pinecone/core-2020-05-10-deduplication huggingface dataset:
Human Cytotrophoblast Expression of the von Hippel–Lindau Protein Is Downregulated during Uterine Invasion in Situ and Upregulated by Hypoxia in Vitro

AbstractThe von Hippel–Lindau tumor-suppressor protein (pVHL) regulates the stability of HIF1α and HIF2α and thus is pivotal in cellular responses to changes in oxygen tension. Paradoxically, human cytotrophoblasts proliferate under hypoxic conditions comparable to those measured in the early gestation placenta (2% O2), but differentiate into tumorlike invasive cells under well-oxygenated conditions such as those found in the uterus. We sought to explain this phenomenon in terms of pVHL expression. In situ, pVHL immunolocalized to villous cytotrophoblast stem cells, and expression was enhanced at sites of cell column initiation; in both of these relatively hypoxic locations, cytoplasmic staining for HIF2α was also detected. As cytotrophoblasts attached to and invaded the uterus, which results in their increased exposure to oxygen, pVHL staining was abruptly downregulated concordant with localization of HIF2α to the nucleus. In vitro, hypoxia (2% O2) upregulated cytotrophoblast pVHL expression together with HIF2α, which localized to the cytoplasm; culture under well-oxygenated conditions greatly reduced levels of both molecules. These results, together with the placental defects previously observed in VHL−/− mice, suggest that pVHL is a component of the mechanism that transduces local differences in oxygen tension at the maternal–fetal interface to changes in the biological behavior of cytotrophoblasts. Furthermore, these data provide the first example of oxygen-dependent changes in pVHL abundance
Adenylyl Cyclase A Expression Is Tip-Specific in Dictyostelium Slugs and Directs StatA Nuclear Translocation and CudA Gene Expression

AbstractcAMP oscillations, generated by adenylyl cyclase A (ACA), coordinate cell aggregation in Dictyostelium and have also been implicated in organizer function during multicellular development. We used a gene fusion of the ACA promoter with a labile lacZ derivative to study the expression pattern of ACA. During aggregation, most cells expressed ACA, but thereafter expression was lost in all cells except those of the anterior tip. Before aggregation, ACA transcription was strongly upregulated by nanomolar cAMP pulses. Postaggregative transcription was sustained by nanomolar cAMP pulses, but downregulated by a continuous micromolar cAMP stimulus and by the stalk-cell-inducing factor DIF. Earlier work showed that the transcription factor StatA displays tip-specific nuclear translocation and directs tip-specific expression of the nuclear protein CudA, which is essential for culmination. Both StatA and CudA were present in nuclei throughout the entire slug in an aca null mutant that expresses ACA from the constitutive actin15 promoter. This suggests that the tip-specific expression of ACA directs tip-specific nuclear translocation of StatA and tip-specific expression of CudA
Bep4 Protein Is Involved in Patterning along the Animal–Vegetal Axis in the Paracentrotus lividus Embryo

AbstractIn sea urchin embryos, the initial animal–vegetal (AV) axis is specified during oogenesis but the mechanism is largely unknown. By using chemical reagents such as lithium, it is possible to shift the principal embryonic territories toward a vegetal fate. We have investigated the possibility of obtaining the same morphological effect as with lithium by utilizing Fabs against the maternal Bep4 protein that is localized in the animal part of Paracentrotus lividus egg and embryos. Incubation of fertilized eggs with Fabs against Bep4 protein causes exogastrulation at 48 h of development of P. lividus embryos, similar to embryos treated with lithium. This vegetalizing effect was ascertained by utilizing territorial markers such as EctoV, EndoI, and Ig8. The effect of Fabs against Bep4 on gene expression was observed by monitoring spatial expression of the hatching enzyme gene. A decreased expression domain compared to its normal spatial distribution was detected and this effect was again comparable to those obtained with lithium treatment. Association of Bep4 with a cadherin was demonstrated by immunoprecipitation and immunostaining experiments, and an involvement in cell signaling is discussed. In addition, treatment of embryos with anti-Bep4 Fabs causes an enhancement in the level and an expansion in the pattern of nuclear β-catenin. Moreover, this treatment also provokes a decrease of β-catenin in adherens junctions. Together, these data indicate that anti-Bep4 Fabs provoke a shift of the animal–vegetal boundary toward the animal pole and suggest an active role of Bep4 protein in patterning along the AV axis
pod-2, along with pod-1, Defines a New Class of Genes Required for Polarity in the Early Caenorhabditis elegans Embryo

