bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantized symplectic actions and 𝑊-algebras
Authors: Losev Ivan
Published: October 2009

With a nilpotent element in a semisimple Lie algebra

g

\mathfrak {g}

one associates a finitely generated associative algebra

W

\mathcal {W}

called a

W
W

-algebra of finite type. This algebra is obtained from the universal enveloping algebra

U
(

g

)

U(\mathfrak {g})

by a certain Hamiltonian reduction. We observe that

W

\mathcal {W}

is the invariant algebra for an action of a reductive group

G
G

with Lie algebra

g

\mathfrak {g}

on a quantized symplectic affine variety and use this observation to study

W

\mathcal {W}

. Our results include an alternative definition of

W

\mathcal {W}

, a relation between the sets of prime ideals of

W

\mathcal {W}

and of the corresponding universal enveloping algebra, the existence of a one-dimensional representation of

W

\mathcal {W}

in the case of classical

g

\mathfrak {g}

and the separation of elements of

W

\mathcal {W}

by finite-dimensional representations.
The analysis of heterogeneous time trends in multivariate age–period–cohort models
Authors: Riebler Andrea , Held Leonhard
Published: October 2009

Age–period–cohort (APC) models are frequently used to analyze mortality or morbidity rates stratified by age group and period. For the case in which rates are given in different strata, multivariate APC models have been considered only recently. Such models share a set of parameters, for example, the age effects, while the other parameters may vary across strata. We show that differences of strata-specific effects are identifiable. We then propose a Bayesian approach based on smoothing priors to estimate multivariate APC models. This provides an alternative to maximum likelihood (ML) estimates of relative risk in the case of equal intervals and gives useful results even in the case of unequal intervals, where ML estimates have severe artifacts. This is illustrated with data on female mortality in Denmark and Norway and data on chronic obstructive pulmonary disease mortality of males in England and Wales, stratified by 3 different areas: Greater London, conurbations excluding Greater London, and nonconurbation areas.
Experimental Evaluation of Ethanolic Extract of Carapa guianensis L. Leaf for Its Wound Healing Activity Using Three Wound Models
Authors: Nayak B. Shivananda , Kanhai Joel , Milne David Malcolm , Pereira Lexley Pinto , Swanston William H.
Published: October 2009

The leaves of Carapa guianensis have been used to treat ulcers, skin parasites, and skin problems. The ethanolic extract of C. guianensis leaf was evaluated for its antibacterial and wound healing activity using excision, incision and dead space wound models in rats. The animals were randomly divided into two groups (n = 6) in all the models. In the excision wound model test group animals were treated topically with the leaf extract (250 mg kg−1 body weight) whereas, control animals were treated with petroleum jelly. In the incision and dead space wound models, the test group animals were treated with extract (250 mg kg−1 day−1) orally by mixing in drinking water and the control group animals were maintained with plain drinking water. Healing was assessed by the rate of wound contraction, period of epithelialization, skin breaking strength, granulation tissue weight and hydoxyproline content. On Day 15 extract‐treated animals exhibited 100% reduction in the wound area when compared to controls (95%) with significant decrease in the epithelialization period. The extract failed to demonstrate antibacterial activity. Skin breaking strength (P < .001), wet (P < .002) and dry (P < .02) granulation tissue and hydroxyproline content (P < .03) were significantly higher in extract treated animals. The increased rate of wound contraction, skin breaking strength and hydroxyproline content supports potential application of C. guianensis in wound healing.
Simultaneous assay of every Salmonella Typhi gene using one million transposon mutants
Authors: Langridge Gemma C. , Phan Minh-Duy , Turner Daniel J. , Perkins Timothy T. , Parts Leopold , Haase Jana , Charles Ian , Maskell Duncan J. , Peters Sarah E. , Dougan Gordon , Wain John , Parkhill Julian , Turner A. Keith
Published: October 2009

Very high-throughput sequencing technologies need to be matched by high-throughput functional studies if we are to make full use of the current explosion in genome sequences. We have generated a very large bacterial mutant pool, consisting of an estimated 1.1 million transposon mutants and we have used genomic DNA from this mutant pool, and Illumina nucleotide sequencing to prime from the transposon and sequence into the adjacent target DNA. With this method, which we have called TraDIS (transposon directed insertion-site sequencing), we have been able to map 370,000 unique transposon insertion sites to the Salmonella enterica serovar Typhi chromosome. The unprecedented density and resolution of mapped insertion sites, an average of one every 13 base pairs, has allowed us to assay simultaneously every gene in the genome for essentiality and generate a genome-wide list of candidate essential genes. In addition, the semiquantitative nature of the assay allowed us to identify genes that are advantageous and those that are disadvantageous for growth under standard laboratory conditions. Comparison of the mutant pool following growth in the presence or absence of ox bile enabled every gene to be assayed for its contribution toward bile tolerance, a trait required of any enteric bacterium and for carriage of S. Typhi in the gall bladder. This screen validated our hypothesis that we can simultaneously assay every gene in the genome to identify niche-specific essential genes.
Measurement of stress factors and residual stress of a film byin situX-ray diffraction during four-point bending
Authors: Ortolani Matteo , Azanza Ricardo Cristy Leonor , Scardi Paolo
Published: October 2009

