Microbiota diversity of three Brazilian native fishes during ice and frozen storage.

This study aimed to assess the bacterial microbiota involved in the spoilage of pacu (Piaractus mesopotamics), patinga (female Piaractus mesopotamics x male Piaractus brachypomus), and tambacu (female Colossoma macropomum × male Piaractus mesopotamics) during ice and frozen storage. Changes in the microbiota of three fish species (N = 22) during storage were studied through 16S rRNA amplicon-based sequencing and correlated with volatile organic compounds (VOCs) and metabolites assessed by nuclear magnetic resonance (NMR). Storage conditions (time and temperature) affected the microbiota diversity in all fish samples. Fish microbiota comprised mainly of Pseudomonas sp., Brochothrix sp., Acinetobacter sp., Bacillus sp., Lactiplantibacillus sp., Kocuria sp., and Enterococcus sp. The relative abundance of Kocuria, P. fragi, L. plantarum, Enterococcus, and Acinetobacter was positively correlated with the metabolic pathways of ether lipid metabolism while B. thermosphacta and P. fragi were correlated with metabolic pathways involved in amino acid metabolism. P. fragi was the most prevalent spoilage bacteria in both storage conditions (ice and frozen), followed by B. thermosphacta. Moreover, the relative abundance of identified Bacillus strains in fish samples stored in ice was positively correlated with the production of VOCs (1-hexanol, nonanal, octenol, and 2-ethyl-1-hexanol) associated with off-flavors. 1H NMR analysis confirmed that amino acids, acetic acid, and ATP degradation products increase over (ice) storage, and therefore considered chemical spoilage index of fish fillets.

Effect of incorporation of calcium polyphosphate sub-microparticles in low-concentration bleaching gels on physical properties of dental enamel.

AIM: To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). METHODS: A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. RESULTS: The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). CONCLUSION: The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy.

Linking Intensive Care Unit functional scales to the International Classification of Functioning: proposal of a new assessment approach.

BACKGROUND: There are several tools to assess functional and physical status in critical ill patients. These tools can guide rehabilitation strategies in Intensive care units (ICU). However, they are not standardized, and this can compromise their applicability. The aim of the study is to identify common contents between International Classification of Functioning, Disability and Health (ICF) and Medical Research Council sum score (MRC-ss), Functional Status Score for the ICU (FSS-ICU), and Physical Function in ICU Test-scored (PFIT-s). As well as to propose a new assessment approach based on the ICF to ICU patients. METHODS: Pilot cross-sectional study. ICU in-patients, both genders, aged between 50 and 75 years were assessed with MRC-ss, FSS-ICU, PFIT-s and the linking rules used were proposed by Cieza et al. The inter-rater agreement for the linking process was performed using the Kappa coefficient. RESULTS: The ICF categories identified in the tools covered a total of 14 items. Common contents were identified in 13 of the 14 and two were related to body functions, six to body structures and five to activities and participation. The inter-rater agreement was considered substantial for the linking of MRC-ss (k = 0.665) and PFIT-s (k = 0.749) to the ICF, and almost perfect for the FSS-ICU (k = 0.832). CONCLUSIONS: This study synthesizes and categorizes commonly used tools and presents a new proposal based on the ICF to guide future studies. The proposed model combines the ICF with the contents of the most relevant instruments used in critical care.

Maintenance of enamel properties after bleaching with high-concentrated hydrogen-peroxide gel containing calcium polyphosphate sub-microparticles.

