Mobilization and recovery of energy stores in traíra, Hoplias malabaricus Bloch (Teleostei, Erythrinidae) during long-term starvation and after re-feeding

In some neotropical environments, fishes often experience periods of poor food supply, especially due to extreme fluctuations in rainfall regime. The fish species that experience periods of drought such as the traíra Hoplias malabaricus (Bloch 1794), may stand up to long-term food deprivation. In this study, experiments were performed in order to determine the dynamic of utilization of endogenous reserves in this species during starvation. Adult traíra were both fasted for 30–240 days and re-fed for 30 days following 90 and 240 days of fasting. Glycogen and perivisceral fat were primary energy substrates consumed. During the first 30 days, fish consumed hepatic and muscular glycogen, without exhausting these reserves, and used lipids from perivisceral fat. Hepatic lipids were an important energy source during the first 60 days of starvation and perivisceral fat were consumed gradually, being exhausted after 180 days. Protein mobilization was noticeable after 60 days of fasting, and became the major energy source as the lipid reserves were decreased (between 90 and 180 days). Following the longest periods of food deprivation, fish had utilized hepatic glycogen again. Fish re-fed for 30 days after 90 and 240 days of fasting were able to recover hepatic glycogen stores, but not the other energy reserves.     

The influence of changes in food availability on the activities of key degradative and metabolic enzymes in the liver and epaxial muscle of the golden perch

This study investigated the influence of feeding frequency on the activities of important degradative enzymes and potentially rate-limiting enzymes in glycolysis and gluconeogenesis in the liver and white epaxial muscle of Macquaria ambigua . Adult animals were either fed daily to satiety (fed), deprived of food for up to 180 days (starved), or starved for 150 days then fed daily to satiety for 30 days (starved/fed). The activities of lipolytic, glycogenolytic and glycolytic enzymes in the livers of starved fish were maintained as long as liver energy stores were available, but became significantly reduced following their exhaustion indicating a decline in metabolism in response to prolonged starvation. The response of epaxial muscle metabolism to changes in food availability was different to that of the liver, as no significant change in the activities of muscle lipolytic or glycogenolytic enzymes were observed in response to starvation. Muscle tissue metabolism was reduced after 60–90 days of starvation, but then returned to prestarvation levels.     

Erythrocyte senescence and haematological changes induced by starvation in the neotropical fish traíra, Hoplias malabaricus (Characiformes, Erythrinidae)

Adult specimens of traira (Hoplias malabaricus Bloch) were subjected to long-term starvation (30 to 240 days) and re-fed for 30 days after 90 and 240 days of food deprivation. Counting of immature erythrocytes in peripheral blood showed that erythropoiesis decreased significantly during the first 30 days of food deprivation. The results suggest that a process of senescence takes place in the pre-existent red blood cells and that the cells are not replaced during starvation. After 240 days of starvation, H. malabaricus had a significantly reduced number of red blood cells, causing changes in hematocrit and blood indices (mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration). Furthermore, during this period, the fish presented leukopenia (lymphocytopenia) and thrombocytopenia. After re-feeding, the number of leukocytes and thrombocytes recovered, but the red blood cell number remained reduced and there was a significant increase in abnormal red cell nuclei.     

Elevated oxygen uptake and high rates of nitrogen excretion in early life stages of the cobia Rachycentron canadum (L.), a fast-growing subtropical fish

Physiological energetics of cobia Rachycentron canadum were quantified for 18 to 82 days post-hatch (dph) hatchery-reared juveniles to better understand energy transformation and its implications in growth and survival. Mean oxygen consumption rates ( ; mg O₂ h⁻¹) of fish fed ad libitum and fish that were starved significantly increased with increasing wet mass (M; g), = 1·4291 M ^0·8119 and = 1·1784 M ^0·7833, respectively, with a significant reduction in mean metabolic rates of starved fish (19 to 27% specific dynamic action; SDA). Total ammonia nitrogen excretion rates ( A _MM, μmol h⁻¹) also scaled with M and significantly decreased after starvation. Mean mass-specific A _MM and urea excretion rates are the highest reported in the literature, with urea accounting for approximately half the total nitrogen excretion measured in both fed and starved fish. Relatively high energetic rates may allow cobia to develop rapidly into pre-juveniles and be less susceptible to predation and starvation at a comparatively early age.     

