pinecone/core-2020-05-10-deduplication huggingface dataset:
Haploinsufficiency of Parathyroid Hormone-Related Peptide (PTHrP) Results in Abnormal Postnatal Bone Development

AbstractAlthough apparently phenotypically normal at birth, mice heterozygous for inactivation of the gene encoding parathyroid hormone-related peptide (PTHrP) develop haplotype insufficiency by 3 months of age. In addition to histologic and morphologic abnormalities similar to those seen in homozygous mutants, heterozygous animals demonstrated alterations in trabecular bone and bone marrow. These included metaphyseal bone spicules which were diminished in volume, irregularly distributed, and less well developed than those seen in age-matched controls as well as bone marrow, which contained an inordinate number of adipocytes. A substantial reduction in PTHrP mRNA was detected in heterozygous tissue, while circulating parathyroid hormone (PTH) and calcium concentrations were normal. Thus, while a physiologic concentration of PTH was capable of maintaining calcium homeostasis, it was incapable of compensating for PTHrP haploinsufficiency in developing bone. In normal animals, both PTHrP and the PTH/PTHrP receptor were expressed predominantly in chondrocytes situated throughout the proliferative zone of the tibial growth plate. In the metaphysis, the PTH/PTHrP receptor was identified on osteoblasts and preosteoblastic cells situated in the bone marrow, while PTHrP was expressed only by osteoblasts. These observations indicate that postnatal bone development involves susceptible pathways that display exquisite sensitivity to critical levels of PTHrP and imply that the skeletal effects of PTH are influenced by locally produced PTHrP. Moreover, identification of both the ligand and its N-terminal receptor in metaphyseal osteoblasts and their progenitors suggests an autocrine/paracrine role for the protein in osteoblast differentiation and/or function. Impairment in this function as a consequence of PTHrP haploinsufficiency may critically influence the course of bone formation, resulting in altered trabecular architecture and perhaps low bone mass and increased bone fragility
Environmental Signals Influence Expression of a Cortical Areal Phenotypein VitroIndependent of Effects on Progenitor Cell Proliferation

AbstractWe have shown previously that,in vitro,cortical progenitor cells isolated from specific locations of the cerebral wall can adopt area-specific fates, assayed by expression of the limbic system-associated membrane protein (LAMP; R. T. Ferri and P. Levitt,Cereb. Cortex3, 187–198, 1993). Progenitors destined to produce LAMP neurons, however, will differentiate to express the limbic molecular phenotype if grown with TGFα and collagen type IV (R. T. Ferri and P. Levitt,Development121, 1151–1160, 1995), while other signals fail to induce LAMP. The present study used BrdU labeling of progenitor cells to examine whether modulation of LAMP expression was paralleled by predictable changes in cell proliferation. The general pattern of proliferation is similar under a variety of culture conditions: approximately half the cells are mitotic, and activity is always highest during the first 24 hrin vitro,with little cell division occurring by the third day. Moreover, the rate of proliferation, in the presence or absence of TGFα, is the same on all substrates tested, with the exception of laminin. The TGFα/collagen type IV signaling system that induces LAMP expression by the precursors has no modulating effect on their proliferative kinetics. Nonetheless, only progenitors that are mitotically active respond to LAMP-inducing signals; only 60% of the neurons, representing those that have divided at least once in culture, can be induced to express LAMP. The data suggest that while specific signals affect choice of area phenotype during the cell cycle, they do so in the absence of major changes in proliferative behavior
The Activity of D-raf in Torso Signal Transduction Is Altered by Serine Substitution, N-Terminal Deletion, and Membrane Targeting

AbstractTheRaffamily of serine/threonine kinases are essential components in many receptor tyrosine kinase-mediated signal transduction pathways. Here, we analyze the function of D-raf in the Torso (Tor) pathway required to specify cellular fates at the embryonic poles. Using mutant embryos lacking endogenous D-raf protein, we show that D-raf's serine/threonine kinase activity is essential for its role in Tor signal transduction and that human Raf-1 will substitute for D-raf in this pathway. After Tor activation, D-raf becomes hyperphosphorylated. We identified two putative serine phosphorylation sites (S388 and S743) in SF9 cells and demonstrate that S743 or its phosphorylation is essential for D-raf function in embryos. Alanine substitution at S388, N-terminal truncation, or targeted membrane association permits transmission of the Torso signal by D-raf, but these D-raf molecules differ in their rescuing potential and relative biological activity. Membrane-targeted D-raftor4021showed the highest level of activity, followed by alanine-substituted D-rafS388Aand N-terminal-truncated D-rafΔ445. Since the activity profiles for these altered forms of D-raf are distinct, these findings indicate that each structural modification differentially affects the regulation and/or propagation of the Tor signal by these mutant D-raf proteins
Identification and Characterization of ahunchbackOrthologue,Lzf2,and Its Expression during Leech Embryogenesis

