Antioxidative responses in females and males of the spider Xerolycosa nemoralis (Lycosidae) exposed to natural and anthropogenic stressors

The aim of this study was to assess the intensity of enzymatic antioxidative parameters [i.e., superoxide dismutase (SOD), catalase (CAT), and the glutathione peroxidases each selene dependent, GPOX or selene independent, including GSTPx, glutathione S-transferase, and GST] and non-enzymatic antioxidative parameters [i.e., glutathione total (GSH-t), the heat shock proteins of Hsp70, and metallothioneins (Mt)] in the midgut glands of female and male wolf spiders Xerolycosa nemoralis (Lycosidae) exposed to natural stressors (i.e., heat shock and starvation) and anthropogenic stressors (i.e., the organophosphorous pesticide dimethoate) under laboratory conditions. The spiders were collected from two differentially polluted sites both localized in southern Poland: Olkusz, which is heavily polluted with metals, and Pilica, the reference site. In response to the stressing factors, increases in Hsp70 levels, in the concentrations of total glutathione and in the activity levels of glutathione-dependent enzymes (GPOX, GSTPx, and GST) were found in the midgut glands of males. In the females, high levels of activity of CAT and SOD were revealed, as well as an increased percentage of Mt-positive cells. Preexposed females, in comparison to the individuals from the reference site, responded with increased SOD activity, irrespective of the stressing factor. In contrast, the changes in the antioxidative parameters in the midgut glands of male X. nemoralis seem to reflect a short-term reaction to the applied stressors and do not confirm the effects of long-term selection in a polluted environment.     

Long-term dynamics and community structure of freshwater gastropods exposed to parasitism and other environmental stressors

1. Freshwater communities are subject to various abrupt environmental disturbances and increasing pollution levels in their habitat. According to the nature and the periodicity of disturbances (i.e. punctuated, recurrent or continuous), one may expect different kinds of response of the target gastropod communities. 2. The gastropod community of a French lake has been investigated for 10 years to study its responses to three main environmental disturbances: supra‐seasonal droughts, recurrent proliferations of cyanobacteria and parasitism by trematodes. The relationship between this latter factor, considered as a continuous stressor, and the gastropod community was a particular focus. 3. A total of 13 280 gastropods belonging to 17 species (mostly Pulmonata with Planorbidae as the dominant family) have been sampled in the lake over the 10‐year time series. Species composition of the gastropod community varied strongly during the study period as did species richness (0–14, mean of 6.5 ± 0.4 species) and abundance of gastropods (0–4456, mean of 192 ± 72 individuals). Trematode larvae belonging to 11 morphotypes of cercariae were detected in 15 of the 17 species of gastropods and had a total prevalence of 2.9%. 4. Droughts (punctuated stressor) were responsible for the disappearance of nearly all gastropod species, and thus represent a severe environmental stressor for them. Nevertheless, the extent of this stressor was limited since the gastropod community was highly resilient. 5. Recurrent proliferations of toxic cyanobacteria (recurrent stressor) coincided with the large decline of the gastropod community, corresponding to a strong decrease in abundance and species richness. Intoxication of gastropods by toxic cyanobacteria was demonstrated by the bioaccumulation of microcystins in all gastropod tissues. 6. Trematode parasitism (continuous stressor) did not affect the gastropod community despite the possibly strong impact of parasites on some host species (those with monthly prevalence as high as 100% at some times). Indeed, abundance and species richness of gastropods were scarcely influenced by trematode prevalence or species richness.     

On the importance of carrion to reproduction in an omnivorous estuarine neogastropod,Ilyanassa obsoleta (Say)

Summary The hypothesis that carrion provides a source of nutrition important to reproduction in the omnivorous neogastropod, Ilyanassa obsoleta (Say), was tested by collecting snails during winter, prior to reproductive season, and allowing them to feed ad libitum on three replicated diets (with starvation control) in the laboratory: vegetable, meat, and a mixture of meat and vegetable.The results indicate that, while a mixed diet is necessary for growth, meat may be the most important dietary constituent in terms of sexual condition and reproductive output of I. obsoleta. It is suggested that the chemotactic response to meat may be strongest for both sexes during the reproductive season, and may be responsible for some of the marked spatial heterogeneity in natural populations.     

