First Week Of Starvation Research Articles

Combined antagonist treatment of glucocorticoid and mineralocorticoid receptor does not affect weight loss of fasting rainbow trout but inhibits a fasting-induced elevation of cortisol secretion

The gastrointestinal system of fish reacts rapidly to food deprivation. The relative masses of digestive organs and activities of digestive enzymes decrease within days of fasting. This is believed to be an energy-conserving strategy as the metabolic cost of maintaining digestive capacity is high. Cortisol is known for its role in energy mobilization following stress exposure, and prolonged elevated cortisol levels have been shown to reduce growth rates in fish. Fish experiencing chronic cortisol elevations show structural changes to their digestive tissues and overall reductions in relative digestive tissue masses. In fish fasting for prolonged periods, circulating cortisol levels have been reported to be downregulated, upregulated, or unchanged compared to feeding fish. This study aimed to investigate if RU486 and spironolactone, antagonists of the glucocorticoid receptor (GR), and mineralocorticoid receptor (MR), respectively, alone or in combination affect circulating cortisol levels during prolonged starvation. In addition, we tested the effects of blocking GR and MR, on the down-regulation of relative digestive tissue mass during starvation, and its effects on weight loss. Three treatment groups of rainbow trout were intraperitoneally implanted with either GR, MR, or GR and MR blockers. A fourth group was implanted with cortisol, while a fifth group served as a control. All treatment groups were sampled over a course of four weeks of food deprivation and compared against each other and fed control fish at day 0 of the trial. Starvation for 2 weeks and longer significantly increased circulating cortisol levels in all groups except for the group implanted with GR and MR antagonists. Loss of body mass occurred most rapidly during the first week of starvation. Spironolactone treatment resulted in significantly reduced loss of mass during the first week, however, over the following weeks, no differences in mass loss were observed in the groups implanted with blockers, while cortisol-treated fish showed the highest decrease in body mass over time. Relative digestive tissue mass decreased in all groups but apparently, the fasting-induced elevation in plasma cortisol levels did not affect the relative weight loss of digestive tissues as no differences were observed between control fish and GR + MR antagonist treated fish. Very high cortisol levels caused by cortisol treatment however caused a faster decrease in the relative mass of some digestive organs, particularly the stomach.

Blood biochemistry fluctuations as influenced by feed provision in juvenile Snow trout (Schizothorax zarudnyi)

This study aimed at determining blood biochemical parameters with potential diagnostic value to assess the nutritional status for healthy Snow trout, Schizothorax zarudnyi. For this purpose, three treatment groups of Snow trout (average weight, 65.9 ± 5.3 g) were kept unfed for 24 h, 7 and 14 days. During the experiment, a natural photoperiod was adopted, water temperature was maintained at 23.2 ± 1.1 °C, pH 7.8 ± 0.2, dissolved oxygen 7 ± 0.4 mg l-1 and ammonia concentration was kept around zero mg l-1. Fish in all treatment groups were fed twice a day, to apparent satiety. At the end of the trial, the levels of glucose; triglyceride; cholesterol; total protein; inorganic phosphorus; calcium; magnesium; triiodothyronine (T3); thyroxin (T4); alkaline phosphatase (ALP); aspartate aminotransferase (AST); Alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were determined using standard clinical methods. The results showed that Glucose (71.8±6.64-138.6±13.02 mg dl-1), AST (63.53±12.17-130.41±23.04Ul-1) and T4 (6.46±0.88-11.69±1.16 ng ­ml-1) levels were significantly affected by the starvation period (p<0.05). T3 levels remained relatively stable during the first week of starvation (2.3±0.25-2.39±0.31 ng ml-1) and then significantly decreased (1.77 ng ml-1) in second week of starvation (p<0.05). Triglycerides levels increased during the first week of starvation (147.40±16.62 to 199.31±31.42 mg dl-1) and decreased in the second week (163.70±24.63 mg dl-1) (p<0.05), significantly. These results suggested that in healthy Snow trout juveniles, glucose, AST and T4 levels are responsive to starvation.

