pinecone/core-2020-05-10-deduplication huggingface dataset:
Competence of Oocytes from the B6.YDOMSex-Reversed Female Mouse for Maturation, Fertilization, and Embryonic Developmentin Vitro

AbstractWhen the Y chromosome of aMus musculus domesticusmouse strain is placed onto the C57BL/6J (B6) inbred genetic background, the XY (B6.YDOM) progeny develop ovaries or ovotestes, but not normal testes, during fetal life. At puberty, while some of the hermaphroditic males become fertile, none of the XY sex-reversed females produce litters. We have previously demonstrated that the eggs ovulated from the B6.YDOMovary undergo fertilization efficiently, but cannot develop beyond the 2-cell stage eitherin vivoorin vitro.In the present study, we collected oocytes directly from the XY ovary, and examined their maturation, fertilization, and embryonic developmentin vitro.The results show that the juvenile XY ovary yielded far more fertilizable oocytes by direct collection andin vitromaturation than throughin vivoovulation, but the majority of fertilized eggs failed to reach the blastocyst stage. Hence, developmental incompetence of oocytes in the XY ovary appears to be programmed during oocyte differentiation or growth. Nonetheless,in vitromatured oocytes showed a higher potential of embryonic development than the ovulated eggs, suggesting that fertility of the XY female may be impaired by multiple factors. We hypothesized that poor responsiveness of the XY ovary to gonadotropins, as we have previously demonstrated in testosterone production, may impair follicular development or proper recruitment of oocytes for ovulation. In the present study, we compared125I-hCG binding in XX and XY ovaries, but did not find a significant difference. Hence, LH activity appears to be impaired after receptor binding in the XY ovary. On the other hand, the pattern of125I-hCG binding indicated that the majority of antral follicles in the XY ovary failed to undergo normal preovulatory phases, which may explain the lower developmental capacity of eggs after ovulation
Modulation of Gene Expression in the Embryonic Digestive Tract ofC. elegans

AbstractTheCaenorhabditis elegansdigestive tract is composed of four distinct modules derived from separate cell lineages: anterior pharynx from the ABa lineage, posterior pharynx from the MS lineage, gut from the E lineage, and rectum from the ABp lineage. TheC. elegansgut esterase gene (ges-1) is normally expressed in the embryonic gut or E lineage. However, expression ofges-1can be switched into cells of the embryonic pharynx and tail by virtue of deleting a tandem pair of WGATAR sites in theges-1promoter. Here, we use both laser ablation experiments and genetic analysis to show that cells expressing the WGATAR-deletedges-1transgene belong to all three nongut lineages of the digestive tract: ABa, MS, and ABp. We also show that the molecular size and spatial distribution ofges-1mRNA transcripts produced by either the WGATAR-deletedges-1transgene or the undeletedges-1control transgene appear correctly regulated, suggesting that the spatial switch inges-1expression occurs at the level of transcription initiation. We further show that both the WGATAR-deleted and the undeletedges-1transgenes respond appropriately to mutations in a series of maternal effect genes (skn-1, mex-1, pie-1,andpop-1) that alter early blastomere fate. Moreover, the pharynx/tail expression of the WGATAR-deletedges-1transgene is abolished by mutations in the zygotic genepha-4.Finally, we use imprecise transposon excision to produce two independentC. elegansstrains with 1- to 2-kb deletions that remove the tandem WGATAR sites from the promoter of the endogenous chromosomalges-1gene: in both of these strains,ges-1is not expressed in the embryonic gut but is expressed in cells of the embryonic pharynx; pharynx expression is weak but incontrovertible. Overall, our results validate previous transgenic analysis ofges-1control and show further thatges-1appears to be regulated in a system-specific, rather than a lineage-specific, manner. The multiple facets ofges-1expression provide an opportunity to investigate how a multicomponent organ system such as the digestive tract is established from diverse cell lineages
Afork head/HNF-3 Homolog Expressed in the Pharynx and Intestine of theCaenorhabditis elegansEmbryo

