bluuebunny/crossref_metadata_2025 huggingface dataset:
Superintegrable three-body systems on the line
Authors: Chanu Claudia , Degiovanni Luca , Rastelli Giovanni
Published: November 2008

We consider classical three-body interactions on a Euclidean line depending on the reciprocal distance of the particles and admitting four functionally independent quadratic in the momentum first integrals. These systems are multiseparable, superintegrable, and equivalent (up to rescalings) to a one-particle system in the three-dimensional Euclidean space. Common features of the dynamics are discussed. We show how to determine quantum symmetry operators associated with the first integrals considered here but do not analyze the corresponding quantum dynamics. The conformal multiseparability is discussed and examples of conformal first integrals are given. The systems considered here in generality include the Calogero, Wolfes, and other three-body interactions widely studied in mathematical physics.
Ecology of diamondback moth in Australian canola: landscape perspectives and the implications for management
Authors: Furlong Michael J. , Spafford Helen , Ridland Peter M. , Endersby Nancy M. , Edwards Owain R. , Baker Greg J. , Keller Michael A. , Paull Cate A.
Published: November 2008

The ecology of diamondback moth (DBM), Plutella xylsotella L. (Lepidoptera: Plutellidae), and records of its frequent, but sporadic, population outbreaks in the canola agroecosystems of southern and western Australia are reviewed. The migratory capacity of DBM, possible maintenance of pest populations on brassicaceous weeds and forage crops, resistance to commonly used pyrethroid insecticides, a lack of effective natural enemies (due to disruption by insecticides and difficulties associated with colonising the vast areas of canola crops) and suitable climatic conditions during critical phases of the crop cycle are all likely to contribute to the observed pest outbreaks. A greater understanding of the ecology of DBM in the canola landscape is fundamental to improving its management in the crop but relevant long-term DBM abundance data are currently lacking. Five critical research issues are identified: (i) improved understanding of the factors which determine regional movement patterns of diamondback in canola-growing areas; (ii) the development and implementation of flexible insecticide resistance management strategies; (iii) better understanding of canola crop colonisation by natural enemies of DBM and their population dynamics under current and alternative insecticide application strategies; (iv) greater appreciation of the interactions between DBM and its crop and weedy host plants; and (v) the development of validated simulation models to aid in the forecasting of possible DBM outbreaks. Each issue represents a significant challenge but all must be addressed if the development of a sustainable integrated strategy for the management of DBM in Australian canola is to become a reality.
Managing ecosystem services in broadacre landscapes: what are the appropriate spatial scales?
Authors: Schellhorn Nancy A. , Macfadyen Sarina , Bianchi Felix J. J. A. , Williams David G. , P. Zalucki Myron
Published: November 2008

Over the past 200 years agriculture has expanded throughout Australia. The culmination of clearing and cultivating land at the farm scale has resulted in highly modified landscapes and a perceived loss of ecosystem services from pest control and pollination. We examine the literature: (i) to identify the appropriate spatial scale for managing pests, natural enemies and pollinators; and (ii) for evidence that farm-scale changes (due to agricultural intensification) across a landscape have resulted in a tipping point favouring pests and hindering pollinators. Although there is limited information to draw firm conclusions, the evidence suggests that actions undertaken on individual farms have an impact both on their neighbours and regionally, and that the culmination of these actions can lead to changes in population dynamics of pests, natural enemies and pollinators. For major pest species, there is reasonable evidence that grain growers may benefit from improved management and higher yields by implementing area-wide pest management strategies on a landscape scale in collaboration with growers of other crops that also share these pests. As yet, for natural enemies and pollinators there is little direct evidence that similar area-wide initiatives will have a greater effect than management strategies aimed at the field and farm level. Managing pests, natural enemies and pollinators beyond the scale of the field or farm is technically and socially challenging and will required a well defined research agenda, as well as compromise, balance and trading among stakeholders. We highlight critical knowledge gaps and suggest approaches for designing and managing landscapes for ecosystem services.
The parafibromin tumor suppressor protein inhibits cell proliferation by repression of the
c-myc
proto-oncogene
Authors: Lin Ling , Zhang Jian-Hua , Panicker Leelamma M. , Simonds William F.
Published: November 2008

Parafibromin is a tumor suppressor protein encoded by
HRPT2
, a gene recently implicated in the hereditary hyperparathyroidism–jaw tumor syndrome, parathyroid cancer, and a subset of kindreds with familial isolated hyperparathyroidism. Human parafibromin binds to RNA polymerase II as part of a PAF1 transcriptional regulatory complex. The physiologic targets of parafibromin and the mechanism by which its loss of function can lead to neoplastic transformation are poorly understood. We show here that RNA interference with the expression of parafibromin or Paf1 stimulates cell proliferation and increases levels of the
c-myc
proto-oncogene product, a DNA-binding protein and established regulator of cell growth. This effect results from both c-myc protein stabilization and activation of the
c-myc
promoter, without alleviation of the
c-myc
transcriptional pause. Chromatin immunoprecipitation demonstrates the occupancy of the
c-myc
promoter by parafibromin and other PAF1 complex subunits in native cells. Knockdown of
c-myc
blocks the proliferative effect of RNA interference with parafibromin or Paf1 expression. These experiments provide a previously uncharacterized mechanism for the anti-proliferative action of the parafibromin tumor suppressor protein resulting from PAF1 complex-mediated inhibition of the
c-myc
proto-oncogene.
Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule
Authors: Politi Yael , Metzler Rebecca A. , Abrecht Mike , Gilbert Benjamin , Wilt Fred H. , Sagi Irit , Addadi Lia , Weiner Steve , Gilbert P. U. P. A.
Published: November 2008

