bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activity of a microinjected inducible murine hsp68 gene promoter depends on plasmid configuration and the presence of heat shock elements in mouse dictyate oocytes but not in two‐cell embryos
Authors: Bevilacqua Arturo , Mangia Franco 
Published: May 2005

AbstractAfter fertilization in the mouse, the zygotic genome is activated in two‐cell embryos by the spontaneous expression, among other genes, of the major inducible heat shock gene, hsp68, in the absence of heat‐inducibility of heat shock genes. To obtain information on this phenomenon, we have probed one‐ and two‐cell embryo's ability to express microinjected reporter DNA constructs, containing the Escherichia coli lacZ gene driven by promoters from early SV40 genes, the human ß‐actin gene, and the normal or HSE‐deleted mouse hsp68 gene. Activity of these promoters was also tested in mouse granulosa cells and dictyate oocytes, as a function of circular/linear construct configuration and occurrence of heat shock. The hsp68 promoter was heat‐inducible in both granulosa cells and oocytes. Its heat activation required the presence of HSEs and, in the oocytes, of construct linear configuration. In the embryos however, this promoter was expressed in dependently of the presence of HSEs and of construct configuration, and its activity was not affected by heat shock. When constructs with early SV40 and ß‐actin promoters were injected into one‐cell embryos, they appeared to be inactivated with the first embryonic cleavage, in agreement with previous observations [Wiekowski et ai., 1992]. By contrast, both normal and HSE‐deleted hsp68 promoters maintained their activity through the first cleavage, providing the first evidence of a gene escaping such transcriptional repression. Present results confirm previous findings on hsp68 expression during early mouse development, and suggest that this activation is mediated by a factor(s) other than HSF. © 1993Wiley‐Liss, Inc.
Development and tissue‐specific distribution of mouse small heat shock protein hsp25
Authors: Gernold M. , Knauf U. , Gaestel M. , Stahl J. , Kloetzel P.‐M. 
Published: May 2005

AbstractWe have investigated the developmental and tissue‐specific distribution of the mouse small hsp25 by immunohistology using an antibody that specifically identifies hsp25. Our analysis shows that the relative amount of hsp25 increases during embryogenesis. Through days 13–20 of embryogenesis, hsp25 accumulation is predominant in the various muscle tissues, including the heart, the bladder, and the back muscles. hsp25 is detectable also in neurons of the spinal cord and the purkinje cells. Furthermore analysis of the closely related α, B‐crystallin shows that in several tissues, including the bladder, the notochordal sheath and the eye lens both proteins are coexpressed. Our studies demonstrate that mammalian hsp25 accumulation is developmentally regulated during mouse embryogenesis and support the view of an important functional role of small heat shock proteins in normal cell metabolism. © 1993Wiley‐Liss, Inc.
Lack of concordance between heat shock proteins and the development of tolerance to teratogen‐induced neural tube defects
Authors: Finnell Richard H. , Van Waes Michael , Bennett Gregory D. , Eberwine James H. 
Published: May 2005

AbstractThe present study was undertaken to examine the role of heat shock response in the development of tolerance and cross‐tolerance in an in vivo murine model of teratogen‐induced neural tube defects. The experimental paradigm designed to address this question was to utilize inbred mouse strains that differed in their sensitivity to hyperthermia and valproic acid induced neural tube defects, subjecting the dams to subteratogenic pretreatments with either heat or valproic acid at two different timepoints during development prior to the administration of the teratogenic insult. A statistically significant reduction in the frequency of neural tube defects and/or embryolethality following a pretreatment in dams subsequently exposed to a teratogenic treatment was considered evidence for the induction of tolerance. This was observed in the SWV embryos exposed to the 38°C pretreatment at 8:06 and to embryos exposed to either pretreatment temperature at 8:10 priorto a teratogenic heat shock at 8:12. In the LM/Bc embryos, only the 41°C pretreatment at 8:06 induced thermotolerance. There was no evidence of tolerance induced in either mouse strain using valproic acid. On the other hand, cross‐tolerance was clearly demonstrated in this study, with a low temperature (41°C) pretreatment successfully protecting SWV fetuses from a subsequent teratogenic treatment with valproic acid, while valproic acid (200 mg/kg) was effective in reducing the risk of hyperthermia‐induced neural tube defects in the LM/Bc fetuses. In all instances, tolerance was induced in the absence of significant induction of hsp synthesis. The lack ofconcordance between hsps and thermotolerance suggests that some other factor(s) is involved in conferring thermotolerance on developing murine embryos. © 1993 Wiley‐Liss, Inc.
Modulation of mouse preimplantation development by epidermal growth factor receptor antibodies, antisense RNA, and deoxyoligonucleotides
Authors: Brice Eleanor C. , Wu Jie‐Xin , Muraro Raffaella , Adamson Eileen D. , Wiley Lynn M. 
Published: May 2005

