bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevention of spinal neural tube defects in the mouse embryo by growth retardation during neurulation
Authors: Copp Andrew J. , Crolla John A. , Brook Frances A. 
Published: April 2021

ABSTRACTHomozygous mutant curly tail mouse embryos developing spinal neural tube defects (NTD) exhibit a celltype-specific abnormality of cell proliferation that affects the gut endoderm and notochord but not the neuroepithelium. We suggested that spinal NTD in these embryos may result from the imbalance of cell proliferation rates between affected and unaffected cell types. In order to test this hypothesis, curly tail embryos were subjected to influences that retard growth in vivo and in vitro. The expectation was that growth of unaffected rapidly growing cell types would be reduced to a greater extent than affected slowly growing cell types, thus counteracting the genetically determined imbalance of cell proliferation rates and leading to normalization of spinal neurulation.Food deprivation of pregnant females for 48 h prior to the stage of posterior neuropore closure reduced the overall incidence of spinal NTD and almost completely prevented open spina bifida, the most severe form of spinal NTD in curly tail mice. Analysis of embryos earlier in gestation showed that growth retardation acts by reducing the incidence of delayed neuropore closure. Culture of embryos at 40-5°C for 15-23 h from day 1(1 of gestation, like food deprivation in vivo, also produced growth retardation and led to normalization of posterior neuropore closure. Labelling of embryos in vitro with [3H]thymidine for 1 h at the end of the culture period showed that the labelling index is reduced to a greater extent in the neuroepithelium than in other cell types in growth-retarded embryos compared with controls cultured at 38°C. Moreover, the incidence of cell death is increased in the neuroepithelium to a greater extent than in other cell types. These results are consistent with the hypothesis that spinal NTD in curly tail embryos result from a genetically determined growth imbalance between neuroepithelium and gut endoderm/notochord.
Divergent axon collaterals in the regenerating goldfish optic tract: a fluorescence double-label study
Authors: Becker David L. , Cook Jeremy E. 
Published: April 2021

ABSTRACT
In the normal goldfish, optic axons are distributed between the two arms (brachia) of each optic tract, in such a way that each axon enters the tectum close to its retinotopic termination site. We have shown previously that regenerating axons at first express little or no preference for their normal brachium. Later, however, a partial refinement of the brachial pathway takes place, implying that some axons must have sent out divergent collateral branches and then eliminated the least appropriate.
We have now studied the formation and subsequent loss of axon collaterals in regeneration using retro–gradely transported fluorescent dyes. We labelled the axons in the medial brachium with Fast Blue and those in the lateral brachium with Diamidino Yellow in a way that avoided cross–contamination. In normal fish, yellow–labelled ganglion cells dominated the dorsal retina and blue–labelled ganglion cells the ventral, with only a narrow zone of overlap. Double–labelled cells were not found.
In fish labelled early in regeneration, however, both dyes were spread over the entire retina in single– and double–labelled ganglion cells. As regeneration progressed, each dye again came to dominate its appropriate retinal region; but much less strongly, confirming previous results. At the same time, doublelabelled cells became harder to find. From 60 days after nerve cut onwards they were rare, and largely confined to the boundary zone between dorsal and ventral retina. Their distribution was consistent with our previous proposal that excess collaterals may be eliminated competitively. Since axons from the boundary zone terminate in a tectal strip equidistant from the two brachia, neither route would confer any clear competitive advantage over the other.
Sea urchin morphogenesis and cell–hyalin adhesion are perturbed by a monoclonal antibody specific for hyalin
Authors: Adelson David L. , Humphreys Tom 
Published: April 2021

