o,p'-DDD in the mouse lung: selective uptake, covalent binding and effect on drug metabolism

By means of autoradiography a high and selective accumulation was observed in the lung alveolar region of C57Bl mice injected with o,p'-[14C]DDD. Exhaustive extraction of lung tissue showed that a large fraction of the radioactivity was covalently bound to protein. Covalent binding in liver was 20-30 times lower and represented a smaller fraction of the total radioactivity present in this tissue. Formation of a cytochrome P-450 catalysed reactive metabolite in lung and liver was indicated by a decreased covalent binding in these tissues in mice pretreated with metyrapone. Both beta-naphthoflavone (beta NF) and phenobarbital (PB) pretreatment decreased binding of o,p'-DDD in lung tissue, while binding in the liver was induced by PB but remained unaffected by beta NF. Pretreatment with high doses of o,p'-DDD and p,p'-DDT gave a significantly decreased binding of o,p'-[14C]DDD in lung, whereas binding in liver remained unchanged. Conjugation with glutathione does not appear to be a major inactivation pathway for the reactive lung metabolite, since a high dose of o,p'-DDD did not deplete non-protein thiols (NPSH) in lung tissue. Pretreatment with o,p'-DDD decreased the N-demethylation of [dimethyl-14C]aminopyrine in both lung and liver in a dose-dependent manner, suggesting that the drug-metabolizing enzyme system may be a target for o,p'-DDD in vivo.     

Safe biotechnology (4). Recommendations for safety levels for biotechnological operations with microorganisms that cause diseases in plants

The Working Party on Safety in Biotechnology of the European Federation of Biotechnology has proposed a classification of microorganisms that cause diseases in plants. In this paper appropriate safety levels are proposed for these classes of microorganisms in order to ensure that research, development and industrial fermentation work with plant pathogens will limit the risk of outbreaks of diseases in crops that could result from work with such microorganisms when they are cultivated in laboratories, glasshouses and biotechnology installations.Co-opted: J. Dähne, J. Drozd, M. Lemattre, I. M. Smith , E. M. A. WaterschootA Report prepared by the Working Party on Safety in Biotechnology of the European Federation of Biotechnology (EFB)

---

     

Sensitive fluorescence in situ hybridization signal detection in maize using directly labeled probes produced by high concentration DNA polymerase nick translation

The signal produced by fluorescence in situ hybridization (FISH) often is inconsistent among cells and sensitivity is low. Small DNA targets on the chromatin are difficult to detect. We report here an improved nick translation procedure for Texas red and Alexa Fluor 488 direct labeling of FISH probes. Brighter probes can be obtained by adding excess DNA polymerase I. Using such probes, a 30?kb yeast transgene, and the rp1, rp3 and zein multigene clusters were clearly detected.     

Chaperonin 60: a paradoxical,evolutionarily conserved protein family with multiple moonlighting functions

Chaperonin 60 is the prototypic molecular chaperone, an essential protein in eukaryotes and prokaryotes, whose sequence conservation provides an excellent basis for phylogenetic analysis. Escherichia coli chaperonin 60 (GroEL), the prototype of this family of proteins, has an established oligomeric‐structure‐based folding mechanism and a defined population of folding partners. However, there is a growing number of examples of chaperonin 60 proteins whose crystal structures and oligomeric composition are at variance with GroEL, suggesting that additional complexities in the protein‐folding function of this protein should be expected. In addition, many organisms have multiple chaperonin 60 proteins, some of which have lost their protein‐folding ability. It is emerging that this highly conserved protein has evolved a bewildering variety of additional biological functions – known as moonlighting functions – both within the cell and in the extracellular milieu. Indeed, in some organisms, it is these moonlighting functions that have been left after the loss of the protein‐folding activity. This highlights the major paradox in the biology of chaperonin 60. This article reviews the relationship between the folding and non‐folding (moonlighting) activities of the chaperonin 60 family and discusses current knowledge on their molecular evolution focusing on protein domains involved in the non‐folding chaperonin functions in an attempt to understand the emerging biology of this evolutionarily ancient protein family.