AbstractTwo‐cell mouse preimplantation embryos were cultured for 48 h in four different reagents to modulate epidermal growth factor (EGF) receptor function. These were rabbit polyclonal and mouse monoclonal antibodies to EGF receptor, EGF receptor antisense RNA, and EGF receptor antisense deoxyoligonucleotides. Embryos were scored for two endpoints: onset of cavitation as a measure of trophectoderm differentiation and mean embryo cell number as a measure of cell proliferation. The consistent observations were that cavitation was significantly accelerated by antibodies and delayed by antisense RNA and antisense deoxyoligonucleotides. None of these reagents exerted a significant effect on mean embryo cell number, with one exception the polyclonal antibody. Our interpretation of these observations is that the antibody binding facilitated cavitation by mimicking natural ligand‐receptor binding and inducing the signal transduction cascade that is typical for the EGF receptor. In the case of antisense RNA or deoxyoligonucleotide, we propose that they delayed onset of cavitation by interfering with EGF receptor production. We hypothesize that during this period of development, EGF receptor is concerned predominantly with the regulation of differentiation more than with cell proliferation. © 1993Wiley‐Liss, Inc.
Possible autocrine/paracrine actions of insulin‐like growth factors during embryonic development: Expression and action of IGFs in undifferentiated P19 cells
Authors: Eicher Dorothea Jenkins , Moats‐Staats Billie M. , Stiles Alan D. , D'Ercole A. Joseph 
Published: May 2005

AbstractThe insulin‐like growth factors I and II (IGF I and II) and their cell surface receptors are expressed in the mammalian embryo and may function as autocrine or paracrine growth factors during early development. P19 embryonic carcinoma cells, derived from a 7.5 day mouse embryo, were used as a model for a functional study of the IGF system in post‐implantation embryogenesis. Undifferentiated P19 cells synthesized IGF I and II, the type I and II IGF receptors, and IGF binding proteins (IGF BP2, IGF BP3, and IGF BP4). P19 cells showed an increase in thymidine incorporation of 150% of control with a 4 hour incubation of IGF I (10 ng/ml) or IGF II (100 ng/ml) and an increase in cell viability compared to control cells during 24 hours of serum starvation. In both experiments IGF I was more potent than IGF II. Endogenous concentrations of IGF I and II in conditioned media were low compared to the doses of exogenous IGFs required for biologic effect, but nonetheless contributed significantly to baseline DNA synthesis, as demonstrated by inhibition of IGF actions with specific antibodies. Cell surface associated IGF BPs bound more radiolabeled IGF than IGF receptors, as determined by binding studies and affinity cross‐linking. IGF I and IGF II appeared to regulate production of IGF BP2, suggesting that the IGFs may regulate their own actions by altering the abundance of their binding proteins. © 1993Wiley‐Liss, Inc.
Rapid induction and clearance of TGFβ1 is an early response to wounding in the mouse embryo
Authors: Martin Paul , Dickson Marion C. , Millan Fergus A. , Akhurst Rosemary J. 
Published: May 2005

