Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea

Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions. Here we report an estimate of the total number of plastic particles and their weight floating in the world''s oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, costal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N = 680) and visual survey transects of large plastic debris (N = 891). Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, we estimate a minimum of 5.25 trillion particles weighing 268,940 tons. When comparing between four size classes, two microplastic <4.75 mm and meso- and macroplastic >4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove <4.75 mm plastic particles from the ocean surface.     

A novel function for proSAAS as an amyloid anti‐aggregant in Alzheimer's disease

Neurodegenerative diseases such as Alzheimer's disease (AD) are characterized by an abnormal aggregation of misfolded beta‐sheet rich proteins such as β‐amyloid (Aβ). Various ubiquitously expressed molecular chaperones control the correct folding of cellular proteins and prevent the accumulation of harmful species. We here describe a novel anti‐aggregant chaperone function for the neuroendocrine protein proSAAS, an abundant secretory polypeptide that is widely expressed within neural and endocrine tissues and which has previously been associated with neurodegenerative disease in various proteomics studies. In the brains of 12‐month‐old APdE9 mice, and in the cortex of a human AD‐affected brain, proSAAS immunoreactivity was highly colocalized with amyloid pathology. Immunoreactive proSAAS co‐immunoprecipitated with Aβ immunoreactivity in lysates from APdE9 mouse brains. In vitro, proSAAS efficiently prevented the fibrillation of Aβ_1–42 at molar ratios of 1 : 10, and this anti‐aggregation effect was dose dependent. Structure‐function studies showed that residues 97–180 were sufficient for the anti‐aggregation function against Aβ. Finally, inclusion of recombinant proSAAS in the medium of Neuro2a cells, as well as lentiviral‐mediated proSAAS over‐expression, blocked the neurocytotoxic effect of Aβ_1–42 in Neuro2a cells. Taken together, our results suggest that proSAAS may play a role in Alzheimer's disease pathology.

     

Activity patterns at the Arctic Circle: nocturnal eagle owls and interspecific interactions during continuous midsummer daylight

Circadian rhythms result from adaptations to biotic and abiotic environmental conditions that cycle through the day, such as light, temperature, or temporal overlap between interacting species. At high latitudes, close to or beyond the polar circles, uninterrupted midsummer daylight may pose a challenge to the circadian rhythms of otherwise nocturnal species, such as eagle owls Bubo bubo. By non‐invasive field methods, we studied eagle owl activity in light of their interactions with their main prey the water vole Arvicola amphibius, and their competitor the white‐tailed eagle Haliaeetus albicilla during continuous midsummer daylight on open, treeless islands in coastal northern Norway. We evaluated circadian rhythms, temporal overlap, exposure, and spatial distribution. The owls maintained a nocturnal activity pattern, possibly because slightly dimmer light around midnight offered favourable hunting conditions. The eagles were active throughout the 24‐h period as opposed to the strictly diurnal rhythm reported elsewhere, thus increasing temporal overlap and the potential for interference competition between the two avian predators. This may indicate an asymmetry, with the owls facing the highest cost of interference competition. The presence of eagles combined with constant daylight in this open landscape may make the owls vulnerable to interspecific aggression, and contrary to the available literature, eagle owls rarely exposed themselves visually during territorial calls, possibly to avoid detection by eagles. We found indications of spatial segregation between owls and eagles reflecting differences in main prey, possibly in combination with habitat‐mediated avoidance. Eagle owl vocal activity peaked in the evening before a nocturnal peak in visual observations, when owls were active hunting, consistent with the hypothesis of a dusk chorus in nocturnal bird species. The owls may have had to trade‐off between calling and foraging during the few hours around midnight when slightly dimmer light reduced the detection risk while also providing better hunting conditions     

Mating systems in two species ofPotentilla from Alaska

Aspects of reproductive ecology have been studied in two species ofPotentilla (Rosaceae) from interior Alaska. Data were collected to determine mating system traits such as seed: ovule and pollen: ovule ratios, and experiments were carried out in the field in order to study the effect of caging, emasculation, and manual self-pollination on seed set and seed quality. Mating system strategies differ between the two species in the populations examined. High pollen: ovule ratio, high seed: ovule ratio, good autodeposition ability, and unpredictable pollination in concert with self-incompatibility indicate thatP. hookeriana in the population studied has adopted a more or less pseudogamous mating system. In contrast, the data suggest thatP. uniflora in the studied population is approaching a sexual, facultatively outbreeding species. Because both species exhibit ploidy variation, a trait common among agamospermous plants, it is concluded that both species are likely to be facultatively agamospermous but that sexual reproduction is much more important in the population ofP. uniflora than it is inP. hookeriana.     

