Oxidative and osmotolerant effects in Salvator merianae (Squamata: Teiidae) red blood cells during hibernation / Efeitos de oxidação e osmotolerância dos eritrócitos de Salvator merianae (Squamata: Teiidae) durante a hibernação

Abstract Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or "tegu" lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.

Resumo A hibernação é uma condição natural dos animais que vivem na zona temperada, embora alguns lagartos tropicais também experenciem hibernação anualmente, como é o caso do lagarto nativo da América do Sul, Salvator merianae ou "teiú". Embora as características fisiológicas e metabólicas associadas à hibernação tenham sido amplamente estudadas, possíveis alterações na integridade das hemácias durante esse período ainda permanecem obscuras. A desidratação e o jejum são consequências naturais da hibernação por vários meses e podem estar relacionadas a algumas modificações celulares. Neste estudo, investigamos se a tolerância osmótica de hemácias do lagarto teiú sob hibernação são diferentes das células obtidas de animais em atividade normal. Além disso, investigamos indiretamente por meio da quantificação de biomoléculas oxidadas e da atividade de enzimas antioxidantes se a membrana das hemácias dos teiús em hibernação poderia estar associada à oxidação. Nossos resultados sugerem que as hemácias possuem maior fragilidade durante o período de hibernação, embora não tenhamos encontrado evidências de um cenário de estresse oxidativo associado à essa fragilidade acentuada. Embora não tenhamos excluído a possibilidade de dano oxidativo durante a hibernação, sugerimos que um aumento no volume das hemácias como consequência de sangue hipoosmótico durante a hibernação também poderia afetar a integridade de hemácias, tal como foi observado.

Oxidative and osmotolerant effects in Salvator merianae (Squamata: Teiidae) red blood cells during hibernation

Abstract Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or tegu lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.

Resumo A hibernação é uma condição natural dos animais que vivem na zona temperada, embora alguns lagartos tropicais também experenciem hibernação anualmente, como é o caso do lagarto nativo da América do Sul, Salvator merianae ou teiú. Embora as características fisiológicas e metabólicas associadas à hibernação tenham sido amplamente estudadas, possíveis alterações na integridade das hemácias durante esse período ainda permanecem obscuras. A desidratação e o jejum são consequências naturais da hibernação por vários meses e podem estar relacionadas a algumas modificações celulares. Neste estudo, investigamos se a tolerância osmótica de hemácias do lagarto teiú sob hibernação são diferentes das células obtidas de animais em atividade normal. Além disso, investigamos indiretamente por meio da quantificação de biomoléculas oxidadas e da atividade de enzimas antioxidantes se a membrana das hemácias dos teiús em hibernação poderia estar associada à oxidação. Nossos resultados sugerem que as hemácias possuem maior fragilidade durante o período de hibernação, embora não tenhamos encontrado evidências de um cenário de estresse oxidativo associado à essa fragilidade acentuada. Embora não tenhamos excluído a possibilidade de dano oxidativo durante a hibernação, sugerimos que um aumento no volume das hemácias como consequência de sangue hipoosmótico durante a hibernação também poderia afetar a integridade de hemácias, tal como foi observado.

A pro-BMP function exerted by Rhodnius prolixus short gastrulation reveals great diversity in the role of BMP modulators during embryonic patterning.

Dorsal-ventral (DV) patterning is regulated by the bone morphogenetic pathway (BMP) in Bilateria. In insect DV patterning, the Toll pathway also plays a role, in addition to BMPs. Variations in the relative importance of each pathway for DV patterning have been reported using single species of coleopteran, hymenopteran, hemipteran and orthopteran insects. To investigate if the molecular control of DV patterning is conserved inside an insect order, the emergent model hemiptera species Rhodnius prolixus was studied. We found that R. prolixus BMP pathway controls the entire DV axis, with a broader effect respective to Toll, as shown for the hemiptera Oncopeltus fasciatus. Different from O. fasciatus, the unique R. prolixus short gastrulation (sog) and the twisted gastrulation (tsg) orthologues do not antagonize, but rather favour embryonic BMP signalling. Our results reinforce the hypothesis that hemiptera rely preferentially on BMPs for DV patterning but that, surprisingly, in R. prolixus Sog and Tsg proteins exert only a positive role to establish a dorsal-to-ventral BMP gradient. Since sog has been reported to be lost from orthopteran and hymenopteran genomes, our results indicate that Sog's role to modify BMP activity varies greatly in different insect species.

