bluuebunny/crossref_metadata_2025 huggingface dataset:
CLASSIFICATION OF CHINESE RICE WINE WITH DIFFERENT MARKED AGES BASED ON NEAR INFRARED SPECTROSCOPY
Authors: YU HAIYAN , YING YIBIN , FU XIAPING , LU HUISHAN
Published: August 2006

The feasibility of near infrared (NIR) spectroscopy for discrimination between Chinese rice wine with different marked ages (1, 3 and 5 years) was presented in this research. NIR spectra were collected in transmission mode in the wavelength range of 800–2500 nm. Discriminant models were developed based on discriminant analysis (DA) together with raw and second derivative spectra. The calibration result for raw spectra was better than that for second derivative spectra. The percentage of samples correctly classified for raw and second derivative spectra was 100 and 78.4%, respectively. In validation analysis, the percentage of samples correctly classified was 94.4%. For 1‐, 3‐ and 5‐year‐old sample groups, the percentage of samples correctly classified was 88.3, 100 and 100%, respectively. The results demonstrated that NIR spectroscopy could be used as a rapid and reliable method for classification of Chinese rice wine with different marked ages.
INFLUENCE OF POSTHARVEST RIPENING ON CHANGES IN QUALITY AND VOLATILE COMPOUNDS OF “GOLDEN ORANGE” AND “GOLDEN LASA” SCAB‐RESISTANT APPLE CULTIVARS
Authors: RIZZOLO ANNA , GRASSI MAURIZIO , ZERBINI PAOLA ECCHER
Published: August 2006

Quality parameters at harvest, and color, ethylene production (EP) and headspace volatile production rates during postharvest ripening at 20C were investigated on two Golden Delicious‐like scab‐resistant apples (Golden Orange [GO] and Golden Lasa [GL]), and on the scab‐susceptible Golden Delicious clone B (G) cultivar. At harvest, quality parameters defined GO and GL apples as less mature than G ones, even if their skin color was yellower. With postharvest ripening, GO and GL apples showed lower EP, lower maximum total volatile production, and their skin color turned as yellow as G ones. When fully mature, GO and GL differed from G apples for organic acid, sugar and volatile compositions, which could explain the different sensory descriptions particular to these cultivars. Canonical discriminant analysis showed that the differences in volatile composition among the three cultivars became greater as the postharvest ripening process went on, and, only when fruits were still immature, could cultivars not be distinguished by using the aroma pattern.
Explaining Pro-Immigrant Sentiment in the U.S.: Social Class, Cosmopolitanism, and Perceptions of Immigrants
Authors: Haubert Jeannie , Fussell Elizabeth
Published: August 2006

In the U.S., research on attitudes toward immigrants generally focuses on anti-immigrant sentiment. Yet, the 1996 General Social Survey indicates that half the population believes that immigrants favorably impact the U.S. economy and culture. Using these data, we analyze theories of both pro- and anti-immigrant sentiment. While we find some support for two theories of intergroup competition, our most important finding connects a cosmopolitan worldview with favorable perceptions of immigrants. We find that cosmopolitans – people who are highly educated, in white-collar occupations, who have lived abroad, and who reject ethnocentrism – are significantly more pro-immigrant than people without these characteristics.
The Occupational Assimilation of Hispanic Immigrants in the U.S.: Evidence from Panel Data
Authors: Toussaint-Comeau Maude
Published: August 2006

This study focuses on the occupational component of the labor market adjustment of Hispanic immigrants. The author asks whether Hispanic immigrants assimilate with natives and what factors influence occupational attainment. The findings suggest that years since migration narrow the socioeconomic gap between Hispanic immigrants, their U.S.-born Hispanic counterparts, and non-Hispanic whites. The level of human capital affects the rate of occupational mobility and determines whether convergence occurs in the groups' socioeconomic occupational status. The occupational status of Hispanic immigrants with low human capital remains fairly stable and does not converge with that of non-Hispanic whites. However, those with high human capital experience upward occupational mobility. In part, their occupational assimilation is driven by the acquisition of human capital among younger Hispanic immigrants.
Second-Generation Pessimism and Optimism: How Chinese and Dominicans Understand Education and Mobility through Ethnic and Transnational Orientations
Authors: Louie Vivian
Published: August 2006

Higher education is crucial to the outcomes of the second generation. This paper explores the contrasting views second-generation Dominicans and Chinese have on their educational trajectories and social mobility. Drawing on interviews with individuals who have gone on to college, I argue that the optimism of the Dominicans emerges from their use of both transnational and ethnic/panethnic perspectives. The Dominicans believe they are doing better than peers in the Dominican Republic and in the United States. The pessimism of the Chinese can be traced to their use of ethnic/panethnic frames of comparison. The Chinese believe they are faring worse than peers in the United States. The results complicate segmented assimilation and transnationalism theories.
Regional Economic Performance and Net Migration Rates in Russia, 1993–2002
Authors: Gerber Theodore P.
Published: August 2006

Soviet legacies and uneven economic distress make post-Soviet Russia an especially interesting case in which to assess the effects of economic performance on regional net migration rates. Random effects models of net regional migration in 77 Russian regions from 1993 to 2002 indicate that mean wages and unemployment levels have substantial and predictable effects. These effects have several dynamic aspects: changes in mean wages (but not changes in unemployment) exert effects independently of wage and unemployment levels, the effect of unemployment decreases over time, and the effect of wage levels appears to increase. Overall, the results suggest a tendency toward regional equilibrium with respect to employment following the initial shock of Soviet collapse and market reforms, but continuing disequilibrium with respect to wages.
Migration and Development: Mexico and Turkey
Authors: Escobar Agustin , Hailbronner Kay , Martin Philip , Meza Liliana
Published: August 2006

