bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression patterns of c-myb and of v-myb induced myeloid-1 (mim-1) gene during the development of the chick embryo
Authors: Quéva Christophe , Ness Scott A. , Grässer Frederick A. , Graf Thomas , Vandenbunder Bernard , Stéhelin Dominique 
Published: April 2021

ABSTRACT
The v-myb oncogene of the acute avian leukemia virus E26 encodes a transcription factor that directly regulates the promyelocyte-specific mim-1 gene (Ness, S.A., Marknell, A. and Graf, T. Cell, 59,1115–1125). We have investigated the relationship between the c-myb proto-oncogene and the transcription of the mim-1 gene both in vitro and in vivo. We demonstrate that the c-myb protein can transactivate the transcription of mim-1 in a transient transfection assay.
In the chick embryo, we confirm that mim-1 is specifically expressed during granulopoiesis and we show that the expression of c-myb and mim-1 are perfectly correlated in the granulocytic spleen and pancreas. However we suggest that mim-1 is efficiently transcribed in the absence of c-myb in the yolk sac and in the promyelocytes at the onset of the colonization of the bursa of Fabricius. On the other hand c-myb transcripts detected in the early hemopoietic progenitor cells, in lymphoid cells and in proliferative epithelia are never associated with mim-1 transcription.
We conclude that the granylocyte-specific mim-1 gene is regulated by c-myZ&gt;-dependent and c-myh-independent mechanisms depending upon the environment in which granulocytic precursor cells differentiate.
The involvement of adherens junction components in myofibrillogenesis in cultured cardiac myocytes
Authors: Goncharova Ekaterina J. , Kam Zvi , Geiger Benjamin 
Published: April 2021

ABSTRACT
The distribution of adherens junction (AJ) components was investigated in cultured heart myocytes. These cells, derived from either newborn rats or chick embryos, develop elaborate arrays of myofibrils which become extensive and laterally aligned following several days in culture. The Z-disks in these cells, visualized by immunolabeling with antibodies to muscle-specific a- actinin, exhibit a characteristic periodicity of about 2 fan and are in register with those of neighboring myofibrils throughout the sarcoplasm. Vinculin, in these cells, associates with intercellular AJ and cell-matrix adhesions. In addition, this protein is detected in periodic bands located along the lateral cell membranes corresponding to “costamers” previously described by Pardo, J.V., Siliciano, J.D. and Craig, S.W. (Proc. Natn. Acad. Sci. USA, 80,1008). Similarly, N-cadherin, which is predominantly associated with intercellular junctions, is also detected in periodic striations located mainly on the dorsal and lateral cell surfaces. Using computer-aided three-dimensional microscopy confirmed that these vinculin- and N-cadherin-containing structures are located in extrajunctional sites, appar-ently associated with Z-disks of peripheral myofibrils. Based on these findings an alternative pathway is proposed for the assembly of vinculin and N-cadherin, which is not triggered by adhesive interactions with extracellular surfaces but rather by interactions at the membrane-cytoplasm interphase with the periphery of the pre-assembled myofibrills. Moreover, we present evidence that antibodies to N-cadherin, which are capable of blocking AJ formation in culture, have an inhibitory effect also on the development and alignment of myofibrils. We discuss the functional significance of the “costameric” organization of vinculin and N-cadherin and consider its involvement both in the lateral alignment of neighboring muscle cells and in the stabilization of developing myofibrils.
Mutually exclusive expression of the Strongylocentrotus purpuratus Spc1 gene and its Lytechinus pictus homologue in cells of hybrid embryos
Authors: Nisson Paul E. , Gaudette Michelle F. , Brandhorst Bruce P. , Crain William R. 
Published: April 2021