Sea urchin larval spicules transform amorphous calcium carbonate (ACC) into calcite single crystals. The mechanism of transformation is enigmatic: the transforming spicule displays both amorphous and crystalline properties, with no defined crystallization front. Here, we use X-ray photoelectron emission spectromicroscopy with probing size of 40–200 nm. We resolve 3 distinct mineral phases: An initial short-lived, presumably hydrated ACC phase, followed by an intermediate transient form of ACC, and finally the biogenic crystalline calcite phase. The amorphous and crystalline phases are juxtaposed, often appearing in adjacent sites at a scale of tens of nanometers. We propose that the amorphous-crystal transformation propagates in a tortuous path through preexisting 40- to 100-nm amorphous units, via a secondary nucleation mechanism.
The molecular face of lipid rafts in model membranes
Authors: Risselada H. Jelger , Marrink Siewert J.
Published: November 2008

Cell membranes contain a large number of different lipid species. Such a multicomponent mixture exhibits a complex phase behavior with regions of structural and compositional heterogeneity. Especially domains formed in ternary mixtures, composed of saturated and unsaturated lipids together with cholesterol, have received a lot of attention as they may resemble raft formation in real cells. Here we apply a simulation model to assess the molecular nature of these domains at the nanoscale, information that has thus far eluded experimental determination. We are able to show the spontaneous separation of a saturated phosphatidylcholine (PC)/unsaturated PC/cholesterol mixture into a liquid-ordered and a liquid-disordered phase with structural and dynamic properties closely matching experimental data. The near-atomic resolution of the simulations reveals remarkable features of both domains and the boundary domain interface. Furthermore, we predict the existence of a small surface tension between the monolayer leaflets that drives registration of the domains. At the level of molecular detail, raft-like lipid mixtures show a surprising face with possible implications for many cell membrane processes.
A unique cell division machinery in the Archaea
Authors: Lindås Ann-Christin , Karlsson Erik A. , Lindgren Maria T. , Ettema Thijs J. G. , Bernander Rolf
Published: November 2008

In contrast to the cell division machineries of bacteria, euryarchaea, and eukaryotes, no division components have been identified in the second main archaeal phylum, Crenarchaeota. Here, we demonstrate that a three-gene operon,
cdv
, in the crenarchaeon
Sulfolobus acidocaldarius
, forms part of a unique cell division machinery. The operon is induced at the onset of genome segregation and division, and the Cdv proteins then polymerize between segregating nucleoids and persist throughout cell division, forming a successively smaller structure during constriction. The
cdv
operon is dramatically down-regulated after UV irradiation, indicating division inhibition in response to DNA damage, reminiscent of eukaryotic checkpoint systems. The
cdv
genes exhibit a complementary phylogenetic range relative to FtsZ-based archaeal division systems such that, in most archaeal lineages, either one or the other system is present. Two of the Cdv proteins, CdvB and CdvC, display homology to components of the eukaryotic ESCRT-III sorting complex involved in budding of luminal vesicles and HIV-1 virion release, suggesting mechanistic similarities and a common evolutionary origin.
Selective saturation of slow endocytosis at a giant glutamatergic central synapse lacking dynamin 1
Authors: Lou Xuelin , Paradise Summer , Ferguson Shawn M. , De Camilli Pietro
Published: November 2008

Exocytosis of synaptic vesicles is rapidly followed by compensatory plasma membrane endocytosis. The efficiency of endocytosis varies with experimental conditions, but the molecular basis for this control remains poorly understood. Here, the function of dynamin 1, the neuron-specific member of a family of GTPases implicated in vesicle fission, was investigated with high temporal resolution via membrane capacitance measurements at the calyx of Held, a giant glutamatergic synapse. Endocytosis at dynamin 1 KO calyces was the same as in wild type after weak stimuli, consistent with the nearly normal ultrastructure of mutant synapses. However, following stronger stimuli, the speed of slow endocytosis, but not of other forms of endocytosis, failed to scale with the increased endocytic load. Thus, high level expression of dynamin 1 is essential to allow the slow, clathrin-mediated endocytosis, which accounts for the bulk of the endocytic response, to operate efficiently over a wide range of activity.
The Ignorance Economy
1
Authors: Roberts Joanne , Armitage John
Published: November 2008

