The sublethal physiological effects of exposure to copper and silver mixtures on rainbow trout (Oncorhynchus mykiss)

The mechanisms behind metal-metal interactions in freshwater environments are currently not well understood. Freshwater environments consist of many different types of metals, from those naturally present such as copper (Cu) and those that originate from anthropogenic sources like silver (Ag). Both Cu and Ag use apical sodium (Na+) channels for uptake into the gills of freshwater fish. In the gills, the mechanisms of Cu2+ and Ag+ toxicity appear to be similar to one another, which is by inhibiting Na+ /potassium (K+)- adenosine triphosphatase (NKA) and carbonic anhydrase (CA). Inhibition of NKA and CA results in ionoregulatory disturbances where branchial Na+ and chloride (Cl-) uptake is reduced and can result in mortality. The overall goal of this research was to build a better understanding of the interactions between Cu and Ag in the context of sub-chronic impacts of metal mixtures on the rainbow trout (Onchorhynchus mykiss). Juvenile rainbow trout were exposed for 10 and 14 days to Cu-only (10-day: 1.0 µM Cu2+, 14-day: 0.35 µM Cu2+), Ag-only (0.04 µM Ag+) or a Cu 2+ + Ag+ mixture (10-day: 1.0 µM Cu2+ + 0.04 µM Ag+; 14-day: 0.35 µM Cu2+ + 0.04 µM Ag+). The effects of Cu-Ag interactions were assessed by measuring bioaccumulation in whole gill, liver and kidney samples, subcellular distribution in the gills and liver, and plasma Na+ and Cl- content. Mortalities were dose dependent and greatest in the mixture exposures. Significant accumulation of Cu and Ag in the gills and kidney were a result of a more than additive affect by metal interactions. Cu accumulation in the liver was also more than additive but no effect was observed on hepatic Ag. Subcellular distribution of Cu mainly occurred in metal sensitive fractions (MSF) while Ag accumulated mainly in biologically detoxified fractions (BDF). Fish exposed to the mixture for 10-days experienced more than additive disruption in plasma Na+ but not in plasma Cl-. During 14-days, mixture-exposed fish experienced a more than additive disruption on ion regulation where plasma Na+ and Cl- were significantly less than Cu2+ or Ag+-only exposed fish. Overall, the effects of metal interactions on bioaccumulation, physiological effects and mortalities were based on exposure concentration

Cancer Biomarker Discovery: The Entropic Hallmark

Background: It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods. Methodology/Principal Findings: Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer. Conclusions/Significance: We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-throughput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Are Park-and-Rides Saving the Environment or Just Saving Parking Costs? Case Study of Denver, Colorado, Light Rail System

Rising greenhouse gas (GHG) emissions have put public transit at the forefront of the push for more sustainable transportation. To improve transit accessibility and attract riders, agencies often build park-and-ride facilities on the periphery of cities. Through the provision of convenient parking facilities, agencies attempt to encourage drivers to shift modes and leave behind their cars to complete their journey by transit. Although park-and-rides are intended to increase transit ridership, such facilities may carry paradoxical environmental consequences. At issue is the degree to which such a multimodal car-to-transit trip actually offsets GHG emissions. The study reported in this paper examined single-occupancy vehicle (SOV) park-and-ride users in the Denver, Colorado, metropolitan area and evaluated the magnitude of GHG emissions saved from transit ridership. Through a comparison of a multimodal trip against a theoretical SOV drive-only trip, the effects from GHG emissions were weighed. In addition, the environmental opportunity cost of park-and-ride stations was assessed through the repetition of the analysis under the assumption that all park-and-ride transit users that originated from within a 2-mi radius would shift modes to walk or bike rather than drive an automobile to the station. The results suggested that park-and-rides located at inner-corridor stations were far less effective in reducing GHG emissions than were end-of-line stations. This ineffectiveness appeared to be exacerbated by a parking fee structure common to both the inner-corridor and end-of-line stations. If the goal is environmental sustainability, the location of a park-and-ride facility at almost every station should be reevaluated in favor of a strategy that focuses on how and where park-and-rides can be most effective. The results of this study suggested that inner-corridor stations, particularly those closest to a downtown area, induced unnecessary driving trips and provided an incentive for longer SOV transit-access car trips