Molecular characterization and expression profiles of two insulin-like growth factor 1 receptors during fasting and re-feeding in Siniperca chuatsi

Two distinct insulin-like growth factor 1 receptors of the mandarin fish Siniperca chuatsi (scIGF1R1 and scIGF1R2) were cloned and characterized in this study. The complementary DNA of scIGF1R1 [4254 base pairs (bp)] and scIGF1R2 (4248 bp) encoded 1418 and 1416 amino acids, respectively. Both receptors contained a single short transmembrane domain, two receptor L domains and a furin-like cysteine-rich domain. Phylogenetic analysis revealed that scIGF1R1 and scIGF1R2 were clustered in two different branches. Both receptors were expressed in all tissues tested, and the expression levels were relatively high in the gonad, liver and brain. During the first week of starvation, the expression levels of both receptors were increased in the muscle and liver, whereas hepatic scIGF1 expression was decreased. After re-feeding, the expression levels of both receptors were gradually restored to the pre-starvation levels in the liver and muscle. The concentration of serum scIGF1 did not exhibit regular changes compared with the control group during fasting and re-feeding. The varying expression profiles of the scIGF1Rs among tissues indicated that these receptors have distinct, tissue-specific roles. Furthermore, the changes in expression levels of scIGF1, scIGF1R1s during fasting and re-feeding provided evidence to support the link between nutritional status and gene expression related to growth and development.

The ability to incorporate functional plastids by the sea slug Elysia viridis is governed by its food source

Functional kleptoplasty in sacoglossan sea slugs is among the most curious photosynthetic associations known. One member of these marine molluscs, Elysia viridis, is known to incorporate plastids from a variety of different algae food sources, but with apparently different outcomes and differences in the time span of the retention of functional kleptoplasts. While it was previously shown that kleptoplasts that stem from Codium tomentosum are kept functional for several weeks (long-term retention, LtR), those that stem from Bryopsis hypnoides or Cladophora rupestris are thought to be of limited use regarding photosynthetic capacity (short-term retention, StR). This is important, because it touches upon the popular yet controversial question of how important photosynthesis is for the thriving of these slugs. The aim of the present study was to determine to what degree the plastid source determines retention time. We, therefore, compared E. viridis feeding on either Cladophora sp. or B. hypnoides. We show that kleptoplasts of B. hypnoides incorporate 14CO2, but with rapidly declining efficiency throughout the first week of starvation, while the plastids of Cladophora sp. are, surprisingly, not incorporated to begin with. The radulae of the different samples showed adjustment to the food source, and when feeding on Cladophora sp., E. viridis survived under laboratory conditions under both starvation and non-starvation conditions. Our results demonstrate that (i) the ability to incorporate plastids by E. viridis differs between the food sources B. hypnoides and Cladophora sp., and (ii) photosynthetic active kleptoplasts are not an inevitable requirement for survival.

Selected plasma biochemistry parameters in gilthead seabream (Sparus aurata) juveniles

Summary The aim of this study was to assess plasma biochemistry parameters with the potential of being used as indicators of the nutritional status for healthy gilthead seabream juveniles. Triplicate groups of 18 seabream (body weight of 58 g) were kept unfed for 24 h, 7 or 14 days. Nine fish per treatment were then sampled randomly for blood collection and the following parameters analyzed in the plasma using standard clinical methods: glucose; protein; triglycerides; cholesterol; calcium; magnesium; inorganic phosphorus; alkaline phosphatase (ALP); aspartate aminotransferase (AST); lactate dehydrogenase (LDH); gamma-glutamyl transferase (GGT); creatine phosphokinase (CPK); and lipase. Biochemical parameters showed lower variability among individuals than did enzymatic parameters. Plasma glucose, protein, cholesterol, calcium and inorganic phosphorus levels were inversely related to the duration of starvation. On the contrary, plasma triglycerides decreased significantly during the first week of starvation and remained stable in the second week. Plasma ALP, AST and LDH decreased significantly after 1 week of starvation and then remained constant. In healthy seabream juveniles, plasma glucose, protein, cholesterol, calcium and inorganic phosphorus are responsive to starvation and may be useful indicators of the nutritional status of the animals. Indicative baseline reference values for gilthead seabream juveniles starved for 24 h and held at optimum temperature are: protein, 3.7–4.9 g dl−1; cholesterol, 341–407 mg dl−1; calcium, 13.1–8.0 mg dl−1; and inorganic phosphorus, 10–14.2 mg dl−1. Plasma triglycerides, along with plasma enzyme activities, may be useful as indicators of short term starvation. For these parameters baseline values after 1 week of starvation were: triglycerides: 138–230 mg dl−1; ALP: 58–125 U L−1; AST: 15–127 U L−1; and LDH 61–677 U L−1. Plasma glucose is only responsive to longer starvation periods, remaining relatively stable during the first week of starvation, and ranging from 59 to 196 mg dl−1.