The regulation of endogeneous energy stores during starvation and refeeding in the somatic tissues of the golden perch

Adult golden perch Macquaria ambigua were fed to satiety, starved for up to 210 days, or starved for 150 days then fed to satiety for 60 days to investigate the utilization of energy stores in response to food deprivation and re-feeding. Golden perch sequentially mobilize energy from hepatic tissue, extra-hepatic lipid, and finally muscle components in response to food deprivation. The relative size of the liver was significantly reduced by 30 days after the onset of food deprivation due to the simultaneous mobilization of lipid, protein and glycogen reserves. These stores were renewed rapidly within 30 days by satiety feeding. Mobilization of lipid stores in perivisceral fat bodies occurred between 30 and 60 days of food deprivation. These deposits were also renewed upon re-feeding, although not as rapidly as liver reserves. The glycogen content of the epaxial muscle was reduced by the 60th day of food deprivation but subsequently increased indicating the mobilization of other energy reserves. The concentration of muscle lipid decreased after 90 days of food deprivation. The only significant response in body composition observed in the fish fed to satiety throughout the study was an increase in the relative size of the perivisceral fat bodies. The results of this study suggest that golden perch are well adapted to cope with extended periods of food deprivation, storing energy as perivisceral fat when food is readily available and having a clearly sequential process for mobilizing energy when food is scarce which largely protects the integrity of the musculature.     

Effects of food deprivation on expression of growth hormone receptor and proximate composition in liver of black seabream Acanthopagrus schlegeli

The effects of food deprivation on the hepatic level growth hormone receptor (GHR) were investigated in black seabream (Acanthopagrus schlegeli) both at the protein level (by radioreceptor assay) and at the mRNA level (by ribonuclease protection assay). Serum levels of growth hormone (GH) and triiodothyronine (T₃) were also measured. Condition factor and hepatic proximate composition of the fish were also assessed. Significant decrease in hepatic GHR binding was recorded as early as on day 2 of starvation. On day 30 this decrease was even more pronounced, with the level in the starved fish reaching less than 20% the fed control level. A concomitant decrease in the hepatic GHR mRNA content was also noted during this period, with a progressive decrease from day 2 to day 30 of starvation. The extent of decrease in the mRNA content was less pronounced than the decrease in receptor binding, with the hepatic GHR mRNA content in the day 30 starved fish representing approximately 30% of the level in the fed control. In large contrast, serum GH level increased progressively during starvation. After 30 days of starvation, serum GH levels in the starved fish were more than three times the concentration found in the fed control. Serum T₃ levels, on the other hand, decreased during starvation, with the difference reaching significance on day 15 and day 30. After 30 days of starvation, serum T₃ levels in the starved fish were only approximately 40% the concentration found in the fed control. The hepatic lipid content exhibited an increasing trend during starvation. On day 30 the hepatic lipid content of the starved fish had doubled the level found in the fed control. However, the hepatic protein content did not exhibit much change during starvation. There was also a minor decrease in the moisture content of the liver during starvation, but the condition factor of the fish as a whole registered a gradual decrease during the course of food deprivation.     

Liver histopathology and accumulation of melano-macrophage centres in Hoplias malabaricus after long-term food deprivation and re-feeding

In the Neotropical traíra Hoplias malabaricus , hepatocyte surface area declined after 30 days of fasting due to reserve utilization. Changes in normal organization of liver were not confirmed until 180 days of fasting. Severe histopathological changes occurred after 240 days. Pigment accumulation in the hepatocytes and increase in number and size (surface area) of melano-macrophage centres (MMC) were also verified during long-term food deprivation. The melano-macrophages were rich in ferric compounds, probably haemosiderin. This suggests that the activity of hepatic macrophages is related to the intense erythrocyte degradation that occurred in traíra following long-term food deprivation. After re-feeding for 30 days, the liver presented a partial restoration, but the large MMC remained. When compared to the respective starved group, the hepatocytes of re-fed fish increased in size, revealing recovering cell activity and storage of some energy reserves.     

