bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of genes that interact with glp-1, a gene required for inductive cell interactions in Caenorhabditis elegans
Authors: Maine Eleanor M. , Kimble Judith 
Published: April 2021

Abstract
The glp-1 gene functions in two inductive cellular interactions and in development of the embryonic hypodermis of C. elegans. We have isolated six mutations as recessive suppressors of temperature-sensitive (ts) mutations of glp-1. By mapping and complementation tests, we found that these suppressors are mutations of known dumpy (dpy) genes; dpy genes are required for development of normal body shape. Based on this result, we asked whether mutations previously isolated in screens for mutants defective in body shape could also suppress glp-1 (ts). From these tests, we learned that unselected mutations of eight genes required for normal C. elegans morphogenesis, including the four already identified, suppress glp-l(ts). All of these suppressors rescue all three mutant phenotypes of glp-l(ts) (defects in embryonic induction of pharyngeal tissue, in embryonic hypodermis development, and in induction of germline proliferation). However, they do not rescue putative glp-1 null mutants and therefore do not bypass the requirement for glp-1 in development. In the light of current ideas about the molecular nature of the glp-1 and suppressor gene products, we propose an interaction between the glp-1 protein and components of the extracellular matrix and speculate that this interaction may impose spatial constraints on the decision between mitosis and meiosis in the germline.
l(1)pole hole is required maternally for pattern formation in the terminal regions of the embryo
Authors: Ambrosio Linda , Mahowald Anthony P. , Perrimon Norbert 
Published: April 2021

Abstract
Maternal expression of the l(l)pole hole (l(l)ph) gene product is required for the development of the Drosophila embryo. When maternal l(l)ph+ activity is absent, alterations in the embryonic fate map occur as visualized by the expression of segmentation genes fushitarazu and engrailed. If both maternal and zygotic activity is absent, embryos degenerate around 7h of development. If only maternal activity is missing, embryos complete embryogenesis and show deletions of both anterior and posterior structures. Anteriorly, structures originating from labral and acron head regions are missing. Posteriorly, abdominal segments A8, 9 and 10, the telson and the proctodeum are missing. Similar pattern deletions are observed in embryos derived from the terminal class of female sterile mutations. Thus, the maternal 1(1)ph+ gene product is required for the establishment of cell identities at the anterior and posterior poles of the Drosophila embryo.
The effects of phorbol ester on mouse blastomeres: a role for protein kinase C in compaction?
Authors: Bloom Theodora L. 
Published: April 2021

Abstract
The effects of phorbol myristate acetate (PMA) and other activators of protein kinase C on the cytoskeletal organization of mouse oocytes and early embryos have been examined. The effects observed depended on the developmental stage on exposure to PMA. PMA had little effect on the cytoskeletal or microvillous organization of unfertilized oocytes. Interphase cells from embryos prior to compaction showed limited disruption and loss of microvilli when exposed to PMA and foci of polymerized actin remained visible in the cytocortex of embryos up to the early 8-cell stage. When compacted late 8-cell embryos were exposed to PMA, most microvilli were lost and little polymerized actin remained in the cytocortex. PMA also caused loss of microtubules from compact 8-cell embryos under some experimental conditions. Intercellular flattening was both prevented and reversed. The relevance of these observations to the rearrangement of cell-cell contacts and cytoskeletal organization seen during compaction at the 8-cell stage is discussed and a possible role for protein kinase C in the generation of cell polarity proposed.
Analysis of competence: receptors for fibroblast growth factor in early Xenopus embryos
Authors: Gillespie L. L. , Paterno G. D. , Slack J. M. W. 
Published: April 2021

