Concomitant osmotic and chaotropicity-induced stresses in Aspergillus wentii: compatible solutes determine the biotic window

Whereas osmotic stress response induced by solutes has been well-characterized in fungi, less is known about the other activities of environmentally ubiquitous substances. The latest methodologies to define, identify and quantify chaotropicity, i.e. substance-induced destabilization of macromolecular systems, now enable new insights into microbial stress biology (Cray et al. in Curr Opin Biotechnol 33:228–259, 2015a, doi:10.​1016/​j.​copbio.​2015.​02.​010; Ball and Hallsworth in Phys Chem Chem Phys 17:8297–8305, 2015, doi:10.​1039/​C4CP04564E; Cray et al. in Environ Microbiol 15:287–296, 2013a, doi:10.​1111/​1462-2920.​12018). We used Aspergillus wentii, a paradigm for extreme solute-tolerant fungal xerophiles, alongside yeast cell and enzyme models (Saccharomyces cerevisiae and glucose-6-phosphate dehydrogenase) and an agar-gelation assay, to determine growth-rate inhibition, intracellular compatible solutes, cell turgor, inhibition of enzyme activity, substrate water activity, and stressor chaotropicity for 12 chemically diverse solutes. These stressors were found to be: (i) osmotically active (and typically macromolecule-stabilizing kosmotropes), including NaCl and sorbitol; (ii) weakly to moderately chaotropic and non-osmotic, these were ethanol, urea, ethylene glycol; (iii) highly chaotropic and osmotically active, i.e. NH4NO3, MgCl2, guanidine hydrochloride, and CaCl2; or (iv) inhibitory due primarily to low water activity, i.e. glycerol. At ≤0.974 water activity, Aspergillus cultured on osmotically active stressors accumulated low-M r polyols to ≥100 mg g dry weight−1. Lower-M r polyols (i.e. glycerol, erythritol and arabitol) were shown to be more effective for osmotic adjustment; for higher-M r polyols such as mannitol, and the disaccharide trehalose, water-activity values for saturated solutions are too high to be effective; i.e. 0.978 and 0.970 (25 ºC). The highly chaotropic, osmotically active substances exhibited a stressful level of chaotropicity at physiologically relevant concentrations (20.0–85.7 kJ kg−1). We hypothesized that the kosmotropicity of compatible solutes can neutralize chaotropicity, and tested this via in-vitro agar-gelation assays for the model chaotropes urea, NH4NO3, phenol and MgCl2. Of the kosmotropic compatible solutes, the most-effective protectants were trimethylamine oxide and betaine; but proline, dimethyl sulfoxide, sorbitol, and trehalose were also effective, depending on the chaotrope. Glycerol, by contrast (a chaotropic compatible solute used as a negative control) was relatively ineffective. The kosmotropic activity of compatible solutes is discussed as one mechanism by which these substances can mitigate the activities of chaotropic stressors in vivo. Collectively, these data demonstrate that some substances concomitantly induce chaotropicity-mediated and osmotic stresses, and that compatible solutes ultimately define the biotic window for fungal growth and metabolism. The findings have implications for the validity of ecophysiological classifications such as ‘halophile’ and ‘polyextremophile’; potential contamination of life-support systems used for space exploration; and control of mycotoxigenic fungi in the food-supply chain.

Calluna vulgaris root cells show increased capacity for amino acid uptake when colonized with the mycorrhizal fungus Hymenoscyphus ericae

Ericoid mycorrhizas are believed to improve N nutrition of many ericaceous plant species that typically occur in habitats with impoverished nutrient status, by releasing amino acids from organic N forms. Despite the ubiquity of mycorrhizal formation the mechanisms and regulation of nutrient transport in mycorrhizal associations are poorly understood. We used an electrophysiological approach to study how amino acid transport characteristics of Calluna vulgaris were affected by colonization with the ericoid mycorrhiza fungus Hymenoscyphus ericae. Both the V_max and K_m parameters of amino acid uptake were affected by fungal colonization in a manner consistent with an increased availability of amino acid to the plant. The ecophysiological significance of altered amino acid transport in colonized root cells of C. vulgaris is discussed. © New Phytologist (2002).

Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

Fungi of the genus Aspergillus are widespread in the environment. Some Aspergillus species, most commonly Aspergillus fumigatus, may lead to a variety of allergic reactions and life-threatening systemic infections in humans. Invasive aspergillosis occurs primarily in patients with severe immunodeficiency, and has dramatically increased in recent years. There are several factors at play that contribute to aspergillosis, including both fungus and host-related factors such as strain virulence and host pulmonary structure/immune status, respectively. The environmental tenacity of Aspergilllus, its dominance in diverse microbial communities/habitats, and its ability to navigate the ecophysiological and biophysical challenges of host infection are attributable, in large part, to a robust stress-tolerance biology and exceptional capacity to generate cell-available energy. Aspects of its stress metabolism, ecology, interactions with diverse animal hosts, clinical presentations and treatment regimens have been well-studied over the past years. Here, we synthesize these findings in relation to the way in which some Aspergillus species have become successful opportunistic pathogens of human- and other animal hosts. We focus on the biophysical capabilities of Aspergillus pathogens, key aspects of their ecophysiology and the flexibility to undergo a sexual cycle or form cryptic species. Additionally, recent advances in diagnosis of the disease are discussed as well as implications in relation to questions that have yet to be resolved.

Effect of temperature and prey in the biology of Scymnus subvillosus (Goeze) (Coleoptera: Coccinellidae)

Dissertação de Mestrado, Biotecnologia em Controlo Biológico, 18 de Dezembro de 2013, Universidade dos Açores.

A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite

A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite: Chitin synthase, the enzyme responsible for the synthesis of chitin in fungal cell wall was extracted from young hyphae of Choanephora cucurbitarum and Phascolomyces articulosus, susceptible and resistant hosts, respectively, to the mycoparasite, Piptocephalis virginiana. Crude enzyme was identified and characterized by measuring the incorporation of the substrate [14C]-UDP-N-acetylglucosamine, into chitin. Most activity occurred in mixed membrane fraction. Inhibition of activity with Polyoxin D and activation with proteases, N-acetyl-glucosamine and magnesium and other ions was observed. Properties of the crude enzyme preparation such as cofactor requirement, Vmax , apparent Km value for UDP-GlcNAc, inhibition by Polyoxin D, response to pH and to temperature, and stability at 4°C were determined. Enzyme activity from both fungi displayed basically the same features as the corresponding enzymes reported from other mucoraceous fungi. However, the two preparations from P. articulosus and C. cucurbitarum differed from each other in their expressed activity (i.e., the preparations from ~ articulosus exhibited higher latency and higher specific chitin synthase activity than the corresponding preparations from ~ cucurbitarum). Trypsin was effective in activation only over a narrow concentration range. Acid protease was the most effec.tive activator. En.dogenous protease estimation indicated higher protease activity in C. cucurbitarum than in P. articulosus. The suggestion is made that regulation of chitin synthase activities may be related to host resistance in the mycoparasitic system.

Sedimentology of the Sixteen Mile Creek Lagoon, Niagara Peninsula, Ontario, Canada

The effec s of relative water level changes in Lake Ontario were detected in the ysical, chemical and biological characteristics of the sediments of the Fifteen, Sixteen and Twenty Mile Creek lagoonal complexes. Regional environmental changes have occurred resulting in the following sequence of sediments in the three lagoons and marsh. From the base up they are; (I) Till,(2) Pink Clay, (3) Bottom Sand, (4) Gyttja, (5) Orange Sandy Silt, (6) Brown Clay and (7) Gray Clay. The till was only encountered in the marsh and channel; however, it is presumed to occur throughout the entire area. The presence of diatoms and sponge spicules, the vertical and ongitudinal uniformity of the sediment and the stratigr ic position of the Pink Clay indicate that it has a glacial or post-glacial lacustrine origin. Overl ng the Pink Clay or Till is a clayey, silty sand to gravel. The downstream fining and unsorted nature of this material indicate that it has a fluvial/deltaic origin. Water levels began rising in the lagoon 3,250 years ago resulting in the deposition of the Gyttja, a brown, organic-rich silty clay probably deposited in a shallow, stagnant environment as shown by the presence of pyrite in the organic material and relatively high proportions of benthic diatoms and grass pollen. Increase in the rate of deposition of the Gyttja on Twenty Mile Creek and a decrease in the same unit on Sixteen Mile Creek is possibly the result of a capture of the Sixteen Mile Creek by the Twenty Mile Creek. The rise in lake level responsible for the onset and transgression of this III unit may have been produced by isostatic rebound; however, the deposition also corresponds closely to a drop in the level of Lake Huron and increased flow through the lower lakes. The o ange Sandy Silt, present only in the marsh, appears to be a buried soil horizon as shown by oxidized roots, and may be the upland equivalant to the Gyttja. Additional deepening resulted in the deposition of Brown Clay, a unit which only occurs at the lakeward end of the three lagoons. The decrease in grass pollen and the relatively high proportion of pelagic diatoms are evidence for this. The deepening may be the result of isostatic rebound; however, the onset of its deposition at 1640 years B.P. is synchronous in the three lagoons and corresponds to the end of the subAtlantic climatic episode. The effects of the climatic change in southern Ontario is uncertain. Average deposition rates of the Brown Clay are similar to those in the upper Gyttja on Sixteen Mile Creek; however, Twenty Mile Creek shows lower rates of the Brown Clay than those in the upper Gyttja. The Gray Clay covers the present bottom of the three lagoons and also occurs in the marsh It is inter1aminated wi sand in the channels. Increases in the rates of deposi ion, high concentrations of Ca and Zn, an Ambrosia rise, and an increase in bioturbation possibly due to the activities of the carp, indicate th this unit is a recent deposit resulting from the activities of man.