AbstractThe asymmetric division of the one-cell Caenorhabditis elegans zygote gives rise to two cells of different size and fate, thereby establishing the animal's anterior–posterior (a-p) axis. Through genetics, a number of genes required for this polarity have been characterized, but many components remain unidentified. Recently, our laboratory discovered a mutation in the pod-1 gene (for polarity and osmotic defective) that uniquely perturbed polarity and osmotic protection. Here, we describe a new C. elegans polarity gene identified during screens for conditional embryonic lethals. Embryos in which this gene has been mutated show a loss of physical and developmental asymmetries in the one-cell embryo, including the mislocalization of PAR and POD-1 proteins required for early polarity. Furthermore, mutant embryos are osmotically sensitive, allowing us to designate this gene pod-2. Thus, pod-2, along with pod-1, defines a new class of C. elegans polarity genes. Genetic analyses indicate that pod-2 functions in the same pathway as pod-1. Temperature-shift studies indicate that pod-2 is required during oogenesis, indicating that aspects of embryonic polarization may precede fertilization. pod-2 mutant embryos also exhibit a unique germline inheritance defect in which germline identity localizes to the wrong spot in the one-cell embryo and is therefore inherited by the wrong cell at the four-cell stage. Our data suggest that pod-2 may be required to properly position an a-p polarity cue
Early Morphogenesis of the Caenorhabditis elegans Pharynx

AbstractWe investigated the cellular behaviors that accompany the early stages of pharyngeal morphogenesis in Caenorhabditis elegans. The embryonic pharynx develops from a ball of cells into a linear tube connected anteriorly to the buccal cavity and posteriorly to the midgut. By using GFP reporters localized to discrete subcellular regions, we show that pharyngeal morphogenesis can be divided into three stages: (1) lengthening of the nascent pharyngeal lumen by reorientation of apicobasal polarity of anterior pharyngeal cells (“Reorientation”), (2) formation of an epithelium by the buccal cavity cells, which mechanically couples the buccal cavity to the pharynx and anterior epidermis (“Epithelialization”), and (3) a concomitant movement of the pharynx anteriorly and the epidermis of the mouth posteriorly to bring the pharynx, buccal cavity, and mouth into close apposition (“Contraction”). Several models can account for these cellular behaviors, and we distinguish between them by physically or genetically ablating cells within the digestive tract. These studies provide the first description of how the pharynx primordium develops into an epithelial tube, and reveal that pharyngeal morphogenesis resembles aspects of mammalian kidney tubulogenesis
Cell Death and Neuronal Replacement during Formation of the Avian Ciliary Ganglion

AbstractProgrammed cell death is a prominent feature of embryonic development and is essential in matching the number of neurons to the target tissues that are innervated. Although a decrease in neuronal number which coincides with peripheral synaptogenesis has been well documented in the avian ciliary ganglion, it has not been clear whether cell death also occurs earlier. We observed TUNEL-positive neurons as early as stage 24, with a large peak at stage 29. This cell death at stage 29 was followed by a statistically significant (P < 0.0001) decrease in total neuron number at stage 31. The total number of neurons was recovered by stage 33/34. This suggested that dying neurons were replaced by new neurons. This replacement process did not involve proliferation because bromodeoxyuridine applied at stages 29 and 31 was unable to label neurons harvested at stage 33/34. The peak of cell death at stage 29 was increased 2.3-fold by removal of the optic vesicle and was reduced by 50% when chCNTF was overexpressed. Taken together, these results suggest that the regulation of neuron number in the ciliary ganglion is a dynamic process involving both cell death and neural replacement from postmitotic precursors prior to differentiation and innervation of target tissues
Lateral Line Placodes Are Induced during Neurulation in the Axolotl

