bluuebunny/crossref_metadata_2025 huggingface dataset:
Cannabinoids modulate spontaneous neuronal activity and evoked inhibition of locus coeruleus noradrenergic neurons
Authors: Muntoni Anna Lisa , Pillolla Giuliano , Melis Miriam , Perra Simona , Gessa Gian Luigi , Pistis Marco
Published: May 2006

The noradrenergic pathway arising from the locus coeruleus (LC) is involved in the regulation of attention, arousal, cognitive processes and sleep. These physiological activities are affected byCannabisexposure − both in humans and laboratory animals. In addition, exogenous cannabinoids, as well as pharmacological and genetic manipulation of the endocannabinoid system, are known to influence emotional states (e.g. anxiety) for which a contributory role of the LC‐noradrenergic system has long been postulated. However, whether cannabinoid administration would affect the LC neuronal activityin vivois still unknown. To this end, single‐unit extracellular recordings were performed from LC noradrenergic cells in anaesthetized rats. Intravenous injection of both the synthetic cannabinoid agonist, WIN55212‐2, and the main psychoactive principle ofCannabis, Δ9‐tetrahydrocannabinol, dose‐dependently increased the firing rate of LC noradrenergic neurons, with WIN55212‐2 being the most efficacious. Similar results were obtained by the administration of these drugs into a lateral ventricle. Cannabinoid‐induced stimulation of LC noradrenergic neuronal activity was counteracted by SR141716A, a cannabinoid receptor antagonist/reverse agonist, which by itself slightly reduced LC discharge rate. Moreover, WIN55212‐2 suppressed the inhibition of noradrenergic cells produced by stimulation of the major γ‐aminobutyric acid (GABA)ergic afferent to the LC, the nucleus prepositus hypoglossi. Altogether, these findings suggest the involvement of noradrenergic pathways in some consequences ofCannabisintake (e.g. cognitive and attention deficits, anxiety reactions), as well as a role for cannabinoid receptors in basic brain activities sustaining arousal and emotional states.
T‐type Cav3.3 calcium channels produce spontaneous low‐threshold action potentials and intracellular calcium oscillations
Authors: Chevalier Marc , Lory Philippe , Mironneau Chantal , Macrez Nathalie , Quignard Jean‐François
Published: May 2006

The precise contribution of T‐type Ca2+ channels in generating action potentials (APs), burst firing and intracellular Ca2+ signals needs further elucidation. Here, we show that Cav3.3 channels can trigger repetitive APs, generating spontaneous membrane potential oscillations (MPOs), and a concomitant increase in the intracellular Ca2+ concentration ([Ca2+]i) when overexpressed in NG108‐15 cells. MPOs were dependent on Cav3.3 channel activity given that they were recorded from a potential range of −55 to −70 mV, blocked by nickel and mibefradil, as well as by low external Ca2+ concentration. APs of distinct duration were recorded: short APs (sAP) or prolonged APs (pAP) with a plateau potential near −40 mV. The voltage‐dependent properties of the Cav3.3 channels constrained the AP duration and the plateau potential was supported by sustained calcium current through Cav3.3 channels. The sustained current amplitude decreased when the resting holding potential was depolarized, thereby inducing a switch of AP shape from pAP to sAP. Duration of the [Ca2+]i oscillations was also closely related to the shape of APs. The Cav3.3 window current was the oscillation trigger as shown by shifting the Cav3.3 window current potential range as a result of increasing the external Ca2+ concentration, which resulted in a corresponding shift of the AP threshold. Overall, the data demonstrate that the Cav3.3 window current is critical in triggering intrinsic electrical and [Ca2+]i oscillations. The functional expression of Cav3.3 channels can generate spontaneous low‐threshold calcium APs through its window current, indicating that Cav3.3 channels can play a primary role in pacemaker activity.
Maturation of otolith‐related brainstem neurons in the detection of vertical linear acceleration in rats
Authors: Lai Suk‐King , Lai Chun‐Hong , Yung Ken K. L. , Shum Daisy K. Y. , Chan Ying‐Shing
Published: May 2006

To investigate the critical maturation time of otolith‐related neurons in processing vertical orientations, rats (postnatal day 4 to adults) were studied for functional activation of c‐fos expression in brainstem neurons by immuno‐/hybridization histochemistry. Conscious rats were subjected to sinusoidal linear acceleration along the vertical plane. Labyrinthectomized and/or stationary controls showed only sporadically scattered Fos‐labeled neurons in the vestibular nuclei, confirming an otolithic origin of c‐fos expression. Functionally activated Fos expression in neurons of the medial and spinal vestibular nuclei and group x were identifiable by P7 and those in group y by P9. A small number of Fos‐labeled neurons characterized by small soma size were found in the ventral part of lateral vestibular nucleus by P9. Other vestibular‐related areas such as prepostitus hypoglossal nucleus, gigantocellular reticular nucleus and locus coeruleus of normal experimental rats showed functionally activated c‐fos expression at P7. Neurons in dorsal medial cell column and beta subnucleus of the inferior olive only showed functionally activated c‐fos expression by the second postnatal week. These findings revealed a unique critical maturation time for each of the vestibular‐related brainstem areas in the recognition of gravity‐related vertical head orientations. By mapping the three‐dimensional distribution of Fos‐immunoreactive neurons, we found an even distribution of otolith‐related neurons within the spinal vestibular nucleus in groups x and y but a clustered distribution in the middle–lateral–ventral part of the medial vestibular nucleus. Taken together, our findings reveal the developmental profile of neuronal subpopulations within the vertical otolith system, thereby providing an anatomical basis for postnatal coding of gravity‐related vertical head movements.
Requirement for Id1 in opioid‐induced oligodendrogenesis in cultured adult rat hippocampal progenitors
Authors: Persson Anders I. , Bull Cecilia , Eriksson Peter S.
Published: May 2006

