An industrialized diet as a determinant of methylation in the 1F region of the NR3C1 gene promoter.

Background: Dietary composition can modify gene expression, favoring the development of chronic diseases via epigenetic mechanisms. Objective: Our study aimed to investigate the relationship between dietary patterns and NR3C1 gene methylation in users of the Brazilian Public Unified Health System (SUS). Methods: We recruited 250 adult volunteers and evaluated their socioeconomic status, psychosocial characteristics, lifestyle, and anthropometrics. Peripheral blood was collected and evaluated for cortisol levels, glycemia, lipid profile, and insulin resistance; methylation of CpGs 40-47 of the 1F region of the NR3C1 gene was also measured. Factors associated with degree of methylation were evaluated using generalized linear models (p < 0.05). Lifestyle variables and health variables were included as confounding factors. Results: The findings of our cross-sectional study indicated an association between NR3C1 DNA methylation and intake of processed foods. We also observed relevant associations of average NR3C1 DNA across the segment analyzed, methylation in component 1 (40-43), and methylation in component 2 (44-47) with a pattern of consumption of industrialized products in relation to BMI, serum cortisol levels, and lipid profile. These results may indicate a relationship between methylation and metabolic changes related to the stress response. Conclusion: These findings suggest an association of methylation and metabolic alterations with stress response. In addition, the present study highlights the significant role of diet quality as a stress-inducing factor that influences NR3C1 methylation. This relationship is further linked to changes in psychosocial factors, lifestyle choices, and cardiometabolic variables, including glucose levels, insulin resistance, and hyperlipidemia.

Methylation of BDNF gene in association with episodic memory in women.

Brain-derived neurotrophic factor (BDNF) gene regulation plays an important role in long-term memory formation, and the DNA methylation (DNAm) level of BDNF promoters has been associated with episodic memory deficits. Our aim was to explore the association between DNAm levels in BDNF promoter IV with verbal learning and memory performance in healthy women. We conducted a cross-sectional study by recruiting 53 individuals. Episodic memory was assessed by using the Rey Auditory Verbal Learning Test (RAVLT). Clinical interviews, RAVLT, and blood sample collection were assessed in all participants. DNAm was measured on DNA from whole peripheral blood using pyrosequencing. According to generalized linear model (GzLM) analyses, cytosine guanine dinucleotide (CpG) site 5 showed significant associations between learning capacity (LC, p < 0.035), that is, every 1% of DNA methylation at CpG site 5 results in a 0.068 reduction in verbal learning performance. To the best of our knowledge, the current study is the first to show that BDNF DNAm plays an important role in episodic memory.

Tobacco use modify exon IV BDNF gene methylation levels in depression.

This study aimed to investigate BDNF gene methylation in individuals with depression based on tobacco use. Therefore, 384 adults from southeastern Brazil were recruited to assess depression, socioeconomic status, lifestyle, and methylation by pyrosequencing exon IV promoter region of the BDNF gene. The Generalized Linear Model (GzLM) was used to check the effect of depression, tobacco, and the interaction between depression and tobacco use in methylation levels. In addition, the Kruskal-Wallis test, followed by Dunn's post hoc test, was used to compare methylation levels. Interaction between depression and tobacco use was significant at levels of BDNF methylation in the CpG 5 (p = 0.045), 8 (p = 0.016), 9 (p = 0.042), 10 (p = 0.026) and mean 5-11 (p < 0.001). Dunn's post hoc test showed that individuals with depression and tobacco use compared to those with or without depression who did not use tobacco had lower levels of BDNF methylation in CpG 5, 6, 7, 8, 9, 11, and mean 5-11. Therefore, we suggest that tobacco use appears to interfere with BDNF gene methylation in depressed individuals.

Lifestyle and NR3C1 exon 1F gene methylation is associated with changes in glucose levels and insulin resistance.