AbstractWe have cloned a member of thefork head/HNF-3 family of transcription factors from the nematodeCaenorhabditis elegans.Within the predicted DNA binding domain, this gene, calledCe-fkh-1,is 75–78% identical to theDrosophila fork headand rat liver HNF-3 α, β, and γ genes.Ce-fkh-1mRNA is highly enriched in embryos. TheCe-fkh-1gene produces three major transcripts: the longest mRNA retains its original 5′-end but two shorter mRNAs aretrans-spliced at the beginning of exons 2 and 3, respectively.In situhybridization and transgenicCe-fkh-1::lacZreporter constructs indicate that theCe-fkh-1gene is expressed in both pharynx and intestine of the embryo, beginning at the midproliferation stage. A second phase ofCe-fkh-1expression occurs in cells of the larval somatic gonad. The pharynx–gut expression ofCe-fkh-1in theC. elegansembryo is compared with expression offork headthroughout the gut ofDrosophilaembryos and with expression of HNF-3 (αβγ) in the endoderm of mammalian embryos. Such conserved patterns of gene expression point to universal features of gastrulation and of digestive tract formation
Correlations between Terminal Mitosis and Differentiated Fate of Retinal Precursor Cellsin Vivoandin Vitro:Analysis with the “Window-Labeling” Technique

AbstractWe have investigated with high resolution the timing of retinal precursor cell commitment to specific differentiated fates, using anin ovomodification of thein vitro“window-labeling” technique (A. M. Repka and R. Adler,J. Histochem. Cytochem.40, 947–953, 1992a). The method involves an initial injection of tritiated thymidine into chick embryos, followed a specified number of hours later by an injection of bromodeoxyuridine (BrDU); cells born during this period are identified by being labeled with thymidine but not with BrDU. We used this method to determine, in a narrow region adjacent to the choroid fissure, the fate of cells born during defined 5-hr intervals between Embryonic Days (ED) 4–8. All the cohorts gave rise to heterogenous differentiated populations, indicating that time of cell birth is not a major cell fate determinant. A progressive restriction in the developmental potential of precursor cells, however, was suggested by the observed decrease in the number of different populations generated during each 5-hr period from ED 4 to 8, and supported also by dissociated cell culture experiments investigating the fate of cells born at different developmental stages. Microenvironmental influences were testedin vitrousing cells windowed-labeledin ovofor 5 hr on ED 5. After spending at least 72 hr within the retina before their isolation for culture, these cells mimicked theirin vivofate, giving rise predominantly to nonphotoreceptor neurons; a completely different behavior was observed when the cells were isolated after shorter exposures to the retinal microenvironment, when they gave rise predominantly to photoreceptors. Together with data demonstrating that differential cell death cannot account for these results, our results are consistent with the hypothesis that cell fate determination occurs after the time of terminal mitosis
cec-1,a Soma-Specific Chromobox-Containing Gene inC. elegans

AbstractThe chromo domain is a phylogenetically conserved sequence motif which was identified as a region of homology between the repressor protein Pc and the heterochromatin constitutive protein HP1 ofDrosophila.The specific function of the chromo domain is not yet understood, but it seems to be required for protein–protein interactions in chromatin-associated complexes. Here, we present a new chromobox-containing gene fromCaenorhabditis elegans(cec-1). It encodes a nuclear protein that is present in all somatic cells from the 50- to 80-cell stage on throughout development and in adult animals. Nocec-1protein was detected in the cells of early embryos, in germ cells, and in their precursor cells Z2 and Z3.cec-1mRNA, however, is already present in all the blastomeres of early embryos. Immunolocalization experiments revealed a homogeneous distribution of CEC-1 within interphase nuclei, while during mitosis CEC-1 seems to dissociate from the condensing chromosomes. The expression pattern of thecec-1gene suggests that it may represent a new regulatory gene inC. elegans
Cloning and Early Dorsal Axial Expression of Flik, a Chick Follistatin-Related Gene: Evidence for Involvement in Dorsalization/Neural Induction

