The utilization of various biochemical entities in gonadally mature Balanus balanoides (L.) under starvaton and feeding in the absence of copulation

Copulation was prevented by isolation in Balanus balanoides (L.) and the changes in total body weight, carbohydrate, lipid, protein, RNA, and DNA followed when the animals were starved and fed; the results are compared with those on animals allowed to copulate with the consequent loss of semen and laying down of egg lamellae. General body tissues, semen, and ovaries are found not to be isolated compartments; on starvation both semen and ovary contribute to general metabolism, the former to a greater extent. Even when the isolated animals are fed there is still an almost complete resorption of semen, but the ovary is largely maintained. Possible control mechanisms are discussed.     

Reduced synthetic activity as a contributing factor to weight-loss in the circannual cycle of Richardson's ground squirrels

1. Glycogen concentrations in Richardson's ground squirrels of the weight-loss phase were 1/4-1/2 those in animals of the weight-gain phase. White adipose lipid content was similar in animals in the two phases when total body weight was similar. 2. Specific activity of 14C in muscle glycogen of fed, starved and refed ground squirrels in the weight-loss phase was similar to that in starved weight-gain phase animals. Activity in adipose lipids of fed, starved, and refed ground squirrels in the weight-gain phase was 5-8 times greater than that in the same nutritional states in weight-loss phase animals. 3. In addition to a voluntary reduction in food intake, a depressed synthetic activity in lipids and glycogen may account in part for the rapid decrease in body weight during the weight-loss phase of the circannual cycle.     

Body shrinkage as a possible over-wintering mechanism of the Antarctic krill, Euphausia superba Dana

Antarctic krill (Euphausia superba Dana) were maintained successfully for 211 days without food. A significant reduction in body size (32.1–56.1% of initial wet wt) was observed. Compared with wild animals starved E. superba decreased their oxygen uptake, ammonia excretion and phosphate excretion considerably (24–52%), but no significant changes in wet: dry wt ratio, and chemical compositions (C, N, P) were observed. The mortality of the starved group was similar to that of controls fed Tetra Marin and frozen copepods and less than that of controls fed a mixture of microalgae (Dunaliella and Phaeodactylum). Because of insufficient lipid storage, E. superba is hypothesized to switch from herbivorous feeding to omnivorous or carnivorous during the Antarctic winter. The present results suggest, however, that body shrinkage could be an alternative way for this animal to conserve energy during the winter. The advantage of this is discussed in the light of the characteristics of body structure and life style of E. superba.     

Effects of starvation on lung mechanics and biochemistry in young and old rats

Two groups of rats (young and old) were food-deprived for 3 wk and were compared with age-matched fed groups. Final body weight and dry and wet weights of lungs were significantly reduced in both young and old starved rats. As determined by saline volume-pressure (VP) curves, lungs of young starved rats accepted significantly less volume at all pressure levels compared with lungs of young fed rats. When expressed as a percent of maximum lung volume, the VP curve in young starved rats was significantly shifted upward at low lung volumes. In the old rats, the VP curves were similar in fed and starved rats. Total lung content of protein, DNA, crude connective tissue, hydroxyproline, and elastin were significantly reduced in young starved compared with young fed rats, whereas in old starved rats only protein and DNA contents were lower than those in old fed animals. It appears that in rapidly growing young rats starvation leads to growth retardation, loss of connective tissue components, and possibly reduction in tissue elastic forces at low lung volumes, whereas starvation has no significant effects on lung mechanics and connective tissue in old rats.     

Radioglucose metabolism by richardson's ground squirrels in the weight-gain and weight-loss phases of the circannual cycle

