bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Corticotropin‐Releasing Factor Binding Protein‐Immunoreactivity in the Rat Hypothalamus: Association With Corticotropin‐Releasing Factor‐, Urocortin 1‐ and Vimentin‐Immunoreactive Fibres
Authors: Henry B. A. , Lightman S. L. , Lowry C. A. 
Published: March 2005

AbstractCorticotropin‐releasing factor binding protein (CRF‐BP) is a 37‐kDa protein with high affinity binding sites for both corticotropin‐releasing factor (CRF) and urocortin 1. Previous studies have examined the distribution of CRF‐BP mRNA and peptide within the central nervous system. Due to the predominant cortical localisation, very little is known about CRF‐BP in subcortical structures including the hypothalamus. The present study employed immunohistochemistry to characterise the distribution of CRF‐BP‐like‐immunoreactive (‐ir) cells and fibres in the rat hypothalamus. Bipolar and multipolar CRF‐BP‐ir neurones were scattered throughout the rostro‐caudal extent of the hypothalamus. Distinct clusters of CRF‐BP‐ir neurones were identified in the anterior and posterior parvocellular and dorsal cap subdivisions of the paraventricular nucleus (PVN), as well as in the dorsal hypothalamic area, dorsomedial hypothalamic nucleus (DMN), ventral premammillary nucleus and zona incerta. CRF‐BP‐ir fibres extending from the third ventricle were found in the mediobasal hypothalamus and within the arcuate nucleus‐median eminence region. Double immunostaining together with confocal microscopy demonstrated that the CRF‐BP‐immunostained fibres within the mediobasal hypothalamus coincided with vimentin immunostaining indicating that CRF‐BP‐ir is present within tanycytes. To define the relationship between CRF‐BP‐ir cells and endogenous ligands for CRF‐BP, double immunohistochemistry was performed to examine possible sites within the hypothalamus where CRF‐ or urocortin 1‐ir fibres innervate regions that contain CRF‐BP‐ir cell bodies. CRF‐BP‐ir cell bodies typically coincided with dense CRF‐ir, but not urocortin 1‐ir fibre innervation. CRF‐ir fibre innervation was moderate to high within the anterior and posterior parvocellular subdivisions of the PVN, the dorsal cap of the PVN, DMN and the zona incerta; all regions that contained CRF‐BP‐ir cell populations. These studies demonstrate that, within the hypothalamus, CRF‐BP‐ir cells and fibres are concentrated within a circuitry known to be involved in mediating neuroendocrine and autonomic responses to stress.
Progesterone Can Block the Preovulatory Gonadotropin‐Releasing Hormone/Luteinising Hormone Surge in the Ewe by a Direct Inhibitory Action on Oestradiol‐Responsive Cells within the Hypothalamus
Authors: Richter T. A. , Robinson J. E. , Lozano J. M. , Evans N. P. 
Published: March 2005

AbstractElevated oestradiol concentrations during the follicular phase stimulate a surge in gonadotropin‐releasing hormone (GnRH) and luteinising hormone (LH) concentrations, which leads to ovulation. Progesterone can block the oestradiol‐induced GnRH/LH surge, but the mechanism that is involved is unclear. We examined the effect of progesterone on oestradiol‐induced activation of cells within the ovine hypothalamus/preoptic area (POA) to determine: (i) in which regions progesterone acts to block the GnRH/LH surge and (ii) whether progesterone directly or indirectly prevents activation of oestradiol‐responsive cells. Cellular activation was assessed by measuring the number of cells that expressed Fos (an immediate early gene). Exposure to increased oestradiol concentrations in the absence of progesterone (which normally stimulates a LH surge) did not cause any region‐specific changes in hypothalamic Fos expression during the activation stage of the LH surge‐induction process (Experiment 1). The same treatment significantly increased cellular activation within the POA, lateral septum (LS), and arcuate nucleus at the time of surge onset (Experiment 2). Concurrent exposure to increased oestradiol and progesterone concentrations during the activation stage of the surge‐induction process (which normally blocks the LH surge) was associated with significantly reduced cellular activation within the ventromedial hypothalamus and anterior hypothalamic area, relative to the positive controls (oestradiol increment alone) and arcuate nucleus relative to the negative controls (no increment in oestradiol) during the activation stage (Experiment 1). At the time of surge onset (Experiment 2), exposure to progesterone during the activation period prevented the oestradiol‐induced increase in cellular activation that occurred in the POA, LS and arcuate nucleus of the positive controls. These results demonstrated that oestradiol and progesterone induced differential region‐ and time‐specific effects on cellular activation within the regions of the ovine brain that generate the preovulatory GnRH/LH surge. Moreover, the lack of cellular activation within the POA, LS and arcuate nucleus at the time of surge onset in animals exposed to progesterone during the activation stage is consistent with the hypothesis that progesterone can block the preovulatory surge by direct inhibition of oestradiol‐induced cellular activation in these areas.
Hypothalamic STAT Proteins: Regulation of Somatostatin Neurones by Growth Hormone Via STAT5b
Authors: Bennett E. , McGuinness L. , Gevers E. F. , Thomas G. B. , Robinson I. C. A. F. , Davey H. W. , Luckman S. M. 
Published: March 2005

