Genotype-specific Expression of Uncle Fester Suggests a Role in Allorecognition Education in a Basal Chordate.

Histocompatibility is the ability to discriminate between self and non-self tissues, and has been described in species throughout the metazoa. Despite its universal presence, histocompatibility genes utilized by different phyla are unique-those found in sponges, cnidarians, ascidians, and vertebrates are not orthologous. Thus, the origins of these sophisticated recognition systems, and any potential functional commonalities between them, are not understood.

Genotype-specific expression of suggests a role in allorecognition education in a basal chordate.

Histocompatibility is the ability to discriminate between self and non-self tissues, and has been described in species throughout the metazoa. Despite its universal presence, histocompatibility genes utilized by different phyla are unique- those found in sponges, cnidarians, ascidians and vertebrates are not orthologous. Thus, the origins of these sophisticated recognition systems, and any potential functional commonalities between them are not understood.

Rtf1-dependent transcriptional pausing regulates cardiogenesis.

During heart development, a well-characterized network of transcription factors initiates cardiac gene expression and defines the precise timing and location of cardiac progenitor specification. However, our understanding of the post-initiation transcriptional events that regulate cardiac gene expression is still incomplete. The PAF1C component Rtf1 is a transcription regulatory protein that modulates pausing and elongation of RNA Pol II, as well as cotranscriptional histone modifications.

Rtf1 Transcriptionally Regulates Neonatal and Adult Cardiomyocyte Biology.

The PAF1 complex component Rtf1 is an RNA Polymerase II-interacting transcription regulatory protein that promotes transcription elongation and the co-transcriptional monoubiquitination of histone 2B. Rtf1 plays an essential role in the specification of cardiac progenitors from the lateral plate mesoderm during early embryogenesis, but its requirement in mature cardiac cells is unknown. Here, we investigate the importance of Rtf1 in neonatal and adult cardiomyocytes using knockdown and knockout approaches.

Glutamate 73 Promotes Anti-arrhythmic Effects of Voltage-Dependent Anion Channel Through Regulation of Mitochondrial Ca Uptake.

Mitochondria critically regulate a range of cellular processes including bioenergetics, cellular metabolism, apoptosis, and cellular Ca signaling. The voltage-dependent anion channel (VDAC) functions as a passageway for the exchange of ions, including Ca, across the outer mitochondrial membrane. In cardiomyocytes, genetic or pharmacological activation of isoform 2 of VDAC (VDAC2) effectively potentiates mitochondrial Ca uptake and suppresses Ca overload-induced arrhythmogenic events.

Mitochondrial Calcium Uniporter Deficiency in Zebrafish Causes Cardiomyopathy With Arrhythmia.

Mitochondrial Ca uptake influences energy production, cell survival, and Ca signaling. The mitochondrial calcium uniporter, MCU, is the primary route for uptake of Ca into the mitochondrial matrix. We have generated a zebrafish mutant that survives to adulthood and exhibits dramatic cardiac phenotypes resembling cardiomyopathy and sinus arrest.

Integrin-alpha-6+ Candidate stem cells are responsible for whole body regeneration in the invertebrate chordate Botrylloides diegensis.

Colonial ascidians are the only chordates able to undergo whole body regeneration (WBR), during which entire new bodies can be regenerated from small fragments of blood vessels. Here, we show that during the early stages of WBR in Botrylloides diegensis, proliferation occurs only in small, blood-borne cells that express integrin-alpha-6 (IA6), pou3 and vasa. WBR cannot proceed when proliferating IA6+ cells are ablated with Mitomycin C, and injection of a single IA6+ Candidate stem cell can rescue WBR after ablation.

Catalytic Enantioselective Synthesis of Guvacine Derivatives through [4 + 2] Annulations of Imines with α-Methylallenoates.

P-Chiral [2.2.1] bicyclic phosphines (HypPhos catalysts) have been applied to reactions between α-alkylallenoates and imines, producing guvacine derivatives.

Multiscale light-sheet for rapid imaging of cardiopulmonary system.