Summary Captive fed, starved, and refed Richardson's ground squirrels in the weight-gain and weight-loss phases of the circannual cycle were injected with radioglucose and the activity of the label in skeletal muscle proteins and white adipose tissue lipids four hours after injection was used to determine if lean body mass and white adipose tissue would be rapidly restored when starved animals were refed. Starvation for six days reduced carcass mass 27–31% and white adipose tissue mass 23–24% (Table 1). Activity of the label in both tissues of weight-gain and weight-loss animals was reduced by starvation. After four days of refeeding activities retured to levels similar to those in fed animals, with the exception of lower activity in skeletal muscle proteins of weight-gain animals. Furthermore, activity in each tissue fraction of starved and refed weight-gain animals was similar to that in weight-loss animals when expressed as per cent of activity in the respective fed state (Table 2). Radioglucose incorporation indicated that when skeletal muscle and adipose tissue are depleted by starvation, distribution of the label upon refeeding is similar to that in the fed state. Four days after refeeding weight-gain phase ground squirrels had restored 5.5 g of lean body mass and 7.5 g of adipose tissue, including 1.4 g (6 kcal) of protein and 7.0 g (66 kcal) of lipid, respectively. These results are also consistent with the fed state, in which weight-gain animals were depositing more lipid than lean body mass.     

Effects of starvation on body composition and cold tolerance in the collembolan Orchesella cincta and the isopod Porcellio scaber

The effects of long-term starvation on the body composition of the isopod Porcellio scaber (Latreille) and the collembolan Orchesella cincta (L.) were studied, by determining the body composition in starved and fed animals. A period under summer conditions (19 degrees C, 75% RH and L/D 16/8 photoperiod), was followed by a period under winter conditions (5 degrees C, 75% RH and LD 6/18 photoperiod). O. cincta was held under summer conditions for 3weeks, during which its protein and lipid content decreased, while its water content increased. In P. scaber, the same occurred during the 6weeks they were kept under summer conditions. During subsequent weeks under winter conditions, changes in cold tolerance of the animals were investigated. Cold tolerance and haemolymph osmolality were measured once a week. Starved animals had lower cold tolerance than fed ones. For P. scaber a decreased haemolymph osmolality was found in starved animals compared to fed ones. This is assumed to be caused by a combination of the consumption of carbohydrates out of the haemolymph and of protein reserves and the accumulation of body water. O. cincta appeared to be capable of osmoregulation, as haemolymph osmolality did not differ between starved and fed animals, despite differences in body water content. Decreased cold tolerance in starved animals of both species may be caused by increased water content or, more probably, by the decrease in reserves needed to produce cryoprotective substances.     

Developmental stages and chemical composition in embryos of the cockroach, Diploptera punctata, with observations on the effect of diet

A developmental time-table has been established for the embryos of viviparous Diploptera punctata. The percentage of gestation time occupied by pre-dorsal closure stages is only 19 per cent compared to 40 or 50 per cent in non-viviparous species. The increase in wet weight of the embryos begins several days before dorsal closure and continues throughout gestation. The increase in dry weight, protein, carbohydrate, and uric acid does not begin until shortly after dorsal closure but thereafter parallels the increase in wet weight.The increase in oöcyte protein during vitellogenesis is tenfold, less than in oviparous or ovoviviparous species. But the increase in embryo protein during gestation is sixtyfold; this characterizes viviparity in D. punctata.Although total lipid increases during gestation, lipid as a percentage of wet weight decreases most rapidly before dorsal closure and less rapidly there-after. It is suggested that before dorsal closure lipid is the major energy source for development. After dorsal closure the embryos are able to drink through their mouths the fluid nutrient provided by the mother.The ultimate source of nutrients required by developing embryos is the maternal diet during gestation. Females starved from ecdysis do not produce young; females fed only sugar from ecdysis produce viable larvae but suffer loss in body weight. Embryos from such females, although normal in length, are deficient in protein.     

Physiological and metabolic adjustments of Hoplosternum littorale (Teleostei,Callichthyidae) during starvation

