bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of a two‐step natural organic acid treatment on microbial activity and lipid damage during blue whiting (Micromesistius poutassou) chilling
Authors: Sanjuás‐Rey Minia , García‐Soto Bibiana , Barros‐Velázquez Jorge , Fuertes‐Gamundi José R. , Aubourg Santiago P.
Published: February 2011

Quality loss inhibition in chilled blue whiting (Micromesistius poutassou) was investigated. For it, a natural organic acid‐mixture including ascorbic, citric and lactic acids was applied in a two‐step processing strategy: (i) as an aqueous dipping medium previous to chilling storage and, (ii) included in the flake ice employed as chilling system. As a result of the acid‐mixture addition, a partial inhibition of microbial and biochemical mechanisms involved in the quality loss was obtained. Thus, aerobe and psychrotrophe counts in treated fish showed lower ranges (2.07–4.15 and 2.43–4.39 log CFU g−1, respectively) than control fish (2.64–5.83 and 2.30–5.30 log CFU g−1, respectively). Sensory analysis revealed that treated fish was still acceptable at the end of the experiment (day 9), while control fish was rejected at this time. Lipid hydrolysis (free fatty acid formation) proved to be more limiting of fish quality than lipid oxidation (peroxide and thiobarbituric acid‐reactive substance formation).
Chemical composition and sensory analysis of cheese whey‐based beverages using kefir grains as starter culture
Authors: Magalhães Karina Teixeira , Dias Disney Ribeiro , de Melo Pereira Gilberto Vinicius , Oliveira José Maria , Domingues Lucília , Teixeira José António , de Almeida e Silva João Batista , Schwan Rosane Freitas
Published: February 2011

The aim of the present work was to evaluate the use of the kefir grains as a starter culture for tradicional milk kefir beverage and for cheese whey‐based beverages production. Fermentation was performed by inoculating kefir grains in milk (ML), cheese whey (CW) and deproteinised cheese whey (DCW). Erlenmeyers containing kefir grains and different substrates were statically incubated for 72 h at 25 °C. Lactose, ethanol, lactic acid, acetic acid, acetaldehyde, ethyl acetate, isoamyl alcohol, isobutanol, 1‐propanol, isopentyl alcohol and 1‐hexanol were identified and quantified by high‐performance liquid chromatography and GC‐FID. The results showed that kefir grains were able to utilise lactose in 60 h from ML and 72 h from CW and DCW and produce similar amounts of ethanol (∼12 g L−1), lactic acid (∼6 g L−1) and acetic acid (∼1.5 g L−1) to those obtained during milk fermentation. Based on the chemical characteristics and acceptance in the sensory analysis, the kefir grains showed potential to be used for developing cheese whey‐based beverages.
Influence of extraction conditions on polyphenols content and cream constituents in black tea extracts
Authors: Chandini Shantha Kumar , Jaganmohan Rao Lingamallu , Subramanian Rangaswamy
Published: February 2011

Increase in water‐to‐tea ratio and extraction time increased polyphenols recovery as well as extractable‐solids‐yield (ESY) in black tea extracts. Polyphenols content‐in‐extracted solids (PES) used as a tea quality parameter, was significantly higher at 50:1 water‐to‐tea ratio and favourably improved only up to 60 min. Extending the extraction period beyond 40 min degraded theaflavins (TF) and also affected the recovery of major catechins. Although tea cream content showed a decrease with increase in water‐to‐tea ratio, the content was nearly the same (1.80–1.89%) in all these extracts when measured at a uniform 0.5% solids concentration. The extraction conditions displayed a similar influence on the other tea cream components, namely, caffeine, calcium, pectin and protein. The conditions optimised (50:1 water‐to‐tea ratio and 40 min) based on higher PES and TF/TR ratio gave a maximum PES of 0.566 g g−1 and TF of 0.46% (black tea) in the extract.
Fatigue, performance and the work environment: a survey of registered nurses
Authors: Barker Linsey M. , Nussbaum Maury A.
Published: February 2011

barker l.m. & nussbaum m.a. (2011) Fatigue, performance and the work environment: a survey of registered nurses.Journal of Advanced Nursing67(6), 1370–1382.

Aims. This paper is a report of a study of perceived levels of mental, physical and total fatigue, and also acute and chronic fatigue states, among registered nurses. Relationships between dimensions of fatigue and performance were investigated, as were differences in fatigue across levels of several demographic and work environment variables.

Background. Fatigue is a factor that has been linked to performance decrements in healthcare workers. As a result of the nature of their work, nurses may be particularly susceptible to multiple dimensions of fatigue, and their performance is closely linked to patient safety.

Methods. An online survey was used to measure mental, physical, and total fatigue dimensions, acute and chronic fatigue states, and performance. Participants were recruited via convenience sampling in cooperation with professional nursing organizations; 745 registered nurses completed the survey between February 2008 and April 2009.

Results. Reported mental fatigue levels were higher than physical fatigue levels, and acute fatigue levels were higher than chronic fatigue levels. All fatigue dimensions and states were negatively correlated with perceived performance. Longer shift lengths and hours worked per week were associated with increases in physical and total fatigue levels. Mental, physical and total fatigue levels also differed with shift schedule.

