pinecone/core-2020-05-10-deduplication huggingface dataset:
Digit Induction by Hensen's Node and Notochord Involves the Expression ofshhbut NotRAR-β2

AbstractIt is well established that Hensen's nodes can induce the formation of supernumerary digits after grafting into the anterior margin of the developing limb bud. The recent finding that distinct mesodermal cell populations are segregated within the node has made it possible to isolate different prospective cell types in an attempt to correlate digit-inducing ability with cell fate. We find that the prospective notochord cells contained within Hensen's node are able to induce supernumerary digits, whereas presumptive somite cells cannot. This early difference in inducing ability persists into later stages of development: epithelial somites are unable to induce while notochord from all lengths of the neuraxis continues to induce. Using probes to retinoic acid receptor-β2 and sonic hedgehog (shh) we find no evidence to support the idea that inducing tissues generate extra digits by releasing retinoic acid into adjacent limb tissue but find that the inducing ability of a tissue correlates with its expression ofshh
Differential Distribution of cAMP Receptors cAR2 and cAR3 duringDictyosteliumDevelopment

AbstractSignal transduction via a family of cAMP receptor subtypes (cARs) is critical for proper development in the cellular slime moldDictyostelium.Genes encoding four related subtypes have been cloned and their expression, based on RNA accumulation, has been previously reported. Here we report the differential spatial and temporal distribution of cAR2 and cAR3 proteins, based on indirect double immunofluorescence. Cells were transformed with acarB::lacZconstruct, and an antibody against β-galactosidase was used to visualize cAR2 expression. Simultaneously, a cAR3-specific antibody was used to identify cAR3-expressing cells. Results indicate that by the time of tip formation (12–14 hr) both receptors are expressed and distribute in a virtually nonoverlapping pattern, with cAR2 being expressed on anterior, prestalk cells and cAR3 present in the rest of the organism. Differential distribution of these two receptor subtypes may result in distinct cAMP signaling mechanisms in the two major regions of the organism
Resynthesizing Evolutionary and Developmental Biology

AbstractA new and more robust evolutionary synthesis is emerging that attempts to explain macroevolution as well as microevolutionary events. This new synthesis emphasizes three morphological areas of biology that had been marginalized by the Modern Synthesis of genetics and evolution: embryology, macroevolution, and homology. The foundations for this new synthesis have been provided by new findings from developmental genetics and from the reinterpretation of the fossil record. In this nascent synthesis, macroevolutionary questions are not seen as being soluble by population genetics, and the developmental actions of genes involved with growth and cell specification are seen as being critical for the formation of higher taxa. In addition to discovering the remarkable homologies of homeobox genes and their domains of expression, developmental genetics has recently proposed homologies of process that supplement the older homologies of structure. Homologous developmental pathways, such those involving thewntgenes, are seen in numerous embryonic processes, and they are seen occurring in discrete regions, the morphogenetic fields. These fields (which exemplify the modular nature of developing embryos) are proposed to mediate between genotype and phenotype. Just as the cell (and not its genome) functions as the unit of organic structure and function, so the morphogenetic field (and not the genes or the cells) is seen as a major unit of ontogeny whose changes bring about changes in evolution
Developmental Evolution of Metazoan Bodyplans: The Fossil Evidence

AbstractEvidence from the fossil record, developmental biology and metazoan phylogeny demonstrates that the rapid origination of major metazoan bodyplans during the late Neoproterozoic and earliest Cambrian was intimately associated with a series of innovations in developmental control mechanisms that included theHoxgene cluster. The interval between about 565 Ma (million years ago) and 530 Ma evidently includes the protostome-deuterostome branching, diversification of independent higher metazoan clades, diversification of important developmental control systems, and formation of higher metazoan bodyplans. Comparative paleontological and developmental studies will allow further tests of alternative models for the sequence of these events, illuminating the association between developmental and bodyplan evolution
HoxGenes and Chordate Evolution

