Chemical forms of selenium in the metal-resistant bacterium Ralstonia metallidurans CH34 exposed to selenite and selenate

International audienceRalstonia metallidurans CH34, a soil bacterium resistant to a variety of metals, is known to reduce selenite to intracellular granules of elemental selenium (Se0). We have studied the kinetics of selenite (SeIV) and selenate (SeVI) accumulation and used X-ray absorption spectroscopy to identify the accumulated form of selenate, as well as possible chemical intermediates during the transformation of these two oxyanions. When introduced during the lag phase, the presence of selenite increased the duration of this phase, as previously observed. Selenite introduction was followed by a period of slow uptake, during which the bacteria contained Se0 and alkyl selenide in equivalent proportions. This suggests that two reactions with similar kinetics take place: an assimilatory pathway leading to alkyl selenide, and a slow detoxification pathway leading to Se0. Subsequently, selenite uptake strongly increased (up to 340 mg Se per g of proteins), and Se0 was the predominant transformation product, suggesting an activation of selenite transport and reduction systems after several hours of contact. Exposure to selenate did not induce an increase in the lag phase duration and the bacteria accumulated approximately 25 fold less Se than when exposed to selenite. SeIV was detected as transient species in the first 12 hours after selenate introduction, Se0 also occurred as minor species, and the major accumulated form was alkyl selenide. Thus, in the present experimental conditions selenate mostly follows an assimilatory pathway, and the reduction pathway is not activated upon selenate exposure. These results show that R. metallidurans CH34 may be suitable for the remediation of selenite - but not selenate -contaminated environments

The Rhubarb Connection and Other Revelations: The Everyday World of Metal Ions

International audiencePink warships that vanish at dusk, urinary maladies of an emperor, and a gold test for cocaine – behold the chemistry of metal ions as never before.In this book you will learn about the sarcophagus molecule, the Chen-Kao test, and how murderers can be caught blue-handed with the wonders of glowing luminol. You will also meet the hidden chemistry of metal ions in everyday life, from the clever modern devices that measure blood-sugar levels, to the leather on your shoes and chewing gum stuck to their soles.Expect to encounter a fair share of heroes and villains, real and fictional, scientist and layperson. Such characters include an ex-MI5 employee running a hospital ward in London amid falling German V1 rockets, a notorious racing cyclist, a proud butler and the lady who first proposed nuclear fission (it’s not who you think it is).With engaging, humorous and intelligent prose, the reader will discover the fascinating back-stories of chemical discoveries and inventions where metal ions have played a major role

The Rhubarb Connection and Other Revelations: The Everyday World of Metal Ions

Pink warships that vanish at dusk, urinary maladies of an emperor, and a gold test for cocaine – behold the chemistry of metal ions as never before. In this book you will learn about the sarcophagus molecule, the Chen-Kao test, and how murderers can be caught blue-handed with the wonders of glowing luminol. You will also meet the hidden chemistry of metal ions in everyday life, from the clever modern devices that measure blood-sugar levels, to the leather on your shoes and chewing gum stuck to their soles. Expect to encounter a fair share of heroes and villains, real and fictional, scientist and layperson. Such characters include an ex-MI5 employee running a hospital ward in London amid falling German V1 rockets, a notorious racing cyclist, a proud butler and the lady who first proposed nuclear fission (it’s not who you think it is). With engaging, humorous and intelligent prose, the reader will discover the fascinating back-stories of chemical discoveries and inventions where metal ions have played a major role. Featuring a foreword by popular science communicator Dr Raychelle Burks of St. Edward's University, Texas

The Rhubarb Connection and Other Revelations: The Everyday World of Metal Ions

Pink warships that vanish at dusk, urinary maladies of an emperor, and a gold test for cocaine – behold the chemistry of metal ions as never before. In this book you will learn about the sarcophagus molecule, the Chen-Kao test, and how murderers can be caught blue-handed with the wonders of glowing luminol. You will also meet the hidden chemistry of metal ions in everyday life, from the clever modern devices that measure blood-sugar levels, to the leather on your shoes and chewing gum stuck to their soles. Expect to encounter a fair share of heroes and villains, real and fictional, scientist and layperson. Such characters include an ex-MI5 employee running a hospital ward in London amid falling German V1 rockets, a notorious racing cyclist, a proud butler and the lady who first proposed nuclear fission (it’s not who you think it is). With engaging, humorous and intelligent prose, the reader will discover the fascinating back-stories of chemical discoveries and inventions where metal ions have played a major role. Featuring a foreword by popular science communicator Dr Raychelle Burks of St. Edward's University, Texas.</jats:p

Solubilization and partial purification of UDP-galactose:diacylglycerol galactosyltransferase activity from spinach chloroplast envelope

AbstractWe have developed procedures to solubilize the envelope UDP-galactose:diacylglycerol galactosyltransferase activity and to assay this enzyme after solubilization with a zwitterionic non-denaturing detergent (CHAPS) and fractionation. From solubilized envelope membranes isolated from intact spinach chloroplasts, we were able to prepare by chromatography on hydroxyapatite a fraction enriched (6–7-fold) in this enzyme responsible for monogalactosyldiacylglycerol synthesis