Sensory cells in tunicates: insights into mechanoreceptor evolution.

Tunicates, the sister group of vertebrates, offer a unique perspective for evolutionary developmental studies (Evo-Devo) due to their simple anatomical organization. Moreover, the separation of tunicates from vertebrates predated the vertebrate-specific genome duplications. As adults, they include both sessile and pelagic species, with very limited mobility requirements related mainly to water filtration. In sessile species, larvae exhibit simple swimming behaviors that are required for the selection of a suitable substrate on which to metamorphose. Despite their apparent simplicity, tunicates display a variety of mechanoreceptor structures involving both primary and secondary sensory cells (i.e., coronal sensory cells). This review encapsulates two decades of research on tunicate mechanoreception focusing on the coronal organ's sensory cells as prime candidates for understanding the evolution of vertebrate hair cells of the inner ear and the lateral line organ. The review spans anatomical, cellular and molecular levels emphasizing both similarity and differences between tunicate and vertebrate mechanoreception strategies. The evolutionary significance of mechanoreception is discussed within the broader context of Evo-Devo studies, shedding light on the intricate pathways that have shaped the sensory system in chordates.

Multiple Forms of Neural Cell Death in the Cyclical Brain Degeneration of A Colonial Chordate.

Human neuronal loss occurs through different cellular mechanisms, mainly studied in vitro. Here, we characterized neuronal death in B. schlosseri, a marine colonial tunicate that shares substantial genomic homology with mammals and has a life history in which controlled neurodegeneration happens simultaneously in the brains of adult zooids during a cyclical phase named takeover. Using an ultrastructural and transcriptomic approach, we described neuronal death forms in adult zooids before and during the takeover phase while comparing adult zooids in takeover with their buds where brains are refining their structure. At takeover, we found in neurons clear morphologic signs of apoptosis (i.e., chromatin condensation, lobed nuclei), necrosis (swollen cytoplasm) and autophagy (autophagosomes, autolysosomes and degradative multilamellar bodies). These results were confirmed by transcriptomic analyses that highlighted the specific genes involved in these cell death pathways. Moreover, the presence of tubulovesicular structures in the brain medulla alongside the over-expression of prion disease genes in late cycle suggested a cell-to-cell, prion-like propagation recalling the conformational disorders typical of some human neurodegenerative diseases. We suggest that improved understanding of how neuronal alterations are regulated in the repeated degeneration-regeneration program of B. schlosseri may yield mechanistic insights relevant to the study of human neurodegenerative diseases.

Lutein/ß-carotene ratio in extra virgin olive oil: An easy and rapid quantification method by Raman spectroscopy.

Carotenoids play an important role in the stability, freshness, and nutritional value of extra-virgin olive oil (EVOO). However, the carotenoid content in EVOO changes over time as a function of olive ripening and degrading events. A reliable quality marker is the ratio between the two most abundant carotenoids, namely lutein and ß-carotene, since the second degrades more rapidly. Thus, to obtain a fast quantification of the lutein/ß-carotene ratio in olive oil could deserve a certain interest. Resonant Raman spectroscopy is a rapid and non-destructive technique, widely applied for food chemical characterization. In this work, using high-performance liquid chromatography and UV-vis absorption spectroscopy as calibration techniques, we present a reliable method to assess the lutein/ß-carotene ratio in EVOO using a single Raman spectrum. The novel approach deserves several methodological and applicative interests, since it would allow rapid, on-site screening of EVOO quality and authenticity, especially if implemented as a portable system.

Contributions from both the brain and the vascular network guide behavior in the colonial tunicate Botryllus schlosseri.

