bluuebunny/crossref_metadata_2025_split huggingface dataset:
hsp23 and hsp26 exhibit distinct spatial and temporal patterns of constitutive expression in Drosophila adults
Authors: Marin Raquel , Valet Jean Paul , Tanguay Robert M. 
Published: May 2005

AbstractTo determine differences in the patterns of expression of Drosophila small heat shock proteins (shsp) during normal development in the absence of stress, proteins obtained from head, thorax and gonads of young (0–12 h, 3 days), middle‐aged (3–6 days) and 15‐ to 20‐day‐old adult flies were separated on SDS‐PAGE gels and blotted with monoclonal antibodies against hsp23 and hsp26. hsp23 was found in the heads and gonads of young males and females. In contrast, the maximum expression of hsp26 was seen in gonads of young flies, and it was only lightly detected in the brain. The expression of both proteins decreased as flies aged. This age‐related decrease was particularly striking for hsp23 in females. The immunoblot results obtained were complemented by immunostaining of thin parasagittal sections of whole fly bodies Hsp23 was found to be expressed in the brain, thoracic ganglion, fat body and gonads of young (0‐12 h) males and females. On the other hand, hsp26 was essentially detected in ovaries and testes of these young flies. The analysis of the tissue expression of both proteins demonstrate that each shsp has a distinct cellular localization. In the central nervous system, hsp23 and hsp26 were present in the neurocytes of the brain and the thoracic ganglion. In addition, hsp23 (but not hsp26) was also detected in the central neuropile of these two organs. In testis, hsp26 was localized in the cytoplasm of spermatocytes and, probably, in the spermatid bundles. In contrast, hsp23 was detected at the periphery of cells (membranes). In ovorioles of newborn females the expression of hsp26 was stronger, and the maximum expression of hsp23 was only reached in older (2 days and more) flies. These results demonstrate that each shsp possesses a specific spatial and temporal pattern of expression in adults of Drosophila. The distinct tissue‐specific and age‐dependent expression of hsp23 and hsp26 suggests that these two proteins may have different functions in crucial organs of Drosophila. © 1993Wiley‐Liss, Inc.
Tissue‐specific expression of heat shock proteins of the mouse in the absence of stress
Authors: Tanguay Robert M. , Wu Y. , Khandjian E. W. 
Published: May 2005

AbstractThe steady‐state levels of four members of the heat shock proteins families (HSP84, HSC73, HSP71, and HSP25) were examined by immunoblot analysis of several different tissues of young and adult mice in the absence of stress. These hsps were detected in all tissues but their level was variable. The levels of HSC73 and HSP84 varied only slightly between different tissues in either young or adult mice, with the exception of skin where these hsps were found in reduced amounts. In contrast, the stress‐inducible member of the HSP70 family, HSP71, was found to be expressed in all tissues but in amounts which differed by as much as two orders of magnitude between tissues. In general, the levels of both HSP71 and HSP25 were found to be tissue dependent, with higher levels found in tissues such as stomach, intestine, colon and bladder, tissues which are exposed to toxic environmental or metabolic products, and which may concentrate these substances by water resorption and/or be exposed to them for longer periods. The levels of HSP71 and HSP25 were generally positively correlated both in young and adult mice although this correlation was not found in certain tissues such as kidney, testes, and bone. Tissues of young mice contained lower amounts of HSP25 and HSP71 than were found in the same tissues from adults. We conclude that hsps are expressed in all tissues of the mouse in the absence of stress and that some organs, particularly those exposed to potentially toxic metabolites, show a higher level of expression of HSP71 and HSP25. © 1993Wiley‐Liss, Inc.
HSP86 and HSP84 exhibit cellular specificity of expression and co‐precipitate with an HSP70 family member in the murine testis
Authors: Gruppi Carol M. , Wolgemuth Debra J. 
Published: May 2005

AbstractThis study extends to the protein level our previous observations, which had established the stage and cellular specificity of expression of hsp86 and hsp84 in the murine testis in the absence of exogenous stress. Immunoblot analysis was used to demonstrate that HSP86 protein was present throughout testicular development and that its levels increased with the appearance of differentiating germ cells. HSP86 was most abundant in the germ cell population and was present at significantly lower levels in the somatic cells. By contrast, the HSP84 protein was detected in the somatic cells of the testis rather than in germ cells. The steady‐state levels of HSP86 and HSP84 paralleled the pattern of the expression of their respective mRNAs, suggesting that regulation at the level of translation was not a major mechanism controlling hsp90 gene expression in testicular cells. Immunoprecipitation analysis revealed that a 70‐kDa protein coprecipitated with the HSP86/HSP84 proteins in testicular homogenates. This protein was identified as an HSP70 family member by immunoblot analysis, suggesting that HSP70 and HSP90 family members interact in testicular cells. © 1993Wiley‐Liss, Inc.
Heat‐shock gene expression and cell cycle changes during mammalian embryonic development
Authors: Walsh David , Li Karen , Wass Jane , Dolnikov Alla , Zeng Frank , Zhe Li , Edwards Marshall 
Published: May 2005