The purpose of this article is to investigate the concept of ignorance. The article employs ignorance and related writings on the lack of knowledge and new Information and Communication Technologies (ICTs), education, and on the state of being ignorant with the aim of expounding an ignorant approach to the critique of the knowledge economy. This perspective necessitates a discussion of those subjects and objects apparently lacking in knowledge in addition to deliberations on the nature of new ICTs. Various studies by educators, economists, and management theorists are introduced and examined as instances of an ignorant standpoint on the knowledge economy. The authors argue and find that whilst an ignorant viewpoint regarding the knowledge economy might initially appear as one that is itself founded on a state of ignorance, a deeper investigation reveals its usefulness when considering the knowledge economy. Thus, the value of the article is that it introduces the concept of the ignorance economy and considers it from an original standpoint in the light of ongoing debates over the knowledge economy.
Data Wealth, Data Poverty, Science and Cyberinfrastructure
1
Authors: Sawyer Steve
Published: November 2008

Changes in access to data are leading to rapid ‘data wealth’ in some scientific fields, even as others remain ‘data‐poor’. Furthermore, the current attention towards developing computer‐based infrastructures and digital access to common data sets—the basics of scientific ‘cyberinfrastructures’—are too‐focused on fields of study characterized by data wealth. To better understand the implications of this twin pursuit of data wealth and cyberinfrastructure, I articulate how data‐poor scholarly fields differ from data‐rich fields. I then suggest four actions that scholars in data‐poor fields can take to improve their work’s value to science and society in lieu of being data‐rich and propose three design considerations for cyberinfrastructures that can better support data‐poor scholarly endeavors.
Semaphorin 4D regulates gonadotropin hormone–releasing hormone-1 neuronal migration through PlexinB1–Met complex
Authors: Giacobini Paolo , Messina Andrea , Morello Francesca , Ferraris Nicoletta , Corso Simona , Penachioni Junia , Giordano Silvia , Tamagnone Luca , Fasolo Aldo
Published: November 2008

In mammals, reproduction is dependent on specific neurons secreting the neuropeptide gonadotropin hormone–releasing hormone-1 (GnRH-1). These cells originate during embryonic development in the olfactory placode and migrate into the forebrain, where they become integral members of the hypothalamic–pituitary–gonadal axis. This migratory process is regulated by a wide range of guidance cues, which allow GnRH-1 cells to travel over long distances to reach their appropriate destinations. The Semaphorin4D (Sema4D) receptor, PlexinB1, is highly expressed in the developing olfactory placode, but its function in this context is still unknown. Here, we demonstrate that PlexinB1-deficient mice exhibit a migratory defect of GnRH-1 neurons, resulting in reduction of this cell population in the adult brain. Moreover, Sema4D promotes directional migration in GnRH-1 cells by coupling PlexinB1 with activation of the Met tyrosine kinase (hepatocyte growth factor receptor). This work identifies a function for PlexinB1 during brain development and provides evidence that Sema4D controls migration of GnRH-1 neurons.
P bodies promote stress granule assembly in Saccharomyces cerevisiae
Authors: Buchan J. Ross , Muhlrad Denise , Parker Roy
Published: November 2008

Recent results indicate that nontranslating mRNAs in eukaryotic cells exist in distinct biochemical states that accumulate in P bodies and stress granules, although the nature of interactions between these particles is unknown. We demonstrate in Saccharomyces cerevisiae that RNA granules with similar protein composition and assembly mechanisms as mammalian stress granules form during glucose deprivation. Stress granule assembly is dependent on P-body formation, whereas P-body assembly is independent of stress granule formation. This suggests that stress granules primarily form from mRNPs in preexisting P bodies, which is also supported by the kinetics of P-body and stress granule formation both in yeast and mammalian cells. These observations argue that P bodies are important sites for decisions of mRNA fate and that stress granules, at least in yeast, primarily represent pools of mRNAs stalled in the process of reentry into translation from P bodies.
EGFR and ADAMs Cooperate to Regulate Shedding and Endocytic Trafficking of the Desmosomal Cadherin Desmoglein 2
Authors: Klessner Jodi L. , Desai Bhushan V. , Amargo Evangeline V. , Getsios Spiro , Green Kathleen J.
Published: November 2008

Regulation of classic cadherins plays a critical role in tissue remodeling during development and cancer; however, less attention has been paid to the importance of desmosomal cadherins. We previously showed that EGFR inhibition results in accumulation of the desmosomal cadherin, desmoglein 2 (Dsg2), at cell–cell interfaces accompanied by inhibition of matrix metalloprotease (MMP)-dependent shedding of the Dsg2 ectodomain and tyrosine phosphorylation of its cytoplasmic domain. Here, we show that EGFR inhibition stabilizes Dsg2 at intercellular junctions by interfering with its accumulation in an internalized cytoplasmic pool. Furthermore, MMP inhibition and ADAM17 RNAi, blocked shedding and depleted internalized Dsg2, but less so E-cadherin, in highly invasive SCC68 cells. ADAM9 and 15 silencing also impaired Dsg2 processing, supporting the idea that this desmosomal cadherin can be regulated by multiple ADAM family members. In contrast, ADAM10 siRNA enhanced accumulation of a 100-kDa Dsg2 cleavage product and internalized pool of Dsg2. Although both MMP and EGFR inhibition increased intercellular adhesive strength in control cells, the response to MMP-inhibition was Dsg2-dependent. These data support a role for endocytic trafficking in regulating desmosomal cadherin turnover and function and raise the possibility that internalization and regulation of desmosomal and classic cadherin function can be uncoupled mechanistically.
How frugal is mother nature with haplotypes?
Authors: Climer Sharlee , Jäger Gerold , Templeton Alan R. , Zhang Weixiong
Published: November 2008

Motivation: Inference of haplotypes from genotype data is crucial and challenging for many vitally important studies. The first, and most critical step, is the ascertainment of a biologically sound model to be optimized. Many models that have been proposed rely partially or entirely on reducing the number of unique haplotypes in the solution.

