bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of blood oxygen stores in bottlenose dolphins (Tursiops truncatus): implications for diving capacity
Authors: Noren Shawn R. , Lacave Geraldine , Wells Randall S. , Williams Terrie M. 
Published: August 2002

AbstractEnhanced oxygen reserves in the blood facilitate diving in marine mammals. For pinnipeds (seals and sea lions), a developmental period of 4 to 24 months is required for blood oxygen stores to reach adult capacities. We investigated whether a similar developmental period for the blood occurs in cetaceans (dolphins and whales), a group of mammals that are exposed to diving immediately after birth. Blood samples were collected from wild and zoological park bottlenose dolphinsTursiops truncatusaged 0–12 years. Red blood cell number (RBC), haemoglobin content (Hb), haematocrit (Hct), mean corpuscular volume (MCV), mean cell haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) were determined for each sample. We found that during postnatal development, RBC, Hb and Hct decreased from 0 to 1.5 months and then increased from 1.5 to 6 months, reaching adult levels by 3 years. MCV and MCH both increased from birth. MCHC decreased from 0 to 3.2 months and then increased. Adult levels for MCV were attained as early as 2 months of age while adult levels for MCH and MCHC were attained by 6 months of age. These results indicate that, for bottlenose dolphins, the development of the blood and its capacity to store oxygen is not complete with weaning, which generally occurs at 1.5 years old. The lower oxygen storage capacity of immature dolphins is likely to limit dive capabilities. Calculated aerobic dive limits (cADLs) for 0‐ to 2‐year‐old dolphin calves are 1.9–3.6 min, compared to 4.8–5.4 min for 3‐ to 12‐year‐old dolphins. Increases in cADLs from 0 to 3 years are attributed to increases in both body mass and mass specific oxygen stores while body mass alone explains the increases in cADLs from 3 to 9 years. The limited diving capacity of young dolphins may influence the foraging behaviours of newly weaned juveniles and females accompanied by calves.
Temperature, genetic and hydroperiod effects on metamorphosis of brown frogs Rana arvalis and R. temporaria in the field
Authors: Loman Jon 
Published: August 2002

AbstractTime for metamorphosis and metamorph size of moor frogs Rana arvalis and common frogs R. temporaria were measured in 22 ponds for 1–8 years. Environmental data in these ponds were also measured. Metamorphosis of the frogs took place from the beginning of June to the beginning of August. When both species were found in one pond, the common frogs metamorphosed up to 20 days earlier than the moor frogs. Most variation in time for metamorphosis, among ponds and years, is explained by temperature effects, but a causal relationship was not established. Within a pond, metamorphosis was later in cold summers than in warm summers. Size at metamorphosis was affected by tadpole density; at high densities metamorphs were smaller. Size at metamorphosis was not related to time for metamorphosis. There was an effect of pond drying; if ponds were about to dry up, metamorphosis was accelerated by about 2.4 days. Tadpoles from ponds with a late metamorphosis in the field had tadpoles that metamorphosed early in a common garden experiment, suggesting counter gradient selection.
Glucocorticoid Receptors in Hippocampal Neurons that Do Not Engage Proteasomes Escape from Hormone-Dependent Down-Regulation but Maintain Transactivation Activity
Authors: Wang Xinjia , Pongrac Julie L. , DeFranco Donald B. 
Published: August 2002

AbstractThe glucocorticoid receptor (GR) protein is subjected to hormone-dependent down-regulation in most cells and tissues. This reduction in receptor levels that accompanies chronic hormone exposure serves to limit hormone responsiveness and operates at transcriptional, posttranscriptional, and posttranslational levels. The ability of glucocorticoid hormones to trigger GR down-regulation may be not universal, particularly in mature and developing neurons in which conflicting results regarding hormone control of GR protein have been reported. We find that endogenous GR is not down-regulated in the HT22 mouse hippocampal cell line and in primary hippocampal neurons derived from embryonic rats. Because GR has the capacity to be ubiquitylated in HT22 cells, receptor down-regulation must be limited by defects in either targeting of polyubiquitylated receptor to the proteasome or processing of the targeted receptor by the proteasome. Despite the lack of GR down-regulation in the HT22 cells, glucocorticoid-induced transcription from transiently transfected templates is attenuated upon prolonged hormone treatment. This termination of GR transactivation is not due to inefficient nuclear import or nuclear retention of the receptor. Furthermore, GR efficiently exports from HT22 cell nuclei in hormone-withdrawn cells, indicating that the receptor has access to both nuclear and cytoplasmic degradation pathways. Our results suggest that appropriate maturation of proteasomal degradative or targeting activities may be required, particularly in hippocampal neurons, for hormone-dependent down-regulation of GR.
Induction of Cyclooxygenase-2 Gene in Pancreatic β-Cells by 12-Lipoxygenase Pathway Product 12-Hydroxyeicosatetraenoic Acid
Authors: Han Xiao , Chen Songyuan , Sun Yujie , Nadler Jerry L. , Bleich David 
Published: August 2002

