Cadmium tolerance of Typha domingensis Pers. (Typhaceae) as related to growth and leaf morphophysiology / A tolerância ao cádmio por Typha domingensis Pers. (Typhaceae) correlacionada com o crescimento e a morfofisiologia foliar

Abstract Typha domingensis (cattail) is a native macrophyte known by its capacity to tolerate several heavy metals effects and the potential use for phytoremediation. However, in despite that cadmium (Cd) is one of the most toxic pollutants; its effects in T. domingensis biology remain uninvestigated. Thus, the objective of this study was to study the tolerance of T. domingensis to cadmium contamination by evaluating its growth, Cd uptake, leaf anatomy and gas exchange. The experiment was designed using three cadmium concentrations (0, 10 and 50 µM) and ten replicates for 90 days. The cadmium uptake, growth, gas exchange, chlorophyll content and leaf anatomy were evaluated. Data was submitted to ANOVA and Scott-Knott test for P<0.05. Typha domingensis accumulates Cd proportionally to its concentration on the solution and the content of this metal was higher in roots as compared to shoots. Plants showed no significant modifications on growth parameters such as the biomass production, number of leaves, number of clones and the biomass allocation to organs. The photosynthesis, transpiration and chlorophyll content were not modified by Cd. Most anatomical traits evaluated were not modified by the metal but the stomatal density and the proportion of vascular tissues were reduced under 50 µM of Cd. In despite, the leaf anatomy showed no toxicity evidences for any Cd level. The absence of growth reduction and the stability of anatomical and physiological traits give insight about the Cd tolerance of this species. Therefore, T. domingensis is able to overcome Cd toxicity and shows potential for phytoremediation.

Resumo A espécie Typha domingensis (taboa) é uma macrófita nativa conhecida por sua tolerância a vários metais pesados e potencial uso na fitorremediação. Contudo, apesar de que o Cd é um dos poluentes mais tóxicos; Seus efeitos em T. domingensis ainda não foram investigados. Assim, o objetivo desse estudo foi avaliar a tolerância de T. domingensis ao cádmio, avaliando o crescimento, absorção de Cd, anatomia foliar e trocas gasosas. O experimento foi conduzido utilizando três concentrações de Cd (0, 10 e 50 µM) e dez repetições por 90 dias.. O crescimento, trocas gasosas e o teor de clorofila e anatomia foliar foram avaliados. Os dados foram submetidos à ANOVA e ao teste de Scott-Knott para P<0,05. A absorção de cádmio, crescimento, trocas gasosas, teor de clorofila e anatomia foliar foram analisados. As plantas de T. domingensis podem acumular Cd proporcionalmente à sua concentração na solução e o teor deste metal foi maior nas raízes em comparação com a parte aérea. As plantas não apresentam modificações significativas nos parâmetros de crescimento como produção de biomassa, número de folhas, número de clones produzidos e alocação de biomassa nos órgãos. A fotossíntese, transpiração e conteúdo de clorofila não foram afetados de forma significativa pelo Cd. A maioria das características anatômicas avaliadas não apresentou diferenças, mas houve redução na densidade estomática e na proporção de tecidos vasculares na concentração de 50 µM de Cd. A anatomia foliar não mostrou evidências de toxicidade em nenhum dos níveis de Cd. A ausência de redução de crescimento e estabilidade das características anatômicas e fisiológicas caracteriza alta tolerância da espécie ao Cd. Portanto, T. domingensis é capaz de superar a toxicidade do Cd e demostra potencial para fitorremediação.

Ação da clorofila como fotossensibilizador e do LED como fonte de luz alternativa na terapia fotodinâmica antimicrobiana contra o Enterococcusfaecalis / Effect of chlorophyll as photosensitizer and LED as an alternative light source on Antimicrobial Photodynamic Therapy against Enterococcus faecalis

