Cadmium toxicity to the freshwater amphipod Gammarus pulex (L.) during the moult cycle

SUMMARY. 1. The toxicity of cadmium to mature Gammarus pulex at different stages in the moult cycle is described.
2. Immediate post-moult animals are significantly more sensitive than intermoult specimens at cadmium concentrations between 1.0 and 0.1 mg 1⁻¹ but not at 0.03 or 0.01 mg Cd 1⁻¹.
3. At a calcium concentration of 40mgl⁻¹, post-moult animals undergo recalcification within 7 days and thereafter there is little variation in their response to cadmium.
4. External calcium concentrations of 40 and 115mg 1⁻¹ do not affect cadmium toxicity but at 180 mg Ca1⁻¹ the sensitivity of immediate post-moult specimens is significantly reduced.
5. The results are discussed with regard to the protection of G. pulex by present water quality standards.     

Carbohydrate and lipid metabolism during the last larval moult of the tobacco hornworm, Manduca sexta

Abstract. At 25°C and with a light regime of 17 h light and 7h dark, the last larval moult of the tobacco hornworm, Manduca sexta , lasts approximately 32 h, during which profound changes of metabolism were observed. At the onset of the moult, which coincides with the cessation of feeding, the proportion of active fat body glycogen phosphorylase increased from 10 (-2h) to 25–30% (Oh). A biphasic pattern with peak activities of 45–50% after t – 12 h and again just prior to the shedding of the cuticle (32 h) was subsequently observed. Haemolymph trehalose concentration decreased significantly from c. 35 (Oh) to 20mM (8h), but then recovered to an intermediate level (30mM; 12h). After completion of the moult, the trehalose concentration was 35–40 mM. The haemolymph glucose level in feeding fourth instar larvae was 4–5 mM, but decreased sharply before the onset of the moult to c. 1 mM, followed by a slow 6-fold increase over the next 20h. Prior to the shedding of the cuticle, the glucose level dropped again dramatically. The haemolymph lipid level increased slowly from an initial level of 1.2–1.4mg/ml during the early part of the moult, reaching a maximum of 1.8mg/ml after /= 16 h. Afterwards, a decrease of c. 50% was observed until ecdysis occurred. Oxygen consumption per animal decreased steadily from 30–35 μl/min pre-moult by approximately 70% to c. 10 μl/min but started to increase about 5 h before the animals resumed feeding.     

Free amino acids in claw muscle and haemolymph from Australian freshwater crayfish at different stages of the moult cycle

Amino acids were measured in claw muscle and haemolymph in the freshwater decapod crustacean, Cherax destructor, at different stages of the moult cycle. The total pool of amino acids in muscles from animals in intermoult (97+/-13 mmol kg(-1) muscle), premoult (80+/-20 mmol kg(-1)) and postmoult (97+/-19 mmol kg(-1)) were not significantly different. Despite the relatively stable total pool of amino acids, there were changes in the concentrations of alanine, glutamine and proline over the moult cycle. Compared to intermoult, claw muscles from animals in premoult had a lower concentration of proline, and animals in postmoult had higher concentrations of alanine and glutamine, but lower concentrations of proline. Concentrations of alanine and glutamine in claw muscle of animals in postmoult were higher and proline concentrations lower than in the same animals during the premoult stage. The concentration of proline in haemolymph was lower in animals in premoult and postmoult compared to intermoult. The total amino acid pool in the claw muscle of Cherax destructor did not change significantly over the moult which is distinctly different to the changes in amino acids reported in the claw muscles of marine decapod crustaceans.     

