Lead-induced hsp70 and hsp60 pattern transformation and leg malformation during postembryonic development in the oribatid mite, Archegozetes longisetosus Aoki

Appendage abnormalities in spiders induced by an alternating temperature protocol in the context of recent advances in molecular spider embryology

In the literature there are numerous reports of developmental deformities in arthropods collected in their natural habitat. Since such teratogenically affected individuals are found purely by chance, the causes of their defects are unknown. Numerous potential physical, mechanical, chemical, and biological teratogens have been considered and tested in the laboratory. Thermal shocks, frequently used in teratological research on the spider Eratigena atrica, have led to deformities on both the prosoma and the opisthosoma. In the 2020/2021 breeding season, by applying alternating temperatures (14 °C and 32 °C, changed every 12 h) for the first 10 days of embryonic development, we obtained 212 postembryos (out of 3,007) with the following anomalies: oligomely, heterosymely, bicephaly, schistomely, symely, polymely, complex anomalies, and others. From these we selected six spiders with defects on the prosoma and two with short appendages on the pedicel for further consideration. The latter cases seem particularly interesting because appendages do not normally develop on this body part, viewed as the first segment of the opisthosoma, and appear to represent examples of atavism. In view of the ongoing development of molecular techniques and recent research on developmental mechanisms in spiders, we believe the observed phenotypes may result, at least in part, from the erroneous suppression or expression of segmentation or appendage patterning genes. We consider "knockdown" experiments described in the literature as a means for generating hypotheses about the sources of temperature-induced body abnormalities in E. atrica.

Teratological changes in postembryos of Eratigena atrica obtained by the application of alternating temperatures on spider embryos

Spider embryonic development depends on several factors, including temperature. Under optimum thermal conditions embryogenesis proceeds undisturbed and embryo mortality is low. On the other hand, dramatic shifts in incubation temperature may cause a range of developmental defects in embryos. It has been confirmed in numerous laboratory experiments that abrupt temperature changes can be a powerful teratogenic factor. Changes in the external structure are frequently reflected in the internal anatomy, and above all, in the central nervous system. In the present teratological study, by exposing spider embryos to the temperatures of 14 °C and 32 °C, changed every 12 hours for the first 10 days of their development, we obtained 74 postembryos of Eratigena atrica with body deformities such as oligomely, heterosymely, schistomely, bicephaly, complex anomalies and others. We selected six spiders to describe and analyze their morphological changes. In one case, that of a spider affected by polymely (the presence of a supernumerary appendage) combined with heterosymely (the fusion of walking legs), we also focused on the structure of the central nervous system. The analysis indicated that this complex anomaly was accompanied by only one change in the central nervous system: the presence of a supernumerary neuropil. Since no fusion of walking leg neuropils was observed, it was concluded that, in this instance, there was no relationship between the fusion of legs and the structure of the central nervous system.

Oppia nitens C.L. Koch, 1836 (Acari: Oribatida): Current Status of Its Bionomics and Relevance as a Model Invertebrate in Soil Ecotoxicology

The oribatid soil mite Oppia nitens C.L. Koch, 1836, is a model microarthropod in soil ecotoxicity testing. This species has a significant role in supporting soil functions and as a suitable indicator of soil contamination. Despite its significance to the environment and to ecotoxicology, however, very little is known of its biology, ecology, and suborganismal responses to contaminants in the soil. In the present review, we present detailed and critical insights into the biology and ecology of O. nitens in relation to traits that are crucial to its adaptive responses to contaminants in soil. We used a species sensitivity distribution model to rank the species sensitivity to heavy metals (cadmium and zinc) and neonicotinoids (imidacloprid and thiacloprid) compared with other standardized soil invertebrates. Although the International Organization for Standardization and Environment and Climate Change Canada are currently standardizing a protocol for the use of O. nitens in soil toxicity testing, we believe that O. nitens is limited as a model soil invertebrate until the molecular pathways associated with its response to contaminants are better understood. These pathways can only be elucidated with information from the mites' genome or transcriptome, which is currently lacking. Despite this limitation, we propose a possible molecular pathway to metal tolerance and a putative adverse outcome pathway to heavy metal toxicity in O. nitens. Environ Toxicol Chem 2019;38:2593-2613. © 2019 SETAC.

