a C diet containing an additional 200 μg/kg of Cr³⁺ as CrPic; (3) a C diet containing an additional 400 μg/kg of Cr³⁺ as CrPic; (4) a C diet containing an additional 3% Camelina meal; (5) diet 2 containing an additional 3% Camelina meal; (6) diet 3 containing an additional 3% Camelina meal. Chromium supplementation significantly (P<0.05) increased the CP concentrations and significantly (P<0.05) decreased the crude fat concentrations in breast samples. The Camelina meal groups presented higher values of unsaturated fatty acids, particularly n-3 fatty acids (P<0.05). In CrPic groups, increased retention of Zn and Fe (P < 0.05) was observed in breast samples, compared to control group, and thiobarbituric acid reactive substances values were significantly (P<0.05) smaller. Myoglobin fraction (metmyoglobin and oximyoglobin) concentrations differ significantly (P<0.05) from the control group, under the influence of Cr³⁺ supplements. This study found that broilers fed with CrPic supplements showed improved mineral composition and oxidative stability of breast meat, proving an effective protection of lipid molecules from oxidation in PUFA-enriched meat.     

Effects of dietary chromium supplementation on performance, carcass traits, serum metabolites, and tissue chromium levels of Japanese quails

This study was conducted to investigate the effects of various levels of dietary chromium supplementation on performance, carcass traits, blood chemistry, and tissue distribution of chromium (Cr³⁺) in quails. Two hundred forty 1-d-old Japanese quails were divided into five groups with four replicates and were fed a basal diet or the basal diet supplemented with 20, 40, 80, or 100 mg/kg Cr (CrCl₃·6H₂O) until 38 d of age. Chromium supplementation decreased carcass fat percentage, serum low-density lipoprotein (LDL), and glucose and increased serum magnesium (Mg) and Cr content of kidney, liver, and muscle. In conclusion, 20, 40, 80, or 100 mg/kg Cr supplementation to quail diet had no effect on performance, chemical composition of carcass except fat percentage, serum protein, calcium (Ca), and inorganic phosphorus (Pi) levels, but reduced serum glucose, LDL and fat percentage of carcass. Chromium is accumulated mainly in the kidneys and liver.     

The Effects of Chromium Histidinate on Mineral Status of Serum and Tissue in Fat-Fed and Streptozotocin-Treated Type II Diabetic Rats

The present study was conducted to investigate the effects of chromium histidinate (CrHis) against experimentally induced type II diabetes and on chromium (Cr), zinc (Zn), selenium (Se), manganese (Mn), iron (Fe), and copper (Cu) in serum, liver, and kidney of diabetic rats. The male Wistar rats (n = 60, 8 weeks old) were divided into four groups. Group I received a standard diet (12% of calories as fat); group II were fed standard diet and received CrHis (110 mcg CrHis/kg body weight per day); group III received a high-fat diet (HFD; 40% of calories as fat) for 2 weeks and then were injected with streptozotocin (STZ) on day 14 (STZ, 40 mg/kg i.p.; HFD/STZ); group IV were treated as group III (HFD/STZ) but supplemented with 110 mcg CrHis/kg body weight per day. The mineral concentrations in the serum and tissue were determined by atomic absorption spectrometry. Compared to the HFD/STZ group, CrHis significantly increased body weight and reduced blood glucose in diabetic rats (p < 0.001). Concentrations of Cr, Zn, Se, and Mn in serum, liver, and kidney of the diabetic rats were significantly lower than in the control rats (p < 0.0001). In contrast, higher Fe and Cu levels were found in serum and tissues from diabetic versus the non-diabetic rats (p < 0.001). Chromium histidinate supplementation increased serum, liver, and kidney concentrations of Cr and Zn both in diabetic and non-diabetic rats (p < 0.001). Chromium supplementation increased Mn and Se levels in diabetic rats (p < 0.001); however, it decreased Cu levels in STZ-treated group (p < 0.001). Chromium histidinate supplementation did not affect Fe levels in both groups (p > 0.05). The results of the present study conclude that supplementing Cr to the diet of diabetic rats influences serum and tissue Cr, Zn, Se, Mn, and Cu concentrations.     

