bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional Analysis ofAvr9/Cf-9 Rapidly ElicitedGenes Identifies a Protein Kinase, ACIK1, That Is Essential for Full Cf-9–Dependent Disease Resistance in Tomato
Authors: Rowland Owen , Ludwig Andrea A. , Merrick Catherine J. , Baillieul Fabienne , Tracy Frances E. , Durrant Wendy E. , Fritz-Laylin Lillian , Nekrasov Vladimir , Sjölander Kimmen , Yoshioka Hirofumi , Jones Jonathan D.G.
Published: December 2004

Tomato (Lycopersicon esculentum) Cf genes confer resistance to the fungal pathogen Cladosporium fulvum through recognition of secreted avirulence (Avr) peptides. Plant defense responses, including rapid alterations in gene expression, are immediately activated upon perception of the pathogen. Previously, we identified a collection of Avr9/Cf-9 rapidly (15 to 30 min) elicited (ACRE) genes from tobacco (Nicotiana tabacum). Many of the ACRE genes encode putative signaling components and thus may play pivotal roles in the initial development of the defense response. To assess the requirement of 42 of these genes in the hypersensitive response (HR) induced by Cf-9/Avr9 or by Cf-4/Avr4, we used virus-induced gene silencing (VIGS) in N. benthamiana. Three genes were identified that when silenced compromised the Cf-mediated HR. We further characterized one of these genes, which encodes a Ser/Thr protein kinase called Avr9/Cf-9 induced kinase 1 (ACIK1). ACIK1 mRNA was rapidly upregulated in tobacco and tomato upon elicitation by Avr9 and by wounding. Silencing of ACIK1 in tobacco resulted in a reduced HR that correlated with loss of ACIK1 transcript. Importantly, ACIK1 was found to be required for Cf-9/Avr9- and Cf-4/Avr4-mediated HRs but not for the HR or resistance mediated by other resistance/Avr systems, such as Pto/AvrPto, Rx/Potato virus X, or N/Tobacco mosaic virus. Moreover, VIGS of LeACIK1 in tomato decreased Cf-9–mediated resistance to C. fulvum, showing the importance of ACIK1 in disease resistance.
CRS1, a Chloroplast Group II Intron Splicing Factor, Promotes Intron Folding through Specific Interactions with Two Intron Domains
Authors: Ostersetzer Oren , Cooke Amy M. , Watkins Kenneth P. , Barkan Alice
Published: December 2004

Group II introns are ribozymes that catalyze a splicing reaction with the same chemical steps as spliceosome-mediated splicing. Many group II introns have lost the capacity to self-splice while acquiring compensatory interactions with host-derived protein cofactors. Degenerate group II introns are particularly abundant in the organellar genomes of plants, where their requirement for nuclear-encoded splicing factors provides a means for the integration of nuclear and organellar functions. We present a biochemical analysis of the interactions between a nuclear-encoded group II splicing factor and its chloroplast intron target. The maize (Zea mays) protein Chloroplast RNA Splicing 1 (CRS1) is required specifically for the splicing of the group II intron in the chloroplast atpF gene and belongs to a plant-specific protein family defined by a recently recognized RNA binding domain, the CRM domain. We show that CRS1's specificity for the atpF intron in vivo can be explained by CRS1's intrinsic RNA binding properties. CRS1 binds in vitro with high affinity and specificity to atpF intron RNA and does so through the recognition of elements in intron domains I and IV. These binding sites are not conserved in other group II introns, accounting for CRS1's intron specificity. In the absence of CRS1, the atpF intron has little uniform tertiary structure even at elevated [Mg2+]. CRS1 binding reorganizes the RNA, such that intron elements expected to be at the catalytic core become less accessible to solvent. We conclude that CRS1 promotes the folding of its group II intron target through tight and specific interactions with two peripheral intron segments.
Proliferation, apoptosis, and survivin expression in a spectrum of melanocytic nevi
Authors: Florell Scott R. , Bowen Anneli R. , Hanks Adrianne N. , Murphy Kelley J. , Grossman Douglas
Published: December 2004

Background:  Apoptosis is important for maintenance of tissue homeostasis and often dysregulated in cutaneous neoplasms. The apoptosis inhibitor survivin is expressed in melanoma and non‐melanoma skin cancers and benign keratinocytic lesions. Its expression has not been studied in melanocytic nevi.

Objective:  We determined the expression pattern of survivin in benign melanocytic nevi in comparison to markers of proliferation and apoptosis.

Methods:  Six cases of each of the following melanocytic nevi were retrieved from a dermatopathology archive: compound dysplastic nevus, intradermal nevus, compound nevus, neurotized intradermal nevus, and Spitz nevus. Survivin expression was evaluated by in situ hybridization. Apoptotic and proliferation indices were calculated by counting immunoreactive cells in terminal deoxynucleotidyl transferase (TdT)‐mediated dUTP nick end labeling and proliferating cell nuclear antigen immunostained sections, respectively.

Results:  All nevi, regardless of histologic type, expressed survivin. Compound melanocytic lesions expressed survivin in both epidermal and dermal compartments. The apoptotic rate was low for dysplastic, compound, and Spitz nevi, and apoptotic cells were not identified in any neurotized nevus. The proliferative index was highest for Spitz nevi, while all other nevi demonstrated rare positive cells.

