bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic and cell biological analysis of integrin outside-in signaling
Authors: Legate Kyle R. , Wickström Sara A. , Fässler Reinhard
Published: February 2009

Integrins are cell surface transmembrane receptors that recognize and bind to extracellular matrix proteins and counter receptors. Binding of activated integrins to their ligands induces a vast number of structural and signaling changes within the cell. Large, multimolecular complexes assemble onto the cytoplasmic tails of activated integrins to engage and organize the cytoskeleton, and activate signaling pathways that ultimately lead to changes in gene expression. Additionally, integrin-mediated signaling intersects with growth factor-mediated signaling through various levels of cross-talk. This review discusses recent work that has tremendously broadened our understanding of the complexity of integrin-mediated signaling.
The BLUF-EAL protein YcgF acts as a direct anti-repressor in a blue-light response of Escherichia coli
Authors: Tschowri Natalia , Busse Susan , Hengge Regine
Published: February 2009

The blue light using FAD (BLUF)-EAL protein YcgF is a known blue-light sensor of Escherichia coli, but its direct regulatory output and physiological function have remained unknown. Here, we demonstrate that unlike other EAL domain proteins, YcgF does not degrade the signaling molecule c-di-GMP, but directly binds to and releases the MerR-like repressor YcgE from its operator DNA upon blue-light irradiation. As a consequence, a distinct regulon of eight small proteins (of 71–126 amino acids) is strongly induced. These include YmgA and YmgB, which, via the RcsC/RcsD/RcsB two-component phosphorelay system, activate production of the biofilm matrix substance colanic acid as well as acid resistance genes and the biofilm-associated bdm gene and down-regulate adhesive curli fimbriae. Thus, small proteins under YcgF/YcgE control seem to act as “connectors” that provide additional signal input into a two-component signaling pathway. Moreover, we found ycgF and ycgE expression to be strongly activated at low temperature, and we elucidate how blue light, cold, and starvation signals are integrated in the expression and activity of the YcgF/YcgE/small protein signaling pathway. In conclusion, this pathway may modulate biofilm formation via the two-component network when E. coli has to survive in an extrahost aquatic environment.
Genomic mapping of binding regions for the Ecdysone receptor protein complex
Authors: Gauhar Zareen , Sun Ling V. , Hua Sujun , Mason Christopher E. , Fuchs Florian , Li Tong-Ruei , Boutros Michael , White Kevin P.
Published: February 2009

We determined the physical locations of the heterodimeric Ecdysone receptor/Ultraspiracle (ECR/USP) nuclear hormone receptor complex throughout the entire nonrepetitive genome of Drosophila melanogaster using a cell line (Kc167) that differentiates in response to 20-hydroxyecdysone (20-HE). 20-HE, the natural ligand of this complex, controls major aspects of insect development, including molting, metamorphosis, and reproduction. Direct gene targets of 20-HE signaling were identified by combining this physical binding-site profiling with gene expression profiling after treatment with 20-HE. We found 502 significant regions of ECR/USP binding throughout the genome. Only 42% of these regions are nearby genes that are 20-HE responsive in these cells. However, at least three quarters of the remaining ECR/USP regions are near 20-HE-regulated genes in other tissue and cell types during metamorphosis, suggesting that binding at many regulatory elements in the genome is largely noncell-type specific. The majority (21/26) of the early targets of 20-HE encode transcriptional regulatory factors. To determine whether any of these targets are required for the morphological differentiation of these cells, we used RNAi to reduce the expression of each of the 26 early genes. Accordingly, we found that three direct targets of ECR/USP—hairy, vrille, and Hr4—are required for cellular differentiation in response to the hormone. Initial mutational analysis of vrille in vivo reveals that it is required for metamorphosis.
Single-pass classification of all noncoding sequences in a bacterial genome using phylogenetic profiles
Authors: Marchais Antonin , Naville Magali , Bohn Chantal , Bouloc Philippe , Gautheret Daniel
Published: February 2009

Identification and characterization of functional elements in the noncoding regions of genomes is an elusive and time-consuming activity whose output does not keep up with the pace of genome sequencing. Hundreds of bacterial genomes lay unexploited in terms of noncoding sequence analysis, although they may conceal a wide diversity of novel RNA genes, riboswitches, or other regulatory elements. We describe a strategy that exploits the entirety of available bacterial genomes to classify all noncoding elements of a selected reference species in a single pass. This method clusters noncoding elements based on their profile of presence among species. Most noncoding RNAs (ncRNAs) display specific signatures that enable their grouping in distinct clusters, away from sequence conservation noise and other elements such as promoters. We submitted 24 ncRNA candidates from Staphylococcus aureus to experimental validation and confirmed the presence of seven novel small RNAs or riboswitches. Besides offering a powerful method for de novo ncRNA identification, the analysis of phylogenetic profiles opens a new path toward the identification of functional relationships between co-evolving coding and noncoding elements.
The effect of age on a visual learning task in the American cockroach
Authors: Brown Sheena , Strausfeld Nicholas
Published: February 2009

