In vivo 'turn on' fluorescence detection of free cysteine in zebrafish kidney and liver.

Cysteine is directly associated with a wide range of biological processes. Besides its essential role in protein synthesis, cysteine undergoes a variety of post-translational modifications which modulate several physiological processes. Dysregulated cysteine metabolism is associated with several neurodegenerative disorders. Accordingly, restoring cysteine balance has therapeutic benefits. It is therefore essential to detect the presence of endogenous free cysteine in order to understand different physiological modes of action inside the cell. Here, a carbazole-pyridoxal conjugate system (CPLC) has been developed to detect endogenous free cysteine in the liver and kidney of an adult zebrafish. In consequence, we have also determined the fluorescence intensity statistics of zebrafish kidney and liver images. CPLC interacts in a very fascinating way with two cysteine molecules through chemodosimetric and chemosensing approaches which are conclusively proved by different spectroscopic analyses (UV-vis, fluorescence, NMR) and theoretical calculations (DFT). The detection limit of CPLC towards cysteine is 0.20 µM. Moreover, this preliminary experiment has been done using HuH-7 cell line to check the permeability of CPLC, interaction with cysteine intracellularly, and assessment of the toxicity of CPLC, if any, before performing details in-vivo experiments in zebrafish model.

An Indian Young-onset Dementia With Parkinsonism With Double Heterozygous Mutations in ABCA7 and PRKN Identified Through Whole-exome Sequencing.

Alzheimer disease and Parkinson disease dementia are the 2 most common neurodegenerative diseases have substantial overlap in pathologic, genetic, and clinical manifestation and complex in nature. Here, for the first time, we report an Indian female young patient who presented with clinical manifestation of both Alzheimer disease and Parkinsonism, including dystonia with rapid disease progression. We identified a heterozygous mutation in the ATP-binding cassette transporter A7 gene and double heterozygous mutation in PRKN by whole-exome sequencing. This case is an example of complex etiology of neurodegenerative disorders and highlights the importance of genetic tests, including whole-exome sequencing in complex diseases.

Endoderm-derived islet1-expressing cells differentiate into endothelial cells to function as the vascular HSPC niche in zebrafish.

Endothelial cells (ECs) line blood vessels and serve as a niche for hematopoietic stem and progenitor cells (HSPCs). Recent data point to tissue-specific EC specialization as well as heterogeneity; however, it remains unclear how ECs acquire these properties. Here, by combining live-imaging-based lineage-tracing and single-cell transcriptomics in zebrafish embryos, we identify an unexpected origin for part of the vascular HSPC niche. We find that islet1 (isl1)-expressing cells are the progenitors of the venous ECs that constitute the majority of the HSPC niche. These isl1-expressing cells surprisingly originate from the endoderm and differentiate into ECs in a process dependent on Bmp-Smad signaling and subsequently requiring npas4l (cloche) function. Single-cell RNA sequencing analyses show that isl1-derived ECs express a set of genes that reflect their distinct origin. This study demonstrates that endothelial specialization in the HSPC niche is determined at least in part by the origin of the ECs.

Cobalt-conjugated carbon quantum dots for in vivo monitoring of the pyruvate dehydrogenase kinase inhibitor drug dichloroacetic acid.

Dichloroacetic acid (DCA), an organohalide that present in environmental sample and biological systems, got high attention for its therapeutic potential as the inhibitor of pyruvate dehydrogenase kinase (PDK), elevated in obesity, diabetes, heart disease and cancer. Herein, we developed a Cobalt conjugated carbon quantum dots (N-CQDs/Co) that selectively detect DCA by fluorescence "turn-on" mechanism. Utilizing TEM, DLS, UV-vis and fluorescence spectroscopy, the mechanism has been thoroughly elucidated and is attributed to disaggregation induced enhancement (DIE). The limit of detection of the N-CQDs/Co complex is 8.7 µM. The structural characteristics and size of the N-CQDs and N-CQDS/Co complex have been verified using FT-IR, XPS, HRTEM, DLS, EDX have been performed. Additionally, the complex is used to specifically find DCA in the human cell line and in zebrafish.Journal instruction requires a city for affiliations; however, these are missing in affiliation [4]. Please verify if the provided city is correct and amend if necessary.Kharagpur is the city. The address is okay.

Regulatory T cells regulate blastemal proliferation during zebrafish caudal fin regeneration.

The role of T cells in appendage regeneration remains unclear. In this study, we revealed an important role for regulatory T cells (Tregs), a subset of T cells that regulate tolerance and tissue repair, in the epimorphic regeneration of zebrafish caudal fin tissue. Upon amputation, fin tissue-resident Tregs infiltrate into the blastema, a population of progenitor cells that produce new fin tissues. Conditional genetic ablation of Tregs attenuates blastemal cell proliferation during fin regeneration. Blastema-infiltrating Tregs upregulate the expression of igf2a and igf2b, and pharmacological activation of IGF signaling restores blastemal proliferation in Treg-ablated zebrafish. These findings further extend our understandings of Treg function in tissue regeneration and repair.