Conclusions:  Survivin is consistently expressed in benign melanocytic lesions, while apoptotic cells are rarely identified, suggesting the dysregulation of apoptotic pathways with the accumulation of cells in these neoplasms.
Longitudinal melanonychia of the toenails with presence of Medlar bodies on biopsy
Authors: Ko Christine J. , Sarantopoulos G. Peter , Pai Gabriel , Binder Scott W.
Published: December 2004

Abstract:  A 9‐year‐old girl presented with a 2‐year history of pigmented streaks on her second right toenail as well as on her fourth and fifth left toenails. The patient was otherwise asymptomatic with no other physical findings. Owing to parental concern, a biopsy was performed, which revealed numerous bacteria as well as Medlar bodies overlying the nail bed with no evidence of a nevomelanocytic lesion. To our knowledge, this is the first report of Medlar bodies causing pigmented streaks in the toenails.
Cluster designation 5 staining of normal and non‐lymphoid neoplastic skin*
Authors: Bogner Paul N. , Su Lyndon D. , Fullen Douglas R.
Published: December 2004

Background:  Immunohistochemical staining for cluster designation 5 (CD5) has been found to label a variety of non‐lymphoid tumors.

Methods:  A variety of eccrine, apocrine, follicular, epithelial, and pagetoid lesions were selected and stained with an anti‐CD5 monoclonal antibody (Novocastra Labs, Newcastle upon Tyne, UK, clone 4C7) by immunohistochemistry. The intensity of positive cytoplasmic staining was graded semiquantitatively (1+ weak staining, 2+ strong staining). Additionally, the percentage of positive lesional cells was placed in one of four categories: >75%, 25–75%, 1–25%, and <1%.

Results:  Within normal skin, CD5 labeled lymphocytes, apocrine glands, deep dermal eccrine glands, and smooth muscle (weak). The majority of benign and malignant apocrine lesions demonstrated strong focal (36%, n = 11)‐to‐diffuse (64%, n = 16) staining. In contrast, labeling of benign eccrine tumors was more focal, tending to localize around ducts (79%, n = 19). Microcystic adnexal carcinoma demonstrated focal staining of deeper ductal structures (71%, n = 7), whereas desmoplastic trichoepithelioma and basal cell carcinoma showed only rare positive cells. All cases of mammary (n = 7) and extramammary (n = 8) Paget's disease labeled diffusely for CD5. Pagetoid Bowen's disease (n = 6), intraepidermal sebaceous carcinoma (n = 3), nor melanoma in situ (n = 6) showed any CD5 staining.

Conclusions:  Immunohistochemical staining for CD5 is extremely useful in the differential diagnosis of pagetoid epidermal lesions and will mark mammary and extramammary Paget's disease, but not pagetoid Bowen's disease, melanoma in situ, or sebaceous carcinoma.
Monkeypox virus: histologic, immunohistochemical and electron‐microscopic findings
Authors: Bayer‐Garner I. B.
Published: December 2004

Background:  Human monkeypox, an emerging viral zoonosis first recognized in Africa, has recently emerged in the mid‐western US. Initially, it presents with skin eruptions and fevers with diaphoresis and rigors. Clinically, the skin lesions progress from papules to vesiculopustules to resolving eschars.

Methods:  Three cutaneous biopsy specimens from two patients with polymerase chain reaction (PCR)‐proven monkeypox were available for review. The histologic, immunohistochemical and electron‐microscopic features were identified.

Results:  The clinical progression of lesions is mirrored histologically with ballooning degeneration of basal keratinocytes and spongiosis of a mildly acanthotic epidermis progressing to full thickness necrosis of a markedly acanthotic epidermis containing few viable keratinocytes. A lichenoid‐mixed inflammatory cell infiltrate is present, which exhibits progressive exocytosis with the keratinocyte necrosis. Inflammation of the superficial and deep vascular plexes, eccrine units and follicles is also present. Viral cytopathic effect is manifest by multinucleated syncytial keratinocytes. Immunohistochemically, viral antigen is detected within keratinocytes of the lesional epidermis, follicular and eccrine epithelium and few dermal mononuclear cells. Electron microscopy reveals virions at various stages of assembly within the keratinocyte cytoplasm.

Conclusions:  The histologic differential diagnosis includes herpes simplex virus, varicella and other pox viruses, such as smallpox. The first one may be differentiated histologically, immunohistochemically and electron microscopically. The last two may be differentiated using PCR assay for the monkeypox extracellular‐envelope virus protein gene.
High‐pressure paint‐gun injury of the finger simulating giant cell tumor of tendon sheath
Authors: Stefanato Catherine M. , Turner Matthew S. , Bhawan Jag
Published: December 2004

Abstract:  High‐pressure paint guns deliver paint at approximately 3000 pounds per square inch. At this pressure, paint will penetrate the skin and spread quickly through fascial planes and tendon sheaths. The present case is that of a lesion from the finger of a 35‐year‐old white male in whom a history was initially unavailable. Histologic examination revealed diffuse fibrohistiocytic proliferation and giant cells, with numerous darkly pigmented, uniformly small‐sized particles throughout the lesion. The initial impression was that of a giant cell tumor of tendon sheath. However, the pigment particles were negative for Perls stain, and polariscopic examination revealed clear refractile fragments. These findings raised the possibility that the lesion was the result of a traumatic event. On further inquiry, it was revealed that the patient had sustained a high‐pressure paint‐gun injury 1 year earlier. The simulation, histopathologically, of a giant cell tumor of tendon sheath by a high‐pressure paint‐gun injury has not, to our knowledge, been reported previously, nor has the histologic finding of small, uniformly sized pigment particles and polarizable refractile fragments in this particular type of injury.
An Evaluation of James et al.'s (1992) VG Estimation Procedure when Artifacts and True Validity are Correlated*
Authors: Thomas Adrian , Raju Nambury S.
Published: December 2004