Neuronal modifications that accompany normal aging occur in brain neuropils and might share commonalties across phyla including the most successful group, the Insecta. This study addresses the kinds of neuronal modifications associated with loss of memory that occur in the hemimetabolous insect Periplaneta americana. Among insects that display considerable longevity, the American cockroach lives up to 64 wk and reveals specific cellular alterations in its mushroom bodies, higher centers that have been shown to be associated with learning and memory. The present results describe a vision-based learning paradigm, based on a modified Barnes maze, that compares memory in young (10-wk old), middle-aged (30-wk old), and aged adults (50-wk old). We show that not only is the performance of this task during the 14 training trials significantly decremented in aged cockroaches, but that aged cockroaches show significant impairment in successfully completing a crucial test involving cue rotation. Light and electron microscopical examination of the brains of these different age groups reveal major changes in neuron morphology and synaptology in the mushroom body lobes, centers shown to underlie place memory in this taxon.
Enhanced CREB-dependent gene expression increases the excitability of neurons in the basal amygdala and primes the consolidation of contextual and cued fear memory
Authors: Viosca Jose , Lopez de Armentia Mikel , Jancic Dragana , Barco Angel
Published: February 2009

Regulated expression of a constitutively active form of cAMP response element-binding protein (CREB), VP16-CREB, lowers the threshold for the late phase of long-term potentiation in the Schaffer collateral pathway in a de novo gene expression-independent manner, and increases the excitability and reduces afterhyperpolarization of neurons at the amygdala and the hippocampus. We explore the consequences of these changes on the consolidation of fear conditioning and find that the expression of VP16-CREB can bypass the requirement for de novo gene expression associated with long-term memory formation, suggesting that CREB-dependent gene expression is sufficient for fear memory consolidation.
Absorbed dose calculations for macromolecular crystals: improvements to RADDOSE
Authors: Paithankar Karthik S. , Owen Robin Leslie , Garman Elspeth F.
Published: February 2009

Radiation damage is an unwelcome and unavoidable aspect of macromolecular crystallography. In order to quantify the extent of X-ray-induced changes, knowledge of the dose (absorbed energy per unit mass) is necessary since it is the obvious metric against which to plot variables such as diffraction intensity loss and B factors. Significant improvements to the program RADDOSE for accurately calculating the dose absorbed by macromolecular crystals are presented here. Specifically, the probability of energy loss through the escape of fluorescent photons from de-excitation of an atom following photoelectric absorption is now included. For lighter elements, both the probability of fluorescence and of its subsequent escape from the crystal are negligible, but for heavier atoms the chance of fluorescence becomes significant (e.g. 30% as opposed to Auger electron decay from a K-shell excited iron atom), and this has the effect of reducing the absorbed dose. The effects of this phenomenon on dose calculations are presented for examples of crystals of an iron-containing protein, 2-selenomethionine proteins, a uranium derivatised protein, and for a nucleic acid sample. For instance, the inclusion of fluorescent escape results in up to a 27% decrease in the calculated absorbed dose for a typical selenomethionine protein crystal irradiated at the selenium K-edge.
A new aspect of specific radiation damage: hydrogen abstraction from organic molecules
Authors: Meents Alke , Dittrich Birger , Gutmann Sascha
Published: February 2009

Radiation damage is one of the major impediments in obtaining high-resolution structural information utilizing ionizing radiation. From electron microscopy it is known that electron irradiation of biological samples results in the formation of molecular hydrogen. In the present work radiation-induced structural changes of the polypeptide cyclosporine A were observed at a temperature of 100 K. Bond length changes are thought to be due to radiation-induced hydrogen abstraction which chemically modifies the molecules in an irreversible way. The resulting formation of molecular hydrogen might explain the observed increase of the crystal mosaicity, which has also been reported in many previous radiation damage studies.
Room-temperature scavengers for macromolecular crystallography: increased lifetimes and modified dose dependence of the intensity decay
Authors: Barker Adam I. , Southworth-Davies Robert J. , Paithankar Karthik S. , Carmichael Ian , Garman Elspeth F.
Published: February 2009

The advent of highly intense wiggler and undulator beamlines has reintroduced the problem of X-ray radiation damage in protein crystals even at cryogenic temperatures (100 K). Although cryocrystallography can be utilized for the majority of protein crystals, certain macromolecular crystals (e.g. of viruses) suffer large increases in mosaicity upon flash cooling and data are still collected at room temperature (293 K). An alternative mechanism to cryocooling for prolonging crystal lifetime is the use of radioprotectants. These compounds are able to scavenge the free radical species formed upon X-ray irradiation which are thought to be responsible for part of the observed damage. Three putative radioprotectants, ascorbate, 1,4-benzoquinone and 2,2,6,6-tetramethyl-4-piperidone (TEMP), were tested for their ability to prolong lysozyme crystal lifetimes at 293 K. Plots of relative summed intensity against dose were used as a metric to assess radioprotectant ability: ascorbate and 1,4-benzoquinone appear to be effective, whereas studies on TEMP were inconclusive. Ascorbate, which scavenges OH^{\bullet} radicals (k
OH = 8 × 109 M
−1 s−1) and electrons with a lower rate constant (k
e-(aq) = 3.0 × 108 M
−1 s−1), doubled the crystal dose tolerance, whereas 1,4-benzoquinone, which also scavenges both OH^{\bullet} radicals (k
OH = 1.2 × 109 M
−1 s−1) and electrons (k
e-(aq) = 1.2 × 1010 M
−1 s−1), offered a ninefold increase in dose tolerance at the dose rates used. Pivotally, these preliminary results on a limited number of samples show that the two scavengers also induced a striking change in the dose dependence of the intensity decay from a first-order to a zeroth-order process.
Yolk sac tumor but not seminoma or teratoma is associated with abnormal epigenetic reprogramming pathway and shows frequent hypermethylation of various tumor suppressor genes
Authors: Furukawa Shinsuke , Haruta Masayuki , Arai Yasuhito , Honda Shohei , Ohshima Junjiro , Sugawara Waka , Kageyama Yukio , Higashi Yotsuo , Nishida Kazunori , Tsunematsu Yukiko , Nakadate Hisaya , Ishii Masahiro , Kaneko Yasuhiko
Published: February 2009

