bluuebunny/crossref_metadata_2025 huggingface dataset:
The electronic structure of free water clusters probed by Auger electron spectroscopy
Authors: Öhrwall G. , Fink R. F. , Tchaplyguine M. , Ojamäe L. , Lundwall M. , Marinho R. R. T. , Naves de Brito A. , Sorensen S. L. , Gisselbrecht M. , Feifel R. , Rander T. , Lindblad A. , Schulz J. , Sæthre L. J. , Mårtensson N. , Svensson S. , Björneholm O.
Published: August 2005

( H 2 O ) N clusters generated in a supersonic expansion source with N∼1000 were core ionized by synchrotron radiation, giving rise to core-level photoelectron and Auger electron spectra (AES), free from charging effects. The AES is interpreted as being intermediate between the molecular and solid water spectra showing broadened bands as well as a significant shoulder at high kinetic energy. Qualitative considerations as well as ab initio calculations explain this shoulder to be due to delocalized final states in which the two valence holes are mostly located at different water molecules. The ab initio calculations show that valence hole configurations with both valence holes at the core-ionized water molecule are admixed to these final states and give rise to their intensity in the AES. Density-functional investigations of model systems for the doubly ionized final states—the water dimer and a 20-molecule water cluster—were performed to analyze the localization of the two valence holes in the electronic ground states. Whereas these holes are preferentially located at the same water molecule in the dimer, they are delocalized in the cluster showing a preference of the holes for surface molecules. The calculated double-ionization potential of the cluster (22.1eV) is in reasonable agreement with the low-energy limit of the delocalized hole shoulder in the AES.
Vibrational energy relaxation of azulene studied by the transient grating method. II. Liquid solvents
Authors: Kimura Y. , Yamamoto Y. , Terazima M.
Published: August 2005

The vibrational energy dissipation process of the ground-state azulene in various liquids has been studied by the transient grating spectroscopy. The acoustic signal produced by the temperature rise of the solvent due to the vibrational energy relaxation of azulene was monitored. The temperature rise-time constant of the solvent has been determined both by the fitting of the acoustic signal to a theoretical model equation and by the analysis of the acoustic peak shift. We found that the temperature rise-time constants determined by the transient grating method in various solvents are larger than the vibrational energy relaxation time constants determined by the transient absorption measurement [D. Schwarzer, J. Troe, M. Votsmeier, and M. Zerezke, J. Chem. Phys. 105, 3121 (1996)]. The difference is explained by different energy dissipation pathways from azulene to solvent; vibrational-vibrational (V-V) energy transfer and vibrational-translational (V-T) energy transfer. The contribution of the V-V energy transfer is estimated in various liquid solvents from the difference between the temperature rise time and vibrational energy relaxation time, and the solvent V-T relaxation time.
Effects of the bias enhanced nucleation hot-filament chemical-vapor deposition parameters on diamond nucleation on iridium
Authors: Arnault J. C. , Schull G. , Polini R. , Mermoux M. , Faerber J.
Published: August 2005

The effects of the bias current density and the filament-to-substrate distance on the nucleation of diamond on iridium buffer layers were investigated in a hot-filament chemical-vapor deposition (HFCVD) reactor. The nucleation density increased by several orders of magnitude with the raise of the bias current density. According to high-resolution field-emission gun scanning electron microscopy observation, diamond nuclei formed during bias-enhanced nucleation (BEN) did not show any preferred oriented growth. Moreover, the first-nearest-neighbor distance distribution was consistent with a random nucleation mechanism. This occurrence suggested that the diffusion of carbon species at the substrate surface was not the predominant mechanism taking place during BEN in the HFCVD process. This fact was attributed to the formation of a graphitic layer prior to diamond nucleation. We also observed that the reduction of the filament sample distance during BEN was helpful for diamond growth. This nucleation behavior was different from the one previously reported in the case of BEN-microwave chemical-vapor deposition experiments on iridium and has been tentatively explained by taking into account the specific properties and limitations of the HFCVD technique.
Highly strained InGaAs∕GaAs multiple quantum-wells for laser applications in the 1200–1300 nm wavelength regime
Authors: Sundgren P. , Berggren J. , Goldman P. , Hammar M.
Published: August 2005

