Biology subjects

Schippers, K. J.

Publications and source records attributed to Schippers, K. J..

4 recordsLinked to original sources

bioRxiv2023

Molecular profiling of sponge deflation reveals an ancient relaxant-inflammatory response

A hallmark of animals is the coordination of whole-body movement. Neurons and muscles are central to this, yet coordinated movements also exist in sponges that lack these cell types. Sponges are sessile animals with a complex canal system for filter-feeding. They undergo whole-body movements resembling "contractions" that lead to canal closure and water expulsion. Here, we combine 3D optical coherence microscopy, pharmacology, and functional proteomics to elucidate anatomy, molecular physiology, and control of these movements. We find them driven by the relaxation of actomyosin stress fibers in epithelial canal cells, which leads to whole-body deflation via collapse of the incurrent and expansion of the excurrent system, controlled by an Akt/NO/PKG/A pathway. A concomitant increase in reactive oxygen species and secretion of proteinases and cytokines indicate an inflammation-like state reminiscent of vascular endothelial cells experiencing oscillatory shear stress. This suggests an ancient relaxant-inflammatory response of perturbed fluid-carrying systems in animals. HighlightsO_LISponge deflation is driven by tension release in actomyosin stress fibers of epithelial pinacocytes C_LIO_LIAkt kinase/Nitric oxide/Protein kinase G/A regulate actomyosin relaxation C_LIO_LIAgitation-induced deflation coincides with an inflammatory state C_LIO_LIThe sponge relaxant-inflammatory response is evolutionary related to similar responses in the vertebrate vascular system C_LI

molecular biology↗

bioRxiv2019

Profiling cellular diversity in sponges informs animal cell type and nervous system evolution

The evolutionary origin of metazoan cell types such as neurons, muscles, digestive, and immune cells, remains unsolved. Using whole-body single-cell RNA sequencing in a sponge, an animal without nervous system and musculature, we identify 18 distinct cell types comprising four major families. This includes nitric-oxide sensitive contractile cells, digestive cells active in macropinocytosis, and a family of amoeboid-neuroid cells involved in innate immunity. We uncover presynaptic genes in an amoeboid-neuroid cell type, and postsynaptic genes in digestive choanocytes, suggesting asymmetric and targeted communication. Corroborating this, long neurite-like extensions from neuroid cells directly contact and enwrap choanocyte microvillar collars. Our data indicate a link between neuroid and immune functions in sponges, and suggest that a primordial neuro-immune system cleared intruders and controlled ciliary beating for feeding.

developmental biology↗

bioRxiv2017

β-catenin has both conserved and novel functions in the sponge Ephydatia muelleri

{beta}-catenin acts as a transcriptional co-activator in the Wnt/{beta}-catenin signaling pathway and a cytoplasmic effector in cadherin-based cell adhesion. These functions are ancient within animals, but the earliest steps in {beta}-catenin evolution remain unresolved due to limited data from key lineages - sponges, ctenophores and placozoans. Previous studies in sponges have characterized {beta}-catenin expression dynamics and used GSK3B antagonists to ectopically activate the Wnt/{beta}-catenin pathway; both approaches rely upon untested assumptions about the conservation of {beta}-catenin function and regulation in sponges. Here, we test these assumptions using an antibody raised against {beta}-catenin from the sponge Ephydatia muelleri. We find that cadherin-complex genes co-precipitate with endogenous Em {beta}-catenin from cell lysates, but that Wnt pathway components do not. However, through immunostaining we detect both cell boundary and nuclear populations, and we find evidence that Em {beta}-catenin is a conserved substrate of GSK3B. Collectively, these data support conserved roles for Em {beta}-catenin in both cell adhesion and Wnt signaling. Additionally, we find evidence for an Em {beta}-catenin population associated with the distal ends of F-actin stress fibers in apparent cell-substrate adhesion structures that resemble focal adhesions. This finding suggests a fundamental difference in the adhesion properties of sponge tissues relative to other animals, in which the adhesion functions of {beta}-catenin are typically restricted to cell-cell adhesions.

evolutionary biology↗

bioRxiv2017

Transcriptome sequencing and delimitation of cryptic Oscarella species (O. carmela and O. pearsei sp. nov) from California, USA.

The homoscleromorph sponge Oscarella carmela, first described from central California, USA is shown to represent two morphologically similar but phylogenetically distant species that are co-distributed. We here describe a new species as Oscarella pearsei, sp. nov. and redescribe Oscarella carmela; the original description was based upon material from both species. Further, we correct the identification of published genomic/transcriptomic resources that were originally attributed to O. carmela, and present new Illumina-sequenced transcriptome assemblies for each of these species, and the mitochondrial genome sequence for O. pearsei sp. nov. Using SSU and LSU ribosomal DNA and the mitochondrial genome, we report the phylogenetic relationships of these species relative to other Oscarella species, and find strong support for placement of O. pearsei sp. nov. in a clade defined by the presence of spherulous cells that contain paracrystalline inclusions; O. carmela lacks this cell type and is most closely related to the Western Pacific species, O. malakhovi. Oscarella pearsei sp. nov and O. carmela can be tentatively distinguished based upon gross morphological differences such as color, surface texture and extent of mucus production, but can be more reliably identified using mitochondrial and nuclear barcode sequencing, ultrastructural characteristics of cells in the mesohyl, and the morphology of the follicle epithelium which surrounds the developing embryo in reproductively active individuals. Usually, cryptic species are very closely related to each other, but in this case and in sponges generally, cryptic species may be very distantly related because sponges can be difficult to identify based upon gross morphological characteristics.

evolutionary biology↗