James, Demaree, Muliak, and Ladd (1992) outlined a procedure for estimating the mean (M) and variance (V) of true validities (ρ's). This procedure was designed to take into account the potential nonzero intercorrelations among the three artifacts (predictor reliability, criterion reliability, and range restriction) and ρ. The accuracy of this new validity generalization procedure was compared with the accuracy of the Model 2‐based (in which correlations are individually corrected for artifacts) procedure because this latter procedure does not require the assumption of uncorrelated artifacts. The current study included two different ρ distributions, three sample sizes, and six different levels of intercorrelations among the three artifacts and ρ. Both procedures yielded relatively accurate estimates of M and V even when the intercorrelations among the three artifacts and ρ were nonzero. The Model 2‐based estimates were slightly more accurate than the James et al. estimates, and the accuracy of the Model 2‐based estimates was much more stable across sample sizes and different levels of intercorrelatedness. Sample‐based artifact data were used in this investigation.
Interstitial capillary changes in lithium nephropathy: effects of antihypertensive treatment
Authors: SKYUM HELLE , MARCUSSEN NIELS , NIELSEN STEEN HORNE , CHRISTENSEN STEN
Published: December 2004

Histopathological changes were investigated in the tubulointerstitium and in the capillaries of male Wistar rats with lithium‐induced nephropathy using stereological methods. Two antihypertensive drugs with opposite effects on the renin‐angiotensin system, an ACE inhibitor (angiotensin converting enzyme inhibitor) and a thiazide diuretic, modified the nephropathy. Generally, there was a significant positive correlation between the reduction in GFR (glomerular filtration rate) and the reduction in the volume of intact tubular structures and interstitial capillaries. A significant negative correlation was seen between the reduction in GFR and the increase in tubulocapillary distance and the absolute volume of interstitial connective tissue, respectively. Treatment with perindopril, and to some extent hydrochlorothiazide, reversed the rise in systolic blood pressure associated with lithium‐induced nephropathy but did not affect the progression to terminal uraemia, the structural renal changes or the mortality. In conclusion, severe tubular and capillary changes are seen in this model of chronic renal failure. Tubular atrophy is associated with a decrease in interstitial capillaries and with an increase in the tubulocapillary distance. Systemic hypertension or activation of the renin‐angiotensin system may not be important factors for the progression to terminal renal failure.
Relativistic velocity and acceleration transformations from thought experiments
Authors: Mathews W. N.
Published: December 2004

I derive the three-dimensional velocity and acceleration transformations of special relativity from a set of thought experiments. These derivations are facilitated by the use of an enhanced particle-light clock and employ simple physical arguments based on kinematic considerations and the principle of relativity. The derivations are conceptually simpler, more intuitive, and less abstract, and require significantly less background and preparatory effort than the usual derivations employing the Lorentz transformation. They also serve to emphasize the directness and immediacy of the connection between the principle of relativity and its physical consequences.
m
-Xylene-Responsive
Pu
-
PnifH
Hybrid σ
54
Promoters That Overcome Physiological Control in
Pseudomonas putida
KT2442
Authors: Carmona Manuel , Fernández Silvia , Rodríguez María J. , de Lorenzo Víctor
Published: December 2004

The sequences surrounding the −12/−24 motif of the
m-
xylene-responsive σ
54
promoter
Pu
of the
Pseudomonas putida
TOL plasmid pWW0 were replaced by various DNA segments of the same size recruited from
PnifH
σ
54
promoter variants known to have various degrees of efficacy and affinity for σ
54
-RNA polymerase (RNAP). In order to have an accurate comparison of the output in vivo of each of the hybrids, the resulting promoters were recombined at the same location of the chromosome of
P. putida
KT2442 with a tailored vector system. The promoters included the upstream activation sequence (UAS) for the cognate regulator of the TOL system (XylR) fused to the −12/−24 region of the wild-type
PnifH
and its higher σ
54
-RNAP affinity variants
PnifH049
and
PnifH319
. As a control, the downstream region of the
glnAp2
promoter (lacking integration host factor) was fused to the XylR UAS as well. When the induction patterns of the corresponding
lacZ
fusion strains were compared in vivo, we observed that promoters bearing the RNAP binding site of
PnifH049
and
PnifH319
were not silenced during exponential growth, as is distinctly the case for the wild-type
Pu
promoter or for the
Pu-PnifH
variant. Taken together, our results indicate that the promoter sequence(s) spanning the −12/−24 region of
Pu
dictates the coupling of promoter output to growth conditions.
Impact of
mutS
Inactivation on Foreign DNA Acquisition by Natural Transformation in
Pseudomonas stutzeri
Authors: Meier Petra , Wackernagel Wilfried
Published: December 2004

