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M Schwerin

Publications and source records attributed to M Schwerin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Chromatin structure of the bovine Cyp19 promoter 1.1. DNaseI hypersensitive sites and DNA hypomethylation correlate with placental expression.

Expression of the Cyp19 gene, encoding aromatase cytochrome P450, is driven by several tissue-specific promoters. The underlying mechanisms of this complex regulation have not yet been elucidated in detail. In the present report we investigate a possible link between chromatin structure and tissue-specific regulation of the bovine Cyp19 gene. We analysed the DNA methylation status and mapped DNaseI hypersensitive sites in the region encompassing the Cyp19 promoter 1.1 (P1.1) which controls Cyp19 expression in the bovine placenta. We show that P1.1 is hypomethylated in placental cotyledons (foetal layer) whereas it is methylated in placental caruncles (maternal layer), testis and corpus luteum. Furthermore, two placenta-specific DNaseI hypersensitive sites, HS1 and HS2, were observed within P1.1. Both DNA hypomethylation and the presence of DNaseI hypersensitive sites correlate with transcriptional activity of P1.1. Sequence analysis of hypersensitive sites revealed potential cis-regulatory elements, an E-box in HS1 and a trophoblast-specific element-like sequence in HS2. It could be demonstrated by electrophoretic mobility shift assays that both sequence motifs are specific targets for placenta-derived nuclear factors. In conclusion, observed tissue-specific differences of the chromatin structure which correlate with tissue-specific promoter activity suggest that chromatin might be an important regulator of aromatase expression in cattle.

Animals↗
PubMed2001

Genome-wide search for loci controlling serum IGF binding protein levels of mice.

A segregating F(2) pedigree based on two mouse lines (DU6i and DBA/2) with extremely different growth characteristics was generated to search for loci affecting serum levels of insulin-like growth factor (IGF) binding proteins (IGFBPs) and to estimate their effects on growth and body composition. DU6i is characterized by high body mass and obesity associated with hyperinsulinemia, hyperleptinemia, and elevated serum IGF-I concentrations. Furthermore, significantly elevated serum levels of IGFBP-2, IGFBP-3, and IGFBP-4 were found in DU6i vs. DBA/2 mice. Linkage analysis identified loci with major effects on the serum level of IGFBP-3 on Chromosome 5 at 58 cM (Igfbp3q1; F = 9.9) and on Chromosome 10 at 46 cM (Igfbp3q2; F = 33.8). A locus significantly influencing serum IGFBP-2 levels in males was found on Chromosome 7. Additional linkage was detected in males and females for IGFBP-2 on Chromosomes 8, 11, 14, 17, and X, and for IGFBP-4 on Chromosome 4. Additional loci affecting IGFBPs acted in a sex-specific manner. The identified loci coincide in part with chromosomal regions controlling growth and obesity. Thus, multiple genes or pleiotropic gene effects may be assumed for these chromosomal regions. The identification of quantitative trait loci for IGFBPs as subcomponents of growth regulation and differentiation will further improve the understanding of complex trait regulation.

Animals↗
PubMed2001

Comparative mapping of five coding DNA sequences on cattle chromosomes 7 and 25.

Comparative mapping of four genes and one unknown coding DNA sequence in breakpoint positions of bovine chromosomes (BTA) 7 and 25 are presented. Performing a genome data base search five bovine expressed sequence tags from the MARC library matched with human genes coding for the general transcription factor IIIC polypeptide 1 (GTF3C1), the hypothetical protein KIAA0556, the interleukin 4 receptor (IL4R), the regulatory factor X-associated ankyrin-containing protein (RFXANK), and with an unknown human coding sequence partially homologous to the genomic cosmid clone R30923. Loci for these sequences were COMPASS predicted on BTA7 or BTA18 and to BTA18 or BTA25. Mapping was performed in a cattle-hamster somatic hybrid cell panel and a cattle-hamster 5000 rad whole genome radiation hybrid panel. GTF3C1, KIAA0556 and IL4R were assigned to the centromere region of BTA25 and RFXANK and R30923 close to the centromere of BTA7. The assignments contribute to the identification of evolutionary chromosome break points between human chromosomes 16 and 19 and BTA7, BTA18, and BTA25.