Growth factors and peptides playing important roles during early development of the central nervous system have also been shown to maintain their regulation of cell genesis in the adult brain. We have previously described that endogenous opioids, expressed in the developing hippocampus, regulate proliferation and differentiation in the adult rat hippocampus. The aim of this study was to investigate the effects of the opioid β‐endorphin on gene expression and glial differentiation in cultures of adult rat hippocampal progenitors (AHPs). Changes in gene expression after stimulation of AHPs with β‐endorphin for 48 h were investigated using cDNA arrays. Confirmation experiments verified that stimulation with β‐endorphin increased the mRNA levels of myelin basic protein, glutathione S‐transferase pi, c‐junD and rab16 (P < 0.05), genes that are associated with oligodendrogenesis. Furthermore, β‐endorphin increased the levels of Id1, but not Id3, mRNA on the arrays. Incubation of AHPs with β‐endorphin resulted in a threefold increase in oligodendrogenesis (P < 0.01) but no significant change in astrogliogenesis. No effect on oligodendrogenesis was observed in the presence of the opioid antagonist naloxone. Coincubation of β‐endorphin with Id1 antisense oligonucleotides for 10 days also entirely blocked the induced oligodendrogenesis in our AHP cultures. Moreover, a subpopulation of AHPs (25%) showed nuclear expression of the proneural transcriptional activator Mash1 that was reduced to approximately 5% of the cells when exposed to β‐endorphin. We suggest a requirement for Id1 in opioid‐induced oligodendrogenesis in cultured AHPs possibly acting on opioid‐responsive AHPs expressing the proneural transcriptional activator Mash1.
Rapid phosphorylation of histone H2A.X following ionotropic glutamate receptor activation
Authors: Crowe Samantha L. , Movsesyan Vilen A. , Jorgensen Timothy J. , Kondratyev Alexei
Published: May 2006

Excessive activation of ionotropic glutamate receptors increases oxidative stress, contributing to the neuronal death observed following neurological insults such as ischemia and seizures. Post‐translational histone modifications may be key mediators in the detection and repair of damage resulting from oxidative stress, including DNA damage, and may thus affect neuronal survival in the aftermath of insults characterized by excessive glutamate release. In non‐neuronal cells, phosphorylation of histone variant H2A.X (termed γ‐H2AX) occurs rapidly following DNA double‐strand breaks. We investigated γ‐H2AX formation in rat cortical neurons (daysin vitro14) following activation ofN‐methyl‐d‐aspartate (NMDA) or α‐amino‐3‐hydroxyl‐5‐methyl‐4‐isoxazolepropionic acid (AMPA)/kainate glutamate receptors using fluorescent immunohistochemical techniques. Moreover, we evaluated the co‐localization of γ‐H2AX ‘foci’ with Mre11, a double‐strand break repair protein, to provide further evidence for the activation of this DNA damage response pathway. Here we show that minimally cytotoxic stimulation of ionotropic glutamate receptors was sufficient to evoke γ‐H2AX in neurons, and that NMDA‐induced γ‐H2AX foci formation was attenuated by pretreatment with the antioxidant, Vitamin E, and the intracellular calcium chelator, BAPTA‐AM. Moreover, a subset of γ‐H2AX foci co‐localized with Mre11, indicating that at least a portion of γ‐H2AX foci is damage dependent. The extent of γ‐H2AX induction following glutamate receptor activation corresponded to the increases we observed following conventional DNA damaging agents [i.e. non‐lethal doses of gamma‐radiation (1 Gy) and hydrogen peroxide (10 µm)]. These data suggest that insults not necessarily resulting in neuronal death induce the DNA damage‐evoked chromatin modification, γ‐H2AX, and implicate a role for histone alterations in determining neuronal vulnerability following neurological insults.
EEG evidence for the presence of an action observation–execution matching system in children
Authors: Lepage Jean‐François , Théoret Hugo
Published: May 2006

In the adult human brain, passive observation of actions performed by others activates some of the same cortical areas that are involved in the execution of actions, thereby contributing to action recognition. This mechanism appears to occur through activation of a population of action‐coding cells known as mirror neurons (MN). In the adult motor cortex, performing actions and observing human movement reduces the magnitude of the mu (8–13 Hz) rhythm, possibly reflecting MN system activity. Despite the wealth of information available regarding the adult MN system, little is known about its existence in children. Here, we used EEG to probe mu rhythm modulation in 15 children during observation and execution of hand actions. Our data show that mu rhythm attenuation occurs in children under 11 years old during observation of hand movements. Similarly to what has been reported in adults, observation of goal/object‐orientated movement produces greater modulation of the mu rhythm than intransitive movement. These data confirm the existence of an observation–execution matching system in the immature human brain and may be of clinical value in the understanding of neurodevelopmental disorders associated with a faulty MN system, such as autism spectrum disorder.
In vivo synaptic plasticity in the dentate gyrus of mice deficient in the neural cell adhesion molecule NCAM or its polysialic acid
Authors: Stoenica Luminita , Senkov Oleg , Gerardy‐Schahn Rita , Weinhold Birgit , Schachner Melitta , Dityatev Alexander
Published: May 2006

