bluuebunny/crossref_metadata_2025 huggingface dataset:
Matching and ideal free distributions
Authors: Houston Alasdair I.
Published: May 2008

Ideal free distributions characterise how a group of animals should be distributed between sources of food. In a simple case, the ratio of the number of animals matches the ratio of input rates, a result known as input matching. The matching law characterises how an animal should allocate responses to sources of food. If matching holds then the ratio of behaviour allocated to the sources matches the ratio of rewards obtained. Several authors have drawn attention to the analogy between input matching and the matching law. I present a critical review of this topic, and go on to investigate the claim that the distribution of animals should be analyzed in the same way that the generalized matching law is analyzed. This involves assuming that the relationship between the ratio of animals and the ratio of resources obeys a power law with two parameters, one corresponding to bias and the other to sensitivity. On this view, a plot of the log of the ratio of animals against the log of the ratio of input rates will be a straight line and its intercept and slope will provide estimates of bias and sensitivity. I show that this approach can give a good fit even when the underlying model does not result in a power law. A consequence is that the parameters estimated cannot be interpreted as bias and sensitivity. I conclude that there are no compelling reasons for analyzing the distribution of animals using log‐log plots, and the method has the disadvantage of encouraging the mistaken view that deviations from input matching follow a power law.
The effect of increased temperature and nitrogen deposition on decomposition in bogs
Authors: Breeuwer Angela , Heijmans Monique , Robroek Bjorn J. M. , Limpens Juul , Berendse Frank
Published: May 2008

Despite their low primary production, ombrotrophic peatlands have a considerable potential to store atmospheric carbon as a result of their extremely low litter decomposition rates. Projected changes in temperature and nitrogen (N) deposition may increase decomposition rates by their positive effects on microbial activity and litter quality, which can be expected to result in enhanced mass loss and N release from Sphagnum and vascular plant litter. This is the first study that examines the combined effects of increased temperature and N deposition on decomposition in bogs. We investigated mass loss and N release at four bog sites along a gradient from north Sweden to northeast Germany in which both temperature and N deposition increased from north to south. We performed two litterbag experiments: one reciprocal experiment with Eriophorum vaginatum litter and one experiment using recalcitrant (Sphagnum fuscum) and more degradable (Sphagnum balticum) Sphagnum litter collected from the most northern site. We measured mass loss and N release during two (Sphagnum) and three (E. vaginatum) years. The N concentration and decomposability of the E. vaginatum litter did not differ between the sites. Mass loss from E. vaginatum litter increased over the gradient from north to south, but there was no such effect on Sphagnum litter. N loss of all litter types was affected by collection site, incubation site and time and all interactions between these factors. N release in Sphagnum was positively related to N concentration.

We conclude that decomposition of vascular plants and Sphagnum litter is influenced by different environmental drivers, with enhanced temperatures stimulating mass loss of vascular plant litter, but not of Sphagnum. Enhanced N deposition increases Sphagnum litter N loss. As long‐term consequences of climate change will presumably entail a higher vascular plant production, overall litter decomposition rates are likely to increase, especially in combination with increased temperature.
The metabolism of lake plankton does not support the metabolic theory of ecology
Authors: De Castro Francisco , Gaedke Ursula
Published: May 2008

We tested if the metabolic theory of ecology (MTE) correctly predicts plankton metabolism in a temperate lake, based on a long‐term (about 15 years), high‐frequency dataset of body size, abundance and production, using two different techniques: least squares regression and maximum likelihood. For phytoplankton, the general fit was relatively poor (r2=0.53). The assumption of the MTE on temperature dependence of metabolism was not supported, and the assumed value of ¾ of the allometric exponent was barely within 95% confidence limits. For some of the models, the value of b was significantly higher than ¾. When radiation was included as an additional predictor, it improved the model considerably (r2=0.67). Including grazing by zooplankton reduced the model residuals during the summer period, when grazing is a dominant factor. The allometric exponent had virtually no effect for phytoplankton, due to little variability in average individual size. Zooplankton production, on the other hand, was better predicted by MTE, showing stronger effects of temperature and body size, the average of which varied by a factor of more than a hundred. However, the best‐fitting value of the allometric exponent for zooplankton was 0.85, and significantly higher than the ¾ predicted by the theory. The ratio of observed production to biomass for the entire plankton community declined linearly with the body size (in log‐log) with a slope corresponding to a value of b=0.85. We conclude that the MTE has little predictive power for the metabolism of lacustrine plankton, in particular for phytoplankton, and especially at the scale of variability of this study, and that this could be improved by incorporating radiation into the model.
Leaf δ13C reflects ecosystem patterns and responses of alpine plants to the environments on the Tibetan Plateau
Authors: Song Minghua , Duan Deyu , Chen Hui , Hu Qiwu , Zhang Feng , Xu Xingliang , Tian Yuqiang , Ouyang Hua , Peng Changhui
Published: May 2008