AbstractCyclooxygenase-2 (COX-2) gene and 12-lipoxygenase (12-LO) gene are preferentially expressed over other types of cyclooxygenase and lipoxygenase in pancreatic β-cells. Inhibition of either COX-2 or 12-LO can prevent cytokine-induced pancreatic β-cell dysfunction as defined by inhibition of glucose-stimulated insulin secretion. As cellular stress induces both genes and their respective end products in pancreatic β-cells, we evaluated the role of 12-hydroxyeicosatetraenoic acid (HETE) on COX-2 gene expression, protein expression, and prostaglandin E2 (PGE2) production.We demonstrate that 12-HETE significantly increases COX-2 gene expression and consequent product formation, whereas a closely related lipid, 15-HETE, does not. In addition, IL-1β-stimulated prostaglandin E2 production is completely inhibited by a preferential lipoxygenase inhibitor cinnaminyl-3,4-dihydroxy-α-cyanocinnamate.We then evaluated IL-1β-induced PGE2 production in islets purified from control C57BL/6 mice and 12-LO knockout mice lacking cytokine-inducible 12-HETE. IL-1β stimulated an 8-fold increase in PGE2 production in C57BL/6 islets but failed to stimulate PGE2 in 12-LO knockout islets. Addition of 12-HETE to 12-LO knockout islet cells produced a statistically significant rise in PGE2 production. Furthermore, 12-HETE, but not 15-HETE, stimulated COX-2 promoter and activator protein-1 binding activity. These data demonstrate that 12-HETE mediates cytokine-induced COX-2 gene transcription and resultant PGE2 production in pancreatic β-cells.
Persistent Parity-Induced Changes in Growth Factors, TGF-β3, and Differentiation in the Rodent Mammary Gland
Authors: D’Cruz Celina M. , Moody Susan E. , Master Stephen R. , Hartman Jennifer L. , Keiper Elizabeth A. , Imielinski Marcin B. , Cox James D. , Wang James Y. , Ha Seung I. , Keister Blaine A. , Chodosh Lewis A. 
Published: August 2002

AbstractEpidemiological studies have repeatedly demonstrated that women who undergo an early first full-term pregnancy have a significantly reduced lifetime risk of breast cancer. Similarly, rodents that have previously undergone a full-term pregnancy are highly resistant to carcinogen-induced breast cancer compared with age-matched nulliparous controls. Little progress has been made, however, toward understanding the biological basis of this phenomenon. We have used DNA microarrays to identify a panel of 38 differentially expressed genes that reproducibly distinguishes, in a blinded manner, between the nulliparous and parous states of the mammary gland in multiple strains of mice and rats. We find that parity results in the persistent down-regulation of multiple genes encoding growth factors, such as amphiregulin, pleiotrophin, and IGF-1, as well as the persistent up-regulation of the growth-inhibitory molecule, TGF-β3, and several of its transcriptional targets. Our studies further indicate that parity results in a persistent increase in the differentiated state of the mammary gland as well as lifelong changes in the hematopoietic cell types resident within the gland. These findings define a developmental state of the mammary gland that is refractory to carcinogenesis and suggest novel hypotheses for the mechanisms by which parity may modulate breast cancer risk.
The Effect of Suppressor of Cytokine Signaling 3 on GH Signaling in β-Cells
Authors: Rønn Sif G. , Hansen Johnny A. , Lindberg Karen , Karlsen Allan E. , Billestrup Nils 
Published: August 2002

