bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental progression of Gpd expression from the inactive X chromosome of the virginia opossum
Authors: Samollow Paul B. , Robinson Edwards S. , Ford Allen L. , Vandeberg John L. 
Published: May 2005

AbstractMetatherian (marsupial) mammals possess a non‐random form of X‐chromosome inactivation in which the paternally‐derived X is always the one inactivated. To examine the progression of X‐linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded Gpd gene products in heterozygous female Virginia opossums (Didelphis virginiana) across a moior portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post‐partum development, expression of the paternal Gpd allele had not attained the adult, tissue‐specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch‐life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpdgene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) maior changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue‐specific manner. © 1995 Wiley‐Liss, Inc.
Cell mixing during early epiboly in the zebrafish embryo
Authors: Wilson Ellen T. , Cretekos Chris J. , Helde Kathryn Ann 
Published: May 2005

AbstractDescendants of early blastomeres in the zebrafish come to populate distinctive regions of the fate map. We present a model suggesting that the distribution of cells in the early gastrula (the fate map stage) results from the passive response of cells to reproducible forces that change the overall shape of the blastoderm just prior to gastrulation. We suggest that one of the morphogenetic changes that accompanies epiboly, the upward doming of the yolk cell into the overlying blastoderm, could be responsible for cell mixing. In support of the model, we show that the timing, extent, and directions of cell mixing in the embryo accurately reflect the expectations of the model. Finally, we show that one portion of the gastrula, a marginal region that later gives rise to many of the mesendodermal derivatives, experiences little cell mixing during the doming process. As a result, this region in the gastrula is populated by the descendants of the subset of the early blastomeres that were originally at the margin. The finding that cytoplasm initially at the edge of the 1‐celled blastodisc is transmitted specifically to mesendodermal precursors at the fate map stage raises the possibility that maternal determinants may contribute to initiation of embryonic patterning in the zebrafish embryo. © 1995 Wiley‐Liss, Inc.
Allocation of epiblast cells to germ layer derivatives during mouse gastrulation as studied with a retroviral vector
Authors: Carey Frederick J. , Linney Elwood A. , Pedersen Roger A. 
Published: May 2005

AbstractThe embryonic ectoderm, or epiblast, is the source of the three primary germ layers that form during gastrulation in the mouse embryo. Previous studies have investigated the fate of epiblast cells in early gastrulation stages using clonal analysis of cell lineage and in late gastrulation stages using transplantation of labeled grafts. In this study, we studied the fate of late gastrulation stage epiblast using a clonal analysis based on a retroviral vector encoding theEscherichia coli lacZgene. We found that by reducing the volume of viral suspension injected into each embryo, it was possible to achieve single infectious events. Our analysis of 20 embryos singly infected at the late streak stage and 21 at the head fold stage revealed clonal descendants in only a single germ layer in each embryo. These results indicate that allocation of epiblast progenitors to a single germ layer fate has occurred by late gastrulation in mouse embryos. © 1995 Wiley‐Liss, Inc.
Cloning, sequencing, and expressional analysis of the chick homologue of follistatin
Authors: Connolly D. J. , Patel K. , Seleiro E. A. P. , Wilkinson D. G. , Cooke J. 
Published: May 2005

AbstractFollistatin, a secreted glycoprotein, has been shown to act as a potent neural inducer during early amphibian development. The function of this protein during embryogenesis in higher vertebrates is unclear, and to further our understanding of its role we have cloned, sequenced, and performed an in‐depth expressional analysis of the chick homologue of follistatin. In addition we also describe the expression pattern of activin βA and activin β B, proteins that have previously been shown to be able to interact with follistatin. In this study we show that the expression of follistatin and the activins do not always overlap. Follistatin was first detected in Hensen's node and subsequently in the region described by Spratt [1952] as the neuralising area. In older embryos it was also expressed in a highly dynamic manner in the hind‐brain as well as in the somites. We also present evidence that follistatin may have a later role in the resegmentation of the somites. We were unable to detect the expression of activin βA during early embryogenesis, whereas activin βB was first expressed in the extending primitive streak and subsequently in the neural folds. The results from this study are consistent with a role for follistatin in neural induction but suggest it has additional functions unrelated to its inhibitory actions on activins. © 1995 Wiley‐Liss, Inc.
Ventral mesodermal patterning in Xenopus embryos: Expression patterns and activities of BMP‐2 and BMP‐4
Authors: Hemmati‐Brivanlou Ali , Thomsen Gerald H. 
Published: May 2005

