Thomas Stach

Humboldt-Universität zu Berlin | HU Berlin · Department of Biology

The planktonic Oikopleura dioica belongs to Tunicata, the probable sister taxon to Craniota, and might show plesiomorphic characters, conserved from the common lineage of Tunicata and Craniota. In O. dioica a pericardium in a position similar to other chordates but also to the heart and pericardium of craniates is found. Surprisingly, little is kno...

Like all macroorganisms, plants have to control bacterial biofilm formation on their surfaces. On the other hand, biofilms are highly tolerant against antimicrobial agents and other stresses. Consequently, biofilms are also involved in human chronic infectious diseases, which generates a strong demand for anti-biofilm agents. Therefore, we systemat...

While cellulose is the most abundant macromolecule in the biosphere, most animals are unable to produce cellulose with the exception of tunicates. Some tunicates have evolved the ability to secrete a complex house containing cellulosic fibers, yet little is known about the early stages of the house building process. Here, we investigate the rudimen...

Purpose A ventral heart positioned posterior to the branchial basket and equipped with a pericardium is homologous in tunicates and their sister group, the craniates, yet the tunicate model organism Ciona intestinalis features a pericardial body, a structure peculiar to few ascidian species. Here, we set out to distinguish between two competing hyp...

1 | ZOOLOGY 2 .0 - CAREFUL READING ADVISED With The Invertebrate Tree of Life, eminent scholars Gonzalo Giribet and Gregory D. Edgecombe bring a diversified and boundless field into the 21st century: Comparative Zoology-quite often regarded as outmoded and dusty-is refreshingly updated and rejuvenated. Compiling, consolidating, connecting the lates...

Malaria parasites are fast replicating unicellular organisms and require substantial amounts of folate for DNA synthesis. Despite the central role of this critical co-factor for parasite survival, only little is known about intraparasitic folate trafficking in Plasmodium. Here, we report on the expression, subcellular localisation and function of t...

Like all macroorganisms, plants have to control bacterial biofilm formation on their surfaces. On the other hand, biofilms are highly tolerant against antimicrobial agents and other stresses. Consequently, biofilms are also involved in human chronic infectious diseases, which generates a strong demand for anti‐biofilm agents. Therefore, we systemat...

With approximately 3000 marine species, Tunicata represents the most disparate subtaxon of Chordata. Molecular phylogenetic studies support Tunicata as sister taxon to Craniota, rendering it pivotal to understanding craniate evolution. Although successively more molecular data have become available to resolve internal tunicate phylogenetic relation...

During blood-stage development, malaria parasites are challenged with the detoxification of enormous amounts of heme released during the proteolytic catabolism of erythrocytic hemoglobin. They tackle this problem by sequestering heme into bioinert crystals known as hemozoin. The mechanisms underlying this biomineralization process remain enigmatic....

Cladistics Cladistics Cover image: Tunicates comprise roughly 3000 species, most of which are sessile ascidians. In the fi rst cladistic analysis of morphological characters for Tunicata, Braun et al. show that these phenotypic characters by themselves support-concordant with molecular phylogenies-the planktonic appendicularians as sister group to...

Cladistics Cover image: Tunicates comprise roughly 3000 species, most of which are sessile ascidians. In the fi rst cladistic analysis of morphological characters for Tunicata, Braun et al. show that these phenotypic characters by themselves support-concordant with molecular phylogenies-the planktonic appendicularians as sister group to the remaini...

During blood stage development, malaria parasites are challenged with the detoxification of enormous amounts of haem released during the proteolytic catabolism of erythrocytic haemoglobin. They tackle this problem by sequestering haem into bioinert crystals known as haemozoin. The mechanisms underlying this biomineralization process remain enigmati...

Development in the colonial ascidian genus Diplosoma is unusual in producing two zooids already during the free-swimming larval period. The development of D. listerianum had been investigated in two studies. The present study reports embryonic development of a second species D. migrans. In D. migrans the pharynx of the oozooid develops from two sep...

We report the occurrence of Pyura gangelion (Savigny, 1816) from two sites in the Persian Gulf and its morphological description is also provided. This species has a wide distribution in the Indian and Pacific oceans as well as the Red Sea region. However, no record is available on its distribution in the Persian Gulf. The species is distinguished...

With approximately 3000 marine species, Tunicata represents the most disparate subtaxon of Chordata. Molecular phylogenetic studies support Tunicata as sister taxon to Craniota, rendering it pivotal to understanding craniate evolution. Although successively more molecular data have become available to resolve internal tunicate phylogenetic relation...

Thaliacea are marine planktonic animals within the taxon Tunicata. The species-poor taxon is characterized by diverse life cycles, with sexually (blastozooid) and asexually (oozooid) reproducing generations, that usually evolved polymorph phenotypes. While recent molecular phylogenetic studies indicate that tunicates might be closest living relativ...

