bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development ofDrosophilalarval sensory organs: spatiotemporal pattern of sensory neurones, peripheral axonal pathways and sensilla differentiation
Authors: Hartenstein Volker 
Published: April 2021

AbstractThe sensilla of Drosophila larval thoracic and abdominal segments appear in a constant temporal sequence during stage 13/14 (9 ·5 –11 ·5 h) of embryonic development. Those sensilla innervated by more than one dendrite (basiconical sensilla, chordotonal organs, some of the trichoid sensilla and campaniform sensilla) appear earlier than sensilla innervated by a single dendrite (majority of trichoid sensilla and campaniform sensilla). Furthermore, a dorsoventrally directed gradient underlies the sequence in which sensilla of a given type appear. Sensory axons are emitted in the same sequence. Thus, axons of the polyinnervated sensilla appear first. Together with a distinct set of efferent axons they form ‘pioneer tracts’ of the two fascicles of the segmental nerves. Cytodifferentiation of the sensillum cells resembles the development of larval epidermal cells in many aspects. Thus, the sheath processes formed by sensillum accessory cells and the axons formed by sensory neurones develop from processes transiently formed by all cells. During the phase of cuticle secretion, apical portions of the presumptive accessory cells are modified to form the cuticular apparatus responsible for receiving the sensory stimuli. Finally, two sets of subepidermally located cells which differ with respect to their morphology and, probably, their origin envelop somata and axons of the sensory neurones.
Membrane glycoproteins immunologically related to the human insulin receptor are associated with presumptive neuronal territories and developing neurones inDrosophila melanogaster
Authors: Piovant Michel , Léna Philippe 
Published: April 2021

AbstractWe have generated a monoclonal antibody (Mab E1C) that recognizes the differentiated nervous system in Drosophila embryos. At the cellular blastoderm stage, Mab E1C behaves as a general ectodermal marker but, in subsequent stages, it also labels the mesoderm. As neurogenesis takes place, staining increases within the neuromeres and is almost exclusively restricted to the nervous tissue by the time neuronal differentiation is completed. In third instar larvae, Mab E1C stains the central nervous system (CNS) as well as the imaginai discs which display a staining pattern related to their degree of neuronal differentiation. No labelling can be detected in adult brains or ovaries. Western blots are consistent with this developmental profile and allow the characterization of a major glycoprotein of 135 × 103Mr (135K) which cosediments with a membrane fraction prepared from embryos. Additional glycoproteins (100K and 80K) are extracted from embryo homogenates by immunoaffinity procedures. In larvae, the 100K polypeptide is not detected. The properties of the 135K and 100K components are highly reminiscent of the molecular pattern of the Drosophila insulin receptor homologue (Petruzzelli et al. (1985)J. biol. Chem. 250, 16072 – 16075). It is shown that a Mab directed against the human insulin receptor stains the same cells as Mab E1C in imaginai discs and in the CNS. Moreover, this Mab cross-reacts with the 135K and 100K components of the embryonic antigen E1C.
Bombesin and other growth factors activate cell proliferation in chick embryo otic vesicles in culture
Authors: Represa J. J. , Miner Cristina , Barbosa E. , Giraldez F. 
Published: April 2021

AbstractThe ability of the mitogenic peptide bombesin and other growth factors to trigger and support early development of the inner ear was studied on chick embryo otocysts in culture. The normal pattern of development was preserved in cultured otic vesicles in the presence of 20 % fetal calf serum in the medium. Differentiation proceeded from stage 18 to 22 during the first 24 h and further to stage 24 in 48 h. Estimates of cell number and mitotic rates revealed a distinct period of proliferative growth which was maximum at the 24 h period of incubation. This was coincident with a high rate of DNA synthesis as measured by the acidprecipitable incorporation of [3H]thymidine. Development could be arrested by deprivation of serum during 24 h. It could then be reactivated by readmission of serum to proceed with the normal pattern of morphological differentiation and cell proliferation. Bombesin (100 nM) was able to reactivate development in growth-arrested vesicles. Its effect was dose-dependent, saturable and potentiated by insulin (5 μg ml-1) which was ineffective if used alone. When associated with insulin, bombesin carried differentiation to stage 21 and stimulated mitotic activity above the level of serum as judged from estimates of cell number and [3H]thymidine uptake. EGF and PDGF were also effective in reinitiating development although their potency was smaller than bombesin. The reactivation by serum or bombesin was blocked by amiloride. The results show that (1) the otic vesicle can provide a useful model for studying the mechanisms that control proliferative growth and differentiation during normal development and (2) bombesin and other growth factors are able to activate growth in embryonic developing tissues.
Patterns of N-CAM expression during myogenesis in Xenopus laevis
Authors: Kay B. K. , Schwartz L. M. , Rutishauser U. , Qiu T. H. , Peng H. B. 
Published: April 2021