The ability to image tissue morphogenesis in real-time and in 3-dimensions (3-D) remains an optical challenge. The advent of light-sheet fluorescence microscopy (LSFM) has advanced developmental biology and tissue regeneration research. In this review, we introduce a LSFM system in which the illumination lens reshapes a thin light-sheet to rapidly scan across a sample of interest while the detection lens orthogonally collects the imaging data.

The Calcineurin-FoxO-MuRF1 signaling pathway regulates myofibril integrity in cardiomyocytes.

Altered Ca handling is often present in diseased hearts undergoing structural remodeling and functional deterioration. However, whether Ca directly regulates sarcomere structure has remained elusive. Using a zebrafish mutant, we explored the impacts of impaired Ca homeostasis on myofibril integrity.

In vivo manipulation of the extracellular matrix induces vascular regression in a basal chordate.

We investigated the physical role of the extracellular matrix (ECM) in vascular homeostasis in the basal chordate , which has a large, transparent, extracorporeal vascular network encompassing an area >100 cm We found that the collagen cross-linking enzyme lysyl oxidase is expressed in all vascular cells and that in vivo inhibition using β-aminopropionitrile (BAPN) caused a rapid, global regression of the entire network, with some vessels regressing >10 mm within 16 h. BAPN treatment changed the ultrastructure of collagen fibers in the vessel basement membrane, and the kinetics of regression were dose dependent. Pharmacological inhibition of both focal adhesion kinase (FAK) and Raf also induced regression, and levels of phosphorylated FAK in vascular cells decreased during BAPN treatment and FAK inhibition but not Raf inhibition, suggesting that physical changes in the vessel ECM are detected via canonical integrin signaling pathways.

Tbx20 drives cardiac progenitor formation and cardiomyocyte proliferation in zebrafish.

Tbx20 is a T-box transcription factor that plays essential roles in the development and maintenance of the heart. Although it is expressed by cardiac progenitors in all species examined, an involvement of Tbx20 in cardiac progenitor formation in vertebrates has not been previously described. Here we report the identification of a zebrafish tbx20 mutation that results in an inactive, truncated protein lacking any functional domains.

Transcriptional Regulation of Heart Development in Zebrafish.

Cardiac transcription factors orchestrate the complex cellular and molecular events required to produce a functioning heart. Misregulation of the cardiac transcription program leads to embryonic developmental defects and is associated with human congenital heart diseases. Recent studies have expanded our understanding of the regulation of cardiac gene expression at an additional layer, involving the coordination of epigenetic and transcriptional regulators.

Temporally and spatially dynamic germ cell niches in Botryllus schlosseri revealed by expression of a TGF-beta family ligand and vasa.

Background: Germ cells are specified during early development and are responsible for generating gametes in the adult. After germ cells are specified, they typically migrate to a particular niche in the organism where they reside for the remainder of its lifetime. For some model organisms, the specification and migration of germ cells have been extensively studied, but how these events occur in animals that reproduce both sexually and asexually is not well understood.

Migration of germline progenitor cells is directed by sphingosine-1-phosphate signalling in a basal chordate.

The colonial ascidian Botryllus schlosseri continuously regenerates entire bodies in an asexual budding process. The germ line of the newly developing bodies is derived from migrating germ cell precursors, but the signals governing this homing process are unknown. Here we show that germ cell precursors can be prospectively isolated based on expression of aldehyde dehydrogenase and integrin alpha-6, and that these cells express germ cell markers such as vasa, pumilio and piwi, as well as sphingosine-1-phosphate receptor.

Molecular evolution and in vitro characterization of Botryllus histocompatibility factor.

Botryllus schlosseri is a colonial ascidian with a natural ability to anastomose with another colony to form a vascular and hematopoietic chimera. In order to fuse, two individuals must share at least one allele at the highly polymorphic fuhc locus. Otherwise, a blood-based inflammatory response will occur resulting in a melanin scar at the sites of interaction.

Aging in the colonial chordate, .