All animals face the possibility of limitations in food resources that could ultimately lead to mortality caused by starvation. The primary goal of this study was to characterize the various physiological strategies that allow fish to survive starvation. A multiparametric approach, including morphological biomarkers, blood plasma metabolites, oxidative stress and energy reserves, was used to assess starvation effects on the fish Hoplosternum littorale. Adult specimens were maintained at four experimental groups: control (fed ad libitum), and starved (not fed) fish for 7 and 28 days. Significant changes were observed not only after 28 days, but also after 7 days of starvation. In the shorter period, the hepatosomatic index as well as plasma triglycerides and glucose were significantly lower in starved fish than in the control ones. These results were accompanied by reduced lipid, glycogen and protein reserves in liver and diminished glycogen content in muscle, suggesting the need of these macromolecules as fuel sources. In addition, increased antioxidant enzyme activities were observed in gills, without evidence of oxidative stress in any of the evaluated tissues. Most significant differences were found in 28-days starved fish: total body weight together with the hepatosomatic index was lower when compared to control fish. The plasmatic metabolites tested (glucose, triglyceride, cholesterol and protein), all energy reserves in liver and glycogen content in muscle decreased in 28-days starved fish. Lipid oxidative damage was reported in liver, kidney and brain, and antioxidant enzymes (GST, GR, GPx and CAT) were activated in gills. According to the multivariate analysis, oxidative stress markers and metabolic parameters were key biomarkers that contributed in separating starved from fed fish. Our study allowed an integrated assessment of the fish response to this particular condition.     

The influence of starvation and copper exposure on the composition of the dorsal carapace and distribution of trace metals in the shore crab Carcinus maenas (L.)

1. The influence of starvation and copper exposure on the composition of the carapace of the shore crab, Carcinus maenas has been investigated. The effects of the concentrations of selected trace metals in the carapace and midgut gland have also been examined.2. Differences in nutritional state did not affect the concentrations or relative proportions of the principle carapace components (calcium, chitin and protein), but starvation was associated with a reduction in carapace copper concentration. Copper concentration in the midgut gland increased in “starved” crabs, while midgut gland zinc and calcium concentrations remained unchanged.3. Starvation in combination with copper exposure (0.5 mg Cu/1) resulted in alterations in both carapace composition and trace metal loads. Carapace calcium concentrations were reduced significantly following copper exposure irrespective of the nutritional state of the crabs. However, the reduction was more marked in “fed” crabs than in “starved” animals.4. Copper-exposed crabs exhibited raised carapace copper concentrations while carapace zinc concentrations were depressed. Such changes were most pronounced in copper-exposed “starved” crabs.5. Calcium concentrations in the midgut glands of “starved” copper-exposed animals were significantly elevated compared with those in either control or “fed”, copper-exposed crabs.6. The findings are discussed with regard to their ecotoxicological significance.     

Hypolipemia,hypoglycemia, and inactivation of glycogen phosphorylase in Locusta migratoria

Feeding starved adult migratory locusts, Locusta migratoria, caused decreases of hemolymph lipid concentrations and of the percentage of active fat body glycogen phosphorylase which suggested that a molecule(s) from the neurosecretory system or the midgut may have been released to regulate metabolism. Fat body phosphorylase was also inactivated after insects were transferred from 0 to 25 ° C. In adults with elevated hemolymph lipid levels after the injection of small doses of corpus cardiacum extract (CC), feeding did not induce a decrease in hemolymph lipid concentrations. It appears that the processes initiated by feeding could not override the effects of the continued presence of adipokinetic hormone(s) (AKHs) in the hemolymph or their long-term effects. Aqueous, methanolic, or ethanolic extracts of brains or storage lobes (SL) of fed locust CC did not lead to decreases of hemolymph lipid concentrations. Bovine insulin was equally inactive when tested at doses which were previously reported to reduce lipid levels. Fractions of ethanolic brain extracts from 3-day-starved males collected after high-performance size-exclusion chromatography, however, produced hypoglycemic effects in fed males. Two biologically active fractions were found, one with high (≥ 10 kDa) and one with low molecular weight (approximately 1 kDa). © 1995 Wiley-Liss, Inc.     