Host quality and spatial patterning in infections of the Eastern mudsnail (Ilyanassa obsoleta) by two trematodes (Himasthla quissetensis and Zoogonus rubellus)

Several studies have suggested that the fitness of a parasite can be directly impacted by the quality of its host. In such cases, selective pressures could act to funnel parasites towards the highest-quality hosts in a population. The results of this study demonstrate that snail host quality is strongly correlated with spatial patterning in trematode infections and that habitat type is the underlying driver for both of these variables. Two trematodes (Himasthla quissetensis and Zoogonus rubellus) with very different life cycles assume the same spatial infection pattern in populations of the first intermediate host (Ilyanassa obsoleta) in coastal marsh habitats. Infected snails are disproportionately recovered from intertidal panne habitats, which offer more hospitable environs for snails than do adjacent habitats (intertidal creeks, coastal flats, and subtidal creeks), in terms of protection from turbulence and wave action, as well as the availability of food stuffs. Snails in intertidal panne habitats are of higher quality when assessed in terms of average size-specific mass, growth rate, and fecundity. In mark-recapture experiments, snails frequently dispersed into intertidal pannes but were never observed leaving them. In addition, field experiments demonstrate that snails confined to intertidal panne habitats are disproportionately infected by both trematode species, relative to conspecifics confined to adjacent habitats. Laboratory experiments show that infected snails suffer significant energetic losses and consume more than uninfected conspecifics, suggesting that infected snails in intertidal pannes may survive better than in adjacent habitats. We speculate that 1 possible mechanism for the observed patterns is that the life cycles of both trematode species allows them to contact the highest-quality snails in this marsh ecosystem.     

Induction of metamorphosis decreases nitric oxide synthase gene expression in larvae of the marine mollusc Ilyanassa obsoleta (say)

Many marine organisms spend the early part of their lives as larvae suspended in the water column before metamorphosing into benthic reproductive adults. Metamorphosis does not occur until a larva has become competent to respond to appropriate stimuli and after a suitable habitat for the young juvenile has been encountered. The gaseous neurotransmitter nitric oxide is thought to be important in the regulation of metamorphosis by holding the organism in the larval state. We have investigated expression of the neuronal nitric oxide synthase (nNOS) gene in larval and metamorphosing individuals of the marine mud snail Ilyanassa obsoleta. Our results indicate that nNOS is expressed at constant levels throughout larval development. In contrast, expression of nNOS decreases markedly during the first 24 h of metamorphosis. Our observations support previous findings that demonstrate that nitric oxide is present in larvae though competence. The decrease in nNOS gene expression that occurs during metamorphosis corresponds with a previously described reduction in nNOS activity.     

A note on the relevance of human population genetic variation and molecular epidemiology to assessing radiation health risk for space travellers

We discuss the relevance to space medicine of studies concerning human genetic variation and consequent variable disease susceptibility or sensitivity between individuals. The size of astronaut and cosmonaut populations is both presently and cumulatively small, and despite the launch of the International Space Station, unlikely to increase by orders of magnitude within the foreseeable future. In addition, astronauts–cosmonauts constitute unrepresentative samples of their national populations. While the context of exposure for the astronaut–cosmonaut group is one unlikely to be replicated elsewhere than in space, aspects of specific exposures may be simulated by events such as occupational radiation exposure or radiation therapy. Hence, population-based studies of genetic susceptibility or sensitivity to disease, especially where it is precipitated by events that may simulate consequences of the space environment, likely will prove of value in assessing long-term health risks.     

Transfer of rare earth elements (REE) from natural soil to plant systems: implications for the environmental availability of anthropogenic REE

Background and aims

Rare Earth Elements (REE) are widely used to trace natural geochemical processes. They are also increasingly used by man (electronics industry, medicine, agriculture) and therefore considered as emerging pollutants. The present study documents REE mobility in non-polluted natural soil-plant systems in order to characterize their environmental availability for future anthropogenic pollution.