Effects of dietary chromium and ascorbic acid supplementation on digestion of nutrients,serum antioxidant status,and mineral concentrations in laying hens reared at a low ambient temperature

This experiment was conducted to evaluate the effects of chromium (chromium picolinate, CrPic) and vitamin C (l-ascorbic acid) supplementation on the digestion of nutrients and serum concentration of some antioxidant vitamins and minerals of laying hens (Hy-Line) reared at a low ambient temperature (6.8°C). One hundred twenty laying hens (32 wk old) were divided into 4 groups, 30 hens per group. The laying hens were fed either a basal diet or the basal diet supplemented with either 400 μg of Cr/kg diet, 250 mg of l-ascorbic acid/kg diet, or 400 μg of Cr plus 250 mg l-ascorbic acid/kg diet. The digestibility of nutrients (DM, OM, CP, and EE) increased by the supplementation of chromium and vitamin C (p<0.05). Supplemental chromium and vitamin C also increased serum vitamin C and E but decreased malondialdehyde concentrations (p<0.05). Additionally, supplemental chromium and vitamin C caused an increase in the serum concentrations of Fe, Zn, Mn, and Cr (p<0.05) but a decrease in Cu concentration. The results of the present study showed that each dietary supplement influenced most of the parameters measured in a similar way. Also, a combination of the two supplements resulted in an additive effect, and supplementing a combination of vitamin C (250 mg/kg of diet) and chromium (400 μg Cr/kg diet) may offer a potential protective management practice in preventing cold-stress-related depression in the performance of laying hens.     

Ascorbic acid status in high-mountain charr,Salvelinus alpinus,in relation to the reproductive cycle

Synopsis Concentrations of total and dehydroascorbic acids and of glutathione were determined in tissues of male and female Arctic charr at different stages of the reproductive cycle. In fish inhabiting an Alpine lake (2344 m above sea level) the ascorbic acid concentrations were significantly higher in the ovary (344 g g^–1 in August) than in the testis (62.6 g g^–1). The ascorbate concentration was significantly higher in liver and kidney of males than in females in the period prior to spawning. This suggests that there was an intensive investment of body ascorbate reserves in the ovary and the results indicated that females deposited approximately 10 times the amount of vitamin C in ovaries than males deposited in testes. However, the endogenous stores cannot account for all ascorbate deposited in ovaries and the remainder must come from food consumed in summer. Since the resident charr of the high-mountain lake had the ascorbate concentration in ovary by one order of magnitude higher than in cultured salmonids it is plausible to speculate that the change in ascorbic acid metabolism reflects the adaptation to the harsh environmental conditions.     

Effects of copper, iron, and ascorbic acid on manganese availability to rats.

Four experiments were done to characterize the interactions of copper, iron, and ascorbic acid with manganese in rats. All experiments were factorially arranged Dietary Mn concentrations were less than 1 micrograms/g (Mn0) and 50 micrograms/g (Mn+). Dietary Cu was less than 1 mg/g (Cu0) and 5 micrograms/g (Cu+); dietary Fe was 10 micrograms/g (Fe10) and 140 micrograms/g (Fe140). Ascorbic acid (Asc) was not added to the diet or added at a concentration of 10 g/kg diet. Experiment 1 had two variables, Mn and Cu; in Experiment 2, the variables were Mn and Asc. In Experiment 3, the variables were Mn, Cu, and Asc; in Experiment 4, they were Mn, Cu, and Fe. Definite interactions between Mn and Cu were observed, but they tended to be less pronounced than interactions between Mn and Fe. Cu depressed absorption of 54Mn and accelerated its turnover. In addition, adequate Cu (Cu+), compared with Cu0, depressed liver, plasma, and whole blood Mn of rats. Absorption of 67Cu was higher in animals fed Mn0 diets than in those fed Mn+. Ascorbic acid depressed Mn superoxide dismutase activity and increased Cu superoxide dismutase activity in the heart. The addition of ascorbic acid to the diet did not affect Mn concentration in the liver or blood. Absorption of 54Mn was depressed in rats fed Fe140 compared with those fed Fe10. Interactions among Fe, Cu, and Mn resulted in a tendency for Mn superoxide dismutase activity to be lower in rats fed Fe140 than in rats fed Fe10. Within the physiologic range of dietary concentrations, Mn and Cu have opposite effects on many factors that tend to balance one another. The effects of ascorbic acid on Mn metabolism are much less pronounced than effects of dietary Cu, which in turn affects Mn metabolism less than does Fe.     

