bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased Excitability of Acidified Skeletal Muscle
Authors: Pedersen Thomas H. , de Paoli Frank , Nielsen Ole B.
Published: January 2005

Generation of the action potentials (AP) necessary to activate skeletal muscle fibers requires that inward membrane currents exceed outward currents and thereby depolarize the fibers to the voltage threshold for AP generation. Excitability therefore depends on both excitatory Na+ currents and inhibitory K+ and Cl− currents. During intensive exercise, active muscle loses K+ and extracellular K+ ([K+]o) increases. Since high [K+]o leads to depolarization and ensuing inactivation of voltage-gated Na+ channels and loss of excitability in isolated muscles, exercise-induced loss of K+ is likely to reduce muscle excitability and thereby contribute to muscle fatigue in vivo. Intensive exercise, however, also leads to muscle acidification, which recently was shown to recover excitability in isolated K+-depressed muscles of the rat. Here we show that in rat soleus muscles at 11 mM K+, the almost complete recovery of compound action potentials and force with muscle acidification (CO2 changed from 5 to 24%) was associated with reduced chloride conductance (1731 ± 151 to 938 ± 64 μS/cm2, P < 0.01) but not with changes in potassium conductance (405 ± 20 to 455 ± 30 μS/cm2, P < 0.16). Furthermore, acidification reduced the rheobase current by 26% at 4 mM K+ and increased the number of excitable fibers at elevated [K+]o. At 11 mM K+ and normal pH, a recovery of excitability and force similar to the observations with muscle acidification could be induced by reducing extracellular Cl− or by blocking the major muscle Cl− channel, ClC-1, with 30 μM 9-AC. It is concluded that recovery of excitability in K+-depressed muscles induced by muscle acidification is related to reduction in the inhibitory Cl− currents, possibly through inhibition of ClC-1 channels, and acidosis thereby reduces the Na+ current needed to generate and propagate an AP. Thus short term regulation of Cl− channels is important for maintenance of excitability in working muscle.
Decreased Phosphatase Activity, Increased Ca2+ Sensitivity, and Myosin Light Chain Phosphorylation in Urinary Bladder Smooth Muscle of Newborn Mice
Authors: Ekman Mari , Fagher Katarina , Wede Mia , Stakeberg Karolina , Arner Anders
Published: January 2005

Developmental changes in the regulation of smooth muscle contraction were examined in urinary bladder smooth muscle from mice. Maximal active stress was lower in newborn tissue compared with adult, and it was correlated with a lower content of actin and myosin. Sensitivity to extracellular Ca2+ during high-K+ contraction, was higher in newborn compared with 3-wk-old and adult bladder strips. Concentrations at half maximal tension (EC50) were 0.57 ± 0.01, 1.14 ± 0.12, and 1.31 ± 0.08 mM. Force of the newborn tissue was inhibited by ∼45% by the nonmuscle myosin inhibitor Blebbistatin, whereas adult tissue was not affected. The calcium sensitivity in newborn tissue was not affected by Blebbistatin, suggesting that nonmuscle myosin is not a primary cause for increased calcium sensitivity. The relation between intracellular [Ca2+] and force was shifted toward lower [Ca2+] in the newborn bladders. This increased Ca2+ sensitivity was also found in permeabilized muscles (EC50: 6.10 ± 0.07, 5.77 ± 0.08, and 5.55 ± 0.02 pCa units, in newborn, 3-wk-old, and adult tissues). It was associated with an increased myosin light chain phosphorylation and a decreased rate of dephosphorylation. No difference was observed in the myosin light chain phosphorylation rate, whereas the rate of myosin light chain phosphatase–induced relaxation was about twofold slower in the newborn tissue. The decreased rate was associated with a lower expression of the phosphatase regulatory subunit MYPT-1 in newborn tissue. The results show that myosin light chain phosphatase activity can be developmentally regulated in mammalian urinary bladders. The resultant alterations in Ca2+ sensitivity may be of importance for the nervous and myogenic control of the newborn bladders.
GCK-3, a Newly Identified Ste20 Kinase, Binds To and Regulates the Activity of a Cell Cycle–dependent ClC Anion Channel
Authors: Denton Jerod , Nehrke Keith , Yin Xiaoyan , Morrison Rebecca , Strange Kevin
Published: January 2005

CLH-3b is a Caenorhabditis elegans ClC anion channel that is expressed in the worm oocyte. The channel is activated during oocyte meiotic maturation and in response to cell swelling by serine/threonine dephosphorylation events mediated by the type 1 phosphatases GLC-7α and GLC-7β. We have now identified a new member of the Ste20 kinase superfamily, GCK-3, that interacts with the CLH-3b COOH terminus via a specific binding motif. GCK-3 inhibits CLH-3b in a phosphorylation-dependent manner when the two proteins are coexpressed in HEK293 cells. clh-3 and gck-3 are expressed predominantly in the C. elegans oocyte and the fluid-secreting excretory cell. Knockdown of gck-3 expression constitutively activates CLH-3b in nonmaturing worm oocytes. We conclude that GCK-3 functions in cell cycle– and cell volume–regulated signaling pathways that control CLH-3b activity. GCK-3 inactivates CLH-3b by phosphorylating the channel and/or associated regulatory proteins. Our studies provide new insight into physiologically relevant signaling pathways that control ClC channel activity and suggest novel mechanisms for coupling cell volume changes to cell cycle events and for coordinately regulating ion channels and transporters that control cellular Cl− content, cell volume, and epithelial fluid secretion.
Moral Hazard, Inspection Policy, and Food Safety
Authors: Starbird S. Andrew
Published: January 2005

