From comparative physiology to toxicological risk assessment

• 1.1. Comparative physiology may help to improve the toxicologists' ability to assess and predict toxicological risks of chemicals.
• 2.2. Three main lines of approach have been distinguished, A: comparative research concerning the toxicokinetics of chemicals in different species; B: research concerning ecophysiological characteristics and C: studies aimed at the identification of biological markers that can be used to signal toxic effects in both experimental and free living populations of organisms.
• 3.3. Some remarks are made on limiting conditions to be fulfilled in order to make comparative physiology valuable from a toxicological point of view.

     

Purification and partial characterization of an AMP deaminase from the marine invertebrate Palaemon serratus

• 1.1. AMP deaminase from Palaemon serratus tail muscle was partially purified by chromatography on cellulose phosphate.
• 2.2. Muscle homogenates expressed very low enzyme activities and the presence of ATP was necessary to detect AMP deaminase. The specific activity and substrate affinity of the purified enzyme were also very low.
• 3.3. The purified prawn muscle AMP deaminase was contaminated by contractile proteins, one of the major contaminants being actin.
• 4.4. The enzyme displayed a very high affinity for actomyosin which was only partially abolished by pyrophosphate.

     

Response to stress of mussels (Mytilus edulis) exposed in dutch tidal waters

• 1.1.Mussels were exposed in the Dutch coastal zone and the Western Scheldt estuary. After six weeks of exposure, trace metals, PCBs and PAHs were measured in the soft tissue.
• 2.2. Tissue concentrations of contaminants are high in the Western Scheldt and intermediate near the Rhine outflow, except for the lower PCB congeners.
• 3.3. Results show that the survival in air is significantly lower at higher tissue concentrations, in particular of the lower PCB congeners.
• 4.4. The clearance rate is reduced at the highest tissue concentrations.

     

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Oxidants and antioxidants in aquatic animals

• 1.1. Oxidative stress, potentially, is experienced by all aerobic life when antioxidant defenses are overcome by prooxidant forces, and is the basis of many physiological abberations.
• 2.2. Environmental contaminants may enhance oxidative stress in aquatic organisms, e.g. highly elevated rates of ideopathic lesions and neoplasia among fish inhabiting polluted environments is increasingly related to oxidative stress associated with environmental pollution.
• 3.3. Metabolism of redox cycling xenobiotics in aquatic organisms is very similar to that of mammals suggesting similarities in the health consequences of exposure to such compounds.
• 4.4. The expression of specific lesions known to arise specifically from oxidative stress, e.g. lipid peroxidation, oxidized bases in DNA and accumulation of lipofuscin pigments are present in many aquatic animals exposed to contaminants.
• 5.5. Aquatic organisms contain the major antioxidant enzymes SOD, catalase and glutathione peroxidase, albeit there are marked quantitative differences among the various species reported.

     

Evaluating the effects of chemical exposures on adaptive functioning

• 1.1. Although morphological and classical toxicological data have typically served as criteria for judging the effects of chemicals on the nervous system, there has been increasing interest in the use of behavioral end-points for examining the adverse effects of chemicals on nervous system function.
• 2.2. The present paper describes the current use of behavioral methods in neurotoxicity assessment and surveys some of the recent developments in the use of specialized methods for examining motor, sensory and cognitive changes following chemical exposures.

     

The usefulness of histopathology in aquatic toxicity studies

• 1.1. A survey was carried out to examine the usefulness of histopathology for the identification of toxic effects of environmental contaminants in fish.
• 2.2. Two small fish species, Poecilia reticulata (guppy) and Oryzias latipes (medaka) were used, and two exposure periods (1 and 3 months) were chosen.
• 3.3. The following compounds were studied: β-hexachlorocyclohexane, bis(tri-n-tributyltin)oxide, di-n-butyltindichloride, sodium bromide, methyl bromide, and methylmercury chloride.
• 4.4. The following is concluded: histopathology provides useful data in characterizing toxic effects in fish; there is a slight advantage for Poecilia reticulata over Oryzias latipes; there is no advantage for 3 months exposure vs 1 month.

     

Catecholamines affect storage and retrieval of conditioned odour stimuli in honey bees

• 1.1. The effects of injected catecholamines and their analogues on odour learning in honey bees is described.
• 2.2. Dopamine blocks the retrieval of a learned odour signal with a specific time course and does not block the storage of this signal.
• 3.3. Noradrenaline blocks retrieval and storage of a conditioned odour signal.
• 4.4. Amphetamine shows the same effects as noradrenaline.
• 5.5. Haloperidol has no affect on memory retrieval or storage.

     

Porphyrin biosynthesis in Rhodopseudomonas palustris—IX. PBG-deaminase. Kinetic studies

• 1.1. PBG-Deaminase obtained from Rp. palustris exhibited classical Michaelis-Menten kinetics in the absence or presence of different ions.
• 2.2. Detailed kinetic studies were carried out in the presence of ammonium, phosphate and magnesium ions.
• 3.3. It has been found that the different effects observed are dependent on both the substrate and the ion concentration.

     

Detection of 180 kDa proteins in electroplax sodium channel preparations

• 1.1. Co-isolating proteins (M_r 170,000–220,000) from sodium channel preparations made from the electric organ of the electric eel (Electrophorus electricus) were detected on Western blots using monoclonal a antibodies.
• 2.2. Similar protein patterns were seen on immunoblots containing immunoprecipitated protein from eel muscle and brain tissues but not heart.
• 3.3. These co-isolating proteins could be separated from the mature TTX-sensitive channel protein (M_r 280,000) using a lentil lectin-Sepharose column.
• 4.4. The 180 kDa proteins do not appear to be channel-related and can be detected as contaminants in electroplax sodium channel preparations using the monoclonal antibodies described here.