Multigenerational exposure of populations of Oppia nitens to zinc under pulse and continuous exposure scenarios

Current soil remediation guidelines for metals reflect single-generation laboratory studies, but in the field, organisms are exposed to metals for more than one generation. The present study assessed the multigenerational effect of zinc (Zn) on Oppia nitens under a pulse or continuous exposure scenario. Synchronized adult mites (parents) were exposed to 6 concentrations of Zn in a field soil. For the pulse exposure, juveniles of parent mites from 3 of the 6 concentrations (105, 158, 237, 335, 553, and 800 mg/kg) were kept in clean media and reared until the third generation. At every generation, the sensitivity of the mites to Zn was tested in a dose-response manner. For the continuous exposure, the mites produced from the parents were re-exposed to the same concentration as their parents. According to critical-level estimates like the median effect concentration, all populations of the F2 and F3 generation mites in the pulse exposure were less sensitive to Zn than the parents and were protected at 250 mg/kg of Zn (Canadian Council of Ministers of the Environment [2018] soil quality guideline). However, the mite generations of the continuous exposure remained as sensitive as the parent generation and were not protected by the Zn guideline level. The Zn niche width narrowed considerably for all continuously exposed mite populations, indicating that they were more sensitive than the parent. Our results show that Zn has a deleterious multigenerational effect on continuously exposed populations of mites. Environ Toxicol Chem 2019;38:896-904. © 2019 SETAC.

Effects of green algae and napa cabbage on life-history parameters and gut microflora of Archegozetes longisetosus (Acari: Oribatida) under laboratory conditions

We compared the effect of green algae (dominated by Protococcus sp.) and the earlier studied napa cabbage on the life-history parameters and gut microflora of the oribatid mite Archegozetes longisetosus (a chelicerate model organism). Napa cabbage contained more crude ash, protein, and crude fibre than green algae, but A. longisetosus developed better on the latter food, displaying higher fertility, lower mortality of offspring and shorter development than on napa cabbage. The gut microflora of A. longisetosus depended on the kind of food and developmental stage of this mite. The adults fed with napa cabbage had more abundant and more active microflora than those fed with green algae, whereas in the tritonymphs the microflora was more abundant when they were fed with green algae, and was more active in the group fed with napa cabbage. Irrespective of the treatment, the highest percentage of the isolated bacteria were gram-positive bacilli or gram-negative bacteria, but the mites feeding on Protococcus sp. contained no cocci, whereas those fed with cabbage had no gram-positive bacteria.

Alleviative effect of selenium on inflammatory damage caused by lead via inhibiting inflammatory factors and heat shock proteins in chicken testes

The aim of this study was to investigate ameliorative effect of selenium (Se) on lead (Pb)-induced inflammatory damage in chicken testes. One hundred eighty 7-day-old male chickens were randomly assigned into the control group, the Se group, the Pb group, and the Pb/Se group. Lead acetate was added in drinking water (350 mg/L Pb). Sodium selenite was added in the standard commercial diet (1 mg/kg Se). On the 30th, 60th, and 90th days of the experiment, 15 chickens of each group were euthanized. Inductively coupled plasma mass spectrometry, hematoxylin and eosin staining, real-time quantitative PCR, and Western blot were used. The results indicated that excess Pb increased nitric oxide content; inducible nitric oxide synthase (iNOS) activity; nuclear factor-kappa B (NF-κB), tumor necrosis factor-α, cyclooxygenase-2, prostaglandin E synthases, and iNOS mRNA levels in a time-dependent manner; NF-κB, iNOS, heat shock protein (HSP) 60, HSP70, and HSP90 protein levels; and Pb concentration. Excess Pb decreased Se concentration and induced histological changes. Se-alleviated Pb caused all of the above changes. Se improved Pb-caused inflammatory damage by decreasing the expression of inflammatory factors and heat shock proteins in the chicken testes. Our results provided theoretical basis of an alleviative effect of Se on Pb-induced bird testis damage.

The Antagonistic Effect of Selenium on Lead-Induced Inflammatory Factors and Heat Shock Protein mRNA Level in Chicken Cartilage Tissue

Selenium (Se) is recognized as a necessary trace mineral in animal diets, including those of birds. Lead (Pb) is a toxic heavy metal and can damage organs in humans and animals. Complex antagonistic interactions between Se and heavy metals have been reported in previous studies. However, little is known regarding the effects of Se on Pb-induced toxicity and the expression of inflammatory factors and heat shock proteins (HSPs) in the cartilage of chickens. In this present study, we fed chickens either with Se or Pb or both Se and Pb supplement and later analyzed the mRNA expressions of inflammatory factors (inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2)) and HSPs (Hsp27, Hsp40, Hsp60, Hsp70, and Hsp90). The results showed that Se and Pb influenced the expression of inflammatory factors and HSP genes in the chicken cartilage tissues. Additionally, we also found that antagonistic interaction existed between Se and Pb supplementation. Our findings suggested that Se could exert a antagonistic effect on Pb in chicken cartilage tissues.