We report on metalorganic vapor-phase epitaxy growth optimization and properties of highly strained InGaAs∕GaAs quantum-well (QW) structures with emission wavelength beyond 1200 nm. It is observed that a sufficiently high V/III ratio in combination with low growth temperature is critical for preserved layer integrity when increasing the strain. Multiple QWs with up to five wells are realized without any degradation in photoluminescence intensity or broad-area laser performance at an emission wavelength of 1240 nm with threshold current density below 70A∕cm2 per well.
Oxygen defects and Fermi level location in metal-hafnium oxide-silicon structures
Authors: Lim Daeyoung , Haight Richard , Copel Matthew , Cartier Eduard
Published: August 2005

We describe an in situ method for measuring the band bending of Si substrates in complex metal-oxide-semiconductor systems using femtosecond pump-probe photoelectron spectroscopy. Following deposition of metal layers (Pt, Re, or Re oxide) on the high-k dielectric HfO2, measurement of the band bending in the underlying Si provides a direct determination of the location of the Fermi level within the Si band gap at the Si-dielectric interface. Changes in the Fermi level with post-deposition anneals and oxygen exposure were correlated with valence and core photoelectron spectroscopy as well as capacitance-voltage measurements. These studies illuminate the roles that gate metal work function, modified by metal induced gap states and defects within the oxide, such as oxygen vacancies, play in defining the location of the Fermi level in metal-oxide-semiconductor structures.
Influence of dislocations on photoluminescence of InGaN∕GaN multiple quantum wells
Authors: Zhang J. C. , Jiang D. S. , Sun Q. , Wang J. F. , Wang Y. T. , Liu J. P. , Chen J. , Jin R. Q. , Zhu J. J. , Yang H. , Dai T. , Jia Q. J.
Published: August 2005

The influence of dislocations on photoluminescence (PL) of InGaN∕GaN multiple quantum wells (MQWs) is investigated by triple-axis x-ray diffraction (TAXRD), transmission electron microscopy (TEM), and PL spectra. The ω scan of every satellite peak by TAXRD is adopted to evaluate the mean screw and edge dislocation densities in MQWs. The results show that dislocations can lead to a reduction of the PL-integrated intensity of InGaN∕GaN MQWs under certain conditions, with edge dislocations playing a decisive role. Additionally, the dislocations can broaden the PL peak, but the effect becomes evident only under the condition when the interface roughness is relatively low.
Ultrafast biexciton dynamics in a ZnO thin film
Authors: Jen Fang-Yi , Lu Yen-Cheng , Chen Cheng-Yen , Wang Hsiang-Chen , Yang C. C. , Zhang Bao-ping , Segawa Yusaburo
Published: August 2005

The emission lines of biexciton and donor-bound biexciton are observed in a high-quality ZnO thin-film sample with time-resolved photoluminescence (TRPL) measurement. The TRPL intensity profiles reveal the formation sequence of various types of exciton. After free excitons are first generated, part of them is trapped by neutral donors to form donor-bound excitons. The other part contributes to the generation of biexcitons through free exciton scattering. Next, a donor-bound biexciton is generated through the trapping of a biexciton or two free excitons by a neutral donor or the trapping of a free exciton by a donor-bound exciton. Except donor-bound exciton, the relaxations of all other exciton states show two decay stages. Either the increasing or decreasing trends of the calibrated decay times in increasing the excitation power are well interpreted with a four-level model.
A priori
prediction of adsorption isotherm parameters and chromatographic behavior in ion-exchange systems
Authors: Ladiwala Asif , Rege Kaushal , Breneman Curtis M. , Cramer Steven M.
Published: August 2005

The
a priori
prediction of protein adsorption behavior has been a long-standing goal in several fields. In the present work, property-modeling techniques have been used for the prediction of protein adsorption thermodynamics in ion-exchange systems directly from crystal structure. Quantitative structure–property relationship models of protein isotherm parameters and Gibbs free energy changes in ion-exchange systems were generated by using a support vector machine regression technique. The predictive ability of the models was demonstrated for two test-set proteins not included in the model training set. Molecular descriptors selected during model generation were examined to gain insights into the important physicochemical factors influencing stoichiometry, equilibrium, steric effects, and binding affinity in protein ion-exchange systems. The
a priori
prediction of protein isotherm parameters can have direct implications for various ion-exchange processes. As proof of concept, a multiscale modeling approach was used for predicting the chromatographic separation of a test set of proteins using the isotherm parameters obtained from the quantitative structure–property relationship models. The simulated column separation showed good agreement with the experimental data. The ability to predict chromatographic behavior of proteins directly from their crystal structures may have significant implications for a range of biotechnology processes.
Genetic reprogramming of tumor cells by zinc finger transcription factors
Authors: Blancafort Pilar , Chen Emily I. , Gonzalez Beatriz , Bergquist Sharon , Zijlstra Andries , Guthy Daniel , Brachat Arndt , Brakenhoff Ruud H. , Quigley James P. , Erdmann Dirk , Barbas Carlos F.
Published: August 2005