Animals↗
PubMed2001

Molecular genome analysis in livestock at the beginning of the new millennium.

Prerequisites, current status, further challenges and limitations in the application of molecular approaches for genome analysis in livestock are reviewed. Aspects of the utilization of mapped 'quantitative trait loci' (QTL) in breeding programmes and of the final identification cloning of the corresponding candidate genes are discussed.

Animals↗
PubMed2001

Structural and functional genomics in domestic animals: the way to understand the phenotype.

Molecular approaches to genome analysis in livestock are reviewed by discussing the contribution of molecular genome analysis to the identification of the genetic variation underlying phenotypic variation (structural genome analysis) and to the definition of the trait-associated and environment-affected gene expression (functional genome analysis) as an important prerequisite to understanding the formation of a phenotype. Aspects of using mapped 'quantitative trait loci' (QTL) or gene variants as well as the identified trait-associated and environment-affected gene expression profile in livestock production are expounded.

Journal Article↗
PubMed2000

Molecular characterization of STAT5A- and STAT5B-encoding genes reveals extended intragenic sequence homogeneity in cattle and mouse and different degrees of divergent evolution of various domains.

The STAT transcription factors form a family of signal transducers and activators of transcription. We sequenced the bovine STAT5B cDNA and both STAT5-encoding genes, STAT5A and STAT5B, representing the first complete description of any STAT5-encoding gene. DNA fiber FISH hybridization revealed that the genes reside only 40 kbp apart on BTA19. Both genes are segmented into 19 exons and all but two of the homologous exons are of equal size. The genes harbor a central block of nearly identical DNA sequence (97.5% sequence identity over 3373 bp), spanning from intron 5 to intron 9. Isolation and sequencing of the homologous segments from mouse revealed the same unusually high degree of intronic sequence conservation in these segments of the murine STAT5-encoding genes. However, the respective sequences are completely divergent between the two species. A comparison of the inter- and intragenic cDNA sequence preservation at nonsynonymous sites reveals that the DNA-binding domain is under the strongest selection pressure for both intergenic and factor-specific intragenic sequence preservation. The so-called "SH3" segment of the linker domain, in contrast, shows species-specific sequence identity in all but one amino acid residues in both factors, in cattle, human, and mouse. This indicates that the same species-specific selection pressure occurs on the linker domain from both factors, STAT5A and STAT5B. Thus, the comparison of evolutionary selection pressures resting on various domains suggests that the DNA-binding domain might contribute to differential DNA binding of STAT5A and STAT5B factors, while both might interact equally well with other cellular factors through a segment of the linker domain.

Amino Acid Sequence↗
PubMed2000

Single QTL effects, epistasis, and pleiotropy account for two-thirds of the phenotypic F(2) variance of growth and obesity in DU6i x DBA/2 mice.

Genes influencing body weight and composition and serum concentrations of leptin, insulin, and insulin-like growth factor I (IGF-I) in nonfasting animals were mapped in an intercross of the extreme high-growth mouse line DU6i and the inbred line DBA/2. Significant loci with major effects (F > 7.07) for body weight, obesity, and muscle weight were found on chromosomes 1, 4, 5, 7, 11, 12, 13, and 17, for leptin on chromosome 14, for insulin on chromosome 4, and for IGF-I on chromosome 10 at the Igf1 gene locus itself and on chromosome 18. Significant interaction between different quantitative trait loci (QTL) positions was observed (P < 0.01). Evidence was found that loci having small direct effect on growth or obesity contribute to the obese phenotype by gene-gene interaction. The effects of QTLs, epistasis, and pleiotropy account for 64% and 63% of the phenotypic variance of body weight and fat accumulation and for over 32% of muscle weight and serum concentrations of leptin, and IGF-I in the F(2) population of DU6i x DBA/2 mice. [The quantitative trait loci described in this paper have been submitted to the Mouse Genome Database.]