AbstractWe provide a comparative analysis of the expression patterns and ventral mesoderm‐inducing properties of Xenopus BMP‐2 and BMP‐4. Transcripts for BMP‐2 and BMP‐4 are maternally stored in eggs, and zygotic expression of these genes is uniform in the ectoderm and mesoderm in late blastulae. During gastrulation, BMP‐2 is expressed at a low level throughout the ectoderm and marginal zone, but at early neurula stages a patch of dorso‐anterior cells displays enhanced expression. In contrast, BMP‐4 transcripts are restricted to the ventrolateral marginal zone during gastrulation, and in late gastrula and early neurula BMP‐4 is expressed in the epidermis but not the neural plate. At post‐neurula stages, BMP‐2 and BMP‐4 transcripts are associated with a variety of mesodermal structures, including the pharyngeal pouches, heart, blood island, and blastopore. At tailbud stages, BMP‐2 and BMP‐4 are expressed in neural tissues including the neural tube and brain. In mesoderm induction assays, BMP‐2 and BMP‐4 induce Xhox3, an early ventral‐posterior mesoderm marker, and larval βT1 globin, a marker for red blood cells. Induction of red blood cells in response to BMP‐4 was demonstrated by staining with a hemoglobin‐specific reagent. Little is known about factors that induce hematopoietic lineages in vertebrates, and these results provide evidence linking BMP activity and blood differentiation. Globin induction by BMP‐2 and BMP‐4 is blocked by co‐expression of a dominant‐negative activin receptor, suggesting that either endogenous activin signals are required for BMP‐mediated induction, or that the trancated activin receptor interferes with signaling by BMP receptors. In assays on marginal zone explants, we demonstrate that BMP‐4 respecifies dorsal mesoderm to form ventral mesoderm, consistent with its ability to induce blood and to ventralize embryos. BMP‐2, however, does not display such activity. The findings extend and support evidence that BMP‐2 and BMP‐4 function in ventral mesoderm induction and patterning in Xenopus. Our data furthermore high light the multiple functions these factors fulfill during early vertebrate embryogenesis. © 1995 Wiley‐Liss, Inc.
Expression of HGF/SF, HGFI/MSP, and c‐met suggests new functions during early chick development
Authors: Théary Clotilde , Sharpe Melanie J. , Batley Sarah J. , Stern Claudio D. , Gherardi Ermanno 
Published: May 2005

AbstractWe report the cloning of full‐length cDNAs for a plasminogen‐related growth factor, hepatocyte growth factor/scatter factor (HGF/SF), its tyrosine kinase receptor, c‐met, and a close member of the same family, hepatocyte growth factor‐like/macrophage stimulating protein (HGFI/MSP), from the chick. We have used these cDNAs to provide the first report of the expression of this family of growth factors and the c‐met receptor at early stages of vertebrate development. RNAase protection and wholemount in situ hyb ridization were used on chick embryos between formation of the primitive streak and early organogenesis. We find patterns of expression for HGF/SF and its receptor c‐met consistent with their known roles in ep ithelial‐mesenchymal transformation and angiogenesis. In addition, these genes and HGFI/MSP are expressed in discrete locations within developing somites, suggesting a role in paraxial mesodermal development. Very strong and early expression of HGF/SF in the elevating limb buds suggests its involvement in limb outgrowth. HGFI/MSP is expressed in the notochord and then in the prospective floor plate region and could play a role in development of the neural tube. Interestingly, c‐met is often more closely as sociated with HGFI/MSP than with its known ligand, HGF/SF, raising the possibility that c‐met expression may be induced by HGFI/MSP. © 1995 Wiley‐Liss, Inc.
Widespread expression of the eve1 gene in zebrafish embryos affects the anterior‐posterior axis pattern
Authors: Barro Ousmane , Vriz Sophie , Joly Jean‐Stephane , Joly Claire , Condamine Hubert , Boulekbache Habib 
Published: May 2005

