pinecone/core-2020-05-10-deduplication huggingface dataset:
Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: prevention with folic acid

Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known.

RESULTS:

Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbs multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis, and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions.

CONCLUSIONS:

Our results indicate that ethanol exposure interrupted divergent cardiac morphogenetic events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects
Requirement for commissureless2 function during dipteran insect nerve cord development

BACKGROUND:

In Drosophila melanogaster, commissureless (comm) function is required for proper nerve cord development. Although comm orthologs have not been identified outside of Drosophila species, some insects possess orthologs of Drosophila comm2, which may also regulate embryonic nerve cord development. Here, this hypothesis is explored through characterization of comm2 genes in two disease vector mosquitoes.

RESULTS:

Culex quinquefasciatus (West Nile and lymphatic filiariasis vector) has three comm2 genes that are expressed in the developing nerve cord. Aedes aegypti (dengue and yellow fever vector) has a single comm2 gene that is expressed in commissural neurons projecting axons toward the midline. Loss of comm2 function in both A. aegypti and D. melanogaster was found to result in loss of commissure defects that phenocopy the frazzled (fra) loss of function phenotypes observed in both species. Loss of fra function in either insect was found to result in decreased comm2 transcript levels during nerve cord development.

CONCLUSIONS:

The results of this investigation suggest that Fra down-regulates repulsion in precrossing commissural axons by regulating comm2 levels in both A. aegypti and D. melanogaster, both of which require Comm2 function for proper nerve cord development
Mathematical modelling of digit specification by a sonic hedgehog gradient

Background: The three chick wing digits represent a classical example of a pattern specified by a morphogen gradient. Here we have investigated whether a mathematical model of a Shh gradient can describe the specification of the identities of the three chick wing digits and if it can be applied to limbs with more digits. Results: We have produced a mathematical model for specification of chick wing digit identities by a Shh gradient that can be extended to the four digits of the chick leg with Shh-producing cells forming a digit. This model cannot be extended to specify the five digits of the mouse limb. Conclusions: Our data suggest that the parameters of a classical-type morphogen gradient are sufficient to specify the identities of three different digits. However, to specify more digit identities, this core mechanism has to be coupled to alternative processes, one being that in the chick leg and mouse limb, Shh-producing cells give rise to digits; another that in the mouse limb, the cellular response to the Shh gradient adapts over time so that digit specification does not depend simply on Shh concentration
Analysis of three μ1-AP1 subunits during zebrafish development

BACKGROUND: The family of AP-1 complexes mediates protein sorting in the late secretory pathway and it is essential for the development of mammals. The ubiquitously expressed AP-1A complex consists of four adaptins γ1, β1, μ1A, and σ1A. AP-1A mediates protein transport between the trans-Golgi network and early endosomes. The polarized epithelia AP-1B complex contains the μ1B-adaptin. AP-1B mediates specific transport of proteins from basolateral recycling endosomes to the basolateral plasma membrane of polarized epithelial cells.\ud
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RESULTS: Analysis of the zebrafish genome revealed the existence of three μ1-adaptin genes, encoding μ1A, μ1B, and the novel isoform μ1C, which is not found in mammals. μ1C shows 80% sequence identity with μ1A and μ1B. The μ1C expression pattern largely overlaps with that of μ1A, while μ1B is expressed in epithelial cells. By knocking-down the synthesis of μ1A, μ1B and μ1C with antisense morpholino techniques we demonstrate that each of these μ1 adaptins is essential for zebrafish development, with μ1A and μ1C being involved in central nervous system development and μ1B in kidney, gut and liver formation.\ud
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CONCLUSIONS: Zebrafish is unique in expressing three AP-1 complexes: AP-1A, AP-1B, and AP-1C. Our results demonstrate that they are not redundant and that each of them has specific functions, which cannot be fulfilled by one of the other isoforms. Each of the μ1 adaptins appears to mediate specific molecular mechanisms essential for early developmental processes, which depends on specific intracellular vesicular protein sorting pathways
A novel planar polarity genepepsinogen-likeregulateswinglessexpression in a posttranscriptional manner

