239 research outputs found
Frugivoria e ictiocoria em uma área de várzea na Amazônia Central brasileira
The aim of the study was to investigate the interaction between fish and plants through analysis of seeds taken entire from the digestive tract of fish, sampled in the Catalão Lake, Central Brazilian Amazon. Samples were collected in 2014 during periods corresponding to the flooding, peak of flood and receding waters. Seeds were consumed by 148 fish individuals, belonging to 14 species, two orders and six families, among them some migratory species, such as Colossoma macropomum, Pterodoras granulosus and species belonging to the genera Brycon and Triportheus. The most intense consumption was observed in May, June and July, corresponding to periods of flooding and early receding of waters. Eighteen plant species belonging to 16 families were identified. Cecropia spp., Ficus insipida and Laetia corymbulosa were the most abundant in the fish diets. Triportheus albus (n=33), Triportheus auritus (n=27) and Colossoma macropomum (n=19) had the largest number of sampled specimens containing seeds in their digestive tract. Seeds of 18 species were sown in a greenhouse with soil from várzea, in order to verify their viability; of these, only seeds of two species (Bactris riparia and Senna alata) did not germinate. For analysis of percentage, germination time and speed, were used two plant species, Cecropia spp. and Laetia corymbulosa, since they were the species most consumed by three species (Triportheus albus, T. angulatus and T. auritus), which were amongst the most abundant fish species in the study area. The percentage, speed and average time of germination of these two species did not differ from seeds taken from the stomach or intestine of the fishes evaluated. The same germination parameters were calculated for a subset of seeds taken only in the intestines (n= 100 seed) and those derived directly from the mother plants (n= 100). The results indicated significant difference for both species among the subsets of seeds taken from the intestines and from the mother-plants. Seeds subjected to the digestive process of the fish showed no germination increment. However, the fact that there were found viable seeds in the digestive tract of fishes with migratory habits, suggests that ichthyochory should be considered an highly important vector of seed dispersal in the várzeas.O objetivo do estudo foi investigar a interação entre peixes e plantas por meio da análise de sementes retiradas inteiras do trato digestório de peixes capturados no lago Catalão, Amazônia Central, Brasil. As coletas foram realizadas no ano de 2014 durante os períodos correspondentes à enchente, cheia e vazante. Consumiram sementes 148 exemplares de peixes pertencentes a 14 espécies, duas ordens e seis famílias, entre elas algumas de hábito migratório, como Colossoma macropomum, Pterodoras granulosus, e espécies dos gêneros Brycon e Triportheus. O consumo mais intenso foi verificado nos meses de maio, junho e julho, correspondentes aos períodos de cheia e início da vazante. Foram identificadas 18 espécies vegetais pertencentes a 16 famílias. Cecropia spp., Ficus insipida e Laetia corymbulosa apresentaram a maior frequência de ocorrência de consumo por peixes. Triportheus albus (n=33), Triportheus auritus (n=27) e Colossoma macropomum (n=19) tiveram o maior número de exemplares capturados com sementes. As sementes foram semeadas em casa de vegetação sobre solo de várzea, com o objetivo de verificar a sua viabilidade; dessas, apenas as sementes de duas espécies (Bactris riparia e Senna alata) não germinaram. Para análise de porcentagem, velocidade e tempo médio de germinação, foram utilizadas duas espécies, Cecropia spp. e Laetia corymbulosa, por terem sido as espécies mais consumidas por três das espécies de peixes mais abundantes na área de estudo, Triportheus albus, T. angulatus e T. auritus. A porcentagem, a velocidade e o tempo médio de germinação dessas duas espécies não diferiram entre sementes retiradas do estômago e do intestino dos peixes. Os mesmos parâmetros germinativos foram calculados para um subconjunto das sementes retiradas somente do intestino (n=100 sementes) e daquelas oriundas diretamente das plantas-mãe (n=100). Os resultados indicaram diferença significativa para as duas espécies entre subconjuntos das sementes retiradas dos intestinos e das plantas-mãe. Sementes submetidas ao processo digestório dos peixes não apresentaram incremento germinativo. Entretanto, o fato de terem sido encontradas sementes viáveis no trato digestório de peixes com hábito migratório, sugere que a ictiocoria deve ser considerada um vetor de elevada importante na dispersão de sementes na várzea
An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : The Redshift Distribution and Evolution of Submillimeter Galaxies