Tunicata, comprising approximately 3,000 marine invertebrate species, has recently been proposed to be the sister taxon to Craniota. Phylogenetic interrelationships of higher tunicate taxa are controversial, and it remains unclear whether traces of a fishlike ancestor with an active mode of life can be found in present‐day tunicates. To answer this...

We investigated the cns of different tunicate species, belonging to the five major groups, utilizing light microscopical serial sections for 3d-reconstructions and immunohistochemical stainings with antibodies against tyrosinated-α-tubulin. While neuroanatomical characters in ascidians are comparable, the morphology of the cns of some planktonic tu...

Salps are marine planktonic chordates that possess an obligatory alternation of reproductive modes in subsequent generations. Within tunicates, salps represent a derived life cycle and are of interest in considerations of the evolutionary origin of complex anatomical structures and life history strategies. In the present study, the eyes and brains...

An international and interdisciplinary conference that offers insight and room for discussion of the simple question: what is active and what is passive? The conference is held on February 16th & 17th and is hosted by the Cluster of Excellence - Image Knowledge Gestaltung of the Humboldt-Universität zu Berlin Location: Sophienstr. 22a, 10178 Berli...

Tunicates are part of this extraordinary exhibition organized by the cluster of excellence IMAGE, KNOWLEDGE, GESTALTUNG. The exhibition showcases the interdisciplinary work of 300 people from about 40 disciplines as different as art, natural sciences, design, architecture, philosophy, humanities, and many more. And dear to my heart, you can immerse...

As one of the three major chordate taxa, the highly diverse taxon, Tunicata has always played a key role in considerations of evolutionary origins of vertebrates, especially since several larger-scaled molecular phylogenetic analyses support the hypothesis that tunicates are the sister group to vertebrates. Molecular phylogenetic studies of the rel...

Background: Understanding the evolution of divergent developmental trajectories requires detailed comparisons of embryologies at appropriate levels. Cell lineages, the accurate visualization of cleavage patterns, tissue fate restrictions, and morphogenetic movements that occur during the development of individual embryos are currently available fo...

The cosmopolitan ascidian Ciona intestinalis is the most common model species of Tuni-cata, the sister-group of Vertebrata, and widely used in developmental biology, genomics and evolutionary studies. Recently, molecular studies suggested the presence of cryptic species hidden within the C. intestinalis species, namely C. intestinalis type A and ty...

Enteropneusts or acorn worms are marine deutero-stomes that have retained many plesiomorphic characters. Thus, enteropneusts are of prime interest in evolutionary comparisons between deuterostomes and protostomes. In the present study, the larval eyes of Glossobalanus marginatus were reconstructed and described based on serial sectioning for transm...

Concerning the evolution of deuterostomes, enteropneusts (acorn worms) occupy a pivotal role as they share some characteristics with chordates (e.g., tunicates and vertebrates) but are also closely related to echinoderms (e.g., sea urchin). The nervous system in particular can be a highly informative organ system for evolutionary inferences, and ad...

In a recent review in BioScience , Ronald A. Jenner declared the quest for the branching pattern of the animal tree of life essentially completed, pointed out obstacles for an understanding of evolutionary transformations, and appealed to “more or less informed imagination” to fill gaps (Jenner 2014). Jenner singled out two disciplines that could c...

Comparison of features of the cell lineages and fate maps of early embryos between related species is useful in inferring developmental mechanisms and amenable to evolutionary considerations. We present cleavage patterns, cell lineage trees, and fate maps of ascidian and appendicularian embryos side by side to facilitate comparison. This revealed a...

Salpida is a high-ranking taxon within Tunicata comprising approximately fifty species in twelve genera. All species are exclusively marine and planktonic. Due to their extraordinary rate of growth and their efficient filter feeding they play an important ecological role. Salps are characterized by a strictly metagenetic life cycle consisting o...

3D-pdf-version of Figure 10 is also deposited on MorphDBase.de (3D-features accessible in Adobe Reader 9.0 and higher): MDB Acc.-No.: T_Stach_EDIT-M-5.1

Deuterostomia is one of the major monophyletic groups in the animal kingdom. Interest in deuterostome evolution stems from the diversity of life cycles and anatomies present in this group and moreover from the fact that vertebrates are part of Deuterostomia. Phylogeny is a prerequisite for the understanding of evolution. In the present review I cri...

Pterobranchs have been interpreted as "missing links" combining primitive invertebrate features with advanced vertebrate-like characteristics. The first detailed morphological description of an ontogenetic stage of a pterobranch, based on digital 3D-reconstruction at electron microscopic resolution, reveals a triploblastic animal with monociliated...

Traditionally, the origin of the third germ layer and its special formation of coelomic cavities by enterocoely is regarded to be an informative character in phylogenetic analyses. In early deuterostomes such as sea urchins, the mesoderm forms through a single evagination pinching off from the apical end of the archenteron which then gives off meso...