Abstract
Xenopus ectodermal cells have previously been shown to respond to acidic and basic FGF by differentiating into mesodermal tissue. In the present study, ectodermal explants from Xenopus blastulae were shown to have high affinity binding sites for 125I-aFGF (Kd = l·4× 10−10M). The total number of sites, determined by Scatchard analysis, was 3× 108 per explant (surface area of approximately 1mm2). Two putative receptors of relative molecular mass 130 000 and 140 000 were identified by chemical crosslinking to 125I-aFGF. Both acidic and basic FGF, but not TGFβ2, could compete for affinity labelling of these bands. The receptor density at the cell surface parallels the developmental competence of Xenopus animal pole cells to respond to FGF. Receptors are present at highest density in the marginal zone but are not restricted to cells in this region.
fushi tarazu protein expression in the cellular blastoderm of Drosophila detected using a novel imaging technique
Authors: Karr Timothy L. , Kornberg Thomas B. 
Published: April 2021

Abstract
The fushi tarazu (ftz) gene is essential for segmentation of the Drosophila embryo. This requirement is reflected at the cellular blastoderm stage of embryogenesis by seven transverse stripes of ftz expression. These stripes correspond to the missing segments of ftz mutant embryos. We describe here novel intermediate patterns of ftz protein expression which were detected in younger embryos by using anti-ftz antibodies and a sensitive fluorescence/immunoperoxidase technique (‘filtered fluorescence imaging’, FFI). Striped patterns of ftz protein evolved continuously, and the different stripes appeared in an ordered sequence, involving both anterior-posterior (A/P) and dorsal-ventral (D/V) progressions. Comparison of these patterns of ftz protein with those of ftz RNA suggests that these novel aspects of the patterning process involve post-transcriptional regulation in addition to the transcriptional control known to be involved in expression of this gene.
Abnormal flowers and pattern formation in floral development
Authors: Meyerowitz Elliot M. , Smyth David R. , Bowman John L. 
Published: April 2021

ABSTRACT
“From our acquaintance with this abnormal metamorphosis, we are enabled to unveil the secrets that normal metamorphosis conceals from us, and to see distinctly what, from the regular course of development, we can only infer.”
- J. W. von Goethe (1790)
Characterization of proteins secreted by sheep oviduct epithelial cells and their function in embryonic development
Authors: Gandolfi F. , Brevini Tiziana A. L. , Richardson Louise , Brown C. R. , Moor R. M. 
Published: April 2021

ABSTRACT
The role in early development of proteins secreted by oviduct epithelial cells has been investigated. Secreted proteins devoid of serum contamination have been produced by the surgical removal and immediate incubation of oviduct cells in [3sS]methionine-containing medium. After electrophoretic separation, secreted polypeptides could be divided into those that were secreted uniformly throughout the oestrous cycle and a second class that showed a cyclical pattern of secretion. The first class of proteins represented a small proportion of total output whilst the predominant second class was composed mainly of polypeptides of Mr 92 and 46×103, respectively. Both of these polypeptide species, referred to as sheep oviduct proteins 92 and 46 (SOP 92, SOP 46), are detected only during the first 4 to 5 days after oestrus when the embryos are located in the oviduct. Oviduct cells collected at oestrus and maintained thereafter in culture secrete the same pattern of proteins and follow the same time course as their counterparts in vivo.
The interaction between the oviduct proteins and the developing embryo was studied firstly by determining whether any of the secreted proteins bound to the zona pellucida. The results of iodination studies showed that two polypeptides of MT 92 and 46×103, respectively, were bound to the zona pellucida of eggs removed from the oviduct but were absent from eggs that had not had contact with the oviduct epithelium. That these newly acquired proteins represent SOP 92 and 46 is suggested by their electrophoretic mobility and their ability to bind to the zona of follicular eggs when added in vitro and by the fact that they both disappear from the zonae of embryos after exit from the oviduct. The collection of unlabelled secreted proteins enabled us to produce a monoclonal antibody, which was used in the second series of experiments on oviduct-embryo interactions. The results confirmed that SOP 92 binds to the zona pellucida and moreover showed that this protein crosses the zona and becomes associated with the individual blastomeres of the developing embryo. These findings provide evidence that the mammalian oviduct probably plays a direct role in supporting embryonic development through specific polypeptides produced by its epithelium.
The small nuclear RNAs for pre-mRNA splicing are coordinately regulated during oocyte maturation and early embryogenesis in the mouse
Authors: Dean Wendy L. , Seufert Andrea C. , Schultz Gilbert A. , Prather Randall S. , Simerly Calvin , Schatten Gerald , Pilch Duane R. , Marzluff William F. 
Published: April 2021

