bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of the elm leaf beetle to host plants induced by oviposition and feeding: the infestation rate matters
Authors: Meiners T. , Hacker N.K. , Anderson P. , Hilker M.
Published: April 2005

We investigated by olfactometry and feeding‐ and oviposition‐choice‐tests how the highly specialised elm leaf beetle, Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), responds to conspecifically induced defences in the field elm Ulmus minor Miller (Ulmaceae). While egg deposition of the beetle induced elms to release volatiles attractive to the egg parasitoid Oomyzus gallerucae Fonscolombe (Hymenoptera: Eulophidae), feeding alone did not. In the present study, females of the elm leaf beetle showed preferences for the odours of twigs induced by low egg deposition and feeding over odours from uninfested twigs. In contrast, heavy infestation rendered elm odours less attractive to the beetles. Feeding and oviposition bioassays revealed an oviposition preference for leaves from uninfested twigs when compared to locally infested leaves. However, beetles preferred to feed upon systemically induced leaves compared to uninfested ones. The different preferences of the elm leaf beetle during host plant approach might be explained by a strategy that accounts for both gaining access to high quality nutrition and avoiding competition or parasitism.
Clinical Applications of Functional Magnetic Resonance Imaging
Authors: Voets N. L. , Matthews P. M.
Published: April 2005

Blood oxygenation level‐dependent (BOLD) functional magnetic resonance imaging (fMRI) provides a new tool for neuroradiology. The BOLD fMRI allows functional changes to be distinguished, even in the absence of structural changes in the brain. Up until now, routine clinical applications largely have been limited to localizing eloquent brain regions in pre‐surgical planning. However, in exploratory applications, the method has allowed new insights into mechanisms of brain plasticity, helping clinicians better appreciate its importance in recovery after brain injury. Several new areas of application may be anticipated based on current research work, including for pre‐symptomatic disease detection, testing drug dose–activity relationships, and the diagnosis and characterization of somatization disorders. A major direction of methodological research is towards integration of fMRI with other techniques, particularly electrophysiological methods. The emphasis that these new approaches to imaging will place on understanding functional changes associated with disease challenges current neuroradiological training and service delivery models. They emphasize the need to develop closer relationship between neuroradiology and the traditional clinical neurosciences.
THE STATE OF THE HOME EQUITY SECURITIES MARKET (AND HOW TO IMPROVE IT): REPORT FROM A RECENT CONFERENCE
Authors: Youngblood Michael D.
Published: April 2005

In 1998, a year which saw the origination of a record volume of single‐family mortgage loans, at least 12 of the top 20 home equity lenders experienced severe problems related to their business models, accounting practices, and access to the debt and equity markets. In march of 1999, Banc of America Securities (BAS) sponsored a conference to explore the causes of and possible solutions to these problems.

This article begins by tracing the industry's problems to lenders' inability to sell the subordinated and residual classes of home equity securities, and goes on to argue that the key to the regular distribution of these securities lies in enhancing the quality and depth of information that lenders provide investors about the underlying loans. The article discusses four proposals for improving lenders' disclosure—proposals that are designed to increase institutional investors' demand for home equity securities by helping them to assess the prepayment and credit risk associated with the securities.

Following the author's summary of the BAS proposals, the article concludes with selected comments on the future of the home equity securities markets by two panels of experts representing bond insurers and rating agencies.
Damage Rate is a Predictor of Fatigue Life and Creep Strain Rate in Tensile Fatigue of Human Cortical Bone Samples
Authors: Cotton John R. , Winwood Keith , Zioupos Peter , Taylor Mark
Published: April 2005

We present results on the growth of damage in 29 fatigue tests of human femoral cortical bone from four individuals, aged 53–79. In these tests we examine the interdependency of stress, cycles to failure, rate of creep strain, and rate of modulus loss. The behavior of creep rates has been reported recently for the same donors as an effect of stress and cycles (Cotton, J. R., Zioupos, P., Winwood, K., and Taylor, M., 2003, “Analysis of Creep Strain During Tensile Fatigue of Cortical Bone,” J. Biomech. 36, pp. 943–949). In the present paper we first examine how the evolution of damage (drop in modulus per cycle) is associated with the stress level or the “normalized stress” level (stress divided by specimen modulus), and results show the rate of modulus loss fits better as a function of normalized stress. However, we find here that even better correlations can be established between either the cycles to failure or creep rates versus rates of damage than any of these three measures versus normalized stress. The data indicate that damage rates can be excellent predictors of fatigue life and creep strain rates in tensile fatigue of human cortical bone for use in practical problems and computer simulations.
Numerical Simulation for Heat Transfer in Prostate Cancer Cryosurgery
Authors: Zhang Jiayao , Sandison George A. , Murthy Jayathi Y. , Xu Lisa X.
Published: April 2005

A comprehensive computational framework to simulate heat transfer during the freezing process in prostate cancer cryosurgery is presented. Tissues are treated as nonideal materials wherein phase transition occurs over a temperature range, thermophysical properties are temperature dependent and heating due to blood flow and metabolism are included. Boundary conditions were determined at the surfaces of the commercially available cryoprobes and urethral warmer by experimental study of temperature combined with a mathematical optimization process. For simulations, a suitable computational geometry was designed based on MRI imaging data of a real prostate. An enthalpy formulation-based numerical solution was performed for a prescribed surgical protocol to mimic a clinical freezing process. This computational framework allows for the individual planning of cryosurgical procedures and objective assessment of the effectiveness of prostate cryosurgery.
A Simplified Procedure to Determine the Optimal Rate of Freezing Biological Systems
Authors: Thirumala Sreedhar , Devireddy Ram V.
Published: April 2005

