Clues from planarians about interleukin-17A and stress that result from light avoidance: IL-17A antagonists reduce defensive responding in flatworms

Emerging evidence links interleukin-17A (IL-17A) to anxiety and stress. Circulating levels of IL-17A are elevated in patients with anxiety disorders, and pharmacological blockade of IL-17 signaling or genetic deletion of IL-17 reduces anxiety-like behaviors in mice. Given that IL-17 is one of the most conserved cytokines among animal phyla, we tested the hypothesis that anti-IL-17 treatments reduce defensive responding in planarians, the simplest animal with bilateral symmetry and a CNS with cephalization. The endpoint selected was light avoidance, which is a common phenotype of planarians and rodents and an index of defensive responding that is reduced by anxiolytic compounds in both species. Planarians were placed at the midline of a Petri dish containing water or test solution that was equally split into light and dark halves. Planarians exposed to a selective IL-17A antibody (0.1, 1, 10 pM) over a 5-min interval spent more time in the light than water-exposed planarians. Cyanidin (0.01, 0.1 1, 10 µM), an anti-inflammatory flavonoid and non-selective IL-17A inhibitor, also increased time spent in the light. Motility was not affected by IL-17A antibody or cyanidin at concentrations that reduced light avoidance, although higher concentrations reduced motility (>10 µM). Our results show that IL-17A antagonists reduce defensive responding in planarians and suggest conservation of IL-17A effects on aspects of anxiety-related behaviors.

Supporting ecosystem services of habitat and biodiversity in temperate seaweed (Saccharina spp.) farms

Habitat provisioning, and the biodiversity within, is considered a type of "supporting" ecosystem service. Ecosystem services are the benefits humans receive from healthy ecosystems. We assess whether kelp (Saccharina spp.) farms provide seasonal habitat for wild organisms. Contrary to other studies conducted in tropic seaweed farms, we did not observe habitat provisioning or increased biodiversity at seasonal temperate seaweed farm sites compared to neighboring non-farm sites, which is encouraging news for the aquaculture industry given that most farm gear is removed from the water after the spring harvest. We quantified fish and crustaceans interacting with kelp farms using GoPro cameras. We also assessed small (<5 mm) invertebrates using mesh settling devices suspended at the same depth as kelp lines (2m). Visual surveys were paired with eDNA. There was coherence in the conclusions drawn from observational and eDNA methods, despite weak coherence in the specific species identified between the methods. Both farm and non-farm sites exhibited higher species richness and biodiversity in the summer non-growing season compared to the winter growing season, attributed to expected seasonal species movements.

Exploring the mitochondrial genome of Caridina pseudogracilirostris: a comparative analysis within the Atyidae Family

BACKGROUND

Caridina pseudogracilirostris is a highly adaptive estuarine species found in brackish waters and marshes along the southwestern and southern coastal regions of India.

METHODS AND RESULTS

The whole mitochondrial genome of C. pseudogracilirostris is 15,451 bp in length with 59.3% AT content and encodes 37 genes, including 22 tRNAs, 13 protein-coding genes, and two rRNAs, which are arranged in a distinctive pattern similar to most crustaceans. ML and BI methods were used for phylogenetic analysis of C. pseudogracilirostris clustered with other Caridina species, supporting the monophyly of the Caridina genus within the Atyidae family. The fully annotated mitochondrial genome of C. pseudogracilirostris was submitted to GenBank under accession number OQ534868.1.

CONCLUSIONS

We are the first to report on the C. pseudogracilirostris whole mitochondrial genome, which provides a valuable resource for future research on genetics, evolution, phylogenetics, etc., among Caridina species and other species. The phylogenetic investigation supports the monophyly of the Caridina genus within the Atyidae family and emphasizes the value of mitochondrial genome data in determining the evolutionary relationships among crustaceans.