Results: This article examines the parsimony of haplotypes using known haplotypes as well as genotypes from the HapMap project. Our study reveals that there are relatively few unique haplotypes, but not always the least possible, for the datasets with known solutions. Furthermore, we show that there are frequently very large numbers of parsimonious solutions, and the number increases exponentially with increasing cardinality. Moreover, these solutions are quite varied, most of which are not consistent with the true solutions. These results quantify the limitations of the Pure Parsimony model and demonstrate the imperative need to consider additional properties for haplotype inference models. At a higher level, and with broad applicability, this article illustrates the power of combinatorial methods to tease out imperfections in a given biological model.

Contact:  weixiong.zhang@wustl.edu
Phases of Infection and Gene Expression of Fusarium graminearum During Crown Rot Disease of Wheat
Authors: Stephens Amber E. , Gardiner Donald M. , White Rosemary G. , Munn Alan L. , Manners John M.
Published: November 2008

Fusarium graminearum causes head blight (FHB) and crown rot (CR) diseases in wheat. Compared with FHB, CR symptom development occurs slowly, usually taking 4 to 8 weeks to become visible. To characterize CR development, we used histological and real-time quantitative polymerase chain reaction analyses to assess fungal colonization during a timecourse of infection. Three distinct phases of infection were identified: i) initial spore germination with formation of a superficial hyphal mat at the inoculation point, ii) colonization of the adaxial epidermis of the outer leaf sheath and mycelial growth from the inoculation point to the crown, concomitant with a drop in fungal biomass, and iii) extensive colonization of the internal crown tissue. Fungal gene expression was examined during each phase using Affymetrix GeneChips. In total, 1,839 F. graminearum genes were significantly upregulated, including some known FHB virulence genes (e.g., TRI5 and TRI14), and 2,649 genes were significantly downregulated in planta compared with axenically cultured mycelia. Global comparisons of fungal gene expression with published data for FHB showed significant similarities between early stages of FHB and CR. These results indicate that CR disease development involves distinct phases of colonization, each of which is associated with a different fungal gene expression program.
Functional Analysis of a Multicopy Host-Selective ACT-Toxin Biosynthesis Gene in the Tangerine Pathotype of Alternaria alternata Using RNA Silencing
Authors: Miyamoto Y. , Masunaka A. , Tsuge T. , Yamamoto M. , Ohtani K. , Fukumoto T. , Gomi K. , Peever T. L. , Akimitsu K.
Published: November 2008

Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a serious disease of commercially important tangerines and their hybrids. The pathogen produces host-selective ACT toxin, and several genes (named ACTT) responsible for ACT-toxin biosynthesis have been identified. These genes have many paralogs, which are clustered on a small, conditionally dispensable chromosome, making it difficult to disrupt entire functional copies of ACTT genes using homologous recombination-mediated gene disruption. To overcome this problem, we attempted to use RNA silencing, which has never been employed in Alternaria spp., to knock down the functional copies of one ACTT gene with a single silencing event. ACTT2, which encodes a putative hydrolase and is present in multiple copies in the genome, was silenced by transforming the fungus with a plasmid construct expressing hairpin ACTT2 RNAs. The ACTT2 RNA-silenced transformant (S-7-24-2) completely lost ACTT2 transcripts and ACT-toxin production as well as pathogenicity. These results indicated that RNA silencing may be a useful technique for studying the role of ACTT genes responsible for host-selective toxin biosynthesis in A. alternata. Further, this technique may be broadly applicable to the analysis of many genes present in multiple copies in fungal genomes that are difficult to analyze using recombination-mediated knockdowns.
Arabidopsis Small RNAs and Their Targets During Cyst Nematode Parasitism
Authors: Hewezi Tarek , Howe Peter , Maier Tom R. , Baum Thomas J.
Published: November 2008