Leaf δ13C is an indicator of water‐use efficiency and provides useful information on the carbon and water balance of plants over longer periods. Variation in leaf δ13C between or within species is determined by plant physiological characteristics and environmental factors. We hypothesized that variation in leaf δ13C values among dominant species reflected ecosystem patterns controlled by large‐scale environmental gradients, and that within‐species variation indicates plant adaptability to environmental conditions. To test these hypotheses, we collected leaves of dominant species from six ecosystems across a horizontal vegetation transect on the Tibetan Plateau, as well as leaves of Kobresia pygmaea (herbaceous) throughout its distribution and leaves of two coniferous tree species (Picea crassifolia, Abies fabri) along an elevation gradient throughout their distribution in the Qilian Mountains and Gongga Mountains, respectively. Leaf δ13C of dominant species in the six ecosystems differed significantly, with values for evergreen coniferous<evergreen broadleaved tree<alpine shrub<sedges∼graminoid<xeromorphs. Leaf δ13C values of the dominant species and of K. pygmaea were negatively correlated with annual precipitation along a water gradient, but leaf δ13C of A. fabri was not significantly correlated with precipitation in habitats without water‐stress. This confirms that variation of δ13C between or within species reflects plant responses to environmental conditions. Leaf δ13C of the dominant species also reflected water patterns on the Tibetan Plateau, providing evidence that precipitation plays a primary role in controlling ecosystem changes from southeast to northwest on the Tibetan Plateau.
Cannabis use and later life outcomes
Authors: Fergusson David M. , Boden Joseph M.
Published: May 2008

Aim  To examine the associations between the extent of cannabis use during adolescence and young adulthood and later education, economic, employment, relationship satisfaction and life satisfaction outcomes.

Design  A longitudinal study of a New Zealand birth cohort studied to age 25 years.

Measurements  Measures of: cannabis use at ages 14–25; university degree attainment to age 25; income at age 25; welfare dependence during the period 21–25 years; unemployment 21–25 years; relationship quality; life satisfaction. Also, measures of childhood socio‐economic disadvantage, family adversity, childhood and early adolescent behavioural adjustment and cognitive ability and adolescent and young adult mental health and substance use.

Findings  There were statistically significant bivariate associations between increasing levels of cannabis use at ages 14–21 and: lower levels of degree attainment by age 25 (P < 0.0001); lower income at age 25 (P < 0.01); higher levels of welfare dependence (P < 0.0001); higher unemployment (P < 0.0001); lower levels of relationship satisfaction (P < 0.001); and lower levels of life satisfaction (P < 0.0001). These associations were adjusted for a range of potentially confounding factors including: family socio‐economic background; family functioning; exposure to child abuse; childhood and adolescent adjustment; early adolescent academic achievement; and comorbid mental disorders and substance use. After adjustment, the associations between increasing cannabis use and all outcome measures remained statistically significant (P < 0.05).

Conclusions  The results of the present study suggest that increasing cannabis use in late adolescence and early adulthood is associated with a range of adverse outcomes in later life. High levels of cannabis use are related to poorer educational outcomes, lower income, greater welfare dependence and unemployment and lower relationship and life satisfaction. The findings add to a growing body of knowledge regarding the adverse consequences of heavy cannabis use.
Gamma‐aminobutyric acid receptor genes and nicotine dependence: evidence for association from a case–control study
Authors: Agrawal Arpana , Pergadia Michele L. , Saccone Scott F. , Hinrichs Anthony L. , Lessov‐Schlaggar Christina N. , Saccone Nancy L. , Neuman Rosalind J. , Breslau Naomi , Johnson Eric , Hatsukami Dorothy , Montgomery Grant W. , Heath Andrew C. , Martin Nicholas G. , Goate Alison M. , Rice John P. , Bierut Laura J. , Madden Pamela A. F.
Published: May 2008

Aims  The gamma‐aminobutyric acid receptor A (GABRA) gene clusters on chromosomes 4 and 5 have been examined previously for their association with alcohol and drug dependence phenotypes. Compelling evidence suggests that GABRA2 is associated with alcohol and drug dependence. However, no study has investigated whether genes in the GABAA gene clusters are associated with nicotine dependence, an important phenotype with a high correlation to persistent smoking, the single most preventable cause of mortality world‐wide.

Design  Using data on 1050 nicotine‐dependent cases and 879 non‐dependent smoking controls, we used logistic regression to examine the association between single nucleotide polymorphisms (SNPs) in 13 genes in the GABAA receptor system as well as GABBR2 (a GABAB gene).

Findings  We found evidence for association between four SNPs in GABRA4, two SNPs in GABRA2 and one SNP in GABRE with nicotine dependence. These included a synonymous polymorphism in GABRA2 (rs279858), lying in a highly conserved region, which has been shown previously to be associated with alcohol and drug dependence. A non‐synonymous polymorphism (rs16859834/rs2229940) in GABRA4, also highly conserved, was associated at P‐value of 0.03. Significant haplotypes associated with nicotine dependence were found for GABRA2. No evidence for epistatic interactions were noted. Our study did not find evidence for an association between GABBR2 gene and nicotine dependence.