AbstractHoxgenes are implicated in the control of axial patterning during embryonic development of many, perhaps all, animals. Here we review recent data onHoxgene diversity, genomic organization, and embryonic expression in chordates (including tunicates, amphioxus, hagfish, lampreys, teleosts) plus their putative sister group, the hemichordates. We consider the potential of comparativeHoxgene data to resolve some outstanding controversies in chordate phylogeny. The use ofHoxgene expression patterns to identify homologies between body plans both within the vertebrates and between the chordate subphyla is also discussed. Homology between the vertebrate hindbrain and an extensive region of amphioxus neural tube is suggested by comparison ofHox-3homologues and strengthened by new data on amphioxusHox-1gene expression reported here. Finally, we give two examples of howHoxgenes are giving glimpses into chordate developmental evolution. The first relates changes inHoxgene expression to transposition of vertebral identities; the second describes a correlation between vertebrate origins andHoxgene cluster duplication. We suggest that the simultaneous duplication of many classes of genes, often interacting in gene networks, allowed the elaboration of new developmental control mechanisms at vertebrate origins
Evolution of Nematode Vulval Fate Patterning

AbstractNematodes provide a useful experimental system with which to investigate the evolution of development at the cellular, genetic, and molecular levels. Building on an understanding of vulval development inCaenorhabditis elegans,analysis of vulval development has been extended to a number of other species in three families of the Nematode phylum. Changes have occurred in most aspects of vulval development: alteration in the number of cells competent to participate in vulval development by changes in apoptosis; changes in the relative contributions of position-dependent predisposition toward particular fates (prepattern), inductive signaling and lateral signaling; and in the specific lineages generated by vulval precursor cells. Genetic analysis of one species in which only three vulval precursor cells are present identified a mutation that increases the number of vulva precursor cells toward that found inC. elegans
In VivoRegulation of the Early Embryonic Cell Cycle inXenopus

AbstractWe report here the first extensivein vivostudy of cell cycle regulation in theXenopusembryo. Cyclin A1, B1, B2, and E1 levels, Cdc2 and Cdk2 kinase activity, and Cdc25C phosphorylation states were monitored during earlyXenopusembryonic cell cycles. Cyclin B1 and B2 protein levels were high in the unfertilized egg, declined upon fertilization, and reaccumulated to the same level during the first cell cycle, a pattern repeated during each of the following 11 divisions. Cyclin A1 showed a similar pattern, except that its level was lower in the egg than in the cell cycles after fertilization. Cyclin B1/Cdc2 kinase activity oscillated, peaking before each cleavage, and Cdc25C alternated between a highly phosphorylated and a less phosphorylated form that correlated with high and low cyclin B1/Cdc2 kinase activity, respectively. Unlike the mitotic cyclins, the level of cyclin E1 did not oscillate during embryogenesis, although its associated Cdk2 kinase activity cycled twice for each oscillation of cyclin B1/Cdc2 activity, consistent with a role for cyclin E1 in both S-phase and mitosis. Although the length of the first embryonic cycle is regulated by both the level of cyclin B and the phosphorylation state of Cdc2, cyclin accumulation alone was rate-limiting for later cycles, since overexpression of a mitotic cyclin after the first cycle caused cell cycle acceleration. The activity of Cdc2 closely paralleled the accumulation of cyclin B2, but cell cycle acceleration caused by cyclin B overexpression was not associated with elevation of Cdc2 activity to higher than metaphase levels. Tyrosine phosphorylation of Cdc2, absent during cycles 2–12, reappeared at the midblastula transition coincident with the disappearance of cyclin E1. Cyclin A1 disappeared later, at the beginning of gastrulation. Our results suggest that the timing of the cell cycle in theXenopusembryo evolves from regulation by accumulation of mitotic cyclins to mechanisms involving periodic G1cyclin expression and inhibitory tyrosine phosphorylation of Cdc2
Positional Information along the Dorsal–Ventral Axis of theDrosophilaEye: Graded Expression of thefour-jointedGene

