bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and biochemical characterization of a novel Mn2+‐dependent phosphodiesterase encoded by the yfcE gene
Authors: Miller Darcie J. , Shuvalova Ludmilla , Evdokimova Elena , Savchenko Alexei , Yakunin Alexander F. , Anderson Wayne F.
Published: June 2007

Escherichia coli YfcE belongs to a conserved protein family within the calcineurin‐like phosphoesterase superfamily (Pfam00149) that is widely distributed in bacteria and archaea. Superfamily members are metallophosphatases that include monoesterases and diesterases involved in a variety of cellular functions. YfcE exhibited catalytic activity against bis‐p‐nitrophenyl phosphate, a general substrate for phosphodiesterases, and had an absolute requirement for Mn2+. However, no activity was observed with phosphodiesters and over 50 naturally occurring phosphomonoesters. The crystal structure of the YfcE phosphodiesterase has been determined to 2.25 Å resolution. YfcE has a β‐sandwich architecture similar to metallophosphatases of common ancestral origin. Unlike its more complex homologs that have added structural elements for regulation and substrate recognition, the relatively small 184‐amino‐acid protein has retained its ancestral simplicity. The tetrameric protein carries two zinc ions per active site from the E. coli extract that reflect the conserved di‐Mn2+ active site geometry. A cocrystallized sulfate inhibitor mimics the binding of phosphate moeities in known ligand/phosphatase complexes. Thus, YfcE has a similar active site and biochemical mechanism as well‐characterized superfamily members, while the YfcE phosphodiester‐containing substrate is unique.
OPUS‐Ca: A knowledge‐based potential function requiring only Cα positions
Authors: Wu Yinghao , Lu Mingyang , Chen Mingzhi , Li Jialin , Ma Jianpeng
Published: June 2007

In this paper, we report a knowledge‐based potential function, named the OPUS‐Ca potential, that requires only Cα positions as input. The contributions from other atomic positions were established from pseudo‐positions artificially built from a Cα trace for auxiliary purposes. The potential function is formed based on seven major representative molecular interactions in proteins: distance‐dependent pairwise energy with orientational preference, hydrogen bonding energy, short‐range energy, packing energy, tri‐peptide packing energy, three‐body energy, and solvation energy. From the testing of decoy recognition on a number of commonly used decoy sets, it is shown that the new potential function outperforms all known Cα‐based potentials and most other coarse‐grained ones that require more information than Cα positions. We hope that this potential function adds a new tool for protein structural modeling.
The leucine‐rich repeat (LRR) protein, CaLRR1, interacts with the hypersensitive induced reaction (HIR) protein, CaHIR1, and suppresses cell death induced by the CaHIR1 protein
Authors: JUNG HO WON , HWANG BYUNG KOOK
Published: June 2007

Leucine‐rich repeat proteins (LRRs) function in a number of signal transduction pathways via protein–protein interactions. The gene encoding a small protein of pepper, CaLRR1, is specifically induced upon pathogen challenge and treatment with pathogen‐associated molecular patterns (PAMPs). We identified a pepper hypersensitive induced reaction (CaHIR1) protein that interacts with the LRR domain of the CaLRR1 protein using yeast two‐hybrid screening. Ectopic expression of the pepper CaHIR1 gene induces cell death in tobacco and Arabidopsis, indicating that the CaHIR1 protein may be a positive regulator of HR‐like cell death. Because transformation is very difficult in pepper plants, we over‐expressed CaLRR1 and CaHIR1 in Arabidopsis to determine cellular functions of the two genes. The over‐expression of the CaHIR1 gene, but not the CaLRR1 gene, in transgenic Arabidopsis confers disease resistance in response to Pseudomonas syringae infection, accompanied by the strong expression of PR genes, the accumulation of both salicylic acid and H2O2, and K+ efflux in plant cells. In Arabidopsis and tobacco plants over‐expressing both CaHIR1 and CaLRR1, the CaLRR1 protein suppresses not only CaHIR1‐induced cell death, but also PR gene expression elicited by CaHIR1 via its association with HIR protein. We propose that the CaLRR1 protein functions as a novel negative regulator of CaHIR1‐mediated cell death responses in plants.
Comparative transcript profiling by cDNA‐AFLP reveals similar patterns of Avr4/Cf‐4‐ and Avr9/Cf‐9‐dependent defence gene expression
Authors: HONG WEI , XU YOU‐PING , ZHENG ZHONG , CAO JIA‐SHU , CAI XIN‐ZHONG
Published: June 2007