Animals↗
PubMed2000

Cis-acting elements regulating the placenta-specific promoter of the bovine Cyp19 gene.

Cyp19 encodes aromatase cytochrome P450, the key enzyme of oestrogen biosynthesis. In the bovine placenta, the majority of Cyp19 transcripts include a 5' untranslated region which is encoded by exon 1.1; this suggests that its 5'-flanking region is the predominant placental promoter. The aim of the present investigation was to examine the promoter activity of this region and to map cis-acting regulatory elements in order to improve our understanding of the complex regulation of this gene within the placenta. As an initial approach, human JEG-3 choriocarcinoma cells were transiently transfected with reporter-gene constructs consisting of different 5'-flanking sequences of exon 1.1 fused to the luciferase gene as a reporter. To localise and further characterise functional cis-acting elements, targeted point mutations and electrophoretic mobility-shift experiments were used. The data demonstrate, for the first time, (1) that the bovine exon 1.1 5'-flanking sequence is an active promoter, (2) that 404 bp of this region are sufficient for constitutive reporter-gene expression in JEG-3 cells and (3) that the region includes at least two different enhancer elements; the data also suggest (4) that one of these elements consists of the E-box motif CATGTG and that the second enhancer element includes the half-site hexameric sequence AGGTCA and additional nucleotides flanking this element upstream.

Animals↗
PubMed1999

Placenta-specific transcripts of the aromatase encoding gene include different untranslated first exons in sheep and cattle.

The aim of the present study was the characterization of the ovine aromatase cytochrome P450 encoding gene (Cyp19) and the analysis of its tissue-specific expression. Two loci with considerable sequence identity were found (Cyp19 and Cyp19b). From Cyp19, tissue-specific transcript variants with different untranslated first exons but identical coding regions could be identified. Cyp19b transcripts were not detected. In the sheep brain and ovarian granulosa cells transcript variants, starting with the untranslated exons 1.4 and 2, respectively, were preferentially found. Exons 1.2 and 1.3 which had been described in bovines could not be detected in sheep and the major 5' untranslated region of the bovine placental transcript, exon 1.1, was also not found to predominate in the sheep placenta. However this exon frequently was combined with a new untranslated exon (exon 1.1a) thus generating an alternative splice variant. The main placental transcripts in sheep had a different first exon (exon 1.5). Two alternatively spliced variants of this transcript were found with tissue-specific preference. From the present data it can be concluded: (a) that the ovine genome contains two copies of Cyp19 of which only one is transcribed and may encode a functional protein; and (b) that in spite of being closely related species, sheep and cattle have remarkable differences concerning tissue-specific transcript distribution and presumable promoter usage.

5' Untranslated Regions↗
PubMed1999

High-resolution human/goat comparative map of the goat polled/intersex syndrome (PIS): the human homologue is contained in a human YAC from HSA3q23.

The genetic and cytogenetic map around the chromosome 1 region shown to be linked with polledness and intersexuality (PIS) in the domestic goat (Capra hircus) was refined. For this purpose, a goat BAC library was systematically screened with primers from human coding sequences, scraped chromosome 1 DNA, bovine microsatellites from the region, and BAC ends. All the BACs (n = 30) were mapped by fluorescence in situ hybridization (FISH) on goat chromosome 1q41-q45. The genetic mapping of 30 new goat polymorphic markers, isolated from these BACs, made it possible to reduce the PIS interval to a region of less than 1 cM on goat chromosome 1q43. The PIS locus is now located between the two genes ATP1B and COP, which both map to 3q23 in humans. Genetic, cytogenetic, and comparative data suggest that the PIS region is now probably circumscribed to an approximately 1-Mb DNA segment for which construction of a BAC contig is in progress. In addition, a human YAC contig encompassing the blepharophimosis-ptosis-epicanthus-inversus region was mapped by FISH to goat chromosome 1q43. This human disease, mapped to HSA 3q23 and affecting the development and maintenance of ovarian function, could be a potential candidate for goat PIS.

