pinecone/core-2020-05-10-deduplication huggingface dataset:
Characterisation of Amphioxus HNF-3 Genes: Conserved Expression in the Notochord and Floor Plate

AbstractThefork head/HNF-3genes form a subclass of a family of transcription factors united by the possession of a conserved DNA binding domain known as the fork head domain. Most vertebrate HNF-3 class genes show several conserved sites of expression during development, including the dorsal lip/Hensen's node, notochord and floor plate, all structures known to organise adjacent tissues. In this paper I report the characterisation of HNF-3 class genes from the cephalochordate amphioxus. I show that amphioxus has two HNF-3 class genes, namedAmHNF-3-1andAmHNF-3-2; molecular phylogenetic analysis reveals that these derive from an independent duplication in the cephalochordate lineage. The expression of both genes in early development appears identical and shows striking similarities to that of vertebrates. In neurulae, transcripts of both genes were detected in the presumed organiser, endoderm, and notochord, supporting morphological and embryological evidence that these are homologous between vertebrates and amphioxus. This expression pattern overlaps considerably with that of amphioxusbrachyury,suggesting that the functional relationship between these genes in vertebrates is conserved with amphioxus. Expression of both genes was maintained in the endoderm and notochord up to the 6 somite stage. After the 6 somite stage no expression ofAmHNF-3-2was detected and expression ofAmHNF-3-1began to decrease in the notochord, such that by the 10 somite stage transcripts were only detected in the terminal regions. At this stage, however, a column ofAmHNF-3-1-expressing cells was detected at the ventral midline of the neural tube, a position occupied by the floor plate in vertebrates. This is the first evidence that amphioxus has a floor plate which is specified by a mechanism conserved with vertebrates. Taken together these data support two conclusions: Firstly, that the role of the dorsal lip/Hensen's node, notochord, and floor plate as organisers of the vertebrate body plan evolved prior to the separation of the vertebrate and cephalochordate lineages, at least 520 million years ago. Secondly, that the role of HNF-3 genes in these structures predates the origin of the multiple HNF-3 genes found in vertebrates
Aminopeptidase-like Protease Released from Oocytes Affects Oocyte Surfaces and Suppresses the Acrosome Reaction in Establishment of Polyspermy Block in Oocytes of the MusselMytilus edulis

AbstractSuppression of the acrosome reaction of sperm on fertilized oocytes inhibits sperm–oocyte binding and is considered one of the three mechanisms responsible for polyspermy block in oocytes of the musselMytilus edulis(Togoet al.,1995). When unfertilized oocytes were inseminated in the presence of aminopeptidase inhibitors and the fertilized oocytes were inseminated again, neither the acrosome reaction nor sperm binding to fertilized oocytes were suppressed, suggesting that aminopeptidase-like protease participates in suppression of the acrosome reaction. The supernatant solution obtained after centrifuging a suspension of fertilized oocytes hydrolyzed aminopeptidase substrates, and these activities were inhibited strongly or effectively by aminopeptidase inhibitors. When unfertilized oocytes were incubated with this supernatant solution and inseminated, both the number of sperm bound and the acrosome reaction rate decreased, and these effects were reversed by conducting this treatment in the presence of aminopeptidase inhibitors. These results suggest that aminopeptidase-like protease released from the oocyte at fertilization affects the oocyte surface to suppress the acrosome reaction and consequently inhibits sperm–oocyte binding
Ectopic Expression of MEF2 in the Epidermis Induces Epidermal Expression of Muscle Genes and Abnormal Muscle Development inDrosophila

