Publications by authors named "Sebastian Hess"

Protists show diverse lifestyles and fulfill important ecological roles as primary producers, predators, symbionts, and parasites. The degradation of dead microbial biomass, instead, is mainly attributed to bacteria and fungi, while necrophagy by protists remains poorly recognized. Here, we assessed the food range specificity and feeding behavior of the algivorous flagellate Orciraptor agilis (Viridiraptoridae, Cercozoa) with a large-scale feeding experiment.

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The vampire amoebae (Vampyrellida, Rhizaria) inhabit freshwater, marine, and terrestrial ecosystems and consume a wide range of eukaryotic prey. This includes diverse microalgae, fungi, and microscopic animals. One of the most captivating aspects of the vampyrellids is their ability to extract the cell contents of other eukaryotes after local dissolution of the prey cell wall, a feeding strategy that occurs in several vampyrellid families, but is best studied in species that attack zygnematophyte green algae.

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The green algae of the genus Ancylonema, which belong to the zygnematophytes, are prevalent colonizers of glaciers worldwide. They display a striking reddish-brown pigmentation in their natural environment, due to vacuolar compounds related to gallic acid. This pigmentation causes glacier darkening when these algae bloom, leading to increased melting rates.

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Chemical pollution is one of the most important threats to freshwater ecosystems. The plethora of potentially occurring chemicals and their effects in complex mixtures challenge standard monitoring methods. Effect-based methods (EBMs) are proposed as complementary tools for the assessment of chemical pollution and toxic effects.

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The zygnematophytes are the closest relatives of land plants and comprise several lineages that adapted to a life on land. Species of the genus Serritaenia form colorful, mucilaginous capsules, which surround the cells and block harmful solar radiation, one of the major terrestrial stressors. In eukaryotic algae, this 'sunscreen mucilage' represents a unique photoprotective strategy, whose induction and chemical background are unknown.

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Vampyrellid amoebae are predatory protists, which consume a variety of eukaryotic prey and inhabit freshwater, marine and terrestrial ecosystems. Although they have been known for almost 150 years, much of their diversity lacks an in-depth characterization. To date, environmental sequencing data hint at several uncharacterized lineages, to which no phenotype is associated.

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Multiple stressors affect freshwater systems and cause a deficient ecological status according to the European Water Framework Directive (WFD). To select effective mitigation measures and improve the ecological status, knowledge on the stressor hierarchy and individual and joined effects is necessary. However, compared to common stressors like nutrient enrichment and morphological degradation, the relative importance of micropollutants such as pesticides and pharmaceuticals is largely unaddressed.

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Muñoz-Gómez and Hess introduce purple photosymbioses, which involve a heterotrophic protist host and anoxygenic photosymbionts from the phylum Proteobacteria.

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Background: Several protists have evolved the ability to perforate the cell walls of algae and fungi to specifically feed on their cell contents. These phagotrophic "protoplast feeders" represent an interesting mechanistic intermediate between predators and parasites and pose a number of cell biological questions. Although their fascinating feeding behaviour has been observed for the last 150 years, it is still unknown how protoplast feeders produce the well-defined and species-specific perforations in biochemically diverse cell walls.

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Unlabelled: To determine efficacy and prognostic parameters of definitive re-irradiation of locoregionally recurrent squamous cell carcinoma of the head and neck (HNSCC).

Materials And Methods: Patients with locoregionally recurrent or second primary HNSCC undergoing re-irradiation with modern radiotherapy technique were eligible for this multicentric retrospective analysis. Main endpoints were overall survival (OS), progression-free survival (PFS) and locoregional control (LC).

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The evolution of streptophytes had a profound impact on life on Earth. They brought forth those photosynthetic eukaryotes that today dominate the macroscopic flora: the land plants (Embryophyta). There is convincing evidence that the unicellular/filamentous Zygnematophyceae-and not the morphologically more elaborate Coleochaetophyceae or Charophyceae-are the closest algal relatives of land plants.

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Microbial eukaryotes display a stunning diversity of feeding strategies, ranging from generalist predators to highly specialized parasites. The unicellular "protoplast feeders" represent a fascinating mechanistic intermediate, as they penetrate other eukaryotic cells (algae and fungi) like some parasites but then devour their cell contents by phagocytosis. Besides prey recognition and attachment, this complex behavior involves the local, pre-phagocytotic dissolution of the prey cell wall, which results in well-defined perforations of species-specific size and structure.

