bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vital dye labelling demonstrates a sacral neural crest contribution to the enteric nervous system of chick and mouse embryos
Authors: Serbedzija George N. , Burgan Scott , Fraser Scott E. , Bronner-Fraser Marianne 
Published: April 2021

ABSTRACT
We have used the vital dye, Dil, to analyze the contribution of sacral neural crest cells to the enteric nervous system in chick and mouse embryos. In order to label premigratory sacral neural crest cells selectively, Dil was injected into the lumen of the neural tube at the level of the hindlimb. In chick embryos, Dil injections made prior to stage 19 resulted in labelled cells in the gut, which had emerged from the neural tube adjacent to somites 29–37. In mouse embryos, neural crest cells emigrated from the sacral neural tube between E9 and E9.5. In both chick and mouse embryos, Dil-labelled cells were observed in the rostral half of the somitic sclerotome, around the dorsal aorta, in the mesentery surrounding the gut, as well as within the epithelium of the gut. Mouse embryos, however, contained consistently fewer labelled cells than chick embryos. Dil-labelled cells first were observed in the rostral and dorsal portion of the gut. Paralleling the maturation of the embryo, there was a rostral-to-caudal sequence in which neural crest cells populated the gut at the sacral level. In addition, neural crest cells appeared within the gut in a dorsal-to-ventral sequence, suggesting that the cells entered the gut dorsally and moved progressively ventrally. The present results resolve a long-standing discrepancy in the literature by demonstrating that sacral neural crest cells in both the chick and mouse contribute to the enteric nervous system in the postumbilical gut.
Expression of the mouse α1 (II) collagen gene is not restricted to cartilage during development
Authors: Cheah Kathryn S. E. , Lau Elizabeth T. , Au Patrick K. C. , Tam Patrick P. L. 
Published: April 2021

ABSTRACT
The mouse αl(II) collagen gene has been isolated and a 5′ portion of the gene which has low homology to other collagen genes was used to study the pattern of expression during mouse embryogenesis. In situ hybridization studies show that in the mouse, like the chick, α1(11) collagen is expressed in chondrogenic tissues in advance of chondrocyte differentiation. The gene is expressed early in embryogenesis at 9.5 days both in the cranial mesenchyme destined for the chondrocranium, and the sclerotome of the somites, and at 12.5 days in the primordia of the hyoid and the laryngeal cartilage. Type II collagen gene transcripts were found in all the chondrogenic tissues of the axial and appendicular skeleton until the onset of endochondral ossification. Expression of α1(11) collagen mRNA was also observed in non-chondrogenic tissues such as the notochord which may be responsible for inducing chondrogenesis in somitic mesoderm, neural retina, the corneal and conjunctival epithelia and sclera of the developing eye. Expression in the tail tendon was late, at 16.5–18.5 days.
Transient expression was also found in the heart at 9.5–12.5 days, the epidermis at 10.5–14.5 days, the calvarial mesenchyme at 12.5–16.5 days, the inner ear at 14.5 days and the fetal brain from 9.5-14.5 days. Within the neural tube, α1(11) collagen mRNA was localized in the proliferative ventricular cells of the forebrain and midbrain of 9.5-to 10.5-day embryos. Subsequently, transcription of the αl(II) collagen gene was confined to restricted areas of the rhombencephalic basal plate, the ventricular layer of the hindbrain and the cervical spinal cord. These examples of expression of the type II collagen gene in the developing nervous system seem to suggest that active transcription of this gene might be associated with early stages of neuroblast differentiation. Type II collagen may therefore have additional roles in development unrelated to chondrogenesis.
Glucose transporter gene expression in early mouse embryos
Authors: Hogan Aileen , Heyner Susan , Charron Maureen J. , Copeland Neal G. , Gilbert Debra J. , Jenkins Nancy A. , Thorens Bernard , Schultz Gilbert A. 
Published: April 2021