We studied the function, development and aging of the adult nervous system in the colonial tunicate Botryllus schlosseri. Adults, termed zooids, are filter-feeding individuals. Sister zooids group together to form modules, and modules, in turn, are linked by a shared vascular network to form a well-integrated colony. Zooids undergo a weekly cycle of regression and renewal during which mature zooids are replaced by developing buds. The zooid brain matures and degenerates on this 7-day cycle. We used focal extracellular recording and video imaging to explore brain activity in the context of development and degeneration and to examine the contributions of the nervous system and vascular network to behavior. Recordings from the brain revealed complex firing patterns arising both spontaneously and in response to stimulation. Neural activity increases as the brain matures and declines thereafter. Motor behavior follows the identical time course. The behavior of each zooid is guided predominantly by its individual brain, but sister zooids can also exhibit synchronous motor behavior. The vascular network also generates action potentials that are largely independent of neural activity. In addition, the entire vascular network undergoes slow rhythmic contractions that appear to arise from processes endogenous to vascular epithelial cells. We found that neurons in the brain and cells of the vascular network both express multiple genes for voltage-gated Na+ and Ca2+ ion channels homologous (based on sequence) to mammalian ion channel genes.

Two distinct evolutionary conserved neural degeneration pathways characterized in a colonial chordate.

Colonial tunicates are marine organisms that possess multiple brains simultaneously during their colonial phase. While the cyclical processes of neurogenesis and neurodegeneration characterizing their life cycle have been documented previously, the cellular and molecular changes associated with such processes and their relationship with variation in brain morphology and individual (zooid) behavior throughout adult life remains unknown. Here, we introduce Botryllus schlosseri as an invertebrate model for neurogenesis, neural degeneration, and evolutionary neuroscience. Our analysis reveals that during the weekly colony budding (i.e., asexual reproduction), prior to programmed cell death and removal by phagocytes, decreases in the number of neurons in the adult brain are associated with reduced behavioral response and significant change in the expression of 73 mammalian homologous genes associated with neurodegenerative disease. Similarly, when comparing young colonies (1 to 2 y of age) to those reared in a laboratory for ∼20 y, we found that older colonies contained significantly fewer neurons and exhibited reduced behavioral response alongside changes in the expression of 148 such genes (35 of which were differentially expressed across both timescales). The existence of two distinct yet apparently related neurodegenerative pathways represents a novel platform to study the gene products governing the relationship between aging, neural regeneration and degeneration, and loss of nervous system function. Indeed, as a member of an evolutionary clade considered to be a sister group of vertebrates, this organism may be a fundamental resource in understanding how evolution has shaped these processes across phylogeny and obtaining mechanistic insight.

Yamanaka Factors in the Budding Tunicate Botryllus schlosseri Show a Shared Spatio-Temporal Expression Pattern in Chordates.

In vertebrates, the four transcription factors Sox2, c-Myc, Pou5f1 and Klf4 are involved in the differentiation of several tissues during vertebrate embryogenesis; moreover, they are normally co-expressed in embryonic stem cells and play roles in pluripotency, self-renewal, and maintenance of the undifferentiated state in adult cells. The in vitro forced co-expression of these factors, named Yamanaka factors (YFs), induces pluripotency in human or mouse fibroblasts. Botryllus schlosseri is a colonial tunicate undergoing continuous stem cell-mediated asexual development, providing a valuable model system for the study of pluripotency in the closest living relatives of vertebrates. In this study, we identified B. schlosseri orthologs of human Sox2 and c-Myc genes, as well as the closest homologs of the vertebrate-specific Pou5f1 gene, through an in-depth evolutionary analysis of the YF gene families in tunicates and other deuterostomes. Then, we studied the expression of these genes during the asexual cycle of B. schlosseri using in situ hybridization in order to investigate their possible involvement in tissue differentiation and in pluripotency maintenance. Our results show a shared spatio-temporal expression pattern consistent with the reported functions of these genes in invertebrate and vertebrate embryogenesis. Moreover, Myc, SoxB1 and Pou3 were expressed in candidate stem cells residing in their niches, while Pou2 was found expressed exclusively in the immature previtellogenic oocytes, both in gonads and circulating in the colonial vascular system. Our data suggest that Myc, SoxB1 and Pou3 may be individually involved in the differentiation of the same territories seen in other chordates, and that, together, they may play a role in stemness even in this colonial ascidian.

iColon, a patient-focused mobile application for perioperative care in colorectal surgery: an observational, real-world study protocol.

