PubMed Health⌕ Search

Biomedical subjects

Tosso Leeb

Publications and source records attributed to Tosso Leeb.

31 records · Page 2Linked to original sources
PubMed2004

Comparative human-mouse-rat sequence analysis of the ICAM gene cluster on HSA 19p13.2 and a 185-kb porcine region from SSC 2q.

The human intercellular adhesion molecule gene (ICAM) cluster is located in a GC-rich and gene-rich region on HSA 19p13.2. We determined the complete DNA sequence of a 185-kb porcine bacterial artificial chromosome (BAC) clone containing parts of the ICAM gene cluster. We used the porcine sequence for a detailed comparative analysis between human, pig, mouse and rat. The 185 kb of porcine sequence covered 220 kb of homologous sequence in the human genome, which adds to the growing evidence that the porcine genome is somewhat smaller than the human genome. The genomic sequences of the four species showed a high level of conserved synteny and no rearrangements in gene order were observed. During evolution, the ICAM3 gene was inactivated by mutation in the mouse and rat genome, whereas it is still present in the human and pig genome. The loss of Icam3 in rodent genomes might be relevant for rodent-specific properties of the T-cell-mediated immune response. All the other investigated genes are conserved across all four investigated sequences.

Animals↗
PubMed2004

Analysis of sequence variability of the bovine prion protein gene (PRNP) in German cattle breeds.

Different alleles of the prion protein gene (PRNP) of human and sheep are known to be associated with varying susceptibilities to transmissible spongiform encephalopathies. However, no polymorphisms in the bovine PRNP gene with an effect on susceptibility to prion diseases have been identified to date. In this study we investigated such polymorphisms in German cattle; 48 healthy animals from six different German cattle breeds and 43 cattle with bovine spongiform encephalopathy (BSE) were analyzed. In contrast to previous studies, all three exons as well as the promoter region of the PRNP gene were investigated. Sequence variants in the bovine PRNP gene could have an impact on the amino acid sequence or the expression level of the prion protein and thus on susceptibility to BSE. We identified a total of 60 polymorphisms in the PRNP gene of German cattle. Of these 60 polymorphisms, 36 were newly identified, whereas 24 of these polymorphisms had been described previously. We did not detect any novel polymorphisms affecting the amino acid sequence of the prion protein. However, we identified a 23-bp insertion/deletion polymorphism in the putative PRNP promoter region that shows a significant association with BSE susceptibility in our animals.

Amyloid↗
PubMed2003

A high resolution physical and RH map of pig chromosome 6q1.2 and comparative analysis with human chromosome 19q13.1.

BACKGROUND: The generation of BAC/PAC contigs in targeted genome regions is a powerful method to establish high-resolution physical maps. In domestic animal species the generation of such contigs is typically initiated with the screening of libraries with probes derived from human genes that are expected to be located in the region of interest by comparative mapping. However, in many instances the available gene-derived probes are too far apart to allow the cloning of BAC/PAC contigs larger than a few hundred kb. High resolution physical mapping allows to estimate the sizes of gaps and to control the orientation of the individual sub-contigs, which helps to avoid errors during the assembly of smaller contigs into final Mb-sized contigs. The recently constructed porcine IMNpRH2 panel allowed us to use this approach for the construction of high-resolution physical maps of SSC 6q1.2. RESULTS: Two sequence-ready BAC/PAC contigs of the gene-rich region on porcine chromosome 6q1.2 (SSC 6q1.2) containing the RYRl gene were constructed. The two contigs spanned about 1.2 Mb and 2.0 Mb respectively. The construction of these contigs was monitored by the results provided by the mapping of 15 markers on the IMpRH(7000rad) and 35 markers on the IMNpRH2(12000rad) radiation hybrid panels. Analyses on the IMpRH panel allowed us to globally link and orientate preliminary smaller contigs, whereas analyses on the high resolution IMNpRH2 panel allowed us to finally identify the order of genes and markers. CONCLUSIONS: A framework map of 523 cR12000 was established covering the whole studied region. The order of markers on the framework 1000:1 RH map was found totally consistent with the data deduced from the contig map. The kb/cR ratio was very constant in the whole region, with an average value of 6.6 kb/cR. We estimate that the size of the remaining gap between the two contigs is of about 300 kb. The integrated physical and RH map of the investigated region on SSC 6q1.2 was used for a comparative analysis with respect to the syntenic regions on HSA 19q13.1 and MMU 7 and revealed a perfectly conserved gene order across the entire studied interval.

Animals↗
PubMed2003

X-linked anhidrotic ectodermal dysplasia (ED1) in men, mice, and cattle.