AbstractSignal transducers and activators of transcription (STATs) are a family of transcription factors linked to class I cytokine receptors. In the present study, we investigated whether their distribution in the hypothalamus reflects the feedback regulation by growth hormone and what role they might play in the functioning of target neurones. We demonstrate that each of the seven known STATs has a distinct distribution in the hypothalamus. Notably, the STAT5 proteins, that are important in growth hormone (GH) and prolactin signalling in peripheral tissues, were expressed in somatostatin neurones of the periventricular nucleus and dopamine neurones of the arcuate nucleus. Because somatostatin neurones are regulated by feedback from circulating GH, we investigated the importance of STAT5 in these neurones. We demonstrate that STAT5b protein expression, similar to somatostatin mRNA, is sexually dimorphic in the periventricular nucleus of rats and mice. Furthermore, chronic infusion of male dwarf rats with GH increased the expression of STAT5b, while a single injection of GH into similar rats induced the phosphorylation of STAT5 proteins. The cellular abundance of somatostatin mRNA in STAT5b‐deficient mice was significantly reduced in the periventricular nucleus, effectively reducing the sexually dimorphic expression. These results are consistent with the hypothesis that STAT5 proteins are involved in the feedback regulation of somatostatin neurones by GH, and that these neurones may respond to patterned GH secretion to reinforce sexual dimorphism in the GH axis.
Regulation of Sin recombinase by accessory proteins
Authors: Rowland Sally J. , Boocock Martin R. , Stark W. Marshall 
Published: March 2005

SummarySin recombinase fromStaphylococcus aureusacts selectively on directly repeatedresHsites, assembling an intertwined synapse in which exactly three supercoils are trapped between the points of strand exchange. Resolution requires the two Sin binding sites inresH(site I, where strand exchange occurs, and site II) and a non‐specific DNA‐bending protein (e.g. Hbsu). We show that a single amino acid substitution in Sin (I100T) is sufficient to relax the normal requirements for site II and Hbsu. Using this hyperactive protein, and the variant recombination siteresHAT, we investigate the roles of site II and Hbsu in synapsis and strand exchange. We conclude that Sin bound at site II, and Hbsu, act together to control site I alignment and the topology of the synapse, and to stimulate strand exchange.
Protein kinase C modulates light responses in Neurospora by regulating the blue light photoreceptor WC‐1
Authors: Franchi Lisa , Fulci Valerio , Macino Giuseppe 
Published: March 2005

SummaryThe Neurospora protein kinase C (NPKC) is a regulator of light responsive genes. We have studied the function of NPKC in light response by investigating its biochemical and functional interaction with the blue light photoreceptor white‐collar 1 (WC‐1), showing that activation of NPKC leads to a significant decrease in WC‐1 protein levels. Furthermore, we show that WC‐1 and NPKC interact in a light‐regulated manner in vivo, and that protein kinase C (PKC) phosphorylates WC‐1 in vitro. We designed dominant negative and constitutively active forms of PKC which are able to induce either a large increase of WC‐1 protein level or a strong reduction respectively. Moreover, these changes in PKC activity result in an altered light response. As WC‐1 is a key component of Neurospora circadian clock and regulates the clock oscillator component FRQ we investigated the effect of NPKC‐mutated forms on FRQ levels. We show that changes in PKC activity affect FRQ levels and the robustness of the circadian clock. Together these data identify NPKC as a novel component of the Neurospora light signal transduction pathway that modulates the circadian clock.
Blue light negatively regulates the sexual filamentation via the Cwc1 and Cwc2 proteins in Cryptococcus neoformans
Authors: Lu Ying‐Ku , Sun Kai‐Hui , Shen Wei‐Chiang 
Published: March 2005