In prokaryotic mismatch repair the MutS protein and its homologs recognize the mismatches. The
mutS
gene of naturally transformable
Pseudomonas stutzeri
ATCC 17587 (genomovar 2) was identified and characterized. The deduced amino acid sequence (859 amino acids; 95.6 kDa) displayed protein domains I to IV and a mismatch-binding motif similar to those in MutS of
Escherichia coli
. A
mutS
::
aac
mutant showed 20- to 163-fold-greater spontaneous mutability. Transformation experiments with DNA fragments of
rpoB
containing single nucleotide changes (providing rifampin resistance) indicated that mismatches resulting from both transitions and transversions were eliminated with about 90% efficiency in
mutS
+
. The
mutS
+
gene of strain ATCC 17587 did not complement an
E. coli
mutant but partially complemented a
P. stutzeri
JM300 mutant (genomovar 4). The declining heterogamic transformation by DNA with 0.1 to 14.6% sequence divergence was partially alleviated by
mutS
::
aac
, indicating that there was a 14 to 16% contribution of mismatch repair to sexual isolation. Expression of
mutS
+
from a multicopy plasmid eliminated autogamic transformation and greatly decreased heterogamic transformation, suggesting that there is strong limitation of MutS in the wild type for marker rejection. Remarkably,
mutS
::
aac
altered foreign DNA acquisition by homology-facilitated illegitimate recombination (HFIR) during transformation, as follows: (i) the mean length of acquired DNA was increased in transformants having a net gain of DNA, (ii) the HFIR events became clustered (hot spots) and less dependent on microhomologies, which may have been due to topoisomerase action, and (iii) a novel type of transformants (14%) had integrated foreign DNA with no loss of resident DNA. We concluded that in
P. stutzeri
upregulation of MutS could enforce sexual isolation and downregulation could increase foreign DNA acquisition and that MutS affects mechanisms of HFIR.
Glutathione Plays a Fundamental Role in Growth and Symbiotic Capacity of
Sinorhizobium meliloti
Authors: Harrison Judith , Jamet Alexandre , Muglia Cecilia I. , Van de Sype Ghislaine , Aguilar O. Mario , Puppo Alain , Frendo Pierre
Published: December 2004

Rhizobia form a symbiotic relationship with plants of the legume family to produce nitrogen-fixing root nodules under nitrogen-limiting conditions. We have examined the importance of glutathione (GSH) during free-living growth and symbiosis of
Sinorhizobium meliloti
. An
S. meliloti
mutant strain (SmgshA) which is unable to synthesize GSH due to a gene disruption in
gshA
, encoding the enzyme for the first step in the biosynthesis of GSH, was unable to grow under nonstress conditions, precluding any nodulation. In contrast, an
S. meliloti
strain (SmgshB) with
gshB
, encoding the enzyme involved in the second step in GSH synthesis, deleted was able to grow, indicating that γ-glutamylcysteine, the dipeptide intermediate, can partially substitute for GSH. However, the SmgshB strain showed a delayed-nodulation phenotype coupled to a 75% reduction in the nitrogen fixation capacity. This phenotype was linked to abnormal nodule development. Both the SmgshA and SmgshB mutant strains exhibited higher catalase activity than the wild-type
S. meliloti
strain, suggesting that both mutant strains are under oxidative stress. Taken together, these results show that GSH plays a critical role in the growth of
S. meliloti
and during its interaction with the plant partner.
Molecular Analysis of the
Vibrio cholerae
Type II Secretion ATPase EpsE
Authors: Camberg Jodi L. , Sandkvist Maria
Published: December 2004

The
type II secretion system is a macromolecular assembly that
facilitates the extracellular translocation of folded proteins in
gram-negative bacteria. EpsE, a member of this secretion system in
Vibrio cholerae
, contains a nucleotide-binding motif
composed of Walker A and B boxes that are thought to participate in
binding and hydrolysis of ATP and displays structural homology
to other transport ATPases. Here we demonstrate that purified
EpsE is an Mg
2+
-dependent ATPase and define
optimal conditions for the hydrolysis reaction. EpsE displays
concentration-dependent activity, which may suggest that the active
form is oligomeric. Size exclusion chromatography showed that the
majority of purified EpsE is monomeric; however, detailed analyses of
specific activities obtained following gel filtration revealed the
presence of a small population of active oligomers. We further report
that EpsE binds zinc through a tetracysteine motif near its carboxyl
terminus, yet metal displacement assays suggest that zinc is not
required for catalysis. Previous studies describing interactions
between EpsE and other components of the type II secretion pathway
together with these data further support the hypothesis that EpsE
functions to couple energy to the type II apparatus, thus enabling
secretion.
pH Regulates Genes for Flagellar Motility, Catabolism, and Oxidative Stress inEscherichia coliK-12
Authors: Maurer Lisa M. , Yohannes Elizabeth , Bondurant Sandra S. , Radmacher Michael , Slonczewski Joan L.
Published: December 2004

