Bánk Beszteri

University of Duisburg-Essen | uni-due · Phycology

The Southern Ocean is characterized by longitudinal water circulations crossed by strong latitudinal gradients. How this oceanographic background shapes planktonic populations is largely unknown, despite the significance of this region for global biogeochemical cycles. Here we show , based on genomic, morphometric, ecophysiological and mating compa...

Deep convolutional neural networks are emerging as the state of the art method for supervised classification of images also in the context of taxonomic identification. Different morphologies and imaging technologies applied across organismal groups lead to highly specific image domains, which need customization of deep learning solutions. Here we p...

Plants, fungi and algae are important components of global biodiversity and are fundamental to all ecosystems. They are the basis for human well-being, providing food, materials and medicines. Specimens of all three groups of organisms are accommodated in herbaria, where they are commonly referred to as botanical specimens. The large number of spec...

Salinization and warming are of increasing concern for freshwater ecosystems. Interactive effects of stressors are often studied in bifactorial, two-level experimental setups. The shape of environmental reaction norms and the position of the “control” conditions along them, however, can influence the sign and magnitude of individual responses as we...

Climate has strongly influenced species composition and evolution over geological and contemporary timescales. While most attention has been paid to the relationship between macroevolutionary processes and climate along latitudinal gradients, very little is known about how climate changes affect the microevolutionary mechanisms of macroevolutionary...

Combining morphological and molecular approaches, a new diatom species is described in the genus Mayamaea from a Special Nature Reserve, Okanj bara in Serbia, an alkaline and subsaline soda pan with pronounced seasonal drying. Mayamaea pannonica sp. nov. possesses typical characteristics of the genus Mayamaea, such as uniseriate striae and hymenes...

Diatoms represent one of the morphologically and taxonomically most diverse groups of microscopic eukaryotes. Light microscopy-based taxonomic identification and enumeration of frustules, the silica shells of these microalgae, is broadly used in aquatic ecology and biomonitoring. One key step in emerging digital variants of such investigations is s...

Our capacity to predict trajectories of ecosystem degradation and recovery is limited, especially when impairments are caused by multiple stressors. Recovery may be fast or slow and either complete or partial, sometimes result in novel ecosystem states or even fail completely. Here, we introduce the Asymmetric Response Concept (ARC) that provides a...

Diatom identification and counting by light microscopy of permanently embedded acid-cleaned silicate shells (frustules) is a fundamental method in ecological and water quality investigations. Here we present a new variant of this method based on “digital virtual slides”, and compare it to the traditional, non-digitized light microscopy workflow on...

Diatom identification and counting by light microscopy is a fundamental method in ecological and water quality investigations. Here we present a new variant of this method based on “digital virtual slides”, and compare it to the traditional, non-digitized light microscopy workflow. We analysed three replicates of six samples using two methods: 1) w...

Diatoms represent one of the morphologically and taxonomically most diverse groups of microscopic eukaryotes. Light microscopy-based taxonomic identification and enumeration of frustules, the silica shells of these microalgae, is broadly used in aquatic ecology and biomonitoring. One key step in emerging digital variants of such investigations is s...

Zinc is an essential trace metal for oceanic primary producers with the highest concentrations in polar oceans. However, its role in the biological functioning and adaptive evolution of polar phytoplankton remains enigmatic. Here, we have applied a combination of evolutionary genomics, quantitative proteomics, co-expression analyses and cellular ph...

Viruses are highly diverse biological entities shaping many ecosystems across Earth. However, understanding the infection of individual microbial cells and the related biochemical changes remains limited.

Raman microspectroscopy has been thoroughly used to assess growth dynamics and heterogeneity of prokaryotic cells. Yet, little is known about how the chemistry of individual cells changes during infection with lytic viruses, resulting in so-called virocells. Here, we investigate biochemical changes of bacterial and archaeal cells of three different...

Eukaryotic phytoplankton are responsible for at least 20% of annual global carbon fixation. Their diversity and activity are shaped by interactions with prokaryotes as part of complex microbiomes. Although differences in their local species diversity have been estimated, we still have a limited understanding of environmental conditions responsible...