Further studies on the effects of dehydroepiandrosterone on hepatic metabolism in BHE rats

Two experiments were conducted to determine the effects of dehydroepiandrosterone (DHEA) on de novo fatty acid synthesis and oxygen consumption in BHE rats fed a 65% glucose diet. In Experiment 1, starved glucose-refed rats were injected ip with 120 mg of DHEA/kg body wt and hepatic de novo fatty acid synthesis was measured. DHEA-treated rats synthesized less fatty acid in response to starvation refeeding than nontreated rats. In Experiment 2, weanling rats were fed the glucose diet for 4 weeks. One-hundred twenty milligrams of DHEA/kg were injected daily for 3 weeks. Body weight gain, epididymal fat pad weight, and carcass lipid were less in the DHEA-treated rats than in the control rats. Mitochondrial respiration was less and liver size was greater in DHEA-treated rats compared with control rats. Whole body oxygen consumption was increased in DHEA-treated rats, suggesting that this steroid might be stimulating futile energy cycles involving lipid and protein turnover possibly through its effect on glucocorticoid and thyroid hormone function.     

Effect of dietary lipid content on lipid transport and storage during larval development of Manduca sexta

Manduca sexta larvae were raised on diets containing either 1.2% fat (control diet), 5.9% fat (high-fat diet) or on a fat-free diet. Insects raised on the control and high-fat diets did not differ significantly in body weight, whereas animals raised on the fat-free diet were significantly smaller. The fat content of the diet had no effect on the hemolymph concentration of lipophorin. During the larval period, lipophorin isolated from animals on the high-fat diet contained more lipid, and lipophorin isolated from animals on the fat-free diet contained less lipid than lipophorin isolated from control animals. However, lipophorin isolated from animals during the prepupal period had the same composition regardless of diet. Compared to controls, animals on the high-fat diet had a larger mass of fat body which contained more stored triacylglycerol, while animals on the fat-free diet had a smaller mass of fat body which contained less stored triacylglycerol. As the fat content of the diet was increased, the fatty acid composition of fat body triacylglycerols reflected more closely that of the dietary lipid.     

Role of glycerol 3-phosphate and glycerophosphate acyltransferase in the nutritional control of hepatic triacylglycerol synthesis

1. Glycerol 3-phosphate content of isolated hepatocytes from starved rats and of glycogen-depleted hepatocytes from fed rats was low and severely limited triacylglycerol synthesis. 2. Raising the glycerol 3-phosphate content by addition of precursors to the cells resulted in a hyperbolic-like relationship between triacylglycerol synthesis and cellular glycerol 3-phosphate content. Statistical analysis of the curves showed no significant differences between the nutritional states either at saturating or at subsaturating glycerol 3-phosphate content. 3. V_max. of glycerophosphate acyltransferase measured in homogenized hepatocytes was decreased by 30–40% in starvation. There was no change in apparent K_m for glycerol 3-phosphate. Since at saturating glycerol 3-phosphate content esterification rates in hepatocytes of both nutritional states were identical, the enzyme is not limiting esterification under this condition. 4. At subsaturating glycerol 3-phosphate content the flux through glycerophosphate acyltransferase necessarily limits esterification. Therefore one would expect a decrease in esterification in starvation under this condition. This was the case when triacylglycerol synthesis was plotted against intracellular glycerol 3-phosphate concentration, calculated from the cellular glycerol 3-phosphate content and the intracellular water space, which was smaller in hepatocytes from starved rats. 5. The data obtained in hepatocytes were extrapolated to the intact liver by using the number of parenchymal cells per g of liver as determined from marker-enzyme analysis and the liver weight per 100g body weight. The extrapolation suggested that glycerol 3-phosphate is limiting esterification in vivo for contents below 0.3–0.4 and 0.5–0.65μmol/g for livers from fed and starved animals respectively. Also for a given fatty acid load and a glycerol 3-phosphate content below 0.3μmol/g the liver may esterify less in the starved state. However, at the glycerol 3-phosphate contents measured in freeze-clamped livers (0.30 and 0.44μmol/g for the fed and starved state respectively), livers in both nutritional states seemed capable of esterifying similar amounts of fatty acids.     

A third component causing random variability beside environment and genotype. A reason for the limited success of a 30 year long effort to standardize laboratory animals?

