bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charged Assembly Helix Motif in Murine Leukemia Virus Capsid: an Important Region for Virus Assembly and Particle Size Determination
Authors: Cheslock Sara Rasmussen , Poon Dexter T. K. , Fu William , Rhodes Terence D. , Henderson Louis E. , Nagashima Kunio , McGrath Connor F. , Hu Wei-Shau 
Published: May 2003

ABSTRACT
We have identified a region near the C terminus of capsid (CA) of murine leukemia virus (MLV) that contains many charged residues. This motif is conserved in various lengths in most MLV-like viruses. One exception is that spleen necrosis virus (SNV) does not contain a well-defined domain of charged residues. When 33 amino acids of the MLV motif were deleted to mimic SNV CA, the resulting mutant produced drastically reduced amounts of virions and the virions were noninfectious. Furthermore, these viruses had abnormal sizes, often contained punctate structures resembling those in the cell cytoplasm, and packaged both ribosomal and viral RNA. When 11 or 15 amino acids were deleted to modify the MLV CA to resemble those from other gammaretroviruses, the deletion mutants produced virions at levels comparable to those of the wild-type virus and were able to complete one round of virus replication without detectable defects. We generated 10 more mutants that displayed either the wild-type or mutant phenotype. The distribution of the wild-type or mutant phenotype did not directly correlate with the number of amino acids deleted, suggesting that the function of the motif is determined not simply by its length but also by its structure. Structural modeling of the wild-type and mutant proteins suggested that this region forms α-helices; thus, we termed this motif the “charged assembly helix.” This is the first description of the charged assembly helix motif in MLV CA and demonstration of its role in virus budding and assembly.
Basic Residues of the Helix Six Domain of Influenza Virus M1 Involved in Nuclear Translocation of M1 Can Be Replaced by PTAP and YPDL Late Assembly Domain Motifs
Authors: Hui Eric Ka-Wai , Barman Subrata , Yang Tae Yong , Nayak Debi P. 
Published: May 2003

ABSTRACT
Influenza type A virus matrix (M1) protein possesses multiple functional motifs in the helix 6 (H6) domain (amino acids 91 to 105), including nuclear localization signal (NLS) (101-RKLKR-105) involved in translocating M1 from the cytoplasm into the nucleus. To determine the role of the NLS motif in the influenza virus life cycle, we mutated these and the neighboring sequences by site-directed mutagenesis, and influenza virus mutants were generated by reverse genetics. Our results show that infectious viruses were rescued by reverse genetics from all single alanine mutations of amino acids in the H6 domain and the neighboring region except in three positions (K104A and R105A within the NLS motif and E106A in loop 6 outside the NLS motif). Among the rescued mutant viruses, R101A and R105K exhibited reduced growth and small-plaque morphology, and all other mutant viruses showed the wild-type phenotype. On the other hand, three single mutations (K104A, K105A, and E106A) and three double mutations (R101A/K102A, K104A/K105A, and K102A/R105A) failed to generate infectious virus. Deletion (ΔYRKL) or mutation (4A) of YRKL also abolished generation of infectious virus. However, replacement of the YRKL motif with PTAP or YPDL as well as insertion of PTAP after 4A mutation yielded infectious viruses with the wild-type phenotype. Furthermore, mutant M1 proteins (R101A/K102A, ΔYRKL, 4A, PTAP, 4A+PTAP, and YPDL) when expressed alone from cloned cDNAs were only cytoplasmic, whereas the wild-type M1 expressed alone was both nuclear and cytoplasmic as expected. These results show that the nuclear translocation function provided by the positively charged residues within the NLS motif does not play a critical role in influenza virus replication. Furthermore, these sequences of H6 domain can be replaced by late (L) domain motifs and therefore may provide a function similar to that of the L domains of other negative-strand RNA and retroviruses.
A Domain in the C-Terminal Region of Latency-Associated Nuclear Antigen 1 of Kaposi's Sarcoma-Associated Herpesvirus Affects Transcriptional Activation and Binding to Nuclear Heterochromatin
Authors: Viejo-Borbolla Abel , Kati Emrah , Sheldon Julie A. , Nathan Kavita , Mattsson Karin , Szekely Laszlo , Schulz Thomas F. 
Published: May 2003

