Salmonella pathogenicity island 2 mediates protection of intracellular Salmonella from reactive nitrogen intermediates.

Salmonella typhimurium causes an invasive disease in mice that has similarities to human typhoid. A type III protein secretion system encoded by Salmonella pathogenicity island 2 (SPI2) is essential for virulence in mice, as well as survival and multiplication within macrophages. Reactive nitrogen intermediates (RNI) synthesized by inducible nitric oxide synthase (iNOS) are involved in the control of intracellular pathogens, including S. typhimurium. We studied the effect of Salmonella infection on iNOS activity in macrophages. Immunofluorescence microscopy demonstrated efficient colocalization of iNOS with bacteria deficient in SPI2 but not wild-type Salmonella, and suggests that the SPI2 system interferes with the localization of iNOS and Salmonella. Furthermore, localization of nitrotyrosine residues in the proximity was observed for SPI2 mutant strains but not wild-type Salmonella, indicating that peroxynitrite, a potent antimicrobial compound, is excluded from Salmonella-containing vacuoles by action of SPI2. Altered colocalization of iNOS with intracellular Salmonella required the function of the SPI2-encoded type III secretion system, but not of an individual "Salmonella translocated effector." Inhibition of iNOS increased intracellular proliferation of SPI2 mutant bacteria and, to a lesser extent, of wild-type Salmonella. The defect in systemic infection of a SPI2 mutant strain was partially restored in iNOS(-/-) mice. In addition to various strategies to detoxify RNI or repair damage due to RNI, avoidance of colocalization with RNI is important in adaptation of a pathogen to an intracellular life style.

The influence of school smoking policy and school prevention programs on the smoking behaviour of high school students in Prince Edward Island, Canada

The aim of the study was to examine the influence of school smoking policy and school smoking prevention programs on the smoking behaviour of students in high schools in Prince Edward Island using the School Health Action Planning Evaluation System (SHAPES). A total sample included 13,131 observations of students in grades 10-12 in ten high schools in Prince Edward Island over three waves of data collection (1999, 2000, and 2001). Changes in prevalence of smoking and factors influencing smoking behaviour were analyzed using descriptive statistics and Chi-Square tests. Multi-level logistic regression analyses were used to examine how both school and student characteristics were associated with smoking behaviour (I, II, III, IV). Since students were located within schools, a basic 2-level nested structure was used in which individual students (level 1) were nested within schools (level 2). For grade 12 students, the combination of both school policies and programs was not associated with the risk of smoking and the presence of the new policy was not associated with decreased risk of smoking, unless there were clear rules in place (I). For the grade 10 study, (II) schools with both policies and programs were not associated with decreased risk of smoking. However, the smoking behaviour of older students (grade 12) at a school was associated with younger students’ (grade 10) smoking behaviour. Students first enrolled in a high school in grade 9, rather than grade 10, were at increased risk of occasional smoking. For students who transitioned from grade 10 to 12 (III), close friends smoking had a substantial influence on smoking behaviour for both males and females (III). Having one or more close friends who smoke (Odds Ratio (OR) = 37.46; 95% CI = 19.39 to 72.36), one or more smokers in the home (OR = 2.35; 95% CI = 1.67 to 3.30) and seeing teachers and staff smoking on or near school property (OR=1.78; 95% CI = 1.13 to 2.80), were strongly associated with increased risk of smoking for grade 12 students. Smoking behaviour increased for both junior (Group 1) and senior (Group 2) students (IV). Group 1 students indicated a greater decrease in smoking behaviour and factors influencing smoking behaviour compared to those of Group 2. Students overestimating the percentage of youth their age who smoke was strongly associated with increased likelihood of smoking. Smoking rates showed a decreasing trend (1999, 2000, and 2001). However, policies and programs alone were not successful in influencing smoking behaviour of youth. Rather, factors within the students and schools contextual environment influenced smoking behaviour. Comprehensive approaches are required for school-based tobacco prevention interventions. Keywords: schools, policy, programs, smoking prevention, adolescents Subject Terms: school-based programming, public health, health promotion

Shrewd alliances: mixed foraging associations between treeshrews,greater racket-tailed drongos and sparrowhawks on Great Nicobar Island, India

Mixed-species foraging associations may form to enhance feeding success or to avoid predators. We report the costs and consequences of an unusual foraging association between an endemic foliage gleaning tupaid (Nicobar treeshrew Tupaia nicobarica) and two species of birds; one an insectivorous commensal (greater racket-tailed drongo Dicrurus paradiseus) and the other a diurnal raptor and potential predator (Accipiter sp.). In an alliance driven, and perhaps engineered, by drongos, these species formed cohesive groups with predictable relationships. Treeshrew breeding pairs were found more frequently than solitary individuals with sparrowhawks and were more likely to tolerate sparrowhawks in the presence of drongos. Treeshrews maintained greater distances from sparrowhawks than drongos, and permitted the raptors to come closer when drongos were present. Treeshrew foraging rates declined in the presence of drongos; however, the latter may provide them predator avoidance benefits. The choice of the raptor to join the association is intriguing; particular environmental resource states may drive the evolution of such behavioural strategies. Although foraging benefits seem to be the primary driver of this association, predator avoidance also influences interactions, suggesting that strategies driving the formation of flocks may be complex and context dependent with varying benefits for different actors.

