bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel, tissue-specific integrin subunit, βν, expressed in the midgut of Drosophila melanogaster
Authors: Yee Gene H. , Hynes Richard O. 
Published: April 2021

ABSTRACT
The integrins are a family of cell surface receptors for extracellular matrix proteins and counter-receptors on other cells. We have used the polymerase chain reaction to identify a novel integrin receptor β subunit in Drosophila melanogaster. The deduced amino acid sequence of this subunit, which we have termed βν (betaneu), indicates that it has several unusual properties. The βν subunit is roughly 33% identical with each of the previously sequenced vertebrate and Drosophila β subunits and is lacking four of the 56 cysteine residues characteristic of most members of this protein family. The expression of the βν gene is strikingly restricted. It is temporally regulated, with maximal expression occurring at 12-15 hours of embryonic development. In situ hybridization analyses and antibody localization on whole-mount embryos reveal that βν expression is tissuespecific and confined to the developing midgut endoderm and its precursors during embryogenesis. Tissue specificity of expression is maintained through later stages of development as βν transcripts are found exclusively in the larval midgut. Within this structure, βν transcripts are especially concentrated in the cells of the midgut imaginal islands which give rise to the adult midgut.
Establishment of gut fate in the E lineage of C. elegans: the roles of lineage-dependent mechanisms and cell interactions
Authors: Goldstein Bob 
Published: April 2021

ABSTRACT
The gut of C. elegans derives from all the progeny of the E blastomere, a cell of the eight cell stage. Previous work has shown that gut specification requires an induction during the four cell stage (Goldstein, B. (1992) Nature 357, 255–257). Blastomere isolation and recombination experiments were done to determine which parts of the embryo can respond to gut induction. Normally only the posterior side of the EMS blastomere contacts the inducing cell, P2. When P2 was instead placed in a random position on an isolated EMS, gut consistently differentiated from the daughter of EMS contacting P2, indicating that any side of EMS can respond to gut induction. Additionally, moving P2 around to the opposite side of EMS in an otherwise intact embryo caused EMS’s two daughter cells to switch lineage timings, and gut to differentiate from the descendents of what normally would be the MS blastomere. The other cells of the four cell stage, ABa, ABp, and P2, did not form gut when placed in contact with the inducer. To determine whether any other inductions are involved in gut specification, timed blastomere isolations were done at the two and eight cell stages. In the absence of cell contact at the two cell stage, segregation of gut fate proceeded normally at both the two and four cell stages. Gut fate also segregated properly in the absence of cell contact at the eight cell stage. A model is presented for the roles of lineage-dependent mechanisms and cell interactions in establishing gut fate in the E lineage.
Foetal testes control the prenatal growth and differentiation of the gubernacular cones in rabbits - a tribute to the late Professor Alfred Jost
Authors: Schoot P. van der 
Published: April 2021

ABSTRACT
Gubernacular cones develop during foetal life in males of various species, including many of the common small laboratory animals. Postnatally these papilla-like organs invert and develop into the muscular cremaster sacs, providing space for testis descent. The mechanism governing male-specific development of these structures during foetal and postnatal life is unknown but foetal testicular androgens or anti-Müllerian hormone are unlikely to be involved. The present study of gubernacular cone development in 28-day-old rabbit foetuses castrated 5–9 days before questions whether foetal testis hormones play any role in these developmental processes. The study comprised an analysis of the microscopic slides in the legacy of the late Professor Alfred Jost in Paris.
Castration at an earlier (19 days) or later (23/24 days) day of foetal life interfered with gubernacular cone growth and differentiation. Unilateral castration partially inhibited ipsilateral gubernacular cone growth. Implantation of a foetal testis close to the ovary could induce male-type gubernacular cone growth in females. Together the data unequivocally support the concept of foetal testicular hormonal control of male-specific gubernacular cone development. Further study is required to unravel the nature of the active foetal testicular agent.
Mesoderm formation in Xenopus ectodermal explants overexpressing Xwnt8: evidence for a cooperating signal reaching the animal pole by gastrulation
Authors: Sokol S. Y. 
Published: April 2021

