Plant litter dynamics in the forest-stream interface: Precipitation is a major control across tropical biomes

Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth's land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m-2 y-1, storage: 55, 113 and 38 g m-2, on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas. © 2017 The Author(s)

Alismatales sensu stricto: cytogenetics analysis with conventional techniques, banding and rDNA sites

A ordem Alismatales corresponde a um dos clados basais de monocotiledôneas e se apresenta predominantemente em hábitats aquático ou semi-aquático. Nesse trabalho, objetivou-se compreender as relações taxonômicas internas e a evolução cariotípica em um grupo de Alismatales de ocorrência exclusivamente neotropical. Para isso, foram realizados estudos citogenéticos em cinco espécies de Alismataceae e quatro de Limnocharitaceae baseados na coloração convencional com uso de Giemsa 2%, marcação das RONs com nitrato de prata, bandeamento cromossômico C, dupla coloração com os fluorocromos CMA/DAPI e hibridização in situ fluorescence (FISH) com sondas de DNA ribossomal 45S. Em Hydrocharitaceae, foi usada apenas a coloração convencional com Giemsa 2%. Na família Alismataceae, as espécies de Echinodorus apresentaram 2n=22 e padrão de bandas CMA/DAPI e C/CMA/DAPI localizadas na região do braço curto e satélite de dois dos menores pares acrocêntricos A hibridização in situ com sondas de DNAr 45S coincidiu em geral, com os blocos observados com uso dos fluorocromos, com exceção de E. andrieuxii que obteve apenas três sítios. E. lanceolatus foi a única espécie que apresentou bandas DAPI+, localizadas nas regiões teloméricas de sete pares acrocêntricos. Em Limnocharitaceae,as regiões marcadas pelos fluorocromos CMA/DAPI e bandeamento C/CMA+ corresponderam às RONs e aos dois sítios de DNAr 45S em Hydrocleys nymphoides (2n=16) e aos quatro em Limnocharis flava (2n=20). Entretanto, L. laforestii diferiu em relação aos sítios de DNAr 45S, que foram apenas dois. As espécies Hydrocleys nymphoides e H. martii tiveram a posição da heterocromatina rica em GC associada ao satélite localizada em um par acrocêntrico pequeno na primeira, e em um par metacêntrico de tamanho intermediário, na segunda. O único representante de Hydrocharitaceae, Limnobium laevigatum, obteve 2n=28 e cariótipo assimétrico do tipo bimodal, assim como as demais espécies. Nesse grupo analisado, técnicas citogenéticas mais refinadas detectaram alterações cromossômicas estruturais importantes para a evolução cariotípica em Alismatales.The order Alismatales corresponds to one of the basal monocotiledones clads and is found predominantly in habitats aquatic or semiaquatic. The present work aimed to understand the internal taxonomic relations and the karyotype evolution in a monofiletic group of Alismatales of exclusively neotropical occurrence. Five species of Alismataceae and four of Limnocharitaceae were investigated using 2% Giemsa, silver nitrate staining, C-banding, CMA/DAPI fluorochromes staining and fluorescence in situ hybridization (FISH) with probes of ribossomal 45S DNA. One species of Hydrocharitaceae was also staining with Giemsa 2%. In Alismataceae, the Echinodorus species showed 2n=22 and CMA/DAPI and C/CMA/DAPI bands located in the short arm and satellite of two of the smallest acrocentric chromosomes pairs. Fluorescence in situ hybridization with 45S rDNA probe co-localized in general, with the blocks revealed after fluorochromes staining, with exception of E. andrieuxii, for which only three 45S rDNA sites were detected. E. lanceolatus was the only species with DAPI+ bands, which were located in the telomeric regions of seven acrocentric pairs. In Limnocharitaceae, Hydrocleys (2n=16) and Limnocharis (2n=20), the CMA+ regions had corresponded to the RONs and the 45S rDNA sites in Hydrocleys nymphoides and Limnocharis flava. L. laforestiidiffered in relation to the number of 45S rDNA because two sites were observed in the later. In Hydrocleys nymphoides and H. martii the GC-rich in the heterochromatin was associated with the satellite located in the smallest acrocentric pair, and in a metacentric pair of intermediate size in the later. The only representative of Hydrocharitaceae, Limnobium laevigatum showed 2n=28 and an asymmetric bimodal karyotype as well as the other investigated species. In the group examined the refined techniques cytogenetic provided information such as detection of structural chromosome changes important for the karyotype evolution in Alismatales.Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNP

Distribution of H4K5ac in chromosomes of species with low DNA content.

