bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dose-dependent regulation of pair-rule stripes by gap proteins and the initiation of segment polarity
Authors: Warrior Rahul , Levine Michael 
Published: April 2021

Abstract
A key step in Drosophila segmentation is the establishment of periodic patterns of pair-rule gene expression in response to gap gene products. From an examination of the distribution of gap and pair-rule proteins in various mutants, we conclude that the on/off periodicity of pairrule stripes depends on both the exact concentrations and combinations of gap proteins expressed in different embryonic cells.
It has been suggested that the distribution of gap gene products depends on cross-regulatory interactions among these genes. Here we provide evidence that autoregulation also plays an important role in this process since there is a reduction in the levels of Kruppel (Kr) RNA and protein in a Kr null mutant.
Once initiated by the gap genes each pair-rule stripe is bell shaped and has ill-defined margins. By the end of the fourteenth nuclear division cycle, the stripes of the pairrule gene even-skipped (eve) sharpen and polarize, a process that is essential for the precisely localized expression of segment polarity genes. This sharpening process appears to depend on a threshold response of the eve promoter to the combinatorial action of eve and a second pair-rule gene hairy. The eve and hairy expression patterns overlap but are out of register and the cells of maximal overlap form the anterior margin of the polarized eve stripe. We propose that the relative placement of the eve and hairy stripes may be an important factor in the initiation of segment polarity.
Re-establishment of the interphase microtubule array in vacuolated plant cells, studied by confocal microscopy and 3-D imaging
Authors: Flanders David J. , Rawlins David J. , Shaw Peter J. , Lloyd Clive W. 
Published: April 2021

Abstract
There are two conflicting ideas about the site of reassembly of cortical microtubules following cytokinesis. Some observations indicate that microtubules (MTs) radiate from the surface of the postcytokinetic nuclear envelope, before becoming organized at the cortex. On the other hand, results of regrowth experiments, following MT depolymerization by drugs, suggest that the array may assemble directly upon the cortex.
In this study, we have taken advantage of the significant separation between nucleus and cortex, in large, vacuolated epidermal cells, to determine which of these two potential sites supports the earliest stages of regrowth in the undrugged, native state.
MTs in stem epidermis of Datura stramonium L. were stained by indirect immunofluorescence. This was performed on hand-cut sections of tissue in which the cells were not separated by enzymes or distorted by airdrying. Epidermal cells with these sheets were optically sectioned by confocal laser scanning microscopy and three-dimensional images reconstructed, rotated and viewed stereoscopically using computer methods.
During metaphase, no MTs can be detected at the cortex but MTs begin to re-colonize the cell surface during early cytokinesis. Thick cables of MTs radiate from the nucleus parallel to the cell plate as well as in other directions, along transvacuolar strands, out to the cortex. Microtubules grow out over the cortex where the thick bundles make contact, as well as from the edges of the fully developed phragmoplast. These early cortical MTs do not form regular transverse arrays: they either appear to be random or to grow in branching V-shaped patterns. The cortical array is therefore not organized immediately but at a later stage.
It is concluded that MT bundles, radiating from the nucleus, are involved in the earliest stages of cortical array formation.
Polysialic acid and N-CAM localisation in embryonic rat kidney: mesenchymal and epithelial elements show different patterns of expression
Authors: Lackie Peter M. , Zuber Christian , Roth Jürgen 
Published: April 2021

Abstract
The expression of polysialic acid (PSA) and the neural cell adhesion molecule (N-CAM) during the embryonic development of rat kidney was investigated using immunocytochemistry and immunoblotting. A monoclonal antibody (mAb 735), which recognised only long chain PSA, and polyclonal antibodies specific for N-CAM were employed.
At the earliest stages of metanephros formation, PSA and N-CAM immunostaining was found in both embryonic anlagen, namely the uretic bud and the metanephrogenic mesenchyme. Reactivity in uretic bud derivatives declined during embryonic development and was generally absent in the collecting duct system by embryonic day 18 (E18). Uninduced metanephrogenic mesenchyme was immunostained throughout development while induced mesenchymal cells showed greatly increased PSA and N-CAM immunoreactivity during their transformation into epithelium. This staining declined rapidly as nephrons differentiated. These processes were preceded by sorting of PSA and N-CAM to the basolateral plasma membrane. Similar N-CAM and PSA patterns were observed in mesonephros development. In adult kidney parenchyma both PSA and N-CAM were undetectable.
Immunoblotting of samples of embryonic kidney with mAb 735 revealed a broad band ranging from 140 to greater than 200×103Mr. N-CAM antibodies revealed reactivity in a band of 140×103Mr after removal of PSA by endoneuraminidase treatment.
Expression of N-CAM and PSA in both embryonic anlagen indicates that neither molecular species acts primarily as an inductive signal. These molecules were localised in areas where changes in cell adhesion during organogenesis might be important and thus may be involved in the grouping of developing cells.
An extra maternally derived X chromosome is deleterious to early mouse development
Authors: Shao Changshun , Takagi Nobuo 
Published: April 2021