Cancer arises by the accumulation of genetic alterations in DNA leading to aberrant gene transcription. Expression-profiling studies have correlated genomewide expression signatures with malignancy. However, functional analysis elucidating the contribution and synergy of genes in specific cancer cell phenotypes remains a formidable obstacle. Herein, we describe an alternative genetic approach for identification of genes involved in tumor progression by using a library of zinc finger artificial transcription factors (ATFs) and functional screening of tumor cells as a source of genetic plasticity and clonal selection. We isolated a six-zinc finger transcriptional activator (TF 20-VP, TF 20 containing the VP64 activator domain) that acts to reprogram a drug-sensitive, poorly invasive, and nonmetastatic cell line into a cell line with a drug-resistant, highly invasive, and metastatic phenotype. Differential expression profiles of cells expressing TF 20-VP followed by functional studies, both
in vitro
and in animal models, revealed that invasion and metastasis requires coregulation of multiple target genes. Significantly, the E48 antigen, associated with poor metastasis-free survival in head and neck cancer, was identified as one specific target of TF 20-VP. We have shown phenotypic modulation of tumor cell behavior by E48 expression, including enhanced cell migration
in vitro
and tumor cell dissemination
in vivo
. This study demonstrates the use of ATFs to identify the group of genes that cooperate during tumor progression. By coregulating multiple targets, ATFs can be used as master genetic switches to reprogram and modulate complex neoplastic phenotypes.
Activation of the plant plasma membrane H
+
-ATPase by phosphorylation and binding of 14-3-3 proteins converts a dimer into a hexamer
Authors: Kanczewska Justyna , Marco Sergio , Vandermeeren Caroline , Maudoux Olivier , Rigaud Jean-Louis , Boutry Marc
Published: August 2005

Plant plasma membrane H
+
-ATPases (PMAs) can be activated by phosphorylation of their penultimate residue (a Thr) and the subsequent binding of regulatory 14-3-3 proteins. Although 14-3-3 proteins usually exist as dimers and can bind two targets, the
in vivo
effects of their binding on the quaternary structure of H
+
-ATPases have never been examined. To address this question, we used a
Nicotiana tabacum
cell line expressing the
Nicotiana plumbaginifolia
PMA2 isoform with a 6-His tag. The purified PMA2 was mainly nonphosphorylated and 14-3-3-free, and it was shown by blue native gel electrophoresis and chemical cross-linking to exist as a dimer. Fusicoccin treatment of the cells resulted in a dramatic increase in Thr phosphorylation, 14-3-3 binding, and
in vivo
and
in vitro
ATPase activity, as well as in the conversion of the dimer into a larger, possibly hexameric, complex. PMA2 phosphorylation and 14-3-3 binding were observed also when cells in stationary growth phase were metabolically activated by transfer to fresh medium. When expressed in yeast, PMA2 was also phosphorylated and formed a complex with 14-3-3 proteins without requiring fusicoccin; no complex was observed when phosphorylation was prevented by mutagenesis. Single-particle analysis by cryoelectron microscopy showed that the PMA2–14-3-3 complex is a wheel-like structure with a 6-fold symmetry, suggesting that the activated complex consists of six H
+
-ATPase molecules and six 14-3-3 molecules.
Polarizable molecules in the vibrational spectroscopy of water
Authors: Harder Edward , Eaves Joel D. , Tokmakoff Andrei , Berne B. J.
Published: August 2005