Gene expression profiles ofEscherichia coliK-12 W3110 were compared as a function of steady-state external pH. Cultures were grown to an optical density at 600 nm of 0.3 in potassium-modified Luria-Bertani medium buffered at pH 5.0, 7.0, and 8.7. For each of the three pH conditions, cDNA from RNA of five independent cultures was hybridized to AffymetrixE.coliarrays. Analysis of variance with an α level of 0.001 resulted in 98% power to detect genes showing a twofold difference in expression. Normalized expression indices were calculated for each gene and intergenic region (IG). Differential expression among the three pH classes was observed for 763 genes and 353 IGs. Hierarchical clustering yielded six well-defined clusters of pH profiles, designated Acid High (highest expression at pH 5.0), Acid Low (lowest expression at pH 5.0), Base High (highest at pH 8.7), Base Low (lowest at pH 8.7), Neutral High (highest at pH 7.0, lower in acid or base), and Neutral Low (lowest at pH 7.0, higher at both pH extremes). Flagellar and chemotaxis genes were repressed at pH 8.7 (Base Low cluster), where the cell's transmembrane proton potential is diminished by the maintenance of an inverted pH gradient. High pH also repressed the proton pumps cytochrome o (cyo) and NADH dehydrogenases I and II. By contrast, the proton-importing ATP synthase F1Foand the microaerophilic cytochromed(cyd), which minimizes proton export, were induced at pH 8.7. These observations are consistent with a model in which high pH represses synthesis of flagella, which expend proton motive force, while stepping up electron transport and ATPase components that keep protons inside the cell. Acid-induced genes, on the other hand, were coinduced by conditions associated with increased metabolic rate, such as oxidative stress. All six pH-dependent clusters included envelope and periplasmic proteins, which directly experience external pH. Overall, this study showed that (i) low pH accelerates acid consumption and proton export, while coinducing oxidative stress and heat shock regulons; (ii) high pH accelerates proton import, while repressing the energy-expensive flagellar and chemotaxis regulons; and (iii) pH differentially regulates a large number of periplasmic and envelope proteins.
Cold Shock of a Hyperthermophilic Archaeon:
Pyrococcus furiosus
Exhibits Multiple Responses to a Suboptimal Growth Temperature with a Key Role for Membrane-Bound Glycoproteins
Authors: Weinberg Michael V. , Schut Gerrit J. , Brehm Scott , Datta Susmita , Adams Michael W. W.
Published: December 2004

The hyperthermophilic archaeon,
Pyrococcus furiosus
, was grown on maltose near its optimal growth temperature, 95°C, and at the lower end of the temperature range for significant growth, 72°C. In addition, cultures were shocked by rapidly dropping the temperature from 95 to 72°C. This resulted in a 5-h lag phase, during which time little growth occurred. Transcriptional analyses using whole-genome DNA microarrays representing 2,065 open reading frames (ORFs) in the
P. furiosus
genome showed that cells undergo three very different responses at 72°C: an early shock (1 to 2 h), a late shock (5 h), and an adapted response (occurring after many generations at 72°C). Each response involved the up-regulation in the expression of more than 30 ORFs unique to that response. These included proteins involved in translation, solute transport, amino acid biosynthesis, and tungsten and intermediary carbon metabolism, as well as numerous conserved-hypothetical and/or membrane-associated proteins. Two major membrane proteins were evident after one-dimensional sodium dodecyl sulfate-gel analysis of cold-adapted cells, and staining revealed them to be glycoproteins. Their cold-induced expression evident from the DNA microarray analysis was confirmed by quantitative PCR. Termed CipA (PF0190) and CipB (PF1408), both appear to be solute-binding proteins. While the archaea do not contain members of the bacterial cold shock protein (Csp) family, they all contain homologs of CipA and CipB. These proteins are also related phylogenetically to some cold-responsive genes recently identified in certain bacteria. The Cip proteins may represent a general prokaryotic-type cold response mechanism that is present even in hyperthermophilic archaea.
Ler Is a Negative Autoregulator of theLEE1Operon in EnteropathogenicEscherichia coli
Authors: Berdichevsky Tatiana , Friedberg Devorah , Nadler Chen , Rokney Assaf , Oppenheim Amos , Rosenshine Ilan
Published: December 2004

EnteropathogenicEscherichia coli(EPEC) causes severe diarrhea in young children. Essential for colonization of the host intestine is the LEE pathogenicity island, which comprises a cluster of operons encoding a type III secretion system and related proteins. TheLEE1operon encodes Ler, which positively regulates many EPEC virulence genes in the LEE region and elsewhere in the chromosome. We found that Ler acts as a specific autorepressor ofLEE1transcription. We further show that Ler specifically binds upstream of theLEE1operon in vivo and in vitro. A comparison of the Ler affinities to different DNA regions suggests that the autoregulation mechanism limits the steady-state level of Ler to concentrations that are just sufficient for activation of theLEE2andLEE3promoters and probably other LEE promoters. This mechanism may reflect the need of EPEC to balance maximizing the colonization efficiency by increasing the expression of the virulence genes and minimizing the immune response of the host by limiting their expression. In addition, we found that the autoregulation mechanism reduces the cell-to-cell variability in the levels ofLEE1expression. Our findings point to a new negative regulatory circuit that suppresses the noise and optimizes the expression levels oflerand otherLEE1genes.
Expression and Characterization of a Soluble, Active Form of the Jaagsiekte Sheep Retrovirus Receptor, Hyal2
Authors: Vigdorovich Vladimir , Strong Roland K. , Miller A. Dusty
Published: December 2004

Retrovirus entry into cells is mediated by specific interactions between virus envelope glycoproteins and cell surface receptors. Many of these receptors contain multiple membrane-spanning regions, making their purification and study difficult. The jaagsiekte sheep retrovirus (JSRV) receptor, hyaluronidase 2 (Hyal2), is a glycosylphosphatidylinositol (GPI)-anchored molecule containing no peptide transmembrane regions, making it an attractive candidate for study of retrovirus entry. Further, the hyaluronidase activity reported for human Hyal2, combined with its broad expression pattern, may point to a critical function of Hyal2 in the turnover of hyaluronan, a major extracellular matrix component. Here we describe the properties of a soluble form of human Hyal2 (sHyal2) purified from a baculoviral expression system. sHyal2 is a 54-kDa monomer with weak hyaluronidase activity compared to that of the known hyaluronidase Spam1. In contrast to a previous report indicating that Hyal2 cleaved hyaluronan to a limit product of 20 kDa and was active only at acidic pH, we find that sHyal2 is capable of further degradation of hyaluronan and is active over a broad pH range, consistent with Hyal2 being active at the cell surface where it is normally localized. Interaction of sHyal2 with the JSRV envelope glycoprotein was analyzed by viral inhibition assays, showing >90% inhibition of transduction at 28 nM sHyal2, and by surface plasmon resonance, revealing a remarkably tight specific interaction with a dissociation constant (KD) of 32 ± 1 pM. In contrast to results obtained with avian retroviruses, purified receptor was not capable of promoting transduction of cells that do not express the virus receptor.
QUANTUM MECHANICS OF DISSIPATIVE SYSTEMS
Authors: Yan YiJing , Xu RuiXue
Published: December 2004