Phenotypic diversity, population structure and stress protein-based capacitoring in populations of Xeropicta derbentina, a heat-tolerant land snail species

The shell colour of many pulmonate land snail species is highly diverse. Besides a genetic basis, environmentally triggered epigenetic mechanisms including stress proteins as evolutionary capacitors are thought to influence such phenotypic diversity. In this study, we investigated the relationship of stress protein (Hsp70) levels with temperature stress tolerance, population structure and phenotypic diversity within and among different populations of a xerophilic Mediterranean snail species (Xeropicta derbentina). Hsp70 levels varied considerably among populations, and were significantly associated with shell colour diversity: individuals in populations exhibiting low diversity expressed higher Hsp70 levels both constitutively and under heat stress than those of phenotypically diverse populations. In contrast, population structure (cytochrome c oxidase subunit I gene) did not correlate with phenotypic diversity. However, genetic parameters (both within and among population differences) were able to explain variation in Hsp70 induction at elevated but non-pathologic temperatures. Our observation that (1) population structure had a high explanatory potential for Hsp70 induction and that (2) Hsp70 levels, in turn, correlated with phenotypic diversity while (3) population structure and phenotypic diversity failed to correlate provides empirical evidence for Hsp70 to act as a mediator between genotypic variation and phenotype and thus for chaperone-driven evolutionary capacitance in natural populations.

The effect of manganese-induced cytotoxicity on mRNA expressions of HSP27, HSP40, HSP60, HSP70 and HSP90 in chicken spleen lymphocytes in vitro

The purpose of this study was to investigate the effect of manganese (Mn)-induced cytotoxicity on heat shock proteins in chicken spleen lymphocytes. Lymphocytes were cultured in medium in the absence and presence of MnCl2 (2 × 10(-4), 4 × 10(-4), 6 × 10(-4), 8 × 10(-4), 10 × 10(-4), and 12 × 10(-4) mmol/L) for 12, 24, 36, and 48 h in vitro. Then, the mRNA levels of HSP27, HSP40, HSP60, HSP70, and HSP90 were examined by real-time quantitative PCR. The results showed that the mRNA levels of HSP27, HSP40, HSP60, HSP70, and HSP90 in all treatment groups at all time points, except mRNA levels of HSP27 at 48 h, had the same tendency. As manganese concentration increased, the mRNA expression of the heat shock proteins first increased and then decreased. In other words, we demonstrated that the mRNA expression of the heat shock proteins was induced at lower concentrations of manganese and was inhibited at higher concentrations. Mn had a dosage-dependent effect on HSP27, HSP40, HSP60, HSP70, and HSP90 mRNA expression in chicken spleen lymphocytes in vitro.

Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster

BACKGROUND

Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (<30nm) in the midgut of Drosophila melanogaster (Oregon R(+)) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.

METHODS

Third instar larvae of D. melanogaster were exposed orally to 1-100μg/mL of aSNPs for 12-36h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.

RESULTS

A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.

CONCLUSION

aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.

GENERAL SIGNIFICANCE

Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.

Concentration-dependent, size-independent toxicity of citrate capped AuNPs in Drosophila melanogaster

The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs) of different sizes (5, 15, 40, and 80 nm) in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES), while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN). We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size.

Leg deformities of oribatid mites as an indicator of environmental pollution

Oribatid mites have often been used as indicators of the degree of environmental pollution but few studies have assessed the effects of pollution at individual level. One possible indicator of environmental stress at individual level is structural malformations of exoskeleton. We studied whether a number of leg deformities in soil oribatid mites could be used as an indicator of the degree of heavy metal pollution or acidity in nature. For this purpose we collected soil samples in a well known pollution gradient of a Finnish Cu-Ni smelter. Heavy metals are common pollutants in the area. Ten focal oribatid species were inspected under microscope for deformations in their legs (missing, broken or deformed leg). Of the focal species only one (Chamobates cuspidatus) showed an increasing trend along the pollution gradient in the proportion of leg abnormalities but there were clear differences in proportions among species. We consider that leg deformities are not a good indicator of heavy metal exposure in the studied species. Our data suggest, however, that they may indicate spatial variation in soil pH. We also tested for the possible effects of pollution on oribatid species number and abundances. There were pollution-related differences in relative abundances of mites but not in the number of species. We discuss the relationship between soil pH, calcium requirements and skeletal malformations of oribatid mites.