Germ cell tumors (GCTs) are thought to arise from primordial germ cells (PGCs) that undergo epigenetic reprogramming: erasure of the somatic imprint in the genital ridge, and re‐establishment of the sex‐specific imprint at gametogenesis in the developing gonad. Previous studies suggested that GCTs show epigenetic patterns reflecting the reprogramming process of PGCs; however, epigenetic alterations of imprinted genes and their relationship with the methylation status of tumor suppressor genes (TSGs) have not been comprehensively studied. We analyzed the methylation status of the H19 and SNRPN differential methylated regions (DMRs) and the promoter region of 17 TSGs, and the expression status of H19, IGF2 and SNRPN in 45 GCTs, and found that 25 and 20 were in the normal and abnormal reprogramming pathways, respectively, defined on the basis of the methylation status of the two DMRs and the anatomical tumor site. The methylation pattern of the H19 and SNRPN DMRs was total erasure in seminomas, mostly physiological in teratomas, and various in yolk sac tumors. There were no correlations between the methylation status of the H19 DMR and mono‐ or biallelic expression of H19 or IGF2. Furthermore, we found that yolk sac tumors had a higher number of methylated TSGs than seminomas (P < 0.001) teratomas (P = 0.004) or other childhood tumors. While TSG methylation was known to have prognostic implications in various cancers, it did not affect the outcomes of patients with yolk sac tumor, suggesting that mechanisms of TSG methylation may be different between yolk sac tumor and other cancers. (Cancer Sci 2009; 100: 698–708)
Efficient inhibition of SDF‐1α‐mediated chemotaxis and HIV‐1 infection by novel CXCR4 antagonists
Authors: Iwasaki Yuki , Akari Hirofumi , Murakami Tsutomu , Kumakura Sei , Dewan Md. Zahidunnabi , Yanaka Mikiro , Yamamoto Naoki
Published: February 2009

CXC chemokine receptor‐4, the receptor for stromal cell‐derived factor‐1α as well as human immunodeficiency virus type 1, belongs to the chemokine receptor family and has been shown to play a critical role in directing the migration of cancer cells to sites of metastasis as well as human immunodeficiency virus type 1 infection. We had previously reported that a duodenally absorbable CXC chemokine receptor‐4 antagonist, KRH‐1636, showed a potent anti‐human immunodeficiency virus type 1 activity both in vivo and in vitro. In this study, we initially examined the effect of the compound and its derivatives on stromal cell‐derived factor‐1α‐mediated chemotaxis of cancer cells in order to evaluate if they could be applicable as a novel inhibitor of cancer metastasis. We found that both KRH‐2731 and KRH‐3955 were highly potent antagonists of stromal cell‐derived factor‐1α‐mediated chemotaxis, i.e. the derivatives exhibited 50% effective concentrations of less than 10 nM, for more than 1000‐fold efficacy improvement over the prototype KRH‐1636. We further demonstrated the greater anti‐human immunodeficiency virus type 1 efficacy of the derivatives compared with the original KRH‐1636. Taken together, the KRH‐1636 derivatives KRH‐2731 and KRH‐3955 may be promising as a novel inhibitory drug for cancer metastasis as well as for human immunodeficiency virus type 1 infection. (Cancer Sci 2009; 100: 778ndash;781)
Microbe‐associated molecular pattern (MAMP) signatures, synergy, size and charge: influences on perception or mobility and host defence responses
Authors: ASLAM SHAZIA N. , ERBS GITTE , MORRISSEY KATE L. , NEWMAN MARI‐ANNE , CHINCHILLA DELPHINE , BOLLER THOMAS , MOLINARO ANTONIO , JACKSON ROBERT W. , COOPER RICHARD M.
Published: February 2009