Abstract
An extra copy of the X chromosome, unlike autosomes, exerts only minor effects on development in mammals including man and mice, because all X chromosomes except one are genetically inactivated. Contrary to this contention, we found that an additional maternally derived X (XM) chromosome, but probably not a paternally derived one (Xp), consistently contributes to early death of 41,XXY and 41,XXX embryos in mice. Because of imprinted resistance to inactivation, two doses of XM remain active in the trophectoderm, and seem to be responsible for the failure in the development of the ectoplacental cone and extraembryonic ectoderm, and hence, from early embryonic death. Discordant observations in man indicating viability of XMXMXP and XMXMY individuals suggest that imprinting on the human X chromosome is either weak, unstable or erased before the initiation of X-inactivation in progenitors of extraembryonic membranes.
Evidence for allelism of the recessive insertional mutation add and the dominant mouse mutation extra-toes (Xt)
Authors: Pohl Thomas M. , Mattei Marie-Geneviève , Rüther Ulrich 
Published: April 2021

Abstract
A recessive mutant caused by insertional mutagenesis in transgenic mice has been detected in which the anterior part of the forelimb is disorganized. The morphology of the thumb is always altered and sometimes the adjacent finger has an extra phalanx. This phenotype suggests that a body plan gene is affected. We have named the mutation add (anterior digit-pattern deformity). Using the cloned DNA from the flanking region of the integrated transgene, add has been mapped close to the centromere of chromosome 13. This position links add to a genetically mapped locus called extra-toes (Xt). The phenotype of the double-mutant addjXt as well as the molecular analysis suggest that add and Xt are allelic.
Identification of vimentin and novel vimentin-related proteins in Xenopus oocytes and early embryos
Authors: Torpey N. P. , Heasman J. , Wylie C. C. 
Published: April 2021

Abstract
We have made antibodies against fusion proteins of Xenopus vimentin. We show for the first time the distribution of vimentin in larval stages, where it is found in cells of mesenchymal origin, and in radial glial cells. In sections of Xenopus oocytes and early embryos, immunocytochemistry reveals the presence of an extensive cytoplasmic network, distributed in an animal-vegetal gradient. Germ plasm stains particularly strongly. The form of the IF proteins in this network is unusual. In immunoblot experiments the anti-vimentin antibodies detect a number of distinct proteins. We have identified those that are the products of the two known vimentin genes, by injection of synthetic mRNA transcribed from cloned vimentin cDNAs into oocytes, followed by two-dimensional Western blotting. This has demonstrated unambiguously that one Xenopus vimentin, Vim1, is present in oocytes and early embryos. However, two other immunoreactive proteins detected in Triton extracts of oocytes and early embryos are not the products of Vim1, since depletion of vimentin mRNA by antisense oligonucleltide injection has no effect on the synthesis of these proteins. These results suggest that novel IF-like proteins are expressed in Xenopus oocytes and early embryos.
Decoding positional information: regulation of the pair-rule gene hairy
Authors: Howard Kenneth R. , Struhl Gary 
Published: April 2021

Abstract
In the series of local gene activations that occur during early Drosophila development, the striped expression patterns of the pair-rule genes provide the first indication of segmental periodicity. The experiments that we report here address the question of how these patterns arise, by studying the regulation of one of these genes, hairy. We show that each of the seven stripes of hairy expression is controlled by a distinct subset of cis-acting regulatory elements, some mediating transcriptional activation and others transcriptional repression. In general, elements necessary and sufficient for triggering a particular stripe response are clustered on the DNA and appear to overlap or be interspersed with elements involved in at least one other stripe response. Our results extend previous findings suggesting that periodic hairy expression arises by a decoding process in which each stripe is triggered by particular combinations or concentrations of regulatory factors. These regulatory factors are likely to include the products of the gap class of segmentation genes that are required for activating or positioning particular subsets of hairy stripes and are expressed with overlapping distributions during early embryogenesis.
Drosophila neurotactin, a surface glycoprotein with homology to serine esterases, is dynamically expressed during embryogenesis
Authors: Hortsch Michael , Patel Nipam H. , Bieber Allan J. , Traquina Zaida R. , Goodman Corey S. 
Published: April 2021