Conclusions  Given the potential role of compounds that enhance GABAergic neurotransmission in smoking cessation research, these findings have enormous potential for informing the wider field of addiction research.
Effects of voucher‐based incentives on abstinence from cigarette smoking and fetal growth among pregnant women
Authors: Heil Sarah H. , Higgins Stephen T. , Bernstein Ira M. , Solomon Laura J. , Rogers Randall E. , Thomas Colleen S. , Badger Gary J. , Lynch Mary Ellen
Published: May 2008

Aims  This study examined whether voucher‐based reinforcement therapy (VBRT) contingent upon smoking abstinence during pregnancy is an effective method for decreasing maternal smoking during pregnancy and improving fetal growth.

Design, setting and participants  A two‐condition, parallel‐groups, randomized controlled trial was conducted in a university‐based research clinic. A total of 82 smokers entering prenatal care participated in the trial.

Intervention  Participants were assigned randomly to either contingent or non‐contingent voucher conditions. Vouchers exchangeable for retail items were available during pregnancy and for 12 weeks postpartum. In the contingent condition, vouchers were earned for biochemically verified smoking abstinence; in the non‐contingent condition, vouchers were earned independent of smoking status.

Measurements  Smoking outcomes were evaluated using urine‐toxicology testing and self‐report. Fetal growth outcomes were evaluated using serial ultrasound examinations performed during the third trimester.

Findings  Contingent vouchers significantly increased point‐prevalence abstinence at the end‐of‐pregnancy (41% versus 10%) and at the 12‐week postpartum assessment (24% versus 3%). Serial ultrasound examinations indicated significantly greater growth in terms of estimated fetal weight, femur length and abdominal circumference in the contingent compared to the non‐contingent conditions.

Conclusions  These results provide further evidence that VBRT has a substantive contribution to make to efforts to decrease maternal smoking during pregnancy and provide new evidence of positive effects on fetal health.
Giant submarine collapse of a carbonate platform at the Turonian–Coniacian transition: The Ayabacas Formation, southern Peru
Authors: Callot Pierre , Sempere Thierry , Odonne Francis , Robert Emmanuel
Published: May 2008

The Ayabacas Formation of southern Peru is an impressive unit formed by the giant submarine collapse of the mid‐Cretaceous carbonate platform of the western Peru back‐arc basin (WPBAB), near the Turonian–Coniacian transition (∼90–89 Ma). It extends along the southwestern edge of the Cordillera Oriental and throughout the Altiplano and Cordillera Occidental over >80 000 km2 in map view, and represents a volume of displaced sediments of >10 000 km3. The collapse occurred down the basin slope, i.e. toward the SW. Six zones are characterised on the basis of deformational facies, and a seventh corresponds to the northeastern ‘stable’ area (Zone 0). Zones 1–3 display increasing fragmentation from NE to SW, and are composed of limestone rafts and sheets embedded in a matrix of mainly red, partly calcareous and locally sandy, mudstones to siltstones. In contrast, in Zones 4 and 5 the unit consists only of displaced and stacked limestone masses forming a ‘sedimentary thrust and fold system’, with sizes increasing to the southwest. In Zone 6, the upper part of the limestone succession consists of rafts and sheets stacked over the regularly bedded lower part. The triggering of this extremely large mass wasting clearly ensued from slope creation, oversteepening and seismicity produced by extensional tectonic activity, as demonstrated by the observation of synsedimentary normal faults and related thickness variations. Other factors, such as pore pressure increases or lithification contrasts probably facilitated sliding. The key role of tectonics is strengthened by the specific relationships between the basin and collapse histories and two major fault systems that cross the study area. The Ayabacas collapse occurred at a turning point in the Central Andean evolution. Before the event, the back‐arc basin had been essentially marine and deepened to the west, with little volcanic activity taking place at the arc. After the event, the back‐arc was occupied by continental to near‐continental environments, and was bounded to the southwest by a massive volcanic arc shedding debris and tuffs into the basin.
Pistachio vicilin, Pis v 3, is immunoglobulin E‐reactive and cross‐reacts with the homologous cashew allergen, Ana o 1
Authors: Willison L. N. , Tawde P. , Robotham J. M. , Penney R. M. , Teuber S. S. , Sathe S. K. , Roux K. H.
Published: May 2008

Background
Patients allergic to cashew nuts often report allergy to pistachio, which could be a result of cross‐reactivity between the two as both are members of the Anacardiaceae family.

Objective
Because cashew 7S globulin (vicilin, Ana o 1) is a recognized major allergen, we cloned the pistachio homologue and assayed it for IgE reactivity and cross‐reactivity with Ana o 1.

Methods
Degenerate primers for 7S globulin were used in PCR to amplify DNA from a pistachio cDNA library. An isolate was sequenced, cloned and expressed in Escherichia coli. Reactivity to the allergen was screened by dot blot using 19 pistachio and/or cashew‐allergic patients' sera. Cross‐reactivity was investigated by inhibition dot‐ and Western immunoblot assays using pistachio/cashew‐allergic patients' sera, and monoclonal antibodies (MAbs) raised against recombinant Ana o 1 (rAna o 1).

Results
An isolate was found that coded for a 7S vicilin‐like protein, designated Pis v 3. IgE reactivity to Pis v 3 was found in the serum of seven of the 19 (37%) patients with histories of allergy to both pistachio and cashew or who were allergic to cashew but had never eaten pistachio. The seven patients with IgE that recognized rPis v 3 also recognized rAna o 1. Six of nine anti‐rAna o 1 MAbs also showed reactivity to rPis v 3 on dot blots.