▪ Abstract  Quantum dissipation involves both energy relaxation and decoherence, leading toward quantum thermal equilibrium. There are several theoretical prescriptions of quantum dissipation but none of them is simple enough to be treated exactly in real applications. As a result, formulations in different prescriptions are practically used with different approximation schemes. This review examines both theoretical and application aspects on various perturbative formulations, especially those that are exact up to second-order but nonequivalent in high-order system-bath coupling contributions. Discrimination is made in favor of an unconventional formulation that in a sense combines the merits of both the conventional time-local and memory-kernel prescriptions, where the latter is least favorite in terms of the applicability range of parameters for system-bath coupling, non-Markovian, and temperature. Also highlighted is the importance of correlated driving and disspation effects, not only on the dynamics under strong external field driving, but also in the calculation of field-free correlation and response functions.
DETECTING MICRODOMAINS IN INTACT CELL MEMBRANES
Authors: Lagerholm B. Christoffer , Weinreb Gabriel E. , Jacobson Ken , Thompson Nancy L.
Published: December 2004

▪ Abstract  Current models for cellular plasma membranes focus on spatial heterogeneity and how this heterogeneity relates to cell function. In particular, putative lipid raft membrane domains have been postulated to exist based in large part on the results that a significant fraction of the membrane is detergent insoluble and that molecules facilitating key membrane processes like signal transduction are often found in the detergent-resistant membrane fraction. Yet, the in vivo existence of lipid rafts remains extremely controversial because, despite being sought for more than a decade, evidence for their presence in intact cell membranes is inconclusive. In this review, a variety of experimental techniques that have been or might be used to look for lipid microdomains in intact cell membranes are described. Experimental results are highlighted and the strengths and limitations of different techniques for microdomain identification and characterization are assessed.
Corticosterone binding globulin regulation and thymus changes after thermal injury in mice
Authors: D’Elia Michele , Patenaude Julie , Hamelin Claudine , Garrel Dominique R. , Bernier Jacques
Published: December 2004

Thermal injury is extremely stressful, and data characterizing the systemic endocrine stress response to this injury are sparse. The objective of this study was to measure the effects of thermal injury on mice on corticosterone (Cort) levels in relation with corticosteroid-binding globulin (CBG) and thymus cell populations. The endocrine stress response was determined by measuring total Cort, free Cort, CBG binding capacity, liver CBG mRNA, and circulating CBG levels at 1, 2, 5, and 10 days postburn. Thymus cell populations were also analyzed. After thermal injury, a rapid increase of total Cort was observed in the first 48 h. This was associated with a decrease of hepatic CBG mRNA, protein levels, and binding capacity. Percentage of free Cort in the burn group peaked at day 2 postburn with a dramatic (+500%) increase. This correlated with a significant decrease of thymus cellularity (50% less). Phenotypic analyses showed that corticosensitive cells were significantly altered. After treatment (5 days), both endocrine and immune parameters returned to control levels. Our results demonstrate that, after a thermal injury, CBG is mainly responsible for Cort’s action on corticosensitive immune cells.
Heat acclimation and physical training adaptations of young women using different contraceptive hormones
Authors: Armstrong Lawrence E. , Maresh Carl M. , Keith NiCole R. , Elliott Tabatha A. , VanHeest Jaci L. , Scheett Timothy P. , Stoppani James , Judelson Daniel A. , De Souza Mary Jane
Published: December 2004

Although endogenous and exogenous steroid hormones affect numerous physiological processes, the interactions of reproductive hormones, chronic exercise training, and heat acclimation are unknown. This investigation evaluated the responses and adaptations of 36 inactive females [age 21 ± 3 (SD) yr] as they undertook a 7- to 8-wk program [heat acclimation and physical training (HAPT)] of indoor heat acclimation (90 min/day, 3 days/wk) and outdoor physical training (3 days/wk) while using either an oral estradiol-progestin contraceptive (ORAL, n = 15), a contraceptive injection of depot medroxyprogesterone acetate (DEPO, n = 7), or no contraceptive (EU-OV, n = 14; control). Standardized physical fitness and exercise-heat tolerance tests (36.5°C, 37% relative humidity), administered before and after HAPT, demonstrated that the three subject groups successfully ( P < 0.05) acclimated to heat (i.e., rectal temperature, heart rate) and improved muscular endurance (i.e., sit-ups, push-ups, 4.6-km run time) and body composition characteristics. The stress of HAPT did not disrupt the menstrual cycle length/phase characteristics, ovulation, or plasma hormone concentrations of EU-OV. No between-group differences ( P > 0.05) existed for rectal and skin temperatures or metabolic, cardiorespiratory, muscular endurance, or body composition variables. A significant difference post-HAPT in the onset temperature of local sweating, ORAL (37.2 ± 0.4°C) vs. DEPO (37.7 ± 0.2°C), suggested that steroid hormones influenced this adaptation. In summary, virtually all adaptations of ORAL and DEPO were similar to EU-OV, suggesting that exogenous reproductive hormones neither enhanced nor impaired the ability of women to complete 7–8 wk of strenuous physical training and heat acclimation.
A consensus sequence in the endothelin-B receptor second intracellular loop is required for NHE3 activation by endothelin-1
Authors: Laghmani Kamel , Sakamoto Aiji , Yanagisawa Masashi , Preisig Patricia A. , Alpern Robert J.
Published: December 2004