Conclusions. Fatigue levels were negatively correlated with performance, further supporting the role of fatigue in nurse performance. Work environment variables were strongly associated with differences in perceived levels of fatigue. By altering the work environment, it may thus be possible to reduce fatigue levels and the rates of medical errors.
Explaining grassland biomass – the contribution of climate, species and functional diversity depends on fertilization and mowing frequency
Authors: Bernhardt‐Römermann Markus , Römermann Christine , Sperlich Stefan , Schmidt Wolfgang
Published: February 2011

1. Grassland ecosystems are often used to generate biomass in temperate regions of the world. It is well known that biomass is influenced by climate and biodiversity, but the relative importance of these two factors in relation to management has not been widely studied. To recommend management treatments maximizing biomass yields we aim to quantify the relative effects of climate species and functional diversity on biomass in differently managed grasslands.

2. We studied the development of biomass yields over the last 37 years on a grassland site in Germany, with mowing at five frequencies (one to eight times per year), each with and without fertilization. We measured plant species richness (SR) and functional richness (FR) (the diversity of functional species properties) using presence–absence indices. We also measured species evenness (SE), functional evenness and functional divergence (FD) using abundance weighted indices. Climate was included as the mean temperature and sum of precipitation during the growing period. By relating biomass to the above‐mentioned climatic and biodiversity parameters, we extracted the contribution of these to biomass yields.

3. Biomass changed over time for all treatments and was maximal at intermediate mowing frequencies. Temporal changes in biomass were partly explained by climate and different aspects of biodiversity, although this differed significantly between treatments. The relative importance of precipitation was highest at high mowing frequencies; the contribution of temperature was highest on less disturbed, unfertilized plots. FR and SR influenced biomass changes in the most intensive disturbance regimes on unfertilized and fertilized plots respectively. FD was most important on intensively disturbed, fertilized plots. SE influenced biomass at low mowing frequencies.

4. Synthesis and applications. Climate, species and functional diversity influence annual grassland biomass yields but their importance depends on nutrient status and management frequency. Our results indicate that management treatments with intermediate disturbance regimes will maximize biomass yields in temperate environments. This recommendation may become even more important in the context of climate change: at intermediate mowing frequencies the influence of climatic variables on biomass is less important by comparison to different aspects of biodiversity.
Pubescent male students’ attitudes towards menstruation in Taiwan: implications for reproductive health education and school nursing practice
Authors: Chang Yu‐Ting , Hayter Mark , Lin Mei‐Ling
Published: February 2011

Aim.  To explore male students’ attitudes towards menstruation.

Background.  Menstruation is a biological event that is often surrounded by secrecy and social stigma that causes anxiety amongst many young girls. A key element of this is the attitudes of young males towards this reproductive health issue. However, the literature around what young males think and feel about menstruation is limited.

Design.  Qualitative.

Methods.  A sample of 27 male students aged between 10–12 years participated in five focus groups. Data were then subject to a thematic analysis.

Results.  Five themes emerged from the data analysis that reflected the boys’ feelings, experiences and attitudes towards menstruation: ‘A silent topic’, ‘An unimportant issue’, ‘Errant information about menstruation’. In addition, according to their experience, participants gradually came to see menstruation from the ‘menstrual stereotype’ viewpoint. In their social life, they made choices that resulted in gradually regulating their behaviour that affected their ‘relationships with girls’.

Conclusion.  Young boys have misguided knowledge about menstruation and this helps to perpetuate the stigma surrounding this element of reproductive health. Boys also express a desire to learn more but are often restricted in this by home and school. School nurses are the best placed professionals to address this issue.

Relevance to clinical practice.  Menstrual education with boys should take a greater prominence than it often does in sexual health education in schools. Such inclusion will provide boys with a balanced and accurate knowledge base and therefore help towards reducing the social stigma around menstruation that is often experienced by young girls.
Predation risk indirectly enhances survival of seaweed recruits but not intraspecific competition in an intermediate herbivore species
Authors: Molis Markus , Preuss Inken , Firmenich Annika , Ellrich Julius
Published: February 2011

1. Non‐consumptive predator effects are an important driver in predator–prey interactions. While indirect effects of predation risk shape interspecific species interactions, e.g. in fuelling trophic cascades, knowledge about non‐consumptive predator effects on intraspecific interactions among intimidated prey is scarce.

2. In laboratory experiments, we tested whether predation by male and female green crabs (Carcinus maenas) is stronger on small than on larger specimens of the periwinkle Littorina littorea, an important herbivore species in intertidal habitats of the temperate zone. Moreover, we asked whether size‐specific differences in predation‐induced mortality reflect as a stronger effect of predation risk (caused by nearby consuming crabs) on the foraging behaviour of more threatened periwinkles and ultimately on the recruitment success of the brown seaweed Fucus serratus. Furthermore, predator activity and prey abundance was measured in the field and the efficacy of predation risk on the survival of seaweed recruits was assessed in three field experiments with two different set‐ups (open plots and crab exclosures).

