92 research outputs found

    Phylogenetic placement of environmental sequences using taxonomically reliable databases helps to rigorously assess dinophyte biodiversity in Bavarian lakes (Germany).

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    1. Reliable determination of organisms is a prerequisite to explore their spatial and temporal occurrence and to study their evolution, ecology, and dispersal. In Europe, Bavaria (Germany) provides an excellent study system for research on the origin and diversification of freshwater organisms including dinophytes, due to the presence of extensive lake districts and ice age river valleys. Bavarian freshwater environments are ecologically diverse and range from deep nutrient‐poor mountain lakes to shallow nutrient‐rich lakes and ponds. 2. We obtained amplicon sequence data (V4 region of small subunit‐rRNA, c. 410 bp long) from environmental samples collected at 11 sites in Upper Bavaria. We found 186 operational taxonomic units (OTUs) associated with Dinophyceae that were further classified by means of a phylogenetic placement approach. 3. The maximum likelihood tree inferred from a well‐curated reference alignment comprised a systematically representative set of 251 dinophytes, covering the currently known molecular diversity and OTUs linked to type material if possible. Environmental OTUs were scattered across the reference tree, but accumulated mostly in freshwater lineages, with 79% of OTUs placed in either Apocalathium, Ceratium, or Peridinium, the most frequently encountered taxa in Bavaria based on morphology. 4. Twenty‐one Bavarian OTUs showed identical sequences to already known and vouchered accessions, two of which are linked to type material, namely Palatinus apiculatus and Theleodinium calcisporum. Particularly within Peridiniaceae, delimitation of Peridinium species was based on the intraspecific sequence variation. 5. Our approach indicates that high‐throughput sequencing of environmental samples is effective for reliable determination of dinophyte species in Bavarian lakes. We further discuss the importance of well‐curated reference databases that remain to be developed in the future

    Strict selection alone of patients undergoing liver transplantation for hilar cholangiocarcinoma is associated with improved survival

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    Liver transplantation for hilar cholangiocarcinoma (hCCA) has regained attention since the Mayo Clinic reported their favorable results with the use of a neo-adjuvant chemoradiation protocol. However, debate remains whether the success of the protocol should be attributed to the neo-adjuvant therapy or to the strict selection criteria that are being applied. The aim of this study was to investigate the value of patient selection alone on the outcome of liver transplantation for hCCA. In this retrospective study, patients that were transplanted for hCCA between1990 and 2010 in Europe were identified using the European Liver Transplant Registry (ELTR). Twenty-one centers reported 173 patients (69%) of a total of 249 patients in the ELTR. Twenty-six patients were wrongly coded, resulting in a study group of 147 patients. We identified 28 patients (19%) who met the strict selection criteria of the Mayo Clinic protocol, but had not undergone neo-adjuvant chemoradiation therapy. Five-year survival in this subgroup was 59%, which is comparable to patients with pretreatment pathological confirmed hCCA that were transplanted after completion of the chemoradiation protocol at the Mayo Clinic. In conclusion, although the results should be cautiously interpreted, this study suggests that with strict selection alone, improved survival after transplantation can be achieved, approaching the Mayo Clinic experience

    (Table T1) Relative abundance of diatoms in ODP Hole 169-1034B sediments

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    Ocean Drilling Program (ODP) Site 1034 (48°38.000'N, 123°30.000'W) was drilled at a water depth of 200 m in the Saanich Inlet, an anoxic fjord on the southeastern coast of Vancouver Island, British Columbia, to a depth of 118.2 meters below seafloor (mbsf). The uppermost 50 m consists of very well-laminated (triplet varves) diatomaceous muds deposited over the past 7000 yr. Below, sediments become progressively less distinctly laminated and reflect better oxygenated bottom-water conditions. The oldest sediments recovered at Site 1034 were dated as 14 to 15 ka (see Shipboard Scientific Party, 1998, doi:10.2973/odp.proc.ir.169s.1998). Varved sediments recovered during Leg 169S in the Saanich Inlet offer an excellent opportunity to compare the interannual variability of recent climatic elements (e.g., sea-surface temperature, salinity, precipitation) with those of late Quaternary periods that were characterized by climates appreciably different from those of today. A large amount of recent diatom data from Saanich Inlet exists, which can serve as a baseline for such comparisons: Sancetta (1989a, doi:10.1029/PA004i003p00235; 1989b, doi:10.1093/plankt/11.3.503; 1990) investigated modern processes controlling the accumulation of diatoms and spacial and temporal trends of diatom flux in the Inlet; Sancetta and Calvert (1988, doi:10.1016/0198-0149(88)90058-1) documented the annual cycle of sedimentation in the fjord. McQuoid (1995) and McQuoid and Hobson (1997, doi:10.1093/plankt/19.2.173) studied the modern pattern of diatom succession in the Saanich Inlet and analyzed the diatoms in laminae couplets in frozen sediment cores for the years 1900 to 1991 A.D. This report describes the intra-annual variability of the diatom assemblages at Site 1034, during a 8-yr interval near 9 ka. Pollen and dinoflagellates are being studied from the same samples by R. Hebda and P. Mudie (unpubl. data)

    Oligocene and lowermost Miocene diatom stratigraphy and datums of ODP Site 199-1220 sediments

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    Completion of studies on material collected during Ocean Drilling Program Leg 199 at Site 1220 in the equatorial Pacific allows calibration of the ranges of >35 stratigraphically important diatoms to paleomagnetic stratigraphy for the Oligocene and earliest Miocene (~33.5-21.5 Ma). The taxonomy of these taxa is reviewed, and age estimates of their first and last occurrences are compiled. The diatom zonation for the Oligocene and earliest Miocene of the equatorial Pacific is revised and correlated with paleomagnetic stratigraphy. This biostratigraphy is likely to be applicable throughout the low-latitude regions of the world's oceans
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