AIMS: the present study aimed to investigate how glucose and insulin levels may be associated with changes in NR3C1 gene methylation levels in adults. MAIN METHODS: 375 volunteers users of the Brazilian Public Unified Health System (SUS) were recruited to assess socioeconomic status, lifestyle, anthropometric data, blood glucose and serum cortisol levels, insulin resistance, and NR3C1 gene methylation assessment. Factors associated with glucose levels and insulin resistance were investigated using multivariate analysis GLzM at 5% significance (p<0.05). KEY FINDINGS: our results verified that glucose levels and insulin resistance were directly related to NR3C1 gene methylation and age, while not being overweight and obese and no tobacco consumption were indirectly related to glucose levels and insulin resistance. SIGNIFICANCE: habits and lifestyle may influence NR3C1 gene regulation, revealing the complexity of environmental impacts on NR3C1 methylation. Furthermore, associated risk factors must be taken into account in epigenetic studies as they directly interfere with blood glucose levels and insulin resistance.

PAI-1 expression in intratumoral inflammatory infiltrate contributes to lymph node metastasis in oral cancer: A cross-sectional study.

INTRODUCTION: Immune cells contribute with mediators in the protein expression profile of the tumor microenvironment. Levels of plasminogen activator inhibitor-1 (PAI-1) are elevated in non-malignant inflammatory conditions; however, the association between PAI-1 expression and inflammation remains uncertain in oral squamous cell carcinoma (OSCC). This study aimed to investigate PAI-1 expression in mononuclear inflammatory cell infiltrate in OSCC and its role as a prognostic marker. METHODS: Samples were collected from patients with OSCC, treated surgically, and followed for 24 months after the procedure. Thirty-nine tumoral tissue were analyzed using immunohistochemistry. Correlation between protein expression, clinicopathological parameters, and the prognosis was investigated. RESULTS: Positive PAI-1 expression in mononuclear inflammatory cell infiltrate was significantly associated with lymph node status (p = 0.009) and with the cytoplasmic expression of vascular endothelial growth factor A (VEGFA) (p = 0.028). Multivariate analysis revealed weak PAI-1 expression as an independent marker for lymph node metastases, with approximately 8-fold increased risk compared to strong expression (OR = 8.60; CI = 1.54-48.08; p = 0.014). CONCLUSION: Our results suggest that the strong PAI-1 expression in intratumoral inflammatory infiltrate is an indicator of a better prognosis for patients diagnosed with oral squamous cell carcinoma.

Food and nutritional insecurity is associated with depressive symptoms mediated by NR3C1 gene promoter 1F methylation.

The aim of this study was to investigate socioeconomic stressors predictive of depressive symptoms and possible epigenetic changes in the glucocorticoid receptor - NR3C1-1F - an encoding gene involved in depressive symptoms. A total of 321 adult volunteers from southeastern Brazil were recruited to evaluate depressive symptoms, socio-demographic and economic factors, including food and nutritional security (FNS) or insecurity (FNiS) status, and NR3C1-1F region methylation by pyrosequencing. Depressive symptom determinants were investigated using a Poisson regression model with robust variance. Mann-Whitney tests and structural mediation equation models were used to evaluate the relationship between NR3C1 DNA methylation, FNiS, and depressive symptoms. Multivariate Poisson regression with robust variance adjusted for sex and FNiS and NR3C1-1F region methylation predicted risk factors for depressive symptoms. Mediation analysis revealed that NR3C1-1F region methylation mediated the relationship between FNiS exposure and depressive symptoms as an outcome, and depressive volunteers and FNiS individuals exhibited a significant increase in NR3C1 methylation when compared to healthy individuals and FNS volunteers, respectively. Therefore, we suggest that stress caused by FNiS may lead to depressive symptoms and that NR3C1-1F DNA methylation can act as a mediator of both FNiS and depressive symptoms.

Alcohol consumption, depression, overweight and cortisol levels as determining factors for NR3C1 gene methylation.

The NR3C1 glucocorticoid receptor (GR) gene is a component of the stress response system, which can be regulated by epigenetic mechanisms. NR3C1 methylation has been associated with trauma and mental issues, including depression, post-traumatic stress, anxiety, and personality disorders. Previous studies have reported that stressful events are involved in NR3C1 gene methylation, suggesting that its regulation under environmental effects is complex. The present study aimed to analyze associations involving stressors such as socioeconomic status, health conditions, and lifestyle in relation to NR3C1 methylation in adults. This study included 386 individual users of the Brazilian Public Unified Health System (SUS), and evaluated socioeconomic and health conditions, body mass index, cortisol levels, and lifestyle. Data were correlated with NR3C1 methylation, determined using DNA pyrosequencing. The results showed that alcohol consumption, overweight, and high cortisol levels were related to NR3C1 demethylation, while depression was related to its methylation. Habits, lifestyle, and health status may influence NR3C1 gene regulation via methylation, revealing the complexity of environmental impacts on NR3C1 methylation.