Metabolic responses to food deprivation and refeeding in juveniles of Rutilus rutilus (Teleostei: Cyprinidae)

Synopsis Effect of food deprivation and refeeding on metabolic parameters were studied in juvenile Rutilus rutilus, weighing 280–460 mg. Tissue hydration increased with the length of the starvation period, reaching a new steady state after 4–5 weeks. Total protein concentration remained constant at about 60% of dry body mass. The concentration of glycogen decreased during food deprivation, a new steady state being reached at about 30% of control values after 4 weeks. Refeeding caused a dramatic increase of glycogen concentration which exceeded the value in fed controls by 6- to 9-fold. This is seen as a tactic for rapid storage of food energy, to be used later for the synthesis of body materials. With respect to their responses to food deprivation the 12 enzymes investigated formed four groups: (1) activity unaffected by food deprivation or refeeding (COX, THIOL, CK, GOT); (2) activity drops to about 60% of control value during the initial phase of food deprivation but remains constant thereafter (PK, LDH, Pase); (3) slow but continuous decrease in activity during the whole period of starvation, i.e. up to 7 weeks (PFK, OGDH, CS, FBPase); (4) activity increases during food deprivation, decreases again upon refeeding (GPT). A model is discussed which distinguishes between four phases in the general response of young fish to food deprivation and refeeding: stress, transition, adaptation, and recovery.     

黑水虻幼虫的耐饥力及饥饿幼虫复食后的生物学特性

【目的】旨在明确黑水虻Hermetia illucens幼虫的耐饥力及饥饿幼虫复食后的发育、生殖力等生物学特性,为评估饥饿对黑水虻后续发育的影响并指导生产实践提供依据。【方法】将不同日龄或不同体重黑水虻幼虫进行不同时长的饥饿处理,测定和分析其耐饥力与日龄、百头重的关系;对7日龄幼虫进行不同时长的饥饿处理后再复喂,测定不同饥饿时长对其预蛹出现时间、总预蛹率、预蛹重、成虫繁殖等的影响。【结果】黑水虻幼虫饥饿后的半数致死时间(LT₅₀)与日龄成指数关系,与体重呈线性相关。7日龄幼虫的耐饥力较强,LT₅₀超过了50 d,饥饿30 d时存活率仍然达到了95%。百头重小于0.5 g的个体,其LT₅₀小于30 d;百头重在2～2.5 g的个体,其LT₅₀在45～70 d。幼虫超过8日龄时或百头重超过4.5 g时,多数个体在饥饿5 d时就提前进入了后续发育阶段。7日龄幼虫饥饿40 d内复食,其预蛹率未受到影响,但预蛹重显著增加;短期饥饿(0～10 d)对其成虫产卵量无显著影响,长期饥饿(30～40 d)使其成虫产卵量显著下降;饥饿长达30 d以上时,卵孵化率也显著降低。【结论】本研究明确了不同体重或不同日龄的黑水虻幼虫都具有一定的耐饥力;饥饿幼虫复食后预蛹重显著增加。     

Effects of feeding,starvation, and refeeding on the fatty acid composition of channel catfish,ICtalurus punctatus,tissues

• 1.1. The effects of feeding, food deprivation (14 and 28 days) and refeeding (starved 14 then fed 14 days) on the fatty acid composition of white muscle, liver and brain of pond-raised channel catfish (Ictalurus punctatus) were investigated.
• 2.2. Levels of n-3 fatty acids were significantly higher (P < 0.05) in white muscle of fish starved 28 days (10.7%) than in fish fed throughout the study (8.0%), due primarily to an increase in 22:6(n-3) docosahexaenoic acid or DHA.
• 3.3. Significantly higher levels of 20:5(n-3) (eicosapentaenoic acid or EPA) were found in livers offish starved 28 days (P < 0.05) compared to fish fed throughout the study.
• 4.4. Results suggest that the fatty acid compositions of channel catfish white muscle and liver are subject to only limited perturbation during periods of starvation and refeeding and that the brain is extremely well protected.

