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1.
Sci Rep ; 6: 30880, 2016 09 07.
Article in English | MEDLINE | ID: mdl-27600734

ABSTRACT

Our knowledge of the genetic diversity and host ranges of viruses is fragmentary. This is particularly true for the Parvoviridae family. Genetic diversity studies of single stranded DNA viruses within this family have been largely focused on arthropod- and vertebrate-infecting species that cause diseases of humans and our domesticated animals: a focus that has biased our perception of parvovirus diversity. While metagenomics approaches could help rectify this bias, so too could transcriptomics studies. Large amounts of transcriptomic data are available for a diverse array of animal species and whenever this data has inadvertently been gathered from virus-infected individuals, it could contain detectable viral transcripts. We therefore performed a systematic search for parvovirus-related sequences (PRSs) within publicly available transcript, genome and protein databases and eleven new transcriptome datasets. This revealed 463 PRSs in the transcript databases of 118 animals. At least 41 of these PRSs are likely integrated within animal genomes in that they were also found within genomic sequence databases. Besides illuminating the ubiquity of parvoviruses, the number of parvoviral sequences discovered within public databases revealed numerous previously unknown parvovirus-host combinations; particularly in invertebrates. Our findings suggest that the host-ranges of extant parvoviruses might span the entire animal kingdom.


Subject(s)
Gene Expression Profiling/methods , Parvovirus/genetics , RNA, Viral/genetics , Animals , Databases, Genetic , Genetic Variation , Metagenomics , Phylogeny , Sequence Analysis, RNA
2.
Toxicol In Vitro ; 17(1): 59-67, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12537963

ABSTRACT

The present work describes an isozyme-related effect of collagenase perfusion on hepatocyte microsomal cytochrome (CYP)-dependent monooxygenase activities: CYP 1A1/2-, 2B1/2-, 3A1/2- and 2E1-dependent activities in microsomes from rat hepatocytes after isolation were about 60% of that of liver microsomes, and CYP 4A1-dependent activity was equivalent to liver microsomes. In contrast, the microsomal protein content of the various CYP isoforms was not affected by hepatocyte isolation. This is in accordance with the hypothesis of CYP inactivation during the process of hepatocyte isolation by collagenase digestion. L-NAME (1 mM) was found unable to protect from the decline of CYP-dependent monooxygenase activities following hepatocyte isolation. It is possible that the decrease in glutathione peroxidase activity observed in the presence of L-NAME, namely depression of defense against peroxynitrite, could counteract the beneficial effect of L-NAME on nitric oxide synthesis inhibition. The present work also shows that L-NAME could not avoid the progressive, isoform-specific, most probably turnover-related, decline of CYP proteins and related monooxygenase activities in cultured hepatocytes. Dysregulations in the mechanisms of CYP expression in rat hepatocyte cultures, presently unknown but nitric oxide independent, thus appear to occur in cultured rat hepatocytes.


Subject(s)
Cytochrome P-450 Enzyme System/metabolism , Enzyme Inhibitors/pharmacology , NG-Nitroarginine Methyl Ester/pharmacology , Animals , Cell Culture Techniques , Collagenases/pharmacology , Hepatocytes , Kinetics , Microsomes, Liver , Nitric Oxide , Rats , Rats, Wistar
3.
EMBO J ; 20(7): 1498-507, 2001 Apr 02.
Article in English | MEDLINE | ID: mdl-11285214

ABSTRACT

Rotaviruses are important human pathogens with a triple-layered icosahedral capsid. The major capsid protein VP6 is shown here to self-assemble into spherical or helical particles mainly depending upon pH. Assembly is inhibited either by low pH (<3.0) or by a high concentration (>100 mM) of divalent cations (Ca(2+) and Zn(2+)). The structures of two types of helical tubes were determined by electron cryomicroscopy and image analysis to a resolution of 2.0 and 2.5 nm. In both reconstructions, the molecular envelope of VP6 fits the atomic model determined by X-ray crystallography remarkably well. The 3-fold symmetry of the VP6 trimer, being incompatible with the helical symmetry, is broken at the level of the trimer contacts. One type of contact is maintained within all VP6 particles (tubes and virus), strongly suggesting that VP6 assemblies arise from different packings of a unique dimer of trimers. Our data show that the protonation state and thus the charge distribution are important switches governing the assembly of macromolecular assemblies.