Conclusion
Of the 37% of pistachio/cashew‐allergic patients' sera that recognized the pistachio allergen, rPis v 3, all showed complete cross‐reactivity with rAna o 1. The data does not identify the primary sensitizing agent but suggests that IgE reactivity to rPis v 3 and rAna o 1 is focused on the most conserved regions of the proteins. Clinical histories suggest that in some cases, cashew was the sensitizing agent. rPis v 3 is a likely contributor to the observed co‐sensitivity to pistachio and cashew in some patients.
Effect of treatment with depot somatostatin analogue octreotide on primary hyperparathyroidism (PHP) in multiple endocrine neoplasia type 1 (MEN1) patients
Authors: Faggiano Antongiulio , Tavares Lidice Brandao , Tauchmanova Libuse , Milone Francesco , Mansueto Gelsomina , Ramundo Valeria , Del Basso De Caro Maria Laura , Lombardi Gaetano , De Rosa Gaetano , Colao Annamaria
Published: May 2008

Background  In patients with multiple endocrine neoplasia type 1 (MEN1), expression of somatostatin receptor (SST) in parathyroid adenomas and effectiveness of therapy with somatostatin analogues on primary hyperparathyroidism (PHP) have been scarcely investigated.

Objective  To evaluate the effects of depot long acting octreotide (OCT‐LAR) in patients with MEN1‐related PHP.

Patients  Eight patients with a genetically confirmed MEN1, presenting both PHP and duodeno‐pancreatic neuroendocrine tumours (NET), were enrolled.

Design  The initial treatment was OCT‐LAR 30 mg every 4 weeks. This therapy was established to stabilize the duodeno‐pancreatic NET before to perform parathyroidectomy for PHP. Before OCT‐LAR therapy, a SST scintigraphy was performed in all patients. SST subtype 2A immunohistochemistry was performed on parathyroid tumour samples from three patients undergone parathyroidectomy after OCT‐LAR therapy.

Measurements  Serum concentrations of PTH, calcium and phosphorus as well as the 24‐h urine calcium :  creatinine ratio and the renal threshold phosphate concentration were evaluated before and after OCT‐LAR.

Results  After OCT‐LAR therapy, hypercalcaemia and hypercalciuria normalized in 75% and 62·5% of patients, respectively, and serum phosphorus and renal threshold phosphate significantly increased. Serum PTH concentrations significantly decreased in all patients and normalized in two of them. SST subtype 2A immunostaining was found in all parathyroid adenomas investigated, while SST scintigraphy showed a positive parathyroid tumour uptake in three of eight patients (37·5%).

Conclusion  Six months of OCT‐LAR therapy controlled hypercalcaemia and hypercalciuria in two‐thirds of patients with MEN1‐related PHP. Direct OCT‐LAR effects mediated by binding to SST expression on parathyroid tumour cells are likely the main mechanism to explain the activity of this compound on calcium and phosphorus abnormalities in MEN1 PHP.
Heterogeneity of lymphoid tissue inducer cell populations present in embryonic and adult mouse lymphoid tissues
Authors: Kim Mi‐Yeon , Rossi Simona , Withers David , McConnell Fiona , Toellner Kai‐Michael , Gaspal Fabrina , Jenkinson Eric , Anderson Graham , Lane Peter J. L.
Published: May 2008

Lymphoid tissue inducer (LTi) cells have a well established role in secondary lymphoid tissue development. Here, we report on the heterogeneity of LTi cells based on their CD4 and chemokine receptor expression. The CD4− LTi‐cell population has a similar phenotype to the CD4+ population, with similar chemokine‐receptor‐expressing subsets. In both embryonic and adult spleen the CD4− LTi‐cell population is comparable as a proportion of total splenocytes to its CD4+ counterpart. In contrast, different proportions of CD4+ and CD4− LTi cells are found in different lymph nodes. Both CD4+ and CD4− LTi cells share the anatomical location and are associated with vascular cell adhesion molecule‐1‐positive stromal cells in spleen and lymph nodes. The numbers of both CD4+ and CD4− LTi cells in adult spleen are augmented in the presence of B cells. With the exception of CD4, there is a strong correlation coefficient (0·89) for gene expression between the two populations. Polymerase chain reaction analysis of individual CD4+ and CD4− LTi cells shows that a similar proportion in embryonic and adult spleen co‐expressed both CXCR5 and CCR7 or CXCR5 alone: 84·6% for adult CD4+ and 87·6% for adult CD4−; 95·3% for embryonic CD4+ and 91·5% for embryonic CD4−. Consistently fewer CCR7 single‐positive cells were found in the CD4+ and CD4− fractions in the embryo.
Adjuvant modulation of the cytokine balance in Mycobacterium tuberculosis subunit vaccines; immunity, pathology and protection
Authors: Agger Else Marie , Cassidy Joseph P. , Brady Joseph , Korsholm Karen S. , Vingsbo‐Lundberg Carina , Andersen Peter
Published: May 2008