Cephalodiscus gracilis Harmer, 1905 is a semisessile deuterostome that shares with fish-like chordates pharyngeal gill slits and a dorsally situated brain. In order to reveal structures potentially homologous among deuterostomes and to infer their functional roles, we investigated the axial complex, associated blood vessels and structures of C. gra...

Background Hair cells are vertebrate secondary sensory cells located in the ear and in the lateral line organ. Until recently, these cells were considered to be mechanoreceptors exclusively found in vertebrates that evolved within this group. Evidence of secondary mechanoreceptors in some tunicates, the proposed sister group of vertebrates, has rec...

A new tunicate, Ascidia subterranea sp. nov., was found in burrows of the axiid crustacean Axiopsis serratifrons on De-rawan Island, Indonesia. It differs from other ascidians in its habitat as well as numerous morphological peculiarities which are described in detail. The shrimp Rostronia stylirostris Holthuis, 1952 was found inside A. subterranea...

A new tunicate, Ascidia subterranea sp. nov., was found in burrows of the axiid crustacean Axiopsis serratifrons on De-rawan Island, Indonesia. It differs from other ascidians in its habitat as well as numerous morphological peculiarities which are described in detail. The shrimp Rostronia stylirostris Holthuis, 1952 was found inside A. subterranea...

The sea urchin (Echinodermata: Echinoidea) masticatory apparatus, or Aristotle's lantern, is a complex structure composed of numerous hard and soft components. The lantern is powered by various paired and unpaired muscle groups. We describe how one set of these muscles, the lantern protractor muscles, has evolved a specialized morphology. This morp...

Nervous systems are important in assessing interphyletic phylogenies because they are conservative and complex. Regarding nervous system evolution within deuterostomes, two contrasting hypotheses are currently discussed. One that argues in favor of a concentrated, structured, central nervous system in the last common ancestor of deuterostomes (LCAD...

Many invertebrates reproduce asexually by budding, but morphogenesis and the role of cell proliferation in this diverse and nonconserved regeneration-like process are generally poorly understood and particularly little investigated in didemnid ascidians. We here analyzed cell proliferation patterns and telomerase activity during budding in the colo...

The origin of mesoderm and coelomic compartments has traditionally been given high value for phylogenetic considerations of animal relationships. Two main modes have been distinguished, associated with the two main groups of animals: schizocoely with protostomes and enterocoely with deuterostomes. During enterocoely, coelomic compartments are forme...

Stach, T. and Kaul, S. 2011. The postanal tail of the enteropneust Saccoglossus kowalevskii is a ciliary creeping organ without distinct similarities to the chordate tail. —Acta Zoologica (Stockholm) 92: 150–160. The postanal tail of chordates is one of the key characters in chordate evolution and it has been suggested to be homologous to the posta...

Invertebrate nervous systems are highly disparate between different taxa. This is reflected in the terminology used to describe them, which is very rich and often confusing. Even very general terms such as 'brain', 'nerve', and 'eye' have been used in various ways in the different animal groups, but no consensus on the exact meaning exists. This im...

The chordate body plan is characterized by a central notochord, a pharynx perforated by gill pores, and a dorsal central nervous system. Despite progress in recent years, the evolutionary origin of each of theses characters remains controversial. In the case of the nervous system, two contradictory hypotheses exist. In the first, the chordate nervo...

The molecular phylogenetic position of Tunicata and internal interrelationship of higher tunicate taxa is controversial. High substitution rates and extreme gene order variability hamper phylogenetic analyses. We describe the sequence and organization of the mitochondrial genome of the aplousobranch ascidian Clavelina lepadiformis and use mitochond...

Abstract Background: Invertebrate nervous systems are highly disparate between different taxa. This is reflected in the terminology used to describe them, which is very rich and often confusing. Even very general terms such as ‘brain’, ‘nerve’, and ‘eye’ have been used in various ways in the different animal groups, but no consensus on the exact me...

Ecteinascidia turbinata is a colonial ascidian that as an adult shares characters with phlebobranch ascidians, whereas the larvae are similar to aplousobranch ascidian larvae. The sarcotubular complex consists of invaginations of the sarcolemma that contact the sarcoplasmatic reticulum via dyads or triads. If present, the invaginations of the sarco...

The tadpole stage of tunicates has played a pivotal role in understanding chordate evolution. While the organization of the mesoderm has been given high importance in comparative anatomical studies of Bilateria, this morphological character remains largely unexplored in tunicate tadpoles. For larvae of the phlebobranch ascidian Ciona intestinalis,...

Stach, T. and Kaul, S. 2011. The postanal tail of the enteropneust Saccoglossus kowalevskii is a ciliary creeping organ without distinct similarities to the chordate tail. — Acta Zoologica (Stockholm) 92: 150–160. The postanal tail of chordates is one of the key characters in chordate evolution and it has been suggested to be homologous to the post...