Effects of dietary combination of chromium and biotin on egg production, serum metabolites, and egg yolk mineral and cholesterol concentrations in heat-distressed laying quails

Chromium picolinate is used in the poultry diet because of its antistress effects in addition to the fact that the requirement for it is increased during stress. This study was conducted to determine if the negative effects of high ambient temperature (34°C) on egg production, egg quality, antioxidant status, and cholesterol and mineral content of egg yolk could be alleviated by combination of chromium picolinate and biotin (0.6/2.0; Diachrome^™, as formulated by Nutrition 21 Inc.), in laying Japanese quails (Coturnix coturnix japanica), Quails (n=240; 50 d old) were divided into 8 groups, 30 birds per group. The quails were fed either a basal diet or the basal diet supplemented with 2, 4, or 8 mg of Diachrome/kg diet. Birds were kept at 22°C and 53% relative humidity (RH). At 14 wk of age, the thermoneutral (TN) group remained in the same temperature as at the beginning of experiment, whereas the heat stress (HS) group was kept in an environment-controlled room (34°C and 41% RH) for 3 wk. Heat exposure decreased performance when the basal diet was fed (p=0.001). Diachrome supplementation at 4 and 8 mg/kg diet, increased feed intake (p=0.05), egg production (p=0.05), feed efficiency (p=0.01), egg weight (p=0.05), and Haugh unit (p=0.01) in quails reared under heat stress conditions. Heat exposure increased concentrations of serum malondialdehyde (MDA) (p=0.001), glucose, and cholesterol (p=0.01), which were elevated by supplemental Diachrome (p≤0.05). Egg yolk Cr, Zn, and Fe (p=0.01) concentrations increased linearly, whereas MDA and cholesterol concentrations decreased (p=0.05) as dietary Diachrome supplementation increased in HS groups. Similar effects of supplementation on serum levels of glucose and cholesterol (p=0.05) and egg yolk concentrations of cholesterol (p=0.05) and Cr (p=0.01) were observed in TN groups. No significant differences in other values were observed in the TN groups. Results of the present study suggest that supplementation with Diachrome protects the quail by reducing the negative effects of heat stress.     

Effects of physical exercise and aging on ascorbic acid and superoxide anion levels in peritoneal macrophages from mice and guinea pigs

The relationship of physical activity and aging, two processes with a high production of oxygen-free radicals to the ascorbate and superoxide anion (O ₂ ^- ) contents of peritoneal macrophages was studied in two animal species: guinea-pig (in which ascorbic acid is a vitamin) and mouse (in which ascorbic acid is not a vitamin). The effects of exhaustive exercise were examined in young and old animals. The results show that macrophages from old animals have a lower ascorbate content than those from young ones, whereas with exercise the ascorbate content increased in both old and young animals. This increase was higher in young than in old animals, and more evident in mice than in guinea-pigs. Aging also resulted in an increase in the O ₂ ^- levels of macrophages. With exercise these levels decreased in young mice but increased in young guinea-pigs. In old animals the exhaustive exercise did not change the O ₂ ^- levels. The results suggest in general a lack of correlation between the intracellular ascorbate and O ₂ ^- levels in relation to both physical exercise and aging.Abbreviations PBS phosphate buffered saline - NBT nitroblue tetrazolium - PEC peritoneal exudate cells - PMN polymorphonuclear     

