bluuebunny/crossref_metadata_2025 huggingface dataset:
The economics of managing tree - crop competition in windbreak and alley systems
Authors: Sudmeyer R. , Flugge F.
Published: December 2005

Re-introducing trees and shrubs into agricultural landscapes as agroforestry systems establishes a tension between long-term objectives, such as increasing shelter, water use, nature conservation and harvesting tree products, and the short-term objective of maximising crop and pasture profitability. This paper describes the growth of crops, pastures and trees at the tree–crop interface in agroforestry systems and the economic returns from alley farming and windbreak systems using various tree–crop competition management strategies in the Esperance region of Western Australia.
Severing lateral tree roots (root-pruning), harvesting mallees and allowing them to coppice, or thinning trees for sawlog regimes increased the yield of crops and pastures in the competition zone. In some instances, these increases were significant: root-pruning increased the annual return from crops grown in the competition zone of Pinus radiata by up to $548/km of the tree line at 1 site. Conversely, root-pruning reduced tree growth by 14–43% across all sites. Therefore, where trees provide benefits, such as shelter from damaging winds, the benefits of reduced tree–crop competition may not offset the consequent reduction in rate of tree growth. For mallee–crop alley systems on agriculturally productive soils, mallee growth rates must be high enough to compensate for crop losses in the competition zone. On less agriculturally productive soils, block-planting mallees may be more profitable than alley systems or crops without competition (sole-crops).
This research has shown that competition management strategies can be used to manipulate the relative productivity of trees, crops and pasture at the tree–agriculture interface. The use of these strategies will depend on the relative economic value of tree and crop products and the value placed on other tree benefits, such as shelter and reduced groundwater recharge.
Molecular signatures in childhood acute leukemia and their correlations to expression patterns in normal hematopoietic subpopulations
Authors: Andersson Anna , Olofsson Tor , Lindgren David , Nilsson Björn , Ritz Cecilia , Edén Patrik , Lassen Carin , Råde Johan , Fontes Magnus , Mörse Helena , Heldrup Jesper , Behrendtz Mikael , Mitelman Felix , Höglund Mattias , Johansson Bertil , Fioretos Thoas
Published: December 2005

Global expression profiles of a consecutive series of 121 childhood acute leukemias (87 B lineage acute lymphoblastic leukemias, 11 T cell acute lymphoblastic leukemias, and 23 acute myeloid leukemias), six normal bone marrows, and 10 normal hematopoietic subpopulations of different lineages and maturations were ascertained by using 27K cDNA microarrays. Unsupervised analyses revealed segregation according to lineages and primary genetic changes, i.e.,
TCF3
(
E2A
)/
PBX1
,
IGH
@/
MYC
,
ETV6
(
TEL
)/
RUNX1
(
AML1
),
11q23
/
MLL
, and hyperdiploidy (>50 chromosomes). Supervised discriminatory analyses were used to identify differentially expressed genes correlating with lineage and primary genetic change. The gene-expression profiles of normal hematopoietic cells were also studied. By using principal component analyses (PCA), a differentiation axis was exposed, reflecting lineages and maturation stages of normal hematopoietic cells. By applying the three principal components obtained from PCA of the normal cells on the leukemic samples, similarities between malignant and normal cell lineages and maturations were investigated. Apart from showing that leukemias segregate according to lineage and genetic subtype, we provide an extensive study of the genes correlating with primary genetic changes. We also investigated the expression pattern of these genes in normal hematopoietic cells of different lineages and maturations, identifying genes preferentially expressed by the leukemic cells, suggesting an ectopic activation of a large number of genes, likely to reflect regulatory networks of pathogenetic importance that also may provide attractive targets for future directed therapies.
Quantum criticality in ferromagnetic single-electron transistors
Authors: Kirchner Stefan , Zhu Lijun , Si Qimiao , Natelson D.
Published: December 2005

Considerable evidence exists for the failure of the traditional theory of quantum critical points, pointing to the need to incorporate novel excitations. The destruction of Kondo entanglement and the concomitant critical Kondo effect may underlie these emergent excitations in heavy fermion metals (a prototype system for quantum criticality), but the effect remains poorly understood. Here, we show how ferromagnetic single-electron transistors can be used to study this effect. We theoretically demonstrate a gate-voltage-induced quantum phase transition. The critical Kondo effect is manifested in a fractional-power-law dependence of the conductance on temperature (
T
). The AC conductance and thermal noise spectrum have related power-law dependences on frequency (ω) and, in addition, show an ω/
T
scaling. Our results imply that the ferromagnetic nanostructure constitutes a realistic model system to elucidate magnetic quantum criticality that is central to the heavy fermions and other bulk materials with non-Fermi liquid behavior.
The mammalian central nervous synaptic cleft contains a high density of periodically organized complexes
Authors: Zuber Benoît , Nikonenko Irina , Klauser Paul , Muller Dominique , Dubochet Jacques
Published: December 2005

