In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a ...light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis.
The food consumption of adolescents has changed nowadays, with an increase in ultra-processed food that in general shows higher calories and lower nutrients. Because of this, the objective of this ...study was to investigate the impacts of a 12-week multi-professional family versus isolated intervention on the food level processing of overweight adolescents. A randomized clinical trial study was carried out in which adolescents (
43; mean aged 13.73 years) who were divided into FG-family group (
21; the adolescents performed the activities with their parents) and IG-isolated group (
22; the adolescents performed the activities alone). The parameters measured before and after 12 weeks of multi-professional intervention (physical exercise, nutrition and psychoeducation) were: body mass, height and body mass index-BMI. The level of food processing was analyzed using a three-day food recall (24hR), classified according to the Food Guide for the Brazilian Population (fresh, minimally, processed and ultra-processed foods). The main results show that there was only a significant reduction in the consumption of processed foods (FG: 7.93%; IG: 49.73%) and ultra-processed foods (FG: 35.06%; IG: 67.16%) in grams (FG: 22.29%; IG: 65.23%) and calories (
0.05; for all comparisons). The consumption of fresh foods in grams (FG:61.97%; IG: 147.13%) and calories (FG: 147.13%; IG: 118.03%) and minimally processed foods (FG: 27.45%; IG: 14.64%) in grams increased significantly (
0.05; for all comparisons). However, no significant differences were observed between all variables analyzed for the groups, nor any interaction (
0.05). In conclusion, both groups who participated in the activities showed positive changes with increased consumption of fresh foods and reduced consumption of processed foods, without difference between them.
Native bees are vital pollinators in the Neotropical Region and can serve as bioindicators for maintaining floral diversity in natural environments. However, the use of pesticides, specifically ...neonicotinoids, in agroecosystems has led to a decline in these pollinating organisms. This study aimed to evaluate the topical (contaminated mist) and residual (contaminated food) acute effect of the insecticide imidacloprid (IMI) on a stingless bee species (native to Brazil) with wide geographical distribution (
Tetragonisca angustula
) and two species restricted to certain regions (
Tetragonisca fiebrigi
and
Tetragonisca weyrauchi
) to determine LC
10–48 h
and LC
50–48 h
. The bees were exposed to various concentrations of IMI, in both topical and residual effect tests, and the results showed that low concentrations of the insecticide adversely affected the survival of all three species, with
T. angustula
being the most sensitive. The study also compared the sensitivity of the three species to the standard insecticide Dimethoate, and the results confirmed that
T. angustula
was the most sensitive. The findings of this study provide crucial ecotoxicological information, particularly concerning the residual effects of neonicotinoids on stingless bees. This evidence reinforces the urgent need to expand research on the effects of neonicotinoids on these important pollinators, so commonly found in nature and meliponaries. In addition, this research contributes significantly to filling the existing knowledge gap about the effects of pesticides on bee species native to Brazil, bringing to light the potential risks that these chemicals pose to the survival of these pollinators and emphasizing the urgent need for efforts of conservation in favor of these precious pollinating agents.
Fipronil is a pyrazole insecticide used to control undesirable insect populations. Due to its large-scale application, there is the potential for surface waters’ contamination, with toxic action for ...non-target organisms, and consequent impacts on aquatic ecosystems. Planarians are potential non-target aquatic invertebrates to these insecticides. They are widespread in tropical freshwaters and have been proposed as good candidates to assess the toxic effects of freshwater systems contaminated by insecticides. Thus, the present study aims to evaluate the sublethal concentrations of a fipronil-based insecticide that may affect the planarian physiology. After chronic exposure to Regent 800 WG®, a significant decrease in locomotor velocity (LOEC—6.25 mg·L−1), regeneration of the auricles and photoreceptors (LOEC—3.13 mg·L−1), and reproduction (fecundity—LOEC 12.5 mg·L−1) were observed. The results of our study demonstrate that long-term exposure to a pyrazole insecticide can compromise non-target aquatic invertebrates while reinforcing the need for a better investigation of complementary parameters (such as behavior, regeneration, and reproduction) for a more accurate risk assessment of commercial pesticide toxicity in freshwater systems.