A method is proposed for the simultaneous measurement of the stress factors and residual stress state of a film byin-situX-ray diffraction during four-point bending. The externally applied load acts as an additional degree of freedom in the stress–strain relation, which allows the problem to be solved for both residual stress and elastic moduli without assuming any grain interaction model. The procedure was tested on a galvanic nickel deposit and the predictions of existing grain interaction models were compared with the experimental results.
Structural studies on carbon nanotube fibres by synchrotron radiation microdiffraction and microfluorescence
Authors: Davies Richard J. , Riekel Christian , Koziol Krzysztof K. , Vilatela Juan J. , Windle Alan H.
Published: October 2009

This study reports on the characterization of a carbon nanotube fibre using synchrotron radiation microbeam small- and wide-angle X-ray scattering in combination with microfluorescence. The fibre, spun directly from a chemical vapour deposition reaction zone, is imaged in terms of microstructural heterogeneities. The results reveal a fibre consisting of highly oriented nanotube bundles and unoriented carbonaceous material. Within the oriented component there is a variable orientation distribution and evidence of differences in nanotube packing. Single catalyst crystallites can be located within the fibre from their wide-angle X-ray scattering signal, and the particulate distribution imaged using X-ray microfluorescence. Whilst this study only constitutes a preliminary analysis, it demonstrates the application of existing fibre characterization methods to new materials. It also highlights the potential of synchrotron radiation micro- and nanobeam small- and wide-angle X-ray scattering and microfluorescence for the study of fibres of a few µm diameter.
Is the microbial tree of life verificationist?
Authors: Lienau E.K. , DeSalle R.
Published: October 2009

The field of microbial phylogenetics has questioned the feasibility of using a tree‐like structure to the describe microbial evolution. This debate centres on two main points. First, because microorganisms are able to transfer genes from one to another in zero generations (horizontal gene transfer, or HGT), the use of molecular characters to perform phylogenetic analyses will yield an erroneous topology and HGT clearly makes the evolution of microorganisms non tree‐like. Second, the use of concatenated gene sequences in a total evidence approach to phylogenetic systematics is a verificationist endeavour, the aim of which is to bolster support. However, the goal of the total evidence approach to phylogenetic research is based in the idea of increasing explanatory power over background knowledge through test and corroboration, rather than to bolster support for nodes in a tree. In this context, the testing of phylogenetic data is a falsificationist endeavour that includes the possibility of not rejecting the null hypothesis that there is no tree‐like structure in molecular phylogenetic data. We discuss several tests that aim to test rigorously the hypothesis that a tree of life exists for microorganisms. We also discuss the philosophical ramifications of background knowledge and corroboration in microbial studies that need to be considered when suggesting that HGT confounds the tree of life.

 © The Willi Hennig Society 2009.
Contrasting activity of Hedgehog and Wnt pathways according to gastric cancer cell differentiation: Relevance of crosstalk mechanisms
Authors: Kim Jie‐Hyun , Shin Hyun Soo , Lee Sang Hun , Lee Inohk , Lee Yeo Song , Park Jun Chul , Kim Yu Jin , Chung Jae Bock , Lee Yong Chan
Published: October 2009

Gastric cancer displays different biological behaviors according to histological differentiation. The different biological behavior might involve the activation of distinct signaling pathways necessary for the growth and survival of cancer cells in gastric cancer. We investigated the differentiation‐related signal interaction between Hedgehog and Wnt pathways in gastric cancer cells. Differentiation of gastric cancer cells was induced by sodium butyrate. The sonic Hedgehog (SHH) signal expressions were increased during cellular differentiation. In contrast, the expression of Wnt signaling was decreased during differentiation. Ectopic expression of glioma‐associated oncogene‐1 (GLI1) increased the level of secreted frizzled related protein‐1 (SFRP1) transcript, whereas inhibition of GLI1 reduced the level of SFRP1 transcript. ChIP assay showed that GLI1 induced the transcriptional regulation of SFRP1 gene expression. Ectopic expression of GLI1 decreased the nuclear β‐catenin staining, but the inhibition of GLI1 induced the reversal of nuclear β‐catenin overexpression. Ectopic expression of β‐catenin also decreased the expression of GLI1 in the butyrate treated cancer cells. SHH and GLI1 immunoexpression was greater in well differentiated gastric cancer tissues compared to poorly differentiated tissues, and nuclear β‐catenin immunoexpression was lower in well differentiated compared to poorly differentiated tissues. The SHH and Wnt pathways are differentially involved according to gastric cancer cell differentiation. (Cancer Sci 2009)
Ethylene perception via ETR1 is required in Arabidopsis infection by Verticillium dahliae
Authors: PANTELIDES IAKOVOS S. , TJAMOS SOTIRIOS E. , PAPLOMATAS EPAMINONDAS J.
Published: October 2009

