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M Kool

Publications and source records attributed to M Kool.

30 records · Page 2Linked to original sources
PubMed1997

Assignment of the canalicular multispecific organic anion transporter gene (CMOAT) to human chromosome 10q24 and mouse chromosome 19D2 by fluorescent in situ hybridization.

Rabbit epithelial basolateral chloride conductance regulator (EBCR) and rat canalicular multispecific organic anion transporter (Cmoat) are found to be homologues based on protein sequence comparison and Northern blot analysis. EBCRis, therefore, renamed as rabbit Cmoat. The gene encoding CMOAT, a transporter possibly involved in Dubin-Johnson syndrome in humans, is mapped on human chromosome 10q24 and mouse chromosome 19D2.

ATP-Binding Cassette Transporters↗
PubMed1995

Does lowering of cholesterol levels influence functional properties of large arteries?

Hypercholesterolaemia is a risk factor for atherosclerosis and induces endothelial dysfunction. Endothelial dysfunction may increase vascular tone and arterial stiffness and as a consequence may decrease arterial distensibility (DC) and arterial compliance (CC). It is hypothesized that lipid-lowering therapy may enhance DC and CC. Therefore, the present study investigates the effect of lipid-lowering therapy with pravastatin on the haemodynamics, DC and CC of the elastic common carotid artery (CCA), and the muscular femoral (FA) and brachial (BA) arteries in patients with primary hypercholesterolaemia. After an 8-week placebo run-in period with a low-cholesterol diet, 19 patients with total cholesterol concentrations of between 6.5 and 9.0 mmol.l-1 and triglyceride concentrations < 4 mmol.l-1 entered a double-blind placebo controlled crossover study. Patients received pravastatin 40 mg o.d. or placebo, each for 8 weeks. Throughout the study the lipid-lowering diet was continued. With pravastatin, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and triglycerides were decreased (total cholesterol 26%, LDL-C 35%, triglycerides 16%), while high-density lipoprotein cholesterol (HDL-C) was not changed. Other laboratory values remained within the normal range. Blood pressure, heart rate, cardiac function and systemic vascular resistance were not influenced by pravastatin. Compared to placebo, diameter, distensibility and compliance of all arteries were not statistically significantly changed with pravastatin. These data suggest that, in patients with mild to moderate primary hypercholesterolaemia, short-term lowering of plasma cholesterol does not alter the haemodynamics and vessel wall properties of large arteries.

Adolescent↗
PubMed1994

Identification of genes involved in DNA replication of the Autographa californica baculovirus.

By use of a transient replication assay, nine genes involved in DNA replication were identified in the genome of the Autographa californica baculovirus. Six genes encoding helicase, DNA polymerase, IE-1, LEF-1, LEF-2, and LEF-3 are essential for DNA replication while three genes encoding P35, IE-2, and PE38 stimulate DNA replication. No stimulation by the AcMNPV pcna gene, encoding a protein with sequence homology to proliferating-cell nuclear antigen, was observed. A pattern of amino acids found in a number of single-stranded-DNA-binding proteins was identified in the carboxyl-terminal region of IE-1.

DNA Replication↗
PubMed1994

Functional mapping of regions of the Autographa californica nuclear polyhedrosis viral genome required for DNA replication.