Cryo-electron microscopy of vitreous section makes it possible to observe cells and tissues at high resolution in a close-to-native state. The specimen remains hydrated; chemical fixation and staining are fully avoided. There is minimal molecular aggregation and the density observed in the image corresponds to the density in the object. Accordingly, organotypic hippocampal rat slices were vitrified under high pressure and controlled cryoprotection conditions, cryosectioned at a final thickness of ≈70 nm and observed below -170°C in a transmission electron microscope. The general aspect of the tissue compares with previous electron microscopy observations. The detailed analysis of the synapse reveals that the density of material in the synaptic cleft is high, even higher than in the cytoplasm, and that it is organized in 8.2-nm periodic transcleft complexes. Previously undescribed structures of presynaptic and postsynaptic elements are also described.
Hurewicz-like tests for Borel subsets of the plane
Authors: Lecomte Dominique
Published: December 2005

Let

ξ
≥
1

\xi \geq 1

be a countable ordinal. We study the Borel subsets of the plane that can be made

Π

ξ

0

\boldsymbol \Pi ^{0}_{\xi }

by refining the Polish topology on the real line. These sets are called potentially

Π

ξ

0

\boldsymbol \Pi ^{0}_{\xi }

. We give a Hurewicz-like test to recognize potentially

Π

ξ

0

\boldsymbol \Pi ^{0}_{\xi }

sets.
Polycomb mediates Myc autorepression and its transcriptional control of many loci in Drosophila
Authors: Goodliffe Julie M. , Wieschaus Eric , Cole Michael D.
Published: December 2005

Aberrant accumulation of the Myc oncoprotein propels proliferation and induces carcinogenesis. In normal cells, however, an abundance of Myc protein represses transcription at the c-myc locus. Cancer cells often lose this autorepression. We examined the control of myc in Drosophila and show here that the Drosophila ortholog, dmyc, also undergoes autorepression. We find that the developmental repressor Polycomb (Pc) is required for dmyc autorepression, and that this Pc-dMyc-mediated repression spreads across an 875-kb region encompassing the dmyc gene. To further investigate the relationship between Myc and Polycomb, we used microarrays to identify genes regulated by each, and identify a striking relationship between the two: A large set of dMyc activation targets is normally repressed by Pc, and 73% of dMyc repression targets require Pc for this repression. Chromatin immunoprecipitation confirmed that many dMyc-Pc-repressed loci have an epigenetic mark recognized by Pc. Our results suggest a novel relationship between Myc and Polycomb, wherein Myc enhances Polycomb repression in order to repress targets, and Myc suppresses Polycomb repression in order to activate targets.
The Fanconi Anemia/BRCA pathway: new faces in the crowd
Authors: Kennedy Richard D. , D'Andrea Alan D.
Published: December 2005

Over the past few years, study of the rare inherited chromosome instability disorder, Fanconi Anemia (FA), has uncovered a novel DNA damage response pathway. Through the cooperation of multiple proteins, this pathway regulates a complicated cellular response to DNA cross-linking agents and other genotoxic stresses. In this article we review recent data identifying new components of the FA pathway that implicate it in several aspects of the DNA damage response, including the direct processing of DNA, translesion synthesis, homologous recombination, and cell cycle regulation. We also discuss new findings that explain how the FA pathway is regulated through the processes of ubiquitination and deubiquitination. We then consider the clinical implications of our current understanding of the FA pathway, particularly in the development and treatment of malignancy in heterozygous carriers of FA mutations or in patients with sporadic cancers. We consider how recent studies of p53-mediated apoptosis and loss of p53 function in models of FA may help explain the clinical features of the disease and finally present a hypothesis to account for the specificity of the FA pathway in the response to DNA cross-links.
The Drosophila microRNA iab-4 causes a dominant homeotic transformation of halteres to wings
Authors: Ronshaugen Matthew , Biemar Frédéric , Piel Jessica , Levine Mike , Lai Eric C.
Published: December 2005

The Drosophila Bithorax Complex encodes three well-characterized homeodomain proteins that direct segment identity, as well as several noncoding RNAs of unknown function. Here, we analyze the iab-4 locus, which produces the microRNAs iab-4-5p and iab-4-3p. iab-4 is analogous to miR-196 in vertebrate Hox clusters. Previous studies demonstrate that miR-196 interacts with the Hoxb8 3′ untranslated region. Evidence is presented that miR-iab-4-5p directly inhibits Ubx activity in vivo. Ectopic expression of mir-iab-4-5p attenuates endogenous Ubx protein accumulation and induces a classical homeotic mutant phenotype: the transformation of halteres into wings. These findings provide the first evidence for a noncoding homeotic gene and raise the possibility that other such genes occur within the Bithorax complex. We also discuss the regulation of mir-iab-4 expression during development.
The core centromere and Sgo1 establish a 50-kb cohesin-protected domain around centromeres during meiosis I
Authors: Kiburz Brendan M. , Reynolds David B. , Megee Paul C. , Marston Adele L. , Lee Brian H. , Lee Tong Ihn , Levine Stuart S. , Young Richard A. , Amon Angelika
Published: December 2005

The stepwise loss of cohesins, the complexes that hold sister chromatids together, is required for faithful meiotic chromosome segregation. Cohesins are removed from chromosome arms during meiosis I but are maintained around centromeres until meiosis II. Here we show that Sgo1, a protein required for protecting centromeric cohesins from removal during meiosis I, localizes to cohesin-associated regions (CARs) at the centromere and the 50-kb region surrounding it. Establishment of this Sgo1-binding domain requires the 120-base-pair (bp) core centromere, the kinetochore component Bub1, and the meiosis-specific factor Spo13. Interestingly, cohesins and the kinetochore proteins Iml3 and Chl4 are necessary for Sgo1 to associate with pericentric regions but less so for Sgo1 to associate with the core centromeric regions. Finally, we show that the 50-kb Sgo1-binding domain is the chromosomal region where cohesins are protected from removal during meiosis I. Our results identify the portions of chromosomes where cohesins are protected from removal during meiosis I and show that kinetochore components and cohesins themselves are required to establish this cohesin protective domain.
Cell population heterogeneity during growth of Bacillus subtilis
Authors: Kearns Daniel B. , Losick Richard
Published: December 2005