Tomato Cf genes confer resistance to the fungal pathogen Cladosporium fulvum. Although the Cf‐4 and Cf‐9 proteins are very similar, the Cf‐4‐ and Cf‐9‐dependent hypersensitive responses (HRs) are distinct in cell death pattern, intensity and sensitivity to environmental conditions. To investigate the mechanism leading to these differences, comparative transcript profiling of Avr4/Cf‐4‐ and Avr9/Cf‐9‐dependent defence gene expression was performed. To do this, cDNA‐AFLP analysis was conducted on Avr/Cf tomato seedlings undergoing early HR. Both Avr4/Cf‐4 and Avr9/Cf‐9 signalling elicited the same spectrum of genes, referred to here as Avr/Cf‐elicited (ACE) genes. Of approximately 25 000 transcript‐derived fragments (TDFs), 367 (1.5%) showed significant differential expression between HR+ and HR− seedlings (either Avr4/Cf‐4‐ or Avr9/Cf‐9‐dependent). However, 42.8% of the ACE TDFs (157/367 in total) showed quantitatively different expression in the two types of HR+ seedlings. The majority of these (135/157, 86.0%) displayed significantly greater differential expression (either induced or repressed) in Avr4/Cf‐4 HR+ seedlings than in Avr9/Cf‐9 HR+ seedlings. Our results are consistent with the previous observation that Avr4/Cf‐4‐dependent HR is more severe than Avr9/Cf‐9‐dependent HR, and indicate that the distinction between Avr4/Cf‐4‐ and Avr9/Cf‐9‐dependent HR is most probably a result of events upstream of the defence responses. Sequencing of 189 ACE fragments identified genes associated with: defence and resistance (33.3%), signal transduction (7.4%), HR and cell death (5.3%), transcriptional regulation and post‐transcriptional modification (4.3%). Expression data revealed that defence response, respiration and biological oxidation are strongly induced while photosynthesis is severely repressed in the HR+ seedlings.
Surface complex structures modelled with quantum chemical calculations: carbonate, phosphate, sulphate, arsenate and arsenite
Authors: Kubicki J. D. , Kwon K. D. , Paul K. W. , Sparks D. L.
Published: June 2007

Hybrid molecular orbital/density functional theory (MO/DFT) calculations on molecular clusters were used to model infrared (IR) vibrational frequencies and interatomic distances obtained via extended X‐ray absorption fine structure (EXAFS) spectroscopy. Molecular clusters were found to provide good agreement with experimental observations for the oxyanions carbonate, phosphate, sulphate, arsenate and arsenite. The results show a consistent tendency to form bidentate bridging surface complexes at low pH, but the protonation and hydration states play a significant role in the results obtained from calculation as various protonation states of monodentate surface complexes are also predicted to be stable as pH increases (i.e. the number of H+ ions in the model are decreased). A method for estimating the Gibbs free energy of adsorption (ΔGads) is discussed to complement the comparisons of experimental and theoretical spectroscopic parameters. Calculated ΔGads values were consistent with the interpretations based on modelling observed spectra.
Parents of children with haemophilia – a transforming experience
Authors: BEETON K. , NEAL D. , WATSON T. , LEE C. A.
Published: June 2007

Summary.  Owing to the improvements in the management of haemophilia, children with severe haemophilia in the United Kingdom have very different experiences of their condition compared with many adults’ early experiences of haemophilia. However, haemophilia can still have physical and social effects which can impact on the quality of life, not only for a child who has the condition, but also for their parents. The purpose of this study was to undertake a qualitative exploration of the impact of haemophilia on parents. The participants included 12 parents of children with severe haemophilia who took part in interviews or focus groups. Four major themes emerged from the data which were initial experiences, managing the condition, engaging with others and developing mastery. The findings highlighted the importance of evaluating parents’ experiences. Parents are deeply affected by their child’s condition and their lives are transformed by the experiences of living with a child with haemophilia. Parents’ responses are influenced by how well the child manages the disorder and the difficulties they experience. Further studies are required in order to develop a more complete understanding of the impact of haemophilia on parent’s lives.
Absence of cyclin‐D2 and Bcl‐2 expression within the germinal centre type of diffuse large B‐cell lymphoma identifies a very good prognostic subgroup of patients
Authors: Amen F , Horncastle D , Elderfield K , Banham A H , Bower M , Macdonald D , Kanfer E , Naresh K N
Published: June 2007

Aims:  To validate and improve the existing algorithm (proposed by Hans et al.) to classify diffuse large B‐cell lymphoma (DLBCL).

Methods and results:  Tissue microarrays constructed from 81 patients with DLBCL were studied by immunohistochemistry for expression of CD10, Bcl‐6, MUM1, Bcl‐2, cyclin‐D2, FOXP1 and PKC‐γ proteins. Cases were classified as either germinal centre B‐like (GCB) or non‐GC according to Hans et al. An alternative classification was also employed, in which cases positive for either CD10 or Bcl‐6 were considered as a GC subgroup and cases negative for both CD10 and Bcl‐6 were considered as a non‐GC subgroup. GC was further subdivided into favourable GC (negative for both Bcl‐2 and cyclin‐D2) and unfavourable GC (positive for either Bcl‐2 or cyclin‐D2). The 5‐year event‐free survival (EFS) amongst patients classified as favourable GC versus ‘others’ was 49.5% and 7.3%, respectively (log rank P < 0.0001). Similarly, the 5‐year overall survival (OS) amongst patients classified as favourable GC versus ‘others’ was 58.6% and 13.7%, respectively (log rank P = 0.0001). The difference in survival was independent of the international prognostic index.

Conclusions:  In this group of patients the risk stratification based on the new algorithm was better than that proposed by Hans et al.
Characteristic Ber‐EP4 and EMA expression in sebaceoma is immunohistochemically distinct from basal cell carcinoma
Authors: Fan Y S , Carr R A , Sanders D S A , Smith A P , Lazar A J F , Calonje E
Published: June 2007

Aims:  There is considerable overlap between the histological features of sebaceoma and basal cell carcinoma (BCC). The distinction between these two tumours is important due to the often more locally aggressive nature of BCC and the association of sebaceoma with the Muir–Torre syndrome. The aim of this study was to describe the immunohistochemical reactivity of the cells in sebaceoma to Ber‐EP4 and epithelial membrane antigen (EMA) and investigate the utility of this panel to differentiate sebaceoma from basal cell carcinoma.

