What is the accuracy of the surgical guide in the planning of orthognathic surgeries? A systematic review.

BACKGROUND: To investigate the true accuracy of the surgical guide in the planning of orthognathic surgeries, which are performed worldwide. MATERIAL AND METHODS: A systematic search was conducted in the PubMed database, Web of science, Scopus and Embase, covering August 2020 to January 2021. Studies that included patients with dentofacial deformity including anteroposterior, vertical and asymmetry problems who were undergoing an orthognathic surgery procedure were included; QUADAS-2 was used to determine the risk of bias by analyzing the quality of the studies. A PRISMA (flowchart) was created to show the study selection, keywords, nomination processes, and inclusion and exclusion criteria. RESULTS: Eleven studies were selected for qualitative and quantitative synthesis. All studies evaluated described high precision of the surgical guide, where the lowest error values were represented by the CAD/CAM technique. CONCLUSIONS: The planning and printing errors related to the guide were all less than 2 mm, and the absolute averages of the errors related to virtual planning in the analysis of the different plans were less than 1 mm. Finally, the measurement of the ANB angle obtained equivalent results between the virtual planning and the traditional.

Probing stress relaxation behavior in glassy methacrylate networks containing thio-carbamate additives.

The incorporation of thiourethane prepolymer (TU) into either the organic phase or as a surface treatment for filler particles in composites reduces polymerization stress and improves fracture toughness. The aim of this study was to gain insight into the influence of the inclusion of thiourethanes on the resulting network of methacrylate-based materials polymerized via free-radical mechanisms. Dynamic mechanical analysis was used to elucidate network parameters and potential stress relaxation behavior of these networks. TU oligomers were synthesized using a combination of trimethylol-tris-3-mercaptopropionate and dicyclohexylmethane 4,4'-diisocyanate and added into composite formulations at 20 wt% replacing part of the organic matrix and/or as TU-silanes used to functionalize filler particles (TU-matrix, TU-Sil or TU-matrix/sil). Materials not containing any form of TU were used as the control (in those cases, 3-(trimethoxysilyl)propyl methacrylate was used as the silane agent). Filler was added at 50 wt%. Degree of conversion was evaluated by near-IR spectroscopy, mechanical properties by 3-point bending and rotational rheometry. Dynamic mechanical analysis was used to obtain network parameters (glass transition temperature (Tg), storage modulus, cross-link density, and breadth of tan delta a proxy for network homogeneity - temperature sweep experiments) and to evaluate the potential for network relaxation (stress relaxation). TU-containing formulations showed 10% higher DC than the control. The time to reach storage/loss modulus crossover in the rheometer experiments was significantly longer for TU-matrix and TU-matrix/sil in comparison with the control (21.6, 27.9, and 5.1 s, respectively). TU-matrix and TU-matrix/sil presented significant lower Tg than the control (151.5, 153.8, and 161.3 °C, respectively). There were no statistical differences among the groups in terms of shear modulus, cross-link density, breadth of tan delta, flexural strength/modulus, and toughness. For at least one group (TU-matrix/sil), the relaxation time was four times faster than for the control at 105 °C. The addition of TU additives into dental polymers resulted in a stark reduction in the stress relaxation time. This behavior, in tandem with the network characterization and mechanical properties seems to indicate the TU networks undergo a variety of reversible associative and dissociative chemical reactions which facilitate enhanced stress relief.

Thiourethane filler functionalization for dental resin composites: Concentration-dependent effects on toughening, stress reduction and depth of cure.