Ectodermal dysplasias are a large group of rare genetic disorders characterized by impaired development of hair, teeth, and eccrine glands in humans, mice, and cattle. Here, we review the cloning, mutation analyses, and functional studies of the known causative genes for the X-chromosomal anhidrotic ectodermal dysplasia (ED1) in these species. Mutations in the ectodysplasin 1 (ED1) gene are responsible for X-linked anhidrotic ectodermal dysplasia. The ED1 gene encodes a signaling molecule of the tumor necrosis factor family that is involved in development of ectodermal appendages. The bovine disorder may serve as an animal model for human ED1.

Animals↗
PubMed2002

Molecular characterization of the equine testis-specific protein 1 (TPX1) and acidic epididymal glycoprotein 2 (AEG2) genes encoding members of the cysteine-rich secretory protein (CRISP) family.

The cysteine-rich secretory protein (CRISP) family consists of three members called acidic epididymal glycoprotein 1 (AEG1), AEG2, and testis-specific protein 1 (TPX1), which share 16 conserved cysteine residues at their C-termini. The CRISP proteins are primarily expressed in different sections of the male genital tract and are thought to mediate cell-cell interactions of male germ cells with other cells during sperm maturation or during fertilization. Therefore, their genes are of interest as candidate genes for inherited male fertility dysfunctions and as putative quantitative trait loci for male fertility traits. In this report, the cloning and DNA sequence of 137 kb of horse genomic DNA from equine chromosome 20q22 containing the closely linked equine TPX1 and AEG2 genes are described. The equine TPX1 gene consists of ten exons spanning 18 kb while the AEG2 gene consists of eight exons that are spread over 24 kb. The expression of these two genes was investigated in several tissues by reverse transcription polymerase chain reaction analysis and Western blotting. Comparative genome analysis between horse, human, and mouse indicates that all three CRISP genes are clustered on one chromosomal location, which shows conserved synteny between these species.

Amino Acid Sequence↗
PubMed2002

Molecular characterization of the equine AEG1 locus.

Acidic epididymal glycoprotein 1 (AEG1), also called cysteine-rich secretory protein 1 (CRISP1), is a member of the CRISP protein family which is characterized by 16 conserved cysteine residues at the C-terminus. The CRISP proteins are expressed in the male genital tract and are thought to be involved in sperm-egg fusion. Therefore, their genes are of interest as candidate genes for inherited male fertility dysfunctions and as putative quantitative trait loci for male fertility traits. In this report, the cloning and DNA sequence of 90 kb of horse genomic DNA from equine chromosome 20q22 containing the complete equine AEG1 gene are described. The equine AEG1 gene consists of eight exons spanning 31 kb. Analysis of equine AEG1 transcripts did not reveal any evidence for alternative splicing, however three different transcription start sites are used. The first transcription start site is located 20 nt downstream of a TATA box motif. Reverse transcription polymerase chain reaction analysis demonstrated that AEG1 is expressed in different parts of the epididymis, whereas it is hardly detectable in the testis. The naturally occurring diversity of the equine AEG1 gene in different horse breeds was investigated and several polymorphisms are reported, including one that affects the amino acid sequence. Finally, sequence comparisons revealed that the intronless equine PGK2 gene for the testis-specific phosphoglycerate kinase is located approximately 39 kb downstream of AEG1.

5' Flanking Region↗
PubMed2002

A single point mutation within the ED1 gene disrupts correct splicing at two different splice sites and leads to anhidrotic ectodermal dysplasia in cattle.

The ectodysplasin 1 gene ( ED1) encodes a signaling molecule of the tumor necrosis factor family that is involved in fetal development of ectodermal appendages. Mutations in the ED1 gene are responsible for X-linked anhidrotic ectodermal dysplasia characterized by impaired development of hair, teeth, and eccrine sweat glands in human, mouse, and cattle. Two isoforms of ectodysplasin 1, termed ED1-A1 and ED1-A2, arise by alternative splicing and bind to different receptors. We identified a novel ED1 splice site mutation in a cattle family with X-linked anhidrotic ectodermal dysplasia. The point mutation is located within a 5' splice site (splice donor) at the beginning of intron 8 that is used exclusively in the alternatively spliced ED1-A1 transcript. Remarkably, cDNA sequencing demonstrated that both physiological transcripts, i.e., the ED1-A1 and the ED1-A2 splice variant, were affected by this point mutation. In an affected animal, the use of cryptic internal splice donor and acceptor sites within exon 8 lead to the production of a single transcript lacking 51 or 45 bp with respect to the normal ED1-A1 or ED1-A2 transcripts, respectively. The translated protein of the mutated transcript contained a large deletion in the functionally important C-terminal tumor necrosis factor-like domain thus causing the observed phenotype of anhidrotic ectodermal dysplasia. Our findings suggest the presence of a splice enhancer in the ED1 gene in the region of the mutation.