ABSTRACTWe have generated and characterized a monoclonal antibody (McA Tg-HYL) that recognizes sea urchin hyalin as evidenced by immunofluorescence staining of the hyaline layer (HL) and immunoblot staining of the hyalin protein band. On immunoblots of HL extracts only the hyalin protein reacted with McA Tg-HYL. Immunoprecipitates of radioactive proteins from embryos incubated with [3SS]methionine yielded radioactive hyalin and 190, 140 and 105×103Mr proteins associated with hyalin. McA Tg-HYL was generated against Tripneustes gratilla embryos but reacts with hyalin from the distantly related sea urchin species, Colobocentrotus atratus, Strongylocentrotus purpuradas, Arbacia punctulate, Lytechinus variegatus and Lytechinus pictus. Developing embryos of the abovementioned six species were treated with McA Tg-HYL and did not gastrulate or form arms. Observations of treated embryos revealed areas of separation of the hyaline layer from the underlying embryonic cells, suggesting that McA Tg-HYL was interfering with binding of the cells to the HL. Using the centrifugation-based adhesion assay of McClay et al. (Proc, natn. Acad. Sci. U.S.A. 78, 4975-4979, 1981), Fab’ fragments of McA Tg-HYL were found to inhibit cell-hyalin binding. McA Tg-HYL did not inhibit hyalin gelation in vitro or the reaggregation of dissociated blastula cells. We postulate that McA Tg-HYL recognizes an evolutionarily conserved hyalin domain involved in cell-hyalin binding and required for normal epithelial folding.
Axolotl pronephric duct cell migration is sensitive to phosphatidylinositol-specific phospholipase C
Authors: Zackson Saul L. , Steinberg Malcolm S. 
Published: April 2021

Abstract
On the basis of its distribution pattern in embryos of the axolotl (Ambystoma mexicanum), we recently identified alkaline phosphatase as a molecule potentially involved in guiding the migration of the pronephric duct. Alkaline phosphatase is a cell surface protein anchored to cell membranes via a covalent linkage to a phosphatidylinositol glycan (PI-G).
The enzyme phosphatidylinositol-specific phospholipase C (PIPLC) specifically releases from cell surfaces molecules anchored by the PI-G linkage. In order to test the possibility that a PI-G anchored protein is involved in directing pronephric duct cell migration, PIPLC was applied to axolotl embryos. The enzyme was introduced into embryos through the use of a novel slow-release bead material, hydrolysed polyacrylamide. PIPLC blocked pronephric duct cell migration without interfering with somite fissure formation, a concurrent, neighbouring morphogenetic cell rearrangement which occurs with little if any alkaline phosphatase present. In addition, alkaline phosphatase activity was markedly diminished in the vicinity of the implanted beads. These observations suggest that at least one protein anchored to the cell membrane by a PI-G linkage, possibly alkaline phosphatase, is involved in guiding or promoting pronephric duct cell migration.
Postnatal development of parthenogenetic ↔fertilized mouse aggregation chimeras
Authors: Paldi A. , Nagy A. , Markkula M. , Barna I. , Dezso L. 
Published: April 2021

Abstract
Chimeras were made from parthenogenetic and fertilized cleavage-stage mouse embryos. The perinatal mortality was high. The parthenogenetic contributions to different tissues at birth ranged from 0 to 50%. No selection of parthenogenetic cells was observed in the pigmentation of the coat, but this does not exclude that such selection could act in other tissues. The weight of chimeras at birth negatively correlated to the average contribution of the parthenogenetic part. The growth rate of chimeras was lower than that of nonchimeric animals.
The data presented demonstrate that, although parthenogenetic cells are not cell lethals and they can participate to some degree in normal development of most tissues, their extensive presence reduces the viability of chimeras and retards the postnatal development.
Novel patterns of homeotic protein accumulation in the head of theDrosophilaembryo
Authors: Mahaffey J. W. , Diederich R. J. , Kaufman T. C. 
Published: April 2021

