An efficient removal approach for degradation of metformin from aqueous solutions with sulfate radicals.

Metformin consumption for diabetes treatment is increasing, leading to its presence in wastewater treatment plants where conventional methods cannot remove it. Therefore, this work aims to analyze the performance of advanced oxidation processes using sulfate radicals in the degradation of metformin from water. Experiments were performed in a photoreactor provided with a low-pressure Hg lamp, using K2S2O8 as oxidant and varying the initial metformin concentration (CA0), oxidant concentration (Cox), temperature (T), and pH in a response surface experimental design. The degradation percentages ranged from 26.1 to 87.3%, while the mineralization percentages varied between 15.1 and 64%. Analysis of variance (ANOVA) showed that the output variables were more significantly affected by CA0, Cox, and T. Besides, a reduction of CA0 and an increase of Cox up to 5000 µM maximizes the metformin degradation since the generation of radicals and their interaction with metformin molecules are favored. For the greatest degradation percentage, the first order apparent rate constant achieved was 0.084 min-1. Furthermore, while in acidic pH, temperature benefits metformin degradation, an opposite behavior is obtained in a basic medium because of recombination and inhibition reactions. Moreover, three degradation pathways were suggested based on the six products detected by HPLC-MS: N-cyanoguanidine m/z = 85; N,N-dimethylurea m/z = 89; N,N-dimethyl-cyanamide m/z = 71 N,N-dimethyl-formamide m/z = 74; glicolonitrilo m/z = 58; and guanidine m/z = 60. Finally, it was shown that in general the toxicity of the degradation byproducts was lower than the toxicity of metformin toward Chlamydomonas reinhardtii.

Fatigue Failure Load of a Bonded Simplified Monolithic Feldspathic Ceramic: Influence of Hydrofluoric Acid Etching and Thermocycling.

OBJECTIVE: To evaluate the effect of hydrofluoric acid (HF) etching and thermocycling (Tc) on fatigue failure load of feldspathic ceramic restorations cemented with two resin cements. METHODS: Disc-shaped feldspathic ceramic (Vitablocs Mark II; Ø=10 mm, 1.0-mm thick) and G10 epoxy resin (Ø=10 mm, 2.5-mm thick) specimens were made and randomly allocated considering three factors: ceramic etching (ie, with vs without 10% HF plus silane application), resin cement (ie, self-adhesive [RelyX U200; U200] or conventional [Multilink Automix; MA]), and Tc (ie, with vs without 5-55°C/12,000 cycles). Adhesive cementation followed each manufacturer's instructions. The fatigue test (n=20) was based on the staircase approach (250,000 cycles; 20 Hz). Contact angle, surface topography, and fractography analysis were also executed. Specific statistical tests were employed for each outcome (α=0.05). RESULTS: The interaction of HF and Tc factors decreased the fatigue resistance for both cements (U200 542.63>U200/HF-Tc 495.00; MA 544.47>MA/HF-Tc 506.84). Comparing the cements associated with HF or Tc, there was statistical superiority for MA (U200-Tc 537.37

Abiotic factors drives floristic variations of fern's metacommunity in an Atlantic Forest remnant / Fatores abióticos regulam as variações florísticas na metacomunidade de samambaias em um remanescente de Floresta Atlântica

Abstract We analyzed floristic variations in fern's metacommunity at the local scale and their relationship with abiotic factors in an Atlantic Forest remnant of northeastern Brazil. Floristic and environmental variations were accessed on ten plots of 10 × 20 m. We performed cluster analyses, based on Bray-Curtis dissimilarity index to establish the floristic relationship. The influence of abiotic factors: luminosity, temperature, relative air humidity and relative soil moisture was evaluated from a redundancy analysis. We found 24 species belonging to 20 genera and 12 families. The fern's flora showed high floristic heterogeneity (>75% for most of the plot's associations). The fern's metacommunity was structured along an abiotic gradient modulated by temperature, luminosity, and relative soil moisture.