3. Male crabs consumed smaller periwinkles more often than larger conspecifics, while females refused periwinkles as food. In summer, 80–90% of periwinkles in the field attained a size at which crab predation was minimal in laboratory assays. The observed up to 15‐fold decrease in the consumption of seaweed recruits by periwinkles in the presence of nearby consuming crabs in laboratory assays was, however, independent of the size of periwinkles. Predation risk effects from the laboratory were only confirmed in field experiments using crab exclosures but not with open plots, suggesting an artefact due to trespassing by wild crabs in the open plot set‐up.

4. Synthesis. Predation risk may not change intraspecific competition for food in L. littorea. Yet, risk effects on foraging behaviour of periwinkles that experience a low threat of real predation indicate that non‐consumptive predator effects may affect prey population dynamics more strongly than consumptive predator effects. Thus predation risk effects may be indirectly beneficial for the survival of basal species like perennial seaweeds, as experimental evidence from field and laboratory experiments indicates.
Climate cues and resources interact to determine seed production by a masting species
Authors: Smaill Simeon J. , Clinton Peter W. , Allen Robert B. , Davis Murray R.
Published: February 2011

1. Mast seeding is the intermittent production of large quantities of seed across a perennial plant population. Such seeding events in many plant species are initiated by climatic cues, but whether these cues act solely as triggers or also via alterations to nutrient availability is unclear.

2. Here, we examine the effect of nitrogenous fertilization on the relationship between seed production in Nothofagus solandri var. cliffortioides and two climatic cues (rainfall and temperature) at specific stages in reproductive development from 1999 to 2008.

3. Foliar nitrogen concentrations were positively correlated with rainfall among years, suggesting rainfall was affecting nitrogen availability.

4. Seedfall mass in unfertilized stands was predominantly determined by rainfall during resource priming, while seed production in fertilized stands was more affected by temperature during floral primordia development. Similarly, seedfall mass in older stands, which contain greater internal nutrient reserves, was predominantly determined by temperature.

5. Synthesis. The results of this study demonstrate that the sensitivity of seed production to climatic cues can be altered by manipulation of resource availability and therefore establish that climatic cues involved in the synchronization of mast seeding can influence reproductive effort via an effect on resource availability. These results also indicate that alterations to resource availability have the potential to alter inter‐annual patterns of seed production, but further study is required to verify this finding.
The roles of environmental filtering and colonization in the fine‐scale spatial patterning of ground‐layer plant communities in north temperate deciduous forests
Authors: Burton Julia I. , Mladenoff David J. , Clayton Murray K. , Forrester Jodi A.
Published: February 2011

1. The majority of plant species in northern temperate deciduous forests are restricted to the ground layer, but the importance of colonization processes relative to environmental filtering in structuring spatial variation in ground‐layer plant communities is poorly understood.

2. Using multivariate analyses, structural equation modelling and geostatistics, we examined interactions among ground‐layer plant communities, the live overstorey and environmental gradients across a 70‐ to 90‐year‐old northern hardwood forest in Wisconsin (USA). We hypothesized that (i) fine‐scale variation is related to environmental filtering rather than dispersal limitation and colonization processes; and (ii) exogenous ‘site’ filters exert more control than the composition and structure of the overstorey.

3. A transition from communities of spring ephemerals to communities of evergreen‐dimorphic species is related to a hierarchy of controls driven by elevation, soil texture and associated effects on soil moisture, overstorey composition, and O‐horizon and soil properties. An orthogonal axis distinguished among sparse communities associated with high levels of soil moisture early in the growing season and rich communities of early summer forbs associated with increasing O‐horizon N:P and %Ca, and short‐distance dispersal mechanisms. Indirect effects of tree species are significant, but cumulatively less important than exogenous site filters.

4. Synthesis.The spatial patterning of ground‐layer plant communities is related to both environmental filtering and colonization. These patterns were related to species’ functional and dispersal characteristics, suggesting that processes structuring ground‐layer plant communities are not merely neutral. Loose regulation of environmental and resource gradients resulting in a coarse‐grained spatial patterning of plant communities observed in second‐growth forests may therefore be related to a simplification in overstorey composition and the absence of heterogeneity accumulating through gap dynamics.
Moving on from Metabolic Scaling Theory: hierarchical models of tree growth and asymmetric competition for light
Authors: Coomes David A. , Lines Emily R. , Allen Robert B.
Published: February 2011

1. Coomes & Allen (2009)showed that the Metabolic Scaling Theory of Plant Growth (MST‐PG) has no empirical support, because the only piece of confirmatory evidence was an analysis of a small and noisy data set from which it was impossible to draw strong inferences. Our re‐analyses showed that MST‐PG predictions were contained within very broad 95% confidence intervals, creating an illusion of close adherence to theoretical predictions. In a response to our paper,Stark, Bentley & Enquist (2010)acknowledge these shortcomings.

2.  We reasoned that MST‐PG makes inaccurate predictions because asymmetric competition for light is not included in the theoretical model. We argued that asymmetric competition has its greatest impact on small trees within populations, such that the mean size‐scaling relationship of the population has a greater exponent than that of trees growing without competitors (i.e. the slope predicted by MST‐PG).Stark, Bentley & Enquist (2010)appear to dispute this logic and criticize the statistical approach we developed to test our hypothesis.

