Hans Lenstra
Utrecht University, Faculty of Veterinary Medicine, Department Member
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In many biological processes, defined regions of proteins are involved in selective recognition. These regions can often be mimicked with peptides and are the main targets for vaccine and drug development. The authors review the use of... more
In many biological processes, defined regions of proteins are involved in selective recognition. These regions can often be mimicked with peptides and are the main targets for vaccine and drug development. The authors review the use of peptides, to define and ultimately mimic defined protein regions of interest. Especially the role of the Pepscan method is emphasized. This method has been proven to be a useful and fast tool in defining protein regions of interest. It is based on the simultaneously synthesis of multiple peptides coupled to solid supports. Hundreds of peptides can be produced and tested in a relatively short period of time. With the construction of random peptide libraries in recombinant DNA systems, it is now even possible to screen for peptidic determinants without the requirement of preliminary knowledge of primary structure. Having this information, the affinity of peptides can be further enhanced with the Pepscan approach. The power of this approach will be illustrated with results from studies on the development of synthetic vaccines and hormone analogues.
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We sequenced and analyzed 97.6 kb of new DNA sequence containing the human TCRAC (Cα) and TCRDC (Cδ) genes as well as the TCRCDV3 (vδ3) and 61 different TCRAJ (Jα) gene segments and compared its organization and structure to the... more
We sequenced and analyzed 97.6 kb of new DNA sequence containing the human TCRAC (Cα) and TCRDC (Cδ) genes as well as the TCRCDV3 (vδ3) and 61 different TCRAJ (Jα) gene segments and compared its organization and structure to the previously described mouse T-cell receptor TCRAC/TCRDC (Cα/Cδ) region. A comprehensive nomenclature, consistent with the IUIS nomenclature committee recommendations, for both human and mouse TCRAJ gene segments is presented. In the human sequence, we identified 20 new TCRAJ gene segments and obtained the germline sequence for 23 additional TCRAJ gene segments known from cDNA clones. Using the sequence data obtained from the human TCRAC/TCRDC region, we have extended a polymerase chain reaction-based assay to test for the expression of the individual TCRAJ gene segments. At least five TCRAJ pseudogene segments were identified by sequence criteria. Like the murine TCRAC/TCRDC sequence, this sequence contains a high level of coding sequence, with over 6.6% of the total sequence being transcribed. Comparison of the human sequence with the previously reported mouse DNA sequence reveals homologous counterparts for the variable and joining (J) gene segments and both constant genes. Eleven new J pseudogene segments have been identified in the mouse TCRAC/TCRDC sequence through the use of human and mouse sequence comparisons. In terms of structure and organization, this region of the human and mouse genome appears to be remarkably conserved.
Research Interests: Information Systems, Genetics, Genomics, T cell receptor, DNA, and 19 moreHumans, Sequence alignment, Mice, Animals, Connective tissue, Chemical Analysis, Biological evolution, Genes, Species Specificity, Amino Acid Sequence, Base Sequence, Membrane Protein, Pseudogenes, Organic Compound, Blood cells, Somatic Cells, DNA sequence, Molecular Sequence Data, and Sequence homology
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The tribe Bovini comprises cattle and cattle-like species. Reconstructions of their phylogeny have so far been incomplete and have yielded conflicting conclusions about the relationship of American bison and wisent (European bison). We... more
The tribe Bovini comprises cattle and cattle-like species. Reconstructions of their phylogeny have so far been incomplete and have yielded conflicting conclusions about the relationship of American bison and wisent (European bison). We have compared the sequences of three mitochondrial and two Y-chromosomal DNA segments. Mitochondrial DNA indicates that four distinct maternal lineages diverged after an early split-off of the buffalo species, leading to (1) taurine cattle and zebu, (2) wisent, (3) American bison and yak, and (4) banteng, gaur, and gayal, respectively. At a higher level, lineages (1) and (2) and lineages (3) and (4) are probably associated. In contrast, Y-chromosomal sequences indicate a close association of American and European bison, which is in agreement with their morphological similarity, complete fertility of hybrid offspring, and amplified fragment length polymorphism (AFLP) fingerprints of nuclear DNA. One explanation for the anomalous divergence of the mitochondrial DNA from the two bison species is lineage sorting, which implies that two distinct mitochondrial lineages coexisted in the bison-yak branch until the recent divergence of American bison and wisent. Alternatively, the wisent may have emerged by species hybridization initiated by introgression of bison bulls in another ancestral species. This "transpatric" mode of species formation would be consistent with the recent appearance of the wisent in the fossil record without clearly identifiable ancestors.