AbstractMyocyte-specific enhancer-binding factor 2 (MEF2) is a myogenic regulatory factor in vertebrates andDrosophila.Whereas the role of MEF2 in regulating vertebrate myogenesis and muscle genes has been extensively studied, little is known of the role of MEF2 in regulatingDrosophilamyogenesis. We have shown in a recent analysis of the regulation of theDrosophila Tropomyosin I(TmI) gene in transgenic flies that MEF2 is a positive regulator ofTmIexpression in the somatic body-wall muscles of embryos, larvae, and adults. To understand further the role of MEF2 in myogenesis and test the role of MEF2 in regulatingTmIexpression, we have used the yeast GAL4/UAS system to generate embryos in which MEF2 is ectopically expressed in tissues where it is not normally expressed or embryos in which MEF2 is overexpressed in the mesoderm and muscles. We observe that ectopic expression of MEF2 in the epidermis and the ventral midline cells in embryos activates the expression ofTmIand other muscle genes in these tissues and that this activation is stage-dependent suggesting a requirement for additional factors. Furthermore, ectopic expression of MEF2 in the epidermis results in a decrease in the expression of signaling molecules in the epidermis and a failure of the embryo to properly form body-wall muscles. These results indicate that MEF2 can function out of context in the epidermis to induce the expression of muscle genes and interfere with a requirement for the epidermis in muscle development. We also find that the level of MEF2 in the mesoderm and/or muscles in embryos is critical to body-wall muscle formation; however, no effect is observed on the development of the visceral muscle or dorsal vessel
GATA-5: A Transcriptional Activator Expressed in a Novel Temporally and Spatially-Restricted Pattern during Embryonic Development

AbstractMembers of the GATA family of zinc finger transcription factors regulate critical steps of cellular differentiation during vertebrate development. In the studies described in this report, we have isolated and functionally characterized the murine GATA-5 cDNA and protein and defined the temporal and spatial pattern of GATA-5 gene expression during mammalian development. The amino terminus of the mouse GATA-5 protein shares high level amino acid sequence identity with the murine GATA-4 and -6 proteins, but not with other members of the GATA family. GATA-5 binds to the functionally important CEF-1 nuclear protein binding site in the cardiac-specific slow/cardiac troponin C (cTnC) transcriptional enhancer and overexpression of GATA-5 transactivates the cTnC enhancer in noncardiac muscle cell lines. During embryonic and postnatal development, the pattern of GATA-5 gene expression differs significantly from that of other GATA family members. In the primitive streak embryo, GATA-5 mRNA is detectable in the precardiac mesoderm. Within the embryonic heart, the GATA-5 gene is expressed within the atrial and ventricular chambers (ED 9.5), becomes restricted to the atrial endocardium (ED 12.5), and is subsequently not expressed in the heart during late fetal and postnatal development. Moreover, coincident with the earliest steps in lung development, only the GATA-5 gene is expressed within the pulmonary mesenchyme. Finally, the GATA-5 gene is expressed in tissue-restricted subsets of smooth muscle cells (SMCs), including bronchial SMCs and SMCs in the bladder wall. These data are consistent with a model in which GATA-5 performs a unique temporally and spatially restricted function in the embryonic heart and lung. Moreover, these data suggest that GATA-5 may play an important role in the transcriptional program(s) that underlies smooth muscle cell diversity
Developmental Regulation of Zbu1, a DNA-Binding Member of the SWI2/SNF2 Family

AbstractThe SWI2/SNF2 gene family has been implicated in a wide variety of processes, involving regulation of DNA structure and chromatin configuration, mitotic chromosome segregation, and DNA repair. Here we report the characterization of the Zbu1 gene, also known as HIP116, located on human chromosome band 3q25, which encodes a DNA-binding member of this superfamily. Zbu1 was isolated in this study by its affinity for a site in the myosin light chain 1/3 enhancer. The protein has single-stranded DNA-dependent ATPase activity, includes seven helicase motifs, and a RING finger motif that is shared exclusively by the RAD5, spRAD8, and RAD16 family members. During mouse embryogenesis, Zbu1 transcripts are detected relatively late in fetal development and increase in neonatal stages, whereas the protein accumulates asynchronously in heart, skeletal muscle, and brain. In adult human tissues, alternatively spliced Zbu1 transcripts are ubiquitous with highest expression in these tissues. Gene expression is also dramatically induced in human tumor lines and in Li-Fraumeni fibroblast cultures, suggesting that it is aberrantly regulated in malignant cells. The developmental profile of Zbu1 gene expression and the association of the protein with a tissue-specific transcriptional regulatory element distinguish it from other members of the SWI2/SNF2 family and suggest novel roles for the Zbu1 gene product
SOX9 Binds DNA, Activates Transcription, and Coexpresses with Type II Collagen during Chondrogenesis in the Mouse