AbstractWe have cloned and sequenced a chick gene, Flik (follistatin-like) that appears to be the homolog of the mammalian TSC36. The ORF encodes a secreted protein of approx 38 kDa, containing a single cysteine-rich domain that shows a strong relationship with the second of the four from which Follistatin is constructed. The remainder of the Flik protein shows no strong family affinities. We describe here the normal expression pattern of the gene during primitive streak and neurula stages. We also give revised data for early neurectodermal expression of chick follistatin (Connollyet al.,1995,Developmental Genetics17(1), 65–77) and follow the new ectopic expression of both genes during the induction of a second neural axis, after grafting of Hensen's node into a peripheral position in a host blastoderm. Both genes mark the organizer (node and/or mesodermal head process) and early neural plate, and could thus be involved in intercellular signaling during mesodermal dorsalization and neural induction. Flik expression appears earlier than that of follistatin however, and unlike that of follistatin, it is maintained strongly in the dorsal midline with intensity smoothly declining into presumptive lateral regions. We show that both genes are upregulated in host tissue in the neighborhood of node grafts, but whereas follistatin is transcribed after 8–10 hr in host epiblast that has formed new neural plate, Flik is expressed within 4 hr in this region, sometimes detectable before the first structural changes (columnarization) of neuralization. Thus, although ectodermal Flik expression is later confined within neural plate, and mesodermal expression concentrated in dorsal axial tissue, its early distribution is consistent with the idea that the encoded protein may first be involved in generating a graded system that positions the boundaries of both neural and dorsal axial mesodermal territories. The results are discussed in relation to this hypothesis and to other recent findings regarding control of vertebrate dorsoventral patterning
The Expression and Regulation ofFollistatinand aFollistatin-likeGene during Avian Somite Compartmentalization and Myogenesis

AbstractWe report on the normal and experimentally altered expression of two structurally related genes,FollistatinandFollistatin-like(Flik), in the somites of avian embryos. In normal chick embryos,Follistatinexpression can first be seen in the cells of the dorsolateral somite quarter. During somite maturation, the cells of the dorsomedial quarter also express this gene. Within the dermomyotome it seems that only the muscle precursors areFollistatin-positive. The migrating precursors of limb and tongue muscle as well as the myotome cells showFollistatinexpression. The manipulation experiments reveal that the expression ofFollistatinin the somites can be inhibited by notochord signals. This effect can be mimicked by sonic hedgehog protein.Flikis expressed in the dorsomedial compartment of the somite and later on in the myotome. UnlikeFollistatin, Flikexpression requires signals emanating from the neural tube. Notochordal influences do not alterFlikexpression. The expression of both genes does not depend on signals of intermediate or lateral mesoderm. Since the products of both genes are proposed to antagonize TGF-β superfamily proteins during gastrulation and neuralization, we postulate that during myogenesis follistatin and flik counteract inhibiting effects of related molecules on muscle differentiation
Development of the Aortic Vessel Wall as Defined by Vascular Smooth Muscle and Extracellular Matrix Markers

AbstractThe building of the vessel wall from its cellular and extracellular matrix (ECM) components is a critical event in the development and maturation of the cardiovascular system. However, little is known about the events that occur after the initial vascular network, a nascent endothelium, is established. The proper recruitment of vascular smooth muscle cells (VSMCs) to the endothelium is one such critical event. Although the majority of VSMCs are of mesodermal origin, it is not understood which populations of embryonic cells are capable of following the VSMC differentiation pathway. Previous studies, which have focused on the VSMC component of vessel wall development, have been limited by the use of markers that are not smooth muscle specific, or have focused on events that occur after a multilayered wall has been established. Therefore, the initial goal of this study was to define when overtly identifiable VSMCs were first associated with the vascular endothelium. Monoclonal antibodies (MAbs) were generated from embryonic vessel wall antigens in order to circumvent problems of cell specificity associated with the use of previously available markers to VSMCs. Critical to this study is our MAb, 1E12, which unlike other antibody markers, is smooth muscle specific. Using 1E12, we defined a pattern for recruitment and differentiation of the VSMC component of the descending aorta in stage 12 to stage 20 (Hamburger and Hamilton, 1951) quail embryos. Immunofluorescent labeling of quail embryos with 1E12 and a MAb to smooth muscle α-actin (SMαA) shows that the first mesodermally derived cells to associate with the aortic endothelium do so at the ventral surface. Recruitment of these cells, which we believe to be primordial VSMCs, proceeds in a ventral to dorsal direction along the aorta and in a radial direction, emanating from the endothelium. Additionally, we have determined the distribution of several ECM proteins, during the initial events of vessel wall development. Our studies show that fibulin-1 is expressed surrounding the primordial VSMCs of the vessel wall before elastin precursors are present and suggest that differential expression of the JB3 antigen (Wunschet al.,1994) may be indicative of early diversity among embryonic VSMCs
Oocyte Maturation Involves Compartmentalization and Opposing Changes of cAMP Levels in Follicular Somatic and Germ Cells: Studies Using Selective Phosphodiesterase Inhibitors