Methods

The study is based on a field approach in non-polluted natural sites with contrasting geological environments (limestone, granite, and carbonatite) and highly variable REE contents.

Results

REE concentrations in soils do not directly reflect bedrock concentrations, but depend largely on pedogenetic processes and on the mineralogy of bedrock and soil. The soils of all sites are with respect to bedrock enriched in heavy REE. The REE uptake by plants is not primarily controlled by the plant itself, but depends on the concentration and the speciation in the soil and the adsorbed soil water pool.

Conclusions

REE uptake by plant roots are linked with those of Fe. Roots absorb preferentially the light REE. Before translocation, REE are retained by the Casparian strip leading to much lower concentrations in the aerial parts. The transport of the REE within the xylem is associated with the general nutrient flux.     

Comprehensive approaches to molecular biomarker discovery for detection and identification of Cronobacter spp. (Enterobacter sakazakii) and Salmonella spp

Cronobacter spp. (formerly Enterobacter sakazakii) and Salmonella spp. are increasingly implicated internationally as important microbiological contaminants in low-moisture food products, including powdered infant formula. Estimates indicate that 40 to 80% of infants infected with Cronobacter sakazakii and/or Salmonella in the United States may not survive the illness. A systematic approach, combining literature-based data mining, comparative genome analysis, and the direct sequencing of PCR products of specific biomarker genes, was used to construct an initial collection of genes to be targeted. These targeted genes, particularly genes encoding virulence factors and genes responsible for unique phenotypes, have the potential to function as biomarker genes for the identification and differentiation of Cronobacter spp. and Salmonella from other food-borne pathogens in low-moisture food products. In this paper, a total of 58 unique Salmonella gene clusters and 126 unique potential Cronobacter biomarkers and putative virulence factors were identified. A chitinase gene, a well-studied virulence factor in fungi, plants, and bacteria, was used to confirm this approach. We found that the chitinase gene has very low sequence variability and/or polymorphism among Cronobacter, Citrobacter, and Salmonella, while differing significantly in other food-borne pathogens, either by sequence blasting or experimental testing, including PCR amplification and direct sequencing. This computational analysis for Cronobacter and Salmonella biomarker identification and the preliminary laboratory studies are only a starting point; thus, PCR and array-based biomarker verification studies of these and other food-borne pathogens are currently being conducted.     

Relative vulnerability of six freshwater gastropods to the leech Nephelopsis obscura (Verrill)

SUMMARY. 1. The vulnerability of six species of freshwater snails to the leech Nephelopsis obscura was determined in laboratory predation experiments.
2. Nephelopsis was unable to prey on prosobranch snails with an operculum, but did consume certain pulmonate species though predation rates were low, ranging from one to two snails per leech per night at 20°C. Apparently, Nephelopsis does not actively select prey, but merely consumes those species most easily handled.
3. Among pulmonates, leeches captured species in the following order: Physa gyrina (Say), Helisoma anceps (Menke). Lymnaea emarginata (Say) and Helisoma trivolvis (Say). Susceptibihty of size classes varied among snail species.
4. Neither environmental structure, such as cobble or macrophytes, nor gastropod escape behaviors, such as clamping to substrates or vertical migration away from bottom-feeding leeches, lowered capture rates by Nephelopsis.
5. In 2 years sampling, only one of seven lakes, however, had appreciable abundances of Nephelopsis. It is therefore suggested that the rarity, low feeding rates, and lack of strong gastropod preference limit the effect of Nephelopsis on field gastropod distributions.     

