Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transgenic mice have become invaluable for analysing gene function and regulation in vivo. However, the size of constructs injected has been limited by the cloning capacity of conventional vectors, a constraint that could be overcome with yeast artificial chromosomes (YACs). We investigated the feasibility of making transgenic mice with YACs by pronuclear injection of a small YAC carrying a gene encoding tyrosinase. Use of a vector with a conditional centromere allowed fifteenfold amplification of the YAC in yeast and its recovery in high yield. The albino phenotype of the recipient mice was rescued demonstrating the correct expression of the tyrosine gene from the construct. Furthermore, the telomeric sequences added by the yeast integrated into the mouse genome and did not reduce efficiency of integration. Using this technique future experiments with longer YACs will allow the expression of gene complexes such as Hox and the globin gene clusters to be analysed in transgenic animals.
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PMID:Transgenic mice generated by pronuclear injection of a yeast artificial chromosome. 162 Jun 4

RT6 is a T cell membrane protein that has attracted interest because a defect in RT6 expression is associated with susceptibility to autoimmune type I diabetes in DP-BB rats and NOD mice. Using PCR screening of human/rodent somatic cell hybrids and fluorescence in situ hybridization, we have determined that the gene for the human RT6 homologue is located at 11q13, centromeric to the gene for tyrosinase (TYR, albino locus) and telomeric to that for fibroblast growth factor 4 (FGF4). The data suggest that the human RT6 gene constitutes a new linkage group with TYR and the gene for olfactory marker protein (OMP) on 11q, which has a counterpart in mouse chromosome 7. Thus, in the human, the RT6 locus is dissociated from the hemoglobin beta chain locus (HBB) and its neighboring conserved linkage group at 11p15, in contrast to the mouse, in which RT6 shows a tighter linkage to Hbb than to Tyr. The results support the conclusion that there has been considerable intrachromosomal reshuffling of linked genes since the divergence of primates and rodents.
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PMID:Assignment of the human RT6 gene to 11q13 by PCR screening of somatic cell hybrids and in situ hybridization. 828 46

Olfactory marker protein (OMP) shows olfactory neuron-specific expression in rodents. We recently reported tight linkage on mouse chromosome 7 of OMP to the shaker-1 deafness mutant, between the tyrosinase and globin loci. Here we isolate and map the human homologue. Our results show that OMP maps immediately centromeric to tyrosinase on the long arm of human chromosome 11. Genetic linkage to this region has recently been established for Usher Syndrome Type I, an autosomal recessive blindness and deafness disorder and a putative homologue of the shaker-1 mutant. OMP is thus a candidate gene for both congenital deafness defects.
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PMID:Human olfactory marker protein maps close to tyrosinase and is a candidate gene for Usher syndrome type I. 849 99

Using 180 F2 progeny of a C57BL6/J >< CAST/Ei tub/+F1 intersubspecific intercross, a map of 28 molecular markers (including eight genes) on chromosome 7 surrounding the tub locus was generated. Using 33 obese F2 progeny, tub was localized approximately 50-52 cM distal to the centromere on mouse chromosome 7 in the interval defined proximally by hemoglobin beta (Hbb), D7Mit38, D7Mit2l7, D7Mit37, D7Mit96, and D7Mit33 and distally by D7Mit98. Using 39 obese F2 progeny from a similar intersubspecific intercross, a telomeric boundary of the interval defining tub was defined by D7Mit53; the order centromere-Hbb/tub-D7Mit53/ D7Mit328/D7Mit220-parathyroid hormone (Pth)-calcitonin (Calc)-zona pellucida 2 (2p2) was established. By combining the data from the two crosses, the most likely gene order on mouse chromosome 7 is centromere-Hbb-tub-Pth-Calc, thus making it likely that the human homolog of tub resides on 17p15, where the gene order HBB-PTH-CALC is conserved. Assignment of the human tubby homolog to 17p15 allows selection and development of polymorphic molecular markers that can be used to examine segregation of a human homolog of tubby in pedigrees segregating for obesity. The gene sulfonylurea receptor was eliminated as a candidate gene for tubby on the basis of its map position, approximately 3.1 +/- 3.1 cM centromeric of tyrosinase and approximately 14.9 +/- 4.8 cM centromeric of Hbb.
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PMID:Molecular mapping of the tubby (tub) mutation on mouse chromosome 7. 883 47

During the pachytene stage of meiotic prophase in male mammals, the X and Y chromosomes become transcriptionally inactive and establish a chromatin domain, the sex body, that is visually distinct from the transcriptionally active autosomes. We used objective criteria to assess these chromatin differences by DNase I sensitivity (DS) of sex chromosome and autosomal sequences at both the cytological and molecular levels. For cytological studies, in situ nick translation techniques were used on air-dried preparations of testicular cells. For molecular studies, nuclei from pachytene spermatocytes were subjected to nuclease sensitivity assays. Both sex-linked and autosomal sequences were assessed, including some gene sequences that are expressed and some that are not expressed in pachytene spermatocytes. There was a wide range of DS in different genomic sequences; however, the sex-linked sequences generally were less nuclease sensitive than were autosomal sequences. Interestingly, a hot spot of recombination (within the Eb gene) showed a high level of nuclease sensitivity, while a cold spot of recombination (centromeric satellite region) exhibited lower sensitivity, more similar to that of sex-linked sequences. We also examined the nuclease sensitivity of a tyrosinase transgene insert, TyBS. In one line of mice, the transgene insert is X-linked, whereas in another, it is autosomal. The transgene was less nuclease sensitive when X-linked than as an autosomal insert. These results support the hypothesis that in pachytene spermatocytes the XY chromosome pair is more condensed and inaccessible to enzymatic digest, whereas the autosomal chromatin is in a more open configuration. In addition, we examined the nuclease sensitivity of some of the same genes in the earlier leptotene/zygotene prophase stage, when the sex chromatin is not maximally condensed. We found that while autosomal gene nuclease sensitivity was equivalent to that at the pachytene stage, X-linked sequences were more nuclease sensitive. Overall, these differences in chromatin nuclease sensitivity correlate with differences in meiotic recombination activity and may be mechanistically related.
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PMID:Chromatin configuration during meiosis I prophase of spermatogenesis. 940 97

Urodele amphibians (newts and salamanders) are important animal models for understanding regeneration mechanisms and genome evolution. We constructed ideograms of BrdU/dT- and C-banded karyotypes in the Japanese fire-belly newt, Cynops pyrrhogaster, which is useful as a model animal with extremely high ability of regeneration. We also established a high-resolution FISH mapping system for newts, and localized satellite DNA sequences, 18S rDNAs, telomeric (TTAGGG)n repeats and seven functional genes, including genes associated with lens regeneration, tyrosinase and two types of gamma crystallins, to chromosomes of the newt. The 18S rDNAs were localized to three chromosomal pairs in males, whereas the chromosomal locations were highly variable in females. No hybridization signals were detected for the telomeric (TTAGGG)n sequence. All three lens regeneration-related genes were mapped on the short arm of chromosome 7, suggesting that the location of the genes in the same linkage group may be correlated with the regulation of gene expression associated with chromatin dynamics in interphase nuclei during regeneration. The chromosomal distribution and nucleotide sequences of pericentric satellite DNA sequences were well conserved between C. pyrrhogaster and European newts; in contrast, there was species specificity of nucleotide sequences for centromere-specific satellite DNAs.
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PMID:Establishment of high-resolution FISH mapping system and its application for molecular cytogenetic characterization of chromosomes in newt, Cynops pyrrhogaster (Urodela, Amphibia). 1752 30