bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suberin lamella development in maize seedling roots grown in aerated and stagnant conditions
Authors: ENSTONE DARYL E. , PETERSON CAROL A. 
Published: March 2005

ABSTRACTHypoxia can stimulate the development of a suberized exodermis in aquatic plants; however, its influence on this aspect of terrestrial root development is sparsely documented. To determine the effects of hypoxia on maize (Zea mays cv. Seneca Horizon) roots, seedlings were grown in vermiculite (VERM), aerated hydroponics (AER), stagnant hydroponics with agar (STAG), or aerated hydroponics with agar (AERAG). The endo‐ and exodermis were examined for wall modifications. Lateral root emergence and aerenchyma formation were documented qualitatively. The endodermal Casparian band formation was unaffected by treatment. Endodermal and exodermal suberin lamella formation was earliest and most extensive in VERM. Suberization, especially in the exodermis of aerated treatments, was depressed in all hydroponic media. In comparison with AER, STAG exodermal lamellae were increased, but endodermal lamellae were decreased. Since the suberized exodermis forms a barrier to radial oxygen loss from roots to the medium, its stimulation in STAG roots (which also developed extensive aerenchyma) would help retain oxygen in the root. The reduction of endodermal lamellae should facilitate oxygen diffusion into the stele. Clearly, the response to environmental conditions is variable within individual cortical cell layers. Additionally, the observed patterns of lamellae, aerenchyma and lateral root development indicate a tight radial co‐ordination of root development.
Metabolic responses to oral tryptophan supplementation before exercise in horses
Authors: Vervuert I. , Coenen M. , Watermülder E. 
Published: March 2005

SummaryThis study was conducted to evaluate the effects of oral tryptophan (Trp) supplementation on exercise capacity and metabolic responses in horses. Three horses had to perform an exercise test: a 15‐min warm‐up followed by a 60‐min walk (1.7 m/s, W1), a 10‐min trot (3.1 m/s, T1), a second 60‐min walk (1.7 m/s, W2), a second 10‐min trot (3.1 m/s, T2) and a final 30‐min walk (1.7 m/s, W3) until the horses were unwilling to continue. The horses exercised on a treadmill at a 6% incline and with a constant draught load of 40 kg (0.44 kN). Two hours before exercise horses were given 50 g Trp (9.8–10.7 g Trp/100 kg BW) by nasogastric tube. A control exercise test was conducted without Trp. During the control test, one horse was able to finish the final 30‐min walk (W3), whereas two horses finished W3 after Trp administration. Higher plasma Trp levels after Trp administration did not change significantly during exercise (Trp: start exercise, 524 ± 41 μmol/l; end exercise 547 ± 20 μmol/l; control: start exercise, 70 ± 10 μmol/l; end exercise, 58 ± 21 μmol/l). After Trp supplementation, blood lactate concentrations were significantly lower after the first and second trotting periods. Free fatty acids in plasma increased during exercise without any treatment‐related differences. Although experimental plasma Trp levels were seven times higher than the control levels, Trp supplementation had no effect on exercise performance and metabolic responses to draught load exercise.
Digestibility rates of major and trace elements in pancreatic duct‐ligated pigs
Authors: Kammlott E. , Karthoff J. , Stemme K. , Gregory P. , Kamphues J. 
Published: March 2005

SummaryLigation of pancreatic duct in pigs leads to a severe maldigestion of calcium and magnesium. Substitution of missing enzymes results in a ‘normalization’ of the digestibility rates of these elements. In comparison to controls the pre‐caecal phosphorus digestibility decreased, but the total digestibility rates increased, after ligation of the pancreatic duct. Furthermore, the total amount of absorbed phosphorus was significantly higher in pancreatic duct ligated pigs. Further studies have to be carried out to investigate, whether phosphorus in exocrine pancreatic insufficiency is excreted with urine, as in this study the observed Ca:P‐ratio in blood was in a physiological range. Without a forced renal excretion of phosphorus, consequences and risks (e.g. secondary hyperparathyroidism) of the regulation have to be considered. Regarding the elements sodium, potassium and chloride, an increased faecal excretion could be observed in pancreatic duct ligated pigs. As a substitution with enzyme products led to digestibility rates similar to those in controls, no losses of electrolytes have to be feared. Even though pancreatic juice seems to have influences on the digestibility of investigated trace elements (copper, zinc, iron and manganese), it did not lead to severe imbalances in the corresponding mineral metabolism.
Characterization of Maize Iranian Mosaic Virus and Comparison with Hawaiian and Other Isolates of Maize Mosaic Virus (Rhabdoviridae)
Authors: Ammar E.‐D. , Gomez‐Luengo R. G. , Gordon D. T. , Hogenhout S. A. 
Published: March 2005

