Effect of aluminum and iron on lipid metabolism in aquatic invertebrates

Methods of thin-layer, gas-liquid, and liquid chromatography were applied to the study of the effect of various concentrations of aluminum and iron salts on the contents of phospholipids, cholesterol, and fatty acids in the aquatic invertebrate Hydropsyche contubernalis L. (Trichoptera). It was found that the effect of the metals under study on lipid contents in living organisms depended on the composition of the aqueous medium and concentrations of the metals. Aluminum and iron altered the value of the cholesterol-to-phospholipid molar ratio. In the absence of lethal effects, this was indicative of attempts to switch adaptational biochemical mechanisms to stabilize cellular structures.     

Effect of cobalt ions on lipid and sterol metabolism in the marine invertebrates Mytilus galloprovincialis and Actinia equina

The lipid and sterol fractions of the mussel Mytilus galloprovincialis and the anemone Actinia equina were analyzed before and after incubation with cobalt ions. There were significant changes in the lipid and sterol composition, strongly depending on the cobalt ions concentrations. The changes in the lipid composition of both invertebrates were different for neutral lipids and phospholipids. These changes concern the length of the fatty acid chains as well as their unsaturation. The cobalt ions inhibited the oxidation of sterols and their alkylation at C-24. Because of these results we can assume that some of the changes caused by cobalt ions might possess adaptive value.     

Aspartic proteinases in fishes and aquatic invertebrates

1. The literature on molecular properties and physiological role of aspartic proteinases in fishes and aquatic invertebrates has been reviewed. 2. Pepsins have not been detected in invertebrates, and apparently cathepsin D, as well as other cathepsins, act both as digestive and lysosomal enzymes in many of these animals. The molecular properties of invertebrate cathepsin D correspond with cathepsin D in fishes and mammalians. 3. Fishes with a true stomach have pepsinogen secretion. Fish pepsins have higher pH optimum and are less stable in strong acid conditions than mammalian pepsins. They are very efficient at low temperatures, but less thermostable than mammalian pepsins. 4. Many fishes have two significantly different pepsins: Pepsin I and Pepsin II, which digest haemoglobin at a maximal rate in the pH ranges 3-4 and 2-3 respectively. Usually the pI of Pepsin I is in the range 6.5-7, whereas pI of Pepsin II is about 4. 5. Fish Pepsin I and cathepsin D have very similar molecular properties, and a hypothesis proposing that cathepsin D is the ancestor enzyme of aspartic proteinases in higher animals is presented.     

Symbioses between aquatic invertebrates and algae

The characteristics of symbiotic associations between algae and invertebrates are outlined, using a number of the better-studied examples. The common assumption that these symbioses are mutualistic ones is discussed. In the present state of knowledge, it is impossible to determine the nature of these associations, but the evidence favours the view that the animal hosts benefit markedly from the presence of the algae, but that the possibility that the algae may be harmed (i.e. parasitized) by the animals cannot be dismissed. Some general lines of investigation which would help to define these relationships are suggested.     

Effect of dehydration on lipid metabolism

Control of 25 sportsmen-wrestlers determined that accelerated loss in weight leads to a significant increase of ketone bodies evacuation with urine. The loss in weight for a 10-11 days period before a competition results in a less pronounced hyperketonuria. In experiment on rats it is shown that 48 and 98 hour hyperthermia and dehydration lead to the inhibition of the glucose-6-phosphate dehydrogenase activity in the liver. The mentioned permits supposing that under indicated conditions the inhibition of fat acid synthesis caused by NADPH2 and an increase of ketone bodies and cholesterol synthesis are observed.     

Effect of aluminum exposure on pteridine metabolism

Occupational and environmental aluminum (Al) exposure cause serious health problems by interaction with biological systems. Al is one of the most documented metals because its cellular targets are unclear biochemical processes and membranes of organisms. The major aim of the present study was to investigate the alteration of serum and urine aluminum in occupational exposure and to observe whether the metal exposure could cause any changes in pteridine-pathway-related critical compounds such as urinary neopterin and biopterin and blood dihydropteridine reductase (DHPR). In this study, determination of the metal concentrations was carried out in Al-exposed workers (n=23) and healthy volunteers (n=18) by using a tomic absorption spectrometer. DHPR enzyme activity and levels of neopterin and biopterin were detected by spectrophotometric and high-performance liquid chromatographic methods, respectively. It was found that occupational exposure to the metal led to a statistically significant increase in serum Al levels compared to the controls (p<0.05). At the same time, urinary neopterin and biopterin concentrations of the exposed group were higher than nonexposed subjects (both p<0.05). The correlations among Al levels and DHPR activity, magnesium concentration in serum and urine, working years, smoking status, and age were evaluated.     

Body mass and excretion of phosphorus in aquatic invertebrates

Empirical materials on the dependence of the intensity of mineral phosphorus excretion (Ex) on the body mass (W) in invertebrates are summarized. The parameters of the average dependence of Ex on W in animals at 20°C are determined. The main factors that influence the parameters of this dependence are discussed. It is shown that the decrease of Ex with an increase of W in animals is, as a rule, more significant compared with the decrease in the intensity of metabolism.     

