Reducing greenhouse gas emissions for climate stabilization: framing regional options

miRNA and mRNA expression analysis reveals the effects of continuous heat stress on antibacterial responses to Aeromonas hydrophila lipopolysaccharide (LPS) in grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella) is the largest economic fish in freshwater culture in China, which is predisposed to infectious diseases under high temperature. Under the background of global warming, the industrialization of the Pearl River Delta region has led to aggravated thermal pollution, which has increasingly serious impacts on the aquatic ecological environment. This will result in more frequent exposure of grass carp to overheated water temperatures. Previous studies have only identified the regulatory genes of fish that respond to pathogens or temperature stress, but the transcriptional response to both is unknown. In this study, the histopathological analysis showed heat stress exacerbated spleen damage induced by Aeromonas hydrophila. The transcriptional responses of the spleens from A. hydrophila lipopolysaccharide (LPS) -injected grass carp undergoing heat stress and at normal temperatures for 6, 24, and 72 h were investigated by mRNA and microRNA sequencing. We identified 28, 20, and 141 differentially expressed (DE) miRNAs and 126, 383, and 4841 DE mRNAs between the two groups after 6, 24, and 72 h, respectively. There were 67 DE genes mainly involved in the cytochrome P450 pathway, antioxidant defense, inflammatory response, pathogen recognition pathway, antigen processing and presentation, and the ubiquitin-proteasome system. There were 5 DE miRNAs involved in regulating apoptosis and inflammation. We further verified 17 DE mRNAs and 5 DE miRNAs using quantitative real-time PCR. Based on miRNAs and mRNAs analysis, continuous heat stress will affect the antibacterial responses of grass carp spleens, resulting in aggravation of spleen injury. Together, these results provide data for further understanding of the decreased tolerance of fish to pathogen infection in persistent high-temperature environments.

Environmental co-exposure of high temperature and Cu induce hormonal disturbance of cortisol signaling and altered responses of cellular defense genes in zebrafish

Global warming is causing a continuous increase in environmental temperatures, which simultaneously activates toxic environmental stresses, such as heavy metal exposure, in aquatic ecosystems. The present study aimed at evaluating the effects of Cu toxicity along with increased temperature during zebrafish embryogenesis. Decreased survival rates were observed following combined exposure to high temperature and Cu. Heart rates of zebrafish embryos were significantly increased only during heat stress. An abnormal morphology with curved body shape was induced by exposure to a combination of Cu and heat stress. Furthermore, heat stress also triggered Cu-induced intracellular reactive oxygen species (ROS) production, with upregulation of superoxide dismutase (SOD) and glutathione s-transferase (GST) expression, and cell death with modified expression of p53 and B-cell lymphoma-2 (Bcl-2) in zebrafish embryos. Finally, increased cortisol levels and altered expression of cortisol-signaling genes were observed following exposure to Cu and high temperatures. These results highlight that realistic exposure to combined stressors induces developmental disturbances via stress-induced responses involving oxidative stress and cell death as well as transcriptional alterations leading to cortisol signaling in fish.

Astragaloside IV improved antioxidative stress capacity and related gene expression of the Keap1-Nrf2 pathway in grass carp (Ctenopharyngodon idella) hepatocytes under heat stress

This study aims to investigate the protective effects of astragaloside IV (AS-IV) on the hepatocytes of grass carp (Ctenopharyngodon idella) on heat stress. Cultured cells were treated with AS-IV (0, 50, 100 and 200 μg/ml) at 28°C for 24 h and then exposed to heat stress by increasing the culturing temperature (32 ± 0.5°C) for 6 h. The increased temperatures significantly reduced cell viability and superoxide dismutase (SOD) activity, and increased malondialdehyde (MDA) levels in the 0 μg/ml AS-IV treatment group at 32°C, but the grass carp hepatocytes treated with 100 and 200 μg/ml AS-IV had significantly increased cell viability and SOD activity and decreased MDA levels. The mRNA levels of keap1a, keap1b, nrf2, gsh-px, cat, cu-zn sod, mgst1 and il-6 were significantly lower in the 0 μg/ml AS-IV treatment group at 32°C, while those of keap1a, nrf2, gsh-px, cat, cu-zn sod, gstp1, ho-1 and il-6 were significantly higher in cells treated with 100 or 200 μg/ml AS-IV. Our findings indicate that AS-IV could enhance the antioxidative stress capacity of grass carp hepatocytes under heat stress, and its mechanism may be associated with the activation of the Keap1-Nrf2 pathway. Thus, these results provide new insights into how to alleviate heat stress in grass carp.