Impact of energy quantisation in single electron transistor island on hybrid complementary metal oxide semiconductor-single electron transistor integrated circuits

For the first time, the impact of energy quantisation in single electron transistor (SET) island on the performance of hybrid complementary metal oxide semiconductor (CMOS)-SET transistor circuits has been studied. It has been shown through simple analytical models that energy quantisation primarily increases the Coulomb Blockade area and Coulomb Blockade oscillation periodicity of the SET device and thus influences the performance of hybrid CMOS-SET circuits. A novel computer aided design (CAD) framework has been developed for hybrid CMOS-SET co-simulation, which uses Monte Carlo (MC) simulator for SET devices along with conventional SPICE for metal oxide semiconductor devices. Using this co-simulation framework, the effects of energy quantisation have been studied for some hybrid circuits, namely, SETMOS, multiband voltage filter and multiple valued logic circuits. Although energy quantisation immensely deteriorates the performance of the hybrid circuits, it has been shown that the performance degradation because of energy quantisation can be compensated by properly tuning the bias current of the current-biased SET devices within the hybrid CMOS-SET circuits. Although this study is primarily done by exhaustive MC simulation, effort has also been put to develop first-order compact model for SET that includes energy quantisation effects. Finally, it has been demonstrated that one can predict the SET behaviour under energy quantisation with reasonable accuracy by slightly modifying the existing SET compact models that are valid for metallic devices having continuous energy states.

Greater Bangalore: Emerging Urban Heat Island

Bangalore is experiencing unprecedented urbanisation and sprawl in recent times due to concentrated developmental activities with impetus on industrialisation for the economic development of the region. This concentrated growth has resulted in the increase in population and consequent pressure on infrastructure, natural resources and ultimately giving rise to a plethora of serious challenges such as climate change, enhanced green-house gases emissions, lack of appropriate infrastructure, traffic congestion, and lack of basic amenities (electricity, water, and sanitation) in many localities, etc. This study shows that there has been a growth of 632% in urban areas of Greater Bangalore across 37 years (1973 to 2009). Urban heat island phenomenon is evident from large number of localities with higher local temperatures. The study unravels the pattern of growth in Greater Bangalore and its implication on local climate (an increase of ~2 to 2.5 ºC during the last decade) and also on the natural resources (76% decline in vegetation cover and 79% decline in water bodies), necessitating appropriate strategies for the sustainable management.

Effectors of Salmonella pathogenicity island 2: An island crucial to the life of Salmonella

The tug of war between a pathogen and its host has been one of the most amazing stories in the field of microbial pathogenesis for ages. The strongest known species of all living organisms is the Homo sapiens and yet it is incredible how a pathogen of the size of few microns is smart enough to defeat this mightiest group of survivors. It is of utmost interest to understand the mechanisms behind the successful habitation of a pathogen inside the ever-resisting and complicate human body. Numerous examples of diseases caused by such pathogens exist which intrigues us to venture in the world of host-pathogen interactions.

Coral diseases are major contributors to coral mortality in Shingle Island, Gulf of Mannar, southeastern India

The present study reports coral mortality, driven primarily by coral diseases, around Shingle Island, Gulf of Mannar (GOM), Indian Ocean. In total, 2910 colonies were permanently monitored to assess the incidence of coral diseases and consequent mortality for 2 yr. Four types of lesions consistent with white band disease (WBD), black disease (BD), white plaque disease (WPD), and pink spot disease (PSD) were recorded from 4 coral genera: Montipora, Pocillopora, Acropora, and Porites. Porites were affected by 2 disease types, while the other 3 genera were affected by only 1 disease type. Overall disease prevalence increased from 8% (n = 233 colonies) to 41.9% (n = 1219) over the 2 yr study period. BD caused an unprecedented 100% mortality in Pocillopora, followed by 20.4 and 13.1% mortality from WBD in Montipora and Acropora, respectively. Mean disease progression rates of 0.8 +/- 1.0 and 0.6 +/- 0.5 cm mo(-1) over live coral colonies were observed for BD and WBD. Significant correlations between temperature and disease progression were observed for BD (r = 0.86, R-2 = 0.75, p < 0.001) and WBD (R-2 = 0.76, p < 0.001). This study revealed the increasing trend of disease prevalence and progression of disease over live coral in a relatively limited study area; further study should investigate the status of the entire coral reef in the GOM and the role of diseases in reef dynamics.