A comparative analysis of two methods for the calculation of electric-field-induced perturbations to molecular vibration

Two common methods of accounting for electric-field-induced perturbations to molecular vibration are analyzed and compared. The first method is based on a perturbation-theoretic treatment and the second on a finite-field treatment. The relationship between the two, which is not immediately apparent, is made by developing an algebraic formalism for the latter. Some of the higher-order terms in this development are documented here for the first time. As well as considering vibrational dipole polarizabilities and hyperpolarizabilities, we also make mention of the vibrational Stark effec

Estudi taxonòmic i ecofisiològic dels membres de la família faucheaceae (Rhodymeniales, Rhodophyta) de la Península Ibèrica i de les Illes Balears

L'objectiu d'aquesta tesi doctoral ha estat estudiar a nivell taxonòmic i ecofisiològic les espècies de la família Faucheaceae (Rhodymeniales, Rhodophyta) presents a la península Ibèrica i a les illes Balears: Fauchea repens (C. Agardh) Montagne i Bory in Montagne, Gloiocladia furcata (C. Agardh) J. Agardh i Gloiocladia microspora (Bornet ex Rodríguez y Femenías) Sánchez i Rodríguez-Prieto, comb. nov. L'estudi taxonòmic es va realitzar a partir de mostres recol·lectades al llarg de la costa de la península Ibérica i de les illes Balears, amb la revisió dels exemplars conservats en els herbaris de diferents universitats espanyoles i dels exemplars tipus localitzats a l'herbari de C. Agardh i al de J.J. Rodríguez y Femenías. Així doncs, amb aquest treball es van completar les dades ja existents quant a la morfologia, l'estructura vegetativa i els tetrasporòfits de les tres espècies i es van aportar dades inèdites pel què fa a les estructures reproductores masculines de Fauchea repens, les estructures reproductores femenines i estadis de postfertilització de F. repens, G. furcata i G. microspora comb. nov. Paral·lelament es va detallar la corologia, l'hàbitat i la fenologia de les tres espècies. De l'estudi de F. repens i G. furcata, espècies tipus dels seus gèneres i, en el cas de la primera també de la família, es proposa una correcció de la descripció original de la família Faucheaceae I.M. Strachan, G.W. Saunders & Kraft, així com una nova combinació Gloiocladia microspora comb. nov. per l'espècie anomenada fins aquest estudi Fauchea microspora Bornet ex Rodríguez y Femenías. S'aporta també una iconografia original de dibuixos i fotografies, i una clau de determinació dels tàxons estudiats. Quant a l'estudi ecofisiològic, es van realitzar una sèrie d'experiments de laboratori per tal de determinar els requeriments de llum, temperatura i fotoperíode per el creixement i supervivència de les tres espècies. Així doncs, es van aportar dades inèdites pel què fa al cultiu in vitro de Fauchea repens, Gloiocladia furcata i Gloiocladia microspora comb. nov., que ens van permetre explicar la distribució batimètrica i geogràfica de les tres espècies.