AbstractGH is an important regulator of cell growth and metabolism. In the pancreas, GH stimulates mitogenesis as well as insulin production in β-cells. The cellular effects of GH are exerted mainly through activation of the Janus kinase-signal transducer and activator of transcription (STAT) pathway. Recently it has been found that suppressors of cytokine signaling (SOCS) proteins are able to inhibit GH-induced signal transduction. In the present study, the role of SOCS-3 in GH signaling was investigated in the pancreatic β-cell lines RIN-5AH and INS-1 by means of inducible expression systems. Via stable transfection of the β-cell lines with plasmids expressing SOCS-3 under the control of an inducible promoter, a time- and dose-dependent expression of SOCS-3 in the cells was obtained. EMSA showed that SOCS-3 is able to inhibit GH-induced DNA binding of both STAT3 and STAT5 in RIN-5AH cells. Furthermore, using Northern blot analysis it was shown that SOCS-3 can completely inhibit GH-induced insulin production in these cells. Finally, 5-bromodeoxyuridine incorporation followed by fluorescence-activated cell sorting analysis showed that SOCS-3 inhibits GH-induced proliferation of INS-1 cells. These findings support the hypothesis that SOCS-3 is a major regulator of GH signaling in insulin-producing cells.
The Mineralocorticoid Receptor May Compensate for the Loss of the Glucocorticoid Receptor at Specific Stages of Mammary Gland Development
Authors: Kingsley-Kallesen Michelle , Mukhopadhyay Sudit S. , Wyszomierski Shannon L. , Schanler Susan , Schütz Günther , Rosen Jeffrey M. 
Published: August 2002

AbstractTo study the role of glucocorticoid receptor (GR) at different stages of mammary gland development, mammary anlage were rescued from GR−/− mice by transplantation into the cleared fat pad of wild-type mice. In virgin mice, GR−/− outgrowths displayed abnormal ductal morphogenesis characterized by distended lumena, multiple layers of luminal epithelial cells in some regions along the ducts, and increased periductal stroma. In contrast, the loss of GR did not result in overt phenotypic changes in mammary gland development during pregnancy, lactation, and involution. Surprisingly, despite the known synergism between glucocorticoids and prolactin in the regulation of milk protein gene expression, whey acidic protein and β-casein mRNA levels were unaffected in GR−/− transplants as compared with wild-type transplants. That mineralocorticoid receptor (MR) might compensate for the loss of GR was suggested by the detection of MR in the mammary gland at d 1 of lactation. This hypothesis was tested using explant cultures derived from the GR−/− transplants in which the mineralocorticoid fludrocortisone was able to synergistically induce β-casein gene expression in the presence of prolactin and insulin. These studies suggest that MR may compensate for the absence of GR at some, but not at all stages of mammary gland development.
Ubc6p and Ubc7p Are Required for Normal and Substrate-Induced Endoplasmic Reticulum-Associated Degradation of the Human Selenoprotein Type 2 Iodothyronine Monodeiodinase
Authors: Botero Diego , Gereben Balazs , Goncalves Carla , de Jesus Lucia A. , Harney John W. , Bianco Antonio C. 
Published: August 2002

Abstract
The type 2 monodeiodinase (D2) is an endoplasmic reticulum-resident membrane selenoprotein responsible for catalyzing the first step in thyroid hormone action, T4 deiodination to T3. Its short half-life is due to ubiquitination and proteolysis by proteasomes, a mechanism that is accelerated by D2 interaction with T4. To identify proteins involved in D2 ubiquitination, a FLAG-tagged selenocystine133-to-Cys mutation of the human D2 (CysD2) was created and expressed in Saccharomyces cerevisiae using the GAL1 gene promoter. CysD2 activity was detected in the microsomes, indistinguishable from transiently expressed CysD2 in vertebrate cells. Treatment with 100 mg/ml cycloheximide or 30 μm T4 caused rapid loss of CysD2 (t1/2 = ∼30 min). Clasto-lactacystin β-lactone not only increased galactose-inducible CysD2 but also stabilized CysD2 in the presence of cycloheximide or T4. Immunoprecipitation with anti-FLAG antibody combined with Western analysis with antiubiquitin revealed that CysD2 is heavily ubiquitinated. Expression of CysD2 in yeast strains that lack the ubiquitin conjugases Ubc6p or Ubc7p stabilized CysD2 half-life by markedly reducing CysD2 ubiquitination, whereas no difference was detected in Ubc1p-deficient mutants. Similarly, expression of CysD2 in UBC6 and UBC7 mutants also impaired the substrate-induced loss of CysD2 activity and protein. In conclusion, Ubc6p and Ubc7p are required for normal and substrate-induced ubiquitination and proteolysis of D2.
Comparative Genomic Sequence Analysis of the Human Chromosome 21 Down Syndrome Critical Region
Authors: Toyoda Atsushi , Noguchi Hideki , Taylor Todd D. , Ito Takehiko , Pletcher Mathew T. , Sakaki Yoshiyuki , Reeves Roger H. , Hattori Masahira 
Published: September 2002