Differential expression of immune-related genes and transposable elements in black tiger shrimp (Penaeus monodon) exposed to a range of environmental stressors

The health of aquatic species is dependent on interactions between the environment, pathogens and the host. Under intensive shrimp aquaculture, environmental conditions can degrade, causing significant stress to the cultured organisms. To investigate the effect of environmental stress on shrimp hemocyte gene expression profiles, we applied suppression subtractive hybridization (SSH) in juvenile Penaeus monodon exposed to hyperthermal, hypoxic or hyposmotic conditions. Random sequencing of 258 clones from the SSH revealed 176 distinct sequences of which 58 shared high similarity to sequences in the public databases. The three most common groups of identifiable unique sequences in the SSH libraries were the POL region of non-LTR retrotransposons (31%), genes with immune or potential immune functions (30%), and genes involved in protein synthesis and processing (18%). Stress-regulated differential expression was further verified by quantitative qRT-PCR, with seven out of eight randomly selected genes showing qRT-PCR profiles that conformed to the patterns predicted by SSH. Hence this work provides a list of genes which appear to be up- or down-regulated in response to stress, providing a basis for studying the genetic response of shrimp to environmental stress.     

Hemolymph cholinesterase activity in the Mussel <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> (Dunker, 1853) that was exposed to adverse natural and anthropogenic conditions

The influence of habitat conditions on the activity, the structure of the substrate specificity (the ratio of the substrate hydrolysis rates), and the kinetic parameters of substrate hydrolysis due to the effect of hemolymph cholinesterase of the mussel Crenomytilus grayanus was studied. Mussels were collected from areas that are influenced by seasonal and stationary upwelling, as well as from a polluted area. Upwelling and anthropogenic pressure were shown to alter the structure of hemolymph cholinesterase substrate specificity in mussels, up to complete loss of the ability to catalyze the hydrolysis of propionyland butyrylthiocholine. It was established that during the seasonal upwelling the efficiency of the cholinergic process in mussels is provided by a wide range of effective concentrations of the substrates and by decreasing their affinity to the enzyme. Under the conditions of chronic anthropogenic pollution, the cholinesterase of the mussel hemolymph loses its ability to hydrolyze substrates other than acetylthiocholine.     

Adaptation of the cholinergic system of <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> (Bivalvia,Mytilidae) to the impact of natural and anthropogenic conditions

The effects of environmental conditions on cholinesterase activity and kinetic parameters of substrate hydrolysis in the hemolymph of the mussel Crenomytilus grayanus were studied. Under seasonal upwellings, the cholinergic system efficiency is provided for by a wide range of efficient concentrations of the substrate, i.e., under such conditions the mussels at the molecular level have a quantitative adaptation strategy of the enzyme. In mussels from the stationary upwelling zone (at a steady low temperature of water) for efficiency of the cholinergic system, the quantitative strategy of enzyme adaptation is realized. In mussels from a highly contaminated site, irreversible damages to the cholinergic process were observed. The affinity of the substrate to the enzyme is highly informative and an appropriate biomarker for the load level and the adaptation capacity of the organism. The affinity of the substrate to the enzyme is recommended as a new biomarker.     

A non-invasive method for assessing adrenal activity in the chinchilla (Chinchilla lanigera)

The Chinchilla is a rodent that was once abundant in the central Andes of South America. Excessive hunting for fur greatly reduced its distribution at the beginning of the twentieth century, and today Chinchilla species are nearly extinct in the wild. Although protected, wild populations of chinchilla are still declining. In general, this species has received little research attention and its biology is poorly understood. Improvements in captive breeding, husbandry, and genetic management are needed to ensure the conservation of the species. In this study, a noninvasive corticosteroid hormone monitoring technique was validated for use in Chinchilla lanigera. Two male domestic chinchillas were administered 3H-corticosterone (i.m.) to determine the time course and relative proportion of urinary and fecal steroid metabolites. Most radioactivity was detected in urine and feces 5-10 and approximately 30 h post-isotope administration, respectively. Corticosteroid immunoreactivity was assessed by corticosterone radioimmunoassay (RIA) and cortisol enzyme immunoassay (EIA). High-pressure liquid chromatography (HPLC) separation of corticosteroid metabolites in unprocessed urine revealed the presence of highly polar corticosteroid metabolites, but after enzymatic hydrolysis and diethyl ether extraction, most immunoreactivity co-eluted with unconjugated cortisol. A 'cause-and-effect' relationship between the administration of exogenous adrenocorticotrophic hormone (ACTH), and the appearance of increased urinary corticosteroid metabolites demonstrated the physiological relevance of these measures for evaluating adrenal status in male chinchillas. From a conservation perspective, these methods can aid in situ and ex situ initiatives designed to evaluate how environmental conditions and management strategies affect overall animal health, well-being and reproduction.     

