Synthesis and assembly of native myosin on muscle polyribosomes

We have used the overload-induced growth of avian muscles to study the assembly of the newly synthesized myosins which were separated by non-denaturing pyrophosphate-polyacrylamide gel electrophoresis. Using this model, we have observed the appearance of fast-like isomyosins in polyribosomes prepared from slow anterior latissimus dorsi muscle after 72 h of overload. These new isoforms comigrating with native myosin from fast posterior latissimus dorsi muscle were not yet present in cellular extracts from the same muscle. The in vitro translation system utilizing muscle specific polyribosomes directs the synthesis of the corresponding myosin isoforms. Under denaturing conditions, myosin heavy chains and light chains dissociate to the expected subunit composition of each specific isoform. The synthesis and assembly of native myosin on polyribosomes indicate that myosin exists as a single mature protein prior to the incorporation in the thick filament.     

Effects of sublethal exposure to copper on diel activity of sea catfish,Arius felis

The effect of sublethal exposure to copper on the diel activity of sea catfish, Arius felis, was examined after 72 h static exposure to copper (0.0, 0.05, 0.1, or 0.2 mg l^–1 ). The locomotor behavior of 28 individual fish was electronically monitored in a 16-compartment rosette tank. Activity was quantified by the number of entries into compartments per hour. Controls and copper-exposed fish (0.05 mg l^–1) behaved similarly after treatment and displayed no significant effects of handling or copper exposure on diel activity. However, fish exposed to 0.1 and 0.2 mg l^–1 copper were hyperactive immediately following exposure; these fish had significantly greater numbers of entries into compartments per hour for entire 24-h monitoring periods (P < 0.01) and for the 12 h of photophase (P < 0.001) and of scotophase (P < 0.001) than fish in the other two experimental groups. The normal diel activity cycle was abolished. Additionally, exposure of fish to copper at 0.1 and 0.2 mg l^–1 resulted in significantly less variability in activity (P < 0.05) compared to control fish and those exposed to 0.05 mg Cu l^–1.     

Effects of acidity on acute toxicity of aluminium-waste and aluminium-contaminated soil

The total heavy metal concentrations of Al-waste and Al-contaminated soil were many times higher than that found in the control soil, which might pose toxic effects on nearby ecosystems under acidic condition. The present study aimed to detect the amount of Al, Cu, Zn, Mn, Pb, Ni and Cd extracted by distilled water and ammonium acetate at pH 3.8, 4.8, 5.8, 6.8 and 7.8. The acute toxicities of water extracts were assessed by two bioassays. Results showed that concentrations of heavy metals, especially Al, were the highest in extracts from Al-contaminated soil extracted with NH₄OAc, followed by Al-waste. The control displayed relatively low levels of metals. More heavy metals were extracted at acidic pH than at neutral pH. Distilled water extracts exhibited lower levels of metals than those extracted with NH₄OAc. The first bioassay, in terms of seed germination and root elongation of B. parachinensis, indicated that the germination rates were seriously retarded by Al-waste even at neutral pH. Less than 25% seeds were germinated in Al-waste and the toxic effect was more obvious at pH 3.8. Root growth in Al-waste and Al-soil was slower than in the control and no seedling in Al-waste had roots longer than 2 cm at the end of this study. In the second bioassay, the photosynthetic rate of Chlorella pyrenoidosa was significantly inhibited by Al-waste when compared with the control, although the pH effect was not clear. This study revealed that the metal availability was pH dependent and their toxicity could be rapidly assessed by two simple bioassays.     

Comparative strategies of heavy metal accumulation by crustaceans: zinc,copper and cadmium in a decapod,an amphipod and a barnacle

This study investigates the comparative strategies of accumulation under standardised laboratory conditions of the essential metals zinc and copper, and the non-essential metal cadmium by three crustaceans of different taxa; vizPalaemon elegans Rathke (Malacostraca: Eucarida: Decapoda),Echinogammarus pirloti (Sexton & Spooner) (Malacostraca: Peracarida: Amphipoda) and the barnacleElminius modestus Darwin (Cirripedia: Thoracica).The decapodP. elegans regulates body zinc concentrations to a constant level (ca. 79 µg Zn g^–1) over a wide range of dissolved metal availabilities until regulation breaks down at high Zn availabilities and net accumulation begins. The amphipodE. pirloti accumulates zinc at all dissolved zinc concentrations but at a low net rate such that the accumulation strategy approaches that of regulation. The barnacleE. modestus accumulates zinc to high body concentrations with no significant excretion of accumulated zinc. In the case of copper,P. elegans similarly regulates body copper concentrations to a constant level (ca. 129 µg Cu g^–1) over a range of dissolved copper availabilities until regulation breaks down at high copper concentrations. Both the amphipodE. pirloti and the barnacleE. modestus on the other hand accumulate copper at all dissolved copper exposures with no evidence of regulation. All three crustaceans accumulate the non-essential metal cadmium at all dissolved cadmium concentrations without regulation.Heavy metal accumulation strategies therefore vary between crustacean taxa and between metals. Uptake rates for zinc and cadmium have been estimated for the three crustaceans and can be interpreted in terms of cuticle permeability and way of life of each crustacean. Examination of these uptake rates provides an insight into possible reasons behind the adoption of particular metal accumulation strategies.     