Methods and results:  Immunohistochemistry of 25 sebaceomas for Ber‐EP4 and EMA revealed unequivocal negative expression of Ber‐EP4 in 24 of 25 sebaceomas. A single case exhibited focal weak Ber‐EP4 staining, predominantly in mature sebocytes and in < 10% of the tumour cells. EMA was not expressed in the germinative cells of sebaceoma, but was expressed strongly in approximately 50% of mature sebocytes in all cases and highlighted the cytoplasmic vacuoles. We reviewed the immunoreactivity of 51 cases of nodular BCCs and found moderate or strong BerEP4 expression in all cases with never less than 20% of the tumour staining. Expression of EMA was uncommon in BCC (moderate or strong in 8%) and was confined to keratotic or squamoid areas.

Conclusion:  The use of Ber‐EP4 in combination with EMA, both widely used immunomarkers in histopathology, is a helpful aid in distinguishing sebaceoma from nodular BCC.
Prognostic indicators of gastric carcinoma confined to the muscularis propria
Authors: Son H , Song S , Rhee J C
Published: June 2007

Aims:  Gastric carcinoma confined to the muscularis propria (MPGC) is considered an intermediate‐stage carcinoma. A method of discriminating between more favourable and less favourable prognostic groups of this entity is critically needed in dealing with this heterogeneous disease. The aim of this study was to examine the correlation between survival of patients with MPGC and its various clinicopathological parameters.

Methods and results:  Various clinicopathological parameters were studied in 171 tissue samples including: macroscopic appearance, size, age, sex, stage, invasion depth, Lauren and Ming classifications, extent, lymphatic emboli and nodal metastasis. Tumours macroscopically resembling early gastric cancers, younger patient age, absence of lymphatic tumour emboli and lower stage were significantly associated with better prognosis of MPGC by univariate analysis. Tumours macroscopically resembling early gastric cancers, younger patient age and Lauren's diffuse type were significantly associated with a better prognosis of MPGC by multivariate analysis.

Conclusions:  These indicators are practical parameters for predicting patient prognosis in clinical practice. The description of these parameters should be carefully noted in the final report and pathologists should evaluate the macroscopic appearance of MPGC.
Relationship between burnout and occupational stress among nurses in China
Authors: Wu Siying , Zhu Wei , Wang Zhiming , Wang Mianzhen , Lan Yajia
Published: June 2007

Title. Relationship between burnout and occupational stress among nurses in China

Aim.  This article is a report of a study of occupational burnout among nurses in China.

Background.  Burnout is described as feelings of emotional exhaustion, depersonalization and reduced personal accomplishment. It is well‐known that burnout is a major problem for many professions. Nurses are considered to be particularly susceptible to this. Measuring burnout among nurses is important because their well‐being has implications for stability in the healthcare workforce and for the quality of care provided.

Method.  The sample consisted of 495 nurses from three provincial hospitals in China. The Maslach Burnout Inventory – General Survey (MBI‐GS) was used to measure burnout, and the Occupational Stress Inventory – Revised edition was used to measure two dimensions of occupational adjustment (occupational stress and coping resources). After statistical testing for validity and reliability of the MBI‐GS with nurses in China, participants’ scores were evaluated and analysed.

Results.  Scores for burnout of surgical and medical nurses were statistically significantly higher than those of other nurses (P < 0·05). Lower educational status was associated with lower professional efficacy, and younger nurses reported higher levels of burnout. The most significant predictors of emotional exhaustion were role overload, responsibility, role insufficiency and self‐care (P < 0·05). The most significant predictors of cynicism were role insufficiency, role boundary, responsibility and self‐care (P < 0·05). The most significant predictors of professional efficacy were role insufficiency, social support and rational/cognitive coping (P < 0·05).

Conclusion.  It is important to reduce occupational stress in nurses and to strengthen their coping resources to prevent burnout. This could be achieved with job redesign, modification of shiftwork systems, and by offering occupational health education.
Maternal Attachment Inventory: psychometric evaluation of the Korean version
Authors: Shin Hyunjeong , Kim Young Hee
Published: June 2007

Title. Maternal Attachment Inventory: psychometric evaluation of the Korean version

Aim.  This paper is a report of an assessment of the validity and reliability of the Korean language version of the Maternal Attachment Inventory.

Background.  Although the Maternal Attachment Inventory has been widely used to measure mother–infant attachment, no psychometric evaluation of the measure with a Korean population has been reported.

Method.  Data from 196 mothers within 6 weeks postpartum were collected during July to November 2003 and used to evaluate the validity and reliability of the Korean version of the Maternal Attachment Inventory. Validity was examined using exploratory factor analysis, item‐to‐subscale correlations, and correlations with other theoretically relevant variables (maternal foetal attachment and maternal sensitivity). For reliability testing, Cronbach's alpha coefficients, item analyses, and subscale‐to‐total correlations were examined.

