Kinetid structure in larval and adult stages of the demosponges <i>Haliclona aquaeductus</i> (Haplosclerida) and <i>Halichondria panicea</i> (Suberitida)

International audienc

A preliminary survey of marine cave habitats in the Maltese Islands

The Mediterranean Sea is a hotspot for marine biodiversity. Past studies of Mediterranean marine caves have revealed the unique biocoenotic and ecological characteristics of these habitats, which are protected by European Union legislation. The Maltese Islands have an abundance of partially and fully submerged marine caves with di fferent geomorphological characteristics, yet there have been no systematic studies on these habitats and their associated species. This study is a firrst synthesis of existing information on the biotic assemblages and physical characteristics of Maltese marine caves. The work combines a review of the available information with a preliminary survey of some marine caves in Gozo, during which several species were recorded for the first time for the Maltese Islands. Characteristic species recorded from local marine caves are highlighted, including several species of red and brown algae, sessile invertebrates including bryozoans, ascidians and sponges, and mobile forms including crustaceans and fi sh. A marked zonation from the cave entrance to the inside of the caves was identifi ed: photophilic algae at the mouth of the cave are progressively replaced by more sciaphilic species, followed by a middle section dominated by sessile invertebrates, and then a completely dark inner section that is mostly devoid of sessile organisms. Several species protected by national and international legislation were found to occur.peer-reviewe

Сравнительное исследование регенерации у губок (Porifera)

International audiencet is well known that sponges have unusually high regenerative abilities, which are often associated with their low tissue organization and high dynamics of cell differentiation. In order to identify the diversity of morphogenesis and cellular mechanisms involved in the restoration processes in Porifera, we carried out a detailed comparative study of the regeneration of a number of sponge species from phylogenetically deleted taxa that differ in their anatomical and histological organization. The objects of this project were sponges from the classes Demospongiae, Homoscleromorpha, and Calcarea, which have the leukonoid, siconoid, and asconoid types of the aquiferous system e-mines, as well as different degrees of epithelial development. The main mechanism for the regeneration of leukonoid Demospongiae is the epithelio-mesenchymal transformation involving polypotent archaeocyte cells. Epithelial morphogenesis and cell transdifferentiation are the basis for the regeneration of leukoid Homoscleromorpha and siconoid and asconoid Calcarea. Asconoid Calcarea regeneration is a rare example of “pure” morphallaxis. We have shown that the morphogenetic processes detected in sponges are as complex and diverse as in other higher animals. Thus, sponges can be a source of important information that will allow us to better understand the early evolution of molecular and cellular mechanisms of morphogenesis in animals.2 СПбГУ, биологический факультет 3 МГУ им. Ломоносова, биологический факультет, Беломорская биологическая станция им. Н.А. Перцова Хорошо известно, что губки обладают необычайно высокими регенерационными сп о-собностями что часто связывают с их низкой тканевой организацией и высокой динамикой клеточной дифференцировки. Для того, чтобы выявить разнообразие морфогенезов и клеточ-ных механизмов вовлеченных в восстановительные процессы у Porifera, нами было предпр и-нято детальное сравнительное исследование регенерации ряда видов губок из филогенетич е-ски удаленных таксонов, отличающиеся анатомической и гистологической организацией. Объектами данного проекта послужили губки из классов Demospongiae, Homoscleromorpha и Calcarea, обладающие лейконоидной, сиконоидной и асконоидной типами водоносной сист е-мы, а также разной степенью развития эпителия. Основным механизмом регенерации лейко-ноидных Demospongiae является эпителио-мезенхимная трансформация с вовлечением поли-потентных клеток-археоцитов. Основой регенерации лейконоидных Homoscleromorpha и сиконоидных и асконоидных Calcarea служат эпителиальные морфогенезы и трансдифферен-цировка клеток. Регенерация асконоидных Calcarea представляет собой редкий пример «чи-стого» морфаллаксиса. Мы показали, что морфогенетические процессы, выявленные у губок, являются столь же сложными и разнообразными, как и у других высших животных. Таким образом, губки могут быть источником важной информации, которая позволит нам глубже понять раннюю эволюцию молекулярных и клеточных механизмов морфогенеза у животных. Благодарности Данная работа осуществлена при финансовой поддержке грантов РФФИ № 16-04-00084, и РНФ № 17-14-01089.-8

WNT/β-Catenin Signalling and Epithelial Patterning in the Homoscleromorph Sponge Oscarella

Sponges branch basally in the metazoan phylogenetic tree and are thus well positioned to provide insights into the evolution of mechanisms controlling animal development, likely to remain active in adult sponges. Of the four sponge clades, the Homoscleromorpha are of particular interest as they alone show the “true” epithelial organization seen in other metazoan phyla (the Eumetazoa). We have examined the deployment in sponges of Wnt signalling pathway components, since this pathway is an important regulator of many developmental patterning processes. We identified a reduced repertoire of three divergent Wnt ligand genes in the recently-sequenced Amphimedon queenslandica (demosponge) genome and two Wnts from our EST collection from the homoscleromorph Oscarella lobularis, along with well-conserved genes for intracellular pathway components (β-catenin, GSK3β). Remarkably, the two O. lobularis Wnt genes showed complementary expression patterns in relation to the evenly spaced ostia (canal openings) of the exopinacoderm (ectoderm), highly reminiscent of Wnt expression during skin appendage formation in vertebrates. Furthermore, experimental activation of the Wnt/β-catenin pathway using GSK3β inhibitors provoked formation of ectopic ostia, as has been shown for epithelial appendages in Eumetazoa. We thus suggest that deployment of Wnt signalling is a common and perhaps ancient feature of metazoan epithelial patterning and morphogenesis