Summary
The glucose transporter (GLUT) isoforms responsible for glucose uptake in early mouse embryos have been identified. GLUT 1, the isoform present in nearly every tissue examined including adult brain and erythrocytes, is expressed throughout preimplantation development. GLUT 2, which is normally present in adult liver, kidney, intestine and pancreatic β cells is expressed from the 8-cell stage onward. GLUT 4, an insulin-recruitable isoform, which is expressed in adult fat and muscle, is not expressed at any stage of preimplantation develop- ment or in early postimplantation stage embryos. Genetic mapping studies of glucose transporters in the mouse show that Glut-1 is located on chromosome 4, Glut-2 on chromosome 3, Glut-3 on chromosome 6, and Glut-4 on chromosome 11.
Cells with persistent twist expression are the embryonic precursors of adult muscles in Drosophila
Authors: Bate Michael , Rushton Emma , Currie Douglas A. 
Published: April 2021

ABSTRACT
twist expression in the embryonic mesoderm of Drosphila declines during germ band retraction to leave a residual population of twisr-expressing cells in the late embryo. In the abdomen, the pattern of twist expression is a simple one: a single cell ventrally, pairs of cells laterally and three cells dorsally in each hemisegment. In the thorax, there are patches of cells associated with the imaginai discs and there are additional clusters in A8 and A9. During larval life, the twist-expressing cells proliferate and, in the abdomen, they form ventral, lateral and dorsal clusters, which are the precursors of the adult abdominal muscles, while in the thorax, they form populations of cells in the imaginai discs that correspond to the adepithelial cells described by previous authors. While most thoracic twist-expressing cells are associated with the discs, the abdominal cells are separate from the precursors of the adult abdominal epidermis, the abdominal histoblasts, and lie on branches of peripheral nerves. The distribution of these cells is tightly linked to the pattern of peripheral nerves, but they segregate normally in da/da embryos despite the absence of the peripheral nervous system.
The development of adult abdominal muscles in Drosophila: myoblasts express twist and are associated with nerves
Authors: Currie Douglas A. , Bate Michael 
Published: April 2021

ABSTRACT
During metamorphosis, the adult muscles of the Drosophila abdomen develop from pools of myoblasts that are present in the larva. The adult myoblasts express twist in the third larval instar and the early pupa and are closely associated with nerves. Growing adult nerves and the twist-expressing cells migrate out across the developing abdominal epidermis, and as twist expression declines, the myoblasts begin to synthesize β3 tubulin. There follows a process involving cell fusion and segregation into cell groups to form multinucleate muscle precursors. These bipolar precursors migrate at both ends to find their correct attachment points, β3 tubulin expression continues at least until 51 h APF by which time the adult muscle pattern has been established.
Activation of p34cdc2 protein kinase activity in meiotic and mitotic cell cycles in mouse oocytes and embryos
Authors: Choi Taesaeng , Aoki Fugaku , Mori Makoto , Yamashita Masakane , Nagahama Yoshitaka , Kohmoto Kaoru 
Published: April 2021

ABSTRACT
p34cdc2 protein kinase is a universal regulator of M-phase in eukaryotic cell cycle. To investigate the regulation of meiotic and mitotic cell cycle in mammals, we examined the changes in phosphorylation states of p34cdc2 and its histone Hl kinase activity in mouse oocytes and embryos.
We showed that p34cde2 has three different migrating bands (referred to as upper, middle and lower bands) on SDS-PAGE followed by immunoblotting with anti- PSTAIR antibody, and that the upper and middle bands are phosphorylated forms since these two bands shifted to the lower one by alkaline phosphatase treatment.
In meiotic cell cycle, only germinal vesicle (GV) stage oocytes had the three forms. The phosphorylated forms decreased gradually in oocytes up to 2 h after isolation from follicles, and thereafter the phosphorylation states did not change significantly until metaphase H. How ever, the histone Hl kinase activity oscillated, being activated at the first and second metaphase in meiosis and inactivated at the time of the first polar body extrusion. These results suggest that changes in phosphorylation states of p34cd” triggered its activation at the first metaphase, but not inactivation and reactivation at the first and second metaphase, respectively.
In mitotic cell cycle, phosphorylated forms appeared at 4h after insemination, increased greatly just before metaphase, and were dephosphorylated in metaphase. Histone Hl kinase activity was high only at metaphase. This kinase activation is probably triggered by déphosphorylation of p34cdc2.
Specific expression of a retinoic acid-regulated, zinc-finger gene, Rex-1, in preimplantation embryos, trophoblast and spermatocytes
Authors: Rogers Melissa B. , Hosler Betsy A. , Gudas Lorraine J. 
Published: April 2021

