bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fate of a
Burkholderia pseudomallei
Lipopolysaccharide Mutant in the Mouse Macrophage Cell Line RAW 264.7: Possible Role for the O-Antigenic Polysaccharide Moiety of Lipopolysaccharide in Internalization and Intracellular Survival
Authors: Arjcharoen S. , Wikraiphat C. , Pudla M. , Limposuwan K. , Woods D. E. , Sirisinha S. , Utaisincharoen P. 
Published: June 2007

ABSTRACT

Burkholderia pseudomallei
is a facultative intracellular gram-negative bacterium that can survive and multiply inside macrophages. One of the mechanisms by which
B. pseudomallei
escapes macrophage killing is by interfering with the expression of inducible nitric oxide synthase (iNOS). However, the bacterial components that modulate antimicrobial activity of the macrophage have not been fully elucidated. In the present study, we demonstrated that
B. pseudomallei
strain SRM117, a lipopolysaccharide (LPS) mutant that lacks the O-antigenic polysaccharide moiety, was more susceptible to macrophage killing during the early phase of infection than the parental wild-type strain (1026b). Unlike the wild type, the LPS mutant could readily stimulate Y701-STAT-1 phosphorylation (pY701-STAT-1) and interferon-regulatory factor 1 (IRF-1) expression, both of which are essential transcription factors of iNOS. Neutralizing antibody against beta interferon was able to inhibit the phosphorylation of Y701-STAT-1 and the expression of IRF-1 and iNOS, all of which resulted in an increased rate of intracellular replication. These data suggest that the O-antigenic polysaccharide moiety of
B. pseudomallei
modulates the host cell response, which in turn controls the intracellular fate of
B. pseudomallei
inside macrophages.
Staphylococcus aureus
Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis
Authors: Zhu Yefei , Weiss Elizabeth C. , Otto Michael , Fey Paul D. , Smeltzer Mark S. , Somerville Greg A. 
Published: June 2007

ABSTRACT

Staphylococcus aureus
and
Staphylococcus epidermidis
are the leading causes of nosocomial infections in the United States and often are associated with biofilms attached to indwelling medical devices. Despite the importance of biofilms, there is very little consensus about the metabolic requirements of
S. aureus
during biofilm growth. To assess the metabolic requirements of
S. aureus
growing in a biofilm, we grew USA200 and USA300 clonal types in biofilm flow cells and measured the extraction and accumulation of metabolites. In spite of the genetic differences, both clonal types extracted glucose and accumulated lactate, acetate, formate, and acetoin, suggesting that glucose was catabolized to pyruvate that was then catabolized via the lactate dehydrogenase, pyruvate formate-lyase, and butanediol pathways. Additionally, both clonal types selectively extracted the same six amino acids (serine, proline, arginine, glutamine, glycine, and threonine) from the culture medium. These data and recent speculation about the importance of arginine in biofilm growth and the function of arginine deiminase in USA300 clones led us to genetically inactivate the sole copy of the arginine deiminase operon by deleting the arginine/ornithine antiporter gene (
arcD
) in the USA200 clonal type and to assess the effect on biofilm development and pathogenesis. Although inactivation of
arcD
did completely inhibit arginine transport and did reduce polysaccharide intercellular adhesin accumulation,
arcD
mutants formed biofilms and achieved cell densities in catheter infection studies that were equivalent to those for isogenic wild-type strains.
Genetic Basis for the New Pneumococcal Serotype, 6C
Authors: Park In Ho , Park Saeyoung , Hollingshead Susan K. , Nahm Moon H. 
Published: June 2007