AbstractLzf1andLzf2are leech zinc finger (Lzf) genes that are shown to be orthologues to theDrosophilagap genehunchback(hb). Neitherin situhybridization nor RT–PCR detectedLzf1transcripts in leech embryos or adults.Lzf2expression was examined in leech embryos at various stages byin situhybridization.Lzf2is expressed continually throughout the early embryonic cleavage divisions, including the period during which the embryo forms stem cells that will give rise to the segmented tissues of the adult. At the time of segmental pattern formation,Lzf2RNA is expressed uniformly along the length of the segmented trunk in both the ectodermal and mesodermal tissues. This is in contrast to the anteriorly restricted gradient ofhbRNA shown to be critical to the normal anteroposterior (AP) patterning of the insect embryo. Thus, this leech orthologue ofhbdoes not appear to play a comparable role in the patterning of the AP axis. In addition,Lzf2is expressed during organogenesis in segmentally restricted patterns in the central nervous system, the gut, and epidermally derived structures.Lzf2is the firsthborthologue to be characterized in detail outside of insects and its expression pattern suggests thathbmay have acquired a gap gene function in arthropods or insects after their phyletic separation from the annelids
Cell–Cell Adhesion Prevents Mutant Cells Lacking Myosin II from Penetrating Aggregation Streams ofDictyostelium

AbstractWhen a small number of fluorescently labeled myosin II mutant cells (mhcA−) are mixed with wild-type cells and development of the chimeras is observed by confocal microscopy, the mutant cells are localized to the edges of aggregation streams and mounds. Moreover, the mutant cells stick to wild-type cells and become distorted (Shelden and Knecht, 1995). Two independent adhesion mechanisms, Contact Sites A and Contact Sites B, function during the aggregation stage and either one or both might be responsible for excluding the myosin II null cells. We have mixedmhcA−cells with cells in which the appearance of Contact Sites B is delayed (strain TL72) as well as cells which lack Contact Sites A (strain GT10) and double mutants in which both adhesion mechanisms are affected (strain TL73). In all chimeras, themhcA−cells were distorted by interactions with the adhesion mutant cells, indicating that it does not require significant adhesive interaction to distort the flaccid cortex ofmhcA−cells.mhcA−cells were excluded from streams composed of cells lacking either Contact Sites A or Contact Sites B but mixed randomly with cells lacking both adhesion systems. By 10 hr of development, cells of strain TL73 acquire Contact Sites B adhesion. If cells of this strain were mixed with labeledmhcA−cells, allowed to develop for 9 hr, and then dissociated before replating, the myosin II null cells were seen to be distorted and excluded from the reaggregates. Thus the exclusion ofmhcA−cells from streams can be accomplished by either Contact Sites A or B. When chimeras of labeled TL73 and wild-type cells were made, the TL73 cells were found to be randomly mixed into aggregation streams. This result indicates that adhesive sorting does not function during aggregation and so cannot account for the exclusion ofmhcA−cells from streams. We hypothesize that the flaccid cortex ofmhcA−cells cannot generate sufficient protrusive force to break the contacts between adhered cells in aggregation streams but can enter streams where the cells are weakly adherent
Arrested Lung Morphogenesis in Transgenic Mice Bearing an SP-C–TGF-β1 Chimeric Gene

