Elżbieta Szulińska

Effects of multigenerational cadmium exposure of insects (Spodoptera exigua larvae) on anti-oxidant response in haemolymph and developmental parameters

Biochemical and organismal indices of metal tolerance were studied in Spodoptera exigua exposed to a cadmium-contaminated diet for one or many (33 or 61) generations. Reduced and oxidised glutathione, protein thiols, total anti-oxidant capacity level, glutathione transferase activity, and Cd accumulation were assayed in the haemolymph of the last instar larvae. The cadmium concentration in the whole larval body as well as larval survival, larval duration time and last instar body weight were also measured. Elevated cadmium concentration in the whole body, higher mortality and longer duration of the larval stage in one-generation exposed insects in comparison with those exposed for many generations suggest that metal tolerance builds over time. For the larvae from multigeneration metal treatment, the higher cadmium concentration in larval haemolymph positively correlated with glutathione oxidation and total anti-oxidant capacity. One-generation exposed insects had lower metal concentration in haemolymph than did 33-generation exposed insects.

Activity of glutathione S-transferase in Spodoptera exigua larvae exposed to cadmium and zinc in two subsequent generations

The aim of our study was to establish changes in activity of important in detoxification enzyme-glutathione S-transferase (GST): in alimentary tract, fat body and Malpighian tubules of Spodoptera exigua larvae being under cadmium and zinc exposure through the first as well as the second generation. There was registered enhancement of the enzyme activity in the fat body and the Malpighian tubules caused by zinc as well as its decrease in the Malpighian tubules under cadmium action. Amounts of metals in the alimentary tract were either several times higher than in the diet ingested by larvae or than in the fat body. Metal concentration in the fat body correlated with the level of the enzyme activity (positive correlation for zinc and negative for cadmium). The effect of metal action differentiated dependently on time exposition.

The effects of cadmium or zinc multigenerational exposure on metal tolerance of Spodoptera exigua (Lepidoptera: Noctuidae)

The effects of ten generational zinc or cadmium pre-exposure on metal tolerance among beet armyworm Spodoptera exigua individuals were compared. These effects were assessed in animals from the 11th generation, reared on a diet either uncontaminated or contaminated with metal (cadmium or zinc). The survival rate of larvae and the degree of metal accumulation (in larvae, pupae and moths; among larval organs: gut and fat body) were analysed. Catalase, superoxide dismutase and glutathione transferase activity in larval organs of individuals subjected to different metal treatments were also measured. Animals transferred from control rearing to metals (cadmium or zinc) in the 11th generation, as well as those from multigenerational zinc treatment, but not from multigenerational cadmium treatment, had a significantly lower survival rate than control animals. Insects from the groups with the high metal treatment had high bioaccumulation factors (above 3.7 and 2.3 following cadmium and zinc, respectively). Cadmium (but not zinc) pre-exposure had a significant effect on metal accumulation in larvae. Multigenerational metal pre-exposure seemed to have mainly a negative effect on glutathione transferase activity in the gut of larvae from the 11th generation, in the case of the individuals exposed to metal other than that used in pre-exposure treatment or kept in control conditions. However, in the case of zinc pre-exposure, such effect was only apparent when zinc was replaced by cadmium. The long-term effect of cadmium on catalase activity in larvae was found.

Metallothioneins and energy budget indices in cadmium and copper exposed spiders Agelena labyrinthica in relation to their developmental stage, gender and origin

The aim of our studies was to explain the role of metallothioneins (MTs) in the neutralization of excessive amounts of metals (essential: copper (Cu) and toxic: cadmium (Cd)) and to describe the energy status in metal-exposed spiders Agelena labyrinthica in relation to its developmental stage, gender and origin. Juvenile, female and male spiders were collected from three variously polluted habitats, transferred to the laboratory and exposed to the metals in their diet. Cu and Cd accumulation in the body and exuviae, bioaccumulation factor, percentage of metallothionein positive cells, MT concentration, percentage of cells with depolarized mitochondria, ATP concentration and ADP/ATP ratio were measured and calculated. Cu appeared to be regulated and its excess is eliminated via, among others, the molting process, while Cd was rather accumulated by the spiders. The level of MTs increased significantly mainly in females exposed to both metals, irrespectively of the pollution degree of their site of origin, indicating a defensive role of the proteins. In general, even if both the MT level and the energy status indices were positively correlated with Cd and Cu concentrations in the spider body, the energy status of A. labyrinthica did not seem disturbed.

Apoptotic and necrotic changes in the midgut glands of the wolf spider Xerolycosa nemoralis (Lycosidae) in response to starvation and dimethoate exposure

In the present study, the intensity of degenerative changes (apoptosis, necrosis) in the cells of the midgut glands of male and female wolf spiders, Xerolycosa nemoralis (Lycosidae), exposed to natural (starvation) and anthropogenic (the organophosphorous pesticide dimethoate) stressors under laboratory conditions were compared. The spiders were collected from two differentially polluted sites, both located in southern Poland: Katowice-Welnowiec, which is heavily polluted with metals, and Pilica, the reference site. Starvation and dimethoate treatment resulted in enhancement of apoptotic and necrotic changes in the midgut glands of the spiders. The frequency of degenerative changes in starving individuals was twice as high as in the specimens intoxicated with dimethoate. The percentage of apoptotic and necrotic cells was higher in starving males than in starving females. A high intensity of necrotic changes, together with increased Cas-3 like activity and a greater percentage of cells with depolarized mitochondria, were typical of starving males from the polluted site. The cell death indices observed in females depended more strongly on the type of stressor than on previous preexposure to pollutants.