ABSTRACT
The expression of the Specl gene of Strongylocentrotus purpuratus and its Lytechinus pictus homologue LpSl was analyzed in reciprocal hybrid embryos of these two species of sea urchin. While the time course of accumulation of Specl mRNA was nearly normal in hybrid embryo populations, the accumulation of LpSl mRNA was not. This was particularly evident in plutei, where the level of LpSl mRNA was less than 5% that in normal L. pictus plutei. In situ hybridization analysis of serial sections indicated that LpSl mRNA was detectable in only about 2% of hybrid plutei in either cross, whereas Specl mRNA was present in nearly all hybrid plutei; expression of either homologue was appropriately restricted to the aboral ectoderm. In crosses of L. pictus eggs with S. purpuratus sperm (LpSp), about 1% of hybrid plutei expressed LpSl RNA in most or all aboral ectoderm cells at normal levels, and did not express Specl RNA; in another 1% of the LpSp hybrid plutei the Specl and LpSl transcripts were present at normal levels in complementary, non-overlapping patches of contiguous aboral ectoderm cells. In the reciprocal SpLp cross, each hybrid pluteus expressed either only the LpSl gene (about 2%) or only the Specl gene through-out the aboral ectoderm. In SpLp hybrid gastrulae the level of LpSl mRNA was less restricted; about 2% of the embryos contained only LpSl RNA, and about half expressed only Specl transcripts, but in the remaining embryos Specl and LpSl transcripts were coexpressed in the same aboral ectoderm cells. Thus, the predominant expression of the Specl gene in hybrid embryos results from the developmentally progressive restriction of transcription of the LpSl gene to aboral ectoderm cells not expressing the Specl gene in a few hybrid embryos, while most hybrid plutei express the Specl gene exclusively.
Erythroid colony formation by fetal rat liver and spleen cells in vitro: inhibition by a low relative molecular mass component of fetal spleen
Authors: Nagel M.-D. , Nagel J. 
Published: April 2021

ABSTRACT
L1ver and spleen hematopoietic cell suspensions from 20-day-old-fetal rats were fractionated on Percoll gradients. A granulocyte-rich splenic fraction inhibited CFUe production by cultures of a CFUe-enriched liver fraction, and by cultures of unfractionated liver and spleen hematopoietic cells. Conditioned medium from the spleen cell fraction contained an inhibitor of relative molecular mass, Mr, 25–35 × 103. The sensitivity of spleen cells to the inhibitor varied with the age of the fetus from which they were derived (20-day-old &lt;18- and 19-day-old). No such age-dependence was found for liver cells. The inhibitor affects cycling CFUe, blocks the lethal effect of AraC, does not appear to be lineage-specific and its influence can be reversed by washing.
Two FGF receptor genes are differentially expressed in epithelial and mesenchymal tissues during limb formation and organogenesis in the mouse
Authors: Peters K. G. , Werner S. , Chen G. , Williams L. T. 
Published: April 2021

ABSTRACT
Fibroblast growth factors (FGFs) can influence the growth and differentiation of cultured cells derived from neuroectoderm, ectoderm or mesenchyme. The FGFs interact with a family of at least four closely related receptor tyrosine kinases that are products of individual genes. To investigate the role of FGFs in the growth and differentiation of embryonic tissues and to determine whether the individual FGF receptor genes might have specific functions, we compared the localization of mRNA for two FGF receptor genes, FGFR1 (the fig gene product) and FGFR2 (the bek gene product), during limb formation and organogenesis in mouse embryos (E9.5-E16.5). Although the two genes were coexpressed in some tissues, the differential expression of FGFR1 and FGFR2 in most embryonic tissues was striking. FGFR1 was expressed diffusely in mesenchyme of limb buds, somites and organ rudiments. In contrast, FGFR2 was expressed predominantly in the epithelial cells of embryonic skin and of developing organs. The differential expression of FGFR1 and FGFR2 in mesenchyme and epithelium respectively, suggests the receptor genes are independently regulated and that they mediate different functions of FGFs during development.
Combined action of c-Kit and erythropoietin on erythroid progenitor cells
Authors: Ohneda Osamu , Yanai Nobuaki , Obinata Masuo 
Published: April 2021

ABSTRACT
Mutations at the murine dominant-white spotting locus (W) (c-Jtir) affect various aspects of hematopoiesis. We have made antibodies against c-Kit with the synthetic peptides deduced from the murine c-kit gene and examined the role of c-Kit in erythropoiesis. The antibody inhibited the stromal cell-dependent large colony formation of the erythroid progenitors. In the culture of erythropoietin-responsive erythroid progenitors of the anemia-inducing Friend virus-infected mouse spleen, the antibody inhibited only proliferation, but not differentiation of the progenitor cells. The inhibition was effective only at the early phase (within 6 hours after erythropoietin addition) before the cells start to proliferate induced by erythropoietin. During the early phase, erythropoietin down-regulated c-kit gene expression. These results suggest a mechanism of combined action of c-Kit with erythropoietin on the lineage-restricted erythroid progenitor cells.
Induction of dorsal and ventral mesoderm by ectopically expressed Xenopus basic fibroblast growth factor
Authors: Kimelman David , Maas Adolf 
Published: April 2021