Buyers have imperfect information about the food safety efforts exerted by suppliers. To gather information about safety, buyers often employ sampling inspection. Sampling inspection exhibits sampling error so some unsafe product passes inspection and some safe product does not. This uncertainty influences buyer and supplier behavior. In this article, I use a principal‐agent model to examine how sampling inspection policies influence food safety. I use the model to examine the sampling inspection policies in the 1996 Pathogen Reduction/Hazard Analysis Critical Control Point Act. I conclude that the regulation of sampling inspection procedures is an effective tool for policy makers who wish to improve food safety.
Living with the Curse of Dimensionality: Closed‐Loop Optimization in a Large‐Scale Fisheries Simulation Model
Authors: Woodward Richard T. , Wui Yong‐Suhk , Griffin Wade L.
Published: January 2005

Facilitated by remarkable increases in computational speed, simulation models are becoming more and more complex and are being increasingly used in applied economic analysis. However, computational limitations remain a major barrier to the study of dynamically optimal policies. We study the problem of carrying out dynamic optimization in conjunction with large simulation models and propose a method for working around the computational difficulties that arise in such problems. Our methods are applied to a model of the Gulf of Mexico's red snapper fishery to study the dynamically optimal total allowable catch.
Behavioral and Welfare Effects of Tournaments and Fixed Performance Contracts: Some Experimental Evidence
Authors: Wu Steven , Roe Brian
Published: January 2005

Using experimental economics, we compare the efficiency and welfare effects of tournaments and fixed performance contracts. Our subjects (agents) were generally better off under fixed performance contracts, but the advantage of the fixed performance contract disappears if the relative magnitude of the standard deviation of the common shock exceeds a critical value. Efficiency wise, agents tend to exert higher effort under fixed performance contracts, on average. Additionally, an increase in the common shock standard deviation appeared to be associated with lower effort under tournaments. Our results shed light on the potential impact of legislative proposals to ban tournament contracts.
Distributional effects of ‘general population’ prescription drug programs in Canada
Authors: Alan Sule , Crossley Thomas F. , Grootendorst Paul , Veall Michael R.
Published: January 2005

Abstract.  Canadian household prescription drug expenditures are studied using the Statistics Canada Family Expenditure Survey masterfiles for periods that include the introduction of provincial ‘general population’ prescription drug programs. Budget shares for non‐senior households are examined over time using non‐parametric regression, parametric ‘difference‐in‐difference’ techniques, and quantile regression methods. The evidence suggests that while program effects are muted when there are high deductibles, a non‐senior prescription drug subsidy is more redistributive than an equal‐cost proportional income transfer, in part because of differential private health insurance coverage by income. This is in contrast to previous evidence on Canadian senior prescription drug subsidies. JEL classification: I18, J42
Trade, market size, and industrial structure: revisiting the home‐market effect
Authors: Yu Zhihao
Published: January 2005

Abstract.  This paper shows that the issues in the recent discussion over the ‘home‐market effects’ are more complicated than previously thought. It is shown that, in general, market size matters for industrial structure even when both the homogeneous and the differentiated goods face transport costs. The home‐market effect for production structure can arise, disappear, or even reverse in sign. The analysis shall change a common perception about de‐industrialization of (small) economies and may also have important implications for the empirical research strategies in this area. JEL classification: F12, L1
Phenotypic and Functional Characterization of Clinical Grade Dendritic Cells Generated from Patients with Advanced Breast Cancer for Therapeutic Vaccination
Authors: Pedersen A. E. , Thorn M. , Gad M. , Walter M. R. , Johnsen H. E. , Gaarsdal E. , Nikolajsen K. , Buus S. , Claesson M. H. , Svane I. M.
Published: January 2005

Dendritic cells (DC) are promising candidates for cancer immunotherapy. However, it is not known whether in vitro‐generated monocyte‐derived DC from cancer patients are altered compared with DC from healthy donors. In a clinical phase I/II study, monocyte‐derived DC were generated in vitro utilizing granulocyte macrophage colony‐stimulating factor and rh‐interleukin‐4 (IL‐4) and used for cancer immunotherapy. In this study, we tested the effect of various maturation cocktails and performed a comparative evaluation of the DC phenotype and functional characteristics. Polyriboinosinic polyribocytidylic acid (Poly I:C) + tumour necrosis factor‐alpha (TNF‐α) induced significant IL‐12 p70 secretion, which was increased after addition of a decoy IL‐10 receptor. The lymph node homing chemokine receptor CCR‐7 expression was induced by TNF‐α + IL‐1β + IL‐6 + prostaglandin E2 but was not induced by Poly I:C + TNF‐α. In general, DC from patients had an intermediate maturity phenotype with a significantly higher expression of CD40 and CD54 compared with healthy donors. In vitro analyses showed an unimpaired capacity of the patient‐derived DC for antigen‐specific (cytomegalovirus, tetanus and keyhole limpet haemocyanin) T‐cell stimulation, whereas the allostimulatory capacity of patient‐derived DC was significantly decreased. These data suggest that patient‐derived DC are more differentiated but are less sensitive to maturation‐inducing agents than DC obtained from healthy individuals.
Structurally Derived Mutations Define Congenital Heart Block‐Related Epitopes Within the 200–239 Amino Acid Stretch of the Ro52 Protein
Authors: Ottosson L. , Salomonsson S. , Hennig J. , Sonesson S.‐E. , Dörner T. , Raats J. , Kuchroo V. K. , Sunnerhagen M. , Wahren‐Herlenius M.
Published: January 2005

