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J Skowronski

Publications and source records attributed to J Skowronski.

14 recordsLinked to original sources
PubMed1992

Gene expression during preimplantation mouse development.

To develop a resource for the identification and isolation of genes expressed in the early mammalian embryo, large and representative cDNA libraries were constructed from unfertilized eggs, and two-cell, eight-cell, and blastocyst-stage mouse embryos. Using these libraries, we now report the first stages at which the cytokines interleukin (IL)-6, IL-1 beta, and interferon (IFN)-gamma are transcribed in the developing embryo and the presence of IL-7 transcripts in the unfertilized egg. Transcripts for IL-1 alpha, -2, -3, -4, or -5 were not detected at these stages. To identify novel genes expressed on activation of the embryonic genome, the egg and eight-cell stage-specific cDNA libraries were subtracted from the two-cell library, yielding a specialized cDNA library enriched for transcripts expressed at the two-cell stage. Sequence and Southern blot analysis of several of these cDNAs expressed predominantly at the two-cell stage of embryogenesis revealed them to be from novel genes, thereby providing the first molecular tools with which to approach the study of gene expression in the early mammalian embryo.

Animals↗
PubMed1991

Expression of a human immunodeficiency virus type 1 long terminal repeat/simian virus 40 early region fusion gene in transgenic mice.

Three lines of transgenic mice carrying the human immunodeficiency virus type 1 (HIV-1) long terminal repeat fused to the simian virus 40 early region (HIV-1 Tag) were constructed. Expression of the transgenes was reproducibly observed in the lymphoid tissue and skin of all three transgenic lines studied. Interestingly, cell types other than T cells, i.e., B cells and thymic stromal cells, contributed most of the expression detectable in the lymphoid organs. Each transgenic line also displayed a different but consistent pattern of transgene expression in nonlymphoid organs. These individual patterns probably reflect the effects of particular chromosomal integration sites on transcriptional activity of the HIV-1 promoter.

Animals↗
PubMed1990

Determinants of the B-cell response against a transgenic autoantigen.

The failure to induce self-tolerance of simian virus 40 large tumor antigen (T antigen) expressed in the pancreatic beta cells of transgenic mice results in an autoimmune response against this protein and the cells that synthesize it. In every transgenic mouse with delayed onset of T-antigen expression and consequent nontolerance, B cells, T cells, and macrophages are attracted to and infiltrate the pancreatic islets. In contrast, the incidence, onset, and intensity of the B-cell response to produce anti-T-antigen autoantibodies vary considerably with genetic background. Thus the initial attraction of lymphocytes to the cells synthesizing a non-self antigen can be separated from the activation of a B-cell response against it. Haplotypes of the major histocompatibility complex (MHC) differentially influence the character of the autoimmune response, with H-2d and H-2k conferring a high incidence of humoral autoimmunity. Additional non-MHC linked genes are also implicated in control of the B-cell response.

Animals↗
PubMed1989

Specific chromosomal abnormalities characterize fibrosarcomas of bovine papillomavirus type 1 transgenic mice.

In the BPV1.69 line of transgenic mice, the bovine papillomavirus type 1 genome elicits both benign dermal fibroblastic proliferation (fibromatoses) and malignant fibrosarcomas. Because these lesions arise only with time, nonviral factors appear to be involved. We have karyotyped several primary tumors as well as a series of low-passage cell lines derived both from fibromatoses and from fibrosarcomas. The fibrosarcomas, but not the preneoplastic fibromatoses, show consistent abnormalities of one or both of two chromosomes, chromosome 8 (trisomy or duplication) and chromosome 14 (monosomy or translocation). The chromosomal abnormalities are not a direct consequence of the viral integration, which we have mapped to chromosome 15 by in situ hybridization. These results suggest that transgenic mice can be used to study the role(s) of cytogenetic changes in tumorigenesis and may direct the search for genes involved in tumor progression.