AbstractTwo lines of evidence suggest that theSry-related geneSox9is important for chondrogenesis in mammalian embryos.Sox9mRNA is expressed in chondrogenic condensations in mice, and mutations in humanSOX9are known to cause skeletal dysplasia. We show here that mouse SOX9 protein is able to bind to a SOX/SRY consensus motif in DNA and contains a modular transcriptional activation domain, consistent with a role for SOX9 as a transcription factor acting on genes involved in cartilage development. One such gene isCol2a1,which encodes type II collagen, the major structural component of cartilage. We have compared, in detail, the expression ofSox9andCol2a1during mouse development. In chondrogenic tissues the expression profiles of the two genes were remarkably similar. Coexpression was detected in some nonchondrogenic tissues such as the notochord, otic vesicle, and neural tube, but others such as heart and lung differed in their expression of the two genes. Immunohistochemistry using an antibody specific for SOX9 revealed that expression of SOX9 protein mirrored the distribution ofSox9mRNA. Our results suggest that SOX9 protein is involved in the regulation ofCol2a1during chondrogenesis, but that this regulation is likely to depend on additional cofactors
tbx6,aBrachyury-Related Gene Expressed by Ventral Mesendodermal Precursors in the Zebrafish Embryo

AbstractClassical embryology experiments have indicated the existence of dorsal-type and ventral-type mesoderms that arise as a consequence of mesoderm induction during vertebrate development. Here we report that the zebrafishtbx6gene, a member of theBrachyury-related T-box family of genes, is exclusively expressed by ventral mesendoderm. Three observations link the expression oftbx6to ventral mesoderm specification. First, the gene is initially expressed at the onset of gastrulation within a ventrolateral subpopulation of cells that express the pan-mesodermal gene,no tail(Brachyury). Second, the mesoderm-inducing factors activin and bFGF activatetbx6expression in animal caps. Third, dorsalization of the mesendodermal precursor population following exposure of embryos to lithium ions causes down-regulation oftbx6transcription.tbx6is expressed transiently in the involuting derivatives of the ventral mesendoderm, which give rise to nonaxial mesodermal tissues; its expression is extinguished as tissue differentiation progresses. Transcription oftbx6commences about an hour after initiation of expression of the pan-mesendodermal geneno tailand the organizer genegoosecoid.The dependence oftbx6expression onno tailactivity was examined inno tailmutant embryos. The activation oftbx6transcription in ventral mesoderm does not depend onno tailgene activity. However,no tailappears to contribute to the maintenance of normal levels oftbx6transcription and may be required fortbx6transcription in the developing tail
Stimulation of Tentacle and Bud Formation by the Neuropeptide Head Activator inHydra magnipapillata

AbstractStimulation of epithelial cell cycling by the neuropeptide head activator was analyzed inHydra magnipapillataand compared with the action of head activator on bud formation and tentacle formation during head regeneration. The results obtained indicate that head activator treatment stimulates epithelial cell division and induces the formation of more tentacle-specific epithelial cells. The number of additional epithelial cells which undergo mitosis during head activator treatment accounts for the increased number of epithelial cells present in the regenerated tentacles. Therefore, the head activator stimulation of tentacle formation can be explained by the mitogenic action of head activator on tentacle cell precursors. To analyze stimulation of bud formation by head activator, polyps of different developmental age were tested under conditions of long-term treatment, and effects on bud formation were compared with effects on epithelial cell proliferation. Head activator treatment strongly stimulated bud formation, but had no detectable effect on epithelial cell numbers. Bud formation occurs at smaller polyp size as a result of head activator treatment, indicating that head activator significantly interferes with the patterning system in hydra
Cyclin-Dependent Kinase 5 Is Associated with Apoptotic Cell Death during Development and Tissue Remodeling