Congenital heart block is a passively transferred autoimmune condition, which affects the children of mothers with Ro/SSA autoantibodies. During pregnancy, the antibodies are transported across the placenta and affect the fetus. We have previously demonstrated that antibodies directed to the 200–239 amino acid (aa) stretch of the Ro52 component of the Ro/SSA antigen correlate with the development of congenital heart block. In this report, we investigated the antibody–antigen interaction of this target epitope in detail at a molecular and structural level. Peptides representing aa 200–239 (p200) with structurally derived mutations were synthesized to define the epitopes recognized by two Ro52 human monoclonal antibodies, S3A8 and M4H1, isolated from patient‐derived phage display libraries. Analyses by ELISA, circular dichroism and MALDI‐TOF‐MS demonstrate that the antibody recognition is dependent on a partly α‐helical fold within the putative leucine zipper of the 200–239 aa stretch and that the two human anti‐p200 monoclonal antibodies, M4H1 and S3A8, recognize different epitopic structures within the p200 peptide. In addition, we investigated the representation of each fine specificity within the sera of mothers with children born with congenital heart block, and in such sera, antibodies of the S3A8 idiotype were more commonly detected and at higher levels than M4H1‐like antibodies.
Genetic Segregation of Spontaneous Erosive Arthritis and Generalized Autoimmune Disease in the BXD2 Recombinant Inbred Strain of Mice
Authors: Mountz J. D. , Yang P. , Wu Q. , Zhou J. , Tousson A. , Fitzgerald A. , Allen J. , Wang X. , Cartner S. , Grizzle W. E. , Yi N. , Lu L. , Williams R. W. , Hsu H.‐C.
Published: January 2005

The BXD2 strain of mice is one of approximately 80 BXD recombinant inbred (RI) mouse strains derived from an intercross between C57BL/6J (B6) and DBA/2J (D2) strains. We have discovered that adult BXD2 mice spontaneously develop generalized autoimmune disease, including glomerulonephritis (GN), increased serum titres of rheumatoid factor (RF) and anti‐DNA antibody, and a spontaneous erosive arthritis characterized by mononuclear cell infiltration, synovial hyperplasia, and bone and cartilage erosion. The features of lupus and arthritis developed by the BXD2 mice segregate in F2 mice generated by crossing BXD2 mice with the parental B6 and D2 strains. Genetic linkage analysis of the serum levels of anti‐DNA and RF by using the BXD RI strains shows that the serum titers of anti‐DNA and RF were influenced by a genetic locus on mouse chromosome (Chr) 2 near the marker D2Mit412 (78 cm, 163 Mb) and on Chr 4 near D4Mit146 (53.6 cm, 109 Mb), respectively. Both loci are close to the B‐cell hyperactivity, lupus or GN susceptibility loci that have been identified previously. The results of our study suggest that the BXD2 strain of mice is a novel model for complex autoimmune disease that will be useful in identifying the mechanisms critical for the immunopathogenesis and genetic segregation of lupus and erosive arthritis.
Immunological Characterization of Novel Secreted Antigens of Mycobacterium tuberculosis
Authors: Amor Y. B. , Shashkina E. , Johnson S. , Bifani P. J. , Kurepina N. , Kreiswirth B. , Bhattacharya S. , Spencer J. , Rendon A. , Catanzaro A. , Gennaro M. L.
Published: January 2005

Proteins secreted by Mycobacterium tuberculosis are targets of host immune responses and as such are investigated for vaccine and immunodiagnostics development. Computer‐driven searches of the M. tuberculosis H37Rv genome had previously identified 45 novel secreted proteins. Here, we report the characterization of these antigens in terms of specificity for the M. tuberculosis complex and the ability to induce human immune responses. BLAST homology searches and Southern hybridization identified 10 genes that were either specific for the M. tuberculosis complex or found in only two nontuberculous mycobacterial species of minor medical significance. Selected recombinant proteins were purified from Escherichia coli cells and tested for the ability to elicit antibody responses in tuberculosis patients. Reactivity of the serum panel was ` 36% with at least one of five novel proteins (Rv0203, Rv0603, Rv1271c, Rv1804c and Rv2253), 56% with the 38 kDa lipoprotein, a M. tuberculosis antigen known to be highly seroreactive, and 68% with a combination of Rv0203, Rv1271c and the 38 kDa antigen. Thus, at least five novel secreted proteins induce antibody responses during active disease; some of these proteins may increase the sensitivity of serological assays based on the 38 kDa antigen.
Phylogeny and biogeography of cichlid fishes (Teleostei: Perciformes: Cichlidae)
Authors: Sparks John S. , Smith Wm. Leo
Published: January 2005

Family level molecular phylogenetic analyses of cichlid fishes have generally suffered from a limited number of characters and/or poor taxonomic sampling across one or more major geographic assemblage, and therefore have not provided a robust test of early intrafamilial diversification. Herein we use both nuclear and mitochondrial nucleotide characters and direct optimization to reconstruct a phylogeny for cichlid fishes. Representatives of major cichlid lineages across all geographic assemblages are included, as well as nearly twice the number of characters as any prior family‐level study. In a strict consensus of 81 equally most‐parsimonious hypotheses, based on the simultaneous analysis of 2222 aligned nucleotide characters from two mitochondrial and two nuclear genes, four major subfamilial lineages are recovered with strong support. Etroplinae, endemic to Madagascar (Paretroplus) and southern Asia (Etroplus), is recovered as the sister taxon to the remainder of Cichlidae. Although the South Asian cichlids are monophyletic, the Malagasy plus South Asian lineages are not. The remaining Malagasy lineage, Ptychochrominae, is monophyletic and is recovered as the sister group to a clade comprising the African and Neotropical cichlids. The African (Pseudocrenilabrinae) and Neotropical (Cichlinae) lineages are each monophyletic in this reconstruction. The use of multiple molecular markers, from both mitochondrial and nuclear genes, results in a phylogeny that in general exhibits strong support, notably for early diversification events within Cichlidae. Results further indicate that Labroidei is not monophyletic, and that the sister group to Cichlidae may comprise a large and diverse assemblage of percomorph lineages. This hypothesis may at least partly explain why morphological studies that have attempted to place Cichlidae within Percomorpha, or that have tested cichlid monophyly using only “labroid” lineages, have met with only limited success.