The neural cell adhesion molecule NCAM and its associated polysialic acid (PSA) play important roles in synaptic plasticity in the CA1 and/or CA3 regions of the hippocampus in vitro. Here, we address the question of whether NCAM and PSA are involved in regulation of synaptic transmission and plasticity also in vivo at synapses formed by entorhinal cortex axons in the dentate gyrus of mice anaesthetized with urethane. We show that basal synaptic transmission, measured as the slope of field excitatory postsynaptic potentials, was reduced strongly in mice lacking ST8SiaII/STX, the enzyme involved in polysialylation of NCAM in stem cell‐derived immature granule cells, but not in mice deficient either in the NCAM glycoprotein or the enzyme ST8SiaIV/PST involved in polysialylation of NCAM in mature neurons. Strikingly, only mice deficient in NCAM, but not in PST or STX, were impaired in long‐term potentiation (LTP) induced by theta‐burst stimulation, suggesting that LTP in the dentate gyrus depends on the NCAM glycoprotein alone rather than on its associated PSA. As also patterns of synaptic activity during and immediately after induction of LTP were impaired in NCAM‐deficient mice, it is likely that induction of LTP requires NCAM. These data are the first to describe that NCAM is necessary for induction of synaptic plasticity in identified synapses in vivo and suggest that polysialylation of NCAM expressed by immature granule cells in the dentate gyrus supports development of basal excitatory synaptic transmission in this region.
Both α2 and α3 GABAA receptor subtypes mediate the anxiolytic properties of benzodiazepine site ligands in the conditioned emotional response paradigm
Authors: Morris H. V. , Dawson G. R. , Reynolds D. S. , Atack J. R. , Stephens D. N.
Published: May 2006

Mice with point‐mutated α2 GABAA receptor subunits (rendering them diazepam insensitive) are resistant to the anxiolytic‐like effects of benzodiazepines (BZs) in unconditioned models of anxiety. We investigated the role of the α2 GABAA subtype in a model of conditioned anxiety. α2(H101R) and wildtype mice were trained in a conditioned emotional response (CER) task, in which lever‐pressing for food on a variable interval (VI) schedule was suppressed during the presentation of a conditioned stimulus (CS+) that predicted footshock. The ability of diazepam, ethanol and pentobarbital to reduce suppression during the CS+ was interpreted as an anxiolytic response. Diazepam (0, 0.5, 1, 2, 4 and 8 mg/kg) induced a dose‐dependent anxiolytic‐like effect in wildtype mice. At high doses, diazepam (2, 4 and 8 mg/kg) was sedative in α2(H101R) mice. Analysis of the anxiolytic properties of nonsedative diazepam doses (0.5 and 1 mg/kg), showed that α2(H101R) mice were resistant to the anxiolytic effects of diazepam. Equivalent anxiolytic properties of pentobarbital (20 mg/kg) and ethanol (1 and 2 g/kg) were seen in both genotypes. These findings confirm the critical importance of the α2 GABAA subtype in mediating BZ anxiolysis. However, as a compound, L‐838417, with agonist properties at α2, α3 and α5‐containing receptors, gave rise to anxiolytic‐like activity in α2(H101R) mice in the CER test, α3‐containing GABA receptors are also likely to contribute to anxiolysis. Observations that α2(H101R) mice were more active, and displayed a greater suppression of lever pressing in response to fear‐conditioned stimuli than wildtype mice, suggests that the α2(H101R) mutation may not be behaviourally silent.
Semaphorin3A regulates synaptic function of differentiated hippocampal neurons
Authors: Bouzioukh Farima , Daoudal Gaël , Falk Julien , Debanne Dominique , Rougon Geneviève , Castellani Valérie
Published: May 2006

Semaphorins are major chemorepellents for developing neuronal projections. Their persistent expression at adult stages suggests that they may contribute to the functioning of neuronal circuits. We investigated the functional properties of semaphorin3A (Sema3A) in adult hippocampal neurons, and report that exogenous application of this cue decreases the efficacy of synaptic transmission evoked in the CA1 region of hippocampal slices. In situ hybridization, imaging and biochemical techniques showed that the Sema3A receptor component neuropilin‐1 is present at hippocampal synapses and localizes in the presynaptic membrane. In differentiated cultured hippocampal neurons, Sema3A elicited Erk1/2 phosphorylation in somata and neuritic compartments. Furthermore, Sema3A application resulted in a striking reduction of synaptophysin and postsynaptic density 95 puncta without affecting the axon diameter. These observations reveal novel functional potentialities for secreted semaphorins, which suggest that these cues could modulate the morphology and function of synapses in the adult brain.
Neuroprotective properties of memantine in different in vitro and in vivo models of excitotoxicity
Authors: Volbracht Christiane , Van Beek Johan , Zhu Changlian , Blomgren Klas , Leist Marcel
Published: May 2006