AbstractTransforming growth factor-β1 (TGF-β1) influences the morphogenesis of many organs, regulating cell growth, differentiation, gene expression, extracellular matrix deposition, and angiogenesis. In order to assess the effects of TGF-β1 on lung developmentin vivo,transgenic mice were generated bearing a chimeric gene composed of human surfactant protein C (SP-C) gene promoter and the porcine TGF-β1 cDNA mutated to ensure constitutive activation of the TGF-β1 peptide. Because of the perinatal loss related to the SP-C–TGF-β1 transgene, embryos bearing the transgene were obtained on Days 16 and 18.5 of gestation. TGF-β1 was selectively expressed in respiratory epithelial cells of the transgenic embryos. Body weight, length, and lung size were not altered in the transgenic embryos; however, lung morphogenesis of Day 18.5 transgenic mice was arrested in a late pseudoglandular stage of development, while that of their nontransgenic littermates was typical of the saccular stage. Lungs of transgenic mice on Day 16 contained fewer acinar buds than those of nontransgenic littermates. At both ages, epithelial cell differentiation, assessed by the expression of Clara cell secretory protein22Abbreviations used: CCSP, Clara cell secretory protein; ECM, extracellular matrix; EGF, epidermal growth factor; PCNA, proliferating cell nuclear antigen; SP-A, surfactant Protein-A; SP-C, surfactant Protein-C; TGF-β1, transforming growth factor-β1; WAP, whey–acidic protein.and pro-SP-C, was inhibited. While collagen III deposition was not affected by the transgene, collagen I expression was persistent in terminal airways of fd 18.5 transgenic lungs. The distribution of α-smooth muscle actin was markedly altered, being detected in the mesenchyme surrounding the distal leading edges of epithelial tubules in the SP-C–TGF-β1 transgenic mice. Expression of TGF-β1 in the developing respiratory epithelium of transgenic mice arrested lung sacculation and epithelial cell differentiationin vivo,supporting the role of TGF-β family members in lung morphogenesis and differentiation
Citral, an Inhibitor of Retinoic Acid Synthesis, Modifies Chick Limb Development

AbstractExogenously applied retinoic acid (RA) is known to affect cartilage pattern in developing and regenerating limbs. There are, however, few reports which analyze the participation of endogenous RA in limb pattern formation. Using an organ culture system, we attempted to reduce the concentration of endogenous RA in the developing chick wing buds by the treatment with citral (3,7-dimethyl-2,6-octadienal), an inhibitor of retinoic acid formation. After this treatment, the cultured wing buds were grafted to the stumps of host embryos. These citral-treated limb buds frequently formed truncated cartilage elements and the defects were rescued by simultaneous treatment with an appropriate concentration of RA. These results suggest that endogenous RA plays a role in chick limb bud development
Epidermal Fate Map of theArabidopsisShoot Meristem

AbstractThe shoot meristem generates all of the aerial structures of an adult plant. It is organized in three layers which produce the epidermis (L1 layer) and the subepidermal layers (L2 and L3). The origin of adult structures has previously been fate mapped to the primary meristem for L2 and L3 tissues. In this work we constructed a fate map of L1 cells in the embryonic shoot meristem. Using the trichome mutationstichelas an epidermal marker, we analyzed 153 plants that included 178 sectors. Sectors on early leaves were found to be smaller and occurred more frequently than those on late leaves. Sectors on late leaves also appeared often to affect more than one leaf. In general, the width and extent of sectors were found to be variable rather than cell lineage-restricted. Our analysis allowed us to assign the most likely fates of L1 precursor cells within the embryonic shoot meristem. The results suggest that the meristem integrates growth dynamics and patterning of all three tissues. In contrast to this coordinated growth behavior of meristematic cells, we found a difference in the lineage restrictions between the L1 and the L2 for the formation of axillary buds
Overexpression of Xgsk-3 Disrupts Anterior Ectodermal Patterning inXenopus

AbstractTheXenopushomolog of glycogen synthase kinase-3, Xgsk-3, plays a major role in regulating the formation of the dorsal–ventral axis, most likely through effects on the mesoderm. To determine whether Xgsk-3 is involved in ectodermal patterning, Xgsk-3 was ectopically overexpressed in the presumptive ectoderm. This approach resulted in a dramatically expanded cement gland, which is due to early changes in cement gland specification at the anterior end of the embryo. Explant experiments were used to show that Xgsk-3 overexpression enhances the response of ectoderm to cement-gland-inducing signals from the mesoderm and to the intercellular signaling factor noggin. Expression of two other noggin-inducible genes,Xotx2andXANF-2,was also expanded in whole embryos, while the expression of the epidermal marker,Xgbx-2,was eliminated. These results suggest that Xgsk-3 may play a role in anterior ectodermal patterning as a component of an intracellular pathway that regulates the ectodermal responsiveness to endogenous inducing signals
Pigment Patterns of Larval Salamanders (Ambystomatidae, Salamandridae): The Role of the Lateral Line Sensory System and the Evolution of Pattern-Forming Mechanisms