Calcium,phosphorus and adenylate levels and Na(+)-K(+)-ATPase activities of prawn,Macrobrachium nipponense,during the moult cycle

Changes in calcium and phosphorus concentrations, adenylate (AMP, ADP and ATP) levels, and ratios and ATPase activities of Macrobrachium nipponense were investigated during the moult cycle. Ca level in the exoskeleton was lowest in early postmoult (stage A), increasing at stages B and through intermoult (stage C) and peaking in premoult (stage D1 and D2). The P concentrations in the exoskeleton and muscle in late premoult and early postmoult stages were higher than those at other moult stages, and were lowest in the intermoult. Muscle adenylate energy charge (AEC) changed with moult stages, and was in agreement with the change in inorganic P level in the muscle. AEC may be a direct indicator of energy metabolic activity during the moult cycle. ATP/ADP and ATP/AMP ratios in premoult and postmoult stages were higher than that in intermoult stage. Na(+)-K(+)-ATPase activities of gills, muscles and hepatopancreatic of prawns were higher in early postmoult and late premoult animals, whereas they were lower in late postmoult, intermoult and early premoult animals. Gill residual ATPase activity was significantly higher in postmoult animals, while the peak value of hepatopancreatic residual ATPase activity appeared in intermoult stage.     

CALCIUM BALANCE AND MOULTING IN THE CRUSTACEA

1. Crustaceans have a high content of calcium, which is chiefly located in the skeleton as calcium carbonate. Calcium is generally the most abundant cation in the body. 2. During intermoult, the exoskeleton is usually fully calcified and the animal is in calcium equilibrium with its environment. 3. In the premoult stages calcium is resorbed from the skeleton and may be lost to the environment or stored within the body. Typically, losses are high and storage is small in aquatic species, whilst most terrestrial forms store much larger amounts of calcium and losses are reduced. Loss of calcium in soluble form by aquatic species must be by outward transport across the gills. 4. Calcium is stored in a variety of different ways, usually with a common taxonomic theme. The main forms are as calcium phosphate granules in cells of the midgut gland (Brachyura), gastroliths (Astacidea and some Brachyura), the haemocoel (some Brachyura) the posterior midgut caeca (Amphipoda) and the ventral portion of the body generally in the Isopoda. 5. At ecdysis, the skeleton is shed and the calcium remaining in it is lost from the body. 6. Recalcification begins immediately, or shortly after, ecdysis using calcium mobilized from the stores. Simultaneously, or when the stores are exhausted, other sources of calcium are utilized. These are calcium in the water (aquatic species), the food (aquatic and terrestrial species) and the exuviae (chiefly terrestrial species). 7. Marine species store little calcium and must obtain the bulk of their requirement (ca. 95%) from the water. Fresh-water species also store little calcium but have, seemingly, adapted to the lower availability of calcium by increasing the affinity of the calcium-absorbing mechanism. The rates of uptake of calcium are consequently similar in marine and fresh-water species. 8. A high degree of storage is essential for terrestrial crustaceans as they do not have access to a large aquatic reservoir of calcium. These large reserves enable the animals to reach an advanced stage of calcification, allowing the resumption of foraging and feeding necessary for completion of calcification. 9. The control of calcium metabolism during the intermoult cycle is poorly under stood. β Ecdysone appears to control the resorption of calcium and the formation of calcium stores during premoult, but the mechanism of control of calcium metabolism during postmoult and intermoult is unknown. 10. The concentration of calcium in the haemolymph of most species is high, but a large proportion of this is in non-ionized form. In premoult, total calcium levels rise as a result of calcium resorption but little change occurs in the concentration of ionized calcium. Postmoult generally sees a fall in blood calcium, sometimes below the intermoult value.     

Arginine utilization by Mycoplasma fermentans is not regulated by glucose metabolism: A 13C-NMR study

Abstract Electrofusion of protoplasts of two mutant strains of Hansenula polymorpha resulted in high fusion and hybrid yields when the calcium ions present in the conventional fusion medium replaced by zinc ions. The optimal fusion conditions were an alignment field of 0.4 kV cm⁻¹ strength and 2 MHz frequency for 30 s, followed by two consecutive pulses of 12 kV cm⁻¹ strength and 15 μs duration. With 0.05–0.1 mM zinc ions in the fusion medium an average clone number of 10⁴–10⁵ clones per 10⁸ input cells was reached. The presence of about 0.6 mM magnesium ions in the zinc fusion medium was essential.     

