23736 research outputs found
Sort by
Non-lethal molecular diagnostic for acanthocephalosis in Colossoma macropomum
No full textThe tambaqui C. macropomum is intensively produced in aquaculture and is subject to numerous parasitosis, such as acanthocephalosis, a parasitosis caused by Neoechinorhynchus buttnerae infection. The conventional diagnosis of acanthocephalosis is performed through fish euthanasia, which brings economic loss for fish farmers and poor efficiency in managing disease prevention. Thus, in this study, was proposed the use of molecular tools to develop a nonlethal diagnosis method for acanthocephalosis. For this, a partial gene sequence of the 18S ribosomal RNA gene of N. buttnerae was isolated, and specific primers were designed for the detection of parasite DNA presence in the host's blood by quantitative polymerase chain reaction (qPCR). Infected and uninfected fish were submitted to molecular diagnosis by qPCR, which showed 84% efficiency, 100% specificity and 50% sensitivity. The identification of false negatives led to histopathological analysis. These analyses confirmed the impairment of intestinal structures and the presence of inflammatory response, specific features of acanthocephalosis lesions. Also, gene expression analysis of RAG2 (Recombination Activating Gene) and MALT1 (Mucosa-associated Lymphoid Tissue Lymphoma Translocation) showed a decrease in parasitized fish, demonstrating that the host immune system was compromised. Thus, evidence that it is possible to diagnose non-lethally, by qPCR, the presence of the parasite N. buttnerae from blood samples taken from its host C. macropomum were generated. Experimental alternatives, however, should be improved to increase the sensitivity of the method. © 2019 Elsevier B.V
Inibição da perda de cobertura vegetal natural nas Terras Indígenas da Amazônia Legal Brasileira
Full text linkThe Brazilian Amazon contains the world’s largest tract of tropical forest, about one quarter of which is within demarcated indigenous territories. Formal governmental recognition of these traditional territories is often a critical deterrent to deforestation, but the relative conservation performance of Indigenous Lands (ILs) under different legal categories and geographic contexts remains poorly understood. We used 30-m resolution Landsat satellite imagery to quantitatively assess the land cover status and annual rates of natural vegetation loss for 381 indigenous territories between 1985 and 2017. Using a comprehensive set of environmental and socio-economic covariates and a mixed-modelling approach, we found that all stages of formal IL recognition consistently inhibits natural vegetation loss throughout the Brazilian Amazon compared to adjacent unprotected areas. Formal Demarcation and distance from roads were the main proximate drivers of avoided natural vegetation loss inside ILs. Forest loss associated with road building is substantially curbed by ILs, showing the importance of frontier expansion when assessing indigenous reserve performance in counteracting natural vegetation loss. Because forest and savannah losses associated with agribusiness frontiers and infrastructure projects are likely to intensify, the importance of ecosystem services provided by ILs is expected to grow across the Brazilian Amazon. Cultural traits or heavily settled ILs have no impact on their effectiveness in precluding natural vegetation loss. Given widespread encroachment of agribusiness, formal recognition of indigenous territories is a key factor in decelerating primary habitat conversion across the Amazon.A Amazônia brasileira contém a maior área de floresta tropical do mundo, cerca de um quarto da qual está dentro de territórios indígenas. O reconhecimento formal desses territórios originários pelo governo pode ser crítico ao controle do desmatamento, porém, o desempenho relativo para conservação das Terras Indígenas (TIs) sob diferentes situações legais e contextos geográficos permanece pouco compreendido. Nós utilizamos imagens de satélite com resolução de 30 m para avaliar quantitativamente o status da cobertura vegetal e uso da terra, bem como as taxas anuais de perda de vegetação natural de 378 territórios indígenas e seu entorno direto, entre 1985 e 2017. Utilizando uma abordagem de modelos mistos nós avaliamos um conjunto abrangente de covariáveis ambientais e socioeconômicas, e concluímos que todos os estágios, incluindo os iniciais, do reconhecimento formal de TIs contribuem consistentemente para o controle da perda de vegetação natural em toda a Amazônia brasileira, em comparação com áreas desprotegidas adjacentes. A homologação final e a proximidade das estradas foram as principais covariáveis determinantes da perda evitada de vegetação natural. Ressalta-se, assim, a importância de se considerar a expansão da infraestrutura, ao avaliar o desempenho das reservas indígenas no controle da perda de vegetação natural. Como a perda de florestas e cerrados associada a fronteiras do agronegócio e projetos de infraestrutura tende a se intensificar, espera-se que a importância dos serviços ecossistêmicos fornecidos pelas TIs aumente na Amazônia brasileira. Nossos resultados apontaram, ainda, que componentes étnicos e linguísticos das populações das TIs não afetam a sua performance de conservação, assim como TIs mais densamente povoadas não apresentam redução de eficácia para a conservação. Verificamos, portanto, que dado o avanço da fronteira agrícola, o reconhecimento formal dos territórios indígenas é o fator-chave na desaceleração da conversão de habitat primário na Amazônia
