bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of Hormesis through Mild Heat Stress on Human Cells
Authors: RATTAN SURESH I. S.
Published: July 2004

Abstract: In a series of experimental studies, it was shown that repetitive mild heat stress has antiaging hormetic effects on growth and various other cellular and biochemical characteristics of human skin fibroblasts undergoing aging in vitro. We have reported the hormetic effects of repeated challenge at the levels of maintenance of stress protein profile; reduction in the accumulation of oxidatively and glycoxidatively damaged proteins; stimulation of the proteasomal activities for the degradation of abnormal proteins; improved cellular resistance to ethanol, hydrogen peroxide, and ultraviolet‐B rays; and enhanced levels of various antioxidant enzymes. Detailed analysis of the signal transduction pathways to determine alterations in the phosphorylation and dephosphorylation states of ERK, JNK, and p38 MAP kinases as a measure of cellular responsiveness to mild and severe heat stress is in progress. Furthermore, comparative studies using nonaging immortal cell lines, such as SV40‐transformed human fibroblasts, spontaneous osteosarcoma cells, and telomerase‐immortalized human bone marrow cells are also in progress for establishing differences in normal and cancerous cells for their responsiveness to mild and severe stresses.
Apolipoprotein E Genotype and Age at Menopause
Authors: KOOCHMESHGI JALAL , MEHDI HOSSEINI‐MAZINANI SEYED , MORTEZA SEIFATI SEYED , HOSEIN‐PUR‐NOBARI NASRIN , TEIMOORI‐TOOLABI LADAN
Published: July 2004

Abstract: We tested the hypothesis that there is a connection between apolipoprotein E (APOE) genotype and age at menopause. A sample of women aged between 50 and 60 years who had reached natural menopause was studied. Survival analysis of data showed a significant relationship between APOE genotype and age at menopause, carriers of the APOE4 allele reaching menopause at an earlier age. Our findings can have a bearing on the question of the evolution of this major human polymorphism and human life history. These findings are also relevant to the question of the connection between reproductive parameters and age‐associated diseases.
How an Individual Fecundity Pattern Looks in Drosophila and Medflies
Authors: NOVOSELTSEV V N , ARKING R , CAREY J R , NOVOSELTSEVA J A , YASHINb A I
Published: July 2004

Abstract: Reproduction usually is characterized by a mean‐population fecundity pattern. Such a pattern has a maximum at earlier ages and a subsequent gradual decline in egg production. It is shown that individual fecundity trajectories do not follow such a pattern. In particular, the regular individual fecundity pattern has no maximum so that experimentally observed maximums are average‐related artifacts. The three‐stage description of individual fecundity, which includes maturation, maturity, and reproductive senescence, is more appropriate. Data are presented for Drosophila and Mediterranean fruitfly females that clearly confirm this hypothesis. A systematic error between egg‐laying scores and the regular individual pattern allows for evaluation of how close the random scores are to the pattern. The first finding of the analysis of the systematic errors is that they are consistent with the three‐stage hypothesis and do not contradict the absence of the maximum in the regular individual pattern. The other finding is the existence of obvious dynamic properties of the systematic error. The slow decrease in egg‐laying at the maturity stage might be the result of a cost of mating. It can also be a consequence of “structural” senescence, that is, a slow rate accumulation of oxidative damage in the gonads.
Mitochondria, Sex, and Mortality
Authors: ROSS IAN K.
Published: July 2004

Abstract: It has been proposed that prior to the evolution of sex, the endosymbiotic relationship between mitochondria and nuclear genomes would have selected mechanisms that maintained the optimum interaction between the two genomes. Once sex evolved, mating would introduce different, competitive, mtDNA and/or nDNA gene products that could well upset the balance. Mechanisms, such as the specific degradation of one mitochondrial genome that is known to occur, could have been selected to prevent part of such competition. Unlike most protein complexes in the cell, the proteins of the multienzyme complexes of the ox‐phos system are derived from both nuclear‐genome‐coded genes and mito‐chondrial‐genome‐coded genes. Minor mutations in either mtDNA or nDNA coding for these proteins are known to lead to major and catastrophic diseases of humans, suggesting that very tight and precise interactions are required. To maintain the evolutionarily established balance after mating, monoallelic expression of the nuclear‐coded genes would be advantageous and prevent subtly different competitive proteins from interacting with the resident mitochondria. This would require regulation of the expression of those specific nuclear genes, possibly under the control of the resident mitochondria. It is possible that aging cells could lose the requisite tight regulation and allow expression of proteins derived from the formerly repressed nuclear alleles that would compete for mitochondrial complex sites. With age, random failure of this control could lead to increasingly inefficient mitochondria in different tissues and organs and eventually to senescence and death.
Proinflammatory Cytokine Impairment of Insulin-Like Growth Factor I-Induced Protein Synthesis in Skeletal Muscle Myoblasts Requires Ceramide
Authors: Strle Klemen , Broussard Suzanne R. , McCusker Robert H. , Shen Wen-Hong , Johnson Rodney W. , Freund Gregory G. , Dantzer Robert , Kelley Keith W.
Published: July 2004