Summary Cryptococcus neoformans is a heterothallic basidiomycetous yeast that primarily infects immunocompromised individuals. Dikaryotic hyphae resulting from the fusion of the MATa and MATα mating type strains represent the filamentous stage in the sexual life cycle of C. neoformans. In this study we demonstrate that the production of dikaryotic filaments is inhibited by blue light. To study blue light photoresponse in C. neoformans, we have identified and characterized two genes, CWC1 and CWC2, which are homologous to Neurospora crassa wc‐1 and wc‐2 genes. Conserved domain analyses indicate that the functions of Cwc1 and Cwc2 proteins may be evolutionally conserved. To dissect their roles in the light response, the CWC1 gene deletion mutants are created in both mating type strains. Mating filamentation in the bilateral cross of cwc1 MATa and MATα strains is not sensitive to light. The results indicate that Cwc1 may be an essential regulator of light responses in C. neoformans. Furthermore, overexpression of the CWC1 or CWC2 gene requires light activation to inhibit sexual filamentation, suggesting both genes may function together in the early step of blue light signalling. Taken together, our findings illustrate blue light negatively regulates the sexual filamentation via the Cwc1 and Cwc2 proteins in C. neoformans.
Respiration metabolism of Group B Streptococcus is activated by environmental haem and quinone and contributes to virulence
Authors: Yamamoto Yuji , Poyart Claire , Trieu‐Cuot Patrick , Lamberet Gilles , Gruss Alexandra , Gaudu Philippe 
Published: March 2005

SummaryGroup B Streptococcus (GBS) is a common constituent of the vaginal microflora, but its transmission to newborns can cause life‐threatening sepsis, pneumonia and meningitis. Energy metabolism of this opportunist pathogen has been deduced to be strictly fermentative. We discovered that GBS undergoes respiration metabolism if its environment supplies two essential respiratory components: quinone and haem. Respiration metabolism led to significant changes in growth characteristics, including a doubling of biomass and an altered metabolite profile under the tested conditions. The GBS respiratory chain is inactivated by: (i) withdrawing haem and/or quinone, (ii) treating cultures with a respiration inhibitor or (iii) inactivating the cydA gene product, a subunit of cytochrome bd quinol oxidase, in all cases resulting in exclusively fermentative growth. cydA inactivation reduced GBS growth in human blood and strongly attenuated virulence in a neonatal rat sepsis model, suggesting that the animal host may supply the components that activate GBS respiration. These results suggest a role of respiration metabolism in GBS dissemination. Our findings show that environmental factors can increase the flexibility of GBS metabolism by activating a newly identified respiration chain. The need for two environmental factors may explain why GBS respiration metabolism was not found in previous studies.
Defining the role of PfCRT in Plasmodium falciparum chloroquine resistance
Authors: Bray Patrick G. , Martin Rowena E. , Tilley Leann , Ward Stephen A. , Kirk Kiaran , Fidock David A. 
Published: March 2005

SummaryRecent studies have highlighted the importance of a parasite protein referred to as the chloroquine resistance transporter (PfCRT) in the molecular basis of Plasmodium falciparum resistance to the quinoline antimalarials. PfCRT, an integral membrane protein with 10 predicted transmembrane domains, is a member of the drug/metabolite transporter superfamily and is located on the membrane of the intra‐erythrocytic parasite's digestive vacuole. Specific polymorphisms in PfCRT are tightly correlated with chloroquine resistance. Transfection studies have now proven that pfcrt mutations confer verapamil‐reversible chloroquine resistance in vitro and reveal their important role in resistance to quinine. Available evidence is consistent with the view that PfCRT functions as a transporter directly mediating the efflux of chloroquine from the digestive vacuole.
The mutation G145S in PrfA, a key virulence regulator of Listeria monocytogenes, increases DNA‐binding affinity by stabilizing the HTH motif
Authors: Eiting Marina , Hagelüken Gregor , Schubert Wolf‐Dieter , Heinz Dirk W. 
Published: March 2005

