bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retrotransposition strategies of the Lactococcus lactis Ll.LtrB group II intron are dictated by host identity and cellular environment
Authors: Coros Colin J. , Landthaler Markus , Piazza Carol Lyn , Beauregard Arthur , Esposito Donna , Perutka Jiri , Lambowitz Alan M. , Belfort Marlene 
Published: March 2005

SummaryGroup II introns are mobile retroelements that invade their cognate intron‐minus gene in a process known as retrohoming. They can also retrotranspose to ectopic sites at low frequency. Previous studies of the Lactococcus lactis intron Ll.LtrB indicated that in its native host, as in Escherichia coli, retrohoming occurs by the intron RNA reverse splicing into double‐stranded DNA (dsDNA) through an endonuclease‐dependent pathway. However, in retrotransposition in L. lactis, the intron inserts predominantly into single‐stranded DNA (ssDNA), in an endonuclease‐independent manner. This work describes the retrotransposition of the Ll.LtrB intron in E. coli, using a retrotransposition indicator gene previously employed in our L. lactis studies. Unlike in L. lactis, in E. coli, Ll.LtrB retrotransposed frequently into dsDNA, and the process was dependent on the endonuclease activity of the intron‐encoded protein. Further, the endonuclease‐dependent insertions preferentially occurred around the origin and terminus of chromosomal DNA replication. Insertions in E. coli can also occur through an endonuclease‐independent pathway, and, as in L. lactis, such events have a more random integration pattern. Together these findings show that Ll.LtrB can retrotranspose through at least two distinct mechanisms and that the host environment influences the choice of integration pathway. Additionally, growth conditions affect the insertion pattern. We propose a model in which DNA replication, compactness of the nucleoid and chromosomal localization influence target site preference.
Granulocytes govern the transcriptional response, morphology and proliferation of Candida albicans in human blood
Authors: Fradin Chantal , De Groot Piet , MacCallum Donna , Schaller Martin , Klis Frans , Odds Frank C. , Hube Bernhard 
Published: March 2005

SummarySurvival in blood and escape from blood vessels into tissues are essential steps for the yeast Candida albicans to cause systemic infections. To elucidate the influence of blood components on fungal growth, morphology and transcript profile during bloodstream infections, we exposed C. albicans to blood, blood fractions enriched in erythrocytes, polymorphonuclear or mononuclear leukocytes, blood depleted of neutrophils and plasma. C. albicans cells exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils were physiologically active and rapidly switched to filamentous growth. In contrast, the presence of neutrophils arrested C. albicans growth, enhanced the fungal response to overcome nitrogen and carbohydrate starvation, and induced the expression of a large number of genes involved in the oxidative stress response. In particular, SOD5, encoding a glycosylphosphatidylinositol (GPI)‐anchored superoxide dismutase localized on the cell surface of C. albicans, was strongly expressed in yeast cells that were associated with neutrophils. Mutants lacking key genes involved in oxidative stress, morphology or virulence had significantly reduced survival rates in blood and the neutrophil fraction, but remained viable for at least 1 h of incubation when exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils. These data suggest that C. albicans genes expressed in blood were predominantly induced in response to neutrophils, and that neutrophils play a key role during C. albicans bloodstream infections. However, C. albicans is equipped with several genes and transcriptional programmes, which may help the fungus to counteract the attack of neutrophils, to escape from the bloodstream and to cause systemic infections.
Patterns of nucleosomal organization in the alc regulon of Aspergillus nidulans: roles of the AlcR transcriptional activator and the CreA global repressor
Authors: Mathieu Martine , Nikolaev Igor , Scazzocchio Claudio , Felenbok Béatrice 
Published: March 2005