ABSTRACT
Peptide growth factors from the fibroblast growth factor (FGF) and transforming growth factor-β families are likely regulators of mesoderm formation in the early Xenopus embryo. Although basic FGF is found in the Xenopus embryo at the correct time and at sufficient concentrations to suggest that it is the FGF-type inducer, the lack of a secretory signal sequence in the basic FGF peptide has raised questions as to its role in the inductive process. We show here that Xenopus basic FGF can ectopically induce mesoderm when translated from injected synthetic RNA within the cells of a Xenopus embryo. Basic FGF produced in this manner is able to induce the formation of both dorsal and ventral mesoderm with the type of mesoderm formed dependent on the inherent dorsal-ventral polarity of the animal hemisphere. Surprisingly, although Xenopus basic FGF produced from the injected mRNA has a potent mesodermalizing effect on animal hemisphere cells, virtually no phenotypic effect is observed with intact embryos. These results suggest that the role of Xenopus basic FGF is to specify the size of the marginal zone, and synergistically with a dorsally localized prepatterning signal, to initially establish the dorsal-ventral axis of the mesoderm.
Expression of XMyoD protein in early Xenopus laevis embryos
Authors: Hopwood N. D. , Pluck A. , Gurdon J. B. , Dilworth S. M. 
Published: April 2021

ABSTRACT
A monoclonal antibody specific for Xenopus MyoD (XMyoD) has been characterized and used to describe the pattern of expression of this myogenic factor in early frog development. The antibody recognizes an epitope close to the N terminus of the products of both XMyoD genes, but does not bind XMyfS or XMRF4, the other two myogenic factors that have been described in Xenopus. It reacts in embryo extracts only with XMyoD, which is extensively phosphorylated in the embryo. The distribution of XMyoD protein, seen in sections and whole-mounts, and by immunoblotting, closely follows that of XMyoD mRNA. XMyoD protein accumulates in nuclei of the future somitic mesoderm from the middle of gastrulation. In neurulae and tailbud embryos it is expressed specifically in the myotomal cells of the somites. XMyoD is in the nucleus of apparently every cell in the myotomes. It accumulates first in the anterior somitic mesoderm, and its concentration then declines in anterior somites from the tailbud stage onwards.
Distribution analysis of transferred donor cells in avian blastodermal chimeras
Authors: Watanabe M. , Kinutani M. , Naito M. , Ochi O. , Takashima Y. 
Published: April 2021

ABSTRACT
Blastodermal chimeras were constructed by transferring quail cells to chick blastoderm. Contribution of donor cells to host were histologically analyzed utilizing an in situ cell marker. Of the embryos produced by Injection of stage Xl-XIII quail cells into stage XI-2 chick blastoderm, more than 50 percent were definite chimeras. The restriction on the spatial arrangement of donor cells was induced by varying the stage of host. Ectodermal chimerism was limited to the head region and no mesodermal chimerism was shown when the quail cells were injected into stage XI-XIII blastoderm. Mesodermal and ectodermal chimerisms were limited to the trunk, not to the head region, when the quail cells were injected into the stage XIV-2 blastoderm. In these chimeras, however, some of the injected quail cells formed ectopic epidermal cysts. Consequently, the stage XIV-2 blastoderm may become intolerant of the injected cells. Our results suggest that it is possible to obtain chimeras that have chimerism limited to a particular germ layer and region by varying the stage of donor cell injection. Injected quail cells contributed to endodermal tissues and primordial germ cells regardless of the injection site. The quail-chick blastodermal chimeras could be useful in the production of a transgenic chicken and in the investigation of immunological tolerance.
Evidence for a highly selective RNA transport system and its role in establishing the dorsoventral axis of theDrosophilaegg
Authors: Cheung Hung-Kam , Serano Thomas L. , Cohen Robert S. 
Published: April 2021