ABSTRACT
It is demonstrated here that the ability of injected Xwnt8 RNA to trigger mesoderm formation in Xenopus presumptive ectoderm (animal caps) depends on the time of explantation. Animal caps isolated from Xwnt8 injected embryos at the late blastula/early gastrula stages differentiate mesodermal tissues whereas caps isolated from early blastula do not. This finding suggests that an endogenous signal reaches the animal cap by the late blastula stage and cooperates with Xwnt8 to induce mesoderm. Similarly, late animal caps isolated at st. 10 from lithium-treated embryos, but not those from control embryos, elongate and express muscle-specific actin transcripts. In addition, the data presented suggests that the cooperating signal is distributed homo-geneously with respect to the future dorsoventral axis and may require FGF- and activin-dependent signal transduction pathways. These observations support a model in which mesoderm is induced in vivo by a combined action of several different signals.
Stem cell factor induces outgrowth of c-kit-positive neurites and supports the survival of c-kit-positive neurons in dorsal root ganglia of mouse embryos
Authors: Hirata Tatsumi , Morii Eiichi , Morimoto Masahiro , Kasugai Tsutomu , Tsujimura Tohru , Hirota Seiichi , Kanakura Yuzuru , Nomura Shintaro , Kitamura Yukihiko 
Published: April 2021

ABSTRACT
The c-kit receptor tyrosine kinase is highly expressed by about 10% of the neurons in the dorsal root ganglia (DRGs) of mouse embryos. We investigated the in vitro effect of stem cell factor (SCF), the ligand for c-kit receptor, on DRGs. Recombinant murine SCF (rmSCF) induced the outgrowth of c-kit-positive neurites from DRGs of normal (+/+) embryos. The effect of SCF was dose dependent and completely abolished by anti-c-kit ACK2 monoclonal antibody (mAb). Some neurites whose outgrowth was induced by nerve growth factor (NGF) were c-kit-positive, but anti-NGF mAb did not inhibit the rmSCF-induced neurite outgrowth. rmSCF did not induce neurite outgrowth from DRGs of W/W embryos that did not express c-kit receptors on the cell surface and of W42/W42 mutant embryos that expressed c-kit receptors without tyrosine kinase activity. rmSCF also had a trophic effect on c-kit-positive neurons in the culture of dissociated DRG cells. Most c-kit-positive neurons appeared to respond to NGF as well, and the SCF-responsive subpopulation represented about 10% of NGF-responsive neurons. rmSCF did not support the survival of DRG neurons from embryos of W/W and W42/W42 genotypes. These results suggest that the stimulus through the c-kit receptor tyrosine kinase has an important role in development of the peripheral nervous system.
Novel genes expressed differentially in ascidians with alternate modes of development
Authors: Swalla Billie J. , Makabe Kazuhiro W. , Satoh Noriyuki , Jeffery William R. 
Published: April 2021

ABSTRACT
We have used a subtractive procedure to isolate cDNA clones encoding genes expressed differentially in ascidian species with alternate modes of development. The ascidians used in this study were Molgula oculata, which develops a tailed (urodele) larva, and Molgula occulta, which develops a tailless (anural) larva. Two of the identified clones, Uro-2 and Uro-11, are described. Southern blots show that the Uro-2 and Uro-11 genes are present in both species, but the corresponding mRNAs are expressed preferentially in the urodele species. In situ hybridization showed that Uro-2 and Uro-11 transcripts accumulate in small oocytes during oogenesis. The maternal Uro-2 and Uro-11 transcripts were distributed throughout the oocyte cytoplasm. Transcript concentrations declined during vitellogenesis, but mature eggs still contain detectable levels of Uro-2 and Uro-11 mRNA. After fertilization, the maternal Uro-2 and Uro-11 transcripts were localized in the ectoplasm of uncleaved zygotes and mostly entered the ectoderm cells during cleavage. The Uro-2 gene appears to produce only maternal transcripts. In contrast, the Uro-11 gene may also produce zygotic transcripts, which accumulate between gastrulation and neurulation in posterior epidermis, neural and tail muscle cells. Zygotic expression of the Uro-11 gene was not detected in embryos of the anural species. The deduced amino acid sequences of the Uro-2 and Uro-11 cDNAs suggest that they encode novel basic proteins with distinctive structural features. The predicted Uro-2 protein contains a leucine zipper motif, suggesting that it may dimerize with another protein. The predicted Uro-11 protein contains a nuclear localization signal, a region with similarity to part of the DNA-binding motif in the bacterial histone-like HU and IHF proteins, 12 repeats of the proposed DNA-binding motif S(T)PXX, and a potential zinc finger of the C6 or C6H2 class, suggesting that it may be a DNA-binding protein. The Uro-2 and Uro-11 proteins are candidates for regulatory factors involved in the evolutionary transition from urodele to anural development.
Nkx-2.5: a novel murine homeobox gene expressed in early heart progenitor cells and their myogenic descendants
Authors: Lints Thierry J. , Parsons Linda M. , Hartley Lynne , Lyons Ian , Harvey Richard P. 
Published: April 2021