OBJECTIVES: The aim of this study was to modify the surface of fillers used in dental composites by the synthesis of two novel thiourethane oligomeric silanes, used to functionalize the silica-containing inorganic particles. Several thiourethane silane concentrations were tested during the silanization process to systematically assess the effect of silane coverage on experimental composite conversion, polymerization stress and fracture toughness. MATERIALS AND METHODS: Two different thiourethane silanes were synthesized based either on 1,6-hexanediol-diissocynate (HDDI), or 1,3-bis(1-isocyanato-1-methylethyl) benzene (BDI). Conventional 3-(Trimethoxysilyl)propyl methacrylate was used as the control. Glass fillers were silanized with 1, 2 or 4 wt% of each thiourethane silane, then evaluated by thermogravimetrical analysis. Photopolymerizable resin composites were prepared with Bis-GMA/UDMA/TEGDMA and 50 wt% silanized glass filler. Polymerization kinetics and degree of conversion were tested using Near-IR. Bioman was used to test polymerization stress. Data were analyzed with two-way ANOVA/Tukey's test (α = 5%). RESULTS: The mass of silane coupled to the filler increased with the concentrations of thiourethane in the silanizing solution, as expected. Thiourethane-containing groups exhibited significantly higher degree of conversion compared to control groups, except for BDI 4%. HDDI 4%, BDI 2% and BDI 4% showed significantly lower polymerization stress than control groups. HDDI 4% exhibited significantly higher fracture toughness. CONCLUSIONS AND CLINICAL SIGNIFICANCE: Novel filler functionalization with thiourethane silanes may be a promising alternative for improving dental composites properties by significantly increasing the degree of conversion, fracture toughness and reducing the polymerization stress.

Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations.

OBJECTIVE: The aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion. METHODS: Class I cavities (4mm depth×5mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature - activated for 20s); (2) Filtek Z250XT (at room temperature - activated for 40s); (3) Filtek Z250XT (pre-heated at 68°C - activated for 20s); (4) Filtek Z250XT (pre-heated at 68°C - activated for 40s); (5) Filtek BulkFill (at room temperature - activated for 20s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature - activated for 40s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α=5%). RESULTS: Pre-heating the resin composite did not influence the intra-pulpal temperature (p=0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC. SIGNIFICANCE: Resin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.

An intense source for cold cluster ions of a specific composition.

The demand for nanoscale materials of ultra-high purity and narrow size distribution is addressed. Clusters of Au, C60, H2O, and serine are produced inside helium nanodroplets using a combination of ionization, mass filtering, collisions with atomic or molecular vapor, and electrostatic extraction, in a specific and novel sequence. The helium droplets are produced in an expansion of cold helium gas through a nozzle into vacuum. The droplets are ionized by electron bombardment and subjected to a mass filter. The ionic and mass-selected helium droplets are then guided through a vacuum chamber filled with atomic or molecular vapor where they collide and "pick up" the vapor. The dopants then agglomerate inside the helium droplets around charge centers to singly charged clusters. Evaporation of the helium droplets is induced by collisions in a helium-filled radio frequency (RF)-hexapole, which liberates the cluster ions from the host droplets. The clusters are analyzed with a time-of-flight mass spectrometer. It is demonstrated that using this sequence, the size distribution of the dopant cluster ions is distinctly narrower compared to ionization after pickup. Likewise, the ion cluster beam is more intense. The mass spectra show, as well, that ion clusters of the dopants can be produced with only few helium atoms attached, which will be important for messenger spectroscopy. All these findings are important for the scientific research of clusters and nanoscale materials in general.

Mixed cationic clusters of nitrogen and hydrogen.

The addition of small impurities, such as a single proton charge carrier, in noble gas clusters has recently been shown to have considerable effects on their geometries and stabilities. Here, we report on a mass spectrometric study of cationic clusters of N2 molecules and the effects that adding hydrogen, in the form of D2, has on the systems. Protonated nitrogen clusters formed by the breakup of D2 are shown to have similar behaviors as protonated rare gas clusters. For larger systems consisting of different mixtures of intact N2 and D2, different molecular species are found to be interchangeable sometimes with regard to magic numbers. This is especially true for the (N2)n(D2)mD+ systems with n + m = 17, which is particularly abundant for all measured combinations of n and m.

Intercostal celiotomy for removal of proventriculus foreign body in muscovy duck (Cairina moschata): case report / Celiotomia intercostal para remoção de corpo estranho do proventrículo de pato-do-mato (Cairina Moschata): relato de caso]

Ducks, geese and swans are included in the Anatidae family, Anseriformes order. The leading injuries causes to waterfowl are tangling in fishing materials and foreign bodies ingestion. A muscovy duck (Cairina moschata) was referred for treatment at Veterinary Teaching Hospital and a radiographic examination showed the presence of a hook in the coelom. Surgical exposure and incision of the proventriculus was made through left intercostal access and the hook along with a fishing line were gently removed. The animal began to feed voluntarily at the fourth post-operative day and two weeks after the procedure the patient was clinically well and was released to wild. This surgical approach differs in some aspects from the listed techniques in the known literature. It proved to be a viable and appropriate alternative to treat this affection since it did not cause any trans- or post-operative complications and enabled rapid recovery and subsequent patient release.(AU)