Plant-parasitic cyst nematodes induce the formation of specialized feeding cells in infected roots, which involves plant developmental processes that have been shown to be influenced by microRNAs (miRNAs) and other small RNAs. This observation provided the foundation to investigate the potential involvement of small RNAs in plant–cyst nematode interactions. First, we examined the susceptibilities of Arabidopsis DICER-like (dcl) and RNA-dependent RNA polymerase (rdr) mutants to the sugar beet cyst nematode Heterodera schachtii. The examined mutants exhibited a trend of decreased susceptibility, suggesting a role of small RNAs mediating gene regulation processes during the plant–nematode interaction. Second, we generated two small RNA libraries from aseptic Arabidopsis roots harvested at 4 and 7 days after infection with surface-sterilized H. schachtii. Sequences of known miRNAs as well as novel small interfering (si)RNAs were identified. Following this discovery, we used real-time reverse-transcriptase polymerase chain reaction to quantify a total of 15 Arabidopsis transcripts that are known targets of six of the different miRNA families found in our study (miR160, miR164, miR167, miR171, miR396, and miR398) in inoculated and noninoculated Arabidopsis roots. Our analyses showed mostly negative correlations between miRNA accumulation and target gene mRNA abundance, suggesting regulatory roles of these miRNAs during parasitism. Also, we identified a total of 125 non-miRNA siRNAs. Some of these siRNAs perfectly complement protein-coding mRNAs or match transposon or retrotransposon sequences in sense or antisense orientations. We further quantified a group of siRNAs in H. schachtii-inoculated roots. The examined siRNAs exhibited distinct expression patterns in infected and noninfected roots, providing additional evidence for the implication of small RNAs in cyst nematode parasitism. These data lay the foundation for detailed analyses of the functions of small RNAs during phytonematode parasitism.
Scale effects in species distribution models: implications for conservation planning under climate change
Authors: Seo Changwan , Thorne James H , Hannah Lee , Thuiller Wilfried
Published: November 2008

Predictions of future species' ranges under climate change are needed for conservation planning, for which species distribution models (SDMs) are widely used. However, global climate model-based (GCM) output grids can bias the area identified as suitable when these are used as SDM predictor variables, because GCM outputs, typically at least 50×50 km, are biologically coarse. We tested the assumption that species ranges can be equally well portrayed in SDMs operating on base data of different grid sizes by comparing SDM performance statistics and area selected by four SDMs run at seven grid sizes, for nine species of contrasting range size. Area selected was disproportionately larger for SDMs run on larger grid sizes, indicating a cut-off point above which model results were less reliable. Up to 2.89 times more species range area was selected by SDMs operating on grids above 50×50 km, compared to SDMs operating at 1 km
2
. Spatial congruence between areas selected as range also diverged as grid size increased, particularly for species with ranges between 20 000 and 90 000 km
2
. These results indicate the need for caution when using such data to plan future protected areas, because an overly large predicted range could lead to inappropriate reserve location selection.
On the mechanics of the golf swing
Authors: Sharp Robin S
Published: November 2008

A perspective of the golf swing is defined, and current knowledge of swing mechanics is reviewed. The implications of previous research are collected. A conventional arm–club simulation model is set up and used to show that an apparently important result from the literature is incorrect. The swing model is fitted, through a parametric optimization process, to data relating to expert golfers. The kinematic deficiencies of the arm–club model are pointed out and a shoulder–arm–club simulation model with shaft flexibility is developed. Parameters of the shoulder–arm–club model for best matching the expert-golfer data are found by optimization. The torques generated by the golfers are deduced. The shoulder–arm–club model is then applied for finding whether or not improvements to the observed torque histories are possible, with a positive result. A pattern for the optimal use of available driving torques is established. Scaling of the problem to help the understanding of the relationship between large and small players is studied through dimensional analysis. Several contributory conclusions are drawn.
Biotemplated syntheses of anisotropic nanoparticles
Authors: Hall Simon R
Published: November 2008

The technological advances predicted (or, perhaps, demanded) for the twenty-first century are intimately linked to the crystallochemically controlled synthesis of high-performance functional materials. To answer the new hendiatris of ‘smaller, faster, better’, the manufacture of these materials as nanoparticles has become a scientific
noblesse oblige
. Direct incorporation into the next generation of electronic devices will necessitate anisotropic forms of these materials, be they nanowires, nanotapes or nanotubes. Chemists have recently discovered that, in addition to the classical methods of anisotropic growth, new routes allow more complex materials to be synthesized in these morphologies. This review describes, using a series of examples, how the morphology of functional materials can be controlled using templated growth mediated by a biopolymer. By involving a biopolymer in the synthetic protocol, anisotropic nanoparticles and assemblages of even quite complex materials can be generated in syntheses that are simple, elegant and highly specific.
Converging migration routes of Eurasian hobbiesFalco subbuteocrossing the African equatorial rain forest
Authors: Strandberg Roine , Klaassen Raymond H.G , Hake Mikael , Olofsson Patrik , Alerstam Thomas
Published: November 2008

Autumn migration of adult Eurasian hobbiesFalco subbuteofrom Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1° S, 15° E). The birds migrated south or southwest to approximately 10° N, where they changed to south-easterly courses. The maximal spread between routes at 10° N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15° E, similar to the hobbies, or at 30–40° E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.
Compensatory investment in zebra finches: females lay larger eggs when paired to sexually unattractive males
Authors: Bolund Elisabeth , Schielzeth Holger , Forstmeier Wolfgang
Published: November 2008

