Conserved chromatin and repetitive patterns reveal slow genome evolution in frogs.

Frogs are an ecologically diverse and phylogenetically ancient group of anuran amphibians that include important vertebrate cell and developmental model systems, notably the genus Xenopus. Here we report a high-quality reference genome sequence for the western clawed frog, Xenopus tropicalis, along with draft chromosome-scale sequences of three distantly related emerging model frog species, Eleutherodactylus coqui, Engystomops pustulosus, and Hymenochirus boettgeri. Frog chromosomes have remained remarkably stable since the Mesozoic Era, with limited Robertsonian (i.

Minireview: Glucocorticoid-Leptin Crosstalk: Role of Glucocorticoid-Leptin Counterregulation in Metabolic Homeostasis and Normal Development.

Glucocorticoids and leptin are two important hormones that regulate metabolic homeostasis by controlling appetite and energy expenditure in adult mammals. Also, glucocorticoids and leptin strongly counterregulate each other, such that chronic stress-induced glucocorticoids upregulate the production of leptin and leptin suppresses glucocorticoid production directly via action on endocrine organs and indirectly via action on food intake. Altered glucocorticoid or leptin levels during development can impair organ development and increase the risk of chronic diseases in adults, but there are limited studies depicting the significance of glucocorticoid-leptin interaction during development and its impact on developmental programming.

Characterization of a novel corticosterone response gene in tadpole tails.

Corticosteroids are critical for development and for mediating stress responses across diverse vertebrate taxa. Study of frog metamorphosis has made significant breakthroughs in our understanding of corticosteroid signaling during development in non-mammalian vertebrate species. However, lack of adequate corticosterone (CORT) response genes in tadpoles make identification and quantification of CORT responses challenging.

Crosstalk between Thyroid Hormone and Corticosteroid Signaling Targets Cell Proliferation in Tadpole Liver.

Thyroid hormones (TH) and glucocorticoids (GC) are involved in numerous developmental and physiological processes. The effects of individual hormones are well documented, but little is known about the joint actions of the two hormones. To decipher the crosstalk between these two hormonal pathways, we conducted a transcriptional analysis of genes regulated by TH, GC, or both hormones together in liver of tadpoles using RNA-Seq.

Development and metamorphosis in frogs deficient in the thyroid hormone transporter MCT8.

Precisely regulated thyroid hormone (TH) signaling within tissues during frog metamorphosis gives rise to the organism-wide coordination of developmental events among organs required for survival. This TH signaling is controlled by multiple cellular mechanisms, including TH transport across the plasma membrane. A highly specific TH transporter has been identified, namely monocarboxylate transporter 8 (MCT8), which facilitates uptake and efflux of TH and is differentially and dynamically expressed among tissues during metamorphosis.

cyp21a2 Knockout Tadpoles Survive Metamorphosis Despite Low Corticosterone.

Corticosteroids are so vital for organ maturation that reduced corticosteroid signaling during postembryonic development causes death in terrestrial vertebrates. Indeed, death occurs at metamorphosis in frogs lacking proopiomelanocortin (pomc) or the glucocorticoid receptor (GR; nr3c1). Some residual corticosteroids exist in pomc mutants to activate the wild-type (WT) GR and mineralocorticoid receptor (MR), and the elevated corticosteroids in GR mutants may activate MR.

Normal Table of Xenopus development: a new graphical resource.

Normal tables of development are essential for studies of embryogenesis, serving as an important resource for model organisms, including the frog Xenopus laevis. Xenopus has long been used to study developmental and cell biology, and is an increasingly important model for human birth defects and disease, genomics, proteomics and toxicology. Scientists utilize Nieuwkoop and Faber's classic 'Normal Table of Xenopus laevis (Daudin)' and accompanying illustrations to enable experimental reproducibility and reuse the illustrations in new publications and teaching.

Impaired negative feedback and death following acute stress in glucocorticoid receptor knockout Xenopus tropicalis tadpoles.

Blood glucocorticoid levels are regulated by the hypothalamo-pituitary-adrenal/interrenal axis (HPA axis in mammals, HPI axis in amphibians), and negative feedback by glucocorticoid signaling is a key player in that regulation. Glucocorticoid and mineralocorticoid receptors (GR and MR) mediate negative feedback in mammals, but little is known about nuclear receptor-mediated feedback in amphibians. Because amphibians have only one corticosteroidogenic cell type responsible for glucocorticoid and mineralocorticoid production, we hypothesized that GR knockout (GRKO) tadpoles have elevated levels of glucocorticoids and mineralocorticoids as well as axis components regulating their production.