© The Willi Hennig Society 2004.
The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data
Authors: Rousset Vincent , Rouse Greg W. , Siddall Mark E. , Tillier Annie , Pleijel Fredrik
Published: January 2005

We assess the phylogenetic position of Siboglinidae (previously known as the phyla Pogonophora and Vestimentifera, but now referred to Annelida) in parsimony analyses of 1100 bp from 18S rRNA, 320 bp from the D1 region of 28S rRNA, and 107 morphological characters, totaling 667 parsimony informative characters. The 34 terminal taxa, apart from six siboglinids, include polychaete members of Sabellida, Terbelliformia, Cirratuliformia and Spionida, plus two Aciculata polychaetes as outgroups. Our results contradict most recent hypotheses in showing a sistergroup relationship between Siboglinidae and Oweniidae, and in that the latter taxon is not a member of Sabellida. Furthermore, our results indicate that Sabellariidae is not closely related to Sabellida, that Serpulidae may be nested within Sabellidae, and that Alvinellidae is nested within Ampharetidae.

© The Willi Hennig Society 2004.
Fireblight in Békés County (Hungary) in 1996/20021
Authors: Zsolt M.
Published: January 2005

Fireblight (Erwinia amylovora) appeared in Hungary in 1996. Most damage occurred on apple, pear, quince and medlar, and also on the ornamentals Pyracantha, Sorbus, Cotoneaster and Crataegus. In 1996–2006, an official programme for elimination of infected parts of plants started in Békés county. This mainly concerned trees in towns and villages, since there are few pome‐fruit orchards in the county. Work teams under official direction pruned back or cut down trees. In total, some 13 000 trees were pruned back and nearly 11 000 were cut down. In addition, 21 villages were subjected to special phytosanitary measures. Infection decreased considerably between 1996 and 2002, but over 90% of the inhabited areas in the county remained subject to special measures, because of the very dispersed occurrence of fireblight.
Ten years of experience with fireblight in Austria1
Authors: Keck M.
Published: January 2005

In 1993, fireblight (Erwinia amylovora) was detected for the first time in Austria, in the most westerly part of the country (Vorarlberg). During the following years, especially since 1998, a stepwise migration from west to east was observed. For control, mechanical measures are mostly used. As these measures require early recognition of symptoms, broad information campaigns for the public and extensive surveys of host plants have been set up. Suspicious plant samples are sent to the central laboratory for diagnosis. Regional plant protection services are assisted by trained volunteers. Eradication and pruning measures are performed by trained working teams. Infected plant material is burned. In all pome‐fruit production areas, the disease forecasting system Maryblyt has been established. Regulations concerning the movement of beehives have been adopted, together with prohibition of the planting of certain ornamental host plants (Crataegus, Cotoneaster). Chemical treatments are limited to one copper oxychloride product. In 2003, temporary application of Prohexadione‐Ca for the prevention of shoot infections was authorized. In some areas, the rigorous application of control measures has reduced the incidence of fireblight and possibly slowed down its progress. However these measures are not sufficient to protect against new, unexpected outbreaks.
Experiences with the control of fireblight in Norway during 1986/20031
Authors: Sletten A. , Melboe N. S.
Published: January 2005

Fireblight was detected for the first time in Norway in 1986, in a limited outbreak on ornamentals, in particular Cotoneaster. An organization for the eradication and containment of the disease was rapidly established, and given comprehensive statutory powers and resources to do surveys and to remove diseased plants and highly susceptible plants from infested areas. The activities have so far been successful. The disease has remained within a restricted area on the West Coast, and has not moved into important fruit‐growing areas or nurseries. Since 2000, fireblight has spread to some adjoining areas, mainly due to uncontrolled movement of beehives. New statutory powers prohibit movement of beehives out of infested areas from May to October.
Introduction of Frankliniella occidentalis and occurrence of Tomato spotted wilt tospovirus in Albania
Authors: Çota E. , Merkuri J.
Published: January 2005

The important quarantine pest Frankliniella occidentalis was found in Albania for the first time in 2001. A monitoring programme using blue and yellow sticky traps, and examination of flower samples from tomato, cucumber and Rubus, confirmed the presence of the pest at low levels in tomato glasshouses in Durrës and Tirana districts, and outdoors on Rubus. TSWV was also detected, and confirmed by ELISA, on tomato and weeds.
Viruses and virus diseases of grapevine in Egypt
Authors: Ahmed H.M.H. , Digiaro M. , Martelli G.P.
Published: January 2005

