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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new locus in Drosophila melanogaster that is required for the correct expression of segmental identity has been discovered. The new locus, termed polyhomeotic (ph), is X-linked and maps cytologically to bands 2D2-3. Homozygous ph flies have homeotic transformations similar to those of known dominant gain of function mutants in the Antennapedia and bithorax complexes (ANT-C, BX-C), and in addition show loss of the humerus. ph interacts with three other similar mutations: Polycomb (Pc), Polycomblike (Pcl), and extra sex comb (esc), and acts as a dominant enhancer of Pc. The expression of ph depends on the ANT-C and BX-C dosage. ph has no embryonic phenotype, but temperature shift studies on ph2 show that the ph+ product is required during embryogenesis and larval development. We propose that ph mutants in some way disrupt the normal expression of the ANT-C and BX-C, and, therefore, that ph+ is needed for maintenance of segmental identity.
Mol Gen Genet 1985
PMID:Polyhomeotic: a gene of Drosophila melanogaster required for correct expression of segmental identity. 392 Apr 76

Hemophilia B or Christmas disease is an X-linked condition caused by absent or reduced levels of functional coagulation factor IX. Based upon the peptide sequence of bovine factor IX, we synthesized a 17-base pair oligonucleotide probe to screen a human liver cDNA library. A recombinant clone was identified with a 917-nucleotide insert whose sequence corresponds to 70% of the coding region of human factor IX. This factor IX cDNA was used to probe restriction endonuclease digested human DNA to identify a Taq I polymorphism associated with the genomic factor IX gene as well as to verify that there is a single copy of this gene per haploid genome. The factor IX cDNA was also used to map the locus for factor IX to a region from Xq26 to Xqter. The cloning of human factor IX cDNA and identification of a Taq I polymorphism and its regional localization will provide a means to study the molecular genetics of hemophilia B and permit linkage analysis with nearby loci.
Somat Cell Mol Genet 1984 Sep
PMID:Isolation and characterization of human factor IX cDNA: identification of Taq I polymorphism and regional assignment. 608 57

The effect of uv irradiation on the recovery of DNA synthesis is examined in a population of hare fibroblasts exhibiting heterozygosity with reference to the X-linked enzyme, glucose-6-phosphate-dehydrogenase (G-6-PD). These cells have been grown from skin explants of a hybrid female cross between Lepus timidus (female) and L. europaeus (male), the former carrying the G-6-PD gene for the slow-moving "T" variant and the latter with the fast-moving "E" variant gene. The hybrid, therefore, exhibits genetic mosaicism due to random inactivation in each cell, of one of the two X chromosomes in the embryonic stage. Exponentially growing cells from 13 fibroblast strains, comprising a wide range of E to T ratios, were exposed to moderately low dose of uv irradiation (6 J/m2). The recovery in DNA synthesis during the 2- to 8-h postirradiation period was calculated as the mean percentage rates of [3H]thymidine incorporated during the time as compared to the unirradiated zero-time controls. The results show a statistically significant positive correlation as determined by linear regression analysis between the levels of E and the rate of recovery in DNA synthesis. This is valid also at the higher dose of uv (21 J/m2). These results strengthen our earlier observations with 25-hydroxycholesterol that in the in vitro system the cell expressing the E variant is perhaps more resistant to cytotoxic agents. This also indicates that various factors contribute to the development of monotypism which include cell growth, cell death, mutation, and selection, to name a few.
Exp Mol Pathol 1984 Dec
PMID:Mosaicism in female hybrid hares heterozygous for glucose-6-phosphate dehydrogenase. V. The recovery of DNA synthesis of hare fibroblasts after ultraviolet irradiation. 651 May 8