The effect of several cell-level parameters on the predicted optimal cooling rate Bopt of an arbitrary biological system has been studied using a well-defined water transport model. An extensive investigation of the water transport model revealed three key cell level parameters: reference permeability of the membrane to water Lpg, apparent activation energy ELp, and the ratio of the available surface area for water transport to the initial volume of intracellular water (SA∕WV). We defined Bopt as the “highest” cooling rate at which a predefined percent of the initial water volume is trapped inside the cell (values ranging from 5% to 80%) at a predefined end temperature (values ranging from −5°C to −40°C). Irrespective of the choice of the percent of initial water volume trapped and the end temperature, an exact and linear relationship exists between Lpg,SA∕WV, and Bopt. However, a nonlinear and inverse relationship is found between ELp and Bopt. Remarkably, for a variety of biological systems a comparison of the published experimentally determined values of Bopt agreed quite closely with numerically predicted Bopt values when the model assumed 5% of initial water is trapped inside the cell at a temperature of −15°C. This close agreement between the experimental and model predicted optimal cooling rates is used to develop a generic optimal cooling rate chart and a generic optimal cooling rate equation that greatly simplifies the prediction of the optimal rate of freezing of biological systems.
Trichomonas vaginalis
Polyamine Metabolism Is Linked to Host Cell Adherence and Cytotoxicity
Authors: Garcia Ana F. , Benchimol M. , Alderete J. F.
Published: April 2005

Trichomonas vaginalis
secretes putrescine that is readily detected in vaginal secretions. We wanted to examine the effect of decreased putrescine synthesis by inhibition of ornithine decarboxylase (ODC) on
T. vaginalis
. One reason is because inhibition of
Tritrichomonas foetus
ODC results in growth arrest, destruction of hydrogenosomes, and decreased amounts of hydrogenosomal enzymes. Treatment of
T. vaginalis
T016 with ≥20 mM 1,4-diamino-2-butanone (DAB) to inhibit ODC resulted in growth arrest, which was reversed by addition of exogenous putrescine. No similar reversal of growth arrest was achieved with the polyamines spermine or spermidine or with iron. Electron microscopic examination of control versus DAB-treated trichomonads did not reveal any adverse effects on the number and integrity of hydrogenosomes. Further, the adhesins AP65, AP51, and AP33 mediating binding to immortalized vaginal epithelial cells (VECs) share identity to enzymes of the hydrogenosome organelle, and there was no difference in amounts of adhesins between control versus DAB-treated
T. vaginalis
parasites. Likewise, similar patterns and extent of fluorescence were evident for the prominent AP65 adhesin. Surprisingly, DAB treatment increased by 4- to 20-fold above untreated trichomonads handled identically the level of adherence mediated by adhesins. Interestingly, the enhanced attachment to VECs was reversed by exogenous putrescine added to DAB-treated trichomonads. Equally noteworthy was that DAB-treated
T. vaginalis
with enhanced adherence did not possess the previously reported ability to kill host cells in a contact-dependent fashion mediated by cysteine proteinases, and total cysteine proteinase activity patterns were identical between control and DAB-treated trichomonads. Overall, these data suggest that polyamine metabolism and secreted putrescine are linked to host cell adherence and cytotoxicity.
Microarray and Proteomics Analyses of Human Intestinal Epithelial Cells Treated with theAeromonas hydrophilaCytotoxic Enterotoxin
Authors: Galindo C. L. , Fadl A. A. , Sha Jian , Pillai L. , Gutierrez C. , Chopra A. K.
Published: April 2005

We performed microarray analyses on RNA from human intestinal epithelial (HT-29) cells treated with the cytotoxic enterotoxin (Act) ofAeromonas hydrophilato examine global cellular transcriptional responses. Based on three independent experiments, Act upregulated the expression of 34 genes involved in cell growth, adhesion, signaling, immune responses (including interleukin-8 [IL-8] production), and apoptosis. We verified the upregulation of 14 genes by real-time reverse transcriptase-PCR and confirmed Act-induced production of IL-8 by enzyme-linked immunosorbent assay on supernatants from nonpolarized and polarized HT-29 cells. Maximal production of IL-8 in response to Act required the presence of intracellular calcium, since chelation of calcium with BAPTA-AM significantly reduced Act-induced IL-8 production in HT-29 cells. We also examined activation of mitogen-activated protein kinases and, as demonstrated by Western blot analysis of apical side-treated polarized HT-29 cells, Act induced phosphorylation of p38, c-Jun NH2-terminal kinase, and extracellular signal-regulated kinase 1/2. In addition, KinetWorks proteomics screening of whole-cell lysates revealed Act-induced phosphorylation of cyclic AMP-response element binding protein (CREB), c-Jun, adducin, protein kinase C, and signal transducer and activator of transcription 3 (STAT3) and decreased phosphorylation of protein kinase Bα, v-raf-1 murine leukemia viral oncogene homolog 1 (i.e., Raf1), and STAT1. We verified activation of CREB and activator protein 1 in polarized cells by gel shift assay. This is the first description of human intestinal epithelial cell transcriptional alterations, phosphorylation or activation of signaling molecules, cytokine production, and calcium mobilization in response to this toxin.
Differential Binding ofEscherichia coliEnterotoxins LT-IIa and LT-IIb and of Cholera Toxin Elicits Differences in Apoptosis, Proliferation, and Activation of Lymphoid Cells
Authors: Arce Sergio , Nawar Hesham F. , Russell Michael W. , Connell Terry D.
Published: April 2005

