UV-B radiation bearings on ephemeral soma in the shallow water tunicate Botryllus schlosseri

Proteome-wide 4-hydroxy-2-nonenal signature of oxidative stress in the marine invasive tunicate Botryllus schlosseri

The colonial ascidian Boytryllus schlosseri is an invasive marine chordate that thrives under conditions of anthropogenic climate change. We show that the B. schlosseri expressed proteome contains unusually high levels of proteins that are adducted with 4-hydroxy-2-nonenal (HNE). HNE represents a prominent posttranslational modification resulting from oxidative stress. Although numerous studies have assessed oxidative stress in marine organisms HNE protein modification has not previously been determined in any marine species. LC/MS proteomics was used to identify 1052 HNE adducted proteins in B. schlosseri field and laboratory populations. Adducted amino acid residues were ascertained for 1849 modified sites, of which 1195 had a maximum amino acid localization score. Most HNE modifications were at less reactive lysines (rather than more reactive cysteines). HNE prevelance on most sites was high. These observations suggest that B. schlosseri experiences and tolerates high intracellular reactive oxygen species levels, resulting in substantial lipid peroxidation. HNE adducted B. schlosseri proteins show enrichment in mitochondrial, proteostasis, and cytoskeletal functions. Based on these results we propose that redox signaling contributes to regulating energy metabolism, the blastogenic cycle, oxidative burst defenses, and cytoskeleton dynamics during B. schlosseri development and physiology. A DIA assay library was constructed to quantify HNE adduction at 72 sites across 60 proteins that represent a holistic network of functionally discernable oxidative stress bioindicators. We conclude that the vast amount of HNE protein adduction in this circumpolar tunicate is indicative of high oxidative stress tolerance contributing to its range expansion into diverse environments.

NEW & NOTEWORTHY

Oxidative stress results from environmental challenges that increase in frequency and severity during the Anthropocene. Oxygen radical attack causes lipid peroxidation leading to HNE production. Proteome-wide HNE adduction is highly prevalent in Botryllus schlosseri , a widely distributed, highly invasive, and economically important biofouling ascidian and the first marine species to be analyzed for proteome HNE modification. HNE adduction of specific proteins physiologically sequesters reactive oxygen species, which enhances fitness and resilience during environmental change.

Transcription profiles and phenotype reveal global response of Staphylococcus aureus exposed to ultrasound and ultraviolet stressors

Ultrasound and ultraviolet light have good inactivation performance against pathogens in sewage. In this study, the inactivation mechanisms of 60 kHz ultrasound and ultraviolet radiation against Staphylococcus aureus (S. aureus) were studied from the perspectives of cell phenotype and transcriptome for the first time. The results showed that both ultrasound and ultraviolet treatments had adverse impacts on the cellular morphology of S. aureus to varying degrees at cellular level. The transcriptomic analysis revealed that there were 225 and 1077 differentially expressed genes (DEGs) in the ultrasound and ultraviolet treatments, respectively. The result revealed that both ultrasound and ultraviolet could interfere with the expression of the genes involved in ABC transporters, amino acid and fatty acid metabolism to influence the membrane permeability. Besides the membrane permeability, ultraviolet also could disturb the ATP synthesis, DNA replication and cell division through restraining the expression of several genes related to carbohydrate metabolism, peptidoglycan synthesis, DNA-binding/repair protein synthesis. Compared with the single inactivation pathway of ultrasound, ultraviolet inactivation of S. aureus is multi-target and multi-pathway. We believe that the bactericidal mechanisms of ultrasound and ultraviolet radiation presented by this study could provide theoretical guidance for the synergistic inactivation of pathogens in sewage by ultrasound and ultraviolet radiation in the future.

Transient impacts of UV-B irradiation on whole body regeneration in a colonial urochordate

Within the chordates, only some colonial ascidians experience whole body regeneration (WBR), where amputated small colonial fragments containing blood-vessels have the capability to regenerate the entire functional adult zooid within 1-3 weeks. Studying WBR in small colonial fragments taken at different blastogenic stages (the weekly developmental process characteristic to botryllid ascidians) from the ascidian Botrylloides leachii, about half of the fragments were able to complete regeneration (cWBR) three weeks following separation, about half were still in uncomplete, running regeneration (rWBR), and only a small percentage died. cWBR significantly increased in fragments that originated from a late blastogenic stage compared to an early stage. Most B. leachii populations reside in shallow waters, under variable daily natural UV irradiation, and it is of interest to elucidate irradiation effects on development and regeneration. Here, we show that UV-B irradiation resulted in enhanced mortality, with abnormal morphological changes in surviving fragments, yet with non-significant cWBR vs. rWBRs. Further, UV-B irradiation influenced the proportion of blood cells (morula cells, hemoblasts) and of multinucleated cells, a new WBR-associated cell type. At 24-h post-amputation we observed enhanced expression of β-catenin (a signaling pathway that plays indispensable roles in cell renewal and regeneration), H3 and PCNA in all cell types of non-irradiated as compared to irradiated fragments. These elevated levels were considerably reduced 9-days later. Since WBR is a highly complex phenomenon, the employment of specific experimental conditions, as UV-B irradiation, alongside blastogenesis (the weekly developmental process), elucidates undisclosed facets of this unique biological occurrence such as transient expression of signature genes.