     

Interference of benzo[a]pyrene with cytochrome P-450-mediated steroid metabolism in pyloric caeca microsomes of the sea star Asterias rubens L.

• 1.1. The effects of benzo[a]pyrene (BaP) on the metabolism of progesterone and pregnenolone, and the effects of steroids on BaP metabolism were examined in pyloric caeca microsomes of female Asterias rubens.
• 2.2. The patterns of metabolism of progesterone and pregnenolone in microsomes were similar to those found in previous studies for homogenates and tissue incubations of pyloric caeca.
• 3.3. BaP reduced the rate of hydroxylation of progesterone and pregnenolone, but had no effect on metabolite formation by non-cytochrome P-450-catalysed reactions.
• 4.4. Microsomal BaP hydroxylase activity was reduced by the presence of progesterone, but pregnenolone and testosterone had no such effect.
• 5.5. The reductions in steroid or BaP metabolism were progressive with increasing ratios of the concentration of the interfering compound to that of the assay substrate and were maximally 50% or less at ratios of × 100.
• 6.6. It is concluded that isoenzymic forms of cytochrome P-450 are present, with preferences towards either steroid or BaP metabolism. The implications of the results for the in vivo situation are discussed.

     

Breast,hips, and buttocks revisited: Honest fatness for honest fitness

This paper comments on: Low, B. S., Alexander, R. D., and Noonan, K.M. Human hips, breast, and buttocks: Is fat deceptive? Ethology and Sociobiology 8: 249-247, 1987. In it I argue that:

• 1.1. Sexual selection has probably not been the most important selection pressure on
• 2.female human body shape.
• 3.2. Male humans in different cultures find different aspects of the female body attractive
• 4.and therefore are unlikely to have exerted consistent directional sexual selection on
• 5.the female body.
• 6.3. Breast size is not correlated with lactation success.
• 7.4. Visible hip width is not correlated with parturition success.
• 8.5. Women would lower their fitness if they tried to deceive men about their internal
• 9.pelvic dimensions.
• 10.6. There are many alternative hypothesis to explain the existence of fat onwomen's
• 11.breast, hips, and buttocks.

     

Endothelins and sarafotoxins: Receptor heterogeneity

• 1.1. Endothelins (ETs) and sarafotoxins (SRTXs) belong to a family of 21-amino-acid peptides comprising at least eight isoforms.
• 2.2. ET exerts multiple pharmacological effects through its receptors.
• 3.3. This review summarizes the observations and findings pointing to the existence of receptor subtypes and leading to their identification.
• 4.4. Two receptor subtypes have been cloned and stably expressed.
• 5.5. The existence of at least two more is predicted by dissimilar ligand potencies in different tissues, kinetics of receptor-ligand interactions, and cross-linking of receptors and radiolabeled ligands.

     

Metabolism of secondary alcohols in Drosophila melanogaster: Effects on alcohol dehydrogenase

• 1.1. In vivo metabolism of a secondary alcohol in Drosophila melanogaster and its effects on alcohol dehydrogenase (ADH) have been studied.
• 2.2. ADH-mediated breakdown of the secondary alcohol, propan-2-ol, was the main source of the acetone produced.
• 3.3. Acetone formation declined and stopped ultimately, suggesting inhibition of ADH activity in vivo which has been confirmed in in vitro studies.
• 4.4. A powerful ketone-trapping agent, semicarbazide, did not restore the ADH activity in vitro, whereas aldehyde substrates of ADH did restore activity.
• 5.5. The final formation of a dead-end ADH:NAD-acetone ternary complex has been proposed and its consequences discussed.

     

Substantial Influence of ERAP2 on the HLA-B*40:02 Peptidome: Implications for HLA-B*27-Negative Ankylosing Spondylitis

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Highlights

• •HLA-B*40:02 and ERAP2 are risk factors for ankylosing spondylitis.
• •The effects of ERAP2 on the B*40:02 peptidome are defined.
• •ERAP2 has a major influence mainly due to alterations of N-terminal residues.
• •These effects provide a basis for the association of ERAP2 with disease.

     

Heart rate and its cholinergic control in the sole (Solea vulgaris), acclimatized to different temperatures

• 1.1. The effects of thermal acclimatization at 10 and 24°C on heart rate were investigated on unrestrained soles (Solea vulgaris).
• 2.2. The sensitivity of heart rate to temperature changes induced by temperature acclimatization was higher in cold-acclimatized than in warm-acclimatized soles.
• 3.3. Heart rate of cold-acclimatized fish to temperature changes was not affected by blocking the vagal tone with atropine.
• 4.4. After atropine treatment the ability of heart rate to show thermal compensation decreased in warm-acclimatized soles.
• 5.5. It is suggested that the vagus nerve can function differently at different temperatures.

     

Extrapolation through hierarchical levels

• 1.1. Translating results from low hierarchical levels to higher orders meets with difficulties with respect to temporal, spatial and organizational scales.
• 2.2. Translating stress effects through hierarchical levels has not yet been possible, thus hampering ecological risk assessment.
• 3.3. Three approaches to link the various levels are described; the energetics, the endpoint and the minimal structure approach.
• 4.4. A concept to integrate these approaches to enable extrapolation of stress effects across hierarchical levels is described.