Cholera toxin (CT), LT-IIa, and LT-IIb are potent adjuvants which induce distinct T-helper (Th)-cell cytokine profiles and immunoglobulin G (IgG) subclass and IgA antibody responses. To determine if the distinct immune regulatory effects observed for LT-IIa, LT-IIb, and CT are elicited by binding of the enterotoxins to their cognate ganglioside receptors, the lineages of lymphoid cells that interact with the three enterotoxins and their effects on various lymphocyte responses in vitro were evaluated. Binding patterns of LT-IIa, LT-IIb, and CT to several lymphoid cell populations were distinctive for each enterotoxin. LT-IIa and CT, but not LT-IIb, induced apoptosis in CD8+T cells. LT-IIa(T34I), a mutant with no detectable binding to gangliosides, did not induce apoptosis. Blockade of GM1on the surface of CD8+T cells by LT-IIa(T14I), a mutant that binds only to GM1but does not induce apoptosis, did not inhibit induction of apoptosis by LT-IIa. Mitogen-induced proliferation of CD8+T cells was abrogated by treatment with CT, while resting CD8+T cells which were sensitive to LT-IIa-induced apoptosis became more resistant to apoptosis after mitogen activation. Exposure to CT, but not to LT-IIa or LT-IIb, inhibited mitogen-driven CD4+T-cell proliferation and expression of CD25 and CD69. In mitogen-stimulated B cells, CT, but not LT-IIa or LT-IIb, enhanced expression levels of CD86, while only CT induced B-cell differentiation into plasma cells. Thus, LT-IIa, LT-IIb, and CT exhibit distinguishable immunomodulatory properties which are likely dependent upon their capacities to recognize different ganglioside receptors on lymphocytes.
Identification of an Immunomodulating Agent fromMycobacterium leprae
Authors: Maeda Yumi , Mukai Tetsu , Spencer John , Makino Masahiko
Published: April 2005

A search for an immunomodulating agent from mycobacteria was carried out usingMycobacterium leprae. The antigenicity of each fraction of the bacterial membrane, which contains the most antigenic components ofM. leprae, was assessed by using sera from paucibacillary leprosy. N-terminal sequencing of the serum-reactive protein and functional assessment of the membrane fractions using monocyte-derived dendritic cells (DCs) identified major membrane protein II (MMP-II) as one of the efficient T-cell-activating candidates. Purified MMP-II stimulated DCs from healthy individuals to produce interleukin-12 p70 and up-regulated the surface expression of major histocompatibility complex class I and II, CD86, and CD83 molecules. Also, there was an increase in the percentage of CD83+cells in the DC population. Furthermore, MMP-II-pulsed DCs expressed their derivatives on their surfaces. Using Toll-like receptor 2 (TLR-2)-dependent receptor constructs, we found that TLR-2 signaling was involved in DC maturation induced by MMP-II. Taken together, MMP-II can be recognized as an immunomodulating protein in terms of activation of antigen-presenting cells and innate immunity.
Genomic Subtraction Followed by Dot Blot Screening of
Streptococcus pneumoniae
Clinical and Carriage Isolates Identifies Genetic Differences Associated with Strains That Cause Otitis Media
Authors: Pettigrew Melinda M. , Fennie Kristopher P.
Published: April 2005

Streptococcus pneumoniae
strains are the leading cause of bacterial otitis media, yet little is known about specific bacterial factors important for this disease. We utilized a molecular epidemiological approach involving genomic subtraction of the
S. pneumoniae
serogroup 19 middle ear strain 5093 against the laboratory strain R6. Resulting subtraction PCR (sPCR) products were used to screen a panel of 93 middle ear, 90 blood, 35 carriage, and 58 cerebrospinal fluid isolates from young children to identify genes found more frequently among middle ear isolates. Probe P41, similar to a hypothetical protein of
Brucella melitensis
, occurred among 41% of middle ear isolates and was found 2.8 (95% confidence interval [CI], 1.32 to 6.5), 3.3 (95% CI, 1.9 to 5.7), and 1.8 (95% CI, 1.1 to 3.0) times more frequently among middle ear strains than carriage, blood, or meningitis strains, respectively. sPCR fragment H10, similar to an unknown
Streptococcus agalactiae
protein, was present in 31% of middle ear isolates and occurred 3.6 (95% CI, 1.2 to 11.2), 2.8 (95% CI, 1.5 to 5.4), and 2.6 (95% CI, 1.2 to 5.5) times more often among middle ear isolates than carriage, blood, or meningitis strains, respectively. These studies have identified two genes of potential importance in otitis media virulence. Further studies are warranted to outline the precise role of these genes in otitis media pathogenesis.
Boosting of DNA Vaccine-Elicited Gamma Interferon Responses in Humans by Exposure to Malaria Parasites
Authors: Wang Ruobing , Richie Thomas L. , Baraceros Maria Fe , Rahardjo Nancy , Gay Tanya , Banania Jo-Glenna , Charoenvit Yupin , Epstein Judith E. , Luke Thomas , Freilich Daniel A. , Norman Jon , Hoffman Stephen L.
Published: April 2005