OBJECTIVE: To assessed the physical and chemical properties of human-enamel after treatment with an experimental bleaching gel containing 35%-hydrogen peroxide (HP) and calcium polyphosphate sub-microparticles (CaPP). MATERIALS AND METHODS: Enamel/dentin specimens (4 × 4 × 3 mm) were obtained (n = 120) and allocated to different groups: control (saliva only); experimental (HP35%); commercial (whiteness-HP-Maxx); CaPP0.5% (HP35% + CaPP0.5wt%); CaPP1.5% (HP35% + CaPP1.5wt%). Three sessions were performed. The specimens' color was assessed using a spectrophotometer and the color (ΔE/ΔE00) and bleaching index (ΔWID) determined. The surface roughness and microhardness were assessed with a roughness tester and Knoop indenter. Raman spectroscopy was performed to obtain the ratios between the areas under the 431, 580, and 1070 cm-1 and the 960 cm-1 bands (430:960, 580:960, 1070:960). Kruskal-Wallis and Dunn compared the color, Ra, and SMH data. The Raman data was analyzed with Kruskal-Wallis and Dunn (α = 5%). RESULTS: The ΔE, ΔE00, and ΔWID were similar among the bleached groups (p > 0.05). The roughness was not different between the groups (p > 0.05). After the 3rd session, CaPP0.5% had higher microhardness than the experimental (p < 0.05). The 1070:960 was higher in the experimental than in the CaPP1.5% and control (p < 0.05). CONCLUSIONS: In human enamel, CaPP did not alter the bleaching effectiveness or roughness, and additionally, CaPP-containing gels increased the microhardness and preserved the mineral content when compared to the experimental without CaPP. CLINICAL RELEVANCE: Experimental bleaching gels containing calcium polyphosphate sub-microparticles as a mineral source reduce the mineral content alteration and superficial microhardness reduction, known potential side effects of the in-office bleaching treatments.

Dental education profile in COVID-19 pandemic: A scoping review.

INTRODUCTION: This scoping review aimed to determine the frequency of different teaching methodologies, tools and platforms applied in dental education during the COVID-19 pandemic. MATERIALS AND METHODS: The search strategy was performed in six databases and grey literature. A total of 28 questionnaire-based studies were included, without language or time restriction, from 20 different countries. RESULTS: Six thousand five hundred sixty-five participants were assessed: 84% undergraduates, 9% of faculty members, 5% of postgraduate students/residents/trainees and 2% of dental schools/residency programs. The pooled eligible data for teaching methodologies were 62% of a combination of different methods (95% CI, 35.5% to 82.3%), 23% a combination of synchronous and asynchronous formats (95% CI, 8.2% to 50.2%) and 15% for only synchronous lectures (95% CI, 4.3% to 42.2%). The reported tools were laptops (40%), smartphones (40%), tablets (40%), desktops (20%), Blackboard (20%), Respondus Lockdown Browser (20%), eProctor (20%) and PowerPoint (20%). The most used platforms were Zoom (70.6%), Microsoft Teams (23.5%) and Cisco Webex (23.5%). A better time management (17.9%; 95% CI, 7.9% to 35.6%) and the possibility of revision with additional notes (14.3%; 95% CI, 5.7% to 31.5%) was the greatest advantages related to dental e-learning, while the increased levels of anxiety/stress/burnout/exhaustion (35.7%; 95% CI, 21% to 54.2%) and internet connection problems (35.7%; 95% CI, 21% to 54.2%) was the most cited disadvantages. CONCLUSION: This scoping review showed promising blended teaching methodologies, tools and platforms in the dental education profile. The evidence suggests that e-learning technologies can widely contribute to dental education during the COVID-19 pandemic. Therefore, this study makes a major contribution to research by assessing the impact of COVID restrictions on dental education and further studies are needed to identify how restrictions in dental practice will affect future professionals.

Synthesis, biological evaluation and molecular modeling studies of novel 1,2,3-triazole-linked menadione-furan derivatives as P2X7 inhibitors.

The P2X7 receptor (P2X7R) is an ion channel that promotes the passage of ions through the membrane through brief stimulation once activated by ATP, its endogenous opener. However, prolonged stimulation with ATP, which occurs in pathological processes, opens a nonselective pore in the plasma membrane, allowing the passage of large molecules and leading to cytokine release or even cell death. In this sense, the search for new inhibitors for this receptor has attracted a great deal of attention in recent years. Considering the booming of biomass upgrading reactions in recent years and the continued efforts to synthesize biologically active molecules containing the 1,2,3-triazole ring, in the present work, we aimed to investigate whether triazole-linked menadione-furan derivatives could present P2X7R inhibitory activity. The novel compounds were tested for their inhibitory activity on ATP-induced dye uptake in peritoneal macrophages. Some have shown promising results, having displayed IC50 values lower than that of the P2X7R inhibitor BBG. Molecular docking studies also indicated that the active compounds bind to an allosteric site on P2X7R, presenting potential P2X7R inhibition.

Care bundle for family interview for pediatric organ donation.

