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Consistent
Kinds of Consistent Terms modified by Consistent Selected AbstractsIS STATUS QUO BIAS CONSISTENT WITH DOWNWARD-SLOPING DEMAND?ECONOMIC INQUIRY, Issue 2 2008DONALD WITTMAN We show that status quo bias combined with downward-sloping demand implies addictive behavior. This result does not depend on transitivity, a complete ordering, or even the existence of a preference relation that rationalizes choices. (JEL D11, D81) [source] RESPONSE LETTER TO DR. BILLINGS: SHORTER SURVIVAL MAY POINT TO BETTER CARE CONSISTENT WITH PATIENT WISHESJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 9 2008Susan Enguidanos PhD No abstract is available for this article. [source] Using Population Count Data to Assess the Effects of Changing River Flow on an Endangered Riparian PlantCONSERVATION BIOLOGY, Issue 4 2006DIANE M. THOMSON análisis de viabilidad poblacional; gestión ribereña; método de difusión; presas; riesgo de extinción Abstract:,Methods for using simple population count data to project extinction risk have been the focus of much recent theoretical work, but few researchers have used these approaches to address management questions. We analyzed 15 years of census data on the federally endangered endemic riparian plant Pityopsis ruthii (Small) with the diffusion approximation (DA). Our goals were to evaluate relative extinction risk among populations in two different watersheds (in Tennessee, U.S.A.) and potential effects of variation in managed river flow on population dynamics. Populations in both watersheds had high projected risks of extinction within 50 years, but the causes of this risk differed. Populations of P. ruthii on the Hiwassee River had higher initial population sizes but significantly lower average growth rates than those on the Ocoee River. The only populations with low predicted short-term extinction risk were on the Ocoee. Growth rates for populations on both rivers were significantly reduced during periods of lower river flow. We found only marginal evidence of a quadratic relationship between population performance and flow. These patterns are consistent with the idea that low flows affect P. ruthii due to growth of competing vegetation, but the degree to which very high flows may reduce population growth is still unclear. Simulations indicated that populations were most sensitive to growth rates in low-flow years, but small changes in the frequency of these periods did not strongly increase risk for most populations. Consistent with results of other studies, DA estimates of extinction risk had wide confidence limits. Still, our results yielded several valuable insights, including the need for greater monitoring of populations on the Hiwassee and the importance of low-flow years to population growth. Our work illustrates the potential value of simple methods for analyzing count data despite the challenges posed by uncertainty in estimates of extinction risk. Resumen:,Los métodos que utilizan datos de conteos simples de la población para proyectar el riesgo de extinción han sido el foco reciente de mucho trabajo teórico, pero pocos investigadores han utilizado estos métodos para responder preguntas de gestión. Analizamos 15 años de datos de censos de la planta ribereña, endémica y federalmente en peligro Pityopsis ruthii (Small) mediante el método de difusión. Nuestras metas fueron evaluar el riesgo de extinción de poblaciones en dos cuencas hidrológicas distintas y con dos efectos potenciales de la variación del flujo de agua sobre la dinámica de la población. Las poblaciones en ambas cuencas tenían alto riesgo de extinción proyectado a 50 años, pero las causas de este riesgo difirieron. Las poblaciones de P. ruthii en el Río Hiwassee tuvieron poblaciones iniciales más grandes, pero tasas de crecimiento significativamente menores, que las poblaciones en el Río Ocoee. Las únicas poblaciones con bajo riesgo de extinción pronosticado estaban en el Ocoee. Las tasas de crecimiento de las poblaciones en ambos ríos se redujeron significativamente durante períodos de bajo flujo en el río. Sólo encontramos evidencia marginal de la relación cuadrática entre el funcionamiento de la población y el flujo. Estos patrones son consistentes con la idea de que los bajos flujos afectan a P. ruthii debido al crecimiento de vegetación competitiva, pero aun no es claro el grado en que flujos muy grandes pueden reducir el crecimiento poblacional. Las simulaciones indicaron que las poblaciones son más sensibles a las tasas de crecimiento en años con bajo flujo en los ríos, pero pequeños cambios en la frecuencia de esos períodos no aumentaron el riesgo en la mayoría de las poblaciones. Consistentemente con los resultados de otros estudios, las estimaciones del riesgo de extinción mediante el método de difusión tienen amplios límites de confianza. Aun así, nuestros resultados aportaron varios conocimientos valiosos, incluyendo la necesidad de mayor monitoreo de las poblaciones en el Hiwassee y la importancia para el crecimiento poblacional de los años con bajo flujo. Nuestro trabajo ilustra el valor potencial de métodos sencillos de análisis de datos de conteo a pesar de los retos impuestos por la incertidumbre en las estimaciones del riesgo de extinción. [source] Experience-dependent plasticity in hypocretin/orexin neurones: re-setting arousal thresholdACTA PHYSIOLOGICA, Issue 3 2010X.