AbstractIn order to determine the time window for induction of lateral line placodes in the axolotl, we performed two series of heterotopic and isochronic transplantations from pigmented to albino embryos at different stages of embryogenesis and assessed the distribution of pigmented neuromasts in the hosts at later stages. First, ectoderm from the prospective placodal region was transplanted to the belly between early neurula and mid tailbud stages (stages 13–27). Whereas grafts from early neurulae typically differentiated only into epidermis, grafts from late neural fold stages on reliably resulted in differentiation of ectopic pigmented neuromasts. Second, belly ectoderm was transplanted to the prospective placodal region between early neurula and tailbud stages (stages 13–35). Normal lateral lines containing pigmented neuromasts formed in most embryos when grafts were performed prior to early tailbud stages (stage 24) but not when they were performed later. Our findings indicate that lateral line placodes, from which neuromasts originate, are already determined at late neural fold stages (first series of grafts) but are inducible until early tailbud stages (second series of grafts). A further series of heterochronic transplantations demonstrated that the decline of inducibility at mid tailbud stages is mainly due to the loss of ectodermal competence
Vertebrate Proteins Related to Drosophila Naked Cuticle Bind Dishevelled and Antagonize Wnt Signaling

AbstractWnt signals control cell fate decisions and orchestrate cell behavior in metazoan animals. In the fruit fly Drosophila, embryos defective in signaling mediated by the Wnt protein Wingless (Wg) exhibit severe segmentation defects. The Drosophila segment polarity gene naked cuticle (nkd) encodes an EF hand protein that regulates early Wg activity by acting as an inducible antagonist. Nkd antagonizes Wg via a direct interaction with the Wnt signaling component Dishevelled (Dsh). Here we describe two mouse and human proteins, Nkd1 and Nkd2, related to fly Nkd. The most conserved region among the fly and vertebrate proteins, the EFX domain, includes the putative EF hand and flanking sequences. EFX corresponds to a minimal domain required for fly or vertebrate Nkd to interact with the basic/PDZ domains of fly Dsh or vertebrate Dvl proteins in the yeast two-hybrid assay. During mouse development, nkd1 and nkd2 are expressed in multiple tissues in partially overlapping, gradient-like patterns, some of which correlate with known patterns of Wnt activity. Mouse Nkd1 can block Wnt1-mediated, but not β-catenin-mediated, activation of a Wnt-dependent reporter construct in mammalian cell culture. Misexpression of mouse nkd1 in Drosophila antagonizes Wg function. The data suggest that the vertebrate Nkd-related proteins, similar to their fly counterpart, may act as inducible antagonists of Wnt signals
Hox11 Acts Cell Autonomously in Spleen Development and Its Absence Results in Altered Cell Fate of Mesenchymal Spleen Precursors

AbstractThe genetic steps governing development of the spleen are largely unknown. Absence of Hox11 in mice results in asplenia, but it is unclear how Hox11 exerts its effect on spleen development. To more precisely define Hox11's role in spleen morphogenesis, we have examined the fate of the developing spleen in Hox11−/− mice. Perturbation of spleen development begins between dE13 and dE13.5. Cells of the spleen anlage persist past this developmental stage as an unorganized rudiment between the stomach and the pancreas. They fail to proliferate, and haematopoietic cells do not colonize the rudiment. At later stages of embryonic development, the cells can be observed in the mesenchyme of the pancreas, also an expression site of Hox11. In Hox11−/−↔+/+ chimaeras, spleens were devoid of Hox11−/− cells, indicating that the genetic defect is cell autonomous and not due to failure of the organ anlage to attract and retain haematopoietic cells. In −/−↔+/+ chimaeric embryos, Hox11−/− cells were initially present in the spleen anlage. However, at dE13, a reorganization of the spleen occurred in the chimaeras and Hox11−/− cells were subsequently excluded from the spleen, suggesting that a change in the affinity for one of the spleen cells had occurred. These observations demonstrate that spleen development consists of genetically separable steps and that absence of Hox11 arrests spleen development at an early stage. The formation of the spleen primordium before the entry of haematopoietic cells does not require the activity of Hox11. However, subsequent differentiation of spleen precursor cells is dependent on the Hox11 gene
Neurotrophins Are Not Required for Normal Embryonic Development of Olfactory Neurons