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Expressed sequence tags from the parasitic nematode Haemonchus contortus were generated in order to identify anchor loci for comparative mapping between nematode genomes and candidate targets for future control measures. In total, 370 SL1... more
Expressed sequence tags from the parasitic nematode Haemonchus contortus were generated in order to identify anchor loci for comparative mapping between nematode genomes and candidate targets for future control measures. In total, 370 SL1 trans-spliced cDNAs from different developmental stages representing 195 different genes were partially sequenced. From these expressed sequence tags 50% were similar to genes with a known or predicted function and 19% were similar to nematode sequences with no ascribed function. From the first, free-living L1 and L3 stages relatively many cDNAs matched to housekeeping genes, and 11% (L1) or 23% (L3) of the encoded proteins were predicted to contain signal peptides. In contrast, no function could be ascribed to most of the cDNAs from the early L5 and adult parasitic stages, but for 30% (L5) or 55% (adult) of the encoded proteins a signal sequence was predicted. This limited analysis suggests that during the transition from the free-living to parasitic stages gene expression shifts towards the synthesis of less conserved extracellular proteins. These proteins offer the best perspectives for vaccine development and the development of anthelmintic drugs. In contrast, cDNAs from the first larval stages may be most suitable for comparative mapping with the free-living nematode Caenorhabditis elegans.
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Research Interests: Analytical Chemistry, DNA, Sheep, Animal Feed, Animals, and 5 moreMeat, Cattle, Chickens, Food Sciences, and Bone and Bones
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CD1d-restricted invariant natural killer T cells (NKT cells) have been well characterized in humans and mice, but it is unknown whether they are present in other species. Here we describe the invariant TCR α chain and the full length CD1d... more
CD1d-restricted invariant natural killer T cells (NKT cells) have been well characterized in humans and mice, but it is unknown whether they are present in other species. Here we describe the invariant TCR α chain and the full length CD1d transcript of pig and horse. Molecular modeling predicts that porcine (po) invariant TCR α chain/poCD1d/α-GalCer and equine (eq) invariant TCR α chain/eqCD1d/α-GalCer form complexes that are highly homologous to the human complex. Since a prerequisite for the presence of NKT cells is the expression of CD1d protein, we performed searches for CD1D genes and CD1d transcripts in multiple species. Previously, cattle and guinea pig have been suggested to lack CD1D genes. The CD1D genes of European taurine cattle (Bos taurus) are known to be pseudogenes because of disrupting mutations in the start codon and in the donor splice site of the first intron. Here we show that the same mutations are found in six other ruminants: African buffalo, sheep, bushbuck, bongo, N’Dama cattle, and roe deer. In contrast, intact CD1d transcripts were found in guinea pig, African elephant, horse, rabbit, and pig. Despite the discovery of a highly homologous NKT/CD1d system in pig and horse, our data suggest that functional CD1D and CD1d-restricted NKT cells are not universally present in mammals.
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The major satellite of the horse genome consists of about 1 million copies of a 221-bp tandem repeat unit. By fluorescence in situ hybridization it has been localized in the centromeres of 58 of the 64 horse chromosomes. The donkey genome... more
The major satellite of the horse genome consists of about 1 million copies of a 221-bp tandem repeat unit. By fluorescence in situ hybridization it has been localized in the centromeres of 58 of the 64 horse chromosomes. The donkey genome contains a similar but not identical satellite. Strikingly, the equine repeat did not hybridize to DNA of the Grevy zebra, despite the divergence of the horse and zebra only 3 to 5 million years ago and the ability of these species to crossbreed. The evolution of satellite DNA in the Equidae is more rapid than that in other mammalian families, which may be explained by their rapid karyotypic evolution.