The classical version of the differential allocation hypothesis states that, when females reproduce over their lifetime with partners that differ in their genetic quality, they should invest more in reproduction with high-quality males. However, in species with lifetime monogamy, such as the zebra finch, partner quality will typically remain the same. In this case, the compensatory investment (CI) hypothesis predicts higher investment for low-quality males, because low genetic quality offspring are more dependent on maternal resources. Here, we show that female zebra finches invested more resources, both in terms of egg volume and yolk carotenoid content, when paired to a low genetic quality male, as judged from his previous ability to obtain extra-pair paternity in aviary colonies. We also found that females deposited slightly larger amounts of testosterone into eggs when paired to a low parental quality male, as judging from his previous success in rearing offspring. This is, to our knowledge, the first experimental support for the CI hypothesis in a species with lifetime monogamy. We stress that in more promiscuous species, the benefits of classical differential allocation may partly be neutralized by the supposed benefits of CI.
Disruptive selection in a bimodal population of Darwin's finches
Authors: Hendry Andrew P , Huber Sarah K , De León Luis F , Herrel Anthony , Podos Jeffrey
Published: November 2008

A key part of the ecological theory of adaptive radiation is disruptive selection during periods of sympatry. Some insight into this process might be gained by studying populations that are bimodal for dual-context traits, i.e. those showing adaptive divergence and also contributing to reproductive isolation. A population meeting these criteria is the medium ground finch (Geospiza fortis) of El Garrapatero, Santa Cruz Island, Galápagos. We examined patterns of selection in this population by relating individual beak sizes to interannual recaptures during a prolonged drought. Supporting the theory, disruptive selection was strong between the two beak size modes. We also found some evidence of selection against individuals with the largest and smallest beak sizes, perhaps owing to competition with other species or to gaps in the underlying resource distribution. Selection may thus simultaneously maintain the current bimodality while also constraining further divergence. Spatial and temporal variation inG. fortisbimodality suggests a dynamic tug of war among factors such as selection and assortative mating, which may alternatively promote or constrain divergence during adaptive radiation.
Visual influences on auditory spatial learning
Authors: King Andrew J
Published: November 2008

The visual and auditory systems frequently work together to facilitate the identification and localization of objects and events in the external world. Experience plays a critical role in establishing and maintaining congruent visual–auditory associations, so that the different sensory cues associated with targets that can be both seen and heard are synthesized appropriately. For stimulus location, visual information is normally more accurate and reliable and provides a reference for calibrating the perception of auditory space. During development, vision plays a key role in aligning neural representations of space in the brain, as revealed by the dramatic changes produced in auditory responses when visual inputs are altered, and is used throughout life to resolve short-term spatial conflicts between these modalities. However, accurate, and even supra-normal, auditory localization abilities can be achieved in the absence of vision, and the capacity of the mature brain to relearn to localize sound in the presence of substantially altered auditory spatial cues does not require visuomotor feedback. Thus, while vision is normally used to coordinate information across the senses, the neural circuits responsible for spatial hearing can be recalibrated in a vision-independent fashion. Nevertheless, early multisensory experience appears to be crucial for the emergence of an ability to match signals from different sensory modalities and therefore for the outcome of audiovisual-based rehabilitation of deaf patients in whom hearing has been restored by cochlear implantation.
Evolution of small inversions in chloroplast genome: a case study from a recurrent inversion in angiosperms
Authors: Catalano Santiago Andrés , Saidman Beatriz Ofelia , Vilardi Juan César
Published: November 2008

Small inversions (SIs) in the chloroplast genome of angiosperms are ubiquitous. These inversions are always flanked by inverted repeats (palindromes or quasipalindromes) between approximately 8 and 50 bp long that form a hairpin structure when the DNA is single‐stranded. We evaluated different methodological and empirical issues about SI evolution. As a case study, we analysed an SI recently discovered in thepsbC–trnS intergenic region ofProsopis(Fabaceae). First, we analysed how inversions can be optimized in cases where the inverted segment also shows indels and substitutions, proposing a method based on Fixed States Optimization. Second, we evaluated the occurrence of this inversion on a phylogeny that includes the major lineages of angiosperms. Finally, we assessed whether the occurrence of this inversion was related to the thermodynamic stability of the hairpin structure (measured by its corresponding free energy) and/or the length of the palindromes by using a modified version of Maddison’s Concentrated Changes Test. Hairpin structure was conserved in most of the 154 sequences analysed, with the inversion taking place at least 10 times in different lineages (monocots, magnoliids, rosids). As was previously proposed for other SIs, our analysis strongly suggests that the occurrence of this inversion is correlated with higher hairpin stability. In contrast, we found no evidence of a correlation with longer palindromes. Our results are in agreement with the hypothesis that hairpin formation is a requisite for SI occurrence. However, alternative explanations cannot be discarded.

© The Willi Hennig Society 2008.
Electrocardiographic abnormalities in opiate addicts
Authors: Wallner Christina , Stöllberger Claudia , Hlavin Anton , Finsterer Josef , Hager Isabella , Hermann Peter
Published: November 2008

Aims  To determine in a cross‐sectional study the prevalence of electrocardiographic (ECG) abnormalities in opiate addicts who were therapy‐seeking and its association with demographic, clinical and drug‐specific parameters.