Thyroid and Corticosteroid Signaling in Amphibian Metamorphosis.

In multicellular organisms, development is based in part on the integration of communication systems. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-adrenal/interrenal axes, are central players in orchestrating body morphogenesis. In all vertebrates, the hypothalamic-pituitary-thyroid axis controls thyroid hormone production and release, whereas the hypothalamic-pituitary-adrenal/interrenal axis regulates the production and release of corticosteroids.

Glucocorticoid receptor mediates corticosterone-thyroid hormone synergy essential for metamorphosis in Xenopus tropicalis tadpoles.

In all vertebrates, thyroid hormone (TH) is critical for normal growth and development. In amphibians, corticosterone (CORT) has no action to advance development by itself but can accelerate development induced by TH. CORT accomplishes this acceleration by increasing tissue sensitivity and responsivity to TH.

Axial Skeletal Malformations in Genetically Modified and .

Skeletal malformations in captive-bred, adult spp., have not previously been reported. Here we describe 10 sexually mature, genetically modified laboratory frogs (6 and 4 ) with axial skeletal abnormalities.

Corticosterone Is Essential for Survival Through Frog Metamorphosis.

Thyroid hormone (TH) is required for frog metamorphosis, and corticosterone (CORT) increases TH signaling to accelerate metamorphic progression. However, a requirement for CORT in metamorphosis has been difficult to assess prior to the recent development of gene-editing technologies. We addressed this long-standing question using transcription activator-like effector nuclease (TALEN) gene disruption to knock out proopiomelanocortin (pomc) and disrupt CORT production in Xenopus tropicalis.

Artificial Solid Electrolyte Interphases for Lithium Metal Electrodes by Wet Processing: The Role of Metal Salt Concentration and Solvent Choice.

In this study, the artificial solid electrolyte interphase (SEI) formed on lithium metal when treated in ZnCl solutions is thoroughly investigated. The artificial SEI on lithium metal electrodes substantially decreases the interfacial resistance by ca. 80% and improves cycling stability in comparison to untreated lithium.

Structural Investigation of Quaternary Layered Oxides upon Na-Ion Deinsertion.

Na-ion batteries are emerging alternatives to Li-ion chemistries for large-scale energy storage applications. Quaternary layered oxide NaMnNiFeMgO offers outstanding electrochemical performance in Na-ion batteries compared to pure-phase layered oxides because of the synergistic effect of the P/O-phase mixing. The material is indeed constituted by a mixture of P3, P2, and O3 phases, and a newly identified Na-free phase, i.

Stem cell development involves divergent thyroid hormone receptor subtype expression and epigenetic modifications in the Xenopus metamorphosing intestine.

In the intestine during metamorphosis of the frog Xenopus laevis, most of the larval epithelial cells are induced to undergo apoptosis by thyroid hormone (TH), and under continued TH action, the remaining epithelial cells dedifferentiate into stem cells (SCs), which then newly generate an adult epithelium analogous to the mammalian intestinal epithelium. Previously, we have shown that the precursors of the SCs that exist in the larval epithelium as differentiated absorptive cells specifically express receptor tyrosine kinase-like orphan receptor 2 (Ror2). By using Ror2 as a marker, we have immunohistochemically shown here that these SC precursors, but not the larval epithelial cells destined to die by apoptosis, express TH receptor α (TRα).

Glucocorticoid receptor is required for survival through metamorphosis in the frog Xenopus tropicalis.

Stress hormones, also known as glucocorticoids, are critical for survival at birth in mammals due at least in part to their importance in lung maturation. However, because air breathing is not always required for amphibian survival and because stress hormones have no known developmental impact except to modulate the developmental actions of thyroid hormone (TH), the requirement for stress hormone signaling during metamorphosis is not well understoodi. Here, we produced a glucocorticoid receptor knockout (GRKO) Xenopus line with a frameshift mutation in the first exon of the glucocorticoid receptor.

Novel vectors for functional interrogation of Xenopus ORFeome coding sequences.