O objetivo deste estudo foi investigar o efeito da Terapia Fotodinâmica antimicrobiana (TFDa) sobre o Enterococcus faecalis (E. faecalis), in vitro, utilizando a clorofila (CL) como agente fotossensibilizador (FS) e o diodo emissor de luz (LED) como fonte de luz. A cultura pura de E. faecalis foi ativada em caldo de BHI a 37oC por 24h. O cultivo do microrganismo foi centrifugado a 3000rpm por 15min, e o pellet re-suspenso em 0,85% de solução salina. As concentrações da bactéria foram ajustadas para 107UFC mL-1 (unidades formadoras de colônias por mililitro). Diferentes tipos de solventes para a CL foram testados: éter, álcool de cereais, Tween 80 e P-123. 100l do inóculo e o mesmo volume da solução teste foram inseridos em cada poço da placa de microtitulação. A mistura foi agitada e aguardou-se 1min. 25l da suspensão foi removida e diluições seriadas foram realizadas. Alíquotas de cada diluição foram espalhadas na superfície da placa, armazenadas em microaerofilia e incubadas na estufa por 24h a 37oC. O número de UFC foi contado em cada placa. Para o experimento da TFDa, os grupos foram divididos em: controle (G1); TBO 1min (G2); CL+Tween 1min (G3); CL+Tween 5min (G4); CL+P-123 1min (G5); CL+P-123 5min (G6); CL+Tween 1min + LED 1min (G7); CL+Tween 1min + LED 5min (G8); CL+Tween 5min + LED 1min (G9); CL+Tween 5min + LED 5min (G10); CL+P-123 1min + LED 1min (G11); CL+P-123 1min + LED 5min (G12); CL+P-123 5min + LED 1min (G13); CL+P-123 5min + LED 5min (G14); TBO 1min + LED 1min (G15); TBO 1min + LED 5min (G16); LED 1min (G17); LED 5min (G18).Um volume de 100l da suspensão bacteriana foi inserido em poços da placa e o mesmo volume da solução do FS foi adicionado. A CL foi solubilizada em soluções aquosas de Tween ou P-123. Cada poço foi agitado e o tempo de préirradiação foi de 1 ou 5min. O LED foi acionado durante 1 ou 5min. 25l da suspensão foi submetida a diluições seriadas e as alíquotas de cada diluição foram espalhadas na superfície da placa em Ágar BHI...

The aim of this study was to investigate the effect of Antimicrobial Photodynamic Therapy (aPDT) against Enterococcus faecalis (E. faecalis), in vitro, using chlorophyll (CL) as photosensitizer (FS) agent and light-emitting diode (LED) as light source. Pure culture of E. faecalis was cultivated in BHI broth at 37oC for 24h. The culture was centrifuged at 3000rpm for 15min, and the pellets were resuspended in 0.85% saline solution. The bacterial concentrations were adjusted to 107CFU mL-1 (colony forming units per milliliter). Different types of solvents for CL were tested: ether, grain alcohol, Tween 80 and P-123. 100l of inoculum and the same volume of the test solution were inserted into each well of the microtitre plate. The mixture was mixed and 1 min was awaited. 25l of the suspension was removed and serial dilutions were performed. Aliquots of each dilution were spread on the surface of the plates, stored in microaerophilic conditions and incubated for 24h at 37oC. The number CFU was counted in each plate. For aPDT experiment, the groups were divided into: control (G1); TBO 1min (G2); CL+Tween 1min (G3); CL+Tween 5min (G4); CL+P-123 1min (G5); CL+P-123 5min (G6); CL+Tween 1min + LED 1min (G7); CL+Tween 1min + LED 5min (G8); CL+Tween 5min + LED 1min (G9); CL+Tween 5min + LED 5min (G10); CL+P-123 1min + LED 1min (G11); CL+P-123 1min + LED 5min (G12); CL+P-123 5min + LED 1min (G13); CL+P-123 5min + LED 5min (G14); TBO 1min + LED 1min (G15); TBO 1min + LED 5min (G16); LED 1min (G17); LED 5min (G18). A volume of 100l of bacterial suspension was inserted into the well of microtitre plate and the same volume of FS was added. CL was solubilized in aqueous solution of Tween and P-123. Each well was mixed and preirradiation time was 1 or 5min. LED was irradiated during 1 or 5 min. 25l of suspension was subjected to serial dilutions and aliquots of each dilution were spread on the surface of agar BHI plates. The plates were stored and incubated at 37oC for 24h...

