Microgramma Vacciniifolia Research Articles

Microgramma vacciniifolia Frond Lectin: In Vitro Anti-leishmanial Activity and Immunomodulatory Effects Against Internalized Amastigote Forms of Leishmania amazonensis.

The treatment of leishmaniasis, an anthropozoonosis caused by Leishmania protozoa, is limited by factors, such as adverse effects, toxicity, and excessive cost, which has highlighted the importance of novel drugs. In this context, natural products have been considered as sources of antileishmanial agents. This study investigated the leishmanicidal activity of Microgramma vacciniifolia frond lectin (MvFL) on promastigotes and amastigotes of Leishmania amazonensis. The effects of MvFL on promastigote proliferation and macrophage infection by amastigotes were evaluated and mean inhibitory concentrations (IC50) were calculated. As a safety assessment, the hemolytic capacity of MvFL (6.25-200µg/mL) against mouse and human erythrocytes was determined. Additionally, the ability of MvFL (6.25-100µg/mL) to modulate lysosomal and phagocytic activities and the nitric oxide (NO) production by murine peritoneal macrophages was also investigated. After 24h, MvFL inhibited the proliferation of L. amazonensis promastigotes, with anIC50 of 88µg/mL; however, hemolytic activity was not observed. MvFL also reduced macrophage infection by amastigotes with an IC50 of 52µg/mL. Furthermore, treatment with MvFL reduced the number of amastigotes internalized by infected murine peritoneal macrophages by up to 68.9% within 48h. At a concentration of 25µg/mL, MvFL stimulated lysosomal activity of macrophages within 72h, but did not alter phagocytic activity or induce NO production at any of the tested concentrations. MvFL exerts antileishmanial activity and further studies are needed to assess its therapeutic potential in in vivo experimental models of leishmaniasis.

Effects of Lectin Preparations from Microgramma vacciniifolia Rhizomes on the Survival, Digestive Enzymes, and Acetylcholinesterase Activity of Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Effects of Lectin Preparations from Microgramma vacciniifolia Rhizomes on the Survival, Digestive Enzymes, and Acetylcholinesterase Activity of Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Alterations induced by Tortrimosaica polypodivora on the stems of Microgramma vacciniifolia: simple or complex galls?

Abstract Microgramma vacciniifolia, an epiphyte fern, hosts of two stem galls. One is induced by Tortrimosaica polypodivora (Lepidoptera), which can also induce galls in M. squamulosa and M. mortoniana. The alterations induced by T. polypodivora on M. vacciniifolia stem were compared to non-galled organs to evaluate the anatomical potentials of host ferns in response to a galling Lepidoptera. Histochemical and histometrical comparisons between galled and non-galled stems were performed to assess the processes leading to gall formation. M. vacciinifolia and M. squamulosa galls were anatomically similar, although their sizes differ, reflecting the growth potential of each host species. Simple structural alterations, such as hyperplasia of cortical and pericycle cells, occur during gall formation, while cell hypertrophy, common in more complex galls, was only detected on the pericycle. Meristele size remained unaltered in galls, but the pericycle appeared hyperplasic. The protective scales were broader in galls. A nutritive tissue with lipids, typical to Lepidoptera galls, was observed around the larval chamber, with small cells and meristematic activity. Starch, proteins, and reducing sugars accumulated in nutritive cells are uncommonly found in Lepidoptera galls. Despite simple structural alterations, T. polypodivora induced a gradient of primary metabolites, similar to angiosperm galls.

Inhibition of Carrageenan-Induced Acute Inflammation in Mice by the Microgramma vacciniifolia Frond Lectin (MvFL).