AbstractNeurons of the vertebrate olfactory epithelium (OE) regenerate continuously throughout life. The capacity of these neurons to regenerate and make new and precise synaptic connections in the olfactory bulb provides a useful model to study factors that may control or mediate neuronal regeneration. Expression and in vitro studies have suggested potential roles for the neurotrophins in the olfactory system. To directly examine whether neurotrophins are required for olfactory neuron development, we characterized in vivo the role of the neurotrophins in the primary olfactory system. For this, we generated mutant mice for TrkA, TrkB, TrkC, and also for BDNF and NT3 together with P2-IRES-tau-LacZ trangenic mice. Histochemical staining for β-galactosidase at birth allowed in vivo analysis of the P2 subpopulation of olfactory neurons as well as their projections to the olfactory bulb. Our data indicate that Trk signaling is not required for normal embryonic development of the olfactory system
The Wheels Mutation in the Mouse Causes Vascular, Hindbrain, and Inner Ear Defects

AbstractIn a screen for mouse mutations with dominant behavioral anomalies, we identified Wheels, a mutation associated with circling and hyperactivity in heterozygotes and embryonic lethality in homozygotes. Mutant Wheels embryos die at E10.5–E11.5 and exhibit a host of morphological anomalies which include growth retardation and anomalies in vascular and hindbrain development. The latter includes perturbation of rhombomeric boundaries as detected by Krox20 and Hoxb1. PECAM-1 staining of embryos revealed normal formation of the primary vascular plexus. However, subsequent stages of branching and remodeling do not proceed normally in the yolk sac and in the embryo proper. To obtain insights into the circling behavior, we examined development of the inner ear by paint-filling of membranous labyrinths of Whl/+ embryos. This analysis revealed smaller posterior and lateral semicircular canal primordia and a delay in the canal fusion process at E12.5. By E13.5, the lateral canal was truncated and the posterior canal was small or absent altogether. Marker analysis revealed an early molecular phenotype in heterozygous embryos characterized by perturbed expression of Bmp4 and Msx1 in prospective lateral and posterior cristae at E11.5. We have constructed a genetic and radiation hybrid map of the centromeric portion of mouse Chromosome 4 across the Wheels region and refined the position of the Wheels locus to the ∼1.1-cM region between D4Mit104 and D4Mit181. We have placed the locus encoding Epha7, in the Wheels candidate region; however, further analysis showed no mutations in the Epha7-coding region and no detectable changes in mRNA expression pattern. In summary, our findings indicate that Wheels, a gene which is essential for the survival of the embryo, may link diverse processes involved in vascular, hindbrain, and inner ear development
Tracing Transgene Expression in Living Zebrafish Embryos

AbstractEctopic expression by injection of plasmid DNA is rarely used in zebrafish embryos due to a low frequency of cells expressing a transgene of interest at detectable levels. Furthermore, the mosaic nature of ectopic expression by plasmid injection requires the direct detection of transgene-expressing cells. We have used the transcriptional activator Gal4-VP16 to amplify transgene expression in living zebrafish embryos. In comparison to conventional expression vectors, Gal4-VP16-amplified expression results in a significant higher number of cells which express a transgene at detectable levels. The Gal4-VP16-activator and the Gal4-VP16-dependent transgene can be placed on a single expression vector. Using tissue-specific regulatory elements, we show that expression of a Gal4-VP16-dependent transgene can be reliably restricted to muscle, notochordal, or neuronal tissues. Furthermore, Gal4-VP16 can drive the expression of two or more transgenes from the same construct resulting in simultaneous coexpression of both genes in virtually all expressing cells. The reported expression system works effectively not only in zebrafish embryos but also in Xenopus embryos, chicken, mouse, and human cultured cells and is thus applicable to a broad variety of vertebrates. The high frequency of transgene expression together with the linked coexpression of more than one transgene opens the possibility of easily monitoring the behavior of individual transgene-expressing cells in real time by labeling them with the fluorescent reporter GFP. The combinatorial nature of the expression system greatly facilitates changing the tissue-specificity, the transgene expressed, or the cell compartment-specific GFP reporter, making it simpler to address a gene's function in different tissues as well as its cell biological consequences
Developmental Expression of Mouse Krüppel-like Transcription Factor KLF7 Suggests a Potential Role in Neurogenesis