GH and IGF-I control over 80% of postnatal growth. We recently established that TNFα impairs the ability of IGF-I to increase protein synthesis and promote expression of myogenin in myoblasts. Here we extend these results by showing that ceramide, a second messenger in both TNFα and IL-1β receptor signaling pathways, is a key downstream sphingosine-based lipid that leads to IGF-I resistance. A cellpermeable ceramide analog, C2-ceramide, inhibits IGF-I-induced protein synthesis by 65% and blocks the ability of IGF-I to increase expression of two key myogenic factors, myogenin and MyoD. Identical results were obtained with both TNFα and IL-1β (1 ng/ml). Consistent with these data, neutral sphingomyelinase (N-SMase), an enzyme that catalyzes formation of ceramide from sphingomyelin, blocks IGF-I-induced protein synthesis and expression of both myogenin and MyoD. The possibility that cytokine-induced ceramide production is required for disruption of IGF-I biologic activity was confirmed by treating C2C12 myoblasts with inhibitors of all three ceramide-generating pathways. A N-SMase inhibitor, glutathione, as well as an acidic sphingomyelinase (A-SMase) inhibitor, D609, reverse the cytokine inhibition of IGF-I-induced protein synthesis by 80% and 45%, respectively. Likewise, an inhibitor of de novo ceramide synthesis, FB1, causes a 50% inhibition. Similarly, all three inhibitors significantly impair the ability of both TNFα and IL-1β to suppress IGF-I-driven expression of myogenin. These experiments establish that ceramide, derived both from sphingomyelin and de novo synthesis, is a key intermediate by which proinflammatory cytokines impair the ability of IGF-I to promote protein synthesis and expression of critical muscle-specific transcription factors.
Thyroid Hormone Regulates Oligodendrocyte Accumulation in Developing Rat Brain White Matter Tracts
Authors: Schoonover Christopher M. , Seibel Melissa M. , Jolson Dawn M. , Stack Mary Jo , Rahman Rounak J. , Jones Sidney A. , Mariash Cary N. , Anderson Grant W.
Published: July 2004

Thyroid hormone (TH) is necessary for normal axonal myelination. Myelin basic protein (MBP) is a structural protein essential for myelin function. In this study, we demonstrate that perinatal hypothyroidism regulates MBP mRNA levels via indirect mechanisms. We observed decreased MBP mRNA accumulation in the hypothyroid rat brain at postnatal (PN) d 10 and 50. Acute TH replacement did not rescue hypothyroid MBP mRNA levels at PN5, 10, or 50. TH is necessary for normal intrahemispheric commissure development including the anterior commissure (AC) and the corpus callosum (CC). We determined that perinatal hypothyroidism decreases AC area and cellularity in the developing rat brain by PN10 and 50. In the developing CC, hypothyroidism initially increases area and cellularity by PN5, but then ultimately decreases area and cellularity by PN50. MBP-expressing oligodendrocytes are a recognized target of TH and are responsible for myelination within intrahemispheric commissures. We found that hypothyroidism reduces the number of mature oligodendrocytes within both the AC and CC. This reduction is noted at PN5, 10, and 50 in the AC and by PN10 and 50 in the CC. Together, these data suggest that TH regulates MBP mRNA levels through indirect mechanisms. These data demonstrate the complex mechanisms whereby TH regulates myelination in the developing brain.
Ghrelin Degradation by Serum and Tissue Homogenates: Identification of the Cleavage Sites
Authors: De Vriese Carine , Gregoire Francoise , Lema-Kisoka Roger , Waelbroeck Magali , Robberecht Patrick , Delporte Christine
Published: July 2004

The endogenous ligand for the GH secretagogue receptor is ghrelin, a peptide recently purified from the stomach. Ghrelin is n-octanoylated on the Ser3 residue, and this modification is essential for its interaction with the receptor. The degradation of ghrelin by rat and human serum, purified commercial enzymes, and tissues homogenates was analyzed by combining HPLC and mass spectrometry. In serum, ghrelin was desoctanoylated, without proteolysis. The desoctanoylation was significantly reduced by phenylmethylsulfonyl fluoride, a serine proteases and esterases inhibitor. In rat serum, the carboxylesterase inhibitor bis-p-nitrophenyl-phosphate totally inhibited ghrelin desoctanoylation, and a correlation was found between ghrelin desoctanoylation and carboxylesterase activity. Moreover, purified carboxylesterase degraded ghrelin. Thus, carboxylesterase could be responsible for ghrelin desoctanoylation in that species. In human serum, ghrelin desoctanoylation was partially inhibited by eserine salicylate and sodium fluoride, two butyrylcholinesterase inhibitors, but not by bis-p-nitrophenyl-phosphate and EDTA. Purified butyrylcholinesterase was able to degrade ghrelin, and there was a correlation between the butyrylcholinesterase and ghrelin desoctanoylation activities in human sera. This suggested that several esterases, including butyrylcholinesterase, contributed to ghrelin desoctanoylation in human serum. In contact with tissues homogenates, ghrelin was degraded by both desoctanoylation and N-terminal proteolysis. We identified five cleavage sites in ghrelin between residues -Ser2-(acyl)Ser3- (stomach and liver), -(acyl?)Ser3-Phe4- (stomach, liver, and kidney), -Phe4-Leu5- (stomach and kidney), -Leu5-Ser6- and -Pro7-Glu8- (kidney). In all cases, the resulting fragments were biologically inactive.
Coordinate Transcription of the ADAMTS-1 Gene by Luteinizing Hormone and Progesterone Receptor
Authors: Doyle Kari M. H. , Russell Darryl L. , Sriraman Venkataraman , Richards JoAnne S.
Published: July 2004