3.  Here we use Bayesian hierarchical models (BHMs) to re‐examine three forest data sets, and find no support for MST‐PG. Based on a large data set from New Zealand, the majority of tall tree species have scaling exponents greater than predicted by MST‐PG, suggesting that asymmetric competition may have influenced the scaling relationships. Parameters for many small tree and shrub species were very poorly estimated, in part because their size ranges were narrow, so these species cannot be used to argue for, or against, MST‐PG.

4.  We hypothesize that scaling relationships are most affected by asymmetric competition in high‐productivity forests because, as many ecologists argue, competition for light is intense in such forests (the productivity‐dependent scaling hypothesis). We estimate growth scaling exponents forNothofagusforest sites which differed in above‐ground biomass (AGB) production. As predicted, scaling exponents were greater in sites with high AGB production and close to MST‐PG predictions in sites with low AGB production.

5. Synthesis.Competition from taller neighbours has strong effects on tree growth, particularly in forests growing in productive locations. We continue to advocate for the inclusion of asymmetric competition into general models of tree growth, mortality, recruitment and size structure.
Understanding belief using citation networks
Authors: Greenberg Steven A.
Published: February 2011

Citation is a powerful method for establishing belief. Published statements gain credibility when followed by citations. Citation in its purest form consists of the scholarly connection of authors' ideas and claims to existing literature, yet there are also non‐scholarly uses of citation that are best called citation distortions. Unfounded biomedical belief systems arising from citation distortions may become widely accepted as fact. The development of methodology for the study of citation distortions and belief systems regarding scientific claims was recently described. Here, I discuss further the methodological approaches to studying published scientific belief systems and identifying citation distortions.
Granulocyte colony‐stimulating factor for hepatitis C therapy‐associated neutropenia: systematic review and economic evaluation
Authors: Tandon P. , Doucette K. , Fassbender K. , Vandermeer B. , Durec T. , Dryden D. M.
Published: February 2011

Summary.  Hepatitis C virus (HCV) treatment requires maximal adherence to pegylated interferon (Peg‐IFN) and ribavirin to achieve a sustained virologic response (SVR). Neutropenia is the most common cause for Peg‐IFN dose reduction. Our objectives were to evaluate the effectiveness, safety and cost‐effectiveness of granulocyte colony‐stimulating factor (G‐CSF) versus Peg‐IFN dose reduction for HCV therapy‐associated neutropenia in treatment naïve adults. We conducted a systematic review to identify controlled trials and observational studies. Study selection, quality assessment and data extraction were completed independently by two investigators. Cost‐effectiveness and cost‐utility analyses compared G‐CSF with dose reduction. Nineteen studies were included. In one trial, the SVR for those receiving G‐CSF was 54.5% (95% CI: 34.7–73.1) compared with 26.3% (95% CI: 11.8–48.8) for dose reduction. The remaining studies were case series or retrospective cohorts and provided weak evidence for the relationship between SVR and G‐CSF. The risk of adverse events, including infection, associated with G‐CSF was low (13.1%; 95% CI: 8.0–20.8) and clinically insignificant. G‐CSF had an incremental cost‐effectiveness ratio of $41 701 per SVR achieved in genotype 1, and $16 115 per SVR achieved in genotype 2 or 3. Estimates were robust under a variety of resource and intervention scenarios. While administration of G‐CSF may enable patients to remain on or resume optimal HCV therapy, there was weak evidence that this improves the likelihood of SVR compared with dose reduction. Adverse effects of G‐CSF are mild. The economic evaluation was inconclusive.
Enhanced AFLP genome scans detect local adaptation in high‐altitude populations of a small rodent (Microtus arvalis)
Authors: FISCHER MARTIN C. , FOLL MATTHIEU , EXCOFFIER LAURENT , HECKEL GERALD
Published: February 2011

Adaptation to adverse environmental conditions such as high altitude requires physiological and/or morphological changes. Genome scans provide a means to identify the genetic basis of such adaptations without previous knowledge about the particular genetic variants or traits under selection. In this study, we scanned 3027 amplified fragment length polymorphisms (AFLP) in four populations of the common vole Microtus arvalis for loci associated with local adaptation and high altitude. We investigated voles from two populations at high elevation (∼2000 m a.s.l.) representing the upper limit of the altitudinal distribution of the species and two geographically close low‐altitude populations (<600 m a.s.l.). Statistical analysis incorporated a new Bayesian FST outlier approach specifically developed for AFLP markers, which considers the intensity of AFLP bands instead of mere presence/absence and allows to derive population‐based estimates of allele frequencies and FIS values. Computer simulations showed that this approach increases the statistical power of the detection of AFLP markers under selection almost to the power of single nucleotide polymorphism (SNP) data without compromising specificity. Our enhanced genome scan resulted in 20 prime candidate markers for positive selection, which show mostly extremely high allele frequency differences between the low‐ and high‐altitude populations. The comparison of global‐ and pairwise‐enhanced genome scans demonstrated further that very strong selective signatures may also be associated with single populations suggesting the importance of local adaptation in alpine populations of common voles.
The transcriptomic responses of the eastern oyster, Crassostrea virginica, to environmental conditions
Authors: CHAPMAN ROBERT W. , MANCIA ANNALAURA , BEAL MARION , VELOSO ARTUR , RATHBURN CHARLES , BLAIR ANNE , HOLLAND A. F. , WARR G. W. , DIDINATO GUY , SOKOLOVA INNA M. , WIRTH EDWARD F. , DUFFY EDWARD , SANGER DENISE
Published: February 2011