ABSTRACT
The abundance and localization of snRNAs and snRNPs involved in processing and splicing of pre-mRNA has been studied during early mouse embryogenesis. The amount of U1, U2, U4, U5 and U6 RNA remains relatively constant between the postovulatory oocyte and 2-cell stage but increases three- to ten-fold in quantity between the 2-cell and blastocyst stages. Localization was examined by in situ hybridization with Ul, U2 and U6 riboprobes and immunofluorescence microscopy using a monoclonal antibody to snRNP antigens. The snRNAs and snRNPs are primarily localized to the germinal vesicle in the preovulatory oocyte but are released and diluted within the cytoplasm of the oocyte during germinal vesicle breakdown and meiotic maturation. They subsequently relocalize to both pronuclei following fertilization and the nuclei of the 2-cell embryo following the first cleavage division. Since the amount of snRNA is constant during the first cleavage, the small amount of pre-mRNA that is synthesized at the time of transcriptional activation in the 2-cell embryo may be spliced and processed by snRNPs of maternal origin.
Transcription of the Spec 1-like gene of Lytechinus is selectively inhibited in response to disruption of the extracellular matrix
Authors: Wessel Gary M. , Zhang Wei , Tomlinson Craig R. , Lennarz William J. , Klein William H. 
Published: April 2021

ABSTRACT
The influence of the extracellular matrix (ECM) on differential gene expression during sea urchin develop­ment was explored using cell-type-specific cDNA probes. The ECM of three species of sea urchins, Strongylocen- trotus purpuratus, Lytechinus variegatus and Lytechinus pictus, was disrupted with the lathrytic agent /5-amino- propionitrile (BAPN), which inhibits collagen deposition in the ECM and arrests gastrulation (Wessel & McClay, Devi Biol. 121: 149, 1987). The levels of several mRNAs (Spec 1, Spec 2, Cylla actin, Cyllla actin and collagen in S. purpuratus, and metallothionine, ubiquitin and LpS3 in L. pictus and L. variegatus) were compared in BAPN- treated and control embryos. These mRNAs accumu­lated normally during BAPN treatment, even though the embryos did not gastrulate. To determine if the ex­pression of any gene product is sensitive to ECM disruption, a differential cDNA screen compared poly (A+) RNA from BAPN-arrested and control embryos in Lytechinus. A cDNA clone was isolated from this screen that represented a 2Ί kb mRNA that did not accumulate during BAPN treatment. Removal of BAPN resulted in the accumulation of this transcript coincident with the onset of gastrulation. This cDNA clone encodes a L. variegatus homologue of LpSl, recently demonstrated to be an ancestral homologue of the aboral ectoderm- specific Spec 1-Spec 2 gene family in S. purpuratus. Nuclear run-on assays in L. pictus suggested that transcriptional activity of LpSl was selectively inhibited by BAPN treatment. Thus, although the accumulation of many gene products occurred independently of the embryonic collagenous matrix, the accumulation of LpSl and LvSl appeared to be mediated by the ECM.
Poly(A) shortening accompanies the activation of translation of five mRNAs during spermiogenesis in the mouse
Authors: Kleene Kenneth C. 
Published: April 2021