ABSTRACT
The latency-associated nuclear antigen 1 (LANA-1) of Kaposi's sarcoma-associated herpesvirus (KSHV) is required for the maintenance and replication of viral episomal DNA. The binding sites for nuclear heterochromatin and transcriptional repressor complexes are located in an amino-terminal region of LANA-1, whereas those for viral episomal DNA, p53, pRB, and members of the BRD/fsh family of nuclear proteins are located in its carboxy-terminal domain. LANA-1 activates or represses several cellular and viral promoters. In this report we show that a domain of 15 amino acids (amino acids 1129 to 1143), located close to the carboxy-terminal end of LANA-1, is required for the interaction of LANA-1 with nuclear heterochromatin or nuclear matrix, and for the ability of LANA-1 to activate the Epstein-Barr virus Cp promoter. LANA-1 proteins that are tightly associated with nuclear heterochromatin or matrix differ in molecular weight from LANA-1 proteins that can be dissociated from the nuclear matrix by high-salt buffers, suggesting that posttranslational modifications may determine the association of LANA-1 with nuclear heterochromatin or matrix.
Promyelocytic Leukemia Protein Mediates Interferon-Based Anti-Herpes Simplex Virus 1 Effects
Authors: Chee Ana V. , Lopez Pascal , Pandolfi Pier Paolo , Roizman Bernard 
Published: May 2003

ABSTRACTHerpes simplex virus (HSV) 1 disaggregates the nuclear domain 10 (ND10) nuclear structures and disperses its organizing promyelocytic leukemia protein (PML). An earlier report showed that ectopic overexpression of PML precludes the disaggregation of ND10 but has no effect on viral replication. PML has been reported to mediate the effects of interferon (IFN) and viral mutants lacking ICP0 (Δα0 mutants). To test the hypothesis that HSV disaggregates ND10 structures and disperses PML to preclude IFN-mediated antiviral effects, we tested the accumulation of viral proteins and virus yields from murine PML+/+and PML−/−cells mock treated or exposed to IFN-α, IFN-γ, or both and infected with the wild-type or Δα0 mutant virus. We report the following results. (i) The levels of growth of wild-type and mutant viruses and of accumulation of viral proteins were not significantly different in untreated PML+/+and PML−/−cells. (ii) Major effects of IFN-α and -γ were observed in PML+/+cells infected with the Δα0 mutant virus, and more minor effects were observed in cells infected with the wild-type virus. The effects of the IFNs on either wild-type or the mutant virus in PML−/−cells were minimal. (iii) The mixture of IFN-α and -γ was more effective than either IFN alone, but again, the effect was more drastic in PML+/+cells than in PML−/−cells. We concluded that the anti-HSV state induced by exogenous IFN is mediated by PML and that the virus targets the ND10 structures and disseminates PML in order to preclude the establishment of the antiviral state induced by IFNs.
Activated Notch1 Inhibits p53-Induced Apoptosis and Sustains Transformation by Human Papillomavirus Type 16 E6 and E7 Oncogenes through a PI3K-PKB/Akt-Dependent Pathway
Authors: Nair Pradip , Somasundaram Kumaravel , Krishna Sudhir 
Published: May 2003

ABSTRACT
Activated Notch1 (AcN1) alleles cooperate with oncogenes from DNA tumor viruses in transformation of epithelial cells. AcN1 signaling has pleiotropic effects, and suggested oncogenic roles include driving proliferation through cyclin D1 or the generation of resistance to apoptosis on matrix withdrawal through a phosphatidylinositol 3-kinase (PI3K)-PKB/Akt-dependent pathway. Here, we extend the antiapoptotic role for AcN1 by showing inhibition of p53-induced apoptosis and transactivation. Chemical inhibitors of the PI3K pathway block AcN1-induced inhibition of p53-dependent apoptosis and nuclear localization of Hdm2. We show that expression of wild-type p53 does not inhibit synergistic transformation by AcN1 and human papillomavirus E6 and E7 oncogenes. We suggest that activation of Notch signaling may serve as an additional mechanism to inhibit wild-type p53 function in papillomavirus-associated neoplasia.
Mutagenesis versus Inhibition in the Efficiency of Extinction of Foot-and-Mouth Disease Virus
Authors: Pariente Nonia , Airaksinen Antero , Domingo Esteban 
Published: May 2003