Measuring the α-particle charge radius with muonic helium-4 ions.

The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering1, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle2-5, in line with recent determinations of the proton charge radius6-9, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties.

Risk factors for depression in adults: NR3C1 DNA methylation and lifestyle association.

OBJECTIVE: The aim of this study was to verify determinant factors for depression and analyze the relationship between possible changes in HPA axis and depression, in this case NR3C1 DNA methylation and serum cortisol levels. METHODS: 349 adult volunteers were recruited to evaluate depression, socio-demographic, economic and lifestyle factors, serum cortisol levels and NR3C1 DNA methylation by pyrosequencing. Depression determinant factors were investigated using a Poisson regression model with robust variance (p < 0.05). RESULTS: Poisson regression with robust variance adjusted by gender, tobacco use, self-perceived stress, leisure activity, suicidal ideation, low cortisol levels and NR3C1 DNA methylation was performed and predicted risk factors for depression. Furthermore, depressive volunteers showed a significant increase in NR3C1 DNA methylation when compared to healthy volunteers. CONCLUSIONS: This findings provide a basis for understanding the role of HPA axis in depression, especially its regulation by NR3C1 DNA methylation. Furthermore, it emphasizes the stressful lifestyle risk factors (female, tobacco uso, self perceived stress, leisure activities absence and suicidal ideation) that can contribute to future research and the search for public health policies to improve quality of live, mental and general health.

Windthrows control biomass patterns and functional composition of Amazon forests.

Amazon forests account for ~25% of global land biomass and tropical tree species. In these forests, windthrows (i.e., snapped and uprooted trees) are a major natural disturbance, but the rates and mechanisms of recovery are not known. To provide a predictive framework for understanding the effects of windthrows on forest structure and functional composition (DBH ≥10 cm), we quantified biomass recovery as a function of windthrow severity (i.e., fraction of windthrow tree mortality on Landsat pixels, ranging from 0%-70%) and time since disturbance for terra-firme forests in the Central Amazon. Forest monitoring allowed insights into the processes and mechanisms driving the net biomass change (i.e., increment minus loss) and shifts in functional composition. Windthrown areas recovering for between 4-27 years had biomass stocks as low as 65.2-91.7 Mg/ha or 23%-38% of those in nearby undisturbed forests (~255.6 Mg/ha, all sites). Even low windthrow severities (4%-20% tree mortality) caused decadal changes in biomass stocks and structure. While rates of biomass increment in recovering vegetation were nearly double (6.3 ± 1.4 Mg ha-1  year-1 ) those of undisturbed forests (~3.7 Mg ha-1  year-1 ), biomass loss due to post-windthrow mortality was high (up to -7.5 ± 8.7 Mg ha-1  year-1 , 8.5 years since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40 years. Resprouting trees contributed little to biomass recovery. Instead, light-demanding, low-density genera (e.g., Cecropia, Inga, Miconia, Pourouma, Tachigali, and Tapirira) were favored, resulting in substantial post-windthrow species turnover. Shifts in functional composition demonstrate that windthrows affect the resilience of live tree biomass by favoring soft-wooded species with shorter life spans that are more vulnerable to future disturbances. As the time required for forests to recover biomass is likely similar to the recurrence interval of windthrows triggering succession, windthrows have the potential to control landscape biomass/carbon dynamics and functional composition in Amazon forests.

PAI-1, CAIX, and VEGFA expressions as prognosis markers in oral squamous cell carcinoma.