Resumo Analisamos as variações florísticas na metacomunidade de samambaias em escala local e sua relação com fatores abióticos em um remanescente de Floresta Atlântica no Nordeste do Brasil. Variações florísticas e ambientais foram acessadas a partir de dez parcelas de 10 × 20 m. Realizamos análises de cluster, baseado no índice de similaridade de Bray-Curtis para estabelecer relações florísticas. A influência de fatores abióticos: luminosidade, temperatura, umidade relativa do ar e umidade relativa do solo foram avaliadas a partir da análise de redundância. Encontramos 24 espécies pertencentes a 20 gêneros e 12 famílias. A flora de samambaias exibiu uma elevada heterogeneidade florística (>75% para a maioria das associações entre plots). Observou-se que a metacomunidade de samambaias estava estruturada ao longo de um gradiente abiótico modulado pela temperatura, luminosidade e umidade relativa do solo.

Abiotic factors drives floristic variations of fern's metacommunity in an Atlantic Forest remnant.

We analyzed floristic variations in fern's metacommunity at the local scale and their relationship with abiotic factors in an Atlantic Forest remnant of northeastern Brazil. Floristic and environmental variations were accessed on ten plots of 10 × 20 m. We performed cluster analyses, based on Bray-Curtis dissimilarity index to establish the floristic relationship. The influence of abiotic factors: luminosity, temperature, relative air humidity and relative soil moisture was evaluated from a redundancy analysis. We found 24 species belonging to 20 genera and 12 families. The fern's flora showed high floristic heterogeneity (>75% for most of the plot's associations). The fern's metacommunity was structured along an abiotic gradient modulated by temperature, luminosity, and relative soil moisture.

Platelet-activating factor (PAF) receptor as a promising target for cancer cell repopulation after radiotherapy.

A major drawback of radiotherapy is the accelerated growth of the surviving tumor cells. Radiotherapy generates a variety of lipids that bind to the receptor for platelet-activating factor, expressed by cells in the tumor microenvironment. In the present study, using the TC-1 tumor cell line, we found that irradiation induced a twofold increase in receptor expression and generated agonists of receptor. Irradiated cells induced a 20-fold increase in live TC-1 proliferation in vitro. Furthermore, subcutaneous co-injection of irradiated TC-1 cells with TC-1 expressing luciferase (TC-1 fluc+) markedly increased TC-1 fluc+ proliferation in a receptor-dependent way. Moreover we used a human carcinoma cell line not expressing the PAF receptor (KBM) and the same cell transfected with the receptor gene (KBP). Following co-injection of live KBP cells with irradiated KBM in RAG mice, the tumor growth was significantly increased compared with tumor formed following co-injection of live KBM with irradiated KBM. This tumor cell repopulation correlated with increased infiltration of tumor-promoting macrophages (CD206+). We propose that receptor represents a possible target for improving the efficacy of radiotherapy through inhibition of tumor repopulation.

Computational speed-up with a single qudit.

Quantum algorithms are known for providing more efficient solutions to certain computational tasks than any corresponding classical algorithm. Here we show that a single qudit is sufficient to implement an oracle based quantum algorithm, which can solve a black-box problem faster than any classical algorithm. For 2d permutation functions defined on a set of d elements, deciding whether a given permutation is even or odd, requires evaluation of the function for at least two elements. We demonstrate that a quantum circuit with a single qudit can determine the parity of the permutation with only one evaluation of the function. Our algorithm provides an example for quantum computation without entanglement since it makes use of the pure state of a qudit. We also present an experimental realization of the proposed quantum algorithm with a quadrupolar nuclear magnetic resonance using a single four-level quantum system, i.e., a ququart.

Cloning, characterization and analysis of the 5' regulatory region of zebrafish xpd gene.

The gene XPD/ERCC2 encodes an ATP-dependent 5'-3' helicase of 760 amino acids. There are few transcription factors known to be involved in the regulation of XPD, and these include the hypoxia-inducible factor-1α (HIF-1α), p53, hepatitis B virus x protein (HBx) and specificity protein 1 (Sp1). To identify functional elements of xpd gene in fish we employed a comparative genomic approach. In our in silico attempt to identify cis-regulatory transcription factor binding sites (TFBSs) conserved among the xpd promoter sequences from five available fish species, we verified that in some cases the spatial disposition of the putative TFBSs was not maintained, but they were present in all the sequences, allowing the prediction of conserved regulatory elements within the promoter sequences analysed. We also investigated the transcriptional regulation of the zebrafish xpd gene. Our in vitro transient transfection-reporter analysis identified a region in the zebrafish xpd gene responsible for xpd regulation, along with regulatory regions that inhibit the activity of this promoter in somatic cells. Moreover, we found two p53 binding sites in the xpd promoter and upon co-transfection assays we observed a repression due to p53. This provides the first identification and characterization of promoter regions that regulate the transcription of the zebrafish xpd gene, and offers insights into the regulation of this gene by p53. Together, these studies further support the utility of comparative genomics to uncover gene regulatory sequences based on evolutionary conservation and provide the basic information to explore and better understand the regulation and expression of XPD.