Rafting in Antarctic Collembola

Darwin was an early exponent of the importance of 'occasional means of dispersal' in accounting for the present-day distribution of plants and animals. This study examined the implications of capture on the water surface of meltwater and seawater for the local and long-range dispersal of Antarctic springtails. Individuals of the maritime Antarctic collembolan Cryptopygus antarcticus , were floated on tap water and seawater at 0, 5 and 10°C. LT₅₀s on seawater were 34 (10°C), 65 (5°C) and 75 (0°C) days. On tap water, LT₅₀s were 69 (10°C), 126 (5°C) and 239 (0°C) days. Less than 20% escaped from the water surface. A significantly greater proportion of springtails moulted on tap water and viable offspring were produced on both tap water and seawater. Comparison across treatments of survival of moulting and non-moulting individuals found significantly greater survival in moulting animals for three of the treatment combinations. It is suggested that moult exuviae facilitate survival on the water film through the simultaneous provision of a flotation aid and a source of nourishment – that is, an 'edible raft'. A separate experiment measuring changes in haemolymph osmolality over time on tap water and seawater at 2 and 5°C found significant differences in all treatments. Causes of mortality are discussed in relation to osmoregulatory failure and starvation.     

Ecophysiological diversity of alpine populations of Gammarus lacustris in relation to environmental calcium

1. The contribution of environmental calcium to ecophysiological diversity among populations of Gammarus lacustris was investigated by comparing five alpine lakes in France.
2. Calcium concentrations in the water varied with substratum lithology, ranging from 6 mg L^–1 in lakes on crystalline (igneous) rocks to 32.7 mg L^–1 in lakes on limestone, and up to 248 mg L^–1 in a lake with a gypsum environment.
3. The duration of the moult cycle and mortality rate were compared between populations by means of field and in situ laboratory and translocation experiments on adult males. Animals from water with low calcium concentrations showed a significantly longer moult cycle and higher mortality rate than those from water with high calcium concentrations. A significant increase in the duration of the moult cycle was observed in animals translocated to water of lower calcium concentration and vice versa.
4. These results suggest the existence of different physiological races of G. lacustris with an ecophysiological plasticity of calcium metabolism narrower than that of river-dwelling gammarids such as G. fossarum. This may be a consequence of geographic isolation among lacustrine populations together with the relatively stable environmental parameters in lakes.     

Growth, mineral uptake and skeletal calcium deposition in brown trout, Salmo trutta L., yolk-sac fry exposed to aluminium and manganese in soft acid water

In 30-day exposures in artificial soft water medium, survival of brown trout alevins was not affected by low pH (4.5,4.8, 5.4), by low calcium concentration (10.25 μmol l⁻¹) or by manganese (≤20 μmol l⁻¹), but was impaired by aluminium (6–8 μmol l⁻¹) at low calcium concentration (10 μmol l⁻¹) irrespective of pH (4.5 or 5.4). Manganese (6.6, 20 μmol l⁻¹) impaired net calcium uptake and calcium deposition in the skeleton at low calcium concentration (25 μmol l⁻¹) irrespective of pH. Aluminium (2–8 μmol l⁻¹) impaired gross development, net uptake of calcium, potassium and sodium, and calcium deposition in the skeleton, and slightly increased the net loss of magnesium, some of these effects being more severe at calcium concentration 10 μmol l⁻¹ than 50 μmol l⁻¹, and some more severe at pH 5.4 than pH 4.5. Net uptake of calcium and sodium were impaired at low pH (4.5, 4.8), and skeletal calcium deposition was impaired at low calcium concentration (10 μmol l⁻¹), but these effects of low pH and low calcium concentration were slight compared with those of the trace metals. The possible role of trace metals in reports of the deleterious effects on fish of low pH levels is discussed.     

The moult cycle of the terrestrial isopod Armadillo officinalis Duméril, 1816 (Crustacea: Isopoda: Oniscidea)

The present work focuses on the moult cycle of Armadillo officinalis. For a 100‐day period, 134 animals were observed and routinely examined with the aim of detecting distinctive morphological characters in the several stages and substages of the moult cycle and of disclosing their duration. Statistical tests and Poisson regression models with robust standard errors were used to investigate differences and relationships between moult and the size and gender of the animals. The appearance of the calcium carbonate deposits on the pereon sternites during the premoult stage was documented in detail, and three main substages were identified. The average duration of the premoult and of the biphasic ecdysis was about 12 and 1.5 days, respectively. This observation period, however, did not allow to establish a determined average duration of the intermoult stage, which was extremely variable. This stage lasted for 2 months or more in most of the cases observed, but about 1‐month‐long intermoult stages were also recorded. No statistically significant association was found between the number of moults and gender and size of the animals.     