We have discovered that cells of Bacillus subtilis at the mid-exponential phase of growth are a mixed population of two strikingly different cell types. One type is single swimming cells (or cell doublets) in which the transcription factor for motility, σD, is active (σD ON). The other type is long chains of sessile cells in which σD is inactive (σD OFF). The population is strongly biased toward σD-ON cells by the action of a novel regulatory protein called SwrA. SwrA stimulates the transcription of a large operon (the flagellum/chemotaxis operon), which includes the genes for σD and an activator of σD-directed gene expression, SwrB. Cell population heterogeneity could enable B. subtilis to exploit its present location through the production of sessile cells as well as to explore new environmental niches through the generation of nomadic cells.
Spliceosome disassembly catalyzed by Prp43 and its associated components Ntr1 and Ntr2
Authors: Tsai Rong-Tzong , Fu Ru-Huei , Yeh Fu-Lung , Tseng Chi-Kang , Lin Yu-Chieh , Huang Yu-hsin , Cheng Soo-Chen
Published: December 2005

Two novel yeast splicing factors required for spliceosome disassembly have been identified. Ntr1 and Ntr2 (NineTeen complex-Related proteins) were identified for their weak association with components of the Prp19-associated complex. Unlike other Prp19-associated components, these two proteins were primarily associated with the intron-containing spliceosome during the splicing reaction. Extracts depleted of Ntr1 or Ntr2 exhibited full splicing activity, but accumulated large amounts of lariat-intron in the spliceosome after splicing, indicating that the normal function of the Prp19-associated complex in spliceosome activation was not affected, but spliceosome disassembly was hindered. Immunoprecipitation analysis revealed that Ntr1 and Ntr2 formed a stable complex with DExD/H-box RNA helicase Prp43 in the splicing extract. Ntr1 interacted with Prp43 through the N-terminal G-patch domain, with Ntr2 through a middle region, and with itself through the carboxyl half of the protein. The affinity-purified Ntr1–Ntr2–Prp43 complex could catalyze disassembly of the spliceosome in an ATP-dependent manner, separating U2, U5, U6, NTC (NineTeen Complex), and lariat-intron. This is the first demonstration of physical disassembly of the spliceosome, catalyzed by a complex containing a DExD/H-box RNA helicase and two accessory factors, which might function in targeting the helicase to the correct substrate.
A human, ATP-independent, RISC assembly machine fueled by pre-miRNA
Authors: Maniataki Elisavet , Mourelatos Zissimos
Published: December 2005

RNA interference (RNAi) is mediated by RNA-induced silencing complexes (RISCs), which are guided by microRNAs (miRNAs) or short interfering RNAs (siRNAs) to cognate RNA targets. In humans, the catalytic engine of RISC is a ribonucleoprotein formed by the Argonaute2 (Ago2) protein and either miRNA (miRNP) or siRNA (siRNP). The Dicer nuclease produces mature miRNAs and siRNAs from pre-miRNAs and double-stranded RNA (dsRNA), respectively, and associates with Ago2. Here, we studied the assembly of human RISC by presenting pre-miRNA to immunopurified complexes that contain Ago2, Dicer, and TRBP. Mature miRNAs were produced in an ATP-independent manner and guided specific cleavage of cognate RNA targets in a pattern that is typical of RISC. This de novo formed RISC activity dissociated from Dicer. The asymmetry of the RISC loading process was fully recapitulated in this system, which, however, could not efficiently assemble RISC from siRNA duplexes. Our findings demonstrate that, in humans, a miRNA loading complex (miRLC) is formed by Ago2 and Dicer prior to their encounter with pre-miRNA. We suggest that the miRLC couples the processing of the pre-miRNA substrate to the unwinding of the product and that after loading of the mature miRNA to Ago2, the miRLC disassembles and the miRNP is released.
The RNA polymerase II subunit Rpb4p mediates decay of a specific class of mRNAs
Authors: Lotan Rona , Bar-On Vicky Goler , Harel-Sharvit Liat , Duek Lea , Melamed Daniel , Choder Mordechai
Published: December 2005

It is commonly appreciated that the mRNA level is determined by the balance between its synthetic and decay kinetics. Yet, little is known about coordination between these distinct processes. A major pathway of the eukaryotic mRNA decay initiates with shortening of the mRNA poly(A) tail (deadenylation), followed by removal of the mRNA 5′ cap structure and its subsequent exonucleolytic degradation. Here we report that a subunit of RNA polymerase II, Rpb4p, is required for the decay of a class of mRNAs whose products are involved in protein synthesis. Cells lackingRPB4are defective in the deadenylation and post-deadenylation steps of representatives of this class of mRNAs. Moreover, Rpb4p interacts with both the mRNP and with subunits of the mRNA decay complex Pat1/Lsm1–7 that enhances decapping. Consistently, a portion of Rpb4p is localized in P bodies, where mRNA decapping and degradation is executed, and mutations inRPB4increase the number of P bodies per cell. We propose that Rpb4p has a dual function in mRNA decay. It promotes or enhances the deadenylation process of specific mRNAs and recruits Pat1/Lsm1–7 to these mRNAs, thus stimulating their decapping and further decay. In this way, Rpb4p might link the activity of the basal transcription apparatus with that of the mRNA decay machinery.
Inactivation of S6 ribosomal protein gene in T lymphocytes activates a p53-dependent checkpoint response
Authors: Šulić Sanda , Panić Linda , Barkić Martina , Merćep Mladen , Uzelac Miljana , Volarević Siniša
Published: December 2005