Most anti-inflammatory drugs used nowadays have an excessive cost and their prolonged use has been connected with several injurious effects. Thus, the search for new anti-inflammatory agents is increasing. Lectins are carbohydrate-interacting proteins that can modulate immune response and the release of inflammation mediators. The Microgramma vacciniifolia frond lectin (MvFL) was previously reported to be an immunomodulatory agent in vitro. This work aimed to evaluate the effects of MvFL on the in vivo inflammatory status in the carrageenan-induced peritonitis and paw edema, using female Swiss mice. The animals were pretreated intraperitoneally with MvFL (5 and 10 mg/kg). In the peritonitis assay, the total and differential migration of white blood cells was evaluated, as well as the levels of cytokines, nitric oxide (NO), and total proteins in the peritoneal fluid. In the paw edema evaluation, the paw volume was measured in the early (from 30 min–2 h) and late (3–4 h) phases of edema formation. MvFL (5 and 10 mg/kg) was efficient in reducing neutrophil infiltration, pro-inflammatory cytokines (IL-6, IL-17, and TNF-α), NO, and protein content in the peritoneal fluid. It also repressed the edema formation in the late phase of the assay. In conclusion, MvFL showed inhibitory effects in in vivo acute inflammation, which encouraged future studies exploiting its immunomodulatory ability.

Antibacterial and antitumor activities of a lectin-rich preparation from Microgramma vacciniifolia rhizome

The rhizome of Microgramma vacciniifolia contains a lectin (carbohydrate-binding protein) called MvRL. Studies demonstrated that a MvRL-rich fraction did not show in vivo genotoxicity and acute toxicity in mice. This study aimed to evaluate the MvRL-rich fraction from M. vacciniifolia rhizome for antibacterial activity in vitro and in vivo as well as antitumor effect in vivo using the Ehrlich carcinoma model in mice. The fraction showed antibacterial activity against Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus with minimal inhibitory concentrations ranging from 31.2 to 125.0 ​μg/mL and minimal bactericidal concentrations from 62.5 to 200 ​μg/mL. The fraction was also effective in vivo against infection caused by these bacteria on Tenebrio molitor larvae considering the parameters evaluated. In regard to the antitumor activity, the treatments of Ehrlich carcinoma-bearing mice with the fraction at 100 and 200 ​mg/kg per os resulted in 62.58% and 75.43% of tumor inhibition, respectively. In conclusion, the MvRL-rich fraction showed in vivo antibacterial and antitumor activities and thus can be considered as an alternative of natural origin for the development of candidates for therapy.

Phenolic substances and cyanogenesis in galled and non-galled tissue of the fern species Microgramma vacciniifolia.

Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midge-induced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.

Antinociceptive and Anti-Inflammatory Effects of Saline Extract and Lectin-Rich Fraction from Microgramma vacciniifolia Rhizome in Mice.

Previous studies have characterized a saline extract from Microgramma vacciniifolia rhizome and its lectin (MvRL)-rich fraction with low acute toxicity. In the present study, we evaluated these preparations for acute toxicity (1,000 mg/kg) and antinociceptive and anti-inflammatory activities (100-400 mg/kg for the extract and 25-50 mg/kg for the fraction). No signs of toxicity were observed. Both the extract and fraction increased the latency period for nociception in the hot plate assay, decreased writhing induced by acetic acid, and promoted analgesic effects in phases 1 and 2 of the formalin test. The antinociceptive mechanism was attributed to interactions with opioid receptors and K+ ATPase channels. The extract and fraction decreased carrageenan-induced paw edema in 46.15 % and 77.22 %, respectively, at the highest doses evaluated. Furthermore, the fraction was shown to act on the bradykinin pathway. The ability to decrease leukocyte migration after treatment was also verified in the peritonitis and air pouch models. In exudates collected from air pouches, decreased tumor necrosis factor (TNF)-α and increased interleukin (IL)-10 levels were noted. Both the extract and fraction also effectively inhibited the development of granulomatous tissue. In conclusion, the substances investigated in this study can be used for the development of novel therapeutic options for pain and inflammatory processes.