AbstractSynchronized regulation of cell division during gastrulation is essential for the regional proliferation of cells and pattern formation of the early CNS. The neural plate and neuroectoderm cells are a rapidly dividing and differentiating population of cells with a unique and rapid heat‐shock response. Heat shock and the heat‐shock genes were studied during neural plate development in a whole rat embryo culture system at 9.5‐11.5 days. A lethal heat shock can cause cell death and severe developmental defects to the forebrain and eye during organogenesis. Heat shock can also result in acquired thermotolerance whereby cell progression is delayed at the G1/S and S/G2 boundaries of the cell cycle. This delay in cell cycle progression caused an overall lengthening of the cell cycle time of at least 2 hr. The heat shock genes may therefore function as cell cycle regulators in neuroectoderm induction and differentiation. The kinetics and expression of the hsp genes were examined in neuroectodermal cells by flow cytometry and Northern analysis. The levels of hsp mRNA 27, 71, 73, and 88 were identified following exposure at 42°C (nonlethal), 43deg;C (lethal) and 42deg;/43deg;C (thermotolerant) heat shock. Examination of hsp gene expression in the neural plate showed tight regulation in the cell cycle phases. Hsp 88 expression was enhanced at Go and hsp71 induction at G2 + M of the cell cycle. Cells exposed to a thermotolerant heat shock of 42deg;C induced hsp71 mRNA expression in all phases of the cell cycle with the mRNA levels of hsp27, 73, and 88 increased but relatively constant. Following a lethal heat shock, dramatic changes in hsp expression were seen especially enhanced hsp71 induction in late S phase. The regulated expression of hsps during the cell cycle at various phases could play a unique and important role in the fate and recovery of neuroectoderm cells during early mammalian embryo development. © 1993Wiley‐Liss, Inc.
The Xenopus platelet‐derived growth factor α receptor: cDNA Cloning and demonstration that mesoderm induction establishes the lineage‐specific pattern of ligand and receptor gene expression
Authors: Jones Susan Dana , Ho Lap , Smith James C. , Yordan Cristina , Stiles Charles D. , Mercola Mark 
Published: May 2005

AbstractWe have cloned the Xenopus PDGF α receptor cDNA and have used this clone, along with cDNA encoding PDGF A, to examine their expression pattern in Xenopus embryos and to determine the factors responsible for lineage specificity. Recombinant Xenopus α receptor expressed in COS cells exhibits PDGF‐A‐dependent tyrosine kinase activity. We find that receptor mRNA is present in cultured marginal zone tissue explants and in animal cap tissue induced to form mesoderm either by grafting to vegetal tissue or by treatment with recombinant activin A. In contrast, PDGF A mRNA is expressed in cultured, untreated animal cap tissue and is suppressed by mesoderm induction. These results suggest that ectodermally produced PDGF A may act on the mesoderm during gastrulation and that mesoderm induction establishes the tissue pattern of ligand and receptor expression. © 1993Wiley‐Liss, Inc.
Site of action of imprinted genes revealed by phenotypic analysis of parthenogenetic embryos
Authors: Varmuza Susannah , Mann Mellissa , Rogers Ian 
Published: May 2005

AbstractThe phenotypes of early postimplantation parthenogenetic embryos were examined. The spectrum of phenotypes suggested that three stages are adversely affected by imprinting—implantation, pregastrulation, and postgastrulation. Survival of parthenogenetic embryos past these developmental blocks can be improved but not completely overcome by experimental asynchrony. These results suggest that imprinting may be “leaky” at early stages. © 1993Wiley‐Liss, Inc.
Giα2 mediates the inhibitory regulation of adenylylcyclase in vivo: Analysis in transgenic mice with Giα2 suppressed by inducible antisense RNA
Authors: Moxham Christopher M. , Hod Yaacov , Malbon Craig C. 
Published: May 2005