Quantitative immunodetection of metallothioneins in relation to metals concentration in spiders from variously polluted areas.

Spiders inhabiting post industrial environments, such as waste heaps or ore-bearing areas, are exposed to high concentrations of metals, accumulated in the body of their prey and transferred along food chains. Therefore spiders are pressed to develop metal-neutralization strategies. Low-molecular, multifunction proteins: metallothioneins (MTs), often postulated as biomarkers of metal exposure, are known to bind metals and thus protect organisms against their toxic effects. Yet the proteins are still not well recognized in spiders. The aim of this study was to assess, by immunodetection method, ELISA, the concentration of metallothioneins in adult females of three web building spider species: Araneus diadematus (Araneidae), Agelena labyrinthica (Agelenidae) and Linyphia triangularis (Linyphiidae) from three variously polluted areas in southern Poland: Olkusz, ore-bearing post industrial site; Katowice-WeŁnowiec: post metallurgic waste heap, Pilica: the reference, rural, area. The concentration of metallothioneins has been analyzed in relation to the metal concentration in spiders body. The study gives the evidence that metallothioneins are reliably detectable by means of ELISA technique. The analysis of results obtained shows a strong species-dependence of the MTs level. Positive correlations between MTs concentration and metal body burden (mainly Zn and Pb) were found. This suggests that the proteins play an important role in the neutralization and regulation of metal ions in spiders. The same correlation indicate the possibility to consider MTs in spiders as biomarkers of metal exposure and effects. However, the species specificity as well as metal characteristics should be taken under account.

The reproductive potential of the spiders Agelena labyrinthica and Xerolycosa nemoralis from areas contaminated with metals.

Spiders successfully colonize industrially contaminated environments and maintain relatively stable populations. The aim of this study was to explain the reproductive strategies of two spider species, Xerolycosa nemoralis (an actively hunting, sit-and-pursue predator) and Agelena labyrinthica (a web-building, sit-and-wait predator), between contaminated and uncontaminated sites. Spiders were collected from a reference site (Pilica) and two contaminated sites (Olkusz and Welnowiec). The amount of energy allocated to the eggs and the number of eggs and hatchlings as well as the hatching success were compared. Wolf spiders from the contaminated sites produced fewer but relatively energy-rich eggs, whereas web-building spiders invested their energy in the production of a higher number of less energy-rich eggs. The comparisons of the hatching percentages suggested that in the contaminated habitats, X. nemoralis achieve a hatching success similar to or higher than that of the reference population at Pilica. A. labyrinthica in the contaminated sites invested a larger amount of energy in eggs than at the reference site, but the hatching success found for this species in the contaminated areas was lower than that found at the reference site.

Selenium modifies glutathione peroxidase activity and glutathione concentration in mice exposed to ozone-provoked oxidative stress.

The aim of this study was to show the direct effect of selenium on glutathione peroxidase (GSH-Px) activity and GSH/GSSG concentrations in 3- and 6-month-old mice. An ozone-oxygen mixture was used to provoke an oxygen stress. To measure the Se-effect mice were gavaged with sodium selenite. GSH-Px activity and total glutathione concentrations were determined in serum and in the postnuclear fraction of liver and lungs. Additionally glutathione concentrations were determined in whole blood. Both ozone and selenium, administered separately, reduced GSH-Px activity in lungs of 6-month-old animals, while in young mice an opposite effect of Se was observed. Ozone administered jointly with Se did not influence GSH-Px activity in 6-month-old mice, while in young, 3-month-old mice, a stimulatory effect in lungs was observed. There were no significant changes in GSH-Px activity in the liver of 6-month-old mice, but the stimulatory effect occurred in young mice treated with Se and Se & ozone jointly. In young mice, ozone (also ozone with Se) augmented glutathione concentrations. The response to ozone and selenium strictly depended on age and the antagonism between selenium and ozone was observed only in a few cases.

The effect of ingested cadmium on the calorific value and structural properties of hunting webs produced by Steatoda grossa (Theridiidae) spiders

The study aimed to assess whether cadmium administered via ingestion to Steatoda grossa cobweb spiders (Theridiidae) affects the energy content and selected structural properties of the produced hunting webs. Cadmium content in webs was assessed with AAS and SEM X-ray microanalysis, while the diameters of silk fibers were estimated with SEM. The energy content of samples was measured in an oxygen micro-bomb calorimeter. Females and males showed different reactions to cadmium supplied through food. In comparison to females, males displayed higher metal concentrations in their bodies and hunting webs, however their calorific values and structural features were not significantly changed. Cadmium-treated females spun webs with smaller single-strand diameters and more frequent multi-stranded threads and invested 47% less energy in web production than the control individuals. It cannot be excluded that such a reduction in energy expenditure for web building in females resulted from energetically costly detoxifying reactions triggered in response to direct and indirect effects of cadmium toxicity.