Putting a new spin on insect jumping performance using 3D modeling and computer simulations of spotted lanternfly nymphs

How animals jump and land on diverse surfaces is ecologically important and relevant to bioinspired robotics. Here, we describe the jumping biomechanics of the planthopper Lycorma delicatula (spotted lanternfly), an invasive insect in the USA that jumps frequently for dispersal, locomotion and predator evasion. High-speed video was used to analyze jumping by spotted lanternfly nymphs from take-off to impact on compliant surfaces. These insects used rapid hindleg extensions to achieve high take-off speeds (2.7-3.4 m s-1) and accelerations (800-1000 m s-2), with mid-air trajectories consistent with ballistic motion without drag forces or steering. Despite rotating rapidly (5-45 Hz) about time-varying axes of rotation, they landed successfully in 58.9% of trials. They also attained the most successful impact orientation significantly more often than predicted by chance, consistent with their using attitude control. Notably, these insects were able to land successfully when impacting surfaces at all angles, pointing to the importance of collisional recovery behaviors. To further understand their rotational dynamics, we created realistic 3D rendered models of spotted lanternflies and used them to compute their mechanical properties during jumping. Computer simulations based on these models and drag torques estimated from fits to tracked data successfully predicted several features of the measured rotational kinematics. This analysis showed that the rotational inertia of spotted lanternfly nymphs is predominantly due to their legs, enabling them to use posture changes as well as drag torque to control their angular velocity, and hence their orientation, thereby facilitating predominately successful landings when jumping.

Tools for photomotor response assay standardization in ecotoxicological studies: Example of exposure to gentamicin in the freshwater planaria Schmidtea mediterranea

Photomotor response assay (PMR) is very useful in an ecotoxicological context because it allows evaluation of behavioral response to potential toxic compounds. However, a lack of procedure standardization makes results comparison difficult between labs and organisms. Here, we aimed to propose five different tools to standardize the PMR procedure so that it may be applied to all model species, regarding: (1) the minimum total sample size, (2) the acclimation period, (3) the number and duration of light and dark phases alternation, (4) the measured behavior, and (5) the statistical analysis. As an example of procedure application, we analyzed the effect of an exposure to the antibiotic gentamicin on the locomotion behavior during PMR in an invertebrate species: the asexual freshwater planaria Schmidtea mediterranea. We encourage future studies using PMR to follow these five tools to improve data analysis and results comparability.

Triploid animals, a potential model for ETosis research: Influence of polyploidy on the formation and efficacy of extracellular traps in the eastern oyster

Decondensation and the subsequent release of chromatin from specific immune cells in response to inflammatory stimuli is a highly conserved aspect of the innate immune system and leads to the formation of extracellular traps, observable in nearly all forms of multicellular life. This process is known as ETosis, with the release of DNA and its associated antimicrobial proteins physically capturing and neutralizing pathogens following an infection or tissue damage. Despite the universality of this response, data concerning extracellular traps in non-model organisms is limited, with most invertebrate studies doing little more than proving their existence due to difficulties in stimulation and high interindividual variability in trap production. This study provides a novel, simple, and inexpensive method for the consistent stimulation of extracellular traps in eastern oyster (Crassostrea virginica) hemocytes. Using the methods described in this study, we compared how ploidy impacts the rate, size, and efficacy of extracellular traps. Findings demonstrated that hemocyte extracellular traps were potent antimicrobials against both Gram-positive and Gram-negative bacteria. Furthermore, we provide evidence to suggest that agranulocytes may be the primary ETosis effector cells in C. virginica. This study is the first to describe extracellular traps in C. virginica and highlights the possible benefits of using triploid animals to gain a further understanding of ETosis and the factors that regulate its induction and efficacy.

Repetitive nociceptive stimulation elicits complex behavioral changes in Hirudo: evidence of arousal and motivational adaptations

Appropriate responses to real or potential damaging stimuli to the body (nociception) are critical to an animal's short- and long-term survival. The initial goal of this study was to examine habituation of withdrawal reflexes (whole-body and local shortening) to repeated mechanical nociceptive stimuli (needle pokes) in the medicinal leech, Hirudo verbana, and assess whether injury altered habituation to these nociceptive stimuli. While repeated needle pokes did reduce shortening in H. verbana, a second set of behavior changes was observed. Specifically, animals began to evade subsequent stimuli by either hiding their posterior sucker underneath adjacent body segments or engaging in locomotion (crawling). Animals differed in terms of how quickly they adopted evasion behaviors during repeated stimulation, exhibiting a multi-modal distribution for early, intermediate and late evaders. Prior injury had a profound effect on this transition, decreasing the time frame in which animals began to carry out evasion and increasing the magnitude of these evasion behaviors (more locomotory evasion). The data indicate the presence in Hirudo of a complex and adaptive defensive arousal process to avoid noxious stimuli that is influenced by differences in internal states, prior experience with injury of the stimulated areas, and possibly learning-based processes.