Triggering of defences by microbes has mainly been investigated using single elicitors or microbe‐associated molecular patterns (MAMPs), but MAMPs are released in planta as complex mixtures together with endogenous oligogalacturonan (OGA) elicitor. We investigated the early responses in Arabidopsis of calcium influx and oxidative burst induced by non‐saturating concentrations of bacterial MAMPs, used singly and in combination: flagellin peptide (flg22), elongation factor peptide (elf18), peptidoglycan (PGN) and component muropeptides, lipo‐oligosaccharide (LOS) and core oligosaccharides. This revealed that some MAMPs have additive (e.g. flg22 with elf18) and even synergistic (flg22 and LOS) effects, whereas others mutually interfere (flg22 with OGA). OGA suppression of flg22‐induced defences was not a result of the interference with the binding of flg22 to its receptor flagellin‐sensitive 2 (FLS2). MAMPs induce different calcium influx signatures, but these are concentration dependent and unlikely to explain the differential induction of defence genes [pathogenesis‐related gene 1 (PR1), plant defensin gene 1.2 (PDF1.2) and phenylalanine ammonia lyase gene 1 (PAL1)] by flg22, elf18 and OGA. The peptide MAMPs are potent elicitors at subnanomolar levels, whereas PGN and LOS at high concentrations induce low and late host responses. This difference might be a result of the restricted access by plant cell walls of MAMPs to their putative cellular receptors. flg22 is restricted by ionic effects, yet rapidly permeates a cell wall matrix, whereas LOS, which forms supramolecular aggregates, is severely constrained, presumably by molecular sieving. Thus, MAMPs can interact with each other, whether directly or indirectly, and with the host wall matrix. These phenomena, which have not been considered in detail previously, are likely to influence the speed, magnitude, versatility and composition of plant defences.
Characterization of a putative endoxylanase in the migratory plant‐parasitic nematodeRadopholus similis
Authors: HAEGEMAN ANNELIES , VANHOLME BARTEL , GHEYSEN GODELIEVE
Published: February 2009

Plant‐parasitic nematodes have developed an arsenal of enzymes to degrade the rigid plant cell wall. In this article, we report the presence of a putative endoxylanase in the migratory endoparasitic nematodeRadopholus similis. This enzyme is thought to facilitate the migration of the nematode, as it breaks down xylan, the major component of hemicellulose. The corresponding gene (Rs‐xyl1) was cloned and the sequence revealed three small introns. Interestingly, the position of all three introns was conserved in a putative endoxylanase fromMeloidogyne hapla, and the position of one intron was conserved in two endoxylanases fromMeloidogyne incognita, which suggests a common ancestral gene. The spatial and temporal expression of theRs‐xyl1gene was examined byin situhybridization and semi‐quantitative reverse transcriptase‐polymerase chain reaction. The putative protein consists of a signal peptide, a catalytic domain and a carbohydrate‐binding module (CBM). The catalytic domain showed similarity to both glycosyl hydrolase family 5 (GHF5) and GHF30 enzymes. Using Hidden Markov Model profiles and phylogenetic analysis, we were able to show that Rs‐XYL1 and its closest homologues are not members of GHF5, as suggested previously, but rather form a subclass within GHF30. Silencing the putative endoxylanase by double‐stranded RNA targeting of the CBM region resulted in an average decrease in infection of 60%, indicating that the gene is important for the nematode to complete its life cycle.
Home range and seasonal movements of Giraffa camelopardalis angolensis in the northern Namib Desert
Authors: Fennessy Julian
Published: February 2009

Estimates of home range size of giraffe in the northern Namib Desert were on average larger than those in other populations. In particular, the largest individual home range of any giraffe bull (1950 km2) was recorded – correlated with low population density, reduced forage density and increased searching for receptive cows. The predominant pattern of movement was linear, along the riparian environments, however, large‐scale irregular movements into tributaries and other areas were also recorded. Small‐scale movements by bulls into the mountains above the Hoarusib River as well as by cows into the northern tributaries of the Hoanib River were observed. Seasonal movements of giraffe were not as distinctive as those in other giraffe populations. Small‐scale habitat segregation was observed in the Hoarusib River study area with giraffe cows foraging only in the Gomatum River during the hot‐dry season. The first ever study of GPS satellite collared giraffe provided some of the highest resolution data on giraffe movements to date, including strong biphasic movement behaviour of giraffe over 24‐h periods.
Changing patterns of coeliac serology requests
Authors: EVANS K. E. , MALLOY A. R. , GORARD D. A.
Published: February 2009

Background  Accurate serological tests have revolutionized the diagnosis of coeliac disease.

Aim  To quantify the volume of coeliac serology requests at a district hospital over a decade, identify their origin, assess positivity rates and subsequent duodenal biopsy and histological confirmation rates.

Methods  Details of patients in whom coeliac serology was requested from 1997 to 2006 were obtained from laboratory databases. The origins of request were categorized into gastroenterology, general practice, paediatrics and other specialities. Duplicate requests were excluded.

Results  A total of 9976 serological tests were requested. Testing increased from 302 in 1997, to 1826 in 2006. In all, 66% of requests were in females. Tests in children accounted for 14–25% of each year’s total. General practitioner requests increased from 3.3% in 1997 to 52% in 2006. The proportion of positive serological results fell from 5.7% in 1997 to 2.6% in 2006. Duodenal biopsies were performed in approximately 85% of seropositive patients in earlier years and approximately 75% of seropositive patients in later years. Most nonbiopsied seropositive patients had serology requested by general practitioners. Biopsies confirmed coeliac disease in 91% of seropositive patients.