We examine the role of electronic polarizability in water on short (tens of femtoseconds), intermediate (hundreds of femtoseconds), and long (≈1 ps) time scales by comparing molecular dynamics results to experimental data for vibrational spectroscopy of HOD in liquid D2O. Because the OH absorption frequency is sensitive to the details of the atomic forces experienced in the liquid, our results provide important quantitative comparisons for several popular empirical water potentials. When compared with their fixed-charge counterparts, the polarizable models give similar slower long time constants for the decay of vibrational correlations and reorientational motion that is in better agreement with experiments. Polarizable potentials yield qualitatively dissimilar predictions for frequency fluctuations and transition dipole moment fluctuations at equilibrium. Models that confine the polarizability to the plane of the molecule (i.e., TIP4P–FQ) overestimate the width of the distribution describing frequency fluctuations by more than a factor of two. These models also underestimate the amplitude of the hydrogen-bond stretch at 170 cm–1. A potential that has both an out-of-plane polarization and fluctuating charges, POL5–TZ, compares best with experiments. We interpret our findings in terms of microscopic dynamics and make suggestions that may improve the quality of emerging polarizable force fields for water.
Bovine papillomavirus E7 transformation function correlates with cellular p600 protein binding
Authors: DeMasi Joseph , Huh Kyung-Won , Nakatani Yoshihiro , Münger Karl , Howley Peter M.
Published: August 2005

The E7 oncoprotein of bovine papillomavirus type 1 (BPV-1) is required for the full transformation activity of the virus. However, the mechanism by which E7 contributes to cellular transformation is unknown. To address this question, we used the proteomic approach of tandem affinity purification to identify cellular proteins that are in complex with E7, and identified the 600-kDa protein, p600, as a binding partner of E7. The ability of E7 to complex with p600 correlated with its ability to enhance anchorage independence of BPV-1 E6-expressing cells. Furthermore, E7 mutant proteins impaired in their ability to bind p600 were transformation defective. Additionally, knockdown of p600 reduced transformation of cells expressing both BPV-1 E6 and E7, as well as E6 alone, suggesting that the ability of E7 to transformed cells is mediated, at least in part, through its ability to bind p600. These data complement work that shows that HPV16 E7 also interacts with p600, and that this interaction correlates with the ability of HPV16 E7 to transform cells. These studies thus identify p600 as a shared target of the E7 proteins of multiple papillomaviruses.
Modeste and Mignon: Balzac rewrites Goethe
Authors: Cave Terence
Published: August 2005

Amid the many literary intertexts of Balzac's
Modeste Mignon
(1844), the works of Goethe play a key role. Modeste's first name contains a coded reference to
Torquato Tasso
, while her family name is borrowed from the Mignon of
Wilhelm Meisters Lehrjahre.
Because Modeste is in many ways quite unlike Mignon, this latter reference has generally been regarded as marginal, but it can be shown that Balzac consciously plays off the
Bildungsroman
of his poetic but in the end solid and capable heroine against Goethe's ill-fated personification of lyrical poetry. Central to this parallel is the scene in which Modeste improvises a setting of her favourite poem by the poet she thinks she is in love with: unusually, the score (composed at Balzac's request by Daniel Auber) is printed consecutively with the narrative. This song transposes into a new literary, musical and social context Mignon's celebrated ‘Kennst du das Land?’.
Modeste Mignon
thus appears as both a specifically French mutation of the Mignon story and an ironic commentary on its Romantic implications.
The experiences of voluntary career change in 30‐somethings and implications for guidance
Authors: Wise Amelia Jane , Millward Lynne J.
Published: August 2005

Purpose

The purpose of the study was to discover the key psychological issues involved in voluntary career change in 30‐somethings, with implications for career theory and guidance.

Design/methodology/approach

A qualitative methodology was employed. Data gathering was by means of semi‐structured interviews and interpretation used interpretative phenomenological analysis. A sensemaking perspective within a constructivist framework defined the research.

Findings

Three types of themes were generated from the participant interviews. The first relates to issues of continuity and discontinuity during the change process, the second deals with participant's values directing the change, and the final theme covers the influence of context on the change process. The implications these themes have for contemporary meanings of career are discussed together with suggestions for guidance.

Research limitations/implications

Findings only reflect views at a point in time. A recommendation for future longitudinal research is made. The effect of the researcher is acknowledged in the sensemaking process.

Practical implications

A number of revisions to traditional career theory are identified and several career guidance implications.