Findings.  Factor analysis showed that the Korean version had three factors explaining 62·9% of the variance. Item‐to‐subscale correlation coefficients ranged from 0·49 to 0·91. Correlation coefficients between the Maternal Attachment Inventory and both maternal foetal attachment and maternal sensitivity ranged from 0·10 to 0·64. However, correlations between the third factor scores and both maternal foetal attachment scores and maternal sensitivity scores were not statistically significant. Cronbach's alpha coefficients ranged from 0·65 to 0·94. Correlation coefficients of the inter‐item analysis ranged from −0·01 to 0·87. Corrected item‐total correlation coefficients were 0·31–0·82. Subscale‐to‐total correlation coefficients of the Maternal Attachment Inventory ranged from 0·52 to 0·92.

Conclusion.  Most items of the Korean version of the Maternal Attachment Inventory were adequate for measuring mothers’ affectionate attachment. The instrument, however, exhibited weaknesses in the psychometric properties related to validity and reliability, particularly regarding the three items included in the third factor. More studies using factor analysis of the Maternal Attachment Inventory are needed.
Finite study areas and vital rates: sampling effects on estimates of spotted owl survival and population trends
Authors: ZIMMERMAN GUTHRIE S. , GUTIÉRREZ R.J. , LAHAYE WILLIAM S.
Published: June 2007

Evaluating the status of endangered wildlife depends upon well‐designed field studies. Finances and logistics often constrain field studies to finite (limited‐sized) areas where inductive inferences are needed to extrapolate results to populations. Although available quantitative techniques for analysing data are robust to many aspects of field investigations, few investigators assess the influence of their study area size on estimators of population parameters and subsequent inferences derived from those estimators.

We used mark–recapture to monitor an entire population of spotted owlsStrix occidentalisin the San Bernardino Mountains of southern California (2140 km2) for which we knew the approximate true rate of survival. We defined hypothetical study areas of varying size by subsampling the population in increments of five territories; we then estimated apparent survival and emigration for non‐juvenile and juvenile owls within each of these sample study areas to assess the influence of study area size on estimators of survival and population trends.

Estimated survival rates of juvenile spotted owls increased approximately fourfold from the smallest sample area to the largest (min = 0·08,SÊ = 0·03;max = 0·33,SÊ = 0·03). In contrast, estimates of apparent survival for non‐juvenile owls did not vary with study area size (rangenon‐juvenile = 0·80–0·82,SÊ = 0·01–0·03).

Juvenile emigration was extremely high in the smallest study area (juvenile = 0·77,SÊ = 0·09) and remained above 10% until > 62% of our study area (approximately 900 km2) was encompassed by a sample study area. Non‐juvenile owls had low annual emigration probabilities from all sample study area sizes (rangenon‐juvenile = 0·00–0·02).

Although estimates of λ (finite population growth rate) increased gradually from 0·828 to 0·903 as the subsample increased from 20 to 143 territories, these estimates were similar to the ‘true’ value.

Synthesis and applications.We provide direct estimates of the bias that sampling limited study areas has on emigration and mark–recapture estimators of survival. Our results demonstrate that permanent emigration from limited study areas can lead to underestimates of survival and population growth rates. In addition, our approach illustrates a technique for using multistate models to assess study design and estimator assumptions.
Developmental Expression of Key Steroidogenic Enzymes in the Brain of Protandrous Black Porgy Fish, Acanthopagrus schlegeli
Authors: Tomy S. , Wu G.‐C. , Huang H.‐R. , Dufour S. , Chang C.‐F.
Published: June 2007

In the present study, we tested the hypothesis that the brain of the black porgy fish, Acanthopagrus schlegeli, has the capacity for de novo steroidogenesis and that these neurosteroids may impact sex differentiation. Gonadal histology and Dmrt1 gene expression revealed that the fish were not sex differentiated until 155 dah (days after hatching). We further demonstrated the developmental expressions of the mRNAs encoding for four key neurosteroidogenic enzymes, namely, the cytochrome P450 side chain cleavage (CYP11A1), 3β‐hydroxysteroid dehydrogenase/Δ5‐Δ4 isomerase (3βHSD), cytochrome P450c17 (CYP17) and aromatase (CYP19b) in the brain at different post‐hatching developmental ages. The results indicated that steroidogenic genes are expressed in brain from the earliest sampling time, 60 dah. Quantitative real‐time polymerase chain reaction analysis demonstrated significantly higher expression levels of these enzymes at 120 dah compared to 60 dah in all the brain regions. However, the increase for 3βHSD was significant only in hypothalamus and midbrain, whereas it was significant only in forebrain and hypothalamus for CYP19b. A decline in mRNA levels were observed for all the genes at 155 dah except in midbrain for CYP11A1 and in hindbrain for CYP19b. Analysis of aromatase enzyme activity showed a significant increase in aromatase activity in the forebrain at 120 dah. Thus, the present study demonstrated for the first time an age‐ and/or region dependent expression of the mRNAs encoding the steroidogenic enzyme genes in the brain of black porgy. The presence of key steroidogenic enzymes as early as 60 dah, before gonadal sex differentiation, demonstrates that steroid biosynthetic capacity in brain precedes histological gonad differentiation. The mRNA transcripts of these genes showed a synchronous peak at 120 dah, suggesting that oestradiol may be locally formed in most parts of the brain. The study suggests an important role for brain aromatase in male black porgy brain sex differentiation, and considers the possibility of a role for this enzyme in neurogenesis.
Melatonin Modulates Spike Coding in the Rat Suprachiasmatic Nucleus
Authors: Inyushkin A. N. , Bhumbra G. S. , Gonzalez J. A. , Dyball R. E. J.
Published: June 2007