ADAMTS-1 (a disintegrin and metalloproteinase with thrombospondin-like motifs) is a multifunctional protease that is expressed in periovulatory follicles. Herein we show that induction of ADAMTS-1 message in vivo and transcription of the ADAMTS-1 promoter in cultured granulosa cells are dependent on separable but coordinate actions of LH and the progesterone receptor (PR). To analyze the molecular mechanisms by which LH and PR regulate this gene, truncations and site-specific mutants of ADAMTS-1 promoter-luciferase reporter constructs (ADAMTS-1-Luc) were generated and transfected into rat granulosa cell cultures. Three regions of the promoter were found to be important for basal activity, two of which were guanine cytosine-rich binding sites for specificity proteins Sp1/Sp3 and the third bound a nuclear factor 1-like factor. Despite the absence of a consensus PR DNA response element in the proximal ADAMTS-1 promoter, cotransfection of a PRA (or PRB) expression vector stimulated ADAMTS-1 promoter activity, a response that was reduced by the PR antagonist ZK98299. Forskolin plus phorbol myristate acetate also increased promoter activity and, when added to cells cotransfected with PRA, ADAMTS-1 promoter activity increased further. Activation of the ADAMTS-1 promoter by PRA involves functional CAAT enhancer binding protein β, nuclear factor 1-like factor, and three Sp1/Sp3 binding sites as demonstrated by transfection of mutated promoter constructs. In summary, LH and PRA/B exert distinct but coordinate effects on transactivation of the ADAMTS-1 gene in granulosa cells in vivo and in vitro with PR acting as an inducible coregulator of the ADAMTS-1 gene.
Genomic Organization of Mouse Orexin Receptors: Characterization of Two Novel Tissue-Specific Splice Variants
Authors: Chen Jing , Randeva Harpal S.
Published: July 2004

In humans and rat, orexins orchestrate divergent actions through their G protein-coupled receptors, orexin-1 (OX1R) and orexin-2 (OX2R). Orexins also play an important physiological role in mouse, but the receptors through which they function are not characterized. To characterize the physiological role(s) of orexins in the mouse, we cloned and characterized the mouse orexin receptor(s), mOX1R and mOX2R, using rapid amplification of cDNA (mouse brain) ends, RT-PCR, and gene structure analysis. The mOX1R cDNA encodes a 416-amino acid (aa) receptor. We have identified two alternative C terminus splice variants of the mOX2R; mOX2αR (443 aa) and mOX2βR (460 aa). Binding studies in human embryonic kidney 293 cells transfected with mOX1R, mOX2αR, and the mOX2βR revealed specific, saturable sites for both orexin-A and -B. Activation of these receptors by orexins induced inositol triphosphate (IP3) turnover. However, human embryonic kidney 293 cells transfected with mOXRs demonstrated no cAMP response to either orexin-A or orexin-B challenge, although forskolin and GTPγS revealed a dose-dependent increase in cAMP. Although, orexin-A and -B showed no difference in binding characteristics between the splice variants; interestingly, orexin-B led to an increase in IP3 production at all concentrations in the mOX2βR variant. Orexin-A, however, showed no difference in IP3 production between the two variants. Additionally, in the mouse, we demonstrate that these splice variants are distributed in a tissue-specific manner, where OX2αR mRNA was undetectable in skeletal muscle and kidney. Moreover, food deprivation led to a greater increase in hypothalamic mOX2βR gene expression, compared with both mOX1R and mOX2αR. This potentially implicates a fundamental physiological role for these splice variants.
Asbestos and the Future of Mass Torts
Authors: White Michelle J
Published: July 2004

Asbestos was once referred to as a ‘miracle mineral’ for its ability to withstand heat and it was used in thousands of products. But exposure to asbestos causes cancer and other diseases. As of the beginning of 2001, 600,000 individuals had filed lawsuits for asbestos-related diseases against more than 6,000 defendants. 85 firms have filed for bankruptcy due to asbestos liabilities and several insurers have failed or are in financial distress. More than $54 billion has been spent on the litigation -higher than any other mass tort. Estimates of the eventual cost of asbestos litigation range from $200 to $265 billion. The paper examines the history of asbestos regulation and asbestos liability and argues that it was liability rather than regulation that eventually caused producers to eliminate asbestos from most products by the late 1970s. But despite the disappearance of asbestos products from the marketplace, asbestos litigation continued to grow. Plaintiffs' lawyers used forum-shopping to select the most favorable state courts techniques for mass processing of claims, and substituted new defendants when old ones went bankrupt. Because representing asbestos victims was extremely profitable, lawyers had an incentive to seek out large numbers of additional plaintiffs, including many claimants who were not harmed by asbestos exposure. The paper contrasts asbestos litigation to other mass torts involving personal injury and concludes that asbestos was unique in a number of ways, so that future mass torts are unlikely to be as big. However new legal innovations developed for asbestos are likely to make future mass torts larger and more expensive. I explore two mechanisms - bankruptcies and class action settlements - that the legal system has developed to resolve mass torts and show that neither has worked for asbestos litigation. The first, bankruptcy by individual asbestos defendants, exacerbates the litigation by spreading it to non-bankrupt defendants. The second, a class action settlement, is impractical for asbestos litigation because of the large number of defendants. As a result, Congressional legislation is needed and the paper discusses the compensation fund approach that Congress is currently considering.
Manager-Investor Conflicts in Mutual Funds
Authors: Mahoney Paul G
Published: July 2004

Half of all of U.S. households own shares in one or more mutual funds, either directly or through personal or employer-sponsored retirement accounts. This article describes the structure and regulation of mutual funds and the resulting incentives facing those who make decisions for the funds. After providing some basic institutional details, it focuses on the cash flows from mutual fund investors to fund managers, brokers, and other third parties and the associated conflicts of interest. The article concludes with a summary of recent legal proceedings against mutual fund managers and brokers based on improper trading practices and regulatory proposals to curb those practices.
Comments
Authors: Honohan Patricko , Howarth Richard B , Schuler Kurt , von Hippel Paul T
Published: July 2004