Patos, gansos e cisnes estão incluídos na família Anatidae, ordem Anseriformes. Entre as principais causas de ferimentos em aves aquáticas, o embaraço com materiais de pesca e a ingestão de corpos estranhos são os mais citados. Um pato-do-mato (Cairina moschata) foi encaminhado para tratamento no Hospital Veterinário e, mediante exame radiográfico, verificou-se a presença de um anzol na cavidade celomática, provavelmente no proventrículo. Utilizando-se o acesso intercostal esquerdo, foi feita a exposição e a incisão do proventrículo. Por meio dessa incisão, o anzol com um segmento de linha de pesca foi delicadamente retirado. O animal começou a se alimentar voluntariamente no quarto dia pós-operatório e duas semanas após o procedimento o paciente se encontrava clinicamente bem e apto à soltura. Esta abordagem cirúrgica difere, em alguns aspectos, das técnicas listadas na literatura e provou ser uma alternativa viável e adequada ao caso, não causando complicações e permitindo recuperação rápida, com posterior soltura do animal.(AU)

Oral antioxidant therapy for prevention and treatment of preeclampsia: Meta-analysis of randomized controlled trials.

AIMS: To determine whether oral antioxidant therapies, of various types and doses, are able to prevent or treat women with preeclampsia. DATA SYNTHESIS: The following databases were searched: MEDLINE, CENTRAL, LILACS, and Web of Science. Inclusion criteria were: a) randomized clinical trials; b) oral antioxidant supplementation; c) study in pregnant women; d) control group, treated or not with placebo. Papers were excluded if they evaluated antioxidant nutrient supplementation associated with other non-antioxidant therapies. Data were extracted and the risk of bias of each study was assessed. Heterogeneity was analyzed using the Cochran Q test, and I2 statistics and pre-specified sensitivity analyses were performed. Meta-analyses were conducted on prevention and treatment studies, separately. The primary outcome was the incidence of preeclampsia in prevention trials, and of perinatal death in treatment trials. Twenty-nine studies were included in the analysis, 19 for prevention and 10 for treatment. The antioxidants used in these studies were vitamins C and E, selenium, l-arginine, allicin, lycopene and coenzyme Q10, none of which showed beneficial effects on the prevention of preeclampsia (RR: 0.89, CI 95%: [0.79-1.02], P = 0.09; I2 = 39%, P = 0.04) and other outcomes. The antioxidants used in the treatment studies were vitamins C and E, N-acetylcysteine, l-arginine, and resveratrol. A beneficial effect was found in intrauterine growth restriction. CONCLUSIONS: Antioxidant therapy had no effects in the prevention of preeclampsia but did show beneficial effects in intrauterine growth restriction, when used in the treatment of this condition.

Electron ionization of helium droplets containing C60 and alcohol clusters.

We report a mass spectrometric investigation of (C60)n clusters mixed with either methanol or ethanol clusters inside helium nanodroplets. The abundance of ion products produced by electron ionization shows marked differences compared with pure methanol/ethanol clusters without C60 [M. Goulart, P. Bartl, A. Mauracher, F. Zappa, A. M. Ellis and P. Scheier, Phys. Chem. Chem. Phys., 2013, 15, 3577], where clusters containing in excess of a hundred alcohol monomers were observed. In contrast, under identical conditions concerning He droplet size and alcohol pickup pressure, only a small number of alcohol molecules become attached to the fullerene ions. Our results suggest that each fullerene cluster acts as a charge sink, which hampers alcohol cluster formation, as well as intra-cluster ion-molecule reactions. The appearance of specific 'magic number' peaks suggests an enhanced probability for the attachment of small alcohol rings to (C60)n+ clusters.

Homogenous demineralized dentin matrix and platelet-rich plasma for bone tissue engineering in cranioplasty of diabetic rabbits: biochemical, radiographic, and histological analysis.