AbstractIn a series of studies to more precisely localize the cellular sites of expression of the cyclin-dependent kinase (Cdk) family members in reproductive organs, we observed a striking expression of Cdk5 in atretic follicles in the ovary, particularly in granulosa cells that appeared to be dying. We determined that these granulosa cells were undergoing apoptotic cell death using thein situDNA fragmentation assay. To extend the generality of the association of Cdk5 with apoptotic cells, we examined its expression as it correlated with the detection of apoptosis in a number of developmental paradigms, including regions of the embryonic nervous system, the developing eye, and the developing limb. Finally, the association of apoptosis and Cdk5 expression and associated kinase activity was examined in the limb and in an induced cell death system, that of androgen withdrawal-induced regression of the prostate gland in male mice. These observations provide new insight into the possible function of this novel Cdk during both differentiation and apoptotic cell death
Vessel Patterning in the Embryo of the Zebrafish: Guidance by Notochord

AbstractWe have cloned the zebrafish homolog of the receptor tyrosine kinaseflk-1to provide us with a tool to study normal vascular pattern formation in the developing zebrafish embryo and to compare it to mutants in which vascular pattern is perturbed. We find that during normal development the first angioblasts arise laterally in the mesoderm and then migrate medially to form the primordia of the large axial vessels, the dorsal aorta (axial artery) and the axial vein. Lumen formation occurs shortly before onset of circulation at 24 hr postfertilization. We examined the specification of vascular progenitors in the mutantcloche,which fails to form both vessels and blood.clochelacks allflk-expressing cells and therefore appears to lack angioblasts. The axial vessels of the trunk form in close proximity to notochord and endoderm, which may provide cues for their formation. The dorsal aorta is normally just ventral to the notochord; the axial vein is just below the dorsal aorta and above the endoderm.floating head (flh)andno tail (ntl)mutants both have defects in the formation of notochord. Both are cell-autonomous lesions,flhabolishing notochord andntlpreventing its differentiation. In both mutants the dorsal aorta fails to form, while formation of the axial vein is less affected. Mosaic analysis of mutant embryos shows that transplanted wild-type cells can become notochord in mutantflhembryos. In these mosaic embryosflhcells expressingflkassemble at the midline, beneath the wild-type notochord, and form an aortic primordium. This suggests that signals from the notochord may guide angioblasts in the fashioning of the dorsal aorta. The notochord seems to be less important for the formation of the vein
Reciprocal Expression of the Eph Receptor Cek5 and Its Ligand(s) in the Early Retina

AbstractRecent evidence suggests that Eph receptor tyrosine kinases and their ligands provide positional information in the developing visual system. We previously found that the Eph receptor Cek5 is more highly expressed in the ventral than dorsal chicken embryonic retina. We now report the identification of a chicken ligand for Cek5 (cCek5-L) that is 75% identical to the ligand LERK2.In situhybridization experiments do not reveal a dorsoventral gradient of cCek5-L transcripts in the optic tectum at Embryonic Day 8, suggesting that this ligand is not involved in guiding Cek5-expressing axons in the tectum. Surprisingly, it is in the retina that high levels of cCek5-L mRNA are present. In the early retina, cCek5-L is more highly expressed in the dorsal than the ventral aspect. Similarly, a Cek5 Ig chimera labels dorsal but not ventral retina, indicating that even if several Cek5 ligands are present, their overall distribution is complementary to that of Cek5. Hence, Cek5 and cCek5-L may both contribute to define anatomical compartments within the early retina. In contrast, in the 11-day embryonic retina the distributions of Cek5 and its ligand(s) show considerable overlap, suggesting changing functions as development progresses. In dissociated cultures of dorsal or ventral retinal cells seeded on plates coated with either receptor or ligand Ig chimeras, the interaction between Cek5 and its ligand(s) or cCek5-L and its receptor(s) is sufficient to mediate cell adhesion and allows neurite outgrowth
Localization of MAP Kinase Activity in EarlyXenopusEmbryos: Implications for Endogenous FGF Signaling