Effect of food shortage and temperature on oxygen consumption in the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Abstract. Temperature and food availability are limiting factors for the establishment of tropical insects in temperate countries. In the alien pest beetle, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), starvation and temperature have a significant impact on metabolic rate with oxygen consumption ranging from 0.5 µmol/g fresh mass (FM)/h at 12 °C to 3.4 µmol/g FM/h at 24 °C. At 12 °C, oxygen consumption decreased continuously during an entire period of starvation. However, at 16, 20 and 24 °C, beetles display a marked hyperactivity that leads to an increase in the oxygen consumption level during the first week of starvation, followed by a steep decrease until the end of the starvation period. Oxygen consumption either does not decline in fed beetles (observed at higher temperatures) or declines at a much shallower rate than in starved beetles (observed at cooler temperatures). During the first week of refeeding, Oxygen consumption rose steeply at 16, 20 and 24 °C before levelling off to the initial value (t0). At 12 °C, no compensation process was observed during recovery. This study reveals that an important threshold in the biology of A. diaperinus lies between 12 and 16 °C, leading to the onset of reduced locomotor activity and the promotion of survival to the detriment of reproduction. This ‘sit and wait’ behaviour is proposed as an adaptive strategy (i.e. inactivity and lower oxygen consumption coupled with low energetic requirements and high recovery abilities). Such behaviour and the observed hyperactivity were rarely described in insects before the present study. Together, the previous and present results suggest that A. diaperinus populations are likely maintained in temperate regions by immigration from warmer situations.

Postmetamorphic Growth and Metabolism of Long-Spined Black Sea Urchin (Diadema antillarum) Reared in the Laboratory

Postmetamorphic growth and metabolism measurements were obtained on two cohorts of laboratory-reared Diadema antillarum. The cohorts grew linearly from less than 1 mm to over 43 mm. Daily growth averaged 0.097 and 0.11 mm d−1, respectively, for the two cohorts, and was found to differ significantly. Urchin metabolism was examined by a series of simultaneous measurements of oxygen consumption and ammonium excretion over 16 days on starved juveniles ranging 16.5 to 18.3 mm. Metabolic activity under conditions of starvation was used as a test of the viability of urchins reared in the laboratory with cultured food resources. Catabolic activity differed from the first week of starvation compared to the second. Metabolic response included: (1) a 2.2-fold increase in oxygen consumption rate; (2) 50% decline in ammonium excretion rate; and (3) a 5.1-fold increase in oxygen to nitrogen ratio. These measurements are consistent with a shift from almost pure protein catabolism during the first seven days of starvation to a lipid : protein catabolic ratio of 1 : 1 after the first week. Growth and metabolism experiments of this type are seen as a first step towards optimizing laboratory culture techniques of this species.