AbstractThe role of the GTP‐binding regulatory protein (G‐protein) Giα2 in vivo was explored using transgenic mice in which the α‐subunit of Giα2 was suppressed by antisense RNA. Rat hepatoma FTO‐2B cells provide an ideal test system for constructs employing the expression vector pPCK‐AS, designed to express antisense RNA at birth under the control of the phosphoenolpyruvate carboxykinase (PEPCK) promoter. Cells transfected with the expression vector containing a sequence antisense to Giα2 (pPCK‐ASGiα2) displayed expression of RNA antisense to Giα2 that, like transcription of the PEPCK gene, was inducible by cyclic AMP. Expression of RNA antisense to Giα2 and suppression of the expression of Giα2, but not Gsa and Giα3, was observed in the transfected FTO‐2B cells. BDF1 mice carrying the transgene displayed suppression of Giα2 in liver and fat, two targets for tissue‐specific expression of the PEPCK gene. The loss of Giα2 in white adipocytes of transgenic mice resulted in 3.1‐fold elevation of basal cyclic AMP accumulation. Cyclic AMP accumulation in response to stimulation by epinephrine (10μM) was normal in adipocytes of transgenic mice, demonstrating no alteration in the stimulatory adenylylcyclase capacity in the Giα2‐deficient cells. The inhibitory adenylylcyclase pathway, in sharp contrast, was severely blunted in response to challenge by the inhibitory A1‐purinergic agonist, (−)R‐N6‐phenylisopropyladenosine. These studies illuminate a critical role of Giα2 in the inhibitory adenylylcyclase signaling pathway in vivo. © 1993Wiley‐Liss, Inc.
Creating a conditional mutation of Wnt‐1 by antisense transgenesis provides evidence that Wnt‐1 is not essential for spermatogenesis
Authors: Erickson Robert P. , Lai Li‐Wen , Grimes Judy 
Published: May 2005

AbstractWe have used mice transgenic for an antisense construct for Wnt‐1 to study the role of this gene in post‐meiotic sperm development. The human PGK‐2 promoter provided levels of Wnt‐1 antisense mRNA in testes in 5 transgenic lines greatly in excess of Wnt‐1 mRNA concentrations, and Wnt‐1 mRNA levels were greatly decreased in the lines, by 98% in three of them. There was a general correlation between copy number of the insert, levels of antisense RNA, and decreases in mRNA. There was little effect of the antisense transgene on fertility or testicular histology suggesting that normal levels of Wnt‐ 1 transcript are not essential for spermatogenesis. © 1993Wiley‐Liss, Inc.
Embryonic and fetal rat myoblasts express different phenotypes following differentiation in vitro
Authors: Pin Christopher L. , Merrifield Peter A. 
Published: May 2005

AbstractMyosin heavy chain (MHC) is encoded by a multigene family containing members which are expressed in developmental and fiber type‐specific patterns. In developing rats, primary (1°) and secondary (2°) myotjbes can be disfinguished by differences in MHC expression: 1° myotubes coexpress embryonic and slow MHC, while 2° myotubes initially express only embryonic MHC. We have used monoclonal antibodies which recognize the embryonic, slow, neonatal, and adult fast IIB/IIX MHCs to examine MHC accumulation in myoblasts obtained from hindlimbs of embryonic day (ED) 14 and ED 20 Sprague‐Dawley rats during differentiation in vitro. Embryonic myoblasts (ED 14), which develop into 1° myotubes in vivo, differentiate as myocytes or small myotubes (i.e., 1–4 nuclei) which express both embryonic and slow MHC. They do not accumulate detectable levels of neonatal or adult fast IIB/IIX MHC. Fetal myoblasts, which develop into secondary myotubes in vivo, fuse to form large myotubes (i.e., 10–50 nuclei) and express predominantly embryonic MHC at 3 days in culture. These myotubes accumulate neonatal and adult fast IIB/IIX isoforms of MHC and eventually contract spontaneously. In contrast to embryonic myotubes, they do not accumulate slow MHC. Our results demonstrate that embryonic and fetal rat myoblasts express different phenotypes in vitro and suggest that they represent distinct myoblast lineages similar to those previously described in chickens and mice. These two lineages may be responsible for the generation of distinct populations of 1° and 2° myotubes in vivo. © 1993Wiley‐Liss, Inc.
Pleiotropic effects of the Cardiac‐lethal gene in the axolotl (Ambystoma mexicanum)
Authors: Smith Steven C. , Armstrong John B. 
Published: May 2005