Mexico and Turkey are among the world's leading labor-sending nations, with about 11 million Mexican-born and 3.5 million Turkish-born persons abroad in 2006. After two decades of uneven growth and job creation as well as persisting poverty and inequality, there are debates within both countries asking whether economic reforms have gone far enough to put the economy on a stable footing for sustained and equitable growth, or whether emigration (pressure) will continue. Some Mexicans are seeking to deepen North American Free Trade Agreement, while most Turks support entry into the European Union as a way of speeding economic growth.
Strangeness at the Gates: The Peculiar Politics of American Immigration
Authors: Ghandnoosh Nazgol , Waldinger Roger
Published: August 2006

Selecting by Origin: Ethnic Migration in the Liberal State. By Christian Joppke. Cambridge: Harvard University Press, 2005

Impossible Subjects: Illegal Aliens and the Making of Modern America. By Mae Ngai. Princeton: Princeton University Press, 2004

Dividing Lines: The Politics of Immigration Control in America. By Daniel Tichenor. Princeton: Princeton University Press, 2002.
The Primary Cilium as the Cell's Antenna: Signaling at a Sensory Organelle
Authors: Singla Veena , Reiter Jeremy F.
Published: August 2006

Almost every vertebrate cell has a specialized cell surface projection called a primary cilium. Although these structures were first described more than a century ago, the full scope of their functions remains poorly understood. Here, we review emerging evidence that in addition to their well-established roles in sight, smell, and mechanosensation, primary cilia are key participants in intercellular signaling. This new appreciation of primary cilia as cellular antennae that sense a wide variety of signals could help explain why ciliary defects underlie such a wide range of human disorders, including retinal degeneration, polycystic kidney disease, Bardet-Biedl syndrome, and neural tube defects.
Regulation of Sexual Development of
Plasmodium
by Translational Repression
Authors: Mair Gunnar R. , Braks Joanna A. M. , Garver Lindsey S. , Wiegant Joop C. A. G. , Hall Neil , Dirks Roeland W. , Khan Shahid M. , Dimopoulos George , Janse Chris J. , Waters Andrew P.
Published: August 2006

Translational repression of messenger RNAs (mRNAs) plays an important role in sexual differentiation and gametogenesis in multicellular eukaryotes. Translational repression and mRNA turnover were shown to influence stage-specific gene expression in the protozoan
Plasmodium
. The DDX6-class RNA helicase, DOZI (development of zygote inhibited), is found in a complex with mRNA species in cytoplasmic bodies of female, blood-stage gametocytes. These translationally repressed complexes are normally stored for translation after fertilization. Genetic disruption of
pbdozi
inhibits the formation of the ribonucleoprotein complexes, and instead, at least 370 transcripts are diverted to a degradation pathway.
Evidence for a Past High-Eccentricity Lunar Orbit
Authors: Garrick-Bethell Ian , Wisdom Jack , Zuber Maria T.
Published: August 2006

The large differences between the Moon's three principal moments of inertia have been a mystery since Laplace considered them in 1799. Here we present calculations that show how past high-eccentricity orbits can account for the moment differences, represented by the low-order lunar gravity field and libration parameters. One of our solutions is that the Moon may have once been in a 3:2 resonance of orbit period to spin period, similar to Mercury's present state. The possibility of past high-eccentricity orbits suggests a rich dynamical history and may influence our understanding of the early thermal evolution of the Moon.
Frames, Biases, and Rational Decision-Making in the Human Brain
Authors: De Martino Benedetto , Kumaran Dharshan , Seymour Ben , Dolan Raymond J.
Published: August 2006

Human choices are remarkably susceptible to the manner in which options are presented. This so-called “framing effect” represents a striking violation of standard economic accounts of human rationality, although its underlying neurobiology is not understood. We found that the framing effect was specifically associated with amygdala activity, suggesting a key role for an emotional system in mediating decision biases. Moreover, across individuals, orbital and medial prefrontal cortex activity predicted a reduced susceptibility to the framing effect. This finding highlights the importance of incorporating emotional processes within models of human choice and suggests how the brain may modulate the effect of these biasing influences to approximate rationality.
Imaging the Mott Insulator Shells by Using Atomic Clock Shifts
Authors: Campbell Gretchen K. , Mun Jongchul , Boyd Micah , Medley Patrick , Leanhardt Aaron E. , Marcassa Luis G. , Pritchard David E. , Ketterle Wolfgang
Published: August 2006

Microwave spectroscopy was used to probe the superfluid–Mott insulator transition of a Bose-Einstein condensate in a three-dimensional optical lattice. By using density-dependent transition frequency shifts, we were able to spectroscopically distinguish sites with different occupation numbers and to directly image sites with occupation numbers from one to five, revealing the shell structure of the Mott insulator phase. We used this spectroscopy to determine the onsite interaction and lifetime for individual shells.
Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic
Escherichia coli
Suggests that It Evolved from Closely Related ColV Virulence Plasmids
Authors: Johnson Timothy J. , Johnson Sara J. , Nolan Lisa K.
Published: August 2006