AbstractMaize Iranian mosaic virus (MIMV) was characterized and compared with isolates of Maize mosaic virus (MMV, genus Nucleorhabdovirus, family Rhabdoviridae) in insect transmission, cytopathology and ultrastructure of infected maize cells, virion proteins and serologically. MIMV is naturally transmitted by Ribautodelphax notabilis, a delphacid planthopper, in Iran. In this study, another planthopper, Peregrinus maidis, vector of MMV, transmitted MIMV with an estimated efficiency of 0.4–1.6% following feeding on MIMV‐infected maize plants and 64% following injection of MIMV into the hemolymph, suggesting that P. maidis gut tissues largely blocked MIMV transmission. MIMV and MMV‐HI (Hawaii) induced similar cytopathologies in cells of infected maize leaves, with virions budding through inner nuclear and endoplasmic reticulum membranes. In thin sections, virions of MIMV were significantly shorter than those of MMV‐HI. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis of virions of MIMV, MMV‐HI, MMV‐CR (Costa Rica) and MMV‐FL (Florida) yielded six proteins of which four were identified as the putative G, N, P and M proteins of plant rhabdoviruses. The N, P and M proteins of MIMV migrated faster in gels than those of the MMV isolates indicating a lower molecular weight, whereas the bands corresponding to the G proteins migrated similarly for both viruses. Polyclonal antibodies to MMV‐HI failed to react with virions of MIMV in enzyme‐linked immunosorbent assay (ELISA) and with MIMV proteins in Western blots. In contrast, these antibodies reacted strongly with MMV‐HI and MMV‐FL virions in ELISA and with MMV‐HI, MMV‐CR and MMV‐FL proteins in Western blots. Further, in ELISA, polyclonal antibodies to MMV‐MR (Mauritius) reacted weakly with MIMV virions but strongly with MMV‐HI and MMV‐FL virions. Thus, it is concluded that MIMV is a new virus of the Nucleorhabdovirus genus that may be distantly related to MMV.
Detection of Races 1 and 2 of Fusarium solani f. sp. cucurbitae and their Distribution in Watermelon Fields in Tunisia
Authors: Boughalleb N. , Armengol J. , El Mahjoub M. 
Published: March 2005

AbstractA crown, foot and fruit rot of watermelon has been observed in most of the watermelon production areas in Tunisia. A survey conducted from 2000 to 2001 allowed the isolation of 291 isolates which were identified as Fusarium solani. These isolates were identified as F. solani f. sp. cucurbitae (Fsc) and races 1 and 2 characterized on the basis of pathogenicity tests on watermelon seedlings and muskmelon fruits. These results were confirmed by counts of the number of septa in the macroconidia. About 271 isolates were identified as Fsc race 1, 12 isolates were identified as Fsc race 2 and eight isolates were not pathogenic. Race 1 is widely distributed in watermelon production areas in Tunisia and race 2 has a lower incidence but it is present in the north, the middle and southern Tunisian watermelon cropping areas. Additionally, a study to compare the virulence of 122 isolates of Fsc race 1 showed different degrees of virulence among them. This is the first report of Fsc races 1 and 2 in Tunisia.
Expression of P‐cadherin distinct from that of E‐cadherin in re‐epithelialization in neonatal rat skin
Authors: Koizumi Michiko , Matsuzaki Takashi , Ihara Setsunosuke 
Published: March 2005

Our previous study showed that an open wound made in neonatal rat skin was covered by migration of certain undifferentiated populations of keratinocytes as a multilayered cell sheet. In this study, the expression of the components of adherens junctions (AJ), E‐ and P‐cadherins, and beta‐catenin, was examined to understand the underlying mechanisms. Both E‐ and P‐cadherins were downregulated in the basal layer at 6 h post‐wounding (PW), indicating a reduction in the intercellular adhesiveness. The expression of P‐cadherin but not E‐cadherin was expanded to the suprabasal layers at the wound margin at 12 h PW. Moreover, the expression pattern of P‐cadherin at sites of cell–cell contact was punctate rather than linear. By 24 h PW, cells accumulated beta‐catenin in the cytoplasm in a suprabasal layer contacting the basal layer at the wound margin. Both the E‐ and P‐cadherins showed a punctate AJ pattern at the confined suprabasal layer. Such differential expression of the E‐ and P‐cadherins strongly suggests that these two classic cadherins play distinct roles in re‐epithelialization. The changing of the E‐ and/or P‐cadherin expression may participate in a delay of terminal differentiation of keratinocytes for cell supply toward a wound.
The United States and the Control of World Oil
Authors: Bromley Simon 
Published: March 2005