Vascular wilts caused by Verticillium spp. are very difficult to control and, as a result, are the cause of severe yield losses in a wide range of economically important crops. The responses of Arabidopsis thaliana mutant plants impaired in known pathogen response pathways were used to explore the components in defence against Verticillium dahliae. Analysis of the mutant responses revealed enhanced resistance in etr1‐1[ethylene (ET) receptor mutant] plants, but not in salicylic acid‐, jasmonic acid‐ or other ET‐deficient mutants, indicating a crucial role of ETR1 in defence against this pathogen. Quantitative polymerase chain reaction analysis revealed that the decrease in symptom severity shown in etr1‐1 plants was associated with significant reductions in the growth of the pathogen in the vascular tissues of the plants, suggesting that impaired perception of ET via ETR1 results in increased disease resistance. Furthermore, the activation and increased accumulation of the PR‐1, PR‐2, PR‐5, GSTF12, GSTU16, CHI‐1, CHI‐2 and Myb75 genes, observed in etr1‐1 plants after V. dahliae inoculation, indicate that the outcome of the induced defence response of etr1‐1 plants seems to be dependent on a set of defence genes activated on pathogen attack.
Clinical outcome of newly diagnosed Crohn’s disease: a comparative, retrospective study before and after infliximab availability
Authors: DOMÈNECH E. , ZABANA Y. , GARCIA‐PLANELLA E. , LÓPEZ SAN ROMÁN A. , NOS P. , GINARD D. , GORDILLO J. , MARTÍNEZ‐SILVA F. , BELTRÁN B. , MAÑOSA M. , CABRÉ E. , GASSULL M. A.
Published: October 2009

Background  Infliximab (IFX) could change the course of Crohn’s disease (CD) by reducing steroid use, surgery or prompting earlier introduction of immunomodulators (IMM).

Aim  To evaluate the impact of IFX availability on the course of early CD.

Methods  Two cohorts of newly diagnosed CD patients were identified: The first cohort included patients diagnosed from January 1994 to December 1997 and the second from January 2000 to December 2003. All patients were diagnosed, treated and followed up in the same centre until December 1999 (first cohort) or December 2005 (second cohort). Development of disease‐related complications, steroid, IMM or IFX requirements and intestinal resections during follow‐up were registered.

Results  A total of 328 patients were included (146 first cohort, 182 second cohort). A similar proportion of patients in both cohorts received steroids, but steroid exposure resulted significantly more intense in the first cohort (P = 0.001). In the second cohort, 14% of patients received IFX. Thiopurines were used more (P = 0.001) and earlier (P = 0.012) in the second cohort. No differences in surgical requirements or the development of disease‐related complications were found.

Conclusions  Following a step‐up therapeutic algorithm, IFX availability did not reduce surgical requirements or the development of disease‐related complications.

Aliment Pharmacol Ther 31, 233–239
The effect of intrathecal fentanyl on Cerebral State Index‐guided sedation during spinal anaesthesia*
Authors: Kim J. Y. , Kim K. B. , Shin C. S. , Ha S. H. , Kim M. K. , Lee J. S.
Published: October 2009

This study investigated the effect of intrathecal fentanyl on the dose of propofol during sedation guided by Cerebral State Index monitoring. Seventy patients were randomly assigned to receive either fentanyl 25 μg (n = 35) or normal saline (n = 35) with hyperbaric bupivacaine 12.5 mg for spinal anaesthesia. Propofol was infused to maintain a Cerebral State Index value of 65–75 for 30 min. The propofol infusion time and dose required to reach a Cerebral State Index value of 75 were recorded together with the time required to reach a Cerebral State Index value higher than 90 after cessation of sedation. The onset time for sedation was faster and the recovery time was slower in the fentanyl group compared to those in the saline group (p = 0.018 and 0.027, respectively). The propofol doses required for onset and maintenance of sedation were significantly lower in the fentanyl group compared to those in the control group (p = 0.018 and < 0.001, respectively). In conclusion, adding intrathecal fentanyl 25 μg during spinal anaesthesia significantly reduced the dose of propofol required for sedation and prolonged the subsequent recovery time.
Exposure to folic acid antagonists during the first trimester of pregnancy and the risk of major malformations
Authors: Matok Ilan , Gorodischer Rafael , Koren Gideon , Landau Daniella , Wiznitzer Arnon , Levy Amalia
Published: October 2009

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Previous studies have suggested a tendency of antifolate drugs to be associated with higher rates of neural tube defects.

WHAT THIS STUDY ADDS

• This study makes use of the data on abortuses, which is missed in many other studies. In this case, the abortion data were critical.

• The study documents that clinicians should avoid, as much as possible, the use of folic acid antagonists during the first trimester of pregnancy, when embryogenesis takes place.

AIM To investigate the safety of folic acid antagonists during the first trimester of pregnancy in a large cohort.

METHODS Computerized databases for medications dispensed from 1998 to 2007 to women registered in ‘Clalit’ HMO, Israel southern district, was linked with maternal and infant hospitalization records, and to therapeutics abortions data. The risk for adverse pregnancy outcomes of folic acid antagonists exposure was assessed by adjusting for known confounders.