ABSTRACT
We have isolated two murine homeobox genes, Nkx-2.5 and Nkx-2.6, that are new members of a sp sub-family of homeobox genes related to Drosophila NK2, NK3 and NK4/msh-2. In this paper, we focus on the Nkx-2.5 gene and its expression pattern during post-implantation development. Nkx-2.5 transcripts are first detected at early headfold stages in myocardiogenic progenitor cells. Expression preceeds the onset of myogenic differentiation, and continues in cardiomyocytes of embryonic, foetal and adult hearts. Transcripts are also detected in future pharyngeal endoderm, the tissue believed to produce the heart inducer. Expression in endoderm is only found laterally, where it is in direct apposition to promyocardium, suggesting an interaction between the two tissues. After foregut closure, Nkx-2.5 expression in endoderm is limited to the pharyngeal floor, dorsal to the developing heart tube. The thyroid primordium, a derivative of the pharyngeal floor, continues to express Nkx-2.5 after transcript levels diminish in the rest of the pharynx. Nkx-2.5 transcripts are also detected in lingual muscle, spleen and stomach.
The expression data implicate Nkx-2.5 in commitment to and/or differentiation of the myocardial lineage. The data further demonstrate that cardiogenic progenitors can be distinguished at a molecular level by late gastrulation. Nkx-2.5 expression will therefore be a valuable marker in the analysis of mesoderm development and an early entry point for dissection of the molecular basis of myogenesis in the heart.
Segment polarity gene interactions modulate epidermal patterning in Drosophila embryos
Authors: Bejsovec Amy , Wieschaus Eric 
Published: April 2021

ABSTRACT
Each segment of a Drosophila larva shows a precisely organized pattern of cuticular structures, indicating diverse cellular identities in the underlying epidermis. Mutations in the segment polarity genes alter the cuticle pattern secreted by the epidermal cells; these mutant patterns provide clues about the role that each gene product plays in the development of wild-type epidermal pattern. We have analyzed embryos that are multiply mutant for five key patterning genes: wingless, patched, engrailed, naked and hedgehog. Our results indicate that wild-type activity of these five segment polarity genes can account for most of the ventral pattern elements and that their gene products interact extensively to specify the diverse cellular identities within the epidermis. Two pattern elements can be correlated with individual gene action: wingless is required for formation of naked cuticle and engrailed is required for formation of the first row of denticles in each abdominal denticle belt. The remaining cell types can be produced by different combinations of the five gene activities. wingless activity generates the diversity of cell types within the segment, but each specific cell identity depends on the activity of patched, engrailed, naked and hedgehog. These molecules modulate the distribution and interpretation of wingless signalling activity in the ventral epidermal cells and, in addition, each can contribute to pattern through a pathway independent of the wingless signalling pathway
Expression of the chicken GATA factor family during early erythroid development and differentiation
Authors: Leonard Mark W. , Lim Kim-Chew , Engel James Douglas 
Published: April 2021