Understanding the mechanisms by which organisms adapt to environmental conditions is a fundamental question for ecology and evolution. In this study, we evaluate changes in gene expression of a marine mollusc, the eastern oyster Crassostrea virginica, associated with the physico‐chemical conditions and the levels of metals and other contaminants in their environment. The results indicate that transcript signatures can effectively disentangle the complex interactive gene expression responses to the environment and are also capable of disentangling the complex dynamic effects of environmental factors on gene expression. In this context, the mapping of environment to gene and gene to environment is reciprocal and mutually reinforcing. In general, the response of transcripts to the environment is driven by major factors known to affect oyster physiology such as temperature, pH, salinity, and dissolved oxygen, with pollutant levels playing a relatively small role, at least within the range of concentrations found in the studied oyster habitats. Further, the two environmental factors that dominate these effects (temperature and pH) interact in a dynamic and nonlinear fashion to impact gene expression. Transcriptomic data obtained in our study provide insights into the mechanisms of physiological responses to temperature and pH in oysters that are consistent with the known effects of these factors on physiological functions of ectotherms and indicate important linkages between transcriptomics and physiological outcomes. Should these linkages hold in further studies and in other organisms, they may provide a novel integrated approach for assessing the impacts of climate change, ocean acidification and anthropogenic contaminants on aquatic organisms via relatively inexpensive microarray platforms.
Stored sperm differs from ejaculated sperm by proteome alterations associated with energy metabolism in the honeybeeApis mellifera
Authors: POLAND VERONICA , EUBEL HOLGER , KING MICHAELA , SOLHEIM CORY , HARVEY MILLAR A. , BAER BORIS
Published: February 2011

Sperm are exposed to substantially different environments during their life history, such as seminal fluid or the female sexual tract, but remarkably little information is currently available about whether and how much sperm composition and function alters in these different environments. Here, we used the honeybeeApis melliferaand quantified differences in the abundance and activity of sperm proteins sampled either from ejaculates or from the female’s sperm storage organ. We find that stored and ejaculated sperm contain the same set of proteins but that the abundance of specific proteins differed substantially between ejaculated and stored sperm. Most proteins with a significant change in abundance are related to sperm energy metabolism. Enzymatic assays performed for a subset of these proteins indicate that specific protein activities differ between stored and ejaculated sperm and are typically higher in ejaculated compared to stored sperm. We provide evidence that the cellular machinery of sperm is plastic and differs between sperm within the ejaculate and within the female’s storage organ. Future work will be required to test whether these changes are a consequence of active adaptation or sperm senescence and whether they alter sperm performance in different chemical environments or impact on the cost of sperm storage by the female. However, these changes can be expected to influence sperm performance and therefore determine sperm viability or sperm competitiveness for storage or egg fertilization.
Dispersal strategies, secondary range expansion and invasion genetics of the nonindigenous round goby, Neogobius melanostomus, in Great Lakes tributaries
Authors: BRONNENHUBER JENNIFER E. , DUFOUR BRAD A. , HIGGS DENNIS M. , HEATH DANIEL D.
Published: February 2011

Dispersal strategies are important mechanisms underlying the spatial distribution and colonizing ability of all mobile species. In the current study, we use highly polymorphic microsatellite markers to evaluate local dispersal and colonization dynamics of the round goby (Neogobius melanostomus), an aquatic invader expanding its range from lake to river environments in its introduced North American range. Genetic structure, genotype assignment and genetic diversity were compared among 1262 round gobies from 20 river and four lake sites in three Great Lakes tributaries. Our results indicate that a combination of short‐distance diffusion and long‐distance dispersal, collectively referred to as ‘stratified dispersal’, is facilitating river colonization. Colonization proceeded upstream yearly (approximately 500 m/year; 2005–2009) in one of two temporal replicates while genetic structure was temporally stable. Contiguous dispersal from the lake was observed in all three rivers with a substantial portion of river fish (7.3%) identified as migrants. Genotype assignment indicated a separate introduction occurred upstream of the invasion front in one river. Genetic diversity was similar and relatively high among lake and recently colonized river populations, indicating that founder effects are mitigated through a dual‐dispersal strategy. The remarkable success of round goby as an aquatic invader stresses the need for better diffusion models of secondary range expansion for presumably sessile invasive species.
Multiple essential roles for EzrA in cell division of Staphylococcus aureus
Authors: Steele Victoria R. , Bottomley Amy L. , Garcia‐Lara Jorge , Kasturiarachchi Jagath , Foster Simon J.
Published: February 2011