ABSTRACT

We have recently reported a new pneumococcal serotype (6C), which is closely related to serotype 6A (I. H. Park et al., J. Clin. Microbiol. 45:1225-1233, 2007). To investigate the genetic basis for serotype 6C, we studied the capsule gene loci of 14 6C isolates from three different continents, including one isolated in Alabama 27 years ago. The
wciN
region of all 6C isolates has a 1,029-bp-long sequence that replaces the 1,222-bp-long sequence of the 6A
wciN
region. This recombination event has created a new 1,125-bp-long open reading frame which encodes a product that is also homologous to glycosyl transferases. Flanking this introduced gene is 300 bp upstream and 100 bp downstream with only about 90% homology with 6A and which is identical in all 6C isolates. Transfer of the
wciN
region converts 6A to 6C. Determination of the DNA sequence of the entire capsule gene locus of one 6C isolate showed that the 6C capsule gene locus is almost identical (>98% homologous) to that of 6A except for the
wciN
region. These findings indicate that the 6C capsule type originated more than 27 years ago by a single recombination event in a 6A locus in which 6A
wciN
was replaced by a gene of unknown origin.
The Localization of Protein Kinase Cδ in Different Subcellular Sites Affects Its Proapoptotic and Antiapoptotic Functions and the Activation of Distinct Downstream Signaling Pathways
Authors: Gomel Ruth , Xiang Cunli , Finniss Susan , Lee Hae Kyung , Lu Wei , Okhrimenko Hana , Brodie Chaya 
Published: June 2007

AbstractProtein kinase Cδ (PKCδ) regulates cell apoptosis and survival in diverse cellular systems. PKCδ translocates to different subcellular sites in response to apoptotic stimuli; however, the role of its subcellular localization in its proapoptotic and antiapoptotic functions is just beginning to be understood. Here, we used a PKCδ constitutively active mutant targeted to the cytosol, nucleus, mitochondria, and endoplasmic reticulum (ER) and examined whether the subcellular localization of PKCδ affects its apoptotic and survival functions. PKCδ-Cyto, PKCδ-Mito, and PKCδ-Nuc induced cell apoptosis, whereas no apoptosis was observed with the PKCδ-ER. PKCδ-Cyto and PKCδ-Mito underwent cleavage, whereas no cleavage was observed in the PKCδ-Nuc and PKCδ-ER. Similarly, caspase-3 activity was increased in cells overexpressing PKCδ-Cyto and PKCδ-Mito. In contrast to the apoptotic effects of the PKCδ-Cyto, PKCδ-Mito, and PKCδ-Nuc, the PKCδ-ER protected the cells from tumor necrosis factor–related apoptosis-inducing ligand–induced and etoposide-induced apoptosis. Moreover, overexpression of a PKCδ kinase-dead mutant targeted to the ER abrogated the protective effect of the endogenous PKCδ and increased tumor necrosis factor–related apoptosis-inducing ligand–induced apoptosis. The localization of PKCδ differentially affected the activation of downstream signaling pathways. PKCδ-Cyto increased the phosphorylation of p38 and decreased the phosphorylation of AKT and the expression of X-linked inhibitor of apoptosis protein, whereas PKCδ-Nuc increased c-Jun NH2-terminal kinase phosphorylation. Moreover, p38 phosphorylation and the decrease in X-linked inhibitor of apoptosis protein expression played a role in the apoptotic effect of PKCδ-Cyto, whereas c-Jun NH2-terminal kinase activation mediated the apoptotic effect of PKCδ-Nuc. Our results indicate that the subcellular localization of PKCδ plays important roles in its proapoptotic and antiapoptotic functions and in the activation of downstream signaling pathways. (Mol Cancer Res 2007;5(6):627–39)
A Possible Link between the Weddell Polynya and the Southern Annular Mode*
Authors: Gordon Arnold L. , Visbeck Martin , Comiso Josefino C. 
Published: June 2007