Accepted by ApJ. 45 pages, 16 figuresWe present the first photometric redshift distribution for a large unbiased sample of 870um selected submillimeter galaxies (SMGs) with robust identifications based on observations with the Atacama Large Millimeter Array (ALMA). In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band, optical-near-infrared, photometry. We model the Spectral Energy Distributions (SEDs) for these 77 SMGs, deriving a median photometric redshift of z=2.3+/-0.1. The remaining 19 SMGs have insufficient optical or near-infrared photometry to derive photometric redshifts, but a stacking analysis of IRAC and Herschel observations confirms they are not spurious. Assuming these sources have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that the undetected SMGs lie at higher redshifts, raising the median redshift for SMGs to z=2.5+/-0.2. More critically we show that the proportion of galaxies undergoing an SMG phase at z>3 is 35+/-5% of the total population. We derive a median stellar mass for SMGs of Mstar=(8+/-1)x10^10Mo, but caution that there are significant systematic uncertainties in our stellar mass estimate, up to x5 for individual sources. We compare our sample of SMGs to a volume-limited, morphologically classified sample of ellipticals in the local Universe. Assuming the star formation activity in SMGs has a timescale of ~100Myr we show that their descendants at z~0 would have a space density and M_H distribution which are in good agreement with those of local ellipticals. In addition the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.Peer reviewe
An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : The Redshift Distribution and Evolution of Submillimeter Galaxies
Accepted by ApJ. 45 pages, 16 figuresWe present the first photometric redshift distribution for a large unbiased sample of 870um selected submillimeter galaxies (SMGs) with robust identifications based on observations with the Atacama Large Millimeter Array (ALMA). In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band, optical-near-infrared, photometry. We model the Spectral Energy Distributions (SEDs) for these 77 SMGs, deriving a median photometric redshift of z=2.3+/-0.1. The remaining 19 SMGs have insufficient optical or near-infrared photometry to derive photometric redshifts, but a stacking analysis of IRAC and Herschel observations confirms they are not spurious. Assuming these sources have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that the undetected SMGs lie at higher redshifts, raising the median redshift for SMGs to z=2.5+/-0.2. More critically we show that the proportion of galaxies undergoing an SMG phase at z>3 is 35+/-5% of the total population. We derive a median stellar mass for SMGs of Mstar=(8+/-1)x10^10Mo, but caution that there are significant systematic uncertainties in our stellar mass estimate, up to x5 for individual sources. We compare our sample of SMGs to a volume-limited, morphologically classified sample of ellipticals in the local Universe. Assuming the star formation activity in SMGs has a timescale of ~100Myr we show that their descendants at z~0 would have a space density and M_H distribution which are in good agreement with those of local ellipticals. In addition the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.Peer reviewe
Germinação de sementes e morfologia de plântulas de espécies pioneiras da várzea amazônica
The white-water floodplain forests (várzea) have been affected for centuries by various human activities that endanger the integrity of this ecosystem, demanding studies that provide conservation and restoration. The objective of this study was to characterize the seedling morphology of three pioneer species present in the floodplain forest of Catalão Lake – AM: Cecropia latiloba Miq. (Urticaceae), Ficus insipida Willd. (Moraceae), Allophylus amazonicus (Mart.) Radlk. (Sapindaceae), as a subsidy to create tools for the field identification. Seeds were collected from three different matrices, these were processed and placed in trays for germination in soil from the collection site. Each developmental phase until the seedling formation was analyzed and morphologically described. In the three species, the germination was classified as epigeal and phanerocotyledonous, and all showed morphological differences in cotyledons, eophylls and cataphylls, allowing the visual separation of them. Our results indicate that the leaf morphology is an important tool to help the identification and differentiation from the early stages of the seedling development. This knowledge can support management strategies such as the formation of a seedling bank for the recovery of degraded várzea forests areas.As florestas de várzea estão sendo afetadas ao longo de séculos por diversas atividades antrópicas que põem em risco a integridade desse ecossistema, demandando estudos que propiciem sua conservação e restauração. O objetivo deste estudo foi caracterizar a morfologia de plântulas de três espécies pioneiras presentes na floresta de várzea do lago Catalão - AM: Cecropia latiloba Miq. (Urticaceae), Ficus insipida Willd. (Moraceae) e Allophylus amazonicus (Mart.) Radlk. (Sapindaceae) como subsídio para criar ferramentas para sua identificação em campo. Para cada espécie foram coletadas sementes de três diferentes matrizes, as quais foram processadas e acondicionadas em bandejas para germinação em solo proveniente do local de coleta. Foram analisadas e descritas morfologicamente cada fase de desenvolvimento até a formação de plântulas e mudas. Nas três espécies, a germinação foi classificada como epígea e fanerocotiledonar, e todas apresentaram diferenças morfológicas nos cotilédones, eófilos e catáfilos, permitindo a separação visual das mesmas. Os resultados indicam que a morfologia foliar é uma importante ferramenta para auxiliar a identificação e diferenciação desde as fases iniciais do desenvolvimento das plântulas. Esse conhecimento pode subsidiar estratégias de manejo como a formação de banco de plântulas para a recuperação de áreas degradadas de várzea
Knock-down of the 37kDa/67kDa laminin receptor LRP/LR impedes telomerase activity.