ABSTRACT
I have compared the quantity and the length of the poly(A) tracts of five haploid-expressed mRNAs in the polysomal and nonpolysomal fractions of round and elongating spermatids in mice: transition proteins 1 and 2, protamines 1 and 2, and an unidentified mRNA of about 1050 bases. Postmitochondrial supernatants of highly enriched populations of round and elongating spermatids (early and late haploid spermatogenic cells) were sedimented on sucrose gradients, and the size and amount of each mRNA in gradient fractions were analyzed in Northern blots. In round spermatids, all five mRNAs are restricted to the postpolysomal fractions, but in elongating spermatids about 30–40% of each mRNA is associated with the polysomes. The distribution of these mRNAs in sucrose gradients suggests that all five mRNAs are stored in a translationally repressed state in round and early elongating spermatids, and that they become translationally active in middle and late elongating spermatids. The translationally repressed forms of all five mRNAs are long and homogenous in size, whereas the polysomal forms are shorter and more heterogenous due to shortening of their poly (A) tracts. The relationship between translational activity and poly(A) size exemplified by these five mRNAs may be typical of mRNAs which are translationally repressed in round spermatids and translationally active in elongating spermatids.
Differential localization of villin and fimbrin during development of the mouse visceral endoderm and intestinal epithelium
Authors: Ezzell Robert M. , Chafel Mark M. , Matsudaira Paul T. 
Published: April 2021

ABSTRACT
The apical surface of transporting epithelia is specially modified to absorb nutrients efficiently by amplifying its surface area as microvilli. Each microvillus is supported by an underlying core of bundled actin filaments. Villin and fimbrin are two actin-binding proteins that bundle actin filaments in the intestine and kidney brush border epithelium. To better understand their function in the assembly of the cytoskeleton during epithelial differentiation, we examined the pattern of villin and fimbrin expression in the developing mouse using immunofluorescence and immunoelectron microscopy. Villin is first detected at day 5 in the primitive endoderm of the postimplantation embryo and is later restricted to the visceral endoderm. By day 8-5, villin becomes redistributed to the apical surface in the visceral endoderm, appearing in the gut at day 10 and concentrating in the apical cytoplasm of the differentiating intestinal epithelium 2–3 days later. In contrast, fimbrin is found in the oocyte and in all tissues of the early embryo. In both the visceral endoderm and gut epithelium, fimbrin concentrates at the apical surface 2–3 days after villin; this redistribution occurs when the visceral endoderm microvilli first contain organized microfilament bundles and when microvilli first begin to appear in the gut. These results suggest a common mechanism of assembly of the absorptive surface of two different tissues in the embryo and identify villin as a useful marker for the visceral endoderm.
Exclusionary dendritic interactions in the retina of the goldfish
Authors: Hitchcock Peter F. 
Published: April 2021

ABSTRACT
The retina of the goldfish grows throughout its life, in part, by the addition of new neurons at the margin. New ganglion cells added at the margin tend not to grow their dendritic arbors into the older, central retina. Hitchcock and Easter (J. Neurosci. 6, 1037-1050 (1986)) proposed that the dendrites of the new cells were prevented from extending centrally within the inner plexiform layer by the dendrites of the previous generations of cells. This proposal was tested by first killing existing ganglion cells with a retrogradely transported neurotoxin (propidium iodide; PI), and then observing the orientation and branching pattern of the dendrites of ganglion cells added subsequently at the margin. Dendrites were stained in retinal wholemounts by intracellular injections of Lucifer yellow. The data showed that cells added subsequent to the PI treatment grew their dendritic arbors preferentially toward central retina consistent with the hypothesis. It is concluded that interactions among adjacent ganglion cells regulates dendritic growth.
Glial interactions with neurons during Drosophila embryogenesis
Authors: Fredieu John R. , Mahowald Anthony P. 
Published: April 2021

ABSTRACT
A monoclonal antibody (Mab5B12) demonstrating speci-ficity for glial cells within the central and peripheral nervous systems of Drosophila has been used in combi-nation with neural-specific antibodies to study the early organization of the Drosophila embryo. The embryonic central nervous system of Drosophila contains cells within the ventral midline that are recognized by mono-clonal antibody 5B12. These cells are not recognized by either a polyclonal antiserum to horse radish peroxidase, which recognizes several antigens on the surface of Drosophila neurons, or Mab22C10, which recognizes an antigen specific to the peripheral nervous system. Mab5B12-positive cells lie dorsal both to the developing anterior and posterior commissures in each thoracic and abdominal segment and to the supraoesophageal com-missure. They ensheath these commissures in later stage embryos. Other Mab5B12-positive cells lie dorsolateral to the CNS and send processes laterally to the lateral sensilla during axonogenesis in the PNS. These cells surround the axons of the intersegmental and segmental nerves. Other cells that line the advancing ectoderm during dorsal closure and surround the anal pads also express the Mab5B12 antigen. Neuronal cell cultures derived from Drosophila gastrulae contain cells express-ing the Mab5B12 antigen. These cells can be found separate or in close association with neuronal clusters and their axons.
Mouse homeo-genes within a subfamily, Hox-1.4, -2.6 and -5.1, display similar anteroposterior domains of expression in the embryo, but show stage- and tissue-dependent differences in their regulation
Authors: Gaunt Stephen J. , Krumlauf Robb , Duboule Denis 
Published: April 2021