To be considered for publication in the Comments section, letters should be relatively short—generally fewer than 1,000 words—and should be sent to the journal offices at the address appearing inside the front cover. The editors will choose which letters will be published. All published letters will be subject to editing for style and length.
Historical Presidential Betting Markets
Authors: Rhode Paul W , Strumpf Koleman S
Published: July 2004

This paper analyzes the large and often well-organized markets for betting on U.S. presidential elections that operated between 1868 and 1940. Four main points are addressed. First, we show that the market did a remarkable job forecasting elections in an era before scientific polling. Second, the market was fairly efficient, despite the limited information of participants and active attempts to manipulate the odds. Third, we argue political betting markets disappeared largely because of the rise of scientific polls and the increasing availability of other forms of gambling. Finally, we discuss lessons this experience provides for the present.
Recommendations for Further Reading
Authors: Saffran Bernard
Published: July 2004

This section will list readings that may be especially useful to teachers of undergraduate economics, as well as other articles that are of broader cultural interest. In general, the articles chosen will be expository or integrative and not focus on original research. If you write or read an appropriate article, please send a copy of the article (and possibly a few sentences describing it) to Bernard Saffran, c/o Journal of Economic Perspectives, Department of Economics, Swarthmore College, Swarthmore, PA 19081.
State Budget Deficit Dynamics and the California Debacle
Authors: Sheffrin Steven M
Published: July 2004

This paper analyzes the recent experience with state budget deficits in the United States, with an in-depth analysis of the California experience. Compared to prior recessions, states were slower to make adjustments in taxes and spending this time. The paper explores a variety of reasons for this difference including changes in the legal, political, and institutional environments, the unusual increase in capital gains revenue during the boom preceding the recession, and the inherent difficulties in forecasting revenues, particularly those derived from capital income. As the case study from California illustrates, states made long term commitments from temporary revenue sources and were required to make budgetary decisions in the face of very incomplete information about current and projected tax receipts.
Multimerization of poly(rC) binding protein 2 is required for translation initiation mediated by a viral IRES
Authors: BEDARD KRISTIN M. , WALTER BRANDON L. , SEMLER BERT L.
Published: July 2004

The cellular protein, poly(rC) binding protein 2 (PCBP2), is known to function in picornavirus cap-independent translation. We have further examined the RNA binding properties and protein–protein interactions of PCBP2 necessary for translation. We have studied its putative multimerization properties utilizing the yeast two-hybrid assay and in vitro biochemical methods, including glutathione S-transferase (GST) pull-down assays and gel filtration. Through genetic analysis, the multimerization domain has been localized to the second K-homologous (KH) RNA binding domain of the protein between amino acids 125 and 158. To examine the function of multimerization in poliovirus translation, we utilized the truncated protein, ΔKH1-PCBP2, which is capable of multimer formation, but does not bind poliovirus stem–loop IV RNA (an interaction required for translation). Utilizing RNA binding and in vitro translation assays, this protein was shown to act as a dominant negative, suggesting that PCBP2 multimerization functions in poliovirus translation and RNA binding. Additionally, PCBP2 containing a deletion in the multimerization domain (ΔKH2-PCBP2) was not able to bind poliovirus stem–loop IV RNA and could not rescue translation in extracts that were depleted of endogenous PCBP2. Results from these experiments suggest that the multimerization of PCBP2 is required for efficient RNA binding and cap-independent translation of poliovirus RNA. By examining the functional interactions of the cellular protein PCBP2, we have discovered a novel determinant in the mechanism of picornavirus cap-independent translation.
Isolation of specific and high-affinity RNA aptamers against NS3 helicase domain of hepatitis C virus
Authors: HWANG BYOUNGHOON , CHO JUNG SUN , YEO HYEON JU , KIM JUNG-HYE , CHUNG KYUNG MIN , HAN KYUNGSOOK , JANG SUNG KEY , LEE SEONG-WOOK
Published: July 2004

Hepatitis C virus (HCV)-encoded nonstructural protein 3 (NS3) possesses protease, NTPase, and helicase activities, which are considered essential for viral proliferation. Thus, HCV NS3 is a good putative therapeutic target protein for the development of anti-HCV agents. In this study, we isolated specific RNA aptamers to the helicase domain of HCV NS3 from a combinatorial RNA library with 40-nucleotide random sequences using in vitro selection techniques. The isolated RNAs were observed to very avidly bind the HCV helicase with an apparent Kd of 990 pM in contrast to original pool RNAs with a Kd of >1 μM. These RNA ligands appear to impede binding of substrate RNA to the HCV helicase and can act as potent decoys to competitively inhibit helicase activity with high efficiency compared with poly(U) or tRNA. The minimal binding domain of the ligands was determined to evaluate the structural features of the isolated RNA molecules. Interestingly, part of binding motif of the RNA aptamers consists of similar secondary structure to the 3′-end of HCV negative-strand RNA. Moreover, intracellular NS3 protein can be specifically detected in situ with the RNA aptamers, indicating that the selected RNAs are very specific to the HCV NS3 helicase. Furthermore, the RNA aptamers partially inhibited RNA synthesis of HCV subgenomic replicon in Huh-7 hepatoma cell lines. These results suggest that the RNA aptamers selected in vitro could be useful not only as therapeutic and diagnostic agents of HCV infection but also as a powerful tool for the study of HCV helicase mechanism.
Origin, evolution, and mechanism of 5′ tRNA editing in chytridiomycete fungi
Authors: LAFOREST MARIE-JOSÉE , BULLERWELL CHARLES E. , FORGET LISE , LANG B. FRANZ
Published: July 2004