Background: Planar cell polarity (PCP) originally referred to the coordination of global organ axes and individual cell polarity within the plane of the epithelium. More recently, it has been accepted that pertinent PCP regulators play essential roles not only in epithelial sheets, but also in various rearranging cells. Results: We identified pepsinogen-like (pcl) as a new planar polarity gene, using Drosophila wing epidermis as a model. Pcl protein is predicted to belong to a family of aspartic proteases. When pcl mutant clones were observed in pupal wings, PCP was disturbed in both mutant and wild-type cells that were juxtaposed to the clone border. We examined levels of known PCP proteins in wing imaginal discs. The amount of the seven-pass transmembrane cadherin Flamingo (Fmi), one of the PCP “core group” members, was significantly decreased in mutant clones, whereas neither the amount of nor the polarized localization of Dachsous (Ds) at cell boundaries was affected. In addition to the PCP phenotype, the pcl mutation caused loss of wing margins. Intriguingly, this was most likely due to a dramatic decrease in the level of Wingless (Wg) protein, but not due to a decrease in the level of wg transcripts. Conclusions: Our results raise the possibility that Pcl regulates Wg expression post-transcriptionally, and PCP, by proteolytic cleavages
Role of heparan sulfate proteoglycans in optic disc and stalk morphogenesis

Background

Heparan sulfate proteoglycans (HSPG) are important for embryonic development via the regulation of gradient formation and signaling of multiple growth factors and morphogens. Previous studies have shown that Bmp/Shh/Fgf signaling are required for the regionalization of the optic vesicle (OV) and for the closure of the optic fissure (OF), the disturbance of which underlie ocular anomalies such as microphthalmia, coloboma and optic nerve hypoplasia.
Results

To study HSPG-dependent coordination of these signaling pathways during mammalian visual system development, we have generated a series of OV-specific mutations in the heparan sulfate (HS) N-sulfotransferase genes (Ndst1 and Ndst2) and HS O-sulfotransferase genes (Hs2st, Hs6st1 and Hs6st2) in mice. Interestingly, the resulting HS undersulfation still allowed for normal retinal neurogenesis and optic fissure closure, but led to defective optic disc and stalk development. The adult mutant animals further developed optic nerve aplasia/hypoplasia and displayed retinal degeneration. We observed that MAPK/ERK signaling was down-regulated in Ndst mutants, and consistent with this, HS-related optic nerve morphogenesis defects in mutant mice could partially be rescued by constitutive Kras activation.
Conclusions

These results suggest that HSPGs, depending on their HS sulfation pattern, regulate multiple signaling pathways in optic disc and stalk morphogenesis
The chromatin remodeling protein CHD7, mutated in CHARGE syndrome, is necessary for proper craniofacial and tracheal development

Background:  Heterozygous mutations in the chromatin remodeling gene  CHD7  cause CHARGE syndrome, a developmental disorder with variable craniofacial dysmorphisms and respiratory difficulties. The molecular etiologies of these malformations are not well understood. Homozygous  Chd7  null mice die by E11, whereas  Chd7 Gt/+   heterozygous null mice are a viable and excellent model of CHARGE. We explored skeletal phenotypes in  Chd7 Gt/+   and  Chd7  conditional knockout mice, using  Foxg1‐Cre  to delete  Chd7  ( Foxg1 ‐CKO) in the developing eye, ear, nose, pharyngeal pouch, forebrain, and gut and  Wnt1‐Cre  ( Wnt1 ‐CKO) to delete  Chd7  in migrating neural crest cells.  Results:   Foxg1 ‐CKO mice exhibited postnatal respiratory distress and death, dysplasia of the eye, concha, and frontal bone, hypoplastic maxillary shelves and nasal epithelia, and reduced tracheal rings.  Wnt1‐ CKO mice exhibited frontal and occipital bone dysplasia, hypoplasia of the maxillary shelves and mandible, and cleft palate. In contrast, heterozygous  Chd7 Gt/+   mice had apparently normal skeletal development.  Conclusions:  Conditional deletion of  Chd7  in ectodermal and endodermal derivatives ( Foxg1‐Cre ) or migrating neural crest cells ( Wnt1‐Cre ) results in varied and more severe craniofacial defects than in  Chd7 Gt/+   mice. These studies indicate that CHD7 has an important, dosage‐dependent role in development of several different craniofacial tissues.  Developmental Dynamics 243:1055–1066, 2014 . © 2014 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.    Key findings:    Chd7 is necessary in craniofacial ectodermal, endodermal, and neural crest cells. Loss of Chd7 in mice results in upper and lower respiratory tract anomalies which mimic human CHARGE syndrome.  Chd7 is important for proper development of neural crest‐derived mesenchymal tissues contributing to bone and cartilage.  Loss of Wnt1Cre‐mediated Chd7 in neural crest cells does not result in heart defects.  Foxg1Cre‐mediated deletion of Chd7 leads to severe microphthalmia
Development of astrocytes in the vertebrate eye

