bluuebunny/crossref_metadata_2025 huggingface dataset:
Hexamerin-based regulation of juvenile hormone-dependent gene expression underlies phenotypic plasticity in a social insect
Authors: Zhou Xuguo , Tarver Matthew R. , Scharf Michael E.
Published: January 2007

Worker termites of the genus Reticulitermes are temporally-arrested juvenile forms that can terminally differentiate into adultsoldier- or reproductive-caste phenotypes. Soldier-caste differentiation is a developmental transition that is induced by high juvenile hormone (JH)titers. Recently, a status quo hexamerin mechanism was identified, which reduces JH efficacy and maximizes colony fitness via the maintenance of high worker-caste proportions. Our goal in these studies was to investigate more thoroughly the influences of the hexamerins on JH-dependent gene expression in termite workers. Our approach involved RNA interference (RNAi), bioassays and quantification of gene expression. We first investigated the expression of 17 morphogenesis-associated genes in response to RNAi-based hexamerin silencing. Hexamerin silencing resulted in significant downstream impacts on 15 out of the 17 genes, suggesting that these genes are members of a JH-responsive genomic network. Next, we compared gene-expression profiles in workers after RNAi-based hexamerin silencing to that of (i) untreated workers that were held away from the colony; and (ii) workers that were also held away from the colony, but with ectopic JH. Here, although there was no correlation between hexamerin silencing and colony-release effects, we observed a significant correlation between hexamerin silencing and JH-treatment effects. These findings provide further evidence supporting the hypothesis that the hexamerins modulate JH availability, thus limiting the impacts of JH on termite caste polyphenism. Results are discussed in a context relative to outstanding questions on termite developmental biology, particularly on regulatory gene networks that respond to JH-, colony- and environmental-cues.
Role of EGF-induced tyrosine phosphorylation of reggie-1/flotillin-2 in cell spreading and signaling to the actin cytoskeleton
Authors: Neumann-Giesen Carolin , Fernow Inga , Amaddii Monia , Tikkanen Ritva
Published: January 2007

Cholesterol and sphingolipid-rich membrane microdomains or rafts have been shown to be involved in signaling through many growth factor receptors but the molecular details of these processes are not well understood. The reggie/flotillin proteins are ubiquitously expressed proteins with a poorly characterized function. They are constitutively associated with membrane rafts by means of acylation and oligomerization. Previous studies have implicated reggies in signaling, regulation of actin cytoskeleton and in membrane transport processes. In this study, we analyzed the putative role of reggie-1/flotillin-2 in signaling through the epidermal growth factor receptor. We show that reggie-1 becomes phosphorylated by Src kinase at several tyrosines upon stimulation of cells with epidermal growth factor. In addition, Src and reggie-1 are present as a molecular complex. Epidermal growth factor stimulation of cells results in a Tyr163-dependent translocation of reggie-1 from the plasma membrane into endosomes. We also show that reggie-1 is capable of enhancing the spreading of cells, again in a tyrosine-dependent manner, and knockdown of reggie-1 interferes with spreading. Thus, we reveal a new function for reggie-1 in the regulation of cell adhesion and actin dynamics and in growth factor signaling.
Transmitting on actin: synaptic control of dendritic architecture
Authors: Schubert Vanessa , Dotti Carlos G.
Published: January 2007

Excitatory synaptic transmission in the central nervous system mainly takes place at dendritic spines, highly motile protrusions on the dendritic surface. Depending on the stimuli received, dendritic spines undergo rapid actin-based changes in their morphology. This plasticity appears to involve signaling through numerous proteins that control the organization of the actin cytoskeleton (actin regulators). At least in part, recruitment and activation of these depends on neurotransmitter receptors at the post-synapse, which directly link neurotransmission to changes in dendritic spine architecture. However, other, non-neurotransmitter-receptors present at dendritic spines also participate. It is likely that several receptor types can control the activity of a single actin-regulatory pathway and it is the complex integration of numerous signals that determines the overall architecture of a dendritic spine.
Phosphorylation of Spc110p by Cdc28p-Clb5p kinase contributes to correct spindle morphogenesis in S. cerevisiae
Authors: Huisman Stephen M. , Smeets Monique F. M. A. , Segal Marisa
Published: January 2007

Spindle morphogenesis is regulated by cyclin-dependent kinases and monitored by checkpoint pathways to accurately coordinate chromosomal segregation with other events in the cell cycle. We have previously dissected the contribution of individual B-type cyclins to spindle morphogenesis in Saccharomyces cerevisiae. We showed that the S-phase cyclin Clb5p is required for coupling spindle assembly and orientation. Loss of Clb5p-dependent kinase abolishes intrinsic asymmetry between the spindle poles resulting in lethal translocation of the spindle into the bud with high penetrance in diploid cells. This phenotype was exploited in a screen for high dosage suppressors that yielded spc110Δ13, encoding a truncation of the spindle pole body component Spc110p (the intranuclear receptor for the γ-tubulin complex). We found that Clb5p-GFP was localised to the spindle poles and intranuclear microtubules and that Clb5p-dependent kinase promoted cell cycle dependent phosphorylation of Spc110p contributing to spindle integrity. Two cyclin-dependent kinase consensus sites were required for this phosphorylation and were critical for the activity of spc110Δ13 as a suppressor. Together, our results point to the function of cyclin-dependent kinase phosphorylation of Spc110p and provide, in addition, support to a model for Clb5p control of spindle polarity at the level of astral microtubule organisation.
Misassembled mutant ΔF508 CFTR in the distal secretory pathway alters cellular lipid trafficking
Authors: Gentzsch Martina , Choudhury Amit , Chang Xiu-bao , Pagano Richard E. , Riordan John R.
Published: January 2007