INTRODUCTION: The enhanced recovery after surgery (ERAS) protocol provides optimised care guidelines for patients undergoing elective colorectal surgery. To ensure high compliance with active ERAS elements, patients must be educated to actively participate in the perioperative care pathway. Mobile health is a rapidly expanding area of the digital health sector that is effective in educating and engaging patients during follow-up. iColon is a mobile application designed by the Operative Unit of General Surgery of IRCCS Sacro Cuore Don Calabria Hospital of Negrar of Valpolicella, which is specifically targeted at patients undergoing elective colorectal surgery. iColon is organised into ERAS phases, and it provides real-time feedback to surgeons about a patient's adherence to perioperative active ERAS elements. METHODS AND ANALYSIS: We hypothesise that by providing a patient-focused mobile application, compliance with active ERAS elements could be improved.The first coprimary objective is to build patient confidence in using the mobile application, iColon, during perioperative care. The second coprimary objective is to establish patient compliance with active ERAS elements.Secondary objectives include examining: length of stay, 30-day readmission rate, postoperative complications and patient satisfaction of received care.This study is a prospective observational real-world study of patients undergoing elective colorectal surgery who are following the ERAS protocol and using iColon during perioperative periods between September 2020 and December 2022.By educating and engaging patients in the ERAS protocol, the mobile application, iColon, should stimulate patients to be more proactive in managing their healthcare by complying more closely with active ERAS elements. ETHICS AND DISSEMINATION: This study has been approved by the local Ethics Committee with the protocol number 29219 of 25 May 2020. The results will be actively disseminated through peer-reviewed journals, conference presentations and various community engagement activities.

rs41291957 controls miR-143 and miR-145 expression and impacts coronary artery disease risk.

The role of single nucleotide polymorphisms (SNPs) in the etiopathogenesis of cardiovascular diseases is well known. The effect of SNPs on disease predisposition has been established not only for protein coding genes but also for genes encoding microRNAs (miRNAs). The miR-143/145 cluster is smooth muscle cell-specific and implicated in the pathogenesis of atherosclerosis. Whether SNPs within the genomic sequence of the miR-143/145 cluster are involved in cardiovascular disease development is not known. We thus searched annotated sequence databases for possible SNPs associated with miR-143/145. We identified one SNP, rs41291957 (G > A), located -91 bp from the mature miR-143 sequence, as the nearest genetic variation to this miRNA cluster, with a minor allele frequency > 10%. In silico and in vitro approaches determined that rs41291957 (A) upregulates miR-143 and miR-145, modulating phenotypic switching of vascular smooth cells towards a differentiated/contractile phenotype. Finally, we analysed association between rs41291957 and CAD in two cohorts of patients, finding that the SNP was a protective factor. In conclusion, our study links a genetic variation to a pathological outcome through involvement of miRNAs.

Stem Cells and Innate Immunity in Aquatic Invertebrates: Bridging Two Seemingly Disparate Disciplines for New Discoveries in Biology.

The scopes related to the interplay between stem cells and the immune system are broad and range from the basic understanding of organism's physiology and ecology to translational studies, further contributing to (eco)toxicology, biotechnology, and medicine as well as regulatory and ethical aspects. Stem cells originate immune cells through hematopoiesis, and the interplay between the two cell types is required in processes like regeneration. In addition, stem and immune cell anomalies directly affect the organism's functions, its ability to cope with environmental changes and, indirectly, its role in ecosystem services. However, stem cells and immune cells continue to be considered parts of two branches of biological research with few interconnections between them. This review aims to bridge these two seemingly disparate disciplines towards much more integrative and transformative approaches with examples deriving mainly from aquatic invertebrates. We discuss the current understanding of cross-disciplinary collaborative and emerging issues, raising novel hypotheses and comments. We also discuss the problems and perspectives of the two disciplines and how to integrate their conceptual frameworks to address basic equations in biology in a new, innovative way.