5′ tRNA editing has been demonstrated to occur in the mitochondria of the distantly related rhizopod amoeba Acanthamoeba castellanii and the chytridiomycete fungus Spizellomyces punctatus. In these organisms, canonical tRNA structures are restored by removing mismatched nucleotides at the first three 5′ positions and replacing them with nucleotides capable of forming Watson–Crick base pairs with their 3′ counterparts. This form of editing seems likely to occur in members of Amoebozoa other than A. castellanii, as well as in members of Heterolobosea. Evidence for 5′ tRNA editing has not been found to date, however, in any other fungus including the deeply branching chytridiomycete Allomyces macrogynus. We predicted that a similar form of tRNA editing would occur in members of the chytridiomycete order Monoblepharidales based on the analysis of complete mitochondrial tRNA complements. This prediction was confirmed by analysis of tRNA sequences using a tRNA circularization/ RT-PCR-based approach. The presence of partially and completely unedited tRNAs in members of the Monoblepharidales suggests the involvement of a 5′-to-3′ exonuclease rather than an endonuclease in removing the three 5′ nucleotides from a tRNA substrate. Surprisingly, analysis of the mtDNA of the chytridiomycete Rhizophydium brooksianum, which branches as a sister group to S. punctatus in molecular phylogenies, did not suggest the presence of editing. This prediction was also confirmed experimentally. The absence of tRNA editing in R. brooksianum raises the possibility that 5′ tRNA editing may have evolved twice independently within Chytridiomycota, once in the lineage leading to S. punctatus and once in the lineage leading to the Monoblepharidales.
Identification of a bifunctional enzyme MnmC involved in the biosynthesis of a hypermodified uridine in thewobbleposition of tRNA
Authors: BUJNICKI JANUSZ M. , OUDJAMA YAMINA , ROOVERS MARTINE , OWCZAREK SYLWIA , CAILLET JOËL , DROOGMANS LOUIS
Published: July 2004

The gene encoding the bifunctional enzyme MnmC that catalyzes the two last steps in the biosynthesis of 5-methylaminomethyl-2-thiouridine (mnm5s2U) in tRNA has been previously mapped at about 50 min on theEscherichia coliK12 chromosome, but to date the identity of the corresponding enzyme has not been correlated with any of the known open reading frames (ORFs). Using the protein fold-recognition approach, we predicted that the 74-kDa product of theyfcKORF located at 52.6 min and annotated as “putative peptidase” comprises a methyltransferase domain and a FAD-dependent oxidoreductase domain. We have cloned, expressed, and purified the YfcK protein and demonstrated that it catalyzes the formation of mnm5s2U in tRNA. Thus, we suggest to rename YfcK as MnmC.
mRNA deadenylation by PARN is essential for embryogenesis in higher plants
Authors: REVERDATTO SERGEI V. , DUTKO JAMES A. , CHEKANOVA JULIA A. , HAMILTON DOUGLAS A. , BELOSTOTSKY DMITRY A.
Published: July 2004

Deadenylation of mRNA is often the first and rate-limiting step in mRNA decay. PARN, a poly(A)-specific 3′ →5′ ribonuclease which is conserved in many eukaryotes, has been proposed to be primarily responsible for such a reaction, yet the importance of the PARN function at the whole-organism level has not been demonstrated in any species. Here, we show that mRNA deadenylation by PARN is essential for viability in higher plants (Arabidopsis thaliana). Yet, this essential requirement for the PARN function is not universal across the phylogenetic spectrum, because PARN is dispensable in Fungi (Schizosaccharomyces pombe), and can be at least severely downregulated without any obvious consequences in Metazoa (Caenorhabditis elegans). Development of the Arabidopsis embryos lacking PARN (AtPARN), as well as of those expressing an enzymatically inactive protein, was markedly retarded, and ultimately culminated in an arrest at the bent-cotyledon stage. Importantly, only some, rather than all, embryo-specific transcripts were hyperadenylated in the mutant embryos, suggesting that preferential deadenylation of a specific select subset of mRNAs, rather than a general deadenylation of the whole mRNA population, by AtPARN is indispensable for embryogenesis in Arabidopsis. These findings indicate a unique, nonredundant role of AtPARN among the multiple plant deadenylases.
A reassessment of the response of the bacterial ribosome to the frameshift stimulatory signal of the human immunodeficiency virus type 1
Authors: LÉGER MÉLISSA , SIDANI SACHA , BRAKIER-GINGRAS LÉA
Published: July 2004