The effects of the application of melatonin in vitro on the electrophysiological activity of suprachiasmatic neurones were characterised using novel measures of coding based on the analysis of interspike intervals. Perfusion of 1 nM melatonin in vitro (n = 53) had no consistent effect on mean spike frequency (Wilcoxon's sign rank, z = −0.01, P = 0.989), but increased the irregularity of firing (Student's paired t‐test, t = −3.02, P = 0.004), as measured by the log interval entropy, and spike patterning (z = −3.43, P < 0.001), as measured by the mutual information between adjacent log intervals. Intracellular recordings in vitro in current clamp mode showed that 1 nM melatonin significantly hyperpolarised (n = 11, z = −2.35, P = 0.019) those cells that showed ‘rebound’ spikes upon termination of a hyperpolarising current pulse. Grouping all cells together (n = 27), melatonin application decreased the duration of the afterhyperpolarisation (z = −2.49, P = 0.013) and increased the amplitude of the depolarising afterpotential (z = −2.71, P = 0.007). The effects of melatonin seen in vitro from extracellular recordings on interspike interval coding were consistent with the changes in spike shape seen from intracellular recordings. A melatonin‐induced increase in the size of the depolarising afterpotential of suprachiasmatic cells might underlie the increased irregularity of spike firing seen during the subjective night time. The method of analysis demonstrated a difference in spike firing that is not revealed by frequency alone and is consistent with the presence of a melatonin‐induced depolarising current.
Morphological Evidence for Direct Interaction Between Gonadotrophin‐Releasing Hormone Neurones and Astroglial Cells in the Human Hypothalamus
Authors: Baroncini M. , Allet C. , Leroy D. , Beauvillain J.‐C. , Francke J.‐P. , Prevot V.
Published: June 2007

In rodents, there is compelling evidence indicating that dynamic cell‐to‐cell communications involving cross talk between astroglial cells (such as astrocytes and specialised ependymoglial cells known as tanycytes) and neurones are important in regulating the secretion of gonadotrophin‐releasing hormone (GnRH), the neurohormone that controls both sexual maturation and adult reproductive function. However, whether such astroglial cell–GnRH neurone interactions occur in the human brain is not known. In the present study, we used immunofluorescence to examine the anatomical relationship between GnRH neurones and glial cells within the hypothalamus of five women. Double‐staining experiments demonstrated the ensheathment of GnRH neurone perikarya by glial fibrillary acidic protein (GFAP)‐immunoreactive astrocyte processes in the periventricular zone of the tuberal region of the hypothalamus. GFAP immunoreactivity did not overlap that of GnRH at the GnRH neurone's projection site (i.e. the median eminence of the hypothalamus). Rather, human GnRH neuroendocrine fibres were found to be closely associated with vimentin or nestin‐immunopositive radial gial processes likely belonging to tanycytes. In line with these light microscopy data, ultrastructural examination of GnRH‐immunoreactive neurones showed numerous glial cells in direct apposition to pre‐embedding‐labelled GnRH cell bodies and/or dendrites in the infundibular nucleus, whereas postembedding immunogold‐labelled GnRH nerve terminals were often seen to be enwrapped by glial cell processes in the median eminence. GnRH nerve button were sometimes visualised in close proximity to fenestrated pituitary portal blood capillaries and/or evaginations of the basal lamina that delineate the pericapillary space. In summary, these data demonstrate that GnRH neurones morphologically interact with astrocytes and tanycytes in the human brain and provide evidence that glial cells may contribute physiologically to the process by which the neuroendocrine brain controls the function of GnRH neurones in humans.
Orexin Expression is Regulated by α‐Melanocyte‐Stimulating Hormone
Authors: López M. , Lage R. , Tung Y. C. L. , Challis B. G. , Varela L. , Virtue S. , O'Rahilly S. , Vidal‐Puig A. , Diéguez C. , Coll A. P.
Published: June 2007

The hypothalamic melanocortin system plays a fundamental role in the regulation of energy homeostasis. Orexins (hypocretins) are also involved in a diverse range of physiological processes, including food intake. Previous evidence has suggested that hypothalamic orexin expression may be influenced by the central melanocortin system. Here, we studied orexin mRNA levels in pro‐opiomelanocortin‐deficient (Pomc–/–) mice, a mouse model lacking all endogenously produced melanocortin peptides. Orexin expression in the lateral hypothalamus was significantly increased in corticosterone deficient Pomc–/– mice. Furthermore, when circulating glucocorticoids were restored to levels within the physiological range, orexin expression remained elevated. However, i.c.v. administration of the melanocortin α‐melanocyte‐stimulating hormone (MSH) to Pomc–/– mice reduced orexin expression back down to wild‐type levels. This was independent of the effects of α‐MSH on food intake because elevated orexin expression persisted in Pomc–/– mice pairfed to α‐MSH‐treated animals. These data indicate that α‐MSH may play a role in the regulation of orexin expression in Pomc–/–, with an elevation in orexin levels contributing to the hyperphagia seen in these animals.
Sex Differences in K+‐Evoked Striatal Dopamine Output from Superfused Striatal Tissue Fragments of Reserpine‐Treated CD‐1 Mice
Authors: Ji J. , McDermott J. L. , Dluzen D. E.
Published: June 2007