Endothelin-1 (ET-1) increases the activity of Na+/H+exchanger 3 (NHE3), the major proximal tubule apical membrane Na+/H+antiporter. This effect is seen in opossum kidney (OKP) cells expressing the endothelin-B (ETB) and not in cells expressing the endothelin-A (ETA) receptor. However, ET-1 causes similar patterns of protein tyrosine phosphorylation, adenylyl cyclase inhibition, and increases in cell [Ca2+] in ETA- and ETB-expressing OKP cells, implying that an additional mechanism is required for NHE3 stimulation by the ETBreceptor. The present studies used ETAand ETBreceptor chimeras and site-directed mutagenesis to identify the ET receptor domains that mediate ET-1 regulation of NHE3 activity. We found that binding of ET-1 to the ETAreceptor inhibits NHE3 activity, an effect for which the COOH-terminal tail is necessary and sufficient. ET-1 stimulation of NHE3 activity requires the COOH-terminal tail and the second intracellular loop of the ETBreceptor. Within the second intracellular loop, a consensus sequence was identified, KXXXVPKXXXV, that is required for ET-1 stimulation of NHE3 activity. This sequence suggests binding of a homodimeric protein that mediates NHE3 stimulation.
Global expression analysis of ECL cells in Mastomys natalensis gastric mucosa identifies alterations in the AP-1 pathway induced by gastrin-mediated transformation
Authors: Kidd M. , Hinoue T. , Eick G. , Lye K. D. , Mane S. M. , Wen Y. , Modlin I. M.
Published: December 2004

Enterochromaffin-like (ECL) cell hyperplasia and then irreversible neoplasia can be generated in the African rodent Mastomys natalensis using the H2 receptor blocker, loxtidine, for 8–16 wk. We used a GeneChip approach complemented by standard technologies to identify gene expression alterations in the gastric mucosa during gastrin-mediated ECL cell transformation. Gastric mucosa (mucosal scrapping) and ECL cell-enriched fractions were obtained from untreated Mastomys (controls) and from animals treated with loxtidine for 8 wk (hyperplasia). Tumor ECL cells were obtained by hand-dissection of gastric ECL cell nodules from animals treated with loxtidine for >16 wk and from a spontaneously developed ECL cell tumor. RNA was isolated, examined on rat U34A GeneChips, and comparison analysis was performed to identify altered gene expression. Alterations in gene expressions were examined further by immunohistochemistry, quantitative RT-PCR (Q-RT-PCR), sequencing and Western blot. GeneSpring analysis demonstrated alterations in few genes (<20) in hyperplastic and tumor mucosa. The histamine H1 receptor was consistently increased in proliferating mucosa. This gene change was confirmed by Q-RT-PCR. Other genes showing alterations included neural-(chromogranin A and somatostatin), cell-cycle-, and AP-1-associated genes. Immunostaining confirmed alterations in neural markers. Cluster analysis of ECL cell-enriched samples demonstrated that c- fos and junD were differently regulated. Q-RT-PCR and Western blot in prospectively collected gastric mucosal samples confirmed the differential expression of Fos and Jun. The negative regulators of AP-1, JunD, and Menin were decreased in tumor mucosa. A missense of unknown function was noted in the menin gene. Hypergastrinemia in an animal model of gastric carcinoids differentially altered the histamine type 1 receptor and gene expression and protein composition of AP-1. These results suggest that expression of this receptor and an altered composition of AP-1 with a loss of inhibition play a role in ECL cell transformation.
The geometry of some natural conjugacies in ℂn dynamics
Authors: Robertson John W.
Published: December 2004

We show that under some simple conditions a topological conjugacy h between two holomorphic self‐maps f1 and f2 of complex n‐dimensional projective space ℙn lifts canonically to a topological conjugacy H between the two corresponding polynomial self‐maps of ℂn+1, and this conjugacy relates the two Green functions of f1 and f2. These conjugacies are interesting because their geometry is not inherited entirely from the geometry of the conjugacy on ℙn. Part of the geometry of such a conjugacy is given (locally) by a complex‐valued function whose absolute value is determined by the Green functions for the two maps, but whose argument seems to appear out of thin air. We work out the local geometry of such conjugacies over the Fatou set and over Fatou varieties of the original map.
Rough singular integrals on product spaces
Authors: Al-Salman Ahmad , Al-Qassem Hussain
Published: December 2004

We study the mapping properties of singular integral operators defined by mappings of finite type. We prove that such singular integral operators are bounded on the Lebesgue spaces under the condition
that the singular kernels are allowed to be in certain block spaces.
Infinite matrices, wavelet coefficients and frames
Authors: Sheikh N. A. , Mursaleen M.
Published: December 2004

We study the action of A on f ∈ L2(ℝ) and on its wavelet coefficients, where is a double infinite matrix. We find the frame condition for A‐transform of f ∈ L2(ℝ) whose wavelet series expansion is known.
Transforming The "Market-Model University": Environmental Philosophy, Citizenship And The Recovery of the Humanities
Authors: Scott Dane
Published: December 2004