Abstract
The neural cell adhesion molecule (N-CAM) is seen in the membrane of nerves and muscles from several vertebrate species. Using indirect immunofluorescence, we have examined the expression of this protein during embryonic and postembryonic myogenesis in the African clawed frog, Xenopus laevis. While good staining for N-CAM was seen in neuronal tissues at all stages examined, no staining of embryonic muscle was observed, including both mononucleated and polynucleated myoblasts. In contrast, limb muscles formed at metamorphosis showed strong expression of N-CAM. The developing limb muscles eventually lose their N-CAM, but will reexpress it dramatically when denervated. These observations suggest that myogenesis programs executed at different stages of development can display distinct patterns of N-CAM expression.
Normal embryogenesis occurs in starfish eggs induced to mature by microinjection of cytoplasm containing maturation-promoting factor (MPF)
Authors: Picard André , Labbé Jean-Claude , Dorée Marcel 
Published: April 2021

Abstract
Oocytes arrested at the first meiotic prophase re-initiate meiosis under the influence of a variety of signals, including hormones. These signals are thought to act indirectly to produce a maturation-promoting factor (MPF) which triggers transition to the metaphase. We show here that non-hormone-stimulated starfish oocytes, induced to mature by microinjection of MPF-containing cytosol taken from hormone-stimulated oocytes, produce normal bipin-naria larvae once fertilized.
The same result was obtained when donor oocytes were induced to mature by microinjecting heterologous MPF partially purified from amphibian oocytes. These results argue against the hypothesis that maturation events essential for normal embryo-genesis occur independently of MPF, at least in starfish.
The expression of rat homeobox-containing genes is developmentally regulated and tissue specific
Authors: Falzon Miriam , Chung Su Yun 
Published: April 2021

Abstract
Seven rat homeobox-containing sequences have been isolated by screening a genomic library with a probe derived from a Drosophila antennapedia cDNA clone. The characterization of two of these homeobox-containing clones has been described (Falzon, M., Sanderson, N. D. and Chung, S. Y. (1987) Gene 54, 23 – 32). Sequence analysis of the remaining five homeobox regions reveals a 180 bp domain sharing 70 – 95 % identity at the amino acid level with the homeodomain from the Drosophila antennapedia gene and with the homeodomains from other metazoan species. Genomic blot analysis shows that each of the homeobox-containing DNA segments is probably present in a single copy per haploid genome. Northern blot analysis of RNA transcripts indicates that the rat homeobox-containing sequences are expressed during embryogenesis and in newborn and adult tissues in a tissue-specific manner; RNA expression is predominantly detected in spinal cord and kidney. Moreover, the pattern of RNA transcripts observed is distinct for each homeobox sequence, indicating differential regulation. Among the seven rat homeobox-containing sequences, the flanking sequences of five of the clones have no obvious sequence similarity with previously published sequences of homeobox-containing genes from other species. Two of the rat clones have been identified as potential homologues to mouse homeobox-containing sequences. For both pairs, a high degree of amino acid conservation (&gt;95 %) is oberved within the homeodomain and its immediate flanking regions between the putative homologous genes in mouse and rat. This strengthens the assertion that some of the mammalian homeobox-containing genes encode highly conserved proteins and may serve important biological functions.
Identification of a component ofDrosophilapolar granules
Authors: Hay Bruce , Ackerman Larry , Barbel Sandra , Jan Lily Y. , Jan Yuh Nung 
Published: April 2021