Effects of heat and cadmium exposure on stress-related responses in the liver of female zebrafish: Heat increases cadmium toxicity

In this study, female zebrafish (Danio rerio) were exposed to 26°C or 34°C, 0 or 197μg/L cadmium (Cd), singly or in combination for 7days. Multiple stress-related indicators were evaluated in the liver. Mortality, lipid peroxidation (LPO) and ultrastructural damage increased significantly by Cd exposure alone, and were not affected by heat alone. Interestingly, the combined exposure increased LPO, ultrastructural damage, and mortality compared with Cd exposure alone. The results indicated that elevated temperature increased Cd toxicity, which could be explained by several reasons. Firstly, Cd-exposed fish failed to activate the antioxidant defense system under heat stress. Secondly, expression levels of heat shock protein 70 (HSP70) were not significantly up-regulated by heat in Cd-exposed fish but increased by 117 times in Cd-free fish. Besides, hypermethylation of heat shock factor (HSF) binding motif in HSP70 promoter was observed during the combined exposure, indicating that simultaneous exposure may have partially suppressed the cytoprotective up-regulation of HSP70. Thirdly, heat induced an immunosuppressive effect in Cd-exposed fish, as reflected by the reduced mRNA and activity levels of nitric oxide synthase (iNOS) and interleukin-1β (IL-1β) expression levels. Finally, heat down-regulated Zir-, Irt-like protein 8 (ZIP8) and copper transporter 1 (CTR1) and up-regulated metallothioneins (MTs) in Cd-exposed fish, possibly suggesting Cu and Zn depletion and Cd accumulation. Hence, our data provide evidences that warmer temperatures can potentiate Cd toxicity, involved in the regulation of gene transcription, enzymatic activity, and DNA methylation. We found that heat indicators showed varied sensitivity between normal and Cd-exposed fish, emphasizing that the field metal pollution should be carefully considered when evaluating effects of climate change.

Estimation of CO2 emission from water treatment plant--model development and application

A comprehensive mathematical model developed for this study was used to compare estimates of on-site and off-site CO2 emissions, from conventional and advanced water treatment plants (WTPs). When 200,000 m(3) of raw water at 10 NTU (Nepthelometric Turbidity Unit) was treated by a conventional WTP to 0.1 NTU using aluminum sulfate as a coagulant, the total CO2 emissions were estimated to be 790 ± 228 (on-site) and 69,596 ± 3950 (off-site) kg CO2e/d. The emissions from an advanced WTP containing micro-filtration (MF) membrane and ozone disinfection processes; treating the same raw water to 0.005 NTU, were estimated to be 395 ± 115 (on-site) and 38,197 ± 2922 (off-site) kg CO2e/d. The on-site CO2 emissions from the advanced WTP were half that from the conventional WTP due to much lower use of coagulant. On the other hand, off-site CO2 emissions due to consumption of electricity were 2.14 times higher for the advanced WTP, due to the demands for operation of the MF membrane and ozone disinfection processes. However, the lower use of chemicals in the advanced WTP decreased off-site CO2 emissions related to chemical production and transportation. Overall, total CO2 emissions from the conventional WTP were 1.82 times higher than that from the advanced WTP. A sensitivity analysis was performed for the advanced WTP to suggest tactics for simultaneously reducing CO2 emissions further and enhancing water quality.

Context-specific energy strategies: coupling energy system visions with feasible implementation scenarios

Conventional energy strategy defines an energy system vision (the goal), energy scenarios with technical choices and an implementation mechanism (such as economic incentives). Due to the lead of a generic vision, when applied in a specific regional context, such a strategy can deviate from the optimal one with, for instance, the lowest environmental impacts. This paper proposes an approach for developing energy strategies by simultaneously, rather than sequentially, combining multiple energy system visions and technically feasible, cost-effective energy scenarios that meet environmental constraints at a given place. The approach is illustrated by developing a residential heat supply strategy for a Swiss region. In the analyzed case, urban municipalities should focus on reducing heat demand, and rural municipalities should focus on harvesting local energy sources, primarily wood. Solar thermal units are cost-competitive in all municipalities, and their deployment should be fostered by information campaigns. Heat pumps and building refurbishment are not competitive; thus, economic incentives are essential, especially for urban municipalities. In rural municipalities, wood is cost-competitive, and community-based initiatives are likely to be most successful. Thus, the paper shows that energy strategies should be spatially differentiated. The suggested approach can be transferred to other regions and spatial scales.