AbstractThe second messenger cAMP has been implicated in the regulation of mammalian and amphibian oocyte maturation. Although a decrease in intraoocyte levels of cAMP precedes germinal vesicle breakdown (GVBD), the gonadotropin induction of ovulation and oocyte maturation is associated with major increases of cAMP in ovarian follicles. In the mammalian system, isolated oocytes undergo spontaneous maturationin vitrobut this process is blocked by treatment with a phosphodiesterase (PDE) inhibitor, IBMX, which increases intraoocyte cAMP levels. In contrast, the same inhibitor, when added to cultured follicles for a brief time, increases follicle cAMP levels, followed by the induction of GVBD. To resolve the paradoxical actions of this PDE inhibitor on the maturation of isolated and follicle-enclosed oocytes, we hypothesized that meiotic maturation requires opposing fluctuations of cAMP levels in the somatic granulosa and germ cells. Such opposing fluctuations may result from selective expression and regulation of PDEs in the somatic and germ cell compartments of the follicle. To test this hypothesis, PDE activity was manipulated in different follicular cells using type-specific inhibitors. The impact of the ensuing changes in cAMP levels in the two compartments was monitored by the induction of GVBD. In isolated oocytes, spontaneous GVBD was blocked by two inhibitors of type 3 PDE (cGMP-inhibited: CGI-PDE), milrinone and cilostamide. In contrast, treatment with an inhibitor for type 4 PDE (cAMP-specific), rolipram, was ineffective. These findings suggest that the oocyte expresses type 3 but not type 4 PDE and that increases in intraoocyte cAMP suppress GVBD. This hypothesis was confirmed byin situhybridization studies with PDE3 and PDE4 probes. PDE3B mRNA was concentrated in oocytes while PDE4D was mainly expressed in granulosa cells. In cultured follicles, LH treatment induced oocyte maturation but the gonadotropin action was blocked by inhibitors of type 3 but not the type 4 PDE inhibitors. Furthermore, treatment with the type 4, but not the type 3, PDE inhibitor mimics the action of LH and induces oocyte maturation, presumably by increasing cAMP levels in granulosa cells. Our findings indicate that PDE subtypes 4 and 3 are located in follicle somatic and germ cells, respectively. Preferential inhibition of PDE 3 in the oocyte may lead to a delay in oocyte maturation without affecting the cAMP-induced ovulatory process in the somatic cells. Conversely, selective suppression of granulosa cell cAMP–PDE may enhance the gonadotropin induction of ovulation and oocyte maturation. Thus, in addition to the well-recognized differential expression and regulation of adenylate cyclase in the somatic and germ cell compartments of the follicle, we suggest that selective regulation and expression of PDEs may be involved in the regulation of cAMP levels and control of oocyte maturation in the preovulatory mammalian follicle
A Central Body Region Defined by a Position-Specific Molecule in the PlanarianDugesia (Girardia) tigrina:Spatial and Temporal Variations during Regeneration

AbstractWe have isolated a monoclonal antibody, TCEN49, that displays position-specific binding to the central body region of the planarianDugesia (Girardia) tigrina.TCEN49 binds to all cell types of the central area with the exception of epithelial cells. Labeled cells are more related by position than by lineage. In the intact organism, boundaries between labeled and unlabeled regions are very sharp and in a dynamic state as they shift in relative position along the body axis during growth and degrowth. During regeneration, TCEN49 antigen is present in the area which will form the central region before it is morphologically apparent. Moreover, when animals are cut through the central region, TCEN49 label fades quickly from those regions determined to become head or tail well before morphogenesis takes place. Taken together, these data suggest that expression of TCEN49 antigen is very sensitive to positional information changes and that it could be involved in the expression of central-body positional identity. TCEN49 antigen is a glycoprotein with an apparent molecular weight of 4.5 kDa, as determined by gel immunoblotting. Immunogold light and electron microscopy demonstrate that the main location of TCEN49 antigen is intracellular (granular components of secretory cells and, to a lesser extent, clear cytoplasmic vesicles and heterochromatin blocks), though it is also detected in the extracellular matrix. TCEN49 antigen represents the first position-specific molecule reported in planarians to date
Induction of Myogenesis in Mesenchymal Cells by MyoD Depends on Their Degree of Differentiation