Microgramma vacciniifolia frond lectin (MvFL) exhibits antitumor activity against sarcoma 180 in mice

In this study, we evaluated the antitumor activity of a lectin from Microgramma vacciniifolia frond (MvFL) in sarcoma 180-bearing mice. First, the in vitro cytotoxicity of MvFL on sarcoma 180 cells was evaluated. Tumor cells were inoculated into Swiss female mice, and after 7 days, the animals were treated intraperitoneally with phosphate-buffered saline (PBS, negative control), methotrexate (MTX, positive control, 1.5 mg/kg) or MvFL (10 or 20 mg/kg) for 7 days. We analyzed tumor weight, angiogenesis, relative water and food consumption, body weight, and hematological, biochemical, and histological parameters. MvFL inhibited cell growth (IC50: 20.6 μg/mL) and induced apoptosis and necrosis. Treatment with MvFL led to an 89.2–96.8% reduction in tumor weight. Histopathological analysis of tumors of animals treated with MvFL revealed necrotic points, presence of leukocyte infiltrates, and a smaller number of pleomorphic cells than negative control. MvFL interfered with the angiogenesis around the sarcoma 180 tumors. No changes in water and food consumption or weight gain were observed. There were no important changes in blood hematological and biochemical parameters in lectin-treated animals. The liver, kidneys, and spleen did not show signs of toxicity in all groups. In conclusion, MvFL has strong antitumor potential against sarcoma 180 models, without toxic effects.

Toxicity assessment of saline extract and lectin-rich fraction from Microgramma vacciniifolia rhizome

Microgramma vacciniifolia is broadly used in folk medicine but safety information is unavailable. Therefore, we evaluated the toxicity of a saline extract and a lectin-rich fraction of M. vacciniifolia rhizome. The extract showed hemolytic activity on mice erythrocytes at 1000 μg/mL, whereas the fraction promoted hemolysis (8.57–26.15%) at all tested concentrations (10–1000 μg/mL). Acute toxicity test in mice indicated an LD50 of >5000 mg/kg. Hematological alterations and increased serum alkaline phosphatase level were observed in the treated animals. Transaminases and urea levels increased in the groups treated with the extract or fraction at 5000 mg/kg. Leukocyte infiltration was observed in the liver of extract-treated animals and in the liver and lungs of mice treated with the fraction. The kidneys of animals treated with the fraction at 5000 mg/kg presented hydropic degeneration. The extract and fraction did not induce oxidative stress in the liver and did not show genotoxicity, as examined by micronucleus and comet assays. In conclusion, the preparations were not lethal to mice but caused some signs of toxicity, mainly the fraction. The results indicated the need to evaluate the toxicity of M. vacciniifolia rhizome in other models and in chronic assays.

Antinutritional effects of the chitin-binding lectin from Microgramma vacciniifolia rhizome (MvRL) on Sitophilus zeamais

Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) is one of the most common and destructive storage pests in the world and its control depends mostly on the utilization of synthetic pesticides. The hazards of synthetic chemicals to people and the environment, together with the development of resistance by the insects, stimulate the investigation of alternative methods. In the present study, we determined the effects of the ingestion of artificial diet containing the Microgramma vacciniifolia rhizome lectin (MvRL) on survival, feeding and nutrition of S. zeamais adults. MvRL was incorporated into the artificial diets at concentrations ranging from 10 to 130 mg/g. Mortality rate, ingested food and variation in the weight of the insects were determined after 7 days. In addition, the in vitro effects of MvRL on the activity of insect digestive enzymes were investigated. MvRL did not increase the mortality rates but disrupted the nutritional status of the insects since the biomass variation and efficiency in conversion of ingested food were negative. The lectin was able to inhibit in vitro β-glucosidase and α-amylase activities. In conclusion, MvRL showed anti-nutritional properties on S. zeamais adults, which may be due interference with digestive enzymes. MvRL may be useful as an additive or synergistic agent for reduced pest fitness by affecting the food conversion into biomass.