This volume includes papers covering a broad range of topics in diatom and chrysophyte research - including historical analyses of taxa names and name changes - through descriptions of novel taxa; observations of fine details of valve and cell morphology and ultrastructure, in many cases in an ecological and/or biostratigraphic context; to atte...

In a response to changes in the environment, species can adapt to the conditions by changing their phenotype, physiology and/or behaviour. This can also be expected in diatoms, particularly in planktonic species, because of their short generation times and high sensitivity to environmental changes. Sediments from ancient lakes dating back several m...

The marine waters around the South Shetland Islands are paramount in the primary production of this Antarctic ecosystem. With the increasing effects of climate change and the annual retreat of the ice shelf, the importance of macroalgae and their diatom epiphytes in primary production also increases. The relationships and interactions between these...

The Southern Ocean is one of the most productive ecosystems in the world. It is an area heavily dependent on marine primary production and serving as a feeding ground for numerous seabirds and marine mammals. Therefore, the phytoplankton composition and presence of toxic species are of crucial importance. Fifteen monoclonal strains of Pseudo-nitzsc...

It has been shown that size of planktonic diatoms responds to changes in water chemistry, but little is known about the influence of different types of environmental factors upon benthic diatom size variation. Here we ask whether water chemistry or hydromorphological influences show a stronger effect on benthic diatom morphometry. 10,624 diatom val...

Natural history collections are leading successful large-scale projects of specimen digitization (images, metadata, DNA barcodes), transforming taxonomy into a big data science. Yet, little effort has been directed towards safeguarding and subsequently mobilizing the considerable amount of original data generated during the process of naming 15-20,...

Zusammenfassung Der Klimawandel mit Temperaturerhöhung und Ozeanversauerung wird dramatische Auswirkungen auf das planktische Leben im Südpolarmeer haben. Unsere Studien zeigen, dass das Plankton im Südozean bereits im Wandel ist. Während heutzutage größere Diatomeen (Kieselalgen) die wichtigsten Primärproduzenten im Südpolarmeer sind, könnte es in...

The ability to rapidly generate and share molecular, visual, and acoustic data, and to compare them with existing information, and thereby to detect and name biological entities is fundamentally changing our understanding of evolutionary relationships among organisms and is also impacting taxonomy. Harnessing taxonomic data for rapid, automated spe...

Some aspects of the life cycle of the Southern Ocean diatom Fragilariopsis kerguelensis have been investigated previously, but many of its details have not been surveyed in nature. We investigated material from a two-year sediment trap time series by high-throughput imaging and image analysis, looking for morphometric signals of life cycle stages....

Fragilariopsiskerguelensis (O’ Meara) Hust. is a ubiquitous diatom of the Southern Ocean. Its thick frustules are the numerically dominant component of the siliceous sediment layer covering large parts of the seafloor beneath. Morphometric variability of frustules of this diatom has been of interest for paleoenvironmental reconstructions. Recently,...

Figure S3. Relationship between valve width and apical length shows a much clearer separation than aspect ratio, and substantially less dependence on apical length.

Table S2. Valve width ranges of the three species when considering (a) only specimens identified in full agreement (unequivocal); (b) specimens identified as belonging to the species considered by the majority of participants (majority); and (c) by any single participant (single vote).

Figure S1. Validation of striae density measurement by SHERPA (on the x‐axis) versus measured manually (on the y‐axis). Black line: y=x. Red line: least squares regression line.

Figure S2. Dependence of identification agreement on apical valve length. The gray line represents the percentage of specimens within a 10 μm broad apical length range which received at least 90% identical taxonomic labels; the black dotted line depicts the absolute number of these cases within the 10 μm size window. The solid black line depicts th...

Figure S4. Eccentricity of the broadest valve position along the apical axis hardly depends on apical length, and is slightly higher (away from 0.5 on the y‐axis) in Fragilariopsis ritscheri than in the other two species.

Table S1. Apical valve length ranges of the three species when considering (a) only specimens identified in full agreement (unequivocal); (b) specimens identified as belonging to the species considered by the majority of participants (majority); and (c) by any single participant (single vote).