AbstractAntibodies that specifically recognize proteins encoded by the homeotic genes: Sex combs reduced, Deformed, labial and proboscipedia, were used to follow the distribution of these gene products during embryogenesis. The position of engrailed-expressing cells was used as a reference and staining conditions were established that could distinguish, among cells expressing engrailed, one of the homeotic proteins or both. Our observations demonstrate two important facts about establishing identity in the head segments. First, in contrast to the overlapping pattern of homeotic gene expression in the trunk segments, we observe a non-overlapping pattern in the head for those homeotic proteins required during embryogenesis. In contrast, the spatial accumulation of the protein product of the non-vital proboscipedia locus overlaps partially with the distribution of the Deformed and Sex combs reduced proteins in the maxillary and labial segments, respectively. Second, two of the proteins, Sex combs reduced and Deformed, have different dorsal and ventral patterns of accumulation. Dorsally, these proteins are expressed in segmental domains while, within the ventral region, a parasegmental register is observed. The boundary where this change in pattern occurs coincides with the junction between the ventral neurogenic region and the dorsal epidermis. After contraction of the germ band, when the nerve cord has completely separated from the epidermis, the parasegmental pattern is observed only within the ventral nerve cord while a segmental register is maintained throughout the epidermis.
Neural enhancer-like elements as specific cell markers in Drosophila
Authors: Ghysen Alain , O’Kane Ahir 
Published: April 2021

Abstract
We have analysed four strains of Drosophila melanogaster which each carry the transposon P[lac,ry+] at a unique genomic location. In one of the strains, P[lac, ry+]A37, all the peripheral neurones that we can identify express the P-lac fusion protein; in at least some cases, all the support cells associated to particular neurones are also labelled. Expression of the fusion protein can be detected in subepidermal cells of the body segments as early as 4–5 h of development, according to a precise and reproducible pattern. On the basis of genetic evidence, we propose that these cells are precursors of sense organs, implying that the development of the peripheral nervous system overlaps in time with the development of the central nervous system. In the other three strains, the fusion product is expressed in unique subsets of cells of the peripheral nervous system, as well as in some other tissues.
Bimodal and graded expression of theXenopushomeobox geneXhox3during embryonic development
Authors: Altaba A. Ruiz I , Melton D. A. 
Published: April 2021

AbstractA Xenopus laevis homeobox gene, Xhox3, has been isolated using the homeobox of the Drosophila pair-rule gene even skipped as a hybridization probe. Xhox3 is first transcribed at the midblastula transition; RNA levels peak at the early neurula stage and decrease thereafter. During the early period of Xhox3 expression, the gastrula and neurula stages, transcripts are found in a graded fashion along the anteroposterior (A-P) axis in the mesoderm and are most concentrated at the posterior pole. In the late period of expression, the tailbud and tadpole stage, transcripts are concentrated at the two ends of the embryo: in the anterior nervous system and posterior tail bud. Analysis of Xhox3 expression in experimentally perturbed embryos shows that different A-P fates in the mesoderm are correlated with different levels of Xhox3 expression. Based on these results and those with other frog homeobox genes, we propose a role for homeobox genes in the patterning of the A-P embryonic axis.
The promoter region of theDrosophila α2-tubulin gene directs testicular and neural specific expression
Authors: Bo Jieying , Wensink Pieter C. 
Published: April 2021

ABSTRACTThe temporal and spatial expression pattern of the Drosophila melanogaster α2-tubulin gene (α2) has been investigated by examining the expression of an α2-lacZ fusion gene. When this fusion gene is introduced into the germ line by P-element mediated transformation, expression is only detected in chordotonal organs and testes. Chordotonal organs, which are sensory organs of the peripheral nervous system, express the gene from late embryonic through adult stages in both males and females. Testicular expression occurs from larval through adult stages and is limited to germ-line cells, the primary and secondary spermatocytes and perhaps the early spermatids.
Developmental patterning of the carbohydrate antigen FC10.2 during early embryogenesis in the chick
Authors: Loveless Wendy , Bellairs Ruth , Thorpe Susan J. , Page Mark , Feizi Ten 
Published: April 2021