Representações sociais que professores constroem sobre a aprendizagem de alunos numa escola pública inclusiva : um cenário de contradições

Esta dissertação de Mestrado tem por objetivo investigar as representações dos profes-sores sobre a aprendizagem de alunos com deficiência no cotidiano escolar de uma escola inclusiva; as concepções, expectativas, avanços e impasses que permeiam a atuação dos edu-cadores que desenvolvem seu trabalho numa escola pública inclusiva. A base teórica desta pesquisa esteve respaldada na teoria das Representações Sociais e em autores como, Durkheim (1987), Moscovici (1978), Mantoan (2005), Maroja (1998), Emygdio (2011), Sas-saki (1997), Nóvoa (1992), entre outros que ao longo de vários anos vem se preocupando em discutir as representações sociais bem como a temática da inclusão no contexto escolar. A amostra deste estudo foi constituída por oito professoras que trabalham na escola campo de pesquisa, no município de João Pessoa. A coleta de dados foi realizada a partir dos instrumentos de pesquisa como, a observação, o diário de campo, o relato de experiência, a exposição e análise de um filme e a entrevista semi estruturada. As respostas obtidas mostraram que para realizar a educação inclusiva faz-se necessário refletir sobre o conceito, o preconceito, as crenças e concepções acerca da inclusão escolar. Constatamos o desejo de maiores condições de trabalho, no que tange a capacitação, mais recursos pedagógicos e a efetiva participação da família, no processo escolar. Observa-mos ainda, que é impossível trabalhar numa escola inclusiva cultivando o preconceito, a indi-vidualidade, a intolerância e a insensibilidade. Ficou evidente a necessidade de maiores discussões, estudos, ações, espaços adequados para o atendimento especializado e envolvimento de todos os atores da educação para que se efetive de forma satisfatória o processo de inclusão escolar.

Accumulated metal speciation in earthworm populations with multi-generational exposure to metalliferous soils: cell fractionation and high energy synchrotron analyses

Predicting metal bioaccumulation and toxicity in soil organisms is complicated by site-specific biotic and abiotic parameters. In this study we exploited tissue fractionation and digestion techniques, combined with X-ray absorption spectroscopy (XAS), to investigate the whole-body and subcellular distributions, ligand affinities, and coordination chemistry of accumulated Pb and Zn in field populations of the epigeic earthworm Lumbricus rubellus inhabiting three contrasting metalliferous and two unpolluted soils. Our main findings were (i) earthworms were resident in soils with concentrations of Pb and Zn ranging from 1200 to 27 000 mg kg(-1) and 200 to 34 000 mg kg(-1), respectively; (ii) Pb and Zn primarily accumulated in the posterior alimentary canal in nonsoluble subcellular fractions of earthworms; (iii) site-specific differences in the tissue and subcellular partitioning profiles of populations were observed, with earthworms from a calcareous site partitioning proportionally more Pb to their anterior body segments and Zn to the chloragosome-rich subcellular fraction than their acidic-soil inhabiting counterparts; (iv) XAS indicated that the interpopulation differences in metal partitioning between organs were not accompanied by qualitative differences in ligand-binding speciation, because crystalline phosphate-containing pyromorphite was a predominant chemical species in the whole-worm tissues of all mine soil residents. Differences in metal (Pb, Zn) partitioning at both organ and cellular levels displayed by field populations with protracted histories of metal exposures may reflect their innate ecophysiological responses to essential edaphic variables, such as Ca2+ status. These observations are highly significant in the challenging exercise of interpreting holistic biomarker data delivered by "omic" technologies.

The influence of hilly terrain on canopy-atmosphere carbon dioxide exchange

Topography influences many aspects of forest-atmosphere carbon exchange; yet only a small number of studies have considered the role of topography on the structure of turbulence within and above vegetation and its effect on canopy photosynthesis and the measurement of net ecosystem exchange of CO2 (N-ee) using flux towers. Here, we focus on the interplay between radiative transfer, flow dynamics for neutral stratification, and ecophysiological controls on CO2 sources and sinks within a canopy on a gentle cosine hill. We examine how topography alters the forest-atmosphere CO2 exchange rate when compared to uniform flat terrain using a newly developed first-order closure model that explicitly accounts for the flow dynamics, radiative transfer, and nonlinear eco physiological processes within a plant canopy. We show that variation in radiation and airflow due to topography causes only a minor departure in horizontally averaged and vertically integrated photosynthesis from their flat terrain values. However, topography perturbs the airflow and concentration fields in and above plant canopies, leading to significant horizontal and vertical advection of CO2. Advection terms in the conservation equation may be neglected in flow over homogeneous, flat terrain, and then N-ee = F-c, the vertical turbulent flux of CO2. Model results suggest that vertical and horizontal advection terms are generally of opposite sign and of the same order as the biological sources and sinks. We show that, close to the hilltop, F-c departs by a factor of three compared to its flat terrain counterpart and that the horizontally averaged F-c-at canopy top differs by more than 20% compared to the flat-terrain case.