Glycine-U-14C Metabolism in Young Rats Fed the 10% Casein Diets Containing Excess Glycine

Nine hours after rats fed ad libitum for 14 days a 10% caein diet (10C), a 10% casein diet containing 7% glycine (10C7G) and a 10% casein diet containing 7% glycine with 1.4% l-arginine HCI and 0.9% l-methionine (10C7GArgMet) were force-fed 10 ml of each diet suspension containing 5 μCi of glycine-U-¹⁴C per 100 g of body weight, the radioactivity recoveries of ¹⁴C in expired CO₂, tissue components and urine were determined.

The radioactivity recovery of ¹⁴C in the expired C0₂ of the 10C7G group was generally higher than that of the 10C7GArgMet group, and those of both groups would have been much higher than that of the 10C group unless the isotope had been diluted. The amount of expiratory ¹⁴C of rats fed a 25 % casein diet containing 7% glycine was not different from that of the 10C7G group. The recovery of ¹⁴C in the trichloroacetic acid (TCA) soluble fraction of muscle of the 10C7G and the 10C7GArgMet groups were greater than that of the 10C group, but there was no difference between the 10C7G and the 10C7GArgMet groups. The recoveries of ¹⁴C in the TCA soluble fraction and protein of plasma and liver, and the muscle protein were negligible in all the groups. The amount of glycine-¹⁴C incorporated into the carcass lipids of the 10C7GArgMet group was larger than that of other groups. Those in the carcass lipids of the 10C7G and the 10C7GArgMet groups would have been much higher than that of the 10C group unless the dilution of the isotope had taken place. The recoveries of ¹⁴C in the liver and muscle glycogen, and liver lipids were remarkably small in all the groups. From the above results, it was suggested that the degradation of glycine-¹⁴C to expiratory CO₂ was not accelerated, but the rate of incorporation of the isotope into carcass lipids was increased by the supplementation of l-arginine and l-methionine to the 10C7G diet as compared with that of rats fed the 10C7G diet.     

Ascorbic acid supplementation and copper status in rats

The effect of a high concentration (1%, w/w) of ascorbic acid in a Cu-adequate (150 μmol/kg) purified diet was studied in rats. After 6 wk, ascorbic acid had significantly reduced Cu concentrations in muscle and bone. The estimated whole body content of Cu in rats fed ascorbic acid was reduced by 20%. Within 1 d after oral administration of⁶⁴Cu, the recovery of the dose in feces was increased in rats fed ascorbic acid, suggesting that the vitamin depresses intestinal absorption of Cu. After intraperitoneal (ip) administration of⁶⁴Cu, the rate of loss of the dose from the body was decreased in rats fed ascorbic acid. This study suggests that the ascorbic acid induces a decreased efficiency of intestinal Cu absorption, which in turn triggers mechanisms to preserve Cu in the body stores. This is supported by the observation that the feeding of a Cu-deficient diet (5 μmol/kg) had similar effects, although more pronounced.     

Role of ascorbate in lung cellular toxicity mediated by light-exposed parenteral nutrition solution