SummaryWe have studied the chromatin organization of three promoters of the alc regulon of Aspergillus nidulans. No positioned nucleosomes are seen in the aldA (aldehyde dehydrogenase) promoter under any physiological condition tested by us. In the alcA (alcohol dehydrogenase I) and alcR (coding for the pathway‐specific transcription factor) promoters, a pattern of positioned nucleosomes is seen under non‐induced and non‐induced repressed conditions. While each of these promoters shows a specific pattern of chromatin restructuring, in both cases induction results in loss of nucleosome positioning. Glucose repression in the presence of inducer results in a specific pattern of partial positioning in the alcA and alcR promoters. Loss of nucleosome positioning depends absolutely on the AlcR protein and it is very unlikely to be a passive result of the induction of transcription. In an alcR loss‐of‐function background and in strains carrying mutations of the respective AlcR binding sites of the alcA and alcR promoters, nucleosomes are fully positioned under all growth conditions. Analysis of mutant AlcR proteins establishes that all domains needed for transcriptional activation and chromatin restructuring are included within the first 241 residues. The results suggest a two‐step process, one step resulting in chromatin restructuring, a second one in transcriptional activation. Partial positioning upon glucose repression shows a specific pattern that depends on the CreA global repressor. An alcR loss‐of‐function mutation is epistatic to a creA loss‐of‐function mutation, showing that AlcR does not act by negating a nucleosome positioning activity of CreA.
Enteropathogenic Escherichia coli EspG disrupts microtubules and in conjunction with Orf3 enhances perturbation of the tight junction barrier
Authors: Tomson Farol L. , Viswanathan V. K. , Kanack Kristen J. , Kanteti Rajani P. , Straub Kathryn V. , Menet Mark , Kaper James B. , Hecht Gail 
Published: March 2005

SummaryEspG, a secreted effector of enteropathogenic Escherichia coli (EPEC), as well as its homologue Orf3, has been shown to disrupt microtubules (MTs) in fibroblasts and non‐polarized epithelial cells. The roles of MTs and the effects of MT disruption in these cell types differ significantly. The aim of this study was to investigate the effects of EspG on polarized, host target intestinal epithelial cells. Immunofluorescent labelling of tubulin showed that EPEC caused progressive fragmentation and loss of the MT network in cells harbouring attached organisms. Immunoblots of proteins extracted from EPEC‐infected cells showed a corresponding loss of α‐tubulin. Type III secretion system (TTSS)‐deficient strains had no effect on MT suggesting TTSS dependence. Mutation of espG, but not espF or map, ablated EPEC's effects on MTs for up to 6 h. Ectopic expression of EspG in HeLa cells caused MT disruption. While deletion of espG alone had no effect on the EPEC‐induced decrease in transepithelial electrical resistance (TER), mutation of both espG and orf3 significantly delayed the kinetics of this response. Complementation of the double mutant with espG alone restored the kinetics of TER drop to that of wild type. Herein, we describe a previously unrecognized phenotype for the EPEC effectors EspG and Orf3.
Differences between cation‐chloride co‐transporter functions in the visual cortex of pigmented and albino rats
Authors: Barmashenko Gleb , Schmidt Matthias , Hoffmann Klaus‐Peter 
Published: March 2005

AbstractAlbinism in mammals is accompanied by specific morphological and functional alterations of the visual system. To understand their cellular basis we studied the physiological characteristics and transmembrane currents of pyramidal neurons in 350‐µm‐thick slices of visual cortex from pigmented and albino rats using whole‐cell and gramicidin perforated patch‐clamp recordings. The resting membrane potential was significantly more positive and the rheobase was significantly lower in neurons of layers II/III and V in albinos as compared with pigmented rats. No significant differences were found in the input resistance, time constant and chronaxy. Whereas the α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptor‐mediated currents were not significantly different, the maximum γ‐aminobutyric acid (GABA)A receptor (GABAAR)‐mediated currents and miniature inhibitory postsynaptic currents showed significantly lower amplitudes in neurons of layer V in visual cortex of albinos as compared with pigmented rats. The reversal potential of the GABAAR‐mediated currents (EGABA) was significantly shifted to more positive values in albinos. Pharmacological experiments showed that this shift could be caused by an increased action of the inward chloride co‐transporter NKCC1 and reduced action of the outward chloride co‐transporter KCC2 in albino rats. This difference seems to be restricted to the visual cortex because in pyramidal neurons from frontal cortex EGABA was not significantly different in albinos as compared with pigmented rats. These results are discussed in relation to functional alterations in the albino visual system.
Impairment of conditioned freezing to tone, but not to context, in Fyn‐transgenic mice: relationship to NMDA receptor subunit 2B function
Authors: Kojima N. , Sakamoto T. , Endo S. , Niki H. 
Published: March 2005