AbstractTo what extent is a drive to appropriate the world's oil a driving force behind American foreign policy? This paper argues that rather than viewing US foreign policy as driven by the expansionary forces of US oil companies seeking new reserves and markets, or by rising concern about levels of import dependence, it is more illuminating to ask how the broader nature of American geopolitics shapes policies towards international oil. The United States does seek to exercise a degree of influence over world oil second to none, but the form of that influence is very ambiguous and very different from the kinds of control over raw materials traditionally associated with imperial powers.
Polymorphisms of the upstream regulatory region of the major histocompatibility complex DRB genes in domestic horses
Authors: Díaz S. , Giovambattista G. , Peral‐García P. 
Published: March 2005

SummarySequence information was obtained on the variation of the ELA‐DRB upstream regulatory region (URR) after polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP) cloning and sequencing of ≈ 220 bp upstream of the first exon of horse DRB genes. The sequence of the proximal URR of equine DRB is composed of highly conserved sequence motifs, showing the presence of the W, X, Y, CAAT and TATA conserved boxes of major histocompatibility complex (MHC) class II promoters. Five different polymorphic horse DRB promoter sequences were detected in five horse breeds. The results demonstrate the existence of polymorphism in the nucleotide sequences of the ELA‐DRB URR, located in the functionally important conserved consensus sequences, the X2 box, the Y box and the TATA box, while conservation were observed in X1 and CAAT boxes. The nucleotide diversity among horse URRs was intermediate between that seen within human and mouse DRB promoters, suggesting the existence of another important source of variability in ELA‐DRB genes. In addition, phylogenetic comparisons, identity analysis and sequence organization suggested that the reported sequences would correspond to an expressed ELA‐DRB locus. However, further information about the functional significance of these promoter polymorphisms will probably be acquired through expression studies on the different sequences.
Heterogeneity of a Fluorescent Tegument Component in Single Pseudorabies Virus Virions and Enveloped Axonal Assemblies
Authors: del Rio T. , Ch'ng T. H. , Flood E. A. , Gross S. P. , Enquist L. W. 
Published: March 2005

ABSTRACT
The molecular mechanisms responsible for long-distance, directional spread of alphaherpesvirus infections via axons of infected neurons are poorly understood. We describe the use of red and green fluorescent protein (GFP) fusions to capsid and tegument components, respectively, to visualize purified, single extracellular virions and axonal assemblies after pseudorabies virus (PRV) infection of cultured neurons. We observed heterogeneity in GFP fluorescence when GFP was fused to the tegument component VP22 in both single extracellular virions and discrete puncta in infected axons. This heterogeneity was observed in the presence or absence of a capsid structure detected by a fusion of monomeric red fluorescent protein to VP26. The similarity of the heterogeneous distribution of these fluorescent protein fusions in both purified virions and in axons suggested that tegument-capsid assembly and axonal targeting of viral components are linked. One possibility was that the assembly of extracellular and axonal particles containing the dually fluorescent fusion proteins occurred by the same process in the cell body. We tested this hypothesis by treating infected cultured neurons with brefeldin A, a potent inhibitor of herpesvirus maturation and secretion. Brefeldin A treatment disrupted the neuronal secretory pathway, affected fluorescent capsid and tegument transport in the cell body, and blocked subsequent entry into axons of capsid and tegument proteins. Electron microscopy demonstrated that in the absence of brefeldin A treatment, enveloped capsids entered axons, but in the presence of the inhibitor, unenveloped capsids accumulated in the cell body. These results support an assembly process in which PRV capsids acquire a membrane in the cell body prior to axonal entry and subsequent transport.
The Minor Capsid Protein L2 Contributes to Two Steps in the Human Papillomavirus Type 31 Life Cycle
Authors: Holmgren Sigrid C. , Patterson Nicole A. , Ozbun Michelle A. , Lambert Paul F. 
Published: March 2005