RESULTS Eighty‐four thousand, eight hundred and twenty‐three infants were born and 998 therapeutic abortions took place; 571 fetuses and infants were exposed to one or more folic acid antagonists in the first trimester of pregnancy. Exposure was associated with an overall increased risk of congenital malformations [odds ratio (OR) 2.43, 95% confidence interval (CI) 1.92, 3.08], due mainly to increased risk for neural tube (adjusted OR 6.5, 95% CI 4.34, 9.15) and cardiovascular defects (OR 1.76, CI 1.05, 2.95).

CONCLUSION First‐trimester exposure to folic acid antagonists is associated with increased risk of congenital malformations.
Daily subcutaneous injections of peptide induce CD4+ CD25+ T regulatory cells
Authors: Dahlberg P E , Schartner J M , Timmel A , Seroogy C M
Published: October 2009

Peptide immunotherapy is being explored to modulate varied disease states; however, the mechanism of action remains poorly understood. In this study, we investigated the ability of a subcutaneous peptide immunization schedule to induce of CD4+ CD25+ T regulatory cells. DO11·10 T cell receptor (TCR) transgenic mice on a Rag 2–/– background were injected subcutaneously with varied doses of purified ovalbumin (OVA323–339) peptide daily for 16 days. While these mice have no CD4+ CD25+ T regulatory cells, following this injection schedule up to 30% of the CD4+ cells were found to express CD25. Real-time quantitative polymerase chain reaction (QPCR) analysis of the induced CD4+ CD25+ T cells revealed increased expression of forkhead box P3 (FoxP3), suggesting that these cells may have a regulatory function. Proliferation and suppression assays in vitro utilizing the induced CD4+ CD25+ T cells revealed a profound anergic phenotype in addition to potent suppressive capability. Importantly, co-injection of the induced CD4+ CD25+ T cells with 5,6-carboxy-succinimidyl-fluorescence-ester (CFSE)-labelled naive CD4+ T cells (responder cells) into BALB/c recipient mice reduced proliferation and differentiation of the responder cells in response to challenge with OVA323–339 peptide plus adjuvant. We conclude that repeated subcutaneous exposure to low-dose peptide leads to de novo induction of CD4+ CD25+ FoxP3+ T regulatory cells with potent in vitro and in vivo suppressive capability, thereby suggesting that one mechanism of peptide immunotherapy appears to be induction of CD4+ CD25+ Foxp3+ T regulatory cells.
Ageing and Toll-like receptor expression by innate immune cells in chronic human schistosomiasis
Authors: Comin F , Speziali E , Martins-Filho O A , Caldas I R , Moura V , Gazzinelli A , Correa-Oliveira R , Faria A M C
Published: October 2009

There has been no systematic study of the immune response of individuals aged over 60 years living in Schistosomiasis mansoni-endemic areas, although senescence is reportedly associated with susceptibility to infection and progressive decline in immune function. We have shown previously, in two endemic areas in Minas Gerais, Brazil, that the frequency of individuals aged over 60 years with chronic schistosomiasis is no longer negligible. Moreover, several elderly individuals who have always lived in these endemic areas stay protected from infection. An important question for studies of ageing and disease control in developing countries is which differences in the immunological profile of these negatively tested (non-infected) individuals can account for their resistance to either infection or reinfection. We show, in the present study, that non-infected (negative) elderly individuals develop innate immune mechanisms of protection that replace the age-associated decline in T cell function. Non-infected elderly individuals from endemic areas of schistosome infection present an increase in the frequency of the natural killer (NK) CD56low subset of NK cells expressing Toll-like receptors (TLR)-1, -2, -3 and -4 as determined by flow cytometry analysis. In addition, the proportion of dendritic cells expressing TLR-1 is elevated as well as the frequency of monocytes expressing TLR-1 and -4. These results suggest that TLR expression by cells of the innate immune system may be related to the negative status of infection in some elderly individuals who are constantly exposed to S. mansoni. Developing mechanisms of protection from infection may represent a biomarker for healthy ageing in this population.
Anti-oxidized low-density lipoprotein antibodies in myeloperoxidase–positive vasculitis patients preferentially recognize hypochlorite-modified low density lipoproteins
Authors: Slot M C , Theunissen R , van Paassen P , Damoiseaux J G M C , Cohen Tervaert J W
Published: October 2009