Abstract
Shortly after the advent of the first imaging passive microwave sensor on board a research satellite an anomalous climate feature was observed within the Weddell Sea. During the years 1974–1976, a 250 × 103 km2 area within the seasonal sea ice cover was virtually free of winter sea ice. This feature, the Weddell Polynya, was created as sea ice formation was inhibited by ocean convection that injected relatively warm deep water into the surface layer. Though smaller, less persistent polynyas associated with topographically induced upwelling at Maud Rise frequently form in the area, there has not been a reoccurrence of the Weddell Polynya since 1976. Archived observations of the surface layer salinity within the Weddell gyre suggest that the Weddell Polynya may have been induced by a prolonged period of negative Southern Annular Mode (SAM). During negative SAM the Weddell Sea experiences colder and drier atmospheric conditions, making for a saltier surface layer with reduced pycnocline stability. This condition enables Maud Rise upwelling to trigger sustained deep-reaching convection associated with the polynya. Since the late 1970s SAM has been close to neutral or in a positive state, resulting in warmer, wetter conditions over the Weddell Sea, forestalling repeat of the Weddell Polynya. A contributing factor to the Weddell Polynya initiation may have been a La Niña condition, which is associated with increased winter sea ice formation in the polynya area. If the surface layer is made sufficiently salty due to a prolonged negative SAM period, perhaps aided by La Niña, then Maud Rise upwelling meets with positive feedback, triggering convection, and a winter persistent Weddell Polynya.
Impact Mechanisms of Shallow Cumulus Convection on Tropical Climate Dynamics*
Authors: Neggers Roel A. J. , Neelin J. David , Stevens Bjorn 
Published: June 2007

Abstract
Subtropical shallow cumulus convection is shown to play an important role in tropical climate dynamics, in which convective mixing between the atmospheric boundary layer and the free troposphere initiates a chain of large-scale feedbacks. It is found that the presence of shallow convection in the subtropics helps set the width and intensity of oceanic ITCZs, a mechanism here termed the shallow cumulus humidity throttle because of the control exerted on the moisture supply to the deep convection zones. These conclusions are reached after investigations based on a tropical climate model of intermediate complexity, with sufficient vertical degrees of freedom to capture (i) the effects of shallow convection on the boundary layer moisture budget and (ii) the dependency of deep convection on the free-tropospheric humidity. An explicit shallow cumulus mixing time scale in this simple parameterization is varied to assess sensitivity, with moist static energy budget analysis aiding to identify how the local effect of shallow convection is balanced globally. A reduction in the mixing efficiency of shallow convection leads to a more humid atmospheric mixed layer, and less surface evaporation, with a drier free troposphere outside of the convecting zones. Advection of drier free-tropospheric air from the subtropics by transients such as dry intrusions, as well as by mean inflow, causes a substantial narrowing of the convection zones by inhibition of deep convection at their margins. In the tropical mean, the reduction of convection by this narrowing more than compensates for the reduction in surface evaporation. Balance is established via a substantial decrease in tropospheric temperatures throughout the Tropics, associated with the reduction in convective heating. The temperature response—and associated radiative contribution to the net flux into the column—have broad spatial scales, while the reduction of surface evaporation is concentrated outside of the convecting zones. This results in differential net flux across the convecting zone, in a sense that acts to destabilize those areas that do convect. This results in stronger large-scale convergence and more intense convection within a narrower area. Finally, mixed layer ocean experiments show that in a coupled ocean–atmosphere system this indirect feedback mechanism can lead to SST differences up to +2 K between cases with different shallow cumulus mixing time, tending to counteract the direct radiative impact of low subtropical clouds on SST.
Warming of the North Pacific Ocean: Local Air–Sea Coupling and Remote Climatic Impacts
Authors: Wu Lixin , Li Chun 
Published: June 2007

Abstract
In this paper, global climatic response to the North Pacific oceanic warming is investigated in a series of coupled ocean–atmosphere modeling experiments. In the model, an idealized heating is imposed over the North Pacific Ocean, while the ocean and atmosphere remain fully coupled both locally and elsewhere. The model explicitly demonstrates that the North Pacific oceanic warming can force a significant change of the atmospheric circulation with a strong seasonal dependence. The seasonal marching of the atmospheric response over the North Pacific is characterized by a quasi-baratropic warm ridge in early winter, a transition to a quasi-baratropic warm trough in late winter, and then to a baroclinic response in summer with a trough and ridge, respectively, in the lower and upper troposphere. The North Pacific warming also forces a significant remote response over the tropical Pacific. In winter, the tropical Pacific response is characterized by a nearly uniform warming coupled with anomalous southerly cross-equatorial winds, while in summer it is dominated by an enhanced zonal SST gradient and anomalous equatorial easterlies. The tropical warming tends to be associated with a reduction of the upper-ocean meridional overturning circulation and equatorial ocean dynamics associated with a reduction of the Hadley circulation and the surface coupled wind–evaporation–SST feedback. The resulting tropical warming can further intensify the seasonal marching of the North Pacific atmospheric response. The global impacts of the North Pacific warming are also discussed.
ENSO Impact on the Space–Time Evolution of the Regional Asian Summer Monsoons
Authors: Lim Young-Kwon , Kim Kwang-Yul 
Published: June 2007