To identify specific cellular factors which could be required during the synthesis of retroviral DNA, we have studied the replication of murine leukemia virus in mouse cells temperature sensitive for cell DNA synthesis (M. L. Slater and H. L. Ozer, Cell 7:289-295, 1976) and in several of their revertants. This mutation has previously been mapped on the X chromosome. We found that a short incubation of mutant cells at a nonpermissive temperature (39 degrees C) during the early part of the virus cycle (between 0- to 20-h postinfection) greatly inhibited virus production. This effect was not observed in revertant or wild-type cells. Molecular studies by the Southern transfer procedure of the unintegrated viral DNA synthesized in these cells at a permissive (33 degrees C) or nonpermissive temperature revealed that the levels of linear double-stranded viral DNA (8.8 kilobase pairs) were nearly identical in mutant or revertant cells incubated at 33 or 39 degrees C. However, the levels of two species of supercoiled viral DNA (with one or two long terminal repeats) were significantly lower in mutant cells incubated at 39 degrees C than in mutant cells incubated at 33 degrees C or in revertant cells incubated at 39 degrees C. Pulse-chase experiments showed that linear viral DNA made at 39 degrees C could not be converted into supercoiled viral DNA in mutant cells after a shift down to 33 degrees C. In contrast, such conversion was observed in revertant cells. Restriction endonuclease analysis did not detect differences in the structure of linear viral DNA made at 39 degrees C in mutant cells as compared to linear viral DNA isolated from the same cells at 33 degrees C. However, linear viral DNA made at 39 degrees C in mutant cells was poorly infectious in transfection assays. Taken together, these results strongly suggest that this X-linked gene, affecting mouse cell DNA synthesis, is operating in the early phase of murine leukemia virus replication. It seems to affect the level of production of unintegrated linear viral DNA only slightly while greatly reducing the infectivity of these molecules. In contrast, the accumulation of supercoiled viral DNA and subsequent progeny virus production are greatly reduced. Our pulse-chase experiments suggest that the apparent, but not yet identified, defect in linear viral DNA molecules might be responsible for their subsequent impaired circularization.
Mol Cell Biol 1984 Jan
PMID:An X-linked gene affecting mouse cell DNA synthesis also affects production of unintegrated linear and supercoiled DNA of murine leukemia virus. 653 58

A model is suggested for mammalian male determination based on interactions postulated to occur among an autosomal repressor gene, an X-linked male-determining gene termed Tdx, and multiple copies of certain DNA sequences on the Y chromosome that do not code for any protein. The repressor, synthesised in limited amounts, has higher affinity for the Y-linked sequences than for Tdx and its affinity for Tdx is greater than that of RNA polymerase. In XY cells the Y effectively binds all available repressor, permitting transcription of Tdx to occur. In XX cells, since competition from the Y-linked high-affinity sequences is absent, the repressor binds to Tdx and prevents transcription. As a result of this competition between Tdx and the Y-linked high-affinity sites for limiting concentrations of the autosomal repressor, the product of the Tdx gene (TDX) is synthesized in the male but not in the female. It is suggested that in determination of the male sex, the role of the Y chromosome is to serve as a sink for the Tdx repressor. The proposed interactions provide a plausible explanation for the genetic properties of several anomalies of sexual development in mouse, man, and other mammals. The model suggests that the postulated multiple, high-affinity sequences on the Y chromosome of the mouse are included among the DNA sequences referred to as the Sxr-Bkm sequences.
Mol Gen Genet 1984
PMID:A model for mammalian male determination based on a passive Y chromosome. 658 8

The fragile X chromosome, associated with a common form of X-linked mental retardation, is cytologically observed most often as a gap or fragile site near the distal end of the long arm in band Xq28. Expression of this site is variable and dependent upon lowered thymidylate pools. In order to examine the behavior of this fragile site in a foreign genetic background, interspecific somatic cell hybrids were isolated from crosses of hamster cells and lymphoblastoid cells derived from male patients with fragile X-linked mental retardation. Three hybrid cell lines containing the human X chromosome were analyzed. Following induction with 5-fluorodeoxyuridine, all three hybrids expressed the fragile site in approximately 10% of the metaphases examined. Our data indicate that expression of the fragile site in band Xq27 is dependent neither on the integrity of the human genome nor on the expression of human autosomal genes.
Somat Cell Mol Genet 1984 Jul
PMID:Expression of fragile X chromosome in human-rodent somatic cell hybrids. 658 93