Myocardial hypoxic stress mediates functional cardiac extracellular vesicle release.

AIMS: Increased shedding of extracellular vesicles (EVs)-small, lipid bilayer-delimited particles with a role in paracrine signalling-has been associated with human pathologies, e.g. atherosclerosis, but whether this is true for cardiac diseases is unknown. METHODS AND RESULTS: Here, we used the surface antigen CD172a as a specific marker of cardiomyocyte (CM)-derived EVs; the CM origin of CD172a+ EVs was supported by their content of cardiac-specific proteins and heart-enriched microRNAs. We found that patients with aortic stenosis, ischaemic heart disease, or cardiomyopathy had higher circulating CD172a+ cardiac EV counts than did healthy subjects. Cellular stress was a major determinant of EV release from CMs, with hypoxia increasing shedding in in vitro and in vivo experiments. At the functional level, EVs isolated from the supernatant of CMs derived from human-induced pluripotent stem cells and cultured in a hypoxic atmosphere elicited a positive inotropic response in unstressed CMs, an effect we found to be dependent on an increase in the number of EVs expressing ceramide on their surface. Of potential clinical relevance, aortic stenosis patients with the highest counts of circulating cardiac CD172a+ EVs had a more favourable prognosis for transcatheter aortic valve replacement than those with lower counts. CONCLUSION: We identified circulating CD172a+ EVs as cardiac derived, showing their release and function and providing evidence for their prognostic potential in aortic stenosis patients.

Sexual and asexual development: two distinct programs producing the same tunicate.

Colonial tunicates are the only chordate that possess two distinct developmental pathways to produce an adult body: either sexually through embryogenesis or asexually through a stem cell-mediated renewal termed blastogenesis. Using the colonial tunicate Botryllus schlosseri, we combine transcriptomics and microscopy to build an atlas of the molecular and morphological signatures at each developmental stage for both pathways. The general molecular profiles of these processes are largely distinct. However, the relative timing of organogenesis and ordering of tissue-specific gene expression are conserved. By comparing the developmental pathways of B. schlosseri with other chordates, we identify hundreds of putative transcription factors with conserved temporal expression. Our findings demonstrate that convergent morphology need not imply convergent molecular mechanisms but that it showcases the importance that tissue-specific stem cells and transcription factors play in producing the same mature body through different pathways.

Sixty years of experimental studies on the blastogenesis of the colonial tunicate Botryllus schlosseri.

In the second half of the eighteenth century, Schlosser and Ellis described the colonial ascidian Botryllus schlosseri garnering the interest of scientists around the world. In the 1950's scientists began to study B. schlosseri and soon recognized it as an important model organism for the study of developmental biology and comparative immunology. In this review, we summarize the history of B. schlosseri studies and experiments performed to characterize the colony life cycle and bud development. We describe experiments performed to analyze variations in bud productivity, zooid growth and bilateral asymmetry (i.e., the situs viscerum), and discuss zooid and bud removal experiments that were used to study the cross-talk between consecutive blastogenetic generations and vascular budding. We also summarize experiments that demonstrated that the ability of two distinct colonies to fuse or reject is controlled by a single polymorphic gene locus (BHF) with multiple, codominantly expressed alleles. Finally, we describe how the ability to fuse and create chimeras was used to show that within a chimera somatic and germline stem cells compete to populate niches and regenerate tissue or germline organs. Starting from the results of these 60 years of study, we can now use new technological advances to expand the study of B. schlosseri traits and understand functional relationships between its genome and life history phenotypes.

A Notch-regulated proliferative stem cell zone in the developing spinal cord is an ancestral vertebrate trait.