Thermoelectric transport properties of armchair graphene nanoribbon heterostructures.

In this paper, we numerically analyze the thermoelectric (TE) properties of recently synthesized graphene nanoribbon (GNR) heterostructures that are obtained as extensions of pristine armchair graphene nanoribbons (AGNRs). After simulating their band structure through a nearest-neighbor tight-binding model, we use the Landauer formalism to calculate the necessary TE coefficients, with which we obtain the electrical conductanceG, thermopowerS, thermal conductanceKe, linear-response thermocurrentIth/ΔT=GS, and figure of meritZT(using literature results for the phonon thermal conductanceKph), at room temperature. We then compare the results for the nanoribbon heterostructures with those for the pristine AGNR nanoribbons. The comparison shows that the metallic AGNRs become semiconducting (with much higherZTvalues) after the inclusion of the extensions that transform them into heterostructures and that some heterostructures have higher values ofZTwhen compared to the semiconducting pristine AGNRs from which they have originated.

Influence of particle size on the SARS-CoV-2 spike protein detection using IgG-capped gold nanoparticles and dynamic light scattering.

Due to the unprecedented and ongoing nature of the coronavirus outbreak, the development of rapid immunoassays to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its highly contagious variants is an important and challenging task. Here, we report the development of polyclonal antibody-functionalized spherical gold nanoparticle biosensors as well as the influence of the nanoparticle sizes on the immunoassay response to detect the SARS-CoV-2 spike protein by dynamic light scattering. By monitoring the increment in the hydrodynamic diameter (ΔDH) by dynamic light scattering measurements in the antigen-antibody interaction, SARS-CoV-2 S-protein can be detected in only 5 min. The larger the nanoparticles, the larger ΔDH in the presence of spike protein. From adsorption isotherm, the calculated binding constant (K D ) was 83 nM and the estimated limit of detection was 13 ng/mL (30 pM). The biosensor was stable up to 90 days at 4 °C. Therefore, the biosensor developed in this work could be potentially applied as a fast and sensible immunoassay to detect SARS-CoV-2 infection in patient samples.

Toxicity and physicochemical parameters of composts including distinct residues from agribusiness and slaughterhouse sludge.

Composting is useful for treatment of residues from agribusiness, but the potential toxicity of the final compost should be evaluated before its agricultural destination. The objective of this study was to evaluate the physicochemical characteristics and the toxicity of agribusiness residues using onion seeds as bioindicators. All tested treatments were composed by sludge from a swine slaughterhouse and sawdust. Besides the control, which included no additional materials, the other treatments included aviary bedding, rice husk and residue from tobacco industries as structuring materials. After 120 days of composting, for all treatments, the temperature inside the composting piles approached the environmental temperature, the physicochemical parameters indicated that the composts were stabilized and, except for the treatment including tobacco residues, that could be used for agriculture without impairing plant germination. Although the treatments including tobacco residues and rice husk showed evidence of cytotoxicity and genotoxicity at the beginning of the composting period, that was not observed for the treatment including aviary bedding. Such potential toxicity was not observed at the end of composting for any of the tested treatments.

Morphological and cytochemical characterization of the peripheral blood cells of farmed streaked prochilod Prochilodus lineatus (Characiformes, Prochilodontidae) / [Caracterização morfológica e citoquímica das células do sangue periférico do curimatã Prochilodus lineatus (Characiformes, Prochilodontidae) em cultivo]

Morphological and cytochemical studies of peripheral blood cells of fish have improved the understanding of their functions and cell types. The present study performed the Morphological and cytochemical analysis of the peripheral blood of Prochilodus lineatus, Characiform native to South America, which has been gaining space in local aquaculture and as a species introduced in Asia. Our analysis provided information on the morphological and cytochemical characteristics of the leukocytes, for the formulation of hypothesis about their role in the immune system of the species. It was found that Prochilodus lineatus has morphological and cytochemical features in common with other fish species, mainly of the Characiformes order. However, we detected the presence of heterophils and PAS positive granulocytes simultaneously with neutrophils. We also found that heterophils and PAS positive granulocytes are very similar, both morphologically and cytochemically.(AU)