Methods  In consecutive therapy‐seeking opiate addicts, a 12‐lead ECG was registered within 24 hours after admission and evaluated according to a pre‐set protocol between October 2004 and August 2006. Additionally, demographic, clinical and drug‐specific parameters were recorded.

Results  Included were 511 opiate‐addicts, 25% female, with a mean age of 29 years (range 17–59 years). One or more ECG abnormalities were found in 314 patients (61%). In the 511 patients we found most commonly ST abnormalities (19%), QTc prolongation (13%), tall R‐ and/or S‐waves (11%) and missing R progression (10%). ECG abnormalities were more common in males than in females (64 versus 54%, P < 0.05), and in patients with positive than negative urine findings for cannabis (68 versus 57%, P < 0.05). Patients with ST abnormalities were more often males than females (21 versus 11%, P < 0.05), had a history of seizures less often (16 versus 27%, P < 0.05), had positive than negative urine findings for cannabis more often (26 versus 15%, P < 0.01) and had negative than positive urine findings for methadone more often (21 versus 11%, P < 0.05). QTc prolongation was more frequent in patients with high dosages of maintenance drugs than in patients with medium or low dosages (27 versus 12 versus 10%, P < 0.05) and in patients whose urine findings were positive than negative for methadone (23 versus 11%, P < 0.001) as well as for benzodiazepines (17 versus 9%, P < 0.05). Limitations of the data are that in most cases other risk factors for the cardiac abnormalities were not known.

Conclusion  ECG abnormalities are frequent in opiate addicts. The most frequent ECG abnormalities are ST abnormalities, QTc prolongation and tall R‐ and/or S‐waves. ST abnormalities are associated with cannabis, and QTc prolongation with methadone and benzodiazepines.
Dysregulation of stromal derived factor 1/CXCR4 axis in the megakaryocytic lineage in essential thrombocythemia
Authors: Salim Juan P. , Goette Nora P. , Lev Paola R. , Chazarreta Carlos D. , Heller Paula G. , Alvarez Clarisa , Molinas Felisa C. , Marta Rosana F.
Published: November 2008

This study investigated the involvement of chemokines including stromal derived factor 1 (SDF‐1), interleukin 8 (IL‐8), growth‐related oncogene alpha (GRO‐α) and their receptors, CXCR4, CXCR2 and CXCR1 in essential thrombocythemia (ET), a chronic myeloproliferative disease characterized by megakaryocytic hyperplasia and high platelet count. Fifty‐three ET patients were studied. Plasma levels of SDF‐1, IL‐8 and GRO‐α, evaluated by enzyme‐linked immunosorbent assay, and flow cytometric analysis of CXCR1 and CXCR2 on the platelet membrane, were found to be normal in ET patients. CXCR4 expression on platelet surface as well as platelet CXCR4 mRNA detected by real‐time reverse transcription polymerase chain reaction, were decreased. Platelet CXCR4 internalization rate was normal while SDF‐1‐induced platelet aggregation was delayed, decreased or absent. Immunohistochemical staining revealed that megakaryocytes were also affected. CXCR4 decrease was not observed either in peripheral white blood cells or in circulating CD34+ precursors. These results show that CXCR4 is decreased in the megakaryocytic lineage in ET, mainly due to a reduced CXCR4 production, and an abnormal platelet response to SDF‐1. This report is the first to describe platelet and megakaryocytic CXCR4 deficiency in a human disease and the presence of this abnormality in a megakaryocytic‐related illness highlights the important role of SDF‐1/CXCR4 axis in platelet development.
Annual variability in survival of sea‐ranched Baltic salmon, Salmo salar L: significance of smolt size and marine conditions
Authors: SALMINEN M. , KUIKKA S. , ERKAMO E.
Published: November 2008

Abstract Carlin tagging data for 1980–1991 were used to examine the influence of smolt size and feeding conditions on the post‐smolt survival of ranched River Neva salmon, (Salmo salar L.), in the the Gulf of Finland, which is the native feeding area of the stock, and in the Bothnian Sea, where the stock has been introduced. Because of better feeding conditions, the survival rates were higher and less variable in the Gulf of Finland than in the Bothnian Sea. In the Bothnian Sea, the annual variability in survival decreased and the mean value increased with increasing smolt size from the smallest (14–16 cm) to the largest (28–30 cm) size classes. The survival was positively correlated with growth rates, food resources and sea‐surface temperatures. This suggests that in the Bothnian Sea the annual variability in survival is mainly because variable marine conditions affect growth rates, and, thus, the vulnerability of the post‐smolts to size‐dependent predation. In the Gulf of Finland, the survival advantage of large initial size and rapid growth was counteracted by size‐selective post‐smolt mortality from fishing. The increase in the survival rate with increasing smolt size levelled off at 22 cm, and the correlations between survival, growth and the indices of feeding conditions were mostly insignificant. For large smolts, some negative correlations were recorded, suggesting that the relative significance of mortality from fishing may even exceed that of size‐dependent natural mortality. The implications of the results for management are discussed.
Fish resources of Dhofar khawrs (coastal lagoons) in the Sultanate of Oman
Authors: FOUDA M.M.
Published: November 2008