AbstractEmbryos of the axolotl affected with the cardiac‐lethal mutation form hearts that never begin to beat. A number of other traits characteristic of the mutant phenotype, including edema, underdeveloped gills, shorter stature, and aphagia (the inability to feed), were believed to be secondary effects of the absence of circulation. We have recently demonstrated that the pre‐cardiac mesoderm is directly affected by the c gene, making it unresponsive to normal inductive signals. In this study, we replaced part or all of the mutant pre‐cardiac mesoderm with wild‐type tissue, to produce embryos with normally beating hearts and circulation. As expected, most of the other mutant characteristics were also corrected. However, otherwise normal individuals remained aphagic. All embryos with beating hearts containing mutant tissue also suffered from an unexpected circulatory arrest some time after the onset of circulation. This apparently indicates that there are at least two tissues other than the myocardium which appear to be directly affected by the c gene. These previously unsuspected pleiotropic effects of the mutation may involve poorly‐characterized mesodermal‐neural crest inductive interactions and may also lead to a greater understanding of the link between congenital heart defects and feeding difficulties in humans. © 1993Wiley‐Liss, Inc.
Mechanism of action of developmentally regulated sea urchin inhibitor of eIF‐4
Authors: Jagus Rosemary , Huang Wun‐Ing , Hiremath Leena S. , Stern Brian D. , Rhoads Robert E. 
Published: May 2005

AbstractThe developmentally regulated inhibitor of eIF‐4 function found in unfertilized sea urchin eggs has been partially purified and its mechanism of action studied in vitro using purified recombinant eIF‐4α and cell‐free translation systems. The results demonstrate that although the phosphorylation of eIF‐4α is necessary to promote protein synthesis, it is not sufficient to maintain all aspects of eIF‐4 function. The egg inhibitor does not change eIF‐4α phosphorylation state. During the blockage of initiation caused by the egg inhibitor, eIF‐4α remains phosphorylated but accumulates in a 48S initiation intermediate. This suggests that the egg inhibitor functions by preventing the release of eIF‐4α from the small ribosomal subunit. The characteristics of the inhibitor in a reticulocyte translation system demonstrate that eIF‐4 activity is inhibited within 3–6 min. However, the inhibitor's characteristics in a mRNA‐dependent translation system contrast with this. Preincubation with the inhibitor for 5–25 min prior to the addition of mRNA does not prevent endogenous eIF‐4 from participating in translation but diminishes its ability to be reutilized, consistent with the accumulation of eIF‐4α on the small ribosomal subunit. The ribosomal localization of the inhibitor suggests that it could prevent eIF‐4α release by direct binding. The gradual inactivation of the inhibitor following fertilization indicates that it represents a component of a novel regulatory cascade that modulates eIF‐4 activity. © 1993 Wiley‐Liss, Inc.
Maturation hormone induced an increase in the translational activity of starfish oocytes coincident with the phosphorylation of the mRNA cap binding protein, eIF‐4E, and the activation of several kinases
Authors: Xu Zhe , Dholakia Jaydev N. , Hille Merrill B. 
Published: May 2005

AbstractThe stimulation of translation in starfish oocytes by the maturation hormone, 1‐methyladenine (1‐MA), requires the activation or mobilization of both initiation factors and mRNAs [Xu and Hille, Cell Regul. 1:1057, 1990]. We identify here the translational initiation complex, eIF‐4F, and the guanine nucleotide exchange factor for eIF‐2, eIF‐2B, as the rate controlling components of protein synthesis in immature oocytes of the starfish, Pisaster orchraceus. Increased phosphorylation of eIF‐4E, the cap binding subunit of the eIF‐4F complex, is coincident with the initial increase in translational activity during maturation of these oocytes. Significantly, protein kinase C activity increased during oocyte maturation in parallel with the increase in eIF‐4E phosphorylation and protein synthesis. An increase in the activities of cdc2 kinase and mitogen‐activated myelin basic protein kinase (MBP kinase) similarly coincide with the increase in eIF‐4E phosphorylation. However, neither cdc2 kinase nor MBP kinase phosphorylates eIF‐4E in vitro. Casein kinase II activity does not change during oocyte maturation, and therefore, cannot be responsible for the activation of translation. Treatment of oocytes with phorbol 12‐myristate 13‐acetate, an activator of protein kinase C, for 30 min prior to the addition of 1‐MA resulted in the inhibition of 1‐MA‐induced phosphorylation of eIF‐4E, translational activation, and germinal vesicle breakdown. Therefore, protein kinase C may phosphorylate eIF‐4E, after very early events of maturation. Another possibility is that eIF‐4E is phosphorylated by an unknown kinase that is activated by the cascade of reactions stimulated by 1‐MA. In conclusion, our results suggest a role for the phosphorylation of eIF‐4E in the activation of translation during maturation, similar to translational regulation during the stimulation of growth in mammalian cells. © 1993 Wiley‐Liss, Inc.
Expression of elongation factor 1α (EF‐1α) and 1βγ (EF‐1βγ) are uncoupled in early Xenopus embryos
Authors: Morales Julia , Bassez Thérèse , Cormier Patrick , Mulner‐Lorillon Odile , Bellé Robert , Osborne H. Beverley 
Published: May 2005