Astrocytes represent the earliest glial population in the embryonic optic nerve, contributing critically to retinal angiogenesis and formation of brain-retinal-barrier. Despite of many developmental and clinical implications of astrocytes, answers to some of the most fundamental questions of this unique type of glial cells remain elusive. This review provides an overview of the current knowledge about the origination, proliferation, and differentiation of astrocytes, their journey from the optic nerve toward the neuroretina, and their involvement in physiological and pathological development of the visual system
Force transmission in epithelial tissues

In epithelial tissues, cells constantly generate and transmit forces between each other. Forces generated by the actomyosin cytoskeleton regulate tissue shape and structure and also provide signals that influence cells' decisions to divide, die, or differentiate. Forces are transmitted across epithelia because cells are mechanically linked through junctional complexes, and forces can propagate through the cell cytoplasm. Here, we review some of the molecular mechanisms responsible for force generation, with a specific focus on the actomyosin cortex and adherens junctions. We then discuss evidence for how these mechanisms promote cell shape changes and force transmission in tissues
Molecular analysis of a phylogenetically conserved carrot gene: developmental and environmental regulation

Article first published online: 6 FEB 2005Abstract 10.1002/dvg.1020110108.abs Extensive studies of gene expression programs in carrot somatic embryos identified a gene, designated Dc3, that serves as a reliable molecular marker for the acquisition of embryogenic potential by carrot cells in culture. The complete sequence of a carrot genomic region, DcG3, encoding a Dc3-like mRNA, was determined. The DcG3 transcription unit contains a single intron and encodes mRNA that is expressed at high levels in embryonic tissue but is undetectable in somatic tissue of carrot. The predicted protein sequence of DcG3 is 163 amino acids and includes two approximately 50 amino acid direct repeats which in turn include additional repetitive elements with an unusual distribution of charged amino acids. Dc3 and Dc3-like mRNAs are encoded by a small divergent gene family. Furthermore, similarities of the Dc3 gene family with genes from other plant species that are expressed in response to environmental and developmental cues suggest a possible role in seed desiccation and possibly in more general water-stiess responses in plants. Analysis of transgenic tobacco containing a β-glucuronidase (GUS) reporter gene fused to a 1.7 kb 5′ upstream element of DcG3 defined a promoter/enhancer complex that confers developmentally and environmentally regulated expression of GUS activity. Thus, DcG3 is phylogenetically conserved together with the trans-acting factors required for its regulated expression in transgenic tobacco.This research was supported by grants from the Texas Advanced Technology Research Program and USDA Competitive Grants\ud
84CRCR- 1 - 139 1 and 86CRCR- 1-2 143.Peer reviewe
Nas transgenic mouse line allows visualization of Notch pathway activity in vivo.