Effects of excess dietary iron and fat on glucose and lipid metabolism

PurposeDiets rich in fat and energy are associated with metabolic syndrome (MS). Increased body iron stores have been recognized as a feature of MS. High-fat diets (HFs), excess iron loading and MS are closely associated, but the mechanism linking them has not been clearly defined. We investigated the interaction between dietary fat and dietary Fe in the context of glucose and lipid metabolism in the body.MethodsC57BL6/J mice were divided into four groups and fed the modified AIN-93G low-fat diet (LF) and HF with adequate or excess Fe for 7 weeks. The Fe contents were increased by adding carbonyl iron (2% of diet weight) (LF+Fe and HF+Fe).ResultsHigh iron levels increased blood glucose levels but decreased high-density lipoprotein cholesterol levels. The HF group showed increases in plasma levels of glucose and insulin and insulin resistance. HF+Fe mice showed greater changes. Representative indices of iron status, such hepatic and plasma Fe levels, were not altered further by the HF. However, both the HF and excess iron loading changed the hepatic expression of hepcidin and ferroportin. The LF+Fe, HF and HF+Fe groups showed greater hepatic fat accumulation compared with the LF group. These changes were paralleled by alterations in the levels of enzymes related to hepatic gluconeogenesis and lipid synthesis, which could be due to increases in mitochondrial dysfunction and oxidative stress.ConclusionsHigh-fat diets and iron overload are associated with insulin resistance, modified hepatic lipid and iron metabolism and increased mitochondrial dysfunction and oxidative stress.     

Effects of dietary supplementation with aluminum and citrate on iron metabolism in the rat

The metabolism of iron (Fe) has been shown to interact with that of aluminum (Al) in relation to intestinal absorption, transport in the blood plasma, and the induction of lipid peroxidation and cellular damage. Also, dietary supplementation with citrate has been shown to increase the absorption of both metals and, in the presence of high intakes of Fe and Al, leads to excessive accumulation of both metals in the body. In this study, the likely interaction between Al and internal Fe metabolism was investigated using rats fed diets that were either deficient, sufficient, or loaded with Fe, with or without the addition of Al and sodium citrate. These diets commenced when the rats were 4 wk old and were continued for 9–11 wk. At that time, Fe metabolism as assessed by measurement of organ uptake of⁵⁹Fe and¹²⁵I-transferrin, after iv injection of transferrin labeled with both isotopes, plus measurement of tissue concentrations of nonheme Fe and Al. The Fedeficient diet and Fe-loaded diet led to states of Fe deficiency and Fe overload in the rats, and supplementation of the diet with Al increased Al levels in the kidneys, liver, and femurs, but, generally, only when the diet also contained citrate. Neither Al nor citrate supplementation of the diet had any effect on nonheme Fe concentrations in the liver, kidney, or brain, or on the uptake of⁵⁹Fe or¹²⁵I-transferrin by liver, kidney, brain, or spleen. Only with the femurs was a significant effect observed: increased⁵⁹Fe uptake in association with increased Al intake. Therefore, using this animal model, there was little evidence for interaction between Fe and Al metabolism, and no support was obtained for the hypothesis that dietary supplementation with Fe and citrate can lead to excessive Fe absorption and deposition in the tissues.     

Effect of exercise on iron metabolism in horses

We investigated the effect of exercise on iron metabolism in horses. Four horses were walked on a mechanical walker for 1 wk (pre-exercise). They then performed moderate exercise on a high-speed treadmill in the first week of the exercise and relative high in the second week and high in the third week. Serum iron was significantly lower in the third week of exercise than in the pre-exercise. Transferrin saturation (TS) was significantly lower in the first and third weeks of exercise than in the pre-exercise. Serum haptoglobin was significantly lower in the first week of exercise than in the pre-exercise and further significantly lower in the second and third weeks than in the first. The packed cell volume did not change during the experiment. The exercise significantly increased the apparent absorption of iron. Urinary iron excretion did not change throughout the experiment. Sweat iron loss did not change during the exercise. The exercise significantly increased iron balance. We considered that hemolysis is induced by moderate exercise and is further enhanced by heavy exercise, which decreases serum iron and TS. However, the increase in iron absorption compensates for the adverse effect of exercise on iron status. Therefore, exercise does not induce anemia in horses.     

Toxicity and bioaccumulation of cadmium and lead in aquatic invertebrates

Cadmium toxicity and lead toxicity to four species of insects (Pteronarcys dorsata, Hydropsyche betteni, Brachycentrus sp. and Ephemerella sp.), one snail (Physa integra) and one amphipod (Gammarus pseudolimnaeus) were determined during 28-day exposures. The 28-day LC50 values for cadmium-exposed snails and lead-exposed amphipods were eleven and four times lower than the 7- and 4-day (96 h) values for these metals, respectively. Lowest effect concentrations obtained after 28 days for cadmium-exposed mayflies (Ephemerella sp.) and snails and lead-exposed amphipods were similar to those affecting fish exposed over their complete life cycle in water of similar quality. Lethal threshold concentrations were not observed for species exposed to either metal, indicating that possible effects could occur at lower concentrations during longer exposure periods. Cadmium and lead concentrations in the animals tested generally increased with increasing water concentrations and were up to 30,000 and 9000 times greater than corresponding metal concentrations in the water.     