This study evaluated the effects of homogenous demineralized dentin matrix (HDDM) slices and platelet-rich plasma (PRP) in surgical defects created in the parietal bones of alloxan-induced diabetic rabbits, treated with a guided bone regeneration technique. Biochemical, radiographic, and histological analyses were performed. Sixty adult New Zealand rabbits were divided into five groups of 12: normoglycaemic (control, C), diabetic (D), diabetic with a PTFE membrane (DM), diabetic with a PTFE membrane and HDDM slices (DM-HDDM), and diabetic with PTFE membrane and PRP (DM-PRP). The quantity and quality of bone mass was greatest in the DM-HDDM group (respective radiographic and histological analyses: at 15 days, 71.70 ± 16.50 and 50.80 ± 1.52; 30 days, 62.73 ± 16.51 and 54.20 ± 1.23; 60 days, 63.03 ± 11.04 and 59.91 ± 3.32; 90 days, 103.60 ± 24.86 and 78.99 ± 1.34), followed by the DM-PRP group (respective radiographic and histological analyses: at 15 days 23.00 ± 2.74 and 20.66 ± 7.45; 30 days 31.92 ± 6.06 and 25.31 ± 5.59; 60 days 25.29 ± 16.30 and 46.73 ± 2.07; 90 days 38.10 ± 14.04 and 53.38 ± 9.20). PRP greatly enhanced vascularization during the bone repair process. Abnormal calcium metabolism was statistically significant in the DM-PRP group (P<0.001) for all four time intervals studied, especially when compared to the DM-HDDM group. Alkaline phosphatase activity was significantly higher in the DM-HDDM group (P<0.001) in comparison to the C, D, and DM-PRP groups, confirming the findings of intense osteoblastic activity and increased bone mineralization. Thus, HDDM promoted superior bone architectural microstructure in bone defects in diabetic rabbits due to its effective osteoinductive and osteoconductive activity, whereas PRP stimulated angiogenesis and red bone marrow formation.

Amniotic membrane as a biological dressing for 5-fluoruracil-induced oral mucositis in rats.

Oral mucositis is a reaction to chemoradiation therapy during cancer treatment. The aim of this study was to investigate the use of amniotic membrane as a biological dressing for oral mucositis lesions in rats. Sixty Wistar rats were divided into three groups (n = 20): control, 5-fluoruracil (5-FU), 5-fluoruracil + amniotic membrane (5-FU+AM). Each group was subdivided (n = 5) according to the time interval to sacrifice (3, 7, 14, and 21 days). Histology (haematoxylin-eosin staining) and immunocytochemistry (anti-rat antibodies CD4, CD8, VEGF, and PCNA) were evaluated. Immunocytochemistry results were analyzed using one-way ANOVA and Tukey tests. The amniotic membrane (5FU+AM) played an important role in cell proliferation (PCNA 3 days 27.08 ± 4.65, 7 days 27.90 ± 3.34) and especially in neovascularization (VEGF 3 days 23.00 ± 1.40, 7 days 26.00 ± 0.95) for all time intervals, when compared to 5-FU (PCNA 3 days 23.12 ± 1.61, 7 days 37.21 ± 1.20; VEGF 3 days 17.05 ± 1.51, 7 days 8.45 ± 1.35) and control (PCNA 3 days 29.99 ± 0.92, 7 days 16.33 ± 2.88; VEGF 3 days 13.65 ± 0.55, 7 days 15.70 ± 1.39). It was biocompatible, showing significant differences compared to the other groups in CD4 (F = 40.72; P = 0.001) and CD8 (F = 69.99, P = 0.001) staining together, only during the inflammation phase (7 days). Amniotic membrane presented biocompatibility and stimulated cell proliferation and neovascularization, functioning as a promising biological dressing.

Tibial osteosynthesis in a guinea pig (Cavia porcellus) / Osteossíntese de tíbia em um cobaio (Cavia porcellus)

A guinea pig was presented with left pelvic limb lameness after unknown trauma. Radiographs revealed complete oblique diaphyseal fracture of the distal third of the left tibia and fibula. The guinea pig was treated surgically with an intramedullary pin. The day after surgery the guinea pig was using the limb comfortably (grade 1/5 lameness). Callus formation was obtained 21 days after surgery without complications.

Um cobaio foi atendido com claudicação de membro pélvico esquerdo após trauma desconhecido. Radiografias revelaram fratura completa oblíqua da diáfise do terço distal da tíbia e fíbula esquerdas. O cobaio foi tratado cirurgicamente com um pino intramedular. No dia seguinte à cirurgia, o paciente utilizava o membro confortavelmente (grau 1/5 de claudicação). Calo ósseo foi obtido 21 dias após a cirurgia, sem complicações.