<p>a, <i>Poncirus trifoliata</i>; b, <i>Arachis pusilla</i>; c, <i>Bixa orellana</i>. Images display, respectively, Giemsa (black and white), DAPI (gray), FITC-conjugated anti-H4K5ac (green), DAPI/FITC (gray/green), CMA (yellow), and CMA/DAPI (yellow/gray) staining. Inset in a1 shows a chromosome with a proximal early condensing chromatin and a terminal heterochromatic block. Arrowheads in b point to the weakly stained A chromosome pair. Asterisks in a indicate chromosomes amplified in a4. Arrows in c point to the heterochromatic arm of chromosome pair 1 in prophase nuclei. Asterisks in c indicate the hypoacetylated CMA⁺ regions around the secondary constriction. Scale bar in a1 corresponds to 10 μm.</p

Distribution of H4K5ac in chromosomes of species with low DNA content.

<p>a, <i>Indigofera campestris</i>; b, <i>Phaseolus lunatus</i>; c, <i>P</i>. <i>vulgaris</i>; d, <i>Solanum lycopersicum</i>. Images display, respectively, Giemsa (black and white), DAPI (gray), FITC-conjugated anti-H4K5ac (green), DAPI/FITC (gray/green), and CMA/DAPI (yellow/gray) staining. Insets show magnified chromosomes displaying high and low condensed regions (a1-d1), and CMA⁺ NORs unlabeled with anti-H4K5ac (b4, b5). Arrows in c and d point to hyperacetylated CMA⁺ NORs. Insets in d2 and d3 show magnified chromosome (left arrow). Arrowheads in c3 and c4 indicate hypoacetylated CMA⁺ chromocenters. Scale bar in a1 corresponds to 10 μm.</p

Condensation patterns of prophase/prometaphase chromosome are correlated with H4K5 histone acetylation and genomic DNA contents in plants - Fig 3

<p>Distribution of H4K5ac in chromosomes of <i>Emilia sonchifolia</i> (<b>a</b>), <i>Rhynchospora tenuis</i> (<b>b</b>), <i>R</i>. <i>pubera</i> (<b>c</b>), and <i>Eleocharis geniculata</i> (<b>d</b>). Images display, respectively, Giemsa (black and white), DAPI (gray), FITC-conjugated anti-H4K5ac (green), DAPI/FITC (gray/green), and CMA/DAPI (yellow/gray) staining. Arrows in a5 and d2 point to NORs. Scale bar in a1 corresponds to 10 μm.</p

Distribution of H4K5ac in chromosomes of species with high DNA content.

<p>a, <i>Allium cepa</i>; b, <i>Callisia repens;</i> c, <i>Nothoscordum pulchellum</i>; d, <i>Araucaria angustifolia</i>. Images display, respectively, Giemsa (black and white), DAPI (gray), FITC-conjugated anti-H4K5ac (green), and CMA/DAPI (yellow/gray) staining. Arrows point to the NORs. Scale bar in a1 corresponds to 10 μm.</p

Aspectos de biologia floral de cajueiros anão precoce e comum Floral biology aspects of the early dwarf and common cashew