MiR-29a is an enhancer of mineral deposition in bone-derived systems.

MicroRNAs (miRNAs) provide a mechanism for fine-tuning of intricate cellular processes through post-transcriptional regulation. Emerging evidences indicate that miRNAs play key roles in regulation of osteogenesis. The miR-29 family was previously implicated in mammalian osteoblast differentiation by targeting extracellular matrix molecules and modulating Wnt signaling. Nevertheless, the function of miR-29 in bone formation and homeostasis is not completely understood. Here, we provide novel insights into the biological effect of miR-29a overexpression in a mineralogenic cell system (ABSa15). MiR-29a gain-of-function resulted in significant increase of extracellular matrix mineralization, probably due to accelerated differentiation. We also demonstrated for the first time that miR-29a induced ß-catenin protein levels, implying a stimulation of canonical Wnt signaling. Our data also suggests that SPARC is a conserved target of miR-29a, and may contribute to the phenotype observed in ABSa15 cells. Finally, we provide evidences for miR-29a conservation throughout evolution based on sequence homology, synteny analysis and expression patterns. Concluding, miR-29a is a key player in osteogenic differentiation, leading to increased mineralization in vitro, and this function seems to be conserved throughout vertebrate evolution by interaction with canonical Wnt signaling and conservation of targets.

Evolutionary conservation of TFIIH subunits: implications for the use of zebrafish as a model to study TFIIH function and regulation.

Transcriptional factor IIH (TFIIH) is involved in cell cycle regulation, nucleotide excision repair, and gene transcription. Mutations in three of its subunits, XPB, XPD, and TTDA, lead to human recessive genetic disorders such as trichothiodystrophy and xeroderma pigmentosum, the latter of which is sometimes associated with Cockayne's syndrome. In the present study, we investigate the sequence conservation of TFIIH subunits among several teleost fish species and compare their characteristics and putative regulation by transcription factors to those of human and zebrafish. We report the following findings: (i) comparisons among protein sequences revealed a high sequence identity for each TFIIH subunit analysed; (ii) among transcription factors identified as putative regulators, OCT1 and AP1 have the highest binding-site frequencies in the promoters of TFIIH genes, and (iii) TFIIH genes have alternatively spliced isoforms. Finally, we compared the protein primary structure in human and zebrafish of XPD and XPB - two important ATP-dependent helicases that catalyse the unwinding of the DNA duplex at promoters during transcription - highlighting the conservation of domain regions such as the helicase domains. Our study suggests that zebrafish, a widely used model for many human diseases, could also act as an important model to study the function of TFIIH complex in repair and transcription regulation in humans.

Cryptic B cell response to renal transplantation.

Transplantation reliably evokes allo-specific B cell and T cell responses in mice. Yet, human recipients of kidney transplants with normal function usually exhibit little or no antibody specific for the transplant donor during the early weeks and months after transplantation. Indeed, the absence of antidonor antibodies is taken to reflect effective immunosuppressive therapy and to predict a favorable outcome. Whether the absence of donor-specific antibodies reflects absence of a B cell response to the donor, tolerance to the donor or immunity masked by binding of donor-specific antibodies to the graft is not known. To distinguish between these possibilities, we devised a novel ELISPOT, using cultured donor, recipient and third-party fibroblasts as targets. We enumerated donor-specific antibody-secreting cells in the blood of nine renal allograft recipients with normal kidney function before and after transplantation. Although none of the nine subjects had detectable donor-specific antibodies before or after transplantation, all exhibited increases in the frequency of donor-specific antibody-secreting cells eight weeks after transplantation. The responses were directed against the donor HLA-class I antigens. The increase in frequency of donor-specific antibody-secreting cells after renal transplantation indicates that B cells respond specifically to the transplant donor more often than previously thought.