Originality/value

This research is unique in addressing specific issues relating to the 30‐something age‐group and is topical in dealing with the phenomena of autonomous career change among this group. The use of a phenomenological perspective is scarce in the study of career change and provides a highly personal insight that furthers our understanding of the meaning of career. This is of particular value to career theorists and career counsellors.
Characterization and enzymatic degradation of Sup35NM, a yeast prion‐like protein
Authors: Chen Ching‐Ying , Rojanatavorn Kawan , Clark A. Clay , Shih Jason C.H.
Published: August 2005

Transmissible spongiform encephalopathies (TSEs) are believed to be caused by an unconventional infectious agent, the prion protein. The pathogenic and infectious form of prion protein, PrPSc, is able to aggregate and form amyloid fibrils, very stable and resistant to most disinfecting processes and common proteases. Under specific conditions, PrPSc in bovine spongiform encephalopathy (BSE) brain tissue was found degradable by a bacterial keratinase and some other proteases. Since this disease‐causing prion is infectious and dangerous to work with, a model or surrogate protein that is safe is needed for the in vitro degradation study. Here a nonpathogenic yeast prion‐like protein, Sup35NM, cloned and overexpressed in E. coli, was purified and characterized for this purpose. Aggregation and deaggregation of Sup35NM were examined by electron microscopy, gel electrophoresis, Congo red binding, fluorescence, and Western blotting. The degradation of Sup35NM aggregates by keratinase and proteinase K under various conditions was studied and compared. These results will be of value in understanding the mechanism and optimization of the degradation process.
Nuclear transfer of perchloric acid–soluble protein by endoplasmic reticulum stressors
Authors: Kanouchi Hiroaki , Matsumoto Mitsuharu , Taga Masaki , Yamada Koji , Oka Tatsuzo , Toné Shigenobu , Minatogawa Yohsuke
Published: August 2005

Perchloric acid–soluble protein (PSP) is highly conserved during evolution from bacteria to mammals. Although PSP has been recognized as an inhibitor of translation and proliferation in vitro, its precise biological role has not yet been elucidated. Since we previously found similar distributions for PSP and the endoplasmic reticulum (ER) and Golgi complex, the intracellular distribution of PSP was analyzed in more detail. Immunofluorescence studies indicated that PSP co‐localized with the ER and Golgi complex, since the distribution pattern of PSP was well matched to both of these organelles. An immunoelectron microscopic study revealed PSP was located not only in the cytosol but also on the surface of the outer ER membrane. Since PSP was present on the ER, we speculated that it may be associated with ER function. Therefore, we analyzed whether or not the ER stress response, which is one of the ER functions, affected PSP expression. The results showed that various ER stressors (thapsigargin, A23187, tunicamycin, brefeldin A, and cisplatin) provoked a dramatic change in the localization of PSP from outside of the nucleus to inside the nucleus within 3 h. Moreover, the ER stressors induced PSP expression. These results suggest that PSP is involved in the cellular response to ER stressors, and that the change in localization of PSP from the ER to the nucleus may be associated with ER stress responses.
Identifying psychosocial problems among youth: factors associated with youth agreement on a positive parent‐completed PSC‐17
Authors: Duke N. , Ireland M. , Borowsky I. W.
Published: August 2005

Background  The choice of informant is a critical piece in the identification of psychosocial problems in youth. While many behavioural measures have been adapted to include information from multiple sources, in the case of parents and youth, poor agreement has been found. Our study purpose was to identify youth and parent factors associated with whether the youth agrees with a positive parent‐completed screen of youth psychosocial problems.

Methods  Parents of youth aged 10–15 years who were seen for a medical visit at eight clinics completed the 17‐item Pediatric Symptom Checklist (PSC‐17). Youth scoring positive on the screen and their parents/guardians were interviewed by telephone after the visit (n = 145). We conducted bivariate and multivariate analyses to identify parent characteristics and child factors associated with whether the youth agrees with the positive parent‐completed screen.

