The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
C S Bawden - One of the best experts on this subject based on the ideXlab platform.
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expression of a wool intermediate filament Keratin transgene in sheep fibre alters structure
Transgenic Research, 1998Co-Authors: C S Bawden, Barry C Powell, S K Walker, George E RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form heterodimers with much of the expressed endogenous Keratin Type I IF. In comparison with non-transgenic sheep, fewer IF microfibrils were visible in the cortical cells of fibres from transgenics. The combined effect on fibre structure was disruption of the formation of orthocortical and paracortical cells in the fibre cortex, a factor which could account for the reduction in fibre crimp. No effects upon transcript or protein levels, or fibre microstructure or macrostructure were observed in transgenic sheep expressing the transgene at lower levels, indicating that subtle changes to the gene expression profile in sheep wool follicles can be tolerated. The data here also illustrate that control over endogenous transcript levels in the cortex results when factors acting on the endogenous Keratin Type I, Keratin Type II and KAP gene sequences are sequestered by the active K2.10 transgene locus. Moreover, interference to a transcriptional hierarchy shared by Keratin and KAP genes may occur prior to establishment of the orthocortical and paracortical compartments of the follicle cortex, at the level of the chromatin.
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Expression of a Wool Intermediate Filament Keratin Transgene in Sheep Fibre Alters Structure
Transgenic Research, 1998Co-Authors: C S Bawden, S K Walker, B.c. Powell, G.e. RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form h...
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transgenic sheep and wool growth possibilities and current status
Reproduction Fertility and Development, 1994Co-Authors: Barry C Powell, C S Bawden, A V Sivaprasad, S K Walker, George E RogersAbstract:Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool Keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first Keratin gene construct, a wool Keratin Type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.
George E Rogers - One of the best experts on this subject based on the ideXlab platform.
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expression of a wool intermediate filament Keratin transgene in sheep fibre alters structure
Transgenic Research, 1998Co-Authors: C S Bawden, Barry C Powell, S K Walker, George E RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form heterodimers with much of the expressed endogenous Keratin Type I IF. In comparison with non-transgenic sheep, fewer IF microfibrils were visible in the cortical cells of fibres from transgenics. The combined effect on fibre structure was disruption of the formation of orthocortical and paracortical cells in the fibre cortex, a factor which could account for the reduction in fibre crimp. No effects upon transcript or protein levels, or fibre microstructure or macrostructure were observed in transgenic sheep expressing the transgene at lower levels, indicating that subtle changes to the gene expression profile in sheep wool follicles can be tolerated. The data here also illustrate that control over endogenous transcript levels in the cortex results when factors acting on the endogenous Keratin Type I, Keratin Type II and KAP gene sequences are sequestered by the active K2.10 transgene locus. Moreover, interference to a transcriptional hierarchy shared by Keratin and KAP genes may occur prior to establishment of the orthocortical and paracortical compartments of the follicle cortex, at the level of the chromatin.
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transgenic sheep and wool growth possibilities and current status
Reproduction Fertility and Development, 1994Co-Authors: Barry C Powell, C S Bawden, A V Sivaprasad, S K Walker, George E RogersAbstract:Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool Keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first Keratin gene construct, a wool Keratin Type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.
Klaus Weber - One of the best experts on this subject based on the ideXlab platform.
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Terrestrial vertebrates have two Keratin gene clusters; striking differences in teleost fish.
European journal of cell biology, 2005Co-Authors: Alexander Zimek, Klaus WeberAbstract:Keratins I and II form the largest subgroups of mammalian intermediate filament (IF) proteins and account as obligatory heteropolymers for the Keratin filaments of epithelia. All human Type I genes except for the K18 gene are clustered on chromosome 17q21, while all Type II genes form a cluster on chromosome 12q13, that ends with the Type I gene K18. Highly related Keratin gene clusters are found in rat and mouse. Since fish seem to lack a Keratin II cluster we screened the recently established draft genomes of a bird (chicken) and an amphibian (Xenopus). The results show that Keratin I and II gene clusters are a feature of all terrestrial vertebrates. Because hair with its multiple hair Keratins and inner root sheath Keratins is a mammalian acquisition, the Keratin gene clusters of chicken and Xenopus tropicalis have only about half the number of genes found in mammals. Within the Type I clusters all genes have the same orientation. In Type II clusters there is a rare gene of opposite orientation. Finally we show that the genes for Keratins 8 and 18, which are the first expression pair in embryology, are not only adjacent in mammals, but also in Xenopus and three different fish. Thus neighboring K8 and K18 genes seem a feature shared by all vertebrates. In contrast to the two well defined Keratin gene clusters of terrestrial vertebrates, three teleost fish show an excess of Type I over Type II genes, the lack of a Keratin Type II gene cluster and a striking dispersal of Type I genes, that are probably the result of the teleost-specific whole genome duplication followed by a massive gene loss. This raises the question whether Keratin gene clusters extend beyond the ancestral bony vertebrate to cartilage fish and lamprey. We also analyzed the complement of non-Keratin IF genes of the chicken. Surprisingly, an additional nuclear lamin gene, previously overlooked by cDNA cloning, is documented on chromosome 10. The two splice variants closely resemble the lamin LIII a+b of amphibia and fish. This lamin gene is lost on the mammalian lineage. r 2005 Elsevier GmbH. All rights reserved.