International audienceThe Notch signaling pathway plays multiple and important roles in mammals. However, several aspects of its action, in particular, the precise mapping of its sites of activity, remain unclear. To address this issue, we generated a transgenic line carrying a construct consisting of a nls-lacZ reporter gene under the control of a minimal promoter and multiple RBP-Jkappa binding sites. Here we show that this transgenic line, which we termed NAS (for Notch Activity Sensor), displays an expression profile that is consistent with current knowledge on Notch activity sites in mice, even though it may not report on all these sites. Moreover, we observe that NAS transgene expression is abolished in a RBP-Jkappa-deficient background, indicating that it indeed requires Notch/RBP-Jkappa signaling pathway activity. Thus, the NAS transgenic line constitutes a valuable and versatile tool to gain further insights into the complex and various functions of the Notch signaling pathway
Induction of apoptosis by Drosophila Myc

Myc proteins are essential regulators of cellular growth and proliferation during normal development. Activating mutations in myc genes result in excessive growth and are frequently associated with human cancers. At the same time, forced expression of Myc sensitizes vertebrate cells towards different pro-apoptotic stimuli. Recently, the ability of overexpressed Myc to induce cell-autonomous apoptosis has been shown to be evolutionarily conserved in Drosophila Myc (dMyc). Here, we show that dMyc induced apoptosis is accompanied by the induction of Drosophila p53 mRNA, but that dp53 activity is not essential for dMyc’s ability to induce apoptosis. Conversely, larvae carrying a hypomorphic dmyc mutation are more resistant to the apoptosis-promoting effects of X-irradiation. These data suggest that the control of apoptosis is a physiological function of Myc and that dMyc might play a role in the response to DNA damage
Generation of mice with a conditional allele for the p75 NTR  neurotrophin receptor gene

The p75 NTR  neurotrophin receptor has been implicated in multiple biological and pathological processes. While significant advances have recently been made in understanding the physiologic role of p75 NTR , many details and aspects remain to be determined. This is in part because the two existing knockout mouse models (Exons 3 or 4 deleted, respectively), both display features that defy definitive conclusions. Here we describe the generation of mice that carry a conditional p75 NTR  (p75 NTR‐FX ) allele made by flanking Exons 4–6, which encode the transmembrane and all cytoplasmic domains, by loxP sites. To validate this novel conditional allele, both neural crest‐specific p75 NTR /Wnt1‐Cre mutants and conventional p75 NTR  null mutants were generated. Both mutants displayed abnormal hind limb reflexes, implying that loss of p75 NTR  in neural crest‐derived cells causes a peripheral neuropathy similar to that seen in conventional p75 NTR  mutants. This novel conditional p75 NTR  allele will offer new opportunities to investigate the role of p75 NTR  in specific tissues and cells. genesis 49:862–869, 2011. © 2011 Wiley‐Periodicals, Inc
A novel  TaulacZ  allele reveals a requirement for  Pitx2  in formation of the mammillothalamic tract

The hypothalamic mammillary region is critical for spatial memory and vestibular processing.  Pitx2  encodes a paired‐like transcription factor that is highly expressed in the developing mammillary region and is required for subthalamic nucleus formation. Here we analyzed a loss of function  Pitx2 ‐ TaulacZ  knock‐in allele to study the effects of  Pitx2  deficiency on neuronal projections in the embryonic mammillary region.  Pitx2 ‐expressing neurons contribute axons to principal mammillary, mammillotegmental and mammillotectal tracts. Embryos with  Pitx2  deficiency exhibit axonal fibers in the principal mammillary tract that are improperly bundled and disorganized, yet project caudally toward the tectum and tegmentum. Embryos with  Nestin‐Cre  mediated conditional  Pitx2  deficiency exhibit truncated mammillothalamic tracts (mtt) that fail to elongate, and reduced  Pax6 ‐positive cells at the branching point of the principal mammillary and mtt. These data suggest that  Pitx2  mediates cell‐autonomous and nonautonomous guidance cues necessary for mammillary collaterals destined to project to the anterior thalamus. genesis 50:67–73, 2012. © 2011 Wiley Periodicals, Inc
An Embryonic Stem Cell-Based System for Rapid Analysis of Transcriptional Enhancers