Regulation of haemolymph sodium and potassium during dehydration in the cricket Teleogryllus oceanicus

ABSTRACT. Male crickets ( Teleogryllus oceanicus ) when dehydrated for 3 days lost 51% of their body water, and 65% of their haemolymph volume. Haemolymph osmolality rose from 391 to 572mOs/kg; [Na⁺] from 149 to 289 HIM; and [K⁺] from 13.0 to 26.3 mM. During dehydration 385 μig Na (expressed as NaCl) and 41 μug K (expressed as KCI) were removed from the haemolymph. Rehydration of the dehydrated insects failed to restore the Na⁺ and K⁺ concentrations to near their original levels. Approximately 62% of the missing Na⁺ was excreted, whilst five times the amount of K⁺ removed from the haemolymph was excreted. It is presumed that the excess represents K⁺ removed from intracellular fluid.     

Extracellular Calcium Concentration Affects Infectivity of Ichthyophthirius (Ciliophora) Theronts

Tomonts and their theront offspring of the hymenostomatid fish parasite Ichthyophthirius multifiliis were exposed to calcium levels from 0 to 0.8 mM Ca^2+. The survival and reproductive rates of tomonts in the absence of extracellular calcium were not significantly different from rates of tomonts provided calcium. Theronts that developed in the absence of calcium, however, were not infective for Ictalurus punctatus even when the extracellular magnesium concentration was doubled. Theronts that developed in 0.10 mM Ca²⁺ were infective (0.77 trophonts/mm² of pectoral fin) to essentially the same extent as theronts provided 0.33 mM Ca^2+. Infectivity of those provided 0.8 mM Ca²⁺ was 1.79 trophonts/mm² of fin, similar to that of theront controls. Theronts deprived of extracellular calcium as they developed contained significantly fewer secretory mucocysts than did theronts provided 0.1 to 0.8 mM Ca²⁺ although no significant differences among groups occurred with respect to abundance of crystalline or differentiating mucocysts. Theronts deprived of extracellular calcium also had swollen or enlarged mitochondria and abnormal crystalline mucocysts.     

Differential affinity of natural haemagglutinin of Macrobrachium rosenbergii towards vertebrate erythrocytes: effect of sex, size and moult stage on haemagglutination titre

Lectins play important role in innate immunity of animals. The affinity of the natural haemagglutinin of the giant freshwater prawn Macrobrachium rosenbergii towards vertebrate erythrocytes and its level with relation to sex, size and moult stages were studied. The strongest agglutinating titres in haemolymph of prawns were marked against guinea pig, chicken, Clarias batrachus, and rabbit erythrocytes, and the weakest towards cattle, dog, horse and goat erythrocytes. A moderately agglutinating titre was evident in duck and human erythrocytes. The haemolymph of adult, male or intermoult stage prawns weighing more than 100 g had the highest haemagglutinating activity as compared to their respective counterparts with varied responses observed towards various erythrocytes.     

Fertilization Potential of the Medaka Egg

Fertilization of the medaka egg in 10% Ringer's solution generates a depolarization of 4 mV just before the appearance of a characteristically longer hyperpolarization (25). The depolarization appears to be the result of a nonspecific leak triggered by sperm stimulation and the amplitude of the depolarization is thought to be independent of [Ca²⁺]_o (25). We have investigated the ionic dependence of this depolarization. An initial small depolarization (3–4 mV; duration, 5–8 sec) is followed by a rising phase of a spike-like depolarization in the range of 10–60 mV. The amplitude of this spike-like depolarization is propodional to log [Ca²⁺], ranging from 0.33–18 mM. Calcium antagonists, e.g. 10 mM cobalt or 10 μg/ml verapamil in 10% Ringer do not block the depolarization in the presence of 1.1 mM CaCl₂.     