Spectral reflectance properties of mangrove species of the Muthupettai mangrove environment, Tamil Nadu.

In the Muthupettai mangrove environment, spectral properties of six mangrove species viz. Avicennia marina, Aegiceras corniculatum, Excoecaria agallocha, Acanthus ilicifolius, Suaeda monoica and S. maritima was studied using Multi band Ground Truth Radiometer (Model-041). The study found that the chlorophyll concentration of different mangrove leaves varies between 0.05 and 0.36 mg g(-1), registering the minimum in S. maritima and maximum in E. agallocha. Interestingly species with higher chlorophyll concentration showed lower reflectance values alteast in the spectral bands 1 and 2. E. agallocha registered 0.36 mg g(-1) of chlorophyll while it recorded only 2.18 and 2.43% reflectance where as S. maritima recorded 3.16 and 3.27% of reflectance in bands 1 and 2. This indicates chlorophyll concentration is one of major factors responsible in determining the reflectance pattern of the pant communities. The spectral properties of mangroves were largely differed with that of the water and soil samples collected from the same locations, these results favourd the utilization of remotely sensed data for depicting various water and soil quality parameters from that of mangrove species in the mangrove environment. This study also found that the difference in reflectance of mangroves at canopy level is not only influenced by the chlorophyll content of species but also by the prevailing environmental condition and background reflectance of soil and water as well.

Multiple antimicrobial resistance in Enterobacteriaceae isolates from pristine freshwater

A freshwater enterobacterial population (N = 111) was studied for antimicrobial and mercury resistance patterns, and for its possible association with biotic and abiotic factors in that environment. Conventional biochemical tests identified Klebsiella sp, Morganella sp, Serratia sp, Escherichia sp, Enterobacter sp, Edwarsiella sp, Proteus sp, Citrobacter sp, Providencia sp, and Kluyvera sp. There was no correlation between antimicrobial resistance patterns of isolates and bacterial genera, but resistance patterns varied among water samples and between seasons. Resistance to multiple antimicrobials was common (61%). The percentage of bacteria resistant to at least one antimicrobial differed between the rainy (100%) and dry seasons (89%). Resistance to â-lactams and chloramphenicol was the most frequent and resistance to amikacin, gentamicin and kanamycin was less frequent. The main water variables examined (abiotic factors pH and temperature; biotic factor chlorophyll a concentration) did not influence antimicrobial resistance. Significant impact on freshwater enterobacteria, as evidenced by antimicrobial-multiple resistance and by the presence of blaTEM gene, may point to the fact that it has an important role in horizontal spread of resistance.

Biochemical studies of embryogenic and non-embryogenic callus of Cardiospermum halicacabum L.

Some physiological and biochemical changes were measured between embryogenic and non-embryogenic callus obtained from Cardiospermum halicacabum. Combination of auxin with cytokinin was more favourable for high amount of callus formation. 2,4-D played a key role in triggering somatic embryo formation. Embryogenic callus had more total carbohydrate and starch contents, total free amino acids, nucleic acids, phenols and ascorbic acid. Non-embryogenic callus exhibited high chlorophyll content, total soluble sugar, protein, ammonia and enzymes like peroxidase and polyphenol oxidase. Thus, the present study indicated that the process of somatic embryogenesis was characterized by some biochemical and physiological changes induced by plant growth regulators.

Photochemical efficiency of adult and young leaves of the neotropical understory shrub Psychotria limonensis (Rubiaceae)in response to changes in the light environment

We explored the short-term adjustment in photochemical efficiency (Fv /Fm )in adult and young leaves of the understory neotropical shrub Psychotria limonensis Krause (Rubiaceae)in response to rapid changes in the light environment.Leaves were collected from 20 individual plants growing under sun and shade conditions on Gigante Peninsula,Barro Colorado Natural Monument (Republic of Panama),during the wet season of 1996. Leaves were distributed in four sequences of light treatments (AB leaves were expanded under sun and were transferred to shade,BA leaves experienced the opposite transfer,and the controls AA and BB leaves that were expanded and maintained under sun or shade conditions).Adult and young leaves did not differ in overall photochemical efficiency.Instead,differences were found among light environments,for which leaves transferred from shade to sun showed the lowest F v /F m ratios.There was no relationship between photochemical efficiency and leaf temperature.In P.limonensis,understory plants are susceptible of photoinhibition independently of the leaf ontogenetic stage.The approach utilized in this experiment allowed the rapid exploration of this capacity, and could be applied to poorly studied understory species

