Investigating the impact of Psidium guajava leaf hydroalcoholic extract in improving glutamatergic toxicity-induced oxidative stress in Danio rerio larvae.

Glutamate is one of the predominant excitatory neurotransmitters released from the central nervous system; however, at high concentrations, this substance may induce excitotoxicity. This phenomenon is involved in numerous neuropathologies. At present, clinically available pharmacotherapeutic agents to counteract glutamatergic excitotoxicity are not completely effective; therefore, research to develop novel compounds is necessary. In this study, the main objective was to determine the pharmacotherapeutic potential of the hydroalcoholic extract of Psidium guajava (PG) in a model of oxidative stress-induced by exposure to glutamate utilizing Danio rerio larvae (zebrafish) as a model. Data showed that treatment with glutamate produced a significant increase in oxidative stress, chromatin damage, apoptosis, and locomotor dysfunction. All these effects were attenuated by pre-treatment with the classical antioxidant N-acetylcysteine (NAC). Treatment with PG inhibited oxidative stress responsible for cellular damage induced by glutamate. However, exposure to PG failed to prevent glutamate-initiated locomotor damage. Our findings suggest that under conditions of oxidative stress, PG can be considered as a promising candidate for treatment of glutamatergic excitotoxicity and consequent neurodegenerative diseases.

Course on Breeding, Handling, and Experimental Procedures of Zebrafish (Danio rerio): Training, Refinement, Paradigm Shift, and Dissemination of Knowledge from Brazil to the World.

Currently, in Brazil, all researchers involved in animal experimentation must undergo training in laboratory animal science to stay updated on biology, methodology, ethics, and legal considerations related to the use of animals. The training program presented in this study not only aims to fulfill a legal obligation but also intends to train students and professionals to effectively care for their biomodels. It seeks to help them understand the importance of this care, both for the welfare of the animals and for the results of their projects. In total, 58 participants were present at the event (pre-event and full-time course). These participants consisted students and professionals from 11 institutions and 5 different countries. These numbers demonstrate the successful attainment of the desired capillarity in the scientific community and the posterior dissemination of knowledge. Through this course, it was possible to train the participants and raise their awareness about the importance of applying scientific knowledge in their daily practices to maintain the animals, ensuring the welfare of the models and refining the research. Finally, the program presented in this study, as well as the strategies adopted, can serve as a model for other institutions aiming to achieve similar results.

Preclinical toxicological assessment of polydatin in zebrafish model.

Polydatin (3,4',5-trihydroxystilbene-3-ß-D-glucoside, piceid), a natural stilbenoid found in different plant sources, has gained increasing attention for its potential health benefits. However, prior to its widespread adoption in human therapeutics and consumer products, a comprehensive investigation of its toxicological effects is crucial. In this study, the toxicity of polydatin was investigated in a developmental toxicity test using zebrafish (Danio rerio) as a valuable model for preclinical assessments. We employed the Fish Embryo Test (FET test - OECD n°236) to investigate the effects of polydatin on survival, hatchability, development, and behavior of zebrafish embryo-larval stage. Remarkably, the results demonstrated that polydatin up to 435 µM showed no toxicity. Throughout the exposure period, zebrafish embryos exposed to polydatin exhibited normal development, with no significant mortality observed. Furthermore, hatching success and heartbeat rate were unaffected, and no morphological abnormalities were identified, signifying a lack of teratogenic effects and cardiotoxicity. Locomotion activity assessment revealed normal swimming patterns and response to stimuli, indicating no neurotoxic effects. Our study provides valuable insights into the toxicological profile of polydatin, suggesting that it may offer potential therapeutic benefits under a considerable concentration range. In addition, zebrafish model proves to be an efficient system for early-stage toxicological screening, guiding further investigations into the secure utilization of polydatin for human health and wellness.

Chlorothalonil as a potential endocrine disruptor in male zebrafish (Danio rerio): Impact on the hypothalamus-pituitary-gonad axis and sperm quality.

