Manganese and related elements in the interstitial water of marine sediments

Analyses for manganese, nickel, iron, cobalt, sodium, and lithium in the interstitial water of cores from the southern California borderland and six deep-sea cores in the area of the East Pacific Rise show great variation in concentration of trace elements. Oxidizing near-shore sediments showed a 50-fold enrichment in manganese in contrast to sulfide-rich reducing sediments, which showed no enrichment. Deep-sea sediments were variable in their concentration of the trace metals. All but one core showed a high enrichment in dissolved manganese, with a maximum of 6.6 parts per million. Two cores showed a 100-fold enrichment in nickel and cobalt. The manganese appears to be in solution either as Mn(2+) or as a complex. The results appear to support manganese nodule formation in deep-sea sediments through a diffusion of manganese from depth to the surface.     

Impacts of fishing low-trophic level species on marine ecosystems

Low-trophic level species account for more than 30% of global fisheries production and contribute substantially to global food security. We used a range of ecosystem models to explore the effects of fishing low-trophic level species on marine ecosystems, including marine mammals and seabirds, and on other commercially important species. In five well-studied ecosystems, we found that fishing these species at conventional maximum sustainable yield (MSY) levels can have large impacts on other parts of the ecosystem, particularly when they constitute a high proportion of the biomass in the ecosystem or are highly connected in the food web. Halving exploitation rates would result in much lower impacts on marine ecosystems while still achieving 80% of MSY.     

Rescue of dystrophic muscle through U7 snRNA-mediated exon skipping

Most mutations in the dystrophin gene create a frameshift or a stop in the mRNA and are associated with severe Duchenne muscular dystrophy. Exon skipping that naturally occurs at low frequency sometimes eliminates the mutation and leads to the production of a rescued protein. We have achieved persistent exon skipping that removes the mutated exon on the dystrophin messenger mRNA of the mdx mouse, by a single administration of an AAV vector expressing antisense sequences linked to a modified U7 small nuclear RNA. We report the sustained production of functional dystrophin at physiological levels in entire groups of muscles and the correction of the muscular dystrophy.     

Phytoavailability and toxicity of beryllium and vanadium

Greenhouse and laboratory studies were conducted to evaluate the toxic effects of Be and V on collards (Brassica oleracea, var. acephala L.). In the laboratory germination study, incremental increases in the Be concentrations of the growing medium induced a steady decline in the radicle length of seven-day-old collard seedling. Beryllium concentrations greater than or equal to 8 mg Be L^?1 totally inhibited seed germination. The presence of V in the growing medium had no effect on collard germination; however, it had a profound effect on subsequent radicle elongation. Concentrations of V less than 1 mg V L^?1 stimulated radicle elongation, while concentrations greater than or equal to 3 mg V L^?1 caused severe toxicity. In the greenhouse study, Be toxicity was observed in collards grown in a Blanton sand (Grossarenic Paleudult) received treatments greater than or equal to 150 mg Be kg ^?1 (as BeSO₄). Irrespective of treatment level, 97% of the Be taken up by the plants remained in the roots while only 3% was translocated to aboveground plant parts. Vanadium tissue concentrations and toxicity to collards varied with soil type. Additions as low as 80 mg V kg^?1 to the Blanton sand significantly reduced collard biomass while additions as high as 100 mg V kg^?1 to an Orangebury loamy sand (Typic Paleudult) had no effect on plant biomass. The differential response was attributed to greater accumulation of V by plants grown in the Blanton soil.     

Identification of cephapirin metabolites and degradants in bovine milk by electrospray ionization--ion trap tandem mass spectrometry

Liquid chromatography-ion trap tandem mass spectrometry (LC-MS/MS) with electrospray ionization was used to identify cephapirin metabolites and degradants in milk from cows dosed with cephapirin. The milk was extracted according to a previously published procedure. Structures for various components were tentatively identified by their molecular weight, product ion mass spectra, and/or correspondence to standard mass spectra. These components may have occurred as metabolites or as degradants that occurred on storage or during extraction. Compounds identified in the milk included cephapirin, desacetylcephapirin, cephapirin lactone, hydrolyzed cephapirin, and a reduced cephapirin lactone that has not previously been reported. Methylcephapirin was also identified, possibly as a trace contaminant in the formulation. Analysis of incurred milk extracts showed that cephapirin and desacetylcephapirin are the major residues in milk. Desacetylcephapirin residues persisted about as long as the parent drug. The detection limit for both residues by LC-MS/MS was approximately 1 ng/mL in milk. These results have implications for microbiological methods or rapid test kits, if such methods or kits respond to cephapirin metabolites and degradants present in the milk.