PURPOSE: to develop a care bundle for best practices in conducting the family interview for organ and tissue donation with the families of children and adolescents. DESIGN AND METHODS: methodological study, with a qualitative approach, developed in Brazil, in three stages: literature review, qualitative study with professionals and family members, and development of the care bundle. RESULTS: Nine studies were selected and 17 health professionals and nine family members were interviewed. With this data, the care bundle was developed in three categories: communication of death, emotional support and information about organ and tissue donation. The recommendations were evaluated by five external professionals and all of them assessed the bundle as having the highest possible quality. CONCLUSIONS: the care bundle was built following the stages of integrative literature review and interviews with professionals working in this scenario and family members who have already gone through a family interview for organ and tissue donation of children and adolescents. PRACTICE IMPLICATIONS: the use of this material is seen as an important resource to support the professional during the conduction of the family interview in a scenario as sensitive and challenging as the care to family members facing death and the decision of organ and tissue donation of children and adolescents. Furthermore, the care bundle can increase the quality of family interviews and impact the reduction of family refusals. DESCRIPTORS: Practice Guideline as Topic. Tissue and Organ Procurement. Patient Care Team. Nursing. Pediatrics. Communication.

Development of a nanotechnological hydrogel containing desonide nanocapsules in association with acai oil: design and in vivo evaluation.

Nanotechnological products have been used as strategies to optimize the therapy and minimize the side effects of topical corticoids. The objective of this study was to develop hydrogels by the addition of sclerotium gum to the suspensions of desonide-loaded açai oil-based nanocapsules and to study their biological effect using an animal model of acute skin inflammation. The hydrogels presented a pH compatible with topical application (4.4 to 5.0), nanometric mean diameter (131 to 165 nm), pseudoplastic behavior, and stability under room conditions during 30 days. The in vitro skin permeation/penetration study demonstrated that a higher amount of desonide (p < 0.05) was retained in the epidermis from the nanotechnological-hydrogels (0.33 to 0.36 µg.cm2) in comparison to the commercial gel cream (0.16 µg.cm2). In the dermis, the nanostructured hydrogels promoted a lower DES retention compared to the non-nanostructured formulations (p < 0.05). This result may indicate a smaller amount of drug reaching the bloodstream and, thus, fewer side effects can be expected. Concerning the anti-inflammatory effect, the developed hydrogels reduced both ear edema and inflammatory cell infiltration, showing an effect comparable to the commercially available formulation, which presents twice the drug concentration. The hydrogels developed may be considered a promising approach to treat dermatological disorders.

A randomized clinical trial to evaluate the efficacy and safety of rivaroxaban in patients with bioprosthetic mitral valve and atrial fibrillation or flutter: Rationale and design of the RIVER trial.

The efficacy and safety of rivaroxaban in patients with bioprosthetic mitral valves and atrial fibrillation or flutter remain uncertain. DESIGN: RIVER was an academic-led, multicenter, open-label, randomized, non-inferiority trial with blinded outcome adjudication that enrolled 1005 patients from 49 sites in Brazil. Patients with a bioprosthetic mitral valve and atrial fibrillation or flutter were randomly assigned (1:1) to rivaroxaban 20 mg once daily (15 mg in those with creatinine clearance <50 mL/min) or dose-adjusted warfarin (target international normalized ratio 2.0-30.); the follow-up period was 12 months. The primary outcome was a composite of all-cause mortality, stroke, transient ischemic attack, major bleeding, valve thrombosis, systemic embolism, or hospitalization for heart failure. Secondary outcomes included individual components of the primary composite outcome, bleeding events, and venous thromboembolism. SUMMARY: RIVER represents the largest trial specifically designed to assess the efficacy and safety of a direct oral anticoagulant in patients with bioprosthetic mitral valves and atrial fibrillation or flutter. The results of this trial can inform clinical practice and international guidelines.

Spasticity distribution and severity in individuals with HTLV-1-associated myelopathy/tropical spastic paraparesis.

In individuals with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), spasticity is one of the main symptoms. The neurological signs of the disease are well defined, but details of how spasticity appears in these individuals have not been well explored. To describe spasticity location and severity of HAM/TSP individuals. Cross-sectional study with individuals older than 18 years, diagnosed with HAM/TSP and with lower limb spasticity. Pregnant women, individuals with other associated neurological diseases, and those using antispastic drugs were not included. Spasticity was assessed by the Modified Ashworth Scale (MAS), applied to the abductor, adductor, flexor, and extensor muscles of the hips, flexors, and extensors of the knees, dorsiflexors, plantiflexors, evertors, and inverters of the foot. Thirty participants were included. The plantiflexor muscles (90%), knee extensors (80%), knee flexors (63,3%), and adductors (50%) were most frequently affected by spasticity. Twenty-three (76.7%) individuals had mixed spasticity, 5 (16.7%) with distal spasticity and 2 (6.7%) with proximal spasticity. MAS was similar between the lower limbs in at least 6 of the 10 muscle groups of each individual. Spasticity was mostly mixed in the lower limbs, with more frequently mild severity. The individuals were partially symmetrical between the lower limbs. The most affected muscle groups were the plantiflexors, knee extensors and flexors and the hip adductors, consecutively, being predominantly symmetrical.