Ribosome biogenesis has been associated with regulation of cell growth and cell division, but the molecular mechanisms that integrate the effect of ribosome biogenesis on these processes in mammalian cells remain unknown. To study the effect of impaired ribosome functions in vivo, we conditionally deleted one or two alleles of the 40S ribosomal protein S6 gene in T cells in the mouse. While complete deletion of S6 abrogated T-cell development, hemizygous expression did not have any effect on T-cell maturation in the thymus, but inhibited the accumulation of T cells in the spleen and lymph nodes, as a result of their decreased survival in the peripheral lymphoid organs. Additionally, TCR-mediated stimulation of S6-heterozygous T cells induced a normal increase in their size, but cell cycle progression was impaired. Genetic inactivation of p53 tumor suppressor rescued development of S6-homozygous null thymocytes and proliferative defect of S6-heterozygous T cells. These results demonstrate the existence of a p53-dependent checkpoint mechanism that senses changes in the fidelity of the translational machinery to prevent aberrant cell division or eliminate defective T cells in vivo. Failure to activate this checkpoint response could potentially lead to a development of pathological processes such as tumors and autoimmune diseases.
Replisome instability, fork collapse, and gross chromosomal rearrangements arise synergistically from Mec1 kinase and RecQ helicase mutations
Authors: Cobb Jennifer A. , Schleker Thomas , Rojas Vanesa , Bjergbaek Lotte , Tercero José Antonio , Gasser Susan M.
Published: December 2005

The yeast checkpoint kinases Mec1 and Rad53 are required for genomic stability in the presence of replicative stress. When replication forks stall, the stable maintenance of replisome components requires the ATR kinase Mec1/Ddc2 and the RecQ helicase Sgs1. It was unclear whether either Mec1 or Sgs1 action requires the checkpoint effector kinase, Rad53. By combining sgs1Δ with checkpoint-deficient alleles, we can now distinguish the role of Mec1 at stalled forks from that of Rad53. We show that the S-phase-specific mec1-100 allele, like the sgs1Δ mutation, partially destabilizes DNA polymerases at stalled forks, yet combining the mec1-100 and sgs1Δ mutations leads to complete disassociation of the replisome, loss of RPA, irreversible termination of nucleotide incorporation, and compromised recovery from hydroxyurea (HU) arrest. These events coincide with a dramatic increase in both spontaneous and HU-induced chromosomal rearrangements. Importantly, in sgs1Δ cells, RPA levels at stalled forks do not change, although Ddc2 recruitment is compromised, explaining the partial Sgs1 and Mec1 interdependence. Loss of Rad53 kinase, on the other hand, does not affect the levels of DNA polymerases at arrested forks, but leads to MCM protein dissociation. Finally, confirming its unique role during replicative stress, Mec1, and not Tel1, is shown to modify fork-associated histone H2A.
Mutation hot spots in mammalian mitochondrial DNA
Authors: Galtier Nicolas , Enard David , Radondy Yoan , Bazin Eric , Belkhir Khalid
Published: December 2005

Animal mitochondrial DNA is characterized by a remarkably high level of within-species homoplasy, that is, phylogenetic incongruence between sites of the molecule. Several investigators have invoked recombination to explain it, challenging the dogma of maternal, clonal mitochondrial inheritance in animals. Alternatively, a high level of homoplasy could be explained by the existence of mutation hot spots. By using an exhaustive mammalian data set, we test the hot spot hypothesis by comparing patterns of site-specific polymorphism and divergence in several groups of closely related species, including hominids. We detect significant co-occurrence of synonymous polymorphisms among closely related species in various mammalian groups, and a correlation between the site-specific levels of variability within humans (on one hand) and between Hominoidea species (on the other hand), indicating that mutation hot spots actually exist in mammalian mitochondrial coding regions. The whole data, however, cannot be explained by a simple mutation hot spots model. Rather, we show that the site-specific mutation rate quickly varies in time, so that the same sites are not hypermutable in distinct lineages. This study provides a plausible mutation model that potentially accounts for the peculiar distribution of mitochondrial sequence variation in mammals without the need for invoking recombination. It also gives hints about the proximal causes of mitochondrial site-specific hypermutability in humans.
Logistic regression protects against population structure in genetic association studies
Authors: Setakis Efrosini , Stirnadel Heide , Balding David J.
Published: December 2005