O estudo da morfologia e da citoquímica das células do sangue periférico dos peixes tem sido eficaz para o entendimento de suas funções e dos tipos celulares. Este estudo realizou a análise morfológica e citoquímica do sangue periférico de Prochilodus lineatus, caracídeo nativo da América do Sul que vem ganhando espaço na aquicultura local e como espécie introduzida na Ásia. Essa análise forneceu informações sobre a morfologia e as características citoquímicas dos leucócitos, visando a hipóteses sobre suas funções. Verificou-se que estas são semelhantes em vários aspectos a outras espécies, principalmente da ordem Characiformes. No entanto, neste estudo detectou-se a presença dos heterofilos e da célula granulocítica especial, simultaneamente à presença dos neutrófilos. Ainda, foi verificado que os heterofilos e a célula granulocítica especial são muito semelhantes morfológica e citoquimicamente.(AU)

Oxidative and osmotolerant effects in Salvator merianae (Squamata: Teiidae) red blood cells during hibernation.

Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or "tegu" lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.

Cutaneous mast cell tumor in a captive Bush dog (Speothos venaticus): pathological and immunophenotypical aspects - case report / Mastocitoma cutâneo em um cachorro-do-mato vinagre (Speothos venaticus) de cativeiro: aspectos patológicos e imunofenotípicos - relato de caso

A senile male captive bush dog (Speothos venaticus) presented a small perianal cutaneous nodule. Histologically, there was an ulcerated round cell tumor composed of well differentiated mast cells with abundant intracytoplasmic purple Giemsa-positive granules, with a diffuse eosinophilic infiltrate. Immunohistochemistry revealed that 30% of the neoplastic cells were positive for Kit in the cytoplasm and cell membrane, and all neoplastic cells were negative for MAC and CD3. Less than 10% of the neoplastic cells were positive for Ki67. At necropsy other primary tumors were identified in this animal, including an intestinal adenoma, an adrenal cortex adenoma and a testicular interstitial cell tumor.(AU)

Um cachorro-vinagre (Speothos venaticus) apresentou um nódulo cutâneo pequeno na região perianal. Histologicamente havia neoplasia cutânea de células redondas e ulcerada, constituída por mastócitos bem diferenciados, com abundantes grânulos citoplasmáticos metacromáticos na coloração de Giemsa e infiltrado eosinofílico difuso. A imuno-histoquímica demonstrou que 30% das células neoplásicas eram positivas para a proteína Kit no citoplasma e na membrana celular. As células foram negativas para MAC e CD3. Menos de 10% das células neoplásicas foram positivas para Ki67. Durante a necropsia, foram identificados outros tumores primários, como adenoma intestinal, adenoma cortical da adrenal e tumor de células intersticiais do testículo.(AU)

Hepatitis E Virus in People Who Use Crack-Cocaine: A Cross-Sectional Study in a Remote Region of Northern Brazil.

People who use crack-cocaine (PWUCC) have numerous vulnerabilities and pose a challenge to health and social assistance services. The exposure to pathogens and risk situations occur differently according to each individual, region and social group. This study identified the presence, genotypes and factors associated with hepatitis E virus (HEV) exposure among a community-recruited cohort of 437 PWUCC in northern Brazil. Epidemiological information was collected through community-based assessments and interviews. Thereafter, blood and fecal samples were collected and tested for HEV using an immunoenzymatic assay, and the genotype was identified by PCR. Logistic regressions were used to identify the risk factors independently associated with exposure to HEV. In total, 79 (18.1%) PWUCC were exposed to HEV: 73 (16.7%) for IgG and six for IgG + IgM. HEV RNA was detected in six fecal samples and in two blood samples from PWUCC with IgM + IgG. Subtype 3c was identified in all of the samples. The factors associated with exposure to HEV were low monthly income, unstable housing (e.g., homelessness), crack-cocaine use ≥40 months, and the shared use of crack-cocaine equipment. The current study provides unique initial insights into HEV status and risk factors among PWUCC in a remote area in Brazil, with diverse implications for urgently improved diagnosis, prevention, and treatment intervention needs.