Most patients with cystic fibrosis (CF) have a single codon deletion (ΔF508) in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) that impairs assembly of the multidomain glycoprotein. The mutant protein escapes endoplasmic reticulum (ER) quality control at low temperature, but is rapidly cleared from the distal secretory pathway and degraded in lysosomes. CF cells accumulate free cholesterol similar to Niemann-Pick disease type C cells. We show that this lipid alteration is caused by the presence of misassembled mutant CFTR proteins, including ΔF508, in the distal secretory pathway rather than the absence of functional CFTR. By contrast, cholesterol distribution is not changed by either D572N CFTR, which does not mature even at low temperature, or G551D, which is processed normally but is inactive. On expression of the ΔF508 mutant, cholesterol and glycosphingolipids accumulate in punctate endosomal structures and cholesterol esters are reduced, indicating a block in the translocation of cholesterol to the ER for esterification. This is overcome by Rab9 overexpression, resulting in clearance of accumulating intracellular cholesterol. Similar but less pronounced alterations in intracellular cholesterol distribution are observed on expression of a temperature-rescued mutant variant of the related ATP-binding cassette (ABC) protein multidrug resistance-associated protein 1 (MRP1). Thus, on escape from ER quality control, misassembled mutants of CFTR and MRP1 impair lipid homeostasis in endocytic compartments.
Characterisation of Plasmodium falciparum RESA-like protein peptides that bind specifically to erythrocytes and inhibit invasion
Authors: Rodriguez Luis Eduardo , Vera Ricardo , Valbuena John , Curtidor Hernando , Garcia Javier , Puentes Alvaro , Ocampo Marisol , Lopez Ramses , Rosas Jaiver , Lopez Yolanda , Patarroyo Manuel A. , Patarroyo Manuel E.
Published: January 2007

The Plasmodium falciparum ring-erythrocyte surface antigen (RESA)-like putative protein was identified and characterised. PCR and RT-PCR assays revealed that the gene encoding this protein was both present and being transcribed in P. falciparum strain FCB-2 16 h after erythrocyte invasion. Indirect immunofluorescence studies detected this protein in infected erythrocyte (IE) cytosol in dense fluorescent granules similar to Maurer's clefts at 16–20 h (parasites in ring and trophozoite stages) and very strongly on IE membranes at 22 h, suggesting that it is synthesised during early ring stages (16 h) and transported to the infected red blood cell (RBC) membrane surface during the trophozoite stage (22 h). Western blotting showed that antisera produced against polymerised synthetic peptides of this protein recognised a 72-kDa band in P. falciparum schizont lysate. P. falciparum RESA-like peptides used in normal RBC binding assays revealed that peptides 30326 (101NAEKI LGFDD KNILE ALDLFY120), 30334 (281RVTWK KLRTK MIKAL KKSLTY300) and 30342 (431SSPQR LKFTA GGGFC GKLRNY450) bind with high activity and saturability, presenting nM affinity constants. These peptides contain α-helical structural elements, as determined by circular dichroism, and inhibit P. falciparum in vitro invasion of normal RBCs by up to 91%, suggesting that some RESA-like protein regions are involved in intra-erythrocyte stage P. falciparum invasion.
Conformational studies on Arabidopsis sulfurtransferase AtStr1 with spectroscopic methods
Authors: Bartels Andrea , Forlani Fabio , Pagani Silvia , Papenbrock Jutta
Published: January 2007

Sulfurtransferases/rhodaneses (Str) are enzymes widely distributed in archaea, prokaryota and eukaryota, and catalyze the transfer of sulfur from a donor molecule to a thiophilic acceptor substrate. In this reaction, Str cycles between the sulfur-free and the sulfur-substituted form. Two-domain Str consist of two globular domains of nearly identical size and conformation connected by a short linker sequence, which is elongated in plant two-domain Str proteins compared to Str in other organisms. The two-domainArabidopsis thalianaStr1 protein (At1g79230) was expressed inEscherichia colias a mature protein, as a variant without the elongated linker sequence, and as AtStr1C332S and AtStr1C339V. The persulfuration state of the purified recombinant proteins was investigated in the presence and absence of sulfur donors by fluorescence spectroscopy. The secondary structure was analyzed by circular dichroism (CD) in the far-UV range, while overall changes in tertiary structure were determined by CD in the near-UV range. Finally, protein stability was analyzed by tryptic digestion. The elongated linker sequence is essential for correct conformation and stability, and thereby affects the catalytic activity of AtStr1. Replacement of the catalytic cysteine residue C332 leads to higher rigidity of the molecule, whereas replacement of C339 does not lead to any conformational changes, providing evidence of the direct involvement of C339 in catalysis.
Neural Attunement Processes in Infants during the Acquisition of a Language-Specific Phonemic Contrast
Authors: Minagawa-Kawai Yasuyo , Mori Koichi , Naoi Nozomi , Kojima Shozo
Published: January 2007