Mutations in an X-linked gene, gust-A, block the responses of Drosophila melanogaster to a group of pyranose sugars. It is shown that the behavioural effects of this mutation are correlated with a loss of electrical responses in taste receptors. The mutation affects the chemoacceptors for pyranose sugars leaving the furanose acceptors intact.
Mol Gen Genet 1981
PMID:A gustatory mutant of Drosophila defective in pyranose receptors. 678 93

Five X-linked, recessive alleles were isolated which suppressed both the pupal and adult coloration phenotypes of the black mutation. Electron micrographs of shed puparia revealed that the aberrant sclerotization of the black cuticle is also suppressed. Amino acid analysis indicated that suppression is associated with an increased concentration of beta-alanine, an amino acid known to be deficient in black. The suppressor locus mapped at the tip of the X, to the right of scute, and intragenic complementation was observed among the alleles.
Mol Gen Genet 1981
PMID:Intergenic suppression of the black mutation of Drosophila melanogaster. 679 39

The rRNA genes (rDNA) in Drosophila melanogaster are found in two clusters, one on the X and one on the Y chromosome. We have compared the ribosomal protein composition of wild-type Oregon-R flies containing both X-linked and Y-linked rDNA with that of flies containing only the Y-linked rDNA by two-dimensional polyacrylamide gel electrophoresis. Four basic proteins (1, 2/3, L4, and L7) normally present in wild-type flies were either electrophoretically not detectable (1, 2/3, and L4) or marginally detectable (L7) in flies with only Y-linked rDNA. No additional proteins were observed in these flies. However, immunodiffusion assays using specific antibodies raised against purified protein L4 confirmed that L4 was present but in relatively lower amounts in these Y-linked rDNA flies. An investigation was carried out to determine whether these electrophoretically undetectable proteins were more readily lost during ribosome preparation and hence were not readily detectable in the 80S particles by gel electrophoresis or whether they had been modified. Thus the proteins in the post-ribosomal cell supernatant and the high salt sucrose gradient were analyzed by two-dimensional gel electrophoresis and immunochemical assays with antibodies raised against protein L4 and total 80S ribosomal proteins. The experimental evidence indicates that there is a small amount of protein L4 and probably proteins 1, 2/3, and L7 in flies with only Y-linked rDNA but significantly less of these proteins than in wild-type flies.
Mol Gen Genet 1982
PMID:Decrease in ribosomal proteins 1, 2/3, L4, and L7 in Drosophila melanogaster in the absence of X rDNA. 681 32

Purified RNA polymerase II (RNA nucleotidyl-transferase; EC 2.7.7.6) extracted from flies possessing lesions in the Ultrabithorax-like (Ubl) locus of Drosophila melanogaster has altered activity in vitro (Greenleaf et al. 1979, 1980; Coulter and Greenleaf 1982). This strongly suggests that the Ubl locus encodes a subunit of RNA polymerase II. Ethyl methanesulfonate was used to induce a temperature-sensitive mutation in this locus. Flies either homozygous or hemizygous for this new X-linked mutation (Ublts) display viability comparable to that of wild-type flies at 22 degrees C but are lethal at 29 degrees C. The temperature-sensitive period for Ublts flies is between gastrulation (6 h, 29 degrees C) and pupation (9-10 days, 22 degrees C). Zygotes shifted from 22 degrees C to 29 degrees C die at either the late embryonic or first larval instar stage while temperature shifts of second and third instar larvae result in the lethal phase occurring at the pupal stage. Most pupae shifted from 22 degrees C to 29 degrees C undergo metamorphosis and eclose as adults. Adults are viable if placed at 29 degrees C; however, all females and some males become sterile if maintained at this temperature. Somatic recombination was used to induce clones homozygous for a null allele of Ubl at different stages of development. Clones of this null allele appear to be cell lethal indicating that the Ubl+ gene product is required at all stages of development. The viability of Ublts pupae and adults at 29 degrees C may result from only a partial reduction in activity caused by the mutation at this nonpermissive temperature.
Mol Gen Genet 1982
PMID:Developmental genetics of a temperature-sensitive RNA polymerase II mutation in Drosophila melanogaster. 681 24


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