Chlorothalonil is a broad-spectrum organochlorine fungicide widely employed in agriculture to control fungal foliar diseases. This fungicide enters aquatic environments through the leaching process, leading to toxicity in non-target organisms. Organic contaminants can impact organism reproduction as they have the potential to interact with the neuroendocrine system. Although there are reports of toxic effects of chlorothalonil, information regarding its impact on reproduction is limited. The aim of the present study was to evaluate the influence of chlorothalonil on male reproductive physiology using the zebrafish (Danio rerio) as ecotoxicological model. Zebrafish were exposed for 7 days to two concentrations of chlorothalonil (0.1 and 10 µg/L) along with a control group (with DMSO - 0.001%). Gene expression of hypothalamus-pituitary-gonad axis components (gnrh2, gnrh3, lhr, fshr, star, hsd17b1, hsd17b3, and cyp19a1), as well as hepatic vitellogenin concentration were assessed. In sperm cells, reactive oxygen species (ROS) content, lipid peroxidation (LPO), mitochondrial functionality, and membrane integrity and fluidity were evaluated. Results indicate that exposure to the higher concentration of chlorothalonil led to a reduction in brain gnr2 expression. In gonads, mRNA levels of lhr, star, and hsd17b1 were decreased at both chlorothalonil concentrations tested. Similarly, hepatic vitellogenin concentration was reduced. Regarding sperm cells, a decreased ROS level was observed, without significant difference in LPO level. Additionally, a higher mitochondrial potential and lower membrane fluidity were observed in zebrafish exposed to chlorothalonil. These findings demonstrate that chlorothalonil acts as an endocrine disruptor, influencing reproductive control mechanisms, as evidenced by changes in expression of genes HPG axis, as well as hepatic vitellogenin concentration. Furthermore, our findings reveal that exposure to this contaminant may compromise the reproductive success of the species, as it affected sperm quality parameters.

Effects of curcumin to counteract levodopa-induced toxicity in zebrafish.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor dysfunction due to the death of dopaminergic neurons in the substantia nigra pars compacta. Currently, treatment of PD has focused on increasing dopamine levels, using a dopamine precursor, levodopa (L-DOPA) or stimulation of dopaminergic receptors. Prolonged use of L-DOPA is associated with the occurrence of motor complications and dyskinesia, attributed to neurotoxic effects of this drug. The aim of this study was to investigate the effects of curcumin (CUR), a lipophilic polyphenol, to counteract L-DOPA induced toxicity. Zebrafish larvae were pre-treated with CUR (0.05 µM) or vehicle dimethyl sulfoxide (DMSO) for 24 hr and subsequently exposed to L-DOPA (1 mM) or vehicle. Immediately and 24 hr after L-DOPA exposure, spontaneous swimming and dark/light behavioral tests were performed. In addition, levels of reactive oxygen species (ROS) and lipid peroxidation products were determined at the end of treatment. CUR significantly improved the motor impairment induced by 24 hr L-DOPA treatment, and reduced levels of ROS and lipoperoxidation products in zebrafish larvae. In conclusion, our results suggest that CUR acts as a neuroprotector against toxicity initiated by L-DOPA. Evidence suggests the observed effects of CUR are associated with its antioxidant properties.

Glyphosate is Harmful to Early Life Stages of the Viviparous Fish Jenynsia Multidentata: Biochemical and Locomotor Effects.

Glyphosate is the most widely used herbicide worldwide due to its efficacy in weed control in agriculture. This herbicide has been consistently detected in the aquatic environment, causing harmful consequences to nontarget organisms residing in agricultural regions. In this study, we assessed the effects of environmentally relevant concentrations of glyphosate (30-100 µg/L) on the early life stages of the viviparous fish Jenynsia multidentata through biochemical and locomotor endpoints. At 96 h of exposure, 30 and 65 µg/L glyphosate caused an increase in acetylcholinesterase (AChE) activity, and 65 µg/L glyphosate also augmented the levels of lipid peroxidation. Glyphosate at 100 µg/L did not alter the activity of acetylcholinesterase or the levels of lipid peroxidation, but it stimulated the activity of the cellular detoxification enzyme glutathione S-transferase. In addition, all concentrations affected the swimming of the fish. Under light conditions, glyphosate caused hypolocomotion at all concentrations tested, whereas under dark conditions, this was observed at 30 and 100 µg/L. Hyperlocomotion was observed at 65 µg/L glyphosate. These findings are alarming for the health of fish, such as J. multidentata that inhabit streams that pass through agricultural areas, especially for the early life stages of these fish. Research studying the effects of pollutants on native species is relevant to improve regulation that protects aquatic ecosystems.