Origin and evolution of the Notch signalling pathway: an overview from eukaryotic genomes

Background. Of the 20 or so signal transduction pathways that orchestrate cell-cell interactions in metazoans, seven are involved during development. One of these is the Notch signalling pathway which regulates cellular identity, proliferation, differentiation and apoptosis via the developmental processes of lateral inhibition and boundary induction. In light of this essential role played in metazoan development, we surveyed a wide range of eukaryotic genomes to determine the origin and evolution of the components and auxiliary factors that compose and modulate this pathway. Results. We searched for 22 components of the Notch pathway in 35 different species that represent 8 major clades of eukaryotes, performed phylogenetic analyses and compared the domain compositions of the two fundamental molecules: the receptor Notch and its ligands Delta/Jagged. We confirm that a Notch pathway, with true receptors and ligands is specific to the Metazoa. This study also sheds light on the deep ancestry of a number of genes involved in this pathway, while other members are revealed to have a more recent origin. The origin of several components can be accounted for by the shuffling of pre-existing protein domains, or via lateral gene transfer. In addition, certain domains have appeared de novo more recently, and can be considered metazoan synapomorphies. Conclusion. The Notch signalling pathway emerged in Metazoa via a diversity of molecular mechanisms, incorporating both novel and ancient protein domains during eukaryote evolution. Thus, a functional Notch signalling pathway was probably present in Urmetazoa

A pan-metazoan concept for adult stem cells : the wobbling Penrose landscape

Funding: EU COST action MARISTEM. Grant Number: 16203 Marie Skłodowska-Curie COFUND program ARDRE. Grant Number: 847681 National Research Agency, ANR. Grant Numbers: ANR-15-IDEX-01, ANR-19-PRC United States-Israel Binational Science Foundation. Grant Number: 2015012Adult stem cells (ASCs) in vertebrates and model invertebrates (e.g. Drosophila melanogaster) are typically long-lived, lineage-restricted, clonogenic and quiescent cells with somatic descendants and tissue/organ-restricted activities. Such ASCs are mostly rare, morphologically undifferentiated, and undergo asymmetric cell division. Characterized by ‘stemness’ gene expression, they can regulate tissue/organ homeostasis, repair and regeneration. By contrast, analysis of other animal phyla shows that ASCs emerge at different life stages, present both differentiated and undifferentiated phenotypes, and may possess amoeboid movement. Usually pluri/totipotent, they may express germ-cell markers, but often lack germ-line sequestering, and typically do not reside in discrete niches. ASCs may constitute up to 40% of animal cells, and participate in a range of biological phenomena, from whole-body regeneration, dormancy, and agametic asexual reproduction, to indeterminate growth. They are considered legitimate units of selection. Conceptualizing this divergence, we present an alternative stemness metaphor to the Waddington landscape: the ‘wobbling Penrose’ landscape. Here, totipotent ASCs adopt ascending/descending courses of an ‘Escherian stairwell’, in a lifelong totipotency pathway. ASCs may also travel along lower stemness echelons to reach fully differentiated states. However, from any starting state, cells can change their stemness status, underscoring their dynamic cellular potencies. Thus, vertebrate ASCs may reflect just one metazoan ASC archetype.Publisher PDFPeer reviewe

Express method for isolation of ready-to-use 3D chitin scaffolds from aplysina archeri (aplysineidae: verongiida) demosponge

Sponges are a valuable source of natural compounds and biomaterials for many biotechnological applications. Marine sponges belonging to the order Verongiida are known to contain both chitin and biologically active bromotyrosines. Aplysina archeri (Aplysineidae: Verongiida) is well known to contain bromotyrosines with relevant bioactivity against human and animal diseases. The aim of this study was to develop an express method for the production of naturally prefabricated 3D chitin and bromotyrosine-containing extracts simultaneously. This new method is based on microwave irradiation (MWI) together with stepwise treatment using 1% sodium hydroxide, 20% acetic acid, and 30% hydrogen peroxide. This approach, which takes up to 1 h, made it possible to isolate chitin from the tube-like skeleton of A. archeri and to demonstrate the presence of this biopolymer in this sponge for the first time. Additionally, this procedure does not deacetylate chitin to chitosan and enables the recovery of ready-to-use 3D chitin scaffolds without destruction of the unique tube-like fibrous interconnected structure of the isolated biomaterial. Furthermore, these mechanically stressed fibers still have the capacity for saturation with water, methylene blue dye, crude oil, and blood, which is necessary for the application of such renewable 3D chitinous centimeter-sized scaffolds in diverse technological and biomedical fields. © 2019 by the authors