AbstractThe TGFβ family of growth factors has been implicated as playing a significant role in many aspects of embryonic morphogenesis, and also as a mediator of adult tissue repair processes. Unlike the situation in the adult, rissue repair in the embryo does not result in scarring, and it has been suggested that this might be due, in part, to reduced levels of growth factors, particularly TGFβ, at the wound site. We have examined the expression patterns of TGFβ genes following wounding of limb bud lesions in cultured Ell.5 mouse embryos. The timetable of wound closure was investigated by standard light and electron microscopy from the time of wounding until the lesion had re‐epithelialised 24 hours later. The expression of transcripts for each of the three TGFβ genes was examined at various time points during the healing process using radioactive in situ hybridisation to tissue sections and wholemount non‐radioactive in situ hybridisation to embryo pieces. Within l to 3 hours of wounding, transcripts encoding TGFβl were rapidly induced within the epithelial cells of the wound margin, particularly those cells at the ventral aspect of the wound. By 3 to 6 hours post‐wounding, TGFβl transcripts were detectable in the mesenchyme of the wound bed. No TGFβS induction was observed, and possible TGFβ2 induction was largely obscured by endogenous expression associated with pre‐cartilage mesenchymal condensation. Immunocytochemical analysis of tissue sections of the wound demonstrated a rapid induction of TGFβl protein within l hour post‐wounding, but also a subsequent rapid clearance of the protein from the wound site such that, by 18 hours post‐wounding, TGFβl levels had returned to near background. These data are discussed in terms of the molecular mechanisms underlying embryonic wound healing and the significance of the results to an understanding of scarring following adult tissue repair. © 1993Wiley‐Liss, Inc.
Use of a tomato mutant constructed with reverse genetics to study fruit ripening, a complex developmental process
Authors: Theologis Athanasios , Oeller Paul W. , Wong Lu‐min , Rottmann William H. , Gantz David M. 
Published: May 2005

AbstractFruit ripening is one of the most dramatic developmental transitions associated with extensive alteration in gene expression. The plant hormone ethylene is considered to be the causative ripening agent. Transgenic tomato plants were constructed expressing antisense or sense RNA to the key enzyme in the ethylene (C2H4) biosynthetic pathway, 1 ‐aminocyclopropane‐1‐carboxylate (ACC) synthase using the constitutive CaMV 35S and fruit specific E8 promoters. Fruits expressing antisense LE‐ACS2 RNA produce less ethylene and fail to ripen only when ethylene production is suppressed by more than 99% (>0.1 nl/g fresh weight). Ethylene production is considerably inhibited (50%) in fruits expressing sense LE‐ACS2 RNA. Antisense fruits accumulate normal levels of polygalacturonase (PG), ACC oxidase (pTOM13), E8, E17, J49, and phytoene desaturase (D2) mRNAs which were previously thought to be ethylene‐inducible. E4 gene expression is inhibited in antisense fruits and its expression is not restored by treatment with exogenous propylene (C3H6). Antisense fruits accumulate PG mRNA, but it is not translated. Immunoblotting experiments indicate that the PG protein is not expressed in antisense fruits but its accumulation is restored by propylene (C3H6) treatment. The results suggest that at least two signal‐transduction pathways are operating during tomato fruit ripening. The independent (developmental) pathway is responsible for the transcriptioncl activation of genes such as PG, ACC oxidase, E8, E17, D2, and J49. The ethylene‐dependent pathway is responsible for the transcriptional and posttranscriptional regulation of genes involved in lycopene, aroma biosynthesis, and the translatability of developmentally regulated genes such as PG. © 1993Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
© 1993Wiley‐Liss, Inc.
Uptake of antisense oligonucleotides and functional block of acetylcholine receptor subunit gene expression in primary embryonic neurons
Authors: Yu C. , Brussaard A. B. , Yang X. , Listerud M. , Role L. W. 
Published: May 2005

AbstractSeveral recent studies have used antisense oligonucleotides in the nervous system to probe the functional role of particular gene products. Since antisense oligonucleotide‐mediated block of gene expression typically involves uptake of the oligonucleotides, we have characterized the mechanism of this uptake into developing neurons from embryonic chickens. Antisense oligonucleotides (15 mers) added to the bathing media are taken up into the embryonic chicken sympathetic neurons maintained in vitro. A portion of the oligonucleotide uptake is temperature dependent and saturates at extracellular oligonucleotide concentrations ≥ 20 μM. This temperature sensitive, saturable component is effectively competed by single nucleotides of ATP and AMP and is reminiscent of receptor‐mediated endocytosis of oligonucleotides described in non‐neuronal cells. The efficiency of the oligonucleotide uptake system is dependent on the developmental stage of the animal but independent of the number of days that the neurons are maintained in vitro.Following the uptake of antisense oligonucleotides directed against ion channel subunit genes expressed by these neurons (nicotinic acetylcholine receptor subunit α3; nAChR α3), biophysical assays reveal that the functional expression of the target gene is largely blocked. Thus the number of wild type nAChR channels expressed is decreased by =80%–90%. Furthermore, following antisense deletion of α3, “mutant” nAChRs with distinct functional characteristics are expressed.In sum, these studies characterize the uptake of antisense oligonucleotide and demonstrate the functional block of specific gene expression in primary developing neurons. In addition, the functional studies emphasize the need for sensitive and specific assay following antisense deletion, since other homologous gene products may substitute for the targeted gene resulting in new phenotypes that are subtly different from wild type. © 1993Wiley‐Liss, Inc.
Opposite functions of Jun‐B and c‐jun in growth regulation and neuronal differentiation
Authors: Schlingensiepen Karl‐Hermann , Schlingensiepen Reimar , Kunst Mechthild , Klinger Ingrid , Gerdes Wilhelm , Seifert Wilfried , Brysch Wolfgang 
Published: May 2005