     

The role of food availability in regulating reproductive development in female golden perch

At a time of the year when female golden perch Macquaria ambigua are not normally reproductively active, they were either fed daily to satiety (Fed), starved for 150 days (S150), or starved for 150 days then fed to satiety for 30 or 60 days (S150/F30 or S150/F60). Fish showed rapid growth and increased food conversion efficiency upon re-feeding relative to Fed animals. The hepatosomatic indices were not significantly different between Fed, S150/F30 and S150/F60 groups, but were significantly reduced in S150 animals. The gonadosomatic indices ( I _G) for both Fed and S150 animals were not significantly different. However, the I _G values for S150/F30 and S150/F60 animals of 6·74±1·22 and 7·84±1·12 were significantly elevated relative to Fed animals and approach those described for wild mature M. ambigua . Oocyte development in Fed and S150 animals did not proceed past the cortical alveoli or perinucleolar stages, respectively, but oocytes in both S150/F30 and S150/F60 animals had undergone vitellogenesis and were close to being mature. The concentration of oestradiol and testosterone in the plasma of S150/F30 and S150/F60 animals increased in accordance with the proposed role of these hormones in teleost reproductive cycles. The reproductive response of M. ambigua to starvation and re-feeding is well suited to reproductive success in temperate Australian rivers where food availability is unpredictable.     

Constraints of body size and swimming velocity on the ability of juvenile rainbow trout to endure periods without food

The hypothesis that body size and swimming velocity affect proximate body composition, wet mass and size‐selective mortality of fasted fish was evaluated using small (107 mm mean total length, L _T) and medium (168 mm mean L _T) juvenile rainbow trout Oncorhynchus mykiss that were sedentary or swimming ( c . 1 or 2 body length s⁻¹) and fasted for 147 days. The initial amount of energy reserves in the bodies of fish varied with L _T. Initially having less lipid mass and relatively higher mass‐specific metabolic rates caused small rainbow trout that were sedentary to die of starvation sooner and more frequently than medium‐length fish that were sedentary. Swimming at 2 body length s⁻¹ slightly increased the rate of lipid catabolism relative to 1 body length s⁻¹, but did not increase the occurrence of mortality among medium fish. Death from starvation occurred when fish had <3·2% lipid remaining in their bodies. Juvenile rainbow trout endured long periods without food, but their ability to resist death from starvation was limited by their length and initial lipid reserves.     

Metabolic responses to prolonged starvation, food restriction, and refeeding in the brown trout, Salmo trutta: oxidative stress and antioxidant defenses

The effects of long-term starvation and food restriction (49 days), followed by refeeding (21 days) have been studied with respect to antioxidant defense in the liver and gills (branchial tissues) of the brown trout, Salmo trutta. Malondialdehyde levels in both tissues increased in parallel with starvation and food restriction and these values did not return to normal after the refeeding period. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) in liver and gills increased during the 49 days of starvation, but glucose-6-phosphate dehydrogenase (G6PD) activities decreased. Glutathione S-transferase (GST) activity decreased in the liver at the 49th day of starvation, but increased in the branchial tissues. Some of the antioxidant enzyme activities (such as hepatic GST and branchial G6PD) returned to control values of fed fish after the refeeding period, but others (e.g. hepatic SOD and branchial GPx) did not return to normal values. In conclusion, our study indicates that total or partial food deprivation induces oxidative stress in brown trout.     