Diversity and function of motile ciliated cell types within ependymal lineages of the zebrafish brain.

Motile cilia defects impair cerebrospinal fluid (CSF) flow and can cause brain and spine disorders. The development of ciliated cells, their impact on CSF flow, and their function in brain and axial morphogenesis are not fully understood. We have characterized motile ciliated cells within the zebrafish brain ventricles. We show that the ventricles undergo restructuring through development, involving a transition from mono- to multiciliated cells (MCCs) driven by gmnc. MCCs co-exist with monociliated cells and generate directional flow patterns. These ciliated cells have different developmental origins and are genetically heterogenous with respect to expression of the Foxj1 family of ciliary master regulators. Finally, we show that cilia loss from the tela choroida and choroid plexus or global perturbation of multiciliation does not affect overall brain or spine morphogenesis but results in enlarged ventricles. Our findings establish that motile ciliated cells are generated by complementary and sequential transcriptional programs to support ventricular development.

Krüppel-like factor 1 is a core cardiomyogenic trigger in zebrafish.

Cardiac regeneration requires dedifferentiation and proliferation of mature cardiomyocytes, but the mechanisms underlying this plasticity remain unclear. Here, we identify a potent cardiomyogenic role for Krüppel-like factor 1 (Klf1/Eklf), which is induced in adult zebrafish myocardium upon injury. Myocardial inhibition of Klf1 function does not affect heart development, but it severely impairs regeneration. Transient Klf1 activation is sufficient to expand mature myocardium in uninjured hearts. Klf1 directs epigenetic reprogramming of the cardiac transcription factor network, permitting coordinated cardiomyocyte dedifferentiation and proliferation. Myocardial expansion is supported by Klf1-induced rewiring of mitochondrial metabolism from oxidative respiration to anabolic pathways. Our findings establish Klf1 as a core transcriptional regulator of cardiomyocyte renewal in adult zebrafish hearts.

Zebrafish Regulatory T Cells Mediate Organ-Specific Regenerative Programs.

The attenuation of ancestral pro-regenerative pathways may explain why humans do not efficiently regenerate damaged organs. Vertebrate lineages that exhibit robust regeneration, including the teleost zebrafish, provide insights into the maintenance of adult regenerative capacity. Using established models of spinal cord, heart, and retina regeneration, we discovered that zebrafish Treg-like (zTreg) cells rapidly homed to damaged organs. Conditional ablation of zTreg cells blocked organ regeneration by impairing precursor cell proliferation. In addition to modulating inflammation, infiltrating zTreg cells stimulated regeneration through interleukin-10-independent secretion of organ-specific regenerative factors (Ntf3: spinal cord; Nrg1: heart; Igf1: retina). Recombinant regeneration factors rescued the regeneration defects associated with zTreg cell depletion, whereas Foxp3a-deficient zTreg cells infiltrated damaged organs but failed to express regenerative factors. Our data delineate organ-specific roles for Treg cells in maintaining pro-regenerative capacity that could potentially be harnessed for diverse regenerative therapies.

Dissection of zebrafish shha function using site-specific targeting with a Cre-dependent genetic switch.

Despite the extensive use of zebrafish as a model organism in developmental biology and regeneration research, genetic techniques enabling conditional analysis of gene function are limited. In this study, we generated Zwitch, a Cre-dependent invertible gene-trap cassette, enabling the establishment of conditional alleles in zebrafish by generating intronic insertions via in vivo homologous recombination. To demonstrate the utility of Zwitch, we generated a conditional sonic hedgehog a (shha) allele. Homozygous shha mutants developed normally; however, shha mutant embryos globally expressing Cre exhibited strong reductions in endogenous shha and shha target gene mRNA levels and developmental defects associated with null shha mutations. Analyzing a conditional shha mutant generated using an epicardium-specific inducible Cre driver revealed unique roles for epicardium-derived Shha in myocardial proliferation during heart development and regeneration. Zwitch will extend the utility of zebrafish in organ development and regeneration research and might be applicable to other model organisms.

Zebrafish FOXP3 is required for the maintenance of immune tolerance.

Regulatory T (Treg) cells play a central role in the suppression of excessive immune responses against both self and non-self antigens. The development and function of Treg cells are controlled by a master regulatory gene encoding the forkhead box P3 (FOXP3) protein in mammals. However, little is known regarding the functions of Treg cells and FOXP3 in non-mammalian vertebrates. In this study, we generated mutant zebrafish lacking a functional FOXP3 ortholog, and demonstrated a significant reduction in survival accompanied by a marked increase in inflammatory gene expression, mononuclear cell infiltration, and T cell proliferation in peripheral tissues. Our findings indicate that the zebrafish FOXP3 protein may have an evolutionally conserved role in the control of immune tolerance, illuminating the potential of the zebrafish as a novel model for investigating the development and functions of Treg cells.