Many patients surviving vasculitis are prone to accelerated atherosclerosis and often have enhanced levels of antibodies to oxidized low-density lipoprotein (oxLDL). To measure anti-oxLDL antibodies, oxidation of LDL is achieved with copper (Cu) or malondialdehyde (MDA). Because, in vivo, LDL may be oxidized with myeloperoxidase (MPO) or its product hypochlorite, we measured anti-hypochlorite LDL antibodies in patients with vasculitis, haemodialysis patients and healthy controls. A newly developed enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to oxLDL as modified by hypochlorite. Results are compared with data obtained by standard LDL oxidation using MDA–LDL or Cu–LDL as substrate. Results were compared between anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients (n = 93), haemodialysis (HD) patients (n = 59) and healthy controls (HC; n = 43). Furthermore, patients with MPO–ANCA-associated vasculitis (n = 47) were compared with patients with proteinase 3 (PR3)–ANCA associated vasculitis (n = 46). Optimal cut-off points were determined by receiver operator characteristic (ROC) curve analysis. Anti-oxLDL antibodies are enhanced in AAV patients (MDA–LDL and hypochlorite–LDL) and in HD patients (hypochlorite–LDL), when compared to HC. Furthermore, patients with MPO–ANCA-associated vasculitis had higher levels of antibodies to hypochlorite–LDL than patients with PR3–ANCA-associated vasculitis. Our newly developed assay, in which hypochlorite–LDL is used as substrate, seems a more sensitive assay than traditional assays to measure oxLDL antibodies. Furthermore, our results suggest that enhanced MPO-mediated LDL oxidation occurs in patients with MPO–ANCA.
Lung macrophages from bacille Calmette–Guérin-vaccinated guinea pigs suppress T cell proliferation but restrict intracellular growth ofM. tuberculosisafter recombinant guinea pig interferon-γ activation
Authors: Jeevan A , Majorov K , Sawant K , Cho H , McMurray D N
Published: October 2009

The guinea pig model of low-dose pulmonary tuberculosis has been used to study the pathogenesis of infection as well as the mechanisms of bacille Calmette–Guérin (BCG) vaccine-induced resistance. We investigated the function of lung cells from naive and BCG-vaccinated guinea pigs after enzymatic digestion of lung tissue with collagenase and DNase I. The total lung digest cells proliferated poorly to purified protein derivative (PPD) but comparatively better to ConA as assessed by [3H]-thymidine uptake. However, the non-adherent population obtained after plastic adherence of lung digests showed an enhanced response to concanavalin A (ConA) and PPD. Therefore, proliferation to ConA and PPD of nylon wool-purified T cells co-cultured with peritoneal (PMøs), alveolar (AMøs) or lung macrophages (LMøs) was assessed. Co-cultures of lung T cells and PMøs showed maximum proliferation to PPD, whereas proliferation was suppressed significantly by the addition of AMøs or LMøs. The response of T cells to ConA was unaffected in co-cultures. Incubation of co-cultures with recombinant guinea pig interferon-γ (rgpIFN-γ) did not reverse the suppression. In contrast, rgpIFN-γ-treated plastic adherent LMøs that were non-specific esterase-positive were capable of reducing the intracellular growth of Mycobacterium tuberculosis. Similarly, total, non-adherent and adherent lung digest cells from BCG-vaccinated guinea pigs showed IFN-γ and tumour necrosis factor (TNF)-α mRNA expression in response to ConA, lipopolysaccharide or PPD by reverse transcription–polymerase chain reaction followed by release of TNF protein but not IFN. These studies indicate that rgp-IFN-γ-treated lung tissue macrophages from BCG-vaccinated guinea pigs are defective for inducing antigen-specific proliferation in T cells, but control the intracellular accumulation of virulent M. tuberculosis.
Acute HIV infection: the impact of anti-retroviral treatment on cellular immune responses
Authors: Hicks C B , Gay C , Ferrari G
Published: October 2009

OTHER ARTICLE PUBLISHED IN THIS MINI-REVIEW SERIES ON INFECTIOUS DISEASE

Congenital cytomegalovirus infection: 50 years on. Clin Exp Immunol 2007; 149: doi:10.1111/j.1365-2249.2007.03454.x

The overall value of initiating anti-retroviral therapy during the acute phase of human immunodeficiency virus type 1 (HIV-1) infection remains unclear. From a clinical perspective, the lack of data from controlled randomized clinical trials limits understanding of long-term effects of treatment on the clinical course of HIV infection. Based on available data, the impact of anti-retroviral therapy during acute infection on the immune response against HIV-1 is not particularly encouraging. Recent observations on the very early depletion of lymphocyte reservoirs in the gastrointestinal tract may partially explain the limited benefit of anti-retroviral therapy initiated during the acute phase of HIV-1 infection. This may also help to explain the dichotomy between early observations demonstrating apparent immunological benefit with early anti-retroviral treatment that were associated none the less with inability to control viral replication following treatment interruption.
Contemporary climate change in the Sonoran Desert favors cold‐adapted species
Authors: KIMBALL SARAH , ANGERT AMY L. , HUXMAN TRAVIS E. , VENABLE D. LAWRENCE
Published: October 2009

Impacts of long‐term climate shifts on the dynamics of intact communities within species ranges are not well understood. Here, we show that warming and drying of the Southwestern United States over the last 25 years has corresponded to a shift in the species composition of Sonoran Desert winter annuals, paradoxically favoring species that germinate and grow best in cold temperatures. Winter rains have been arriving later in the season, during December rather than October, leading to the unexpected result that plants are germinating under colder temperatures, shifting community composition to favor slow growing, water‐use efficient, cold‐adapted species. Our results demonstrate how detailed ecophysiological knowledge of individual species, combined with long‐term demographic data, can reveal complex and sometimes unexpected shifts in community composition in response to climate change. Further, these results highlight the potentially overwhelming impact of changes in phenology on the response of biota to a changing climate.
Does dispersal control population densities in advection‐dominated systems? A fresh look at critical assumptions and a direct test
Authors: Downes Barbara J. , Lancaster Jill
Published: October 2009

1. In advection‐dominated systems (both freshwater and marine), population dynamics are usually presumed to be dominated by the effects of migrants dispersing by advection, especially over the small spatial scales at which populations can be studied, but few studies have tested this presumption. We tested the hypothesis that benthic densities are controlled by densities of dispersers for two aquatic insects in upland streams.