HIV-1 uses a programmed -1 ribosomal frameshift to produce the precursor of its enzymes. This frameshift occurs at a specific slippery sequence followed by a stimulatory signal, which was recently shown to be a two-stem helix, for which a three-purine bulge separates the upper and lower stems. In the present study, we investigated the response of the bacterial ribosome to this signal, using a translation system specialized for the expression of a firefly luciferase reporter. The HIV-1 frameshift region was inserted at the beginning of the coding sequence of the luciferase gene, such that its expression requires a −1 frameshift. Mutations that disrupt the upper or the lower stem of the frameshift stimulatory signal or replace the purine bulge with pyrimidines decreased the frameshift efficiency, whereas compensatory mutations that re-form both stems restored the frame-shift efficiency to near wild-type level. These mutations had the same effect in a eukaryotic translation system, which shows that the bacterial ribosome responds like the eukaryote ribosome to the HIV-1 frameshift stimulatory signal. Also, we observed, in contrast to a previous report, that a stop codon immediately 3′ to the slippery sequence does not decrease the frameshift efficiency, ruling out a proposal that the frameshift involves the deacylated-tRNA and the peptidyl-tRNA in the E and P sites of the ribosome, rather than the peptidyl-tRNA and the aminoacyl-tRNA in the P and A sites, as commonly assumed. Finally, mutations in 16S ribosomal RNA that facilitate the accommodation of the incoming aminoacyl-tRNA in the A site decreased the frameshift efficiency, which supports a previous suggestion that the frameshift occurs when the aminoacyl-tRNA occupies the A/T entry site.
Detection of Nascent and/or Mature Forms of Oviductin in the Female Reproductive Tract and Post-ovulatory Oocytes by Use of a Polyclonal Antibody Against Recombinant Hamster Oviductin
Authors: McBride Deborah S. , Boisvert Chantale , Bleau Gilles , Kan Frederick W.K.
Published: July 2004

Oviductins belong to a family of glycoproteins that have been suggested to play several roles during the early processes of reproduction. Recently, a polyclonal antibody was raised against recombinant hamster oviductin (rhaOvm). Here the anti-rhaOvm antibody was used to investigate the sites of localization of oviductin in the female golden hamster. In the hamster oviduct, immunolabeling was restricted to the content of the Golgi saccules and secretory granules of the non-ciliated oviduct cells. After its release into the lumen, oviductin becomes associated with the zona pellucida of post-ovulatory oocytes. In unfertilized oocytes, oviductin was also detected in membrane invaginations along the oolemma and in some vesicles within the ooplasm. Furthermore, oviductin was detected over the microvilli and within multivesicular bodies of uterine epithelial cells. Western blotting analysis revealed the presence of oviductin in the hamster oviduct but not in the uterus or ovary. In the oviduct, the anti-rhaOvm antibody detected a polydispersed band corresponding to native oviductin (160–350 kD) and several lower molecular weight bands (<100 kD) corresponding to nascent and partially glycosylated forms of oviductin. The anti-rhaOvm antibody provides an additional tool for investigation into the cytochemical and biochemical properties of different forms of hamster oviductin in the female reproductive tract.
Vascular Mural Cells in Healing Canine Myocardial Infarcts
Authors: Dobaczewski Marcin , Akrivakis Spyridon , Nasser Kamal , Michael Lloyd H. , Entman Mark L. , Frangogiannis Nikolaos G.
Published: July 2004

Angiogenesis is a critical process in healing of myocardial infarcts, leading to the formation of highly vascular granulation tissue. However, effective cardiac repair depends on mechanisms that inhibit the angiogenic process after a mature scar is formed, preventing inappropriate expansion of the fibrotic process. Using a canine model of reperfused myocardial infarction, we demonstrated that maturation of the infarct leads to the formation of neovessels, with a thick muscular coat, that demonstrate distinct morphological characteristics. Many of these “neoarterioles” lack a defined internal elastic lamina and demonstrate irregular deposits of extracellular matrix in the media. Vascular mural cells in healing infarcts undergo phenotypic changes, showing minimal expression of desmin during the proliferative phase (1 hr occlusion/7 days reperfusion) but in the mature scar (8 weeks reperfusion) acquire a phenotype similar to that of vascular smooth muscle cells in control areas. Non-muscle myosin heavy chains A and B are induced in infarct endothelial cells and myofibroblasts, respectively, but are not expressed in neovascular mural cells. Recruitment of a muscular coat and formation of neoarterioles in mature scars may inhibit endothelial cell proliferation and vascular sprouting, stabilizing the infarct vasculature.
Differential Expression of Apolipoprotein D in Human Astroglial and Oligodendroglial Cells
Authors: Navarro Ana , del Valle Eva , Tolivia Jorge
Published: July 2004

Apolipoprotein D (Apo D) is a secreted lipocalin in the nervous system that may be related to processes of reinnervation and regeneration. Under normal conditions, Apo D is present in the central nervous system in oligodendrocytes, astrocytes, and some scattered neurons. To elucidate the regional and cellular distribution of Apo D in normal human brain, we performed double immunohistochemistry for glial fibrillary acidic protein (GFAP) and Apo D in samples of postmortem human cerebral and cerebellar cortices. Most of the GFAP-positive cells in the gray matter had features of protoplasmic astrocytes and were mainly Apo D-positive. Apo D staining was mostly confined to the cell soma and proximal processes, whereas GFAP extended to a rich and extensive array of processes. The fibrous astrocytes in the white matter were immunoreactive for GFAP but not for Apo D. In the white matter, Apo D was mainly detected in oligodendrocytes and extracellularly in the neuropil. The results of the present study support a specific behavior for each astrocyte type. These findings suggest that Apo D expression may be cell-specific, depending on the particular tissue physiology at the time of examination.
Carbonic Anhydrase VI in the Mouse Nasal Gland
Authors: Kimoto Masaya , Iwai Soichi , Maeda Takashi , Yura Yoshiaki , Fernley Ross T. , Ogawa Yuzo
Published: July 2004