A mixture of DNA plasmids expressing fivePlasmodium falciparumpre-erythrocyte-stage antigens was administered with or without a DNA plasmid encoding human granulocyte-macrophage colony-stimulating factor (hGM-CSF) as an immune enhancer. After DNA immunization, antigen-specific gamma interferon (IFN-γ) responses were detected by ELISPOT in 15/31 volunteers to multiple class I- and/or class II-restricted T-cell epitopes derived from all five antigens. Responses to multiple epitopes (≤7) were detected simultaneously in some volunteers. By 4 weeks after challenge withP. falciparumparasites, 23/31 volunteers had positive IFN-γ responses and the magnitude of responses was increased from 2- to 143-fold. Nonetheless, none was protected against malaria. Volunteers who received hGM-CSF had a reduced frequency of IFN-γ responses to class I peptides compared to those who only received plasmids expressingP. falciparumproteins before challenge (3/23 versus 3/8;P= 0.15) or after parasite challenge (4/23 versus 5/8;P= 0.015) but not to class II peptides before or after challenge. The responses to one antigen (P. falciparumcircumsporozoite protein [PfCSP]) were similar among volunteers who received the five-gene mixture compared to volunteers who only received the PfCSP DNA plasmid in a previous study. In summary, DNA-primed IFN-γ responses were boosted in humans by exposure to native antigen on parasites, coadministration of a plasmid expressing hGM-CSF had a negative effect on boosting of class I-restricted IFN-γ responses, and there was no evidence that immunization with PfCSP DNA in the mixture reduced T-cell responses to PfCSP compared to when it was administered alone.
Human Lyme Arthritis and the Immunoglobulin G Antibody Response to the 37-Kilodalton Arthritis-Related Protein of
Borrelia burgdorferi
Authors: Salazar Carlos A. , Rothemich Monika , Drouin Elise E. , Glickstein Lisa , Steere Allen C.
Published: April 2005

In
Borrelia burgdorferi
-infected C3H-
scid
mice, antiserum to a differentially expressed, 37-kDa spirochetal outer-surface protein, termed arthritis-related protein (Arp), has been shown to prevent or reduce the severity of arthritis. In this study, we determined the immunoglobulin G (IgG) antibody responses to this spirochetal protein in single serum samples from 124 antibiotic-treated human patients with early or late manifestations of Lyme disease and in serial serum samples from 20 historic, untreated patients who were followed longitudinally from early infection through the period of arthritis. These 20 patients were representative of the spectrum of the severity and duration of Lyme arthritis. Among the 124 antibiotic-treated patients, 53% with culture-proven erythema migrans (EM) had IgG responses to recombinant glutathione
S
-transferase (GST)-Arp, as did 59% of the patients with facial palsy and 68% of those with Lyme arthritis. In addition, 75 to 80% of the 20 past, untreated patients had reactivity with this protein when EM was present, during initial episodes of joint pain, or during the maximal period of arthritis. There was no association at any of these three time points between GST-Arp antibody levels and the severity of the maximal attack of arthritis or the total duration of arthritis. Thus, after the first several weeks of infection, 60 to 80% of patients had IgG antibody responses to GST-Arp, but this response did not correlate with the severity or duration of Lyme arthritis.
CD46-Independent Binding of Neisserial Type IV Pili and the Major Pilus Adhesin, PilC, to Human Epithelial Cells
Authors: Kirchner Marieluise , Heuer Dagmar , Meyer Thomas F.
Published: April 2005

Neisseria gonorrhoeae
is a gram-negative bacterial pathogen which infects the human mucosal epithelium. An early critical event in neisserial infection is the type IV pilus-mediated adherence to the host cell. The PilC protein, located on the pilus tip, has earlier been identified as the major pilus adhesin. Previous studies suggested that the cell surface protein CD46 is a pilus receptor for
Neisseria
. We investigated the role of CD46 in pilus-mediated gonococcal infection of epithelial cells. Differences in binding efficiencies of piliated gonococci as well as purified pilus adhesin PilC2 on human epithelial cell lines did not correlate to the level of surface-expressed CD46. Additionally, no binding of piliated gonococci or PilC2 protein was observed on CD46-transfected CHO and MDCK cells. Furthermore, specific down-regulation of CD46 expression in human epithelial cell lines by RNA interference did not alter the binding efficiency of piliated gonococci or purified PilC2 protein, although other CD46-dependent processes, such as measles virus infection and C3b cleavage, were significantly reduced. These data support the notion that pilus-mediated gonococcal infection of epithelial cells can occur in a CD46-independent manner, thus questioning the function of CD46 as an essential pilus receptor for pathogenic neisseriae.
Construction and Characterization of
Listeria monocytogenes
Mutants with In-Frame Deletions in the Response Regulator Genes Identified in the Genome Sequence
Authors: Williams Tatjana , Bauer Susanne , Beier Dagmar , Kuhn Michael
Published: April 2005