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It is known that a satisfactory clinical outcome can follow the implantation of cardiac valve allografts in spite of the loss of living cells in the tissue. If viable cells are not required for long term graft function, then effective... more
It is known that a satisfactory clinical outcome can follow the implantation of cardiac valve allografts in spite of the loss of living cells in the tissue. If viable cells are not required for long term graft function, then effective disinfection of the tissue might become possible. In an earlier paper in this series we reported that peracetic acid (PAA) is an effective antimicrobial agent for the treatment of valve allografts; it was lethal to the cells but at a concentration of 0.21% had little effect on the mechanical properties or extracellular morphology of the valve leaflets. It was also found that PAA-treatment could be combined with storage in 85% glycerol at 4 °C, or cryopreservation with 10%Me2SO, without substantial further impairment of microscopic structure or mechanical properties. In this paper we describe the implantation of processed ovine aortic valves in the descending thoracic aorta of sheep. The experimental groups included control untreated valves and valves that had been treated with antibiotics or PAA and either cryopreserved, or stored in 85%glycerol. The recipient sheep showed good clinical appearances until the experiment was terminated at six months. The explanted grafts were examined by standard morphological and mechanical testing methods. The PAA-treated valves were clearly recognisable as valves: the leaflets had fair to medium morphology in both the unpreserved and the cryopreserved groups. All leaflets had a superficial overgrowth of cells. Microsatellite analysis for allelic differences were performed on samples of donor and recipient tissues using three markers of tissue source. Only one valve, which had been treated with PAA, revealed allelic differences between donor and recipient. It is suggested that DNA-fragments may have remained after the destruction of donor cells and six months of implantation: the overgrowing cells were almost certainly of recipient origin. We conclude that our experiments, in which PAA-treatment was combined with preservation, are sufficiently encouraging to justify further studies to refine the technique, but in our opinion they are not sufficient to justify a clinical trial at this time.
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The polymerase chain reaction (PCR) allows the in vitro amplification of DNA fragments starting with tiny amounts of biological sample and oligonucleotide primers derived from sequence data. Since the technique is fast and easy, PCR has... more
The polymerase chain reaction (PCR) allows the in vitro amplification of DNA fragments starting with tiny amounts of biological sample and oligonucleotide primers derived from sequence data. Since the technique is fast and easy, PCR has taken the DNA-technology to the routine laboratoria. We present a survey of the following applications of PCR: 1) The amplification of gene fragments as fast alternative of cloning. 2) The modification of DNA fragments. 3) The sensitive detection of pathogenic microorganisms, if desired followed by an accurate genotyping. 4) DNA analysis of arachaeological specimens. 5) The detection of mutations relevant for inherited diseases, malignant transformation or tissue typing. 6) The analysis of genetic markers for forensic applications, for paternity testing and for the mapping of hereditary traits. 7) The species-specific amplification of DNA segments between interspersed-repeat elements. 8) The study of gene expression.
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... Article first published online: 24 APR 2009. DOI: 10.1111/j.1365-2052.1994.tb00129.x. © 1994 International Society for Animal Genetics. Issue. Animal Genetics. Volume 25, Issue 3, page 207, June 1994. Additional Information. How to... more
... Article first published online: 24 APR 2009. DOI: 10.1111/j.1365-2052.1994.tb00129.x. © 1994 International Society for Animal Genetics. Issue. Animal Genetics. Volume 25, Issue 3, page 207, June 1994. Additional Information. How to Cite. ...