AbstractInformation necessary for the formation of pole cells, precursors of the germ line, is provided maternally and localized to the posterior pole of the Drosophila egg. The maternal origin and posterior localization of polar granules suggest that they may be associated with pole cell determinants. We have generated an antibody (Mab46Fll) against polar granules. In oocytes and early embryos, the Mab46Fll antigen is sharply localized to the posterior embryonic pole. In pole cells, it becomes associated with nuclear bodies within, and nuage around, the nucleus. Immunoreactivity remains associated with cells of the germ line throughout the life cycle of both males and females. This antibody recognizes a 72–74 ×103Mr protein and is useful both as a pole cell lineage marker and in biochemical studies of polar granules.
Detection of spatially- and stage-specific proteins in extracts from single embryos of the domesticated carrot
Authors: Racusen R. H. , Schiavone F. M. 
Published: April 2021

Abstract
Single embryos, representing each of four distinct morphological stages, were selected from cultures of the domesticated carrot for analysis of total [3SS]methionine-labelled proteins. Following exposure to radiolabel for 12 to 18 h, embryos were individually disrupted in a 3 mm diameter, precisely-matched, plastic mortar and pestle. Radiolabelled proteins extracted by this procedure were separated by two-dimensional electrophoresis procedures, consisting of isoelectric focusing in 1 mm tubes, followed by SDS-PAGE in a small slab gel. Comparisons of autoradiographs of these gels revealed that the levels of a number of proteins were modulated during the conversion of disordered callus cells into maturing embryos. In addition, miniature surgical techniques were used to separate the apex (cotyledon end) from the base (root end) of late-stage embryos, for extraction of proteins and analysis of spatial differences in protein distribution. About five proteins in extracts from each section were observed to be synthesized at different rates in the two halves, indicating that there are molecular correlates for early polarized growth. About half of the proteins, whose appearances were unique to apical and basal sections of embryos, were also observed to fluctuate in comparisons of autoradiographs of two-dimensional protein separations from embryos at different developmental stages.
Patterns of junctional communication during development of the early amphibian embryo
Authors: Guthrie Sarah , Turin Luca , Warner Anne 
Published: April 2021

Abstract
Cell-cell communication through gap junctions was examined in Xenopus laevis embryos between the 16cell and early blastula stages using Lucifer Yellow, Fluorescein, lead EDTA and dicyanoargentate as probes of junctional permeability. Injections were made into cells whose position was identified with respect to the primary cleavage axis and the grey crescent. FITC dextrans revealed cytoplasmic bridges between the injected cell and its sister only. In the animal pole at the 16-cell stage at the future dorsal side of the embryo, Lucifer Yellow was frequently and extensively transferred between cells through gap junctions. At the future ventral side gap junctional transfer of Lucifer Yellow was significantly less frequent and less extensive. The asymmetry of transfer between future dorsal and ventral sides of the animal pole was more marked at the 32-cell stage. In the vegetal pole also at the 32-cell stage, a dorsoventral difference in junctional permeability to Lucifer Yellow was observed. At the 64-cell stage the transfer of Lucifer Yellow was relatively frequent between cells lying in the same radial segment in the animal pole; transfer into cells outside each segment was infrequent, except at the grey crescent. At the 128-cell stage, Lucifer transfer between future dorsal or future ventral cells in the equatorial region was infrequent. A high incidence of transfer was restored at the future dorsal side at the 256-cell stage. At the 32-cell stage, fluorescein was infrequently transferred between animal pole cells although lead EDTA moved from cell to cell with high, comparable frequency in future dorsal and ventral regions. Dicyanoargentate always transferred extensively, both at the 32- and 64-cell stages. Treatment of embryos with methylamine raised intracellular pH by 015 units, increased the electrical conductance of the gap junction and produced a 10fold increase in the frequency of Lucifer Yellow transfer through gap junctions in future ventral regions of the animal pole at the 32-cell stage.
Cell proliferation and early differentiation during embryonic development and metamorphosis ofHydractinia echinata
Authors: Plickert G. , Kroiher M. , Munck A. 
Published: April 2021