Experimental models of chemically induced Parkinson's disease in zebrafish at the embryonic larval stage: a systematic review.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra that results in a decrease in dopamine levels, resulting in motor-type disturbances. Different vertebrate models, such as rodents and fish, have been used to study PD. In recent decades, Danio rerio (zebrafish) has emerged as a potential model for the investigation of neurodegenerative diseases due to its homology to the nervous system of humans. In this context, this systematic review aimed to identify publications that reported the utilization of neurotoxins as an experimental model of parkinsonism in zebrafish embryos and larvae. Ultimately, 56 articles were identified by searching three databases (PubMed, Web of Science, and Google Scholar). Seventeen studies using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 4 1-methyl-4-phenylpyridinium (MPP+), 24 6-hydroxydopamine (6-OHDA), 6 paraquat/diquat, 2 rotenone, and 6 articles using other types of unusual neurotoxins to induce PD were selected. Neurobehavioral function, such as motor activity, dopaminergic neuron markers, oxidative stress biomarkers, and other relevant parameters in the zebrafish embryo-larval model were examined. In summary, this review provides information to help researchers determine which chemical model is suitable to study experimental parkinsonism, according to the effects induced by neurotoxins in zebrafish embryos and larvae.

Glyphosate-based herbicide (GBH) causes damage in embryo-larval stages of zebrafish (Danio rerio).

Glyphosate-Based Herbicides (GBH) show risks to the environment and also to aquatic organisms, such as fish. The present work aimed to evaluate the effects of GBH and Pure Glyphosate (PG) exposure on Danio rerio embryos at drinking water concentrations. Zebrafish embryos were exposed to 250, 500, and 1000 µg L-1 of Roundup Original DI® and pure glyphosate for 96 h. Glyphosate concentration in water, parameters physicochemical water, survival, hatching rate, heart rate, malformations, behavior, and biomarkers were evaluated. We verified that at 6 h post-fertilization (hpf), animals exposed to GBH 500 showed decreased survival as compared to the control. The hatching rate increased in all groups exposed to GBH at 48 hpf as compared to the control group. The embryos exposed did not present changes in the spontaneous movement and touch response. Exposed groups to GBH demonstrated a higher number of malformations in fish embryos as compared to the control. Most malformations were: pericardial edema, yolk sac edema, body malformations, and curvature of the spine. In heart rate, bradycardia occurred in groups exposed, as predicted due to cardiac abnormalities. As biochemical endpoints, we observed a decrease in Glutathione S-transferase (GBH 250, GBH 500 and PG 250) and Acetylcholinesterase (GBH 250 and PG 250) activity. No differences were found between the groups in the concentration of protein, Total Antioxidant Capacity Against Peroxyl Radicals, Lipid peroxidation, Reactive Oxygen Species, Non-protein thiols, and Catalase. In conclusion, the damage in all evaluated stages of development was aggravated by survival and malformations. Therefore, the large-scale use of GBHs, coupled with the permissiveness of its presence could be the cause damage to the aquatic environment affecting the embryonic development of non-target organisms.

Toxicity evaluation of traditional and organic yerba mate (Ilex paraguariensis A. St.-Hil.) extracts.

Yerba mate (Ilex paraguariensis A. St.-Hil.) is an important source of biologically active compounds with pharmacological potential. The aim of this study was to examine the toxicity of different extracts obtained from either traditional or organic cultivated yerba mate in vitro and in vivo. Aqueous, ethanolic and methanolic extracts were obtained from commercial samples of yerba mate and total phenolic content was determined employing Folin-Ciocalteau reagent. The aqueous extracts presented higher content of total phenols, compared to ethanolic and methanolic extracts, and also demonstrated lower cytotoxicity, which is the basis for testing were carried out only using aqueous extracts. The main phenolic acids found in traditional aqueous (TA) extract were chlorogenic, gallic and protocatechuic acids. Gallic and hydroxybenzoic acids were detected in aqueous cultivated organic (OA) extract. Pretreatment with OA extract (100 µg/ml, 1 hr) was cytoprotective against rotenone-induced toxicity (1 µM). For in vivo toxicity assay, zebrafish embryos were exposed to OA or TA extracts (10-160 µg/ml) at 4 hr post fertilization. TA extract decreased embryos survival in a concentration-dependent manner, reduced the hatching rate at 40 µg/ml, increased edema frequency at 80 µg/ml and altered body curvature at 120 µg/ml. Further, TA extract produced locomotor disorders at concentrations equal to or greater than 10 µg/ml. In contrast, OA extract exhibited no apparent toxic effect on organogenesis and behavior up to 100 µg/ml. In summary, the OA cultivated extract showed the lowest cytotoxicity in vitro, enhanced reduction in rotenone-induced toxicity, and produced less toxicity in zebrafish embryos compared to the TA extract.