Improved Media Formulations for Primary Cell Cultures Derived from a Colonial Urochordate

The cultivation of marine invertebrate cells in vitro has garnered significant attention due to the availability of diverse cell types and cellular potentialities in comparison to vertebrates and particularly in response to the demand for a multitude of applications. While cells in the colonial urochordate Botryllus schlosseri have a very high potential for omnipotent differentiation, no proliferating cell line has been established in Botryllus, with results indicating that cell divisions cease 24-72 h post initiation. This research assessed how various Botryllus blood cell types respond to in vitro conditions by utilizing five different refinements of cell culture media (TGM1-TGM5). During the initial week of culture, there was a noticeable medium-dependent increase in the proliferation and viability of distinct blood cell types. Within less than one month from initiation, we developed medium-specific primary cultures, a discovery that supports larger efforts to develop cell type-specific cultures. Specific cell types were easily distinguished and classified based on their natural fluorescence properties using confocal microscopy. These results are in agreement with recent advances in marine invertebrate cell cultures, demonstrating the significance of optimized nutrient media for cell culture development and for cell selection.

The novel Orshina Rhythm in a colonial urochordate signifies the display of recurrent aging/rejuvenation sequels

When it comes to aging, some colonial invertebrates present disparate patterns from the customary aging phenomenon in unitary organisms, where a single senescence phenomenon along ontogeny culminates in their inevitable deaths. Here we studied aging processes in 81 colonies of the marine urochordate Botryllus schlosseri each followed from birth to death (over 720 days). The colonies were divided between three life history strategies, each distinct from the others based on the presence/absence of colonial fission: NF (no fission), FA (fission develops after the colony reaches maximal size), and FB (fission develops before the colony reaches maximal size). The study revealed recurring patterns in sexual reproductive statuses (hermaphroditism and male-only settings), colonial vigor, and size. These recurring patterns, collectively referred to as an Orshina, with one or more 'astogenic segments' on the genotype level. The combination of these segments forms the Orshina rhythm. Each Orshina segment lasts about three months (equivalent to 13 blastogenic cycles), and concludes with either the colonial death or rejuvenation, and is manipulated by absence/existing of fission events in NF/FA/FB strategies. These findings indicate that reproduction, life span, death, rejuvenation and fission events are important scheduled biological components in the constructed Orshina rhythm, a novel aging phenomenon.

Transcriptome landscapes that signify Botrylloides leachi (Ascidiacea) torpor states

Harsh environments enforce the expression of behavioural, morphological, physiological, and reproductive rejoinders, including torpor. Here we study the morphological, cellular, and molecular alterations in torpor architype in the colonial urochordate Botrylloides aff. leachii by employing whole organism Transmission electron (TEM) and light microscope observations, RNA sequencing, real-time polymerase chain reaction (qPCR) quantification of selected genes, and immunolocalization of WNT, SMAD and SOX2 gene expressions. On the morphological level, torpor starts with gradual regression of all zooids and buds which leaves the colony surviving as condensed vasculature remnants that may be 'aroused' to regenerate fully functional colonies upon changes in the environment. Simultaneously, we observed altered distributions of hemolymph cell types. Phagocytes doubled in number, while the number of morula cells declined by half. In addition, two new circulating cell types were observed, multi-nucleated and bacteria-bearing cells. RNA sequencing technology revealed marked differences in gene expression between different organism compartments and states: active zooids and ampullae, and between mid-torpor and naive colonies, or naive and torpid colonies. Gene Ontology term enrichment analyses further showed disparate biological processes. In torpid colonies, we observed overall 233 up regulated genes. These genes included NR4A2, EGR1, MUC5AC, HMCN2 and. Also, 27 transcription factors were upregulated in torpid colonies including ELK1, HDAC3, RBMX, MAZ, STAT1, STAT4 and STAT6. Interestingly, genes involved in developmental processes such as SPIRE1, RHOA, SOX11, WNT5A and SNX18 were also upregulated in torpid colonies. We further validated the dysregulation of 22 genes during torpor by utilizing qPCR. Immunohistochemistry of representative genes from three signaling pathways revealed high expression of these genes in circulated cells along torpor. WNT agonist administration resulted in early arousal from torpor in 80% of the torpid colonies while in active colonies WNT agonist triggered the torpor state. Abovementioned results thus connote unique transcriptome landscapes associated with Botrylloides leachii torpor.

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

Adult 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.