Testing evolutionary adaptation potential under climate change in invertebrates (mostly Drosophila): findings, limitations and directions

A (quite) large set of experiments has been undertaken to assess the potential for evolutionary changes in invertebrates under current and future climate change conditions. These experimental studies have established some key principles that could affect climate change adaptation, yet there remain substantial obstacles in reaching a meaningful predictive framework. This Review starts with exploring some of the traits considered in individuals and approaches used in assessing evolutionary adaptation relevant to climate, and some of the core findings and their substantial limitations, with a focus on Drosophila. We interpret results in terms of adaptive limits based on population processes versus fundamental mechanistic limits of organisms. We then consider the challenges in moving towards a predictive framework and implications of the findings obtained to date, while also emphasizing the current limited context and the need to broaden it if links to changes in natural populations are to be realized.

Electrophysiological characterization of a schistosome transient receptor potential channel activated by praziquantel

Ion channels have proved to be productive targets for anthelmintic chemotherapy. One example is the recent discovery of a parasitic flatworm ion channel targeted by praziquantel (PZQ), the main clinical therapy used for treatment of schistosomiasis. The ion channel activated by PZQ - a transient receptor potential ion channel of the melastatin subfamily, named TRPMPZQ - is a Ca2+-permeable ion channel expressed in all parasitic flatworms that are PZQ-sensitive. However, little is currently known about the electrophysiological properties of this target that mediates the deleterious action of PZQ on many trematodes and cestodes. Here, we provide a detailed biophysical characterization of the properties of Schistosoma mansoni TRPMPZQ channel (Sm.TRPMPZQ) in response to PZQ. Single channel electrophysiological analysis demonstrated that Sm.TRPMPZQ when activated by PZQ is a non-selective, large conductance, voltage-insensitive cation channel that displays distinct properties from human TRPM paralogs. Sm.TRPMPZQ is Ca2+-permeable but does not require Ca2+ for channel gating in response to PZQ. TRPMPZQ from Schistosoma japonicum (Sj.TRPMPZQ) and Schistosoma haematobium (Sh.TRPMPZQ) displayed similar characteristics. Profiling Sm.TRPMPZQ responsiveness to PZQ has established a biophysical signature for this channel that will aid future investigation of endogenous TRPMPZQ activity, as well as analyses of endogenous and exogenous regulators of this novel, druggable antiparasitic target.

Associations between DNA methylation and gene regulation depend on chromatin accessibility during transgenerational plasticity

BACKGROUND

Epigenetic processes are proposed to be a mechanism regulating gene expression during phenotypic plasticity. However, environmentally induced changes in DNA methylation exhibit little-to-no association with differential gene expression in metazoans at a transcriptome-wide level. It remains unexplored whether associations between environmentally induced differential methylation and expression are contingent upon other epigenomic processes such as chromatin accessibility. We quantified methylation and gene expression in larvae of the purple sea urchin Strongylocentrotus purpuratus exposed to different ecologically relevant conditions during gametogenesis (maternal conditioning) and modeled changes in gene expression and splicing resulting from maternal conditioning as functions of differential methylation, incorporating covariates for genomic features and chromatin accessibility. We detected significant interactions between differential methylation, chromatin accessibility, and genic feature type associated with differential expression and splicing.

RESULTS

Differential gene body methylation had significantly stronger effects on expression among genes with poorly accessible transcriptional start sites while baseline transcript abundance influenced the direction of this effect. Transcriptional responses to maternal conditioning were 4-13 × more likely when accounting for interactions between methylation and chromatin accessibility, demonstrating that the relationship between differential methylation and gene regulation is partially explained by chromatin state.

CONCLUSIONS

DNA methylation likely possesses multiple associations with gene regulation during transgenerational plasticity in S. purpuratus and potentially other metazoans, but its effects are dependent on chromatin accessibility and underlying genic features.