ABSTRACT
An oligosaccharide antigen (FC10.2), formerly described only in mammalian cells and secreted glycoproteins, has been detected and found to display striking temporal and spatial patterning in the chick during early embryonic development. This antigen is expressed on type 1 chains, which are isomers of oligosaccharides of the poly-iV-acetyllactosamine series (type 2 chains). Immunoreactivities before and after neuraminidase treatment of serial sections of chick embryos during the first 17 stages of development indicate that the FC10.2 structure occurs predominantly in the sialylated form (S-FC10.2). The FC10.2 and S-FC10.2 antigens are prominent markers of the primordial germ cells, being strongly expressed by these cells from the pre-primitive streak stage onwards. S-FC10.2 is also a clear marker of the pronephric duct from its first appearance. Initially present over the entire apical surface of the ectoderm, antigenicity diminishes in an antero-posterior direction as neurulation proceeds. A unique pattern for a carbo hydrate antigen is displayed by cells of the primitive streak; antigenicity is lost with de-epithelialisation and ingression, but is regained in a pericellular distribution on the mesoderm cells that emerge from the primitive streak. Thereafter, successive changes in expression and distribution of FC10.2 and S-FC10.2 are features of mesodermal tissues, particularly during somitogenesis. These antigens are prominent components of the extracellular matrix around the notochord and sclerotome cells. They are also prominent posteriorly in the subecto-dermal region, ceasing abruptly at the lateral limits of the embryo proper. Although no absolute correlations can yet be made, several features of the distribution of these antigens suggest that they may be integral components of, or ligands for, cell adhesion molecules.
XY follicle cells in the ovaries of XO/XY and XO/XY/XYY mosaic mice
Authors: Palmer Stephen J. , Burgoyne Paul S. 
Published: April 2021

ABSTRACT
XO/XY and XO/XY/XYY mosaic hermaphrodites were generated from crosses involving BALB/cWt males. The distribution of Y-bearing cells in the gonads of these mice was studied by in situ hybridisation using the Y-specific probe pY353B. XY cells were found to contribute to all cell lineages of the ovary including follicle cells. The proportion of XY follicle cells was not significantly different from the XY contribution to other gonadal or non-gonadal cell lineages. However, this proportion was consistently low, all the hermaphrodites having a low XY contribution to the animal as a whole.
Because the XO- and Y-bearing cell lineages are developmentally balanced, the XY follicle cells cannot have formed as a result of a ‘mismatch’ in which the Y-directed testis determination process is pre-empted by an early acting programme of ovarian development. These results are discussed with respect to the hypothesis that Tdy acts in the supporting cell lineage, the lineage from which Sertoli cells and follicle cells are believed to be derived.
Plasma membrane localization of the Toll protein in the syncytial Drosophila embryo: importance of transmembrane signaling for dorsal–ventral pattern formation
Authors: Hashimoto Carl , Gerttula Suzanne , Anderson Kathryn V. 
Published: April 2021

ABSTRACT
Formation of the Drosophila embryo’s dorsal-ventral pattern requires the maternal product of the Toll gene. DNA sequence and genetic analyses together suggested that the Toll gene product is a transmembrane protein which communicates information from an extracyto-plasmic compartment to the cytoplasm. Using antibodies as probes, we show that the Toll protein is a 135 ×103Mr glycoprotein which is tightly associated with embryonic membranes. During the syncytial stage when dorsalventral polarity is established, the maternal Toll protein is associated with the plasma membrane around the entire embryo. During later embryonic stages, the Toll protein is expressed zygotically on many cell surfaces, possibly to promote cell adhesion. The plasma membrane localization of the Toll protein in the syncytial embryo suggests that transmembrane signaling from the extracellular perivitelline space to the cytoplasm is required for establishment of the embryonic dorsal-ventral pattern.
The interaction of boar sperm proacrosin with its natural substrate, the zona pellucida, and with polysulfated polysaccharides
Authors: Urch U. A. , Patel H. 
Published: April 2021