Salmonella methylglyoxal detoxification by STM3117-encoded lactoylglutathione lyase affects virulence in coordination with Salmonella pathogenicity island 2 and phagosomal acidification

Intracellular pathogens such as Salmonella enterica serovar Typhimurium (S. Typhimurium) manipulate their host cells through the interplay of various virulence factors. A multitude of such virulence factors are encoded on the genome of S. Typhimurium and are usually organized in pathogenicity islands. The virulence-associated genomic stretch of STM3117-3120 has structural features of pathogenicity islands and is present exclusively in non-typhoidal serovars of Salmonella. It encodes metabolic enzymes predicted to be involved in methylglyoxal metabolism. STM3117-encoded lactoylglutathione lyase significantly impacts the proliferation of intracellular Salmonella. The deletion mutant of STM3117 (Delta lgl) fails to grow in epithelial cells but hyper-replicates in macrophages. This difference in proliferation outcome was the consequence of failure to detoxify methylglyoxal by Delta lgl, which was also reflected in the form of oxidative DNA damage and upregulation of kefB in the mutant. Within macrophages, the toxicity of methylglyoxal adducts elicits the potassium efflux channel (KefB) in the mutant which subsequently modulates the acidification of mutant-containing vacuoles (MCVs). The perturbation in the pH of the MCV milieu and bacterial cytosol enhances the Salmonella pathogenicity island 2 translocation in Delta lgl, increasing its net growth within macrophages. In epithelial cells, however, the maturation of Delta lgl-containing vacuoles were affected as these non-phagocytic cells maintain less acidic vacuoles compared to those in macrophages. Remarkably, ectopic expression of Toll-like receptors 2 and 4 on epithelial cells partially restored the survival of Delta lgl. This study identified a novel metabolic enzyme in S. Typhimurium whose activity during intracellular infection within a given host cell type differentially affected the virulence of the bacteria.

An island called India: phylogenetic patterns across multiple taxonomic groups reveal endemic radiations

Island systems from around the world have provided fascinating opportunities for studies pertaining to various evolutionary processes. One recurring feature of isolated islands is the presence of endemic radiations. In this regard, the Indian subcontinent is an interesting entity given it has been an island during much of its history following separation from Madagascar and currently is isolated from much of Eurasia by the Himalayas in the north and the Indian Ocean in the south. Not surprisingly, recent molecular studies on a number of endemic taxa from India have reported endemic radiations. These studies suggest that the uniqueness of Indian biota is not just due to its diverse origin, but also due to evolution in isolation. The isolation of India has generated some peculiarities typically seen on oceanic islands. However, these patterns might be confined to, groups with low dispersal ability.

Co-ordination of pathogenicity island expression by the BipA GTPase in enteropathogenic Escherichia coli (EPEC).

BipA is a novel member of the ribosome binding GTPase superfamily and is widely distributed in bacteria and plants. We report here that it regulates -multiple cell surface- and virulence-associated -components in the enteropathogenic Escherichia coli (EPEC) strain E2348/69. The regulated components include bacterial flagella, the espC pathogenicity island and a type III secretion system specified by the locus of enterocyte effacement (LEE). BipA positively regulated the espC and LEE gene clusters through transcriptional control of the LEE-encoded regulator, Ler. Additionally, it affected the pattern of proteolysis of intimin, a key LEE-encoded adhesin specified by the LEE. BipA control of the LEE operated independently of the previously characterized regulators Per, integration host factor and H-NS. In contrast, it negatively regulated the flagella-mediated motility of EPEC and in a Ler-independent manner. Our results indicate that the BipA GTPase functions high up in diverse regulatory cascades to co-ordinate the expression of key pathogenicity islands and other virulence-associated factors in E. coli.

Photographic analysis of natural and impounded salt marsh in the vicinity of Merritt Island, Florida

Qualitative analyses of available photographs and maps of Merritt Island, Florida provide a large-scale, historical perspective of ecological changes of the marshes in the vicinity. Sites that deserve closer scrutiny can be identified. Secondarily, such an analysis provides a geographical orientation essential for communication not only between newcomers and those familiar with the area, but also among those familiar with the area but who refer to sites by differing methods. Photographs and maps from various sources were examined. Below are listed what we consider to be the most useful subset of these for ecological and geographical assessment of salt marsh impoundments on Merritt Island, Florida. (Document has 25 pages.)