Two-component systems are widely distributed in prokaryotes where they control gene expression in response to diverse stimuli. To study the role of the sixteen putative two-component systems of
Listeria monocytogenes
systematically, in frame deletions were introduced into 15 out of the 16 response regulator genes and the resulting mutants were characterized. With one exception the deletion of the individual response regulator genes has only minor effects on in vitro and in vivo growth of the bacteria. The mutant carrying a deletion in the ortholog of the
Bacillus subtilis
response regulator gene
degU
showed a clearly reduced virulence in mice, indicating that DegU is involved in the regulation of virulence-associated genes.
87Sr/86Sr of brines from the Fennoscandian Shield: a synthesis of groundwater isotopic data from the Baltic Sea region
Authors: Négrel Philippe , Casanova Joël , Blomqvist Runar
Published: April 2005

High salinity CaNaCl brines occur in Sweden and Finland. The complex geological history of the Fennoscandian Shield is reflected by the wide range of saline waters whose chemical compositions have been explained by local waterrock interaction, simple evolution of relict sea water, or freezing of sea water during glacial periods. This study deals with the present knowledge of Sr isotopes in groundwater from the Fennoscandian Shield to better constrain the origin of their deep saline component. Two different mixing trends are seen between Äspö Island groundwater and the Baltic Sea. The first trend links the North Sea to rivers through various dilution levels in the Baltic; the second trend is a simple linear relationship through Äspö groundwaters, agreeing with a binary mixing between a Baltic end-member and a highly Sr-concentrated fluid. Strontium isotope compositions are presented for precipitation in Finland and Sweden, the Baltic Sea, and the river waters draining the Fennoscandian Shield, and for groundwaters from several sites in the Fennoscandian Shield. At least six mixing lines between rain-and-snow input and surface waters can be drawn in each region around the Baltic Sea, reflecting a first step of waterrock interaction. A second series of calculated lines links the surface end-members and the deep brines, and defines a range of 87Sr/86Sr ratios for the deep brines at each site. All sites show a specific 87Sr/86Sr signature and the large 87Sr/86Sr variations is site specific. The well-constrained 87Sr/86Sr signatures in deep brines should correspond to a large, well-mixed, and homogeneous water reservoir.
Chemical tags in otoliths indicate the importance of local and distant settlement areas to populations of a temperate sparid, Pagrus auratus
Authors: Hamer Paul A , Jenkins Gregory P , Gillanders Bronwyn M
Published: April 2005

Understanding geographic origins of fish is essential to the management of fisheries and protection of critical juvenile habitats. We used natural chemical tags (Mn, Sr, and Ba), characterized from otoliths of 0+ snapper (Pagrus auratus) (approximately 13 months postsettlement), to determine the origins of 1- and 2-year-old (subadult) fish about to recruit to the Victorian fishery. We sampled subadults from eight areas across 700 km of coastline and within the major Victorian fishery, Port Phillip Bay. Maximum likelihood analyses indicated for both cohorts that most subadults in Port Phillip Bay and a significant proportion from west Victorian coastal waters had settled within Port Phillip Bay. The contribution of the Port Phillip Bay settlement area to coastal populations, however, decreased with distance to the west, varied between cohorts, and was negligible at locations over 200 km to the east of the bay. Comparison of elemental tags between 0+ fish of known settlement origin and the subadults indicated that unknown settlement areas may have contributed recruitment to one of the cohorts. These results have highlighted the importance of local settlement areas to sustaining the major Victorian fishery, but small juveniles can migrate large distances from this settlement area and contribute to coastal populations.
Multivariate life-history indices of exploited coral reef fish populations used to measure the performance of no-take zones in a marine protected area
Authors: Begg Gavin A , Mapstone Bruce D , Williams Ashley J , Adams Samantha , Davies Campbell R , Lou Dong C
Published: April 2005

We investigate the use of multivariate life-history indices to assess the performance of no-take zones with respect to ameliorating the impacts of harvest on exploited coral reef fish populations in the Great Barrier Reef Marine Park. A range of life-history parameters were estimated for the two major target species of the Great Barrier Reef (GBR) line fishery, common coral trout (Plectropomus leopardus) and red throat emperor (Lethrinus miniatus), collected from five adjacent reefs (three of which were closed to all forms of fishing) in each of three geographically dispersed regions between 1995 and 1998. Life-history parameters were used to compare the status of populations on open and closed reefs over regions and years. Principal components (PC) analyses were used to effectively reduce the number of parameters to four significant PCs for each species, accounting for 84% and 94% of the total variation in the data for common coral trout and red throat emperor, respectively. We were able to clearly identify those populations that were sampled from reefs open or closed to fishing based on the multivariate descriptors of life-history parameters. The concurrent use of several life-history indices maximised our potential to differentiate changes related to no-take zones from background variation.
Using ascidian embryos to study the evolution of developmental gene regulatory networks
Authors: Cone Angela C , Zeller Robert W
Published: April 2005