AbstractThe early embryonic development of Hydractinia lasts about 2-5 days until the developing planula larva acquires competence for metamorphosis. Most embryonic cells stop cycling on reaching the larval stage. In older larvae of Hydractinia, cells that are still proliferating occur exclusively in the endoderm in a typical distribution along the longitudinal axis. During metamorphosis, proliferation activity begins again. The number of S-phase cells has increased by the 9th hour after induction of metamorphosis. Proliferative activity starts in the middle gastric region and in basal parts of primary polyps. Tentacles and stolon tips are always free of replicating cells.
Theoretical aspects of stripe formation in relation to Drosophila segmentation
Authors: Lacalli T. C. , Wilkinson D. A. , Harrison L. G. 
Published: April 2021

ABSTRACT
Many aspects of Drosophila segmentation can be discussed in one-dimensional terms as a linear pattern of repeated elements or cell states. But the initial metameric pattern seen in the expression of pair-rule genes is fully two-dimensional, i.e. a pattern of stripes. Several lines of evidence suggest a kinetic mechanism acting globally during the syncytial blastoderm stage may be responsible for generating this pattern. The requirement that the mechanism should produce stripes, not spots or some other periodic pattern, imposes preconditions on this act, namely (1) sharp anterior and posterior boundaries that delimit the pattern-forming region, and (2) an axial asymmetrizing influence in the form of an anteroposterior gradient. Models for Drosophila segmentation generally rely on the gradient to provide positional information in the form of concentration thresholds that cue downstream elements of a hierarchical control system. This imposes restrictions on how such models cope with experimental disturbances to the gradient. A shallower gradient, for example, means fewer pattern elements. This need not be the case if the gradient acts through a kinetic mechanism like reaction-diffusion that involves the whole system. It is then the overall direction of the gradient that is important rather than specific concentration values. We illustrate this and some related properties of reaction-diffusion models with computations using a specific model, a variant of the Brusselator, and discuss features that appear to be both relevant to Drosophila and of general significance: (1) sharp boundaries and gradients can together orient and stabilize multistripe patterns and (2) boundaries, including fixed boundaries established within a pattern-forming region, may be important for controlling the subdivision of large pattern domains into smaller elements as is observed in the expression of pair-rule genes.
The effect of epidermal growth factor, insulin and transferrin on the growth-promoting properties of serum depleted by repeated culture of postimplantation rat embryos
Authors: Pratten M. K. , Brooke A. M. , Broome S. C. , Beck F. 
Published: April 2021

ABSTRACTHomologous serum, when repeatedly used for the culture of postimplantation rat embryos, rapidly loses its capacity to support growth and development. Replenishment of the ‘exhausted’ serum with glucose and vitamins (MEM vitamin concentrate -Flow Laboratories) together with gentle dialysis to remove small molecular weight toxic metabolites (lactate etc) fails to restore the growth-promoting properties of the serum. This suggests that ‘recycled’ serum has been depleted of specific growth-promoting factors. Such serum that has been subjected to dialysis can be completely replenished by addition of 30 % normal rat serum. It is therefore probable that the growth promoters are originally present at very low concentrations and become rate limiting when serum is recycled. Many growth factors and hormones fall into this category and it is likely that a considerable number are involved when serum is ‘exhausted’ by repeated use. When insulin, epidermal growth factor or rat transferrin are added to dialysed ‘exhausted’ serum each effects a partial restoration of growth of rat embryos.
Tissue effects on the expression of serotonin, tyrosine hydroxylase and GABA in cultures of neurogenic cells from the neuraxis and branchial arches
Authors: Mackey Harris M. , Payette Robert F. , Gershon Michael D. 
Published: April 2021