This paper addresses the problem of the declining status of philosophy and the humanities in higher education. These events have given rise to discussions of the "corporatization" of higher education and the dominance of the "Market-Model University." In the Market-Model University the chief goals are to teach marketable skills and develop marketable innovations. In responding to these developments, my thesis is that practical philosophy, exemplified by environmental philosophy, off ers direction for positive reforms that will revitalize philosophy and the humanities. (While my comments focus on philosophy, I believe much of what is said can apply to other fields in the humanities.) More specifically, they point to a "Citizen-Model University" as a positive alternative to the Market-Model. In the Citizen-Model University the chief goal is education for "citizenship". This focus in education will allow democratic societies to better meet the challenges of the twenty-first century. Such challenges are increasingly characterized by difficult decisions involving environmental problems (e.g., global warming) and technological developments (e.g., biotechnology). These kinds of problems cannot be left to the "invisible hand" of the market. They require democratic citizens capable of moral deliberation, leading to intelligent choices.
Catching the "Third Wave" of Democratization?: Debating Political Party Effectiveness in Africa Since 1980
Authors: McMahon Edward R.
Published: December 2004

Many observers believe that multi-party democracy increasingly represents the inevitable future of governance around the world, including Africa. Some countries such as South Africa, Ghana, Kenya, and Senegal have in fact made remarkable progress in instituting and moving toward consolidation of democratic systems. There has also been a history on the continent, however, of political systems that place de facto or de jure legal constraints on the ability of political parties to function. In fact, in recent years many African leaders have only grudgingly permitted multi-party politics under donor pressure. There remains a current of underlying skepticism toward political parties, and arguments exist against multi-party politics. This paper identifies and explains five key arguments. It then critiques them and determines that while individual elements of these arguments may have some validity, the conclusion that is drawn, i.e.that party activity should be constrained, if not prohibited, is not consonant with democratic governance. The final section presents suggestions of how weaknesses in political party functioning could be addressed without placing limits on the ability of parties to play their legitimate role in a democratic political process.
Age, Ethnicity, and Socioeconomic Patterns in Early Computer Use
Authors: Calvert Sandra L. , Rideout Victoria J. , Woolard Jennifer L. , Barr Rachel F. , Strouse Gabrielle A.
Published: December 2004

Parents were interviewed about the media habits of their 6-month to 6-year-old children. For children who had used computers, linear increases in computer usage occurred across this age range with a shift from using a computer on a parent’s lapat aboutage 21/2 to autonomous computer and mouse use at about age 31/2. There were almost no gender differences in early computer patterns. Families with higher incomes and higher education levels were more likely to own computers and to have Internet access from home. Latino families were least likely to own a computer; Latino and African American families were less likely than Caucasian families to have Internet access at home. Parents perceived computers favorably for children’s learning. No relationship was found between the frequency with which children play computer games and the likelihood that they can read, but increased nongame computer use was associated with increased likelihood of reading.
The Political Determinants of Economic Performance
Authors: Pinto Pablo M. , Timmons Jeffrey F.
Published: December 2004

The authors present and test a theory about the effects of political competition on the sources of economic growth. Using Mankiw, Romer, and Weil’s model of economic growth and data for roughly 80 countries, the authors show that political competition decreases the rate of physical capital accumulation and labor mobilization but increases the rate of human capital accumulation and (less conclusively) the rate of productivity change. The results suggest that political competition systematically affects the sources of growth, but those effects are cross-cutting, explainingwhy democracy itself may be ambiguous. These findingshelp clarify the debate about regime type and economic performance and suggest new avenues for research.
Are “Nondiscriminatory” Immigration Policies Reversible?
Authors: Joppke Christian
Published: December 2004

In the English-speaking settler states, the notion of “nondiscriminatory” immigration policy has the precise meaning of eschewing ethnicity, race, and national origins as selection criteria in the context of past policies that had blatantly resorted to them. There has been an interesting recent debate over whether the commitment to nondiscrimination has consolidated into a “structural feature of liberal democracy” (G. Freeman), or whether it is a conjunctural “feature of public discussion at certain times and places” (R. Brubaker), and thus could be easily reversed. Evidence from the United States and Australia can adjudicate this debate in favor of the structural position. Three factors are identified that shore up nondiscriminatory immigration policies: the general acceptance of the nondiscrimination norm, even by those who are opposed to some of its effects; the shrinking demographic possibility of ethnic selectivity “by subterfuge”; and the instantly mobilizeable memory of settler states’ racist pasts.
Legal Defeats—Political Wins
Authors: Dotan Yoav , Hofnung Menachem
Published: December 2004

Why do political parties and politicians turn to litigation instead of using political channels in their efforts to affect public policies? Over the past 20 years, there has been a noticeable trend in which Israeli parties and politicians have turned to the courts for intervention in national and internal party affairs, government policies, and even parliamentary procedures. The authors argue that this phenomenon is tied to the growth of open competition within political parties on one hand and reforms in the legal doctrines controlling access to litigation on the other. This study indicates that politicians seek litigation even when their chances of winning in court are marginal. According to the findings, politicians exhibit a lower propensity to seek out-of-court settlements than other kinds of litigants. The results suggest that politicians resort to litigation to challenge majoritarian policies and also because they gain considerable media exposure (regardless of the actual outcome of litigation), enhancing their political stature.