AbstractIn many species of salamanders, pigment cells derived from the neural crest give rise to a horizontal stripe pattern in hatchling larvae. A defining element of these horizontal stripe patterns is a region over the middle of the myotomes that is relatively free of melanophores. This study shows that formation of a “melanophore-free region” and horizontal stripe pattern inAmbystoma tigrinum tigrinum(family Ambystomatidae) correlates with the development of the trunk lateral line sensory system. Moreover, prevention of lateral line development results in greater densities of melanophores in the middle of the flank, essentially eliminating the melanophore-free region in this taxon. A phylogenetic survey also revealed that ablation of the lateral lines has qualitatively similar effects on melanophores in seven of eight additional taxa (Ambystomatidae:A. barbouri, A. maculatum, A. talpoideum;Salamandridae:Notophthalmus viridescens, Pleurodeles waltl, Taricha granulosa, T. rivularis). InTaricha torosa,however, a superficially similar melanophore-free region forms prior to lateral line development, and ablation of the lateral lines does not perturb the horizontal stripe pattern. Finally, heterospecific grafting experiments demonstrated thatT. torosalateral lines are competent to generate a melanophore-free region, andT. torosamelanophores are competent to respond to cues associated with the lateral lines. These results indicate that lateral line-dependent pattern-forming mechanisms are common and probably ancestral within the families Ambystomatidae and Salamandridae and suggest that these ancestral mechanisms have been retained inT. torosaas redundant, lateral line-independent mechanisms for stripe formation have evolved
When Neural Crest and Placodes Collide: Interactions between Melanophores and the Lateral Lines That Generate Stripes in the SalamanderAmbystoma tigrinum tigrinum(Ambystomatidae)

AbstractA prominent element of the early larval pigment pattern in the salamanderAmbystoma tigrinum tigrinum(family Ambystomatidae) is a horizontal stripe over the lateral surface of the myotomes where otherwise abundant, neural crest-derived melanophores are not found. This study examines the formation of this “melanophore-free region.” When the trunk lateral lines were ablated (by removing cranial lateral line placodes), the melanophore-free region did not form; instead, melanophores populated the middle of the flank and the distribution of yellow, neural crest-derived xanthophores was perturbed. Time-lapse videomicrography demonstrated that during normal development, the melanophore-free region is established because melanophores retreat from the midbody lateral line primordium as it migrates caudally along the inner side of the epidermis. Melanophores do not repopulate the middle of the flank after primordium migration and heterochronic grafting experiments suggest that extracellular factors contribute to maintaining the melanophore-free region during these later stages. Finally, photographic series, microsurgical manipulations, electron microscopy, and staining for molecules of the extracellular matrix (peanut agglutinin-binding components, tenascin, chondroitin sulfate proteoglycans, fibronectin, laminin) suggest that several factors contribute to establishing and maintaining the melanophore-free region, including steric effects of the lateral lines, interactions between melanophores and xanthophores, lateral line-dependent alterations of the subepidermal basement membrane, and a general elaboration of the extracellular matrix. Lateral line effects on melanophores are inferred to be a shared, ancestral feature of pigment pattern development for the families Ambystomatidae and Salamandridae (D. M. Parichy,Dev. Biol.174, 265–282. 1996). The results of this study thus provide insights into a phylogenetically primitive mechanism for stripe formation, and a context for interpreting evolutionary innovations in pattern-forming mechanisms
Changes in the Segmental Pattern of Sensory Neuron Projections in the Chick Hindlimb under Conditions of Altered Cell Adhesion Molecule Function