Historical carbon footprinting and implications for sustainability planning: a case study of the Pittsburgh region

This study estimates fossil-based CO(2) emissions and energy use from 1900-2000 for Allegheny County, PA. Total energy use and emissions increased from 1900 to 1970, reflecting the significant industrial, economic, and population growth that occurred in Allegheny County. From 1970 to 2000, Allegheny County experienced a 30% decrease in total emissions and energy use from peak values, primarily because of a decline in industrial activity (40% decrease in value added) and the loss of a quarter of its population. Despite these dramatic economic and demographic transitions, per capita emissions remained stable from 1970 to 2000, buoyed by relatively stable or slightly increasing emissions in the commercial and transportation sectors. Allegheny County's history suggests the scale of change needed to achieve local emissions reductions may be significant; given years of major technological, economic, and demographic changes, per capita emissions in 1940 were nearly the same in 2000. Most local governments are planning emissions reductions rates that exceed 1% per year, which deviate significantly from historical trends. Our results suggest additional resources and improved planning paradigms are likely necessary to achieve significant emissions reductions, especially for areas where emissions are still increasing.

The technology path to deep greenhouse gas emissions cuts by 2050: the pivotal role of electricity

Several states and countries have adopted targets for deep reductions in greenhouse gas emissions by 2050, but there has been little physically realistic modeling of the energy and economic transformations required. We analyzed the infrastructure and technology path required to meet California's goal of an 80% reduction below 1990 levels, using detailed modeling of infrastructure stocks, resource constraints, and electricity system operability. We found that technically feasible levels of energy efficiency and decarbonized energy supply alone are not sufficient; widespread electrification of transportation and other sectors is required. Decarbonized electricity would become the dominant form of energy supply, posing challenges and opportunities for economic growth and climate policy. This transformation demands technologies that are not yet commercialized, as well as coordination of investment, technology development, and infrastructure deployment.

Exposure to traffic and risk of hospitalization due to injuries

Research on the risk of motor vehicle injuries and their relationship with the amount of travel has been only partially analyzed. The few individual exposure assessments are related to very specific subsets of the driving and traveling populations. This study analyzes the relationship between kilometers traveled and hospitalization due to motor vehicle injuries. Twelve thousand three hundred and sixty nine Spanish university graduates from the Seguimiento Universidad de Navarra multipurpose cohort study were evaluated. They had not been hospitalized due to motor vehicle injuries at baseline and were followed up to eight years. Biannual questionnaires allowed for self-reporting of kilometers traveled in motor vehicles, together with incidence of hospitalization. Covariates in the Cox regression models included age and gender and baseline use of safety belt while driving, driving a vehicle with driver-side airbag, driving a motorcycle, and drinking and driving. There were 49,766 participant-years with an average yearly travel of 7,828 km per person-year. Thirty-six subjects reported a first hospitalization event during this time. The adjusted hazard ratio per additional kilometer traveled was 1.00005 (95% confidence interval 1.000013 to 1.000086). Even the smallest of reductions in the amount of kilometers traveled (from an average of 3,250 km per year to 1,000) has a statistically significant protective effect on the likelihood of sustaining hospitalization due to motor vehicle injury (aHR 0.9, 95% CI 0.78 to 0.98). In light of current policies aimed to reduce motorized traffic due to environmental concerns, it may be appropriate to consider the additional health benefit related to reductions in injuries.

Life-cycle analysis on biodiesel production from microalgae: water footprint and nutrients balance

This research examines the life-cycle water and nutrients usage of microalgae-based biodiesel production. The influence of water types, operation with and without recycling, algal species, geographic distributions are analyzed. The results confirm the competitiveness of microalgae-based biofuels and highlight the necessity of recycling harvested water and using sea/wastewater as water source. To generate 1 kg biodiesel, 3726 kg water, 0.33 kg nitrogen, and 0.71 kg phosphate are required if freshwater used without recycling. Recycling harvest water reduces the water and nutrients usage by 84% and 55%. Using sea/wastewater decreases 90% water requirement and eliminates the need of all the nutrients except phosphate. The variation in microalgae species and geographic distribution are analyzed to reflect microalgae biofuel development in the US. The impacts of current federal and state renewable energy programs are also discussed to suggest suitable microalgae biofuel implementation pathways and identify potential bottlenecks.