Avian pathogenic
Escherichia coli
(APEC), an extraintestinal pathogenic
E. coli
causing colibacillosis in birds, is responsible for significant economic losses for the poultry industry. Recently, we reported that the APEC pathotype was characterized by possession of a set of genes contained within a 94-kb cluster linked to a ColV plasmid, pAPEC-O2-ColV. These included
sitABCD
, genes of the aerobactin operon,
hlyF
,
iss
, genes of the salmochelin operon, and the 5′ end of
cvaB
of the ColV operon. However, the results of gene prevalence studies performed among APEC isolates revealed that these traits were not always linked to ColV plasmids. Here, we present the complete sequence of a 174-kb plasmid, pAPEC-O1-ColBM, which contains a putative virulence cluster similar to that of pAPEC-O2-ColV. These two F-type plasmids share remarkable similarity, except that they encode the production of different colicins; pAPEC-O2-ColV contains an intact ColV operon, and pAPEC-O1-ColBM encodes the colicins B and M. Interestingly, remnants of the ColV operon exist in pAPEC-O1-ColBM, hinting that ColBM-type plasmids may have evolved from ColV plasmids. Among APEC isolates, the prevalence of ColBM sequences helps account for the previously observed differences in prevalence between genes of the “conserved” portion of the putative virulence cluster of pAPEC-O2-ColV and those genes within its “variable” portion. These results, in conjunction with Southern blotting and probing of representative ColBM-positive strains, indicate that this “conserved” cluster of putative virulence genes is primarily linked to F-type virulence plasmids among the APEC isolates studied.
Membrane Vesicles: an Overlooked Component of the Matrices of Biofilms
Authors: Schooling Sarah R. , Beveridge Terry J.
Published: August 2006

The matrix helps define the architecture and infrastructure of biofilms and also contributes to their resilient nature. Although many studies continue to define the properties of both gram-positive and gram-negative bacterial biofilms, there is still much to learn, especially about how structural characteristics help bridge the gap between the chemistry and physical aspects of the matrix. Here, we show that membrane vesicles (MVs), structures derived from the outer membrane of gram-negative bacteria, are a common particulate feature of the matrix ofPseudomonas aeruginosabiofilms. Biofilms grown using different model systems and growth conditions were shown to contain MVs when thin sectioned for transmission electron microscopy, and mechanically disrupted biofilms revealed MVs in association with intercellular material. MVs were also isolated from biofilms by employing techniques for matrix isolation and a modified MV isolation protocol. Together these observations verified the presence and frequency of MVs and indicated that MVs were a definite component of the matrix. Characterization of planktonic and biofilm-derived MVs revealed quantitative and qualitative differences between the two and indicated functional roles, such as proteolytic activity and binding of antibiotics. The ubiquity of MVs was supported by observations of biofilms from a variety of natural environments outside the laboratory and established MVs as common biofilm constituents. MVs appear to be important and relatively unacknowledged particulate components of the matrix of gram-negative or mixed bacterial biofilms.
DksA Is Required for Growth Phase-Dependent Regulation, Growth Rate-Dependent Control, and Stringent Control offisExpression inEscherichia coli
Authors: Mallik Prabhat , Paul Brian J. , Rutherford Steven T. , Gourse Richard L. , Osuna Robert
Published: August 2006

DksA is a critical transcription factor inEscherichia colithat binds to RNA polymerase and potentiates control of rRNA promoters and certain amino acid promoters. Given the kinetic similarities between rRNA promoters and thefispromoter (Pfis), we investigated the possibility that DksA might also control transcription from Pfis. We show that the absence ofdksAextends transcription from Pfiswell into the late logarithmic and stationary growth phases, demonstrating the importance of DksA for growth phase-dependent regulation offis. We also show that transcription from Pfisincreases with steady-state growth rate and thatdksAis absolutely required for this regulation. In addition, both DksA and ppGpp are required for inhibition of Pfispromoter activity following amino acid starvation, and these factors act directly and synergistically to negatively control Pfistranscription in vitro. DksA decreases the half-life of the intrinsically short-livedfispromoter-RNA polymerase complex and increases its sensitivity to the concentration of CTP, the predominant initiating nucleotide triphosphate for this promoter. This work extends our understanding of the multiple factors controllingfisexpression and demonstrates the generality of the DksA requirement for regulation of kinetically similar promoters.
N-Acetyl-d-Glucosamine Induces the Expression of Multidrug Exporter Genes,mdtEF, via Catabolite Activation inEscherichia coli
Authors: Hirakawa Hidetada , Inazumi Yoshihiko , Senda Yasuko , Kobayashi Asuka , Hirata Takahiro , Nishino Kunihiko , Yamaguchi Akihito
Published: August 2006

