Elevated Carbon Dioxide Levels Research Articles

Capturing the global signature of surface ocean acidification during the Palaeocene-Eocene Thermal Maximum.

Geologically abrupt carbon perturbations such as the Palaeocene-Eocene Thermal Maximum (PETM, approx. 56 Ma) are the closest geological points of comparison to current anthropogenic carbon emissions. Associated with the rapid carbon release during this event are profound environmental changes in the oceans including warming, deoxygenation and acidification. To evaluate the global extent of surface ocean acidification during the PETM, we present a compilation of new and published surface ocean carbonate chemistry and pH reconstructions from various palaeoceanographic settings. We use boron to calcium ratios (B/Ca) and boron isotopes (δ11B) in surface- and thermocline-dwelling planktonic foraminifera to reconstruct ocean carbonate chemistry and pH. Our records exhibit a B/Ca reduction of 30-40% and a δ11B decline of 1.0-1.2‰ coeval with the carbon isotope excursion. The tight coupling between boron proxies and carbon isotope records is consistent with the interpretation that oceanic absorption of the carbon released at the onset of the PETM resulted in widespread surface ocean acidification. The remarkable similarity among records from different ocean regions suggests that the degree of ocean carbonate change was globally near uniform. We attribute the global extent of surface ocean acidification to elevated atmospheric carbon dioxide levels during the main phase of the PETM.This article is part of a discussion meeting issue 'Hyperthermals: rapid and extreme global warming in our geological past'.

Ocean Acidification: An Introduction

Ocean acidification (OA) generally refers to the ongoing decrease in ocean pH. Ocean acidification is caused primarily by the oceanic uptake of excess carbon dioxide (CO2) from the atmosphere. Other impacts related to climate change (increased sea level rise, coastal flooding and extreme weather events) often receive more attention than OA, but the acidification of the Earth’s oceans is well documented and is a major concern for the marine science community. This publication is the first in a series that addresses ocean acidification in Florida. It specifically explains the changes that are occurring to the chemistry of our coastal and oceanic waters because of elevated carbon dioxide levels. Additional publications address potential environmental, economic, and social implications for Florida.

Bilateral carotid sinus nerve transection exacerbates morphine-induced respiratory depression

Opioid-induced respiratory depression (OIRD) involves decreased sensitivity of ventilatory control systems to decreased blood levels of oxygen (hypoxia) and elevated levels of carbon dioxide (hypercapnia). Understanding the sites and mechanisms by which opioids elicit respiratory depression is pivotal for finding novel therapeutics to prevent and/or reverse OIRD. To examine the contribution of carotid body chemoreceptors OIRD, we used whole-body plethysmography to evaluate hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses including changes in frequency of breathing, tidal volume, minute ventilation and inspiratory drive, after intravenous injection of morphine (10 mg/kg) in sham-operated (SHAM) and in bilateral carotid sinus nerve transected (CSNX) Sprague-Dawley rats. In SHAM rats, morphine produced sustained respiratory depression (e.g., decreases in tidal volume, minute ventilation and inspiratory drive) and reduced the HVR and HCVR responses. Unexpectedly, morphine-induced suppression of HVR and HCVR were substantially greater in CSNX rats than in SHAM rats. This suggests that morphine did not compromise the function of the carotid body-chemoafferent complex and indeed, that the carotid body acts to defend against morphine-induced respiratory depression. These data are the first in vivo evidence that carotid body chemoreceptor afferents defend against rather than participate in OIRD in conscious rats. As such, drugs that stimulate ventilation by targeting primary glomus cells and/or chemoafferent terminals in the carotid bodies may help to alleviate OIRD.

Adaptive physiological response, carbon partitioning, and biomass production of Withania somnifera (L.) Dunal grown under elevated CO2 regimes.

