pinecone/core-2020-05-10-deduplication huggingface dataset:
Increased Expression of Laminin-1 and Collagen (IV) Subunits in the Aganglionic Bowel ofls/ls,but Notc-ret−/− Mice

AbstractExtracellular matrix molecules, including laminin, affect the development of enteric neurons and accumulate in the aganglionic colon ofls/lsmice. Quantitative Northern analysis revealed that mRNAs encoding the β1 and γ1 subunits of laminin and collagens α1(IV) and α2(IV) are increased in the colons ofls/lsmice. Transcripts of laminin α1 were evaluated quantitatively with reverse transcription and the competitive polymerase chain reaction (RT–cPCR). The abundance of laminin α1 transcripts was developmentally regulated, but greater in thels/lsthan the wild-type colon at each age examined.In situhybridization revealed that transcripts in the colon encoding laminin α1 and β1 and collagen α2(IV) were initially expressed in the endoderm, but by E15, expression shifted to cells of the colonic mesenchyme (ls/ls> wild type) where crest-derived cells migrate. The expression of laminin α1 was examined in the totally aganglionic intestine of E15 and newbornc-ret−/− mice, to determine whether an increase occurs when neurogenesis fails independently of thels/lsdefect. RT–cPCR revealed no difference from control in mRNA encoding laminin α1 in thec-ret−/− colon in either E15 or newborn animals. The accumulation of immunohistochemically demonstrable laminin that is prominent in the newbornls/lscolon could not be detected in that ofc-ret−/− animals. These observations suggest that transcripts encoding laminin-1 and collagen (IV) are increased in the colon and surrounding pelvic mesenchyme ofls/lsmice because of an intrinsic lesion, rather than a secondary consequence of aganglionosis. The data are compatible with the hypothesis that the increased expression of laminin-1 contributes to the failure of crest-derived cells to complete their colonization of thels/lscolon
Twins Raised from Separated Blastomeres Develop into Sexually MatureStrongylocentrotus purpuratus

AbstractThe first two blastomeres ofStrongylocentrotus purpuratusembryos were separated and the resulting twins raised in pairs through larval life and to sexual maturity. We derive two conclusions from this study: changes in the pattern of specification of embryonic cell fates following blastomere separation result in the creation of two sets of fully functional coelomic pouches and imaginal rudiments, and sex determination in sea urchins is chromosomal, since the pairs of twins were always of the same sex
Gap Junction Formation between Cultured Embryonic Lens Cells Is Inhibited by Antibody to N-Cadherin

AbstractIntercellular communication mediated by gap junctions is important for tissue homeostasis in the avascular lens, and extensive areas of gap junctions form between fiber cells during fiber cell differentiation and lens development. We examined the role of the calcium-dependent cell adhesion molecule, N-cadherin, in the process of gap junction formation between fiber cells. Lentoids, multicellular structures with characteristics of differentiated fiber cells, were isolated from embryonic chick lens cultures and subsequently paired to provide anin vitromodel of fiber cell interactions. Gap junction formation between cells of paired lentoids was monitored by observing the lentoid-to-lentoid transfer of fluorescent dyes, either calcein or Lucifer yellow, over a time course of up to 48 hr. Dye transfer between lentoids was inhibited upon the addition to the medium of Fab fragments (100–622 μg/ml) of a monoclonal antibody specific for N-cadherin, and also by the reduction of extracellular calcium in the incubation medium. However, the addition of Fab fragments (100–1500 μg/ml) of an antibody to a fiber-cell-specific integral membrane protein, MIP, did not change the time course nor extent of dye transfer between lentoids. Our results, using cultured embryonic cells, extend those from previous studies with cell lines and transfected cells. We conclude that cadherin interactions facilitate the formation of gap junctions between embryonic lens fiber cells, by the stabilization of membrane appositions and/or by the generation of an intracellular signal(s)
The Role of Localized Cell Surface-Associated Glycoproteins during Fertilization in the HydrozoanAequorea