Abstract

Neonatal lung injury has been induced experimentally by infusion of multivitamin-containing light-exposed parenteral nutrition (PN) solutions. The objective was to explore the role of ascorbate in toxic effects of light-exposed PN on primary cultured foetal rat lung epithelial cells. Hydroperoxides were measured in 3% amino acid solutions at baseline, immediately after addition of either multivitamins or ascorbate alone (400 μg/mL) and again after a 24-h period of exposure to (or protection from) ambient light. Cellular toxicity was assessed by [C¹⁴]adenine release. Multivitamins or ascorbate alone increased hydroperoxides in PN, which was attenuated by light protection. Light-exposed PN containing multivitamins was more toxic to cells than baseline or light-protected PN. Exposure to ascorbate at concentrations both lower (< 5 μg/mL) and higher (> 1000 μg/mL) than normally contained in PN-induced oxidant-mediated cell death, as indicated by protective effects of hydroperoxide and hydroxyl radical scavengers. This study concludes that ascorbate generates toxic amounts of peroxide in PN solutions. The types and physiological importance of hydroperoxides induced by pro-oxidant effects of ascorbate require further evaluation in vivo.     

Effects of phosphorus and vitamin C deficiency,vitamin A toxicity,and lipid peroxidation on skeletal abnormalities in Atlantic halibut (Hippoglossus hippoglossus)

Dietary nutrients play an important role in skeletal tissue metabolism of fish. Deficiency and toxicity of certain nutrients have been linked to bone deformities in larval and juvenile fish. The pathogenesis of skeletal disorders in larval and juvenile fish from the same genetic stock, cultured under similar environment conditions is often difficult to distinguish when marginal deficiencies of multiple nutrients are involved. A study was conducted to characterize the skeletal deformities linked to the deficiency of phosphorus and ascorbic acid, vitamin A toxicity and lipid peroxidation in juvenile halibut. Five experimental diets containing a low level of phosphorus (0.5% dry matter basis), no vitamin C supplement, high level of vitamin A (80 000 IU kg^?1) and oxidized marine fish oil (peroxide value, 7.53 meq kg^?1) and a control diet based on cod fillet and vitamin free casein were fed to juvenile Atlantic halibut for 14 weeks in an attempt to characterize the skeletal deformities. Phosphorus, ascorbic acid, retinol, and α‐tocopherol concentrations of liver and kidney were measured at 0 and 14 weeks. Reduced vertebral ash and phosphorus content were observed in fish fed the low phosphorus diet. Skeletal abnormalities included abnormal hemal and neural spines in the hemal region and scoliosis in the cephalic and hemal regions of the vertebral column. Hepatic and kidney ascorbic acid concentrations were significantly lower in the group fed no ascorbic acid supplement. Skeletal abnormalities were scoliosis and lordosis primarily in the hemal region of the vertebral column. High levels of vitamin A in the diet caused increased hepatic retinol content and scoliosis spanning the cephalic/prehemal and anterior hemal regions of the vertebral column. Fish fed the oxidized oil diet showed increased thiobarbituric acid (TBA) value in the liver and muscle tissue with no significant decrease in hepatic vitamin E concentration. The most frequent skeletal deformity observed was scoliosis, spanning the cephalic/prehemal regions as well as the anterior hemal region of the vertebral column. The pattern and type of abnormalities observed in fish fed these experimental diets were similar to those observed in a commercial halibut hatchery.     

Ascorbic acid turnover and excretion in two arboreal marsupials and in laboratory rabbits

Rates of turnover and routes of excretion of 1-14C-ascorbic acid were compared among laboratory rabbits and two species of arboreal marsupials. Ringtail possums (Pseudocheirus peregrinus) exhibited higher blood ascorbate levels than either brushtail possums (Trichosurus vulpecula) or rabbits, as well as greater pool sizes, shorter half-times and higher total entry rates of ascorbic acid. These differences were due partly to the high ascorbic acid content of Eucalyptus foliage, the ringtail's diet; when the dietary contribution of ascorbate was taken into account, endogenous entry rates (i.e. 'synthesis') were not significantly different among species. The main excretory route of 14C from 1-14C-ascorbate was expired CO2 in all three species. Estimates to total pool size of ascorbate by isotope dilution were higher than those by tissue analysis. This was considered to be due to excretion of 14C during equilibration of injected 1-14C-ascorbate with the body pool.     