AbstractSeveral observations suggest that developing ommatidia in theDrosophilaeye have distinct dorsal–ventral (d-v) positional identities, despite their morphological uniformity. To identify molecular differences along the d-v axis of the eye, we carried out a systematic screen for P-element insertions that show nonuniform reporter gene expression along this axis. We identified P-element insertions in whichlacZexpression is activated in dorsal, ventral, or equatorial regions of the disc. These patterns of transcriptional enhancer activity are established early in disc development and are maintained in a size invariant manner during disc growth. Several insertions with an equatorial-to-polar gradient oflacZexpression disrupt thefour-jointed(fj) gene which is required for proper leg, wing, and eye development. ThefjcDNA sequence includes a presumptive internal signal sequence, indicating thatfjencodes a cell surface or secreted protein. Analysis of thefjphenotype and expression pattern in the leg suggests thatfjis required for cell–cell signaling during disc development
Defective Chorioallantoic Fusion in Mid-gestation Lethality of Parthenogenone ⇔ Tetraploid Chimeras

AbstractPrevious studies of parthenogenetic embryos revealed severe perturbations of both embryonic and extraembryonic tissue lineages during postimplantation development. The majority of pure parthenogenetic concepti have no recognizable axis and exhibit preferential terminal differentiation of their trophectoderm and primitive endoderm. To further define the role of the extraembryonic lineages in parthenogenetic development, we provided them with zygote-derived extraembryonic tissues by aggregating them with fertilized tetraploid embryos. On Day 12 of combinedin vitroandin vivodevelopment, most of the embryos proper in these chimeras were entirely derived parthenogenetically, whereas their trophectoderm and primitive endoderm tissues were derived from the tetraploid component. NoIgf2expression was detected in the parthenogenetic embryo proper, indicating that imprinting was manifested in such chimeras. Typical development of the parthenogenetic embryo proper was markedly improved in comparison with pure parthenogenetic concepti, with such chimeras attaining an average of 23 somites (range, 10 to 35). However, most of the chimeras died abruptly at Day 13, and all were being resorbed at Day 14 of development. The gross normality of axial structures and organ development suggests that a major cause of failure of these chimeric parthenogenones to survive beyond mid-gestation was due to defective chorioallantoic fusion. Our results indicate that the severe perturbation of axial development seen in most pure parthenogenetic concepti is a secondary consequence of the effects of parthenogenesis on the trophectoderm and primitive endoderm lineages. Moreover, the mid-gestation death of parthenogenetic embryos proper despite the presence of zygote-derived tetraploid tissues implicates extraembryonic mesoderm in manifesting the effects of genomic imprinting
20-Hydroxyecdysone, but Not Juvenile Hormone, Regulation ofyolk proteinGene Expression Can Be Mapped tocis-Acting DNA Sequences

AbstractThe threeyolk proteingenes (yps) ofDrosophila melanogasterare expressed in the ovary and fat body of the adult female. Their levels of expression in the fat body depend upon both juvenile hormone (JH) and 20-hydroxyecdysone (20E). Using transformed lines of flies with various flanking sequences from theypgenes andlacZ, Adh,or nativeypgenes as reporters, the regulation of the threeypgenes by 20E and the JH analogue ZR515 (methoprene) was investigated. For 20E, induction of reporter gene expression in males was assayed and, for JH, upregulation of the genes in nutritionally deprived females, which express yolk proteins (YPs) at very low levels, was followed. We were able to map 20E inducible sites upstream ofyp3and sites located 3′ and within the coding sequence or introns ofyp3which can interact to respond to 20E. There are also sites in the intergenic spacer betweenyp1andyp2.Evidence for repressors was also found upstream of theypgenes, suggesting downstream 20E inducible elements may be importantin vivo.There appears to be a difference in the response to 20E in the fat body of the thorax and abdomen between different constructs in males. It is not clear whether those sequences which respond to 20E are genuine ecdysone response elements (i.e., binding sites for the ecdysone receptor) or if the effect is indirect. Methoprene upregulation of YPs, however, was only ever observed using nativeypgenes as reporters, suggesting that this hormone may act on intron sequences orypcoding sequences, or perhaps by influencing stability of theypmRNA
Strong Induction of Activin Expression after Injury Suggests an Important Role of Activin in Wound Repair