The pathogenesis of stroke, trauma and chronic degenerative diseases, such as Alzheimer's disease (AD), has been linked to excitotoxic processes due to inappropriate stimulation of the N‐methyl‐d‐asparate receptor (NMDA‐R). Attempts to use potent competitive NMDA‐R antagonists as neuroprotectants have shown serious side‐effects in patients. As an alternative approach, we were interested in the anti‐excitotoxic properties of memantine, a well‐tolerated low affinity uncompetitive NMDA‐R antagonist presently used as an anti‐dementia agent. We explored in a series of models of increasing complexity, whether this voltage‐dependent channel blocker had neuroprotective properties at clinically relevant concentrations. As expected, memantine protected neurons in organotypic hippocampal slices or dissociated cultures from direct NMDA‐induced excitotoxicity. However, low concentrations of memantine were also effective in neuronal (cortical neurons and cerebellar granule cells) stress models dependent on endogenous glutamate stimulation and mitochondrial stress, i.e. exposure to hypoxia, the mitochondrial toxin 1‐methyl‐4‐phenylpyridinium (MPP+) or a nitric oxide (NO) donor. Furthermore, memantine reduced lethality and brain damage in vivo in a model of neonatal hypoxia‐ischemia (HI). Finally, we investigated functional rescue (neuronal capacity to migrate along radial glia) by memantine in cerebellar microexplant cultures exposed to the indirect excitotoxin 3‐nitropropionic acid (3‐NP). Potent NMDA‐R antagonists, such as (+)MK‐801, are known to block neuronal migration in microexplant cultures. Interestingly, memantine significantly restored the number of neurons able to migrate out of the stressed microexplants. These findings suggest that inhibition of the NMDA‐R by memantine is sufficient to block excitotoxicity, while still allowing some degree of signalling.
MDMA and fenfluramine reduce L‐DOPA‐induced dyskinesia via indirect 5‐HT1A receptor stimulation
Authors: Bishop Christopher , Taylor Jennifer L. , Kuhn Donald M. , Eskow Karen L. , Park John Y. , Walker Paul D.
Published: May 2006

Chronicl‐3,4‐dihydroxyphenylalanine (L‐DOPA) pharmacotherapy in Parkinson's disease is often accompanied by the development of abnormal and excessive movements known as dyskinesia. Clinical and experimental studies indicate that indirect serotonin agonists can suppress dyskinesia without affecting the efficacy of L‐DOPA. While the mechanism by which these effects occur is not clear, recent research suggests that serotonin 5‐HT1A receptors may play a pivotal role. To test this, male Sprague–Dawley rats with unilateral 6‐hydroxydopamine medial forebrain bundle lesions received 1 week of daily treatment with L‐DOPA (12 mg/kg, i.p.) plus benserazide (15 mg/kg, i.p.). Beginning on the 8th day of treatment and every 3rd or 4th day thereafter, rats were pretreated with vehicle (0.9% NaCl), the serotonin and dopamine releaser 3,4‐methylenedioxymethamphetamine (MDMA; 0.25 or 2.5 mg/kg, i.p.) or the serotonin releaser fenfluramine (FEN; 0.25 or 2.5 mg/kg, i.p.) 5 min prior to L‐DOPA, after which abnormal involuntary movements (AIMs) and rotations were quantified every 20th minute for 2 h. Pretreatment with 2.5 mg/kg of either MDMA or FEN reduced AIMs. To determine the contribution of the 5‐HT1A receptor to these effects, another group of L‐DOPA‐primed 6‐hydroxydopamine‐lesioned rats were pretreated with the 5‐HT1A antagonist WAY100635 (0.5 mg/kg, i.p.), MDMA + WAY100635 (2.5 + 0.5 mg/kg, i.p.) or FEN + WAY100635 (2.5 + 0.5 mg/kg, i.p.) 5 min prior to L‐DOPA and subsequent AIMs and rotation tests. The antidyskinetic effects of MDMA and FEN were reversed by cotreatment with WAY100635. These results suggest that 5‐HT‐augmenting compounds such as MDMA and FEN probably convey antidyskinetic properties in part via stimulation of 5‐HT1A receptors.
Membrane traffic in outer hair cells of the adult mammalian cochlea
Authors: Kaneko Toshihiko , Harasztosi Csaba , Mack Andreas F. , Gummer Anthony W.
Published: May 2006

Outer hair cells (OHCs), the sensory‐motor cells responsible for the extraordinary frequency selectivity and dynamic range of the cochlea, rapidly endocytose membrane and protein at their apical surface. Endocytosis and transcytosis in isolated OHCs from the mature guinea‐pig cochlea were investigated using the amphiphatic membrane probe FM1‐43. We observed membrane transport from the apical surface to both the basolateral wall and the subnuclear pole. By double‐labelling with DiOC6, a stain for endoplasmic reticulum, and aspiration of the plasma membrane, we showed that the basolateral target was the subsurface cisternae. The fluorescent signal was about three times weaker at the basal than at the apical pole. The speed of vesicle transport to the subnuclear pole was approximately 0.4 µm/s. Changing extracellular Ca2+ concentration from 25 µm to 2 mm accelerated rapid endocytosis. Extracellular application of BAPTA‐AM (25 µm), an intracellular Ca2+ chelator, and TFP (20 µm), a specific inhibitor of calmodulin, reduced endocytic activity, as did depolarization of the whole cell. The presence of extracellular Cd2+ (200 µm), a Ca2+‐channel blocker, had no effect on the voltage dependence of endocytosis at the apical pole, and inhibited the voltage dependence at the subnuclear pole. These results suggest that rapid endocytosis is a Ca2+/calmodulin‐dependent process, with extracellular Ca2+ entering through voltage‐gated Ca2+ channels at the basal pole. The two distinct destinations of endocytosed membrane are consistent with the functional polarization of the OHC, with the basolateral wall being dedicated to electromechanical transduction and the subnuclear pole being dedicated to electrochemical transduction processes.
Nucleus incertus contribution to hippocampal theta rhythm generation
Authors: Nuñez A. , Cervera‐Ferri A. , Olucha‐Bordonau F. , Ruiz‐Torner A. , Teruel V.
Published: May 2006