Abstract
This study investigates how ENSO affects the space–time evolution of the Asian summer monsoon (ASM) precipitation and synoptic variables on a 5-day resolution over the entire ASM area. Cyclostationary EOF and regression methods were used to investigate the detailed evolution features associated with ENSO during the prominent life cycle of the ASM (21 May–17 September). This ENSO mode is identified as the third largest component (next to the seasonal cycle and the intraseasonal oscillations with a 40–50-day period) of the ASM rainfall variation.
The ENSO mode reveals that the individual regional monsoons over the ASM domain respond to ENSO in a complex manner. 1) Under the El Niño condition, the early monsoon stage over India, the Bay of Bengal, and the Indochina peninsula is characterized by rainfall deficit, along with a delayed monsoon onset by one or two pentads. This is the result of weakened diabatic heating over the Asian continent and meridional pressure gradient over the Indian Ocean, causing a weak low-tropospheric westerly monsoonal flow and the ensuing moisture transport decrease toward the regional monsoon areas. Onsets of the subsequent regional monsoons are delayed successively by this poorly developed ASM system in the early stage. 2) The Walker circulation anomaly persistently induces an enhanced subsidence over the Maritime Continent, resulting in a drought condition over this region for the entire ASM period. 3) The Hadley circulation anomaly linked to the Walker circulation anomaly over the Tropics drives a rising motion over the subtropical western Pacific, resulting in a wetter south China monsoon. The negative sea level pressure anomaly over the subtropical western Pacific associated with this anomalous Hadley circulation provides an unfavorable condition for the moisture transport toward East Asia, causing drier monsoons over north China, Japan, and Korea regions. 4) This negative sea level pressure anomaly intrudes into India, the Bay of Bengal, and the Indochina peninsula during late July and early August, developing a brief wet period over these regions. In contrast, the physical changes including the onset variation and the monsoon strength addressed above are reversed during La Niña events.
In reality, the observed ASM rainfall anomaly does not necessarily follow the ENSO-related patterns addressed above because of other impacts contributing to the rainfall variations. Although the impact of ENSO is moderately important, a comparison with other impacts demonstrates that the rainfall variations are controlled more by regional-scale intraseasonal oscillations.
Variability and Singularity of Seoul, South Korea, Rainy Season (1778–2004)
Authors: Wang Bin , Jhun Jong-Ghap , Moon Byung-Kwon 
Published: June 2007

Abstract
The 227-yr daily precipitation record gathered for Seoul, South Korea, represents one of the longest instrumental measurements, which provides an exceptional opportunity for detecting climate singularity (a property of phase locking to annual cycle) of extreme weather events and multidecadal–centennial variability of the rainy season structure. From late June to early September, the occurrence of heavy rain events shows a climatological quasi-biweekly oscillation. The rainy season characteristics, including the dates of onset, retreat, summit, and the duration, all show significant centennial variations. The rainy season summit shows a tendency toward delayed occurrence, which changed from the 37th pentad (P37; 30 June–4 July) during the 1778–1807 period to P44 (4–8 August) during the 1975–2004 period. The amplitude of the interannual (2–6 yr) variation of summer precipitation shows a prominent fluctuation with a 50-yr rhythm. A notable climatological break (around 9–13 August) divides the rainy season into a changma (Korean for continuous rain period) and a post-changma period. The major modes of subseasonal variability of the rainy season are characterized by an advanced changma and an enhanced post-changma, respectively. The former is dominated by biennial variation, whereas the latter has a major 5-yr spectral peak, suggesting that the processes leading to their variability are different. The occurrence of severe drought events exhibits a 4-yr spectral peak along with large power on a centennial time scale, while the severe flood events have a spectral peak at 3 and 19 yr, respectively. The remarkable climate variability in Seoul rainfall suggests that trends detected by using a 50-yr-or-shorter precipitation record likely reflect natural variability.
Tropical Cyclone Changes in the Western North Pacific in a Global Warming Scenario
Authors: Stowasser Markus , Wang Yuqing , Hamilton Kevin 
Published: June 2007