Conclusion  Increasingly, coeliac serological testing is requested by general practitioners. Twice as many females are tested. Increasing test numbers but diminishing positivity rates suggest testing is requested at lower symptom thresholds. Positive serological results are often not confirmed histologically.
Family‐centred care and health‐related quality of life of patients in paediatric neurosciences
Authors: Moore M. H. , Mah J. K. , Trute B.
Published: February 2009

Background  Little is known about the influence of contextual factors such as health services characteristics on health‐related quality of life (HRQL) for children with a neurological condition. To address this gap, we conducted an exploratory study of the relationship between family‐centred care (FCC) and HRQL outcomes in children from neurosciences clinics in a large acute care hospital.

Methods  A total of 187 family caregivers completed questionnaires regarding their socio‐demographic status, the severity of their children's condition (FIM™), perceptions of their children's HRQL (PedsQL 4.0) and their experiences of FCC (MPOC‐20). Hierarchical regression analyses explored the hypothesis that FCC is a significant predictor of children's HRQL, independent of illness severity.

Results  Illness severity and FCC jointly explained one‐third of the variance in children's total HRQL. When FCC was controlled for illness severity, it remained a significant predictor of physical, psychosocial and total HRQL scores.

Conclusions  This study provides evidence that the level of FCC is positively related to paediatric HRQL independent of neurological illness severity. The implication is that the uptake of FCC practices by service providers can positively impact the quality of life of children with neurological disorders.
Daily stressors and coping responses of children and adolescents with type 1 diabetes
Authors: Hema D. A. , Roper S. O. , Nehring J. W. , Call A. , Mandleco B. L. , Dyches T. T.
Published: February 2009

Background  Youth with type 1 diabetes cope with a variety of stressors related to daily life and disease management. While previous studies have focused on diabetes‐related stressors, little research has examined daily stressors.

Methods  In this qualitative descriptive study, daily stressors and coping responses of 19 children and 33 adolescents with type 1 diabetes (65% are female) were investigated. Participants recorded their own stressors and coping responses in daily diaries for 2–3 weeks.

Results  Five broad themes of daily stressors emerged: people, self, context, no stressor and ambiguous. Coping responses included three general themes: submission, personal responsibility and ambiguous. Younger children reported more stressors related to friends/peers and siblings (people), and adolescents described more stressors related to self, parents (people) and school (context). Younger children used more coping that involved choosing an alternate activity, helping others and an emotional response (taking personal responsibility), whereas adolescents used more coping that involved persistence, alternate thinking and talking things over (taking personal responsibility).

Conclusions  Youth with diabetes did not report stressors related to diabetes and its management as major themes in their daily lives. Clinical interventions based on perceptions of how youth understand and cope with stress are explored.
Translational Mini-Review Series on Immunology of Vascular Disease: Accelerated atherosclerosis in vasculitis
Authors: Cohen Tervaert J W
Published: February 2009

Premature atherosclerosis has been observed during the course of different systemic inflammatory diseases such as rheumatoid arthritis and sytemic lupus erythematosus. Remarkably, relatively few studies have been published on the occurrence of accelerated atherosclerosis in patients with vasculitis. In giant cell arteritis (GCA), mortality because of ischaemic heart disease is not increased. In addition, intima media thickness (IMT) is lower in patients with GCA than in age-matched controls. In contrast, IMT is increased significantly in Takayasu arteritis, another form of large vessel vasculitis occurring in younger patients. In Takayasu arteritis and in Kawasaki disease, a form of medium-sized vessel vasculitis, accelerated atherosclerosis has been well documented. In small vessel vasculitis because of anti-neutrophil cytoplasmic autoantibodies-associated vasculitis, cardiovascular diseases are a major cause of mortality. IMT measurements reveal conflicting results. During active disease these patients experience acceleration of the atherosclerotic process. However, when inflammation is controlled, these patients have atherosclerotic development as in healthy subjects. Several risk factors, such as diabetes and hypertension, are present more often in patients with vasculitis compared with healthy controls. In addition, steroids may be pro-atherogenic. Most importantly, many patients have impaired renal function, persistent proteinuria and increased levels of C-reactive protein, well-known risk factors for acceleration of atherosclerosis. Enhanced oxidation processes, persistently activated T cells and reduced numbers of regulatory T cells are among the many pathophysiological factors that play a role during acceleration of atherogenesis. Finally, autoantibodies that may be relevant for acceleration of atherosclerosis are found frequently in elevated titres in patients with vasculitis. Because patients have an increased risk for cardiovascular events, vasculitis should be treated with as much care as possible. In addition, treatment should be considered with angiotensin-converting-enzyme inhibitors and/or angiotensin receptor-1 blockers, statins and acetylsalicyl acid. Finally, classical risk factors for cardiovascular disease should be monitored and treated as much as possible.
Algal mats and insect emergence in rivers under Mediterranean climates: towards photogrammetric surveillance
Authors: POWER M. , LOWE R. , FUREY P. , WELTER J. , LIMM M. , FINLAY J. , BODE C. , CHANG S. , GOODRICH M. , SCULLEY J.
Published: February 2009

1. In a nitrogen (N)‐limited river subject to Mediterranean summer drought hydrology, the colour of macroalgal proliferations changed with successional and seasonal changes in epiphyte assemblages. New growth of the dominant macroalga,Cladophora glomerata, was green, as were proliferations ofOedogonium,MougeotiaandSpirogyra, which did not become heavily colonized with diatoms. GreenCladophoraturned yellow asCladophorafilaments became colonized by diatoms that were not N fixers, and turned rust‐coloured as later‐successional epiphyte assemblages became dominated by denseEpithemia turgidaandE. sorex, which both contain N‐fixing cyanobacterial endosymbionts.