-B. Gao Abstract The neuropeptide hypocretin is synthesized exclusively in the lateral hypothalamus and participates in many brain functions critical for animal survival, particularly in the promotion and maintenance of arousal in animals , a core process in animal behaviours. Consistent with its arousal-promoting role in animals, the neurones synthesizing hypocretin receive extensive innervations encoding physiological, psychological and environmental cues and send final outputs to key arousal-promoting brain areas. The activity in hypocretin neurones fluctuates and correlates with the behavioural state of animals and intensive activity has been detected in hypocretin neurones during wakefulness, foraging for food and craving for addictive drugs. Therefore, it is likely that hypocretin neurones undergo experience-dependent changes resulting from intensive activations by stimuli encoding changes in the internal and external environments. This review summarizes the most recent evidence supporting experience-dependent plasticity in hypocretin neurones. Current data suggest that nutritional and behavioural factors lead to synaptic plasticity and re-organization of synaptic architecture in hypocretin neurones. This may be the substrate of enhanced levels of arousal resulting from behavioural changes in animals and may help to explain the mechanisms underlying the changes in arousal levels induced by physiological, psychological and environmental factors. [source] Publishing in the Majors: A Comparison of Accounting, Finance, Management, and Marketing,CONTEMPORARY ACCOUNTING RESEARCH, Issue 1 2004EDWARD P. SWANSON Abstract Business schools evaluate publication records, especially for the promotion and tenure decision, by comparing the quality and quantity of a candidate's research with those of peers within the same discipline (intradisciplinary) and with those of academics from other business disciplines (interdisciplinary). A recently developed analytical model of the research review process provides theory about the norms used by editors and referees in deciding whether to publish research papers. The model predicts that interdisciplinary differences exist in quality norms, which could result in disparity among business disciplines in the number of top-tier articles published. I examine the period from 1980 to 1999 and, consistent with the theory, find that significant differences exist in the number of articles and proportion of doctoral faculty who published in the "major" journals in accounting, finance, management, and marketing. Most notably, the proportion of doctoral faculty publishing a major article is 1.4 to 2.4 times greater in the other business disciplines than in accounting (depending on the set of journals). The theory also predicts an upward drift over time in the quality norms used by referees. Consistent with a drift, the number of articles published has declined substantially in marketing and, to a lesser extent, in the other business disciplines. [source] Improving Jurors' Evaluations of Auditors in Negligence Cases,CONTEMPORARY ACCOUNTING RESEARCH, Issue 3 2001Kathryn Kadous Abstract Prior research indicates that individuals acting as jurors experience outcome effects in audit negligence litigation. That is, jurors evaluate auditors more harshly in light of negative outcomes, even when audit quality is constant. I posit that outcome effects in this setting are caused by jurors using their negative affect (i.e., feelings) resulting from learning about negative audit outcomes as information relevant to auditor blameworthiness. I tested this hypothesis in an experiment in which I manipulated audit quality, outcome information, and provision of an attribution instruction. The attribution instruction was designed to discredit negative affect as a cue to auditor blameworthiness. Consistent with expectations, attribution participants' evaluations of auditors exhibited less reliance on outcome information and more reliance on audit quality information than did evaluations made by control participants. In fact, outcome effects were eliminated for attribution participants. Courts may be able to improve the quality of jurors' decisions in such cases by employing an attribution instruction. [source] SELF-CONTROL, CRIMINAL MOTIVATION AND DETERRENCE: AN INVESTIGATION USING RUSSIAN RESPONDENTSCRIMINOLOGY, Issue 2 2005CHARLES R. TITTLE With data from respondents in Nizhni Novgorod, Russia, we address the generality of self-control theory. We also assess two hypotheses. The first focuses on the attractiveness of criminal acts, that is, motivation toward crime. The second concerns the contention that the mediating link between self-control and criminal conduct is the failure of those with less self-control to anticipate the long-term costs of misbehavior. Although the magnitude of associations between self-control and indicators of criminal behavior is about the same in this study as it is in others, which suggests that the theory is not culturally bound, those associations are largely overshadowed by criminal attraction. Consistent with that, failure to anticipate costly long-term consequences does not appear to be the mediating link between self-control and criminal behavior: the evidence shows no tendency for sanction fear to be greater among those with greater self-control. In fact, sanction fear is modestly and significantly related to the crime measures independent of self-control, though sanction fear also appears to be influenced by criminal attraction. The results suggest that in the production of criminal behavior, motivation may be more important than controls inhibiting criminal impulses. [source] PATHWAYS TO SEX-BASED DIFFERENTIATION IN CRIMINAL COURT SENTENCINGCRIMINOLOGY, Issue 2 2003SAMANTHA JEFFRIES Using a matched sampling method, this research examined the process of sex-based differentiation in sentencing outcomes for 194 men and 194 women, sentenced over a seven-year period in Christchurch, New Zealand. Consistent with past research, our results showed that judicial processing treated women more leniently than men. Path analyses revealed that judges were less likely to sentence women than men to imprisonment terms because of gendered information and decisions made earlier in the judicial process, such