Microgramma vacciniifolia (Polypodiaceae) fronds contain a multifunctional lectin with immunomodulatory properties on human cells

In this study, we report the purification and characterization of a multifunctional lectin (MvFL) from Microgramma vacciniifolia fronds as well as its immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). MvFL (pI 4.51; 54kDa) is a glycoprotein able to inhibit trypsin activity and that has sequence similarities (32% coverage) with a plant RNA-binding protein. Hemagglutinating activity of MvFL was not altered by heating at 100°C for 30min, but was reduced in alkaline pH (8.0 and 9.0). Fluorimetric analyses showed that this lectin did not undergo marked conformational changes when heated. However, the MvFL conformation changed depending on the pH. MvFL at 6.25–25μg/mL was not cytotoxic to lymphocytes present among PBMCs. The PBMCs incubated for 24h with the lectin (12.5μg/mL) showed increased TNF-α, IFN-γ, IL-6, IL-10, and nitric oxide production. MvFL also stimulated T lymphocytes from PBMCs to differentiate into CD8+ cells. The activation (indicated by CD28 expression) of these cells was also stimulated. In conclusion, MvFL is a heat-stable and multifunctional protein, with both lectin and trypsin inhibitor activities, and capable of inducing predominantly a Th1 response in human PBMCs as well as activation and differentiation of T lymphocytes.

Epiphytic ferns in swamp forest remnants of the coastal plain of southern Brazil: latitudinal effects on the plant community

Community structure and spatial distribution of epiphytic ferns in swamp forest remnants along the coastal plain of the state of Rio Grande do Sul were analyzed. A total of 440 trees were sampled in fifty-seven 10 x 10 m plots. Each phorophyte was divided into five ecological zones (strata), where all species of epiphytic ferns were recorded. A total of 34 species representing 18 genera in six families were recorded. Polypodiaceae was the most represented family with 17 species, and Microgramma vacciniifolia had the highest epiphytic importance value. Characteristic holoepiphyte was the predominant ecological category, representing 70 % of the species. Ordination analysis showed a gradual change in floristic composition between ecological zones with richness differing significantly between strata. We observed that with increasing latitude there was a decrease in mean temperature and total rainfall, but an increase in frosts. These climatic and phytogeography changes result in a reduction in species richness and a change in the structure of epiphytic fern communities in a north-to-south direction. The importance of swamp forest remnants of the coastal plain to the diversity of epiphytic ferns is discussed.

Record of insects in two fern species of the genus Microgramma (Polypodiaceae) in the Atlantic Rain Forest, Rio de Janeiro state, Brazil.

species, Microgramma vacciniifolia (Langsd. et Fisch.) Copel. and Microgramma geminata (Schrad.) R.M.Tryon et A.F.Tryon.M. vacciniifolia is a fern epiphyte with Neotropical geographic range. It occurs in many types of vegetation and also in urban trees. In field work in the restinga (sandy coastal plains) of the Marica Environmental Protection Area, Rio de Janeiro State, Brazil, two morphological types of galls, ellipsoid and ovoid ( Figure 1a, b), were reported. Both galls were collected in a Myrtaceae “thicket” community from June 2008 to August 2009 and transported to the laboratory. Part of the sample was packed in transparent plastic bags with moist cotton and checked daily for adult emergence. The botanical dried specimens were deposited in the herbarium of the Faculdade de Formacao de Professores, UERJ (RFFP) and the zoological material were incorporated into the holdings of the Museu Nacional (MNRJ), Rio de Janeiro, Brazil (Cecidomyiidae), Agencia Paulista de Tecnologia dos Agronegocios (APTA), Ribeirao Preto (wasps) and Instituto Uiracu, Bahia (micromoths).The ellipsoid galls are induced by a micromoth (Microlepidoptera), Tortrimosaica polypodivora (Brown et Baixeras, 2004) (Figure 1a). One parasitoid wasp - Cheloninae (Braconidae) - and one inquiline species - Dasineura sp. (Cecidomyiidae) - are also found in the galls and this is the first record of both being connected to M. vacciniifolia. T. polypodivora also induces galls in another fern, Microgramma squamulosa (Kaulf.) de la Sota (Brown et al., 2004). Maia and Santos (2011) described Primadiplosis microgrammae (Maia, 2011) (Cecidomyiidae, Diptera) ( Figure 1b) as producing the ovoid galls found in M. vacciniifolia. In the present note, we record the occurrence of two parasitoids Torymidae and Tetrastichinae (Eulophidae). Hymenoptera is also recorded in these galls for the first time.Although these new records of wasps are presented at family or subfamily levels, they represent an important contribution due to the scarceness of data on insect-fern interactions in the neotropics. The new data indicate that these interactions are much more complex than our previous knowledge indicated.A compilation of gall midges and host plant species of the neotropical region revealed that 92% of these species were monophagous (inducing galls on a single host plant species) and only 5.6% were oligophagous (Carneiro et al., 2009). There is currently no data available for micromoths.The galls induced by micromoths (ellipsoid) are more frequent than those induced by midges (ovoid). The first galls can be found in M. vacciniifolia occurring in natural areas and urban trees, while the second galls are rare even in natural areas. This fern is cyanogenic. The cyanogenesis always occurs in the leaves and there is variation in the stem ( Santos et al., 2005 ). Studies suggest that insect oviposition is stimulated by cyanoglucosides and these compounds could play an important role in host selection (Honda et al., 1997). In field work in a Clusia “scrub” community, in the Restinga de Jurubatiba National Park (Carapebus municipality, Rio de Janeiro state) another micromoth (not identified) in the pupal stage was found to use the stem of