ABSTRACT
Prior studies, which have relied upon the use of pseudovirions generated in heterologous cell types, have led to sometimes conflicting conclusions regarding the role of the minor capsid protein of papillomaviruses, L2, in the viral life cycle. In this study we carry out analyses with true virus particles assembled in the natural host cell to assess L2's role in the viral infectious life cycle. For these studies we used the organotypic (raft) culture system to recapitulate the full viral life cycle of the high-risk human papillomavirus HPV31, which was either wild type or mutant for L2. After transfection, the L2 mutant HPV31 genome was able to establish itself as a nuclear plasmid in proliferating populations of poorly differentiated (basal-like) human keratinocytes and to amplify its genome to high copy number, support late viral gene expression, and cause formation of virus particles in human keratinocytes that had been induced to undergo terminal differentiation. These results indicate that aspects of both the nonproductive and productive phases of the viral life cycle occur normally in the absence of functional L2. However, upon the analysis of the virus particles generated, we found an approximate 10-fold reduction in the amount of viral DNA encapsidated into L2-deficient virions. Furthermore, there was an over-100-fold reduction in the infectivity of L2-deficient virus. Because the latter deficiency cannot be accounted for solely by the 10-fold decrease in encapsidation, we conclude that L2 contributes to at least two steps in the production of infectious virus.
Circumventing Tolerance to the Prion Protein (PrP): Vaccination with PrP-Displaying Retrovirus Particles Induces Humoral Immune Responses against the Native Form of Cellular PrP
Authors: Nikles Daphne , Bach Patricia , Boller Klaus , Merten Christoph A. , Montrasio Fabio , Heppner Frank L. , Aguzzi Adriano , Cichutek Klaus , Kalinke Ulrich , Buchholz Christian J. 
Published: March 2005

ABSTRACT

Passive immunization with antibodies directed against the cellular form of the prion protein (PrP
C
) can protect against prion disease. However, active immunization with recombinant prion protein has so far failed to induce antibodies directed against native PrP
C
expressed on the cell surface. To develop an antiprion vaccine, a retroviral display system presenting either the full-length mouse PrP (PrP209) or the C-terminal 111 amino acids (PrP111) fused to the transmembrane domain of the platelet-derived growth factor receptor was established. Western blot analysis and immunogold electron microscopy of the retroviral display particles revealed successful incorporation of the fusion proteins into the particle membrane. Interestingly, retroviral particles displaying PrP111 (PrP
D111
retroparticles) showed higher incorporation efficiencies than those displaying PrP209. Already 7 days after intravenous injection of PrP
D111
retroparticles, PrP
C
-deficient mice (
Prnp
o/o
) showed high immunoglobulin M (IgM) and IgG titers specifically binding the native PrP
C
molecule as expressed on the surface of T cells isolated from PrP
C
-overexpressing transgenic mice. More importantly, heterozygous
Prnp
+/o
mice and also wild-type mice showed PrP
C
-specific IgM and IgG antibodies upon vaccination with PrP
D111
retroparticles, albeit at considerably lower levels. Bacterially expressed recombinant PrP, in contrast, was unable to evoke IgG antibodies recognizing native PrP
C
in wild-type mice. Thus, our data show that PrP or parts thereof can be functionally displayed on retroviral particles and that immunization with PrP retroparticles may serve as a novel promising strategy for vaccination against transmissible spongiform encephalitis.
Role of Receptor-Mediated Endocytosis in the Formation of Vaccinia Virus Extracellular Enveloped Particles
Authors: Husain Matloob , Moss Bernard 
Published: March 2005

ABSTRACT
Infectious intracellular mature vaccinia virus particles are wrapped by cisternae, which may arise from trans-Golgi or early endosomal membranes, and are transported along microtubules to the plasma membrane where exocytosis occurs. We used EH21, a dominant-negative form of Eps15 that is an essential component of clathrin-coated pits, to investigate the extent and importance of endocytosis of viral envelope proteins from the cell surface. Several recombinant vaccinia viruses that inducibly or constitutively express an enhanced green fluorescent protein (GFP)-EH21 fusion protein were constructed. Expression of GFP-EH21 blocked uptake of transferrin, a marker for clathrin-mediated endocytosis, as well as association of adaptor protein-2 with clathrin-coated pits. When GFP-EH21 was expressed, there were increased amounts of viral envelope proteins, including A33, A36, B5, and F13, in the plasma membrane, and their internalization was inhibited. Wrapping of virions appeared to be qualitatively unaffected as judged by electron microscopy, a finding consistent with a primary trans-Golgi origin of the cisternae. However, GFP-EH21 expression caused a 50% reduction in released enveloped virions, decreased formation of satellite plaques, and delayed virus spread, indicating an important role for receptor-mediated endocytosis. Due to dynamic interconnection between endocytic and exocytic pathways, viral proteins recovered from the plasma membrane could be used by trans-Golgi or endosomal cisternae to form new viral envelopes. Adherence of enveloped virions to unrecycled viral proteins on the cell surface may also contribute to decreased virus release in the presence of GFP-EH21. In addition to a salvage function, the retrieval of viral proteins from the cell surface may reduce immune recognition.
Isolation and Characterization of Avian Influenza Viruses, Including Highly Pathogenic H5N1, from Poultry in Live Bird Markets in Hanoi, Vietnam, in 2001
Authors: Nguyen Doan C. , Uyeki Timothy M. , Jadhao Samadhan , Maines Taronna , Shaw Michael , Matsuoka Yumiko , Smith Catherine , Rowe Thomas , Lu Xiuhua , Hall Henrietta , Xu Xiyan , Balish Amanda , Klimov Alexander , Tumpey Terrence M. , Swayne David E. , Huynh Lien P. T. , Nghiem Ha K. , Nguyen Hanh H. T. , Hoang Long T. , Cox Nancy J. , Katz Jacqueline M. 
Published: March 2005