ABSTRACT
We have previously isolated a cDNA clone for a gene whose expression is reduced by retinoic acid (RA) treatment of F9 embryonal carcinoma cells. The nucleotide sequence indicated that this gene, Rex-1, encodes a zinc-finger protein and thus may be a transcriptional regulator. The Rex-1 message level is high in two lines of embryonic stem cells (CCE and D3) and is reduced when D3 cells are induced to differentiate using four different growth conditions. As expected for a stem-cell-specific message, Rex-1 mRNA is present in the inner cell mass (ICM) of the day 4.5 mouse blastocyst. It is also present in the polar trophoblast of the blastocyst. One and two days later, Rex-1 message is found in the ectoplacental cone and extraembryonic ectoderm of the egg cylinder (trophoblast-derived tissues), but its abundance is much reduced in the embryonic ectoderm which is directly descended from the ICM. Rex-1 is expressed in the day 18 placenta (murine gestation is 18 days), a tissue which is largely derived from trophoblast. The only tested adult tissue that contains detectable amounts of Rex-1 mRNA is the testis. In situ hybridization and northern analyses of RNA from germ-cell-deficient mouse testis and stage-specific germ cell preparations suggest that Rex-1 expression is limited to spermatocytes (germ cells undergoing meiosis). These results suggest that Rex-1 is involved in trophoblast development and spermatogenesis, and is a useful marker for studies of early cell fate determination in the ICM.
Expression pattern of the Brachyury gene in whole-mount T
WIS/T
WIS mutant embryos
Authors: Herrmann Bernhard G. 
Published: April 2021

ABSTRACT
The murine Brachyury (T) gene is required in mesoderm formation. Mutants carrying different T alleles show a graded severity of defects correlated with gene dosage along the body axis. The phenotypes range from shortening of the tail to the malformation of sacral vertebrae in heterozygotes, and to disruption of trunk development and embryonic death in homozygotes. Defects include a severe disturbance of the primitive streak, an early cessation of mesoderm formation and absence of the allantois and notochord, the latter resulting in an abnormality of the neural tube and somites. The T gene is expressed in nascent mesoderm and in the notochord of wild-type embryos. Here the expression of T in whole-mount mutant embryos homozygous for the T allele Twis is described. The Twisgene product is altered, but the Twis/Twis phenotype is very similar to that of T/T embryos which lack T. In early Twis/Twis embryos T expression is normal, but ceases prematurely during early organogenesis coincident with a cessation of mesoderm formation. The archenteron/node region is disrupted and the extension of the notochord precursor comes to a halt, followed by a decrease and finally a complete loss of T gene expression in the primitive streak and the head process/notochord precursor. It appears that the primary defect of the mutant embryo is the disruption of the notochord precursor in the node region which is required for axis elongation. Thus the T gene product is directly or indirectly involved in the organization of axial development.
The transcription factor TTF-1 is expressed at the onset of thyroid and lung morphogenesis and in restricted regions of the foetal brain
Authors: Lazzaro Domenico , Price Melanie , Felice Mario De , Lauro Roberto Di 
Published: April 2021