Influence of aluminium on phosphorus and calcium localization in roots of beech (Fagus sylvatica)

Beech plants ( Fagus sylvatica L. provenance Maramures) were grown in nutrient solution at low pH (4.2) and exposed to different concentrations of AlCl₃. Uptake and leakage of Ca²⁺(⁴⁵Ca²⁺) and H²PO₄-(³²P) were studied. A high external aluminium concentration (1.0m M ) reduced the uptake and export to the shoot of both calcium and phosphate, while 0.1 m M Al increased the phosphorus level in the roots. To determine the impact of aluminium on the localization of calcium and phosphate, leakage of the elements from both intact plants and plants frozen prior to the leakage experiment was studied. The leakage of Ca²⁺ from intact plants was not affected by prior exposure to 0.1 m M Al. Freezing of the beech plants before the leakage experiment increased leakage of calcium slightly more from roots of control plants than for roots exposed to 0.1 m M Al, indicating that even low concentrations of alminium may impede the influx of calcium across the plasma membrane in the roots. The patterns of Ca²⁺ leakage from roots previously exposed to 1.0 m M Al indicated that very little Ca²⁺ was located extracellularly. The extracellular fraction of phosphate increased with increasing Al concentration in the nutrient solution. Low Al concentration (0.1 m M ) only reduced the intracellular phosphate concentration to a minor extent, while 1.0 m M Al profoundly decreased it. It is concluded that 0.1 m M AlCl₃ has a limited effect upon the localization of Ca²⁺ and phosphate in the roots. At higher levels of Al, 0.1–1.0 m M , there is a more dramatic change in nutrient localization in the free space and uptake over the plasma membrane.     

Cytoplasmic free Ca2+ dynamics in single tomato (Lycopersicon esculentum) protoplasts subjected to chilling temperatures

Protoplasts were isolated from leaves of tomato seedlings ( Lycopersicon esculentum Mill., cv. Marmande) at the 2nd to 4th true leaf stage and were loaded with the calcium binding tetra[acetoxymethyl⁺] ester of the fluorescent stilbene chromophore, Fura 2. Although the loading efficiency of the dye in these protoplasts was low, many protoplasts loaded only in the cytosol were always obtained. Changes in the cytosolic calcium concentration ([Ca²⁺]_cyt) were determined in single protoplasts in a temperature-controlled perfusion chamber by use of fluorescence photometry microscopy after excitation at 340 and 380 nm. When the protoplasts were subjected to chilling temperatures (10–15°C) by a circulating solution, the [Ca²⁺]_cyt increased in 64% of the analysed protoplasts. Depending on the initial resting level of [Ca²⁺]_cyt, three main types of kinetics were obtained in these protoplasts: (1) In 21% of the protoplasts, [Ca²⁺]_cyt increased to a maximum within 10–20 s from the start of temperature decrease, followed by a fast decrease; (2) in 11% of the protoplasts, the [Ca²⁺]_cyt both increased and decreased somewhat slower; and (3) in 32% a constant increase of [Ca²⁺]_cyt was obtained 1 min after the start of temperature decrease.     

45Ca2+ Uptake into Rat Whole Brain Synaptosomes Unaltered by Dihydropyridine Calcium Antagonists

Abstract: Voltage-dependent ⁴⁵Ca²⁺ uptake into rat whole brain synaptosomes was measured after 3-s KCl-induced depolarization to investigate possible inhibitory effects of calcium antagonists, nitrendipine, nimodipine, and nisoldipine. At a Ca²⁺ concentration of 1.2 m M , nitrendipine, in concentrations ranging from 0.1 n M to 10 μ M , had no effect on ⁴⁵Ca²⁺ uptake. When the Ca²⁺ concentration was lowered to 0.06 and 0.12 m M , nitrendipine, 10 μ M , inhibited ⁴⁵Ca²⁺ uptake in response to 109 m M KCl depolarization. However, in a separate concentration response study, nitrendipine, nimodipine, and nisoldipine, 0.1 n M to 10 μ M , failed to alter the uptake of ⁴⁵Ca²⁺ (0.06 m M Ca²⁺) into 30 m M KCl-depolarized synaptosomes. The high concentrations of these agents required to depress ⁴⁵Ca²⁺ uptake indicate that the dihydropyridine calcium antagonists are considerably less potent in brain tissue than in peripheral tissue.     

