No abstract

Floating marine plastic debris was found to function as solid-phase extraction media, adsorbing and concentrating pollutants out of the water column. Plastic debris was collected in the North Pacific Gyre, extracted, and analyzed for 36 individual PCB congeners, 17 organochlorine pesticides, and 16 EPA priority PAHs. Over 50% contained PCBs, 40% contained pesticides, and nearly 80% contained PAHs. The PAHs included 2, 3 and 4 ring congeners. The PCBs were primarily CB-11, 28, 44, 52, 66, and 101. The pesticides detected were primarily p,p-DDTs and its metabolite, o,p-DDD, as well as BHC (a,b,g and d). The concentrations of pollutants found ranged from a few ppb to thousands of ppb. The types of PCBs and PAHs found were similar to those found in marine sediments. However, these plastic particles were mostly polyethylene which is resistant to degradation and although functioning similarly to sediments in accumulating pollutants, these had remained on or near the ocean surface. Particles collected included intact plastic items as well as many pieces less than 5 mm in size.

No abstract

Araneoid spiders use specialized abdominal glands to manufacture up to seven different protein-based silks/glues that have diverse physical properties. The fibroin sequences that encode egg case fibers (cover silk for the egg case sac) and the secondary structure of these threads have not been previously determined. In this study, MALDI tandem TOF mass spectrometry (MS/MS) and reverse genetics were used to isolate the first egg case fibroin, named tubuliform spidroin 1 (TuSp1), from the black widow spider, Latrodectus hesperus. Real-time quantitative PCR analysis demonstrates TuSp1 is selectively expressed in the tubuliform gland. Analysis of the amino acid composition of raw egg case silk closely aligns with the predicted amino acid composition from the primary sequence of TuSp1, which supports the assertion that TuSp1 represents a major component of egg case fibers. TuSp1 is composed of highly homogeneous repeats that are 184 amino acids in length. The long stretches of polyalanine and glycine-alanine subrepeats, which account for the crystalline regions of minor ampullate and major ampullate fibers, are very poorly represented in TuSp1. However, polyserine blocks and short polyalanine stretches were highly iterated within the primary sequence, and (13)C NMR spectroscopy demonstrated that the majority of alanine was found in a beta-sheet structure in post-spun egg case silk. The TuSp1 repeat unit does not display substantial sequence similarity to any previously described fibroin genes or proteins, suggesting that TuSp1 is a highly divergent member of the spider silk gene family.