AbstractWe previously demonstrated that transgenic mice overexpressing Fyn tyrosine kinase exhibit higher seizure susceptibility and enhanced tyrosine phosphorylation of several proteins, including the N‐methyl‐D‐aspartate (NMDA) receptor subunit 2B (NR2B). In the present study, we analysed behavioural phenotypes, especially conditioned fear responses, of Fyn‐transgenic (TG) mice to better understand the role of Fyn in learned emotional behaviour. Tone‐dependent conditioned freezing was significantly attenuated in Fyn‐TG mice, whereas context‐dependent freezing was unaffected. Neither massed nor spaced conditioning ameliorated the attenuation of tone‐dependent freezing. However, the selective NR2B antagonist ifenprodil, when administered before conditioning, restored tone‐dependent freezing in Fyn‐TG mice at a dose that did not affect freezing in wild‐type (WT) mice. These results suggest that impairment of tone‐dependent conditioned freezing in Fyn‐TG mice is caused by disruption of the NR2B‐containing NMDA receptor function. Tyrosine phosphorylation of brain proteins, including NR2B, was enhanced in Fyn‐TG mice compared with that in WT mice. We also found that ifenprodil significantly suppressed the enhanced tyrosine phosphorylation. Thus, our data support the notion that NMDA receptor activity is tightly correlated with protein tyrosine phosphorylation, and Fyn might be one key molecule that controls tone‐dependent conditioned freezing through the regulation of NMDA receptor function.
Endogenous enkephalins, not endorphins, modulate basal hedonic state in mice
Authors: Skoubis P. D. , Lam H. A. , Shoblock J. , Narayanan S. , Maidment N. T. 
Published: March 2005

AbstractThe aversive response to naloxone administration observed in human and animal studies suggests the presence of an endogenous opioid tone regulating hedonic state but the class(es) of opioid peptides mediating such opioid hedonic tone is uncertain. We sought to address this question using mice deficient in either beta‐endorphin or pro‐enkephalin in a naloxone‐conditioned place aversion paradigm. Mice received saline in the morning in one chamber and either saline or naloxone (0.1, 1 or 10 mg/kg, s.c.) in the afternoon in another chamber, each day for 3 days. On the test day they were given free access to the testing chambers in the afternoon and the time spent in each chamber was recorded. Whereas wild‐type and beta‐endorphin‐deficient mice exhibited a robust conditioned place aversion to naloxone, pro‐enkephalin knockout mice failed to show aversion to naloxone at any dose tested. In contrast, these mice showed a normal conditioned aversion to the kappa opioid receptor agonist, U50,488 (5 mg/kg), and to LiCl (100 mg/kg) indicating that these mice are capable of associative learning. In a separate experiment, pro‐enkephalin knockout mice, similar to wild‐type and beta‐endorphin‐deficient mice, demonstrated a significant conditioned place preference to morphine (2.5, 5 and 10 mg/kg s.c.). These data suggest that enkephalins, but not endorphins, may mediate an endogenous opioid component of basal affective state and also indicate that release of neither endogenous enkephalins nor endorphins is critical for the acquisition or expression of the association between contextual cues and the rewarding effect of exogenously administered opiates.
Behavioural phenotypes of hypomorphic KCC2‐deficient mice
Authors: Tornberg Janne , Voikar Vootele , Savilahti Harri , Rauvala Heikki , Airaksinen Matti S. 
Published: March 2005

AbstractHyperpolarizing fast inhibitory neurotransmission by γ‐aminobutyric acid and glycine requires an efficient chloride extrusion mechanism in postsynaptic neurons. A major effector of this task in adult animals is the potassium‐chloride co‐transporter KCC2 that is selectively and abundantly expressed postsynaptically in most CNS neurons. Yet, the role of KCC2 in adult brain at the systems level is poorly known. Here, we characterize the behaviour of mice doubly heterozygous for KCC2 null and hypomorphic alleles that retain 15–20% of normal KCC2 protein levels in the brain. These hypomorphic KCC2‐deficient mice were viable and fertile but weighed 15–20% less than wild‐type littermates at 2 weeks old and thereafter. The mice displayed increased anxiety‐like behaviour in several tests including elevated plus‐maze and were more susceptible to pentylenetetrazole‐induced seizures. Moreover, the mice were impaired in water maze learning and showed reduced sensitivity to tactile and noxious thermal stimuli in von Frey hairs, hot plate and tail flick tests. In contrast, the mice showed normal spontaneous locomotor activity in open field and Y‐maze tests, and intact motor coordination in rotarod and beam tests. The results suggest that requirements for KCC2‐dependent fast hyperpolarizing inhibition may differ among various functional systems of the CNS. As shunting inhibition is expected to be intact in KCC2‐deficient neurons, these mice may provide a useful tool to study the specific functions and relative importance of hyperpolarizing fast synaptic inhibition in adult CNS that may have implications for human neuropsychiatric disorders, such as epilepsy, pain and anxiety.
Synaptic contacts between an identified type of ON cone bipolar cell and ganglion cells in the mouse retina
Authors: Lin Bin , Masland Richard H. 
Published: March 2005