Previous results showed that plasmids containing one of the eight putative origins (ori's) of Autographa californica nuclear polyhedrosis virus (AcMNPV) are replicated after transfection into Spodoptera frugiperda cells if essential trans-acting factors are supplied by AcMNPV infection (Kool et al., Virology, 192, 94-101, 1993a; Kool et al., J. Gen. Virol., in press, 1993b; Leisy and Rohrmann, Virology, 196, 722-730, 1993). In this report a transient complementation assay is described in which four cotransfected cosmid clones, instead of AcMNPV infection, provided essential trans-acting factors for plasmid DNA replication. In this assay plasmid replication was found to be independent of the presence, in cis, of a viral ori. No replication of plasmids occurred when one of the cosmids was omitted from the transfection mixture. This result indicated that this assay is a valid approach for identification of AcMNPV replication genes. We further used the assay to define essential regions in the four required cosmids. Six regions of the AcMNPV genome, EcoRI-I (map unit 0.3-5.8), EcoRI-O (map unit 6.9-8.7), SstI-F (map unit 38.9-45.0), EcoRI-D (map unit 59.9-68.3), a BamHI-SstII fragment of BamHI-B (map unit 84.3-89.7), and EcoRI-B (map unit 90.0-100), with at least seven genes, were found to be essential for plasmid DNA replication. These regions contain the putative DNA polymerase gene (SstI-F), the helicase-like gene (EcoRI-D), and the region where most of the trans-activating immediate--early genes of AcMNPV are located (EcoRI-B). For SstI-F it was shown that this region contains besides the DNA polymerase gene at least one other replication gene. These results show that it will now be possible to define the set of AcMNPV genes necessary and sufficient for DNA replication.

Animals↗
PubMed1994

A putative non-hr origin of DNA replication in the HindIII-K fragment of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus.

In addition to the seven known homologous regions (hrs) of Autographa californica multiple nucleocapsid polyhedrosis virus (AcMNPV) the HindIII-K fragment was also found to carry a putative ori, although this fragment does not contain an hr. Deletion analysis showed that this ori contains several segments essential for its activity and other 'auxiliary' sequences that enhance the ori activity. Sequence analysis identified several structures often found in other viral replication oris, such as palindromes and other repeated motifs. Although most of the auxiliary sequences of this ori were found to be deleted in the Bombyx mori nucleocapsid polyhedrosis virus genome, the essential part of this ori, containing the palindromes and the A/T-rich region, was retained. This and the fact that after prolonged serial passage of AcMNPV large replicating DNA molecules are found in which repeated sequences derived from the HindIII-K fragment accumulate are consistent with this region being a putative origin of AcMNPV DNA replication.

Animals↗
PubMed1994

Nucleotide sequence and genetic organization of a 7.3 kb region (map unit 47 to 52.5) of Autographa californica nuclear polyhedrosis virus fragment EcoRI-C.

The nucleotide sequence and genetic organization of a 7297 bp region within the EcoRI-C fragment of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus (AcMNPV) are presented. Eight putative open reading frames were found and their respective amino acid sequences compared with a number of data libraries. ORF 1227 corresponded with gp41 and its predicted protein sequence was found to be 55 amino acids longer at its C terminus than reported previously. Moreover the main part of the ORF 1227 product, including the additional 55 amino acids, showed a high degree of homology with protein p40 of Helicoverpa zea single nucleocapsid nuclear polyhedrosis virus (HzSNPV). Three other ORFs in the analysed AcMNPV region showed homology with ORFs in the HzSNPV sequence, indicating that the general organization of this region is similar in both viruses. However one ORF found in the AcMNPV sequence was absent from the corresponding HzSNPV sequence.

Amino Acid Sequence↗
PubMed1993

Location of two putative origins of DNA replication of Autographa californica nuclear polyhedrosis virus.

Previously, we described a defective Autographa californica nuclear polyhedrosis virus (AcMNPV) which must contain cis-acting elements required for DNA synthesis, such as the origin(s) of replication (ori). Defective genomes of AcMNPV generated after serial undiluted passage were analyzed further. Three small separated regions were retained in DNA of defective AcMNPV and accumulated in extracellular defective interfering viruses as well as in intracellular DNA after 40 passages. Two of these regions have now been identified as containing putative ori. They are located on the HindIII-B fragment between map units (m.u.) 50.1 and 53.2 and on the HindIII-Q fragment between m.u. 87.2 and 88.9 of the physical map of AcMNPV DNA, respectively. Transfection of Spodoptera frugiperda cells with plasmids containing these sequences followed by superinfection with intact helper AcMNPV resulted in amplification of these plasmids, as demonstrated by the Dpnl sensitivity assay. The replicating activity of HindIII-Q is putatively located within the 1000-bp region containing a highly repetitive DNA (hr5), which is also ascribed to enhance delayed-early gene expression. In order to demonstrate replicating activity of test plasmids, it appeared essential to transfect the cells well before superinfection with helper virus.