AbstractThe zygotic expression of the evel gene is restricted to the ventral and laletul cells of the marginal zone. At later stages, the mRNAs are localized in the most posterior part of the extending tail tip. An evel clone (pcZf14), containing a poly‐A tail, has been isolated. In order to address evel gene function, pcZf14 transcript injections into zebrafish embryos have been performed. The injection into uncleaved eggs of a synthetic evel mRNA (12 pg), which encodes a protein of 28 kd, produces embryos with anterior‐posterior (A‐P) axis defects and the formation of additional axial structures. The first category of 24 h phenotypes (87%) mainly displays a gradual decrease in anterior structures. This is comparable to previous phenotypes observed following Xhox3 messenger injection either in Xenopus or in zebrafish that have been classified according to the index of axis deficiency (zf‐IAD). These phenotypes result in anomalies of the development of the neural keel, from microphthalmia to acephaly. The second category (13%) corresponds to the phenotypes described above together with truncal or caudal supernumerary structures. Additional truncal structures are the most prominent of these duplicated phenotypes, displaying a “zipper” shape of axial structures including neural keels and noto‐chords. Caudal duplication presents no evident axis supernumerary structures. The observation of these phenotypes suggests an important role for the evel gene in mesodermal cell specification and in the development of the posterior region, and more particularly of the most posterior tail tip where endogenous eve1 messengers are found. © 1995 Wiley‐Liss, Inc.
Involvement of Wnt1 and Pax2 in the formation of the midbrain‐hindbrain boundary in the zebrafish gastrula
Authors: Kelly Gregory M. , Moon Randall T. 
Published: May 2005

AbstractThe secreted signalling molecule encoded by the wntl gene and the paired box‐containing pax2 gene are thought to play an integral role in patterning the zebrafish rostral nervous system. Using a double‐label analysis, we compare the expression patterns of wnt1 RNA and pax2 protein during zebrafish embryogenesis to determine whether they were expressed in identical or overlapping patterns in individual embryos. During gastrulation, wntl RNA was detected in a pattern similar but not identical to the pax2 protein. Later, wntl and pax2 co‐localize to the midbrain‐hindbrain boundary. Exogenous retinoic acid, a teratogen that is known to affect the formation of the midbrain‐hindbrain boundary, has a profound affect on both wntl and pax2 expression at gastrulation. Furthermore, when pax2 is overexpressed in zebrafish embryos, the wntl pattern of expression expands ventrally in the prospective rostral neuroepithelium. Despite the widespread and random distribution of exogenous pax2 RNA, it alone is unable to induce wntl expression in other ec‐topic sites. These results are consistent with the coordinate expression of wntl and pax2 being in a pathway responsible for establishing the midbrain‐hindbrain boundary and support the earlier interpretation that pax2 may regulate wntl expression [Krauss et al., 1992], although only in a subset of embryonic cells. These data suggest that a predisposition for the regionalization of the central nervous system exists at gastrulation. © 1995 Wiley‐Liss, Inc.
Involvement of differential gene expression and mRNA stability in the developmental regulation of the hsp 30 gene family in heat‐shocked Xenopus laevis embryos
Authors: Ohan Nicholas W. , Heikkila John J. 
Published: May 2005