To elucidate the developmental neural attunement process in the language-specific phonemic repertoire, cerebral hemodynamic responses to a Japanese durational vowel contrast were measured in Japanese infants using near-infrared spectroscopy. Because only relative durational information distinguishes this particular vowel contrast, both first and second language learners have difficulties in acquiring this phonemically crucial durational difference. Previous cross-linguistic studies conducted on adults showed that phoneme-specific, left-dominant neural responses were observed only for native Japanese listeners. Using the same stimuli, we show that a larger response to the across-category changes than to the within-category changes occurred transiently in the 6- to 7-month-old group before stabilizing in the groups older than 12 months. However, the left dominance of the phoneme-specific response in the auditory area was observed only in the groups of 13 months and above. Thus, the durational phonemic contrast is most likely processed first by a generic auditory circuit at 6–7 months as a result of early auditory experience. The neural processing of the contrast is then switched over to a more linguistic circuit after 12 months, this time with a left dominance similar to native adult listeners.
Lack of Hypoxia-Inducible Factor-1α Impairs Midbrain Neural Precursor Cells Involving Vascular Endothelial Growth Factor Signaling
Authors: Milosevic Javorina , Maisel Martina , Wegner Florian , Leuchtenberger Julia , Wenger Roland H. , Gerlach Manfred , Storch Alexander , Schwarz Johannes
Published: January 2007

Oxygen tension is critical for proliferation of human and murine midbrain-derived neural precursor cells (mNPCs). Here, we conditionally inactivated the hypoxia-responsive transcription factor hypoxia-inducible factor-1α (HIF-1α) in murine NPCs to determine its role in proliferation, survival, and dopaminergic differentiationin vitroas well as survival of murine dopaminergic neuronsin vivo. HIF-1α conditional knock-out (HIF-1α CKO) mNPCs showed midbrain-specific impairment of survival and proliferation. Dopaminergic differentiation of HIF-1α CKO mNPCsin vitrowas markedly reduced. Expression of vascular endothelial growth factor (VEGF) mRNA was reduced in HIF-1α CKO mNPCs, whereas erythropoietin signaling was not affected. Treatment of HIF-1α CKO mNPCs with 50 ng/ml VEGF partially recovered proliferation and dopaminergic differentiationin vitro. In substantia nigra (SN) of adult HIF-1α CKO mice, protein levels of dopaminergic marker molecules such as tyrosine hydroxylase (TH) and aldehyde dehydrogenase were reduced by 41 and 61%, respectively. The cell survival marker Bcl-2 was reduced by 58% while caspase-3 was activated. Nonbiased stereological cell counts of TH-positive neurons in SN of young adult HIF-1α CKO mice revealed a reduction of 31% compared with cre/wt mice (in which the wild- typeHif1aallele is expressed in parallel with the Cre recombinase allele). However, we found no impairment of striatal dopamine concentrations or locomotor behavior. In conclusion, HIF-1α seems to be a transcription factor relevant to the development and survival of substantia nigra dopaminergic neurons involving VEGF signaling.
Cholinergic Interneurons Control the Excitatory Input to the Striatum
Authors: Pakhotin Pavel , Bracci Enrico
Published: January 2007

How the extent and time course of presynaptic inhibition depend on the action potentials of the neuron controlling the terminals is unknown. We investigated this issue in the striatum using paired recordings from cholinergic interneurons and projection neurons. Glutamatergic EPSCs were evoked in projection neurons and cholinergic interneurons by stimulation of afferent fibers in the cortex and the striatum, respectively. A single spike in a cholinergic interneuron caused significant depression of the evoked glutamatergic EPSC in 34% of projection neurons located within 100 μm and 41% of cholinergic interneurons located within 200 μm. The time course of these effects was similar in the two cases, with EPSC inhibition peaking 20–30 ms after the spike and disappearing after 40–80 ms. Maximal depression of EPSC amplitude was up to 27% in projection neurons and to 19% in cholinergic interneurons. These effects were reversibly blocked by muscarinic receptor antagonists (atropine or methoctramine), which also significantly increased baseline EPSC (evoked without a preceding spike in the cholinergic interneuron), suggesting that some tonic cholinergic presynaptic inhibition was present. This was confirmed by the fact that lowering extracellular potassium, which silenced spontaneously active cholinergic interneurons, also increased baseline EPSC amplitude, and these effects were occluded by previous application of muscarinic receptor antagonists. Collectively, these results show that a single spike in a cholinergic interneuron exerts a fast and powerful inhibitory control over the glutamatergic input to striatal neurons.
Activity-Dependent Control of Slow Synaptic Vesicle Endocytosis by Cyclin-Dependent Kinase 5
Authors: Evans Gareth J. O. , Cousin Michael A.
Published: January 2007

The stimulated dephosphorylation of the dephosphin group of endocytic proteins by calcineurin and their subsequent rephosphorylation by cyclin-dependent kinase 5 (cdk5) is required for synaptic vesicle (SV) retrieval in central nerve terminals. However, the specific endocytic pathway(s) controlled by these enzymes is unknown. To address this issue, we combined functional and morphological assays of endocytosis in primary neuronal cultures with pharmacological and molecular ablation of calcineurin and cdk5 activity. During strong stimulation, inhibition of calcineurin or cdk5 blocked uptake of the activity-dependent membrane marker FM1–43, but not the more hydrophilic FM2–10. However, FM2–10 uptake-measured poststimulation was sensitive to cdk5 and calcineurin inhibition, indicating that a slow form of endocytosis persists after termination of stimulation. In parallel EM studies, inhibition of cdk5 during strong stimulation greatly reduced horseradish peroxidase labeling of plasma membrane-derived nerve terminal endosomes, but not SVs. Furthermore, during mild stimulation, FM1–43 uptake was unaffected by cdk5 inhibition and the SV membrane was exclusively retrieved via a single SV route, suggesting that recruitment of the endosomal route of membrane retrieval is activity dependent. Thus, we propose that the calcineurin/cdk5-dependent phosphorylation cycle of the dephosphins specifically controls a slow endocytic pathway that proceeds via endosomal intermediates and is activated by strong physiological stimulation in central nerve terminals.
Involvement of Non-NMDA Glutamate Receptors in Central Amygdala in Synaptic Actions of Ethanol and Ethanol-Induced Reward Behavior
Authors: Zhu Wei , Bie Bihua , Pan Zhizhong Z.
Published: January 2007