Amino Acid Sequence↗
PubMed2002

Construction of a 1.2-Mb BAC/PAC contig of the porcine gene RYR1 region on SSC 6q1.2 and comparative analysis with HSA 19q13.13.

We screened a porcine bacterial artificial chromosome (BAC) and a P1 derived artificial chromosome (PAC) library to construct a sequence-ready approximately 1.2-Mb BAC/PAC contig of the ryanodine receptor-1 gene (RYR1) region on porcine chromosome (SSC) 6q1.2. This genomic segment is of special interest because it harbors the locus for stress susceptibility in pigs and a putative quantitative trait locus for muscle growth. Detailed physical mapping of this gene-rich region allowed us to assign to this contig 17 porcine genes orthologous to known human chromosome 19 genes. Apart from the relatively well-characterized porcine gene RYR1, the other 16 genes represent novel chromosomal assignments and 14 genes have been cloned for the first time in pig. Comparative analysis of the porcine BAC/PAC contig with the human chromosome (HSA) 19q13.13 map revealed a completely conserved gene order of this segment between pig and human. A detailed porcine-human-mouse comparative map of this region was constructed.

Animals↗
PubMed2002

Cloning and chromosomal localization of MYO15A to chromosome 5 of the dog (Canis familiaris).

Mutations in the myosin XVA gene (MYO15A) cause congenital non-syndromic deafness in humans and mice. Therefore, the M YO15A gene represents a candidate gene for hereditary hearing loss in dogs. Using a human cDNA to screen a dog BAC library, we isolated a canine BAC clone. Sequencing of the BAC ends confirmed homology to the human gene. To facilitate future linkage studies, we report the physical mapping of the canine MYO15A gene to CFA5q23-q24 by FISH and RH mapping.

Animals↗
PubMed2002

Congenital hypotrichosis with anodontia in cattle: a genetic, clinical and histological analysis.

Hypotrichosis, an almost complete lack of teeth and the complete absence of eccrine nasolabial glands, was observed among the progeny of a normal cow of the black and white German Holstein breed. Similar congenital anomalies are known in humans and mice as X-linked anhidrotic ectodermal dysplasia (ED1), leading to the impaired formation of hair, teeth and sweat glands. The pedigree of the four affected male calves in the investigated cattle family indicated that the described phenotype is inherited as a monogenic X-linked recessive trait. We used a diagnostic reverse transcription-polymerase chain reaction (RT-PCR) assay to study the heredity of a previously reported causative large genomic deletion in the bovine ED1 gene. This test allowed the unequivocal classification of disease carriers that were phenotypically normal. As the clinical, pathological and genetic findings in human ED1 show striking similarities to the described phenotype in cattle, this bovine disorder may serve as an animal model for human ED1.

Animals↗
PubMed2002

Cloning and characterization of the mammalian-specific nicolin 1 gene (NICN1) encoding a nuclear 24 kDa protein.

We have identified a novel mammalian gene, termed nicolin 1 gene (NICN1), that is present in human, dog and mouse, whereas it is absent from the available genome sequences of nonmammalian organisms. The NICN1 gene consists of six exons and spans about 6 kb of genomic DNA. It encodes a 213 amino acid protein that does not belong to any known protein family. Experiments using green fluorescent protein (GFP)-tagged nicolin 1 fusion proteins indicate that nicolin 1 is a nuclear protein. Northern analysis and semiquantitative RT-PCR demonstrated that the 2.5 kb NICN1 mRNA is expressed in a tissue-specific manner. The highest NICN1 expression levels are found in brain, testis, liver, and kidney. On the other hand the NICN1 expression is weak in spleen, leukocytes, small intestine and colon. The NICN1 gene is also expressed during development.

Amino Acid Sequence↗
PubMed2002

Genomic organization of the murine aminomethyltransferase gene (Amt).

Aminomethyltransferase (Amt), also called glycine cleavage system T-protein is an important enzyme in glycine metabolism (EC 2.1.2.10). Mutations in this gene in humans lead to nonketotic hyperglycinemia, a fatal Mendelian disease. Here, we report the cloning and sequencing of the murine Amt gene. The murine Amt gene consists of nine closely spaced exons that are contained within approximately 5 kb of genomic DNA. It encodes a protein of 403 amino acids that is highly homologous to other mammalian aminomethyltransferases. The cis-acting promoter of the Amt gene is likely to be very short as immediately upstream of the murine Amt gene another gene termed Nicolin 1 gene (Nicn1) is located.

Amino Acid Sequence↗