Optimization and calibration of behavioural tests on different species of planaria for ecotoxicological studies

Freshwater planarian are emerging as a valuable in vivo model for (eco) toxicological studies, but the lack of harmonization of procedures between laboratories remains a challenge. This study aimed to optimize, automate and select the best behavioural tests and analyse the potential of different planarian species as models for toxicological assessment. We implemented four tests: exploration, photomotor response, Tapping and Planarian Light Dark Test, on different planaria species using the DanioVision system. We conclude that the exploration assay performed in 24 wellplate at 10 000 lux is the one that is robust and reliable for toxicological studies with planaria. Dugesia japonica and Schmidtea mediterranea have proved to be sensitive models for toxicological screening of organophosphorus pesticides through behavioural analysis. Under necessary experimental conditions, the motility baseline in controls, for both species allowed the detection of behavioural changes, making both good models for behavioural testing in (eco) toxicological context.

Plausibility of Daphnia magna as an alternative experimental model to evaluate effects on eicosanoid synthesis

Eicosanoids play important roles in inflammation, allergy, fever, and immune responses. In the eicosanoid pathway, cyclooxygenase (COX) catalyzes the conversion of arachidonic acid to prostaglandins and is a crucial target of nonsteroidal anti-inflammatory drugs (NSAIDs). Thus, toxicological studies on the eicosanoid pathway are important for drug discovery and the evaluation of adverse health outcomes due to environmental contaminants. However, experimental models are limited owing to concerns regarding ethical standards. Thus, new alternative models for evaluating toxic effects on the eicosanoid pathway must be developed. To this end, we adopted an invertebrate species, Daphnia magna, as an alternative model. D. magna was exposed to ibuprofen, a major NSAID, for 6 and 24 h. Transcription of eicosanoid-related genes (pla2, cox, pgd synthase, pgd2r2, ltb4dh, and lox) was analyzed by qPCR, eicosanoids (arachidonic acid, prostaglandin F2, dihydroxy prostaglandin F2, and 5-hydroxyeicosatetraenoate) were quantified by multiple reaction monitoring, and enzyme-linked immunosorbent assay was used to determine protein levels of arachidonic acid and prostaglandin E2 (PGE2). After 6 h of exposure, transcription of the pla2 and cox genes was downregulated. In addition, the whole-body level of arachidonic acid, an upstream of COX pathway, increased by over 1.5-fold. The levels of PGE2, a downstream of COX pathway, decreased after 24 h of exposure. According to our results, it is expected that the eicosanoid pathway might be conserved in D. magna, at least partially. This indicates the plausibility of D. magna as an alternative model for the screening of new drugs or chemical toxicity.

Without a pinch of salt: effect of low salinity on eggs and nauplii of the salmon louse (Lepeophtheirus salmonis)

The salmon louse is an economically important parasite on Atlantic salmon and poses a major threat to aquaculture. Several treatment methods have lost their effect due to resistance development in the lice. A rather new method for combatting sea lice is freshwater treatment where the various life stages of lice are differently affected by this treatment. In this study, we analyzed the effect of freshwater on the egg strings. A 3-h treatment with freshwater had a detrimental effect on the egg strings. First, the water penetrated the string, widening it, then entering the eggs and enlarging them. Finally, the ordered structure of the egg strings collapsed, and no alive animals hatched. Shorter treatments had a lower effectivity, and treatments with brackish water also showed milder effects. The egg strings were found to have a protective effect against low salinities, as hatched nauplii died rapidly under conditions that embryos survived. We also found that embryos react to low salinity on a molecular level by changing gene expression of several genes, when incubated in brackish water. Additionally, the hatching of embryos treated with brackish water was delayed in comparison to seawater controls.