Observation of environment-induced double sudden transitions in geometric quantum correlations.

Correlations in quantum systems exhibit a rich phenomenology under the effect of various sources of noise. We investigate theoretically and experimentally the dynamics of quantum correlations and their classical counterparts in two nuclear magnetic resonance setups, as measured by geometric quantifiers based on trace norm. We consider two-qubit systems prepared in Bell diagonal states, and perform the experiments in real decohering environments resulting from Markovian local noise which preserves the Bell diagonal form of the states. We then report the first observation of environment-induced double sudden transitions in the geometric quantum correlations, a genuinely nonclassical effect not observable in classical correlations. The evolution of classical correlations in our physical implementation reveals in turn the finite-time relaxation to a pointer basis under nondissipative decoherence, which we characterize geometrically in full analogy with predictions based on entropic measures.

Measuring bipartite quantum correlations of an unknown state.

We report the experimental measurement of bipartite quantum correlations of an unknown two-qubit state. Using a liquid state Nuclear Magnetic Resonance setup and employing geometric discord, we evaluate the quantum correlations of a state without resorting to prior knowledge of its density matrix. The method is applicable to any 2 ⊗ d system and provides, in terms of number of measurements required, an advantage over full state tomography scaling with the dimension d of the unmeasured subsystem. The negativity of quantumness is measured as well for reference. We also observe the phenomenon of sudden transition of quantum correlations when local phase and amplitude damping channels are applied to the state.

Inhibition of autonomic storm by epidural anesthesia does not influence cardiac inflammatory response after brain death in rats.

BACKGROUND: After brain death (BD) donors usually experience cardiac dysfunction, which is responsible for a considerable number of unused organs. Causes of this cardiac dysfunction are not fully understood. Some authors argue that autonomic storm with severe hemodynamic instability leads to inflammatory activation and myocardial dysfunction. OBJECTIVES: To investigate the hypothesis that thoracic epidural anesthesia blocks autonomic storm and improves graft condition by reducing the inflammatory response. METHODS: Twenty-eight male Wistar rats (250-350 g) allocated to four groups received saline or bupivacaine via an epidural catheter at various times in relation to brain-death induction. Brain death was induced by a sudden increase in intracranial pressure by rapid inflation of a ballon catheter in the extradural space. Blood gases, electrolytes, and lactate analyses were performed at time zero, and 3 and 6 hours. Blood leukocytes were counted at 0 and 6 hours. After 6 hours of BD, we performed euthanasia to measure vascular adhesion molecule (VCAM)-1, intracellular adhesion molecule (ICAM)-1, interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, Bcl-2 and caspase-3 on cardiac tissue. RESULTS: Thoracic epidural anesthesia was effective to block the autonomic storm with a significant difference in mean arterial pressure between the untreated (saline) and the bupivacaine group before BD (P < .05). However, no significant difference was observed for the expressions of VCAM-1, ICAM-1, TNF-α, IL-1ß, Bcl-2, and caspase-3 (P > .05). CONCLUSION: Autonomic storm did not seem to be responsible for the inflammatory changes associated with BD; thoracic epidural anesthesia did not modify the expression of inflammatory mediators although it effectively blocked the autonomic storm.

Molecular cloning and expression analysis of xpd from zebrafish (Danio rerio).

The XPD gene, located in human chromosome 19, encodes one of the two helicase components of transcriptional factor IIH (TFIIH), a ten-subunit, multifunctional complex that is essential for multiple processes, including basal transcription initiation and DNA damage repair [1, 2]. Alterations in XPD resulting in defective TFIIH function are associated with UV-sensitive disorders including Xeroderma pigmentosum, Cockayne syndrome, and Trichothiodystrophy (TTD) [3, 4]. TTD mice exhibit many symptoms of premature aging, including osteoporosis, kyphosis and osteosclerosis [5]. This fact has triggered our interest in analyzing XPD involvement in bone biology using zebrafish as model organism. Although orthologs of xpd are present in all species analyzed, no specific data on its gene structure, regulation or function exists at this time in any fish system. In this study we isolated the zebrafish cDNA encoding xpd, and examined its spatial-temporal expression during early development as well as its tissue distribution in adult zebrafish. Only one gene was identified in zebrafish and its sequence analysis showed a molecular structure with 23 coding exons similar to other species. The amino acid sequences were also found to be largely conserved among all species analyzed, suggesting function maintenance throughout evolution. Gene expression analysis in different zebrafish tissues by qPCR showed xpd expression in all tissues examined with the highest expression in branchial arches. Analysis of xpd expression in zebrafish embryos showed maternal inheritance and presence of xpd transcripts in all developmental stages analyzed suggesting its implication in early zebrafish larval development.