Vertebrates have evolved the most sophisticated nervous systems we know. These differ from the nervous systems of invertebrates in several ways, including the evolution of new cell types, and the emergence and elaboration of patterning mechanisms to organise cells in time and space. Vertebrates also generally have many more cells in their central nervous systems than invertebrates, and an increase in neural cell number may have contributed to the sophisticated anatomy of the brain and spinal cord. Here, we study how increased cell number evolved in the vertebrate central nervous system, investigating the regulation of cell proliferation in the lamprey spinal cord. Markers of proliferation show that a ventricular progenitor zone is found throughout the lamprey spinal cord. We show that inhibition of Notch signalling disrupts the maintenance of this zone. When Notch is blocked, progenitor cells differentiate precociously, the proliferative ventricular zone is lost and differentiation markers become expressed throughout the spinal cord. Comparison with other chordates suggests that the emergence of a persistent Notch-regulated proliferative progenitor zone was a crucial step for the evolution of vertebrate spinal cord complexity.

Differentiation and Induced Sensorial Alteration of the Coronal Organ in the Asexual Life of a Tunicate.

Tunicates, the sister group of vertebrates, possess a mechanoreceptor organ, the coronal organ, which is considered the best candidate to address the controversial issue of vertebrate hair cell evolution. The organ, located at the base of the oral siphon, controls the flow of seawater into the organism and can drive the "squirting" reaction, i.e., the rapid body muscle contraction used to eject dangerous particles during filtration. Coronal sensory cells are secondary mechanoreceptors and share morphological, developmental, and molecular traits with vertebrate hair cells. In the colonial tunicate Botryllus schlosseri, we described coronal organ differentiation during asexual development. Moreover, we showed that the ototoxic aminoglycoside gentamicin caused morphological and mechanosensorial impairment in coronal cells. Finally, fenofibrate had a strong protective effect on coronal sensory cells due to gentamicin-induced toxicity, as occurs in vertebrate hair cells. Our results reinforce the hypothesis of homology between vertebrate hair cells and tunicate coronal sensory cells.

High-precision morphology: bifocal 4D-microscopy enables the comparison of detailed cell lineages of two chordate species separated for more than 525 million years.

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 for few disparate animal taxa, encumbering evolutionarily meaningful comparisons. Tunicates, considered to be close relatives of vertebrates, are marine invertebrates whose fossil record dates back to 525 million years ago. Life-history strategies across this subphylum are radically different, and include biphasic ascidians with free swimming larvae and a sessile adult stage, and the holoplanktonic larvaceans. Despite considerable progress, notably on the molecular level, the exact extent of evolutionary conservation and innovation during embryology remain obscure. RESULTS: Here, using the innovative technique of bifocal 4D-microscopy, we demonstrate exactly which characteristics in the cell lineages of the ascidian Phallusia mammillata and the larvacean Oikopleura dioica were conserved and which were altered during evolution. Our accurate cell lineage trees in combination with detailed three-dimensional representations clearly identify conserved correspondence in relative cell position, cell identity, and fate restriction in several lines from all prospective larval tissues. At the same time, we precisely pinpoint differences observable at all levels of development. These differences comprise fate restrictions, tissue types, complex morphogenetic movement patterns, numerous cases of heterochronous acceleration in the larvacean embryo, and differences in bilateral symmetry. CONCLUSIONS: Our results demonstrate in extraordinary detail the multitude of developmental levels amenable to evolutionary innovation, including subtle changes in the timing of fate restrictions as well as dramatic alterations in complex morphogenetic movements. We anticipate that the precise spatial and temporal cell lineage data will moreover serve as a high-precision guide to devise experimental investigations of other levels, such as molecular interactions between cells or changes in gene expression underlying the documented structural evolutionary changes. Finally, the quantitative amount of digital high-precision morphological data will enable and necessitate software-based similarity assessments as the basis of homology hypotheses.

Neutrophil Gelatinase-Associated Lipocalin and Contrast-Induced Acute Kidney Injury.