A thiophene-modified screen printed electrode for detection of dengue virus NS1 protein.

A thiophene-modified screen printed electrode (SPE) for detection of the Dengue virus non-structural protein 1 (NS1), an important marker for acute phase diagnosis, is described. A sulfur-containing heterocyclic compound, the thiophene was incorporated to a carbon ink to prepare reproducible screen printed electrodes. After cured, the thiophene SPE was coated by gold nanoparticles conjugated to Protein A to form a nanostrutured surface. The Anti-NS1 antibodies immobilized via their Fc portions via Protein A, leaving their antigen specific sites free circumventing the problem of a random antibodies immobilization. Amperometric responses to the NS1 protein of dengue virus were obtained by cyclic voltammetries performed in presence of ferrocyanide/ferricyanide as redox probe. The calibration curve of immunosensor showed a linear response from 0.04 µg mL(-1) to 0.6 µg mL(-1) of NS1 with a good linear correlation (r=0.991, p<0.05). The detection limit (0.015 µg mL(-1) NS1) was lower than conventional analytical methods. In this work, thiophene monomers incorporated in the carbon ink enhanced the electroanalytical properties of the SPEs, increasing their reproducibility and sensitivity. This point-of-care testing represents a great potential for use in epidemic situations, facilitating the early diagnosis in acute phase of dengue virus.

Decorating (C60) n+, n = 1-3, with CO2 at low temperatures: Sterically enhanced physisorption.

Multiple attachment of CO2 to the monomer, dimer and trimer cations of C60 has been observed in the mass spectra of He nanodroplets sequentially doped with C60 and CO2 and exposed to electron ionization at 50 eV. Remarkable anomalies were seen in the ion yield for CO2 coverage for (C60)2+(CO2)8 and (C60)3+(CO2)1,2. These provide insight into the influence of steric properties on the nature of physisorption. The enhanced stabilities of (C60)2+(CO2)8 and (C60)3+(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60. Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.

Correlação entre cálcio e insulina durante o teste de tolerância à glicose em ovelhas gestantes e não gestantes / Calcium and insulin correlation during the glucose tolerance test in pregnant non-pregnant ewes

Compararam-se as concentrações de cálcio, glicose e insulina em ovelhas gestantes e não gestantes submetidas ao teste de tolerância à glicose (TTG). Oito ovelhas gestantes (GG) e oito não gestantes (NG) foram submetidas ao TTG por meio da administração endovenosa de uma solução de glicose, na dose de 500mg/kg de peso vivo. Amostras de sangue foram coletadas nos tempos de -15, zero, 15, 30, 45, 60, 90, 120, 150 e 180 minutos, sendo zero min o momento da infusão, para avaliação da concentração sanguínea de glicose, cálcio e insulina. Foi avaliada a taxa de metabolização de glicose e insulina, por meio do cálculo da área sob a curva (ASC). As concentrações de glicose, cálcio, insulina e a ASC da insulina não diferiram entre os grupos (P>0,05), entretanto as três últimas ASCs da glicose foram mais elevados nas gestantes (P<0,05), que correspondem ao período entre 90 e 180min. O teste de correlação de Pearson revelou correlação negativa entre concentração de cálcio e insulina nas gestantes (P<0,05). Estes resultados indicam menor taxa de metabolização de glicose em ovelhas gestantes e uma possível relação de cálcio e insulina no terço final de gestação.

The aim of this study was to investigate glucose, insulin and calcium metabolism during the Glucose Tolerance Test (GTT) in pregnant or nonpregnant ewes. Eight pregnant (PG) and nonpregnant (NPG) ewes per group received a glucose endovenosus bolus containning 500mg/kg in one minute. Blood samples were collected on -15, 0, 15, 30, 45, 60, 90, 120, 150 and 180 minutes interval (0 min - injection). These samples were used to evaluate glucose, calcium, insulin concentration, as well as insulin and glucose metabolization rate, which were determined by calculating the Area Under the Curve (AUC). The calcium, glucose and insulin concentrations were not different between groups. However, the three last glucose ASCs were higher in the pregnant group and in this group calcium and insulin blood concentrations were negatively correlated .These results showed lower glucose tolerance in pregnant ewes and suggest a link between insulin and calcium in the late pregnancy.