Animals↗
PubMed1989

cDNA sequence of neuroendocrine protein 7B2 expressed in beta cell tumors of transgenic mice.

The cDNA for a widely distributed neuroendocrine protein called 7B2 has been cloned from beta cell tumors of transgenic mice and sequenced. As deduced from the cDNA sequence, 7B2 is a secretory protein of 186 amino acids, nearly identical to its human and porcine homologs. The presence of several pairs of basic residues in the carboxyl terminal portion of the protein suggests that 7B2 can undergo proteolytic maturation in secretory granules and thus generate potential bioactive peptides. 7B2 mRNA is about 1.5 kilobase long and is apparently transcribed from a single gene per haploid genome. The use of tissue-specific promoters to express oncogenes in rare cell types of transgenic mice is a powerful tool for immortalization and expansion of these cells, and it facilitates the isolation and the study of rare proteins such as 7B2.

Adenoma, Islet Cell↗
PubMed1989

Tumorigenic latency and separable stages during fibrosarcoma development in transgenic mice carrying papillomavirus genomes.

Transgenic mice have been established carrying the genomes of bovine papillomavirus type 1 (BPV-1), and human papillomaviruses types 5 and 18. Transcriptional dormancy is characteristic of all three viral genomes in transgenic mouse lines maintained for 2-4 years. Only BPV-1, which induces both dermal and epidermal pathology in its natural host, has been found to elicit abnormalities when carried in transgenic mice. The BPV-1 genome acts in these mice as a tissue specific oncogene, in that it elaborates the development of skin fibrosarcomas. Three abnormal stages are evident: two distinct and successive stages of a proliferative hyperplasia (a mild and an aggressive fibromatoses), and the solid tumors (fibrosarcomas). Analysis of tissue biopsies and of derivative cell cultures from each pathology confirms that this pathway is composed of separate stages. Notably, progression from hyperplasia to neoplasia is accompanied by specific cytogenetic changes, which appear necessary in addition to the actions of the BPV oncogenes. The reproducibility of the tumorigenic pathway induced by the BPV genome is providing inroads into the molecular genetic and biochemical mechanisms of tumor development.

Animals↗
PubMed1988

Unit-length line-1 transcripts in human teratocarcinoma cells.

We have characterized the approximately 6.5-kilobase cytoplasmic poly(A)+ Line-1 (L1) RNA present in a human teratocarcinoma cell line, NTera2D1, by primer extension and by analysis of cloned cDNAs. The bulk of the RNA begins (5' end) at the residue previously identified as the 5' terminus of the longest known primate genomic L1 elements, presumed to represent "unit" length. Several of the cDNA clones are close to 6 kilobase pairs, that is, close to full length. The partial sequences of 18 cDNA clones and full sequence of one (5,975 base pairs) indicate that many different genomic L1 elements contribute transcripts to the 6.5-kilobase cytoplasmic poly(A)+ RNA in NTera2D1 cells because no 2 of the 19 cDNAs analyzed had identical sequences. The transcribed elements appear to represent a subset of the total genomic L1s, a subset that has a characteristic consensus sequence in the 3' noncoding region and a high degree of sequence conservation throughout. Two open reading frames (ORFs) of 1,122 (ORF1) and 3,852 (ORF2) bases, flanked by about 800 and 200 bases of sequence at the 5' and 3' ends, respectively, can be identified in the cDNAs. Both ORFs are in the same frame, and they are separated by 33 bases bracketed by two conserved in-frame stop codons. ORF 2 is interrupted by at least one randomly positioned stop codon in the majority of the cDNAs. The data support proposals suggesting that the human L1 family includes one or more functional genes as well as an extraordinarily large number of pseudogenes whose ORFs are broken by stop codons. The cDNA structures suggest that both genes and pseudogenes are transcribed. At least one of the cDNAs (cD11), which was sequenced in its entirety, could, in principle, represent an mRNA for production of the ORF1 polypeptide. The similarity of mammalian L1s to several recently described invertebrate movable elements defines a new widely distributed class of elements which we term class II retrotransposons.