What influences upland soil chemistry in the Amazon basin, Brazil? Major, minor and trace elements in the upper rhizosphere
No full textIncreasing land transformation in the Amazon basin, from forest to post-forest usage such as pastureland, agriculture and agroforestry, triggers significant changes in hydrology, soil fertility and regional climatology. However, relatively little is known about Amazon basin soil chemistry in general and about its possible alteration with recent land-use change. We present robust pedogeochemical data for 65 elements and oxides, and evidence for modification due to recent deforestation and post-forest land use on upland soils in Amazonas state, Brazil. Differences emerge in median element concentrations between these two land-cover types, and between central and southern parts of the basin. These new data, a product of the bi-national EcoRespira-Amazon (ERA) project, are based on triplicate sampling under different seasonal conditions at 29 sites, representing ca. 740,000 km2 and average annual meteorological conditions. Mineral soil samples (TOP: 0–20 cm; BOT: 30–50 cm) characterize the active upper rhizosphere. Data were obtained with very tight quality control from sampling to analysis (following GEMAS protocols), using various overlapping analytical methods. Some major, minor and trace element concentrations deviate strongly from established world soil averages, including the recent PEGS2. Geological (lithological) and weathering boundary conditions define the primary soil chemical signal. This is overprinted by biogeochemical forces (ecosystem feedbacks), and recently by human intervention (change of land cover, deforestation). The general assumption of depleted tropical soils is not justified as such – a more differentiated view is needed, since carbon and macronutrients such as nitrogen and phosphorous, albeit not always plant-available, do often occur in relatively high concentrations (median values TOP: 1.9, 0.15 and 0.02 wt%). Calcium, magnesium and potassium are truly depleted (median values TOP: 0.025, 0.095 and 0.065 wt%), albeit with noticeable variance. Trace elements, from silver to zirconium and including REE, show highly differentiated responses. Most are relatively enriched in post-forest soils; a subtle signal that is interpreted as reduced plant-soil interaction. BOT concentrations are generally higher than those in TOP soil, reflecting weathering conditions and biogeochemical cycling – with interesting exceptions (Br, Cd, Rb). © 2019 Elsevier B.V
Dwarf geckos and giant rivers: The role of the São Francisco River in the evolution of Lygodactylus klugei (Squamata: Gekkonidae) in the semi-arid Caatinga of north-eastern Brazil
No full textSpecies diversification can be strongly influenced by geomorphological features, such as mountains, valleys and rivers. Rivers can act as hard or soft barriers to gene flow depending on their size, speed of flow, historical dynamics and regional topographical characteristics. The São Francisco River (SFR) is the largest perennial river in the Caatinga biome in north-eastern Brazil and has been considered a barrier to gene flow and dispersal. Herein, we evaluated the role of the SFR on the evolution of Lygodactylus klugei, a small gecko from the Caatinga. Using a single-locus species delimitation method (generalized mixed Yule coalescent), we defined lineages (haploclades). Subsequently, we evaluated the role of the SFR in structuring genetic diversity in this species using a multilocus approach to quantify migration across margins. We also evaluated genetic structure based on nuclear markers, testing the number of populations found through an assignment test (STRUCTURE) across the species distribution. We recovered two mitochondrial lineages structured with respect to the SFR, but only a single population was inferred from nuclear markers. Given that we detected an influence of the SFR only on mitochondrial markers, we suggest that the current river course has acted as a relatively recent geographical barrier for L. klugei, for ~450 000 years. © 2019 The Linnean Society of London, Biological Journal of the Linnean Society
Genomic analyses reveal two species of the matamata (Testudines: Chelidae: Chelus spp.) and clarify their phylogeography
No full textThe matamata is one of the most charismatic turtles on earth, widely distributed in northern South America. Debates have occurred over whether or not there should be two subspecies or species recognized due to its geographic variation in morphology. Even though the matamata is universally known, its natural history, conservation status and biogeography are largely unexplored. In this study we examined the phylogeographic differentiation of the matamata based on three mitochondrial DNA fragments (2168 bp of the control region, cytochrome oxidase subunit I, and the cytochrome b gene), one nuclear genomic DNA fragment (1068 bp of the R35 intron) and 1661 Single Nucleotide Polymorphisms (SNPs). Our molecular and morphological analyses revealed the existence of two distinct, genetically deeply divergent evolutionary lineages of matamatas that separated in the late Miocene (approximately 12.7 million years ago), corresponding well to the time when the Orinoco Basin was established. As a result of our analyses, we describe the genetically and morphologically highly distinct matamata from the Orinoco and Río Negro Basins and the Essequibo drainage as a species new to science (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto is distributed in the Amazon