Animals↗
PubMed1993

The structural and functional organization of the Autographa californica nuclear polyhedrosis virus genome.

Baculoviruses are used as biological control agents of insect pests in agriculture and forestry. The multiple-nucleocapsid nuclear polyhedrosis virus of Autographa californica (AcMNPV) is the prototype baculovirus. Recently, this virus has become widely used as vector for the high-level expression of foreign genes in insect cells. An updated physical map of restriction sites as well as the location of open reading frames (ORFs) and transcripts are presented. Most characteristic is the dispersal of "early", "late", and "very late" genes over the genome and the presence of nested sets of 3' and 5' coterminal transcripts.

Baculoviridae↗
PubMed1993

Identification of seven putative origins of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus DNA replication.

Seven putative origins of DNA replication (oris) were identified and located on the genome of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus (AcMNPV), when an improved infection-dependent replication assay was used. A threefold higher yield of amplified plasmid was achieved when an m.o.i. of 1 was used (instead of 25), and another twofold increase was obtained when the interval between transfection and infection was extended from 5 to 24 h. Six of the putative oris were located in hr regions with homologous sequences. This suggests that all hrs in AcMNPV are bifunctional, i.e. have both ori and enhancer activity for transcription. In addition to the six hrs, the HindIII-K fragment of AcMNPV was also identified to carry a putative ori, although this fragment does not contain an hr region. However, the individual role of these seven oris during viral DNA replication, and whether they are all active simultaneously in vivo, is still unclear. The replication of an ori-containing plasmid starts at the same time (6 h post-infection) and proceeds at the same rate as viral DNA replication. A circular topology of ori-containing plasmids was a prerequisite for replication. Linear DNA, with an ori, did not replicate. Therefore, we suggest a theta structure or a rolling-circle as a model for baculovirus DNA replication.

Animals↗
PubMed1991

Detection and analysis of Autographa californica nuclear polyhedrosis virus mutants with defective interfering properties.

Defective interfering particles (DIPs) were generated upon continuous production of Autographa californica nuclear polyhedrosis virus (AcNPV) in bioreactors. This configuration mimicked the serial undiluted passaging of virus, which is known to result in plaque-morphology mutants. Restriction enzyme analysis of DIP-containing preparations of extracellular virus showed the presence of many DNA fragments in less than equimolar amounts. These fragments were colinear on the physical map of AcNPV and extended from map position 1.7 to 45. These DIPs thus lacked 43% of the genetic information of the standard virus, including the polyhedrin and DNA polymerase genes. The existence of DIPs was confirmed by electron microscopy, where virions were observed with reduced length. Among the less than equimolar fragments in DIP-containing preparations, fragments were observed linking sequences from map positions 1.7 and 45 via a TGTT linker of unknown origin. The DIPs could not be plaque-purified and needed standard (helper) virus to replicate; DIP-containing preparations interfered with standard virus replication in an interference assay, which explained the reduction in productivity of an AcNPV expression vector-insect cell system in continuous bioreactor operations. The origin of these DIPs and their possible generation mechanism are discussed.

Animals↗
PubMed1990

Bioreactor development for production of viral pesticides or heterologous proteins in insect cell cultures.

The insect cell-baculovirus expression system has significant potential for producing proteins requiring some degree of posttranslational modification. T. ni cells appear to be as good a host as S. frugiperda cells for heterologous protein production as demonstrated by production of beta-galactosidase. Attachment-dependent cells of T. ni can be effectively cultured in a packed-bed reactor using glass beads. When cell in such a reactor were infected, they produced 35% of the total protein as beta-galactosidase. No cell detachment was observed even 70 h postinfection. A model of viral entry has been proposed and tested.

Animals↗