Phototrophic growth in the lumostat: a photo-bioreactor with on-line optimization of light intensity

A novel approach is described for the growth of phototrophic microorganisms in batch culture in laboratory-scale photo-bioreactors. Pure CO₂ is added separately to the aeration gas in a closed loop and the rate of photosynthetic activity is monitored continuously by recording the amount of CO₂ added in order to maintain constant pH. These activity measurements are used to control the intensity of illumination by varying the voltage applied to a bank of fluorescent tubes. The intensity of illumination is maintained at the value giving the maximal rate of photosynthesis while photoinhibition due to excess light is avoided. Since the light intensity received by the individual cells is maintained at the optimal value we term the device a lumostat.Measurements of photosynthetic activity by monitoring CO₂ addition were in excellent agreement with off-line measurements of cell carbon as long as corrections were made for diffusion loss through the walls of the tubing. Exponential growth of a thermophilic strain of the cyanobacteriumSynechococcus was obtained for 7 generations with maximum cell densities of 8 × 10⁷ cells mL^–1. The productivity of the lumostat is superior to that of batch cultures at any fixed light intensity.     

Two alternatively spliced mouse urokinase receptor mRNAs with different histological localization in the gastrointestinal tract

Two mouse urokinase-type plasminogen activator receptor (muPAR) cDNAs were isolated: muPAR1 is homologous to the human urokinase-type plasminogen activator receptor while muPAR2 codes for a 199 residue protein sharing the first 133 residues with muPAR1. Mouse genomic DNA sequencing indicates that the two different mRNAs arise by alternative splicing. In situ hybridization showed differential expression of the two mRNAs in mouse gastric mucosa. muPAR1 mRNA is located in luminal epithelial cells situated close to urokinase-type plasminogen activator-producing connective tissue cells of the lamina propria, pointing to plasmin generation controlled by the cooperation of different cells that may play a role in the release of gastric epithelial cells. muPAR2 mRNA is expressed in the basal epithelial cells, and the deduced protein sequence includes the receptor ligand binding domain, but omits the region involved in glycolipid-mediated membrane anchoring, suggesting that muPAR2 may code for a secreted uPA binding protein.     

Localization of urokinase-type plasminogen activator messenger RNA in the normal mouse by in situ hybridization

The histological distribution of urokinase-type plasminogen activator (u-PA) mRNA was analyzed in normal mouse tissue by in situ hybridization with anti-sense RNA transcribed from three different subclones of a mouse u-PA cDNA. Hybridization signal was found over a distinct fibroblast-like cell in the lamina propria of the gastrointestinal tract, over proximal, distal, and collecting tubules of the kidney, and over the epithelium of the bladder, ductus deferens, and epididymis. No hybridization signal was found over cells of the lung, pancreas, liver, adrenal, pituitary, cerebrum, hypothalamus, cerebellum, sciatic nerve, and striated muscle, nor over endothelial cells in any tissue investigated. The lack of u-PA mRNA in lung tissue was confirmed by Northern analysis and is in contrast to the high amounts of u-PA protein found in this tissue.     

Dual-parameter flow cytometric analysis coupling the measurements of forward-angle light scatter and DNA content of archival ovarian carcinomas of low malignant potential

Paraffin-embedded archival specimens from 45 cases of ovarian carcinoma of low malignant potential (OCLMP) were analyzed by flow cytometry (FCM) using propidium iodide (PI) staining. Since single-parameter FCM analysis is often deficient in the resolution of subtle near-diploid DNA-aneuploid populations, forward-angle light scatter (FALS) was measured as a second parameter. DNA aneuploidy was identified in 15 cases (33%). In 7 of those 15 cases, aneuploidy was resolved with single-parameter FCM; in the remaining 8 cases, DNA aneuploidy was resolved only following dual-parameter analysis coupling DNA content and FALS. In all 15 cases, a single near-diploid aneuploid population was observed (mean DNA index = 1.2); there were no tetraploid aneuploid cases. The proliferative activity for all 45 cases studied ranged from 1.0% to 8.9%, with a mean of 3.5%. No difference in mean proliferative activity was observed between the aneuploid and diploid tumors (P greater than .05). To exclude the possibility that PI staining artifacts caused the observed aneuploidy, five of the eight cases shown to be aneuploid by dual-parameter analysis were further studied using an alternate DNA-binding dye, DAPI, yielding similar results. To exclude the possibility that contaminating stromal and/or inflammatory cells caused the observed aneuploidy, samples from a subset of the dual-parameter cases were sorted, revealing the aneuploid populations to be composed primarily of tumor nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)