The expression of MdtEF, a multidrug exporter inEscherichia coli, is positively controlled through multiple signaling pathways, but little is known about signals that induce MdtEF expression. In this study, we investigated compounds that induce the expression of themdtEFgenes and found that out of 20 drug exporter genes inE. coli, the expression ofmdtEFis greatly induced byN-acetyl-d-glucosamine (GlcNAc). The induction ofmdtEFby GlcNAc is not mediated by theevgSA,ydeO,gadX, andrpoSsignaling pathways that have been known to regulatemdtEFexpression. On the other hand, deletion of thenagEgene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction ofmdtEFby GlcNAc was also greatly inhibited by the addition of cyclic AMP (cAMP) and completely abolished upon deletion of the cAMP receptor protein gene (crp). Other PTS sugars, glucose andd-glucosamine, also inducedmdtEFgene expression. These results suggest thatmdtEFexpression is stimulated through catabolite control.
A Functional
dlt
Operon, Encoding Proteins Required for Incorporation of
d
-Alanine in Teichoic Acids in Gram-Positive Bacteria, Confers Resistance to Cationic Antimicrobial Peptides in
Streptococcus pneumoniae
Authors: Kovács Márta , Halfmann Alexander , Fedtke Iris , Heintz Manuel , Peschel Andreas , Vollmer Waldemar , Hakenbeck Regine , Brückner Reinhold
Published: August 2006

Streptococcus pneumoniae
is one of the few species within the group of low-G +C gram-positive bacteria reported to contain no
d
-alanine in teichoic acids, although the
dltABCD
operon encoding proteins responsible for
d
-alanylation is present in the genomes of two
S. pneumoniae
strains, the laboratory strain R6 and the clinical isolate TIGR4. The annotation of
dltA
in R6 predicts a protein,
d
-alanine-
d
-alanyl carrier protein ligase (Dcl), that is shorter at the amino terminus than all other Dcl proteins. Translation of
dltA
could also start upstream of the annotated TTG start codon at a GTG, resulting in the premature termination of
dltA
translation at a stop codon. Applying a novel integrative translation probe plasmid with
Escherichia coli
′
lacZ
as a reporter, we could demonstrate that
dltA
translation starts at the upstream GTG. Consequently,
S. pneumoniae
R6 is a
dltA
mutant, whereas
S. pneumoniae
D39, the parental strain of R6, and Rx, another derivative of D39, contained intact
dltA
genes. Repair of the stop codon in
dltA
of R6 and insertional inactivation of
dltA
in D39 and Rx yielded pairs of
dltA
-deficient and
dltA
-proficient strains. Subsequent phenotypic analysis showed that
dltA
inactivation resulted in enhanced sensitivity to the cationic antimicrobial peptides nisin and gallidermin, a phenotype fully consistent with those of
dltA
mutants of other gram-positive bacteria. In addition, mild alkaline hydrolysis of heat-inactivated whole cells released
d
-alanine from
dltA
-proficient strains, but not from
dltA
mutants. The results of our study suggest that, as in many other low-G+C gram-positive bacteria, teichoic acids of
S. pneumoniae
contain
d
-alanine residues in order to protect this human pathogen against the actions of cationic antimicrobial peptides.
Activity of
Rhodobacter sphaeroides
RpoH
II
, a Second Member of the Heat Shock Sigma Factor Family
Authors: Green Heather A. , Donohue Timothy J.
Published: August 2006

We have identified a second RpoH homolog, RpoH
II
, in the α-proteobacterium
Rhodobacter sphaeroides
. Primary amino acid sequence comparisons demonstrate that
R. sphaeroides
RpoH
II
belongs to a phylogenetically distinct group with RpoH orthologs from α-proteobacteria that contain two
rpoH
genes. Like its previously identified paralog, RpoH
I
, RpoH
II
is able to complement the temperature-sensitive phenotype of an
Escherichia coli
σ
32
(
rpoH
) mutant. In addition, we show that recombinant RpoH
I
and RpoH
II
each transcribe two
E. coli
σ
32
-dependent promoters (
rpoD
P
HS
and
dnaK
P1) when reconstituted with
E. coli
core RNA polymerase. We observed differences, however, in the ability of each sigma factor to recognize six
R. sphaeroides
promoters (
cycA
P1,
groESL
1
,
rpoD
P
HS
,
dnaK
P1,
hslO
, and
ecfE
), all of which resemble the
E. coli
σ
32
promoter consensus. While RpoH
I
reconstituted with
R. sphaeroides
core RNA polymerase transcribed all six promoters, RpoH
II
produced detectable transcripts from only four promoters (
cycA
P1,
groESL
1
,
hslO
, and
ecfE
). These results, in combination with previous work demonstrating that an RpoH
I
mutant mounts a typical heat shock response, suggest that while RpoH
I
and RpoH
II
have redundant roles in response to heat, they may also have roles in response to other environmental stresses.
Two GacA-Dependent Small RNAs Modulate the Quorum-Sensing Response in
Pseudomonas aeruginosa
Authors: Kay Elisabeth , Humair Bérénice , Dénervaud Valérie , Riedel Kathrin , Spahr Stéphanie , Eberl Leo , Valverde Claudio , Haas Dieter
Published: August 2006

In
Pseudomonas aeruginosa
, the GacS/GacA two-component system positively controls the quorum-sensing machinery and the expression of extracellular products via two small regulatory RNAs, RsmY and RsmZ. An
rsmY rsmZ
double mutant and a
gacA
mutant were similarly impaired in the synthesis of the quorum-sensing signal
N
-butanoyl-homoserine lactone, the disulfide bond-forming enzyme DsbA, and the exoproducts hydrogen cyanide, pyocyanin, elastase, chitinase (ChiC), and chitin-binding protein (CbpD). Both mutants showed increased swarming ability, azurin release, and early biofilm development.
Methionine Sulfoxide Reductase inHelicobacter pylori: Interaction with Methionine-Rich Proteins and Stress-Induced Expression
Authors: Alamuri Praveen , Maier Robert J.
Published: August 2006