We conduct an extensive simulation study to compare the merits of several methods for using null (unlinked) markers to protect against false positives due to cryptic substructure in population-based genetic association studies. The more sophisticated “structured association” methods perform well but are computationally demanding and rely on estimating the correct number of subpopulations. The simple and fast “genomic control” approach can lose power in certain scenarios. We find that procedures based on logistic regression that are flexible, computationally fast, and easy to implement also provide good protection against the effects of cryptic substructure, even though they do not explicitly model the population structure.
Functional genomics of membrane transporters in human populations
Authors: Urban Thomas J. , Sebro Ronnie , Hurowitz Evan H. , Leabman Maya K. , Badagnani Ilaria , Lagpacan Leah L. , Risch Neil , Giacomini Kathleen M.
Published: December 2005

Although considerable progress has been made toward characterizing human DNA sequence variation, there remains a deficiency in information on human phenotypic variation at the single-gene level. We systematically analyzed the function of all protein-altering variants of eleven membrane transporters in heterologous expression systems. Coding-region variants were identified by screening DNA from a large sample (n = 247-276) of ethnically diverse subjects. In total, we functionally analyzed 88 protein-altering variants. Fourteen percent of the polymorphic variants (defined as variants with allele frequencies ≥1% in at least one major ethnic group) had no activity or significantly reduced function. Decreased function variants had significantly lower allele frequencies and were more likely to alter evolutionarily conserved amino acid residues. However, variants at evolutionarily conserved positions with approximately normal activity in cellular assays were also at significantly lower allele frequencies, suggesting that some variants with apparently normal activity in biochemical assays may influence occult functions or quantitative degrees of function that are important in human fitness but not measured in these assays. For example, eight (14%) of the 58 variants for which we had measured the transport of at least two substrates showed substrate-specific defects in transport. These variants and the reduced function variants provide plausible candidates for disease susceptibility or variation in clinical drug response.
Retrotransposon accumulation and satellite amplification mediated by segmental duplication facilitate centromere expansion in rice
Authors: Ma Jianxin , Jackson Scott A.
Published: December 2005

The abundance of repetitive DNA varies greatly across centromeres within an individual or between different organisms. To shed light on the molecular mechanisms of centromere repeat proliferation, we performed structural analysis of LTR-retrotransposons, mostly centromere retrotransposons of rice (CRRs), and phylogenetic analysis of CentO satellite repeats harbored in the core region of the rice chromosome 4 centromere (CEN4). The data obtained demonstrate that the CRRs in the centromeric region we investigated have been enriched more significantly by recent rounds of segmental duplication than by original integration of active elements, suggesting that segmental duplication is an important process for CRR accumulation in the centromeric region. Our results also indicate that segmental duplication of large arrays of satellite repeats is primarily responsible for the amplification of satellite repeats, contributing to rapid reshuffling of CentO satellites. Intercentromere satellite homogenization was revealed by genome-wide comparison of CentO satellite monomers. However, a 10-bp duplication present in nearly half of the CEN4 monomers was found to be completely absent in rice centromere 8 (CEN8), suggesting that CEN4 and CEN8 may represent two different stages in the evolution of rice centromeres. These observations, obtained from the only complex eukaryotic centromeres to have been completely sequenced thus far, depict the evolutionary dynamics of rice centromeres with respect to the nature, timing, and process of centromeric repeat amplification.
Fungivore host‐use groups from cluster analysis: patterns of utilisation of fungal fruiting bodies by ciid beetles
Authors: Orledge Glenda M. , Reynolds Stuart E.
Published: December 2005

Abstract.  1. Ciid beetles typically live and breed in the fruiting bodies of lignicolous basidiomycete fungi. This study was undertaken to address the lack of an objective examination of patterns of host use by ciids.

2. Cluster analysis of ciid host‐use datasets from Britain, Germany, North America, and Japan, and subsequent cross‐dataset comparisons, demonstrated the existence of ciid host‐use patterns of wide geographical occurrence. These patterns were formalised as ciid host‐use groups.

3. Six Holarctic ciid host‐use groups, and two host‐use subgroups, were identified, and are described. Each host‐use group comprises an assemblage of fungal genera and the breeding ciids that it supports. Each taxon belongs to only a single host‐use group, but may be associated with several members of that group. There is a strong tendency for closely related taxa to belong to the same host‐use group.

4. It is suggested that ciid host‐use groups are defined ultimately by host chemistry, with the ciids that belong to a particular group recognising, and responding positively to, emitted volatiles characterising the fungi belonging to that group.

5. The idea of the host‐use group bears comparison with the concepts of niche and guild, but is not equivalent to either.

6. Ciid host‐use groups have a valuable role to play in underpinning future studies of ciid ecology, also the systematics of both ciids and their fungal hosts.
Effects of nutrients and parasitism on the density of a salt marsh planthopper suppressed by within‐trophic‐level interactions
Authors: Moon Daniel C. , Stiling Peter
Published: December 2005

Abstract.  1. Competition, food quality, and pressure from natural enemies have all been established as important determinants of phytophagous insect densities. Examining how these forces interact, however, is important for furthering our understanding of insect population and community ecology.

2. In this paper the results of a factorial field experiment are reported in which the effects of within‐trophic‐level interactions on the top‐down and bottom‐up forces influencing the density of a salt marsh planthopper were examined.

3. Plant quality was increased by adding nitrogen fertiliser, and parasitism was decreased through the use of yellow sticky traps that removed hymenopteran parasitoids. These treatments were applied to plots with either low or high densities of a lepidopteran stem borer, which has been shown to negatively affect the planthopper.