ABSTRACT
RNA viruses replicate near the error threshold for maintenance of genetic information, and an increase in mutation frequency during replication may drive RNA viruses to extinction in a process termed lethal mutagenesis. This report addresses the efficiency of extinction (versus escape from extinction) of foot-and-mouth disease virus (FMDV) by combinations of the mutagenic base analog 5-fluorouracil (FU) and the antiviral inhibitors guanidine hydrochloride (G) and heparin (H). Selection of G- or H-resistant, extinction-escape mutants occurred with low-fitness virus only in the absence of FU and with high-fitness virus with some mutagen-inhibitor combinations tested. The combination of FU, G, and H prevented selection of extinction-escape mutants in all cases examined, and extinction of high-fitness FMDV could not be achieved by equivalent inhibitory activity exerted by the nonmutagenic agents. The G-resistant phenotype was mapped in nonstructural protein 2C by introducing the relevant mutations in infectious cDNA clones. Decreases in FMDV infectivity were accompanied by modest decreases in the intracellular and extracellular levels of FMDV RNA, maximal intracellular concentrations of FU triphosphate, and a decrease in the intracellular concentrations of UTP. In addition to indicating a key participation of mutagenesis in virus extinction, the results suggest that picornaviruses provide versatile experimental systems to approach the problem of extinction failure associated with inhibitor-escape mutants during treatments based on enhanced mutagenesis.
transActivity of the Norovirus Camberwell Proteinase and Cleavage of the N-Terminal Protein Encoded by ORF1
Authors: Seah Ee Ling , Marshall John A. , Wright Peter J. 
Published: May 2003

ABSTRACTThe virus-encoded proteinase of Camberwell virus, a genogroup 2 norovirus, was synthesized inEscherichia coli. The purified proteinase had correct N and C termini and showedtransactivity in cell-free assays.transactivity was also demonstrated in COS cells transfected with constructs encoding either the proteinase or a proteinase-polymerase fusion. The N-terminal protein of ORF1 was cleaved in COS cells, possibly at the site E194/S.
X-RAY SPECTRAL ANALYSIS OF SU UMa TYPE DWARF NOVAE OBSERVED WITH ROSAT
Authors: GÜN GÜLNUR ÝKİS , ERCAN E. NİHAL 
Published: May 2003

X-ray spectral parameters were determined for eight SU UMa type Dwarf Novae observed with the ROSAT PSPC. The raw data were fitted with various spectral models and the best fit spectral models are found to be that of Raymond–Smith and Thermal Bremsstrahlung. The best fit temperatures were estimated to be between kT ~ 1.1-1.8 keV while the Column Densities were found to be between NH ~ 2.4×1020-4.1×1020 cm -2. The estimated 0.1-2.4 keV fluxes were in the range of log FX=-13 to -11 ergs cm-2 s-1. FX/F UV and FX/F opt rates were calculated to be between ~0.09 and ~0.37. This shows that most of the energy is radiated in the Optical and Ultraviolet band from the accretion disk in the quiescent state. Many of the SU UMa type Dwarf Novae show an Ultraviolet lag in their outburst spectrum, the Coronal Siphon Flow Model of Meyer and Meyer-Hofmeister may explain this phenomenon. This model proposes a corona at the boundary layer of a system when it is a quiescent state and suggests that some parts of the X-rays come from the corona. For these reasons, the equations of this model were applied to the results of the spectral analysis. Using this model, the mass accretion rates, the mass evaporation rates, and the radii of the coronas were calculated to be ~10-12.3-10-11.3 M⊙ yr -1, ~10-6.5-10-5.5 g cm -2 s -1 and ~109.1-109.9 cm , respectively. The pressures in the coronas were less than ~1200 g cm -2 s -1 for (z) up to ~10×109 cm . The obtained values suggest that the Corona model can indeed operate in SU UMa type Dwarf Novae.
Angiotensin II Inhibits Endothelial Cell Motility Through an AT1-Dependent Oxidant-Sensitive Decrement of Nitric Oxide Availability
Authors: Desideri Giovambattista , Bravi Maria Cristina , Tucci Marzia , Croce Giuseppe , Marinucci Maria Contina , Santucci Anna , Alesse Edoardo , Ferri Claudio 
Published: May 2003

Objective—The migratory capability of vascular endothelial cells plays a pivotal role in the maintenance of vessel wall integrity and is stimulated by nitric oxide (NO). Angiotensin II increases NAD(P)H oxidase activity in endothelial cells, thereby promoting reactive oxygen species (ROS) generation. Because ROS can both reduce NO synthase activity and increase NO breakdown, thus impairing NO availability in endothelial cells, we evaluated the effect of angiotensin II on human vascular endothelial cell (HUVEC) motility.Methods and Results—Angiotensin II dose- and time-dependently reduced HUVEC migration. Besides inhibiting HUVEC motility, angiotensin II altered intracellular glutathione redox status. The generation of ROS by cultured HUVECs was significantly increased by angiotensin II. Furthermore, angiotensin II reduced NO metabolite concentrations in culture media. The angiotensin II type 1 receptor antagonist candesartan cilexetil attenuated the inhibitory action exerted by angiotensin II on HUVEC motility, reversed the angiotensin II-induced increase in intracellular oxidative stress, and restored NO availability. Similar effects were exerted by the flavonoid inhibitor diphenylene iodinium and the antioxidant agentN-acetyl-l-cysteine.Conclusions—All together, our data demonstrate that angiotensin II inhibits HUVEC motility by reducing NO availability. Such reduction is due to an angiotensin II type 1 receptor-dependent increment in intracellular ROS generation.
Free-living nematodes from nature reserves in Costa Rica. 4. Cephalobina
Authors: Holovachov Oleksandr , Esquivel Alejandro , Bongers Tom 
Published: May 2003