The central nucleus of the amygdala (CeA) plays a critical role in positive emotional responses that involve stimulus-reward learning and are induced by the reinforcing effects of many drugs of abuse, including alcohol. Behavioral studies have implicated CeA as a key brain structure in alcohol reward, but the underlying mechanisms are still poorly understood. Recent studies have demonstrated that both NMDA and non-NMDA receptors in CeA neurons are targets of acute and chronic alcohol in naive and alcohol-dependent animals. However, little is known about the role of CeA non-NMDA receptors in synaptic actions of alcohol and, particularly, in the behavior of alcohol reward. In the present study with both whole-cell voltage-clamp recordings in CeA slicesin vitroand analysis of an animal model of conditioned place preference (CPP)in vivo, we investigated the synaptic mechanisms for actions of acute and chronic ethanol on CeA non-NMDA receptor functions and their contribution to ethanol-induced reward behavior. Acute ethanol significantly inhibited evoked and miniature synaptic currents mediated by non-NMDA receptors through inhibitions of both postsynaptic non-NMDA receptors and presynaptic glutamate release involving N-type Ca2+channels. CeA neurons from rats exhibiting the ethanol-induced CPP behavior showed a significant increase in non-NMDA synaptic transmission. Blockade of this increased synaptic transmission through CeA microinjection abolished the CPP behavior. These results suggest that acute alcohol inhibits CeA non-NMDA synaptic transmission through both presynaptic and postsynaptic mechanisms, and chronic alcohol upregulates this synaptic activity, which is required for the alcohol-induced reward behavior.
Noncholinergic Lesions of the Medial Septum Impair Sequential Learning of Different Spatial Locations
Authors: Dwyer Trisha A. , Servatius Richard J. , Pang Kevin C. H.
Published: January 2007

The medial septum and diagonal band of Broca (MSDB) are major afferents to the hippocampus and are important for learning, memory, and hippocampal theta rhythm. In the present study, we assessed the effect of cholinergic or noncholinergic MSDB lesions on the sequential learning of different goal locations in the same environment, a type of task that is proposed to require hippocampal theta rhythm. Rats were administered saline, 192-IgG saporin (SAP), or kainic acid (KA) into the MSDB and then behaviorally tested. On any day, a single arm of a radial maze was rewarded with food, but the location of this rewarded arm changed between days. As in previous studies, intraseptal SAP reduced the number of cholinergic neurons although sparing GABAergic septohippocampal neurons. KA had the reverse effect, reducing GABAergic septohippocampal neurons and sparing cholinergic neurons. KA, but not SAP, impaired performance on the repeated acquisition task. Saline and SAP rats showed rapid within-session learning, whereas KA rats were much slower to learn the goal location. Performance on a 30 min retention trial was also impaired, although this may be attributable to incomplete acquisition. These findings provide evidence that noncholinergic, but not cholinergic, MSDB neurons are important in helping the animal deal with high loads of memory interference, and provides partial support for the idea that hippocampal theta rhythm is involved.
Altered Axonal Mitochondrial Transport in the Pathogenesis of Charcot-Marie-Tooth Disease from Mitofusin 2 Mutations
Authors: Baloh Robert H. , Schmidt Robert E. , Pestronk Alan , Milbrandt Jeffrey
Published: January 2007

Mutations in the mitochondrial fusion protein mitofusin 2 (MFN2) are the most commonly identified cause of Charcot-Marie-Tooth type 2 (CMT2), a dominantly inherited disease characterized by degeneration of peripheral sensory and motor axons. However, the mechanism by which mutations in this ubiquitously expressed mitochondrial fusion protein lead to neuropathy has not yet been elucidated. To explore how MFN2 mutations lead to degeneration of peripheral axons, we expressed neuropathy-associated forms of MFN2 in cultured dorsal root ganglion neurons, cells preferentially affected in CMT2. Disease-associated MFN2 mutant proteins induced abnormal clustering of small fragmented mitochondria in both neuronal cell bodies and proximal axons. Interestingly, transport of mitochondria in axons was significantly impaired in neurons expressing disease-mutated forms of MFN2. The diminished axonal mitochondrial transport was not attributable to diminished ATP levels in the neurons, and oxidative respiration was normal in mutant MFN2-expressing cells. Additionally, mitochondrial oxidative enzyme activity was normal in muscle mitochondria from a CMT2 patient with an MFN2 mutation, further supporting that abnormal mitochondrial transport in neurons is independent from an energy production defect. This abnormal mitochondrial trafficking provides a likely explanation for the selective susceptibility of the longest peripheral axons to MFN2 mutations, in which proper localization of mitochondria is critical for axonal and synaptic function.
Political Opportunities and Collective Identity in Ohio's Gay and Lesbian Movement, 1970 to 2000
Authors: Van Dyke Nella , Cress Ronda
Published: January 2007