AbstractActivins are members of the transforming growth factor β (TGFβ) superfamily, which comprises a growing group of dimeric proteins. TGFβ and several other members of this superfamily are known to play an important role in wound healing. However, expression of activin during wound healing has not been demonstrated so far. In this study we have analyzed the expression pattern of activin and activin receptors in normal and wounded skin. We found a large induction of activin A and a minor induction of activin B mRNA expression 1 day after skin injury and high expression levels of activin A and B were found within the first 7 days after wounding. At 13 days after injury, expression of activin A mRNA had returned to the basal level, whereas high levels of activin B persisted.In situhybridization studies revealed expression of activin A in the granulation tissue below the wound and activin B in the hyperproliferative epithelium at the wound edge and in the migrating epithelial tongue. All known types of activin receptors as well as the activin binding protein follistatin were expressed in normal and wounded skin. However, no significant induction of receptor gene expression was seen during the repair process. The distribution of activins and activin receptors in the wound suggests multiple autocrine and paracrine activities of the ligands during wound healing. Our data provide evidence for a novel function of activin and indicate that —besides TGFβs themselves—other members of this superfamily might also play an important role in tissue repair
pH Regulation in Mouse Sperm: Identification of Na+-, Cl−-, and[formula]Dependent and Arylaminobenzoate-Dependent Regulatory Mechanisms and Characterization of Their Roles in Sperm Capacitation

AbstractIntracellular pH (pHi) regulates several aspects of mammalian sperm function, although the transport mechanisms that control pHiin these cells are not understood. The pHiof mouse cauda epididymal sperm was determined from the fluorescence excitation ratio of 2,7-bis(carboxyethyl)-5(6)-carboxyfluorescein and calibrated with nigericin and elevated external [K+]. Two acid efflux mechanisms were identified following imposition of acid loads. One pathway has many anticipated characteristics of the somatic Na+-dependent Cl−–[formula]exchanger, although sperm and somatic mechanisms can be distinguished by their ion selectivity and inhibitor sensitivity. Sperm may have an isoform of this exchange pathway with novel functional characteristics. The second acid-export pathway does not require extracellular anions or cations and is inhibited by arylaminobenzoates (flufenamic acid, diphenylamine-2-carboxylate). Mouse sperm also recover spontaneously from intracellular alkalinization. Recovery rates inN-methyl-D-glucamine+Cl−or in 0.25Msucrose are not significantly different from that in a complex culture medium. Thus, recovery from alkalinization does not utilize specific, ion-dependent transport mechanisms. Other widely distributed acid-efflux mechanisms, such as the Na+–H+antiport pathway and the Na+-independent Cl−–[formula]exchanger are not major regulators of mouse sperm pHi. Sperm capacitation results in pHiincreases (from 6.54 ± 0.08 to 6.73 ± 0.09) that require a functional Na+-, Cl−-, and[formula]-dependent acid-efflux pathway. Inhibition of this regulatory mechanism attenuates alkaline shifts in pHiduring capacitation as well as the ability of sperm to produce a secretory response to zona pellucida agonists. These data suggest that one aspect of mouse sperm capacitation is the selective activation of one major pHiregulator
A Single MEF2 Site Governs Desmin Transcription in Both Heart and Skeletal Muscle during Mouse Embryogenesis