The hippocampal theta rhythm is generated by the pacemaker activity of the medial septum‐diagonal band of Broca (MS/DBB) neurons. These nuclei are influenced by brainstem structures that modulate the theta rhythm. The aim of the present work is to determine whether the nucleus incertus (NI), which has important anatomical connections with the MS/DBB, contributes to the hippocampal theta rhythm generation in rats. Hippocampal field activity was recorded in urethane‐anaesthetized rats. Electrical stimulation of the NI not only evoked theta rhythm in the hippocampus, but also decreased the amplitude of delta waves. Unit recordings in the NI revealed either a non‐rhythm discharge pattern in most neurons (76%), or a rhythm activity at 13–25 Hz in the remaining neurons. The firing rate of these neurons increased during the presence of theta rhythm evoked by either sensory or reticularis pontis oralis nucleus (RPO) stimulation. Electrolytic lesions of NI, or the microinjection of the γ‐aminobutyric acid (GABA)A agonist muscimol, abolished the theta rhythm evoked by RPO stimulation. Consequently, the NI may be a relay station between brainstem structures and the MS/DBB in the control of the hippocampal theta rhythm generation.
Identification of disabled‐1 as a candidate gene for critical period neuroplasticity in cat and mouse visual cortex
Authors: Yang Cui Bo , Zheng Yu Ting , Kiser Paul J. , Mower George D.
Published: May 2006

Rearing in darkness slows the time course of the critical period in visual cortex, such that at 5 weeks of age normal cats are more plastic than dark‐reared cats, whereas at 20 weeks dark‐reared cats are more plastic [G. D. Mower (1991)Dev. Brain Res., 58, 151–158]. Thus, a stringent criterion is that genes that are important for plasticity in visual cortex will show differences in expression between normal and dark‐reared visual cortex that are of opposite direction in young vs. older animals. The present study reports the identification by differential display PCR of Dab‐1, the mammalian homolog of the drosophila disabled‐1 gene, as a candidate gene for critical period neuronal plasticity, expression of which is regulated according to this criterion in cat visual cortex. Evidence for this bidirectional direction regulation is extended to Dab‐1 protein in cat and mouse visual cortex and shown to be specific to visual cortex, not occurring in frontal cortex. The Reelin/Dab‐1 pathway has well‐documented functions in cell migration during prenatal life and increasing evidence indicates that in postnatal brain the pathway plays a role in synaptic plasticity. The present results extend this evidence by directly implicating Dab‐1 in postnatal critical period plasticity of visual cortex.
Taxa–area relationships for microbes: the unsampled and the unseen
Authors: Woodcock Stephen , Curtis Thomas P. , Head Ian M. , Lunn Mary , Sloan William T.
Published: May 2006

The recent observation of a power–law relationship, S ∝ Az, between number of taxa, S, and area, A, for microbial eukaryotes and bacteria suggests that this is one of the few generic relationships in ecology, applicable to plants, animals and microbes. However, the rate of increase in the number of species with area varies from approximately the fourth (z = 0.26) to as little as the 50th root (z = 0.0019) in microbes. This is an enormous range for which no quantitative explanation has been proffered. We show by sampling from synthetic populations that the disparity between sample and community sizes in microbial community surveys means z can be considerably underestimated and accrual of rare taxa with increasing area will not be detectable. Significant microbial taxa–area relationships will only be observed when changes in community structure within samples correlate with area. Thus, the very low z values observed recently cannot be used as the sole evidence in support of any particular community theory of community assembly. More generally, this suggests that our search for patterns and laws in the microbial world will be profoundly influenced and, potentially distorted by the sample sizes that are typical of microbial community surveys.
Phylogeny, physiology and distribution of ‘Candidatus Microthrix calida’, a new Microthrix species isolated from industrial activated sludge wastewater treatment plants
Authors: Levantesi Caterina , Rossetti Simona , Thelen Karin , Kragelund Caroline , Krooneman Janneke , Eikelboom Dick , Nielsen Per Halkjær , Tandoi Valter
Published: May 2006

Twelve strains of filamentous bacteria morphologically identified as ‘Microthrix parvicella’ were isolated from industrial activated sludge wastewater treatment plants. 16S rRNA gene sequences analysis showed that these strains were all closely related to ‘Candidatus Microthrix parvicella’. Six of them, however, had a 16S rRNA gene similarity of only 95.7% and 96.7% to ‘Candidatus Microthrix parvicella’ suggesting the presence of a new species. The name ‘Candidatus Microthrix calida’ is proposed for this new microorganism. The physiological properties of these six isolates supported the description of a new taxon. The ‘Candidatus Microthrix calida’ strains produced thin filaments (0.3–0.7 µm diameter), they did not grow on the media supporting the growth of ‘Candidatus Microthrix parvicella’ and could be cultivated at higher temperature (up to 36.5°C). Preliminary data on substrate uptake were obtained by microautoradiography on pure culture. Two new fluorescence in situ hybridization (FISH) probes, Mpa‐T1‐1260 specific for ‘Candidatus Microthrix calida’ and Mpa‐all‐1410 targeting both Microthrix species, were designed. The presence of Microthrix spp. was investigated in 114 activated sludge plants. ‘Microthrix parvicella’ morphotype was detected in 23% of the analysed samples and FISH analysis revealed that ‘Candidatus Microthrix calida’ was present in 5% of them. The remaining ‘M. parvicella’ filaments were positive with probe Mpa‐all‐1410 but could not all be identified as ‘Candidatus Microthrix parvicella’ suggesting the presence of more hitherto undescribed biodiversity within this morphotype.
Phylogenetic relationships of freshwater bryozoans (Ectoprocta, Phylactolaemata) inferred from mitochondrial ribosomal DNA sequences
Authors: Okuyama Makiko , Wada Hiroshi , Ishii Teruhisa
Published: May 2006