Abstract
Four species of Cephalobina: Geraldius bakeri, Diastolaimus croca, Trualaimus
culeatus and Tricirronema tentaculatum are described and illustrated on the
basis of material collected in Costa Rica. A scanning electron microscope
(SEM) study of G. bakeri is given for the first time. Diastolaimus croca is
found to have a circle of six setiform processes anterior to the true labial
setae. Detailed descriptions of the female reproductive system in G.
backeri, D. croca and Macrolaimus sp. are given. The use of the female
reproductive system and structure of the labial sensilla in the systematics
of the family Chambersiellidae, together with its taxonomic placement, are
discussed. Notes on the systematic position of the family Bicirronematidae
and a key to the species of this family are given.
Characterisation and partial purification of a white mustard kairomone that attracts the beet cyst nematode, Heterodera schachtii
Authors: Rühm Rainer , Dietsche Elvira , Harloff Hans-Joachim , Lieb Manuela , Franke Stephan , Aumann Jens 
Published: May 2003

AbstractA kairomone from white mustard, Sinapis alba , that attracts infective juveniles (J2) of the beet cyst nematode, Heterodera schachtii, was extracted from root exudates and enriched by rotary evaporation. The kairomone-containing root exudate fractions were then repeatedly enriched and separated on a combination of octyl and octadecyl columns, leaving a single UV-absorbing HPLC peak. Glucose and fructose were identified by a subsequent HPLC separation in the ion moderated partition chromatography mode. The kairomone appeared in the fructose-containing fraction. As fructose did not cause nematode attraction, the fructose fraction contained at least one further substance. HPLC separations showed that the kairomone shares several properties with fructose and that it is relatively more polar than those compounds giving an UV signal. The repeated reversed-phase and ion moderated partition chromatography separations of single kairomone-containing fractions indicate that the kairomone is composed of one single substance which could not be identified with the methods applied. Gas chromatographic and mass spectrometric analyses revealed the presence of glucose, fructose, myo-inositol, sucrose and xylofuranose/ribofuranose in S. alba root exudates.
The reniform nematode, Rotylenchulus macrosoma, infecting olive in southern Spain
Authors: Castillo Pablo , Vovlas Nicola , Troccoli Alberto 
Published: May 2003

Abstract
Severe root infection of wild olive (Olea europea L. ssp. sylvestris),
together with heavy soil infestation by the reniform nematode Rotylenchulus
macrosoma, was detected in a natural wild olive orchard on sandy soil in
Cádiz province, Andalucía, southern Spain. Most, but not all, of the
morphometric characters of this population agreed with those reported for
immature and adult females and males in previously studied populations.
Sedentary immature and mature females showed a semi-endoparasitic feeding
habit in wild and cultivated olives (cvs Arbequina and Picual). Naturally
infected roots of wild olive responded to nematode infection identically to
artificially infected olive planting stocks. The feeding site induced by R.
macrosoma on olive roots consists of a stelar syncytium, which originates
from an endodermal cell enlarging by a curved sheet of pericycle cells
formed by hypertrophy of pericycle cells adjacent to the feeding cell. There
were obvious anatomical differences between the feeding sites induced by R.
macrosoma and R. macrodoratus on olive roots.
Lipid utilisation during storage of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis from Greece and the UK
Authors: Menti Hara , Patel Mavji , Wright Denis , Perry Roland 
Published: May 2003