Edge effects on fern community in an Atlantic Forest remnant of Rio Formoso, PE, Brazil.

We have investigated how edge effects influence the fern community of Jaguarão Forest (08º 35' 49" S and 35º 15' 39" W), located in the district of Rio Formoso, Pernambuco, Brazil. A comparative analysis was made of the interior and edge of the fragment of forest, regarding the richness, abundance and diversity of ferns in the two areas. Six plots of 10 × 20 m were chosen, three in each area. A total of 381 ferns were recorded, which were distributed among 25 species, 17 genera and 12 families. The two areas (edge and interior) were found to differ, with distinct relative air humidities and temperatures (p = 0.00254 and p = 0.00019, respectively). The interior showed higher diversity (t = 7.251 and p = 0.018) and richness (t = 6.379 and p = 0.023) than the edge area, but the same abundance (t = 1.728; p = 0.226) as the edge. Regarding the composition of the flora, it was clear that the interior is a habitat completely distinct from the edge with regard to the fern community, given that only one species, Adiantum petiolatum Desv., was common to both environments. It was concluded that the edge effect causes a decrease in richness and abundance of the fern species found in Jaguarão Forest, where the more sensitive species are being replaced by species that are tolerant to the disturbance caused by the creation of an edge.

Fire effects on the population structure of Zanthoxylum rhoifolium Lam (Rutaceae) in a Brazilian savanna.

Since cerrado fires may impede the growth of seedlings into trees, they may shape the population of woody species. In this study, we assessed the effects of a severe fire on the population structure and spatial distribution of Zanthoxylum rhoifolium, a widespread cerrado tree. We were interested to know the importance of the resprouting and sexual reproduction in regenerating the population. The study area had been for about six years protected from fire, before a severe fire at the end of the dry season in 2006. We sampled and measured all individuals of Z. rhoifolium found in 80 plots of 25 m(2). We found 149 individuals before the fire and 112 after the fire, of which 77 were resprouts from burned seedlings and saplings. We did not find significant differences between the population structure before and after the fire. The spatial distribution of the population remained clumped after the fire. Thus, the Z. rhoifolium population was very resilient to a severe fire. We did not find any new seedlings. As a consequence, resprouting seems to be more important than sexual reproduction in promptly regenerating the Z. rhoifolium populations.

Phylogenetic overdispersion of plant species in southern Brazilian savannas.

Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.

Fire effects on the population structure of Zanthoxylum rhoifolium Lam (Rutaceae) in a Brazilian savanna / Efeitos do fogo na estrutura da população de Zanthoxylum rhoifolium Lam (Rutaceae) em uma savana brasileira

Since cerrado fires may impede the growth of seedlings into trees, they may shape the population of woody species. In this study, we assessed the effects of a severe fire on the population structure and spatial distribution of Zanthoxylum rhoifolium, a widespread cerrado tree. We were interested to know the importance of the resprouting and sexual reproduction in regenerating the population. The study area had been for about six years protected from fire, before a severe fire at the end of the dry season in 2006. We sampled and measured all individuals of Z. rhoifolium found in 80 plots of 25 m². We found 149 individuals before the fire and 112 after the fire, of which 77 were resprouts from burned seedlings and saplings. We did not find significant differences between the population structure before and after the fire. The spatial distribution of the population remained clumped after the fire. Thus, the Z. rhoifolium population was very resilient to a severe fire. We did not find any new seedlings. As a consequence, resprouting seems to be more important than sexual reproduction in promptly regenerating the Z. rhoifolium populations.