as criminal history, length of custodial remands, and pre-sentence recommendations by probation officers. In contrast, judges exercised considerable leniency towards women (compared with men) in setting the length of prison terms, even after statistically controlling for all sex-differentiated factors such as criminal history. Explanations and implications are discussed. [source] Bandgap characters in GaAs-based ternary alloysCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2010N. Tit Abstract The existence and origins of the bowing character in the bandgap variation of GaAs-based ternary alloys are theoretically investigated based on two different computational methods. Within the framework of the virtual crystal approximation (VCA), both the empirical sp3s * tight-binding (TB) method with, and without, the inclusion of the spin-orbit coupling effects, and the first-principle full-potential linear augmented plane wave (FP-LAPW) technique are applied on both the common-cation GaSbxAs1-x and the common-anion Ga1-xInxAs alloys. These methods are used to calculate the bandgap energy, the partial and total densities of states and the constituent charge ionicity versus the composition x. The results show that the bowing behavior exists in the case of common-cation alloys (GaSbxAs1-x) as a manifestation of a competition between the anion atoms (As and Sb) in trapping the made-available-cationic charges. The bowing parameter is found to be proportional to the electronegativity characters of the competing anions (,anion). Consistent with this in the case of common-anion alloys (Ga1-xInxAs), as due to the lack of anion competition, the bowing is just absent and the variation of bandgap energy is found to be rather linear. The excellent agreement between our theoretical results and recent photoluminescence data has corroborated our claim. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] EndothelinA (ETA) and ETB receptor-mediated regulation of nitric oxide synthase 1 (NOS1) and NOS3 isoforms in the renal inner medullaACTA PHYSIOLOGICA, Issue 4 2007J. C. Sullivan Abstract Aim:, Our laboratory and others have shown that endothelin (ET)-1 directly stimulates nitric oxide (NO) production in inner medullary collecting duct (IMCD) cells. The goal of this study was to determine which NO synthase (NOS) isoforms in IMCD are sensitive to ET-1, and the role of ETA and ETB receptor activation in vivo and in vitro. Methods:, NOS enzymatic activity and NOS isoform protein expression were examined in cultured IMCD-3 cells and isolated renal inner medulla. ETB receptor-deficient homozygous rats (sl/sl) have elevated levels of circulating ET-1 and lack a functional ETB signalling pathway in kidneys, and furthermore provides a unique model to study ETA receptor signalling in the renal inner medulla in vivo. Results:, Incubation of IMCD-3 cells with exogenous ET-1 (50 nm) resulted in ETA -dependent increased NOS1 protein expression in IMCD-3 cells with no effect on NOS2 or NOS3 expression. ETB receptor antagonism has no effect on NOS expression in IMCD-3 cells. Consistent with in vitro results, cytosolic NOS1 protein expression was significantly greater in the renal inner medulla of sl/sl rats compared with heterozygous (sl/+) controls, with no alteration in NOS3 expression. In contrast to protein expression data, NOS1- and NOS3-specific enzymatic activities decreased in the cytosolic fraction from the renal inner medulla of sl/sl compared with sl/+. Conclusion:, These results provide evidence that both ETA and ETB receptors regulate NOS isoform activity in the renal inner medulla and specifically support the hypothesis that ETA receptor activation increases NOS1 expression. [source] TOGp regulates microtubule assembly and density during mitosis and contributes to chromosome directional instabilityCYTOSKELETON, Issue 8 2009Lynne Cassimeris Abstract TOGp, a member of the XMAP215 MAP family, is required for bipolar mitotic spindle assembly. To understand how TOGp contributes to spindle assembly, we examined microtubule dynamics after depleting TOGp by siRNA. Fluorescence recovery after photobleaching of GFP-tubulin demonstrated that spindle microtubule turnover is slowed two-fold in the absence of TOGp. Consistent with photobleaching results, microtubule regrowth after washout of the microtubule depolymerizing drug nocodazole was slower at the centrosomes and in the vicinity of mitotic chromatin in cells depleted of TOGp. The slower microtubule turnover is likely due to either nucleation or the transitions of dynamic instability because TOGp depletion did not effect the rate of plus end growth, measured by tracking EB1-GFP at microtubule ends. In contrast, microtubule regrowth after nocodazole washout was unaffected by prior depletion of TACC3, a centrosomal protein that interacts with TOGp. Kinetochore fibers in both untreated and TOGp-depleted cells were stable to incubation at 4°C or lysis in buffer containing calcium indicating that stable kinetochore-microtubule attachments are formed in the absence of TOGp. Depletion of TOGp, but not TACC3, reduced kinetochore oscillations during prometaphase/metaphase. Defects in oscillations are not due simply to multipolarity or loss of centrosome focus in the TOGp-depleted cells, since kinetochore oscillations appear normal in cells treated with the proteosome inhibitor MG132, which also results in multipolar spindles and centrosome fragmentation. We hypothesize that TOGp is required for chromosome motility as a downstream consequence of reduced microtubule dynamics and/or density. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] Negative appraisals and cognitive avoidance of intrusive memories in depression: a replication and extensionDEPRESSION AND ANXIETY, Issue 7 2008Alishia D. Williams B.A. (Hons.) Abstract Recent research has demonstrated that intrusive negative autobiographical memories represent a shared phenomenological feature of posttraumatic stress disorder (PTSD) and depression. A preliminary investigation (Starr and Moulds, 2006) successfully applied a cognitive appraisal model of PTSD to the maintenance of intrusive memories in depression. The current investigation sought to replicate and extend these findings. Two hundred and fifty first-year undergraduate students were interviewed to assess for the presence of a negative autobiographical memory that had spontaneously intruded in the past week. Participants completed self-report inventories assessing trait and situational employment of cognitive avoidance mechanisms in response to these memories. Consistent with Starr and Moulds, intrusion-related distress correlated with dysphoria, irrespective of intrusion frequency. Assigning negative appraisals to one's intrusive memory and attempts to control the memory were positively associated with intrusion-related distress, level of depression, and cognitive avoidance mechanisms. Additionally, negative appraisals and control influenced the employment rumination as an avoidant response to a greater degree than the corresponding trait tendency. Finally, negative appraisals and the use of cognitive mechanisms were predictive of depression concurrently. The results support the validity of borrowing from PTSD models to elucidate the cognitive mechanisms that maintain intrusive memories in depressed samples. Depression and Anxiety 0:1,8, 2007. © 2007 Wiley-Liss, Inc. [source] The expression of anger and its relationship to symptoms and cognitions in obsessive,compulsive disorderDEPRESSION AND ANXIETY, Issue 3 2005Stephen P. Whiteside Abstract We compared the association between obsessive,compulsive disorder (OCD) and the expression of anger in a sample of 71 patients and 71 college students. Some authors [Rubenstein et al., J Anxiety Disord 1995;9:1,9] have proposed that anger and hostility underlie the symptoms of OCD; however, there has been little empirical study of this relationship. One recent study [Whiteside and Abramowitz, Cog Therapy Res 2004;28:259,268] with college undergraduates found that the association between OCD symptoms and anger was attributable to depressive symptoms. In the present study, we compared the expression of anger in a sample of patients diagnosed with OCD and nonclinical volunteers. Consistent with the previous study, we found increased levels of anger in patients with OCD as compared to control participants; however, these differences could be attributed to between-group differences in general distress. These results were discussed within the framework of the cognitive theory of OCD. © 2005 Wiley-Liss, Inc. [source] Effects of buspirone and alprazolam treatment on the startle-potentiated startle responseDEPRESSION AND ANXIETY, Issue 3 2004Randall L. Commissaris Ph.D. Abstract The startle potentiated startle (SPS) paradigm has been reported to be an effective procedure for studying the conditioned enhancement of acoustic startle in the absence of electric shocks or extinction. This study examines the effects of two anxiolytic treatments, buspirone and alprazolam, on this SPS effect. Subjects were tested in the SPS paradigm 2 days a week (Monday and Thursday) for 10 weeks. Each startle test session consisted of 10 Noise Alone trials (115 dB acoustic noise burst presented for 40 ms) and 10 Light+Noise trials (115 dB acoustic stimuli presented during the latter 40 ms of a 3,540 ms period in which a 15-watt light was illuminated). Although there was no difference in startle amplitude on Noise Alone trials when compared to Light+Noise trials initially, by the end of the first test session and continuing throughout the duration of the experiment, startle amplitude on Light+Noise trials was significantly (approximately 50,75%) greater than on Noise Alone trials. After five control (i.e., no injection) SPS test sessions, once-weekly drug challenges were conducted over the course of 7 weeks. In these weekly drug challenges, subjects received acute treatment with various doses of the benzodiazepine anxiolytic alprazolam (0.25, 0.5, 1.0 mg/kg) or the novel anxiolytic buspirone (1.0, 2.0, 4.0 mg/kg); subjects also received vehicle treatment (0.5% methylcellulose) on one treatment day. All treatments were administered intraperitoneally (IP), 15 min before the start of startle testing. Consistent with previous reports, buspirone increased and alprazolam decreased startle amplitude on the Noise Alone trials; these effects were dose-related. Both agents reduced the magnitude of the SPS effect when it was expressed as the Light+Noise startle amplitude minus the Noise Alone startle amplitude. These findings are similar to the effects of these treatments in the traditional shock-based fear-potentiated startle paradigm. Depression and Anxiety 19:146,151, 2004. © 2004 Wiley-Liss, Inc. [source] Recent Changes in the Workforce and Practice of Dermatologic SurgeryDERMATOLOGIC SURGERY, Issue 3 2009EMILY P. TIERNEY MD BACKGROUND The increasing number of American College of Mohs Surgery (ACMS) fellowship positions over the last decade has resulted in a greater number of fellowship-trained surgeons in dermatologic surgery. METHODS Mohs micrographic fellowship-trained surgeons (MMFTSs) and non-Mohs fellowship-trained surgeons performing Mohs micrographic surgery (NMMFTSs) were compared using the American Academy of Dermatology Practice Profile Survey (2002/05). An analysis of recent Mohs fellowship classes was also performed. RESULTS In 2005, there was an equivalent proportion of MMFTSs and NMMFTSs in the workforce (ratio MMFTS:NMMFTS=0.9) but, in 2005, there was a shift in the youngest age cohort (29,39) to a greater proportion of MMFTSs (MMFTS:NMMFTS=1.55). In 2005, the youngest MMFTSs (29,39) were more likely