Ethno-medicinal study of plants used for treatment of human ailments, with residents of the surrounding region of forest fragments of Paraná, Brazil

Ethnopharmacological relevanceThis study aims to document the traditional knowledge on the use of medicinal plants in the neighborhood of the protected area “Parque Estadual da Cabeça do Cachorro”, a fragment of seasonal semideciduous forests. This vegetation is intensely fragmented and disturbed; despite its importance there are few records of the traditional knowledge of medicinal species. Material and methodsTwenty-four residents in the neighborhood of the protected area “Parque Estadual da Cabeça do Cachorro” were interviewed. The residents were questioned about preparation techniques, recommended doses, ways of administration and healing properties of various parts of the plants and were invited to walk through the park to collect in situ some species of plants. The recognized medicinal species were identified and traditional knowledge was systematized. Quantitative indices (Informant Consensus Factor – FIC and Use Value – UV) were calculated. Results115 species of medicinal plants belonging to 54 botanical families were cited. Asteraceae (n=14), Fabaceae (n=11), Myrtaceae (n=6), Bignoniaceae, Solanaceae and Verbenaceae (n=5) were the most species-rich. The highest use values were calculated for Achyrocline satureioides, Aristolochia triangularis and Bauhinia forficata (0.63). Moreover, the informants consensus about usages of medicinal plants ranges from 0.024 to 0.663, which shows high level of agreements among the informants for gastro-intestinal and respiratory system diseases. Furthermore, for the first time, new traditional medicinal uses of Asteraceae (Chromolaena pedunculosa Hook. & Arn.), Commelinaceae (Tradescantia fluminensis Vell.) and Polypodiaceae (Microgramma vacciniifolia Langsd. & Fisch.) species were reported. ConclusionsPresent study revealed that the residents of the surrounding region of forest fragments of Paraná are rich in ethno-medicinal knowledge and rely on plant-based remedies for common health problems. As in many parts of Brazil knowledge of the past is combined with new knowledge that has recently been incorporated emphasizing the cultural changes that this area is experiencing. Despite the use of different species of plants are crucial to their way of life, there is concern that these rich popular knowledge may disappear in the future as a result of a possible modernization of this area.