It is known that protection against tuberculosis is mediated primarily by T helper type 1 (Th1) cells but the influence of the Th1/Th2 balance of a vaccination response on the subsequent protection and pathology during infection has not been studied in detail. We designed a panel of Ag85B‐ESAT‐6 subunit vaccines based on adjuvants with different Th1/Th2‐promoting activities and studied cellular responses, bacterial replication and pathology in the lungs of mice infected with Mycobacterium tuberculosis. All vaccines induced cell‐mediated and humoral responses but with markedly different interferon‐γ : interleukin‐5 (IFN‐γ : IL‐5) and immunoglobulin G1 (IgG1) : IgG2 ratios. The vaccines promoted different levels of control of bacterial replication with the most efficient protection being exerted by cationic liposomes containing monophosphoryl lipid A and low to completely absent immunity with conventional aluminium. The level of protection correlated with the amount of IFN‐γ produced in response to the vaccine whereas there was no inverse correlation with the level of IL‐5. Characterizing a protective response was an accelerated recruitment of IL‐17 and IFN‐γ‐producing lymphocytes resulting in the early formation of granulomas containing clustered inducible nitric oxide synthase‐activated macrophages. In comparison, non‐protected mice exhibited a different inflammatory infiltrate rich in neutrophil granulocytes. This study indicates that the adjuvant component of a tuberculosis vaccine may be crucial in determining the kinetics by which effective granulomas, pivotal in controlling bacterial growth, are formed.
Endogenous and exogenous controls of root life span, mortality and nitrogen flux in a longleaf pine forest: root branch order predominates
Authors: Guo Dali , Mitchell Robert J. , Withington Jennifer M. , Fan Ping‐Ping , Hendricks Joseph J.
Published: May 2008

Root life span regulates the quantity and quality of root‐derived organic matter transferred to the soil organic matter pool. However, poor understanding of the rates and controls of root life span has hindered the prediction of carbon (C) flow and nutrient cycling dynamics at the ecosystem scale.

We examined the effects of root branch order, root diameter, mycorrhizal colonization, season of birth, depth in the soil, nitrogen (N) fertilization and foliage removal on root life span in a longleaf pine (Pinus palustrisMill.) forest from 2001 to 2004 using minirhizotron and soil monolith sampling.

Among all factors, root branch order had the strongest and most consistent effect on life span, with higher order roots having a 46% longer life span than roots one order lower.

Within first order roots, mycorrhizal colonization significantly increased root life span by > 45% in 2 of 3 years.

Roots born in winter and spring generally lived longer than roots born in summer and autumn. Root life span was positively correlated with depth in the soil and root diameter, but the correlations were weaker than with order, year and season. Neither N fertilization nor foliage removal had a significant impact on root life span.

When biomass mortality and associated N flux were estimated based on order‐specific mean life span, N concentration and ecosystem‐scale biomass estimates, first order roots constituted approximately 50% of the total biomass mortality and > 60% of the N flux for the first three root orders combined.

Synthesis.Our results show that (i) root branch order was the strongest predictor of life span among all covariates and can effectively partition the distal longleaf pine root systems into three or more populations with different turnover rates; (ii) only a fraction of fine roots turns over annually, whereas models of C cycles assume an annual turnover for the entire fine root system. We conclude that an order‐based approach holds greater promise than the traditional diameter class approach for evaluating the role of different fine root populations in C flow and nutrient cycling.
Looking inside the box: bacterial transistor arrays
Authors: Shimizu Thomas S. , Le Novère Nicolas
Published: May 2008

One often compares cells to computers, and signalling proteins to transistors. Location and wiring of those molecular transistors is paramount in defining the function of the subcellular chips. The bacterial chemotactic sensing apparatus is a large, stable assembly consisting of thousands of receptors, signal transducing kinases and linking proteins, and is responsible for the motile response of the bacterium to environmental signals, whether chemical, mechanical, or thermal. Because of its rich functional repertoire despite its relative simplicity, this chemosome has attracted much attention from both experimentalists and theoreticians, and the bacterial chemotaxis response becoming a benchmark in Systems Biology. Structural and functional models of the chemotactic device have been developed, often based on particular assumptions regarding the topology of the receptor lattice. In this issue of Molecular Microbiology, Briegel et al. provide a detailed view of the receptor arrangement, unravelling the wiring of the molecular signal processors.
EhMLBP is an essential constituent of the Entamoeba histolytica epigenetic machinery and a potential drug target
Authors: Lavi Tal , Siman‐Tov Rama , Ankri Serge
Published: May 2008