to be female (47.1%) than of MMFTSs overall (24%). MMFTSs were 5 times as likely to be in full-time academic positions and performed 2 to 3 times as many Mohs cases per week as NMMFTSs. CONCLUSIONS Consistent with demographic shifts in dermatology, differences have emerged in the demographics, surgical volumes, and settings of MMFTSs and NMMFTSs. Recent increases in the ACMS fellowship positions have resulted in a greater proportion of MMFTSs among younger dermatologic surgeons. It will be important to follow how this increase in fellowship trainees affects the dermatologic surgery workforce. [source] Retinoic acid affects craniofacial patterning by changing Fgf8 expression in the pharyngeal ectodermDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 9 2008Makoto Abe Retinoic acid signaling plays important roles in establishing normal patterning and cellular differentiation during embryonic development. In this study, we show that single administration of retinoic acid at embryonic day 8.5 causes homeotic transformation of the lower jaw into upper jaw-like structures. This homeosis was preceded by downregulation of Fgf8 and Sprouty expression in the proximal domain of the first pharyngeal arch. Downregulation of mesenchymal genes such as Dlx5, Hand2, Tbx1 and Pitx2 was also observed. The oropharynx in retinoic acid-treated embryos was severely constricted. Consistent with this observation, Patched expression in the arch endoderm and mesenchyme was downregulated. Thus, retinoic acid affects the expression of subsets of epithelial and mesenchymal genes, possibly disrupting the regional identity of the pharyngeal arch. [source] Mi-2 chromatin remodeling factor functions in sensory organ development through proneural gene repression in DrosophilaDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2006Yasutoyo Yamasaki Mi-2, the central component of the nucleosome remodeling and histone deacetylation (NuRD) complex, is known as an SNF2-type ATP-dependent nucleosome remodeling factor. No morphological mutant phenotype of Drosophila Mi-2 (dMi-2) had been reported previously; however, we found that rare escapers develop into adult flies showing an extra bristle phenotype. The dMi-2 enhanced the phenotype of acHw49c, which is a dominant gain-of-function allele of achaete (ac) and produces extra bristles. Consistent with these observations, the ac -expressing proneural clusters were expanded, and extra sensory organ precursors (SOP) were formed in the dMi-2 mutant wing discs. Immunostaining of polytene chromosomes showed that dMi-2 binds to the ac locus, and dMi-2 and acetylated hisotones distribute on polytene chromosomes in a mutually exclusive manner. The chromatin immunoprecipitation assay of the wing imaginal disc also demonstrated a binding of dMi-2 on the ac locus. These results suggest that the Drosophila Mi-2/NuRD complex functions in neuronal differentiation through the repression of proneural gene expression by chromatin remodeling and histone deacetylation. [source] Financial Liberalisation in Southern Africa: An AssessmentDEVELOPMENT POLICY REVIEW, Issue 3 2004Obert Nyawata In the early 1990s many Southern African economies embarked on financial liberalisation. Although it is too soon to carry out sophisticated econometric analysis of this change in policy, the available empirical evidence may be inspected to see whether it lends support to advocates of financial liberalisation. In this article we explore the avenues through which financial liberalisation might be expected to exert an influence. Consistent with much of the existing literature, we discover that a degree of agnosticism is warranted. Financial liberalisation is no panacea and will not improve economic performance unless accompanied by sound economic policies. It remains difficult to isolate the effects of financial liberalisation from the data available. [source] Generation and characterization of a novel neural crest marker allele, Inka1-LacZ, reveals a role for Inka1 in mouse neural tube closureDEVELOPMENTAL DYNAMICS, Issue 4 2010Bethany S. Reid Abstract Previous studies identified Inka1 as a gene regulated by AP-2, in the neural crest required for craniofacial morphogenesis in fish and frog. Here, we extend the analysis of Inka1 function and regulation to the mouse by generating a LacZ knock-in allele. Inka1-LacZ allele expression occurs in the cephalic mesenchyme, heart, and paraxial mesoderm prior to E8.5. Subsequently, expression is observed in the migratory neural crest cells and their derivatives. Consistent with expression of Inka1 in tissues of the developing head during neurulation, a low percentage of Inka1,/, mice show exencephaly while the remainder are viable and fertile. Further studies indicate that AP-2, is not required for Inka1 expression in the mouse, and suggest that there is no significant genetic interaction between these two factors during embryogenesis. Together, these data demonstrate that while the expression domain of Inka1 is conserved among vertebrates, its function and regulation are not. Developmental Dynamics 239:1188,1196, 2010. © 2010 Wiley-Liss, Inc. [source] Coordination of development and metabolism in the pre-midblastula transition zebrafish embryoDEVELOPMENTAL DYNAMICS, Issue 7 2008Bryce A. Mendelsohn Abstract To define the mechanisms that coordinate early embryonic development and metabolism, we have examined the response of zebrafish embryos to anoxia before the midblastula transition. Our findings reveal that anoxic pre-midblastula transition embryos slow the cell cycle, arrest before the midblastula transition and can recover normally if restored to a normoxic environment. Analyses of respiratory rates reveal that pre-midblastula transition embryos are less reliant on oxidative phosphorylation than older embryos. Interestingly, arrest in anoxia occurs despite