bluuebunny/crossref_metadata_2025_split huggingface dataset:
Summing inclusion maps between symmetric sequence spaces
Authors: Defant Andreas , Mastyło Mieczyslaw , Michels Carsten 
Published: September 2002

In 1973/74 Bennett and (independently) Carl proved that for

1
≤
u
≤
2

1 \le u \le 2

the identity map id:

ℓ
u

↪

ℓ
2

\ell _u \hookrightarrow \ell _2

is absolutely

(
u
,
1
)

(u,1)

-summing, i. e., for every unconditionally summable sequence

(

x
n

)

(x_n)

in

ℓ
u

\ell _u

the scalar sequence

(
‖

x
n

‖

ℓ
2

)

(\|x_n \|_{\ell _2})

is contained in

ℓ
u

\ell _u

, which improved upon well-known results of Littlewood and Orlicz. The following substantial extension is our main result: For a

2
2

-concave symmetric Banach sequence space

E
E

the identity map

id
:
E
↪

ℓ
2

\text {id}: E \hookrightarrow \ell _2

is absolutely

(
E
,
1
)

(E,1)

-summing, i. e., for every unconditionally summable sequence

(

x
n

)

(x_n)

in

E
E

the scalar sequence

(
‖

x
n

‖

ℓ
2

)

(\|x_n \|_{\ell _2})

is contained in

E
E

. Various applications are given, e. g., to the theory of eigenvalue distribution of compact operators, where we show that the sequence of eigenvalues of an operator

T
T

on

ℓ
2

\ell _2

with values in a

2
2

-concave symmetric Banach sequence space

E
E

is a multiplier from

ℓ
2

\ell _2

into

E
E

. Furthermore, we prove an asymptotic formula for the

k
k

-th approximation number of the identity map

id
:

ℓ
2
n

↪

E
n

\text {id}: \ell _2^n \hookrightarrow E_n

, where

E
n

E_n

denotes the linear span of the first

n
n

standard unit vectors in

E
E

, and apply it to Lorentz and Orlicz sequence spaces.
Positivity, sums of squares and the multi-dimensional moment problem
Authors: Kuhlmann S. , Marshall M. 
Published: September 2002

Let

K
K

be the basic closed semi-algebraic set in

R

n

\mathbb {R}^n

defined by some finite set of polynomials

S
S

and

T
T

, the preordering generated by

S
S

. For

K
K

compact,

f
f

a polynomial in

n
n

variables nonnegative on

K
K

and real

ϵ
>
0

\epsilon >0

, we have that

f
+
ϵ
∈
T

f+\epsilon \in T

[15]. In particular, the

K
K

-Moment Problem has a positive solution. In the present paper, we study the problem when

K
K

is not compact. For

n
=
1

n=1

, we show that the

K
K

-Moment Problem has a positive solution if and only if

S
S

is the natural description of

K
K

(see Section 1). For

n
≥
2

n\ge 2

, we show that the

K
K

-Moment Problem fails if

K
K

contains a cone of dimension 2. On the other hand, we show that if

K
K

is a cylinder with compact base, then the following property holds:
\[

(
‡
)

∀
f
∈

R

[
X
]
,
f
≥
0
on
K
⇒
∃
q
∈
T
such that
∀
real
ϵ
>
0
,
f
+
ϵ
q
∈
T
.

(\ddagger )\quad \quad \forall f\in \mathbb {R}[X], f\ge 0 \text { on } K\Rightarrow \exists q\in T \text { such that }\forall \text { real } \epsilon >0, f+\epsilon q\in T.\quad

\]
This property is strictly weaker than the one given in [15], but in turn it implies a positive solution to the

K
K

-Moment Problem. Using results of [9], we provide many (noncompact) examples in hypersurfaces for which (

‡
\ddagger

) holds. Finally, we provide a list of 8 open problems.
Accuracy of Race Coding on American Indian Death Certificates, Montana 1996–1998
Authors: Harwell Todd S. , Hansen Dina , Moore Kelly R. , Jeanotte Duane , Gohdes Dorothy , Helgerson Steven D. 
Published: September 2002