Lead acetate ecotoxicity in tropical soils.

Lead acetate (AcPb) is an important raw material used in chemical industries worldwide. The potential toxicity of AcPb is generally attributed to the presence of Pb. However, the effect of AcPb on the environment as a whole is still poorly known. This study aimed to evaluate AcPb toxicity on three standard species of soil invertebrates and two plant species using ecotoxicology tests. Three tropical soils (Oxisol, Inceptisol, and Tropical Artificial Soil (TAS)) were contaminated with different concentrations of AcPb and one dose of K-acetate (positive control). These soils were used in tests with Eisenia andrei (earthworm), Folsomia candida (springtail), Enchytraeus crypticus (enchytraeid), Zea mays (maize), and Phaseolus vulgaris (common bean). Dose-response curves obtained in the laboratory tests were used to estimate the EC50 values for each species. Among invertebrates, the highest sensitivity to AcPb was observed for E. crypticus in the TAS (EC50 = 29.8 mg AcPb kg-1), whereas for E. andrei and F. candida the highest sensitivity was observed in the Oxisol (EC50 = 141.9 and 1835 mg AcPb kg-1, respectively). Folsomia candida was the least sensitive invertebrate species to AcPb in all soils. Among plant species, Z. mays was less sensitive (EC50 = 1527.5 mg AcPb kg-1) than P. vulgaris (EC50 = 560.5 mg AcPb kg-1) in the Oxisol. The present study evidenced that the toxicity of AcPb should not be attributed uniquely to the presence of Pb, as the treatment containing uniquely Ac provoked the same toxicity as the highest dose of AcPb.

Electric-field-generated topological states in a silicene nanotube.

Applying an electric field perpendicular to the axis of a silicene armchair nanotube allows us to numerically study the formation of eight topological edge states as silicene's intrinsic spin-orbit gap is closed by the sublattice-staggered electrostatic potential created by the electric field. Following their evolution with electric field, it is revealed that, at very small fields, these eight states are very broad, spin-locked, and sublattice constrained, inheriting their properties from the K and K' states in a silicene two-dimensional honeycomb lattice. Four of those states are centered at the very top of the nanotube and the other four states are centered at the very bottom. As the field increases, each state starts to become narrower and to spread its spectral weight to the other sublattice. With further increase of the field, each state starts to spatially split, while the sublattice spreading continues. Once the spectral weight of each state is distributed evenly among both sublattices, the state has also effectively split into two spatially disconnected parts, after which, further increasing of the field will spread apart the two halves, moving them to the lateral regions of the nanotube, at the same time that the state halves become narrower. This is consistent with the formation of topological edge states, which delimit four ribbon-like topologically different regions: top and bottom topologically trivial 'ribbons' (where the electric field has induced a topological phase transition) that are adjacent to two topologically nontrivial 'ribbons' located at opposing sides of the nanotube. We also briefly access the possibility of observing these edge states by calculating the electronic properties for an electric field configuration that can be more readily produced in the laboratory.

Meta-analysis and systematic review of ADGRL3 (LPHN3) polymorphisms in ADHD susceptibility.