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Otsen, M., Plas, M. E., Groeneveld, J., Roos, M. H., Lenstra, J. A., and Hoekstra, R. 2000. Genetic markers for the parasitic nematode Haemonchus contortus based on intron sequences. Experimental Parasitology95, 226–229
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Polymorphic molecular markers are being identified to characterize the genomes of parasitic nematodes. The aim is to construct a map with markers evenly spread over the six chromosomes. With such a map, regions can be identified that are... more
Polymorphic molecular markers are being identified to characterize the genomes of parasitic nematodes. The aim is to construct a map with markers evenly spread over the six chromosomes. With such a map, regions can be identified that are under selection pressure when attempts are being made to eradicate worms, be it by drugs, vaccines or genetic resistance in the sheep. Several types of markers have been developed, microsatellites, transposon-associated markers, amplified fragment length polymorphism (AFLP) and expressed sequence tag (EST) markers. Linkage groups can be constructed using several genetic crosses between inbred and drug resistant strains. EST markers will be especially important for comparative mapping with the genome of Caenorhabditis elegans, and therefore localization of the linkage group on a chromosome. It will then be possible to identify functional genes close to markers that have changed allele frequencies under selection pressure and identify the mechanisms of resistance to parasite control.
Research Interests: Zoology, Polymorphism, Helminthology, Animals, Genome, and 4 moreNematoda, Haemonchus, Genetic Markers, and DNA marker
Two horses (a 7-year-old Groninger warmblood gelding and a six-month-old Trakehner mare) with pathologically confirmed rhabdomyolysis were diagnosed as suffering from multiple acyl-CoA dehydrogenase deficiency (MADD). This disorder has... more
Two horses (a 7-year-old Groninger warmblood gelding and a six-month-old Trakehner mare) with pathologically confirmed rhabdomyolysis were diagnosed as suffering from multiple acyl-CoA dehydrogenase deficiency (MADD). This disorder has not been recognised in animals before. Clinical signs of both horses were a stiff, insecure gait, myoglobinuria, and finally recumbency. Urine, plasma, and muscle tissues were investigated. Analysis of plasma showed hyperglycemia, lactic acidemia, increased activity of muscle enzymes (ASAT, LDH, CK), and impaired kidney function (increased urea and creatinine). The most remarkable findings of organic acids in urine of both horses were increased lactic acid, ethylmalonic acid (EMA), 2-methylsuccinic acid, butyrylglycine (iso)valerylglycine, and hexanoylglycine. EMA was also increased in plasma of both animals. Furthermore, the profile of acylcarnitines in plasma from both animals showed a substantial elevation of C4-, C5-, C6-, C8-, and C5-DC-carnitine. Concentrations of acylcarnitines in urine of both animals revealed increased excretions of C2-, C3-, C4-, C5-, C6-, C5-OH-, C8-, C10:1-, C10-, and C5-DC-carnitine. In addition, concentrations of free carnitine were also increased. Quantitative biochemical measurement of enzyme activities in muscle tissue showed deficiencies of short-chain acyl-CoA dehydrogenase (SCAD), medium-chain acyl-CoA dehydrogenase (MCAD), and isovaleryl-CoA dehydrogenase (IVD) also indicating MADD. Histology revealed extensive rhabdomyolysis with microvesicular lipidosis predominantly in type 1 muscle fibers and mitochondrial damage. However, the ETF and ETF-QO activities were within normal limits indicating the metabolic disorder to be acquired rather than inherited. To our knowledge, these are the first cases of biochemical MADD reported in equine medicine.
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DNA sequences from Bovidae (cattle, goats and sheep) in the EMBL nucleotide database contain several short interspersed repeated sequences (SINEs). Three different SINEs have been found: Bov-A2, containing two 115-bp A elements; Bov-tA, a... more
DNA sequences from Bovidae (cattle, goats and sheep) in the EMBL nucleotide database contain several short interspersed repeated sequences (SINEs). Three different SINEs have been found: Bov-A2, containing two 115-bp A elements; Bov-tA, a tRNA pseudogene coupled to an A element; and Bov-B of 560 bp or less and partially homologous to the A element. Bov-A2, Bov-tA and Bov-B occupy about 1.8%, 1.6% and 0.5%, respectively, of the bovine genome as represented in the nucleotide database. Apart from a tRNA-like sequence in both Bov-tA and the porcine SINEs, there was no similarity with the porcine SINEs. Apparently, the artiodactyle SINEs were established after the divergence leading to the Suidae and Bovidae but before the radiation within these families. Oligonucleotides were designed for a specific amplification of DNA from Bovidae.