ABSTRACT
By use of in situ hybridization experiments on mouse embryo sections, we compare the transcript patterns of three homeo-genes from the Hox-1.4 subfamily (Hox- 1.4, -2.6 and -5.1). Genes within a subfamily are true homologues, present in the genome as a result of duplication of an ancestral homeo-gene cluster.
We show that Hox-1.4, -2.6 and -5.1 are similar, although apparently not identical, in the limits of their transcript domains along the anteroposterior axis. Within the prevertebral column of the day embryo, for example, the anterior boundary of transcripts for each of the three genes was most obvious at the junction of the first and second prevertebrae. Similarly, all three genes showed an anterior boundary of transcripts within the central nervous system that was located in the midmyelencephalon of the hindbrain. Both in the prevertebral column and hindbrain, however, Hox-2.6 and Hox-5.1 transcripts extended slightly anterior to the anteriormost limits detected for Hox-1.4.
In spite of close similarities in the positions of their transcript domains, Hox-1.4, -2.6 and -5.1 displayed striking stage- and tissue-dependent differences in the relative abundance of their transcripts. For example, Hox-5.1 transcripts were abundant within mesoderm and ectoderm of early stages ( and days), yet were detected only weakly in mesodermal components of the lung and stomach at days, and were apparently absent from these tissues at days. In contrast, Hox-1.4 and Hox-2.6 transcripts were relatively weakly detected at and days, but were abundant within the lung and stomach at days. Our findings suggest, but do not prove, that genes within the Hox-1.4 subfamily might be coordinately regulated in their expression.
We discuss the patterns of mouse homeo-gene expression now observed in terms of models originally devised for Drosophila. We also propose how our new findings may help to explain any selective advantage to the vertebrates of homeo-gene duplication to form subfamilies.
Regionalisation of the mouse embryonic ectoderm: allocation of prospective ectodermal tissues during gastrulation
Authors: Tam Patrick P. L. 
Published: April 2021

ABSTRACT
The regionalisation of cell fate in the embryonic ectoderm was studied by analyzing the distribution of graft-derived cells in the chimaeric embryo following grafting of wheat germ agglutinin-gold-labelled cells and culturing primitive-streak-stage mouse embryos. Embryonic ectoderm in the anterior region of the egg cylinder contributes to the neuroectoderm of the prosencephalon and mesencephalon. Cells in the distal lateral region give rise to the neuroectoderm of the rhombencephalon and the spinal cord. Embryonic ectoderm at the archenteron and adjacent to the middle region of the primitive streak contributes to the neuroepithelium of the spinal cord. The proximal-lateral ectoderm and the ectodermal cells adjacent to the posterior region of the primitive streak produce the surface ectoderm, the epidermal placodes and the cranial neural crest cells. Some labelled cells grafted to the anterior midline are found in the oral ectodermal lining, whereas cells from the archenteron are found in the notochord. With respect to mesodermal tissues, ectoderm at the archenteron and the distal-lateral region of the egg cylinder gives rise to rhomben-cephalic somitomeres, and the embryonic ectoderm adjacent to the primitive streak contributes to the somitic mesoderm and the lateral mesoderm. Based upon results of this and other grafting studies, a map of prospective ectodermal tissues in the embryonic ectoderm of the full-streak-stage mouse embryo is constructed.