2. The rate and composition of insect emergence from floating algal mats differed among proliferations of different colour. The rates of emergence (individuals day−1 500 cm−2) of nematoceran flies were three to 25 times greater from yellow or rusty‐colouredCladophoramats than from greenCladophora,OedogoniumorMougeotiamats that had lower epiphyte densities. Biomass emergence fromCladophoramats that were rusty in colour was eight to 10 times greater than from yellowCladophoramats, because larger nematocerans dominated in rusty mats (Chironominae versus Ceratopogonidae in yellow mats).

3. Proliferations ofEpithemia‐infestedCladophoraoccur at and above drainage areas of about 100 km2(channel widths of 25–30 m) in this river network, coinciding with the drainage area threshold where a step increase in concentration of total dissolved N is observed during summer.

4. In rivers under Mediterranean climate regimes, algal succession during the prolonged low flow season is less subject to stochastic interruption by spates than in rivers under more continental climates. Under these summer drought conditions, photogrammetric detection of colour changes in algal proliferations may help us track reach or basin‐scale change in their ecological functions.
Is structure or function a better measure of the effects of water abstraction on ecosystem integrity?
Authors: DEATH RUSSELL G. , DEWSON ZOË S. , JAMES ALEXANDER B. W.
Published: February 2009

1. Assessments of flow abstractions in streams often focus on changes to biological communities and in‐stream physical characteristics, with little consideration for changes in ecosystem functioning. It is unclear whether functional indicators of ecosystem health may be useful for assessing the impacts of reduced discharge on small streams.

2. We used weirs and diversions to reduce stream discharge by over 89% in three small New Zealand streams (11–84 L s−1), ranging in water quality from pristine to moderately impaired.

3. We used both structural (benthic invertebrates) and functional (drifting invertebrates, leaf breakdown, coarse particulate organic matter (CPOM) retention and primary productivity) measures of ecosystem integrity to compare responses to water abstraction in before‐after, control‐impact designed experiments during summer 2005.

4. At the pristine site, the density of invertebrates, taxon richness, Macroinvertebrate Community Index (MCI), Quantitative MCI, percentage of Ephemeroptera, Plecoptera and Trichoptera individuals and percentage of filter‐feeders decreased in response to reduced flows. Only taxon richness decreased at the mildly impaired stream, and reduced discharge had no effect on the invertebrate community at the stream with the lowest water quality.

5. We found that reduced discharge had little influence on the breakdown rate of willow leaves in mesh bags over 1 month. Primary productivity was also relatively insensitive to water abstraction. However, CPOM retention increased with decreased flows. Drift propensity of invertebrates increased at two sites but only within the first few days after flow reduction.

6. Structural measures of ecosystem integrity suggested that the impacts of water abstraction differed among streams of varying water quality, probably because of differences in the sensitivity of invertebrate assemblages in the three streams. In contrast, the three functional measures tested were generally less sensitive to water abstraction impacts, although understanding how stream ecosystems respond to water abstraction clearly requires that both are considered.
Endothelial cell‐specific molecule 2 (ECSM2) modulates actin remodeling and epidermal growth factor receptor signaling
Authors: Ma Fanxin , Zhang Dongmei , Yang Hansuo , Sun Huaqin , Wu Wen , Gan Yan , Balducci James , Wei Yu‐quan , Zhao Xia , Huang Yao
Published: February 2009

Endothelial cell‐specific molecules (ECSMs) play a pivotal role in the pathogenesis of many angiogenesis‐related diseases. Since its initial discovery, the exact function of human ECSM2 has not been defined. In this study, by database mining, we identified a number of hypothetical proteins across species exhibiting substantial sequence homology to the human ECSM2. We showed that ECSM2 is preferentially expressed in endothelial cells and blood vessels. Their characteristic structures and unique expression patterns suggest that ECSM2 is an evolutionarily conserved gene and may have important functions. We further explored the potential roles of human ECSM2 at the molecular and cellular level. Using a reconstitution mammalian cell system, we demonstrated that ECSM2 mainly resides at the cell membrane, is critically involved in cell‐shape changes and actin cytoskeletal rearrangement, and suppresses tyrosine phosphorylation signaling. More importantly, we uncovered that ECSM2 can cross‐talk with epidermal growth factor receptor (EGFR) to attenuate the EGF‐induced cell migration, possibly via inhibiting the Shc‐Ras‐ERK (MAP kinase) pathway. Given the importance of growth factor and receptor tyrosine kinase‐mediated signaling and cell migration in angiogenesis‐related diseases, our findings regarding the inhibitory effects of ECSM2 on EGF‐mediated signaling and cell motility may have important therapeutic implications.
Effects of fire on regional evapotranspiration in the central Canadian boreal forest
Authors: BOND‐LAMBERTY BEN , PECKHAM SCOTT D. , GOWER STITH T. , EWERS BRENT E.
Published: February 2009