Uma vez que as queimadas no cerrado podem impedir o crescimento de plântulas, elas podem moldar a população de espécies arbóreas. Neste estudo, avaliamos os efeitos de uma queimada severa na estrutura e na distribuição espacial da população de Zanthoxylum rhoifolium, uma espécie de árvore comum no cerrado. O objetivo era saber a importância relativa do rebrotamento e da reprodução sexuada na regeneração da população. A área de estudo, há aproximadamente seis anos sem queimar, sofreu uma queimada severa no final da estação seca de 2006. Amostramos todos os indivíduos de Z. rhoifolium encontrados em 80 parcelas de 25 m². Encontramos 149 indivíduos antes do fogo e 112 depois dele, dos quais 77 eram rebrotas de plântulas e jovens queimados. Não encontramos diferenças significativas entre a estrutura da população antes e após o fogo. A distribuição espacial da população permaneceu agregada após a queimada. Portanto, a população de Z. rhoifolium foi resiliente ao fogo. Não foi encontrada nenhuma nova plântula. Consequentemente, o rebrotamento parece ser mais importante que a reprodução sexuada na regeneração imediata das populações de Z. rhoifolium.

Phylogenetic overdispersion of plant species in southern Brazilian savannas / Dispersão filogenética de espécies de plantas em savanas no Sudeste do Brasil

Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.

Comunidades ecológicas resultam não somente de processos ecológicos atuais, como a competição e os filtros ambientais, mas também de processos evolutivos passados e contínuos. Com base nessas premissas, podemos inferir mecanismos de coexistência contemporânea a partir das relações filogenéticas das espécies em uma comunidade. Estudamos a estrutura filogenética das comunidades de plantas de quatro áreas de cerrado, no Sudeste do Brasil. Calculamos duas medidas das distâncias filogenéticas das espécies amostradas. Estimamos a estrutura filogenética comparando suas distâncias observadas com a distribuição dessas distâncias em comunidades nulas. Obtivemos comunidades nulas aleatorizando as relações filogenéticas do banco regional de espécies. Encontramos uma dispersão filogenética de espécies de cerrado. Há várias explicações para essa dispersão, dependendo da história filogenética dos traços e das interações ecológicas contemporâneas. Entretanto, com base nos modelos de coexistência entre árvores e gramíneas, nas forças ecológicas dependentes da densidade e na história evolutiva da flora do cerrado, argumentamos que a dispersão filogenética das espécies do cerrado é predominantemente devida às interações competitivas, aos ataques de herbívoros e patógenos e à especiação ecológica. Estudos futuros precisarão incluir informações sobre a história filogenética dos traços das plantas.

Species convergence into life-forms in a hyperseasonal cerrado in central Brazil.

Whether the functional structure of ecological communities is deterministic or historically contingent is still quite controversial. However, recent experimental tests did not find effects of species composition variation on trait convergence and therefore the environmental constraints should play the major role on community convergence into functional groups. Seasonal cerrados are characterized by a sharp seasonality, in which the water shortage defines the community functioning. Hyperseasonal cerrados experience additionally waterlogging in the rainy season. Here, we asked whether waterlogging modifies species convergences into life-forms in a hyperseasonal cerrado. We studied a hyperseasonal cerrado, comparing it with a nearby seasonal cerrado, never waterlogged, in Emas National Park, central Brazil. In each area, we sampled all vascular plants by placing 40 plots of 1 m(2) plots in four surveys. We analyzed the species convergences into life-forms in both cerrados using the Raunkiaer's life-form spectrum and the index of divergence from species to life-form diversity (IDD). The overall life-form spectra and IDDs were not different, indicating that waterlogging did not affect the composition of functional groups in the hyperseasonal cerrado. However, there was a seasonal variation in IDD values only in the hyperseasonal cerrado. As long as we did not find a seasonal variation in life-form diversity, the seasonal variation of convergence into life-forms in the hyperseasonal cerrado was a consequence of the seasonal variation of species diversity. Because of high functional redundancy of cerrado plants, waterlogging promoted a floristic replacement without major changes in functional groups. Thus, waterlogging in the hyperseasonal cerrado promoted seasonal changes in species convergence into life-forms by reducing species diversity.