AbstractTo identify potential functions for the Krüppel-like transcription factor KLF7, we have determined the spatiotemporal pattern of gene expression during embryogenesis and in the adult organism. We show that the profile of Klf7 expression predominantly involves the central and peripheral nervous systems and is broadly identified by three separate phases. The first phase occurs early in embryogenesis with increasingly strong expression in the spinal cord, notably in motor neurons of the ventral horn, in dorsal root ganglia, and in sympathetic ganglia. The second robust phase of Klf7 expression is confined to the early postnatal cerebral cortex and is downregulated thereafter. The third phase is characterized by high and sustained expression in the adult cerebellum and dorsal root ganglia. Functionally, these three phases coincide with establishment of neuronal phenotype in embryonic spinal cord, with synaptogenesis and development of mature synaptic circuitry in the postnatal cerebral cortex, and with survival and/or maintenance of function of adult sensory neurons and cerebellar granule cells. Consistent with Klf7 expression in newly formed neuroblasts, overexpression of the gene in cultured fibroblasts and neuroblastoma cells repressed cyclin D1, activated p21, and led to G1 growth arrest. Based on these data, we argue for multiple potential functions for KLF7 in the developing and adult nervous system; they include participating in differentiation and maturation of several neuronal subtypes and in phenotypic maintenance of mature cerebellar granule cells and dorsal root ganglia
The BMP Family Member Gdf7 Is Required for Seminal Vesicle Growth, Branching Morphogenesis, and Cytodifferentiation

AbstractEpithelial–mesenchymal interactions play an important role in the development of many different organs and tissues. The secretory glands of the male reproductive system, including the prostate and seminal vesicles, are derived from epithelial precursors. Signals from the underlying mesenchyme are required for normal growth, branching, and differentiation of the seminal vesicle epithelium. Here, we show that a member of the BMP family, Gdf7, is required for normal seminal vesicle development. Expression and tissue recombination experiments suggest that Gdf7 is a mesenchymal signal that acts in a paracrine fashion to control the differentiation of the seminal vesicle epithelium
NeuroD2 Is Necessary for Development and Survival of Central Nervous System Neurons

AbstractNeuroD2 is sufficient to induce cell cycle arrest and neurogenic differentiation in nonneuronal cells. To determine whether this bHLH transcription factor was necessary for normal brain development, we used homologous recombination to replace the neuroD2 coding region with a β-galactosidase reporter gene. The neuroD2 gene expressed the reporter in a subset of neurons in the central nervous system, including in neurons of the neocortex and hippocampus and cerebellum. NeuroD2−/− mice showed normal development until about day P14, when they began exhibiting ataxia and failure to thrive. Brain areas that expressed neuroD2 were smaller than normal and showed higher rates of apoptosis. Cerebella of neuroD2-null mice expressed reduced levels of genes encoding proteins that support cerebellar granule cell survival, including brain-derived neurotrophic factor (BDNF). Decreased levels of BDNF and higher rates of apoptosis in cerebellar granule cells of neuroD2−/− mice indicate that neuroD2 is necessary for the survival of specific populations of central nervous system neurons in addition to its known effects on cell cycle regulation and neuronal differentiation
Ovulation Triggers Activation of Drosophila Oocytes

AbstractDrosophila melanogaster mature oocytes in ovaries are arrested at metaphase I of meiosis. Eggs that have reached the uterus have released this arrest. It was not known where in the female reproductive tract egg activation occurs and what triggers it. We investigated when and where the egg is activated in Drosophila in vivo and at what meiotic stage the egg is fertilized. We found that changes in the egg's envelope's permeability, one feature of activation, initiate during ovulation, even while most of the egg is still within the ovary. The egg becomes impermeable as it proceeds down the oviducts; the process is complete by the time the egg is in the uterus. Cross-linking of vitelline membrane protein sV23 also increases progressively as the egg moves through the oviducts and the uterus. Activation also triggers meiosis to resume before the egg reaches the uterus, such that the earliest eggs that reach the uterus are in anaphase I. We discuss models for Drosophila egg activation in vivo