Changes in fire regimes are driving the carbon balance of much of the North American boreal forest, but few studies have examined fire‐driven changes in evapotranspiration (ET) at a regional scale. This study used a version of the Biome‐BGC process model with dynamic and competing vegetation types, and explicit spatial representation of a large (106 km2) region, to simulate the effects of wildfire on ET and its components from 1948 to 2005 by comparing the fire dynamics of the 1948–1967 period with those of 1968–2005. Simulated ET averaged, over the entire temporal and spatial modeling domain, 323 mm yr−1; simulation results indicated that changes in fire in recent decades decreased regional ET by 1.4% over the entire simulation, and by 3.9% in the last 10 years (1996–2005). Conifers dominated the transpiration (EC) flux (120 mm yr−1) but decreased by 18% relative to deciduous broadleaf trees in the last part of the 20th century, when increased fire resulted in increased soil evaporation, lower canopy evaporation, lowerEC, and a younger and more deciduous forest. Well‐ and poorly drained areas had similar rates of evaporation from the canopy and soil, butECwas twice as high in the well‐drained areas. Mosses comprised a significant part of the evaporative flux to the atmosphere (22 mm yr−1). Modeled annual ET was correlated with net primary production, but not with temperature or precipitation; ET and its components were consistent with previous field and modeling studies. Wildfire is driving significant changes in hydrological processes by affecting mean stand age, forest species, and energy balance. These changes, particularly in poorly drained areas, may control the future carbon balance of the boreal forest.
Predicting population survival under future climate change: density dependence, drought and extraction in an insular bighorn sheep
Authors: Colchero Fernando , Medellin Rodrigo A. , Clark James S. , Lee Raymond , Katul Gabriel G.
Published: February 2009

Our understanding of the interplay between density dependence, climatic perturbations, and conservation practices on the dynamics of small populations is still limited. This can result in uninformed strategies that put endangered populations at risk. Moreover, the data available for a large number of populations in such circumstances are sparse and mined with missing data. Under the current climate change scenarios, it is essential to develop appropriate inferential methods that can make use of such data sets.

We studied a population of desert bighorn sheep introduced to Tiburon Island, Mexico in 1975 and subjected to irregular extractions for the last 10 years. The unique attributes of this population are absence of predation and disease, thereby permitting us to explore the combined effect of density dependence, environmental variability and extraction in a ‘controlled setting.’ Using a combination of nonlinear discrete models with long‐term field data, we constructed three basic Bayesian state space models with increasing density dependence (DD), and the same three models with the addition of summer drought effects.

We subsequently used Monte Carlo simulations to evaluate the combined effect of drought, DD, and increasing extractions on the probability of population survival under two climate change scenarios (based on the Intergovernmental Panel on Climate Change predictions): (i) increase in drought variability; and (ii) increase in mean drought severity.

The population grew from 16 individuals introduced in 1975 to close to 700 by 1993. Our results show that the population's growth was dominated by DD, with drought having a secondary but still relevant effect on its dynamics.

Our predictions suggest that under climate change scenario (i), extraction dominates the fate of the population, while for scenario (ii), an increase in mean drought affects the population's probability of survival in an equivalent magnitude as extractions. Thus, for the long‐term survival of the population, our results stress that a more variable environment is less threatening than one in which the mean conditions become harsher. Current climate change scenarios and their underlying uncertainty make studies such as this one crucial for understanding the dynamics of ungulate populations and their conservation.
Differential localization of carbachol‐ and bicuculline‐sensitive pontine sites for eliciting REM sleep‐like effects in anesthetized rats
Authors: FENIK VICTOR B. , KUBIN LESZEK
Published: February 2009

Carbachol, a cholinergic agonist, and GABAAreceptor antagonists injected into the pontine dorsomedial reticular formation can trigger rapid eye movement (REM) sleep‐like state. Data suggest that GABAergic and cholinergic effects interact to produce this effect but the sites where this occurs have not been delineated. In urethane‐anesthetized rats, in which carbachol effectively elicits REM sleep‐like episodes (REMSLE), we tested the ability of 10 nL microinjections of carbachol (10 mm) and bicuculline (0.5 or 2 mm) to elicit REMSLE at 47 sites located within the dorsal pontine reticular formation at the levels ‐8.00 to ‐10.80 from bregma (B) (Paxinos and Watson,The Rat Brain in Stereotaxic Coordinates, Academic Press, San Diego, 1997). At rostral levels, most carbachol and some bicuculline injections elicited REMSLE with latencies that gradually decreased from 242 to 12 s for carbachol and from 908 to 38 s for bicuculline for more caudal injection sites. As the latencies decreased, the durations of bicuculline‐elicited REMSLE increased from 104 s to over 38 min, and the effect was dose dependent, whereas the duration of carbachol‐elicited REMSLE changed little (104–354 s). Plots of REMSLE latency versus the antero‐posterior coordinates revealed that both drugs were maximally effective near B‐8.80. At levels caudal to B‐8.80, carbachol was effective at few sites, whereas bicuculline‐elicited REMSLE to at least B‐9.30 level. Thus, the bicuculline‐sensitive sites extended further caudally than those for carbachol and antagonism of GABAAreceptors both triggered REMSLE and controlled their duration, whereas carbachol effects on REMSLE duration were small or limited by its concurrent REMSLE‐opposing actions.
The relation between common sleep problems and emotional and behavioral problems among 2‐ and 3‐year‐olds in the context of known risk factors for psychopathology
Authors: REID GRAHAM J. , HONG RYAN Y. , WADE TERRANCE J.
Published: February 2009