Cancer has become a major problem worldwide due to its increasing incidence and mortality rates. Both the 37kDa/67kDa laminin receptor (LRP/LR) and telomerase are overexpressed in cancer cells. LRP/LR enhances the invasiveness of cancer cells thereby promoting metastasis, supporting angiogenesis and hampering apoptosis. An essential component of telomerase, hTERT is overexpressed in 85-90% of most cancers. hTERT expression and increased telomerase activity are associated with tumor progression. As LRP/LR and hTERT both play a role in cancer progression, we investigated a possible correlation between LRP/LR and telomerase. LRP/LR and hTERT co-localized in the perinuclear compartment of tumorigenic breast cancer (MDA-MB231) cells and non-tumorigenic human embryonic kidney (HEK293) cells. FLAG® Co-immunoprecipitation assays confirmed an interaction between LRP/LR and hTERT. In addition, flow cytometry revealed that both cell lines displayed high cell surface and intracellular LRP/LR and hTERT levels. Knock-down of LRP/LR by RNAi technology significantly reduced telomerase activity. These results suggest for the first time a novel function of LRP/LR in contributing to telomerase activity. siRNAs targeting LRP/LR may act as a potential alternative therapeutic tool for cancer treatment by (i) blocking metastasis (ii) promoting angiogenesis (iii) inducing apoptosis and (iv) impeding telomerase activity.This work was supported by the National Research Foundation, the Republic of South Africa.NCS201
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Potent and Broad Neutralization of HIV-1 by a Llama Antibody Elicited by Immunization
Llamas (Lama glama) naturally produce heavy chain–only antibodies (Abs) in addition to conventional Abs. The variable regions (VHH) in these heavy chain–only Abs demonstrate comparable affinity and specificity for antigens to conventional immunoglobulins despite their much smaller size. To date, immunizations in humans and animal models have yielded only Abs with limited ability to neutralize HIV-1. In this study, a VHH phagemid library generated from a llama that was multiply immunized with recombinant trimeric HIV-1 envelope proteins (Envs) was screened directly for HIV-1 neutralization. One VHH, L8CJ3 (J3), neutralized 96 of 100 tested HIV-1 strains, encompassing subtypes A, B, C, D, BC, AE, AG, AC, ACD, CD, and G. J3 also potently neutralized chimeric simian-HIV strains with HIV subtypes B and C Env. The sequence of J3 is highly divergent from previous anti–HIV-1 VHH and its own germline sequence. J3 achieves broad and potent neutralization of HIV-1 via interaction with the CD4-binding site of HIV-1 Env. This study may represent a new benchmark for immunogens to be included in B cell–based vaccines and supports the development of VHH as anti–HIV-1 microbicides
Insight into the structure-property relationship of UO nanoparticles
Highly crystalline UO nanoparticles (NPs) with sizes of 2–3 nm were produced by fast chemical deposition of uranium(IV) under reducing conditions at pH 8–11. The particles were then characterized by microscopy and spectroscopy techniques including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy at the U M edge and extended X-ray absorption fine structure (EXAFS) spectroscopy at the U L edge. The results of this investigation show that despite U(IV) being the dominant oxidation state of the freshly prepared UO NPs, they oxidize to UO with time and under the X-ray beam, indicating the high reactivity of U(IV) under these conditions. Moreover, it was found that the oxidation process of NPs is accompanied by their growth in size to 6 nm. We highlight here the major differences and similarities of the UO NP properties to PuO, ThO and CeO NPs
Estudo da qualidade microbiológica de linguiças provenientes do Rio Grande do Sul e do perfil de suscetibilidade das bactérias isoladas