The gene encoding adhesion G protein-coupled receptor L3 (ADGRL3, also referred to as latrophilin 3 or LPHN3) has been associated with ADHD susceptibility in independent ADHD samples. We conducted a systematic review and a comprehensive meta-analysis to summarize the associations between the most studied ADGRL3 polymorphisms (rs6551665, rs1947274, rs1947275, and rs2345039) and both childhood and adulthood ADHD. Eight association studies (seven published and one unpublished) fulfilled criteria for inclusion in our meta-analysis. We also incorporated GWAS data for ADGRL3. In order to avoid overlapping samples, we started with summary statistics from GWAS samples and then added data from gene association studies. The results of our meta-analysis suggest an effect of ADGRL3 variants on ADHD susceptibility in children (n = 8724/14,644 cases/controls and 1893 families): rs6551665 A allele (Z score = -2.701; p = 0.0069); rs1947274 A allele (Z score = -2.033; p = 0.0421); rs1947275 T allele (Z score = 2.339; p = 0.0978); and rs2345039 C allele (Z score = 3.806; p = 0.0026). Heterogeneity was found in analyses for three SNPs (rs6551665, rs1947274, and rs2345039). In adults, results were not significant (n = 6532 cases/15,874 controls): rs6551665 A allele (Z score = 2.005; p = 0.0450); rs1947274 A allele (Z score = 2.179; p = 0.0293); rs1947275 T allele (Z score = -0.822; p = 0.4109); and rs2345039 C allele (Z score = -1.544; p = 0.1226). Heterogeneity was found just for rs6551665. In addition, funnel plots did not suggest publication biases. Consistent with ADGRL3's role in early neurodevelopment, our findings suggest that the gene is predominantly associated with childhood ADHD.

Manganese requirements of broiler breeder hens.

The present research was conducted to assess Mn requirements of broiler breeder hens. One hundred and twenty Cobb 500 hens, 22 wk of age, were individually allocated in cages. After fed a Mn-deficient diet (22.2 ppm), hens were randomly placed in treatments having 6 increments of 30-ppm Mn. All trace minerals were from laboratory grade sources being Mn from Mn sulfate (MnSO4H2O). Treatments were fed for 4 periods of 28 d. There were no interactions between dietary Mn and period for any evaluated response (P > 0.05). Requirements of Mn for hen day egg production and settable egg production were 115.8 and 56.6 ppm and 122.1 and 63.6 ppm (P < 0.05), respectively, using quadratic polynomial (QP) and broken line quadratic (BLQ) models, whereas total eggs and total settable eggs per hen had Mn requirements estimated at 115.7 and 56.6 and 121.8 and 61.7 ppm (P < 0.05), respectively. Number of cracked, defective, and contaminated eggs decreased, whereas hatchability, hatchability of fertile eggs, eggshell percentage, and eggshell palisade layer increased when hens were fed diets having 48.5 to 168.2-ppm Mn (P < 0.05). Maximum responses for egg weight and eggshell percentage were 117.7 and 63.6 ppm as well as 131.6 and 71.0 ppm (P < 0.05), respectively, using QP and BLQ models. Breaking strength and egg specific gravity had Mn requirements estimated at 140.2 and 112.7 ppm as well as 131.3 68.5 ppm (P < 0.05), whereas eggshell palisade layer and eggshell thickness were maximized with 128.8 and 68.8 ppm and 140.2 134.2 ppm, respectively, for QP and BLQ models (P < 0.05). Maximum yolk Mn content values were obtained using 118.0- and 118.4-ppm Mn by QP and BLQ models, respectively. The average Mn requirements estimated for QP and BLQ models is 128.4 and 92.3 ppm Mn (18.7 and 13.5 mg/hen/d), respectively, which is much lower than what has been currently recommended in commercial production.

18F-FDG PET/CT images defined the true extent of a urothelial bladder carcinoma.

A patient was referred, after neoadjuvant chemotherapy, for pre-surgical evaluation of urothelial bladder carcinoma (single lesion). Two thickenings in the left ureter wall identified on the CT scan were equivocal for malignancy. 18F-FDG PET/CT with delayed pelvic images, hyperhydration, and furosemide showed hypermetabolic ureteral metastases and multifocal bladder tumors. There were no lymph nodes or distant metastases. These 18F-FDG PET/CT findings completely altered the surgical treatment. The patient underwent left nephroureterectomy, radical cystoprostatectomy, and lymphadenectomy, followed by a urinary transit reconstruction. Histopathology confirmed multifocal high-grade urothelial carcinoma in the bladder walls and left ureter and benign lymph nodes.

Hair as an alternative noninvasive matrix: sources of variation in testosterone levels.