Objectives. The purpose of this study was to describe the consistency of coding of American Indians on Montana death certificates and to identify the characteristics of American Indians in Montana associated with consistent classification on death certificates. Methods. The Billings Area Indian Health Service (IHS) patient registration file was linked with Montana Department of Health and Human Services death certificate files for 1996–1998. Results. A total of 769 Montana residents who had died in 1996–1998 were matched to the IHS registration file. Of these decedents, 696 (91%) were consistently classified as American Indian on the death certificate. Seventy-two (99%) of the 73 decedents not classified as Indian were classified as white. American Indians living in counties on or near the seven Montana reservations were more likely to be consistently classified than Indians living in other counties (95% vs. 70%); those with less than 12 years of education (93% vs. 88%) were more likely to be consistently classified than those with 12 or more years of education. Decedents whose cause of death was suicide were less likely than those with other causes of death to be consistently classified (72% vs. 95%). In contrast, a higher percentage of those with an alcohol-related cause of death than of those with other causes of death were consistently classified, although this difference was not statistically significant. Conclusions. The mortality rates for Montana American Indians are underestimated overall, and are differentially under- and overestimated for selected conditions.
Atmospheric sulphur and cloud condensation nuclei in marine air in the Southern Hemisphere
Authors: Ayers G. P. , Cainey J. M. , Gillett R. W. , Ivey J. P. 
Published: September 2002

Measurements of atmospheric sulphur species made in Southern Ocean air, at the Cape Grim Baseline Air Pollution Station, are reviewed in an attempt to discern the role played by oceanic emissions of dimethyl sulphide (DMS) as a source of cloud condensation nuclei (CCN). Consistent with conclusions reached by others, our data indicate that the connection between DMS concentration and CCN concentration is neither simple nor direct, being mediated through a range of chemical pathways and intermediate species that are subject to considerable variability over timescales ranging from minutes to months. Physical and meteorological processes are no less important than chemical processes as sources of complexity in the DMS to CCN transformation process. Moreover, the considerable uncertainty that currently exists about both the number of chemical pathways involved in DMS oxidation, and the kinetic coefficients associated with the proposed pathways, make quantitative modelling studies problematic.
Nevertheless, synthesis of a large body of data available from Cape Grim and other Southern Ocean sites does permit some refinement of our understanding of the DMS–CCN connection. Here, these data are employed to illustrate the current state of knowledge about the connections between DMS, CCN and cloud properties at Cape Grim, and to highlight the many complexities that underlie these connections.
Mechanism of ToxT-Dependent Transcriptional Activation at theVibrio cholerae tcpAPromoter
Authors: Hulbert Robin R. , Taylor Ronald K. 
Published: September 2002

ABSTRACTThe AraC homolog ToxT coordinately regulates virulence gene expression inVibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with thetcpApromoter and investigated the mechanism of ToxT-dependent transcriptional activation attcpA.Deletion analysis showed that a region from −95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to −63. A collection of point mutations generated by error-prone PCR revealed two small regions required for ToxT-dependent transactivation. Binding studies performed with representative mutations showed that the two regions define sites at which ToxT binds to thetcpApromoter region, most likely as a dimer. Results obtained by using arpoAtruncation mutation showed that ToxT-dependent activation attcpAinvolves the C-terminal domain of the RNA polymerase alpha subunit. A model of ToxT-dependent transcriptional activation attcpAis proposed, in which ToxT interacts with two A-rich regions oftcpAcentered at −72 and −51 and requires the alpha C-terminal domain of RNA polymerase.
Mutation inyaaTLeads to Significant Inhibition of Phosphorelay during Sporulation inBacillus subtilis
Authors: Hosoya Shigeo , Asai Kei , Ogasawara Naotake , Takeuchi Michio , Sato Tsutomu 
Published: September 2002