Objective: To analyze the microbiological quality of sausages from different regions of the state of Rio Grande do Sul, and to study the susceptibility profile of the bacteria isolated from these samples. Methods: Microbiological analysis was performed using the multiple tube technique (Most Probable Number per gram of sample) and the susceptibility profile by the Kirby-Bauer method. Results: The results of the microbiological analyzes demonstrated that 100% (16) of the analyzed samples were suitable for human consumption. The susceptibility profiles of 28 isolated bacteria were evaluated, with sensitivity in 85% of all antimicrobials tested, 2% of the profiles were considered intermediate and 13% resistant. Conclusions: Through this research were obtained information of great value for the whole community, which will help minimize and prevent food infections due to the consumption of these sausages.Atualmente a ocorrência de doenças bacterianas transmitidas pela ingestão de alimentos contaminados, como as linguiças, é um alerta no dia a dia da população. As principais bactérias causadoras destes distúrbios são os coliformes termotolerantes, que podem apresentar um alto índice de resistência, tornando-se mais patogênicos aos seres humanos. Dessa forma, é importante a realização de um controle microbiológico em todos os alimentos antes de consumi-los. Este trabalho teve por objetivo a análise da qualidade microbiológica de linguiças, provenientes de diferentes regiões do estado do Rio Grande do Sul, e o estudo do perfil de suscetibilidade das bactérias isoladas destas amostras. A análise microbiológica foi realizada através da técnica dos tubos múltiplos (Número Mais Provável por grama de amostra) e o perfil de suscetibilidade pelo método de Kirby-Bauer. Os resultados das análises microbiológicas demonstraram que 100% (16) das amostras analisadas estavam próprias para o consumo humano. Foram avaliados os perfis de suscetibilidade de 28 bactérias isoladas, sendo que estas apresentaram sensibilidade em 85% de todos antimicrobianos testados, 2% dos perfis foram considerados intermediários e 13% resistentes. Através desta pesquisa se obteve informações de grande valia para toda a comunidade, as quais ajudarão a minimizar e prevenir infecções alimentares decorrentes do consumo destes embutidos
Investigation of Adverse Reactions in Tattooed Skin through Histological and Chemical Analysis
Background:
Just as the number of tattooed people has increased in recent years, so has the number of adverse reactions in tattooed skin. Tattoo colourants contain numerous, partly unidentified substances, which have the potential to provoke adverse skin reactions like allergies or granulomatous reactions. Identification of the triggering substances is often difficult or even impossible.
Methods:
Ten patients with typical adverse reactions in tattooed skin were enrolled in the study. Skin punch biopsies were taken and the paraffin-embedded specimens were analysed by standard haematoxylin and eosin and anti-CD3 stainings. Tattoo colourants provided by patients and punch biopsies of patients were analysed with different chromatography and mass spectrometry methods and X-ray fluorescence. Blood samples of 2 patients were screened for angiotensin-converting enzyme (ACE) and soluble interleukin-2 receptor (sIL-2R).
Results:
Histology showed variable skin reactions such as eosinophilic infiltrate, granulomatous reactions, or pseudolymphoma. CD3+ T lymphocytes dominated the dermal cellular infiltrate. Most patients had adverse skin reactions in red tattoos (n = 7), followed by white tattoos (n = 2). The red tattooed skin areas predominantly contained Pigment Red (P.R.) 170, but also P.R. 266, Pigment Orange (P.O.) 13, P.O. 16, and Pigment Blue (P.B.) 15. The white colourant of 1 patient contained rutile titanium dioxide but also other metals like nickel and chromium and methyl dehydroabietate – known as the main ingredient of colophonium. None of the 2 patients showed increased levels of ACE and sIL-2R related to sarcoidosis. Seven of the study participants showed partial or complete remission after treatment with topical steroids, intralesional steroids, or topical tacrolimus.
Conclusions:
The combination of the methods presented might be a rational approach to identify the substances that trigger adverse reactions in tattoos. Such an approach might help make tattoo colourants safer in the future if such trigger substances could be omitted
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