2. Our study animals were two species of caddisflies (Hydropsychidae), which become sedentary filter‐feeders following settlement onto substrata. Densities of dispersers in the drift (advective dispersal) were quantified using nets placed along the upstream edges of riffles, where the latter abruptly abutted a slower, upstream run. Settlement was estimated at each site using brick pavers, half of which had been fenced to prevent colonization of their top surfaces by walking hydropsychids, thus allowing us to distinguish also the mode of movement during settlement.

3. First through fifth instars of two species, Smicrophylax sp. AV2 and Asmicridea sp. AV1, were abundant and showed disparate results. Drift and settlement were relatively strongly related for Smicrophylax. The best fit lines were shown by second and third instars settling on plain bricks, suggesting that drift played a strong role in settlement, but that some drifters dropped to the bottom and located substrata by walking. Quantile regression suggested that drift sets limits to settlement in this species and that settlement success was highly variable. In contrast, settlement by Asmicridea was poorly related to drift; settlers were mainly individuals re‐dispersing within sites.

4. Smicrophylax densities appear to be controlled by dispersal from upstream, but benthic density of Asmicridea is more likely linked to local demography. Our data demonstrate the dangers of assuming that supposedly drift‐prone species can all be modelled in the same way. Alternative models emphasizing little or different kinds of movement should be considered. Variability in oviposition coupled with weak dispersal, for example, is a viable alternative hypothesis to explain variation in benthic density along channels. Moreover, the constraints on settlement of Smicrophylax show that immigrants into sites can be in short supply, an hypothesis rarely considered in stream research.
Socialism in soil? The importance of mycorrhizal fungal networks for facilitation in natural ecosystems
Authors: Van Der Heijden Marcel G. A. , Horton Thomas R.
Published: October 2009

1. Almost all plants are engaged in symbiotic relationships with mycorrhizal fungi. These soil fungi can promote plant growth by supplying limiting nutrients to plant roots in return for plant assimilates.

2. Many mycorrhizal fungi are not host specific and one fungal individual can colonize and interconnect a considerable number of plants. The existence of these so‐called mycorrhizal networks implies that fungi have the potential to facilitate growth of other plants and distribute resources among plants irrespective of their size, status or identity. In this paper, we explore the significance of mycorrhizal fungal networks for individual plants and for plant communities.

3. We address the following questions: (i) are all plant species benefitting from mycorrhizal networks, (ii) is benefit dependent on the size or age of a plant, (iii) is fungal support related to the relative dominance of plants in a community, (iv) are there host dependent barriers and physiological constraints for support and (v) what is the impact of mycorrhizal networks on plant–plant interactions and plant community dynamics? Moreover, using a review of published studies, we test whether mycorrhizal networks facilitate growth of small seedlings that establish between or near larger plants.

4. We found 60 cases where seedling species were grown together with larger plants with or without mycorrhizal fungal networks. Mycorrhizal networks promoted seedling growth in 48% of the cases (for 21 seedling species), while negative effects (25%) and no effects (27%) were also common. Seedlings associating with ectomycorrhizal fungi benefitted in the majority of the cases while effects on seedlings associating with arbuscular mycorrhizal fungi were more variable. Thus, the facilitative effects of mycorrhizal fungal networks depend on seedling species identity, mycorrhizal identity, plant species combinations and study system. We present a number of hypothetical scenarios that can explain the results based on cost–benefit relationship of individual members in a network.

5.
Synthesis. Overall, this review shows that mycorrhizal networks play a key role in plant communities by facilitating and influencing seedling establishment, by altering plant–plant interactions and by supplying and recycling nutrients.
Kisspeptin/Gpr54‐Independent Gonadotrophin‐Releasing Hormone Activity in Kiss1 and Gpr54 Mutant Mice
Authors: Chan Y. M. , Broder‐Fingert S. , Wong K. M. , Seminara S. B.
Published: October 2009