O conhecimento da biologia floral é de suma importância para o desenvolvimento da cultura do cajueiro (Anacardium occidentale L.). Com relação aos aspectos botânicos, as características morfológicas das flores contribuíram efetivamente para a determinação das espécies do gênero Anacarduim conhecidas. No presente trabalho, objetivou-se estudar a biologia floral dos cajueiros anão precoce e comum. A pesquisa foi desenvolvida na área experimental do Departamento de Fitotecnia, Centro de Ciências Agrárias, Universidade Federal do Piauí, em Teresina, PI, avaliando-se nove clones de cajueiro anão ("CAP 14", "Embrapa 09", "Embrapa 50", "Embrapa 51", "Embrapa 76", "Embrapa 183", "Embrapa 189", "FAGA 01", "FAGA 11") e um clone de cajueiro comum ("CCA"), utilizando-se quatro panículas por planta, cada uma com orientação norte, sul, leste e oeste. Os tipos varietais, cajueiro comum e anão precoce, apresentam pouca variação para a maioria dos caracteres avaliados. A proporção entre flores hermafroditas e o total de flores, em cajueiro comum, pode levá-lo a uma maior produção de frutos por panícula do que nos clones de cajueiro anão precoce analisados. O número de frutos desenvolvidos é bastante reduzido nos dois tipos varietais. As panículas situadas em diferentes orientações cardeais são semelhantes em todos os clones estudados quanto aos aspectos relacionados à biologia floral do cajueiro.The knowledge of the floral biology is very important for the development of the cashew's culture (Anacardium occidentale L.). In relation to botanical aspects, the morphological characteristics of flowers contributed effective to determination of the well-known species of Anacardium. It was aimed at studing the floral biology of the early dwarf and common cashew. The research was developed in the experimental area of the Department of Fitotecnia, Centro de Ciências Agrárias, Universidade Federal do Piauí, in Teresina, PI, and nine clones of dwarf cajueiro ('CAP 14', 'Embrapa 09', 'Embrapa 50', 'Embrapa 51', 'Embrapa 76', 'Embrapa 183', 'Embrapa 189', 'FAGA 01', 'FAGA 11') and a clone of common cashew ('CCA'), were evaluated using four paniculae per plant, in north, south, east and west orientation. The varietal types, common and early dwarf cashew, present little variation for most of the evaluated characteristics. The common cashew presents a larger proportion between the number of hermaphrodite flowers and the total number of flowers than the early dwarf cashew clones; this may facilitate a larger production of fruits in the common cashew. The number of developed fruits is very low in both varietal types. The paniculae placed in different cardinal orientations are similar in all the clones in relation to the aspects related to the floral biology of the cashew

Toxicity at the cellular level of artificial synthetic flavorings

The goal of the present study was to evaluate the cytotoxicity and genotoxicity of artificial synthetic flavoring agents Cookie and Tutti-frutti. To this end, root meristem cells of Allium cepa L. were exposed to these substances in exposure times of 24 and 48 hours using individual doses of 0.3; 0.6 and 0.9 mL and doses combined as follows: 0.3 mL + 0.3 mL; 0.6 mL and 0.9 mL + 0.6 mL + 0.9 mL. After applying the treatments, root meristems were fixed, hydrolyzed, stained and analyzed a total of 5,000 cells using an optical microscope to evaluate each dose and combined treatment. All three doses of Cookie flavoring and combined treatments significantly inhibited cell division of the tissue studied. Doses of Tutti-Frutti caused no change in cell division rate. In addition, doses of both flavorings and treatments combining these solutions induced cell aberrations in a significant number of cells to the A. cepa system. Therefore, under these analytical conditions, Cookie flavoring and combined doses were cytotoxic and genotoxic, and Tutti-Frutti flavoring, although non-cytotoxic, demonstrated genotoxic action. The goal of the present study was to evaluate the cytotoxicity and genotoxicity of artificial synthetic flavoring agents cookie and tutti-frutti. To this end, root meristem cells of Allium cepa L. were exposed to these substances in exposure times of 24 and 48 hour using individual doses of 0.3; 0.6 and 0.9 mL and doses combined as follows: 0.3 mL + 0.3 mL; 0.6 mL and 0.9 mL + 0.6 mL + 0.9 mL. After applying the treatments, root meristems were fixed, hydrolyzed, stained and analyzed a total of 5,000 cells using an optical microscope to evaluate each dose and combined treatment. All three doses of cookie flavoring and combined treatments significantly inhibited cell division of the tissue studied. Doses of tutti-frutti caused no change in cell division rate. In addition, doses of both flavorings and treatments combining these solutions induced cell aberrations in a significant number of cells to the A. cepa system. Therefore, under these analytical conditions, cookie flavoring and combined doses were cytotoxic and genotoxic, and tutti-frutti flavoring, although non-cytotoxic, demonstrated genotoxic action.