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Milk concentrates are used in the manufacturing of dairy products such as yogurt and cheese or are processed into milk powder. Processes for the nonthermal separation of water and valuable milk ingredients are becoming increasingly widespread at farm level. The technical barriers to using farm-manufactured milk concentrate in dairies are minimal, hence the suspicion that the practice of on-farm raw milk concentration is still fairly uncommon for economic reasons.

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Greater differentiation is being made between types of milk according to product and process characteristics. This study investigated consumer preferences for 4 different types of milk in packaging-blind and nonblind experiments. The taste of long-life milk, conventional fresh whole milk, pasture-based milk, and organic milk was assessed by 138 randomly selected respondents.

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The Vampyrellida (Endomyxa, Rhizaria) is a group of free-living, predatory amoebae, which is most closely related to the Phytomyxea (plasmodiophorids and phagomyxids). It encompasses about 50 credibly described species that have a characteristic life history with the regular alternation of trophic amoebae and immobile digestive cysts. All known vampyrellid amoebae are naked and filose, but the different species display a broad morphological variety.

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Weathering of plastics leads to the formation of increasingly smaller particles with the release of chemical compounds. The latter occurs with currently unknown environmental impacts. Leachate-induced effects of weathered microplastics (MPs) are therefore of increasing concern.

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The Cutosea represent a deep-branching lineage within the phylum Amoebozoa that is still relatively poorly explored. Currently, there are four cutosean representatives known - the monotypic genera Armaparvus, Idionectes, Sapocribrum, and Squamamoeba - with marked genetic distances. Idionectes vortex is the deepest-branching species and differs markedly from the other Cutosea in ecology, life history, and most importantly, in its ability to form a flagellated swarmer with an exceptional swimming mechanism.

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The ingestion of microplastics (MPs) is well documented for various animals and spherical MPs (beads) in many studies. However, the retention time and egestion of MPs have been examined less, especially for irregular MPs (fragments) which are predominantly found in the environment. Furthermore, the accumulation of such particles in the gastrointestinal tract is likely to determine whether adverse effects are induced.

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The vampyrellids (Vampyrellida, Rhizaria) are naked amoebae of considerable genetic diversity. Three families have been well-defined (Vampyrellidae, Leptophryidae, and Placopodidae), but most vampyrellid lineages detected by environmental sequencing are poorly known or completely uncharacterized. In the brackish sediment of Lake Bras D'Or, Nova Scotia, Canada, we discovered an amoeba with a vampyrellid-like life history that was morphologically dissimilar from previously known vampyrellid taxa.

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Oxygenic photosynthesizers (cyanobacteria and eukaryotic algae) have repeatedly become endosymbionts throughout evolution. In contrast, anoxygenic photosynthesizers (e.g.

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The present study evaluated very small microplastic particle (MPs) transfer to zebrafish and marine medaka larvae via prey experimentally exposed to MPs from the onset of feeding. Larvae were fed Paramecium or Artemia nauplii loaded with fluorescent 1-5 or 10-20 μm MP. Pollutant accumulation was analyzed by optically tracking of benzo[a]pyrene (BaP) and recording cyp1a transcription.

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Purpose: The aim of our study was the external validation of an extended variant of the four-tiered diagnosis-specific graded prognostic assessment (DS-GPA) that includes more information about extracranial disease burden and blood test results, and predicts survival of patients with brain metastases. The extracranial DS-GPA (EC-GPA) includes serum albumin, lactate dehydrogenase, and number of extracranial organs involved. Originally, the score was developed in Germany.

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Purpose: The aim of our study was an external validation of the extracranial prognostic score predicting survival of patients with brain metastases receiving cranial irradiation on data from a single institution.

Materials And Methods: A retrospective analysis of 524 patients with brain metastases treated with cranial radiotherapy in a single tertiary center was performed. Three predictive scores were calculated and assessed for their ability to discriminate prognostic groups: (i) The Recursive Partitioning Analysis (RPA) score (available for 524 patients); (ii) the Diagnosis-Specific Graded Prognostic Assessment (DS-GPA) score (464 patients); (iii) the extracranial score (EC-S) developed by Nieder et al.

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Article Synopsis
  • Eukaryotic ecology mainly relies on oxygenic photosynthesis, driven by chlorophylls, which can be both beneficial for energy harvesting and harmful due to reactive oxygen species.
  • The research shows that a widespread process called chlorophyll catabolism converts chlorophylls into non-toxic forms (CPEs) among various microeukaryotes, except for Archaeplastida.
  • This catabolism likely evolved in algivorous microeukaryotes to detoxify chlorophylls and played a crucial role in photosynthetic endosymbiosis, enabling the diversification of eukaryotes following increased oxygen levels in the environment.
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