Ascidians are ideally positioned taxonomically at the base of the chordate tree to provide a point of comparison for developmental regulatory mechanisms that operate among protostomes, non-chordate deuterostomes, invertebrate chordates, and vertebrates. In this review, we propose a model for the gene regulatory network that gives rise to the ascidian notochord. The purpose of this model is not to clarify all of the interactions between molecules of this network, but to provide a working schematic of the regulatory architecture that leads to the specification of endoderm and the patterning of mesoderm in ascidian embryos. We describe a series of approaches, both computational and biological, that are currently being used, or are in development, for the study of ascidian embryo gene regulatory networks. It is our belief that the tools now available to ascidian biologists, in combination with a streamlined mode of development and small genome size, will allow for more rapid dissection of developmental gene regulatory networks than in more complex organisms such as vertebrates. It is our hope that the analysis of gene regulatory networks in ascidians can provide a basic template which will allow developmental biologists to superimpose the modifications and novelties that have arisen during deuterostome evolution.
EVOLUTION OF CONTINUOUS-TIME QUANTUM RANDOM WALKS ON CIRCLES
Authors: INUI NORIO , KASAHARA KOICHIRO , KONISHI YOSHINAO , KONNO NORIO
Published: April 2005

This work deals with both instantaneous uniform mixing property and temporal standard deviation for continuous-time quantum random walks on circles in order to study their fluctuations comparing with discrete-time quantum random walks, and continuous- and discrete-time classical random walks.
CAT'S DILEMMA — TRANSITIVITY VS. INTRANSITIVITY
Authors: PIOTROWSKI EDWARD W. , MAKOWSKI MARCIN
Published: April 2005

We study a simple example of a sequential game illustrating problems connected with making rational decisions that are universal for social sciences. The set of chooser's optimal decisions that manifest his preferences in case of a constant strategy of the adversary (the offering player), is investigated. It turns out that the order imposed by the player's rational preferences can be intransitive. The presented quantitative results imply a revision of the "common sense" opinions stating that preferences showing intransitivity are paradoxical and undesired.
THE GINI COEFFICIENT'S APPLICATION TO GENERAL COMPLEX NETWORKS
Authors: HU HAI-BO , WANG LIN
Published: April 2005

The Gini coefficient, which was originally used in microeconomics to describe income inequality, is introduced into the research of general complex networks as a metric on the heterogeneity of network structure. Some parameters such as degree exponent and degree-rank exponent were already defined in the case of scale-free networks also as a metric on the heterogeneity. In scale-free networks, the Gini coefficient is proved to be equivalent to the parameters mentioned above, and moreover, a classification of infinite scale-free networks is given according to the value of the Gini coefficient.
Role of SGK1 in nitric oxide inhibition of ENaC in Na+-transporting epithelia
Authors: Helms My N. , Yu Ling , Malik Bela , Kleinhenz Dean J. , Hart C. Michael , Eaton Douglas C.
Published: April 2005

Several studies have shown that nitric oxide (NO) inhibits Na+ transport in renal and alveolar monolayers. However, the mechanisms by which NO alters epithelial Na+ channel (ENaC) activity is unclear. Therefore, we examined the effect of applying the NO donor drug l-propanamine 3,2-hydroxy-2-nitroso-1-propylhidrazino (PAPA-NONOate) to cultured renal epithelial cells. A6 and M1 cells were maintained on permeable supports in medium containing 1.5 μM dexamethasone and 10% bovine serum. After 1.5 μM PAPA-NONOate was applied, amiloride-sensitive short-circuit current measurements decreased 29% in A6 cells and 44% in M1 cells. This differed significantly from the 3% and 19% decreases in A6 and M1 cells, respectively, treated with control donor compound ( P < 0.0005). Subsequent application of PAPA-NONOate to amiloride-treated control (no NONOate) A6 and M1 cells did not further decrease transepithelial current. In single-channel patch-clamp studies, NONOate significantly decreased ENaC open probability ( Po) from 0.186 ± 0.043 to 0.045 ± 0.009 ( n = 7; P < 0.05) without changing the unitary current. We also showed that aldosterone significantly decreased NO production in primary cultures of alveolar type II (ATII) epithelial cells. Because inducible nitric oxide synthase (iNOS) coimmunoprecipitated with the serum- and glucocorticoid-inducible kinase (SGK1) and both proteins colocalized in the cytoplasm (as shown in our studies in mouse ATII cells), SGK1 may also be important in regulating NO production in the alveolar epithelium. Our study also identified iNOS as a novel SGK1 phosphorylated protein (at S733 and S903 residues in miNOS) suggesting that one way in which SGK1 could increase Na+ transport is by altering iNOS production of NO.
Persistent Sodium Currents in Mesencephalic V Neurons Participate in Burst Generation and Control of Membrane Excitability
Authors: Wu Nanping , Enomoto Akifumi , Tanaka Susumu , Hsiao Chie-Fang , Nykamp Duane Q. , Izhikevich Eugene , Chandler Scott H.
Published: April 2005