AbstractHydrozoan eggs can be fertilized only at the site of polar body formation and first acquire this ability during second polar body formation. The eggs ofAequorea victoriaform a discrete Triticum lectin binding moiety in the jelly coat near the first polar body as it is being given off and also a discrete concanavalin A binding moiety associated with the egg surface where the second polar body forms, which disappears immediately after fertilization. The germinal vesicle has an eccentric position in full grownAequoreaoocytes. The region of oocyte surface closest to the germinal vesicle is the site where the polar bodies normally form. When oocytes are centrifuged during oocyte maturation, the meiotic apparatus sometimes shifts to a different position with reference to the egg surface and polar bodies are given off at this new site. There is a corresponding shift in the position of the Triticum and concanavalin A lectin binding moieties, indicating that their formation is associated with local events occurring at the site of polar body formation. Treatment ofAequoreaeggs with Triticum or concanavalin A causes a marked reduction in the ability of these eggs to be fertilized, suggesting that sugar-containing moieties, to which the lectins bind, play a role in fertilization. Removal of sugars on these moieties with mannosidase orN-acetylglucosaminidase, or the cleavage of the protein the sugars are attached to with trypsin, results in eggs that do not bind Triticum or concanavalin A and also show a marked reduction in the ability to be fertilized. These experiments suggest that the lectin binding moieties are glycoproteins
cAMP-Dependent Protein Kinase Is Required for the Expression of a Gene Specifically Expressed inDictyosteliumPrestalk Cells

AbstractIn theDictyosteliumslug there are two types of prestalk cells, pstA cells and pstO cells, that differ in their ability to utilize the distal and proximal parts of the promoter ofecmA,a gene that is specifically expressed in prestalk cells. When Rm, a dominant inhibitory form of the regulatory subunit of cAMP-dependent protein kinase (PKA), is expressed under the control of the complete promoter of theecmAgene (in a construct termed ecmAO:Rm) development proceeds to the slug stage. Although able to form small but outwardly normal slugs, ecmAO:Rm cells are defective in prestalk cell differentiation. In ecmAO:Rm cells, the induction of pstA- and pstO-specific gene expression by the stalk cell inducer DIF is greatly inhibited. Paradoxically, a very large fraction of the cells in an ecmAO:Rm slug show evidence of once having expressed the ecmA and ecmO prestalk markers. However, we present evidence that this is due to abortive prestalk cell differentiation that terminates when sufficient Rm protein has accumulated to block PKA activity. This results in regulative transdifferentiation of prespore cells to form prestalk cells. During their transitory period as prestalk cells the ecmAO:Rm cells coexpress both the ecmA and ecmO markers, indicating a possible link between PKA activity and divergence of the two prestalk cell subtypes. Finally, we show that the level of the DNA binding activity believed to lie at the end of the DIF signal transduction pathway is reduced in ecmAO:Rm slugs
The Embryonic Central Nervous System Lineages ofDrosophila melanogaster I. Neuroblast Lineages Derived from the Ventral Half of the Neuroectoderm

AbstractCentral nervous system development inDrosophilastarts with the delamination from the neuroectoderm of about 30 neuroblasts (NBs) per hemisegment. Understanding the mechanisms leading to the specification of the individual NBs and their progeny requires the identification of their lineages. Here we describe 17 embryonic NB lineages derived from the ventral half of the neuroectoderm and we assign these lineages to identified medial and intermediate NBs. The lineages are composed of interneurons (NB 1-2, NB 2-1, MP2, NB 4-1, NB 5-1, NB 5-3, NB 6-1, NB 6-2, and NB 7-2), interneurons and motoneurons (NB 3-1, NB 3-2, NB 4-2, NB 5-2, NB 7-1, and NB 7-3), or interneurons, motoneurons, and glial cells (NB 1-1 and NB 2-2). NB 1-1, NB 2-2, and NB 3-1 form segment-specific lineages. Neuroectodermal progenitors forming NB 2-1, NB 5-1, and NB 7-3 divide while still in the ectoderm to give rise to an additional epidermoblast. Expression of segmentation genes is not lineal in the clones of NB 1-2 and NB 7-3 (engrailed), NB 1-1, NB 4-2, and NB 7-1 (even-skipped), and NB 7-1 (gooseberry-proximal). The timing of delamination for individual NBs as well as the number of their progeny is not strictly invariant. The 17 NBs produce about 200 neurons and only three glial cells, corresponding to about 70% of the estimated total number of neurons and 10% of the glial cells per thoracic and abdominal hemisegment. Previously identified neural cell types were linked to particular lineages and we introduce a systematic terminology for the ventral nerve cord neurons. The wild-type clones provide a foundation for the analysis of mutants, expression patterns, and experimental manipulations
daughterlessIs Required forDrosophilaPhotoreceptor Cell Determination, Eye Morphogenesis, and Cell Cycle Progression