Basin and the Mahury drainage. Additionally, the analyses revealed that each species displays phylogeographic differentiation. For C. orinocensis, there is moderate mitochondrial differentiation between the Orinoco and the Río Negro. For C. fimbriata, there is more pronounced differentiation matching different river systems. One mitochondrial clade was identified from the Amazon, Ucayali, and Mahury Rivers, and another one from the Madeira and Jaci Paraná Rivers. The C. orinocensis in the Essequibo and Branco Rivers have haplotypes that constitute a third clade clustering with C. fimbriata. Phylogenetic analyses of the R35 intron and SNP data link the matamatas from the Essequibo and Branco with the new species, suggesting past gene flow and old mitochondrial introgression. Chelus orinocensis is collected for the pet trade in Colombia and Venezuela. However, neither the extent of the harvest nor its impact are known. Hence, it is crucial to gather more information and to assess its exploitation throughout its distribution range to obtain a better understanding of its conservation status and to design appropriate conservation and management procedures. Resumen: La matamata es una de las tortugas más carismáticas del mundo, ampliamente distribuida en el norte de Sudamérica. Debido a su variación morfológica geográfica, se debate sobre el reconocimiento de dos subespecies o especies. A pesar de que la matamata es universalmente conocida, su historia natural, estado de conservación y biogeografía han sido muy poco estudiados. En este estudio examinamos la diferenciación filogeográfica de las matamatas en base a tres fragmentos de ADN mitocondrial (2168 pb de la región de control, la subunidad I del citocromo oxidasa y el gen del citocromo b), un fragmento de ADN genómico nuclear (1068 pb del intrón R35) y 1661 polimorfismos de nucleótido único (SNPs). Nuestros análisis moleculares y morfológicos revelaron la existencia de dos linajes evolutivos distintos de matamatas, genéticamente divergentes que se separaron en el Mioceno tardio (hace aproximadamente 12.7 millones de años), correspondiendo al tiempo en que se estableció la cuenca del Orinoco. Como resultado de nuestros análisis, describimos las genéticamente y morfológicamente distintas matamatas de las cuencas del Orinoco, Río Negro y Essequibo como una especie nueva para la ciencia (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto se distribuye en la cuenca del Amazonas y en el drenaje del Mahury. Adicionalmente, los análisis revelaron que cada especie muestra diferenciación filogeográfica. Para C. orinocensis, hay una moderada diferenciación mitocondrial entre el Orinoco y el Río Negro. Para C. fimbriata, hay una diferenciación más pronunciada, concordando con los diferentes sistemas fluviales. Se identificó un clado de los ríos Amazonas, Ucayali y Mahury y otro de los ríos Madeira y Jaci Paraná. Las C. orinocensis de los ríos Essequibo y Branco tienen haplotipos que constituyen un tercer clado que se agrupa con C. fimbriata. Los análisis filogenéticos del intrón R35 y los datos de SNP asocian las matamatas de Essequibo y Branco con la nueva especie, sugiriendo flujo de genes pasado e introgresión mitocondrial antigua. Chelus orinocensis se colecta para el comercio de mascotas en Colombia y Venezuela. Sin embargo, ni se conoce el alcance de las colectas ni su impacto. Por lo tanto, es crucial recopilar más información y evaluar su explotación en todo su rango de distribución, comprender mejor su estado de conservación y para diseñar acciones apropiadas de conservación y manejo. © 202
Ocorrência do pepper yellow mosaic virus e cucumber mosaic virus em Capsicum chinense no estado do Amazonas, Brasil
Full text linkThe habanero chilli pepper, Capsicum chinense is an important crop in the Amazon Basin, mainly grown by small-scale producers. Capsicum chinense plants in an experimental field in the northern Brazilian state of Amazonas were found exhibiting characteristic symptoms of viral infection. Leaf sap from symptomatic plants examined under a transmission electron microscope revealed the presence of elongated flexuous particles and isometric particles. Using molecular assays, the viruses were identified as pepper yellow mosaic virus (PepYMV) and cucumber mosaic virus (CMV). Aphids, identified as Aphis gossypii, were found colonizing the C. chinense plants in the field and may be the vector for both PepYMV and CMV. We report the first occurrence of these viruses infecting C. chinense in the state of Amazonas.A pimenta-de-cheiro, Capsicum chinense é uma cultura importante na Bacia Amazônica, cultivada principalmente por pequenos produtores. Plantas de C. chinense em um campo experimental localizado no norte do estado brasileiro do Amazonas, foram encontradas apresentando sintomas característicos de infecção viral. Extratos de amostras de folhas sintomáticas examinados ao microscópio eletrônico de transmissão revelaram a presença de partículas alongadas e flexuosas e de partículas isométricas. Análises moleculares permitiram identificar a presença do pepper yellow mosaic virus (PepYMV) e do cucumber mosaic virus (CMV). Pulgões, identificados como Aphis gossypii foram encontrados colonizando pimenteiras-de-cheiro neste campo experimental e podem representar o provável vetor de PepYMV e CMV. Este trabalho relata a primeira ocorrência desses vírus infectando C. chinense no estado do Amazonas
New insight into the systematics of Heteromurini (Collembola: Entomobryidae: Heteromurinae) with special reference to Alloscopus and Sinodicranocentrus gen.n.