EhMLBP has been identified as a protein that specifically binds to methylated long interspersed element (LINE) retrotransposons and rDNA in Entamoeba histolytica. EhMLBP is unique to Entamoeba parasites, which makes this protein a possible drug target for treating amebiasis. In the work described here, we evaluated this potential. Downregulation of EhMLBP using antisense technology resulted in trophozoites with impaired growth and cytopathic activity. This indicated that EhMLBP is an essential protein. With a view to identifying new antiamebic agents, we tested the effect of distamycin A, a drug with known antimalarial activity, on the growth of the parasite and on the ability of EhMLBP to bind to DNA. Distamycin A (IC50 = 13 μM) efficiently inhibited the growth of E. histolytica. Indeed, distamycin A at a concentration of 5–20 μM inhibited the binding of EhMLBP to methylated LINE DNA in vitro. As an additional approach to identify molecules that inhibit EhMLBP activity, a selective biopanning assay was performed using the DNA‐binding domain of EhMLBP and the Ph.D.‐12 phage display peptide library. Remarkably, four out of the 11 phages selected after three rounds of biopanning expressed the peptide ‘SYFDQNERWGAP’ (Pept3) at their surface. The binding of EhMLBP to Pept3 was confirmed by ELISA. Phage expressing Pept3 inhibited the binding of EhMLBP to RT LINE DNA. The growth of E. histolytica transfectants expressing Pept3 was significantly impaired compared with that of trophozoites expressing a scrambled version of Pept3. These results highlight EhMLBP as an essential constituent of the parasite E. histolytica and a novel target for antiamebic chemotherapy.
Characterization and pathogenicity of Colletotrichum species associated with anthracnose on chilli (Capsicum spp.) in Thailand
Authors: Than P. P. , Jeewon R. , Hyde K. D. , Pongsupasamit S. , Mongkolporn O. , Taylor P. W. J.
Published: May 2008

Fungal isolates from chilli (Capsicum spp.) fruits in Thailand that showed typical anthracnose symptoms were identified as Colletotrichum acutatum, C. capsici and C. gloeosporioides. Phylogenetic analyses from DNA sequence data of ITS rDNA and β‐tubulin (tub2) gene regions revealed three major clusters representing these three species. Among the morphological characters examined, colony growth rate and conidium shape in culture were directly correlated with the phylogenetic groupings. Comparison with isolates of C. gloeosporioides from mango and C. acutatum from strawberry showed that host was not important for phylogenetic grouping. Pathogenicity tests validated that all three species isolated from chilli were causal agents for chilli anthracnose when inoculated onto fruits of the susceptible Thai elite cultivar Capsicum annuum cv. Bangchang. Cross‐infection potential was shown by C. acutatum isolates originating from strawberry, which produced anthracnose on Bangchang. Interestingly, only C. acutatum isolates from chilli were able to infect and produce anthracnose on PBC 932, a resistant genotype of Capsicum chinense. This result has important implications for Thai chilli breeding programmes in which PBC 932 is being hybridized with Bangchang to incorporate anthracnose resistance into chilli cultivars.
A host‐pathogen simulation model: powdery mildew of grapevine
Authors: Calonnec A. , Cartolaro P. , Naulin J.‐M. , Bailey D. , Langlais M.
Published: May 2008

An epidemiological model simulating the growth of a single grapevine stock coupled to the dispersal and disease dynamics of the airborne conidia of the powdery mildew pathogen Erysiphe necator was developed. The model input variables were either climatic (temperature, wind speed and direction) or related to the pathogen (location and onset of primary infection). The environmental input variables dictated plant growth and pathogen spread (latent period, infection, lesion growth, conidial spore production and release). Input parameters characterized the crop production system, the growth conditions and the epidemiological characteristics of the pathogen. Output described, at each time step, number, age and pattern of healthy and infected organs, infected and infectious leaf area and aerial density of spores released. Validation of the model was achieved by comparing model output with experimental data for epidemics initiated at different times of host growth. Epidemic behaviour for two contrasting years of crop development and 7 phenological stages at the time of primary infection (PI) was examined. For PI occurring at day 115 a vine with late budbreak (1998) showed 58% of primary leaves diseased at flowering compared with only 19% for a vine with early budbreak (2003). Depending on the phenological stage at PI (1–4 leaves), the proportion of diseased primary leaves decreased from 42% to 6% at flowering. Simulations suggested that differences resulted from the interplay between the timing of the first sporulation event, the phenological stage at the time of initial infection, and the age structure and spatial distribution of the leaf population.
If the antibody fails – a mass Western approach
Authors: Lehmann Ute , Wienkoop Stefanie , Tschoep Hendrik , Weckwerth Wolfram
Published: May 2008

Sucrose‐phosphate synthase (SPS) has attracted the interest of plant scientists for decades. It is the key enzyme in sucrose metabolism and is under investigation in various plant species, e.g. spinach, tobacco, poplar, resurrection plants, maize, rice, kiwi and Arabidopsis thaliana. In A. thaliana, there are four distinct SPS isoforms. Their expression is thought to depend on environmental conditions and plant tissue. However, these data were derived from mRNA expression levels only. No data on SPS protein identification from crude extracts have been available until now. An antibody approach failed to distinguish the four isoforms. Therefore, we developed a method for SPS quantification and isoform‐specific identification in A. thaliana complex protein samples. Samples were separated on SDS‐PAGE, digested and directly applied to liquid chromatography/triple‐stage quadrupole mass spectrometry (LC/TSQ‐MS). In this approach, known as mass Western, samples were analysed in multi‐reaction monitoring (MRM) mode, so that all four SPS isoforms could be measured in one experiment. In addition to the relative quantification, stable isotope‐labelled internal peptide standards allowed absolute quantification of SPS proteins. Protein extracts from various plant tissues, samples harvested during the day or the night, and cold‐stressed plants were analysed. The stress‐specific SPS5a isoform showed increased concentrations in cold‐stressed leaf material.
Identification of Arabidopsis thaliana phloem RNAs provides a search criterion for phloem‐based transcripts hidden in complex datasets of microarray experiments
Authors: Deeken Rosalia , Ache Peter , Kajahn Inga , Klinkenberg Joern , Bringmann Gerhard , Hedrich Rainer
Published: May 2008