Toxic effects of Microgramma vacciniifolia rhizome lectin on Artemia salina, human cells, and the schistosomiasis vector Biomphalaria glabrata

The present study evaluated the toxicity of Microgramma vacciniifolia rhizome lectin (MvRL) to Artemia salina, human tumour cell lines (larynx epidermoid carcinoma Hep-2, NCI-H292 lung mucoepidermoid carcinoma, and chronic myelocytic leukaemia K562), and normal peripheral blood mononuclear cells (PBMCs), as well as to Biomphalaria glabrata embryos and adults. MvRL was toxic to A. salina (LC50=159.9μg/mL), and exerted cytotoxic effects on NCI-H292 cells (IC50=25.23μg/mL). The lectin (1–100μg/mL) did not affect the viability of K562 and Hep-2 tumour cells, as well as of PBMCs. MvRL concentration of 1, 10, and 100μg/mL promoted malformations (mainly exogastrulation) in 7.8%, 22.5%, and 27.7% of embryos, respectively, as well as delayed embryo development in 42.0%, 69.5%, and 54.7% of embryos, respectively. MvRL at a concentration of 100μg/mL killed B. glabrata embryos (17.7%) and adults (25%). Further, MvRL damaged B. glabrata reproductive processes, which was evidenced by observations that snails exposed to the lectin (100μg/mL) deposited fewer eggs than those in the control group, and approximately 40% of the deposited eggs exhibited malformations. Comparison of these results with that from A. salina assay indicates that MvRL is adulticidal at the concentration range which is toxic to environment. In conclusion, the cytotoxicity of MvRL on tumour cell and absence of toxicity to normal cell indicate its potential as chemotherapeutic drug. Also, the study revealed that the lectin is able to promote deleterious effects on B. glabrata embryos at environmentally safe concentrations.

Antifungal Activity of Microgramma vacciniifolia Rhizome Lectin on Genetically Distinct Fusarium oxysporum f. sp. lycopersici Races

Fusarium oxysporum f. sp. lycopersici races 1, 2, and 3 deteriorate tomato crops since they cause a vascular wilt. Lectins are carbohydrate-binding proteins with hemagglutinating and antifungal activities. This work reports that Microgramma vacciniifolia rhizome lectin (MvRL) inhibits F. oxysporum f. sp. lycopersici race 3 growth (61%) more intensely than of races 1 (55%) and 2 (45%). The hemagglutinating activity of MvRL was inhibited by glycoprotein preparations from mycelia of races 1, 2, and 3, and these data indicate that lectin carbohydrate-binding sites recognized glycosylated molecules from races. Inter-simple sequence repeat (ISSR) marker system showed that race 3 is genetically distinct from races 1 and 2, and thus the highest sensitiveness of F. oxysporum f. sp. lycopersici race 3 to MvRL may be due to molecular characteristics of this race.

Estudos químicos e biológicos de Microgramma vacciniifolia (Langsd. & Fisch.) Copel (Polypodiaceae)

Chemical studies with aerial parts of Microgramma vacciniifolia (Langsd. & Fisch.) Copel. afforded ²-sitosterol, hopan-22-ol, 6-metoxiapinenin-7-O-²-D-allopyranoside and a mixture containing ethyl esters of carboxilic acids. The structures of the coumpounds were elucidated by spectroscopy and GC-MS analysis. The total phenolics contents of the crude extract and fractions were determined by Folin-Ciocalteau method. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH). The AcOEt fraction showed better activity in DPPH assay (9.9 ± 0.03 µg/mL), and presented also higher contents of the total phenolic (93.60 ± 1.11 µg/mg). Antimicrobial and allelopathic effects of the crude etanolic extract and fractions also were evaluated. In addition, the combination of biological activities was discussed.