ABSTRACT
The phenotypically diverse neurones of the enteric nervous system are developmentally derived from precursors that migrate to the bowel from the vagal and sacral regions of the neuraxis. In order to gain insight into the generation of enteric neuronal diversity, we examined the expression of serotonin (5-HT), tyrosine hydroxylase and GABA in vitro. In the mature avian intestine, intrinsic neurones contain 5- HT or GABA but not tyrosine hydroxylase. These markers were demonstrated immunocytochemically, singly or simultaneously. All three phenotypic markers developed in cultures of cranial, vagal or truncal neural crest when the cultures were grown in enriched medium, containing horse serum and chick embryo extract; however, 5-HT and GABA, but not tyrosine hydroxylase-immunoreactive cells, also developed in cultures that were grown in partially defined medium. Tyrosine hydroxylase immunoreactivity was seen when partially defined medium was supplemented with nerve growth factor (NGF). Cultures of branchial arches (III and IV) contained cells that displayed tyrosine hydroxylase immunoreactivity, but not that of 5-HT- or GABA-; however, 5-HT immunoreactivity was seen when branchial arches were cocultured with aneuronal hindgut (from 4-day chick embryos). Cultures of cells from chick gut dissociated at 7 days contained tyrosine hydroxylase as well as 5- HT and GABA immunoreactivities; however, no cultures of bowel dissociated at 8 days or later expressed tyrosine hydroxylase immunoreactivity. When neur- axial cells were cocultured with branchial arches or heart instead of gut, no 5-HT-immunoreactive cells were seen; nevertheless, the further addition of explants of gut to the heart/crest cocultures did permit the expression of 5-HT immunoreactivity. These results are consistent with the hypotheses that precursors with the potential to give rise to cells that express 5-HT, GABA and tyrosine hydroxylase are found at several levels of the neuraxis; however, the ability to express these phenotypes may be suppressed either while the crest cells are migrating (for example, 5-HT and GABA expression by crest cells passing through the branchial arches) or in their final destination (for example, tyrosine hydroxylase in the gut). This suppression may be transient and reversed by the microenvironment of the target organs.
Monitoring positional information during oogenesis in adultDrosophila
Authors: Fasano Laurent , Kerridge Stephen 
Published: April 2021

ABSTRACTAbout 184 P[lac,ry+]A insertions (O’Kane & Gehring, 1987) have been incorporated into the genome via P element-mediated transformation. The temporal-spatial localization of β-galactosidase, synthesized by these insertions during oogenesis, is described. 32 % present control levels of endogenous β-galactosidase expression and 68 % show novel patterns. 13 % of the insertions are germline-specific; 33%, follicle-cell-specific; 20 % are expressed in both germ line and follicle cells; and 2%, specific to the germarium. Several lines exhibit strict temporal-spatial localiz ations of β-galactosidase; notably those expressed in specific populations of follicle cells. The results are discussed with respect to some of the positional information encoded in the genome to which the insertions respond, the use of the insertions as markers for cell differentiation and the potential of the technique for isolating new genes involved in egg production.
A gene with sequence similarity to Drosophila engrailed is expressed during the development of the neural tube and vertebrae in the mouse
Authors: Davidson Duncan , Graham Elizabeth , Sime Christina , Hill Robert 
Published: April 2021

ABSTRACT
The mouse genes En-1 and En-2 display sequence similarity, in and around the homeobox region, to the engrailed family in Drosophila. This paper describes their pattern of expression in the 12 ·5-day mouse embryo as determined by in situ hybridization.
En-2 is expressed in a subset of cells expressing En-1. Both genes are expressed in the developing midbrain and its junction with the hindbrain. In addition, En-1 is expressed in the floor of the hindbrain, a restricted ventrolateral segment of the neural tube throughout the trunk and anterior part of the tail, the dermatome of tail somites, the centrum and costal processes in developing vertebrae, a restricted region of facial mesenchyme and the limb-bud ectoderm. Supplementary studies of 9 ·5-day and 10 ·-5-day embryos showed that the same pattern of expression pertained in the neural tube, but that expression in the somites is at first confined to the dermatome and later found at a low level in restricted sclerotomal regions. Both genes are expressed in restricted domains which do not cross tissue-type boundaries. In several instances, however, boundaries of expression lie within morphologically undifferentiated tissue.
These results suggest that En-1 and En-2 may be involved in the establishment or maintenance of the spatial integrity of specific domains within developing tissues.