Surveys for virus and virus‐like diseases were carried out in commercial vineyards of the main grapevine‐growing areas of Egypt along the river Nile and in recently reclaimed desert lands. The only symptoms observed and identified with reasonable confidence in the field were those of leafroll disease in red‐berried cultivars. No virus was transmitted to herbaceous hosts by mechanical inoculation from glasshouse‐forced cuttings of about 300 vines (40% of total samples). By contrast, ELISA tests showed that 78% of the assayed European vines (521 out of 664) were infected by one (29%) or more (49%) viruses. Grapevine virus A (GVA) was the most widespread virus (67.9% infection), followed by Grapevine leafroll‐associated virus 3 (GLRaV‐3) (55.9% infection). All the other viruses tested for were scarcely represented, i.e. Grapevine leafroll‐associated virus 1 (GLRaV‐1) 1.8% infection, Grapevine leafroll‐associated virus 2 (GLRaV‐2) 1.4% infection, Grapevine virus B (GVB) (0.6% infection) and Grapevine fleck virus (GFkV) (0.2% infection), or, like Grapevine fanleaf virus (GFLV), were totally absent. The infection rate of native cultivars (86%) was particularly heavy. ‘Banaty Abiad’ and ‘Romy Ahmer’, the two major Egyptian cultivars, had infection levels of 78% and 89%, respectively, and ‘Fayoumy’, the most important cultivar in the Fayoum area, had 96% infection. Totally infected were the tested samples of several minor native cultivars such as ‘Farg El‐Tair’, ‘Siwi Abiad’, ‘Ta’afi’, ‘Romy Abiad’, ‘Eswid El‐Wady’, ‘Edkawy’ and ‘Bez El‐Anza’. Slightly better was the sanitary situation of imported European grapevine cultivars (60% infection) and of American rootstocks (11.5% infection). In rootstocks, infection rate by GVA and GLRaV‐3 was 5.5%, whereas GVB and GLRaV‐1 were only sporadically detected.
A preliminary account of the sanitary status of stone‐fruit trees in Morocco
Authors: Bouani A. , Al Rwahnih M. , Ghanem‐Sabanadzovic N. Abou , Alami I. , Zemzami M. , Myrta A. , Savino V.
Published: January 2005

Field surveys were carried out in the main stone‐fruit growing areas of Morocco to evaluate the sanitary status of commercial orchards, varietal collections and nurseries. The presence of virus and virus‐like diseases was checked by ELISA, sap transmission to herbaceous hosts, testing on woody indicators and molecular hybridization (dot‐blot and tissue‐printing). 1211 samples (382 almond, 339 peach, 291 plum, 150 apricot and 49 cherry) were tested by ELISA for the presence of Prunus necrotic ring spot virus (PNRSV), Prune dwarf virus (PDV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV) and Plum pox virus (PPV). The overall average of virus infection rate was 16.4%, whereas that of single species was: 22.6% for almond, 17.8% for plum, 15% for peach, 10.2% for cherry, and 2.7% for apricot. The following viruses were detected: PNRSV, PDV, ACLSV and ApMV. 565 samples were tested by dot‐blot and tissue‐printing hybridization for the presence of Peach latent mosaic viroid (PLMVd) and Hop stunt viroid (HSVd). 48 samples were infected, 41 by PLMVd and 7 by HSVd. In addition, nested‐PCR tests identified Plum bark necrosis and stem‐pitting associated virus (PBNSPaV) in a few almond trees affected by stem pitting.
Experience with fireblight in the Czech Republic1
Authors: Bĕhalová M.
Published: January 2005

Erwinia amylovora has been spreading in the Czech Republic since 1986 regardless of emergency phytosanitary measures which have been taken. Its spread follows the predominant wind direction (west to east). The infested area now covers two thirds of the area of the country. Wild Crataegus spp. are the most important and widespread host plants. E. amylovora is still regulated as a quarantine pest, and areas free from fireblight are subject to special phytosanitary measures.
Practice of applying streptomycin to control fireblight in Hungary1
Authors: Németh J.
Published: January 2005

The conditions under which streptomycin may be used for fireblight control in Hungary are described. Authorizations for individual limited treatment programmes are given to registered growers only.
Emergence en Tunisie de Fusarium oxysporum f.sp. tuberosi agent de flétrissure vasculaire des plants et de pourriture sèche des tubercules de pomme de terre
Authors: Daami‐Remadi Mejda M. , Mahjoub Et M. El
Published: January 2005

Le pouvoir pathogène de certains isolats de Fusarium oxysporum collectés a été testé sur plants et sur tubercules de pomme de terre. L’inoculation de plants du cultivar ‘Spunta’ par une suspension de spores a engendré une réduction de croissance et le flétrissement vasculaire de l’ensemble des plants inoculés par les différents isolats. L’agent pathogène a été ré‐isolé. Sur tubercules, les différents isolats se sont comporté comme agents de pourriture sèche. Cet ensemble de résultats confirme qu’il s’agit de Fusarium oxysporum f.sp. tuberosi, signalé pour la première fois en Tunisie.
Occurrence of viruses in irrigated wheat in Zambia
Authors: Kapooria R. G. , Ndunguru J.
Published: January 2005

Surveys were conducted during the cool‐dry months of June–August 1997 and June–July 1998 for the presence of viruses in irrigated wheat in Central, Copperbelt, Lusaka and Southern Provinces of Zambia in 14 commercial farms and four wheat cultivar plots. Virus symptoms were observed on nine wheat cultivars (Triticum aestivum‘Deka’, ‘Gamtoos’, ‘Lorie II’, ‘MM2’, ‘Nata’, ‘Nkwazi’, ‘P7’, ‘Scan’ and ‘Sceptre’) of South African, Zambian and Zimbabwean origin. Several viruses were identified on the basis of field symptomatology, symptoms developing on mechanically inoculated indicator plant species or cultivars and serology (DAS‐ELISA). The study revealed the occurrence of Brome mosaic virus (BMV), Barley stripe mosaic virus (BSMV), Barley yellow dwarf virus and its strains (BYDV‐PAV and RPV), Soil‐borne wheat mosaic virus (SBWMV), Wheat dwarf virus (WDV), Wheat streak mosaic virus (WSMV) and Wheat spindle streak mosaic virus (WSSMV). DSA‐ELISA tests confirmed these identifications. The prevalence of viruses varied annually and from field to field. BSMV, BYDV‐PAV, SBWMV, WDV, WSMV and WSSMV were found to be the most prevalent viruses. Viruses generally occurred in mixed infections of 3–6 viruses and the most common virus complex consisted of 4 viruses (50%), viz. BYDV, SBWMV, WDV and WSSMV. Five‐ and six‐virus complexes were relatively less common (20% each) whereas 3‐virus complex was noticed in only 10% cases. SBWMV and WSSMV have been found to be new to Africa and Zambia and are reportedly vectored by a fungal protist –Polymyxa graminis. BYDV strains MAV and SGV were also tested but gave negative results against their antisera.
Determination of the fatigue fracture planes of Co–Cr–Mo biomedical alloys using electron backscatter diffraction
Authors: WANG S. C. , BROWNE M. , UBHI H. S. , STARINK M. J.
Published: January 2005