In Bacillus subtilis, EzrA is involved in preventing aberrant formation of FtsZ rings and has also been implicated in the localization cycle of Pbp1. We have identified the orthologue of EzrA in Staphylococcus aureus to be essential for growth and cell division in this organism. Phenotypic analyses following titration of EzrA levels in S. aureus have shown that the protein is required for peptidoglycan synthesis as well as for assembly of the divisome at the midcell and cytokinesis. Protein interaction studies revealed that EzrA forms a complex with both the cytoplasmic components of the division machinery and those with periplasmic domains, suggesting that EzrA may be a scaffold molecule permitting the assembly of the division complex and forming an interface between the cytoplasmic cytoskeletal element FtsZ and the peptidoglycan biosynthetic apparatus active in the periplasm.
Characterization of Botryosphaeriaceae from plantation‐grown Eucalyptus species in South China
Authors: Chen S. F. , Pavlic D. , Roux J. , Slippers B. , Xie Y. J. , Wingfield M. J. , Zhou X. D.
Published: February 2011

The Botryosphaeriaceae is a species‐rich family that includes pathogens of a wide variety of trees, including Eucalyptus species. Symptoms typical of infection by the Botryosphaeriaceae have recently been observed in Eucalyptus plantations in South China. The aim of this study was to identify the Botryosphaeriaceae associated with these symptoms. Isolates were collected from branch cankers and senescent twigs of different Eucalyptus spp. All isolates resembling Botryosphaeriaceae were separated into groups based on conidial morphology. Initial identifications were made using PCR‐RFLP fingerprinting, by digesting the ITS region of the rDNA operon with the restriction enzymes CfoI and KspI. Furthermore, to distinguish isolates in the Neofusicoccum parvum/N. ribis complex, a locus (BotF15) previously shown to define these species, was amplified and restricted with CfoI. Selected isolates were then identified using comparisons of DNA sequence data for the ITS rDNA and translation elongation factor 1‐alpha (TEF‐1α) gene regions. Based on anamorph morphology and DNA sequence comparisons, five species were identified: Lasiodiplodia pseudotheobromae, L. theobromae, Neofusicoccum parvum, N. ribis sensu lato and one undescribed taxon, for which the name Fusicoccum fabicercianum sp. nov. is provided. Isolates of all species gave rise to lesions on the stems of an E. grandis clone in a glasshouse inoculation trial and on the stems of five Eucalyptus genotypes inoculated in the field, where L. pseudotheobromae and L. theobromae were most pathogenic. The five Eucalyptus genotypes differed in their susceptibility to the Botryosphaeriaceae species suggesting that breeding and selection offers opportunity for disease avoidance in the future.
Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei‐induced responses in the potato periderm
Authors: Khatri B. B. , Tegg R. S. , Brown P. H. , Wilson C. R.
Published: February 2011

Using hydroponics and novel non‐destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole‐tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first‐formed internodes were most susceptible to infection, whilst later‐forming and slower‐expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen‐induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common‐scab‐tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).
The threat of wild habitat to scab resistant apple cultivars
Authors: Lê Van A. , Durel C.E. , Le Cam B. , Caffier V.
Published: February 2011

Evaluations of plant resistance to pathogens are rarely made using isolates from wild habitats, although the heterogeneity of such habitats may generate pathogen diversity which could be a source of new virulence in cultivated habitats. The aim of this study was to investigate whether scab resistance factors, identified and characterized in apples using isolates of Venturia inaequalis from a cultivated habitat, remained effective against isolates from a wild habitat. Three V. inaequalis core collections originating from the cultivated apple Malus × domestica and from two wild species, M. sieversii and M. sylvestris, were established to maximize pathogen diversity. For each core collection, 10 isolates were inoculated in mixtures onto 51 genotypes from an apple progeny segregating for two qualitative resistance genes and six quantitative resistance loci (QRL). On each apple genotype, isolates that contributed to the scab symptoms were identified within the mixture using microsatellite markers. The most frequently detected isolates were inoculated singly to compare their aggressiveness according to their host origin. The results showed that isolates from a wild habitat were able to infect the susceptible apple genotypes. However, these isolates were never more aggressive than isolates from the cultivated habitat on the resistance factors tested. It can therefore be concluded that the resistance factors used in this study, identified with V. inaequalis isolates from a cultivated habitat, remained effective against isolates from M. sylvestris and M. sieversii.
Treatment of Multi‐Drug‐Resistant Tuberculosis in Mice with DNA Vaccines Alone or in Combination with Chemotherapeutic Drugs
Authors: Liang Y. , Wu X. , Zhang J. , Yang Y. , Wang L. , Bai X. , Yu Q. , Li N. , Li Z.
Published: February 2011