ABSTRACTThe specification of cell fates along the dorsoventral axis of the Drosophila embryo is dependent on the asymmetric distribution of proteins within the egg and within the egg’s outer membranes. Such asymmetries arise during oogenesis and are dependent on multiple cell-cell interactions between the developing oocyte and its neighboring somatic follicle cells. The earliest known such interaction involves the generation of a signal in the oocyte and its reception in the follicle cells lying on the dorsal surface of the oocyte at ∼ stage 10 of oogenesis. Several independent lines of investigation indicate that the fs(1)K10 (K10) gene negatively regulates the synthesis of the signal in the oocyte nucleus. Here we present data that indicate that the accumulation of K10 protein in the oocyte nucleus is a multistep process involving: (1) the synthesis of K10 RNA in nurse cells, (2) the rapid transport of K10 RNA from nurse cells into the oocyte, (3) the localization of K10 RNA to the anterior margin of the oocyte, and (4) K10 protein synthesis and localization. K10 RNA is transported into the oocyte continuously beginning at ∼ stage 2. This indicates a high degree of selectivity in transport, since most RNAs synthesized in stage 2 and older nurse cells are stored there until stage 11, when nurse cells donate their entire cytoplasm to the oocyte. The sequences responsible for the early (pre-stage 11) and selective transport of K10 RNA into the oocyte map to the 3′ transcribed non-translated region of the gene. None of the other identified genes involved in dorsoventral axis formation are required for K10 RNA transport. Two such other genes, cappuccino (capu) and spire (spir) are, however, required for the subsequent localization of K10 RNA to the oocyte’s anterior end.
Inducible cell ablation inDrosophilaby cold-sensitive ricin A chain
Authors: Moffat Kevin G. , Gould Jane H. , Smith Hazel K. , O’Kane Cahir J. 
Published: April 2021

ABSTRACTWe have developed a system for temperature-inducible killing of specific cells in the fruitfly Drosophila melanogaster. The system overcomes many of the limitations of existing cell ablation methods and is in principle applicable to any non-homeothermic eukaryote. Temperature-sensitive and cold-sensitive mutations in the ricin toxin A chain (RTA) of castor bean were generated in yeast. One cold-sensitive mutation, RAcs2, produced temperature-dependent ablation of eye cells in Drosophila when expressed under control of the eye-specific sev enhancer. At 29°C, cell death was observed within 7 hours in the developing eye and no obvious toxic effects were observed elsewhere; at 18°C, extremely low toxicity was observed. DNA sequencing of RAcs2 revealed a single amino acid substitution in the RTA active site cleft.
A quantitative and interspecific test for biological activity of anti-Müllerian hormone: the fetal ovary aromatase assay
Authors: Clemente Nathalie Di , Ghaffari Sarah , Pepinsky R. B. , Pieau C. , Josso Nathalie , Cate R. L. , Vigier B. 
Published: April 2021

ABSTRACTAnti-Müllerian hormone (AMH), also known as Müllerian-inhibiting substance or factor, has previously been shown to sex-reverse the steroidogenic pattern of fetal mammalian ovaries through repression of aromatase biosynthesis. Study of the ontogeny of the response of cyclic AMP-stimulated aromatase activity of rat fetal ovaries to AMH has allowed us to develop a quantitative biossay for the hormone. Linear responses as a function of the logarithm of AMH concentration were observed over ranges of 0.2 -7.5 μg/ml for the bovine protein and 0.15 -2 μg/ml for the human protein, with a maximal decrease in aromatase activity of 90% for both proteins. Under the same in vitro conditions, AMH treatment did not affect cyclic AMP-stimulated fetal rat testicular aromatase activity. Partially purified chick AMH also decreased rat ovarian aromatase activity, allowing us to use this test to study AMH ontogeny in chick gonads. Analysis of the species specificity of AMH repression of ovarian aromatase activity indicated that turtle and rat fetal ovaries responded to AMH of other vertebrate classes, whereas aromatase activity of chick embryo ovaries could be repressed only by the homospecific hormone.
Fgf-4expression during gastrulation, myogenesis, limb and tooth development in the mouse
Authors: Niswander Lee , Martin Gail R. 
Published: April 2021

ABSTRACTFgf-4, initially isolated as a transforming gene from human tumors, is a member of the Fibroblast Growth Factor (FGF) family. It has previously been shown by northern blot hybridization analysis to be expressed in teratocarcinoma and embryonic stem cells, suggesting that it plays a role in embryonic development. We have carried out an RNA in situ hybridization analysis of Fgf-4 expression in the developing mouse embryo, from fertilization through the 14th day of gestation (E14.5). Our results show that Fgf-4 RNA is first detected at the late blastocyst stage in cells that give rise to all of the embryonic lineages (inner cell mass cells). During the early stages of gastrulation, expression becomes restricted to the primitive streak where mesoderm and definitive endoderm are formed. Expression continues in the distal (rostral) two-thirds of the streak through approx. E10, and then is detected in the tail bud, which replaces the streak as the primary source of mesoderm. Additional sites of expression are found after the three primary germ layers are established and organogenesis begins. Fgf-4 RNA is detected transiently in the branchial arch units, the somitic myotome, the apical ectodermal ridge of the developing limb bud and the tooth bud, suggesting that the gene has multiple roles during embryogenesis. These results are compared with the expression patterns of other FGF genes. Taken together, the data suggest that individual members of the gene family are expressed sequentially in developmental pathways such as mesoderm formation and myogenesis, and play a role in specific epithelial-mesenchymal interactions.
Altered mitotic domains reveal fate map changes in Drosophila embryos mutant for zygotic dorsoventral patterning genes
Authors: Arora Kavita , Nüsslein-Volhard Christiane 
Published: April 2021