Abstract
Drosophila neurotactin is a transmembrane glycoprotein with an apparent molecular mass of 135 x 103 Neurotac tin is regionally expressed at the cellular blastoderm stage; later in embryogenesis the expression of the protein becomes restricted to cells of the peripheral and central nervous system. Immunocytochemical localiz ation shows neurotactin protein at points of cell-cell contact. Using the anti-neurotactin monoclonal antibody BP-106, a neurotactin cDNA was isolated that encodes a 846 residue polypeptide. The chromosomal location of the neurotactin gene is 73C. The extracellular domain at the carboxyterminal end of the neurotactin protein shows a strong structural and sequence homology to serine esterases without retaining the amino acids forming the active center. Neurotactin therefore belongs to a growing group of proteins including Drosophila glutactin and thyroglobulins that are known to share this serine esterase protein domain motif without retaining the active center of the enzyme.
Carbonic anhydrase III, an early mesodermal marker, is expressed in embryonic mouse skeletal muscle and notochord
Authors: Lyons Gary E. , Buckingham Margaret E. , Tweedie Susan , Edwards Yvonne H. 
Published: April 2021

ABSTRACT
Carbonic anhydrase HI (CAHI) is an abundant soluble protein in adult mammalian slow twitch skeletal muscle fibers. It is thought to be an early marker for myogenesis based upon its high level of expression in myoblasts in vitro prior to fusion. Using in situ hybridization, we have studied the in vivo distribution of CAIH gene transcripts in mouse embryos and fetuses from 7.25 days to 17.5 days post coitum (p.c.). CAIH mRNAs are first detected in the myotomes of somites between 9.5 and 10.5 days p.c. (20–30 somites). At 15.5 daysp.c., CAIH begins to be restricted to developing slow muscle fibers. By two weeks post partum (p.p.), CAIH mRNAs are detected mainly in slow muscle fibers.
CAHI transcripts are detected at an earlier stage (7.25 days p.c.) in the developing notochord. CAIH is expressed at a much higher level in the notochord than it is in developing skeletal muscle. As the notochord forms the nucleus pulposus in fetal mice, CAIH mRNA levels remain very high. Expression of CAIH in the notochord is of interest in the context of skeletal myogenesis because the notochord is thought to play an important role in somite formation. In addition to the notochord, CAIH transcripts are detected prenatally in several other non-muscle tissues: in cells of the choroid plexus, endocardial cushion and ureter, and in adipocytes.
Endodermal origin of yolk-sac-derived teratomas
Authors: Sobis H. , Verstuyf A. , Vandeputte M. 
Published: April 2021

ABSTRACTMutant mice deficient in glucose-6-phosphate dehydrogenase were used to induce teratomas. This enzyme is linked to the X chromosome, which can be inactivated in female embryo. The differences in the enzyme activity between yolk sac mesoderm and embryo versus yolk sac endoderm can be detected in female concepti by using appropriate crosses of wild-type and G6PD-deficient mice. Histochemical study showed that the dual cell population was observed in heterozygous embryos and in the embryomas derived from them. The teratomas derived from the corresponding yolk sac, however, were G6PD-positive from wild-type and G6PD-negative from homozygous enzyme-deficient mothers. We conclude that yolk-sac-derived teratomas are of endodermal origin because of the fact that the paternal X chromosome is inactivated in the yolk sac endoderm, whereas in the yolk sac mesoderm, as in the embryo, the inactivation is at random.
Expression of a novel cadherin (EP-cadherin) in unfertilized eggs and early Xenopus embryos
Authors: Ginsberg Dorit , Desimone Douglas , Geiger Benjamin 
Published: April 2021

Abstract
Two distinct cadherin cDNA clones of Xenopus laevis were isolated from a stage 17 embryo cDNA library. Analysis of the complete deduced amino acid sequences indicated that one of these molecules is closely homologous to chicken and mouse N-cadherin, while the other displays comparable homology to both E- and P-cadherins and was thus denoted EP-cadherin. This molecule has an apparent relative molecular mass of 125 ×103 (compared to approx. 138 ×103 or approx. 140 x103 of E-cadherin and N-cadherins, respectively). Northern and Western blot analyses indicated that N-cadherin is first expressed at the neurula stage while EP-cadherin is the only cadherin detected in unfertilized eggs and cleavage stage embryos. Immunolabeling of Xenopus eggs with antibodies prepared against a fusion protein, containing a segment of EP-cadherin, indicated that the protein is highly enriched at the periphery of the animal hemisphere. EP-cadherin was also found in A6 epithelial cells derived from Xenopus kidneys, and was apparently localized in the intercellular adherens junctions.
Involvement of Bone Morphogenetic Protein-4 (BMP-4) and Vgr-1 in morphogenesis and neurogenesis in the mouse
Authors: Jones C. Michael , Lyons Karen M. , Hogan Brigid L. M. 
Published: April 2021