The problems of tuberculosis (TB) and its drug resistances are very severe in China. New therapeutic agents or regimens to treat multi‐drug‐resistant tuberculosis (MDR‐TB) are urgently needed. We studied the effects of Ag85A DNA vaccine alone or in combination with rifampin (RFP) or pyrazinamide (PZA) for the treatment of MDR‐TB in mice. Ag85A DNA vaccine significantly increased the production of IFN‐γ, but lowered the production of IL‐4. Seventy female BALB/c mice infected with Mycobacterium tuberculosis clinical isolate HB361, which was resistant to RFP and isoniazid but sensitive to PZA, were treated with plasmid pVAX1, RFP, PZA, M. vaccae vaccine, Ag85A DNA, Ag85A DNA combined with RFP or PZA, respectively. Ag85A DNA vaccine alone or in combination with RFP or PZA reduced the pulmonary and splenic bacterial loads by 1.03–1.38 logs, respectively. Ag85A DNA combined with conventional chemotherapy for the treatment of MDR‐TB might result in cure of MDR‐TB in developing countries.
Stimulatory Lipids Accumulate in the Mouse Liver within 30 min of Contact Sensitization to Facilitate the Activation of Naïve iNKT Cells in a CD1d‐Dependent Fashion
Authors: Dey N. , Szczepanik M. , Lau K. , Majewska‐Szczepanik M. , Askenase P. W.
Published: February 2011

Natural killer T cells with invariant αβ‐T cell receptors (TCRs) (iNKT cells) constitute a lipid‐responsive arm of the innate immune system that has been implicated in the regulation or promotion of various immune, infectious and neoplastic processes. Contact sensitivity (CS), also known as contact hypersensitivity or allergic contact dermatitis, is one such immune process that begins with topical sensitization to an allergen and culminates in a localized cutaneous inflammatory response after challenge with the same allergen. CS depends on events initiated early in sensitization by hepatic iNKT cells. We have shown previously that these iNKT cells release IL‐4 early after skin sensitization to activate B‐1 B cells to produce IgM antibodies that aid in local recruitment of the effector T cells. Here, we utilize adoptive transfer techniques in several strains of knockout mice to demonstrate that hepatic lipids isolated 30 min after sensitization are significantly more stimulatory to naïve hepatic iNKT cells than hepatic lipids isolated after sham sensitization. These stimulatory hepatic lipids specifically affect iNKT cells and not B‐1 B cells. The downstream CS response is abrogated with anti‐CD1d‐blocking antibodies, suggesting a critical role of CD1d in the activation of hepatic iNKT cells with these lipids. Hepatocytes may not be essential, as donor hepatic iNKT cells can reconstitute CS without migrating to the recipient mouse liver. Rather, CD1d‐expressing liver mononuclear cells are sufficient for activation of iNKT cells. In conclusion, stimulatory lipids accumulate in the liver soon after sensitization and facilitate iNKT cell activation in a CD1d‐dependent yet potentially hepatocyte‐independent manner.
Differential Regulation of Notch Ligands in Dendritic Cells upon Interaction with T Helper Cells
Authors: Sauma D. , Espejo P. , Ramirez A. , Fierro A. , Rosemblatt M. , Bono M. R.
Published: February 2011

The Notch signalling pathway has recently been linked to T helper 1 (Th1)/T helper 2 (Th2) cell polarization via a mechanism involving differential expression of Notch ligands, Delta‐like and Jagged, in antigen‐presenting cells. However, whether stimuli other than pathogen‐derived factors are involved in the regulation of Notch ligand expression in dendritic cells (DCs) remains unknown. Here, we address the effect of T helper cells (Th1 and Th2) on Delta‐like 4 and Jagged 2 expression in bone marrow–derived DCs. We demonstrate that both Th1 and Th2 cells induce Delta‐like 4 mRNA expression in DCs, in a process that is, in part, mediated by CD40 signalling. In contrast, only Th2 cells induce a significant increase in Jagged 2 mRNA levels in DCs. Additionally, we show that IL‐4, a hallmark Th2 cytokine, plays a role in Jagged 2 expression, as evidenced by the fact that cholera toxin, a Th2‐promoting stimulus, induces Jagged 2 mRNA expression in DCs only in the presence of IL‐4. Finally, we demonstrate that DCs also express Notch 1 and that this expression is downregulated by IL‐4. These data suggest that Notch ligands are differentially regulated in DCs: Delta‐like 4 is regulated by T helper cells and by pathogen‐derived Th1 stimuli, whereas Jagged 2 is regulated by Th2 cells and pathogen‐derived Th2‐promoting stimuli. Based on our results, we propose that the positive feedback loop that Th2 cells exert on T cell polarization may involve the induction of Jagged 2 expression in DCs.
A sedimentological model for the continental Upper Triassic Tadrart Ouadou Sandstone Member: recording an interplay of climate and tectonics (Argana Valley; South‐west Morocco)
Authors: MADER NADINE K. , REDFERN JONATHAN
Published: February 2011