The reductive repair of oxidized methionine residues performed by methionine sulfoxide reductase is important for the gastric pathogenHelicobacter pylorito maintain persistent stomach colonization. Methionine-containing proteins that are targeted for repair by Msr were identified from whole-cell extracts (after cells were exposed to O2stress) by using a coimmunoprecipitation approach. Proteins identified as Msr-interacting included catalase, GroEL, thioredoxin-1 (Trx1), and site-specific recombinase; with one exception (Trx1, the reductant for Msr) all these proteins have approximately twofold higher methionine (Met) content than other proteins. These Met-rich proteins were purified and were shown to individually form a cross-linked adduct with Msr. Catalase-specific activity in anmsrstrain was one-half that of the parent strain; this difference was only observed under oxidative stress conditions, and the activity was restored to nearly wild-type levels by adding Msr plus dithiothreitol tomsrstrain extracts. In agreement with the cross-linking study, pure Msr used Trx1 but not Trx2 as a reductant. Comparative structure modeling classified theH. pyloriMsr in class II within the MsrB family, like theNeisseriaenzymes. PureH. pylorienzyme reduced only the R isomer of methylp-tolyl-sulfoxide with an apparentKmof 4.1 mM for the substrate. Stress conditions (peroxide, peroxynitrite, and iron starvation) all caused approximately 3- to 3.5-fold transcriptional up-regulation ofmsr. Neither the O2level during growth nor the use of background regulatory mutants had a significant effect onmsrtranscription. Late log and stationary phase cultures had the highest Msr protein levels and specific activity.
Interaction of TonB with the Outer Membrane Receptor FpvA ofPseudomonas aeruginosa
Authors: Adams Hendrik , Zeder-Lutz Gabrielle , Schalk Isabelle , Pattus Franc , Celia Hervé
Published: August 2006

Pyoverdine-mediated iron uptake by the FpvA receptor in the outer membrane ofPseudomonas aeruginosais dependent on the inner membrane protein TonB1. This energy transducer couples the proton-electrochemical potential of the inner membrane to the transport event. To shed more light upon this process, a recombinant TonB1 protein lacking the N-terminal inner membrane anchor (TonBpp) was constructed. This protein was, after expression inEscherichia coli, purified from the soluble fraction of lysed cells by means of an N-terminal hexahistidine or glutathioneS-transferase (GST) tag. Purified GST-TonBppwas able to capture detergent-solubilized FpvA, regardless of the presence of pyoverdine or pyoverdine-Fe. Targeting of the TonB1 fragment to the periplasm ofP. aeruginosainhibited the transport of ferric pyoverdine by FpvA in vivo, indicating an interference with endogenous TonB1, presumably caused by competition for binding sites at the transporter or by formation of nonfunctional TonB heterodimers. Surface plasmon resonance experiments demonstrated that the FpvA-TonBppinteractions have apparent affinities in the micromolar range. The binding of pyoverdine or ferric pyoverdine to FpvA did not modulate this affinity. Apparently, the presence of either iron or pyoverdine is not essential for the formation of the FpvA-TonB complex in vitro.
Solution Structure of the Conserved Hypothetical Protein Rv2302 from
Mycobacterium tuberculosis
Authors: Buchko Garry W. , Kim Chang-Yub , Terwilliger Thomas C. , Kennedy Michael A.
Published: August 2006

The
Mycobacterium tuberculosis
protein Rv2302 (80 residues; molecular mass of 8.6 kDa) has been characterized using nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. While the biochemical function of Rv2302 is still unknown, recent microarray analyses show that Rv2302 is upregulated in response to starvation and overexpression of heat shock proteins and, consequently, may play a role in the biochemical processes associated with these events. Rv2302 is a monomer in solution as shown by size exclusion chromatography and NMR spectroscopy. CD spectroscopy suggests that Rv2302 partially unfolds upon heating and that this unfolding is reversible. Using NMR-based methods, the solution structure of Rv2302 was determined. The protein contains a five-strand, antiparallel β-sheet core with one C-terminal α-helix (A61 to A75) nestled against its side. Hydrophobic interactions between residues in the α-helix and β-strands 3 and 4 hold the α-helix near the β-sheet core. The electrostatic potential on the solvent-accessible surface is primarily negative with the exception of a positive arginine pocket composed of residues R18, R70, and R74. Steady-state {
1
H}-
15
N heteronuclear nuclear Overhauser effects indicate that the protein's core is rigid on the picosecond timescale. The absence of amide cross-peaks for residues G13 to H19 in the
1
H-
15
N heteronuclear single quantum correlation spectrum suggests that this region, a loop between β-strands 1 and 2, undergoes motion on the millisecond to microsecond timescale. Dali searches using the structure closest to the average structure do not identify any high similarities to any other known protein structure, suggesting that the structure of Rv2302 may represent a novel protein fold.
TrzN from
Arthrobacter aurescens
TC1 Is a Zinc Amidohydrolase
Authors: Shapir Nir , Pedersen Charlotte , Gil Omer , Strong Lisa , Seffernick Jennifer , Sadowsky Michael J. , Wackett Lawrence P.
Published: August 2006

