Phylogenetic and environmental components of inter-specific variability in the antioxidant defense system in freshwater anomurans Aegla (Crustacea, Decapoda)

Multiple Biomarker Responses in Aegla castro Exposed to Copper: A Laboratory Approach

Although some biomarkers have already been determined in aeglids collected in the field, data from laboratory exposures are scarce. To our knowledge, no studies have investigated oxidative stress biomarkers in aeglids exposed to metals in the laboratory, or performed hemocyte counts and the comet assay using gill and hepatopancreas of aeglids. Thus, we investigated the effects of acute Cu exposure on intermolt males of Aegla castro, collected from a reference stream, acclimated for 6 days in the laboratory, and then exposed to 11 μg L-1 of dissolved Cu (Cu 11) or only to water (CTR), for 24 h. Gill and hepatopancreas samples were used to determine Cu accumulation, DNA damage, and metallothionein content (MT), while hemolymph samples were used to determine Cu accumulation, DNA damage, and hemocyte counts. Muscle samples were used to determine Cu accumulation and acetylcholinesterase activity (AChE). Non-protein thiol content (NPSH), catalase (CAT), glutathione S-transferase activities (GST), lipoperoxidation (LPO), and protein carbonylation content (PCC) were measured only in the hepatopancreas. Aegla castro exposed to Cu accumulated this metal in gills and activated detoxification mechanisms, through increased MT content in the gill, and showed an immune response, evidenced by an increase in hyaline hemocytes. Therefore, gill and hemocytes appear to have a protective role in preventing the transport and bioavailability of Cu through the body. On the other hand, we observed a decrease in MT content in the hepatopancreas of crabs exposed to Cu, suggesting the excretion of MT in association with Cu bound to the sulfhydryl groups of this protein.

Effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants

Phytoremediation is considered to be the most environmentally friendly green restoration technology for dealing with mine waste. Adding amendments can improve the substrate environment for plant growth and enhance remediation efficiency. Herbaceous plants have become the preferred species for vegetation restoration in abandoned mines because of their fast greening and simple management. After 8 weeks of pot experiments in the early stage, it was shown that the plant height and fresh weight of the plants treated with 5% conditioner and 0.5% straw (C₂S₂) were significantly higher than those of other treatments. Considering that, in this paper, to explore the effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants, the untreated copper tailings were employed as the control group, whereas copper tailings repaired by ryegrass (Lolium perenne L.), vetiver grass (Chrysopogon zizanioides L.), and tall fescue (Festuca arundinacea) with or without conditioners and straw combination into the compound amendments were taken separately as the test group. After 6 months of planting, the pH, electrical conductivity, water content, available potassium, organic matter, total nitrogen, and available phosphorus in the main physical and chemical properties of copper tailings in each experimental area were analyzed. The results showed that the electrical conductivity, organic matter, and total nitrogen content of copper tailings were improved to a certain extent by planting plants without treatment. Meanwhile, compared with the control group, all indexes of planting plants showed an upward trend after adding composite amendments. Among them, pH, water content, and available potassium content of copper tailings were enhanced more obviously. Furthermore, as discovered from the gray correlation analysis results, vetiver grass planted with composite amendments has the best comprehensive effect of improving the physicochemical properties of copper tailings, followed by tall fescue and ryegrass.

Seasonal effect on biomarker responses in sentinel species: innovation in mangrove conservation status assessment

We evaluated the environmental quality in mangrove areas of the Western Atlantic with different levels and history of contamination, considering biomarkers for the crab Ucides cordatus. For this purpose, specimens were collected in two climatic seasons (rainy and dry seasons) and assays of genotoxicity (MN, micronucleus), cytotoxicity (NRRT, neutral red retention time) and biochemical (MT, metallothionein; and LPO, lipoperoxidation) were conducted. In the most impacted mangroves, there was an increase in the mean of micronucleus (frequency of MN/1000), which was associated with a shorter retention time (minutes of NRRT). In contrast, the most pristine areas showed MN < 3 and NRRT < 100 min, with no seasonal effect, indicating a lower effect of degenerative processes by xenobiotics. The rainy season was more harmful, especially regarding cytogenotoxicity. The use of bioindicator species for environmental monitoring should be guided by an analysis of biomarkers considering the season, because during the period of highest rainfall, biomarkers values can change.