AbstractDesmin, the muscle-specific intermediate filament protein is one of the earliest known myogenic markers both in heart and in somites. We have previously shown that high levels of desmin expression in the skeletal cell line C2C12are due to a distal enhancer, which contains a muscle-specific factor-2 (MEF2) binding site, adjacent to an E box, the binding site of the myogenic Helix-Loop-Helix (mHLH) regulators. We have further shown that MEF2C, a myocyte restricted member of the MEF2 family and all four mHLH factors can bind to their corresponding sites and through a cooperation with a second proximal E box can transactivate the desmin promoter. To study the significance of these regulatory elementsin vivo,we have generated transgenic mice with desmin–lacZ reporters, intact or mutated at the MEF2 and E box of the enhancer. We show that thecis-acting DNA sequences within the 1-kb 5′ flanking region of the mouse desmin gene are sufficient to direct appropriate temporal transcription both in heart and in skeletal muscle during mouse embryogenesis. Mutation at the MEF2 site completely suppressed transcription of the linked lacZ transgene in both developing heart and somites of the embryos. Mutation of the E box only suppressed activation in skeletal muscle precursors (somites and limb buds) but not in cardiac muscle. These data demonstrate that the MEF2 site is indispensable for the desmin enhancer function both in heart and in skeletal muscle. In addition, MEF2 cooperation with the mHLH regulators is absolutely necessary for proper transcriptional activity during embryonic skeletal muscle development
The Role of Interleukin-4 in the Regulation of Mouse Primordial Germ Cell Numbers

AbstractInterleukin-4 (IL-4), a pleiotropic cytokine, stimulates a dose-dependent increase in the number of mouse primordial germ cells in culture. Results from bromodeoxyuridine incorporation assays suggest that IL-4 acts as a survival factor rather than as a mitogen for primordial germ cells in this system. Studies on the embryonic expression patterns of IL-4 and its receptors, using RT–PCR and ELISA, show that IL-4 and its receptors are present at the correct time and place to influence PGC numbersin vivo
Cellular Interactions Mediated by the HomeoticPISTILLATAGene Determine Cell Fate in theArabidopsisFlower

AbstractFlowers develop from the coordinated division and differentiation of cells derived from the shoot apical meristem. By inducing chromosomal deletions in individual shoot apical meristem cells, we have generatedArabidopsisplants that are genetically mosaic for the homeoticPISTILLATAgene. Flowers bearing wild-typePISTILLATAepidermal tissue and mutantpistillatainternal tissues are phenotypically normal. Based on this non-cell-autonomy, we suggest thatPISTILLATAcontrols the production of a substance involved in cell–cell communication between the outer and inner tissue layers of the flower. These mosaic flowers were also used to assess the relative contributions of meristematic cells to the developing floral organs. These observations indicate that meristematic cells have discrete but somewhat variable contributions to theArabidopsisflower. We have used these results to construct a fate map of theArabidopsisfloral primordium
Xenopus laevisEgg Jelly Coats Consist of Small Diffusible Proteins Bound to a Complex System of Structurally Stable Networks Composed of High-Molecular-Weight Glycoconjugates

AbstractThe extracellular matrix surroundingXenopus laeviseggs includes three morphologically distinct jelly layers designated J1, J2, and J3 from the innermost to outermost. Previously, using the quick-freeze, deep-etch, rotary-shadow technique, we found that each layer has a unique fibrillogranular ultrastructure. In this study, we show that the fibrillar network is composed of high-molecular-weight glycoconjugates, while the globular material consists of low-molecular-weight proteins some of which are released into the aqueous medium. Analysis by SDS–PAGE and differential staining of individually dissected jelly layers shows that both J1 and J2 contain three high-molecular-weight, acidic, Alcian blue-staining components (450, 630, and 900 kDa), while J3 contains two high-molecular-weight components that stain with PAS but not with Alcian blue. Each jelly layer also contains low-molecular-weight proteins from 75 to 250 kDa that do not stain with PAS or Alcian blue. Chromatography of whole egg jelly on a Sephacryl 500 column resulted in isolation of the major Alcian blue staining band (630 kDa) which eluted first, and two PAS staining bands which eluted second. Rotary-shadowing demonstrated that these high-molecular-weight glycoconjugates are long and branched, suggesting that they are major constituents of the jelly fiber network. SDS–PAGE analysis shows that these networks are stable for at least 16 hr after eggs are oviposited. In contrast, the low-molecular-weight globular proteins which constitute 30% of the total jelly protein are steadily released into the surrounding medium