Table S3. Striae density ranges of the three species when considering (a) only specimens identified in full agreement (unequivocal); (b) specimens identified as belonging to the species considered by the majority of participants giving an identification for that specimen (majority); and (c) by any single participant (single vote).

Fragilariopsis kerguelensis is one of the most abundant diatoms in the sediments of the Southern Ocean. Its morphometric features have been proposed as proxies, based on links with, for example, iron availability, sea surface temperature and glacial/interglacial conditions. We investigated morphometric changes in F. kerguelensis valves in a well-st...

Semi‐automated methods for microscopic image acquisition, image analysis and taxonomic identification have repeatedly received attention in diatom analysis. Less well studied is the question whether and how such methods might prove useful for clarifying the delimitation of species that are difficult to separate for human taxonomists. To try to answ...

The recently established diatom genus Shionodiscus is characterized as possessing a labiate process on the valve face and strutted processes with long internal and reduced, or no, external extensions. Many Thalassiosira species with these features were transferred to this new genus, as well as some with short internal, strutted process extensions....

Light microscopy analysis of diatom frustules is widely used in basic and applied research, notably taxonomy, morphometrics, water quality monitoring and paleo-environmental studies. Although there is a need for automation in these applications, various developments in image processing and analysis methodology supporting these tasks have not become...

This folder contains analysis data from the study published as Article (Manuscript ID TEJP-2014-0106): TITLE: RNA and DNA based assessment of sea ice protist biodiversity of the central Arctic Ocean. AUTHORS: Anique Stecher, Stefan Neuhaus, Benjamin Lange, Stephan Frickenhaus, Bánk Beszteri, Peter Kroth and Klaus Valentin JOURNAL: The European Jour...

(English abstract below) Kurzfassung Optische Technologien und Verfahren sind sowohl in der limnischen als auch marinen Forschung Deutschlands über alle Bereiche und Skalen etabliert und entwickeln sich rasant weiter. Die Arbeitsgruppe „Aquatische Optische Technologien“ (AOT) will Forschern und Anwendern eine Plattform bieten, die Wissenstransfer...

Sea ice is a large and diverse ecosystem contributing significantly to primary production in ice-covered regions. In the Arctic Ocean, sea ice consists of mixed multi-year ice (MYI), often several metres thick, and thinner first-year ice (FYI). Current global warming is most severe in Arctic regions; as a consequence, summer sea ice cover is decrea...

Ice-binding proteins (IBPs) have been isolated from various sea-ice organisms. Their characterisation points to a crucial role in protecting the organisms in sub-zero environments. However, their in situ abundance and diversity in natural sea-ice microbial communities is largely unknown. In this study, we analysed the expression and phylogenetic di...

Vanhoeffenus antarcticus was described by Heinrich Heiden from a net sample taken from 385 m depth by the Gauss expedition (First German Antarctic Expedition) while frozen in pack ice near the Antarctic continent in the austral summer of 1902–3. Valves of this peculiar diatom have only ever been observed in preparations from this locality and only...

A small diatom with a peculiar shape is often identified as Navicula schmassmannii in samples collected from alpine lakes and the Arctic region. Due to its characteristic outline, it is relatively well-identifiable, but scanning electron microscope (SEM) confirmation is essential for proving species identity. This species likely has a palaeoecologi...

Optische Technologien und Verfahren sind sowohl in der limnischen als auch marinen Forschung Deutschlands über alle Bereiche und Skalen etabliert und entwickeln sich rasant weiter. Die Arbeitsgruppe „Aquatische Optische Technologien“ (AOT) will Forschern und Anwendern eine Plattform bieten, die Wissenstransfer fördert, der nationalen Entwicklergeme...

Fragilariopsis kerguelensis, a dominant diatom species throughout the Antarctic Circumpolar Current, is coined to be one of the main drivers of the biological silicate pump. Here, we study the distribution of this important species and expected consequences of climate change upon it, using correlative species distribution modeling and publicly avai...

Background Light microscopic analysis of diatom frustules is widely used both in basic and applied research, notably taxonomy, morphometrics, water quality monitoring and paleo-environmental studies. In these applications, usually large numbers of frustules need to be identified and/or measured. Although there is a need for automation in these appl...