ABSTRACTIn the course of aBacillus subtilisfunctional genomics project which involved screening for sporulation genes, we identified an open reading frame,yaaT, whose disruptant exhibits a sporulation defect. Twenty-four hours after the initiation of sporulation, most cells of theyaaTmutant exhibited stage 0 of sporulation, indicating that theyaaTmutation blocks sporulation at an early stage. Furthermore, the mutation inyaaTled to a significant decrease in transcription from a promoter controlled by Spo0A, a key response regulator required for the initiation of sporulation. However, neither the level of transcription ofspo0A, the activity of σH, which transcribesspo0A, nor the amount of Spo0A protein was severely affected by the mutation inyaaT. Bypassing the phosphorelay by introducing anspo0Amutation (sof-1) into theyaaTmutant suppressed the sporulation defect, suggesting that theyaaTmutation interferes with the phosphorelay process comprising Spo0F, Spo0B, and histidine kinases. We also observed that mutation ofspo0E, which encodes the phosphatase that dephosphorylates Spo0A-P, suppressed the sporulation defect in theyaaTmutant. These results strongly suggest thatyaaTplays a significant role in the transduction of signals to the phosphorelay for initiation of sporulation. Micrographs indicated that YaaT-green fluorescent protein localizes to the peripheral membrane, as well as to the septum, during sporulation.
DistinctclpPGenes Control Specific Adaptive Responses inBacillus thuringiensis
Authors: Fedhila Sinda , Msadek Tarek , Nel Patricia , Lereclus Didier 
Published: September 2002

ABSTRACTClpP and ClpC are subunits of the Clp ATP-dependent protease, which is ubiquitous among prokaryotic and eukaryotic organisms. The role of these proteins in stress tolerance, stationary-phase adaptive responses, and virulence in many bacterial species has been demonstrated. Based on the amino acid sequences of theBacillus subtilis clpCandclpPgenes, we identified oneclpCgene and twoclpPgenes (designatedclpP1andclpP2) inBacillus thuringiensis.Predicted proteins ClpP1 and ClpP2 have approximately 88 and 67% amino acid sequence identity with ClpP ofB. subtilis, respectively. Inactivation ofclpCinB. thuringiensisimpaired sporulation efficiency. TheclpP1andclpP2mutants were both slightly susceptible to salt stress, whereas disruption ofclpP2negatively affected sporulation and abolished motility. Virulence of theclpmutants was assessed by injecting bacteria into the hemocoel ofBombyx morilarvae. TheclpP1mutant displayed attenuated virulence, which appeared to be related to its inability to grow at low temperature (25°C), suggesting an essential role for ClpP1 in tolerance of low temperature. Microscopic examination ofclpP1mutant cells grown at 25°C showed altered bacterial division, with cells remaining attached after septum formation. Analysis oflacZtranscriptional fusions showed thatclpP1was expressed at 25 and 37°C during the entire growth cycle. In contrast,clpP2was expressed at 37°C but not at 25°C, suggesting that ClpP2 cannot compensate for the absence of ClpP1 in theclpP1mutant cells at low temperature. Our study demonstrates that ClpP1 and ClpP2 control distinct cellular regulatory pathways inB. thuringiensis.
Evidence for Targeting of Yop Effectors by the Chromosomally Encoded Ysa Type III Secretion System ofYersinia enterocolitica
Authors: Young Briana M. , Young Glenn M. 
Published: September 2002