Subject(s)
Antigens, Viral , Capsid Proteins , Capsid/chemistry , Rotavirus/chemistry , Capsid/ultrastructure , Cryoelectron Microscopy , Crystallography, X-Ray , Humans , Models, Molecular , Polymorphism, Genetic , Protein Structure, Secondary , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/ultrastructure , Rotavirus/ultrastructure
4.
Neurosci Lett ; 131(1): 21-6, 1991 Sep 30.
Article in English | MEDLINE | ID: mdl-1791975

ABSTRACT

The relationship between microtubules, neurofilaments and microtubule-associated protein (MAP)2 was investigated in spinal cord neurons grown for up to 14 days in vitro. Neurons were labelled using antibodies against MAP2, neurofilaments and tubulin, and immunofluorescence analyzed by confocal microscopy. A well-structured network of neurofilaments and microtubules was observed in unstimulated cultures. MAP2 staining was poorly structured but became more filamentous following depolymerization of microtubules with nocodazole. Double-staining experiments suggested that MAP2 was now closely associated with neurofilaments in cell bodies and dendrites. Stimulation of cultures with excitatory amino acids increased the resistance of the microtubular cytoskeleton to depolymerization by nocodazole. Again double-labelling experiments demonstrated an increased association between neurofilaments and MAP2 immunofluorescence. Previous results suggested that the stability of the neuronal cytoskeleton could be modulated by glutamate receptors acting through an increased binding of MAP2 to microtubules. From the results presented here, we further suggest that cross-linking of neurofilaments to microtubules may also play a role in this process.


Subject(s)
Intermediate Filaments/ultrastructure , Microtubule-Associated Proteins/physiology , Neurons/physiology , Nocodazole/pharmacology , Quisqualic Acid/pharmacology , Spinal Cord/physiology , Animals , Antibodies, Monoclonal , Cells, Cultured , Embryo, Mammalian , Fluorescent Antibody Technique , Intermediate Filaments/drug effects , Microtubule-Associated Proteins/drug effects , Neurons/drug effects , Neurons/ultrastructure , Rats , Spinal Cord/ultrastructure , Tubulin/drug effects , Tubulin/physiology
5.
Eur J Neurosci ; 3(6): 551-558, 1991 Jun.
Article in English | MEDLINE | ID: mdl-12106487

ABSTRACT

The state of neuronal microtubule polymerization is influenced by microtubule-associated proteins such as MAP2, which is specifically localized within neuronal dendrites and cell bodies. We have demonstrated that stimulation of spinal cord or cortical neurons in vitro with excitatory amino acids results in a dramatic modification of the neuronal cytoskeleton as monitored with antibodies against MAP2 and tubulin. Stimulation of cultures with glutamate receptor agonists induced a reorganization of MAP2 immunoreactivity into a distinctive network of bundles within certain neuronal cell bodies and their proximal neurites. The effect was not abolished by depolymerizing drugs such as nocodazole, or protein synthesis inhibitors. The effect was dependent upon the entry of sodium following depolarization and was not associated with neuronal damage. We suggest that in neurons the state of the neuronal cytoskeleton can be modulated by glutamate receptor activation acting through MAP2.

6.
Neurosci Lett ; 111(3): 275-80, 1990 Apr 06.
Article in English | MEDLINE | ID: mdl-2110639

ABSTRACT

The effect of excitatory amino acid stimulation on the cytoskeleton of cultured spinal cord and cortical neurons was monitored with antibodies against microtubule-associated proteins tau and MAP2. In unstimulated cultures tau-1 immunoreactivity was restricted to axon-like processes. Stimulation with glutamate (0.1-1 mM) or N-methyl-D-aspartate (NMDA) (0.1 mM) resulted in a dramatic increase in the intensity of tau labelling in axons and the appearance of staining within a proportion of neuronal cell bodies and dendrites. Quisqualate or kainate stimulation resulted only in an increase in tau immunoreactivity within axons. The NMDA mediated events were calcium dependent and the effects of all excitatory amino acids could be blocked by specific antagonists. In contrast, following stimulation with excitatory amino acids, MAP2-immunoreactivity was associated with filaments which formed a complex network within the cell body. This suggests that the different excitatory amino acid receptor subtypes can have differential effects on the neuronal cytoskeleton.


Subject(s)
Aspartic Acid/analogs & derivatives , Glutamates/pharmacology , Microtubule-Associated Proteins/analysis , Animals , Aspartic Acid/pharmacology , Axons/analysis , Calcium/pharmacology , Cells, Cultured , Cerebral Cortex/cytology , Immunohistochemistry/methods , N-Methylaspartate , Neurons/drug effects , Rats , Spinal Cord/cytology , tau Proteins
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