Impact of methionine on net ketoacid production in humans

An exogenous acid load (NH 4Cl) inhibits net ketoacid production in the first week of starvation and the fourth to eighth weeks of ketogenic dieting. To determine whether an acid load produced by amino acid metabolism can similarly modify ketosis, five overweight volunteers ingested methionine (H 2SO 4), NH 4Cl, and NaCl (control), in varying order, each day for seven days during weeks 5 to 8 of hypocaloric ketogenic dieting. During days 5 to 7 of each phase, blood pH, bicarbonate, and pCO 2 were stable but lower in the NH 4Cl phase (7.32 ± 0.02, 18.1 ± 1.2 mmol/L, 35.8 ± 1.4 mmHg) and the methionine phase (7.33 ± 0.01, 17.1 ± 0.9 mmol/L, 34.0 ± 2.0 mmHg) than in the NaCl phase (7.38 ± 0.01, 22.3 ± 0.2 mmol/L, 37.6 ± 1.6 mmHg), P < .05. Over this period, blood acetoacetate concentration was lower during the methionine and NH 4Cl phases than during NaCl, P < .05. In addition blood β-hydroxybutyrate and total ketone-body concentrations were lower in the methionine than NaCl phases, P < .05. Urinary acetoacetate and β-hydroxybutyrate excretion fell with both acid loads, P < .05. Compared with control values, urinary total ketone excretion was suppressed by 67 ± 10% in the NH 4Cl and 89 ± 3% in the methionine periods. When NaCl was ingested after either of the acid loads, urinary ketone excretion increased by 300% to 700%. Thus, methionine ingestion, which results in an acid challenge equivalent to that of a large protein load, has an impact on net ketoacid production similar to that of NH 4Cl. This observation suggests that endogenous as well as exogenous acid loads can influence organic acid production in a direction that helps maintain acid-base equilibrium.

Changes in the biochemical composition of tissues in Juvenile Sea bass during forced starvation

The effects of starvation on sea bass ( Dicentrarchus labrax) fingerlings (initial average weight 9.5 g) at 19° in sea water were studied. Fish start to die on day 19. Proximate analysis shows that water content increases with starvation time whereas protein and lipid contents decrease. After an initial decline, nitrogen excretion remains stable from day 2 to day 14. Starvation resulted in a reduction of liver, muscle and digestive tract lipids, mainly the triglycerides which are significantly reduced within the first week of starvation. The influence of water temperature on these changes is discussed.

Lipid Composition of a Psychrophilic Marine Vibrio sp. During Starvation-Induced Morphogenesis

Qualitative and quantitative changes with time in phospholipids and fatty acids were examined after suspension of cells of a psychrophilic marine bacterium in nutrient-free artificial seawater at 5 degrees C. Viability was maintained throughout the 21-day examination period, with plate counts and acridine orange direct counts indicating a slight increase in cell number. Gravimetric data, however, showed a significant decrease in bacterial biomass during the 3-week study. Levels of ATP per cell also decreased significantly (59%) during the starvation period. Since starvation (resulting in dormancy) is probably the typical physiological state of marine bacteria, estimation of bacterial density in marine waters by using ATP data obtained from log-phase cells is probably inaccurate. Total lipid phosphate decreased (65%) during the starvation period, with phosphatidylethanolamine showing the greatest loss. A large increase (57%) in the neutral lipid fraction was also detected, especially during the first week of starvation. A selective increase in palmitoleate at the expense of myristate was detected in the membrane lipids. The effects of these changes on membrane fluidity and the possible consequences for these cells in the marine environment are discussed.

Starvation-Survival Processes of a Marine Vibrio

Levels of DNA, RNA, protein, ATP, glutathione, and radioactivity associated with [S]methionine-labeled cellular protein were estimated at various times during the starvation-survival process of a marine psychrophilic heterotrophic Vibrio sp., Ant-300. Values for the macromolecules were analyzed in terms of total, viable, and respiring cells. Electron micrographs (thin sections) were made on log-phase and 5.5-week-starved cells. On a per-cell basis, the levels of protein and DNA rapidly decreased until a constant level was attained. A second method in which radioactive sulfur was used for monitoring protein demonstrated that the cellular protein level decreased for approximately 2.5 weeks and then remained constant. An initial decrease in the RNA level with starvation was noted, but with time the RNA (orcinol-positive material) level increased to 2.5 times the minimum level. After 6 weeks of starvation, 45 to 60% of the cells remained capable of respiration, as determined by iodonitrotetrazolium violet-formazan granule production. Potential respiration and endogenous respiration levels fell, with an intervening 1-week peak, until at 2 weeks no endogenous respiration could be measured; respiratory potential remained high. The cell glutathione level fell during starvation, but when the cells were starved in the presence of the appropriate amino acids, glutathione was resynthesized to its original level, beginning after 1 week of starvation. The cells used much of their stored products and became ultramicrocells during the 6-week starvation-survival process. Ant-300 underwent many physiological changes in the first week of starvation that relate to the utilization or production of ATP. After that period, a stable pattern for long-term starvation was demonstrated.