Se exploró el ajuste a corto plazo en la eficiencia fotosintética (Fv /Fm )en hojas jovenes y adultas del arbusto del sotobosque neotropical Psychotria limonensis Krause (Rubiaceae)en respuesta a cambios rápidos de luz ambiental. Las hojas fueron recolectadas de 20 plantas individuales bajo condiciones de sol y sombra en Peninsula Gigante, Monumento Natural Barro Colorado (Panamá),durante la estación lluviosa de 1996.Las hojas fueron distribuidas en una secuencia cuatro tratamientos de luz (AB las hojas fueron expandidas bajo el sol y fueron transferidas a la sombra,BA las hojas experimentaron la transferencia contraria,y las hojas controles AA y BB que fueron expandidas y mantenidas bajo condiciones de sol o de sombra).Las hojas adultas o jóvenes no difieren en la eficiencia fotoquímica general.Por el contrario,se encontró diferencias entre los ambientes de luz (iluminados), para los cuales las hojas transferidas de la sombra al sol mostraron las menores tasas Fv /Fm .No hubo relación entre la eficiencia fotoquímica y la temperatura de las hojas. En P.limonensis ,las plantas son suceptibles a la foto -inhibición independientemente del estado ontogenético de la hoja. El enfoque utilizado en este experimento permitió la rápida exploración de esta capacidad y demostró que puede ser utilizado en otras especies poco estudiadas del sotobosque

Native state, energetic interaction of chlorophyll precursors and intraplastid location of S-adenosyl-L-methionine: Mg-protoporphyrin IX methyltransferase in etiolated leaves.

Low temperature fluorescence spectra (FS) and fluorescence excitation spectra (FES) of protoporphyrin IX (Proto), Mg-protoporphyrin IX and its monomethyl ester (MgProto-ME) and protochlorophyllide (Pchlide) in etiolated barley leaves treated with 5-aminolevulinic acid and/or 2,2'-dipyridyl were studied. The spectra of Proto and MgProto-ME showed a little dependence on temperature of registration and exhibited similarity to low temperature spectra in diluted organic and buffer solutions. However, a red wavelength shift for Soret bands of Proto and MgProto-ME was observed due to porphyrin interaction with bovine serum albumin in 0.05 M, Na2HPO4 solution at room temperature. Disaggregating treatments had no effect on Proto and MgProto-ME spectra in plants. These results suggested that in etiolated leaves Proto and MgProto-ME molecules were in a monomer state. The spectral properties of these molecules were determined by interaction of porphyrins with proteins and other plastid membrane components. The spectral analyses indicated an efficient energy migration from Proto and MgProto-ME molecules to active form of Pchlide which emitted at 656nm, and no energy transfer from carotenoids to porphyrins in vivo. These findings suggested that Proto and MgProto-ME from carotenoids, and close location of these porphyrins and photoactive Pchlide in etioplast membranes. The latter conclusion was strongly supported by an observation that in etiolated leaves, S-adenosyl-L-methionin:Mg-protoporphyrin IX methyltransferase, which converts MgProto into MgProtoME, were located not only in prothylakoids but also in prolamellar bodies containing photoactive Pchlide.

A model for the organization of chlorophyll-protein complex of photosystem II and analysis of its photochemical efficiency and excitation migration.

A model is proposed for the organization of chlorophyll-protein complex in photosystem II (PS II) of higher plants. The rates of exciton migration and exciton trapping have been computed using stochastic method to find out the photochemical efficiency of the dimeric PS II. Three dimeric PS II units are assumed to form a group, as transfer of the exciton to the light harvesting bed of the nearest neighbour on either side may only be effective. A relationship has been deduced between the fractions of the reaction centre traps closed and the number of jumps (J) required by the exciton for trapping. The photochemical efficiency and fluorescence quantum yield are computed using J as the parameter in an empirical equation.