Growth inhibitory effects of 3'-nitro-3-phenylamino nor-beta-lapachone against HL-60: a redox-dependent mechanism.

In this study, the cytotoxicity, genotoxicity and early ROS generation of 2,2-dimethyl-(3H)-3-(N-3'-nitrophenylamino)naphtho[1,2-b]furan-4,5-dione (QPhNO(2)) were investigated and compared with those of its precursor, nor-beta-lapachone (nor-beta), with the main goal of proposing a mechanism of antitumor action. The results were correlated with those obtained from electrochemical experiments held in protic (acetate buffer pH 4.5) and aprotic (DMF/TBABF(4)) media in the presence and absence of oxygen and with those from dsDNA biosensors and ssDNA in solution, which provided evidence of a positive interaction with DNA in the case of QPhNO(2). QPhNO(2) caused DNA fragmentation and mitochondrial depolarization and induced apoptosis/necrosis in HL-60 cells. Pre-treatment with N-acetyl-l-cysteine partially abolished the observed effects related to the QPhNO(2) treatment, including those involving apoptosis induction, indicating a partially redox-dependent mechanism. These findings point to the potential use of the combination of pharmacology and electrochemistry in medicinal chemistry.

Facile synthesis of oxo-/thioxopyrimidines and tetrazoles C-C linked to sugars as novel non-toxic antioxidant acetylcholinesterase inhibitors.

Microwave-assisted synthesis of oxo-/thioxopyrimidines and tetrazoles linked to furanoses with D-xylo and D-ribo configuration, and to a D-galacto pyranose is reported and compared to conventional methods. Reaction of dialdofuranoses and dialdopyranoses with a ß-keto ester and urea or thiourea under microwave irradiation at 300 W gave in 10 min the target molecules containing the 2-oxo- or 2-thioxo-pyrimidine ring in high yield. The tetrazole-derived compounds were obtained in two steps by reaction of the formyl group with hydroxylamine hydrochloride, copper sulfate, triethylamine and dicyclohexylcarbodiimide to give an intermediate nitrile, which was then treated with sodium azide. The use of microwave irradiation in the latter step also resulted in a considerably shorter reaction time (10 min) compared to hours under conventional heating to obtain a complete starting materials conversion. Acetylcholinesterase inhibition ranged from 20% to 80% for compounds concentration of 100 µg/mL, demonstrating the potential of this family of compounds for the control of Alzheimer's disease symptoms. Most of the compounds showed antioxidant activity in the ß-carotene/linoleic acid assay, some of them exhibiting IC(50) values in the same order of magnitude as those of gallic acid. The bioactive compounds did not show cytotoxic effects to human lymphocytes using the MTT method adapted for non-adherent cells, nor genotoxicity determined by the short-term in vitro chromosomal aberration assay.

Phenotypic plasticity to light of two congeneric trees from contrasting habitats: Brazilian Atlantic Forest versus cerrado (savanna).

The Brazilian Atlantic Forest is a typically multi-layer tropical forest, while cerrado (savanna) is a patchy habitat with different physiognomy. Despite these differences, both habitats have high light heterogeneity. Functional traits of Dalbergia nigra and D. miscolobium from the Atlantic Forest and cerrado, respectively, were evaluated under shade (25% of full sunlight) and full sunlight in a nursery experiment. We hypothesised that both species should benefit from high phenotypic plasticity in relation to light. Plasticity was estimated using the relative distance phenotypic index (RDPI). D. miscolobium had lower shoot growth under both light conditions, suggesting it has low competitive capacity in the forest environment, which could explain its limited ability to expand over areas of Atlantic Forest. The studied species exhibited photoprotection strategies under high light and improved light capture under low light. Stomatal conductance, ETR(max) (maximum electron transport rate), PPFD(sat) (saturating photosynthetically active photon flux density), chlorophyll and carotenoid content had higher RDPI than stem morphological traits. Although both species showed considerable phenotypic plasticity, D. miscolobium had higher RDPI for eight of 11 evaluated traits. This high plasticity could be one of the factors that explain the occurrence of this species in a wide range of environmental conditions, from open grassland to dense woodlands, and it could also reflect its adaptation to high light. D. nigra also had considerable plasticity and good growth performance in both shade and full sunlight, but its absence in areas of cerrado suggests that factors other than light limit its occurrence in these habitats.