The contribution of sleep problems to emotional and behavioral problems among young children within the context of known risk factors for psychopathology was examined. Data on 2‐ and 3‐year‐olds, representative of Canadian children without a chronic illness, from three cross‐sectional cohorts of the Canadian National Longitudinal Study of Child and Youth were analysed (n = 2996, 2822, and 3050). The person most knowledgeable (PMK), usually the mother, provided information about her child, herself, and her family. Predictors included: child health status and temperament; parenting and PMK depressive symptomatology; family demographics (e.g., marital status, income) and functioning. Child sleep problems included night waking and bedtime resistance. Both internalizing/emotional (i.e., anxiety) and externalizing/behavioral problems (i.e., hyperactivity, aggression) were examined. Adjusting for other known risk factors, child sleep problems accounted for a small, but significant, independent proportion of the variance in internalizing and externalizing problems. Structural equation models examining the pathways linking risk factors to sleep problems and emotional and behavioral problems were a good fit of the data. Results were replicated on two additional cross‐sectional samples. The relation between sleep problems and emotional and behavioral problems is independent of other commonly identified risk factors. Among young children, sleep problems are as strong a correlate of child emotional and behavioral problems as PMK depressive symptomatology, a well‐established risk factor for child psychopathology. Adverse parenting and PMK symptomatology, along with difficult temperament all contribute to both sleep problems and emotional and behavioral problems. Children’s sleep problems appear to exacerbate emotional and behavioral problems.
Time course of continuous positive airway pressure effects on central sleep apnoea in patients with chronic heart failure
Authors: ARZT MICHAEL , SCHULZ MARTINA , SCHROLL STEPHAN , BUDWEISER STEPHAN , BRADLEY T. DOUGLAS , RIEGGER GÜNTER A. J. , PFEIFER M.
Published: February 2009

Continuous positive airway pressure (CPAP) causes a variable immediate reduction in the frequency of central apnoeas and hypopnoeas in patients with congestive heart failure (CHF) and central sleep apnoea (CSA), but has beneficial mid‐term effects on factors known to destabilize the ventilatory control system. We, therefore, tested whether CPAP therapy leads, in addition to its short‐term effects on CSA, to a significant further alleviation of CSA after 12 weeks of treatment on the same CPAP level in such patients. CPAP therapy was initiated in 10 CHF patients with CSA. During the first night on CPAP, the pressure was stepwise increased to a target pressure of 8–12 cmH2O or the highest level the patients tolerated (<12 cmH2O). Throughout the second night (baseline CPAP), the achieved CPAP of the first night was applied. After 12 weeks of CPAP treatment, we performed a follow‐up polysomnography (12 weeks CPAP) on the same CPAP level (8.6 ± 1.1 cmH20). We found a significant reduction of the apnoea‐hypopnoea index (AHI) between the diagnostic polysomnography and baseline CPAP night (41.8 ± 19.2 versus 22.2 ± 12.6 events per hour; P = 0.005). The AHI further significantly decreased between the baseline CPAP night and the 12 weeks CPAP night on the same CPAP level (22.2 ± 12.6 versus 12.8 ± 11.0 events per hour; P = 0.028). We conclude that, in addition to its immediate effects, CPAP therapy leads to a time‐dependent alleviation of CSA in some CHF patients, indicating that in such patients neither clinical nor scientific decisions should be based on a short‐term trial of CPAP.
Determining optimal sleep position in patients with positional sleep‐disordered breathing using response surface analysis
Authors: LEE JUNG BOK , PARK YOUNG HWAN , HONG JUNG HWA , LEE SEUNG HOON , JUNG KI HWAN , KIM JE HYUNG , YI HYERYEON , SHIN CHOL
Published: February 2009

A lateral position (LP) during sleep is effective in reducing sleep disorder symptoms in mild or moderate sleep apnea patients. However, the effect of head and shoulder posture in LP on reducing sleep disorders has not been reported. In this study, effective sleeping positions and a combination of sleep position determinants were evaluated with respect to their ability to reduce snoring and apnea. The positions evaluated included the following: cervical vertebrae support with head tilting (CVS‐HT), scapula support (SS), and LP. A central composite design was applied for response surface analysis (RSA). Sixteen patients with mild or moderate positional sleep apnea and snoring who underwent polysomnography for two nights were evaluated. Based on an estimated RSA equation, LP (with a rotation of at least 30°) had the most dominant effect [P = 0.0057 for snoring rate, P = 0.0319 for apnea–hypopnea index (AHI)]. In addition, the LP was found to interact with CVS‐HT (P = 0.0423) for snoring rate and CVS‐HT (P = 0.0310) and SS (P = 0.0265) for AHI. The optimal sleep position reduced mild snoring by more than 80% (i.e. snoring rate in the supine position was <20%) and the snoring rate was approximately zero with a 40° rotation. To achieve at least 80% reduction of AHI, LP and SS should be >30° and/or 20 mm respectively. To determine an effective sleep position, CVS‐HT and SS, as well as the degree of the LP, should be concurrently considered in patients with positional sleep apnea or snoring.