BACKGROUND: In oral squamous cell carcinoma (OSCC), the HIF-1 complex promotes the expression of genes involved in specific mechanisms of cell survival under hypoxic conditions, such as plasminogen activator inhibitor-1 (PAI-1), carbonic anhydrase 9 (CAIX), and vascular endothelial growth factor A (VEGFA). The study aimed to investigate the presence and prognostic value of PAI-1, CAIX, and VEGFA in OSCC. MATERIALS AND METHODS: Immunohistochemistry was used to analyze the expressions of these proteins in 52 tumoral tissue samples of patients with OSCC, surgically treated and followed by a minimum of 24 months after surgery. The correlations between protein expressions and clinicopathological parameters and prognosis were analyzed. RESULTS: Positive PAI-1 membrane expression was significantly associated with local disease relapse (P = .027). Multivariate analysis revealed that the positive PAI-1 membrane expression is an independent marker for local disease relapse, with approximately 14-fold increased risk when compared to negative expression (OR = 14.49; CI = 1.40-150.01, P = .025). Strong PAI-1 cytoplasmic expression was significantly associated with the less differentiation grade (P = .027). Strong CAIX membrane expression was significantly associated with local disease-free survival (P = .038). Positive CAIX cytoplasmic expression was significantly associated with lymph node affected (P = .025) and with disease-specific survival (P = .022). Multivariate analysis revealed that the positive CAIX cytoplasmic expression is an independent risk factor for disease-related death, increasing their risk approximately 3-fold when compared to negative expression (HR = 2.84; CI = 1.02-7.87, P = .045). Positive VEGFA cytoplasmic expression was significantly associated with less differentiation grade (P = .035). CONCLUSION: Our results suggest a potential role for these expressions profiles as tumor prognostic markers in OSCC patients.

JMJD1A, H3K9me1, H3K9me2 and ADM expression as prognostic markers in oral and oropharyngeal squamous cell carcinoma.

AIMS: Jumonji Domain-Containing 1A (JMJD1A) protein promotes demethylation of histones, especially at lysin-9 of di-methylated histone H3 (H3K9me2) or mono-methylated (H3K9me1). Increased levels of H3 histone methylation at lysin-9 (H3K9) is related to tumor suppressor gene silencing. JMJD1A gene target Adrenomeduline (ADM) has shown to promote cell growth and tumorigenesis. JMJD1A and ADM expression, as well as H3K9 methylation level have been related with development risk and prognosis of several tumor types. METHODS AND RESULTS: We aimed to evaluate JMJD1A, ADM, H3K9me1 and H3K9me2expression in paraffin-embedded tissue microarrays from 84 oral and oropharyngeal squamous cell carcinoma samples through immunohistochemistry analysis. Our results showed that nuclear JMJD1A expression was related to lymph node metastasis risk. In addition, JMJD1A cytoplasmic expression was an independent risk marker for advanced tumor stages. H3K9me1 cytoplasmic expression was associated with reduced disease-specific death risk. Furthermore, high H3K9me2 nuclear expression was associated with worse specific-disease and disease-free survival. Finally, high ADM cytoplasmic expression was an independent marker of lymph node metastasis risk. CONCLUSION: JMJD1A, H3K9me1/2 and ADM expression may be predictor markers of progression and prognosis in oral and oropharynx cancer patients, as well as putative therapeutic targets.

Laser spectroscopy of muonic deuterium.

The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius rd and the polarizability serve as important benchmarks for understanding the nuclear forces and structure. Muonic deuterium µd is the exotic atom formed by a deuteron and a negative muon µ(-). We measured three 2S-2P transitions in µd and obtain r(d) = 2.12562(78) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value r(d) = 2.1424(21) fm. The µd value is also 3.5σ smaller than the r(d) value from electronic deuterium spectroscopy. The smaller r(d), when combined with the electronic isotope shift, yields a "small" proton radius r(p), similar to the one from muonic hydrogen, amplifying the proton radius puzzle.

Improved x-ray detection and particle identification with avalanche photodiodes.

Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work, we report on a fitting technique used to account for different detector responses resulting from photoabsorption in the various avalanche photodiode layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2 and corrects the timing information by up to 25 ns to account for space dependent electron drift time. In addition, this waveform analysis is used for particle identification, e.g., to distinguish between x-rays and MeV electrons in our experiment.

Large-scale wind disturbances promote tree diversity in a Central Amazon forest.