Amino Acid Sequence↗
PubMed1986

Sequence of human DNA polymerase beta mRNA obtained through cDNA cloning.

A cDNA library from polyA+ RNA of a human teratocarcinoma cell line in phage lambda gt11 was screened with a fragment of the rat beta-polymerase cDNA, lambda pol beta-10, as probe. Five positive phage were identified and plaque purified. The cDNA of one positive clone selected for detailed study was 1257 bp. This insert was sequenced and found to contain the coding region for beta-polymerase, as well as 163 bp and 137 bp from the 5' and 3' untranslated regions, respectively. The primary structure of human beta-polymerase (318 amino acids, Mr = 36, 133) deduced from the cDNA was similar to rat beta-polymerase (95% matched residues). The greatest difference between the sequences of the human and rat cDNAs was in the 3' untranslated regions (64% matched base residues). These results provide necessary sequence information for study of the human beta-polymerase gene.

Amino Acid Sequence↗
PubMed1985

Expression of a cytoplasmic LINE-1 transcript is regulated in a human teratocarcinoma cell line.

The major primate family of highly repeated, long interspersed DNA sequences (LINE-1, previously Kpn I, family) includes several thousand 6-kilobase-pair long units that terminate in an A-rich stretch. Recent evidence indicates that long open reading frames occur in at least some family members. These results suggested that one or more LINE-1 family members might be structural genes. Accordingly, a variety of human cell lines was analyzed for the presence of a cytoplasmic, polyadenylylated RNA homologous to LINE-1 sequences. Such a transcript was detected in a human pluripotent teratocarcinoma cell line (NTera2 clone D1). The RNA is approximately 6.5 kilobases long and is homologous to the LINE-1 strand with the open reading frames. The abundance of the transcript varies markedly with previously described variations in the phenotype of these cells and is highest when the cells display the embryonal carcinoma morphology. This RNA may represent a mRNA transcribed from one or more functional genes in the LINE-1 family.

Cell Line↗
PubMed1984

Bovine 1.709 satellite. Recombination hotspots and dispersed repeated sequences.

The nucleotide sequence of 3800 base-pair repeated unit of bovine 1.709 satellite was determined. The 3800 base-pair unit is not internally repeated and contains members of at least three different families of elements that are dispersed in the bovine genome. Two of three elements are associated with extensive length polymorphism within the satellite repeat unit. One of these comprises the 3' end of the bovine Alu-like sequences; the second is composed of C-A dinucleotides.

Animals↗
PubMed1984

Defining the beginning and end of KpnI family segments.

Comparison of the sequences at the ends of several newly cloned and full length members of the monkey KpnI family with one another and with previously described monkey and human segments defines the nucleotide sequence at the two termini. No terminal repeats either direct or inverted are noted within full length family members which may or may not be immediately flanked by direct repeats. At the 3' terminus, several family members have polyadenylation signals followed by a d(A)-rich stretch. The genomic frequency of segments within the full length element increases markedly from the 5' to the 3' terminus, consistent with the cloning of various truncated family members. One such truncated version joined to a low copy number DNA segment is inserted in monkey alpha-satellite where the combination appears to have been amplified in conjunction with the satellite itself.

Animals↗
PubMedDate not supplied

Nucleotide sequence of bovine 1.723 satellite DNA.

The nucleotide sequence of the bovine 1.723 satellite DNA repeated unit was determined. The 680 bp long period of this satellite DNA does not show any significant sequence similarities with the known bovine satellite DNAs. Short repetitive sequences which are parts of 680 bp long repeated units do not form any orderly periodical structure. It seems, however, that the basic repeated unit of the 1.723 bovine satellite DNA has been formed by successive duplications of two, about 100 bp long sequences. The sequence divergence between different copies of the 680 bp repeated unit was also analyzed.

Animals↗