Comprehensive knowledge of the gene content of human chromosome 21 (HSA21) is essential for understanding the etiology of Down syndrome (DS). Here we report the largest comparison of finished mouse and human sequence to date for a 1.35-Mb region of mouse chromosome 16 (MMU16) that corresponds to human chromosome 21q22.2. This includes a portion of the commonly described “DS critical region,” thought to contain a gene or genes whose dosage imbalance contributes to a number of phenotypes associated with DS. We used comparative sequence analysis to construct a DNA feature map of this region that includes all known genes, plus 144 conserved sequences ≥100 bp long that show ≥80% identity between mouse and human but do not match known exons. Twenty of these have matches to expressed sequence tag and cDNA databases, indicating that they may be transcribed sequences from chromosome 21. Eight putative CpG islands are found at conserved positions. Models for two human genes, DSCR4 and DSCR8, are not supported by conserved sequence, and close examination indicates that low-level transcripts from these loci are unlikely to encode proteins. Gene prediction programs give different results when used to analyze the well-conserved regions between mouse and human sequences. Our findings have implications for evolution and for modeling the genetic basis of DS in mice.[Sequence data described in this paper have been submitted to the DDBJ/GenBank under accession nos. AP003148through AP003158, and AB066227. Supplemental material is available athttp://www.genome.org.]
Genome-Wide Analysis of the Odorant-Binding Protein Gene Family in Drosophila melanogaster
Authors: Hekmat-Scafe Daria S. , Scafe Charles R. , McKinney Aimee J. , Tanouye Mark A. 
Published: September 2002

Olfaction is of considerable importance to many insects in behaviors critical for survival and reproduction, including location of food sources, selection of mates, recognition of colony con-specifics, and determination of oviposition sites. An ubiquitous, but poorly understood, component of the insect's olfactory system is a group of odorant-binding proteins (OBPs) that are present at high concentrations in the aqueous lymph surrounding the dendrites of olfactory receptor neurons. OBPs are believed to shuttle odorants from the environment to the underlying odorant receptors, for which they could potentially serve as odorant presenters. Here we show that the Drosophilagenome carries 51 potential OBP genes, a number comparable to that of its odorant-receptor genes. We find that the majority (73%) of these OBP-like genes occur in clusters of as many as nine genes, in contrast to what has been observed for the Drosophila odorant-receptor genes. Two of the presumptive OBP gene clusters each carries an odorant-receptor gene. We also report an intriguing subfamily of 12 putative OBPs that share a unique C-terminal structure with three conserved cysteines and a conserved proline. Members of this subfamily have not previously been described for any insect. We have performed phylogenetic analyses of the OBP-related proteins inDrosophila as well as other insects, and we discuss the duplication and divergence of the genes for this large family.[The sequence data from this study have been submitted to FlyBase. Annotations for these sequences are available as supplementary material at http://www.genome.org.]
Temperature-Regulated Transcription in the Pathogenic Fungus Cryptococcus neoformans
Authors: Steen Barbara R. , Lian Tian , Zuyderduyn Scott , MacDonald William Kim , Marra Marco , Jones Steven J.M. , Kronstad James W. 
Published: September 2002

