Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

Transcription of the ileS operon in the archaeon Methanobacterium thermoautotrophicum Marburg.

In the thermophilic archaeon Methanobacterium thermoautotrophicum Marburg, the structural gene for isoleucyl-tRNA synthetase (ileS) is flanked upstream by orf401 and downstream by purL. orf401 encodes a 43.5-kDa protein with an unknown function. Northern (RNA) hybridization and S1 nuclease protection experiments showed that the orf401, ileS, and purL genes are cotranscribed from an archael consensus promoter in front of orf401. The corresponding transcript was about eightfold increased in cells that had been exposed to pseudomonic acid A, a specific inhibitor of isoleucyl-tRNA synthetase. Growth inhibition by puromycin, tryptophan starvation, or starvation for hydrogen did not affect the level of this transcript. The level of a trpE transcript, however, was drastically elevated upon tryptophan starvation, while inhibition by pseudomonic acid A had no effect on the level of this transcript. Expression of ileS thus appears to be controlled by a regulatory mechanism which specifically responds to the availability of isoleucyl-tRNA. Extensive decay of the orf401-ileS-purL message was observed. Degradation occurred, presumably by endonucleolytic cleavage, within the orf401 region

Regulation of tryptophan biosynthesis in Methanobacterium thermoautotrophicum Marburg.

A tryptophan-auxotrophic mutant of the archaeon Methanobacterium thermoautotrophicum Marburg was grown with growth-promoting and growth-limiting concentrations of tryptophan. The specific activities of anthranilate synthase (TrpEG) and tryptophan synthase (TrpB) increased 30- to 40-fold in tryptophan-starved cells. Levels of trpE-specific and trpD-specific mRNAs (transcripts of the first and the last genes, respectively, of the M. thermoautotrophicum Marburg trp gene cluster) increased about 10-fold upon starvation for tryptophan. Thus, the expression of the trp genes appears to be regulated primarily at the level of transcription. These data support transcription of trp genes as an operon and support a regulatory model involving a repressor. Anthranilate synthase was feedback inhibited by L-tryptophan, with a Ki of 3.0 microM. In a leucine-auxotrophic mutant starved for L-leucine, the level of alpha-isopropylmalate synthase (LeuA) was 10-fold higher than in cells grown with L-leucine. In addition to the finding of specific regulation of gene expression by the end products of their respective pathways, it was found that the levels of anthranilate synthase and alpha-isopropylmalate synthase were reduced upon growth in the presence of amino acids of other families, such as L-alanine, L-proline, or L-arginine. Conversely, starvation for tryptophan caused a slight elevation of alpha-isopropylmalate synthase and starvation for leucine caused a significant increase of anthranilate synthase and tryptophan synthase specific activities. The latter effect was also observed at the level of trp-specific mRNA and is reminiscent of general amino acid control

Glomerulare Veranderungen bei der Refluxnephropathie. [Glomerular changes in reflux nephropathy]

Two patients with bilateral vesicoureteral reflux are presented. In both cases renal insufficiency progressed despite surgical correction of the vesicoureteral reflux and proteinuria persisted. Biopsy specimens from both patients revealed interstitial damage and segmental and focal glomerulosclerosis. These glomerular lesions in association with reflux nephropathy may be an important cause of renal function deterioration

Urologische Komplikationen nach Nierentransplantation [Urological complications following renal transplantation (author's transl)]

Between December 1964 and April 1974, 216 renal transplants were performed on 200 recipients at the University Clinic of the Cantonal Hospital at Zurich. The ureteroneocystostomy was performed in most cases, a pyeloureterostomy being done only five times. 12% of all recipients (24 patients) developed serious urological postoperative complications involving 27 (14.3%) of the transplants, with four cases being fatal. Not considered as a serious complication were urinary infections and retention due to clotting, both of which could be treated conservatively with success. Of the more serious cases, 8 involved stenosis of the ureter, 4 compression of the ureter, 2 obstruction of the ureter, and 4 bladder fistulation. In 10 of these cases the complication can be related to imperfect operative technique in respect to transplanting the donor kidney. Preserving sufficient ureter vascularization is of paramount importance, and consideration must be given to increased vulnerability to infection as a result of the immunosuppressive therapy. Extreme stripping of the pyelon and ureter can result in stenosis and necrosis of the ureter. The treatment of urinary passage complications has not been standardized. However, fistula closure and operative correction of ureter obstruction must be carried out quickly

Isoleucyl-tRNA synthetase of Methanobacterium thermoautotrophicum Marburg : cloning of the gene, nucleotide sequence, and localization of a base change conferring resistance to pseudomonic acid

The ileS gene encoding the isoleucyl-tRNA synthetase of the thermophilic archaebacterium Methanobacterium thermoautotrophicum Marburg was isolated and sequenced. ileS was closely flanked by an unknown open reading frame and by purL and thus is arranged differently from the organizations observed in several eubacteria or in Saccharomyces cerevisiae. The deduced amino acid sequence of isoleucyl-tRNA synthetase was compared with primary sequences of isoleucyl-, valyl-, leucyl-, and methionyl-tRNA synthetases from eubacteria and yeast. The archaebacterial enzyme fitted well into this group of enzymes. It contained the two short consensus sequences observed in class I aminoacyl-tRNA synthetases as well as regions of homology with enzymes of the isoleucine family. Comparison between the isoleucyl-tRNA synthetases of M. thermoautotrophicum yielded 36% amino acid identity with the yeast enzyme and 32% identity with the corresponding enzyme from Escherichia coli. The ileS gene of the pseudomonic acid-resistant M. thermoautotrophicum mutant MBT10 was also sequenced. The mutant enzyme had undergone a glycine to aspartic acid transition at position 590, in a conserved region comprising the KMSKS consensus sequence. The inhibition constants of pseudomonic acid, KiIle and KiATP, for the mutant enzyme were 10-fold higher than those determined for the wild-type enzyme. Both the mutant and the wild-type ileS gene were expressed in E. coli, and their products displayed the expected difference in sensitivity toward pseudomonic acid