No abstract

An intracanalicular fibroadenoma of the breast showing a clonal chromosomal aberration t(4;12) (q27;q15) as the sole cytogenetic abnormality is described. In order to narrow down the breakpoint region on chromosome 12 on the molecular level we performed fluorescence in situ hybridization (FISH) analysis with a cosmid pool originating from a YAC-contig overspanning part of the region 12q14-15. We were able to narrow down the breakpoint to an approximately 230kb fragment belonging to the HMGI-C gene which maps within an area recently designated as MAR (Multiple Aberration Region). The chromosomal breakpoints of other frequent benign solid tumors, i.e. lipomas, uterine leiomyomas, and pleomorphic adenomas are clustered within the third intron of that gene.

An approach to sequencing proteins by the solid-phase method combined with isolation of proteins and polypeptides by gel electrophoresis is described. Mixtures of proteins or polypeptides resulting from digests are fractionated in the presence of dodecylsulphate in polyacrylamide gels. They are detected with Coomassie blue, eluted, selectively reacted with porous glass derivatives and sequenced in their amino-terminal regions with the aid of a new microsequencer. Alternatively they can be analysed or digested with enzymes and fingerprinted. It is a relatively rapid method of purifying proteins for sequence analysis which we have used to provide partial protein sequence data to complement DNA sequences. Nine genes, four from the unc operon of Escherichiu coli encoding the SI, 8, y and E subunits of ATP synthase and five for capsid proteins of bacteriophage lambda, have been identified by this method.Protein sequence analysis can provide imptirtant information for interpretation and confirmation of DNA sequences. This has been exemplified by the identification of overlapping genes in the related bacteriophages 4 x 1 74 and G4 [I -31 and in the discovery of a different genetic code in mammalian mitochondria [4].The most difficult step in obtaining protein sequence data is often the isolation of the protein itself. The purification of specific proteins by conventional means (e.g. by gel filtration) from structures such as bacteriophages, mitochondrial enzyme complex containing hydrophobic constituents, can be very time-consuming and may require several months' work. However, resolution and recovery of the individual constituents of these complex mixtures on a scale sufficient for microsequence analysis often can be achieved simply and rapidly over a period of 1-2 days by electrophoresis in the presence of dodecylsulphate in polyacrylamide gels. For example, radiolabelled proteins from bacteriophages 4x174 and G4 were purified on polyacrylamide gels and partial protein sequences determined at a radiochemical level. This established that gene K overlaps A and C and that gene E overlaps gene D [3,5].We have now devised procedures for recovery and microsequence analysis of small amounts (0.1 -10 nmol) of nonradioactive proteins from polyacrylamide gels although larger amounts of protein up to 50 nmol can readily be prepared by the same procedure. The proteins are stained briefly with a dye and eluted in high yield by electrophoresis. The products can be digested with enzymes and fingerprinted, or be subjected to amino acid analysis, or be sequenced in the amino-terminal region. Sequence analysis is preceded by selective covalent attachment to porous glass derivatives. Contaminating salts and dyes do not attach and are removed by a simple washing step. The immobilised protein can then be sequenced with the Abbreviations. DITC-glass, the p-phenylene diisothiocyanato derivative of 3-aminopropyl porous glass; F1-ATPase. extrinsic ATPase sector of proton translocating ATP synthase complex.aid of a solid-phase microsequencer....

The assignments of the methylene carbon resonances, C-2 and -4 and C-6and -7, in thetropanesareclarified. Car-bony1 and hydroxy additivity parameters in thetropaneseries (carbonyl aeffect, -1 7.2 p.p.m. ; equatorial hydroxy : a,

Incorporation studies with [1,2-13C] acetate have established the regular polyketide nature of flavoglaucin modified by isoprenylation. The aromatic isoprenylation occurs without any change in stereochemistry of the olefin in the di methy la I lyl moiety.