AbstractFour complete hsp 30 genes have been isolated from Xenopus laevis: hsp 30A, hsp 30B (a pseudogene), hsp 30C, and hsp 30D. The hsp 30A and hsp 30C genes are first heat inducible at the early tailbud stage, as determined by RNase protection and RT‐PCR assays. In this study, we determined by RT‐PCR that the hsp 30D gene was first heat inducible (33oC for 1 h) at the mid‐tailbud stage, approximately 1 day later in development than hsp 30A and hsp 30C. Furthermore, using Northern blot analysis, we detected the presence of very low levels of hsp 30 mRNA at the heat‐shocked late blastula stage. The relative levels of these pre‐tailbud (PTB) hsp 30 mRNAs increased at the gastrula and neurula stage followed by a dramatic enhancement in heat shocked tail‐bud and tadpole stage embryos (50‐ to 100‐ fold relative to late blastula). Interestingly, treatment of blastula or gastrula embryos at high temperatures (37oC for 1 h) or with the protein synthesis inhibitor, cycloheximide, followed by heat shock, led to enhanced accumulation of the pre‐tailbud (PTB) hsp 30 mRNAs. hsp 70, hsp 87, and actin messages were not stabilized at high temperatures or by cycloheximide treatment. Finally, hsp 30D mRNA was not detected by RT‐PCR analysis of cycloheximidetreated, heat‐shocked blastula stage embryos, confirming that it is not a member of the PTB hsp 30 mRNAs. This study indicates that differential gene expression and mRNA stability are involved in the regulation of hsp 30 gene expression during early Xenopus laevis development. © 1995 Wiley‐Liss, Inc.
Transmission‐ratio distortion of X chromosomes among male offspring of females with skewed X‐inactivation
Authors: Naumova A. K. , Olien L. , Bird L. M. , Slamka C. , Fonseca M. , Verner A. E. , Wang M. , Leppert M. , Morgan K. , Sapienza C. 
Published: May 2005

AbstractWe have begun a search for heritable variation in X‐chromosome inactivation pattern in normal females to determine whether there is a genetic effect on the imprinting of X‐chromosome inactivation in humans. We have performed a quantitative analysis of X‐chromosome inactivation in lymphocytes from mothers in normal, three‐generation families. Eight mothers and 12 grandmothers exhibited evidence of highly skewed patterns of X‐chromosome inactivation. We observed that the male offspring of females with skewed X‐inactivation patterns were three times more likely to inherit alleles at loci that were located on the inactive X chromosome (Xi) than the active X chromosome (Xa). The region of the X chromosome for which this phenomenon was observed extends from XP11 to ‐Xq22. We have also examined X‐chromosome inactivation patterns in 21 unaffected mothers of male bilateral sporadic retinoblastoma patients. Six of these mothers had skewed patterns of X‐chromosome inactivation. In contrast to the tendency for male offspring of skewed mothers from nondisease families to inherit alleles from the inactive X chromosome, five of the six affected males inherited the androgen receptor alleles from the active X chromosome of their mother. © 1995 Wiley‐Liss, Inc.
Expression of X‐linked genes in androgenetic, gynogenetic, and normal mouse preimplantation embryos
Authors: Latham Keith E. , Rambhatla Lakshmi 
Published: May 2005

AbstractA quantitative RT‐PCR approach has been used to examine the expression of a number of X‐linked genes during preimplan‐tation development of normal mouse embryos and in androgenetic and gynogenetic mouse embryos. The data reveal moderately reduced expression of the Prps1, Hprt, and Pdha1 mRNAs in androge‐netic eight‐cell and morula stage embryos, but not in androgenetic blastocysts. Pgk1 mRNA abundance was severely reduced in androgenones at the eight‐cell and morula stages and remained reduced, but to a lesser degree, in androgenetic blastocysts. These data indicate that paternally inherited X chromosomes are at least partially repressed in androgenones, as they are in normal XX embryos, and that the degree of this repression is chromosome position‐dependent or gene‐dependent. Gynogenetic embryos expressed elevated amounts of some mRNAs at the morula and blas‐tocyst stages, indicative of a delay in dosage compensation that may be chromosome position‐dependent. The Xist RNA was expressed at a greater abundance in androgenones than in gynogenones at the eight‐cell and morula stages, consistent with previous studies. Xist expression was observed in both and rogenones and gynogenones at the blas‐tocyst stage. We conclude that the developmental arrest in early androgenones may be, in part, due to reduced expression of essential X‐linked genes, particularly those near the X inactivation center, where as the developmental defects of gyno‐genones and parthenogenones, by contrast, may be partially due to overexpression of X‐linked genes in extraembryonic tissues, possibly those far‐thest away from the X inactivation center. © 1995 Wiley‐Liss, Inc.
Identification of genes showing altered expression in preimplantation and early postimplantation parthenogenetic embryos
Authors: Mann Mellissa , Latham Keith E. , Varmuza Sue 
Published: May 2005