Metabolic Adaptations to Prolonged Food Deprivation by the American Badger Taxidea taxus

Energy expenditures for food processing, maintenance, and activity requirements were determined in the laboratory on the American badger, Taxidea taxus, both with ad lib. food and starved for 7, 20, and 30 days. Body weight decreased at about 76 g per day, resulting in a respiratory quotient (RQ) of 0.83 after 30 days of starvation. Energy requirements were calculated from V̇o2, values. A 24.2%, 19.7%, and 26.3% reduction in total metabolism was observed at 7, 20, and 30 days, respectively, without food because of reduced maintenance and activity requirements. As a result, badgers were able to conserve approximately 17 g of tissue per day after 30 days without food. Part of the lower maintenance metabolism was accounted for by a 1.7 C reduction in body temperature. Activity was most depressed the first week of starvation but progressively increased after 20 and 30 days without food.

Survival of a Psychrophilic Marine Vibrio Under Long-Term Nutrient Starvation

Ant-300, a psychrophilic marine vibrio isolated from the surface water of the Antarctic convergence, was starved for periods of more than 1 year. During the first week of starvation, cell numbers increased from 100 to 800% of the initial number of cells. Fifty percent of the starved cells remained viable for 6 to 7 weeks while a portion of the population remained viable for more than 1 year. During the first 2 days of starvation, the endogenous respiration of the cells decreased over 80%. After 7 days, respiration had been reduced to 0.0071% total carbon respired per hour and remained constant thereafter. After 6 weeks of starvation, 46% of the cellular deoxyribonucleic acid had been degraded. Observation of the cellular deoxyribonucleic acid with Feulgen staining before starvation showed the average number of nuclear bodies per cell varied from 1.44 to 4.02 depending on the age of the culture. A linear relationship was found between the number of nuclear bodies per cell and the increase in cell numbers upon starvation. Our data suggest that Ant-300 is capable of surviving long periods of time with little or no nutrients and is therefore well adapted for the sparse nutrient conditions of the colder portions of the open ocean.

Effets d'un je�ne de courte dur�e sur les principaux constituants biochimiques de l'oursin Arbacia lixula. I. Stade de repos sexuel

The effects of starvation on the levels of protein, carbohydrates and lipids of three principal reserve compartments-the gonads, digestive tract, and test-have been studied in the resting stage of the sea urchin Arbacia lixula. Variations of these levels were observed during 1 month's starvation. Analysis of covariance revealed the following significant changes: (a) a decrease in carbohydrates of the test and digestive tract; (b) a decrease in lipids of the test and gonads; (c) an increase in proteins of the gonads. A decrease in the carbohydrates and lipids of the test during the first week of starvation emphasizes the importance of the test as a storage organ.

Carbohydrate reserves and phosphatase activity in the mollusc-trematode relationship of Mytilus edulis L. and Proctoeces maculatus (Looss, 1901) Odhner, 1911.