No full textClassification of Heteromurini represented by Heteromurus and Dicranocentrus is currently under debate due to the presence of 5 or 6 antennal segments, respectively. Among the Heteromurini, Alloscopus is traditionally considered to be closely related to Heteromurus but its phylogenetic position is challenged by recent molecular evidence. A multilocus molecular phylogeny and topology tests conducted here indicate the closer relationship of Alloscopus and Dicranocentrus, and one non-Dicranocentrus basal group, Sinodicranocentrus gen.n. Two new species, Alloscopus bannaensis and A. liuae, are described from southern China. Intact tergal chaetotaxy including macrochaetae, microchaetae and S-chaetae is illustrated in Alloscopus for the first time. A new genus Sinodicranocentrus gen.n. is also erected based on the unique paired outer teeth on unguis and S-chaetotaxic pattern. Transformation among S-chaetae on the fifth abdominal tergite is presented to further illuminate the possible relationships among Heteromurini taxa. Main distinguishing characters used in the classification of Heteromurini and the phylogenetic position of supraspecific taxa are discussed. Comprehensive keys to the genera of Heteromurini and the species of Alloscopus are provided. This study provides the new insight into the relationships among Heteromurini genera and highlights the great systematic values of intact tergal chaetotaxy within the tribe. © Senckenberg Gesellschaft für Naturforschung, 2020
Obtenção de culturas miceliais monocariótica e dicariótica de duas linhagens amazônicas de Geastrum (Geastraceae, Basidiomycota)
Full text linkThe high diversity of the genus Geastrum and the difficulty of obtaining mycelial cultures impairs the study of the ecophysiology and the exploration of the biotechnological potential of the taxon. In this study, different culture media were tested to obtain mycelial cultures for G. lloydianum and G. subiculosum collected in the Brazilian Amazon. Data on spore germination, and isolation of monokaryotic cultures and in vitro sexual reproduction are presented, as well as a brief morphological description of the cultures obtained. For both species, Potato Dextrose Agar (PDA) was the most promising of the tested culture media. The highest growth in agar culture ever recorded for this genus is reported (4.9 mm per week for G. lloydianum and 7.5 mm for G. subiculosum). In the PDA culture medium, spores germinated after 35-40 days of incubation and the isolation of monokaryotic cultures of the two species, as well as in vitro sexual crosses, were successfully performed.A alta diversidade do gênero Geastrum e a dificuldade de obtenção de culturas miceliais prejudicam o estudo ecofisiológico e a exploração do potencial biotecnológico do táxon. Nesse estudo, foram testados diferentes meios de cultivo, visando a obtenção de culturas miceliais para G. lloydianum e G. subiculosum coletadas na Amazônia brasileira. A germinação dos esporos, o isolamento das culturas monocarióticas e o cruzamento sexual in vitro são apresentados, além de uma breve descrição morfológica das culturas obtidas. O meio de cultura Batata Dextrose Ágar (BDA) foi o mais promissor dentre os meios de cultura testados no cultivo das duas espécies. Reportamos o maior crescimento em cultura de ágar já registrado para esse gênero (4,9 mm por semana para G. lloydianum e 7,5 mm por semana para G. subiculosum). Nesse meio de cultivo, os esporos germinaram após 35-40 dias de incubação e o isolamento de culturas monocarióticas das duas espécies, assim com os cruzamentos sexuais in vitro, foram realizados com sucesso