ABSTRACTYersinia enterocoliticaO:8 has two contact-dependent type III secretion systems (TTSSs). The Ysa TTSS is encoded by a set of genes located on the chromosome and exports Ysp proteins. The Ysc TTSS and the Yop effector proteins it exports are encoded by genes located on plasmid pYVe8081. In this study, secretion of YspG, YspH, and YspJ by the Ysa TTSS was shown to require pYVe8081. Furthermore, mutations that blocked the function of the Ysc TTSS did not affect YspG, YspH, and YspJ production. This indicated that YspG, YspH, and YspJ are encoded by genes located on pYVe8081 and that they may correspond to Yops. A comparison of Ysps with Yop effectors secreted byY. enterocoliticaindicated that YspG, YspH, and YspJ have apparent molecular masses similar to those of YopN, YopP, and YopE, respectively. Immunoblot analysis demonstrated that antibodies directed against YopN, YopP, and YopE recognized YspG, YspH, and YspJ. Furthermore, mutations inyopN,yopP, andyopEspecifically blocked YopN, YopP, and YopE secretion by the Ysc TTSS and YspG, YspH, and YspJ secretion by the Ysa TTSS. These results indicate YspG, YspH, and YspJ are actually YopN, YopP, and YopE. Additional analysis demonstrated that YopP and YspH secretion was restored toyopPmutants by complementation intranswith a wild-type copy of theyopPgene. Examination ofY. enterocolitica-infected J774A.1 macrophages revealed that both the Ysc and Ysa TTSSs contribute to YopP-dependent suppression of tumor necrosis factor alpha production. This indicates that both the Ysa and Ysc TTSSs are capable of targeting YopP and that they influenceY. enterocoliticainteractions with macrophages. Taken together, these results suggest that the Ysa and Ysc TTSSs contributeto Y. enterocoliticavirulence by exporting both unique and common subsets of effectors.
A Novel Cytology-Based, Two-Hybrid Screen for Bacteria Applied to Protein-Protein Interaction Studies of a Type IV Secretion System
Authors: Ding Zhiyong , Zhao Zhenming , Jakubowski Simon J. , Krishnamohan Atmakuri , Margolin William , Christie Peter J. 
Published: September 2002

ABSTRACTDivIVA ofBacillus subtilisand FtsZ ofEscherichia coliwere used to target heterologous protein complexes to cell division sites ofE. coliandAgrobacterium tumefaciens. DivIVA and FtsZ that were fused to the dimerizing leucine zipper (LZ) domain of the yeast transcription activator GCN4 directed the green fluorescent protein (GFP) that was fused to an LZ domain toE. colidivision sites, resulting in fluorescence patterns identical to those observed with DivIVA::GFP and FtsZ::GFP. These cell division proteins also targeted the VirE1 chaperone and VirE2 secretion substrate complex to division sites ofE. coliandA. tumefaciens. Coproduction of the native VirE1 or VirE2 proteins inhibited the dihybrid interaction in both species, as judged by loss of GFP targeting to division sites. The VirE1 chaperone bound independently to N- and C-terminal regions of VirE2, with a requirement for residues 84 to 147 and 331 to 405 for these interactions, as shown by dihybrid studies with VirE1::GFP and DivIVA fused to N- and C-terminal VirE2 fragments. DivIVA also targeted homo- and heterotypic complexes of VirB8 and VirB10, two bitopic inner membrane subunits of theA. tumefaciensT-DNA transfer system, inE. coliand homotypic complexes of VirB10 inA. tumefaciens.VirB10 self-association in bacteria was mediated by the C-terminal periplasmic domain, as shown by dihybrid studies with fusions to VirB10 truncation derivatives. Together, our findings establish a proof-of-concept for the use of cell-location-specific proteins for studies of interactions among cytosolic and membrane proteins in diverse bacterial species.
Protein-Protein Interactions That Regulate the Energy Stress Activation of σBinBacillus subtilis
Authors: Delumeau Olivier , Lewis Richard J. , Yudkin Michael D. 
Published: September 2002