The kisspeptin/Gpr54 signalling pathway plays a critical role in reproduction by stimulating the secretion of gonadotrophin‐releasing hormone (GnRH), yet mice carrying mutations in Kiss1 (which encodes kisspeptin) or Gpr54 exhibit partial sexual maturation. For example, a proportion of female Kiss1−/− and Gpr54−/− mice exhibit vaginal oestrus, and some male Kiss1−/− and Gpr54−/− mice exhibit spermatogenesis. To characterise this partial sexual maturation, we examined the vaginal cytology of female Kiss1−/− and Gpr54−/− mice over time. Almost all mutant mice eventually enter oestrus, and then spontaneously transition from oestrus to dioestrus and back to oestrus again. These transitions are not associated with ovulation, and the frequency of these transitions increases with age. The oestrus exhibited by female Kiss1−/− and Gpr54−/− mice was disrupted by the administration of the competitive GnRH antagonist acyline, which also resulted in lower uterine weights and, in Kiss1−/− mice, lower serum follicle‐stimulating hormone (FSH) and luteinising hormone (LH) concentrations. Similarly, male Kiss1−/− and Gpr54−/− mice treated with acyline had smaller testicular sizes and an absence of mature sperm. In addition to examining intact Kiss1−/− and Gpr54−/− mice, we also assessed the effects of acyline on gonadotrophin concentrations in gonadectomised mice. Gonadectomy resulted in a significant increase in serum FSH concentrations in male Gpr54−/− and Kiss1−/− mice. Acyline administration to gonadectomised Kiss1−/− and Gpr54−/− male mice lowered serum FSH and LH concentrations significantly. By contrast to males, gonadectomy did not result in significant gonadotrophin changes in female Kiss1−/− and Gpr54−/− mice, but acyline administration was followed by a decrease in LH concentrations. These results demonstrate that, although kisspeptin signalling is critical for the high levels of GnRH activity required for normal sexual maturation and for ovulation, Kiss1−/− and Gpr54−/− mice retain some degree of GnRH activity. This GnRH activity is sufficient to produce significant effects on vaginal cytology and uterine weights in female mice and on spermatogenesis and testicular weights in male mice.
Oestradiol and Insulin‐Like Growth Factor‐1 Reduce Cell Loss after Global Ischaemia in Middle‐Aged Female Rats
Authors: Traub M. L. , De Butte‐Smith M. , Zukin R. S. , Etgen A. M.
Published: October 2009

Whereas the ability of oestradiol and insulin‐like growth factor (IGF)‐1 to afford neuroprotection against ischaemia‐induced neuronal death in young female and male rodents is well established, the impact of IGF‐1 in middle‐aged animals is largely unknown. The present study assessed the efficacy of oestradiol and IGF‐1 with respect to reducing neuronal death after transient global ischaemia in middle‐aged female rats after 8 weeks of hormone withdrawal. Rats were ovariohysterectomised and implanted 8 weeks later with an osmotic mini‐pump delivering IGF‐1 or saline into the lateral ventricle. Some rats also received physiological levels of oestradiol by subcutaneous pellet. Two weeks later, rats were subjected to global ischaemia or sham operation. Surviving hippocampal CA1 neurones were quantified. Ischaemia produced massive CA1 cell death compared to sham‐operated animals, which was evident at 14 days. Significantly more neurones survived in animals treated with either oestradiol or IGF‐1, but simultaneous treatment produced no additive effect. IGF‐1, an endogenous growth factor, may be a clinically useful therapy in preventing human brain injury, with neuroprotective equivalence to oestradiol but without the harmful side‐effects.
Bargaining and trust: the effects of 36‐h total sleep deprivation on socially interactive decisions
Authors: ANDERSON CLARE , DICKINSON DAVID L.
Published: October 2009

Although it is well known that sleep loss results in poor judgement and decisions, little is known about the influence of social context in these processes. Sixteen healthy young adults underwent three games involving bargaining (‘Ultimatum’ and ‘Dictator’) and trust, following total sleep deprivation (TSD) and during rested wakefulness (RW), in a repeated‐measures, counterbalanced design. To control for repeatability, a second group (n = 16) was tested twice under RW conditions. Paired anonymously with another individual, participants made their simple social interaction decisions facing real monetary incentives. For bargaining, following TSD participants were more likely to reject unequal‐split offers made by their partner, despite the rejection resulting in a zero monetary payoff for both participants. For the trust game, participants were less likely to place full trust in their anonymous partner. Overall, we provide novel evidence that following TSD, the conflict between personal financial gain and payoff equality is focused upon avoidance of unfavourable inequality (i.e. unfairness). This results in the rejection of unfair offers at personal monetary cost, and the lack of full trust which would expose one to being exploited in the interaction. As such, we suggest that within a social domain decisions may be more influenced by emotion following TSD, which has fundamental consequences for real‐world decision‐making involving social exchange.
Do complex population histories drive higher estimates of substitution rate in phylogenetic reconstructions?
Authors: RAMAKRISHNAN UMA , HADLY ELIZABETH A.
Published: October 2009

Our curiosity about biodiversity compels us to reconstruct the evolutionary past of species. Molecular evolutionary theory now allows parameterization of mathematically sophisticated and detailed models of DNA evolution, which have resulted in a wealth of phylogenetic histories. But reconstructing how species and population histories have played out is critically dependent on the assumptions we make, such as the clock‐like accumulation of genetic differences over time and the rate of accumulation of such differences. An important stumbling block in the reconstruction of evolutionary history has been the discordance in estimates of substitution rate between phylogenetic and pedigree‐based studies. Ancient genetic data recovered directly from the past are intermediate in time scale between phylogenetics‐based and pedigree‐based calibrations of substitution rate. Recent analyses of such ancient genetic data suggest that substitution rates are closer to the higher, pedigree‐based estimates. In this issue, Navascués & Emerson (2009) model genetic data from contemporary and ancient populations that deviate from a simple demographic history (including changes in population size and structure) using serial coalescent simulations. Furthermore, they show that when these data are used for calibration, we are likely to arrive at upwardly biased estimates of mutation rate.
Amphibian chytridiomycosis in Japan: distribution, haplotypes and possible route of entry into Japan
Authors: GOKA KOICHI , YOKOYAMA JUN , UNE YUMI , KUROKI TOSHIRO , SUZUKI KAZUTAKA , NAKAHARA MIRI , KOBAYASHI AREI , INABA SHIGEKI , MIZUTANI TOMOO , HYATT ALEX D.
Published: October 2009