inhibition of zygotic transcription, revealing a central role for maternal factors in the response to energy limitation. Consistent with this concept, we demonstrate that the posttranslational energy-sensing AMP-activated protein kinase pathway is activated in anoxia in pre-midblastula transition embryos. Taken together, these findings demonstrate a maternal program capable of coordinating developmental rate and metabolism in the absence of transcription-based pathways or cell cycle checkpoints. Developmental Dynamics 237:1789,1798, 2008. © 2008 Wiley-Liss, Inc. [source] Nuclear receptor NR5A2 is required for proper primitive streak morphogenesisDEVELOPMENTAL DYNAMICS, Issue 12 2006Cassandre Labelle-Dumais Abstract NR5A2, also known as liver receptor homologue 1 (LRH-1) and fetoprotein transcription factor (FTF), is an orphan nuclear receptor involved in the regulation of cholesterol metabolism and steroidogenesis in the adult. NR5A2 was also shown to be expressed during early mouse embryogenesis. Consistent with its early expression pattern, a targeted disruption of this gene leads to embryonic lethality around the gastrulation period. To characterize the embryonic phenotype resulting from NR5A2 loss of function, we undertook morphological and marker gene analyses and showed that NR5A2,/, embryos display growth retardation, epiblast disorganization, a mild embryonic,extraembryonic constriction, as well as abnormal thickening of the proximo-posterior epiblast. We demonstrated that, although initial specification of the anterior,posterior axis occurred in the absence of NR5A2, primitive streak formation was impaired and neither embryonic nor extraembryonic mesoderm was generated. Moreover, although the visceral endoderm does not show major morphological abnormalities in NR5A2,/, embryos, a decrease in the expression level of HNF4 and GATA4 was observed. Aggregation experiments demonstrated that, in the presence of wild-type tetraploid cells, NR5A2 mutant cells in the epiblast are capable of undergoing normal gastrulation. Therefore, our results suggest a requirement for NR5A2 in extraembryonic tissues and identify a novel role of this gene in proper primitive streak morphogenesis. Developmental Dynamics 235:3359,3369, 2006. © 2006 Wiley-Liss, Inc. [source] Gap junctions are involved in cell migration in the early postnatal subventricular zoneDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2009Mônica Marins Abstract The massive migration of neuroblasts and young neurons through the anterior extension of the postnatal subventricular zone (SVZ), known as the rostral migratory stream (RMS) is still poorly understood on its molecular basis. In this work, we investigated the involvement of gap junctional communication (GJC) in the robust centrifugal migration from SVZ/RMS explants obtained from early postnatal (P4) rats. Cells were dye-coupled in homocellular and heterocellular pairings and expressed at least two connexins, Cx 43 and 45. Treatment with the uncoupler agent carbenoxolone (CBX, 10,100 ,M) reversibly reduced outgrowth from SVZ explants, while its inactive analog, glycyrhizinic acid (GZA), had no effect. Consistent with a direct effect on cell migration, time-lapse video microscopy show that different pharmacological uncouplers cause an abrupt and reversible arrest of cell movement in explants. Our results indicate that GJC is positively involved in the migration of neuroblasts within the SVZ/RMS. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Transcriptional profiling of brain-derived-neurotrophic factor-induced neuronal plasticity: A novel role for nociceptin in hippocampal neurite outgrowthDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2006Robert H. Ring Abstract Brain derived neurotrophic factor (BDNF) exhibits a sequence of actions on neurons ranging from acute enhancement of transmission to long-term promotion of neurite outgrowth and synaptogenesis associated with learning and memory. The manifold effects of BDNF on neuronal modifications may be mediated by genomic alterations. We previously found that BDNF treatment acutely increases transcription of the synaptic vesicle protein Rab3A, required for trophin-induced synaptic plasticity, as well as the peptide VGF, which increases during learning. To elucidate comprehensive transcriptional programs associated with short- and long-term BDNF exposure, we now examine mRNA abundance and complexity using Affymetrix GeneChips in cultured hippocampal neurons. Consistent with the modulation of synaptic plasticity, BDNF treatment (3,6 h) induced mRNAs encoding the synapse-associated proteins synaptojanin 2, neuronal pentraxin 1, septin 9, and ryanodine receptor 2. BDNF also induced expression of mRNAs encoding neuropeptides (6,12 h), including prepronociceptin, neuropeptide Y, and secretogranin. To determine whether these neuropeptides induced by BDNF mediate neuronal development, we examined their effects on hippocampal neurons. The four mature peptides derived from post-translational processing of the ppNociceptin propeptide induced the expression of several immediate early genes in hippocampal cultures, indicating neuronal activation. To examine the significance of activation, the effects of nociceptin (orphanin FQ) and nocistatin on neurite outgrowth were examined. Quantitative morphometric analysis revealed that nociceptin significantly increased both average neurite length and average number of neurites per neuron, while nocistatin had no effect on these parameters. These results reveal a novel role for nociceptin and suggest that these neuropeptide systems may contribute to the regulation of neuronal function by BDNF. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Loss of steroidogenic factor 1 alters cellular topography in the mouse ventromedial nucleus of the hypothalamusDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2004Aline M. Davis Abstract Knockout (KO) mice lacking the orphan nuclear receptor steroidogenic factor 1 (SF-1) exhibit marked structural abnormalities of the ventromedial nucleus of the hypothalamus (VMH). In this study, we sought to determine the molecular mechanisms underlying the VMH abnormalities. To trace SF-1-expressing neurons, we used a SF-1/enhanced green fluorescent protein (eGFP) transgene. Although the total numbers of eGFP-positive cells in wild-type (WT) and SF-1 KO mice were indistinguishable, cells that normally localize precisely within the VMH were scattered more diffusely in adjacent regions in SF-1 KO mice. This abnormal distribution is likely due to the loss of SF-1 expression in VMH neurons rather than secondary effects of deficient steroidogenesis, as redistribution also was seen in mice with a CNS-specific KO of SF-1. Thus, the absence of SF-1 alters the distribution of cells that normally form the VMH within the mediobasal hypothalamus. Consistent with this model, the hypothalamic expression patterns of the transcription factors islet-1 and nkx2.1 also were displaced in SF-1 KO mice. Independent of gene expression, birthdate analyses further suggested that cells with earlier birthdates were affected more severely by the loss of SF-1 than were later born cells. We conclude that the absence of SF-1 causes major changes in cellular arrangement within and around the developing VMH that result from altered cell migration. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 424,436, 2004 [source] A dual systems model of adolescent risk-taking,DEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2010Laurence Steinberg Abstract It has been hypothesized that reward-seeking and impulsivity develop along different timetables and have different neural underpinnings, and that the difference in their timetables helps account for heightened risk-taking during adolescence. In order to test these propositions, age differences in reward-seeking and impulsivity were examined in a socioeconomically and ethnically diverse sample of 935 individuals between the ages of 10 and 30, using self-report and behavioral measures of each construct. Consistent with predictions, age differences in reward-seeking follow a curvilinear pattern, increasing between preadolescence and mid-adolescence, and declining thereafter. In contrast, age differences in impulsivity follow a linear pattern, with impulsivity declining steadily from age 10 on. Heightened vulnerability to risk-taking in middle adolescence may be due to the combination of relatively higher inclinations to seek rewards and still maturing capacities for self-control. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 216,224, 2010 [source] The influence of natural variations in maternal care on play fighting in the ratDEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2008Carine I. Parent Abstract Naturally occurring variations in maternal care in the rat influence the sensitivity of offspring to stress in adulthood. The offspring of mothers that show lower levels of pup licking/grooming (i.e., low-LG mothers) demonstrate enhanced responses to stress and increased anxiety compared to those of high-LG mothers. Low-LG offspring are also more sensitive to the influence of environmental enrichment than high-LG offspring. This study examined play fighting in the juvenile offspring of high-LG and low-LG dams in a multiple-play partners housing environment. Male offspring from low-LG dams demonstrated a significantly higher frequency of pouncing, pinning and aggressive social grooming than did high-LG males and high-LG and low-LG females. Consistent with earlier reports, male pups engaged in more play fighting than did females and maternal care was associated with differences in play fighting but only in males. Lower levels of stimulation in the form of LG from the dam during perinatal development may thus increase sensitivity for the stimulating effects of play behavior in periadolescence, in part explaining the increased solicitation of play fighting through increased pouncing in the male offspring of the low-LG mothers. These findings identify a possible influence of variations in maternal care on play fighting and suggest that maternal care in the perinatal period influence social interactions during periadolescence. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 767,776, 2008 [source] Cross-Modal transfer of the conditioned eyeblink response during interstimulus interval discrimination training in young ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 7 2008Kevin L. Brown Abstract Eyeblink classical conditioning (EBC) was observed across a broad developmental period with tasks utilizing two interstimulus intervals (ISIs). In ISI discrimination, two distinct conditioned stimuli (CSs; light and tone) are reinforced with a periocular shock unconditioned stimulus (US) at two different CS,US intervals. Temporal uncertainty is identical in design with the exception that the same CS is presented at both intervals. Developmental changes in conditioning have been reported in each task beyond ages when single-ISI learning is well developed. The present study sought to replicate and extend these previous findings by testing each task at four separate ages. Consistent with previous findings, younger rats (postnatal day,PD23 and 30) trained in ISI discrimination showed evidence of enhanced cross-modal influence of the short CS,US pairing upon long CS conditioning relative to older subjects. ISI discrimination training at PD43,47 yielded outcomes similar to those in adults (PD65,71). Cross-modal transfer effects in this task therefore appear to diminish between PD30 and PD43,47. Comparisons of ISI discrimination with temporal uncertainty indicated that cross-modal transfer in ISI discrimination at the youngest ages did not represent complete generalization across CSs. ISI discrimination undergoes a more protracted developmental emergence than single-cue EBC and may be a more sensitive indicator of developmental disorders involving cerebellar dysfunction. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 647-664, 2008. [source] Hyperphagia and obesity of OLETF rats lacking CCK1 receptors: Developmental aspectsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 5 2006Timothy H. Moran Abstract Otsuka Long Evans Tokushima Fatty (OLETF) rats have a deletion in the gene encoding the cholecystokinin,1 (CCK1) receptor. This deletion prevents protein expression, making the OLETF rat a CCK1 receptor knockout model. Consistent with the absence of CCK1 receptors, OLETF rats do not reduce their food intake in response to exogenously administered CCK and consume larger than normal meals. This deficit in within-meal feedback signaling is evident in liquid as well as solid meals. Neonatal OLETF rats show similar differences in independent ingestion tests. Intake is higher and is reflected in greater licking behavior. Neonatal OLETF rats also have diminished latencies to consume and higher initial ingestion rats. Adult OLETF rats are hyperphagic and obese. Although arcuate nucleus peptide gene expression is apparently normal in OLETF rats, when obesity is prevented through pair-feeding to amounts consumed by control Long Evans Tokushima Otsuka (LETO) rats, dorsomedial hypothalamic NPY mRNA expression is significantly elevated in OLETF rats. NPY overexpression is also evident in preobese, juvenile OLETF rats suggesting a causal role for this overexpression in the hyperphagia and obesity. Running wheel exercise normalizes food intake and body weight in OLETF rats. When access to exercise is provided at a time when OLETF rats are obese, the effects are limited to the period of exercise. When running wheel access is available to younger, preobese OLETF rats, exercise results in long lasting reductions in food intake and body weight and improved glucose regulation. These lasting metabolic effects of exercise may be secondary to an exercise induced reduction in DMH NPY mRNA expression. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 360,367, 2006. [source] Developmental profiles for multiple object tracking and spatial memory: typically developing preschoolers and people with Williams syndromeDEVELOPMENTAL SCIENCE, Issue 3 2010Kirsten O'Hearn The ability to track moving objects, a crucial skill for mature performance on everyday spatial tasks, has been hypothesized to require a specialized mechanism that may be available in infancy (i.e. indexes). Consistent with the idea of specialization, our previous work showed that object tracking was more impaired than a matched spatial memory task in individuals with Williams syndrome (WS), a genetic disorder characterized by severe visuo-spatial impairment. We now ask whether this unusual pattern of performance is a reflection of general immaturity or of true abnormality, possibly reflecting the atypical brain development in WS. To examine these two possibilities, we tested typically developing 3- and 4-year-olds and people with WS on multiple object tracking (MOT) and memory for static spatial location. The maximum number of objects that could be correctly tracked or remembered (estimated from the k -statistic) showed similar developmental profiles in typically developing 3- and 4-year-old children, but the WS profile differed from either age group. People with WS could track more objects than 3-year-olds, and the same number as 4-year-olds, but they could remember the locations of more static objects than both 3- and 4-year-olds. Combining these data with those from our previous studies, we found that typically developing children show increases in the number of objects they can track or remember between the ages of 3 and 6, and these increases grow in parallel across the two tasks. In contrast, object tracking in older children and adults with WS remains at the level of 4-year-olds, whereas the ability to remember multiple locations of static objects develops further. As a whole, the evidence suggests that MOT and memory for static location develop in tandem typically, but not in WS. Atypical development of the parietal lobe in people with WS could play a causal role in the abnormal, uneven pattern of performance in WS. This interpretation is consistent with the idea that multiple object tracking engages different mechanisms from those involved in memory for static object location, and that the former can be particularly disrupted by atypical development. [source] Children use categories to maximize accuracy in estimationDEVELOPMENTAL SCIENCE, Issue 6 2006Sean Duffy The present study tests a model of category effects upon stimulus estimation in children. Prior work with adults suggests that people inductively generalize distributional information about a category of stimuli and use this information to adjust their estimates of individual stimuli in a way that maximizes average accuracy in estimation (see Huttenlocher, Hedges & Vevea, 2000). However, little is known about the developmental origin of this cognitive process. In the present study, 5- and 7-year-old children viewed stimuli that varied in size and reproduced each from memory. Consistent with the predictions of a Bayesian model of category effects on estimation, responses were adjusted toward the central value of the stimulus distribution. Additionally, the dispersion of the stimulus distribution affected the pattern of bias and variability of responses in a way that is predicted by the model. The results suggest that, like adults, children use categories for increasing average accuracy in estimating inexact stimuli. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||