Animals↗
PubMed1999

Fat storage capacity in growth-selected and control mouse lines is associated with line-specific gene expression and plasma hormone levels.

OBJECTIVE: For a detailed understanding of the complex traits growth and fat storage, a dissection into single genetic entities is mandatory. Therefore, blood plasma concentrations of hormones and the expression of selected genes were measured in extremely differentiated mouse lines. Genes were selected as candidates which might influence the complex traits body weight and fat accumulation, and which are located in chromosomal regions recently identified to affect trait differences between the lines. SUBJECTS AND MEASUREMENTS: The mouse lines were selected for high body weight (DU6), high carcass protein content (DU6P) and unselected controls (DUKs). In the selected lines DU6 and DU6P, mean body weights at the age of six weeks were about twice as high as the DUKs, whereas total fat weight was increased 2.2-fold in DU6 mice compared to DU6P and 3.2-fold in comparison to DUKs. Blood plasma concentrations of insulin-like growth factor 1 (IGF-1), growth hormone (GH), insulin and leptin, were measured in all lines at three weeks and at six weeks of age. Expression patterns of the genes encoding growth hormone (Gh), insulin-like growth factor 1 (Igf1), lipoprotein lipase (Lpl), glycerolphosphate dehydrogenase 1 (GDC-1), and adipocyte protein 2 (Ap2) were analyzed by Northern blot hybridization. RESULTS: In line DU6, highly significant increased concentrations of insulin and leptin were observed at six weeks of age; at this stage, IGF-1 concentrations were elevated in the two selected lines compared to controls with maximal concentrations of IGF-1 and GH in DU6P. The amount of mRNA for GH in the pituitary gland, for Igf1 in the liver and for LPL in epididymal fat tissue was significantly elevated in the two selected lines compared to controls at the age of three weeks, but not at six weeks. IGF-1 and GDC-1 mRNA concentrations were significantly higher in the DU6 mice than in the DU6P (P < 0.01) and the DUKs (P < 0.001) mice examined at both ages. CONCLUSIONS: The results prove line-specific concentrations of the analyzed hormones and the transcription amounts of Gh, Igf1, GDC-1 and Lpl. The measured differences are either direct genetic effects or secondary changes, resulting from different food consumption.

Adipocytes↗
PubMed1999

Detection of QTL for milk production traits in cattle by application of a specifically developed marker map of BTA6.

Interval mapping was carried out to identify quantitative trait loci (QTL) for milk production traits in five granddaughter design families of the German Holstein population. Fourteen randomly generated markers spanning the whole of BTA6 and six targeted microsatellite markers from BTA6q21-31 were included in the analysis. In one family a QTL with effects on milk fat yield and milk protein yield was mapped to the interval TGLA37-FBN13 (3 CM proximal to FBN13, lodscore 3.22) in the middle part of the chromosome. Although there are several reports about QTL with effects on milk production traits on BTA6 in the literature, a QTL with effects on milk fat and milk protein yield has not been previously described.

Animals↗
PubMed1999

Bovine chromosome 4 workshop: consensus and comprehensive linkage maps.

The report of the bovine chromosome 4 (BTA4) workshop is presented. Six laboratories contributed a total of 30,168 informative meioses from 62 loci. Twenty-two loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of BTA4. The remaining 40 loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 131.4 cM. The female map was 124.3 cM in length, while the male map was 134.3 cM. The comprehensive sex-averaged map spanned 141.6 cM. The length of the female and male comprehensive maps were 123.1 cM and 156.4 cM, respectively. Average genetic distance between loci was 6 and 2.3 cM for the consensus and comprehensive linkage maps, respectively.

Animals↗