AbstractBiochemical and histochemical techniques were employed to study tissue distribution, and concentrations of carbohydrate reserves and phosphatase activity in uninfected Mytilus edulis and specimens parasitized byProctoeces maculatus. Glycogen was stored in the mantle, hepatopancreas, labial palps and mesosomal Leydig cells of the mussel, and in the body parenchyma of post-miracidial stages of the trematode. The glycogen content of the mantle and hepatopancreas increased steadily from January to a maximum level in June and then declined sharply to a minimum level in December. No differences were observed in the annual glycogen cycle of infected and uninfected mussels. Starvation of mussels at a temperature conducive to high metabolic activity of the worms resulted in a rapid decline in the glycogen content of infected mussels by the first week of starvation. A stable glycogen concentration was maintained for 4 weeks by starved uninfected mussels. The distribution of acid phosphatase activity in the tissues ofM. edulisandP. maculatuswas greater than that of alkaline phosphatase activity, but increased alkaline phosphatase activity was observed in the haemolymph of mussels infected with adultP. maculatus.

Feeding, starvation and metabolic rate in the shore crab Carcinus maenas

The relationship between food intake and metabolic rate (as measured by oxygen consumption) of Carcinus maenas (L.) was studied. The metabolic rate of feeding crabs which had been starved for a short period increased, and several days were required for it to return to its original level. During prolonged starvation, the metabolic rate of C. maenas fell in two stages. The first reduction was to about 60% of the “feeding level”; this occurred during the first week of starvation. There was then a further reduction to about 40% of the “feeding level” and, at this level of metabolism, the crabs were able to survive for 3 months, with only 50% mortality; most of this occurred in the last 2 weeks. Metabolic rate was found to affect food intake; crabs acclimated to 24°C took 2.4 times as much food as crabs acclimated to 10°C, although the metabolic levels of the two groups differed by a factor of only 1.4. From the results obtained when the crabs were starved and when starved crabs were fed, it is suggested that, during starvation, the metabolic rate of C. maenas first drops from the elevated “feeding level” to a level at which carbohydrate reserves are utilised, and subsequently to a minimum level at which lipid reserves and proteins are used.

Hydroxyproline excretion during starvation of obese subjects

Hydroxyproline excretion was measured in 12 obese subjects during starvation. There was a consistent rise after the first week of starvation, and refeeding with low calorie, low hydroxyproline diets failed to affect the increased hydroxyproline excretion. Potassium supplementation in 2 subjects eating 300–600 calories caused a striking fall in hydroxyproline levels. Plasma growth hormone levels during fasting in 2 subjects were not elevated. It was concluded that the elevated hydroxyproline excretion during starvation and refeeding could arise from the collagenous supporting structures of fat and other tissues and that bone was not the major source since the excretion of calcium and pyrophosphate was not excessive.

Description and Biology of Hesperocimex Sonorensis, New Species, an Ectoparasite of the Purple Martin (Hemiptera: Cimicidae)1

This species is described from a population inhabiting nests of Progne subis hesperia in Sonora, Mexico. In laboratory studies it was found that first instar nymphs, fed once to repletion and then starved, molted and survived up to 63 days; that adults unfed after their final moult survived up to 169 days (males) or 218 days (females); and that a normally reproducing colony starved after approximately 75 days of age showed maximum survival for males of 59 days, for females 66 days. Well nourished virgin females were incapable of laying eggs, but after mating oviposited at the rate of 5.79 eggs per day per female for five consecutive weeks, with maximum production 6.88 eggs per day per female over a 3-day period. In one colony of 9 males and 14 females 5,195 eggs were produced over a 28-week period, an average of 343 per female, and 92.5% of these eggs hatched. Of 301 nymphs emerging to the adult stage, 37.9% were females, 62.1% males. Limited autogenous reproduction can occur in this species. In a colony where both sexes were not fed, 15 females produced 9 eggs; in another where only the females were unfed 13 females produced 25 eggs. Unfed males were found capable of inseminating females with viable sperm. 28 unfed males and 14 well fed females were kept together for one week, when the males were removed; these females averaged 242 eggs each during a 13-week period following exposure to the males, with maximum average production of 133 eggs for a 28- day period during the third to sixth weeks; 91.9% of these eggs hatched. Egg production declined sharply after eight weeks and virtually stopped by the 13th week, but when males were then added to the colony production increased to 0.9 egg per day per female. When starvation was imposed on a well-fed colony active in egg production, this production declined 92% between the fourth and seventh days, and only one egg was laid after the first week of starvation.