With the growing use of genome-wide screens for cis-regulatory elements, there is a pressing need for platforms that enable fast and cost-effective experimental validation of identified hits in relevant developmental and tissue contexts. Here, we describe a murine embryonic stem cell (ESC)-based system that facilitates rapid analysis of putative transcriptional enhancers. Candidate enhancers are targeted with high efficiency to a defined genomic locus via recombinase-mediated cassette exchange. Targeted ESCs are subsequently differentiated in vitro into desired cell types, where enhancer activity is monitored by reporter gene expression. As a proof of principle, we analyzed a previously characterized, Sonic hedgehog (Shh)-dependent, V3 interneuron progenitor (pV3)-specific enhancer for the Nkx2.2 gene, and observed highly specific enhancer activity. Given the broad potential of ESCs to generate a spectrum of cell types, this system can serve as an effective platform for the characterization of gene regulatory networks controlling cell fate specification and cell function.Molecular and Cellular BiologyStem Cell and Regenerative BiologyOther Research Uni
Xenopus: An ideal system for chemical genetics

Chemical genetics, or chemical biology, has become an increasingly powerful method for studying biological processes. The main objective of chemical genetics is the identification and use of small molecules that act directly on proteins, allowing rapid and reversible control of activity. These compounds are extremely powerful tools for researchers, particularly in biological systems that are not amenable to genetic methods. In addition, identification of small molecule interactions is an important step in the drug discovery process. Increasingly, the African frog Xenopus is being used for chemical genetic approaches. Here, we highlight the advantages of Xenopus as a first-line in vivo model for chemical screening as well as for testing reverse engineering approaches. genesis 50:207–218, 2012. © 2012 Wiley Periodicals, Inc
Role of the gene Miniature in Drosophila wing maturation.

Miniature is an extracellular zona pellucida domain-containing protein, required for flattening of pupal wing epithelia in Drosophila. Here, we show that Miniature also plays an important role in the post-eclosion wing maturation processes triggered by the neurohormone bursicon. Wing expansion and epithelial apoptosis are drastically delayed in miniature loss-of-function mutants, and sped up upon overexpression of the protein in wings. Miniature acts upstream from the heterotrimeric Gs protein transducing the bursicon signal in wing epithelia. We propose that Miniature interacts with bursicon and regulates its diffusion through or stability within the wing tissue
Generation of mice carrying a knockout-first and conditional-ready allele of transforming growth factor beta2 gene

Transforming growth factor beta2 (TGFβ2) is a multifunctional protein which is expressed in several embryonic and adult organs. TGFB2 mutations can cause Loeys Dietz syndrome, and its dysregulation is involved in cardiovascular, skeletal, ocular, and neuromuscular diseases, osteoarthritis, tissue fibrosis, and various forms of cancer. TGFβ2 is involved in cell growth, apoptosis, cell migration, cell differentiation, cell-matrix remodeling, epithelial-mesenchymal transition, and wound healing in a highly context-dependent and tissue-specific manner. Tgfb2(-/-) mice die perinatally from congenital heart disease, precluding functional studies in adults. Here, we have generated mice harboring Tgfb2(βgeo) (knockout-first lacZ-tagged insertion) gene-trap allele and Tgfb2(flox) conditional allele. Tgfb2(βgeo/βgeo) or Tgfb2(βgeo/-) mice died at perinatal stage from the same congenital heart defects as Tgfb2(-/-) mice. β-galactosidase staining successfully detected Tgfb2 expression in the heterozygous Tgfb2(βgeo) fetal tissue sections. Tgfb2(flox) mice were produced by crossing the Tgfb2(+/βgeo) mice with the FLPeR mice. Tgfb2(flox/-) mice were viable. Tgfb2 conditional knockout (Tgfb2(cko/-) ) fetuses were generated by crossing of Tgfb2(flox/-) mice with Tgfb2(+/-) ; EIIaCre mice. Systemic Tgfb2(cko/-) embryos developed cardiac defects which resembled the Tgfb2(βgeo/βgeo) , Tgfb2(βgeo/-) , and Tgfb2(-/-) fetuses. In conclusion, Tgfb2(βgeo) and Tgfb2(flox) mice are novel mouse strains which will be useful for investigating the tissue specific expression and function of TGFβ2 in embryonic development, adult organs, and disease pathogenesis and cancer. genesi