Most species of freshwater bryozoans (Ectoprocta: Phylactolaemata) have few morphological distinctions, and within phylactolaemates, the morphology of the statoblast has been used to determine evolutionary relationships. Here, two controversial phylogenies have been proposed for phylactolaemates with regard to the relationship of Lophopodidae to other families. Two plumatellid genera, Gelatinella and Hyalinella, are candidates for the ancestral type of lophopodids. In addition, the coexistence of spines on the surfaces of the statoblast has led to the suggestion that lophopodids are closely related to the family Cristatellidae. In this study, we analysed mitochondrial DNA sequences of the 12S and 16S rDNA genes of 10 phylactolaemate species. Our results suggest that plumatellids may not be a direct ancestral group of lophopodids and that cristatellids are not a sister group of lophopodids. Fredericella, which was previously thought to be an ancestral group, was revealed to be derived. In addition, our results suggest that Stephanella is the most basal phylactolaemate. Mapping morphological characteristics onto the sequence‐based phylogenetic tree revealed convergent evolution of statoblast characters.
Interrelationships of the Gastrotricha and their place among the Metazoa inferred from 18S rRNA genes
Authors: Todaro M. Antonio , Telford Maximilian J. , Lockyer Anne E. , Littlewood D. Timothy J.
Published: May 2006

The phylum Gastrotricha includes about 700 species. They are small worm‐like organisms abundant among marine and freshwater meiobenthos. In spite of their ubiquity, diversity and relative abundance, phylogenetic relationships of these animals remain enigmatic due to the conflicting results of morphological and molecular cladistic analyses. Also unclear are the alliances within the phylum. In order to best estimate the position of Gastrotricha among the Metazoa and to shed some light on the ingroup phylogenetic relationships, small subunit (SSU) ribosomal DNA (rDNA) from 15 species of Chaetonotida (eight genera) and 28 species of Macrodasyida (26 genera) were included in an alignment of 50 metazoan taxa representing 26 phyla. Of the gastrotrich SSU rDNA sequences, eight are new and, along with published sequences represent eight families, including the five marine most speciose. Gastrotricha were resolved within a monophyletic Lophotrochozoa as part of a clade including Micrognathozoa, Rotifera and Cycliophora. The Gnathostomulida were sister to this clade. Nodal support was low for all of these relationships except the grouping of the Micrognathozoa, Rotifera and Cycliophora. Bayesian inference resolved the Gastrotricha as monophyletic with weak nodal support; the Macrodasyida were resolved as paraphyletic with many basal nodes poorly supported. Within the Chaetonotida, the monotypic Multitubulatina Neodasys was found in alliance with the macrodasyidan Urodasys while all the Paucitubulatina were found to form a single, well‐supported clade, with Musellifer as the most basal member. Among the more densely sampled Macrodasyida the Lepidodasyidae and Macrodasyidae were each found to be polyphyletic while monophyly was well supported for the Turbanellidae and Thaumastodermatidae. The congruence of our results with those of the cladistic analysis based on morphological traits provides confidence about the value of each dataset, and calls for widening of the research to include additional taxa of particular phylogenetic significance such as the Dactylopodolidae, Diuronotus, Heteroxenotrichula and Draculiciteria. The study highlights the problems in working with small species, the need for voucher specimens and the confused taxonomic status and membership of various gastrotrich families.
The Effects of Income Imputation on Microanalyses: Evidence from the European Community Household Panel
Authors: Nicoletti Cheti , Peracchi Franco
Published: May 2006

Social surveys are usually affected by item and unit non-response. Since it is unlikely that a sample of respondents is a random sample, social scientists should take the missing data problem into account in their empirical analyses. Typically, survey methodologists try to simplify the work of data users by ‘completing’ the data, filling the missing variables through imputation. The aim of the paper is to give data users some guidelines on how to assess the effects of imputation on their microlevel analyses. We focus attention on the potential bias that is caused by imputation in the analysis of income variables, using the European Community Household Panel as an illustration.
Sibling Death Clustering in India: State DependenceVersusUnobserved Heterogeneity
Authors: Arulampalam Wiji , Bhalotra Sonia
Published: May 2006

Data from a range of environments indicate that the incidence of death is not randomly distributed across families but, rather, that there is a clustering of death among siblings. A natural explanation of this would be that there are (observed or unobserved) differences across families, e.g. in genetic frailty, education or living standards. Another hypothesis that is of considerable interest for both theory and policy is that there is a causal process whereby the death of a child influences the risk of death of the succeeding child in the family. Drawing language from the literature on the economics of unemployment, the causal effect is referred to here as state dependence (or scarring). The paper investigates the extent of state dependence in India, distinguishing this from family level risk factors that are common to siblings. It offers some methodological innovations on previous research. Estimates are obtained for each of three Indian states, which exhibit dramatic differences in socio-economic and demographic variables. The results suggest a significant degree of state dependence in each of the three regions. Eliminating scarring, it is estimated, would reduce the incidence of infant mortality (among children who are born after the first child) by 9.8% in the state of Uttar Pradesh, 6.0% in West Bengal and 5.9% in Kerala.
Multilevel Modelling of Complex Survey Data
Authors: Rabe-Hesketh Sophia , Skrondal Anders
Published: May 2006

