The tremendous potential of deep-sea mud as a source of rare-earth elements.

Potential risks of supply shortages for critical metals including rare-earth elements and yttrium (REY) have spurred great interest in commercial mining of deep-sea mineral resources. Deep-sea mud containing over 5,000 ppm total REY content was discovered in the western North Pacific Ocean near Minamitorishima Island, Japan, in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features. Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km2 × 0-10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively. Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future.

Co-localized expression of FasL, Fas, Caspase-3 and apoptotic DNA fragmentation in mouse testis after oral exposure to di(2-ethylhexyl)phthalate.

Expression of apoptosis-related proteins FasL, Fas and Caspase-3, as well as DNA fragmentation were examined in mouse testis 12 h after exposure to 4-0.004 mg/g di(2-ethylhexyl)phthalate (DEHP). Immunocytochemical examination of the highest dose (4 mg/g DEHP) mouse revealed a distribution of FasL in Sertoli cell and Fas in nearby spermatocyte, and Fas and Caspase-3 in the same spermatocyte. Fas-positive spermatocytes had a DNA-fragmented nucleus detectable by terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end labeling (TUNEL) method. After exposure to 4, 0.4, 0.04 or 0.004 mg/g DEHP, the maximum number of nuclei with fragmented DNA per 0.5 microm testis section was 22, 7, 5 and 3, respectively. In unexposed control the maximum number was 3. To further estimate total amount of the fragmented DNA in testis of the exposed mouse, the extracted DNA fragments were analyzed by agarose gel electrophoresis. The amount of fragments in the first three steps of the DNA ladder was estimated by a photo-densitometry. In the highest dose mouse (4 mg/g DEHP), the fragmented DNA was 2.2 times as much in the control. In lower dose mouse (0.4, 0.04 or 0.004 mg/g DEHP), it was 1.1 times as much in the control. Taken together, these observations suggest that a single oral exposure to DEHP as low as 0.04 mg/g might be effective to testicular DNA fragmentation and apoptosis.