Phloem‐mobile signals play a major role in plant nutrition, development and communication. In the latter context, phloem‐mobile RNAs have been associated with signalling between plant tissues. In this study, we focused on the identification of transcripts in the shoot phloem of the model plant Arabidopsis thaliana. To isolate transcripts expressed in phloem parenchyma cells and in companion cell–sieve element complexes, we used laser microdissection coupled to laser pressure catapulting (LMPC). Mobile transcripts in sieve elements were isolated from leaf phloem exudates. After optimization of sampling and fixation, RNA of high quality was isolated from both sources. The modifications to the RNA amplification procedure described here were well suited to production of RNA of sufficient yield and quality for microarray experiments. Microarrays hybridized with LMPC‐derived phloem tissue or phloem sap RNA allowed differentiation between phloem‐expressed and mobile transcript species. Using this set of phloem transcripts and comparing them with microarrays derived from databases of light, hormone and nutrient treatment experiments, we identified phloem‐derived RNAs as mobile, potential long‐distance signals. Our dataset thus provides a search criterion for phloem‐based signals hidden in the complex datasets of microarray experiments. The availability of these comprehensive phloem transcript profiles will facilitate reverse‐genetic studies and forward‐genetic screens for phloem and long‐distance RNA signalling mutants.
Puberty as a highly vulnerable developmental period for the consequences of cannabis exposure
Authors: Schneider Miriam
Published: May 2008

During puberty, neuronal maturation of the brain, which began during perinatal development, is completed such that the behavioral potential of the adult organism can be fully achieved. These maturational events and processes of reorganization are needed for the occurrence of adult behavioral performance but simultaneously render the organism highly susceptible to perturbations, such as exposure to psychoactive drugs, during this critical developmental time span. Considering the variety of maturational processes occurring in the endocannabinoid system during this critical period, it is not surprising that the still‐developing brain might by highly susceptible to cannabis exposure. Emerging evidence from human studies and animal research demonstrates that an early onset of cannabis consumption might have lasting consequences on cognition, might increase the risk for neuropsychiatric disorders, promote further illegal drug intake and increase the likelihood of cannabis dependence. These findings suggest that young people represent a highly vulnerable cannabis consumer group and that they run a higher risk than adult consumers of suffering from adverse consequences from cannabinoid exposure. The aim of the present review is to provide an overview over the possible deleterious residual cannabinoid effects during critical periods of postnatal maturation and to offer a more precise delineation of the vulnerable time window for cannabinoid exposure.
Innate and Learned Predator Recognition Mediated by Chemical Signals in Eurycea nana
Authors: Epp Kristen J. , Gabor Caitlin R.
Published: May 2008

Effective and efficient predator recognition and avoidance are essential for the persistence of prey populations, especially in habitats where non‐native predators have been introduced. Predator recognition studies are commonly couched within a learned or innate dichotomous framework; however, characteristics of some systems or species could favor innate recognition combined with the ability to alter avoidance responses based on experience with predators. Eurycea nana is a fully aquatic salamander inhabiting a system with a diverse, yet temporally stable, community of native and non‐native opportunistically foraging fish predators. To examine predator recognition, we examined avoidance responses (decreased activity) of predator‐naïve (first‐generation, captive‐reared) and predator‐experienced (recently collected) E. nana to the chemical cues of a native predator, a non‐native predator, a non‐predator, and a blank control. Both predator‐naïve and predator‐experienced E. nana significantly lowered activity in response to the native fish predator when compared with a blank control. Interestingly, predator‐naïve E. nana decreased activity in response to the non‐native fish predator while predator‐experienced E. nana did not. These results indicate that while there is an innate component to predator recognition in E. nana, experience and risk assessment may also be important.
Who Cares? Males Provide Most Parental Care in a Monogamous Nesting Cuckoo
Authors: Maurer Golo
Published: May 2008

Cuckoos hold a prominent position in the study of parental care, because they show the greatest variation of any bird family in the way they care for their offspring. Despite this, few data are available on cuckoos with biparental care even though it is the most common form of parental care in cuckoos and birds in general. Here I describe the breeding behaviour of the pheasant coucal,Centropus phasianinus, an old‐world nesting cuckoo. I show that males almost exclusively build the nest and incubate and brood the young alone both at night and during the day. The incubation pattern of short,c. 40 min bouts on the nest interspersed with 20 min frequent recesses is well suited to incubation by a single parent and is widespread amongst birds. Males also defend the nestlings and deliver 80% of the feeds to the young consisting of insects (65%), frogs and reptiles. Females did not compensate for their fewer feeding visits by delivering more vertebrates than males. Although coucal males get little help feeding, the hourly feeding rate of 3.8 feeds per brood (1.4 feeds/nestling) exceed that of the few nesting cuckoos studied to date and matches that of other tropical non‐passerines. Predominantly male care is found in less than 5% of birds, mainly species with reversed sexual size dimorphism or reversed sex‐roles. Its evolution, especially in monogamous species, remains puzzling. The breeding behaviour of pheasant coucals illustrates a possible transitional stage in the evolution of polyandry and interspecific brood parasitism in cuckoos.
Male Nest Choice in Sand Gobies, Pomatoschistus minutus
Authors: Wong Bob B. M. , Lehtonen Topi K. , Lindström Kai
Published: May 2008