AbstractInduction of the jun‐B and/or c‐jun transcription factors is part of the immediate early response to diverse stimuli that induce alterations in cellular programs. While c‐jun is a protooncogene whose expression is required for induction of cell proliferation, jun‐B has recently been found to be induced by stimuli inducing differentiation in various cell lines. Furthermore, its expression is largely restricted to differentiating cells during embryogenesis. To determine the functional significance of these findings, we used antisense phosphorothioate oligodeoxynucleotides to inhibit expression of the two genes in proliferating and neuronally differentiating cells. While selective inhibition of c‐jun expression reduced proliferation rates, inhibition of jun‐B protein synthesis markedly increased proliferation in 3T3 fibroblasts, human mammary carcinoma cells and PC‐12 pheochromocytoma cells, suggesting jun‐B involvement in negative growth control. Neuronal differentiation of PC‐12 cells induced by nerve growth factor (NGF) was prevented by inhibition of jun‐B protein synthesis. PC‐12 cells not only failed to grow neurites but also remained in the proliferative state. Furthermore, in cultured primary neurons from rat hippocampus, inhibition of jun‐B expression, again, markedly reduced morphological differentiation. Conversely, inhibition of c‐jun protein synthesis enhanced morphological differentiation of both primary neurons and PC‐12 tumor cells. Thus, jun‐B expression is required for neuronal differentiation and its balance with c‐jun activity is involved in regulating key steps in proliferation and differentiation processes. © 1993Wiley‐Liss, Inc.
Juvenile hormone action to suppress gene transcription and influence message stability
Authors: Jones Grace , Venkataraman Venkateswar , Manczak Maria , Schelling Douglas 
Published: May 2005

AbstractProteins normally expressed in high abundance only at larval‐pupal metamorphosis in Trichoplusia ni were examined in a comparative analysis of the role and level of hormonal control of their expression. Some related proteins in the hemocyanin‐superfamily (i.e., an acidic protein [AJHSP1] and two basic proteins [BJHSP1, BJHSP2]) were shown by nuclear run‐on analysis to be specifically transcriptionally suppressed by juvenile hormone (JH), while transcription of another member of that family which is also metamorphosis‐associated (arylphorin) was not specifically sensitive to JH. The stability of the mRNA for those members transcriptionally down‐regulated by JH appeared to decrease under high JH conditions. While each protein was resorbed to some extent by the prepupal fat body, only the two basic proteins were quantitatively cleared from prepupal hemolymph. The JH‐sensitive proteins studied appear to be encoded in single copy genes not immediately juxtaposed in the genome. These and previous studies now permit a more comprehensive understanding of the different combinations of mechanisms involving transcription, mRNA stability, translation, and protein clearance that operate to regulate these metamorphosis‐associated proteins. © 1993Wiley‐Liss, Inc.
A murine CDC25/ras‐GRF‐related protein implicated in ras regulation
Authors: Chen Luping , Zhang Li‐jia , Greer Peter , Tung Pierre S. , Moran Michael F. 
Published: May 2005