ABSTRACT
The DNA motif WGATAR has been identified within transcriptional regulatory domains of globin and other erythroid-specific genes and the activator proteins that bind to this regulatory element, the GATA factors, belong to a multi-gene family that is expressed in chicken erythroid cells. Here we show that, as in chickens, multiple members of the GATA factor family are expressed in human and murine erythroid cells. During the early stages of chicken embryogenesis (well before blood island formation), each of the GATA family members is transcribed with a unique temporal and spatial pattern. In the primitive erythroid lineage, tran-scription of the embryonic -globin gene parallels GATA-1 expression while the switch to -globin transcription in definitive erythroid cells is directly preceded by a pronounced increase in GATA-3 accumulation. The timing and pattern of expression of these different mRNAs during avian erythroid development and differentiation suggests that temporally regulated changes in GATA factor expression are required for vertebrate hematopoiesis.
Prestalk cells in monolayer cultures exhibit two distinct modes of cellulose synthesis during stalk cell differentiation in Dictyostelium
Authors: Blanton R. L. 
Published: April 2021

ABSTRACT
Stalk formation in Dictyostelium discoideum involves the synthesis of a stalk tube by the prestalk cell population and stalk cell walls by the individual prestalk cells. Cellulose is a major structural component of the stalk tube and stalk cell walls. The DIF-deficient strain HM44 was used to study the events of stalk formation in monolayer cultures. The induction of cellulose synthase activity was shown to require both DIF and cAMP. Microscopical observations of monolayer cultures using the cellulose-indicating fluorochrome Tinopal LPW demonstrated the presence in these cultures of two cellulose-containing materials: the stalk cell walls and an intercellular material found between cells and around cell clumps. The synthesis of intercellular material precedes that of stalk cell walls in induced cultures. Cells committed to stalk cell formation were delayed in doing so if they were switched to medium containing cAMP but no DIF. During this delay the cells synthesized large quantities of the intercellular material. The intercellular material was shown to be microfibrillar, was sensitive to cellulase, and labelled with a colloidal gold-conjugated cellulase. The intercellular material may have the same mode of cellulose synthesis as that involved in stalk tube formation. If so, that mode would be favored by DIF and cAMP in combination, whereas the cellulose synthesis involved in stalk cell wall formation would be DIF-dependent but delayed or repressed by cAMP.
Expression of Drosophila glass protein and evidence for negative regulation of its activity in non-neuronal cells by another DNA-binding protein
Authors: Ellis Michael C. , O’Neill Elizabeth M. , Rubin Gerald M. 
Published: April 2021

ABSTRACT
The glass gene encodes a DNA-binding zinc-finger protein required for the development of Drosophila photoreceptor cells and which appears to regulate a number of genes specifically expressed in photoreceptors. We have generated monoclonal antibodies to Glass and used them to examine Glass distribution during development. Glass is expressed in all cell types of the developing eye and in all other organs that contain photoreceptor cells in Drosophila, including a small number of cells in the brain. We altered the normal pattern of glass expression by placing the gene under the control of the hsp70 promoter. Our results suggest that nonphotoreceptor cells are restricted in their response to Glass expression. In an effort to discover the mechanism of this restriction, we examined the expression of a number of reporter gene constructs. Our results suggest that nonsensory cells are unable to express certain reporter constructs in response to Glass expression because another DNA-binding factor represses Glass activity in nonsensory cells.
Constitutive expression of a somatic heat-inducible hsp70 gene during amphibian oogenesis
Authors: Billoud Bernard , Rodriguez-Martin Maria-Luz , Berard Line , Moreau Nicole , Laine Marie-Christine , Angelier Nicole 
Published: April 2021

ABSTRACT
We isolated and characterized a sequence coding for heat-shock protein 70 (HSP70) of the amphibian Pleu-rodeles waltl. Results from S1 nuclease protection assays led us to conclude that an hsp70 gene, strictly inducible in somatic cells during heat shock, is constitutively active during oogenesis. By quantitative northern and western blot analysis, we showed that both hsp70 mRNA and HSP70-related protein levels increased in oocytes from stage II to stage VI under physiological conditions. Furthermore, by in situ hybridization to the nascent transcripts of lampbrush chromosome loops, we provided evidence for a clear-cut relationship between this increase in hsp70 mRNA and transcriptional activity during the lampbrush stage of oogenesis. These results strongly suggest that hsp70 genes are actively transcribed throughout oogenesis. HSP70-related proteins localized in the cytoplasm of young oocytes are progressively transferred to the nucleus in the course of oogenesis and preferentially accumulated in the nuclei of some stage VI oocytes.
Expression of the c-ret proto-oncogene during mouse embryogenesis
Authors: Pachnis Vassilis , Mankoo Baljinder , Costantini Frank 
Published: April 2021