Hair is one widely used alternative matrix for endocrine studies. Not only can it maintain hormone content during storage for long periods of time, but its collection also induces little to no stress. Noninvasive techniques have broadened the opportunities for endocrine research, particularly regarding wild animals. Despite its advantages, many sources of variation may affect the steroid concentration found in hair, such as body location harvested, fur color, reproductive status, and sex. Thus, domestic species, such as the dog, are an excellent and approachable model for understanding this variability. For such, we addressed diverse sources of variation in testosterone concentrations from 24 domestic dogs (Canis lupus familiaris) of the Poodle breed of various colors and neuter status, and from both sexes. The variation comprised the comparison between 2 different matrices (blood vs hair); 2 different extraction storage methods (refrigerator vs freezer); 3 body regions (head, torso, and limbs); 3 coat colors (black, brown, and white); different neuter status (intact vs castrated males) and, finally, sex. Our results showed no correlation between blood and hair testosterone concentrations. Additionally, we did not find differences related to the storage method, body region, or coat color. There were differences in concentration between males and females, but not between females and castrated males. We discuss hair testosterone levels exhibited reasonable stability, and we present practical applications for both domestic and wildlife animals.

Behavior and gut bacteria of Partamona helleri under sublethal exposure to a bioinsecticide and a leaf fertilizer.

The exposure of bees to agrochemicals during foraging and feeding has been associated with their population decline. Sublethal exposure to agrochemicals can affect behavior and the microbiota. Gut microbiota is associated with insect nutritional health, immunocompetence, and is essential for neutralizing the damage caused by pathogens and xenobiotics. Research on the effect of the bioinsecticides and fertilizers on the microbiota of bees remains neglected. In this study, we assessed the sublethal effect of both bioinsecticide spinosad and the fertilizer copper sulfate (CuSO4) on the behavior and gut microbiota in forager adults of the stingless bee Partamona helleri (Friese), which is an important pollinator in the Neotropical region. Behavioral assays and gut microbiota profiles were assessed on bees orally exposed to estimated LC5 values for spinosad and CuSO4. The microbiota were characterized through 16S rRNA gene target sequencing. Acute and oral sublethal exposure to spinosad and CuSO4 did not affect the overall activity, flight take-off, and food consumption. However, CuSO4 decreased bee respiration rate and copper accumulated in exposed bees. Exposure to spinosad increased the proportional abundance of the genus Gilliamella, but CuSO4 did not alter the composition of the gut microbiota. In conclusion, sublethal exposure to CuSO4 induces changes in respiration, and spinosad changes the abundance of gut microorganisms of P. helleri.

Critical mercury concentration in tropical soils: Impact on plants and soil biological attributes.

Mercury is a toxic element that becomes a problem when present at high concentrations in soils. Mercury toxicity in soils varies depending on chemical species, concentration, exposure routes, and organism vulnerability. There is little information regarding the toxicity of Hg in tropical soils, especially for establishing safe levels of this pollutant. The purpose of this study was to investigate Hg concentrations in two tropical soils and their effect on oats and common beans, as well as on soil biological attributes. The experiment was carried out in a greenhouse, following ISO 11.269-2 and OECD-208 guidelines. Oat and common bean were cultivated in a Typic Hapludox (TyHpx) and Rhodic Acrudox (RhAcx) contaminated with HgCl2 at the following concentrations: 0, 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 mg of Hg kg-1 of dry soil. The biological variables analyzed were seedling emergence, vegetative growth, chlorophyll content (SPAD index), gas exchange (photosynthetic rate, internal CO2 concentration, transpiration rate, and stomatal conductance), and Hg concentration and accumulation in shoot dry matter. Microbial biomass carbon, soil basal respiration, and metabolic quotient (qCO2) were also analyzed. Due to the sorptive characteristics of TyHpx, it had higher Hg concentrations than RhAcx. Mercury showed toxic effects on both oat and common bean species. However, common bean was affected only at concentrations higher than 20 mg kg-1. The microbial community showed high sensitivity to soil Hg concentrations, but external factors, such as the plant species cultivated, influenced the sensitivity of the community. The microbiota was most sensitive in pots with common bean, and this effect was more pronounced at low clay and low organic matter contents (TyHpx). In this study, the concentration of 0.36 mg kg-1 was critical for Hg in these soils, based on its deleterious effects on oat and common bean and on biological soil attributes.