Results  Fifty per cent of youth participants agreed with their parent on a positive parent‐completed PSC‐17 based on their completion of the Y‐PSC‐17 as a self‐report measure. Youth who reported a positive Y‐PSC‐17 in agreement with their parent were twice as likely to meet diagnostic cut‐offs on sub‐scales of anxiety/depression and aggression on the Child Behaviour Checklist (P < 0.01 and P < 0.05 respectively), reported lower parent–child connectedness (P < 0.01) and their parents reported more anger/frustration (P < 0.05) than youth who disagreed with the positive parent‐completed screen. Most of these associations remained significant when controlling for the other factors and demographic characteristics in multivariate analysis.

Conclusions  Findings indicate that when the youth agrees with a positive parent‐completed PSC‐17, there is higher parent frustration, lower parent–child connectedness, and the youth is more likely to have a diagnosis of an emotional or behavioural disorder. Thus, when possible, the use of both parent and youth as informants provides necessary information in formulating a comprehensive treatment strategy to address the psychosocial needs of youth.
The penC mutation conferring antibiotic resistance in Neisseria gonorrhoeae arises from a mutation in the PilQ secretin that interferes with multimer stability
Authors: Zhao Shuqing , Tobiason Deborah M. , Hu Mei , Seifert H. Steven , Nicholas Robert A.
Published: August 2005

The penC resistance gene was previously characterized in an FA19 penA mtrR penB gonococcal strain (PR100) as a spontaneous mutation that increased resistance to penicillin and tetracycline. We show here that antibiotic resistance mediated by penC is the result of a Glu‐666 to Lys missense mutation in the pilQ  gene  that  interferes  with  the  formation  of the SDS‐resistant high‐molecular‐mass PilQ secretin complex, disrupts piliation and decreases transformation frequency by 50‐fold. Deletion of pilQ in PR100 confers the same level of antibiotic resistance as the penC mutation, but increased resistance was  observed  only  in  strains  containing  the mtrR and penB resistance determinants. Site‐saturation mutagenesis of Glu‐666 revealed that only acidic or amidated amino acids at this position preserved PilQ function. Consistent with early studies suggesting the importance of cysteine residues for stability of the PilQ multimer, mutation of either of the two cysteine residues in FA19 PilQ led to a similar phenotype as penC: increased antibiotic resistance, loss of piliation, intermediate levels of transformation competence and absence of SDS‐resistant PilQ oligomers. These data show that a functional secretin complex can enhance the entry of antibiotics into the cell and suggest that the PilQ oligomer forms a pore in the outer membrane through which antibiotics diffuse into the periplasm.
Secretion of YscP from Yersinia enterocolitica is essential to control the length of the injectisome needle but not to change the type III secretion substrate specificity
Authors: Agrain Céline , Sorg Isabel , Paroz Cécile , Cornelis Guy R.
Published: August 2005

The length of the needle of the Yersinia Ysc injectisome is determined by a protein called YscP. This protein, which acts both as a molecular ruler and as a substrate‐specificity switch for type III secretion is itself secreted by the injectisome. In this report, we address the question why YscP is secreted. By a systematic deletion analysis and by fusing different parts of the molecule to the adenylate cyclase reporter, we identified two independent secretion signals. One of them is encompassed within the 35 N‐terminal residues while the second one spans residues 97–137. These two signals are functionally different from Yop secretion signals. When both secretion signals were removed, Yops could still be secreted but the needle length control was lost. YscP possessing only one signal did not control needle length properly but the control was improved when more YscP was produced and secreted. YscP deprived of both signals could not control length, even when overproduced. We conclude from this that YscP needs to be secreted to exert its length control function but not its substrate‐specificity switch function.
A master regulator σB governs osmotic and oxidative response as well as differentiation via a network of sigma factors in Streptomyces coelicolor
Authors: Lee Eun‐Jin , Karoonuthaisiri Nitsara , Kim Hyo‐Sub , Park Joo‐Hong , Cha Chang‐Jun , Kao Camilla M. , Roe Jung‐Hye
Published: August 2005

