ABSTRACT
A novel human X-linked gene shows placenta-specific expression and has been named PLAC1. The gene maps 65 kb telomeric to HPRT at Xq26 and has been completely sequenced at the cDNA and genomic levels. The mouse orthologue Plac1 maps to the syntenically equivalent region of the mouse X chromosome. In situ hybridization studies with the antisense mRNA during mouse embryogenesis detect Plac1 expression from 7.5 dpc (days postcoitum) to 14.5 dpc in ectoplacental cone, giant cells, and labyrinthine trophoblasts. The putative human and murine PLAC1 proteins are 60% identical and 77% homologous. Both include a signal peptide and a peptide sequence also found in an interaction domain of the ZP3 (zona pellucida 3) protein. These results make PLAC1 a marker for placental development, with a possible role in the establishment of the mother-fetus interface.
Subject(s)
Gene Expression Regulation, Developmental , Placenta/metabolism , Pregnancy Proteins/genetics , X Chromosome , Amino Acid Sequence , Animals , Base Sequence , Chromosome Mapping , Embryonic and Fetal Development , Expressed Sequence Tags , Giant Cells/metabolism , Humans , Mice , Molecular Sequence Data , Open Reading Frames , Pregnancy Proteins/chemistry , RNA, Antisense , RNA, Messenger/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Transcription, Genetic , Trophoblasts/metabolismABSTRACT
A method has been established to convert pYAC4-based linear yeast artificial chromosomes (YACs) into circular chromosomes that can also be propagated in Escherichia coli cells as bacterial artificial chromosomes (BACs). The circularization is based on use of a vector that contains a yeast dominant selectable marker (G418R), a BAC cassette and short targeting sequences adjacent to the edges of the insert in the pYAC4 vector. When it is introduced into yeast, the vector recombines with the YAC target sequences to form a circular molecule, retaining the insert but discarding most of the sequences of the YAC telomeric arms. YACs up to 670 kb can be efficiently circularized using this vector. Re-isolation of megabase-size YAC inserts as a set of overlapping circular YAC/BACs, based on the use of an Alu-containing targeting vector, is also described. We have shown that circular DNA molecules up to 250 kb can be efficiently and accurately transferred into E.coli cells by electroporation. Larger circular DNAs cannot be moved into bacterial cells, but can be purified away from linear yeast chromosomes. We propose that the described system for generation of circular YAC derivatives can facilitate sequencing as well as functional analysis of genomic regions.
Subject(s)
Chromosomes, Artificial, Yeast/genetics , Chromosomes, Bacterial/genetics , DNA, Circular/genetics , Genetic Vectors , Alu Elements , Electrophoresis, Gel, Pulsed-Field , Electroporation , Escherichia coli/genetics , Genetic Markers , Saccharomyces cerevisiae/genetics , Transformation, GeneticABSTRACT
Human sex chromosomes, which are morphologically and genetically different, share few regions of homology. Among them, only pseudoautosomal regions (PARs) pair and recombine during meiosis. To better address the complex biology of these regions, we sequenced the telomeric 400 kb of the long arm of the human X chromosome, including 330 kb of the human Xq/YqPAR and the telomere. Sequencing reveals subregions with distinctive regulatory and evolutionary features. The proximal 295 kb contains two genes inactivated on both the inactive X and Y chromosomes [ SYBL1 and a novel homologue ( HSPRY3 ) of Drosophila sprouty ]. The GC-rich distal 35 kb, added in stages and much later in evolution, contains the X/Y expressed gene IL9R and a novel gene, CXYorf1, only 5 kb from the Xq telomere. These properties make Xq/YqPAR a model for studies of region-specific gene inactivation, telomere evolution, and involvement in sex-limited conditions.
Subject(s)
Proteins/genetics , Telomere/genetics , X Chromosome/genetics , Y Chromosome/genetics , Base Composition , Blotting, Southern , Cell Line , Chromosome Mapping , Chromosomes, Artificial, Yeast , Dosage Compensation, Genetic , Humans , In Situ Hybridization, Fluorescence , Intracellular Signaling Peptides and Proteins , Membrane Proteins/genetics , Membrane Proteins/metabolism , Molecular Sequence Data , Proteins/metabolism , R-SNARE Proteins , Repetitive Sequences, Nucleic Acid , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA , Telomere/metabolism , X Chromosome/metabolism , Y Chromosome/metabolismABSTRACT
SYBL1 is a gene in the 320kb human pseudo-autosomal region at the terminus of Xq and Yq. In contrast to other pseudoautosomal genes, SYBL1 is inactivated on one X in every female cell, and is also inactive on the Y of male cells. Hypermethylation of the CpG island associated with the human gene is involved in this phenomenon. In an attempt to further examine its regulation, the genomic organization of the X-linked mouse Sybl1 homolog was analyzed and compared with the human gene. Human and mouse show the same exon number, exon-intron junctions and a highly conserved basal promoter. The structural and functional conservation of basal regulatory regions suggests that inactivation is imposed by similar auxiliary epistatic regulatory mechanism.
Subject(s)
Genes/genetics , Membrane Proteins/genetics , Animals , Base Sequence , Binding Sites , Blotting, Northern , Chloramphenicol O-Acetyltransferase/genetics , Chloramphenicol O-Acetyltransferase/metabolism , DNA/chemistry , DNA/genetics , Exons , Gene Expression , Gene Expression Regulation, Developmental , HeLa Cells , Humans , Introns , Male , Mice , Molecular Sequence Data , Promoter Regions, Genetic/genetics , R-SNARE Proteins , RNA, Messenger/genetics , RNA, Messenger/metabolism , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Regulatory Sequences, Nucleic Acid/genetics , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Tissue Distribution , Transcription, GeneticABSTRACT
Observation on body weight gain, blood glucose levels, and responses to a glucose challenge in ob/ob mice adrenalectomized at five months of age, demonstrate that removal of the adrenals of older mice retains the potential to lower serum glucose levels and depress body weight gain seen in young ob/ob mice adrenalectomized at two months of age. These findings suggest that the adrenals continue to play a role in body weight gain and hyperglycemia of the ob/ob mouse up to five months of age.
Subject(s)
Adrenalectomy , Hyperglycemia/etiology , Mice, Obese/physiology , Age Factors , Animals , Blood Glucose/metabolism , Body Weight , Female , Glucose Tolerance Test , Mice , Mice, Obese/bloodABSTRACT
The estrogen-like activity of delta-9-tetrahydrocannabinol (delta9-THC), an active component of marihuana, as measured by uterine weight gain and vaginal smear techniques in ovariectomized rats, is reflected in histological examination of uterine and vaginal tissues. Doses of 1, 2.5, and 10 milligrams of delta9-THC per kilogram elicit hypertrophy and hyperplasia of the uterus; the dose of 2.5 milligrams per kilogram is most effective. There is an increase in stratification of vaginal epithelium with doses of 2.5 and 10 milligrams per kilogram; cornifying cells are seen with 2.5 milligrams per kilogram.