AbstractA partial cDNA encoding a novel putative p2, ras guanine nucleotide release‐inducing factor (GRF), GRF2, was amplified from murine embryonic stem cells. The presumptive catalytic region of GRF2 is related to the yeast Ras GRF encoded by CDC25. GRF2 is 80% identical to murine CDC25Mm/ras‐GRF, but is more similar to yeast CDC25 than to other ras GRFs related to the Drosophila son of sevenless gene product. A 9‐kb GRF2 messenger RNA was highly expressed in brain, but GRF2‐specific antibodies recognized apparent GRF2 proteins in various mouse tissues in addition to brain. Thus GRF2 represents a novel widely‐expressed protein that is highly related to CDC25Mm/ras‐GRF, at least in its catalytic domain. Both GRF2 and CDC25Mm/ras‐GRF are expressed in murine embryonic stem cells, suggesting that different Ras activators may regulate ras‐dependent proliferation and differentiation in early mouse development. © 1993Wiley‐Liss, Inc.
Altered morphology of vegetative amoebae induced by increased expression of the Dictyostelium discoideum ras‐related gene rap1
Authors: Rebstein P. J. , Weeks G. , Spiegelman G. B. 
Published: May 2005

AbstractThe rap1 gene of Dictyostelium discoideum is a member of the ras‐gene superfamily of low molecular weight GTPase proteins. The rapl gene is expressed both during growth and development in D. discoideum. To examine the action of the Rapl protein in D. discoideum, the rap1 cDNA was expressed under the control of the inducible discoidin promoter. Treatment with conditioned media, which induces the discoidin promoter, increased Rap1 protein levels in vegetative cells approximately six fold. Overexpression of the Rapl protein correlated with the appearance of morphologically aberrant vegetative amoebae: cells were extensively spread and flattened. The distribution of F‐actin was altered in these cells, with an increase in actin staining around the cell periphery. Induction of the discoidin promoter by starvation in the rapl transformants also resulted in spread flat cells. When starved D. discoideum amoebae are refed with HL5 media, the cells rapidly respond by rounding up. By contrast, the rapl transformant cells showed a pronounced delay in rounding up. Rapid tyrosine phosphorylation of a p45 protein occurred in both control cells and the rapl transformant upon refeeding, implying that the signal transduction pathway leading to tyrosine phosphorylation remained functional in the rapl transformant. We propose that the Rapl protein functions in the regulation of cell morphology in D. discoideum. © 1993Wiley‐Liss, Inc.
Developmental requirements for the ecdysoneless (ecd) locus in Drosophila melanogaster
Authors: Henrich Vincent C. , Livingston Leon , Gilbert Lawrence I. 
Published: May 2005

AbstractThe ecdysoneless locus in Drosophila melanogaster has been defined previously by a single conditional mutation, I(3)ecd1, that causes an ecdysteroid deficit and larval death at the restrictive temperature, 29°C, although the primary role of the mutation in developmental processes has been unclear. Gene dosage and complementation studies reported here for ecd1 and five nonconditional lethal alleles indicate that the ecd locus plays prezygotic and postzygotic roles essential for normal embryonic development, the successful completion of each larval molt, adult eclosion, and female fertility. The ecd locus is also required for normal macrochaete differentiation. For each observed phenotype, the severity of mutational effects was correlated with ecd mutant genotypes. In all cases, ecd1 homozygotes were least affected. Mutants heteroallelic for ecd1 and any one of four nonconditional recessive mutations were more severely affected than ecd1 homozy‐gotes, revealing these as hypomorphic alleles. For all phenotypic effects, mutants heteroallelic for ecd1 and a dominant mutation (ecd3D) were most severely affected. These individuals died during embryogenesis at 29°C and developed no macrochaetes on the dorsal thorax when transferred to 29°C during the white prepupal stage. The ecd3D mutation also caused female semisterility in heterozygotes. Ecdysteroid regulation has been implicated previously in all the developmental processes disrupted by these ecd mutations except for macrochaete differentiation. © 1993 Wiley‐Liss, Inc.
Analysis of the subtelomeric regions of macronuclear gene‐sized DNA molecules of the hypotrichous ciliate Stylonychia lemnae: Implications for the DNA fragmentation process during macronuclear development?
Authors: Maercker Christian , Lipps Hans Joachim 
Published: May 2005

AbstractThe subtelomeric regions of macronuclear gene‐sized DNA molecules from Stylonychia lemnae were analyzed. The results obtained indicate that these regions show a highly ordered and common sequence organization: Immediately adjacent to the telomeric sequence a short inverted repeat sequence is found, followed by another 7–9 bp inverted repeat sequence at approximately position 40. A 10 bp consensus sequence found in the subtelomeric regions of all gene‐sized DNA molecules is found at approximately position 60 and in addition at about the same position palindromic sequences showing no homology to each other are localized. The biological significance of this sequence organization is discussed. © 1993Wiley‐Liss, Inc.