ABSTRACT
Boar sperm acrosin is an acrosomal protease with trypsin-like specificity, and it functions in fertilization by assisting sperm passage through the zona pellucida by limited hydrolysis of this extracellular matrix. In addition to a proteolytic active site domain, acrosin binds the zona pellucida at a separate binding domain that is lost during proacrosin autolysis. In this study, we quantitate the binding of proacrosin to the physiological substrate for acrosin, the zona pellucida, and to a nonsubstrate, the polysulfated polysaccharide fucoidan. Binding was analogous to sea urchin sperm bindin that binds egg jelly fucan and the vitelline envelope of sea urchin eggs. Proacrosin was found to bind to fucoidan and to the zona pellucida with binding affinities similar to bindin interaction with egg jelly fucan. These interactions were competitively inhibited by similar relative molecular mass polysulfated polymers. Since bindin and proacrosin have distinctly different amino acid sequences, their interaction with acidic sulfate esters demonstrates an example of convergent evolution wherein different macromolecules localized in analogous sperm compartments have the same biological function. From cDNA sequence analysis of proacrosin, this binding may be mediated through a consensus sequence for binding sulfated glycoconjugates. Proacrosin binding to the zona pellucida may serve as both a recognition or primary sperm receptor, as well as maintaining the sperm on the zona peUucida once the acrosome reaction has occurred.
Retarded nuclear migration in Drosophila embryos with aberrant F-actin reorganization caused by maternal mutations and by cytochalasin treatment
Authors: Hatanaka Ko , Okada Masukichi 
Published: April 2021

ABSTRACT
Three X-linked mutations of Drosophila melanogaster, gs(l)N26, gs(l)N441 and paralog, had a common maternal-effect phenotype. Mutant embryos show reduced egg contraction that normally occurs at an early cleavage stage in wild-type embryos. In addition, the mutants exhibited retarded nuclear migration while synchronous nuclear divisions were unaffected. The retarded migration causes nuclei to remain in the anterior part of the embryo retaining their spherical distribution even in a late cleavage stage. This consequently results in an extreme delay in nuclear arrival in the posterior periplasm. A mutant phenocopy was induced in wild-type embryos that were treated with cytochalasin B or D at a very early cleavage stage. Remarkable differences were noticed in the organization of cortical F-actin between the mutants and the wild type throughout the cleavage stage: obvious F-actin aggregates were dispersed in the cortex of mutant embryos, in contrast to the wild type where the cortical F-actin layer was smooth and underlying F-actin aggregates were smaller than those in the mutants; the transition of the distribution pattern of F-actin in the yolk mass, from the centralized to the fragmented type, occurred later in the mutants than in wild type. The results suggest that these mutations affect the mechanism underlying establishment and transition of F-actin organization required for normal egg contraction and nuclear migration in the cleavage embryos.
The development of adult muscles in Drosophila: ablation of identified muscle precursor cells
Authors: Broadie Kendal S. , Bate Michael 
Published: April 2021

ABSTRACT
A small subset of mesodermal cells continues to express twist in the late embryo of Drosophila. These cells are the precursors of adult muscles. Each late twist-expressing cell begins to divide early in the second larval instar and division continues throughout the second and third instars, resulting in a small clone of twist-expressing cells at puparium formation. Treatment with a DNA-synthesis inhibitor, hydroxyurea (HU), ablates these cells if applied during S-phase of their replication cycle. We ablated twist-expressing lineages in the larva and demonstrated that this results in the absence of subsets of muscles in the adult abdomen and leg. HU treatment during this larval period has no discernible effect on the adult epidermis or innervation. We conclude that the twist-expressing cells identified in the late embryo are the unique primordia of adult muscles.
Each primordium is fated to establish 6-10 adult muscle fibres, defined here as a ‘muscle fibre group’. Each primordium has a unique fate and, after ablation, is not replaced by neighbouring cells. This unique fate does not rest with a particular founder cell within the primordium but is specified at the primordium level: ablation of a subset of cells within a muscle primordium does not result in an ablation of the resulting muscle group or in a decrease in the number of fibres within that muscle group, but rather results in a uniform decrease in the number of nuclei/fibres throughout the entire muscle. Thus, the twist-expressing primordia in the abdomen appear to be fated to give rise to a particular muscle group but act as an equivalent precursor pool in the formation of that muscle group. Our results permit the conclusion that specific muscle groups in the adult leg arise from restricted pools of twist-expressing adepithelial cells in the larval imaginal disc in a similar fashion. We conclude that the fate restriction of myoblast pools in early development defines elements of the final adult muscle pattern. The fate restriction of myoblast cells may be a result of genetic determination to form a specified muscle group or, alternatively, reflect the spatial isolation of otherwise equivalent cells to form muscle-specific precursor pools.