Ferromanganese micronodules from the surficial sediments of Georges Bank

Ferromanganese micronodules have been found on Georges Bank, off the U.S. northeast coast, distributed throughout the surficial sediments within an area about 125 km long and at least 12 km wide. These coarse, sand-sized concretions have precipitated from metal-rich interstitial waters and contain many of the textural and structural features common to other neritic nodules. Most of the nodules have accreted around detrital grains, and X-ray powder diffraction analyses indicate the presence of geothite and vernadite (δ-MnO2) in the ferromanganese layers. Chemical analyses of the micronodules, when compared with similar data on deep-sea manganese nodules, reveal lower Mn/Fe ratios, significantly higher concentrations of V and As, comparable values of Mo, and an order of magnitude less of Co, Ni, Ce and most other metals

Small DNA Pieces in C. elegans Are Intermediates of DNA Fragmentation during Apoptosis

While studying small noncoding RNA in C. elegans, we discovered that protocols used for isolation of RNA are contaminated with small DNA pieces. After electrophoresis on a denaturing gel, the DNA fragments appear as a ladder of bands, ∼10 nucleotides apart, mimicking the pattern of nuclease digestion of DNA wrapped around a nucleosome. Here we show that the small DNA pieces are products of the DNA fragmentation that occurs during apoptosis, and correspondingly, are absent in mutant strains incapable of apoptosis. In contrast, the small DNA pieces are present in strains defective for the engulfment process of apoptosis, suggesting they are produced in the dying cell prior to engulfment. While the small DNA pieces are also present in a number of strains with mutations in predicted nucleases, they are undetectable in strains containing mutations in nuc-1, which encodes a DNase II endonuclease. We find that the small DNA pieces can be labeled with terminal deoxynucleotidyltransferase only after phosphatase treatment, as expected if they are products of DNase II cleavage, which generates a 3′ phosphate. Our studies reveal a previously unknown intermediate in the process of apoptotic DNA fragmentation and thus bring us closer to defining this important pathway

In C. elegans, High Levels of dsRNA Allow RNAi in the Absence of RDE-4

C. elegans Dicer requires an accessory double-stranded RNA binding protein, RDE-4, to enact the first step of RNA interference, the cleavage of dsRNA to produce siRNA. While RDE-4 is typically essential for RNAi, we report that in the presence of high concentrations of trigger dsRNA, rde-4 deficient animals are capable of silencing a transgene. By multiple criteria the silencing occurs by the canonical RNAi pathway. For example, silencing is RDE-1 dependent and exhibits a decrease in the targeted mRNA in response to an increase in siRNA. We also find that high concentrations of dsRNA trigger lead to increased accumulation of primary siRNAs, consistent with the existence of a rate-limiting step during the conversion of primary to secondary siRNAs. Our studies also revealed that transgene silencing occurs at low levels in the soma, even in the presence of ADARs, and that at least some siRNAs accumulate in a temperature-dependent manner. We conclude that an RNAi response varies with different conditions, and this may allow an organism to tailor a response to specific environmental signals

Ferromanganese crusts and nodules chemical analyses from the USGS Reston analytical laboratories

Based on comparative studies on the utility of ICP, atomic absorption, and other techniques for the elemental analysis of geological samples the authors decided to pursue a scheme of analysis based primarily around the induction coupled plasma atonic emission spectrometry (ICP) technique because of its simultaneous multielement capability and its relatively large linear concentration range. Atomic Absorption techniques are used only for those elements where the sensitivity, precision, or accuracy of the ICP technique are not sufficient for the determination. The elements Cu, Ni, Mo, Sr, V, Y, Cr, Ba, Co, and P were determined by ICP spectrometry, K, Pb, and Zn by FAA spectrometry and Cr by Zeeman GFAA spectrometry on a concentrated solution of 100mg sample dissolved into 3 mL HN03, 1 mL HC104 and 10 mL HF. Mn, Ti, Al, Fe, Mg and Ca is determined by ICP spectrometry and Cd by Zeeman GFAA spectrometry on a dilution of the previous solution with 3N HCl. A dissolution of 100mg of sample into (1+1) HCl was analysed for As using Zeeman GFAA spectrometry. A fusion of 100mg of sample with a mixture of LiBO2+liB4O2 was analysed for Si and Na using ICP technique. Before analysis, the samples were dried at 110°C overnight and fused at 1000°C for 45 minutes

Annotated record of the detailed examination of Mn micronodules from stations over George Bank, Atlantic Ocean

Ferromanganese micronodules have been found on Georges Bank, off the U.S. northeast coast, distributed throughout the surficial sediments within an area about 125 km long and at least 12 km wide. These coarse, sand-sized concretions have precipitated from metal-rich interstitial waters and contain many of the textural and structural features common to other neritic nodules. Most of the nodules have accreted around detrital grains, and X-ray powder diffraction analyses indicate the presence of geothite and vernadite ( delta -MnO sub(2)) in the ferromanganese layers. Chemical analyses of the micronodules, when compared with similar data on deep-sea manganese nodules, reveal lower Mn/Fe ratios, significantly higher concentrations of V and As, comparable values of Mo, and an order of magnitude less of Co, Ni, Ce and most other, metals