Bacterivory by starved marine heterotrophic nanoflagellates of two species which feed differently, estimated by uptake of dual radioactive-labelled bacteria

Abstract: The rates of ingestion of bacteria and of accumulation of bacterial biomass by hungry Pteridomonas danica and Paraphysomonas imperforata were measured using dual radioactive-labelled bacteria in experiments lasting 4–8 h. Pteridomonas continuously consumed 4–5 bacteria h⁻¹ throughout experiments lasting 8 h, irrespective of bacterial concentration above a threshold of about 5 × 10⁵ bacteria ml⁻¹, and continued to catch bacteria even below this density. The clearance rate of about 1 nl cell⁻¹ h⁻¹ at higher bacterial concentrations increased three or four times as bacterial numbers fell. Paraphysomonas cells, with only half the biomass of Pteridomonas , ingested up to 10 bacteria h⁻¹ at high bacterial concentrations, and gradually reduced the feeding rate, effectively ceasing to feed at 10⁶ bacteria ml⁻¹; their initial clearance rate of 1–2.5 nl cell⁻¹ h⁻¹ subsequently fell as low as 0.1 nl cell⁻¹ h⁻¹. Estimation of feeding rate by extrapolation from short-term experiments on such flagellates requires extreme caution. These flagellates, starved to levels typical of the natural environment, accumulated ingested bacterial biomass at an efficiency of between 16 and 21%, indicating that in nature they would recycle 80% or more of the nutrients contained in their food.     

Calcium translocations during the moulting cycle of the semiterrestrial isopod <Emphasis Type="Italic">Ligia hawaiiensis</Emphasis> (Oniscidea,Crustacea)

Terrestrial isopods moult first the posterior and then the anterior half of the body. During the moulting cycle they retain a significant fraction of cuticular calcium partly by storing it in sternal CaCO₃ deposits. We analysed the calcium content in whole Ligia hawaiiensis and the calcium distribution between the posterior, the anterior ventral, and the anterior dorsal cuticle during four stages of the moulting cycle. The results indicate that: (1) overall, about 80% of the calcium is retained and 20% is lost with the exuviae, (2) in premoult 68% of the calcium in the posterior cuticle is resorbed (23% moved to the anterior ventral cuticle, 17% to the anterior dorsal cuticle, and the remaining 28% to internal tissues), (3) after the posterior moult 83% of the calcium in the anterior cuticle is shifted to the posterior cuticle and possibly to internal storage sites, (4) following the anterior moult up to 54% of the calcium in the posterior cuticle is resorbed and used to mineralise the new anterior cuticle. ⁴⁵Ca-uptake experiments suggest that up to 80% of calcium lost with the anterior exuviae may be regained after its ingestion. Whole body calcium of Ligia hawaiiensis is only 0.7 times that of the fully terrestrial isopods. These terrestrial species can retain only 48% of whole body calcium, suggesting that the amount of calcium that can be retained by shifting it between the anterior and posterior integument is limited. We propose that fully terrestrial Oniscidea rely to a larger degree on other calcium sources like internal stores and uptake from the ingested exuviae.     

Bird community energetics in a boreal coniferous forest

The annual minimum energy consumption of the bird community was 2524 × 10³ kcal km⁻², of which 44% was consumed by wintering species and 73% by passerines. The daily energy consumption was in summer 14–16 × 10³ and in winter 1–2 × 10³ kcal km⁻². In spruce forests and in afforested swamps birds required approximately 0.12% of the net primary production. Their total annual energy consumption was covered by invertebrates (59%), vertebrates (2%) and vegetable matter (39%); the food derived from the ground (55%), from trees (44%) and from the air (1%). Arboreal insectivorous passerines, ground passerines and gallinaceous birds were the most important ecological guilds. Among passerines existence metabolism accounted for 73% of the annual energy consumption, extra activity for 17%, breeding activity for 1%, moult for 4% and nestlings for 4%.