Leaf-eating invertebrates as competitors of aquatic hyphomycetes

Summary Leaf-eating invertebrates selectively ingest leaf areas rich in fungal cells. The effect of this process on coincident and cumulative species diversity (species numbers and evenness) of the fungi was studied on 3 substrates (oak leaves, larch and spruce needles) in 2 hardwater and 2 softwater streams. Cumulative species number of colonizing fungi follows the equation S=k·A ^z(A=area below decay curve of the substrate, k=substrate-specific constant, Z=0.47). Higher feeding activity means faster weight loss of the substrate which leads to lower species richness of the fungi. The opposite is true for early successional stages on larch needles. Evenness of the fungi (distribution of individuals among species) is negatively correlated with feeding intensity by invertebrates, as measured by increased decay rates. The overall effect of leaf-eating invertebrates on aquatic hyphomycetes resembles that of potent competitors preempting substrate otherwise used by a late successional tail of relatively rare fungi.     

Effect of iron on growth and lipid accumulation in Chlorella vulgaris

The economic feasibility of algal mass culture for biodiesel production is enhanced by the increase in biomass productivity and storage lipids. Effect of iron on growth and lipid accumulation in marine microalgae Chlorella vulgaris were investigated. In experiment I, supplementing the growth media with chelated FeCl3 in the late growth phase increased the final cell density but did not induce lipid accumulation in cells. In experiment II, cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into new media supplemented with five levels of Fe3+ concentration. Total lipid content in cultures supplemented with 1.2 x 10(-5) mol L(-1) FeCl3 was up to 56.6% biomass by dry weight and was 3-7-fold that in other media supplemented with lower iron concentration. Moreover, a simple and rapid method determining the lipid accumulation in C. vulgaris with spectrofluorimetry was developed.     

Effect of diosgenin on lipid metabolism in rats.

The purpose of this study was to determine whether diosgenin suppresses cholesterol absorption in rats, and to examine relevant changes in cholesterol and bile acid metabolism. Diosgenin fed with the diet for 1 week inhibited cholesterol absorption as determined by the serum isotope ratio technique, as well as by measuring in the feces the amount of unabsorbed radioactivity from orally administered [3H]cholesterol. In addition, diosgenin suppressed the serum and liver uptake of radioactivity from co-administered [3H]cholesterol as well as the accumulation of liver cholesterol in the cholesterol-fed rat; diosgenin was substantially more active than cholestyramine or beta-sitosterol. In vitro, diosgenin had no effect on the activity of rat pancreatic esterase. Diosgenin decreased the elevated cholesterol in serum LDL and elevated cholesterol in the HDL fraction of cholesterol-fed rats; diosgenin had no effect on serum cholesterol in normocholesterolemic rats. In contrast to cholestyramine, diosgenin markedly increased neutral sterol excretion without altering bile acid excretion; in vitro, diosgenin had no effect on bile acid binding. Diosgenin treatment increased hepatic and intestinal cholesterol synthesis as well as the activity of hepatic HMG CoA reductase. This was accompanied by increased biliary concentration of cholesterol, but not of bile acids. Diosgenin had no effect on cholesterol synthesis when added to normal rat liver homogenates. It was concluded that diosgenin interferes with the absorption of cholesterol of both exogenous and endogenous origin; such interference is accompanied by derepressed, i.e., increased, rates of hepatic and intestinal cholesterol synthesis. The increased unabsorbed cholesterol together with enhanced secretion of cholesterol into bile resulted in increased excretion of neutral sterols without affecting the biliary and fecal excretion of bile acids.     

Effect of aluminum and deferoxamine on biliary iron elimination in the rat

Iron (Fe) and aluminum (Al) eliminations in bile were studied in rats after intravenous administration of Fe, Al, deferoxamine mesylate (Desferal, Ciba) (DFA), feroxamine (FeA), and aluminoxamine (AlA) at the dose of 50 mumole/kg body weight. Bile was obtained from the bile duct of anesthetized rats, and the concentrations of Fe and Al in bile were measured by an inductively coupled plasma optical emission spectrometer. The results showed an increase of Fe elimination in bile, from 10 to more than 20 mumole/liter after Fe and also after Al administration; an increase to about 350 mumole/liter after DFA administration; to 250 mumole/liter after FeA administration; and to 100 mumole/liter after AlA administration. Aluminum elimination in bile was increased only after Al and particularly after AlA administration but not after Fe and FeA administration. In conclusion, Al and AlA were able to increase Fe elimination in bile. Thus Al overload observed in hemodialyzed patients may induce an excessive iron loss in bile and partly explain microcytic anemia.