AbstractInitiation ofDrosophilaperipheral nervous system (PNS) development requires theachaete–scutecomplex (AS-C) and theatonal(ato) genes. The AS-C andatoencode basic helix-loop-helix (bHLH) transcription factors that dimerizein vitrowith another bHLH protein,daughterless(da).dahas many functions duringDrosophilaembryonic development, as it is required for proper sex determination, oogenesis, and neurogenesis. Here, we examine the expression and function ofdawithin the developingDrosophilaeye. The use of a monoclonal antibody to the Da protein revealed that Da levels are modulated across the developing eye disc. Within the morphogenetic furrow (MF) and photoreceptor cell R8, there is a cell-by-cell correspondence between high levels of Da protein expression and Ato protein expression. Mosaic analysis of adult tissue demonstrates thatdafunction is cell autonomous and required within R2, R3, R4, R5, and R8. Examination of gene expression inda−imaginal disc clones reveals thatdaregulates Ato expression in the MF, affects the progression of the MF, and is necessary for the reestablishment of the G2and M phases of the synchronized cell cycle posterior to the MF
Transforming Growth Factor-β Is a Survival Factor for Neonate Cortical Neurons: Coincident Expression of Type I Receptors in Developing Cerebral Cortices

AbstractTransforming growth factor-β (TGF-β) is a multifunctional polypeptide which plays a crucial role in the regulation of cell proliferation, differentiation, and organogenesis. In the present study, we investigated the expression of signaling receptors for TGF-β in developing mice byin situhybridization, revealing a significant difference in the expression of TGF-β type I and type II receptors. Unexpectedly, the TGF-β type I receptors were exclusively expressed without any detectable expression of the TGF-β type II receptors in developing cerebral cortices. In primary cortical neurons, a neutralizing antibody for TGF-β significantly reduced the expression ofbcl-2and subsequently induced neuronal cell death, indicating that TGF-β functions as a survival factor for cortical neuronsin vitro.Consistent with the result ofin situhybridization, the TGF-β type I but not type II receptors were detected in primary cortical neurons by affinity crosslink and RT–PCR analyses. The concomitant expression of TGF-β2 and the TGF-β type I receptors in developing cerebral cortices suggests that the TGF-β signaling system plays a pivotal role in neuronal differentiation and that unidentified components may be involved in TGF-β signaling in the development of the central nervous system
Inhibition of Cranial Neural Crest Adhesionin Vitroand Migrationin VivoUsing Integrin Antisense Oligonucleotides

AbstractAlthough it is well-established that β1integrins play a functional role in the migration of cranial neural crest cells, little is known about the number or importance of their associated α subunits. Here, we have utilized antisense oligonucleotides (aONs) against various mammalian integrin α subunits to functionally “knock out” integrinsin vitroandin vivo.First, we examined the attachmentin vitroof cranial neural crest cells to fibronectin and laminin in the presence of antisense or reversed-sense oligonucleotides using a quantitative adhesion assay. We found three α integrin aONs that blocked attachment to fibronectin substrates only, one that blocked attachment to laminin substrates only, and one that blocked attachment to both fibronectin and laminin. As expected, an aON to chick β1integrin reduced attachment to both fibronectin and laminin substrates. These results suggest that there are three or more functionally distinct integrin heterodimers on avian cranial neural crest cells. Second, we examined the ability of aONs against various α integrin subunits to perturb cranial neural crest migrationin vivoby injecting the oligonucleotides into the cranial mesenchyme through which neural crest cells migrate. Those α aONs that inhibited cell attachmentin vitroalso caused neural crest and/or neural tube abnormalities after injectionin vivo.In addition, two aONs that had no effectin vitrodid affect emigration of neural crest cellsin vivo.Immunoprecipitations revealed that some integrin subunits were depleted after treatment with antisense but not reversed-sense oligonucleotides bothin vivoandin vitro.The results suggest that integrin α subunits are required for cranial neural crest cell attachment and emigration
The Cellular Patterns of BDNF andtrkBExpression Suggest Multiple Roles for BDNF duringXenopusVisual System Development