Chlorine substitution-dependent toxicities of polychlorinated biphenyls to the earthworm Eisenia fetida in soil

Polychlorinated biphenyls (PCBs) with different chlorine substitution patterns often coexist in e-waste-processing sites. However, the single and combined toxicity of PCBs to soil organisms and the influence of chlorine substitution patterns remain largely unknown. Herein, we evaluated the distinct in vivo toxicity of PCB28 (a trichlorinated PCB), PCB52 (a tetrachlorinated PCB), PCB101 (a pentachlorinated PCB), and their mixture to earthworm Eisenia fetida in soil, and looked into the underlining mechanisms in an in vitro test using coelomocytes. After a 28-days exposure, all PCBs (up to 10 mg/kg) were not fatal to earthworms, but could induce intestinal histopathological changes and microbial community alterations in the drilosphere system, along with a significant weight loss. Notably, pentachlorinated PCBs with a low bioaccumulation ability showed greater inhibitory effects on the growth of earthworm than lowly chlorinated PCBs, suggesting that bioaccumulation was not the main determinant of chlorine substitution-dependent toxicity. Furthermore, in vitro assays showed that the highly chlorinated PCBs induced a high-percentage apoptosis of eleocytes in the coelomocytes and significantly activated antioxidant enzymes, indicating that the distinct cellular vulnerability to lowly/highly chlorinated PCBs was the main contributor to the PCBs toxicity. These findings emphasize the specific advantage of using earthworms in the control of lowly chlorinated PCBs in soil due to their high tolerance and accumulation ability.

Contrasting adaptive genetic consequences of stream insects under changing climate

Freshwater biodiversity undergoes degradation due to climate change. Researchers have inferred the effects of climate change on neutral genetic diversity, assuming the fixed spatial distributions of alleles. However, the adaptive genetic evolution of populations that may change the spatial distribution of allele frequencies along environmental gradients (i.e., evolutionary rescue) have largely been overlooked. We developed a modeling approach that projects the comparatively adaptive and neutral genetic diversities of four stream insects, using empirical neutral/ putative adaptive loci, ecological niche models (ENMs), and a distributed hydrological-thermal simulation at a temperate catchment under climate change. The hydrothermal model was used to generate hydraulic and thermal variables (e.g., annual current velocity and water temperature) at the present and the climatic change conditions, projected based on the eight general circulation models and the three representative concentration pathways scenarios for the two future periods (2031-2050, near future; 2081-2100, far future). The hydraulic and thermal variables were used for predictor variables of the ENMs and adaptive genetic modeling based on machine learning approaches. The increases in annual water temperature in the near- (+0.3-0.7 °C) and far-future (+0.4-3.2 °C) were projected. Of the studied species, with different ecologies and habitat ranges, Ephemera japonica (Ephemeroptera) was projected to lose rear-edge habitats (i.e., downstream) but retain the adaptive genetic diversity owing to evolutionary rescue. In contrast, the habitat range of the upstream-dwelling Hydropsyche albicephala (Trichoptera) was found to remarkably decline, resulting in decreases in the watershed genetic diversity. While the other two Trichoptera species expanded their habitat ranges, the genetic structures were homogenized over the watershed and experienced moderate decreases in gamma diversity. The findings emphasize the evolutionary rescue potential, depending on the extent of species-specific local adaptation.

Impact of invertebrates on water quality safety and their sheltering effect on bacteria in water supply systems

Invertebrates in drinking water not only affect human health, but also provide migration and shelter for pathogenic microorganisms. Their residues and metabolites also produce DBPs (disinfection by-products), which have adverse effects on the health of residents. In this study, the contributions of the rotifers and nematodes to the BDOC (biodegradable dissolved organic carbon), BRP (bacterial regrowth potential) and DBPs in drinking water were explored, and the sheltering effects of chlorine-resistant invertebrates on indigenous bacteria and pathogenic bacteria were studied, and the health and safety risk of invertebrates in drinking water was also assessed. The contributions of rotifer BAPs (biomass-associated products), UAPs (utilization-associated products) of rotifer, and nematode BAPs to the BRP were 46, 1240, and 24 CFU/mL. Nematodes were found to have a sheltering effect on indigenous bacteria and pathogenic bacteria, allowing them to resist chlorine disinfection and UV (ultraviolet) disinfection. When subjected to a UV dose of 40 mJ/cm², the inactivation rates of indigenous bacteria and three pathogenic bacteria decreased by 85% and 39-50% when bacteria were sheltered by the living nematodes; while decreased by 66% and 15-41% when they were sheltered by nematode residue. The safety risk posed by invertebrates in the drinking water was mainly due to their ability to promote bacterial regeneration and carry bacteria. This study aims to provide a theoretical basis and technical support for the risk control of invertebrates' pollution, and provides references for ensuring the safety of drinking water and formulating standards for the levels of invertebrates in drinking water.