ABSTRACT
The c-ret proto-oncogene encodes a receptor tyrosine kinase whose normal function has yet to be determined. To begin to investigate the potential role of this gene in vertebrate development, we have isolated cDNA clones representing the murine c-ret gene, and have analyzed the pattern of expression during mouse embryogenesis, using northern blotting, in situ hybridization to histological sections and whole-mount hybridization histochemistry. c-ret transcripts were detected beginning at day 8.5 of embryogenesis, and were observed in a number of cell lineages in the developing peripheral and central nervous systems, as well as in the excretory system. In the cranial region at day 8.5-9.5, c-ret mRNA was restricted to a population of neural crest cells migrating from rhombomere 4 and forming the anlage of the facioacoustic ganglion, as well as to a closely associated domain of surface ectoderm and pharyngeal endoderm. At later stages (10.5–14.5 days), c-ret mRNA was observed in all cranial ganglia. In the peripheral nervous system of the trunk, c-ret was expressed in the autonomic ganglia and in subsets of cells in the dorsal root ganglia. In the enteric nervous system, c-ret was expressed in the presumptive enteric neuroblasts of the vagal crest (day 9.0–11.5), and in the myenteric ganglia of the gut (day 13.5–14.5). c-ret mRNA was observed in several regions of the central nervous system, including the undifferentiated neuroepithelial cells of the ventral neural tube (8.5 days), the motor neurons in the spinal cord and the hindbrain (10.5–14.5 days), the embryonic neuroretina (day 13.5) and the layers of the postnatal retina containing ganglion, amacrine and horizontal cells. Outside the nervous system, c-ret was expressed in the nephric (Wolffian) duct at day 8.5–10.5, the ureteric bud epithelium (but not the surrounding metanephric mesenchyme) at day 11.0–11.5, and the growing tips of the renal collecting ducts (but not the previously formed, subcortical portions of the collecting ducts, or the mesenchyme-derived renal vesicles) at day 13.5–17.5. Our results suggest that the c-ret gene may encode the receptor for a factor involved in the proliferation, migration, differentiation or survival of a variety of neuronal cell lineages, as well as in inductive interactions during organogenesis of the kidney.
The developing organ of Corti contains retinoic acid and forms supernumerary hair cells in response to exogenous retinoic acid in culture
Authors: Kelley Matthew W. , Xu Xiao-Mei , Wagner Michael A. , Warchol Mark E. , Corwin Jeffrey T. 
Published: April 2021

ABSTRACT
The mammalian organ of Corti has one of the most highly ordered patterns of cells in any vertebrate sensory epithelium. A single row of inner hair cells and three or four rows of outer hair cells extend along its length. The factors that regulate the formation of this strict pattern are unknown. In order to determine whether retinoic acid plays a role during the development of the organ of Corti, exogenous retinoic acid was added to embryonic mouse cochleae in vitro. Exogenous retinoic acid significantly increased the number of cells that developed as hair cells and resulted in large regions of supernumerary hair cells and supporting cells containing two rows of inner hair cells and up to 11 rows of outer hair cells. The effects of retinoic acid were dependent on concentration and on the timing of its addition.
Western blot analysis indicated that cellular retinoic acid binding protein (CRABP) was present in the sensory epithelium of the embryonic cochlea. The amount of CRABP apparently increased between embryonic day 14 and postnatal day 1, but CRABP was not detectable in sensory epithelia from adults. A retinoic acid reporter cell line was used to demonstrate that retinoic acid was also present in the developing organ of Corti between embryonic day 14 and postnatal day 1, and was also present in adult cochleae at least in the vicinity of the modiolus. These results suggest that retinoic acid is involved in the normal development of the organ of Corti and that the effect of retinoic acid may be to induce a population of prosensory cells to become competent to differentiate as hair cells and supporting cells.