Electron backscatter diffraction on a scanning electron microscope has been utilized to acquire crystal orientation information around faceted fatigue cracks in a Co–Cr–Mo alloy for medical implants. The faceted fracture planes are unambiguously determined as {111} planes.
Microstructural characterization of autogenous laser welds on 316L stainless steel using EBSD and EDS
Authors: KELL J. , TYRER J. R. , HIGGINSON R. L. , THOMSON R. C.
Published: January 2005

This research is concerned with autogenous welding of 316L stainless steel and the microstructure generated by such a process. Autogenous welding does not require a filler material and in this case relies on an initial shallow melt phase to maintain a conduction limited weld. Essentially, a high power laser beam traverses the substrate, with the beam shaped by conventional optics, which produces a Gaussian irradiance distribution; or with a diffractive optical element, used to produce a uniform irradiance distribution.

Initial results have shown that due to the nature of the heating cycle, complex microstructures are developed. These fine, complicated microstructures cannot be satisfactorily resolved and quantified using standard optical microscopy techniques. Electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) have been carried out on a number of different microstructures prepared using a range of welding parameters. It is demonstrated that the simultaneous determination of the chemistry and crystallography is a very useful tool for rapid identification of the different phases formed on solidification as a consequence of varying welding procedures.
A truncated H‐NS‐like protein from enteropathogenic Escherichia coli acts as an H‐NS antagonist
Authors: Williamson Helen S. , Free Andrew
Published: January 2005

The H‐NS nucleoid‐associated protein of Escherichia coli is the founder member of a widespread family of gene regulatory proteins which have a bipartite structure, consisting of an N‐terminal coiled‐coil oligomerization domain and a C‐terminal DNA‐binding domain. Here we characterize a family of naturally occurring truncated H‐NS derivatives lacking the DNA‐binding domain, which we term the H‐NST family. H‐NST proteins are found in large genomic islands in pathogenic E. coli strains, which are absent from the corresponding positions in the E. coli K‐12 genome. Detailed analysis of the H‐NST proteins from enteropathogenic E. coli (EPEC) and uropathogenic E. coli (UPEC) shows that the EPEC protein (H‐NSTEPEC) has a potent anti‐H‐NS function at the classical H‐NS‐repressed operon proU. This correlates with the ability of H‐NSTEPEC to co‐purify with H‐NS in vitro, and can be abolished by a mutation of leucine 30 to proline which is predicted to prevent the N‐terminal region from forming a coiled‐coil structure. In contrast, despite being 90% identical to H‐NSTEPEC at the protein level, the UPEC homologue (H‐NSTUPEC) has only a weak anti‐H‐NS activity, correlating with a much‐reduced ability to interact with H‐NS during column chromatography. A single amino acid difference at residue 16 appears to account for these different properties. The hnsTEPEC gene is transcribed monocistronically and expressed throughout the exponential growth phase in DMEM medium. Our data suggest that a truncated derivative of H‐NS encoded by an ancestral mobile DNA element can interact with the endogenous H‐NS regulatory network of a bacterial pathogen.
Regulation of the hetero‐octameric ATP phosphoribosyl transferase complex from Thermotoga maritima by a tRNA synthetase‐like subunit
Authors: Vega M. Cristina , Zou Peijian , Fernandez Francisco J. , Murphy Gavin E. , Sterner Reinhard , Popov Alexander , Wilmanns Matthias
Published: January 2005

The molecular structure of the ATP phosphoribosyl transferase from the hyperthermophile Thermotoga maritima is composed of a 220 kDa hetero‐octameric complex comprising four catalytic subunits (HisGS) and four regulatory subunits (HisZ). Steady‐state kinetics indicate that only the complete octameric complex is active and non‐competitively inhibited by the pathway product histidine. The rationale for these findings is provided by the crystal structure revealing a total of eight histidine binding sites that are located within each of the four HisGS–HisZ subunit interfaces formed by the ATP phosphoribosyl transferase complex. While the structure of the catalytic HisGS subunit is related to the catalytic domain of another family of (HisGL)2 ATP phosphoribosyl transferases that is functional in the absence of additional regulatory subunits, the structure of the regulatory HisZ subunit is distantly related to class II aminoacyl‐tRNA synthetases. However, neither the mode of the oligomeric subunit arrangement nor the type of histidine binding pockets is found in these structural relatives. Common ancestry of the regulatory HisZ subunit and class II aminoacyl‐tRNA synthetase may reflect the balanced need of regulated amounts of a cognate amino acid (histidine) in the translation apparatus, ultimately linking amino acid biosynthesis and protein biosynthesis in terms of function, structure and evolution.
The tale of two RNA polymerases: transcription profiling and gene expression strategy of bacteriophage Xp10
Authors: Semenova Ekaterina , Djordjevic Marko , Shraiman Boris , Severinov Konstantin
Published: January 2005