Reserpine inhibits vesicular monoamine transporter‐2 (VMAT‐2) function and thereby impairs vesicular dopamine (DA) storage within nerve terminals. The present report compared the effects of reserpine treatment upon the striatal dopaminergic system in male and female mice as a means to assess potential sex differences in VMAT‐2/DA storage function. After treatment with reserpine, male mice showed significantly greater striatal DA concentrations and K+‐evoked DA output from the striatum compared to females. By contrast, no statistically significant sex differences were observed in methamphetamine‐evoked DA output in reserpine‐treated mice. These results demonstrate a clear sex difference in the striatal dopaminergic responses to reserpine and suggest that females possess a more active VMAT‐2/DA storage capacity, as indicated by the greater degree of deficits observed when VMAT‐2/DA storage function is inhibited by reserpine. Such findings have important implications for understanding some of the bases for sex differences in neurotoxicity and neurodegeneration of the nigrostriatal dopaminergic system.
Genetic reconstruction of the population dynamics of a carnivorous marsupial (Antechinus flavipes) in response to floods
Authors: LADA HANIA , MAC NALLY RALPH , TAYLOR ANDREA C.
Published: June 2007

Human activities such as regulating river flows, logging and removing fallen timber adversely affect floodplain ecosystems around the world. Studies of the dynamics of floodplain‐dwelling populations will help to understand the effects of altered flood regimes and to manage and restore floodplains. The yellow‐footed antechinus (Antechinus flavipes) is the only small, native, carnivorous mammal (Marsupialia) on many degraded floodplains in south‐eastern Australia, where its abundance appears to increase with proximity to floods, which is partly due to enhanced survival (as inferred from increased abundance of second‐year females). We analysed population genetic patterns and maternity among samples collected following the period of postnatal dispersal, in the years preceding and following planned floods, at different distances from flood locations along the Murray River. Our genic and genotypic analyses of mitochondrial DNA (mtDNA) control region haplotypes and 11 microsatellite loci demonstrated high immigration rates into sites in close proximity to floods. All sampled males emigrated from their natal sites to points of capture, while some females were philopatric. There were high rates of dispersal of males among all sites within a partially flooded forest, while females dispersed more to locations closest to inundations rather than to distant places. These results suggest that environmental flows are beneficial to antechinus both by enhancing adult survival and promoting dispersal of females.
Bioluminescence in Vibrio fischeri is controlled by the redox‐responsive regulator ArcA
Authors: Bose Jeffrey L. , Kim Unmi , Bartkowski Wojciech , Gunsalus Robert P. , Overley Ashley M. , Lyell Noreen L. , Visick Karen L. , Stabb Eric V.
Published: June 2007

Bioluminescence generated by the Vibrio fischeri Lux system consumes oxygen and reducing power, and it has been proposed that cells use this to counteract either oxidative stress or the accumulation of excess reductant. These models predict that lux expression should respond to redox conditions; yet no redox‐responsive regulator of lux is known. We found that the luxICDABEG operon responsible for bioluminescence is repressed by the ArcAB system, which is activated under reducing conditions. Consistent with a role for ArcAB in connecting redox monitoring to lux regulation, adding reductant decreased luminescence in an arc‐dependent manner. ArcA binds to and regulates transcription from the luxICDABEG promoter, and it represses luminescence both in the bright strain MJ1 and in ES114, an isolate from the squid Euprymna scolopes that is not visibly luminescent in culture. In ES114, deleting arcA increased luminescence in culture ∼500‐fold to visible levels comparable to that of symbiotic cells. ArcA did not repress symbiotic luminescence, but by 48 h after inoculation, ArcA did contribute to colonization competitiveness. We hypothesize that inactivation of ArcA in response to oxidative stress during initial colonization derepresses luxICDABEG, but that ArcAB actively regulates other metabolic pathways in the more reduced environment of an established infection.
DegU co‐ordinates multicellular behaviour exhibited by Bacillus subtilis
Authors: Verhamme Daniël T. , Kiley Taryn B. , Stanley‐Wall Nicola R.
Published: June 2007

Unicellular organisms use a variety of mechanisms to co‐ordinate activity within a community and accomplish complex multicellular processes. Because some of the processes that are exhibited by one species can be physiologically incompatible, it raises the question of how entry into these different pathways is regulated. In the Gram‐positive bacterium Bacillus subtilis, genetic competence, swarming motility, biofilm formation, complex colony architecture and protease production are all regulated by the response regulator DegU. DegU appears to integrate environmental signals and co‐ordinate multicellular behaviours that are subsequently manifested at different levels of DegU phosphorylation. Data are presented which indicate that: (i) swarming motility is activated by very low levels of DegU∼P that can be generated independently from its cognate sensor kinase DegS; (ii) complex colony architecture is activated by low levels of DegU∼P that are produced in a DegS‐dependent manner to activate transcription of yvcA, a novel gene required for complex colony architecture; and (iii) high levels of DegU∼P inhibit complex colony architecture and swarming motility but are required prior to the activation of exoprotease production. A model is proposed to explain why such a system may have evolved within B. subtilis to control these multicellular processes through a single regulator.
Solutions for Initial‐Boundary‐Value Problems Representing Gravity Currents Arising from Variable Inflow
Authors: Pascal J. P. , Moodie T. B. , Antar N. , D'Alessio S. J. D.
Published: June 2007

