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- Creusot, F., et al.
(författare)
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The CIC YAC library: Sizing of the clones and determination of clones carrying repeated DNA sequences.
- 1995
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Ingår i: The Plant Journal. - 0960-7412 .- 1365-313X. ; 8:5, s. 763-770
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Tidskriftsartikel (refereegranskat)abstract
- A new Arabidopsis thaliana (ecotype Columbia) genomic library has been constructed in Yeast Artificial Chromosomes: the CIC library (for CEPH, INRA and CNRS). Optimization of plant culture conditions and protoplast preparation allowed the recovery of large amounts of viable protoplasts. Mechanical shearing of DNA was minimized by isolation of DNA from protoplasts embedded in agarose. Cloning of large inserts was favored by including two successive size fractionation steps (after partial EcoRI digestion and after ligation with the vector arms), which selected DNA fragments larger than 350 kb. The library consists of 1152 clones with an average insert size of 420 kb. Clones carrying chloroplast DNA and various nuclear repeated sequences have been identified. Twenty-one per cent of the clones are found to contain chloroplast DNA. Therefore, the library represents around four nuclear genome equivalents. The clones containing 5S rDNA genes, 18S-25S rDNA sequences and the 180 bp paracentromeric repeated element account for 3.6%, 8.9% and 5.8%, respectively. Only one clone was found to carry the 160 bp paracentromeric repeated element. Given the smaller size of clones carrying Arabidopsis repeated DNA, the average size of remaining clones is around 480 kb. The library was screened by PCR amplification using pairs of primers corresponding to sequences dispersed in the genome. Seventy out of 76 pairs of primers identified from one to seven YAC clones. Thus at least 92% of the genome is represented in the CIC library. The survey of the library for clones containing unlinked DNA sequences indicates that the proportion of chimeric clones is lower than 10%.
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- Larsson, Erik, et al.
(författare)
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Tissue and differentiation specific expression of the endogenous retrovirus ERV3 (HERV-R) in normal human tissues and during induced monocytic differentiation in the U-937 cell line
- 1997
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Ingår i: Leukemia. - 0887-6924 .- 1476-5551. ; 11:Suppl. 3, s. 142-4
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Tidskriftsartikel (refereegranskat)abstract
- ERV3 (HERV-R) is a complete, single copy human endogenous retrovirus located on the long arm of chromosome 7. The open reading frame in its envelope gene has been conserved during evolution but the gag and pol genes contain in-frame termination codons. To find a suitable experimental model system for analysis of the functions of the ERV3 genome, an extensive screening study of different normal and neoplastic human tissues was performed. Most tissues express low levels of the ERV3 env mRNA although high expression levels are observed in placenta, sebaceous glands, adrenals, testis, bronchial, epithelium and the monocytic cell line U-937. In U-937 cells the ERV3 env expression varied in a manner related to the differentiation status of the cells; being highest in the terminally differentiated non proliferating cells. U-937 cells can be induced to differentiate from the monoblastic to the mature monocyte/macrophage stage upon stimulation by several substances such as phorbolesters (TPA), Vitamin D3, Retinoic Acid (RA) and combinations of some cytokines. We conclude that the ERV3 locus is expressed in a tissue and differentiation specific way and that the U-937 cell line is a suitable model system to further analyze the proposed functions of ERVs such as immunomodulation, cell fusion and protection against exogenous retroviral infections.
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