AbstractThe temporal patterns of BDNF andtrkBexpression in the developingXenopus laevistadpole, and the responsiveness of retinal ganglion cells to BDNF, both in culture andin vivo,suggest significant roles for this neurotrophin during visual system development (Cohen-Cory and Fraser,Neuron12, 747–761, 1994;Nature378, 192–196, 1995). To examine the potential roles of this neurotrophin within the developing retina and in its target tissue, the optic tectum, we studied the cellular sites of BDNF expression byin situhybridization. In the developing optic tectum, discrete groups of cells juxtaposed to the tectal neuropil where retinal axons arborize expressed BDNF, supporting the target-derived role commonly proposed for this neurotrophin. In the retina, retinal ganglion cells, ciliary margin cells, and a subset of cells in the inner nuclear layer expressed the BDNF gene. The expression of BDNF coincided with specifictrkBexpression by both retinal ganglion cells and amacrine cells, as well as with the localization of functional BDNF binding sites within the developing retina, as shown byin situhybridization and BDNF cross-linking studies. To test for a possible role of endogenous retinal BDNF during development, we studied the effects of neutralizing antibodies to BDNF on the survival of retinal ganglion cells in culture. Exogenously administered BDNF increased survival, whereas neutralizing antibodies to BDNF significantly reduced baseline retinal ganglion cell survival and differentiation. This suggests the presence of an endogenous retinal source of neurotrophic support and that this is most likely BDNF itself. The retinal cellular patterns of BDNF andtrkBexpression as well as the effects of neutralizing antibodies to this neurotrophin suggest that, in addition to a target-derived role, BDNF plays both autocrine and/or paracrine roles during visual system development
lem7,a Novel Temperature-SensitiveArabidopsisMutation That Reversibly Inhibits Vegetative Development

AbstractAn important question in developmental biology concerns the mechanisms by which a few cells coordinate division and differentiation to yield the complex structures and organs found in multicellular organisms. During vegetative growth in plants, cells in the apical meristem must coordinate division and differentiation to yield the fully mature leaf organ. Alterations in these processes may result in an abnormal leaf. In this paper we present the isolation and characterization of an EMS-generated, cold-temperature-sensitive mutation inArabidopsis thaliana,designatedlem7(leafmorphogenesis).lem7is a semidominant mutation that maps to a novel locus on chromosome 2. When grown at 16°C,lem7reversibly arrests leaf development at the shoot apex. In contrast,lem7grown at 30°C appears phenotypically normal. Our data also suggest that theLem7locus may not be involved solely in leaf organogenesis, but may also play a role in floral development and the maintenance of patterns and structures after cellular differentiation. At an intermediate temperature of 23°C, leaves on thelem7plant emerged phenotypically normal but began to show drastic changes at about 13 days postgermination. These changes include a reduced bilateral symmetry, a rough leaf lamina, a reduced number of trichomes, and an altered vascular network. Leaves that developed at the permissive temperature (30°C) and shifted to the nonpermissive temperature (16°C) form tumor-like outgrowths. Histological analysis of these tumor-like outgrowths and leaves grown at the intermediate temperature reveal abnormally large mesophyll cells, a disorganized mesophyll layer, and collapsed epidermal cells. We propose that the reversible inhibition of leaf development inlem7under nonpermissive temperatures may serve as a useful tool for identifying genes involved inArabidopsisleaf organogenesis
Nonmyristoylated MARCKS Complements Some but Not All of the Developmental Defects Associated with MARCKS Deficiency in Mice