Abstract A fish resource monitoring programme was undertaken during 1992–1993 in nine Dhofar khawrs (coastal lagoons) of Oman. The khawrs contained a large number of fish comprising mostly milkfish, Chanos chanos (Forsskal), and mullet, Mugil cephalus L. A wide range of species were recorded (47) with Khawr Sawli supporting the highest number (26). Most fish use khawrs as nursery grounds and migrate to the sea for breeding. Mullets matured in winter, milkfish in early spring and the other species in spring‐summer except the sleeper, Ophiocara porocephala (Valenciennes), which breeds all year round. Three species of invertebrates with commercial value were collected: Indian white shrimp, Penaeus indicus H. Milne Edwards, Mud crab, Scylla serrata (Forskal), and swimming crab, Portunus pelagicus (L.). Khawr water temperature followed a seasonal cycle and surface temperatures were higher than the deeper waters. Heavy rains in early spring caused extensive flooding and opening of khawrs to the sea. This had little effect on water salinity in some khawrs (Rawri and Mughsayl), while others displayed marked elevation in salinity (Taqah, Sawli and Jnawf) or reduced salinity by 50% (Qurm al‐Kabir). Sedimentation and organic decomposition added during flooding produced drastic reduction in dissolved oxygen. Khawrs were again connected to the sea during monsoon (June–September) as water levels increased. Intrusion of sea water increased salinity and continued for several months in shallow khawrs (Jnawf); however, freshwater seepage reduced salinity in most khawrs. Massive fish mortality following heavy rains was the most significant seasonal occurrence. Extensive fish losses also occurred when water levels dropped after opening khawrs to the sea, and left many fish stranded in shallow areas. Other environmental perturbations existed in most khawrs (e.g. pollution and overgrazing). However, these khawrs have potential for small‐scale fisheries and different types of aquaculture. Management problems are identified and options for solutions suggested.
Angling pressure, yield and catch per effort of grayling, Thymallus thymallus (L)., and brown trout, Salmo trutta L., on the rivers Glomma and Rena, southeastern Norway
Authors: LINLØKKEN A.
Published: November 2008

Abstract Postal questionnaires, interviews and accurate reports from anglers were used to study angling activity, yield and catch per effort of grayling, Thymallus thymallus (L.), and brown trout, Salmo trutta L., on three stretches of the regulated river Glomma and two stretches of its tributary, the river Rena in southeastern Norway. Angling activity was expressed as hours angling per kilometre of river and varied from 364 (CL 245–598) to 1337 (CL 912–1991) h km‐1. Grayling and brown trout dominated the catches. The catches were estimated between 476 (CL 334–659) and 753 (CL 517–1155) grayling and brown trout per kilometre river stretch. The mean weights were estimated between 216 and 353 g for grayling, and 260 and 395 g for brown trout. The yield of grayling and brown trout was estimated between 8.7 (CL 6.1–12.4) and 46.4 (CL 34.9–62.3) kg ha‐1 yr‐1. The quotient grayling/brown trout in the catches varied between 0.41 and 5.1, and was found to be significantly negatively correlated with angling effort (r = ‐ 0.838, P <0.05). Catch per effort was estimated between 132 (CL 82–218) and 382 (CL 287–513) g h‐1, and was also negatively correlated to angling effort, according to: Catch per effort (g h‐1) = ‐ 0.210 × effort (h km‐1) + 405 (r = and 0.899, P <0.02).

Angling activity in earlier years was determined from number of permits sold where data were available. On stretches where angling activity was moderate, there was a tendency towards increase, whereas on stretches where activity had been high for several years, the activity seemed to have stagnated, indicating that a saturation had been reached.
Fishing grounds of bottom‐liners on the continental shelf of south‐east Brazil
Authors: PAIVA M.P. , ROCHA C.A.S. , GOMES A.M.G. , DE ANDRADE M. F.
Published: November 2008

Abstract The space and depth distribution of the bottom‐line fisheries on the continental shelf of south‐east Brazil were analysed, and an attempt was made to identify the areas and depths where fishing effort is concentrated to delimit the main fishing grounds. Four main fishing grounds were identified based on the effort and catches between 1975 and 1985. These were, in decreasing order of importance: north of Espírito Santo state, near the Abrolhos archipelago; adjacent to Rio de Janeiro state, under the influence of Cabo Frio upwelling; north of São Paulo state, encircling Alcatrazes archipelago; and the outer edge of the Rio de Janeiro and São Paulo state continental shelves, between the Guanabara and Sepetiba bays. The concentration of the fisheries, the greater catches and the best productivity indices were found in outer and deeper areas along the edge of the continental shelf. There was a concentration of fishing effort and higher catches in deeper grounds, from the north to the south of the regional fishing area. The bathymetric distribution of the fisheries showed that they intensified from 30 m depth to the outer edge of the continental shelf. The fishery productivity indices increased towards a depth of 50 m, but fell thereafter. Fishing activities were lowest during the winter season for the whole region, but intensified during the summer‐autumn or spring‐summer seasons.