AbstractUniparental embryos have been instrumental in studying imprinting because contributions from the parental genomes can be determined unambiguously. In this study, we set out to identify imprinted genes showing differential expression between parthenogenetic and fertilized embryos during preimplantation and early postimplantation stages of development. We identified three genes‐apolipoprotein E, pyruvate kinase‐3, and protein phosphatase 1 gamma‐that represent excellent candidates for imprinted genes, based on the results of the differential screen, their function in differentiation and the cell cycle, and their location within imprinted chromosomal regions. In addition, two novel genes expressed in trophoblast were identified, 1661 and RA81. These genes, together with four known imprinted genes, H19, Igf2r, Igf2, and Snrpn, showed evidence of expression from both parental alleles in early stage embryos, indicating a role for postfertilization processes in regulating imprinted gene function. © 1995 Wiley‐Liss, Inc.
Expression of SGP‐1 mRNA in preimplantation mouse embryos
Authors: Cao Qiu Ping , Crain William R. 
Published: May 2005

AbstractIn a search for genes expressed in preimplantation mouse embryos that are important for the earliest steps in differentiation, we identified an abundant mRNA that codes for a sulfated glycoprotein, SGP‐1. The amount of this RNA rises ˜ 100‐fold during preimplantation development to a level approximately equal to that of β‐actin mRNA in blastocysts, although the level of these transcripts per cell remains fairly constant during these stages at ˜ 2,000–4,000 copies. An antisense RNA that is complementary to approximately the last one‐third of the message and contains an open reading frame of 455 nt was found in blastocysts at a 2–3‐fold higher level than the mRNA. In situ hybridization with sense and antisense riboprobes showed that both strands are distributed throughout the embryo. The abundance of the SGP‐1 mRNA indicates that the encoded protein may play an important role in the development of embryos, and the excess of antisense RNA raises the possibility of an unusual mechanism of regulating its expression. © 1995 Wiley‐Liss, Inc.
A Xenopus laevis gene encoding EF‐1αS, the somatic form of elongation factor 1α: Sequence, structure, and identification of regulatory elements required for embryonic transcription
Authors: Johnson Andrew D. , Krieg Paul A. 
Published: May 2005

AbstractTranscription of the Xenopus laevis EF‐1αS gene commences at the mid‐blastula stage of embryonic development and then continues constitutively in all somatic tissues. The EF‐1αS promoter is extremely active in the early Xenopus embryo where EF‐1αS transcripts account for as much as 40% of all new polyadenylated transcripts. We have isolated the Xenopus EF‐1αS gene and used microinjection techniques to identify promoter elements responsible for embryonic transcription. These in vivo expression studies have identified an enhancer fragment, located approximately 4.4 kb upstream of the transcription start site, that is required for maximum expression from the EF‐1αS promoter. The enhancer fragment contains both an octamer and a G/C box sequence, but mutation studies indicate that the octamer plays no significant role in regulation of EF‐1αS expression in the embryo. The presence of a G/C element in the enhancer and of multiple G/C boxes in the proximal promoter region suggests that the G/C box binding protein, Spl, plays a major role in the developmental regulation of EF‐1αS promoter activity. © 1995 Wiley‐Liss, Inc.