Canopy gaps created by wind-throw events, or blowdowns, create a complex mosaic of forest patches varying in disturbance intensity and recovery in the Central Amazon. Using field and remote sensing data, we investigated the short-term (four-year) effects of large (>2000 m(2)) blowdown gaps created during a single storm event in January 2005 near Manaus, Brazil, to study (i) how forest structure and composition vary with disturbance gradients and (ii) whether tree diversity is promoted by niche differentiation related to wind-throw events at the landscape scale. In the forest area affected by the blowdown, tree mortality ranged from 0 to 70%, and was highest on plateaus and slopes. Less impacted areas in the region affected by the blowdown had overlapping characteristics with a nearby unaffected forest in tree density (583 ± 46 trees ha(-1)) (mean ± 99% Confidence Interval) and basal area (26.7 ± 2.4 m(2) ha(-1)). Highly impacted areas had tree density and basal area as low as 120 trees ha(-1) and 14.9 m(2) ha(-1), respectively. In general, these structural measures correlated negatively with an index of tree mortality intensity derived from satellite imagery. Four years after the blowdown event, differences in size-distribution, fraction of resprouters, floristic composition and species diversity still correlated with disturbance measures such as tree mortality and gap size. Our results suggest that the gradients of wind disturbance intensity encompassed in large blowdown gaps (>2000 m(2)) promote tree diversity. Specialists for particular disturbance intensities existed along the entire gradient. The existence of species or genera taking an intermediate position between undisturbed and gap specialists led to a peak of rarefied richness and diversity at intermediate disturbance levels. A diverse set of species differing widely in requirements and recruitment strategies forms the initial post-disturbance cohort, thus lending a high resilience towards wind disturbances at the community level.

Proton structure from the measurement of 2S-2P transition frequencies of muonic hydrogen.

Accurate knowledge of the charge and Zemach radii of the proton is essential, not only for understanding its structure but also as input for tests of bound-state quantum electrodynamics and its predictions for the energy levels of hydrogen. These radii may be extracted from the laser spectroscopy of muonic hydrogen (µp, that is, a proton orbited by a muon). We measured the 2S(1/2)(F=0)-2P(3/2)(F=1) transition frequency in µp to be 54611.16(1.05) gigahertz (numbers in parentheses indicate one standard deviation of uncertainty) and reevaluated the 2S(1/2)(F=1)-2P(3/2)(F=2) transition frequency, yielding 49881.35(65) gigahertz. From the measurements, we determined the Zemach radius, r(Z) = 1.082(37) femtometers, and the magnetic radius, r(M) = 0.87(6) femtometer, of the proton. We also extracted the charge radius, r(E) = 0.84087(39) femtometer, with an order of magnitude more precision than the 2010-CODATA value and at 7σ variance with respect to it, thus reinforcing the proton radius puzzle.

The size of the proton.

The proton is the primary building block of the visible Universe, but many of its properties-such as its charge radius and its anomalous magnetic moment-are not well understood. The root-mean-square charge radius, r(p), has been determined with an accuracy of 2 per cent (at best) by electron-proton scattering experiments. The present most accurate value of r(p) (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants. This value is based mainly on precision spectroscopy of atomic hydrogen and calculations of bound-state quantum electrodynamics (QED; refs 8, 9). The accuracy of r(p) as deduced from electron-proton scattering limits the testing of bound-state QED in atomic hydrogen as well as the determination of the Rydberg constant (currently the most accurately measured fundamental physical constant). An attractive means to improve the accuracy in the measurement of r(p) is provided by muonic hydrogen (a proton orbited by a negative muon); its much smaller Bohr radius compared to ordinary atomic hydrogen causes enhancement of effects related to the finite size of the proton. In particular, the Lamb shift (the energy difference between the 2S(1/2) and 2P(1/2) states) is affected by as much as 2 per cent. Here we use pulsed laser spectroscopy to measure a muonic Lamb shift of 49,881.88(76) GHz. On the basis of present calculations of fine and hyperfine splittings and QED terms, we find r(p) = 0.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm. Our result implies that either the Rydberg constant has to be shifted by -110 kHz/c (4.9 standard deviations), or the calculations of the QED effects in atomic hydrogen or muonic hydrogen atoms are insufficient.