Anthracene derivatives are an interesting class of compounds and modifications in the anthracene ring, producing different compounds with different properties. Structural analysis of anthracene ...derivatives with modifications in position 9,10 of the aromatic ring is necessary in order to obtain information about its properties. The introduction of groups with polar substituents increases the possibility to modify the molecule lipophilicity, corroborating its use as bioimaging probes. Anthracene derivatives are used in many biochemical applications. These compounds can react with molecular singlet oxygen O2 (1Δg), a reactive oxygen species, through the Diels–Alder reaction 4 + 2 to form the respective endoperoxide and to be used as a chemical trap in biological systems. Thus, the structural and crystalline characterizations of two anthracene derivatives are presented in this work to obtain information about their physical-chemical properties. The compounds were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analyses and scanning electron microscopy. The molecular structures of the compounds were studied by the Density Functional Theory, M06-2X/6-311++G(d,p) level of theory in the gas phase. From the results obtained for the frontier molecular orbitals, HOMO and LUMO, and from the Molecular Electrostatic Potential map, it was possible to predict the chemical properties of both compounds. The supramolecular arrangements were also theoretically studied, whose molecules were kept fixed in their crystallographic positions, through the natural bonding orbitals analysis to check the stability of interactions and the quantum theory of atoms in molecules to verify the type of intermolecular interaction between their molecules, as well as how they occur.
Singlet molecular oxygen O(2)((1)Δ(g)) is a potent oxidant that can react with different biomolecules, including DNA, lipids and proteins. Many polycyclic aromatic hydrocarbons have been studied as ...O(2)((1)Δ(g)) chemical traps. Nevertheless, a suitable modification in the polycyclic aromatic ring must be made to increase the yield of O(2)((1)Δ(g)) chemical trapping. With this goal, an anthracene derivative, diethyl-3,3'-(9,10-anthracenediyl)bisacrylate (DADB), was obtained from the reaction of 9,10-dibromoanthracene and ethyl acrylate through the Heck coupling reaction. The coupling of ethyl acrylate with the anthracene ring produced a new lipophilic, esterified, fluorescent probe reactive toward O(2)((1)Δ(g)). This compound reacts with O(2)((1)Δ(g)) at a rate of k(r) = 1.69 × 10(6) M(-1) s(-1) forming a stable endoperoxide (DADBO(2)), which was characterized by UV-Vis, fluorescence, HPLC/MS and (1)H and (13)C NMR techniques. The photophysical, photochemical and thermostability features of DADB were also evaluated. Furthermore, this compound has the potential for great application in biological systems because it is easily synthetized in large amount and generates specific endoperoxide (DADBO(2)), which can be easily detected by HPLC tandem mass spectrometry (HPLC/MS/MS).
Fipronil is a pyrazole insecticide used to control undesirable insect populations. Due to its large-scale application, there is the potential for surface waters’ contamination, with toxic action for ...non-target organisms, and consequent impacts on aquatic ecosystems. Planarians are potential non-target aquatic invertebrates to these insecticides. They are widespread in tropical freshwaters and have been proposed as good candidates to assess the toxic effects of freshwater systems contaminated by insecticides. Thus, the present study aims to evaluate the sublethal concentrations of a fipronil-based insecticide that may affect the planarian physiology. After chronic exposure to Regent 800 WGsup.®, a significant decrease in locomotor velocity (LOEC—6.25 mg·Lsup.−1), regeneration of the auricles and photoreceptors (LOEC—3.13 mg·Lsup.−1), and reproduction (fecundity—LOEC 12.5 mg·Lsup.−1) were observed. The results of our study demonstrate that long-term exposure to a pyrazole insecticide can compromise non-target aquatic invertebrates while reinforcing the need for a better investigation of complementary parameters (such as behavior, regeneration, and reproduction) for a more accurate risk assessment of commercial pesticide toxicity in freshwater systems.
Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. ...We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG2000-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum.
This study analyzes the care provided to adolescents in crisis in a municipality in Greater Metropolitan Rio de Janeiro, Brazil. The article reports on a qualitative health study that used ...Therapeutic Itinerary and Life Narratives as the methodological resources. The principal theoretical reference was psychoanalyst René Kaës. Based on the adolescents' own verbal accounts, the study aimed to grasp the collective realities that could potentially shed light on the different types of logic and professional practices applied to care for adolescents in psychosocial crisis situations. The underlying assumption was that an approach to the dialectical nature of the crisis required maintaining a framework that would allow establishing a space for transition within which to develop the necessary conditions for disruptive and paradoxical elements to be elaborated. However, crisis care in the context studied here proved to be hampered by infrastructure issues, institutional rigidity, and fragmentation of activities, with little orientation towards inter-sector work.
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