The current Xenopus ORFeome contains ~10,250 validated, full-length cDNA sequences without stop codons from Xenopus laevis and ~3,970 from Xenopus tropicalis cloned into Gateway-compatible entry vectors. To increase the utility of the ORFeome, we have constructed the Gateway-compatible destination vectors pDXTP and pDXTR, which in combination can control the spatial and temporal expression of any open reading frame (ORF). pDXTP receives a promoter/enhancer of interest, which controls the spatial expression of a doxycycline-inducible transcription factor rtTA.

Insufficiency of Thyroid Hormone in Frog Metamorphosis and the Role of Glucocorticoids.

Thyroid hormone (TH) is the most important hormone in frog metamorphosis, a developmental process which will not occur in the absence of TH but can be induced precociously by exogenous TH. However, such treatments including TH treatments often do not replicate the events of natural metamorphosis in many organs, including lung, brain, blood, intestine, pancreas, tail, and skin. A potential explanation for the discrepancy between natural and TH-induced metamorphosis is the involvement of glucocorticoids (GCs).

Three-Year Outcomes With Hypofractionated Versus Conventionally Fractionated Whole-Breast Irradiation: Results of a Randomized, Noninferiority Clinical Trial.

Purpose: The adoption of hypofractionated whole-breast irradiation (HF-WBI) remains low, in part because of concerns regarding its safety when used with a tumor bed boost or in patients who have received chemotherapy or have large breast size. To address this, we conducted a randomized, multicenter trial to compare conventionally fractionated whole-breast irradiation (CF-WBI; 50 Gy/25 fx + 10 to 14 Gy/5 to 7 fx) with HF-WBI (42.56 Gy/16 fx + 10 to 12.

Impact of the Acid Treatment on Lignocellulosic Biomass Hard Carbon for Sodium-Ion Battery Anodes.

The investigation of phosphoric acid treatment on the performance of hard carbon from a typical lignocellulosic biomass waste (peanut shell) is herein reported. A strong correlation is discovered between the treatment time and the structural properties and electrochemical performance in sodium-ion batteries. Indeed, a prolonged acid treatment enables the use of lower temperatures, that is, lower energy consumption, for the carbonization step as well as improved high-rate performance (122 mAh g at 10 C).

Methods for Investigating the Larval Period and Metamorphosis in .

Anuran metamorphosis resembles postembryonic development in mammals, a period around birth when many organs/tissues mature into their adult form as circulating thyroid and stress hormone levels are high. Unlike uterus-enclosed mammalian embryos, tadpoles develop externally and undergo the dramatic changes of hormone-dependent development totally independent of maternal influence, making them a valuable model in which to study vertebrate postembryonic organ development and maturation. Various protocols have been developed and/or adapted for studying metamorphosis in and , two highly related and well-studied frog species.

Dual function model revised by thyroid hormone receptor alpha knockout frogs.

All vertebrates require thyroid hormone (TH) for normal growth and development. Plasma TH enters cells and alters gene expression via nuclear receptors TRα and TRβ. In-vitro studies showed that TRs function as repressors of TH-inducible genes in the absence of TH and as activators of those same genes in the presence of TH.

Towards High-Performance Aqueous Sodium-Ion Batteries: Stabilizing the Solid/Liquid Interface for NASICON-Type Na VTi(PO ) using Concentrated Electrolytes.

Aqueous Na-ion batteries may offer a solution to the cost and safety issues of high-energy batteries. However, substantial challenges remain in the development of electrode materials and electrolytes enabling high performance and long cycle life. Herein, we report the characterization of a symmetric Na-ion battery with a NASICON-type Na VTi(PO ) electrode material in conventional aqueous and "water-in-salt" electrolytes.

Functional analysis of thyroid hormone receptor beta in founders using CRISPR-Cas.

Amphibians provide an ideal model to study the actions of thyroid hormone (TH) in animal development because TH signaling via two TH receptors, TRα and TRβ, is indispensable for amphibian metamorphosis. However, specific roles for the TRβ isoform in metamorphosis are poorly understood. To address this issue, we generated disrupted tadpoles using the CRISPR-Cas system We first established a highly efficient and rapid workflow for gene disruption in the founder generation (F0) by injecting sgRNA and Cas9 ribonucleoprotein.

A novel stress hormone response gene in tadpoles of Xenopus tropicalis.

Previous work identified a transcribed locus, Str. 34945, induced by the frog stress hormone corticosterone (CORT) in Xenopus tropicalis tails. Because thyroid hormone had no influence on its expression, Str.