Gender dynamics have historically shaped the gay and lesbian rights movement, with gay men and lesbians working together more during some time periods than others. In this article, the authors explore how changes in the sociopolitical context influence the gendered collective identity and gender composition of the gay and lesbian rights movement over time. The authors use data on the gay and lesbian rights movement in Columbus, Ohio, from 1970 to 2000 and interviews with twenty-four movement participants. They find that shifts in the sociopolitical context, including the activity of movement opponents, change the salience of gender and other identities for movement participants, thereby leading to changes in the movement's collective identity. They contribute to the literatures on gender, sexuality, and social movements by demonstrating that countermovements can mobilize stigma in a way that heightens identity salience and alters collective identities.
Single-Tooth Implant Restorations in the Esthetic Zone With PureForm Ceramic Crowns: 3 Case Reports
Authors: Schiroli Guido
Published: January 2007

The anterior maxillary jaw is frequently called the “esthetic zone” because of its high visibility and influence on facial appearance. Implant placement and single-tooth restoration in this region can present some esthetic challenges for the clinician. The underlying titanium abutment, for example, can diminish porcelain translucency and result in a darkened prosthesis. Subsequent changes in soft-tissue margins can also result in the visibility of titanium at the gingival crevice. In recent years, all-ceramic restorations have gained popularity in response to increasing patient demands for improved esthetics. This article describes the clinical use of a new, tooth-shaped, ceramic coping system in the restoration of single teeth in the esthetic zones of 3 patients. Four tapered screw implants were placed in the locations of the central incisors (n = 3) and bicuspid (n = 1). Conventional ceramic protocols were used to fabricate all-ceramic crowns that were cemented onto small core abutments attached to the implants. All prostheses restored the biomechanical needs of the patients and achieved excellent esthetic results.
Performance of push-in pressure cells in overconsolidated clay
Authors: Richards D. J. , Clark J. , Powrie W. , Heymann G.
Published: January 2007

Low-profile push-in pressure cells (spade cells) are commonly used to measure total horizontal stresses in both normally and overconsolidated clays. It is known that spade cells over-read the in situ stress in such deposits as a result of the complex localised stresses created during installation. Previous investigations into the magnitude of over-read are limited in number and have produced scattered results. During construction of the Channel Tunnel Rail Link at Ashford, Kent, a spade cell was installed horizontally in an overconsolidated clay, aligned to measure initial vertical stress, and the change in vertical stress due to excavation of material above the cell. The results of this experiment are presented and interpreted with reference to a finite element analysis and a comparison of spade cell and self-boring pressuremeter test data of horizontal stresses at the same site, to assess the performance of this type of spade cell in the Atherfield Clay.
Response toward novel stimuli in a group of tufted capuchins (Cebus libidinosus) in Brasília National Park, Brazil
Authors: Sabbatini Gloria , Stammati Margherita , Tavares Maria Clotilde H. , Visalberghi Elisabetta
Published: January 2007

We investigated responses toward novel foods and novel objects by wild capuchins that routinely exploit visitors' foods in Brasília National Park. Given the capuchins' daily exposure to human foods and objects, we expected them to be more explorative toward novel foods and objects compared to capuchins that are not habituated to visitors. However, since the safety and palatability of potential foods have to be learned, we also expected the capuchins to be cautious about eating novel foods, as has been reported for wild and captive capuchins. Stimuli were presented on a platform in four experimental conditions: familiar food (FF), novel food (NF), familiar food plus novel object (FF+O), and novel food plus novel object (NF+O). Latencies to approach and contact the platform, and to approach and to ingest food did not differ across conditions. Nevertheless, the capuchins were significantly more responsive (measured in terms of interest, manipulation, etc.) toward familiar foods than novel foods, and ate significantly more of the former. In other words, their explorative response toward novel foods led to little consumption. Our results do not support the “readiness to eat” hypothesis, according to which a lower readiness to eat and food neophobia are the consequences of the presence of a distracting novel object. The finding that capuchins explore novel stimuli but remain cautious about eating novel foods supports the view that neophilia and neophobia are motivationally independent responses. Am. J. Primatol. 69:1–14, 2007. © 2007 Wiley‐Liss, Inc.
Measurement of eye‐gaze in chimpanzees (Pan troglodytes)
Authors: Bethell Emily J. , Vick Sarah‐Jane , Bard Kim A.
Published: January 2007