短期饥饿和再投喂对岩原鲤仔鱼生存生长以及RNA/DNA和RNA/蛋白质比率的影响(英文)

研究通过对岩原鲤仔鱼在饥饿和再投喂条件下其生存、生长率、RNA/DNA和RNA/蛋白质比率的测定,评估了仔鱼对饥饿的耐受能力和恢复能力。在(19.5±0.5)℃水温下,将岀膜后第16天的岩原鲤仔鱼随机分成6个组:1个持续投饲对照组,实验组分别禁食1、2、3、4、5d后再投喂,实验共进行10d。每天分别从各组取9尾鱼测定体重、体长、RNA、DNA、蛋白质含量。实验结果显示,饥饿处理组仔鱼存活率和以上各项生长指标均随饥饿时间的增加而下降,在恢复投喂后均表现不同程度的补偿生长,其中饥饿1、2、3d的仔鱼在恢复投喂后显示出完全补偿生长,几乎弥补了饥饿所产生的影响,平均终体重与对照组比较无显著差异。饥饿4、5d的仔鱼显示部分补偿生长,恢复投喂只少量减轻了饥饿的影响,平均终体重与对照组相比存在显著差异。饥饿1、2、3d的仔鱼和4、5d的仔鱼在恢复投喂后分别需要1—2d和4d时间才能达到与对照组无显著差异水平。仔鱼生长率变动范围从0.59%到8.00%WW/day,仔鱼RNA/DNA比率、RNA/蛋白质比率与生长率的回归方程为:GR=3.63RNA/DNA 1.74(R2=0.80)和GR=120.14RNA/Protein 2.33(R2=0.31),两种比率均与生长率呈显著线性相关,RNA/DNA比率对生长变化的拟合度更好。结果表明,仔鱼阶段食物缺乏很可能是影响岩原鲤仔鱼存活、生长的主要因素。RNA/DNA更适合作为评定岩原鲤仔鱼营养条件和生长的指标。     

Lysosomal enzyme activities in muscle following starvation and refeeding in the saithe Pollachius virens L

Saithe (Pollachius virens L.) were starved for 66 days at 10 degrees C and activities of aryl sulfatase, acid proteinase, beta-glucuronidase, RNAase and acid phosphatase measured in homogenates prepared from fast and slow myotomal muscles. In fed fish, hydrolase activities were generally higher in slow than fast muscles. With the exception of acid proteinase activity in slow muscle, the activities of all the lysosomal enzymes increased by 70 to 100% during starvation. In general, there was a proportionally larger increase in the hydrolase activities in fast than in slow muscle. In a second experiment, fish were starved for 74 days, and refed for up to 52 days. The increases in aryl sulfatase and acid proteinase activity produced in fast muscle with starvation were found to be rapidly reversed by refeeding. Lysosomal enzyme activities in fish sampled after 10 days refeeding were not significantly different from fed controls. Membrane fractions enriched in aryl sulfatase activity were prepared from the fast muscle of 66-day starved fish. These were capable of degrading both myosin heavy chains and actin to lower molecular weight peptides at acid (pH 5.0), but not at neutral pH. The results suggest a role for lysosomal enzymes in the breakdown of myofibrillar proteins during starvation.     

Changes in plasma thyroxine,triiodothyronine and cortisol associated with starvation in rainbow trout (Salmo gairdneri)

Synopsis Chronically starved rainbow trout (Salmo gairdneri) showed a significant fall in liver size, total liver glycogen, liver glycogen concentration and plasma glucose levels. Liver lipid concentration did not differ significantly from controls although total liver lipid reserves fell during the first 40 days of starvation but had partly recovered after 65 days of starvation. Plasma cortisol and T3 levels did not show consistent changes concomitant with food deprivation over the 65 day period of the experiment. However, plasma T4 levels in fish starved for 40 or 65 days were significantly lower than comparably fed animals. The involvement of T4 in intermediate metabolic processes in salmonids is discussed.     