Western blotting analysis of mouse nasal tissue using a specific anti-mouse secreted carbonic anhydrase (CA VI) antibody has shown that CA VI is present in this tissue. A single immunoreactive band of 42 kD was observed, as has been found previously for salivary tissues. RT-PCR analysis has shown that nasal mucosa expressed CA VI mRNA. By immunohistochemistry (IHC), CA VI was observed in acinar cells, in duct contents of the anterior gland of the nasal septum, and in the lateral nasal gland. The Bowman's gland, the posterior gland of the nasal septum, and the maxillary sinus gland were negative. Immunoreactivity was also observed in the mucus covering the respiratory and olfactory mucosa and in the lumen of the nasolacrimal duct. In contrast, an anti-rat CA II antibody (that crossreacts with the mouse enzyme) stained only known CA II-positive cells and an occasional olfactory receptor neuron. These results indicate that CA VI is produced by the nasal gland and is secreted over the nasal mucosa. By reversible hydration of CO2, CA VI is presumed to play a role in mucosal functions such as CO2 sensation and acid–base balance. It may also play a role in olfactory function as a growth factor in maturation of the olfactory epithelial cells.
Differential Expression of Basement Membrane Components in Lymphatic Tissues
Authors: Määttã Marko , Liakka Annikki , Salo Sirpa , Tasanen Kaisa , Bruckner-Tuderman Leena , Autio-Harmainen Helena
Published: July 2004

Peripheral lymphoid tissues act as important organs of immunological defense. Characteristic of their architecture is the rich reticular fiber meshwork composed of various extracellular matrix (ECM) molecules with which the stationary non-lymphatic cells stay in intimate contact and form channels through which the lymphatic cells travel. Here we studied the distribution of various laminin (Ln) chains and different types of collagens in human spleen, lymph node, and tonsil to clarify their chain-specific distribution. The most widely distributed proteins in all these organs were Ln chains α5, β1, γ1 and collagen types IV and XVIII, which were present in practically all compartments. Conversely, Ln α1, α2, α4, and type VII collagen showed a more restricted expression pattern. A unique feature was that Ln α3-, β3-, and γ2-chains, which normally are not localized to the vascular wall in non-lymphatic tissues, were present also in capillary basement membranes (BMs) of the follicular structures of lymph node and tonsil and in Ln α1-chain and type VII collagen also in the splenic white pulp. We also found that collagen XVII was exclusively present in the ring fibers of the spleen. The results indicate that BMs of lymphatic tissues contain a variety of macromolecules that probably contribute strongly to immunological events. In addition, capillaries of the lymphoid tissue exhibit a specified BM composition resembling that in epithelial BMs of non-lymphoid tissues.
Differential Expression of CD44 During Human Prostate Epithelial Cell Differentiation
Authors: Alam Tahirah N. , O'Hare Michael J. , Laczkó István , Freeman Alex , Al-Beidh Farah , Masters John R. , Hudson David L.
Published: July 2004

CD44 is a polymorphic transmembrane glycoprotein that binds hyaluronan and growth factors. Multiple isoforms of the protein can be generated by alternative splicing but little is known about the expression and function of these isoforms in normal development and differentiation. We have investigated the expression of CD44 during normal prostate epithelial cell differentiation. A conditionally immortalized prostate epithelial cell line, Pre2.8, was used as a model system. These cells proliferate at 33C but at 39C stop dividing and undergo changes consistent with early stages of cell differentiation. During the differentiation of these cells, the expression of the CD44 isoform v3-v10 was upregulated. Two layers of epithelial cells can clearly be distinguished in the human prostate, a basal layer expressing keratins 5/14 and a luminal layer expressing keratins 8/18. In prostate tissue the v3-v10 isoform was found predominantly in basal cells but also in keratin 14-negative, keratin 19-positive cells intermediate between the two layers. CD44 v3-v10 was also expressed in other keratin 14-negative prostate tissues, the ejaculatory ducts and prostatic urethra. Therefore, CD44 v3-v10 may be important as a cell surface marker for differentiating cells in the prostate epithelium.
Attenuation of Neointimal Vascular Smooth Muscle Cellularity in Atheroma by Plasminogen Activator Inhibitor Type 1 (PAI-1)
Authors: Schneider David J. , Hayes Michael , Wadsworth Marilyn , Taatjes Heidi , Rincón Mercedes , Taatjes Douglas J. , Sobel Burton E.
Published: July 2004

Rupture of vulnerable atheroma often underlies acute coronary syndromes. Vulnerable plaques exhibit a paucity of vascular smooth muscle cells (VSMCs) in the cap. Therefore, decreased VSMC migration into the neointima may predispose to vulnerability. The balance between cell surface plasminogen activator activity and its inhibition [mediated primarily by plasminogen activator inhibitor type 1 (PAI-1)] modulates migration of diverse types of cells. We sought to determine whether increased expression of PAI-1 would decrease migration of VSMCs in vitro and neointimal cellularity in vivo in apolipo-protein E knockout (ApoE−-/–) mice fed a high-fat diet. Increased vessel wall expression of PAI-1 in transgenic mice was induced with the SM22α promoter. VSMC migration through Matrigel in vitro was quantified with laser scanning cytometry. Expression of PAI-1 was increased threefold in the aortic wall of SM22-PAI transgene-positive mice. Neointimal cellularity of vascular lesions was decreased by 26% ( p=0.01; n=5 each) in ApoE−-/– mice with the SM22-PAI transgene compared with ApoE−-/– mice. VSMCs explanted from transgene-positive mice exhibited twofold greater expression of PAI-1 and their migration was attenuated by 27% ( p=0.03). Accordingly, increased expression of PAI-1 protein by VSMCs reduces their migration in vitro and their contribution to neointimal cellularity in vivo.
Immunohistochemical Demonstration of Carbonic Anhydrase Isoenzyme VI (CA VI) Expression in Rat Lower Airways and Lung
Authors: Leinonen Jukka S. , Saari Kirsi A. , Seppänen Jaana M. , Myllylä Hanna M. , Rajaniemi Hannu J.
Published: July 2004