Abstract
Bone Morphogenetic Protein-4 (BMP-4) and Vgr-1 are members of the TGF-/J gene family most closely related to the Drosophila Decapentaplegic and Xenopus Vg-1 genes. Members of this gene family have been implicated in diverse processes during embryogenesis including epithelial-mesenchymal interactions. Here, we use in situ hybridization to localize BMP-4 and Vgr-1 transcripts during murine development. BMP-4 mRNA is found in a variety of tissues. In the 8.5 days p.c. embryo, transcripts are localized to the mesoderm posterior to the last somite. Later gestation embryos show expression in developing limbs, the embryonic heart, the facial processes and condensed mesenchymal cells associated with early whisker follicle formation. In the developing central nervous system (CNS), BMP-4 expression is restricted to the floor of the diencephalon associated with pituitary development. In contrast, Vgr-1 transcripts are found along the anteroposterior axis of the CNS, in cells immediately adjacent to the floor plate and in the roof plate extending to the forebrain. Together, the data support the hypothesis that polypeptide growth factors of the TGF-β superfamily play key roles in the initial stages of neurogenesis and organogenesis during murine development.
Primitive erythropoiesis of mouse teratocarcinoma stem cells PCC3/A/1 in serum-free medium
Authors: Miwa Yoko , Atsumi Tadao , Imai Nobuo , Ikawa Yoji 
Published: April 2021

Abstract
Mouse teratocarcinoma stem cells PCC3/A/1 differentiated into various types of cells, such as red cells, when they were grown in serum-free medium containing transferrin and bovine serum albumin on a KCF cell feeder layer. These red cells were stained well with 2,7-diaminofluorene (DAF), and therefore were erythroid cells. They were nucleated and contained embryonic globin chains, immunologically identified with anti-embryonic hemoglobin antisera after acid urea Triton X-100 polyacrylamide gel electrophoresis (UT-PAGE). The addition of erythropoietin to the culture medium enhanced the production of both embryonic and adult globin chains. The addition of interleukin-3 also enhanced the production of embryonic globin chains, but not the production of adult globin chains. These results indicated that primitive erythropoiesis of PCC3/A/1 teratocarcinoma cells did not require exogenous addition of any hematopoietic factor such as erythropoietin or interleukin-3. This culture system will be a new model system for investigating the factors regulating the primitive erythropoiesis in yolk sac blood islands.
Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development
Authors: Perris Roberto , Krotoski Danuta , Lallier Thomas , Domingo Carmen , Sorrell J. Michael , Bronner-Fraser Marianne 
Published: April 2021

Abstract
In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosamino-glycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinyl-ated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were ob-served. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratan sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around mi-grating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distri-butions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In gen-eral, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia.
Expression of a novel Müller glia specific antigen during development and after optic nerve lesion
Authors: Schlosshauer Burkhard , Grauer Dorothee , Dütting Dieter , Vanselow Jens 
Published: April 2021

ABSTRACT
To generate monoclonal antibodies, immunogen fractions were purified from embryonic chick retinae by temperature-induced detergent-phase separation employing Triton X-114. Under reducing conditions, the monoclonal antibody (mAb) 2M6 identifies a protein doublet at 40 and 46×103Mr, which appears to form disulfide-coupled multimers. The 2M6 antigen is regulated developmentally during retinal histogenesis and its expression correlates with Müller glial cell differentiation. Isolated glial endfeet and retinal glial cells in vitro were found to be 2M6-positive, identified with the aid of the general glia marker mAb R5. mAb 2M6 does not bind to any other glial cell type in the CNS as judged from immunohistochemical data. Cell-type specificity was further substantiated by employing retinal explant and single cell cultures on laminin in conjunction with two novel neuron-specific monoclonal antibodies. MAb 2M6 does not bind either to neurites or to neuronal cell bodies. Incubation of retinal cells in vitro with bromodeoxyuridine (BrdU) and subsequent immunodouble labeling with mAb 2M6 and anti-BrdU reveal that mitotic Müller cells can also express the 2M6 antigen.
To investigate whether Müller cell differentiation depends on interactions with earlier differentiating ganglion cells, transections of early embryonic optic nerves in vivo were performed. This operation eliminates ganglion cells. Müller cell development and 2M6 antigen expression were not affected, suggesting a ganglion-cell-independent differentiation process. If, however, the optic nerve of juvenile chicken was crushed to induce a transient degeneration/regeneration process in the retina, a significant increase of 2M6 immunoreactivity became evident. These data are in line with the hypothesis that Müller glial cells, in contrast to other distinct glial cell types, might facilitate neural regeneration.