The functional and biophysical properties of a persistent sodium current ( INaP) previously proposed to participate in the generation of subthreshold oscillations and burst discharge in mesencephalic trigeminal sensory neurons (Mes V) were investigated in brain stem slices (rats, p7–p12) using whole cell patch-clamp methods. INaPactivated around −76 mV and peaked at −48 mV, with V1/2of −58.7 mV. Ramp voltage-clamp protocols showed that INaPundergoes time- as well as voltage-dependent inactivation and recovery from inactivation in the range of several seconds (τonset= 2.04 s, τrecov= 2.21 s). Riluzole (≤5 μM) substantially reduced INaP, membrane resonance, postinhibitory rebound (PIR), and subthreshold oscillations, and completely blocked bursting, but produced modest effects on the fast transient Na+current ( INaT). Before complete cessation, burst cycle duration was increased substantially, while modest and inconsistent changes in burst duration were observed. The properties of the INaTwere obtained and revealed that the amplitude and voltage dependence of the resulting “window current” were not consistent with those of the observed INaPrecorded in the same neurons. This suggests an additional mechanism for the origin of INaP. A neuronal model was constructed using Hodgkin-Huxley parameters obtained experimentally for Na+and K+currents that simulated the experimentally observed membrane resonance, subthreshold oscillations, bursting, and PIR. Alterations in the model gNaPparameters indicate that INaPis critical for control of subthreshold and suprathreshold Mes V neuron membrane excitability and burst generation.
Calcium Time Course as a Signal for Spike-Timing–Dependent Plasticity
Authors: Rubin Jonathan E. , Gerkin Richard C. , Bi Guo-Qiang , Chow Carson C.
Published: April 2005

Calcium has been proposed as a postsynaptic signal underlying synaptic spike-timing–dependent plasticity (STDP). We examine this hypothesis with computational modeling based on experimental results from hippocampal cultures, some of which are presented here, in which pairs and triplets of pre- and postsynaptic spikes induce potentiation and depression in a temporally asymmetric way. Specifically, we present a set of model biochemical detectors, based on plausible molecular pathways, which make direct use of the time course of the calcium signal to reproduce these experimental STDP results. Our model features a modular structure, in which long-term potentiation (LTP) and depression (LTD) components compete to determine final plasticity outcomes; one aspect of this competition is a veto through which appropriate calcium time courses suppress LTD. Simulations of our model are also shown to be consistent with classical LTP and LTD induced by several presynaptic stimulation paradigms. Overall, our results provide computational evidence that, while the postsynaptic calcium time course contains sufficient information to distinguish various experimental long-term plasticity paradigms, small changes in the properties of back-propagation of action potentials or in synaptic dynamics can alter the calcium time course in ways that will significantly affect STDP induction by any detector based exclusively on postsynaptic calcium. This may account for the variability of STDP outcomes seen within hippocampal cultures, under repeated application of a single experimental protocol, as well as for that seen in multiple spike experiments across different systems.
Encoding the Timing of Inhibitory Inputs
Authors: Kanold Patrick O. , Manis Paul B.
Published: April 2005

Many neuronal systems represent information by the timing of individual spikes, and it is generally assumed that spike timing predominantly encodes excitatory inputs. We show here that the timing of inhibition can also be explicitly encoded in spike times using time-dependent and voltage-dependent properties of a rapidly inactivating potassium channel ( IKIF). In vitro recordings in rat dorsal cochlear nucleus show that the effects of inhibition on spike timing can long outlast the duration of the inhibitory potential and that this depends only on the membrane voltage change during the inhibitory postsynaptic potential. Modeling results show that small neuronal populations with a heterogeneous distribution of IKIF voltage dependence can robustly encode intervals of >100 ms between inhibition and excitation. Thus neuronal systems can detect and represent the precise timing of inhibition, suggesting the importance of inhibition in information encoding.
Relation Between Activities of the Cortex and Vibrissae Muscles During High-Voltage Rhythmic Spike Discharges in Rats
Authors: Shaw Fu-Zen , Liao Yi-Fang
Published: April 2005

Paroxysmal 5- to 12-Hz high-voltage rhythmic spike (HVRS) activities, which are accompanied by whisker twitching (WT), are found in Long Evans rats, but the function of these HVRS activities is still debated. In four major functional hypotheses of HVRS discharges, i.e., alpha tremor, attention/mu rhythm, idling/mu rhythm, and absence seizure, the first two hypotheses emphasize WT behavior in HVRS bouts. Whisker movement is primarily determined by activation of intrinsic and extrinsic muscles. To clarify the role of WT in HVRS activities, simultaneous recording of the activities from the cortex and intrinsic/extrinsic and neck muscles were performed. Most HVRS bouts (68.8%) revealed no time-locked WT behavior in a 2-h recording session. In addition, WT primarily arose from active protraction due to activation of intrinsic muscles followed by passive retraction. A small portion of WT resulted from activation of both vibrissae muscles with dynamic frequency-dependent phase shifts. Onset of the rhythmic vibrissae EMG significantly lagged behind HVRS onset, and the mean duration of vibrissae muscle activity was one-third to a one-half of a HVRS bout. Moreover, a greater number of HVRS bouts were associated with a longer HVRS duration and higher oscillation frequency. Oscillation frequencies of HVRS activities without WT behavior were significantly lower than those with WT. Under peripheral sensory/motor blockade by xylocaine injection, oscillation frequencies of HVRS bouts significantly decreased, but no remarkable changes in the number or duration of HVRS bouts were observed. Compared with vibrissa muscle activity during WT and exploratory whisking, the duration of muscular activity in each cycle was apparently longer during whisking bouts. Based on these results, overemphasis of the role of WT on HVRS activities might not be appropriate. Instead, HVRS discharges may be associated with absence seizure or idling state. In addition, peripheral inputs, including WT, may elevate the oscillation frequency of HVRS bouts. Moreover, different muscular controls may exist between WT and whisking.
Discharge Characteristics of Pursuit Neurons in MST During Vergence Eye Movements
Authors: Akao Teppei , Mustari Michael J. , Fukushima Junko , Kurkin Sergei , Fukushima Kikuro
Published: April 2005