AbstractWe surveyed the potential contacts between an identified type of bipolar cell and retinal ganglion cells in the mouse. By crossing two existing mouse strains (line 357 and line GFP‐M), we created a double transgenic strain in which GFP is expressed by all members of a single type of ON cone bipolar cell and a sparse, mixed population of retinal ganglion cells. The GFP‐expressing bipolar cells appear to be those termed CB4a of Pignatelli & Strettoi [(2004) J. Comp. Neurol., 476, 254–266] and type 7 of Ghosh et al. [(2004) J. Comp. Neurol., 469, 70–82 and J. Comp. Neurol., 476, 202–203]. The labelled ganglion cells include examples of most or all types of ganglion cells present in the mouse. By studying the juxtaposition of their processes in three dimensions, we could learn which ganglion cell types are potential synaptic targets of the line 357 bipolar cell. Of 12 ganglion cell types observed, 10 types could be definitively ruled out as major synaptic targets of the line 357 bipolar cells. One type of monostratified ganglion cell and one bistratified cell tightly cofasciculate with axon terminals of the line 357 bipolar cells. Double labelling for kinesin II demonstrates colocalization of bipolar cell ribbons at the sites of contact between these two types of ganglion cell and the line 357 bipolar cells.
Short‐term treatment with the antidepressant fluoxetine triggers pyramidal dendritic spine synapse formation in rat hippocampus
Authors: Hajszan Tibor , MacLusky Neil J. , Leranth Csaba 
Published: March 2005

AbstractThe pathomechanism of major depressive disorder and the neurobiological basis of antidepressant therapy are still largely unknown. It has been proposed that disturbed hippocampal activity could underlie some of the cognitive and vegetative symptoms of depression, at least in part because of loss of pyramidal cell synaptic contacts, a process that is likely to be reversed by antidepressant treatment. Here we provide evidence that daily administration of the antidepressant fluoxetine to ovariectomized female rats for 5 days induces a robust increase in pyramidal cell dendritic spine synapse density in the hippocampal CA1 field, with similar changes appearing in CA3 after 2 weeks of treatment. This rapid synaptic remodelling might represent an early step in the fluoxetine‐induced cascade of responses that spread across the entire hippocampal circuitry, leading to the restoration of normal function in the hippocampus. Hippocampal synaptic remodelling might provide a potential mechanism to explain certain aspects of antidepressant therapy and mood disorders, especially those associated with changes in reproductive state in women, that cannot be reconciled adequately with current theories for depression.
The influence of bladder neck mucosal eversion and early urinary extravasation on patient outcome after radical retropubic prostatectomy: a prospective controlled trial
Authors: Srougi Miguel , Paranhos Mario , Leite Kátia M. , Dall’oglio Marcos , Nesrallah Luciano 
Published: March 2005