The effect of chemical dispersion and temperature on the metabolic and cardiac responses to physically dispersed crude oil exposure in larval American lobster (Homarus americanus)

Despite their potential vulnerability to oil spills, little is known about the physiological effects of petroleum exposure and spill responses in cold-water marine animal larvae. We investigated the effects of physically dispersed (water-accommodated fraction, WAF) and chemically dispersed (chemically enhanced WAF, CEWAF; using Slickgone EW) conventional heavy crude oil on the routine metabolic rate and heart rate of stage I larval American lobster (Homarus americanus). We found no effects of 24-h exposure to sublethal concentrations of crude oil WAF or CEWAF at 12 °C. We then investigated the effect of sublethal concentrations of WAFs at three environmentally relevant temperatures (9, 12, 15 °C). The highest WAF concentration increased metabolic rate at 9 °C, whereas it decreased heart rate and increased mortality at 15 °C. Overall, metabolic and cardiac function of American lobster larvae is relatively resilient to conventional heavy crude oil and Slickgone EW exposure, but responses to WAF may be temperature-dependent.

Ultrastructural characterization of the putative defensive glands (warts) in the sessile, colonial rotifer Sinantherina socialis (Gnesiotrocha; Flosculariidae)

Female Sinantherina socialis are freshwater, sessile, colonial rotifers that possess two pairs of distinctive glands (warts) located below the corona. Previous studies demonstrated that colonies are unpalatable to many invertebrate and vertebrate predators; those authors suggested that the warts were a possible source of a chemical deterrent to predation. Here we explore wart ultrastructure and cytochemisty to determine whether the warts function as exocrine glands and if their contents display any allomone-like chemistry, respectively. Externally, the warts appear as elevated bulges without pores. Internally, the warts are specialized regions of the integumental syncytium and therefore acellular. The lipid stain Nile Red labels all four warts. Two lipid membrane probes (sphingomyelin and phosphatidylinositol) also bind the warts and may be staining internal secretion vesicle membranes. In fact, wart ultrastructure is defined by hundreds of membrane-bound secretion vesicles packed tightly together. The vesicles are mostly electron-lucent and crowded into a well-defined cytoplasmic space. The cytoplasm also contains abundant ribosomes, rough endoplasmic reticulum, mitochondria, and Golgi, but nuclei are generally positioned peripheral to the packed vesicles. Absence of muscles around the warts or any signs of direct innervation suggests expulsion of gland contents is forced by general body contraction. A single specimen with 'empty' warts implies that secretions are released en masse from all glands simultaneously. The identity of the chemical secretion remains to be determined, but the lack of osmium and uranyl acetate staining suggests a low abundance or absence of phenols, unsaturated lipids, or NH2 and -COOH groups. This absence, combined with the positive Nile Red staining, is interpreted as evidence that vesicles contain saturated fatty acids such as lactones that are unpalatable to predators.

SUMO and PIAS repress NF-κB activation in a basal chordate

Small ubiquitin-like modifier (SUMO) regulates various biological processes, including the MyD88/TICAMs-IRAKs-TRAF6-NF-κB pathway, one of the core immune pathways. However, its functions are inconsistent between invertebrates and vertebrates and have rarely been investigated in lower chordates, including amphioxus and fishes. Here, we investigated the SUMOylation gene system in the amphioxus, a living basal chordate. We found that amphioxus has a SUMOylation system that has a complete set of genes and preserves several ancestral traits. We proceeded to study their molecular functions using the mammal cell lines. Both amphioxus SUMO1 and SUMO2 were shown to be able to attach to NF-κB Rel and to inhibit NF-κB activation by 50-75% in a dose-dependent fashion. The inhibition by SUMO2 could be further enhanced by the addition of the SUMO E2 ligase UBC9. In comparison, while human SUMO2 inhibited RelA, human SUMO1 slightly activated RelA. We also showed that, similar to human PIAS1-4, amphioxus PIAS could serve as a SUMO E3 ligase and promote its self-SUMOylation. This suggests that amphioxus PIAS is functionally compatible in human cells. Moreover, we showed that amphioxus PIAS is not only able to inhibit NF-κB activation induced by MyD88, TICAM-like, TRAF6 and IRAK4 but also able to suppress NF-κB Rel completely in the presence of SUMO1/2 in a dose-insensitive manner. This suggests that PIAS could effectively block Rel by promoting Rel SUMOylation. In comparison, in humans, only PIAS3, but not PIAS1/2/4, has been reported to promote NF-κB SUMOylation. Taken together, the findings from amphioxus, together with those from mammals and other species, not only offer insights into the functional volatility of the animal SUMO system, but also shed light on its evolutionary transitions from amphioxus to fish, and ultimately to humans.