Short communication: Effects of acute copper exposure on ionic regulation of the freshwater crab Aegla castro

Aeglids are unique freshwater decapods whose habitats are being impacted by metallic compounds, such as copper (Cu). Thus, we investigated the effects of acute Cu exposure on ionic regulation of Aegla castro. For this, male specimens in intermolt were collected from a reference stream and acclimated for 5 days in laboratory. After which, crabs were exposed to 11 μg L^-1 Cu (Cu11) or only to water (CTR) for 24 h. Hemolymph samples were withdrawn for the determination of Na⁺, K⁺, Ca²⁺, and Mg²⁺ concentrations and the posterior gills removed for the analysis of Na⁺/K⁺-ATPase, Ca²⁺-ATPase, H⁺-ATPase, and carbonic anhydrase (CA) activities. Increased Ca²⁺ and Mg²⁺ hemolymph concentrations were observed in animals from Cu11, when compared with CTR group. In addition, decreased activity of CA was observed in animals exposed to Cu. In the current study, alterations in Ca²⁺ and Mg²⁺concentrations probably indicate that animals activated exoskeleton reabsorption mechanisms, characteristic of the premolt. Therefore, increased Ca²⁺ and Mg²⁺ concentrations in hemolymph may indicate that a biochemical signal associated with the molting cycle was triggered by Cu exposure. Despite the known harmful effects of Cu on osmoregulatory enzymes, here we observed decreased activity only in CA. However, decreased activity of CA could trigger both acid-base imbalance and ionic disruption, since CA provides H⁺ and HCO₃^- for intracellular pH maintenance, and underpins Na⁺ and Cl^- for ionic regulation. Therefore, understanding how aeglids respond to metal contamination in laboratory conditions is crucial to assess their potential as an alternative biological model for aquatic ecotoxicology.

Peculiar relationships among morphology, burrowing performance and sand type in two fossorial microteiid lizards

Associations among ecology, morphology and locomotor performance have been intensively investigated in several vertebrate lineages. Knowledge on how phenotypes evolve in natural environments likely benefits from identification of circumstances that might expand current ecomorphological equations. In this study, we used two species of Calyptommatus lizards from Brazilian Caatingas to evaluate if specific soil properties favor burrowing performance. As a derived prediction, we expected that functional associations would be easily detectable at the sand condition that favors low-resistance burrowing. We collected two endemic lizards and soil samples in their respective localities, obtained morphological data and recorded performance of both species in different sand types. As a result, the two species burrowed faster at the fine and homogeneous sand, the only condition where we detected functional associations between morphology and locomotion. In this sand type, lizards from both Calyptommatus species that have higher trunks and more concave heads were the ones that burrowed faster, and these phenotypic traits did not morphologically discriminate the two Calyptommatus populations studied. We discuss that integrative approaches comprising manipulation of environmental conditions clearly contribute to elucidate processes underlying phenotypic evolution in fossorial lineages.

Ion regulation in the antennal glands differs among Ocypodoidea and Grapsoidea crab species