Effect of Illicium verum (Hook) essential oil on cholinesterase and locomotor activity of Alphitobius diaperinus (Panzer).

The aim of this work was to test the insecticidal effect of the essential oil of Illicium verum (Hook) by observing the survival, biochemical parameters (acetylcholinesterase (AChE) activity, glutathione s-transferase (GST) activity and the concentration of reactive oxygen species (ROS)) and locomotor capacity of the Coleoptera Alphitobius diaperinus (Panzer), a pest of beef poultry. The sublethal concentrations (100% survival of A. diaperinus during 96 h of exposure) of I. verum essential oil selected for analysis were 0.5% and 1%. The selected sublethal concentrations did not show significant increases in ROS levels after 24 h of exposure to the essential oil. However, increases in GST activity were seen following exposure to 0.5% I. verum essential oil, while decreases in AChE activity were observed following exposure to concentrations of 0.5% and 1%. These results correlate with the observed behavior of A. diaperinus; when placed into an arena, these insects typically demonstrate aversion to stimuli and refuge-seeking behavior. Following exposure to 0.5% I. verum essential oil, the insects showed loss of refuge-seeking capacity and, following exposure to a concentration of 1%, loss of locomotor capacity. Overall, these results indicate that I. verum essential oil can be used as an alternative to conventional insecticides.

Novelties from the herbaceous stratum in a key region for the conservation of the Southern Amazon / Novidades do estrato herbáceo em uma região chave para a conservação da Amazônia Meridional

Abstract The contribution of the herbaceous stratum to tropical plant diversity is considerable, however this component remains undersampled. We investigated floristic, structural, ecological and conservation issues concerning the herbaceous component of a seasonal deciduous forest associated with granitic rock outcrops in the Cristalino Region, a key area for biodiversity conservation in the Brazilian Amazon. We installed a permanent plot of 1 ha, allocating 10 transect-lines of 20 m each. We identified the sampled individuals, measured height and projection, and verified cover and frequency per species, genera and family. We recorded 86 species, 62 genera and 25 families, with Orchidaceae being the family with the highest species richness. Among the 26 new species added to Cristalino Flora, we included Philodendron deflexum Poepp. ex Schott and Griffinia nocturna Ravenna, the latter 'Critically Endangered'. Furthermore, the occurrence of G. nocturna in an Amazonian forest matrix is a novelty in this study. The estimate of species diversity according to Shannon-Wiener (H') was 2.43 nats.ind.-1 (equivalent to 11.37 ± 0.90 IC95% equally common species), and according to Simpson (1/D), 6.82 (± 0.648 IC95%). The rarefaction and extrapolation curves for the diversity estimates tended to stabilize. Although the vegetation on rock outcrops usually presents a high number of endemic species, this pattern was not found in our study area, which can be explained by its continuous occurrence in the forest matrix. The understory of our study area consists in a mixture of floras, being composed mainly of species from the Amazon and/or Cerrado biomes. In view of the current anthropic pressure faced by the southern Amazon, we reinforce the importance of carrying out inventories of its herbaceous communities, since the risk of species loss is even more alarming when considering present undersampling of this component.