Current sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans.

Background: Light microscopic analysis of diatom frustules is widely used both in basic and applied research, notably taxonomy, morphometrics, water quality monitoring and paleo-environmental studies. In these applications, usually large numbers of frustules need to be identified and / or measured. Although there is a need for automation in these a...

Fragilariopsis kerguelensis, a dominant diatom species throughout the Antarctic Circumpolar Current, is coined to be one of the main drivers of the biological silicate pump. Here, we study the distribution of this important species and expected consequences of climate change upon it, using correlative species distribution modeling and publicly avai...

Advances in next-generation sequencing technologies are providing longer nucleotide sequence reads that contain more information about phylogenetic relationships. We sought to use this information to understand the evolution and ecology of bacterioplankton at our long-term study site in the Western Sargasso Sea. A bioinformatics pipeline called Phy...

Marine dinoflagellates (alveolata) are microalgae of which some cause harmful algal blooms and produce a broad variety of most likely polyketide synthesis derived phycotoxins. Recently, novel polyketide synthesase (PKS) transcripts have been described from the Florida red tide dinoflagellate Karenia brevis (gymnodiniales) which are evolutionarily r...

Presence of KS proteins in A. ostenfeldii and Heterocapsa triquetra. Western blot analysis of protein extracts from A. ostenfeldii AOSH 2 and Heterocapsa triquetra SCCAP strain K-0481 using a polyclonal rabbit anti- K. brevis KS antibody. Note that the size of the labelled polypeptide is consistent with the molecular weight predicted based on the t...

Extended phylogenetic tree of Type I and Type II KS domains from prokaryotic and eukaryotic PKS and FAS. Sixty-eight taxa representing Type I and Type II KS domains were retrieved from NCBI genbank, John et al., 2008 and Lopèz-Legentil et al., 2010 and analyzed by a maximum likelihood approach. Multiple amino acid alignment was performed with the M...

Multiple alignment of Type I and Type II KS domains from prokaryotic and eukaryotic PKS and FAS. Fifty-nine taxa representing Type I and Type II KS domains were in silico translated and aligned using the MUSCLE algoritm included into MEGA 5.0. If no GenBank accession numbers provided information can be get from *John U, Beszteri B, Derelle E, Van d...

Primer collection used to obtain the 5 full length KS transcripts. Method abbreviations: S –Sanger Sequencing; 5′RACE-Rapid amplification of 5′ cDNA ends; 3′RACE-Rapid amplification of 3′ cDNA ends. (DOCX)

Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molec...

Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molec...

Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molec...

There have been few studies of the bacterial community within the bottom boundary layer (BBL)-the turbulent region of the water column above the benthos-in shallow seas. Typically, the BBL has large amounts of particulate organic matter suspended by turbulence, and it is often the first region of the water column to become hypoxic when oxygen decli...

Scanning electron micrographs of thalassiosiroid diatoms in the type material (Additional file 4) of Cyclotella nana (= Thalassiosira pseudonana): Stephanodiscus hantzschii Grunow (A, B), Stephanodiscus minutulus (Kützing) Cleve & Möller (C, D), Discostella pseudostelligera (Hustedt) Houk & Klee (E-H), Cyclotella striata (Kützing) Grunow in Cleve &...

Scanning electron micrographs showing exterior (A, B) and interior (C, D) views of Thalassiosira pseudonana (marine strain NEPC709) from Alverson et al. [25]. Scale bar = 2 μM.

Strict consensus of eight most parsimonious trees from a phylogenetic analysis of 32 morphological characters for select Thalassiosirales.

The nomenclatural history of Thalassiosira pseudonana.

The identity of Thalassiosira pseudonana.

Hustedt's observations on the type locality of Cyclotella nana (= T. pseudonana).

Pairwise differences among Thalassiosira pseudonana culture strains at four loci.

Publication of the first diatom genome, that of Thalassiosira pseudonana, established it as a model species for experimental and genomic studies of diatoms. Virtually every ensuing study has treated T. pseudonana as a marine diatom, with genomic and experimental data valued for their insights into the ecology and evolution of diatoms in the world's...

Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only...