Gills and the antennal gland are ion-regulatory organs in crabs. Previous studies have suggested that the differences in the morphology and ion regulation of gills and accessory respiratory organs between ocypodid and grapsid species are related to their distinct evolutionary transition to land habitats. In addition, Na⁺, K⁺-ATPase (NKA) activity and Na⁺ and NH₄⁺ regulation in the antennal gland differ between ocypodid and grapsid species, which had different terrestrial adaptation trajectories. This study used five Ocypodoidea species and three Grapsoidea species from the intertidal and supratidal zones to further investigate the differences in ion regulation and NKA activity in the antennal gland between these crab families in different habitats. Crabs were transferred to 5 practical salinity unit (PSU) water, and osmolality, Na⁺ and Cl^- concentrations in the urine and hemolymph, and NKA activity in the antennal gland were examined. Phylogenetic ANOVA results showed that the NKA activity in the antennal gland was higher in the ocypodid than grapsid groups, and Moran's I autocorrelation analysis also indicated that NKA activity in the antennal gland was phylogenetically correlated among crabs. K-means clustering showed a difference among the crabs in the crabs' Na⁺ and Cl^- concentrations in the urine/hemolymph, NKA activities in the antennal gland and gill 6, and number of pairs of gills. Crabs with relatively high antennal gland NKA activity were found not only in the Ocypode species, which are better adapted to terrestrial environments, but also in two intertidal species of Gelasiminae. In conclusion, part of the Ocypodidae lineage may have a) the ability to reabsorb Na⁺ and b) higher NKA activity in the antennal gland than other families, and this phenomenon is phylogenetically correlated in Ocypodoidea and Grapsoidea. The physiological diversity in osmoregulation among intertidal and costal species provides a base to further investigate their ecological niches and guilds.

Are shallow-water shrimps proxies for hydrothermal-vent shrimps to assess the impact of deep-sea mining?

Polymetallic seafloor massive sulphide deposits are potential targets for deep-sea mining, but high concentrations of metals (including copper - Cu) may be released during exploitation activities, potentially inducing harmful impact. To determine whether shallow-water shrimp are suitable ecotoxicological proxies for deep-sea hydrothermal vent shrimp the effects of waterborne Cu exposure (3 and 10 days at 0.4 and 4 μM concentrations) in Palaemon elegans, Palaemon serratus, and Palaemon varians were compared with Mirocaris fortunata. Accumulation of Cu and a set of biomarkers were analysed. Results show different responses among congeneric species indicating that it is not appropriate to use shallow-water shrimps as ecotoxicological proxies for deep-water shrimps. During the evolutionary history of these species they were likely subject to different chemical environments which may have induced different molecular/biochemical adaptations/tolerances. Results highlight the importance of analysing effects of deep-sea mining in situ and in local species to adequately assess ecotoxicological effects under natural environmental conditions.

Beneficial effects of antioxidants in improving health conditions of sheep infected with foot-and-mouth disease

The effect of multinutrient antioxidant treatment on sheep naturally infected with FMD virus was investigated in terms of general health conditions, serum proteins profile, and antioxidant/oxidant parameters. Twenty diseased sheep were divided into 4 equal groups (n = 5) and underwent certain therapeutic protocols for 8 weeks as follows: GI, infected not treated group; GII, infected and treated with the ideal and usual line of treatment against FMD virus infection; GIII, infected animals supplemented orally zinc methionine at a dose of 5 g/head/day and vitamin E with selenium-enriched yeast at the same dose level; GIV, infected animals received both the ideal treatment and antioxidants. The animals under experiment were clinically evaluated. Blood samples were obtained for the comet assay and biochemical examination at zero time and at the 8th week after treatment. Results revealed that DNA damage reduced in both GIII and GIV groups which received antioxidants. In the GI group, the activity of SOD and GPx and the level of total antioxidant capacity (TAC) markedly decreased. However, in both GIII and GIV groups treated with multinutrient antioxidants, GPx and TAC values significantly increased after treatment in comparison with the values of the same groups before treatment. After treatment with multinutrient antioxidants, α1-, β-, and γ-globulins levels markedly increased in GII and GIII groups while α2-globulin level decreased. The improvement in healing of clinical signs and general health conditions was clear in the GIV group. Finally, FMD infection in sheep was found to be associated with oxidative stress. The use of antioxidants as therapeutic approaches recovers and improves general health conditions and performance of affected animals.