Twenty-year follow-up of the facial phenotype of Brazilian patients with Sotos syndrome.

Sotos syndrome is characterized by overgrowth starting before birth through childhood with intellectual disability and craniofacial anomalies. The majority of patients are large for gestational age with developmental delay or intellectual disability. The majority of cases are caused by pathogenic variants in NSD1. The most consistent physical features in this disorder are facial dysmorphisms including prominent forehead, downslanted palpebral fissures, prognathism with a pointed chin, and a long and narrow face. We present a follow-up to a cohort of 11 individuals found to harbor heterozygous, pathogenic, or likely pathogenic variants in NSD1. We analyzed the facial dysmorphisms and the condition using retrospective over 20 years. Among these patients, followed in our medical genetics outpatient clinic for variable periods of time, all had a phenotype compatible with the characteristic Sotos syndrome facial features, which evolved with time and became superimposed with natural aging modifications. We present here a long-term follow-up of facial features of Brazilian patients with molecularly confirmed Sotos syndrome. In this largest Brazilian cohort of molecularly confirmed patients with Sotos syndrome to date, we provide a careful description of the facial phenotype, which becomes less pronounced with aging and possibly more difficult to recognize in adults. These results may have broad clinical implications for diagnosis and add to the global clinical delineation of this condition.

Effect of storage temperature, water activity, oxygen headspace concentration and pasteurization intensity on the time to growth of Aspergillus fischerianus (teleomorph Neosartorya fischeri).

This study aims to assess, by means of a full factorial design, the effect of storage temperature (10-30 °C), water activity (aw, 0.87-0.89), headspace oxygen (O2) level (0.15-0.80%) and pasteurization intensity (95 °C-105 °C/15sec) on the time to visible growth (tv, days) of Aspergillus fischerianus on acidified Potato Dextrose Agar (aPDA, pH 3.6) for up to 90 days. Moreover, in order to validate the results obtained on aPDA, 12 conditions were selected and assessed in concentrate strawberry-puree based medium. Overall, storage temperature had the greatest effect on the tv of A. fischerianus on the evaluated conditions. At 10 °C, no visible growth was observed over the 90 day incubation period, whilst visible mycelia (diameter ≥ 2 mm) were present in 37% and 89% of the conditions at 22 °C and 30 °C, respectively. Pasteurization intensity had only a minor effect on the outgrowth of A. fischerianus. Growth inhibition was observed when aw was reduced to 0.870 ± 0.005 in combination with very low headspace O2 levels (0.15% ± 0.10) in both, aPDA and concentrate strawberry-based media, regardless of the incubation temperature and heat pasteurization intensity. Overall, longer tv's were required when incubation was done at 22 °C compared to 30 °C. Ultimately, the effect of O2 (0.05 and 1%) and pasteurization intensity (95 °C and 105 °C/15sec) were evaluated on totally 22 fruit purees (un-concentrates and concentrates) over a 60 day storage period. None of the concentrates purees (aw ≤0.860) evaluated in this study supported the growth of A. fischerianus. On the other hand, A. fischerianus growth inhibition was only observed when the O2 levels were ≤0.05% on un-concentrates fruit purees (aw ≥ 0.980) stored at ambient temperature (22 °C). Combination of multiple stress factors effectively inhibited growth of A. fischerianus. In general, storage of fruit purees at low temperatures (<10 °C) or distribution in the form of concentrates can be considered as important strategies to prevent the growth of spoilage associated heat-resistant moulds.

Diabetes mellitus and poor glycemic control increase the occurrence of coronal and root caries: a systematic review and meta-analysis.