Abstract
The spatial and temporal pattern of mitoses during the fourteenth nuclear cycle in a Drosophila embryo reflects differences in cell identities. We have analysed the domains of mitotic division in zygotic mutants that exhibit defects in larval cuticular pattern along the dorsoventral axis. This is a powerful means of fate mapping mutant embryos, as the altered position of mitotic domains in the dorsoventral pattern mutants correlate with their late cuticular phenotypes.
In the mutants twist and snail, which fail to differentiate the ventrally derived mesoderm, mitoses specific to the mesoderm are absent. The lateral mesectodermal domain shows a partial ventral shift in twist mutants but a proportion of ventral cells do not behave characteristically, suggesting that twist has a positive role in the establishment of the mesoderm. In contrast, snail is required to repress mesectodermal fates in cells of the presumptive mesoderm. In the absence of both genes, the mesodermal and the mesectodermal anlage are deleted.
Mutations at five loci delete specific pattern elements in the dorsal half of the embryo and cause partial ventralization. Mutations in the genes zerkniillt and shrew affect cell division only in the dorsalmost cells corresponding to the amnioserosa, while the genes tolloid, screw and decapentaplegic (dpp) affect divisions in both the prospective amnioserosa and the dorsal epidermis. We demonstrate that in each of these mutants dorsally placed mitotic domains are absent and this effect is correlated with an expansion and dorsal shift in the position of more ventral domains. The loss of activity in each of the five genes results in qualitatively similar alterations in the mitotic pattern; mutations with stronger ventralizing phenotypes affect increasingly greater subsets of the dorsal cells. Double mutant analysis indicates that these genes act in a concerted manner to specify dorsal fates. The correlation between phenotypic strength and the progressive loss of dorsal pattern elements in the ventralized mutants, suggests that one of these gene products, perhaps dpp, may provide positional information in a graded manner.
An early marker of axial pattern in the chick embryo and its respecification by retinoic acid
Authors: Sundin Olof , Eichele Gregor 
Published: April 2021

Abstract
Chick Ghox 2.9 protein, a homeodomain-contaming polypeptide, is first detected in the mid-gastrula stage embryo and its levels increase rapidly in the late gastrula. At this time, the initially narrow band of expression along the primitive streak expands laterally to form a shield-like domain that encompasses almost the entire posterior region of the embryo and extends anteriorly as far as Hensen’s node. We have found that this expression domain co-localizes with a morphological feature that consists of a stratum of refractile, thickened mesoderm. Antibody-staining indicates that Ghox 2.9 protein is present in all cells of this mesodermal region. In contrast, expression within the ectoderm overlying the region of refractile mesoderm varies considerably. The highest levels of expression are found in ectoderm near the streak and surrounding Hensen’s node, regions that recent fate mapping studies suggest are primarily destined to give rise to neurectoderm.
At the definitive streak stage (Hamburger and Hamilton stage 4) the chick embryo is especially sensitive to the induction of axial malformations by retinoic acid. Four hours after the treatment of definitive streak embryos with a pulse of retinoic acid the expression of Ghox 2.9 protein is greatly elevated. This ectopic expression occurs in tissues anterior to Hensen’s node, including floor plate, notochord, presumptive neural plate and lateral plate mesoderm, but does not occur in the anteriormost region of the embryo. The ectopic induction of Ghox 2.9 is strongest in ectoderm, and weaker in the underlying mesoderm. Endoderm throughout the embryo is unresponsive. At stage 11, Ghox 2.9 is normally expressed at high levels within rhombomere 4 of the developing hindbrain. In retinoic-acid-treated embryos which have developed to this stage, typical rhombomere boundaries are largely absent. Nevertheless, Ghox 2.9 is still expressed as a discrete band, but one that is widened and displaced to a more anterior position.