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host‐specific distribution of the fungus.
Bronchopulmonary dysplasia and brain white matter damage in the preterm infant: a complex relationship
Authors: Gagliardi Luigi , Bellù Roberto , Zanini Rinaldo , Dammann Olaf
Published: October 2009

We analysed the relationship between bronchopulmonary dysplasia (BPD) and brain white matter damage (WMD) in very preterm infants, adjusting for common risk factors and confounders. We studied a cohort of infants <32 weeks gestational age (GA) and <1500 g, admitted to 12 hospitals in Northern Italy in 1999–2002. The association between BPD and WMD was estimated by generalised estimating equations and conditional logistic models, adjusting for centre, GA, propensity score for prolonged ventilation and other potential confounders. Directed acyclic graphs (DAG) were used to depict the underlying causal structure and guide analysis.

Of the 1209 infants reaching 36 weeks, 192 (15.8%) developed BPD (supplemental oxygen at 36 weeks) and 88 (7.3%) ultrasound‐defined WMD (cystic periventricular leukomalacia). In crude analysis, BPD was a strong risk factor for WMD [odds ratio (OR) = 5.9]. With successive adjustments, the OR progressively decreased to 3.88 when adjusting for GA, to 2.72 adding perinatal risk factors, and further down to 2.16 [95% confidence interval 1.1, 3.9] when ventilation was also adjusted for. Postnatal factors did not change the OR. Significant risk factors for WMD, in addition to BPD, were a low GA, a lower Apgar score, a higher illness severity score, ventilation and early‐onset sepsis, while antenatal steroids, being small for GA, and surfactant were associated with a reduced risk.

In conclusion, our data suggest that BPD is associated with an increased risk of WMD; most of the effect is due to shared risk factors and causal pathways. DAGs helped clarify the complex confounding of this scenario.
Trends in birth size and macrosomia in Queensland, Australia, from 1988 to 2005
Authors: Lahmann Petra H. , Wills Rachael‐Anne , Coory Michael
Published: October 2009

The objectives of this study were to explore temporal changes in birth measures in Queensland, Australia, and examine whether secular trends are similar to those in other countries. This study used data from the Queensland Perinatal Data Collection, including singleton livebirths (n = 831 375) from 1988 to 2005. Recorded birthweight (BW, g), birth length (BL, cm), gestational age (weeks), maternal age, ethnic origin and calculated ponderal index (PI, kg/m3) were used. Temporal trends were assessed over the intervals 1988–2005 for BW and 2001–2005 for BW, BL and PI.

Mean BW increased during the 17‐year interval by ∼1.9 g/year at a relatively low rate compared with reports from other countries. The proportion of high BW infants (≥4000 g) rose by 0.8% per year. Stratification by Indigenous status indicated that the increase in mean BW and prevalence of high BW was confined to non‐Indigenous newborns only. The secular increase in BW was further modified by gestational age, and maternal age. The increase in BW was larger in term infants (4.2 g/year) than in preterm infants (1.8 g/year), and larger in infants of younger mothers than in those of older mothers (5.0 g/year vs. 3.1 g/year). There were no trends in mean BL and mean PI at birth from 2001 to 2005. In Queensland, mean BW increased moderately in the last 17 years, as did the proportion of high BW infants. The trend in rising BW remained after controlling for other perinatal characteristics. Birth measures per se and related trends differed by Indigenous status and warrant further investigation.
Drought, ozone, ABA and ethylene: new insights from cell to plant to community
Authors: WILKINSON SALLY , DAVIES WILLIAM J
Published: October 2009

Recent reports show ethylene‐dependent reductions in stomatal sensitivity to abscisic acid (ABA) under ozone stress. These changes reduce stomatal control of plant water loss in drying soil. Here we review evidence that ABA and ethylene, and interactions between these two stress‐induced hormones, control many of the responses of intact plants to drought and ozone stress, with emphasis on effects on stomata and shoot growth. We draw attention to convergent signalling and response pathways induced by ozone and drought that can increase production of hydrogen peroxide (H2O2) and nitric oxide (NO). Stomatal responses to a wider range of stresses and developmental cues may also be controlled via the same sets of signalling pathways. Other hormones, or effectors such as xylem/apoplastic pH or changes in plant water status, also play a role in signalling within and between organs. We discuss the implications, for crops, natural ecosystems and water catchment processes, of ethylene's antagonism of the stomatal response to ABA, against a back‐drop of predictions for reduced precipitation and increasing ozone pollution, as part of global climate change and increasing urbanization and industrial development.