Summary Listeria monocytogenes, a Gram‐positive, facultative intracellular human pathogen, causes systemic infections with high mortality rate. The majority of the known pathogenicity factors of L. monocytogenes is regulated by a single transcription factor, PrfA. Hyperhaemolytic laboratory strains of L. monocytogenes express the constitutively active mutant PrfAG145S inducing virulence gene overexpression independent of environmental conditions. PrfA belongs to the Crp/Fnr family of transcription factors generally activated by a small effector, such as cAMP or O2. We present the crystal structures of wild‐type PrfA, the first Gram‐positive member of the Crp/Fnr family, and of the constitutively active mutant PrfAG145S. Cap (Crp) has previously been described exclusively in the cAMP‐induced (DNA‐free and ‐bound) conformation. By contrast, the PrfA structures present views both of the non‐induced state and of the mutationally activated form. The low DNA‐binding affinity of wild‐type PrfA is supported both structurally (partly disordered helix–turn–helix motif, overall geometry of the HTH α‐helices deviates from Cap) and by surface plasmon resonance analyses (KD = 0.9 µM). In PrfAG145S the HTH motifs dramatically rearrange to adopt a conformation comparable to cAMP‐induced Cap and hence favourable for DNA binding, supported by a DNA‐binding affinity of 50 nM. Finally, the hypothesis that wild‐type PrfA, like other Crp/Fnr family members, may require an as yet unidentified cofactor for activation is supported by the presence of a distinct tunnel in PrfA, located at the interface of the β‐barrel and the DNA‐binding domain.
The Effect of Different Timing of Top Dressing of Nitrogen Application under Low Light Intensity on the Yield of Rice (Oryza sativa L.)
Authors: Samarajeewa K. B. D. P. , Kojima N. , Sakagami J.‐I. , Chandanie W. A. 
Published: March 2005

AbstractThree levels of shade (0, 45 and 70 %) on rice was studied by changing the time of nitrogen top dressing application. The shade was given for the respective plots from heading up to harvesting and the top dressing was applied 20 days (standard) and 5 days (late) before heading. Significant yield reduction was not observed under the given conditions but ripening percentage and thousand‐grain weight was significantly affected. Ripening rate was found as the key factor that determined the rice yield under low light intensities. The adverse effects of shade on the yield and yield components were not able to significantly minimize by the change of the timing of application of nitrogen top dressing.
Different responsiveness of striatonigral and striatopallidal neurons to L‐DOPA after a subchronic intermittent L‐DOPA treatment
Authors: Carta A. R. , Tronci E. , Pinna A. , Morelli M. 
Published: March 2005

AbstractEarly gene induction by L‐DOPA in the striatum of dopamine denervated rats represents a useful way to study long‐term modifications produced by this drug. The effects of acute and subchronic L‐DOPA administration on zif‐268 mRNA expression were compared in 6‐hydroxydopamine‐lesioned rats. Rats received a subchronic intermittent L‐DOPA (6 mg/kg) treatment, which produces behavioural sensitization, a correlate of dyskinetic movements. Three days after interruption of subchronic treatment, zif‐268 mRNA was evaluated after an L‐DOPA challenge. Zif‐268 mRNA levels increased in the lesioned dorsolateral striatum after either acute or subchronic L‐DOPA administration. Double labelling of striatal cells with zif‐268 and enkephalin or dynorphin mRNA probes was performed to assess neuronal activation in the indirect and direct output pathway. Single acute L‐DOPA significantly increased zif‐268 in all striatal neurons reflecting a hyperresponsiveness of dopamine‐depleted striatum. After subchronic L‐DOPA, zif‐268 mRNA labelling was still increased in the striatonigral pathway, limited to dynorphin+ neurons, whereas in all other neurons it was similar to the control value. Results suggest that striatal neurons responding to acute L‐DOPA differ from those responding to subchronic L‐DOPA. L‐DOPA‐induced behavioural sensitization was associated to a down‐regulation in the responsiveness of striatopallidal and striatonigral dynorphin– neurons, whereas in striatonigral neurons containing dynorphin a hyperresponsiveness to L‐DOPA was observed. High levels of zif‐268, together with a persistent hyperresponsiveness of striatonigral dymorphinergic neurons and hyporesponsiveness of striatopallidal neurons, by creating an unbalanced state of striatal efferent neurons, may be implicated in dyskinetic movements observed in Parkinson's disease (PD).
Defective control and adaptation of reflex eye movements in mutant mice deficient in either the glutamate receptor δ2 subunit or Purkinje cells
Authors: Katoh Akira , Yoshida Takashi , Himeshima Yufuko , Mishina Masayoshi , Hirano Tomoo 
Published: March 2005