Cianogênese em esporófitos de pteridófitas avaliada pelo teste do ácido pícrico

Os glicosídeos cianogênicos são substâncias de defesa encontradas em alguns vegetais, capazes de liberar ácido cianídrico por meio de reações de hidrólise. O presente estudo teve como objetivo avaliar a ocorrência da cianogênese em esporófitos de pteridófitas num afloramento rochoso localizado no Parque Estadual da Serra da Tiririca, Rio de Janeiro, Brasil. Foram analisadas mensalmente durante um ano, folhas férteis, estéreis, jovens (báculos) e caules de 19 espécies de pteridófitas, distribuídas em 13 gêneros e nove famílias. A cianogênese foi caracterizada pelo teste do papel de filtro gotejado com ácido pícrico. Das pteridófitas estudadas, 14 foram pela primeira vez analisadas e 14 espécies apresentaram resultado positivo para a cianogênese. Os resultados encontrados demonstraram haver variação na liberação do ácido cianídrico nas espécies em diferentes partes do vegetal ao longo do período analisado. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. (Polypodiaceae) e Pteridium aquilinum (L.) Kuhn var. arachnoideum (Kaulf.) Brade (Dennstaedtiaceae) mostraram-se cianogênicas durante todo o período analisado.

Composição florística e estrutura comunitária de epífitos vasculares em uma floresta de galeria na Depressão Central do Rio Grande do Sul

Apesar das florestas de galeria serem amplamente difundidas nos neotropicos, existem poucas informacoes disponiveis sobre seu epifitismo vascular. O objetivo deste estudo foi investigar a composicao floristica e a estrutura comunitaria dos epifitos vasculares em uma floresta de galeria que acompanha dois arroios na Depressao Central do Rio Grande do Sul, sul do Brasil. A area estudada situa-se na Estacao Experimental Agronomica (30°04' - 30°07' S e 51°40' - 51°42' W) da Universidade Federal do Rio Grande do Sul (UFRGS) a uma altitude aproximada de 40 m. O clima regional e subtropical umido (Cfa), com medias anuais de temperatura e precipitacao de 19,2 oC e 1.310 mm, respectivamente. Sessenta forofitos com DAP minimo de 10 cm foram amostrados atraves do metodo de pontos quadrantes. Os parâmetros de frequencia e diversidade foram estimados com base na ocorrencia epifitica sobre individuos forofiticos e sobre os segmentos fuste e copa. O levantamento floristico resultou em 13 familias, 32 generos e 50 especies. As familias mais ricas em especies foram Orchidaceae (13), Bromeliaceae (8), Polypodiaceae (8), Cactaceae (5) e Piperaceae (5). Duas pteridofitas, Microgramma vacciniifolia e Polypodium pleopeltifolium, apresentaram os maiores valores de importância. O indice de diversidade de Shannon foi 3,434 (nats) para toda a comunidade epifitica. Considerando os ambientes de fuste e copa, os valores foram 3,092 e 3,298, respectivamente. Estes valores intermediarios em relacao a outros estudos no sul do Brasil provavelmente refletem uma tipica situacao subtropical, onde a diversidade epifitica decresce com a diminuicao da temperatura e precipitacao.

Epifitismo vascular em uma floresta de restinga do Brasil subtropical

Um estudo fitossociológico de epífitos vasculares foi realizado em uma floresta de restinga do nordeste do Rio Grande do Sul, Brasil. Um total de 60 árvores hospedeiras (forófitos) foi amostrado empregando o método dos quadrantes centrados, incluindo árvores com no mínimo 10cm de diâmetro à altura do peito. Os epífitos vasculares registrados pertencem a 8 famílias, 20 gêneros e 31 espécies, sendo as Orchidaceae e as Bromeliaceae as mais diversificadas. Diversas espécies adicionais foram registradas no estande florestal de aproximadamente um hectare. Valores de frequência dos epífitos vasculares formaram uma sequência gradualmente decrescente de espécies, sendo Microgramma vacciniifolia (Polypodiaceae) e Tillandsia aëranthos (Bromeliaceae) as mais importantes. O índice de diversidade de Shannon doi estimado (H'=2,990), usando a frequência sobre forófitos individuais como uma medida de participação quantitativa (pi). O número de epífitos vasculares sobre forófitos individuais variou de 4 a 16 espécies, apresentando uma distribuição polimodal e um valor modal mais alto de oito espécies.