4. Addition of nitrogen increased planthopper density significantly, but only on plots with low stem borer densities. Yellow sticky traps significantly reduced parasitism of planthopper eggs, but this resulted in increased planthopper density only on plots with low stem borer density. Thus, where stem borer densities were high, the effects of fertiliser and reduced parasitism on planthopper densities were suppressed.

5. The results of this study show that negative interactions between herbivores can affect vertical trophic linkages, and can greatly modify the strengths of top‐down or bottom‐up effects on herbivore density.
Ants and plant size shape the structure of the arthropod community of Hirtella myrmecophila, an Amazonian ant‐plant
Authors: Izzo Thiago Junqueira , Vasconcelos Heraldo L.
Published: December 2005

Abstract.  1. To investigate the influence of plant size and the presence of resident ants on the arthropod community associated with the ant‐plant Hirtella myrmecophila, ants (Allomerus octoarticulatus) were experimentally removed from plants of various sizes, with a second group of similar‐sized plants remaining as controls. The abundance and diversity of arthropods on these plants were determined at 45‐day intervals for 7 months. Collected arthropods were assigned into one of three predetermined groups: herbivores, spiders (mostly web‐building spiders), or ‘tourists’ (mostly non‐resident ants, hemipterans, dipterans, or scarabeid beetles).

2. Ant removal had a positive influence on the abundance and diversity of herbivores, but no measurable effects on the abundance and diversity of ‘tourists’, while the effect on spider abundance was significant only when data from Dipoena sp. nov. were removed from the analysis. While A. octoarticulatus had a negative effect on most spiders, it favoured Dipoena sp. nov., which was found to be a specialist predator of A. octoarticulatus.

3. Plant size positively affected the abundance and diversity of ‘tourists’ in plants with and without ants, but for herbivores and spiders this effect was dependent on ant treatment. In ant‐maintained plants the per‐plant abundance of herbivores and spiders was independent of plant size, whereas in ant‐removed plants it was not.

4. These results suggest that A. octoarticulatus affects all arthropods found on its host plant, except those presenting an occasional and temporary association with the plant, and that the magnitude of ant effects on the susceptible guilds increases as plant size increases.
Crop domestication disrupts a native tritrophic interaction associated with the sunflower, Helianthus annuus (Asterales: Asteraceae)
Authors: Chen Yolanda H. , Welter Stephen C.
Published: December 2005

Abstract.  1. Crop domestication has been a largely overlooked factor that may explain why insect herbivores tend to be more abundant and less attacked in agricultural habitats than in native habitats. This study explores how domestication of the sunflower, Helianthus annuus L., affects the sunflower moth, Homoeosoma electellum (Lepidoptera: Pyralidae), and its parasitoids.

2. Common garden experiments were used to assess the effect of domestication on larval abundance in an agricultural and a native habitat. The effect of domestication on parasitism was determined using two studies: one study that manipulated nitrogen according to levels found in agricultural and native habitats, and a second common garden study in the native habitat.

3. At peak infestation in the agricultural common garden, larval abundance was 10 times higher on agricultural plants than on wild plants. In contrast, larval abundance did not differ between plant genotypes in the native habitat.

4. Larvae were four times more likely to be parasitised on wild sunflowers than on agricultural sunflowers, and three times more likely to be parasitised on low nitrogen plants than on high nitrogen plants. Parasitism did not differ between agricultural and wild plants in the native habitat, where flowers were more similar in size.

5. Sunflower domestication has increased larval abundance, accelerated larval development, and lowered parasitism. The magnitude of the effect appears to depend upon nutrient availability. Thus, domestication can disrupt tritrophic interactions, and may help explain why some insect pests are more abundant and less attacked in agro‐ecosystems.
Density‐dependent effects on the reproductive fitness of the New Zealand beech scale insect (Ultracoelostoma assimile) across multiple spatial scales
Authors: Wardhaugh Carl W. , Didham Raphael K.
Published: December 2005

Abstract.  1. Intraspecific competition can be an important factor influencing the individual fitness of organisms. This study reports density‐dependent effects on the fecundity of the beech scale insect (Ultracoelostoma assimile, Hemiptera: Margarodidae) on naturally occurring, canopy‐dominant red beech (Nothofagus fusca, Fagaceae) trees in New Zealand. For the first time an increasing intensity of intraspecific competition at increasing spatial scales within individual host trees is demonstrated.

2. Beech scale insect ‘tests’ containing adult female scale insects and eggs were collected from the trunks of 10 red beech trees [17.7–48.5 cm in diameter at breast height (1.4 m), d.b.h.] with varying densities of scale insect infestation. The relationship between individual female fecundity and scale insect density at three spatial scales: local (within 5 cm), lower trunk (below 2 m above ground level), and whole tree, was tested.

