The use of transposons to introduce well-defined deletions in plasmids: possibilities for in vivo cloning.
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Arginine↗
Biomedical subjects
J Hille
Publications and source records attributed to J Hille.
Relief of polarity caused by transposon Tn5: application in mapping a cloned region of the Escherichia coli uvrB locus essential for UV resistance.
The structure and function of recombinant plasmid pNP5, which consists of vector pMB9 and a 2.5 kb EcoRI fragment harbouring the Escherichia coli uvrB gene, has been investigated. Insertional inactivation with the transposons Tn1 (Apr) or Tn5 (Kmr) has been used to determine the region on pNP5 DNA that is essential for UV resistance in uvrB deletion strains. This region spans approx. 1.8 kb and is separated by at least 280 bp from the pMB9 promoter to which it has been fused. Furthermore, a procedure is described to eliminate the polarity exerted by the transposon Tn5. A combination of in vitro digestion of pNP5::Tn5 DNA with restriction endonuclease XHoI, followed by ligation and subsequent in vivo propagation of the resulting plasmid DNA yields predominantly pNP5 molecules with a site-specific nonpolar mutation. The method allows an investigation of cloned complex genetic units, such as operons.
Chromosome Mapping↗
An easy and efficient procedure for the isolation of pure DNA restriction fragments from agarose gels.
A new procedure is developed to isolate DNA from agarose gels. Using a kind of blotting technique, DNA is isolated from the gel. It is shown that the isolated DNA can be used for fragmentation by restriction endonucleases, synthesis of complementary RNA by DNA-dependent RNA polymerase from Escherichia coli and nick translation. The procedure gives a high recovery and is easy to perform.
Buffers↗
[Principles of classification and nomenclature in families with striking social peculiarities shown by an example of the district of Osterburg (author's transl)].
The necessity of an uniform characterization for the so called "families with social perculiarities" is explained. Criterias and designations for this purpose are proposed and used in a survey in the district of Osterburg. It is shown, that social risks concentrate in villages. They increase with a rising number of children, especially in families with 5 and more children, and that the social burden of numerous children is "infectious" in respect of peculiarities. Alcoholism is the most negative of them. The most important tasks are the care of potators and of families with childbirth intervals of less than two years.
Classification↗
Malignant neuroendocrine tumor presenting in the mandible.
The carotid body, jugulotympanic, vagal, and laryngeal paragangliomas are the most common paragangliomas respectively within the head and neck, although unusual examples in other sites have been described. Among these are several references in the literature to a mandibular or "alveolar body" paraganglioma, even though such an entity does not appear to have been adequately documented. This report describes a case which presented as an extensive osteoblastic tumor involving the mandible and which radiographically appeared as a typical osteosarcoma. However, the immunohistochemical and electron microscopic features were of a neuroendocrine tumor and the histologic pattern suggested a paraganglioma. The tumor was nonfunctional and an extensive search failed to reveal any further lesions. Eight months after resection of the lesion, metastatic deposits appeared within the left iliac crest and lumbar vertebra. The origin of this tumor is discussed.
Aged↗
Plant-inducible virulence promoter of the Agrobacterium tumefaciens Ti plasmid.
Agrobacterium tumefaciens is the causative agent of crown gall, a plant tumour that can arise on most species of dicotyledonous plants. The tumour-inducing capacity of the bacterium requires the presence of a large plasmid, designated the Ti plasmid, which itself contains two regions essential for tumour formation-the T(umour)-region and the Vir(ulence)-region. The T-region is transferred to plant cells by an unknown mechanism, and becomes stably integrated into the plant genome. The Vir-region has been identified by transposon mutagenesis, but the DNA of this region has never been detected in tumour lines. However, trans-complementation of Vir mutants indicates that genes of the Vir-region are functional in the bacterium. Moreover, the Vir- and T-regions can be physically separated in A. tumefaciens without loss of tumour-inducing capacity. Seven loci, designated virA-F and virO (refs 17, 20-22), have been identified in the Vir-region of the octopine Ti plasmid, but their functions are unknown. As virC mutants in the octopine-type plasmid pTiB6 are invariably avirulent in tests on various plant species, this gene seems to be essential for virulence and we are studying it in detail. We report here that the promoter of virC shows no detectable activity in A. tumefaciens and Escherichia coli K-12 grown in standard medium, but that its activity is induced by a plant product.
Gene Expression Regulation↗