OBJECTIVES: To assess the occurrence of coronal and root caries in adults with diabetes mellitus (DM). MATERIALS AND METHODS: This study was performed accordingly to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. A search strategy was adapted for six databases, as well as gray literature. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal tools for observational studies. Revman 5.3 was used to conduct five meta-analyses. The quality of evidence of meta-analysis was evaluated by GRADE. RESULTS: From 4047 titles retrieved, 29 studies were included in qualitative synthesis and 20 in quantitative synthesis. Findings showed a higher mean of DMFT in DM individuals compared with healthy controls (mean difference = 1.71; 95% CI 1.08-2.33; p < 0.01; I2 = 55%). Individuals with type 2 DM were three times more likely to have root caries in comparison with non-DM individuals (OR = 3.17; 95% CI 1.19-8.49; p = 0.02; I2 = 70%). Individuals with uncontrolled glycemic levels within the population with DM had higher prevalence of caries than individuals with controlled DM (OR = 3.82; 95% CI 1.12-13.07; p < 0.01; I2 = 89%; DMFT index mean difference = 2.61; 95% CI 1.14-4.08; p < 0.01; I2 = 75%). CONCLUSIONS: Diabetes mellitus may increase the occurrence of coronal and root caries in adults. Poor glycemic control turned diabetic individuals more likely to have caries. CLINICAL RELEVANCE: Dental caries can be an oral sign to indicate poor glycemic control in individuals with DM. Strategies to prevent root caries should be adopted in individuals with type 2 DM. Besides, dental and medical treatments should synergistically explore whether dietary habits are healthy for controlling both, DM and caries.

Laser therapy for recurrent aphthous stomatitis: an overview.

OBJECTIVES: To evaluate therapeutic effects of laser therapy on patients with recurrent aphthous stomatitis assessing evidences from previously published systematic reviews. MATERIALS AND METHODS: An overview of systematic reviews was conducted based on PRISMA checklist. Search strategies were developed and adapted for six different electronic databases and a gray literature search was also performed. The methodology quality of the included systematic reviews was assessed by the Measurement Tool to Assess the Methodological Quality of Systematic Reviews 2 (AMSTAR 2). RESULTS: After a two-step selection, five systematic reviews were included. Methodology quality was considered as a high risk of bias in two systematic reviews, while in the other three were graded as moderate. The systematic reviews' conclusions demonstrated that all included systematics reviews showed positive effects of laser therapy for pain relief, and most of them demonstrated healing improvement. A meta-analysis was not feasible due to heterogeneity in treatments parameters. CONCLUSIONS: Evidence suggested that laser therapy is an effective tool to treat recurrent aphthous stomatitis; nevertheless, more randomized clinical trials should be conducted to compare different lasers parameters. CLINICAL RELEVANCE: The present overview evaluated recent evidence about laser therapy for recurrent aphthous stomatitis management in order to contribute for evidence-based dentistry and decision-making. This overview suggests that laser therapy is a safe and promising alternative to treat recurrent aphthous stomatitis, since it promotes wound healing and pain relief.

Proteomic profile of saliva collected directly from ducts: a systematic review.

OBJECTIVE: To present a systematic review that provides updated information about proteins found in salivary fluid extracted strictly from ducts. METHODS: The systematic review probing strategy was based on electronic databases word search (PubMed, EMBASE, LILACS, Web of Science, and Scopus). Risk of bias was assessed based on Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data. RESULTS: After 2 rounds of scrutiny, 12 articles were included, totaling 231 individuals (125 were healthy, 41 were elder individuals with radicular caries, 56 had primary Sjögren's syndrome, and 9 were patients who had received radiotherapy for head and neck cancer). The selected studies had no similarities among proteins found, demonstrating the need of standard reference in experimental methodology to obtain a thorough coverage of proteins. CONCLUSION: Further studies are required to better determine the relative amount of proteins described in this study. It is essential to increase the number of samples, to perform similar collection techniques, to include other analyses methods such as mass spectrometry, and to perform the validation of some proteins using immunoassay techniques such as Elisa and Western blot. CLINICAL RELEVANCE: Proteomic profile of saliva collected from ducts is essential to better understand the disease process, enabling the identification of biomarkers for specific clinical situations.

Quantum Chemical-Guided Steglich Rearrangement of Azlactones and Isoxazolones.

The theoretical-guided evaluation of the Steglich rearrangement of azlactones and isoxazolones allowed the determination of the reactivity patterns in these heterocycles, including the factors that drive the regioselectivity toward both possible sites. These results allowed the first experimental report on the regioselective Steglich rearrangement of isoxazolones, affording the nitrogen- or carbon-acyloxy adducts.