3. Beech scale insect fecundity was density dependent, with total female egg load decreasing with increasing scale insect density. The strength of the density‐dependent effect increased with increasing spatial scale, suggesting that scale insects are creating a tree‐wide drain on the quality of phloem sap, rather than depleting nutrients from localised, high‐density areas within trees. These results indicate that at high densities, the New Zealand beech scale insect can have a negative effect on the nutritional quality of the phloem of red beech, thus negatively affecting conspecifics elsewhere on individual host trees. The increasing intensity of the effect with increasing spatial scale within individual trees emphasises the importance of measuring density‐dependent effects at the appropriate spatial scale.
The effect of a seasonal time constraint on development time, body size, condition, and morph determination in the horned beetle Allomyrina dichotoma L. (Coleoptera: Scarabaeidae)
Authors: Plaistow S. J. , Tsuchida K. , Tsubaki Y. , Setsuda K.
Published: December 2005

Abstract.  1. In horned beetles selection favours males that adjust their investment in horn development in relation to cues that predict adult body size. Here it is shown that in the Japanese horned beetle, Allomyrina dichotoma. There is a significant discontinuity in the horn length body size allometry. This can be described as a linear relationship that is shifted towards an increased horn length to body length ratio in males with horns longer than 16 mm.

2. Larval nutrition explains morph determination in A. dichotoma. However, unlike other species, variation in larval nutrition was the result of a seasonal time constraint that limits the time available for feeding prior to the onset of winter diapause.

3. Even when eggs were reared with an ad libitum food supply, minor morphs were still observed. Individuals that were oviposited later in the season had less time to feed, shorter development times, eclosed as smaller individuals and, in the case of males, were more likely to be hornless. Major morphs, minor morphs, and females all reduced their body size in response to seasonal time constraints in the same way. However, males that were laid later in the season had faster development times than females laid at the same time, but showed no reduction in their size relative to females, suggesting seasonal time constraints increase growth rates in males but not in females.

4. No evidence was found that seasonal time constraints resulted in a reduction of size‐corrected fat reserves at eclosion, or that minor morphs gained any developmental advantage by reducing investment in horn length.
Influence of the aphid pathogen Pandora neoaphidis on the foraging behaviour of the aphid parasitoid Aphidius ervi
Authors: Baverstock J. , Alderson P. G. , Pell J. K.
Published: December 2005

Abstract.  1. The parasitoid Aphidius ervi and the entomopathogenic fungus Pandora neoaphidis both require successful invasion of an aphid host to complete their life cycle. A shorter developmental period allows P. neoaphidis to out‐compete A. ervi. Aphidius ervi may reduce this fitness cost by avoiding aphid colonies containing P. neoaphidis. Here the response of A. ervi towards P. neoaphidis was assessed using sequential experiments designed to replicate different stages of parasitoid foraging behaviour.

2. Entry rate experiments showed that A. ervi entered aphid colonies containing P. neoaphidis‐sporulating cadavers and that there was no significant difference in the attraction of A. ervi to aphid‐damaged Vicia faba plants containing either healthy Acyrthosiphon pisum or P. neoaphidis‐sporulating cadavers.

3. Observational behavioural experiments indicated that the presence of P. neoaphidis did not affect the search time or total foraging time of A. ervi on V. faba plants infested with either healthy A. pisum or P. neoaphidis‐sporulating cadavers.

4. In Petri dish bioassays using aphids infected with P. neoaphidis over a period of 120 h, A. ervi showed no difference in attack rate against uninfected aphids or living aphids infected with P. neoaphidis for 1, 24, 48, 72, or 96 h. However, sporulating cadavers (120 h infection) were not attacked.

5. Aphidius ervi appears only able to detect the presence of P. neoaphidis once the host is dead and sporulation has started. The fitness of A. ervi may therefore be severely reduced when foraging in P. neoaphidis‐infected aphid colonies.
Regional dynamics of a patchily distributed herbivore along an altitudinal gradient
Authors: González‐Megías Adela , Gómez José M. , Sánchez‐Piñero Francisco
Published: December 2005

Abstract. 1. Metapopulation dynamics should be more important at the borders of species distributions due to two main factors: (1) populations are less abundant and fluctuate more at the borders than in the centre of their distributions, and (2) resources in the range margins of species distributions are often more scarce and fragmented.

2. Most metapopulation studies have been performed in a fraction of the entire distribution of species. The main goal here is to study the population dynamics of a narrowly distributed species including both the borders and the centre of the distribution, and to test the predictions described above.

3. The density and extinction events in a patchily distributed species,Timarcha lugens, was quantified for 5 years along an altitudinal gradient including the upper and lower limits of the species distribution. The dispersal ability ofTimarchawas also studied using a mark–release–recapture study.

4. Extinction events and empty patches were only found at the borders ofTimarchadistribution. The fluctuation in beetle density was greater in patches suffering extinction events. Resource abundance was negatively related to beetle density and positively related to extinction events. In addition, the dispersal rate among patches was very low and beetles moved distances of no further than 25 m.

5. Population density governs the extinction events in this system, and its fluctuation was more evident near the border of the distribution. Both factors together with the relative population stability in patches at medium and high altitudes, and the low dispersal rate of the individuals support the idea of a source–sink metapopulation structure inT. lugens.
Are ball‐rolling (Scarabaeini, Gymnopleurini, Sisyphini) and tunnelling scarabaeine dung beetles equally choosy about the size of ingested dung particles?
Authors: Holter P. , Scholtz C. H.
Published: December 2005

Abstract.  1. The maximum size of ingested particles was determined in 11 species of ball‐rolling, adult dung beetle (Scarabaeidae: Scarabaeinae) by mixing small latex or glass balls of known diameter into their food. The tribes Scarabaeini, Gymnopleurini, and Sisyphini (four, four, and three species respectively) were represented, with mean body sizes ranging from 0.33 to 4.0 g fresh weight.