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genes coding for intermediate filament proteins common features and unexpected differences in the genomes of humans and the teleost fish fugu rubripes
Journal of Cell Science, 2003Co-Authors: Alexander Zimek, Reimer Stick, Klaus WeberAbstract:We screened the genomic sequences of the teleost fish Fugu rubripes for genes that encode cytoplasmic intermediate filament (IF) proteins. Here, we compare the number of genes per subfamily (I to IV) as well as the gene mapping in the human and fish genomes. There are several unexpected differences. F. rubripes has a sizeable excess of Keratin Type I genes over Keratin Type II genes. Four of the six Keratin Type II genes map close to four Keratin Type I genes. Thus, a single Keratin II gene cluster (as in mammals) seems excluded. Although a continuous genome sequence is not yet available for F. rubripes, it is difficult to see how all 19 Keratin Type I genes can be collected as in the human genome into a single cluster without the presence of Type II genes and various unrelated genes. F. rubripes has more Type III and Type IV genes than humans. Some of the Type IV genes acquired additional novel intron positions. One gene even harbors (in addition to the two Type IV introns) three novel introns and three introns usually present only in mammalian and F. rubripes Type I-III genes. This mixture of Type IV and Type I-III intron positions poses a problem for the traditional view that the first Type IV gene arose in evolution by a mRNA-mediated translocation event. In the 42 F. rubripes genes analysed here, there are several differences in intron patterns compared with mammalian genes. Most correspond to additional introns in the fish genes. A search for genes encoding nuclear lamins reveals the four established fish lamins (A, B1, B2 and LIII) as well as an unexpected second lamin A.
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common and variant properties of intermediate filament proteins from lower chordates and vertebrates two proteins from the tunicate styela and the identification of a Type IIi homologue
Journal of Cell Science, 1998Co-Authors: Dieter Riemer, Klaus WeberAbstract:The chordates combine the vertebrates and the invertebrate phyla of the cephalo- and urochordates (tunicates). Two cytoplasmic intermediate filament (IF) proteins of the urochordate Styela plicata are characterized by cDNA cloning, gene organization, tissue specific expression patterns in the adult animal and the self assembly properties of the recombinant proteins. In line with metazoan phylogeny St-A and St-B have the short length version of the coil 1b domain found in all vertebrate and cephalochordate IF proteins while protostomic IF proteins have the longer length version with an extra 42 residues. St-A is the first IF protein from a lower chordate which can be unambiguously related to a particular vertebrate IF subfamily. St-A shares 46% sequence identity with desmin, displays the N-terminal motif necessary for filament assembly of Type III proteins and forms normal homopolymeric 10 nm filaments in vitro. St-A but not St-B is present in smooth muscle cells of the body wall musculature. St-A and St-B are found as separate networks in some interior epithelia. St-B shares 30 to 35% identity with Keratin 8, St-A and desmin and does not form IF under in vitro assembly conditions. Its relation to a particular vertebrate IF Type or to the eight currently known IF proteins from the cephalochordate Branchiostoma remains unresolved. The striking relation between St-A and desmin predicts that the common progenitor of the urochordate (tunicate) and the cephalochordate/vertebrate lineages already possessed a Type III homologue. Unlike in vertebrates intron patterns cannot be used to classify the tunicate IF genes. Although St-A is a Type III homologue its gene shows an intron position which in vertebrates is restricted to Keratin Type II genes.
Barry C Powell - One of the best experts on this subject based on the ideXlab platform.