Although material resources can have a direct bearing on the fitness of both sexes, few studies have actually examined resource‐based preferences from a male choice perspective. In sand gobies, Pomatoschistus minutus, the size of a male’s nest influences his attractiveness to females and also dictates the number of eggs he can receive. Thus, one might expect males to prefer larger nests. However, an earlier study of marine sand gobies from a population with a surplus of nest sites and high nest predation found that males exhibited size‐assortative nest preferences. Here, we investigated male nest preferences from a brackish population characterised by a chronic nest shortage but lower predation risk. A survey of naturally settled nests in the field (shells and rocks) showed a pattern of size‐assortative nest occupancy consistent with the previously studied population, with larger males occupying larger (i.e. rock) nests. However, when offered a choice of potential nests in the absence of male competition, we found that all male gobies in our population, irrespective of their own body size, actually preferred larger nests. Moreover, a predilection towards large nests superseded any preferences based on nest colour. Our results not only indicate the existence of male preferences for material resources but, considered in the light of previous work, also suggest that such preferences may vary among populations and, importantly, may not necessarily be realised in a competitive setting.
Incidental Sanctions and the Evolution of Direct Benefits
Authors: Wagner William E. , Basolo Alexandra L.
Published: May 2008

Recent research has shown that a variety of traits that increase male success in mating and sperm competition can impose costs on females, resulting in antagonistic coevolution between the sexes. Yet, in many animals, females are known to receive direct benefit from their mates, including many in which female multiple mating results in intense sperm competition among males. The most common explanation for the evolution of male‐provided direct benefits is pre‐mating female choice based on benefit quality. This explanation is insufficient, however, for those direct benefits that females cannot directly assess prior to mating. Given that intrasexual selection will often favor male traits that increase female mating costs, many types of direct benefits can thus be difficult to explain. In this paper, we review four additional hypotheses for the evolution of male‐provided direct benefits, and present a fifth hypothesis that has received little attention. This latter hypothesis proposes that selection often favors female reproductive tactics that are conditional upon the past costs and benefits of mating. These conditional female reproductive tactics should evolve because the quality of the benefit provided by a previous mate can change the costs and benefits of alternative reproductive decisions. Furthermore, many of the conditional reproductive tactics we might expect females to express should incidentally penalize males which provide lower quality direct benefits. These conditional reproductive tactics may thus play an important role in determining whether females incur costs or receive benefits from their mates. In addition to favoring the evolution of direct benefits, we argue that conditional female reproductive tactics may also favor reliable signaling of benefit quality. The most common explanation for reliable signaling is the handicap mechanism, which proposes that differential costs of signaling prevent low quality males from deceptively producing attractive signals. For direct benefits, however, there is a second type of deception: males which produce attractive signals and can afford to provide high quality direct benefits may choose to cheat on the advertised benefit. The handicap mechanism does nothing to prevent cheating on direct benefits by males which can afford to produce attractive signals, and is thus insufficient for ensuring reliable signaling of benefit quality. In contrast, conditional female reproductive tactics that incidentally penalize low benefit males should also penalize males which cheat on the benefits advertised by their signals.
Novelty Responses in a Bird Assemblage Inhabiting an Urban Area
Authors: Echeverría Alejandra Isabel , Vassallo Aldo Iván
Published: May 2008

Neophobia, or the hesitancy to approach a novel food item, object, or place, is an important factor influencing the foraging behavior of animals. Environmental factors (e.g. rapid anthropogenic changes, migration into new habitats) are associated with novelty in feeding ecology and may affect neophobic responses. Mechanisms that underlie the differential neophobic response may involve complex interactions with the environment: post‐fledging experience in a greater diversity of habitats or in habitats that are more complex may contribute to reduced neophobia. In a previous study, it was observed that some urbanized species, in particular house sparrows (Passer domesticus) and shiny cowbirds (Molothrus bonariensis) show high levels of neophobia. This study was carried out in a suburban marsh of Cortaderia selloana, a relatively simple and predictable ecosystem as compared to urban areas. For this reason, in the present study, we explored novelty responses of bird species inhabiting an urban area, representing a complex environment. The results were compared to those obtained previously in the suburban marsh. We found unexpectedly high levels of neophobia in house sparrows, but shiny cowbirds showed a somewhat neophilic response. In the presence of novel objects, house sparrows tended to enter the feeders alone, while shiny cowbirds tended to forage in groups. We found no differences in latencies to forage or in visit duration between habitat types, but the proportion of individuals that visited the feeders when novel objects were present was lower in the urban area for house sparrows and eared doves (Zenaida auriculata). The results are discussed in the context of invasion success and feeding innovation in shiny cowbirds.