Simulated variations in atmospheric CO2 over a Wisconsin forest using a coupled ecosystem-atmosphere model

Ecosystem fluxes of energy, water, and CO2 result in spatial and temporal variations in atmospheric properties. In principle, these variations can be used to quantify the fluxes through inverse modelling of atmospheric transport, and can improve the understanding of processes and falsifiability of models. We investigated the influence of ecosystem fluxes on atmospheric CO2 in the vicinity of the WLEF-TV tower in Wisconsin using an ecophysiological model (Simple Biosphere, SiB2) coupled to an atmospheric model (Regional Atmospheric Modelling System). Model parameters were specified from satellite imagery and soil texture data. In a companion paper, simulated fluxes in the immediate tower vicinity have been compared to eddy covariance fluxes measured at the tower, with meteorology specified from tower sensors. Results were encouraging with respect to the ability of the model to capture observed diurnal cycles of fluxes. Here, the effects of fluxes in the tower footprint were also investigated by coupling SiB2 to a high-resolution atmospheric simulation, so that the model physiology could affect the meteorological environment. These experiments were successful in reproducing observed fluxes and concentration gradients during the day and at night, but revealed problems during transitions at sunrise and sunset that appear to be related to the canopy radiation parameterization in SiB2.

Global vegetation and terrestrial carbon cycle changes after the last ice age

•In current models, the ecophysiological effects of CO2 create both woody thickening and terrestrial carbon uptake, as observed now, and forest cover and terrestrial carbon storage increases that took place after the last glacial maximum (LGM). Here, we aimed to assess the realism of modelled vegetation and carbon storage changes between LGM and the pre-industrial Holocene (PIH). •We applied Land Processes and eXchanges (LPX), a dynamic global vegetation model (DGVM), with lowered CO2 and LGM climate anomalies from the Palaeoclimate Modelling Intercomparison Project (PMIP II), and compared the model results with palaeodata. •Modelled global gross primary production was reduced by 27–36% and carbon storage by 550–694 Pg C compared with PIH. Comparable reductions have been estimated from stable isotopes. The modelled areal reduction of forests is broadly consistent with pollen records. Despite reduced productivity and biomass, tropical forests accounted for a greater proportion of modelled land carbon storage at LGM (28–32%) than at PIH (25%). •The agreement between palaeodata and model results for LGM is consistent with the hypothesis that the ecophysiological effects of CO2 influence tree–grass competition and vegetation productivity, and suggests that these effects are also at work today.

Avaliação da toxicidade de florações naturais e de cultura de cianobactérias: efeitos sobre Ceriodaphnia silvestri (Crustacea, Cladocera)