AbstractWe have used a sensitive assay for MAP kinase activity to investigate the role of endogenous fibroblast growth factor (FGF)-activated MAP kinase in earlyXenopusembryonic patterning. MAP kinase activity is low during cleavage stages and increases significantly during gastrulation. The temporal profile of this activity correlates well with the expression pattern ofXenopuseFGF. Spatially, MAP kinase activity is lowest in animal pole tissue and higher in vegetal pole cells and the marginal zone. Endogenous MAP kinase activity is FGF receptor-dependent, demonstrating that FGF signaling is active in all three germ layers of the early embryo. This activity is necessary for normal expression of Mix.1, a meso-endodermal marker, in the endoderm as well as in the mesoderm, indicating that MAP kinase plays a functional role in patterning of both of these germ layers. Spatial and temporal changes in MAP kinase activation during gastrulation also suggest a role for FGF signaling in this process. In addition, we find that embryonic wounding during dissection results in significant stimulation of this pathway, providing a possible explanation for earlier observations of effects of surgical manipulation on cell fate in early embryos
Regeneration ofSarcophagaImaginal Discsin Vitro:Implication of 20-Hydroxyecdysone

AbstractWhen the 3/4 sectors of leg imaginal discs ofSarcophagawere culturedin vitroin the presence of 2.5 × 10−8M20-hydroxyecdysone, wound healing and restoration of their morphology occurred. This concentration of ecdysone was critical for wound healing and was 40 times lower than that necessary for inducing differentiation of imaginal discsin vitro.Lost positional values revealed by expression of thewinglessgene were found to show partial recovery under these conditions. These results suggest that a low titer of ecdysone is essential for the regeneration of imaginal discs
Role of cAMP-Dependent Protein Kinase in Controlling Aggregation and Postaggregative Development inDictyostelium

AbstractWe have examined the role of cAMP-dependent protein kinase (PKA) in controlling aggregation and postaggregative development inDictyostelium.We previously showed that cells in which the gene encoding the PKA catalytic subunit has been disrupted (pkacat−cells) are unable to aggregate [S. K.O. Mann and R.A. Firtel (1991). A developmentally regulated, putative serine/threonine protein kinase is essential for development inDictyostelium. Mech. Dev.35, 89–102]. We show thatpkacat−cells are unable to activate adenylyl cyclase in response to cAMP stimulation due to the inability to express the aggregation-stage, G-protein-stimulated adenylyl cyclase (ACA). Constitutive expression of ACA from an actin promoter results in a high level of Mn2+-stimulated adenylyl cyclase activity and restores chemoattractant- and GTPγS-stimulated adenylyl cyclase activity but not the ability to aggregate. Similarly, expression of the constitutively active, non-G protein-coupled adenylyl cyclase ACG inpkacat−cells also does not restore the ability to aggregate, although ACG can complement cells in which theACAgene has been disrupted. These results indicate thatpkacat−cells lack multiple, essential aggregation-stage functions. As the mound forms, high, continuous levels of extracellular cAMP functioning through the cAMP serpentine receptors activate a transcriptional cascade that leads to cell-type differentiation and morphogenesis. The first step is the induction and activation of the transcription factor GBF and downstream postaggregative genes, followed by the induction of prestalk- and prespore-specific genes. We show thatpkacat−cells induce postaggregative gene expression in response to exogenous cAMP, but the level of induction of some of these genes, includingGBF,is reduced.SP60(a prespore-specific gene) is not induced andecmA(a prestalk-specific gene) is induced to very low levels. Expressing GBF constitutively inpkacat−cells restoresecmAexpression to a moderate level, butSP60is not detectably induced. Overexpression of PKAcat from the Actin 15 (Act15), ecmAprestalk, and thePKAcatpromoters inpkacat−cells results in significant aberrant spatial patterning of prestalk and prespore cells, as determined bylacZ reporter studies. Our studies identify new, essential regulatory roles for PKA in mediating multicellular development