This paper is a review of experiments, performed in our laboratory during the past 20 years, designed to analyse the significance of different components of random variability in quantitative traits in laboratory rats and mice. Reduction of genetic variability by using inbred strains and reduction of environmental variability by highly standardized husbandry in laboratory animals did not remarkably reduce the range of random variability in quantitative biological traits. Neither did a tremendous increase of the environmental variability (i.e., living in a natural setting) increase it. Therefore, the postnatal environment cannot be that important as the source of random variability. Utilizing methods established in twin research, only 20-30% of the range of the body weight in inbred mice were directly estimated to be of environmental origin. The remaining 70-80% were due to a third component creating biological random variability, in addition to the genetic and environmental influences. This third component is effective at or before fertilization and may originate from ooplasmic differences. It is the most important component of the phenotypic random variability, fixing its range and dominating the genetic and the environmental component. The Gaussian distribution of the body weights observed, even in inbred animals, seems to be an arrangement supporting natural selection rather than the consequence of heterogeneous environmental influences. In a group of inbred rats, the males with the highest chance of parenting the next generation were gathered in the central classes of the distribution of the body weight.     

Glucose metabolism in the mucosa of the small intestine. Changes of hexokinase activity during perfusion of the proximal half of rat small intestine

1. The effect of perfusion on the activities of hexokinase and lactate dehydrogenase was studied in the proximal half of the small intestine of fed and starved rats. 2. Perfusion of preparations from starved rats with a medium containing glucose caused a significant increase in hexokinase activity of the particle-free supernatant. The increase in activity was observed as early as 5min after the start of perfusion and persisted for up to 66min of perfusion. No increase in hexokinase activity of the particle-free supernatant was observed when a medium containing mannitol was used. As a further control, preparations from fed rats were perfused under the same conditions. With the medium containing glucose, the hexokinase activity of the particle-free supernatant remained unchanged during the first 15min of perfusion and thereafter fell gradually until, after 66min of perfusion, 73% of the original activity was retained. 3. The activity of lactate dehydrogenase in the particle-free supernatant prepared from the proximal half of the untreated small intestine of starved rats was significantly lower than in corresponding preparations from fed animals. However, it did not change significantly on perfusion with media containing either mannitol or glucose. 4. The distribution of hexokinase activity between total particulate fraction and particle-free supernatant was measured in preparations from starved rats after perfusion for 5–10min. In preparations that had not been perfused the ratio of hexokinase activity in total particulate fraction/particle-free supernatant was significantly higher in starved than in fed animals. After perfusion with a medium containing glucose, the total homogenate activity had not changed significantly, whereas the ratio of hexokinase activity in total particulate fraction/particle-free supernatant decreased significantly and approached the value obtained with fed animals. 5. The results agree with the view that the glucose-dependent increase of hexokinase activity in the soluble cell compartment as observed in vivo and in vitro in the intestinal mucosa of starved rats is brought about by a release of hexokinase activity from a particulate subcellular structure(s).     

The effects of a pure protein diet on the amino-acid composition of Neomysis integer (Leach)

Neomysis integer (Leach) was fed lipid- and carbohydratc-free albumin or kaolin (starved) for up to eight days and the ability of the animal to maintain its total protein and free and protein amino-acid patterns was examined. Considerable effects on the body composition were seen although the amino-acid patterns of the diet and tissue protein were similar. Total protein was reduced to the same extent in both starved and albumin-fed animals, despite some utilization of the dietary protein. Conversely, the level of total free amino acid was reduced in starved animals but not in the protein-fed mysids. The amino-acid composition of the protein hydrolysates was altered after both starvation and feeding and the patterns produced indicated that protein synthesis, as well as catabolism had occurred in the albumin-fed animals. There were also changes in the composition of the free amino-acid pools of both starved and fed animals. In the starved samples taurine, aspartate, and arginine appeared to be conserved, while in the albumin-fed animals alanine, leucine, tyrosine and phenylalanine were substantially and consistently decreased, and arginine increased, in concentration. Although the results showed that the quality of the protein fraction was altered by the albumin diet, the amino-acid composition of the albumin had no direct effect on the resultant composition of either the protein hydrolysate or the free amino-acid pool in protein-fed animals.     

