18 research outputs found

    Glaciation Effects on the Phylogeographic Structure of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in the Southern Andes

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    The long-tailed pygmy rice rat Oligoryzomys longicaudatus (Sigmodontinae), the major reservoir of Hantavirus in Chile and Patagonian Argentina, is widely distributed in the Mediterranean, Temperate and Patagonian Forests of Chile, as well as in adjacent areas in southern Argentina. We used molecular data to evaluate the effects of the last glacial event on the phylogeographic structure of this species. We examined if historical Pleistocene events had affected genetic variation and spatial distribution of this species along its distributional range. We sampled 223 individuals representing 47 localities along the species range, and sequenced the hypervariable domain I of the mtDNA control region. Aligned sequences were analyzed using haplotype network, Bayesian population structure and demographic analyses. Analysis of population structure and the haplotype network inferred three genetic clusters along the distribution of O. longicaudatus that mostly agreed with the three major ecogeographic regions in Chile: Mediterranean, Temperate Forests and Patagonian Forests. Bayesian Skyline Plots showed constant population sizes through time in all three clusters followed by an increase after and during the Last Glacial Maximum (LGM; between 26,000–13,000 years ago). Neutrality tests and the “g” parameter also suggest that populations of O. longicaudatus experienced demographic expansion across the species entire range. Past climate shifts have influenced population structure and lineage variation of O. longicaudatus. This species remained in refugia areas during Pleistocene times in southern Temperate Forests (and adjacent areas in Patagonia). From these refugia, O. longicaudatus experienced demographic expansions into Patagonian Forests and central Mediterranean Chile using glacial retreats

    Polyp flats, a new system for experimenting with jellyfish polyps, with insights into the effects of ocean acidification

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    Research interest on jellyfish has grown exponentially over the last years and studies focusing on the biology and ecology of the jellyfish polyp stage are being recognized as crucial in understanding jellyfish proliferations. Due to the difficulty of conducting in situ work with jellyfish polyps, laboratory experiments are the most used approach. Here, we describe the design and successful testing of a new system that allows continuous seawater renewal while keeping constant the selected physicochemical conditions of the water throughout the experiment in contrast to closed systems used previously. As a first test, we started an experiment to assess the effects of ocean acidification on the growth and development of jellyfish polyps of Aurelia sp. This new design demonstrated high precision in maintaining constant conditions (pH, temperature, and flow rates) among the replicates of each treatment, and ensured excellent conditions for jellyfish polyp survival. All together it has shown to be an effective platform to assess the effect of environmental variables on the growth and development of jellyfish polyps. © 2014, by the American Society of Limnology and Oceanography, Inc

    Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning: A review

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    Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams.This study has received funding from the Iberian Association of Limnology (AIL) through the project URBIFUN (Urbanization effects on the relationship between microbial biodiversity and ecosystem functioning), awarded to Míriam Colls and Ferran Romero. Authors thank as well the Basque Government (Consolidated Research Group IT951-16) and the MERLIN project 101036337 – H2020-LC-GD-2020/H2020-LC-GD-2020-3.info:eu-repo/semantics/publishedVersio

    Limited value of 18F-FDG PET/CT and S-100B tumour marker in the detection of liver metastases from uveal melanoma compared to liver metastases from cutaneous melanoma

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    PURPOSE: The objective of this study was to evaluate the value of (18)F-FDG PET/CT and S-100B tumour marker for the detection of liver metastases from uveal melanoma in comparison to liver metastases from cutaneous melanoma. METHODS: A retrospective evaluation was conducted of 27 liver metastases in 13 patients with uveal melanoma (UM) (mean age: 56.8, range: 30-77) and 43 liver metastases in 14 patients (mean age: 57.9, range: 40-82) with cutaneous melanoma (CM) regarding size and FDG uptake by measuring the maximum standardized uptake value (SUV(max)). S-100B serum tumour markers were available in 20 patients. Cytology, histology, additional morphological imaging and follow-up served as reference standard. In nine patients liver metastases were further evaluated histologically regarding GLUT-1 and S-100 receptor expression and regarding epithelial or spindle cell growth pattern. RESULTS: Of 27 liver metastases in 6 of 13 patients (46%) with UM, 16 (59%) were FDG negative, whereas all liver metastases from CM were positive. Liver metastases from UM showed significantly (p < 0.001) lower SUV(max) (mean: 3.5, range: 1.5-13.4) compared with liver metastases from CM (mean: 6.6, range: 2.3-15.3). In four of six (66.7%) patients with UM and liver metastases S-100B was normal and in two (33.3%) increased. All PET-negative liver metastases were detectable by morphological imaging (CT or MRI). S-100B was abnormal in 13 of 14 patients with liver metastases from CM. S-100B values were significantly higher (p = 0.007) in the CM patient group (mean S-100B: 10.9 microg/l, range: 0.1-115 microg/l) compared with the UM patients (mean: 0.2 microg/l, range: 0.0-0.5 microg/l). Histological work-up of the liver metastases showed no obvious difference in GLUT-1 or S-100 expression between UM and CM liver metastases. The minority (36%) of patients with UM had extrahepatic metastases and the majority (86%) of patients with CM had extrahepatic metastases, respectively. There was a close to significant trend to better survival of UM patients compared with CM patients (p = 0.06). CONCLUSION: FDG PET/CT and serum S-100B are not sensitive enough for the detection of liver metastases from UM, whereas liver metastases from cutaneous melanoma are reliably FDG positive and lead regularly to increased S-100B tumour markers. The reason for the lower FDG uptake in UM liver metastases remains unclear. We recommend to perform combined contrast-enhanced PET/CT in order to detect FDG-negative liver metastases from UM
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