ABSTRACT

Since 1997, outbreaks of highly pathogenic (HP) H5N1 and circulation of H9N2 viruses among domestic poultry in Asia have posed a threat to public health. To better understand the extent of transmission of avian influenza viruses (AIV) to humans in Asia, we conducted a cross-sectional virologic study in live bird markets (LBM) in Hanoi, Vietnam, in October 2001. Specimens from 189 birds and 18 environmental samples were collected at 10 LBM. Four influenza A viruses of the H4N6 (
n
= 1), H5N2 (
n
= 1), and H9N3 (
n
= 2) subtypes were isolated from healthy ducks for an isolation frequency of over 30% from this species. Two H5N1 viruses were isolated from healthy geese. The hemagglutinin (HA) genes of these H5N1 viruses possessed multiple basic amino acid motifs at the cleavage site, were HP for experimentally infected chickens, and were thus characterized as HP AIV. These HA genes shared high amino acid identities with genes of other H5N1 viruses isolated in Asia during this period, but they were genetically distinct from those of H5N1 viruses isolated from poultry and humans in Vietnam during the early 2004 outbreaks. These viruses were not highly virulent for experimentally infected ducks, mice, or ferrets. These results establish that HP H5N1 viruses with properties similar to viruses isolated in Hong Kong and mainland China circulated in Vietnam as early as 2001, suggest a common source for H5N1 viruses circulating in these Asian countries, and provide a framework to better understand the recent widespread emergence of HP H5N1 viruses in Asia.
Amino Acid Preferences for a Critical Substrate Binding Subsite of Retroviral Proteases in Type 1 Cleavage Sites
Authors: Bagossi Péter , Sperka Tamás , Fehér Anita , Kádas János , Zahuczky Gábor , Miklóssy Gabriella , Boross Péter , Tözsér József 
Published: March 2005

ABSTRACT

The specificities of the proteases of 11 retroviruses representing each of the seven genera of the family
Retroviridae
were studied using a series of oligopeptides with amino acid substitutions in the P2 position of a naturally occurring type 1 cleavage site (Val-Ser-Gln-Asn-Tyr↓Pro-Ile-Val-Gln; the arrow indicates the site of cleavage) in human immunodeficiency virus type 1 (HIV-1). This position was previously found to be one of the most critical in determining the substrate specificity differences of retroviral proteases. Specificities at this position were compared for HIV-1, HIV-2, equine infectious anemia virus, avian myeloblastosis virus, Mason-Pfizer monkey virus, mouse mammary tumor virus, Moloney murine leukemia virus, human T-cell leukemia virus type 1, bovine leukemia virus, human foamy virus, and walleye dermal sarcoma virus proteases. Three types of P2 preferences were observed: a subgroup of proteases preferred small hydrophobic side chains (Ala and Cys), and another subgroup preferred large hydrophobic residues (Ile and Leu), while the protease of HIV-1 preferred an Asn residue. The specificity distinctions among the proteases correlated well with the phylogenetic tree of retroviruses prepared solely based on the protease sequences. Molecular models for all of the proteases studied were built, and they were used to interpret the results. While size complementarities appear to be the main specificity-determining features of the S2 subsite of retroviral proteases, electrostatic contributions may play a role only in the case of HIV proteases. In most cases the P2 residues of naturally occurring type 1 cleavage site sequences of the studied proteases agreed well with the observed P2 preferences.