Análise estrutural da floresta tropical úmida do município de Alta Floresta, Mato Grosso, Brasil

This paper deals with the composition and structure of a pristine tropical rainforest using likelihood patterns to compare it with other Amazonian sites. This work was carried out in Alta Floresta, Mato Grosso. Our ground truth was obtained from a two-hectare plot, which was divided into 20 plots of 10 by 100 m each. In each plot, all trees with dbh = 10 cm were recorded. To evaluate the level of similarity between the Alta Floresta and other nine Amazonian sites we used the hierarchy clustering method linked by group means (UPGMA) through Sorensen index (qualitative). For ordination, we used the same method based on multidimensional non-metric scaling (NMS) through Jaccard index applied to presence or absence of botanical families or genera. The software PATN was used to run Mantel test with Jaccard index, which was, in turn, used for the similarity analysis among sites. The studied site presented 1,101 individuals distributed in 32 botanical families, 54 genera e 68 species. The richest family was Leguminosae. Helicostilys podogyne and Cecropia sp. were the most important species of the studied area. The Alta Floresta site did not present any similarity when compared to other Amazonian sites.

Este trabalho teve como objetivo estudar a composição e estrutura de um estrato arbóreo da floresta tropical úmida em Alta Floresta - MT, determinando os padrões de semelhança com outras regiões da Amazônia brasileira. O estudo foi realizado em uma área de 2 hectares, dividida em 20 parcelas de 10x 100m, onde foram mensurados a altura e o DAP 10 cm de todos os indivíduos. Para avaliação do grau de similaridade entre a composição florística e estrutura arbórea de Alta Floresta com as nove regiões pertencentes à Amazônia Legal brasileira, utilizou-se o método de agrupamento hierárquico aglomerativo com ligações pela média dos grupos (UPGMA), por meio do índice de Sorensen (qualitativo). Para a ordenação, foi utilizado o mesmo programa, utilizando a Escalonamento Multidimensional não-métrica (NMS) por meio do índice de Jaccard aplicado à presença e ausência de famílias e gêneros. Para análise de similaridade entre as 10 regiões, comparando a matriz de distâncias físicas entre elas com as matrizes de composição de famílias e gêneros, utilizou-se o programa PATN por meio do Teste de Mantel com o índice de Jaccard. A região apresentou 1101 indivíduos, pertencentes a 32 famílias, 54 gêneros e 68 espécies. A família com maior riqueza de espécie foi Leguminosae. A espécie Helicostilys podogyne e o gênero Cecropia sp. foram as mais importantes no levantamento. A floresta tropical úmida de Alta Floresta não se assemelhou com nenhuma das nove regiões comparadas neste estudo.

Análise de custos e rendimentos de diferentes métodos de corte de cipós para produção de madeira na floresta nacional do Tapajós

This survey was conducted in the Tapajós National Forest, in the state of Pará, Brazil evaluating the cost and income of four different methods of cutting vines in the course of forest management, looking to log wood production. Each method was conducted in an area of 96 ha by cutting the vines (1) around all commercial and potentially commercial trees (Method M1), (2) only in the area of commercial and potentially commercial tree occurrence (Method M2), (3) around al commercial and potentially commercial trees and toward fall (Method M3), and (4) only around those commercial trees chosen for the first harvest (Method M4). In all variables analyzed, the methods differed statistically.Method M4 which showed the lowest cost (6.35 U.S. $), may be considered the best. In this method, the vine population was partially preserved, which is important ecologically.

Esta pesquisa foi realizada na Floresta Nacional do Tapajós, Pará, e foram avaliados os custos e rendimentos de quatro diferentes Métodos de corte de cipós na condução do manejo florestal, visando à produção de madeira em toras. Cada método foi conduzido numa área de 96 ha e a metodologia consistiu em cortar os cipós em torno de todas as árvores comerciais e potencialmente comerciais (Método M1-Individual), apenas na área de ocorrência de árvores comerciais e potencialmente comerciais (Método M2-Zoneado), em torno de todas as árvores comerciais e potencialmente comerciais e na direção de queda (Método M3-direção de queda) e apenas em torno das árvores comerciais destinadas à primeira colheita (Método M4). Em todas as variáveis analisadas os métodos utilizados diferiram estatisticamente. O método M4, com o menor custo (6,35 US$) e maior rendimento (2,07 ha/hora) é considerado o melhor desta pesquisa. Neste método, a população de cipós é parcialmente preservada, mantendo, assim, sua importante função ecológica na floresta.