TrzN, the broad-specificity triazine hydrolase from
Arthrobacter
and
Nocardioides
spp., is reportedly in the amidohydrolase superfamily of metalloenzymes, but previous studies suggested that a metal was not required for activity. To help resolve that conundrum, a double chaperone expression system was used to produce multimilligram quantities of functionally folded, recombinant TrzN. The TrzN obtained from
Escherichia coli
(
trzN
) cells cultured with increasing zinc in the growth medium showed corresponding increases in specific activity, and enzyme obtained from cells grown with 500 μM zinc showed maximum activity. Recombinant TrzN contained 1 mole of Zn per mole of TrzN subunit. Maximally active TrzN was not affected by supplementation with most metals nor by EDTA, consistent with previous observations (E. Topp, W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels, Appl. Environ. Microbiol. 66:3134-3141, 2000) which had led to the conclusion that TrzN is not a metalloenzyme. Fully active native TrzN showed a loss of greater than 90% of enzyme activity and bound zinc when treated with the metal chelator 8-hydroxyquinoline-5-sulfonic acid. While exogenously added zinc or cobalt restored activity to metal-depleted TrzN, cobalt supported lower activity than did zinc. Iron, manganese, nickel, and copper did not support TrzN activity. Both Zn- and Co-TrzN showed different relative activities with different
s
-triazine substrates. Co-TrzN showed a visible absorption spectrum characteristic of other members of the amidohydrolase superfamily replaced with cobalt.
Rippling Is a Predatory Behavior in
Myxococcus xanthus
Authors: Berleman James E. , Chumley Tatiana , Cheung Patricia , Kirby John R.
Published: August 2006

Cells of
Myxococcus xanthus
will, at times, organize their movement such that macroscopic traveling waves, termed ripples, are formed as groups of cells glide together on a solid surface. The reason for this behavior has long been a mystery, but we demonstrate here that rippling is a feeding behavior which occurs when
M. xanthus
cells make direct contact with either prey or large macromolecules. Rippling has been observed during two fundamentally distinct environmental conditions: (i) starvation-induced fruiting body development and (ii) predation of other organisms. Our results indicate that case (i) does not occur in all wild-type strains and is dependent on the intrinsic level of autolysis. Analysis of predatory rippling indicates that rippling behavior is inducible during predation on proteobacteria, gram-positive bacteria, yeast (such as Saccharomyces cerevisiae), and phage. Predatory efficiency decreases under genetic and physiological conditions in which rippling is inhibited. Rippling will also occur in the presence of purified macromolecules such as peptidoglycan, protein, and nucleic acid but does not occur in the presence of the respective monomeric components and also does not occur when the macromolecules are physically separated from
M. xanthus
cells. We conclude that rippling behavior is a mechanism utilized to efficiently consume nondiffusing growth substrates and that developmental rippling is a result of scavenging lysed cell debris.
Cross-Functionality of Nitrogenase Components NifH1 and VnfH inAnabaena variabilis
Authors: Pratte Brenda S. , Eplin Kim , Thiel Teresa
Published: August 2006

Anabaena variabilisfixes nitrogen under aerobic growth conditions in differentiated cells called heterocysts using either a Mo nitrogenase or a V nitrogenase. ThenifH1gene, which encodes the dinitrogenase reductase of the Mo nitrogenase that is expressed only in heterocysts, is cotranscribed withnifD1andnifK1, which together encode the Mo dinitrogenase. These genes were expressed in the presence or absence of molybdate or vanadate. ThevnfHgene, which encodes the dinitrogenase reductase of the V nitrogenase, was located about 23 kb fromvnfDGK, which encodes the V dinitrogenase; however, likevnfDGK,vnfHwas expressed only in the absence of molybdate, with or without vanadate. LikenifH1, thevnfHgene was expressed exclusively in heterocysts under either aerobic or anaerobic growth conditions and thus is under the control of developmental factors. ThevnfHmutant was able to grow diazotrophically using the V nitrogenase, because NifH1, which was also made in cells starved for molybdate, could substitute for VnfH. Under oxic conditions, thenifH1mutant grew in the absence of molybdate but not in its presence, using VnfH, while thenifH1 vnfHdouble mutant did not grow diazotrophically with or without molybdate or vanadate. AnifH1mutant that expressednifDKandvnfHbut notvnfDGKwas able to grow and fix nitrogen normally, indicating that VnfH could substitute for NifH in the Mo nitrogenase and that these dinitrogenase reductases are not involved in determining the metal specificity of the Mo nitrogenase or the V nitrogenase.
AI-3 Synthesis Is Not Dependent onluxSinEscherichia coli
Authors: Walters Matthew , Sircili Marcelo P. , Sperandio Vanessa
Published: August 2006