Gaze cues are used as an index of social cognition in primates, yet the sensitivity to different forms of gaze, and consequently the cues required to test gaze‐following abilities remain understudied. Whereas the eye is attributed special signal value in humans, the camouflaged ocular morphology of non‐human primates has led to the consensus that head orientation may be a more salient cue. This study presents the first documentation of the surface eye movements of the chimpanzee, Pan troglodytes, in order to determine the behavioral forms of eye‐gaze and their saliency as signals, document their functional variation, and address the signal value of the eyes distinct from head orientation. Movements of the eye were identified as Scan (continuous movement), Glance (a single movement <1 sec), or Fixate (no movement). Scans, glances, and fixations were reliably detected by humans during live observation and from video (Cohen's kappa over 0.70) and, therefore, are likely also to be detected by conspecifics. Eye‐gaze comprised a nonunitary measure of visual attention, reflecting the attentional task demands of different activities. Specifically, chimpanzees spent significantly more time scanning while feeding and resting, than grooming, F(2,28) = 10.23, P<0.001, and spent significantly more time fixating while grooming, than feeding or resting, F(2,28) = 7.52, P<0.01. Further, eye‐gaze was often incongruent with head movement, varying significantly with the form of eye‐gaze: incongruence was found during 12–21% of fixations, during 42–49% of scans, and during 70–100% of glances, F(2,16) = 30.17, P<0.001. These findings provide the basis for discrimination of the adaptive significance of gaze‐processing abilities with emphasis on sensitivity to eye‐gaze distinct from head orientation. If we are to continue exploring gaze‐processing abilities in primates, then we need greater consideration of the precise nature of the signals themselves. Here we present evidence for special consideration of the eyes as a salient signal in P. troglodytes. Am. J. Primatol. 69:562–575, 2007. © 2007 Wiley‐Liss, Inc.
Are rotation curves in NGC 6946 and the Milky Way magnetically supported?
Authors: Battaner E. , Florido E.
Published: January 2007

The inner disk rotation of NGC 6946 and the Milky Way is dominated by gravity but magnetism is not negligible at radii where the rotation curve becomes flat, and indeed could become dominant at very large radii. Values of the order of 1 μG, or even less, produce a centripetal force when the absolute value of the slope of the curve [B φ , R ] (azimuthal field strength versus radius) is less than the slope of a B φ ‐profile proportional to R –1. The ∝ R –1‐profile is here called the critical profile. From the hypothesis of magnetically driven rotation curves, the following is to be expected: at large radii, a “subcritical” profile (slope flatter than R –1); at still larger radii a B φ ‐profile becoming asymptotically critical as the density becomes asymptotically vanishing. Recent observations of magnetic fields in NGC 6946 and the Milky Way are in very good agreement with these predictions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A planetary system with an escaping Mars
Authors: Süli Á. , Dvorak R.
Published: January 2007

The chaotic behaviour of the motion of the planets in our Solar System is well established. In this work to model a hypothetical extrasolar planetary system our Solar System was modified in such a way that we replaced the Earth by a more massive planet and let the other planets and all the orbital elements unchanged. The major result of former numerical experiments with a modified Solar System was the appearance of a chaotic window at κ E ∈ (4, 6), where the dynamical state of the system was highly chaotic and even the body with the smallest mass escaped in some cases. On the contrary for very large values of the mass of the Earth, even greater than that of Jupiter regular dynamical behaviour was observed. In this paper the investigations are extended to the complete Solar System and showed, that this chaotic window does still exist. Tests in different ‘Solar Systems’ clarified that including only Jupiter and Saturn with their actual masses together with a more ‘massive’ Earth (4 < κ E < 6) perturbs the orbit of Mars so that it can even be ejected from the system. Using the results of the Laplace‐Lagrange secular theory we found secular resonances acting between the motions of the nodes of Mars, Jupiter and Saturn. These secular resonances give rise to strong chaos, which is the cause of the appearance of the instability window. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phospholipid and triacylglycerol fatty acid content and pattern in the cardiac endothelium of rats depleted in long‐chain polyunsaturated ω3 fatty acids
Authors: Carpentier Yvon A. , Portois Laurence , Louchami Karim , Zhang Ying , Sener Abdullah , Malaisse Willy J.
Published: January 2007

Rats depleted in long‐chain polyunsaturated ω3 fatty acids (ω3‐depleted rats) display several features of the metabolic syndrome including hypertension and cardiac hypertrophy. This coincides with alteration of the cardiac muscle phospholipid and triacylglycerol fatty acid content and/or pattern. In the present study, the latter variables were measured in the cardiac endothelium of normal and ω3‐depleted rats. Samples derived from four rats each were obtained from 16 female normal fed rats and three groups of 36–40 female fed ω3‐depleted rats each aged 8–9, 15–16 and 22–23 weeks. At comparable mean age, the ratio between the square root of the total fatty acid content of phospholipids and cubic root of the total fatty acid content of triacylglycerols was lower in ω3‐depleted rats than in control animals. The total fatty acid content of triacylglycerols was inversely related to their relative content in C20:4ω6. Other differences between ω3‐depleted rats and control animals consisted in a lower content of long‐chain polyunsaturated ω3 fatty acids in both phospholipids and triacylglycerols, higher content of long‐chain polyunsaturated ω6 fatty acids in phospholipids, higher activity of Δ9‐desaturase (C16:0/C16:1ω7 and C18:0/C18:1ω9 ratios) and elongase [(C16:0 + C16:1ω7)/(C18:0 + C18:1ω9) and C20:4ω6/C22:4ω6 ratios], but impaired generation of C22:6ω3 from C22:5ω3 in the former rats. These findings support the view that cardiovascular perturbations previously documented in the ω3‐depleted rats may involve impaired heart endothelial function. Copyright © 2007 John Wiley & Sons, Ltd.
Structures of the High‐Temperature Solid Phases of the Odd‐Numbered Fatty Acids from Tridecanoic Acid to Tricosanoic Acid
Authors: Gbabode Gabin , Negrier Philippe , Mondieig Denise , Moreno Calvo Evelyn , Calvet Teresa , Cuevas‐Diarte Miquel Àngel
Published: January 2007