AbstractIn the amphibian Xenopus laevis, the elongation factor 1α proteins (EF‐1α) synthesised in oocytes and somatic cells correspond to distinct gene products. Furthermore, the somatic EF‐1α gene (EF‐1αS) produces one of the most highly expressed early zygotic transcripts in the embryo. The functional recycling of EF‐1α (conversion of EF‐1α‐GDP to EF‐1α‐GTP) is assured by the EF‐1βγ complex. We show here that in Xenopus laevis embryos, contrary to the situation for EF‐1α, EF‐1β, and EF‐1γ mRNAs are transcribed from the same genes in oocytes and somatic cells. In addition, the onset of transcription of the EF‐1β and EF‐1γ genes from the zygotic gencme occurs several hours after that of the somatic EF‐1αS gene. Therefore, during early Xenopus development the expression of these three elongation factors is not co‐ordinated at the transcriptional level. The consequences of this uncoupling on the efficiency of translational elongation in the early Xenopus embryo are discussed. © 1993 Wiley‐Liss, Inc.
Tubulin mRNA instability and stabilization by protein synthesis inhibitors are reproducible in nontranslating extracts from Chlamydomonas
Authors: Baker Ellen J. 
Published: May 2005

AbstractIn Chlamydomonas rein‐hardtii, flagellar amputation stimulates an induction in the synthesis of flagellar proteins which allows the cells to rapidly regenerate their flagella. The induction involves the coordinate accumulation and rapid degradation of a large number mRNAs, including those encoding the tubulins. The post‐induction degradation of induced tubulin mRNAs has been shown to differ from the consti‐tutive turnover pathway in two ways: (1) the rate of degradation is accelerated, and (2) degradation is prevented by inhibition of protein synthesis. In this report, it is shown that the post‐induction degradation of all deflagellation‐induced mRNAs examined is prevented by cycloheximide (CX), suggesting they all may be degraded via the same pathway. A cell‐free decay system has been developed to investigate the degradation pathway. At least two characteristics of tubulir mRNA degradation are reproducible in these extracts: (1) endogenous α‐tubulin mRNA is less stable than constitutive mRNAs in the same extract and (2) α‐tubulin mRNA in extracts prepared from CX‐treated cells (CX ex‐tracts) is significantly more stable than it is in extracts from untreated cells (control extracts). This indicates that the mechanism by which CX blocks rapid degradation of tubulin mRNA in vivo is not simply by preventing its translation and suggests the involvement of an altered trans‐factor. The difference in tubulin mRNA stability in the two extracts is maintained when the extracts are prepared under conditions that dissociate ribosomes from mRNPs, indicating intact polysome structure is not necessary. Tubulin mRNA‐containing polysomes isolated from control and CX extracts are equally stable when assayed alone. However, the poly‐somes from control extracts are more sensitive to exogenous RNAse treatment than are those from CX extracts, indicating a structural difference. There are no detectable differences in soluble factors that influence tubulin mRNA degradation rate between control and CX extracts; addition of excess soluble factors to either control or CX extracts does not alter the tubulin mRNA degradation in the extract, nor does a simple one‐to‐one combination of the two extracts result in stabilization or destabilization of the whole population of tubulin mRNAs in the mixture. The deflagellation‐induced mRNAs, as a group, are shown to be particularly susceptible to a nuclease activity in extracts, inhibitable by vanadyl ribonucleoside complexes, which does not appear to attack constitutive mRNAs. It is proposed that a structural difference in the tubulin mRNPs produced in the presence and absence of CX underlies their differences in stabilities, and that a common nuclease targets the induced flagellar protein mRNAs. © 1993 Wiley‐Liss, Inc.