The quorum-sensing (QS) signal autoinducer-2 (AI-2) has been proposed to promote interspecies signaling in a broad range of bacterial species. AI-2 is spontaneously derived from 4,5-dihydroxy-2,3-pentanedione that, along with homocysteine, is produced by cleavage ofS-adenosylhomocysteine (SAH) andS-ribosylhomocysteine by the Pfs and LuxS enzymes. Numerous phenotypes have been attributed to AI-2 QS signaling usingluxSmutants. We have previously reported that theluxSmutation also affects the synthesis of the AI-3 autoinducer that activates enterohemorrhagicEscherichia colivirulence genes. Here we show that several species of bacteria synthesize AI-3, suggesting a possible role in interspecies bacterial communication. TheluxSmutation leaves the cell with only one pathway, involving oxaloacetate andl-glutamate, for de novo synthesis of homocysteine. The exclusive use of this pathway for homocysteine production appears to alter metabolism in theluxSmutant, leading to decreased levels of AI-3. The addition of aspartate and expression of an aromatic amino acid transporter, as well as a tyrosine-specific transporter, restored AI-3-dependent phenotypes in anluxSmutant. The defect in AI-3 production, but not in AI-2 production, in theluxSmutant was restored by expressing thePseudomonas aeruginosa S-adenosylhomocysteine hydrolase that synthesizes homocysteine directly from SAH. Furthermore, phenotype microarrays revealed that theluxSmutation caused numerous metabolic deficiencies, while AI-3 signaling had little effect on metabolism. This study examines how AI-3 production is affected by theluxSmutation and explores the roles of the LuxS/AI-2 system in metabolism and QS.
The
Bacillus subtilis
DivIVA Protein Has a Sporulation-Specific Proximity to Spo0J
Authors: Perry S. E. , Edwards D. H.
Published: August 2006

The
Bacillus subtilis
DivIVA protein controls the positioning of the division site and the relocation of the chromosome during sporulation. By performing coimmunoprecipitation experiments, we demonstrated that a myc-DivIVA protein is in proximity to FtsZ and MinD during vegetative growth and Spo0J during the first 120 min of sporulation.
Police deaths in New York and London during the twentieth century
Authors: Kyriacou D N , Monkkonen E H , Peek-Asa C , Lucke R E , Labbett S , Pearlman K S , Hutson H R
Published: August 2006

Objectives:To describe the incidences and causes of occupational police deaths in New York City in the United States and Greater London in the United Kingdom during the twentieth century. To assess the relation between overall societal violence and violence directed toward police officers in these metropolitan areas.

Design and setting:Ecological study of New York and London from 1900 through 1999.

Main outcome measures:Intentional and unintentional occupational police mortality rates for New York and London were estimated for each decade. The general population homicide rates of both New York and London were assessed for their correlation with their respective intentional occupational police mortality rates.

Results:During the 20th century, 585 police officers in New York and 160 police officers in London died while participating in law enforcement activities. New York had markedly greater intentional police mortality rates compared to London throughout most of the 20th century, but these differences decreased significantly by the end of the century. Intentional gunshot wounds comprised 290 police deaths in New York, but only 14 police deaths in London. In New York, gun shot wounds (both intentional and unintentional) accounted for more occupational police deaths (51.6%) than did all other injury mechanisms combined. In London, motor vehicle collision was the most common cause (47.5%) of occupational police death. There were no apparent correlations between the general population homicide rates and intentional police mortality rates in either New York (r2 = 0.05, 95% CI −0.77 to 0.81) or London (r2 = 0.34, 95% CI −0.61 to 0.89).

Conclusions:During the 20th century, both intentional and unintentional occupational police mortality rates were significantly greater in New York compared to London. These differences are likely from several socioeconomic, cultural, and occupational factors. The declines in police deaths in New York during the latter part of the 20th century indicate that at least some measures taken by the New York Police Department have been successful at significantly reducing the incidence of both intentional and unintentional police deaths.
Incidence and lifetime costs of injuries in the United States
Authors: Corso P , Finkelstein E , Miller T , Fiebelkorn I , Zaloshnja E
Published: August 2006

Background:Standardized methodologies for assessing economic burden of injury at the national or international level do not exist.

Objective:To measure national incidence, medical costs, and productivity losses of medically treated injuries using the most recent data available in the United States, as a case study for similarly developed countries undertaking economic burden analyses.

Method:The authors combined several data sets to estimate the incidence of fatal and non-fatal injuries in 2000. They computed unit medical and productivity costs and multiplied these costs by corresponding incidence estimates to yield total lifetime costs of injuries occurring in 2000.

Main outcome measures:Incidence, medical costs, productivity losses, and total costs for injuries stratified by age group, sex, and mechanism.

Results:More than 50 million Americans experienced a medically treated injury in 2000, resulting in lifetime costs of $406 billion; $80 billion for medical treatment and $326 billion for lost productivity. Males had a 20% higher rate of injury than females. Injuries resulting from falls or being struck by/against an object accounted for more than 44% of injuries. The rate of medically treated injuries declined by 15% from 1985 to 2000 in the US. For those aged 0–44, the incidence rate of injuries declined by more than 20%; while persons aged 75 and older experienced a 20% increase.

Conclusions:These national burden estimates provide unequivocal evidence of the large health and financial burden of injuries. This study can serve as a template for other countries or be used in intercountry comparisons.
Motorcycle injuries in a developing country and the vulnerability of riders, passengers, and pedestrians
Authors: Solagberu B A , Ofoegbu C K P , Nasir A A , Ogundipe O K , Adekanye A O , Abdur-Rahman L O
Published: August 2006

At a Nigerian university hospital, none of the motorcyclists who presented over a 12 month period had been wearing a helmet, and of the eight patients who died, seven had head injuries. Of the five collision types described, the rate of motorcycle-other vehicle collisions was highest at 40.6%, while the motorcycle-pedestrian rate was 23.4%. Measures to prevent these collisions might reduce overall crashes by 64%; in addition, helmet law should be enforced.
Lower rates of emergency department injury visits among Latino children in the USA: no association with health insurance
Authors: Simon T D , Bublitz Emsermann C , Dickinson L M , Hambidge S J
Published: August 2006

Background and objective:Latino children have lower rates of injury visits to emergency departments (EDs) than non-Latino white and African American children. This study tests the hypothesis that this difference reflects health insurance status.