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expression of a wool intermediate filament Keratin transgene in sheep fibre alters structure
Transgenic Research, 1998Co-Authors: C S Bawden, Barry C Powell, S K Walker, George E RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form heterodimers with much of the expressed endogenous Keratin Type I IF. In comparison with non-transgenic sheep, fewer IF microfibrils were visible in the cortical cells of fibres from transgenics. The combined effect on fibre structure was disruption of the formation of orthocortical and paracortical cells in the fibre cortex, a factor which could account for the reduction in fibre crimp. No effects upon transcript or protein levels, or fibre microstructure or macrostructure were observed in transgenic sheep expressing the transgene at lower levels, indicating that subtle changes to the gene expression profile in sheep wool follicles can be tolerated. The data here also illustrate that control over endogenous transcript levels in the cortex results when factors acting on the endogenous Keratin Type I, Keratin Type II and KAP gene sequences are sequestered by the active K2.10 transgene locus. Moreover, interference to a transcriptional hierarchy shared by Keratin and KAP genes may occur prior to establishment of the orthocortical and paracortical compartments of the follicle cortex, at the level of the chromatin.
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transgenic sheep and wool growth possibilities and current status
Reproduction Fertility and Development, 1994Co-Authors: Barry C Powell, C S Bawden, A V Sivaprasad, S K Walker, George E RogersAbstract:Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool Keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first Keratin gene construct, a wool Keratin Type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.
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Characterization of a hair (wool) Keratin intermediate filament gene domain.
The Journal of investigative dermatology, 1994Co-Authors: Barry C Powell, Juliana S. BeltrameAbstract:Abstract In epithelial differentiation Keratin intermediate filament genes are expressed in multifarious tissue-specific and stage-specific patterns. Pairs of Type I and Type II intermediate filament genes, belonging to multigene families, are coordinately regulated, and 4–5 genes of each Type are expressed in the hair follicle. Accumulating chromosomal mapping data points to a major locus for each intermediate filament multigene family on separate chromosomes. In this report we describe the isolation of a sheep hair Keratin cosmid by chromosome walking that overlaps two previously described cosmids and establishes a continuous 100-kb segment of cloned DNA containing three hair and three hair-like Type II intermediate filament Keratin genes. A new hair Keratin Type II intermediate filament gene, KRT2.11 , is located in the middle of the cluster, and partial sequence data reveal a striking conservation of its predicted N-terminal region with other sheep hair Keratin Type II intermediate filament proteins. Expression analyses demonstrate the presence of a 2.4-kb KRT2.11 transcript in wool follicle RNA and show that expression occurs in the follicle cortical Keratinocytes above the dermal papilla. The three hair genes are clustered within about 40 kb and flanked by hair-like genes that are not expressed in the hair follicle, thereby demarcating a hair Keratin gene domain.
S K Walker - One of the best experts on this subject based on the ideXlab platform.
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expression of a wool intermediate filament Keratin transgene in sheep fibre alters structure
Transgenic Research, 1998Co-Authors: C S Bawden, Barry C Powell, S K Walker, George E RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form heterodimers with much of the expressed endogenous Keratin Type I IF. In comparison with non-transgenic sheep, fewer IF microfibrils were visible in the cortical cells of fibres from transgenics. The combined effect on fibre structure was disruption of the formation of orthocortical and paracortical cells in the fibre cortex, a factor which could account for the reduction in fibre crimp. No effects upon transcript or protein levels, or fibre microstructure or macrostructure were observed in transgenic sheep expressing the transgene at lower levels, indicating that subtle changes to the gene expression profile in sheep wool follicles can be tolerated. The data here also illustrate that control over endogenous transcript levels in the cortex results when factors acting on the endogenous Keratin Type I, Keratin Type II and KAP gene sequences are sequestered by the active K2.10 transgene locus. Moreover, interference to a transcriptional hierarchy shared by Keratin and KAP genes may occur prior to establishment of the orthocortical and paracortical compartments of the follicle cortex, at the level of the chromatin.
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Expression of a Wool Intermediate Filament Keratin Transgene in Sheep Fibre Alters Structure
Transgenic Research, 1998Co-Authors: C S Bawden, S K Walker, B.c. Powell, G.e. RogersAbstract:Alteration of the protein composition of the wool fibre via transgenesis with sheep wool Keratin and Keratin associated protein (KAP) genes may lead to production of fibre Types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool Type II intermediate filament (IF) Keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical Type I (p < 0.05) and Type II (p < 0.01) Keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the Keratin Type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of Keratin Type II IF protein, it appeared unable to form h...
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transgenic sheep and wool growth possibilities and current status
Reproduction Fertility and Development, 1994Co-Authors: Barry C Powell, C S Bawden, A V Sivaprasad, S K Walker, George E RogersAbstract:Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool Keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first Keratin gene construct, a wool Keratin Type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.