In this article, we report on theoretical and numerical studies of models for suddenly initiated variable inflow gravity currents in rectangular geometry. These gravity currents enter a lighter, deep ambient fluid at rest at a time‐dependent rate from behind a partially opened lock gate and their subsequent dynamics is modeled in the buoyancy‐inertia regime using ½‐layer shallow water theory. The resistance to flow that is exerted by the ambient fluid on the gravity current is accounted for by a front condition which involves a non‐dimensional parameter that can be chosen in accordance with experimental observations. Flow filament theory is used to arrive at expressions for the variable inflow velocity under the assumptions of an inviscid and incompressible fluid moving through an opening of fixed area which is suddenly opened under a lock gate at one end of a large rectangular tank. The fluid in the lock is subjected to a (possibly) time varying pressure applied uniformly over its surface and the finite movement of the free surface is accounted for. Finding this time‐dependent inflow velocity, which will then serve as a boundary condition for the solution of the shallow‐water equations, involves solving forced non‐linear ordinary differential equations and the form of this velocity equation and its attendant solutions will, in general, rule out finding self‐similar solutions for the shallow‐water equations. The existence of self‐similar solutions requires that the gravity currents have volumes proportional to t α, where α≥ 0 and t is the time elapsed from initiation of the flow. This condition requires a point source of fluid with very special properties for which both the area of the gap and the inflow velocity must vary in a related and prescribed time‐dependent manner in order to preserve self‐similarity. These specialized self‐similar solutions are employed here as a check on our numerical approach. In the more natural cases that are treated here in which fluids flow through an opening of fixed dimensions in a container an extra dimensional parameter is introduced thereby ruling out self‐similarity of the solutions for the shallow‐water equations so that the previous analytical approaches to the variable inflow problem, involving the use of phase‐plane analysis, will be inapplicable. The models developed and analyzed here are expected to provide a first step in the study of situations in which a storage container is suddenly ruptured allowing a heavy fluid to debouch at a variable rate through a fixed opening over level terrain. They also can be adapted to the study of other situations where variable inflow gravity currents arise such as, for example, flows of fresh water from spring run‐off into lakes and fjords, flows from volcanoes and magma chambers, discharges from locks and flash floods.
Triiodothyronine Modulates Differential Homing of Recent Thymic Emigrants to Peripheral Lymphoid Organs
Authors: Ribeiro‐Carvalho M. M. , Smaniotto S. , Neves‐dos‐Santos S. , Mouço T. , Savino W. , Mello‐Coelho V.
Published: June 2007

The functioning of the immune system partially relies on T‐cell exportation from the thymus, the major site of T‐cell differentiation. Although the molecular mechanisms governing this process begin to be elucidated, it is not clear if thyroid hormones can alter the homing of recent thymic emigrants (RTE) to peripheral lymphoid organs. Herein, we investigated whether triiodothyronine (T3) could influence the homing of thymus‐derived T cells. For that we used intrathymic injection of T3 in combination with fluorescein isothiocyanate (FITC) to trace, 16 h later, FITC+ cells, termed RTE, in peripheral lymphoid organs. We observed that T3 stimulated thymocyte export, increasing the frequency of CD4+ RTE and CD8+ RTE in the subcutaneous and mesenteric lymph nodes. By contrast, the relative numbers of CD4+ RTE in the spleen were decreased. T3 also changed the differential distribution pattern of CD4+ RTE, and to a lesser extent CD8+ RTE in the peripheral lymphoid organs. Moreover, the expression of extracellular matrix (ECM) components, such as laminin and fibronectin, which are known to be involved in T‐cell migration, increased in the lymph nodes but not in the spleen following intrathymic T3 treatment. In conclusion, our data correspond to the first demonstration that in vivo treatment with thyroid hormone stimulates thymic T‐cell homing and T‐cell distribution in peripheral lymphoid organs.
Effect of Insulin‐like Growth Factor‐I on Leishmania amazonensis Promastigote Arginase Activation and Reciprocal Inhibition of NOS2 Pathway in Macrophage In vitro
Authors: Vendrame C. M. V. , Carvalho M. D. T. , Rios F. J. O. , Manuli E. R. , Petitto‐Assis F. , Goto H.
Published: June 2007

We showed previously that insulin‐like growth factor (IGF)‐I induces an exacerbation of the lesion development in experimental cutaneous leishmaniasis favouring parasite growth within host macrophages. Here we studied the effect of IGF‐I in vitro in BALB/c mouse peritoneal macrophages infected with stationary phase Leishmania amazonensis promastigotes. IGF‐I was used to pre‐incubate either macrophage or parasite before infection of the macrophages or adding it at the start of the Leishmania–macrophage culture and maintaining it throughout the experimental period. Independent of stimulation protocol, IGF‐I induced significantly increased parasite growth within macrophages. Arginase activation considered as a key factor in Leishmania growth was studied, and its expression and activity were increased in Leishmania‐infected macrophages but significantly more in infected cells upon IGF‐I stimulus, an effect specifically inhibited by NOHA. Arginase known to be present on Leishmania was also studied, and its expression and activity were seen in the absence of any stimulus but significantly increased after 5 min of incubation with IGF‐I. In addition, Leishmania was pre‐incubated with NOHA for 5 min, washed, then macrophages infected observing a significantly reduced parasite burden in both IGF‐I‐stimulated and non‐stimulated macrophages. Reciprocal decrease in the nitric oxide (NO) level and inhibition of nitric oxide synthase (NOS2) expression were also observed in IGF‐I‐stimulated infected macrophages. Our data strongly suggest that IGF‐I induces preferential expression and activation of Leishmania promastigote arginase, contributes to the alternative activation of macrophages in the context of innate immunity and interferes with NOS pathway in infected macrophages probably as a reciprocal effect.
IFN‐γ, But Not Nitric Oxide or Specific IgG, is Essential for the In vivo Control of Low‐virulence Sylvio X10/4 Trypanosoma cruzi Parasites
Authors: Marinho C. R. F. , Nuñez‐Apaza L. N. , Martins‐Santos R. , Bastos K. R. B. , Bombeiro A. L. , Bucci D. Z. , Sardinha L. R. , Lima M. R. D. , Álvarez J. M.
Published: June 2007