Effects of sugar feeding on carbohydrate and lipid metabolism in a parasitoid wasp

Lifetime patterns of carbohydrate and lipid metabolism were compared in starved and sucrose‐fed adults of the parasitoid Macrocentrus grandii (Goidanich) (Hymenoptera: Braconidae). As expected, sucrose‐fed individuals lived longer than did starved individuals. Macrocentrus grandii males and females eclosed with levels of simple storage sugars (presumably primarily trehalose) and glycogen that were below maximum levels recorded from sucrose‐fed parasitoids. Both of these nutrients dropped to very low levels in starved individuals within 4 days post‐emergence and were maintained at high levels in sucrose‐fed individuals throughout their lives. Lipid reserves at emergence represented the highest lipid levels for both sexes in the two diet treatments, with levels declining over the lifetimes of males and females from both diet treatments. Our results therefore suggest that dietary sucrose is used to synthesize trehalose and glycogen, but not lipids in M. grandii. Also, in contrast to the patterns observed for the simple sugars and glycogen, lipid levels in starved individuals did not drop below levels observed in sugar‐fed individuals. The average number of mature eggs carried by females at emergence was 33 and increased to approximately 85 in sucrose‐fed and 130 in starved females by the age of 5 d in the absence of hosts. The egg maturation rate was therefore higher in starved than in sugar‐fed females. Potential explanations for this unexpected result are discussed.     

The effects of feeding condition and dietary lipid level on lipoprotein lipase gene expression in liver and visceral adipose tissue of red sea bream Pagrus major

The effects of feeding condition and dietary lipid level on lipoprotein lipase (LPL) gene expression in the liver and visceral adipose tissue of red sea bream Pagrus major were investigated by competitive polymerase chain reaction. Not only visceral adipose tissue but also liver of red sea bream showed substantial LPL gene expression. In the liver, starvation (at 48 h post-feeding) drastically stimulated LPL gene expression in the fish-fed low lipid diet, but had no effect in the fish fed high lipid diet. Dietary lipid level did not significantly affect the liver LPL mRNA level under fed condition (at 5 h post-feeding). In the visceral adipose tissue, LPL mRNA number per tissue weight was significantly higher in the fed condition than in the starved condition, irrespective of the dietary lipid levels. Dietary lipid levels did not affect the visceral adipose tissue LPL mRNA levels under fed or starved conditions. Our results demonstrate that both feeding conditions and dietary lipid levels alter the liver LPL mRNA levels, while only the feeding conditions but not dietary lipid levels cause changes in the visceral adipose LPL mRNA level. It was concluded that the liver and visceral adipose LPL gene expression of red sea bream seems to be regulated in a tissue-specific fashion by the nutritional state.     

The response of the haemoglobin system of fed and starved rainbow trout, Salmo gairdneri Richardson, to bleeding

Seven days after a 15% reduction in blood volume by bleeding, the haemoglobin system of rainbow trout showed a modification in relative abundance of two of the four haemoglobins present in the haemolyate. The least anodic non-Root effect haemoglobin increased proportionally whereas the major component, with its Root effect properties, showed a decline. A total of 30 days of starvation did not influence the relative proportions of the fractions. However, bleeding of these starved S. gairdneri provoked a shift similar to that of fed trout. In this case, however, both non-Root haemoglobins, and the minor Root fraction, increased proportionally. The major Root fraction declined. The response of the starved group was more acute since all four components were significantly affected in contrast to two fractions in fed animals.     

Carbohydrate metabolism in starved fifth instar larvae of Manduca sexta

The influence of starvation on carbohydrate metabolism in fifth instar larvae of Manduca sexta was studied. The percentage of active fat body glycogen phosphorylase increased from 10% to approximately 50% within 3 h of starvation; afterward the enzyme was slowly inactivated. The increase of phosphorylase activity might have been caused by a peptide(s) from the CC. The amount of fat body glycogen in starved animals decreased over 24 h by approximately 20 mg. The released glucose molecules seem to be converted mainly to trehalose because the hemolymph trehalose concentration in starved animals was always slightly higher than in the fed controls, and the glucose concentration decreased even when phosphorylase was activated. The chitosan content in starved larvae increased during the first 9 h of treatment to the same extent as in fed controls. It is suggested that fat body glycogen phosphorylase was activated during starvation to provide substrates for chitin synthesis and energy metabolism.