AbstractExpression of a transfected MyoD gene induces myogenic differentiation of most cell types. In this study, we evaluated the ability of an exogenous MyoD gene to induce myogenic conversion in two pairs of matched cell lines with different degrees of differentiation within either the osteoblastic or chondrocytic lineage. We show that osteoblasts and chondrocytes are resistant to the myogenic effects of MyoD alone. However, in their less-differentiated cell line counterparts, MyoD induces expression of muscle-cell-specific markers. Less-differentiated osteoblasts can be made resistant to MyoD-induced myogenic conversion by induction of adipogenic differentiation using dexamethasone. Finally, a dominant positive form of MyoD, one which is tethered to a partner, E47, activates muscle-specific gene expression in osteoblasts. Our results suggest that the response of a cell to MyoD depends on its lineage and its degree of differentiation. Furthermore, commitment of cells to the osteoblastic or chondrocytic lineage may involve inhibition of alternative pathways, such as those leading to myoblastic differentiation. Finally, osteoblasts may express a protein(s) which interferes with the activity of MyoD by inhibiting its association with E proteins. This interference can be overcome by expression of the MyoD–E47 hybrid, suggesting that osteoblasts are otherwise competent to undergo myogenic conversion
Onset ofC. elegansGastrulation Is Blocked by Inhibition of Embryonic Transcription with an RNA Polymerase Antisense RNA

AbstractCleavage and gastrulation initiation inCaenorhabditis elegansembryos are characterized by an invariant temporal and spatial pattern of cell divisions and cell movements. Although bulk embryonic transcription does not begin until gastrulation onset, some transcription can be detected as early as the 4-cell stage. To determine whether any early transcripts are required for normal cleavage-stage patterning, we blocked transcription in embryos by injecting hermaphrodite parental gonads with RNA antisense to theama-1gene, which encodes the large subunit of RNA polymerase II. This treatment prevented the expression of a reporter gene driven by an early embryonic promoter but did not detectably perturb the maternally controlled segregation of the germ line P granules or the pattern of cell division through the first four cleavages. In the fifth cell cycle, however, the two endodermal precursor (E) cells divided early and abnormally and failed to initiate gastrulation. The embryos arrested between the sixth and seventh cell cycles with less than 100 cells. These results indicate that embryonically transcribed gene products are required for gastrulation initiation. They also demonstrate the efficacy of a method for blocking embryonic transcription that may be useful in other organisms
Spontaneous Calcium Transients Regulate Myofibrillogenesis in EmbryonicXenopusMyocytes

AbstractSpontaneous transient elevations of intracellular calcium (Ca2+i) have functional roles in the development ofXenopusspinal neurons. However, less is known about the roles of elevations of Ca2+iin the differentiation of other cell types. We have examinedXenopusmyocytes as a first step in determining if Ca2+itransients are a more general feature of differentiation in excitable cells. We find that cultured myocytes, like neurons, exhibit spontaneous Ca2+itransients during an early developmental period. These transients average 1.4 min in duration and occur at an average frequency of 6/hr in cultures containing myocytes and neurons. Culture conditions can influence transient production; for example, myocyte-enriched cultures have a lower incidence of transient-producing cells. Transients persist in 0-Ca2+medium, indicating that they arise from intracellular stores. Caffeine-sensitive Ca2+stores are present in these cells, and depletion or block of these stores eliminates transient production. To determine if transients play a functional role during development, we blocked their production with intracellular BAPTA, a rapid Ca2+chelator. Cellular differentiation is significantly inhibited only when BAPTA is applied early in development, during the period of transient production, while later BAPTA treatments have no effect. Blocking transient production severely perturbed myofibril organization and sarcomere assembly. However, other aspects of myocyte differentiation were not affected by transient blockade, indicating that not all myogenic differentiation programs are regulated in this manner. Our results suggest that spontaneous Ca2+itransients play a role in cytoskeletal organization during myofibrillogenesis