For small objects moving smoothly in space close to the observer, smooth pursuit and vergence eye movements maintain target images near the foveae to insure high-resolution processing of visual signals about moving objects. Signals for both systems must be synthesized for pursuit-in-three-dimensions (3D). Recent studies have shown that responses of the majority of pursuit neurons in the frontal eye fields (FEF) code pursuit-in-3D. This area is known to have reciprocal connections with the medial superior temporal area (MST) where frontal pursuit neurons are found. To examine whether pursuit-in-3D signals are already present in MST and how MST neurons discharge during vergence-tracking induced by a small spot, we examined discharge of MST pursuit neurons in 2 monkeys. Of a total of 219 pursuit neurons examined during both frontal pursuit and vergence-tracking, 61% discharged only for frontal pursuit, 18% only for vergence-tracking, and 21% for both. A majority of vergence-related MST neurons exhibited sensitivity to vergence eye velocity. Their discharge was maintained during brief blanking of a vergence target. About 1/3 of vergence-related MST neurons exhibited visual responses to spot motion in depth. The preferred directions for visual motion and vergence-tracking were similar in half of our population. Some of the remaining neurons showed opposite preferred directions. A significant proportion (29%) of vergence-related neurons discharged before onset of eye movements with lead times longer than 20 ms. The results in this and previous studies indicate differences in discharge characteristics of FEF and MST pursuit neurons, suggesting different roles for the two in pursuit-in-3D.
Intracortical Pathways Mediate Nonlinear Fast Oscillation (>200 Hz) Interactions Within Rat Barrel Cortex
Authors: Staba Richard J. , Ard Tyler D. , Benison Alexander M. , Barth Daniel S.
Published: April 2005

Whisker evoked fast oscillations (FOs; >200 Hz) within the rodent posteromedial barrel subfield are thought to reflect very rapid integration of multiwhisker stimuli, yet the pathways mediating FO interactions remain unclear and may involve interactions within thalamus and/or cortex. In the present study using anesthetized rats, a cortical incision was made between sites representing the stimulated whiskers to determine how intracortical networks contributed to patterns of FOs. With cortex intact, simultaneous stimulation of a pair of whiskers aligned in a row evoked supralinear responses between sites separated by several millimeters. In contrast, stimulation of a nonadjacent pair of whiskers within an arc evoked FOs with no evidence for nonlinear interactions. However, stimulation of an adjacent pair of whiskers in an arc did evoke supralinear responses. After a cortical cut, supralinear interactions associated with FOs within a row were lost. These data indicate a distinct bias for stronger long-range connectivity that extends along barrel rows and that horizontal intracortical pathways exclusively mediate FO-related integration of tactile information.
The retinoblastoma gene pathway regulates the postmitotic state of hair cells of the mouse inner ear
Authors: Mantela Johanna , Jiang Zhe , Ylikoski Jukka , Fritzsch Bernd , Zacksenhaus Eldad , Pirvola Ulla
Published: April 2005

Precursors of cochlear and vestibular hair cells of the inner ear exit the cell cycle at midgestation. Hair cells are mitotically quiescent during late-embryonic differentiation stages and postnatally. We show here that the retinoblastoma gene Rb and the encoded protein pRb are expressed in differentiating and mature hair cells. In addition to Rb, the cyclin dependent kinase inhibitor (CKI) p21 is expressed in developing hair cells, suggesting that p21 is an upstream effector of pRb activity. p21 apparently cooperates with other CKIs, as p21-null mice exhibited an unaltered inner ear phenotype. By contrast, Rb inactivation led to aberrant hair cell proliferation, as analysed at birth in a loss-of-function/transgenic mouse model. Supernumerary hair cells expressed various cell type-specific differentiation markers, including components of stereocilia. The extent of alterations in stereociliary bundle morphology ranged from near-normal to severe disorganization. Apoptosis contributed to the mutant phenotype, but did not compensate for the production of supernumerary hair cells, resulting in hyperplastic sensory epithelia. The Rb-null-mediated proliferation led to a distinct pathological phenotype, including multinucleated and enlarged hair cells, and infiltration of hair cells into the mesenchyme. Our findings demonstrate that the pRb pathway is required for hair cell quiescence and that manipulation of the cell cycle machinery disrupts the coordinated development within the inner ear sensory epithelia.
From the Editor
Authors: Camm Jeffrey D.
Published: April 2005

I have made several additions to the editorial board and am planning a new special issue.
LP Modeling for Asset-Liability Management: A Survey of Choices and Simplifications
Authors: Sodhi ManMohan S.
Published: April 2005

Dynamic linear programming (LP) models for asset-liability management (ALM) are quite powerful and flexible but face two challenges: (1) many modeling choices, not all consistent with one another or with finance theory, and (2) solution difficulties due to the large number of scenarios obtained from standard interest-rate models. We first survey these modeling choices with a view to help researchers make self-consistent choices. Next, we review how the dynamic LP model for ALM and the representation of uncertainty therein have been simplified in the past to motivate new or hybrid models emphasizing tractability. To this end, we review existing static LP models as extreme modeling simplifications and aggregation as a simplification of uncertainty.