AbstractIn the developing chick hindlimb, pathfinding by sensory axons is affected by their interactions with other axons entering the limb. Cell adhesion molecules (CAMs) expressed on the growing axons are likely to influence these interactions. Accordingly, to elucidate how CAMs affect sensory axon pathfinding, we injected antibodies that block the functions of NCAM, G4/L1, or N-cadherin into the hindlimb, starting at St. 25, when all motoneuron axons but only a few sensory axons had entered the plexus. In each case, the segmental pattern of projections was assessed 2–3 days later by retrogradely labeling individual peripheral nerves. With all perturbations, the gross anatomical nerve pattern developed normally; that is, some sensory axons formed cutaneous nerves while other sensory axons projected to muscles. However, the segmental pattern of sensory projections was changed when either G4/L1 or N-cadherin function was blocked in that fewer sensory axons crossed the anterior–posterior axis of the plexus. A likely reason for this effect is that anti-G4/L1 and anti-N-cadherin each decreased the amount of fasciculation and that sensory axons are less able to travel across the plexus when they are defasciculated. Anti-G4/L1 affected both cutaneous and muscle sensory projections while anti-N-cadherin affected cutaneous but not muscle sensory projections, in accord with known differences in the expression of these two CAMs on sensory and motoneuron axons. Although anti-NCAM did not appear to alter sensory projections, when polysialic acid (PSA) was enzymatically removed from NCAM, there was a marked increase in cutaneous projections from the most proximate DRG, although muscle sensory projections were unchanged. PSA removal may cause an increase in fasciculation that forces sensory axons to track along neighboring axons. Thus, without PSA, cutaneous axons project more in accord with the relative anterior–posterior positions they had as they entered the plexus. Taken together, these studies suggest that axonal fasciculation mediated by CAMs and regulated by PSA influences the ability of sensory growth cones to navigate through the plexus and project along the correct peripheral nerves
A Peroxovanadium Compound InducesXenopusOocyte Maturation: Inhibition by a Neutralizing Anti-insulin Receptor Antibody

AbstractSynthetic peroxovanadium compounds are a new class of potent inhibitors of protein phosphotyrosine phosphatases. These compounds exhibit insulin-like activity bothin vitroand in experimental animals. However, the molecular mechanism by which these compounds exert their biological effect is not well defined. We demonstrate here that several of these compounds induceXenopusoocyte maturationin vitro,as indicated by germinal vesicle breakdown. Using one of these compounds for further studies, we show that the induction is dose-dependent and is accompanied by activation of maturation promoting factor as well as activation ofXenopusMAP kinase. Like insulin, bpV(pic) causes an acute accumulation of PI(3,4,5)P3(phosphotidylinositol-3,4,5-trisphosphate), a product of PI 3-kinase. More importantly, bpV(pic)-induced oocyte maturation was abolished by microinjection of a neutralizing monoclonal anti-insulin receptor antibody (17A3) into oocytes or preincubation of oocytes with a PI 3-kinase inhibitor (wortmannin). These results suggest that bpV(pic) acts upstream of theXenopusIGF-1 receptor in the induction of meiotic maturation, presumably by neutralizing an inhibitory protein tyrosine phosphatase(s) that may regulate the receptor. Finally, using an oocyte–follicle cell complex that responded to human chorionic gonadotropin (hCG) to undergo GVBD, we showed that injection of 17A3 anti-insulin receptor antibody into oocytes did not affect hCG-induced oocyte maturation
Retinoic Acid Induces Stage-Specific Repatterning of the Rostral Central Nervous System

AbstractWe had previously reported that in gastrulating mouse embryos retinoic acid (RA) induces morphological as well molecular alterations strictly depending on the time of administration. In particular, embryos treated with RA at the mid–late streak stage share reduction of the rostral central nervous system (CNS) and increase of the hindbrain. In the same embryos, loss of the forebrain-expressed genes, such asEmx1, Emx2,andDlx1,and rostral ectopic expression of theHoxb-1gene suggest an antero-posterior (A/P) ordered repatterning of the fore-, mid-, and hindbrain regions. Several genes, such asPax-2, Wnt-1, En-2,andEn-1,are involved in the establishment of midbrain and rostral hindbrain regional identities and boundaries. We report that these genes become coordinately anteriorized only in embryos treated with RA at the late streak stage. Moreover, in the hindbrain of the same embryos, at 8.5 days post coitum (dpc),Wnt-1andPax-2are rostrally induced all along the neural plate. Considering that forebrain markers are repressed in embryos treated with RA at the same time, these findings strongly support the idea that RA administration at the late streak stage induces an ordered repatterning of the rostral CNS, possibly altering the A/P nature of mesendodermal inductive signals