The incidence of toxic cyanobacterial blooms is one of the important consequences of eutrophication in aquatic ecosystems. It is a very common phenomenon in reservoirs and shrimp ponds in the State of Rio Grande do Norte (RN), Brazil. Cyanobacterias produce toxins which can affect aquatic organisms and men trough the food chain. Aiming to contribute to the studies of cyanobacterias in RN, we propose: a) to evaluate the toxicity of isolated cyanobacterias in important fresh-water environments; and b) to verify the effects of both natural and cultured blooms occurred in reservoirs for human supply and in the cladoceran Ceriodaphnia silvestrii. This study was carried out using samples of natural blooms occurred between March and October of 2004 in Gargalheiras Dam (08º L e 39º W), in July of 2004 in Armando Ribeiro Gonçalves Dam (06o S e 37o W) and in commercial shrimp ponds (Litopenaeus vannamei) located in fresh-water environments. The samples were collected with plankton net (20µm.) for identification, isolation and obtaining of phytoplanktonic biomass for liophilization and later toxicity bioassays. The toxicity of cultured samples and natural blooms was investigated through bioassays in Swiss mice. Quantification of cyanobacteria in samples was conducted following the Ütermol method, with 300mL samples fixed with lugol. The toxicity test with Ceriodaphnia silvestrii followed ABNT, 2001 recommendations, and were accomplished with natural hepatotoxic bloom s samples and cultured samples of both non-toxic and neurotoxic C. raciborskii. In this test, five newborns, aged between 6 and 24 hours, were exposed to different concentrations (0 a 800 mg.L-1) of crude cyanobacterial extracts during 24 and 48 hours. Three replicates were used per treatment. The pH, temperature and dissolved oxygen at the beginning and after 24 and 48hours from the test were measured. We estimated the CL50 through the Trimmed Spearman-Karber method. The blooms were constituted by Microcystis panniformis, M. aeruginosa, Anabaena circinalis, Cylindrospermopsis raciborskii and Planktothrix agardhii, producers of mycrocistin-LR confirmed with HPLC analysis. Samples of hepatotoxic blooms registered toxinogenic potential for C. silvestrii, with CL50-24h value of 47.48 mg.L-1 and CL5048h of 38.15 mg.L-1 for GARG samples in march/2005; CL50-24h of 113,13 mg.L-1 and CL5048h of 88,24 mg.L-1 for ARG July/2004; CL50-24h of 300.39 mg.L-1 and CL50-48h of 149.89 mg.L-1 for GARG October/2005. For cultured samples, values of CL50-24h and CL50-48h for C. raciborskii toxic strains were 228.05 and 120.28 mg.L-1, respectively. There was no mortality of C. silvestrii during the tests with non-toxic C. raciborskii strain. The toxicity test with C. silvestrii presented good sensitivity degree to cyanotoxins. The toxicity of natural hepatotoxic blooms samples (microcystins) and cultured neurotoxic saxitoxins producer samples analyzed in this study give us strong indications of that toxin s influence on the zooplanktonic community structure in tropical aquatic environments. Eleven cyanobacteria strains were isolated, representing 6 species: Anabaenopsis sp., Cylindrospermopsis raciborskii, Chroococcus sp., Microcystis panniformis, Geitlerinema unigranulatum e Planktothrix agardhii. None presented toxicity in Swiss mice. The strains were catalogued and deposited in the Laboratório de Ecologia e Toxicologia de Organismos Aquáticos (LETMA), in UFRN, and will be utilized in ecotoxicológical and ecophysiological studies, aiming to clarify the causes and control of cyanobacterial blooms in aquatic environments in RN. This state s reservoirs must receive broader attention from the authorities, considering the constant blooms occurring in waters used for human consumption

Structural and functional leaf traits of two Gochnatia species from distinct growth forms in a sclerophyll forest site in Southeastern Brazil

O gênero Gochnatia é comumente encontrado em diferentes fitofisionomias do Cerrado do Estado de São Paulo, crescendo desde ambientes mais abertos até áreas florestais mais fechadas. Aqui foram comparadas a anatomia foliar e alguns parâmetros ecofisiológicos de duas espécies do gênero Gochnatia, uma arbustiva (Gochnatia barrosii Cabrera) e a outra arbórea (Gochnatia polymorpha (Less.) Cabrera), ambas ocorrendo em área de cerradão na Estação Ecológica de Assis, SP. Encontraram-se diferenças estruturais qualitativas entre as espécies, com G. barrosii apresentando folhas anfiestomáticas, com epiderme unisseriada e G. polymorpha apresentando folhas hipoestomáticas, com epiderme múltipla ou hipoderme, na face adaxial. Além disso, as folhas de G. barrosii apresentaram menores valores para a espessura dos tecidos (com exceção da epiderme na face abaxial) e da folha em relação a G. polymorpha. Foram observadas diferenças na assimilação de CO2 tanto em base de área quanto de massa seca foliar, além de diferenças na área foliar específica, sendo esta maior em G. barrosii. Apesar das folhas de G. barrosii possuírem estrutura bem menos escleromorfa do que as folhas de G. polymorpha, não foram encontradas diferenças na eficiência do uso de água. Os resultados sugerem que espécies de formas distintas de crescimento de um mesmo gênero possuem características foliares diferenciadas para lidar com as variações ambientais a que são submetidas.