Nitrification rates in the lower river Rhine as a monitor for ecological recovery

The rate of in situ nitrification was tested as an indicator of the toxicological quality of the river Rhine. Concentration changes of ammonium ions over 85 to 133 km long reaches of three river branches downstream of the densely populated Ruhr-area (F.R.G.) were calculated from a data base for the period 1972 to 1986. Concentrations of ammonium in the river exceeded values of 1 mg N/l in winter. Because of the very high input of ammonium, bacterial nitrification dominated over other nitrogen processes. Relative rates of nitrification in the three river branches were proportional to the water temperature for the individual years. Nitrification rates in the river increased by a factor of ca. 4 during the period of 1972 to 1986. Toxic substances, whose concentrations decreased in the same period of time, were proposed as inhibitors of in situ nitrification rather than e.g. a low oxygen saturation of the water. The improvement of the conditions in the river, indicated by the in situ rate of nitrification, was also documented by data on macrofauna and fish populations.     

The effect of heavy metal speciation in sediment on bioavailability to tubificid worms

The bioavailability of heavy metals in sediment to freshwater tubificid worms was compared with measures of chemical extractability using a sequential extraction procedure. In order to provide a range of test sediments of different quality, various mineral phases were prepared, in which the metals were spiked by adsorption or coprecipitation and these were then mixed with a bulk base sediment in known proportions. Results indicated good correlation between worm metal burden and metal mobilised from the sediments in the first (exchangeable) sequential extraction step for Cd, Cu and Pb. Of the other metals tested, Zn levels in the worms were found to be constant, suggesting regulation, and Ni uptake was too small for accurate measurement. In general, metals spiked to the sediment directly, or adsorbed on the clay mineral phase were found to be much more available than those bound to sewage sludge, carbonate or hydrous ferric oxide phases.     

Iron reduction by bacteria: range of organisms involved and metals reduced

Abstract The majority of the bacteria tested were able to reduce both ferric iron and nitrate. However, ferric iron may be reduced by bacteria which do not possess a nitrate reductase and, conversely, the possession of a nitrate reductase does not confer the ability to reduce ferric iron. A glucose-fermenting Vibrio and an anaerobic lithotroph were tested for their ability to reduce a greater variety of metals. The Vibrio reduced the wider range of metals and to a greater degree. Lithotrophic bacteria not only reduce a more restricted range of metals, they also appear not to possess the capacity of fermentative bacteria to use metals as minor electron sinks.     

Post‐ingestive effects of nectar alkaloids depend on dominance status of bumblebees

Abstract 1. Secondary metabolites have acute or chronic post‐ingestive effects on animals, ranging from death to growth inhibition to reduced nutrient assimilation. 2. Although characterised as toxic, the nectar of Gelsemium sempervirens is not lethal to pollinators, even when the concentration of the nectar alkaloid gelsemine is very high. However, little is known about the sublethal costs of nectar alkaloids. 3. Using a microcolony assay and paired worker bumblebees, the present study measured the effects of artificial nectar containing gelsemine on oocyte development. Oocytes are a sensitive indicator of protein utilisation and general metabolic processes. We also calculated carbohydrate concentrations in the haemolymph to examine energetic costs of gelsemine consumption. 4. High concentrations of gelsemine significantly reduced mean oocyte width in subordinate bees, while dominant bees showed only a trend towards oocyte inhibition. Gelsemine consumption did not reduce carbohydrate concentrations in haemolymph. 5. The cost of ingesting gelsemine may be due to direct toxicity of alkaloids or may be an expense associated with detoxifying gelsemine. Detoxification of alkaloids can require reallocation of resources away from essential metabolic functions like reproduction. The risks associated with nectar alkaloid consumption are tied to both the social and nutritional status of the bee.     

Assessment of organochlorine pesticides and metals in ring‐tailed lemurs (Lemur catta) at Beza Mahafaly Special Reserve,Madagascar

Like most of Madagascar's endemic primates, ring‐tailed lemurs (Lemur catta) face a number of threats to their survival. Although habitat loss is of greatest concern, other anthropogenic factors including environmental contamination may also affect lemur health and survival. In this study, we examined ring‐tailed lemurs from the Beza Mahafaly Special Reserve (BMSR), southern Madagascar for exposure to organochlorine (OC) pesticides and metals and examined differences in contaminant concentrations between sexes and among age groups, troops, and habitats. A total of 14 pesticides and 13 metals was detected in lemur blood (24 individuals) and hair (65 individuals) samples, respectively. p,p′‐DDT, heptachlor, aldrin, heptachlor epoxide, endrin aldehyde, and endrin were among the most prevalent pesticides detected. Surprisingly, the persistent metabolite of p,p′‐DDT, p,p′‐DDE, was not detected. The most commonly detected metals were aluminum, zinc, boron, phosphorus, silicon, and copper, whereas metals considered more hazardous to wildlife (e.g. arsenic, cadmium, lead, selenium, vanadium) were not found above detection limits. Overall, concentrations of OC pesticides and metals were low and similar to those considered to be background concentrations in other studies examining the ecotoxicology of wild mammals. Few inter‐sex, ‐age, ‐troop, and ‐habitat differences in contaminant concentrations were observed, suggesting a uniform distribution of contaminants within the reserve. Several statistically significant relationships between lemur body size and contaminant concentrations were observed, but owing to the lack of supportive data regarding contaminant exposure in wild primates, the biological significance of these findings remains uncertain. Results of this study document exposure of ring‐tailed lemurs at BMSR to multiple OC pesticides and metals and provide essential baseline data for future health and toxicological evaluations of lemurs and other wild primates, especially those in regions with expanding agricultural and mining operations. Am. J. Primatol. 71:998–1010, 2009. © 2009 Wiley‐Liss, Inc.