The continental Upper Triassic Tadrart Ouadou Sandstone Member was deposited in an extensional setting on the Pangaean continent, strongly influenced by a low‐latitude climatic regime (10° to 20° north). Complex interaction of basin subsidence and climatically driven processes led to high facies variability and a lack of correlatable units across the Argana Valley exposures. A process‐orientated approach integrating detailed facies with architectural element analysis was undertaken, which resulted in a multistage depositional model for the Tadrart Ouadou Sandstone Member. The basin‐scale model shows that basal alluvial fan and braided river systems are confined to the centre of the Argana Valley exposures. Aeolian deposits occur throughout the sequence, but dominate in the north. After a phase of playa deposition, prominent basin‐wide fluvial incision of up to 8 m marks the onset of perennial fluvial flow. These well‐sorted, internally complex and locally highly amalgamated fluvial sandstones are widespread throughout the basin and are focused in a north to south (south‐west) flowing channel system. After a final stage of aeolian sedimentation, sandstone deposition of the Tadrart Ouadou Sandstone Member in the Argana Valley is terminated rapidly by the onlap of lacustrine mudstones of the Sidi Mansour Member. The study revealed that, except for one pronounced period of perennial conditions, sedimentation is controlled largely by ephemeral fluvial flow, alternating ground water tables, deflation processes and periods with limited periodic local run‐off. The study highlights that facies architecture in the basin is the result of complex interaction of local syn‐sedimentary tectonics and the climatic regime within the basin, but also the climate of the catchment area to the east. The data suggest a proximal to mid‐distal basin setting in the rain‐shadow to the west of a mountain range (Massif Ancien), which exerted a strong control on the depositional environments of Triassic deposits exposed in this part of South‐west Morocco.
A versatile system for detecting transposition in Arabidopsis
Authors: Fedoroff Nina V. , Smith David L.
Published: February 2011

The maize transposable element Activator (Ac) has been shown to be active in a number of dicots, including Arabidopsis thaliana, whose small genome and short generation time have favored its wide adoption as a model organism for molecular genetic approaches to plant physiology and development. Using the Ac element and several bacterial and plant marker genes, we have devised a versatile system for identifying plants in which a transposon has excised and reinserted elsewhere in the genome. The transposons have been designed to facilitate the identification of insertions downstream of promoters and in the vicinity of enhancers by the inclusion of a β‐glucuronidase (GUS) gene either lacking a promoter or having a minimal promoter sequence. The system permits the transposon and the source of transposase to be maintained either stably in separate plants or in the same plant. Plants in which transposition is occurring can be identified by the frequent somatic activation of the GUS gene. The herbicide chlorsulfuron is used as a selective agent to identify progeny plants in which the transposon has excised from its original insertion site within a chlorsulfuron‐resistant acetolactate synthase gene. Additional selectable markers permit the identification of plants containing a transposed element, but lacking transposase. Here we describe our initial characterization of the system and demonstrate its reliability and efficiency in identifying plants with transposed elements.
Proembryo culture: in vitro development of early globular‐stage zygotic embryos from Brassica juncea
Authors: Liu Chun‐Ming , Xu Zhi‐Hong , Chua Nam‐Hai
Published: February 2011

We have systematically investigated the nutritional requirements for in vitro culture of zygotic proembryos of Brassica juncea. Normal embryo development in vitro was achieved in a new embryo culture medium (ECM) which contains mineral salts, sugars, amino acids, organic acids and coconut water. The culture system is comprised of two agar layers, with the top layer containing a higher osmolality than the bottom layer. Proembryos were embedded in the top layer in which the osmotic pressure decreased gradually during culture because of the diffusion of osmotically active compounds into the bottom layer. Using such a double‐layer culture system and the ECM, proembryos as small as 35 μm (8–36 cells) could be cultured and developed into normal, mature embryos with an efficiency of at least 75%. In contrast to previous findings, we found that the removal of the suspensor had only a small effect on the development of embryos 55 μm or smaller, but no effect on larger proembryos. We expect this system to be very useful for investigations of the mechanism of plant embryogenesis.
The accumulation of zein polypeptides and zein mRNA in cultured endosperms of maize is modulated by nitrogen supply
Authors: Balconi Carlotta , Rizzi Eduardo , Motto Mario , Salamini Francesco , Thompson Richard
Published: February 2011

The effect of nitrogen (N) nutrition upon the accumulation of seed storage protein has been studied in wild‐type and opaque‐2 mutant (o2) maize endosperms grown in vitro, for 5 days, on a solid medium containing different amounts of N in the form of inorganic or organic compounds. As reference, the accumulation of zein proteins in endosperms grown to maturity in vivo under field conditions was also examined. The developmental stage up to 14–19 days after pollination (DAP) defines, both in vivo and in vitro, a phase of growth during which the major zein classes of 20 and 22 kDa are synthesized both in wild‐type and o2 endosperms. In vitro, the corresponding transcripts of the genes coding the 20 and 22 kDa zeins, and of the zein synthesis associated gene b‐32, are also present Under in vitro conditions, the level of expression of the zein synthesizing system, as monitored by zein accumulation, is dependent on the level and form of N supplied in the medium. In vivo, at stages of development from 19 DAP to maturity, the synthesis of the 22 kDa zein class and of the b‐32 protein is under control of the O2 transcriptional activator. It is hypothesized that at early stages of endosperm development (between 9 and 14–19 DAP) a ‘metabolic control’, based on N availability, is operative, possibly based on a regulatory factor different from O2.