The basidiomycete fungus Cryptococcus neoformans is an opportunistic pathogen of worldwide importance that causes meningitis, leading to death in immunocompromised individuals. Unlike many basidiomycete fungi, C. neoformans is thermotolerant, and its ability to grow at 37°C is considered to be a virulence factor. We used serial analysis of gene expression (SAGE) to characterize the transcriptomes of C. neoformans strains that represent two varieties with different polysaccharide capsule serotypes. These include a serotype D strain of the C. neoformans varietyneoformans and a serotype A strain of variety grubii. In this report, we describe the construction and characterization of SAGE libraries from each strain grown at 25°C and 37°C. The SAGE data reveal transcriptome differences between the two strains, even at this early stage of analysis, and identify sets of genes with higher transcript levels at 25°C or 37°C. Notably, growth at the lower temperature increased transcript levels for histone genes, indicating a general influence of temperature on chromatin structure. At 37°C, we noted elevated transcript levels for several genes encoding heat shock proteins and translation machinery. Some of these genes may play a role in temperature-regulated phenotypes in C. neoformans, such as the adaptation of the fungus to growth in the host and the dimorphic transition between budding and filamentous growth. Overall, this work provides the most comprehensive gene expression data available forC. neoformans; this information will be a critical resource both for gene discovery and genome annotation in this pathogen.[This paper is dedicated to the memory of Michael Smith, founding director of the Biotechnology Laboratory and the British Columbia Genome Sciences Centre. The following individuals kindly provided reagents, samples, or unpublished information as indicated in the paper: Brendan Loftus, Claire Fraser, Richard Hyman, Eula Fung, Don Rowley, Ron Davis , Bruce A. Roe, Doris Kupfer, Jennifer Lewis, Sola Yu, Kent Buchanan, Dave Dyer, and Juneann Murphy.]
On the Stationarity of Savings in the United States
Authors: Brodsky Noel 
Published: August 2002

The question of stationarity of saving as a percent of disposable personal income is examined in detail. National Income and Product Accounts data is taken annually from 1929-1988, and quarterly from 1970-1988. The initial approach uses Dickey-Fuller (1987) tests. Their results indicate that, depending on the time period chosen, one is led to believe that both stationarity and non-stationarity exist in the data. ARIMA models are then fitted to both annual and quarterly data. Relatively large non-difference models are necessary to fit the long-range annual data (1929-1988), while relatively small differentiated models fit quarterly and short-range annual (1946-I 988) models. It is concluded that at least for saving as a percent of disposable income in the US, it is reasonable to believe that saving is not a stationary process. Quarterly Review of Economics & Finance, Summer 1994, 34(2):
183-I 93. (Reprinted with permission of ABIfInform, Copyright UMI.)
An ontology model to facilitate knowledge-sharing in multi-agent systems
Authors: TAMMA VALENTINA , BENCH-CAPON TREVOR 
Published: August 2002

This article presents and motivates an extended ontology knowledge model which represents explicitly semantic information about concepts. This knowledge model results from enriching the standard conceptual model with semantic information which precisely characterises the concept's properties and expected ambiguities, including which properties are prototypical of a concept and which are exceptional, the behaviour
of properties over time and the degree of applicability of properties to subconcepts. This enriched conceptual model permits a precise characterisation of what is represented by class membership mechanisms and helps knowledge engineers to determine, in a straightforward manner, the meta-properties holding for a concept. Meta-properties are recognised to be
the main tool for a formal ontological analysis that allows us to build ontologies with a clean and untangled taxonomic structure.This enriched semantics can prove useful to describe what is known by agents in a multi-agent system, and might facilitate the use of reasoning mechanisms on the knowledge that instantiates an ontology. These mechanisms can be used to solve ambiguities that can arise when agents with heterogeneous ontologies have to interoperate in order to perform a task.
‘French is the Language of Love and Stuff’: Student perceptions of issues related to motivation in learning a foreign language
Authors: Williams Marion , Burden Robert , Lanvers Ursula 
Published: August 2002

AbstractThis article reports on an investigation into the motivation of secondary school students in the South‐west of England to learn foreign languages. A questionnaire was constructed based on a model derived from the motivation literature to examine students' responses on 16 constructs related to motivation. This was administered to 228 students in years 7, 8 and 9. The analysis revealed a decrease in motivation with age, and higher level of motivation among girls than boys. It also revealed a strikingly higher motivation to learn German than French, which was even more marked when the boys only were considered. These findings were further investigated using interviews. Both girls and boys were able to provide clear explanations for differences between the genders, as well as for the language differences. These included such aspects as French being considered feminine, it not being ‘cool’ for boys to be seen to make an effort at French, and the tendency for boys not to try at anything that appears to be tedious.