Bacteriophage Xp10 infects rice pathogen Xanthomonas oryzae. Xp10 encodes its own single‐subunit RNA polymerase (RNAP), similar to that found in phages of the T7 family. On the other hand, most of Xp10 genes are organized in a manner typical of lambdoid phages that are known to rely only on host RNAP for their development. To better understand the temporal pattern of viral transcription during Xp10 development, we performed global transcription profiling, primer extension, chemical kinetic modelling and bioinformatic analyses of Xp10 gene expression. Our results indicate that true to its mosaic nature, Xp10 relies on both host and viral RNAPs for expression of genes coding for virion components and host lysis. The joint transcription of the same set of genes by two types of RNA polymerases is unprecedented for a bacteriophage. Curiously, such a situation is realized in chloroplasts.
Diversity and differentiation in two populations of Gibberella circinata in South Africa
Authors: Britz H. , Coutinho T. A. , Wingfield B. D. , Marasas W. F. O. , Wingfield M. J.
Published: January 2005

Gibberella circinata[anamorph Fusarium circinatum (= F. subglutinans f.sp. pini)] causes pitch canker and is an important pathogen in South African pine nurseries. The initial outbreak of the pitch canker fungus was limited to a single nursery at Ngodwana in Mpumalanga Province. Subsequently, several other pine nurseries in South Africa became infected. Most of these outbreaks were relatively small except for the outbreak in the Klipkraal nursery (Mpumalanga Province). The genetic diversity, population differentiation and relative frequencies of the sexual and asexual cycles among two South African subpopulations were determined to establish whether immigration, mutation and/or recombination contributed towards population structure. The allelic diversity of the initial population (Ngodwana) was observed to be lower (0·16) than that of the more recent Klipkraal population (0·25). Approximately 4% (GST = 0·04) of total gene diversity could be attributed to differences among the subpopulations. Furthermore, six new vegetative compatibility groups (VCGs) have been identified since the initial outbreak of G. circinata in South Africa 10 years ago. The relatively low allelic diversity and low level of genetic differentiation suggest restricted gene flow among subpopulations, and indicate that the pathogen has been introduced recently. However, the amount of allelic and VCG diversity suggests that multiple genotypes have been introduced into South Africa. The increases in effective population number, allelic diversity and new VCGs over the past 10 years suggest that sexual reproduction might be occurring.
Detection of a tomato strain of Parietaria mottle virus (PMoV‐T) by molecular hybridization and RT‐PCR in field samples from north‐eastern Spain
Authors: Galipienso L. , Herranz M. C. , Pallás V. , Aramburu J.
Published: January 2005

Parietaria mottle virus (PMoV‐T) infecting tomatoes from different commercial fields in Catalonia, Spain was detected by dot‐blot and tissue‐printing hybridization and one‐step reverse transcriptase PCR (RT‐PCR). Specific cDNA was amplified by RT‐PCR from mechanically infected Chenopodium quinoa plants and cloned into a plasmid vector. A digoxigenin‐labelled riboprobe was synthesized for molecular hybridization, and a specific set of primers (PMoV‐1F/PMoV‐1R) were designed for one‐step RT‐PCR assays. Material from different parts of PMoV‐T‐infected tomato plants was used for the analysis. The virus was detected on necrotic apical shoots, fruits with symptoms, and symptomless shoots grown from old necrotic branches, but not on the old necrotic branches themselves. Both molecular hybridization and one‐step RT‐PCR procedures were highly specific, and no cross‐reactions were observed with other related ilarviruses. PMoV‐T was detected successfully by molecular techniques on all infected tomato plants collected from commercial fields, although one‐step RT‐PCR was less robust than molecular hybridization. The observed reliability of tissue‐printing hybridization could greatly facilitate both the large‐scale analysis and epidemiological studies of this important pathogen.
Genetic variation in Candidatus Phytoplasma australiense
Authors: Streten C. , Gibb K. S.
Published: January 2005

This study examined whether genes that are less conserved than the 16S rRNA gene can distinguish Candidatus Phytoplasma australiense strains that are identical based on their 16S rRNA genes, with a view to providing insight into their origins and distribution, and any patterns of association with particular plant hosts. Sequence analysis of the tuf gene and rp operon showed that Ca. P. australiense strains could be differentiated into four subgroups, named 16SrXII‐B (tuf‐Australia I; rp‐A), 16SrXII‐B (tuf‐New Zealand I; rp‐B), 16SrXII‐B (tuf‐New Zealand II) and 16SrXII‐B (rp‐C). Strawberry lethal yellows 1, strawberry green petal, Australian grapevine yellows, pumpkin yellow leaf curl and cottonbush witches’ broom phytoplasmas were designated members of the 16SrXII‐B (tuf‐Australia I; rp‐A) subgroup. The strawberry lethal yellows 2 and cottonbush reduced yellow leaves phytoplasmas were assigned to the 16SrXII (tuf‐New Zealand II; rp‐B) subgroup. No relationship was observed between these phytoplasma subgroups and collection date, location or host plant. However, the study revealed evolutionary divergence in the 16SrXII group.
A combined agar‐absorption and BIO‐PCR assay for rapid, sensitive detection of Xylella fastidiosa in grape and citrus
Authors: Fatmi M. , Damsteegt V. D. , Schaad N. W.
Published: January 2005