Early gonadal differentiation is associated with the antagonistic action of Foxl2 and Dmrt1l in the Pacific oyster

As the second largest phylum in the zoological kingdom next to arthropods, the mechanism of gonadal differentiation in mollusca is quite complex. Currently, although much has been carried out on gonadal differentiation in the Pacific oyster, there is still unknown information that needs to be further explored. Here, analysis of the Foxl2 and Dmrt1l expression in samples at different development periods of male and female gonads as well as in annual gonad samples revealed that Log₁₀ (Foxl2/Dmrt1l) values were an effective method for sex identification in oysters. In differentiated gonadal tissue, Log₁₀ (Foxl2/Dmrt1l) values greater than 2 were females and less than 1 for males. Subsequent sequential sampling of the same individuals verified that Log₁₀ (Foxl2/Dmrt1l) values greater than 2 for resting gonads would develop as females and less than 1 would develop as males in the future. Relative expression analysis of Foxl2 and Dmrt1l in the annual samples revealed a negative correlation between Log₁₀ (Foxl2) and Log₁₀ (Dmrt1l). Double fluorescence reporter validation results showed that DMRT1L protein was able to bind the Foxl2 promoter and repress its activity with a weak dosage effect. Antagonism between Dmrt1l and Foxl2 is therefore not restricted to vertebrates, and the competing regulatory networks are of great significance in the maintenance of gonadal sex in oysters after sexual differentiation. This study provides novel ideas and insights into the study of early gonadal differentiation in the adult oyster.

Copper toxicity does not affect low tide emersion tolerance of Mytilus galloprovincialis

Intertidal mussels are well adapted to withstand emersion from water during low tide, but they may be intermittently exposed to waterborne toxicants such as copper, which targets physiological processes including metabolism, ammonia excretion, and osmoregulation. To determine if copper exposure damages intertidal organisms' ability to tolerate tidal emersion, Mediterranean mussels (Mytilus galloprovincialis) were exposed to copper for 96 h followed by 6 h of emersion. Oxygen uptake increased after copper exposure which suggests that copper accumulation caused moderate stress in the mussels, but ammonia excretion and anaerobic metabolism were unaffected by mixed copper and emersion exposures. Shell composition analyses indicate that cycles of copper exposure and tidal emersion may affect bivalve shell growth, but copper deposition into shells may decrease the metal's overall toxicity. Results suggest that copper does not damage M. galloprovincialis's tolerance to tidal emersion, and insight is provided into the mussel's ability to overcome mixed stressor exposures.

Co-contaminants of ethinylestradiol and sulfamethoxazole in groundwater exacerbate ecotoxicity and ecological risk and compromise the energy budget of C. elegans