OBJECTIVETo evaluate the role of bladder neck (BN) mucosal eversion during retropubic radical prostatectomy (RRP) on the rate of BN sclerosis and urinary incontinence, with the hypothesis that BN mucosal eversion is not essential to improve the clinical outcome after RRP.PATIENTS AND METHODSOne hundred patients with stage T1c–T2c prostate cancer had RRP by the same surgeon and were randomly divided in two equal groups; one had a vesico‐urethral anastomosis with and one with no BN mucosal eversion. The patients were assessed by retrograde cysto‐urethrography 4 days after surgery to evaluate the presence of urinary leakage. The occurrence of BN sclerosis and the rate of urinary incontinence (more than one pad/day) was assessed by double‐blind interviews at 2 days, 2 months and 6 months after catheter removal, and the incidence of BN sclerosis was also assessed after 12 months.RESULTSIn the groups with or with no BN mucosal eversion, 48 and 47 patients, respectively, fulfilled the selection criteria. Urinary leakage after vesico‐urethral anastomosis was more common after mucosal eversion (33% vs 21%), but not significantly (P = 0.251). BN sclerosis occurred in only one patient, with no mucosal eversion. The rate of urinary continence was similar in both groups at 2 days (69% vs 68%, respectively), 2 months (90% vs 87%) and 6 months (92% vs 92%) after surgery. Urinary extravasation at 4 days after surgery was followed by same rate of BN sclerosis and urinary continence as in patients with no urinary extravasation.CONCLUSIONBN mucosal eversion before vesico‐urethral anastomosis during RRP is not essential to reduce the frequency of BN sclerosis or urinary incontinence. Early radiological urinary extravasation at the vesico‐urethral anastomosis did not increase the risk of BN sclerosis or urinary incontinence.
A novel technique for approaching the endopelvic fascia in retropubic radical prostatectomy, based on an anatomical study of fixed and fresh cadavers
Authors: Takenaka Atsushi , Hara Ryoei , Soga Hideo , Murakami Gen , Fujisawa Masato 
Published: March 2005

OBJECTIVETo present the anatomical basis and details of a technique for an approach to the endopelvic fascia devised to preserve urinary continence.PATIENTS, MATERIALS AND METHODSFor cross‐sectional macroscopic observation, seven formalin‐fixed specimens of the male pelvic contents including the pelvic wall were serially sectioned at a 5‐mm thickness. Semi‐serial sections from eight other specimens were examined histologically. Eight fresh cadavers were dissected to mimic the various steps in a retropubic radical prostatectomy. After approaching the endopelvic fascia in an anatomically determined manner to reach the paraprostatic space, the pubic bone was removed and nerves near the rhabdosphincter dissected. To assess the clinical implication of this approach, we examined the time to achieve continence in 23 consecutive patients who had a radical retropubic prostatectomy using the new technique.RESULTSSectional macroscopic observation depicted the fascia of the levator ani as a definite structure adherent to but not fused with the lateral pelvic fascia. The thin fascia overlying the levator ani fascia and lateral pelvic fascia represented the true endopelvic fascia. Microscopically, the lower part of the fascia of the levator ani was rich in smooth muscle, which interdigitated with the framework of the rhabdosphincter. In fresh cadavers, the levator ani muscle was removed laterally still covered by its fascia, without visualizing the muscle fibres. Small branches from the pudendal nerve entered the rhabdosphincter. The mean (sd, range) distance from the lowest point of the endopelvic fascia to the point where the sphincteric branch entered the rhabdosphincter was 5.5 (1.8, 3–8) mm. The continence rate at 1, 3, 6 and 9 months after surgery using the new technique was 44%, 83%, 96% and 100%, respectively.CONCLUSIONSPreserving the fascia of the levator ani helps to protect the levator ani muscle, rhabdosphincter and pudendal nerve branches to the rhabdosphincter. In retropubic radical prostatectomy, this anatomical approach to the endopelvic fascia should preserve or allow the earlier recovery of urinary continence.
The incidence and treatment of lymphoceles after radical retropubic prostatectomy
Authors: Pepper Ruth J. , Pati Jhumur , Kaisary Amir V. 
Published: March 2005

OBJECTIVETo determine the incidence and treatment of lymphoceles after retropubic radical prostatectomy (RP).PATIENTS AND METHODSUp to January 2004, 260 patients who had a retropubic RP in one institution by one surgeon were assessed retrospectively, using the patients’ notes or the computerized results system to determine whether a lymphocele was suspected and then confirmed by imaging studies (computed tomography or ultrasonography).RESULTSNine patients developed symptomatic lymphoceles; eight of these were detected by imaging. Four lymphoceles required intervention while the remainder regressed spontaneously. No complications were reported in the group that was treated.CONCLUSIONThe rate of symptomatic lymphocele formation was low after RP, with an overall incidence of 3.5%. Ultrasonography was effective in detecting lymphoceles and ultrasonographically guided percutaneous drainage an effective treatment.