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ABSTRACT
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... a, Joannes HF Erkens , JGA Langeveld b, Willem PA Posthumus b, Rob H. Meloen ", Fatima Gebauer , Isabela Correa , Luis Enjuanes and ... filter for a few seconds in TABLE 1 MONOCLONAL ANTIBODIES AGAINST THE SPIKE PROTEIN OF... more
... a, Joannes HF Erkens , JGA Langeveld b, Willem PA Posthumus b, Rob H. Meloen ", Fatima Gebauer , Isabela Correa , Luis Enjuanes and ... filter for a few seconds in TABLE 1 MONOCLONAL ANTIBODIES AGAINST THE SPIKE PROTEIN OF TGEV Site mAh Linear " Neutralizing ...
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Research Interests: Genetics, Microbiology, Zoology, Polymorphism, Reproduction, and 21 moreGenetic Diversity, Sheep, Habitat, Parasite, Animals, Drug Resistance, Microbial genetic and drug resistance, Fragmentation, Mating System, Anti-Bacterial Agents, Inbreeding, SHEEP DISEASES, Genetic variation, Economic Loss, Veterinary Sciences, Species Specificity, Benzimidazoles, Haemonchus, Population dynamic, Allele Frequency, and Haemonchus contortus
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Several animal species such as cattle, goats, sheep, and water buffalo provide milk for dairy products. We describe a simple procedure for detecting the species origin of milk used for cheese production. DNA was isolated from Italian... more
Several animal species such as cattle, goats, sheep, and water buffalo provide milk for dairy products. We describe a simple procedure for detecting the species origin of milk used for cheese production. DNA was isolated from Italian mozzarella or Greek feta by sequential organic extractions and resin purification. This DNA was analyzed by polymerase chain reaction-restriction fragment length polymorphism as described previously for meat samples. This procedure differentiated mozzarella made from water buffalo milk and from less expensive bovine milk and also feta cheeses made from bovine, ovine, and caprine milk.
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The large subunit of eukaryotic ribosomes contains acidic phosphoproteins which are related to L7/L12 from Escherichia coli. In the brine shrimp Artemia these proteins are designated eL12 and eL12'. We have isolated cDNA... more
The large subunit of eukaryotic ribosomes contains acidic phosphoproteins which are related to L7/L12 from Escherichia coli. In the brine shrimp Artemia these proteins are designated eL12 and eL12'. We have isolated cDNA clones for these proteins from a cDNA bank that was constructed by the use of size-fractionated poly(A)-rich RNA (8-10S fraction) from Artemia and a synthetic oligonucleotide as primer. Clones containing DNA sequences coding for eL12 and eL12 were characterized by hybrid-selected translation and DNA sequencing. The proteins eL12 and eL12' share an identical peptide of 22 amino acids at their carboxy termini whereas the remaining part of the protein shows little sequence homology. The nucleotide sequences show a different codon use for the amino acids in the common carboxy terminus, thereby excluding a common exon coding for this part of both proteins. Despite the differences in amino acid sequence in the major part of eL12 and eL12' the proteins have a considerable degree of homology on the basis of the distribution of hydrophobic and hydrophilic amino acids over the polypeptide chains, in agreement with a related folding and function of both proteins. Relative levels of mRNA coding for eL12, eL12' and elongation factor 1 alpha were determined during the development of Artemia from a dormant cyst to a nauplius. The data show a coordinate expression of the genes for EF-1 alpha and both ribosomal proteins, excluding a differential expression of the genes for these related ribosomal proteins during embryogenesis. Analysis of the gene copy number for eL12 and eL12' indicates the presence of a few genes for each protein.