Carbonic anhydrase isoenzyme VI (CA VI), which is transported in high concentrations in saliva and milk into the alimentary tract, is an important element of mucosal protection in the upper alimentary tract. Like alimentary tract mucosa, the respiratory tract mucosa is also exposed to heavy microbial, physical, and chemical stress. The protective and renewal-promoting factors present in the surface mucus of the respiratory tract are mainly produced by the seromucous tracheobronchial glands. Here we studied the secretion of CA VI by these glands in adult and developing rats using immunohistochemical techniques. The serous acinar and duct cells of the tracheobronchial glands stained for CA VI. The presence of the enzyme also in the duct content indicates its active secretion into the surface mucus. CA VI was also visible in the secretory cells and at the base of the ciliated cells of the tracheobronchial surface epithelium. Moreover, the Clara cells of the bronchiolar surface epithelium stained for CA VI. These findings are consistent with the hypothesis that CA VI has a mucosa-protective role not only in the gastrointestinal tract but also in the respiratory tract, where CA VI may act as a pivotal pH neutralizer and growth factor.
Fluorescence In Situ Hybridization Analysis Reveals Multiple Loci of Knob-associated DNA Elements in One-knob and Knobless Maize Lines
Authors: Adawy Sami S.M. , Stupar Robert M. , Jiang Jiming
Published: July 2004

Fluorescence in situ hybridization analyses were conducted to examine the presence or absence of the 180- and 350-bp knob-associated tandem repeats in maize strains previously defined as “one-knob” or “knobless.” Multiple loci were found to hybridize to these two repeats in all maize lines analyzed. Our results show that the number of 180- and 350-bp repeat loci do not correlate with the number of knobs in maize and that these tandem repeats are not independently sufficient to confer knob heterochromatin, even when present at megabase sizes.
Development of Sensitive Immunoassays for Free and Total Human Glandular Kallikrein 2
Authors: Väisänen Ville , Eriksson Susann , Ivaska Kaisa K , Lilja Hans , Nurmi Martti , Pettersson Kim
Published: July 2004

Background: Free and total human kallikrein 2 (hK2) might improve the discrimination between prostate cancer and benign prostatic hyperplasia. Concentrations of hK2 are 100-fold lower than concentrations of prostate-specific antigen (PSA); therefore, an hK2 assay must have a low detection limit and good specificity.

Methods: PSA- and hK2-specific monoclonal antibodies were used in solid-phase, two-site immunofluorometric assays to detect free and total hK2. The total hK2 assay used PSA-specific antibodies to block nonspecific signal. The capture antibody of the free hK2 assay did not cross-react with PSA. To determine the hK2 concentrations in the male bloodstream, total hK2 was measured in a control group consisting of 426 noncharacterized serum samples. Free and total hK2 were measured in plasma from 103 patients with confirmed prostate cancer.

Results: All 426 males in the control group had a total hK2 concentration above the detection limit of 0.0008 μg/L. The median total hK2 concentration was 0.022 μg/L (range, 0.0015–0.37 μg/L). hK2 concentrations were 0.1–58% of total PSA (median, 3.6%). hK2 concentrations were similar in men 41–50 and 51–60 years of age. The ratio of hK2 to PSA steadily decreased from 5–30% at PSA <1 μg/L to 1–2% at higher PSA concentrations. In 103 patients with prostate cancer, the median hK2 concentration in plasma was 0.079 μg/L (range, 0.0015–16.2 μg/L). The median free hK2 concentration was 0.070 (range, 0.005–12.2) μg/L. The proportion of free to total hK2 varied from 17% to 131% (mean, 85%).

Conclusions: The wide variation in the free-to-total hK2 ratio suggests that hK2 in blood plasma is not consistently in the free, noncomplexed form in patients with prostate cancer. The new assay is sufficiently sensitive to be used to study the diagnostic accuracies of free and total hK2 for prostate cancer.
Stripping for the wolf: Rethinking representations of gender in children's literature
Authors: MARSHALL ELIZABETH
Published: July 2004

ABSTRACTS

This essay seeks to broaden theoretical paradigms commonly used in the social sciences to analyze representations of gender, especially girlhood, in children's literature. In particular, this project seeks to add to liberal feminist frameworks for conceptualizing textual representations of gender and sexuality in literacy studies. Liberal feminisms theorize gender through the lens of sex‐role theory, a paradigm in which social roles are allocated to men and to women on the basis of biological sex. The author acknowledges this important theoretical tradition, which brings attention to sex‐role stereotypes in children's literature, and approaches the topic of gender representation from another perspective. Drawing on feminist and literary theories informed by poststructuralism, the author analyzes how discourses of femininity produce the contested subjectivity of the “girl.” Through a textual analysis of four variants of “Little Red Riding Hood,” the author illustrates how poststructural feminist literary theory allows for a reading of the girl as less a natural category than as the product of evolving, culturally situated, and contradictory discourses. In this wayanother possible direction for analyzing gender in children's literature is offered.
On what crosses, and does not cross, our desks in early literacy
Authors: DUKE NELL K. , MOSES ANNIE M.
Published: July 2004

Book reviewed in this article:

Language, Literacy and Cognitive Development: The Development and Consequences of Symbolic Communication. Edited by Eric Amsel & James P. Byrnes. 2002.