AbstractThe ionotropic glutamate receptor δ2 subunit (GluRδ2) is selectively expressed in cerebellar Purkinje cells and is implicated in long‐term depression, synaptic formation and elimination. To study the effect of GluRδ2 deficiency on motor control, we measured the vestibulo‐ocular reflex (VOR) and optokinetic response (OKR) induced by sinusoidal rotation of the animal and/or the surrounding screen in two GluRδ2 mutant mice: a GluRδ2 knockout mouse (δ2–/–) and a lurcher mouse with a point mutation in the GluRδ2 gene resulting in loss of all Purkinje cells. δ2–/– showed significantly higher VOR gain in the dark (VORD) than in the wild‐type. In δ2–/–, the VOR gain in light was lower than that in the dark. The phase of OKR lagged more in δ2–/– than in lurcher and wild‐type mice. Both mutant mice failed to change the VORD or OKR gain adaptively in response to sustained vestibular and/or visual stimulation. Basal properties of VOR and OKR changed little by lesion of the flocculus, but they changed substantially by lesion of the inferior olivary nuclei (IO). The abnormal VOR gain and OKR phase delay were clearly reduced in δ2–/– by the latter lesion. Our results indicate that failures in the GluRδ2‐dependent synaptic regulation affect motor performance more severely than loss of cerebellar cortical outputs. This study suggests that the anomalies in δ2–/– are dependent on inputs from IO and that GluRδ2 deficiency changed properties of not only the cerebellar cortex but also the brainstem neuronal pathways controlling reflex eye movements during development.
Differential regulation of type I and type II interleukin‐1 receptors in focal brain inflammation
Authors: Docagne Fabian , Campbell Sandra J. , Bristow Adrian F. , Poole Stephen , Vigues Stephan , Guaza Carmen , Perry V. Hugh , Anthony Daniel C. 
Published: March 2005

AbstractMost pathologies of the brain have an inflammatory component, associated with the release of cytokines such as interleukin‐1β (IL‐1β) from resident and infiltrating cells. The IL‐1 type I receptor (IL‐1RI) initiates a signalling cascade but the type II receptor (IL‐1RII) acts as a decoy receptor. Here we have investigated the expression of IL‐1β, IL‐1RI and IL‐1RII in distinct inflammatory lesions in the rat brain. IL‐1β was injected into the brain to generate an inflammatory lesion in the absence of neuronal cell death whereas neuronal death was specifically induced by the microinjection of N‐methyl‐d‐aspartate (NMDA). Using TaqMan RT‐PCR and ELISA, we observed elevated de novo IL‐1β synthesis 2 h after the intracerebral microinjection of IL‐1β; this de novo IL‐1β remained elevated 24 h later. There was a concomitant increase in IL‐1RI mRNA but a much greater increase in IL‐1RII mRNA. Immunostaining revealed that IL‐1RII was expressed on brain endothelial cells and on infiltrating neutrophils. In contrast, although IL‐1β and IL‐1RI were elevated to similar levels in response to NMDA challenge, the response was delayed and IL‐1RII mRNA expression was unchanged. The lesion‐specific expression of IL‐1 receptors suggests that the receptors are differentially regulated in a manner not directly related to the endogenous level of IL‐1 in the CNS.
Intracerebral study of gamma rhythm reactivity in the sensorimotor cortex
Authors: Szurhaj William , Bourriez Jean‐Louis , Kahane Philippe , Chauvel Patrick , Mauguière François , Derambure Philippe 
Published: March 2005

AbstractThe generators and functional correlates of gamma oscillations within the sensorimotor cortex remain unclear. With the goal of locating the oscillations' sources precisely and then studying the relationship between oscillatory reactivity and ongoing movement, we recorded stereoelectroencephalograms with intracerebral electrodes in eight epileptic subjects awaiting surgical treatment. The sensorimotor cortex was free of lesions and was exhaustively explored with the electrodes. Subjects were asked to perform various self‐paced movements contralateral to the exploration zone, brief and sustained, distal movements and a pointing movement. We used the event‐related desynchronization method to quantify the reactivity of the 40–60‐Hz band before, during and after the performance of movement. A very focused, event‐related synchronization of gamma rhythms was found in all subjects. It was predominantly observed in the primary sensorimotor area and its distribution was consistent with the functional map established using electrical stimulations. Two different temporal patterns were observed, the event‐related synchronization of gamma rhythms was related either to movement onset or to movement offset but was never recorded before movement. This observation suggests that gamma oscillations are more probably related to movement execution than to motor planning. The different patterns argue in favour of multiple functional roles; it has been shown that gamma oscillations may support the efferent drive to the muscles and here we show that they are also likely to be related to somatosensory integration. We therefore suggest that gamma oscillations in the 40–60‐Hz band may support afferent sensory feedback to the sensorimotor cortex during the performance of movement.