Ethinylestradiol (EE2) and sulfamethoxazole (SMX) are among pharmaceuticals and personal care products (PPCPs) and regarded as emerging contaminants in groundwater worldwide. However, the ecotoxicity and potential risk of these co-contaminants remain unknown. We investigated the effects of early-life long-term co-exposure to EE2 and SMX in groundwater on life-history traits of Caenorhabditis elegans and determined potential ecological risks in groundwater. L1 larvae of wild-type N2 C. elegans were exposed to measured concentrations of EE2 (0.001, 0.75, 5.1, 11.8 mg/L) or SMX (0.001, 1, 10, 100 mg/L) or co-exposed to EE2 (0.75 mg/L, no observed adverse effect level derived from its reproductive toxicity) and SMX (0.001, 1, 10, 100 mg/L) in groundwater. Growth and reproduction were monitored on days 0 - 6 of the exposure period. Toxicological data were analyzed using DEBtox modeling to determine the physiological modes of action (pMoAs) and the predicted no-effect concentrations (PNECs) to estimate ecological risks posed by EE2 and SMX in global groundwater. Early-life EE2 exposure significantly inhibited the growth and reproduction of C. elegans, with lowest observed adverse effect levels (LOAELs) of 11.8 and 5.1 mg/L, respectively. SMX exposure impaired the reproductive capacity of C. elegans (LOAEL = 0.001 mg/L). Co-exposure to EE2 and SMX exacerbated ecotoxicity (LOAELs of 1 mg/L SMX for growth, and 0.001 mg/L SMX for reproduction). DEBtox modeling showed that the pMoAs were increased growth and reproduction costs for EE2 and increased reproduction costs for SMX. The derived PNEC falls within the range of detected environmental levels of EE2 and SMX in groundwater worldwide. The pMoAs for EE2 and SMX combined were increased growth and reproduction costs, resulting in lower energy threshold values than single exposure. Based on global groundwater contamination data and energy threshold values, we calculated risk quotients for EE2 (0.1 - 123.0), SMX (0.2 - 91.3), and combination of EE2 and SMX (0.4 - 341.1). Our findings found that co-contamination by EE2 and SMX exacerbates toxicity and ecological risk to non-target organisms, suggesting that the ecotoxicity and ecological risk of co-contaminants of pharmaceuticals should be considered to sustainably manage groundwater and aquatic ecosystems.

Control of high-speed jumps: the rotation and energetics of the locust (Schistocerca gregaria)

Locusts (Schistocerca gregaria) jump using a latch mediated spring actuated system in the femur-tibia joint of their metathoracic legs. These jumps are exceptionally fast and display angular rotation immediately after take-off. In this study, we focus on the angular velocity, at take-off, of locusts ranging between 0.049 and 1.50 g to determine if and how rotation-rate scales with size. From 263 jumps recorded from 44 individuals, we found that angular velocity scales with mass^-0.33, consistent with a hypothesis of locusts having a constant rotational kinetic energy density. Within the data from each locust, angular velocity increased proportionally with linear velocity, suggesting the two cannot be independently controlled and thus a fixed energy budget is formed at take-off. On average, the energy budget of a jump is distributed 98.7% to translational kinetic energy and gravitational potential energy, and 1.3% to rotational kinetic energy. The percentage of energy devoted to rotation was constant across all sizes of locusts and represents a very small proportion of the energy budget. This analysis suggests that smaller locusts find it harder to jump without body rotation.

Previous stress causes a contrasting response to cadmium toxicity in the aquatic snail Potamopyrgus antipodarum: lethal and behavioral endpoints

In aquatic ecosystems, animals are often exposed to a combination of stressors, including both natural and anthropogenic factors. Combined stressors may have additive or interactive effects on animals, either magnifying or reducing the effects caused by each stressor alone. Therefore, standardized bioassays can lead to overestimations or underestimations of the risk of toxicants if natural stressors are not bear in mind. The inclusion of natural stress in laboratory bioassays may help to extrapolate the laboratory results to ecosystems. This study assesses the effects of successive exposure to two sources of stress (high water conductivity and cadmium toxicity) on the behavior and survival of the aquatic snail Potamopyrgus antipodarum (Tateidae, Mollusca). I conducted a bioassay consisting on exposure to high conductivity (5000 mg NaCl/L, 7 days), followed by exposure to cadmium (0.03, 0.125, and 0.25 mg Cd/L for 7 days) and by a post-exposure period (7 days). Mortality, inactivity, and the time to start activity of active animals were monitored in each animal. In general, cadmium lethality was higher in animals previously undergoing high conductivity than in non-stressed ones. Previously stressed animals showed longer time to start activity, with a noticeable effect at the two highest cadmium concentrations. Animals submitted to the two highest cadmium concentration both, stressed and non-stressed, showed a moderate recovery during the post-exposure period. It is concluded that previous stress caused a worsening of the cadmium toxicity on the aquatic snail Potamopyrgus antipodarum, which is especially noticeable for mortality. However, there was no interactive effect between cadmium and conductivity on snail activity, which may be indicative of recovery after cadmium exposure regardless the previous stress suffered by the snails.