Multilevel modelling is sometimes used for data from complex surveys involving multistage sampling, unequal sampling probabilities and stratification. We consider generalized linear mixed models and particularly the case of dichotomous responses. A pseudolikelihood approach for accommodating inverse probability weights in multilevel models with an arbitrary number of levels is implemented by using adaptive quadrature. A sandwich estimator is used to obtain standard errors that account for stratification and clustering. When level 1 weights are used that vary between elementary units in clusters, the scaling of the weights becomes important. We point out that not only variance components but also regression coefficients can be severely biased when the response is dichotomous. The pseudolikelihood methodology is applied to complex survey data on reading proficiency from the American sample of the ‘Program for international student assessment’ 2000 study, using the Stata program gllamm which can estimate a wide range of multilevel and latent variable models. Performance of pseudo-maximum-likelihood with different methods for handling level 1 weights is investigated in a Monte Carlo experiment. Pseudo-maximum-likelihood estimators of (conditional) regression coefficients perform well for large cluster sizes but are biased for small cluster sizes. In contrast, estimators of marginal effects perform well in both situations. We conclude that caution must be exercised in pseudo-maximum-likelihood estimation for small cluster sizes when level 1 weights are used.
Proximity and inter‐organizational collaboration: A literature review
Authors: Knoben J. , Oerlemans L.A.G.
Published: May 2006

The proximity concept is used in many different ways in the literature. These dimensions of proximity are, however, defined and measured in many different (sometimes even contradictory) ways, show large amounts of overlap, and often are under‐ or over‐specified. The goal of this paper is to specify the different dimensions of proximity relevant in inter‐organizational collaboration more precisely and to provide definitions of these dimensions. The research presented contributes to reducing the ambiguity of the proximity concept as used in the literature.

Based on the above, the following research question is addressed in this paper: ‘Which dimensions of proximity are relevant in inter‐organizational collaboration and how are they defined?’ A systematic literature review is presented in order to disentangle the dimensions of the proximity concept. Based on this literature review, three dimensions of proximity relevant in inter‐organizational collaboration are distinguished: geographical proximity, organizational proximity and technological proximity. Examples (case studies) from the literature are used to illustrate the current conceptual ambiguity as well as to clarify how the proposed dimensions of proximity reduce this conceptual ambiguity.
The effect of congenital deafness on duration judgment
Authors: Kowalska Joanna , Szelag Elzbieta
Published: May 2006

Objective:  Congenital deafness provides the opportunity to study how atypical sensory and language experiences affect different aspects of information processing, e.g., time perception.

Methods:  Using two methods of temporal estimation, reproduction (Exp. 1) and production (Exp. 2), the effect of deafness on duration judgment was investigated within a time domain of a few seconds. We examined 16 congenitally deaf adolescents, aged between 16 and 19 years, and 16 normally hearing subjects, matched for gender and age. In Exp. 1 subjects were asked to reproduce durations from 1 to 5.5 s, whereas in Exp. 2 they produced durations from 1 to 6 s.

Results:  The results showed that in both experiments, the region of accurate estimation was significantly limited in deaf individuals, compared to normal hearing ones. Deaf adolescents judged accurately only intervals around 3 s, whereas they overestimated standards shorter than 2 s and underestimated those above 3 s. In contrast, controls correctly estimated the majority of standards applied in both experiments, with the exception of underreproduction of intervals longer than 3 s (Exp. 1).

Conclusions:  The effect of deafness on the accuracy of duration judgment can be linked to differences in the use of conventional time units, applied strategy as well as cognitive processes such as attention or working memory.
The Female Sexual Subjectivity Inventory: Development and Validation of a Multidimensional Inventory for Late Adolescents and Emerging Adults
Authors: Horne Sharon , Zimmer-Gembeck Melanie J.
Published: May 2006

Three studies were conducted to develop and validate a theoretically derived multidimensional inventory of females' sexual self-conceptions ( sexual subjectivity). Study 1 revealed five factors on the Female Sexual Subjectivity Inventory (FSSI): sexual body-esteem, three factors of conceptions and expectations of sexual desire and pleasure (self, partner, and self-efficacy), and sexual self-reflection. A shorter revised version of the FSSI was tested in Study 2. In Study 3, a confirmatory factor analysis indicated a good fit to the data. The FSSI had a sound factorial structure and high reliability. Significant associations between the five scales in the FSSI and sexual self-awareness, safe sex self-efficacy, and sexual anxiety provided evidence of validity Some FSSI scales were also associated with self-silencing in close relationships, resistance to sexual double standards, and self-esteem. Sexual subjectivity is a complex intraindividual phenomenon that includes cognitive and emotional components, some of which can be assessed with the FSSI scales.
The Development of the Sexual Self-Concept Inventory for Early Adolescent Girls
Authors: O'Sullivan Lucia F. , Meyer-Bahlburg Heino F. L. , McKeague Ian W.
Published: May 2006