AbstractThe myristoylated alanine-rich C kinase substrate, or MARCKS protein, is a widely expressed, prominent substrate for protein kinase C. Although the exact function of MARCKS has not been elucidated, targeted disruption of the MARCKS gene (Macs) in mice has shown that MARCKS plays a crucial role in the development of the central nervous system. Mice deficient in MARCKS exhibited universal perinatal death with defects in neurulation, fusion of the cerebral hemispheres, formation of the great forebrain commissures, and retinal and cortical lamination (Stumpoet al., Proc. Natl. Acad. Sci. USA92, 944–948, 1995). In the present studies, a transgene consisting of approximately 3.4 kb of promoter from the human MARCKS gene (MACS), with an epitope tag sequence inserted at the carboxyl terminus of the MARCKS coding region, was able to complement completely MARCKS deficiency in mice. Thus, the human transgene contained all of the elements necessary for normal developmental expression of MARCKS. To test the importance of MARCKS myristoylation to its developmental role, an otherwise identical transgene was constructed in which the glycine at the amino terminus of MARCKS was mutated to an alanine. This mutation, which resulted in the expression of nonmyristoylated MARCKS, was successful in partially rescuing theMacsnull phenotype. Specifically, about 25% of these mice survived the perinatal period; these survivors appeared to develop normally except for slightly decreased body size. In both the survivors and the nonsurvivors, all of the known anatomical defects associated with MARCKS deficiency were corrected by expression of the nonmyristoylated human protein. These results indicate that myristoylation of MARCKS is not required for the protein to correct many of the developmental abnormalities characteristic of its deficiency
Alternative Splicing of theEndo16Transcript Produces Differentially Expressed mRNAs during Sea Urchin Gastrulation

AbstractTheEndo16gene codes for an RGD-containing calcium-binding protein that is found on the basal surfaces and in the extracellular matrix of cells of the invaginating archenteron during sea urchin gastrulation. Previously, we have shown thatEndo16is a single copy gene and we have determined the coding sequence and analyzed the temporal and spatial expression of a 6.6-kb mRNA. In this report we demonstrate that two additional longerEndo16mRNAs are produced by differential splicing rather than alternative promoter usage. cDNA clones for two 8.5-kb mRNAs have been isolated and analyzed. The two 8.5-kb mRNAs are identical to each other in the coding region and differ only in their 3′ UTRs. The extended open reading frame of the 8.5-kb mRNAs code for domains already identified in the 6.6-kb mRNA, including two different types of calcium-binding motifs and a region with a highly conserved cysteine pattern similar to that found in Ecm1 in the mouse. The 6.6- and 8.5-kb mRNAs show overlapping but distinct temporal as well as spatial expression patterns during gastrulation
Patterns of Distal-less Gene Expression and Inductive Interactions in the Head of the Direct Developing FrogEleutherodactylus coqui

AbstractThe direct developing frogEleutherodactylus coquiexhibits radical changes in its embryogenesis. A frog-like head forms directly with no appearance of a cement gland or several jaw cartilages characteristic of tadpoles, and limbs appear early in development. The numerous differences in the embryogenesis ofE. coquiprovide an opportunity to examine developmental causes for the evolutionary shift from biphasic to direct development. We have cloned DNA fragments corresponding to fourE. coquigenes related to theDrosophiladistal-less geneDll.While the expression patterns of the distal-less genes are generally conserved, there are some spatiotemporal differences when embryos ofE. coquiare compared to those ofXenopus laevis.The changes in gene expression are correlated with the embryonic changes in head structures including craniofacial cartilages and in particular, the cement gland. We have then examined inductive interactions involved in cement gland formation by interspecific transplants and recombinants.E. coquiembryos can generate signaling that culminates in cement gland formation, butE. coquiectoderm appears to be incapable of a cement gland response. These results show here that inductive interactions in the anterior region of theE. coquiembryo have been modified during the evolution of direct development, and that changes in the competence of theE. coquiectoderm may be responsible for the loss of certain tadpole-specific structures, such as cement gland