Premenstrual Syndrome, Inflammatory Status, and Mood States in Soccer Players.

OBJECTIVE: To evaluate the relationship between the inflammatory profile and mood states in the different phases of the menstrual cycle in soccer players with and without premenstrual syndrome (PMS). METHODS: Data on the menstrual cycle and mood states were collected using the Daily Symptom Report and the Brunel Mood Scale. Cytokine and stress hormone concentrations were measured in urine by flow cytometry before and after a game in the luteal phase and in the follicular phase of one menstrual cycle. RESULTS: In all, 59.6% of the athletes had PMS. The PMS group showed higher concentrations of interleukin (IL)-1ß, IL-6, and IL-8 than the athletes without PMS. After the game, IL-6 decreased in the follicular phase and the luteal phase. The tumor necrosis factor-α levels were higher in the group without PMS during the post-game follicular phase than before the game. In the PMS group, tension was higher in the follicular phase before the game and depression was higher in the pre-game luteal phase than in the group without PMS. The PMS group also presented a negative correlation between depression and IL-10 levels in the pre-game follicular phase. Finally, in the pre-game luteal phase were found positive correlations between growth hormone and IL-10. CONCLUSION: PMS influences the inflammatory condition related to mood states and stress hormones in female soccer players.

Structural evidence for a fatty acid-independent myotoxic mechanism for a phospholipase A2-like toxin.

The myotoxic mechanism for PLA2-like toxins has been proposed recently to be initiated by an allosteric change induced by a fatty acid binding to the protein, leading to the alignment of the membrane docking site (MDoS) and membrane disrupting site (MDiS). Previous structural studies performed by us demonstrated that MjTX-II, a PLA2-like toxin isolated from Bothrops moojeni, presents a different mode of ligand-interaction caused by natural amino acid substitutions and an insertion. Herein, we present four crystal structures of MjTX-II, in its apo state and complexed with fatty acids of different lengths. Analyses of these structures revealed slightly different oligomeric conformations but with both MDoSs in an arrangement that resembles an active-state PLA2-like structure. To explore the structural transitions between apo protein and fatty-acid complexes, we performed Normal Mode Molecular Dynamics simulations, revealing that oligomeric conformations of MjTX-II/fatty acid complexes may be reached in solution by the apo structure. Similar simulations with typical PLA2-like structures demonstrated that this transition is not possible without the presence of fatty acids. Thus, we hypothesize that MjTX-II does not require fatty acids to be active, although these ligands may eventually help in its stabilization by the formation of hydrogen bonds. Therefore, these results complement previous findings for MjTX-II and help us understand its particular ligand-binding properties and, more importantly, its particular mechanism of action, with a possible impact on the design of structure-based inhibitors for PLA2-like toxins in general.

Cold-adapted enzymes produced by fungi from terrestrial and marine Antarctic environments.

Antarctica is the coldest, windiest, and driest continent on Earth. In this sense, microorganisms that inhabit Antarctica environments have to be adapted to harsh conditions. Fungal strains affiliated with Ascomycota and Basidiomycota phyla have been recovered from terrestrial and marine Antarctic samples. They have been used for the bioprospecting of molecules, such as enzymes. Many reports have shown that these microorganisms produce cold-adapted enzymes at low or mild temperatures, including hydrolases (e.g. α-amylase, cellulase, chitinase, glucosidase, invertase, lipase, pectinase, phytase, protease, subtilase, tannase, and xylanase) and oxidoreductases (laccase and superoxide dismutase). Most of these enzymes are extracellular and their production in the laboratory has been carried out mainly under submerged culture conditions. Several studies showed that the cold-adapted enzymes exhibit a wide range in optimal pH (1.0-9.0) and temperature (10.0-70.0 °C). A myriad of methods have been applied for cold-adapted enzyme purification, resulting in purification factors and yields ranging from 1.70 to 1568.00-fold and 0.60 to 86.20%, respectively. Additionally, some fungal cold-adapted enzymes have been cloned and expressed in host organisms. Considering the enzyme-producing ability of microorganisms and the properties of cold-adapted enzymes, fungi recovered from Antarctic environments could be a prolific genetic resource for biotechnological processes (industrial and environmental) carried out at low or mild temperatures.