Abstract
The total lipid (TL) content and the fatty acid composition of the different
lipid classes in infective juveniles of Steinernema feltiae and
Heterorhabditis megidis isolates from Greece (GR) and from the United
Kingdom (UK) were compared, and the changes during storage were determined.
Steinernema feltiae GR had a greater amount of TL than S. feltiae UK, which
was reflected in a greater neutral lipid (NL) content. The phospholipid and
free fatty acid fractions of the two Steinernema populations were similar.
The two Heterorhabditis populations did not differ in their lipid content.
In both S. feltiae populations, NL decreased by ca 60% during the first 4
weeks but remained more or less stable during the next 16 weeks. In the two
Heterorhabditis populations, NL decreased by ca 70% during the first 4 weeks
and continued to decrease, with 3-5% remaining after 12 weeks. The fatty
acid profiles and the percentages of saturation of NL and phospholipid
fractions in each population were similar before and after storage.
Virulence in Meloidogyne hapla differentiated by resistance in common bean (Phaseolus vulgaris)
Authors: Chen Peichen , Roberts Philip 
Published: May 2003

Abstract
A diverse collection of seven Meloidogyne hapla isolates, all identified as
cytological race A, were studied for their host-parasite interactions with
several common bean (Phaseolus vulgaris L.) genotypes. The M. hapla isolates
showed significant (P < 0.01) differential interactions of ability to
reproduce on resistant common bean cultivars. Based on the nematode egg mass
production on susceptible cv. Yolano and resistant cv. NemaSnap beans, the
isolates formed three groups. Four isolates produced many egg masses on both
susceptible and resistant cultivars and were defined as virulent to
resistance in cv. NemaSnap. Two isolates produced many egg mass numbers on
susceptible cv. Yolano, but very few on resistant cv. NemaSnap, and were
defined as avirulent to the resistance in NemaSnap. One isolate, WI,
produced fewer egg masses on susceptible cv. Yolano than on resistant cv.
Nemasnap and was defined as virulent to resistance in cv. NemaSnap. The
three types of host-parasite interaction indicated a transagonal reaction
for a gene-for-gene relationship between M. hapla and resistant common bean
(cv. NemaSnap). Analysis of an F2 population from crosses between cultivars
NemaSnap and Yolano revealed a single dominant gene pattern of segregation
for a major form of resistance in cv. NemaSnap. According to an allelism
test, the resistance to M. hapla in cv. NemaSnap was not derived from the
line PI165426, which is the pedigree source of M. incognita resistance in
cv. NemaSnap. However, PI165426 was found to have M. hapla resistance but
may not be homozygous for these factors.
The infectivity and behaviour of exsheathed and ensheathed Heterorhabditis megidis infective juveniles
Authors: Dempsey Catherine , Griffin Christine 
Published: May 2003

AbstractThe consequences of sheath loss on infectivity and behaviour of infective juveniles (IJ) were investigated in Heterorhabditis megidis. Ensheathed IJ were more infective, killing 32% of wax moth larvae, compared to 18% killed by exsheathed IJ. The percentage of time engaged in seven behavioural activities was recorded for individually stored IJ but no differences were found between exsheathed and ensheathed IJ. Immobility was the most common behavioural category exhibited by both exsheathed and ensheathed IJ, occupying one third of the observation time. Storage conditions affected the rate of exsheathment; 40% of IJ stored for 28 days in water in bulk (50 in 8 ml) exsheathed compared to only 23% of those stored individually (1 in 2 ml).
Effect of tuber-borne micro-organisms on hatching activity of potato root leachate towards potato cyst nematodes
Authors: Ryan N. Aileen , Jones Peter 
Published: May 2003

AbstractPotato cyst nematodes hatch in response to hatching factors (HF) present in potato root leachate (PRL). The much higher spontaneous hatch (hatch in the absence of potato plants or PRL) of both Globodera rostochiensis and Globodera pallida in sand (32.2 and 21.1%, respectively) compared to in vitro (6.0 and 4.8%) experiments suggested the presence of other hatching factor-producing organisms in the non-sterile sand. When sterile PRL (from aseptically cultured microplants) and non-sterile PRL (from aseptically cultured microplants grown in the presence of tuber washings) samples were collected and assayed for hatching activity, the in vitro hatch of both PCN species but particularly of G. pallida was greater in non-sterile PRL. When these samples were fractionated on Sephadex G-10 by low pressure liquid chromatography and the fractions tested for hatching activity, the non-sterile PRL produced more hatching factors (HF) than the sterile PRL; in the fractionated sterile PRL only one significant HF (active towards G. pallida) was observed, compared to six (towards G. pallida) and three (towards G. rostochiensis) HF from the non-sterile PRL, with two HF being active towards both species. The non-sterile PRL appeared to produce more hatching factor stimulants (HS) and fewer hatch inhibitors (HI) than the sterile PRL. These results suggest that soil micro-organisms play an important role in the production of hatching chemicals and it is proposed that the differences in HF profiles between sterile and non-sterile PRL were due, at least in part, to increased HS production in the non-sterile PRL.