ABSTRACT
TTF-1, a homeodomain-containing transcription factor, which is required for the specific expression of the thyroglobulin and thyroperoxidase gene promoters in differentiated thyroid cell lines, is expressed at the very beginning of rat thyroid differentiation. TTF-1 mRNA is detected in the endodermal cells of the thyroid rudiment in the rat embryo and precedes the expression of the two known target genes by 5 days. No delay is observed between the appearance of TTF-1 mRNA and protein, which shows a clear nuclear localization. In the adult thyroid, TTF-1 is present only in the endoderm-derived follicular cells.
Two additional domains of expression of TTF-1 have been observed, the lung and restricted areas of the brain. In the lung, TTF-1 mRNA and protein are also present at the earliest stages of differentiation and are later confined to the bronchial epithelium. In the brain, TTF-1 appears to be restricted to structures of diencephalic origin, including the developing neurohypophysis. The early detection of TTF-1 in the endodermal cells of the thyroid and lung anlage and in restricted neuroblast populations indicates that TTF-1 may have a role in cell determination in these three systems and that additional mechanisms may be involved in the activation of thyroid-specific gene expression.
Retinoic acid modifies development of the midbrain-hindbrain border and affects cranial ganglion formation in zebrafish embryos
Authors: Holder Nigel , Hill James 
Published: April 2021

ABSTRACT
Considerable evidence now suggests that retinoic acid (RA) is an important modulator of patterning events in early neuronal development in vertebrates. In this paper, we describe the effects of exogenously applied RA on early neural development in the zebrafish embryo. Neural anatomy is assessed by immunocytochemical and histochemical analysis of the developing embryo in whole mounts at 24 h post-fertilization. RA was applied for one hour at concentrations ranging from 10−9 to 10−6M to embryos at 50% epiboly, the midgastrula stage, and at 10−7M to embryos at early and late gastrula stages.
The neuroanatomical analysis shows that 10−7M RA causes a defined lesion to the developing central nervous system which corresponds to a loss of a region of the brain in the caudal midbrain-rostral hindbrain area, the precursor of the cerebellum and associated neural structures. The region that fails to develop corresponds to the cranial expression domain of the engrailed protein as assessed by the monoclonal antibody 4D9 (Patel et al. 1989: Expression of engrailed proteins in arthropods, annelids and chordates. Cell 58, 955-968). Structures caudal to rhombomere 4 are unaffected by 10 7 M RA, as are the cranial midbrain and forebrain: 10−7M RA also affects the development of cranial ganglia, principally the Vth, anterior lateral line and VUIth ganglia, suggesting that RA affects normal development of the cranial neural crest. Effects of RA at stages immediately prior to and after gastrulation show some similar and some distinct features.
Results are discussed in terms of the possible role of RA as an endogenous moderator of normal head development.
Control of dorsoventral pattern in vertebrate neural development: induction and polarizing properties of the floor plate
Authors: Placzek Marysia , Yamada Toshiya , Tessier-Lavigne Marc , Jessell Thomas , Dodd Jane 
Published: April 2021

Abstract
Distinct classes of neural cells differentiate at specific locations within the embryonic vertebrate nervous system. To define the cellular mechanisms that control the identity and pattern of neural cells we have used a combination of functional assays and antigenic markers to examine the differentiation of cells in the developing spinal cord and hindbrain in vivo and in vitro. Our results suggest that a critical step in the dorsoventral patterning of the embryonic CNS is the differentiation of a specialized group of midline neural cells, termed the floor plate, in response to local inductive signals from the underlying notochord. The floor plate and notochord appear to control the pattern of cell types that appear along the dorsoventral axis of the neural tube. The fate of neuroepithelial cells in the ventral neural tube may be defined by cell position with respect to the ventral midline and controlled by polarizing signals that originate from the floor plate and notochord.
Conserved segmental expression of Krox-20 in the vertebrate hindbrain and its relationship to lineage restriction
Authors: Nieto M. Angela , Bradley Leila C. , Wilkinson David G. 
Published: April 2021

Abstract
The zinc-finger gene Krox-20 is expressed in two alternating segments, rhombomeres (r) 3 and 5, in the developing mouse hindbrain. This expression pattern is established prior to rhombomere formation in the mouse, but it is not known how the timing of expression relates to cellular events of segmentation, such as lineage restriction. We have cloned Krox-20 sequences from Xenopus and the chick and shown that its alternating expression pattern is conserved in these systems, suggesting that its role in hindbrain development is conserved. Analysis of the early stages of Krox-20 expression in the chick show that both domains of expression precede the restriction of cell lineage to specific rhombomeres, consistent with a role of this gene in early events of hindbrain segmentation. The finding that expression is not coincident with lineage restriction indicates that early expression may not reflect an irreversible commitment of cells to r3 and r5 and/or may be mosaic.
Purine utilisation, de novo synthesis and degradation in mouse preimplantation embryos
Authors: Alexiou Maria , Leese Henry J. 
Published: April 2021