A computer system for the analysis of molecular evolution modes of protein-encoding genes (SAMEM): The relationship between molecular evolution and phenotypic traits

An online computer system for the analysis of the molecular evolution modes of genes and proteins has been developed (SAMEM: ). SAMEM computations are based on the ratio of radical to conservative amino acid substitutions (K _R /K _C ), the rate of amino acid substitutions in the course of protein evolution (V _P ), and statistical relationships between the evolutionary changes of all known amino acid properties and particular features of an organism. The system facilitates the interpretation of the results of K _R /K _C and V _P analyses.     

The Planktonic Index of Biotic Integrity (P-IBI): An approach for assessing lake ecosystem health

Using historical (1970) and more recent (1996) Lake Erie plankton and trophic status data, we developed a Planktonic Index of Biotic Integrity (P-IBI) to measure changes in lake ecosystem health. We used discriminant analysis to determine phytoplankton and zooplankton community characteristics (metrics) that distinguished among levels of impairment. Traditional measures of lake trophic status classes (i.e., oligotrophic, mesotrophic, eutrophic), such as chlorophyll a and total phosphorus concentrations, were used to classify sites on a gradient of impairment. We then judged the ability of plankton metrics to distinguish among trophic status classes. Because of the temporal variability found in plankton communities, we conducted analyses on a monthly basis (May–September). For June, July and August we found five unique metrics that could distinguish among trophic status classes. The P-IBI showed an increase in water quality in Lake Erie between 1970 (<3 = eutrophic) and the mid-1990s (1996 and 1997) (3–4 = mesotrophic) (which reflected mean (±standard error) total phosphorus concentrations (μg/L) 1970 > 1996; western basin (41.53 ± 2.68 > 29.75 ± 1.39), eastern basin (14.84 ± 0.82 > 7.74 ± 0.28) and mean (±standard error) chlorophyll a concentrations (μg/L) uncorrected for pheophytin 1970 > 1996; western basin (12.58 ± 1.82 > 5.40 ± 0.22), central basin (5.90 ± 0.36 > 3.17 ± 0.54), and eastern basin (5.17 ± 0.38 > 1.67 ± 0.18)), with declining water quality in the late 1990s (1998 and 1999) (3) and 2002 (<3). We recommend that the techniques used in creating the P-IBI be investigated for determining ecosystem health of other lakes.     

Cellular biosensing system for assessing immunomodulating effects on the inducible nitric oxide synthase (iNOS) cascade

A cellular biosensing system has been constructed to assess the biological safety/toxicity of chemicals. Detection of nitric oxide (NO) by the cellular biosensing system was used as a readout for assessing the immunomodulating effects of various chemicals, because some are known to induce NO synthase (iNOS) activity thereby increasing NO production. The macrophage-like cell line, RAW264.7, was cultured on the electrode coated with a polyion complex layer. The potent immune activating abilities of lipopolysaccharide could be verified by the cellular biosensing system: NO release from cells was detected within 600 ms by double potential step chronoamperometry.     

Development of an expert system for the integration of biomarker responses in mussels into an animal health index

Biomarkers on sentinel organisms are utilised worldwide in biomonitoring programs. However, the lack of effective interpretational capacity has hampered their uptake for use for assessment of risk in environmental management. The aim of the present study was to develop and test an objective decision-support or expert system capable of integrating biomarker results into a five-level health-status index. The expert system is based on a set of rules derived from available data on responses to natural and contaminant-induced stress of marine mussels. Integration of parameters includes: level of biological organization; biological significance; mutual inter-relationship; and qualitative trends in a stress gradient. The system was tested on a set of biomarker data obtained from the field and subsequently validated with data from previous studies. The results demonstrate that the expert system can effectively quantify the biological effects of different levels of pollution. The system represents a simple tool for risk assessment of the harmful impact of contaminants by providing a clear indication of the degree of stress syndrome induced by pollutants in mussels.