Abstract
The influence of global warming on the climatology of tropical cyclones in the western North Pacific basin is examined using the high-resolution International Pacific Research Center (IPRC) regional climate model forced by ocean temperatures and horizontal boundary fields taken from the NCAR Community Climate System Model version 2 (CCSM2) coupled global climate model. The regional model is first tested in 10 yr of simulation with boundary forcing taken from observations and is shown to produce a reasonably good representation of the observed statistics of tropical cyclone numbers and locations. The model was then run for 10 yr with forcing from a present-day control run of the CCSM2 and then for 10 yr with forcing fields taken from the end of a long run with 6 times the present-day atmospheric CO2 concentration. The global-mean surface air temperature warming in the perturbed run is 4.5 K, while the surface warming in the tropical western North Pacific is about 3 K. The results of these experiments reveal no statistically significant change in basinwide tropical cyclone numbers in the peak season from July to October in response to the CO2 increase. However, a pronounced and statistically significant increase in tropical cyclone occurrence in the South China Sea is found. While the basinwide total number of storms remains nearly unchanged in the warm climate, there is a statistically significant increase in the average strength of the cyclones and in the number of the storms in the strongest wind categories.
Australian Rainfall and Surface Temperature Variations Associated with the Southern Hemisphere Annular Mode
Authors: Hendon Harry H. , Thompson David W. J. , Wheeler Matthew C. 
Published: June 2007

Abstract
Daily variations in Australian rainfall and surface temperature associated with the Southern Hemisphere annular mode (SAM) are documented using observations for the period 1979–2005. The high index polarity of the SAM is characterized by a poleward contraction of the midlatitude westerlies. During winter, the high index polarity of the SAM is associated with decreased daily rainfall over southeast and southwest Australia, but during summer it is associated with increased daily rainfall on the southern east coast of Australia and decreased rainfall in western Tasmania. Variations in the SAM explain up to ∼15% of the weekly rainfall variance in these regions, which is comparable to the variance accounted for by the El Niño–Southern Oscillation, especially during winter. The most widespread temperature anomalies associated with the SAM occur during the spring and summer seasons, when the high index polarity of the SAM is associated with anomalously low maximum temperature over most of central/eastern subtropical Australia. The regions of decreased maximum temperature are also associated with increased rainfall. Implications for recent trends in Australian rainfall and temperature are discussed.
West African Storm Tracks and Their Relationship to Atlantic Tropical Cyclones
Authors: Hopsch Susanna B. , Thorncroft Chris D. , Hodges Kevin , Aiyyer Anantha 
Published: June 2007

Abstract
The automatic tracking technique used by Thorncroft and Hodges has been used to identify coherent vorticity structures at 850 hPa over West Africa and the tropical Atlantic in the 40-yr ECMWF Re-Analysis. The presence of two dominant source regions, north and south of 15°N over West Africa, for storm tracks over the Atlantic was confirmed. Results show that the southern storm track provides most of the storms that reach the main development region where most tropical cyclones develop. There exists marked seasonal variability in location and intensity of the storms leaving the West African coast, which may influence the likelihood of downstream intensification and longevity.
There exists considerable year-to-year variability in the number of West African storm tracks, both in numbers over the land and continuing out over the tropical Atlantic Ocean. While the low-frequency variability is well correlated with Atlantic tropical cyclone activity, West African rainfall, and SSTs, the interannual variability is found to be uncorrelated with these. In contrast, variance of the 2–6-day-filtered meridional wind, which provides a synoptic-scale measure of African easterly wave activity, shows a significant, positive correlation with tropical cyclone activity at interannual time scales.