Design:Secondary analysis.

Patients/setting:Children under 19 years of age visiting EDs in the USA, sampled in the National Hospital Ambulatory Medical Care Survey of EDs (NHAMCS-ED) from 1997 to 2001.

Main outcome measures:Rates of ED injury visits; ED injury visit rates by race/ethnicity stratified by health insurance and adjusted for other covariates; subtypes of injury visits; and procedures and hospital admissions by race/ethnicity.

Results:Injuries accounted for >56 million, or 40.5%, of total ED visits among pediatric patients. Injury visits occurred at lower rates for Latino children (9.9 per 100 person years) than non-Latino white and African American children (16.2 and 18.3, respectively), although total ED visit rates were similar. Regardless of health insurance status, Latino children had lower rates of injury visits than non-Latino white and African American children. Latino children had lower rates of the three major subtypes of injury visits (sports, accidental falls, struck by/between objects). Latino children had similar rates of procedures and hospital admissions to non-Latino white children.

Conclusions:Irrespective of their insurance status, Latino children have lower rates of ED injury visits in the USA than non-Latino white children. Possible reasons for this difference include different healthcare seeking behavior or different injury patterns by race/ethnicity, but not differences in health insurance status or barriers to accessing ED care.
Blurring the distinctions between on and off the job injuries: similarities and differences in circumstances
Authors: Smith G S , Sorock G S , Wellman H M , Courtney T K , Pransky G S
Published: August 2006

Objectives:To compare the causes of non-fatal work and non-work injuries and the places or environments where they occur. It has been suggested that many injuries may have similar etiologies on and off the job and thus involve some common prevention strategies. However lack of comparable data on work relatedness has prevented testing this proposition.

Methods:The National Health Interview Survey (NHIS) now collects information on the cause, location, and work relatedness of all medically attended injuries. National US estimates of non-fatal work and non-work injuries were compared by cause and place/location for working age adults (18–64 years).

Results:Overall 28.6% of injuries to working age adults were work related (37.5% among employed people). The causes and locations of many work and non-work injuries were similar. Falls, overexertion, and struck/caught by were leading causes for work and non-work injuries. Motor vehicle injuries were less likely to be work related (3.4% at workv19.5% non-work) and overexertion injuries more likely to be work related (27.1%v13.8%). Assaults were less than 1% of work injuries and 1.8% of non-work injuries. Both work and non-work injuries occurred in every location examined—including the home where 3.5% of injuries were work related.

Conclusions:Work and non-work injuries share many similarities suggesting opportunities to broaden injury prevention programs commonly restricted to one setting or the other. Comprehensive efforts to prevent both non-work and work injuries may result in considerable cost savings not only to society but also directly to employers, who incur much of the associated costs.
Bicycle helmet prevalence two years after the introduction of mandatory use legislation for under 18 year olds in Alberta, Canada
Authors: Hagel B E , Rizkallah J W , Lamy A , Belton K L , Jhangri G S , Cherry N , Rowe B H
Published: August 2006

Objective:To determine changes in helmet use in cyclists following the introduction of a bicycle helmet law for children under age 18.

Methods:Cyclists were observed by two independent observers from July to August 2004 (post-legislation) in Edmonton, Alberta. The data were compared with a similar survey completed at the same locations and days in July to August 2000 (pre-legislation). Data were collected for 271 cyclists in 2004 and 699 cyclists in 2000.

Results:The overall prevalence of helmet use increased from 43% (95% CI 39 to 47%) in 2000 to 53% (95% CI 47 to 59%) in 2004. Helmet use increased in those under 18, but did not change in those 18 and older. In the cluster adjusted multivariate Poisson regression model, the prevalence of helmet use significantly increased for those under age 18 (adjusted prevalence ratio (APR) 3.69, 95% CI 2.65 to 5.14), but not for those 18 years and older (APR 1.17, 95% CI 0.95 to 1.43).

Conclusion:Extension of legislation to all age groups should be considered.
Effects of undercover police stings of gun dealers on the supply of new guns to criminals
Authors: Webster D W , Bulzacchelli M T , Zeoli A M , Vernick J S
Published: August 2006

Objective:To assess the effects of undercover police stings and lawsuits against gun dealers suspected of facilitating illegal gun sales in three US cities (Chicago, Detroit, Gary) on the flow of new firearms to criminals.

Methods:An interrupted time series design and negative binomial regression analyses were used to test for temporal change in the recovery of guns used in crimes within one year of retail sale in both intervention and comparison cities.

Results:The stings were associated with an abrupt 46.4% reduction in the flow of new guns to criminals in Chicago (95% confidence interval, −58.6% to −30.5%), and with a gradual reduction in new crime guns recovered in Detroit. There was no significant change associated with the stings in Gary, and no change in comparison cities that was coincident with the stings in Chicago and Detroit.

Conclusions:The announcement of police stings and lawsuits against suspect gun dealers appeared to have reduced the supply of new guns to criminals in Chicago significantly, and may have contributed to beneficial effects in Detroit. Given the important role that gun stores play in supplying guns to criminals in the US, further efforts of this type are warranted and should be evaluated.