The differentiating bacterium Streptomyces coelicolor harbours some 66 sigma factors, which support its complex life cycle. σB, a functional homologue of σS from Escherichia coli, controls both osmoprotection and differentiation in S. coelicolor A3(2). Microarray analysis revealed σB‐dependent induction of more than 280 genes by 0.2 M KCl. These genes encode several sigma factors, oxidative defence proteins, chaperones, systems to provide osmolytes, cysteine, mycothiol, and gas vesicle. σB controlled induction of itself and its two paralogues (σL and σM) in a hierarchical order of σB→σL→σM, as revealed by S1 mapping and Western blot analyses. The phenotype of each sigma mutant suggested a sequential action in morphological differentiation; σB in forming aerial mycelium, σL in forming spores and σM for efficient sporulation. σB was also responsible for the increase in cysteine and mycothiol, the major thiol buffer in actinomycetes, upon osmotic shock, revealing an overlap between protections against osmotic and oxidative stresses. Proteins in sigB mutant were more oxidized (carbonylated) than the wild type. These results support a hypothesis that σB serves as a master regulator that triggers other related sigma factors in a cascade, and thus regulates differentiation and osmotic and oxidative response in S. coelicolor.
The 5′ untranslated region‐mediated enhancement of intracellular listeriolysin O production is required for Listeria monocytogenes pathogenicity
Authors: Shen Aimee , Higgins Darren E.
Published: August 2005

Listeriolysin O (LLO) and ActA are essential virulence determinants for Listeria monocytogenes pathogenesis. Transcription of actA and hly, encoding LLO, is regulated by PrfA and increases dramatically during intracellular infection. The 5′ untranslated regions (5′ UTRs) of actA and prfA have been shown to upregulate expression of their respective gene products. Here, we demonstrate that the hly 5′ UTR plays a critical role in regulating expression of LLO during intracellular infection. Deletion of the hly 5′ UTR, while retaining the hly ribosome binding site, had a moderate effect on LLO production during growth in broth culture, yet resulted in a marked decrease in LLO levels during intracellular infection. The diminished level of LLO resulted in a significant defect in bacterial cell‐to‐cell spread during intracellular infection and a 10‐fold reduction in virulence during in vivo infection of mice. Insertion of the hly 5′ UTR sequence between a heterologous promoter and reporter gene sequences indicated that the hly 5′ UTR functions independent of PrfA‐mediated transcription and can enhance expression of cis‐associated genes through a mechanism that appears to act at both a post‐transcriptional and translational level. The ability of the hly 5′ UTR to increase gene expression can be exploited to achieve PrfA‐independent complementation of virulence genes and high‐level expression of single copy heterologous genes in L. monocytogenes.
Transcriptional regulation of the circadian clock operon kaiBC by upstream regions in cyanobacteria
Authors: Kutsuna Shinsuke , Nakahira Yoichi , Katayama Mitsunori , Ishiura Masahiro , Kondo Takao
Published: August 2005

In the cyanobacterium, Synechococcus elongatus PCC 7942, the kaiBC operon is upregulated by the KaiA protein and downregulated by the KaiC protein to generate circadian oscillation. We investigated the regulation of kaiBC transcription. A primer extension and deletion analyses of the upstream region mapped the sufficient promoter region (SPR) to base pairs −55 to +1 (the transcription start site, TSS) and identified a constitutive negative regulatory region upstream of the SPR (base pairs −897 to −56) that extended into the coding sequence of kaiA. Base‐pair substitution within the SPR identified a sequence from −52 to −28 that was the essential element for transcription. Most of the examined sequences drove rhythmic expression of a luxAB reporter that was similar to the expression driven by the kaiBC promoter (PkaiBC) and responded to the overexpression of kaiA or kaiC, even in a promoter activity range of 1–8000%. These results indicate that circadian feedback regulation by KaiA and KaiC is addressed to a  global step preceding transcription driven by PkaiBC. However, increasing or decreasing the intrinsic activity of PkaiBC greatly affected the rhythm, suggesting that constitutive adjustment of PkaiBC activity by the sequences identified here is essential for the oscillator.
“As Our Muscles Get Softer, Our Missile Race Becomes Harder”: Cultural Citizenship and the “Muscle Gap”
Authors: OCA JEFFREY MONTEZ DE
Published: August 2005

Abstract  The “muscle gap” was a period of Cold War anxiety projected onto the bodies of young, white males that produced a discourse fixated on their perceived softness and openness to communist penetration. The underlying anxiety was that youth would be unable to uphold the “national heritage” of expansionism built by the hard (white) men of previous generations. Looking at cultural citizenship as a process of subject‐formation sheds light on how a racial project can simultaneously be a gender project that (re)produces a racial‐gender order where whiteness and hegemonic masculinity are markers and repositories of superiority, domination, and privilege.