ABSTRACT
The importance of de novo purine synthesis as opposed to the réutilisation of metabolites by salvage pathways, and the nature of the excretory product(s) of purine degradation, have been examined in cultured pre-implantation mouse embryos. In the presence of azaser-ine and mycophenolic acid, which inhibit de novo purine synthesis, embryo cleavage was blocked prior to com-paction, the precise stages at which this occurred depended on whether the cultures were established on day 1 or day 2 after fertilisation, and indicated that salvage pathways were insufficient to fulfil the demand for nucleotides during early preimplantation develop-ment. The end-product of purine degradation appeared to be xanthine, which was excreted in very small amounts on days 1, 2 and 3, with a pronounced rise from the early to late blastocyst. Uric acid formation or excretion could not be detected. Exogenous hypoxan-thine and adenine, which partially inhibited develop-ment, were taken up by the embryos and converted to xanthine, most probably by salvage pathways, since the enzyme xanthine oxidase, which converts hypoxanthine directly to xanthine and then to uric acid, could not be detected. Exogenous guanine bad little effect on develop-ment and was also converted to xanthine, but in this case, the conversion was probably in a single step, via the enzyme guan ase.
Spatial and temporal patterns of distribution of the gap junction protein connexin43 during mouse gastrulation and organogenesis
Authors: Yancey S. Barbara , Biswal Sandip , Revel Jean-Paul 
Published: April 2021

ABSTRACT
Connexin43 (Cx43) is a member of the family of channel-forming proteins that make up the gap junction and are believed to provide pathways for cell-cell exchange of developmental signals. We have used immunofluor-escence and confocal microscopy to characterize the patterns of distribution of Cx43 in postimplantation mouse embryos representing stages of development extending through gastrulation and the major period of organogenesis [through 13.5 days post coitum (dpc)]. We find that Cx43 is expressed early after implantation by the undifferentiated, pluripotent cells of the primitive embryonic ectoderm from which all tissues of the fetus are believed to be derived. As cells become committed to particular developmental pathways, there is a progressive restriction of Cx43 to specific areas and organ systems. The patterns are complex and not limited by germ layer of origin, although there is a clear preference for expression in ectodermal and, to a lesser extent, mesodermal derivatives. Expression in lens, retina, kidney, brain, pineal and pituitary glands is initiated early in organogenesis. In heart, the first clear signal for Cx43 appears in the ventricle at about 10 dpc and is only subsequently detected in the atrium at about 13–13.5 dpc. Particularly intriguing with regard to functional implications is the high level expression observed at sites of inductive interaction; the eye lens and optic cup, the infundibulum and the apical ectodermal ridge of the limb bud.
The Drosophila pumilio gene: an unusually long transcription unit and an unusual protein
Authors: Macdonald Paul M. 
Published: April 2021

ABSTRACT
Specification of the posterior body plan in Drosophila requires the action of a determinant prelocalized to the posterior pole of the embryo. During embryogenesis this determinant appears to move anteriorly in a process dependent on the pumilio (pum) gene. This report describes the cloning and molecular characterization of a cDNA derived from the pum gene, and the analysis of pum mRNA and protein expression during early Drosophila development. The pum gene is unusually large; comparison of genomic and cDNA sequences reveals that the pum transcription unit is at least 160 kb in length.
The pum cDNA encodes a 157 × 103Mr protein which consists mainly of regions enriched in a single amino acid, usually glycine, alanine, glutamine or serine/threonine. Six tandem repeats of a 36 amino acid repeat unit are also present. Pum protein is cytoplasmic and is concentrated in a subcortical region of the embryo. The distribution of pum protein exhibits no asymmetry along the anteroposterior axis of the embryo. .