2. Only particles with maximum diameters of 4–85 µm were ingested. Hence rollers, like other known beetles feeding on fresh dung, filter out larger, indigestible plant fragments and confine ingestion to small particles of higher nutritional value.

3. The maximum diameter of ingested particles increased significantly with body weight, whereas taxon (tribe) had no additional effect. Because big rollers accept larger particles than do tunnellers (which make dung stores for feeding and breeding in the soil immediately below the pat) of similar weight, the slope of the diameter‐against‐weight regression for rollers was significantly higher than that found earlier for tunnellers.

4. An explanation could be that a typical food ball made by a roller is considerably smaller than the amount of dung available to a feeding tunneller of the same size. If the roller were as choosy about particle size as the tunneller, it might not get enough food. This applies to large rollers in particular because their food balls contain a higher proportion of coarse fibres than those made by small species.
Life‐threatening pulmonary hypertension and right ventricular failure complicating calcium and phosphate replacement in the intensive care unit
Authors: Felton T. W. , McCormick B. A. , Finfer S. R. , Fisher M. M.
Published: December 2005

A 43‐year‐old man developed septic shock and acute lung injury after surgery to drain an ischiorectal abscess. In the intensive care unit he initially improved but developed severe hypoxaemia, right ventricular failure and pulmonary hypertension 90 min after receiving intravenous calcium gluconate and potassium phosphate, best explained by the formation of a calcium‐phosphate precipitant that resulted in aggregate anaphylaxis. His rapid deterioration and lack of response to conventional therapies necessitated support with extracorporeal membrane oxygenation that was life saving. This adverse event has altered local practice regarding calcium and phosphate replacement and has implications for all intensive care units.
The pharmacoeconomics of peri‐operative beta‐blocker therapy
Authors: Biccard B. M. , Sear J. W. , Foëx P.
Published: December 2005

It is widely recommended that beta‐blockade be used peri‐operatively as it may reduce the incidence of postoperative cardiovascular complications including death. However, there are few data concerning the cost‐effectiveness of such strategies. We have analysed the pharmacoeconomics of acute beta‐blockade using data from eight prospective peri‐operative studies in which patients underwent elective non‐cardiac surgery, and in which the incidence of adverse side‐effects of treatment, as well as clinical outcomes, have been reported. The costs of treatment were based on the NHS reference costs for 2004. From these data, the number‐needed‐to‐treat (NNT) to prevent a major cardiovascular complication (including cardiovascular death) in high‐risk patients was 18.5. This is comparable to the NNT for peri‐operative statin therapy. The incremental cost of peri‐operative beta‐blockade (costs of drug acquisition and of treating associated adverse drug events) was £67.80 per patient. This results in a total cost of £1254.30 per peri‐operative cardiovascular complication prevented. However, there is evidence that in patients at lower cardiovascular risk, beta‐blockers may be potentially harmful, since their adverse effects (hypotension, bradycardia) may outweigh their potential cardioprotective effects.
Anchoring of the internal jugular vein with a pilot needle to facilitate its puncture with a wide bore needle: a randomised, prospective, clinical study
Authors: Tripathi M. , Pandey M.
Published: December 2005

In this prospective, randomised study, consented adult patients of both genders were divided into two groups. In group 1 (n = 79) patients, during internal jugular vein cannulation, the pilot needle was removed before the wide bore needle (18G) puncture. In group 2 (n = 78) patients, the internal jugular vein was anchored by leaving the pilot needle in place during wide bore needle puncture. In demographically similar groups, the first attempt success rate improved from 64% in group 1 to 81% in group 2 (p < 0.05). Internal jugular vein puncture was more frequently detected at the entry of the needle with anchoring (group 2: 78%) than without (group 1: 53%); p < 0.05. Ultrasonography of a further 30 internal jugular vein punctures in each group demonstrated that the anchoring manoeuvre (group 2b) significantly (p < 0.05) prevented an indenting effect of the puncture needle, with a higher vertical to horizontal diameter ratio of the internal jugular vein when there was anchoring (0.97; SD 0.004) than without pilot needle anchoring (0.65; SD 0.008). In conclusion, when using surface landmarks, anchoring of the internal jugular vein with the pilot needle facilitated its puncture.
Levosimendan: a promising treatment for myocardial stunning?
Authors: Ellger B. M. , Zahn P. K. , Van Aken H. K. , Schmidt C. , Brussel T.
Published: December 2005

We report a case of a 55‐year‐old male undergoing major orofacial cancer surgery. A stent to the left anterior descending artery had been implanted for ischaemic heart disease 3 years previously. Twenty‐four hours after uneventful anaesthesia and surgery, the patient developed myocardial infarction and cardiogenic shock. Immediate percutaneous transluminal coronary angioplasty, intra aortic balloon counterpulsation, and catecholamine therapy failed to stabilise haemodynamics. In light of successful reperfusion therapy and an only moderate elevation of troponin I, myocardial stunning rather than myonecrosis was considered to be the major contributor to life‐threatening left ventricular failure. Therefore, the calcium‐sensitising drug levosimendan, which exerts positive inotropic activity without increasing myocardial oxygen demand, was administered as a rescue medication. Within 24 h, levosimendan resulted in decreased filling pressures, reduced left ventricular end‐diastolic volume, and augmented systemic pressures. Seven days following surgery, the patient was discharged from the intensive care unit in good clinical condition.