Application of the polymerase chain reaction (PCR) to disease diagnosis is limited in part by the presence of PCR inhibitors. Inhibition can be overcome and sensitivity increased by culturing bacteria on agar media prior to PCR (termed BIO‐PCR). However, Xylella fastidiosa grows slowly, requiring 10–14 days for visible colonies to appear. In this study an agar‐absorption BIO‐PCR method for detecting X. fastidiosa in grape and citrus plants was developed. Optimum lengths of time for absorption of inhibitors by the agar medium or enrichment of bacteria on the medium were determined for Pierce's disease of grape and citrus variegated chlorosis. When petioles of grape and citrus leaves with symptoms were spotted onto agar media, the spots washed after various time intervals and assayed for X. fastidiosa by real‐time PCR, 97% (31 out of 32) and 100% (six out of six) of spots were positive after 2 days and 4 h for grape and citrus, respectively. With direct PCR, only 12·5% (four out of 32) and 33% (two out of six) of spots were positive, respectively, and visible X. fastidiosa colonies were evident after 10 and 14 days, respectively. In a separate experiment with samples from a different vineyard, 46% (13 out of 28) of the grape samples (agar spots) were positive after 1 day and 93% (26 out of 28) after 5 days using agar‐absorption PCR. In contrast, all samples were negative by direct PCR. Viable X. fastidiosa were recovered from all samples after 14 days. Further tests with eight randomly selected grape petioles from three Texas vineyards known to have Pierce's disease resulted in 50% being positive by a simple 24 h agar‐absorption PCR assay, whereas none was positive by direct PCR. Overall, 10 out of 16 (63%) vines from five vineyards (two in California and three in Texas) were positive after the 24 h agar‐absorption PCR assay. In contrast, only one vine was positive by direct PCR. This simple agar absorption‐based PCR assay protocol should prove useful for the routine detection of X. fastidiosa and other slow‐growing bacteria in the presence of PCR inhibitors.
Morphological and molecular characterization of the sudden‐death syndrome pathogen of soybean in Brazil
Authors: Arruda G. M. T. , Miller R. N. G. , Ferreira M. A. S. V. , Café‐Filho A. C.
Published: January 2005

Brazilian Fusarium isolates causing soybean sudden death syndrome (SDS) were characterized by comparing them with other Fusarium isolates associated with soybean root rot, as well as F. solani f.sp. glycines isolates associated with the disease in the USA, using molecular (mitochondrial and nuclear rDNA), morphological, cultural and pathogenic characteristics. On the basis of pathogenicity data, and restriction fragment length polymorphism and sequence analysis of the rDNA internal transcribed spacer (ITS) regions, isolates formed a group distinct from nonSDS F. solani isolates, as well as other Fusarium species. ITS sequence analysis also revealed that Brazilian isolates were distinct from the majority of SDS pathogens from the USA (Fusarium virguliforme) and conformed to Fusarium tucumaniae.
MODALITES DE LA DIFFERENCIATION DES CARACTERES SEXUELS SOMATIQUES DE NEREIDIENS (ANNELIDES POLYCHETES)
Authors: BOILLY‐MARER YOLANDE
Published: January 2005

The influence of the age, of the fast and of the temperature with the differentiation of sexual somatic characters has been studied in some Nereids. The sexual somatic characters can be differentiated in Nereis of any age if the cerebral endocrine inhibition of the heteronereidation is suppressed. The supranormal temperatures release prematurely and accelerate the process of the differentiation of these characters; the low temperatures moderate these phenomena without preventing their apparition. The fast do not influence the differentiation of the somatic sexual characters.
MORPHOGENETIC SUBSTANCES FOUND IN THE EMBRYOS OF SEA URCHIN, WITH SPECIAL REFERENCE TO THE ANTI‐VEGETALIZING SUBSTANCE
Authors: FUJIWARA AKIKO , YASUMASU IKUO
Published: January 2005

When sea urchin embryos up to the 2‐cell stage are treated with 5 × 10−3 M chloramphenicol for a short period, small blastulae filled with mesenchyme‐like cells (type A) are formed. If a homogenate of the embryos up to the 2‐cell stage is introduced just after the chloramphenicol treatment, almost all embryos developed to normal plutei. Chloramphenicol treatment, started at the 8 ∽ 32‐cell stages, induces vegetalized larvae (type B), and presumptive vegetalized ones develop normally after treatment with a homogenate of the embryos at the 16 ∽ 64‐cell stages. If embryos are treated in the same manner at 7 hr after insemination, abnormal embryos which seem to be bipolar ones (type C) are observed at 40 hr after the treatment. These also develop normally, if a homogenate of embryos at the stages from unfertilized egg to gastrula is added to them at the end of the chloramphenicol treatment. The substances having these activities are named morphogenetic substances α, β and γ, respectively. The morphogenetic substance β (anti‐vegetalizing substance) is heat stable and its molecular weight is less than 10,000.
DIRECT ISOLATION OF NATIVE THIN FILAMENTS FROM EMBRYONIC MUSCLE CELLS*
Authors: OBINATA TAKASHI , HAYASHI IZUMI , FISCHMAN DONALD A.
Published: January 2005

A method is presented for the release of “native” thin filaments from 13‐day old embryonic chick muscle without tryptic digestion or desoxycholate (DOC) solubilization of Z bands. The isolated filaments were 50–60 Å in diameter, of variable length, and formed “arrowhead‐like” complexes with heavy meromyosin (HMM). In addition, the filaments interacted with purified myosin to form actomyosin as effectively as action extracted from an acetone powder of muscle. The Mg++‐dependent ATPase activity and extent of superprecipitation of the synthetic actomyosin required a low concentration of Ca++, strongly suggesting the presence of troponin and tropomyosin on the thin filaments isolated from muscle at this stage of embryogenesis. The native thin filaments were more sensitive to trypsin than synthetic F‐actin prepared from an acetone powder based on measurements of flow birefrengence, viscosity and the ability to activate myosin ATPase.