Fatty acid synthetase in control, starved and refed Richardson's ground squirrels

1. Starvation for 6 days reduced whole body mass and total body lipids to 76 and 71%, respectively, of pre-starvation levels in weight-gain phase ground squirrels. After 4 days of refeeding, body mass increased to 86% of pre-starvation level but total body lipids had not changed from starvation levels. 2. Compared to the fed state, fatty acid synthetase (FAS) activity in white adipose tissue (WAT) was 15 and 31% in starved and refed 4-day animals, respectively, and in liver was 26 and 21% in starved and refed 4-day animals, respectively. Lipids depleted by starvation during prehibernatory fattening were not rapidly restored in Richardson's ground squirrels. 3. Changes in these parameters with starvation and refeeding were similar in weight-loss phase animals. 4. In control animals of both phases, WAT accounted for at least 90% of total FAS activity and liver nearly all of the remainder.     

Toxic effects of mercury on testicular activity in the freshwater teleost, Clarias batrachus (L.)

Catfish ( Clarias batrachus L.) were exposed to selected sublethal concentrations of mercuric chloride (HgCl₂; 0.05 mg l⁻¹), methylmercuric chloride (CH₃HgCl; 0.04 mg l⁻¹) and emisan 6 (an organic mercurial fungicide; 0.5 mg l ⁻¹) for intervals of 45, 90 and 180 days from February to July (preparatory to spawning phase of the annual reproductive cycle). The gonadosomatic index showed a significant decrease after 90- and 180-day exposure to the mercurials. Histologically, the seminiferous tubules were smaller in size and contained mostly spermatids in comparison to the control fish in which they were greatly distended and full of spermatozoa. The Leydig cells showed pycnotic changes in Hg-treated fish after 90 and 180 days. In the Hg-treated testes, total lipid content and ³²P uptake decreased significantly after 90 and 180 days. Levels of phospholipids and free cholesterol registered a significant reduction during all the durations. Esterified cholesterol level showed a significant decrease only in the 90-day HgCl₂ and CH₃HgCl groups, and in all 180-day Hg groups, while the level of free fatty acid decreased significantly only in the 180-day Hg groups. The observations suggest that impairment of testicular lipid metabolism by Hg is one of the possible factors that led to the inhibition of steroidogenesis and spermatogenesis.     

Metabolic changes in the African fruit beetle,Pachnoda sinuata,during starvation

Specimens of the fruit beetle Pachnoda sinuata were starved for up to 30 days. The weight of the beetles declined consistently throughout the starvation period. Concentrations of carbohydrates and alanine in flight muscles, fat body and haemolymph decreased rapidly after onset of starvation, while the concentration of proline remained high. Whereas the lipid concentrations in the haemolymph did not change significantly upon starvation, the lipid content in flight muscles and fat body decreased significantly.Beetles that had been starved for 14 days responded to injection of Mem-CC, the endogenous neuropeptide from its corpora cardiaca, with hyperprolinaemia and a decrease in the alanine level, but no such effect was monitored after prolonged starvation of 28 days. Regardless of the period of starvation, Mem-CC injection could not cause hypertrehalosaemia or hyperlipaemia, although carbohydrates were increased in fed beetles after injection.Flight ability of beetles that had been starved for 15 or 30 days was apparently not impaired. During such periods, beetles used proline exclusively as fuel for flight as evidenced by the increase in the level of alanine in the haemolymph and decrease of the level of proline; the concentrations of carbohydrates and lipids remained unchanged.Activities of malic enzyme and alanine aminotransferase (enzymes involved in transamination in proline metabolism), glyceraldehyde-3-phosphate dehydrogenase (enzyme of glycolysis), 3-hydroxyacyl-CoA dehydrogenase (enzyme of beta-oxidation of fatty acids) and of malate dehydrogenase (enzyme of Krebs cycle) were measured in fat body and flight muscles. In flight muscle tissue the maximum activity of NAD(+)-dependent malic enzyme increased, while that of glyceraldehyde-3-phosphate dehydrogenase decreased during starvation, and malate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase and alanine aminotransferase were unchanged. In fat body tissue, activities of NADP(+)-dependent malic enzyme and 3-hydroxyacyl-CoA dehydrogenase increased during food deprivation and activities of glyceraldehyde-3-phosphate dehydrogenase, malate dehydrogenase and alanine aminotransferase remained unchanged.