Crystal structures of the high‐temperature phases of odd‐numbered fatty acids (CnH2n−1OOH) from tridecanoic acid (C13H25OOH) to tricosanoic acid (C23H45OOH) are presented in this article. They have been determined from high‐quality X‐ray powder‐diffraction patterns. Two types of high‐temperature phases are adopted: one monoclinic A2/a with Z=8 for the fatty acids with n=13 and n=15, denoted as C′′, and one monoclinic P21/a with Z=4 for the longer‐chain fatty acids, denoted as C′. It appears that the packing arrangement of the alkyl chains and of the carboxyl groups is similar in all of the structures. However, the arrangement at the methyl‐group interface differs between the C′ and C′′ forms. A survey of the intermolecular interactions involved in these polymorphs coupled with a study of the effects of temperature on the structures have led us to a better understanding of the arrangement of the molecules within the high‐temperature solid phases of odd‐numbered fatty acids.
Polypeptide and Polypeptide Hybrid Copolymer Synthesis via NCA Polymerization
Authors: Deming Timothy J.
Published: January 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Simultaneous analysis of steady‐state intracellular pH and cell morphology by automated laser scanning cytometry
Authors: Koo Mei K. , Oh Chia H. , Holme Andrea L. , Pervaiz Shazib
Published: January 2007

Background:

Cytosolic pH (pHi) changes are critical in cellular response to diverse stimuli, including cell survival and death signaling. The potential drawback in flow‐based analysis is the inability to simultaneously visualize the cells during pHi measurements. Here, the suitability of laser scanning cytometer (LSC) in pHi measurement was investigated.

Aim:

Using the two extensively reported pH‐sensitive fluorescent probes, 2,7‐bis(2‐Carboxyethyl)‐5(6)‐carboxyfluorescein acetoxymethyl ester (BCECF‐AM) and 5‐(and‐6)‐carboxy SNARF‐1 acetoxymethyl ester, we evaluated the potential of automated LSC as a platform for simultaneous determination of pHi and cell morphology. The effect of a variety of buffer systems‐commonly employed for pHi measurements‐on cell morphology before pH clamping with the ionophore, nigericin, was also assessed.

Methods:

Measurement of cytosolic pH was performed using pH‐sensitive fluorescent probes BCECF‐AM and SNARF‐1. pH clamping was carried out using nigericin and samples were analyzed on the LSC or CyAn™ ADP Flow Cytometer.

Results:

The pHi clamping conditions were optimized as 140 mM potassium and 10 μM nigericin. The suitable buffers used for pH clamping: 140 mM KCl, 1 mM MgCl2, 2 mM CaCl2·2H2O, 5 mM glucose, 20 mM MES and 140mM KCl, 1 mM MgCl2, 2 mM CaCl2·2H2O, 5 mM glucose, and 20 mM Tris. Results obtained with the LSC strongly correlated with those obtained by flow cytometry.

Conclusion:

We report here that LSC is an excellent and highly reproducible platform for pHi determination, and provides the added advantage of simultaneous imaging of cells before, during, and after pH measurements. © 2007 International Society for Analytical Cytology.
A Sall4 mutant mouse model useful for studying the role of Sall4 in early embryonic development and organogenesis
Authors: Warren Madhuri , Wang Wei , Spiden Sarah , Chen‐Murchie Dongrong , Tannahill David , Steel Karen P. , Bradley Allan
Published: January 2007

SALL4 is a homologue of the Drosophila homeotic gene spalt, a zinc finger transcription factor, required for inner cell mass proliferation in early embryonic development. It also interacts with other transcription factors to control the development of the anorectal region, kidney, heart, limbs, and brain. Truncating mutations in SALL4 cause Okihiro syndrome, manifest as Duane anomaly, radial ray defects and sensorineural and conductive deafness. We report the characterization of a novel murine Sall4 null allele created by bacterial recombineering in ES cells. Homozygous mutant mice exhibit early embryonic lethality. Heterozygous mutant mice recapitulate phenotypic features of Okihiro syndrome including deafness, lower anogenital tract abnormalities, renal hypoplasia, anencephaly, Hirschprung's disease, and skeletal defects. This phenotype shows important differences in cardiac and ear manifestations to previously characterized Sall4 mutant alleles and should prove useful for the investigation of the influence of modifier alleles and protein interactions on the transcriptional regulatory function of Sall4. genesis 45:51–58, 2007. © 2007 Wiley‐Liss, Inc.
A microstrip‐line phase shifter constructed by a tunable filter
Authors: Morikawa Daisuke , Deguchi Hiroyuki , Tsuji Mikio , Shigesawa Hiroshi
Published: January 2007

A phase shifter configuration based on a bandpass filter that can change the phase continuously is discussed. In this configuration, the phase change due to resonance is used by making variable the center frequency of a filter with a broad passband. The configuration consisting of varactor diodes loaded on a microstrip line filter with short‐circuited stubs to decrease the insertion loss is studied in detail by analysis and experiment. The possibility of application to a phase shifter is verified. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(2): 25– 32, 2007; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecjb.20253
Long‐period earthquake ground displacements recorded on Guadeloupe (French Antilles)
Authors: Jousset P. , Douglas J.
Published: January 2007

Displacement time‐histories derived from accelerograms of three recent earthquakes in western North America (Hector Mine, Mw 7.1; Denali, Mw 7.9; and San Simeon, Mw 6.5) have been shown to feature large long‐period (∼10 s) ground‐motion cycles. Such long‐period displacements cause a localized peak within the displacement response spectrum that is currently not considered within any earthquake engineering design spectra. These displacement pulses have also been shown to be persistent and to feature on time‐histories from widely separated stations (∼20 km).