Resumo A contribuição do estrato herbáceo para a diversidade de plantas tropicais é considerável, mas esse componente permanece subamostrado. Investigamos questões florísticas, estruturais, ecológicas e de conservação relacionadas ao componente herbáceo de uma floresta estacional decidual associada a afloramentos rochosos graníticos na região do Cristalino, que é uma área chave para a conservação da biodiversidade na Amazônia brasileira. Instalamos um plot permanente de 1 ha, alocando 10 linhas de 20 m cada. Identificamos os indivíduos amostrados, medimos altura e projeção e verificamos cobertura e frequência por espécie, gênero e família. Registramos 86 espécies, 62 gêneros e 25 famílias, sendo Orchidaceae a família com maior riqueza de espécies. Entre as 26 novas espécies adicionadas à Flora do Cristalino, incluímos Philodendron deflexum Poepp ex Schott e Griffinia nocturna Ravenna, esta última 'Criticamente Ameaçada'. Além disso, a ocorrência de G. nocturna em uma matriz florestal amazônica é uma novidade neste estudo. A estimativa da diversidade de espécies de acordo com Shannon-Wiener (H ') foi 2,43 nats / ind.-1 (equivalente a 11,37 ± 0,90 IC95% espécies igualmente comuns), e de acordo com Simpson (1/D), 6,82 (± 0,648 IC95%). As curvas de rarefação e extrapolação para as estimativas de diversidade tenderam à estabilização. Embora a vegetação associada a afloramentos rochosos em geral apresente um elevado número de espécies endêmicas, esse padrão não foi encontrado para a nossa área de estudo, o que pode ser explicado pela sua ocorrência contínua à matriz florestal. O sub-bosque da nossa área de estudo apresenta mistura de floras, sendo composto principalmente por espécies dos biomas Amazônia e/ou Cerrado. Diante das pressões antrópicas existentes no sul da Amazônia, reforçamos a importância da realização de inventários das comunidades herbáceas desse bioma, já que o risco de perda de espécies é ainda mais alarmante quando consideramos a subamostragem desse componente.

Evaluating the Role of Breathing Guidance on Game-Based Interventions for Relaxation Training.

Working in a fast-paced environment can lead to shallow breathing, which can exacerbate stress and anxiety. To address this issue, this study aimed to develop micro-interventions that can promote deep breathing in the presence of stressors. First, we examined two types of breathing guides to help individuals learn deep breathing: providing their breathing rate as a biofeedback signal, and providing a pacing signal to which they can synchronize their breathing. Second, we examined the extent to which these two breathing guides can be integrated into a casual game, to increase enjoyment and skill transfer. We used a 2 × 2 factorial design, with breathing guide (biofeedback vs. pacing) and gaming (game vs. no game) as independent factors. This led to four experimental groups: biofeedback alone, biofeedback integrated into a game, pacing alone, and pacing integrated into a game. In a first experiment, we evaluated the four experimental treatments in a laboratory setting, where 30 healthy participants completed a stressful task before and after performing one of the four treatments (or a control condition) while wearing a chest strap that measured their breathing rate. Two-way ANOVA of breathing rates, with treatment (5 groups) and time (pre-test, post-test) as independent factors shows a significant effect for time [F(4, 50) = 18.49, p < 0.001, η t i m e 2 = 0 . 27 ] and treatment [F(4, 50) = 2.54, p = 0.05, η2 = 0.17], but no interaction effects. Post-hoc t-tests between pre and post-test breathing rates shows statistical significance for the game with biofeedback group [t(5) = 5.94, p = 0.001, d = 2.68], but not for the other four groups, indicating that only game with biofeedback led to skill transfer at post-test. Further, two-way ANOVA of self-reported enjoyment scores on the four experimental treatments, with breathing guide and game as independent factors, found a main effect for game [ F ( 1 , 20 ) = 24 . 49 , p < 0 . 001 ,   η g a m e 2 = 0 . 55 ], indicating that the game-based interventions were more enjoyable than the non-game interventions. In a second experiment, conducted in an ambulatory setting, 36 healthy participants practiced one of the four experimental treatments as they saw fit over the course of a day. We found that the game-based interventions were practiced more often than the non-game interventions [t (34) = 1.99, p = 0.027, d = 0.67]. However, we also found that participants in the game-based interventions could only achieve deep breathing 50% of the times, whereas participants in the non-game groups succeeded 85% of the times, which indicated that the former need adequate training time to be effective. Finally, participant feedback indicated that the non-game interventions were better at promoting in-the-moment relaxation, whereas the game-based interventions were more successful at promoting deep breathing during stressful tasks.