What mechanisms underlie aging? One theory, the wear-and-tear model, attributes aging to progressive deterioration in the molecular and cellular machinery which eventually lead to death through the disruption of physiological homeostasis. The second suggests that life span is genetically programmed, and aging may be derived from intrinsic processes which enforce a non-random, terminal time interval for the survivability of the organism. We are studying an organism that demonstrates both properties: the colonial ascidian, is a member of the Tunicata, the sister group to the vertebrates, and has a number of life history traits which make it an excellent model for studies on aging.

Analysis of the basal chordate Botryllus schlosseri reveals a set of genes associated with fertility.

Background: Gonad differentiation is an essential function for all sexually reproducing species, and many aspects of these developmental processes are highly conserved among the metazoa. The colonial ascidian, Botryllus schlosseri is a chordate model organism which offers two unique traits that can be utilized to characterize the genes underlying germline development: a colonial life history and variable fertility. These properties allow individual genotypes to be isolated at different stages of fertility and gene expression can be characterized comprehensively.

Whole-mount fluorescent in situ hybridization staining of the colonial tunicate Botryllus schlosseri.

Botryllus schlosseri is a colonial ascidian with characteristics that make it an attractive model for studying immunology, stem cell biology, evolutionary biology, and regeneration. Transcriptome sequencing and the recent completion of a draft genome sequence for B. schlosseri have revealed a large number of genes, both with and without vertebrate homologs, but analyzing the spatial and temporal expression of these genes in situ has remained a challenge.

The candidate histocompatibility locus of a Basal chordate encodes two highly polymorphic proteins.

The basal chordate Botryllus schlosseri undergoes a natural transplantation reaction governed by a single, highly polymorphic locus called the fuhc. Our initial characterization of this locus suggested it encoded a single gene alternatively spliced into two transcripts: a 555 amino acid-secreted form containing the first half of the gene, and a full-length, 1008 amino acid transmembrane form, with polymorphisms throughout the ectodomain determining outcome. We have now found that the locus encodes two highly polymorphic genes which are separated by a 227 bp intergenic region: first, the secreted form as previously described, and a second gene encoding a 531 amino acid membrane-bound gene containing three extracellular immunoglobulin domains.

Nuclear phosphatase PPM1G in cellular survival and neural development.

Background: PPM1G is a nuclear localized serine/threonine phosphatase implicated to be a regulator of chromatin remodeling, mRNA splicing, and DNA damage. However, its in vivo function is unknown.

Results: Here we show that ppm1g expression is highly enriched in the central nervous system during mouse and zebrafish development.

Sodium pump activity in the yolk syncytial layer regulates zebrafish heart tube morphogenesis.

Na(+),K(+) ATPase pumps Na(+) out of and K(+) into the cytosol, maintaining a resting potential that is essential for the function of excitable tissues like cardiac muscle. In addition to its well-characterized physiological role in the heart, Na(+),K(+) ATPase also regulates the morphogenesis of the embryonic zebrafish heart via an as yet unknown mechanism. Here, we describe a novel non-cell autonomous function of Na(+),K(+) ATPase/Atp1a1 in the elongation of the zebrafish heart tube.

The PAF1 complex differentially regulates cardiomyocyte specification.

The specification of an appropriate number of cardiomyocytes from the lateral plate mesoderm requires a careful balance of both positive and negative regulatory signals. To identify new regulators of cardiac specification, we performed a phenotype-driven ENU mutagenesis forward genetic screen in zebrafish. In our genetic screen we identified a zebrafish ctr9 mutant with a dramatic reduction in myocardial cell number as well as later defects in primitive heart tube elongation and atrioventricular boundary patterning.

The PAF1 complex component Leo1 is essential for cardiac and neural crest development in zebrafish.

Leo1 is a component of the Polymerase-Associated Factor 1 (PAF1) complex, an evolutionarily conserved protein complex involved in gene transcription regulation and chromatin remodeling. The role of leo1 in vertebrate embryogenesis has not previously been examined. Here, we report that zebrafish leo1 encodes a nuclear protein that has a similar molecular structure to Leo1 proteins from other species.