ABSTRACTσBis an alternative σ factor that controls the general stress response inBacillus subtilis. In the absence of stress, σBis negatively regulated by anti-σ factor RsbW. RsbW is also a protein kinase which can phosphorylate RsbV. When cells are stressed, RsbW binds to unphosphorylated RsbV, produced from the phosphorylated form of RsbV by two phosphatases (RsbU and RsbP) which are activated by stress. We now report the values of theKmfor ATP and theKifor ADP of RsbW (0.9 and 0.19 mM, respectively), which reinforce the idea that the kinase activity of RsbW is directly regulated in vivo by the ratio of these nucleotides. RsbW, purified as a dimer, forms complexes with RsbV and σBwith different stoichiometries, i.e., RsbW2-RsbV2and RsbW2-σB1. As determined by surface plasmon resonance, the dissociation constants of the RsbW-RsbV and RsbW-σBinteractions were found to be similar (63 and 92 nM, respectively). Nonetheless, an analysis of the complexes by nondenaturing polyacrylamide gel electrophoresis in competition assays suggested that the affinity of RsbW2for RsbV is much higher than that for σB. The intracellular concentrations of RsbV, RsbW (as a monomer), and σBmeasured before stress were similar (1.5, 2.6, and 0.9 μM, respectively). After ethanol stress they all increased. The increase was greatest for RsbV, whose concentration reached 13 μM, while those of RsbW (as a monomer) and σBreached 11.8 and 4.9 μM, respectively. We conclude that the higher affinity of RsbW for RsbV than for σB, rather than a difference in the concentrations of RsbV and σB, is the driving force that is responsible for the switch of RsbW to unphosphorylated RsbV.
Tactic Responses to Oxygen in the Phototrophic Bacterium
Rhodobacter sphaeroides
WS8N
Authors: Romagnoli Simona , Packer Helen L. , Armitage Judith P. 
Published: September 2002

ABSTRACT

The temporal and spatial behavior of a number of mutants of the photosynthetic, facultative anaerobe
Rhodobacter sphaeroides
to both step changes and to gradients of oxygen was analyzed. Wild-type cells, grown under a range of conditions, showed microaerophilic behavior, accumulating in a 1.3-mm band about 1.3 mm from the meniscus of capillaries. Evidence suggests this is the result of two signaling pathways. The strength of any response depended on the growth and incubation conditions. Deletion of either the complete chemosensory operons 1 and 2 plus the response regulator genes

cheY
4

and

cheY
5

or

cheA
2

alone led to the loss of all aerotactic responses, although the cells still swam normally. The Prr system of
R. sphaeroides
responds to electron flow through the alternative high-affinity cytochrome oxidase,
cbb
3
, controlling expression of a wide range of metabolic pathways. Mutants with deletions of either the complete Prr operon or the histidine kinase, PrrB, accumulated up to the meniscus but still formed a thick band 1.3 mm from the aerobic interface. This indicates that the negative aerotactic response to high oxygen levels depends on PrrB, but the mutant cells still retain the positive response. Tethered PrrB
−
cells also showed no response to a step-down in oxygen concentration, although those with deletions of the whole operon showed some response. In gradients of oxygen where the concentration was reduced at 0.4 μM/s, tethered wild-type cells showed two different phases of response, with an increase in stopping frequency when the oxygen concentration fell from 80 to 50% dissolved oxygen and a decrease in stopping at 50 to 20% dissolved oxygen, with cells returning to their normal stopping frequency in 0% oxygen. PrrB and CheA
2
mutants showed no response, while PrrCBA mutants still showed some response.
Induction of a DNA Nickase in the Presence of Its Target Site Stimulates Adaptive Mutation in
Escherichia coli
Authors: Rodriguez Cesar , Tompkin Joshua , Hazel Jill , Foster Patricia L. 
Published: September 2002