Effect of high‐dose vitamin C supplementation on growth,tissue ascorbic acid concentrations and physiological response to transportation stress in juvenile silver pomfret,Pampus argenteus

This study investigated the effect of high‐dose vitamin C supplementation on growth, tissue ascorbic acid concentrations and physiological response to transportation stress in juvenile silver pomfret, Pampus argenteus (initial average weight 6.2 ± 0.2 g). Three practical diets were formulated to contain 100 (control), 450 and 800 mg ascorbic acid/kg diet, respectively, supplied as l‐ascorbyl‐2‐polyphosphate. Each diet was fed to triplicate groups of fish in circular tanks (3 m ø, 1.5 m depth) (60 fish/tank) for 9 weeks. Growth did not change significantly with dietary vitamin C levels, although an improvement tendency with an increase in vitamin C supplementation was observed. Ascorbic acid concentrations in the liver and muscle of fish fed diets containing graded levels of vitamin C were positively correlated with dietary levels of this vitamin. Tissue ascorbic acid concentrations significantly increased with increasing vitamin C supplementation. After 9 weeks, the fish were subjected to transportation stress for 4 h to determine the influence of high vitamin C supplementation on the physiological response to this stressor. Serum cortisol, glucose and lactate levels significantly increased in stressed fish. Serum cortisol and glucose concentrations after stress were significantly higher in fish fed the control diet (7.91 μg L^?1 and 0.80 mm , respectively) than in the other groups. However, there were no significant differences in serum cortisol and glucose levels after stress between the 450 and 800 mg kg^?1 diets. No significant change could be found in serum lactate levels after stress among the different treatments. In conclusion, the dietary administration of high doses of vitamin C could reduce stress in silver pomfret and increase the survival of fish under stress conditions.     

Salicylic acid induces amelioration of chromium toxicity and affects antioxidant enzyme activity in Sorghum bicolor L.

Aim: Chromium (Cr(VI)) would inflict serious morphological, metabolic, and physiological anomalies in plants ranging from chlorosis of shoot to lipid peroxidation and protein degradation. Cr(VI) toxicity is often associated with oxidative stress, caused by the excessive formation of reactive oxygen species (ROS). In response, plants are equipped with a repertoire of mechanisms to counteract heavy metal (HM) toxicity. Salicylic acid (SA) plays a key role in the signal transduction pathways of various stress responses, demonstrating the protective effect of SA against abiotic stress factors. So, the present investigation was carried out to study the amelioration of pernicious effects of different concentration of Cr(VI) (0.0, 2.0, and 4.0?mg Cr(VI) kg^?1 soil in the form of potassium dichromate) by treatments of salicylic acid solution viz. pretreatment and foliar spray via antioxidative enzymes and their metabolites.

Results: With different treatments of salicylic acid solution, the reinstatement from ill effects of Cr(VI) toxicity was contemplated but the most conspicuous effect was observed when salicylic acid solution was supplied through the foliar spray (0.50?mM). This was accompanied with an increase in ascorbate peroxidase activity and hydrogen peroxide content and decrease in peroxidase activity and ascorbic acid content.

Significance of the study: This study suggests that salicylic acid when applied through pre-treatment of seeds or through a foliar spray can be used to ameliorate the toxic effects of chromium (VI). Salicylic acid has the great potential for reducing the toxicity of heavy metals without negatively impacting the growth of the plants.     

Elimination of apple stem grooving virus by chemotherapy and development of an immunocapture RT-PCR for rapid sensitive screening

Ombuin (7,4′-dimethyl quercetin) (10 μg ml^-1, for 12 wk), glycyrrhizin/quercetin (80 μg ml^-1and 10 μg ml^-1respectively, for 18 wk), ribavirin (10 μg ml^-1, for 12 wk) and quercetin/ribavirin (10 μg ml^-1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT-PCR, and immunocapture RT-PCR. A sensitive immunocapture RT-PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.