Ethanol modulates the effector functions of human monocyte-derived macrophages in response to Paracoccidioides brasiliensis yeast cells.

We aimed to investigate the effects of ethanol and its metabolites (ß-hydroxybutyrate and sodium acetate) in the effector functions of macrophages in response to Paracoccidioides brasiliensis yeast cells and to determine their influence in the development of the adaptive response. Purified peripheral blood monocytes were differentiated into macrophages and were treated with ethanol, ß-hydroxybutyrate, and sodium acetate, and stimulated with P. brasiliensis yeast cells and evaluated for their phenotypic characteristics, functional activity, and capability to induce T cells activation/differentiation. We found that the ethanol treatment diminished the expression of HLA-AB, HLA-DR, CD80, and CD86, modulating the expression of dectin-1, as well as Syk phosphorylation. The ethanol treatment increased the phagocytic activity, expression of CD206, and IL-10 production; however, reduced ROS production, fungicidal activity, caspase-1 cleavage, and IL-1ß and IL-6 production. Our data also showed that the presence of ethanol reduced the differentiation of Th1 and Th17 cells and increased the frequency of Th2 cells. Our results indicated that ethanol exposure could suppress effector function of macrophages, possibly leading to the polarization of M2 macrophages. The ethanol modulates the expression of costimulatory and antigen-presentation molecules and interferes with the NLRP3 inflammasome. Altogether, these alterations affect the development of the adaptive response, decreasing the frequency of IL-17, IL-22, and IFN- γ producing cells, and increasing the frequency of IL-4 producing cells. Therefore, exposure to ethanol can impair the capability of macrophages to exert their effector functions and activate the acquired response related to resistance to P. brasiliensis infection.

Behavioral changes occur earlier than redox alterations in developing zebrafish exposed to Mancozeb.

As agriculture expands to provide food and wellbeing to the world's growing population, there is a simultaneous increasing concern about the use of agrochemicals, which can harm non-target organisms, mainly in the aquatic environment. The fungicide Mancozeb (MZ) has been used on a large-scale and is a potent inducer of oxidative stress. Therefore, there is an urgent need for the development of more sensitive biomarkers designed to earlier biomonitoring of this compound. Here we tested the hypothesis that behavioral changes induced by sublethal MZ concentrations would occur first as compared to biochemical oxidative stress markers. Embryos at 4 h post-fertilization (hpf) were exposed to Mancozeb at 5, 10 and 20 µg/L. Controls were kept in embryo water only. Behavioral and biochemical parameters were evaluated at 24, 28, 72, and 168 hpf after MZ exposure. The results showed that MZ significantly altered spontaneous movement, escape responses, swimming capacity, and exploratory behavior at all exposure times. However, changes in ROS steady-stead levels and the activity of antioxidant enzymes were observable only at 72 and 168 hpf. In conclusion, behavioral changes occurred earlier than biochemical alterations in zebrafish embryos exposed to MZ, highlighting the potential of behavioral biomarkers as sensitive tools for biomonitoring programs.

Resveratrol Derivatives as Potential Treatments for Alzheimer's and Parkinson's Disease.

Neurodegenerative diseases are characterized by the progressive loss of neurons in different regions of the nervous system. Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most prevalent neurodegenerative diseases, and the symptoms associated with these pathologies are closely related to the regions that are most affected by the process of neurodegeneration. Despite their high prevalence, currently, there is no cure or disease-modifying drugs for the treatment of these conditions. In the last decades, due to the need for the development of new treatments for neurodegenerative diseases, several authors have investigated the neuroprotective actions of naturally occurring molecules, such as resveratrol. Resveratrol is a stilbene found in several plants, including grapes, blueberries, raspberries, and peanuts. Studies have shown that resveratrol presents neuroprotective actions in experimental models of AD and PD, however, its clinical application is limited due to its rapid metabolism and low bioavailability. In this context, studies have proposed that structural changes in the resveratrol molecule, including glycosylation, alkylation, halogenation, hydroxylation, methylation, and prenylation could lead to the development of derivatives with enhanced bioavailability and pharmacological activity. Therefore, this review article aims to discuss how resveratrol derivatives could represent viable molecules in the search for new drugs for the treatment of AD and PD.