ABSTRACT

Adaptive mutation to Lac
+
in
Escherichia coli
strain FC40 depends on recombination functions and is enhanced by the expression of conjugal functions. To test the hypothesis that the conjugal function that is important for adaptive mutation is the production of a single-strand nick at the conjugal origin, we supplied an exogenous nicking enzyme, the gene II protein (gIIp) of bacteriophage f1, and placed its target sequence near the
lac
allele. When both gIIp and its target site were present, adaptive mutation was stimulated three- to fourfold. Like normal adaptive mutations, gIIp-induced mutations were

recA
+

and

ruvC
+

dependent and were mainly single-base deletions in runs of iterated bases. In addition, gIIp with its target site could substitute for conjugal functions in adaptive mutation. These results support the hypothesis that nicking at the conjugal origin initiates the recombination that produces adaptive mutations in this strain of
E. coli
, and they suggest that nicking may be the only conjugal function required for adaptive mutation.
Characterization of the Depletion of 2-
C
-Methyl-
d
-Erythritol-2,4-Cyclodiphosphate Synthase in
Escherichia coli
and
Bacillus subtilis
Authors: Campbell Tracey L. , Brown Eric D. 
Published: September 2002

ABSTRACT

The
ispF
gene product in
Escherichia coli
has been shown to catalyze the formation of 2-
C
-methyl-
d
-erythritol 2,4-cyclodiphosphate (MEC) in the deoxyxylulose (DOXP) pathway for isoprenoid biosynthesis. In this work, the
E. coli
gene
ispF
and its
Bacillus subtilis
orthologue,
yacN
, were deleted and conditionally complemented by expression of these genes from distant loci in the respective organisms. In
E. coli
, complementation was achieved through integration of
ispF
at the
araBAD
locus with control from the arabinose-inducible
araBAD
promoter, while in
B. subtilis
,
yacN
was placed at
amyE
under control of the xylose-inducible
xylA
promoter. In both cases, growth was severely retarded in the absence of inducer, consistent with these genes being essential for survival.
E. coli
cells depleted of MEC synthase revealed a filamentous phenotype. This was in contrast to the depletion of MEC synthase in
B. subtilis
, which resulted in a loss of rod shape, irregular septation, multicompartmentalized cells, and thickened cell walls. To probe the nature of the predominant deficiency of MEC synthase-depleted cells, we investigated the sensitivity of these conditionally complemented mutants, grown with various concentrations of inducer, to a wide variety antibiotics. Synthetic lethal behavior in MEC synthase-depleted cells was prevalent for cell wall-active antibiotics.
Overexpression of the MtrC-MtrD-MtrE Efflux Pump Due to an
mtrR
Mutation Is Required for Chromosomally Mediated Penicillin Resistance in
Neisseria gonorrhoeae
Authors: Veal Wendy L. , Nicholas Robert A. , Shafer William M. 
Published: September 2002

ABSTRACT

The importance of the
mtrCDE
-encoded efflux pump in conferring chromosomally mediated penicillin resistance on certain strains of
Neisseria gonorrhoeae
was determined by using genetic derivatives of penicillin-sensitive strain FA19 bearing defined mutations (
mtrR
,
penA
, and
penB
) donated by a clinical isolate (FA6140) expressing high-level resistance to penicillin and antimicrobial hydrophobic agents (HAs). When introduced into strain FA19 by transformation, a single base pair deletion in the
mtrR
promoter sequence from strain FA6140 was sufficient to provide high-level resistance to HAs (e.g., erythromycin and Triton X-100) but only a twofold increase in resistance to penicillin. When subsequent mutations in
penA
and
porIB
were introduced from strain FA6140 into strain WV30 (FA19
mtrR
) by transformation, resistance to penicillin increased incrementally up to a MIC of 1.0 μg/ml. Insertional inactivation of the gene (
mtrD
) encoding the membrane transporter component of the Mtr efflux pump in these transformant strains and in strain FA6140 decreased the MIC of penicillin by 16-fold. Genetic analyses revealed that
mtrR
mutations, such as the single base pair deletion in its promoter, are needed for phenotypic expression of penicillin and tetracycline resistance afforded by the
penB
mutation. As
penB
represents amino acid substitutions within the third loop of the outer membrane PorIB protein that modulate entry of penicillin and tetracycline, the results presented herein suggest that PorIB and the MtrC-MtrD-MtrE efflux pump act synergistically to confer resistance to these antibiotics.