Broadband and accelerometric data from the Les Saintes earthquake sequence of 2004–2006 (4.9⩽Mw⩽5.3) recorded on Guadeloupe (French Antilles) are shown in this article to feature similar long‐period motions. The broadband data are used to independently corroborate the displacement time‐histories derived through high‐pass filtering and double integration of accelerometric data. It is shown that high‐quality broadband data are suitable for this purpose. The long‐period motions observed cause a localized peak in displacement response spectra at periods between 5 and 10 s. It is suggested here that the cause of these large‐amplitude long‐period motions are specific source mechanisms, which may possibly involve the presence of fluids within the source.

The form of the displacement response spectra from these time‐histories is significantly different from the spectral shape specified in recent seismic design codes since the peak in the spectra is at a much greater period than expected. This leads to an underestimation of spectral displacements for periods between about 5 and 10 s. Therefore, if these observed long‐period cycles are a common feature of earthquake ground motions the standard form of displacement design spectra may need to be reconsidered. Copyright © 2007 John Wiley & Sons, Ltd.
Addition and multiplication of sets
Authors: Kirby Laurence
Published: January 2007

Ordinal addition and multiplication can be extended in a natural way to all sets. I survey the structure of the sets under these operations. In particular, the natural partial ordering associated with addition of sets is shown to be a tree. This allows us to prove that any set has a unique representation as a sum of additively irreducible sets, and that the non‐empty elements of any model of set theory can be partitioned into infinitely many submodels, each isomorphic to the original model. Also any model of set theory has an isomorphic extension in which the empty set of the original model is non‐empty. Among other results, the relations between the arithmetical operations and the transitive closure and the adductive hierarchy are elucidated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Coherent Description of Nonlinear Flow Behavior of Entangled Polymers as Related to Processing and Numerical Simulations
Authors: Wang Shi‐Qing
Published: January 2007

This Feature Article describes a plausible picture of entangled polymer shear flow behavior, resulting from a decade of efforts in our laboratory to unravel the origins of a host of intricate and interconnected rheological phenomena. The first report of spurt flow by Bagley (1958) raised several key questions: Does the spurt flow reflect a constitutive failure as suggested by Vindogradov et al. (1972), Doi‐Edwards (1979) and McLeish‐Ball (1986)? How is it related to sharkskin, “melt fracture” and/or wall slip? The subject remained unsettled and “paradoxical” [Denn (1990)] until the 1990's when a first quantitative description of polymer slip was provided by Brochard and de Gennes (1992). The experimental elucidation [Rheol. Acta 1998, 37, 415] of the interfacial origin of the spurt flow led to the conclusion that the stress maximum in the Doi‐Edwards theory (1979) was a theoretical artefact and to a decade of efforts to derive a constitutive description of polymer flow by incorporating Marrucci's idea of convective constraint release (1996). Ongoing studies (2003–present) of constitutive flow and interfacial slip behavior of entangled polymer solutions have revealed something surprising: the entangled polybutadiene solutions appear to respond differently to rate‐controlled vs. stress‐controlled shear. The results [Macromolecules 2004, 37, 9083] imply that there would not necessarily be a homogeneous shear field in a simple‐shear apparatus in the rate‐controlled mode. An effective particle tracking velocimetric (PTV) method was developed to allow determination of the velocity profile across the gap in various shear apparatuses including cone‐plate and linear sliding‐plate setups for startup shear, large amplitude oscillatory shear (LAOS) and step strain experiments. Our PTV observations show an initial linear velocity variation across the gap and a nonlinear velocity profile beyond the shear stress overshoot [Phys. Rev. Lett. 2006, 96, 016001], growth of shear banding in LAOS [Phys. Rev. Lett. 2006, 96, 196001] and elastic breakup of several entangled solutions after step strain [Phys. Rev. Lett. 2006, 97, 187801]. These results present great challenges to both the prevailing theoretical description of entangled polymer flow that is based on tube models and the conventional rheometric protocols used to experimentally determine constitutive flow behavior, and questions the validity to perform numerical simulations of polymer processing based on the available constitutive models.

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Titan's ion chemistry: A laboratory perspective
Authors: McEwan Murray J. , Anicich Vincent G.
Published: January 2007

Some of the most interesting objects in the solar system are those bodies that have significant atmospheres. The discovery that Titan, Saturn's largest satellite, has a substantial nitrogen‐based atmosphere makes it a prime extraterrestrial object of interest. The advent of the Cassini orbiter spacecraft program that is able to observe and sample Titan's ionosphere adds greatly to this interest. We report here a summary of some of the efforts that have been made in the laboratory to understand the processes responsible for chemical processing of the primary ions formed in Titan's ionosphere, into the ions observed by in situ sampling. The presence of significant hydrocarbons and the colder temperatures of Titan's ionosphere lead to a much greater complexity in the ion chemistry of Titan than is apparent in the ion chemistry of Earth. A review of all the ion–molecule chemistry investigated in laboratory studies relevant to Titan is included as a table. The complexity of some of the hydrocarbon ion structures formed in just three reactive ion–molecule sequences from the primary ions has required a new experimental methodology which is discussed. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:281–319, 2007