Publications de Thierry Jean Heger

Soil protistology rebooted: 30 fundamental questions to start with

Enrique Lara, Alexandre Jousset, Edward Mitchell, Thierry Jean Heger, Bertrand Fournier, Mariusz Lamentowicz, Santosh Kumar, Vincent Eric Jules Jassey

Protists are the most diverse eukaryotes. These microbes are keystone organisms of soil ecosystems and regulate essential processes of soil fertility such as nutrient cycling and plant growth. Despite this, protists have received little scientific attentio ...

Pergamon-Elsevier Science Ltd2017

Impact of farming practices on soil diatoms and testate amoebae: A pilot study in the DOK-trial at Therwil, Switzerland

Edward Mitchell, Thierry Jean Heger

Testate amoebae (Arcellinida and Euglyphida) and diatoms (Bacillariophyta) respond to different ecological gradients. These protists are useful tools for biomonitoring and paleoecological studies in aquatic and terrestrial ecosystems. However, little is kn ...

2012

COI Barcoding of Nebelid Testate Amoebae (Amoebozoa: Arcellinida): Extensive Cryptic Diversity and Redefinition of the Hyalospheniidae Schultze

Enrique Lara, Edward Mitchell, Thierry Jean Heger

We used Cytochrome Oxidase Subunit 1 (COI) to assess the phylogenetic relationships and taxonomy of Nebela sensu stricto and similar taxa (Nebela group, Arcellinida) in order to clarify the taxonomic validity of morphological characters. The COI data not o ...

2012

COI gene reveals size-dependent high dispersal and low intra-specific diversity in free-living terrestrial protists (Euglyphida; Assulina)

Enrique Lara, Edward Mitchell, Thierry Jean Heger

Aim Propagule size and ecological requirements are believed to be major factors influencing the passive dispersal of free-living terrestrial protists. We compared the colonization potential of three closely related testate amoeba species (Assulina muscoru ...

Wiley-Blackwell2011

Comparing COI and SSU rDNA barcodes for assessing the diversity and phylogenetic relationships of cyphoderiid testate amoebae (Rhizaria: Euglyphida)

Enrique Lara, Edward Mitchell, Thierry Jean Heger

The mitochondrial Cytochrome Oxidase Subunit 1 gene (COI) has been promoted as an ideal “DNA barcode” for animal species and other groups of eukaryotes. However, the utility of the COI marker for species level discrimination and for phylogenetic analyses h ...

2011

Rediscovery of Nebela ansata (Amoebozoa: Arcellinida) in eastern North America: biogeographical implications

Edward Mitchell, Thierry Jean Heger

Aim The question whether free-living protists are generally cosmopolitan is currently a matter of debate. In this study we investigate the geographical distribution of a distinctive testate amoeba species, Nebela ansata, and use our data to assess the pote ...

2011

Biogeography, Evolution and Diversity of Free-Living Protists : Insights from Testate Amoebae

Thierry Jean Heger

Although widely recognized as essential actors of ecosystem processes and representing a significant part of the Earth's biodiversity, free-living protists are poorly known. Major questions concerning their diversity, ecology, and evolution remain complete ...

EPFL2010

Molecular phylogeny of euglyphid testate amoebae (Cercozoa: Euglyphida) suggests transitions between marine supralittoral and freshwater/terrestrial environments are infrequent

Enrique Lara, Edward Mitchell, Thierry Jean Heger

Marine and freshwater ecosystems are fundamentally different regarding many biotic and abiotic parameters. The physiological adaptations required for an organism to pass the salinity barrier are considerable. Many eukaryotic lineages are restricted to eith ...

Elsevier2010

The curse of taxonomic uncertainty in biogeographical studies of free-living terrestrial protists: a case study of testate amoebae from Amsterdam Island

Edward Mitchell, Thierry Jean Heger

Aim A current debate in microbial biogeography contrasts two views concerning the distribution of free-living microorganisms. The first view assumes a ubiquitous distribution, while the second view assumes that at least some species have limited geographic ...

2009

Morphology, Biometry, and Taxonomy of Freshwater and Marine Interstitial Cyphoderia (Cercozoa: Euglyphida)

Edward Mitchell, Thierry Jean Heger

Good taxonomy is essential for ecological, biogeographical, and evolutionary studies of any group of organisms. Therefore, we performed detailed light- and scanning electron microscopy (SEM) investigations on the shell ultrastructure and biometric analyses ...

2009

Ribosomal RNA Genes Challenge the Monophyly of the Hyalospheniidae (Amoebozoa: Arcellinida)

Enrique Lara, Edward Mitchell, Thierry Jean Heger, Mariusz Lamentowicz

To date only five partial and two complete SSU rRNA gene sequences are available for the lobose testate amoebae (Arcellinida). Consequently, the phylogenetic relationships among taxa and the definition of species are still largely dependant on morphologica ...

2008

SSU rRNA reveals a sequential increase in shell complexity among the Euglyphid testate amoebae (Rhizaria: Euglyphida)

Enrique Lara, Edward Mitchell, Thierry Jean Heger

2007

Living specimen tomography by digital holographic microscopy: morphometry of testate amoeba

Tristan Colomb, Christian Depeursinge, Pierre Marquet, Florian Charrière, Nicolas Pavillon, Edward Mitchell, Benjamin Rappaz, Thierry Jean Heger

This paper presents an optical diffraction tomography technique based on digital holographic microscopy. Quantitative 2-dimensional phase images are acquired for regularly-spaced angular positions of the specimen covering a total angle of π, allowing to bu ...

2006

Microclimatic factors influencing refugium suitability for Rhodnius prolixus

Thierry Jean Heger

Rehydration in the triatomine bug Rhodnius prolixus (Stal) is dependent on the blood meal, and water balance regulation is crucial for survival of starving bugs. In an experimental arena with zones at different climatic conditions, starved R. prolixus nymp ...

2006