Highly virulent strains of Trypanosoma cruzi are frequently used as murine models of Chagas’ disease. However, these strains do not fully represent the spectrum of parasites involved in the human infection. In this paper, we analysed parasitaemia, mortality, tissue pathology and parasite‐specific IgG serum levels in immune‐deficient mice infected with Sylvio X10/4 parasites, a T. cruzi derived from a chagasic patient that yields very low parasitaemias and in C3H/HePAS mice induces a chronic cardiopathy resembling the human disease. IFN‐γ was identified as a crucial element for parasite control as its absence determined a drastic increase in parasitaemia, tissue parasitism, leukocyte infiltrates at the heart and striated muscles and mortality. The lack of IFN‐γ or IL‐12p40, a molecule shared by IL‐12 and IL‐23, also resulted in spinal cord lesions and a progressive paralysis syndrome. Whereas IgG2a was the main Ig isotype in infected C57BL/6 mice, IL‐12p40‐KO mice produced IgG2a and IgG1 and IFN‐γ‐KO mice produced only IgG1. The IFN‐γ‐protective effect was not essentially mediated by nitric oxide (NO), inasmuch as infected iNOS‐KO mice showed no parasitaemia and low tissue damage. Mice deficient in CD4+ or CD8+ T cells showed an intermediate phenotype with increased mortality and tissue pathology but no parasitaemia. Interestingly, CD28‐KO mice were unable to produce anti‐T. cruzi IgG antibodies but presented moderate tissue pathology and managed to control the infection. Thus, differently from infections with high virulence parasites, neither IgG, NO nor CD28‐mediated signalling are essential for the non‐sterile control of Sylvio X10/4 parasites.
Field geometry, petrography and geochemistry of a dolomitization front (Late Jurassic, central Lebanon)
Authors: NADER FADI H. , SWENNEN RUDY , ELLAM ROB M. , Immenhauser Adrian
Published: June 2007

This contribution describes the field geometry, petrography and geochemistry of a well‐exposed dolomitization front in Upper Jurassic carbonates, and attempts to highlight the sedimentological, structural and relative sea‐level controls on multiphase dolomitization and related diagenetic events. The data presented reflect the superposition of various diagenetic phases which have resulted in a single dolostone body, whose dimensions are well defined in the field. Local microbial intraclastic dolomites of Late Tithonian age accumulated in a hypersaline lagoon during relative sea‐level fall. These pre‐date beige hydrothermal dolostones (51 to 55 mol% CaCO3; δ18O: −9·3 to −4·0‰ V‐PDB; δ13C: −1·5 to +2·1‰ V‐PDB; 87Sr/86Sr: 0·70742; matrix porosity: ≈6%; Klinkenberg permeability: ≈0·5 mD), whose dolomitizing fluid circulated along faults and invaded the nearby facies. First, the burrows were dolomitized, then the bulk rocks, resulting in the investigated ‘tongue’‐shaped dolomite body. Upon Late Jurassic–Early Cretaceous uplift, near‐surface water percolated through – and altered – the underlying beige dolostones. This event was followed by a ferroan dolomite cement phase, which occurred during further burial. This contribution, featuring a well‐defined geometric pattern of a dolomitization front with a large petrographic and geochemical data set, may also serve as a case study illustrating the complexity of superimposed diagenetic processes which have to be taken into account in modelling exercises of multiphase hydrothermal dolomitization.
The origin and glaciodynamic significance of sandstone ridge networks from the Hirnantian glaciation of the Djado Basin (Niger)
Authors: DENIS MICHAËL , BUONCRISTIANI JEAN‐FRANÇOIS , KONATÉ MOUSSA , GUIRAUD MICHEL , Eyles Nick
Published: June 2007

The Djado Basin (Niger) was located beneath the inner part of the Late Ordovician ice sheet. The Felar‐Felar Formation consists mainly of glaciomarine deposits, associated with the major ice sheet recession within the glaciation, and is bounded by two glacial unconformities. Structures corresponding to sandstone ridges are found within the Felar‐Felar Formation. Sandstone ridges are several metres high, about 10 m wide and hundreds of metres long. These structures are organized in extensive anastomosed to sub‐polygonal networks. The association of sandstone ridge networks with the later glacial unconformity and with other glacial evidence suggests sub‐glacial conditions for their origin. Sandstone ridge sedimentological characteristics indicate that sandstone ridges result from the scouring of the Felar‐Felar Formation by sub‐glacial, turbulent and pressurized meltwater; then sub‐glacial cavities were infilled with sand derived from glacial abrasion. Sandstone ridge networks are comparable with tunnel channels and document unusual drainage structures of the inner part of the palaeo‐ice sheet.