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) is an early marker of acute kidney injury (AKI). METHODS AND RESULTS: Urine NGAL and serum NGAL (sNGAL) were assessed at 2, 6, 24, and 48 hours after contrast media (CM) exposure in 458 high-risk patients (development set). Optimal thresholds in predicting contrast-induced AKI (serum creatinine [sCr] increase ≥0.3 mg/dL at 48 hours after CM administration) were identified. Major adverse events (MAE; death, dialysis, nonfatal myocardial infarction, sustained kidney injury, and myocardial revascularization) at 1 year were assessed. In the development set, optimal thresholds for contrast-induced AKI occurred at 6 hours for both urine NGAL (≥20 ng/mL; 97% negative predictive value and 27% positive predictive value) and sNGAL (≥179 ng/mL; 93% negative predictive value and 20% positive predictive value). Furthermore, sNGAL ≥179 ng/mL at 6 hours was an independent predictor of 1-year MAE. 1-year MAE occurred in 27/198 patients (13.5%) with sNGAL <179 ng/mL and sCr <0.3 mg/dL, in 57/193 (29.5%) patients with only sNGAL ≥179 ng/mL, and in 37/67 (55%) patients with sCr ≥0.3 mg/dL. In additional 253 patients (validation set), no patient with urine NGAL <20 ng/mL or sNGAL <179 ng/mL at 6 hours developed contrast-induced AKI. Furthermore, 6/68 (9%) patients with sNGAL <179 ng/mL and sCr increase <0.3 mg/dL had 1-year MAE versus 17/57 (30%) patients with sNGAL ≥179 ng/mL and sCr increase <0.3 mg/dL and 8/16 (50%) patients with sCr increase ≥0.3 mg/dL. CONCLUSIONS: Urine NGAL <20 ng/mL and sNGAL <179 ng/mL at 6 hours are reliable markers for ruling out contrast-induced AKI. sNGAL ≥179 ng/mL at 6 hours predicts 1-year MAE. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01098032.

Acute Kidney Injury in Patients With Chronic Kidney Disease Undergoing Internal Carotid Artery Stent Implantation.

OBJECTIVES: This study sought to investigate acute kidney injury (AKI) following carotid artery stenting (CAS). BACKGROUND: Few data exist on AKI following CAS. METHODS: This study evaluated 126 chronic kidney disease (CKD) patients who underwent CAS. The risk for contrast-induced AKI was defined by the Mehran score. Hemodynamic depression (i.e., periprocedural systolic blood pressure <90 mm Hg or heart rate <60 beats/min), AKI (i.e., an increase of ≥0.3 mg/dl in the serum creatinine concentration at 48 h), and 30-day major adverse events (including death, stroke, and acute myocardial infarction) were assessed. RESULTS: AKI occurred in 26 patients (21%). Although baseline kidney function and contrast volume were similar in the AKI group and the non-AKI group, the risk score was higher (10 ± 3 vs. 8 ± 3; p = 0.032), and hemodynamic depression (mostly due to hypotension) (65.5% vs. 35%; p = 0.005) was more common in the AKI group. The threshold of hemodynamic depression duration for AKI development was 2.5 min (sensitivity 54%, specificity 82%). Independent predictors of AKI were hemodynamic depression (odds ratio [OR]: 4.01; 95% confidence interval [CI]: 1.07 to 15.03; p = 0.009), risk score (OR: 1.29; 95% CI: 1.03 to 1.60; p = 0.024), and male sex (OR: 6.07; 95% CI: 1.18 to 31.08; p = 0.021). Independent predictors of 30-day major adverse events that occurred more often in the AKI group (19.5% vs. 7%; p = 0.058) were AKI (HR: 4.83; 95% CI: 1.10 to 21.24; p = 0.037) and hemodynamic depression (HR: 5.58; 95% CI: 1.10 to 28.31; p = 0.038). CONCLUSIONS: AKI in CKD patients undergoing CAS is mostly due to hemodynamic depression and is associated with a higher 30-day major adverse events rate.