The Sexual Self-Concept Inventory (SSCI) was developed to assess sexual self-concept in an ethnically diverse sample of urban early adolescent girls. Three scales (Sexual Arousability, Sexual Agency, and Negative Sexual Affect) were shown to be distinct and reliable dimensions of girls' sexual self-concepts. Validity was established through comparisons with established instruments. Sexual Arousability and Sexual Agency were associated with positive sexual self-esteem, positive future orientation toward sex, intentions to engage in intercourse, and lower levels of sexual experience. Negative Sexual Affect was associated with stronger abstinence attitudes and lack of intentions or orientation toward sex in the near future. The results indicate that the SSCI constitutes a valid means of assessing early adolescent girls' views of their sexuality and sexual behavior and may be of use in studies of health and risk-related decision making.
Toward an Understanding of Gender Differences in Inferring Sexual Interest
Authors: Levesque Maurice J. , Nave Christopher S. , Lowe Charles A.
Published: May 2006

Research has shown that, after brief opposite-gender interactions, men perceive women more sexually than women perceive men (e.g., Abbey, 1982 ). This study examined interpersonal perceptions following dyadic cross-gender interactions between unacquainted individuals. Of particular concern were perceptions of sexual traits, interaction qualities, and physical attractiveness. The influence of being gender schematic on sexual judgments was examined. The results provide further support for Abbey's finding that men oversexualize women following brief interactions but failed to support the hypothesized gender schema effects. Additional analyses suggest the presence of another gender difference in judging attraction. Women who rated their partners as physically attractive also attributed more positive qualities to their partner and the interaction. By contrast, men's ratings of women revealed more limited associations with perceived physical attractiveness. Results are discussed in terms of gender differences in judging sexual attraction, the correlates of physical attractiveness, and continuing efforts to explain oversexualization.
Risk Perception, Rape, and Sexual Revictimization: A Prospective Study of College Women
Authors: Messman-Moore Terri L. , Brown Amy L.
Published: May 2006

Risk perception was examined in relation to sexual victimization among 262 college women. Participants were presented with written vignettes that described hypothetical situations with a stranger and with an acquaintance. Participants' hypothetical decision to leave a potentially risky situation with an acquaintance predicted rape and revictimization during an 8-month follow-up period. Revictimized participants had significantly delayed responses compared to previously victimized respondents who were not revictimized. Multivariate models indicated that prior victimization and delayed risk response increased vulnerability for rape and other forms of sexual victimization. Results highlight the need to assess multiple aspects of risk perception, including threat identification and behavioral responses to hypothetical or real situations. Findings suggest that delayed response to danger cues might be one factor that increases vulnerability for revictimization by acquaintances.
Ligious Leaders' Perspectives on Marriage, Divorce, and Intimate Partner Violence
Authors: Levitt Heidi M. , Ware Kimberly N.
Published: May 2006

Religious leaders from Jewish, Christian, and Islamic faiths were interviewed about their understanding of the intersection of intimate partner violence (IPV) and religion, and a grounded-theory analysis was conducted. The present manuscript explored the leaders' beliefs about the partners' responsibility for IPV and the role of divorce. Although religious leaders tended to place greater responsibility for abuse on the perpetrator, most also thought women bore some responsibility—either for inciting abuse or for not leaving the situation. Although there was diversity in beliefs, most of the leaders expressed concerns related to balancing the sacredness of marriage with the urgency of divorce in cases of IPV. Many suggested that divorce be considered as a “last resort” and would urge reconciliation if possible.
Ten polymorphic tetranucleotide microsatellite markers isolated from the Anolis roquet series of Caribbean lizards
Authors: GOW JENNIFER L. , JOHANSSON HELENA , SURGET‐GROBA YANN , THORPE ROGER S.
Published: May 2006

The Anolis roquet series of Caribbean lizards provides natural replicates with which to examine the role of historical contingency and ecological determinism in shaping evolutionary patterns. Here, we describe 10 polymorphic tetranucleotide microsatellites to facilitate studies on population differentiation and gene flow. All loci successfully amplified in several species from this series. Genotyping 96 individuals from two A. roquet populations demonstrated the markers’ suitability as population genetic markers: genetic diversity was high (9–22 alleles per locus); there were no instances of linkage disequilibrium; and, with one exception, all genotypic frequencies conformed to Hardy–Weinberg equilibrium expectations.
PERM: a computer program to detect structuring factors in social units
Authors: DUCHESNE PIERRE , ÉTIENNE CÉDRIC , BERNATCHEZ LOUIS
Published: May 2006

perm is a permutation program designed to detect statistical connections between grouping structures and grouping factors or correlates. Groups may be of various kinds such as herds, flocks, schools and mating couples provided they make up meaningful social units. Relatedness, population membership and genotypic contents are among several aggregating variables which may be processed. Typically, perm takes in a collection of grouped data and outputs a P value. The latter is computed on the basis of random membership among groups (HO). All files, including input, output and program, are of Excel type (.xls). perm can be downloaded free of charge at: http://www.bio.ulaval.ca/louisbernatchez/downloads.htm.
Isolation of highly polymorphic autosomal microsatellite loci and a sex‐linked locus from sugarbirds
Authors: FELDHEIM KEVIN A. , MCFARLANE MHAIRI L. , BOWIE RAURI C. K.
Published: May 2006

We describe the isolation of six tetranucleotide microsatellites from the Cape sugarbird (Promerops cafer) using an enrichment protocol. All loci were highly variable with number of alleles ranging from nine to 26 and values of observed heterozygosity ranging from 0.534 to 0.931. All loci were in Hardy–Weinberg equilibrium with the exception of Pro66 and Pro86. Further analysis of Pro86 indicated it was Z‐linked. All loci amplified and were variable in the congeneric Gurneys sugarbird (Promerops gurneyi). These loci will be used in mating system and phylogeographic studies of Cape sugarbirds in South Africa.