Woody vegetation associated with rocky outcrops in Southern Amazonia: a starting point to unveil a unique flora / Vegetação lenhosa associada a afloramentos rochosos na Amazônia Meridional: um marco inicial que revela uma flora única

Abstract: Vegetation associated with rocky outcrops is responsible for increasing floristic and landscape diversity, since its flora can be different from the adjacent landscape. Our objective was to characterize the woody vegetation associated with the rocky outcrop of the RPPN Mirante da Serra, Cristalino region, Mato Grosso State, Brazil. In a Deciduous Seasonal Forest associated with granite outcrops, we demarcated a plot of 1ha. We performed collections on this plot, installed for conducting monitoring studies, and also random collections on trails near the plot to better represent the outcrop flora. We totaled 126 species, 95 genera and 39 families. Overall, 18 species were increased to the Flora of Cristalino - with seven new records to the flora of Mato Grosso and four new records to the Amazon Domain. We found two threatened and 17 Brazilian endemic species. The rocky outcrop present in the RPPN Mirante da Serra is an important conservation area for a continuous execution of floristic studies in a manner to enable a monitoring program of the area, considering the new occurrence records and also because it contains threatened species.

Resumo: A vegetação que se associa a afloramentos rochosos é responsável por incrementar a diversidade florística e de paisagens, uma vez que a flora pode ser distinta da paisagem circundante. Nosso objetivo foi caracterizar a vegetação lenhosa sobre o afloramento rochoso da RPPN Mirante da Serra, região do Cristalino, estado de Mato Grosso, Brasil. Em uma Floresta Estacional Decidual associada a afloramento granítico, demarcamos uma parcela de 1 ha. Realizamos coletas nesse plot, instalado para a realização de estudos de monitoramento e, ainda, coletas aleatórias em trilhas próximas da parcela para melhor representar a flora do afloramento. A amostragem resultou em um total de 126 espécies, 95 gêneros e 39 famílias. Ao todo, 18 espécies foram incrementadas à Flora do Cristalino, das quais sete são novos registros à flora do estado de Mato Grosso e quatro ao Domínio da Amazônia. Encontramos duas espécies ameaçadas e 17 endêmicas do Brasil. O afloramento rochoso presente na RPPN Mirante da Serra é uma importante área de conservação para uma contínua realização de estudos florísticos de modo a possibilitar um programa de monitoramento da área, considerando os novos registros de ocorrência e, também, por conter espécies ameaçadas.

Acute Exposure to Permethrin Modulates Behavioral Functions, Redox, and Bioenergetics Parameters and Induces DNA Damage and Cell Death in Larval Zebrafish.

Permethrin (PM) is a synthetic pyrethroid insecticide widely used as domestic repellent. Damage effects to nontarget organisms have been reported, particularly in the early stages of development. Studies indicate redox unbalance as secondary PM effect. Therefore, our goal was to investigate the acute PM effects on larval zebrafish. Larvae (6 days postfertilization) were exposed to PM (25-600 µg/L) during 24 hours, and 50% lethal concentration was estimated. For subsequent assays, the sublethal PM concentrations of 25 and 50 µg/L were used. PM increased anxiety-like behaviors according to the Novel Tank and Light-Dark tests. At the molecular level, PM induced increased ROS, which may be related to the increased lipid peroxidation, DNA damage, and apoptosis detected in PM-exposed organisms. In parallel, upregulation of the antioxidant system was detected after PM exposure, with increased superoxide dismutase, glutathione S-transferase and glutathione reductase activities, and thiol levels. The increased of Nrf2 target genes and the activation of an electrophile response element-driven reporter Tg(EPRE:LUC-EGFP) suggest that the Nrf2 pathway can mediate a fast response to PM, leading to antioxidant amplification. By using high-resolution respirometry, we found that exposure to PM decreased the oxygen consumption in all respiratory stages, disrupting the oxidative phosphorylation and inhibiting the electron transfer system, leading to decrease in bioenergetics capacity. In addition, PM led to increases of residual oxygen consumption and changes in substrate control ratio. Glucose metabolism seems to be affected by PM, with increased lactate dehydrogenase and decreased citrate synthase activities. Taken together, our results demonstrated the adverse effects of acute sublethal PM concentrations during larval development in zebrafish, causing apparent mitochondrial dysfunction, indicating a potential mechanism to redox unbalance and oxidative stress, which may be linked to the detected cell death and alterations in normal behavior patterns caused by acute PM exposure.

Stress and productivity patterns of interrupted, synergistic, and antagonistic office activities.

We describe a controlled experiment, aiming to study productivity and stress effects of email interruptions and activity interactions in the modern office. The measurement set includes multimodal data for n = 63 knowledge workers who volunteered for this experiment and were randomly assigned into four groups: (G1/G2) Batch email interruptions with/without exogenous stress. (G3/G4) Continual email interruptions with/without exogenous stress. To provide context, the experiment's email treatments were surrounded by typical office tasks. The captured variables include physiological indicators of stress, measures of report writing quality and keystroke dynamics, as well as psychometric scores and biographic information detailing participants' profiles. Investigations powered by this dataset are expected to lead to personalized recommendations for handling email interruptions and a deeper understanding of synergistic and antagonistic office activities. Given the centrality of email in the modern office, and the importance of office work to people's lives and the economy, the present data have a valuable role to play.

N-acetylcysteine inhibits Mancozeb-induced impairments to the normal development of zebrafish embryos.

Mancozeb (MZ), a manganese/zinc-containing ethylene-bis-dithiocarbamate (EBCD) fungicide has been claimed to present low acute toxicity and short environmental persistence, however, its effects on embryogenesis in non-target organisms is unclear. Here, we used zebrafish embryos (5 hpf) to assess the potential embryotoxic effects induced by MZ (up to 72 hpf) as well as the role of reactive oxygen species (ROS) in this process by pre-treatment with a classical antioxidant (N-acetylcysteine, NAC). Markers of reactive oxygen species production (ROS), glutathione (GSH) levels and glutathione S-transferase (GST) activity were measured along with genotoxicity (comet assay), cell death (Acridine Orange) and behavioral parameters (spontaneous movement, touch stimulation and swimming response), in order to determine potential mechanisms of embryotoxicity. According to results, MZ was able to induce morphological abnormalities such as body axis distortion, DNA damage, cell death, increased ROS generation and changes in behavioral endpoints during zebrafish development. All these toxic effects were inhibited by the pre-treatment with NAC indicating a key role of redox unbalance during MZ-induced embryotoxicity. At least in our knowledge, this is the first report on the deleterious effect of MZ to the normal embryogenesis of zebrafish. In addition, the importance of ROS generation during this pathophysiological condition was highlighted.

Mancozeb exposure results in manganese accumulation and Nrf2-related antioxidant responses in the brain of common carp Cyprinus carpio.

Manganese (Mn)-containing dithiocarbamates such as Mancozeb (MZ) have been shown to induce oxidative stress-related toxicity in rodents and humans. However, little is known about the neurotoxic effects induced by MZ in fish. In this study, carp (Cyprinus carpio) were exposed to non-lethal waterborne concentrations of MZ, and oxidative stress parameters as well as metal accumulation in fish brains were evaluated. The experimental groups were as follows: control, MZ 5 mg/L, and MZ 10 mg/L. Fish were exposed for 7 days, and then brain was removed and prepared for subsequent analysis of antioxidant enzymes, reactive oxygen species (ROS), and expression of Nrf2 and phosphoNrf2. In parallel, manganese (Mn) levels were evaluated in blood and brain tissues. Mn levels were significantly increased in blood and brain of MZ-exposed carps. In addition, a concentration-dependent increase (p < 0.05) in ROS levels was observed in parallel to increments (p < 0.05) in the activity of major antioxidant enzymes, such as GPx, GR, and GST. On the other hand, significant decreases (p < 0.05) in CAT and SOD activities were observed. The expression of total and phosphorylated forms of Nrf2 was significantly (p < 0.05) upregulated in the brain of carps exposed to Mz when compared to the control, indicating an activation of the Nrf2 antioxidant pathway. Our study showed for the first time the activation of the Nrf2/ARE pathway and bioaccumulation of Mn induced by MZ exposure in fish species, highlighting important mechanisms of action and its toxicological impacts to aquatic organisms.