Winter cherry or Ashwagandha (Withania somnifera) is an important medicinal plant used in traditional and herbal medicine system. Yet, there is no information available on response of this plant to changing climatic conditions particularly elevated atmospheric CO2 concentrations. Therefore, we conducted an experiment to examine the effect of elevated CO2 concentrations (ECs) on Withania somnifera. The variations in traits of physiological adaptation, net primary productivity, carbon partitioning, morphology, and biomass in response to elevated CO2 concentrations (ambient, 600 and 800µmol mol-1) during one growth cycle were investigated within the open top chamber (OTC) facility in the foothill of the Himalayas, Dehardun, India. ECs significantly increased photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, soil respiration, net primary productivity and the carbon content of plant tissues (leaf, stem, and root), and soil carbon. Furthermore, ECs significantly enhanced biomass production (root and shoot), although declined night leaf respiration. Overall, it was summarized that photosynthesis, stomatal conductance, water use efficiency, leaf, and soil carbon and biomass increased under ECs rendering the physiological adaptation to the plant. Increased net primary productivity might facilitate mitigation effects by sequestering elevated levels of carbon dioxide. We advocate further studies to investigate the effects of ECs on the accumulation of secondary metabolites and health-promoting substances of this as well as other medicinal plants.

Persistent Environmental Stress Delayed the Recovery of Marine Communities in the Aftermath of the Latest Permian Mass Extinction

AbstractThe aftermath of the latest Permian mass extinction is a key interval for the evolution of modern marine ecosystems. It has been hypothesized that the magnitude of the mass extinction delayed the subsequent recovery, and so to test this, we undertook the highest resolution study to date of the post‐extinction (Griesbachian) microbialite unit on the Great Bank of Guizhou, south China. The benthic community from the microbialite unit is taxonomically diverse when compared to other coeval deposits, recording both inarticulate and articulate brachiopods, crinoids, echinoids, bivalves, gastropods, microconchids, and ostracods. Here we recognize 49 taxa from 4,557 individuals, which raise the known diversity of the Great Bank of Guizhou basal microbialite unit to 84 invertebrate species, making it the most diverse Early Triassic community currently reported. About 89% of the genera are Permian holdovers, whilst only 13% of the species are Permian holdovers. These new data record no temporal trends in the species richness, Simpson diversity, Simpson effective diversity, taxonomic distinctness, functional diversity, or body size of the benthos during the post‐extinction microbialite unit. Nevertheless, the small body sizes of the benthic community, prevalence of opportunistic taxa (e.g., Claraia), and the large lophophoral cavity in the lingulid brachiopod, Sinolingularia huananensis, suggests that these animals lived in a highly stressed environment. We propose that the microbialite unit contains a survival fauna in an interval that represents persistent environmental stress from the latest Permian mass extinction event, associated with deoxygenation, high temperatures, elevated atmospheric carbon dioxide levels (pCO2), and elevated primary productivity.

Performance of PICS bags under extreme conditions in the sahel zone of Niger

Experiments in Niger assessed whether extreme environmental conditions including sunlight exposure affect the performance of triple-layer PICS bags in protecting cowpea grain against bruchids. Sets of PICS bags and woven polypropylene bags as controls containing 50 kg of naturally infested cowpea grain were held in the laboratory or outside with sun exposure for four and one-half months. PICS bags held either inside or outside exhibited no significant increase in insect damage and no loss in weight after 4.5 months of storage compared to the initial values. By contrast, woven bags stored inside or outside side by side with PICS bags showed several-fold increases in insects present in or on the grain and significant losses in grain weight. Grain stored inside in PICS bags showed no reduction in germination versus the initial value but there was a small but significant drop in germination of grain in PICS bags held outside (7.6%). Germination rates dropped substantially more in grain stored in woven bags inside (16.1%) and still more in woven bags stored outside (60%). PICS bags held inside and outside retained their ability to maintain internal reduced levels of oxygen and elevated levels of carbon dioxide. Exposure to extreme environmental conditions degraded the external polypropylene outer layer of the PICS triple-layer bag. Even so, the internal layers of polyethylene were more slowly degraded. The effects of exposure to sunlight, temperature and humidity variation within the sealed bags are described.

Enhanced astaxanthin accumulation in Haematococcus pluvialis using high carbon dioxide concentration and light illumination

In this study, an economical two-stage method was proposed for the production of natural astaxanthin from Haematococcus pluvialis without a medium replacement step. In stage 1, H. pluvialis were grown under low light illumination until they reached optimal biomass. In stage 2, cells were switched to astaxanthin induction conditions utilizing the combination of high light illumination and elevated carbon dioxide levels (5 or 15%). The introduction of CO2 altered the C/N balance creating a nutrient deficiency without a change of media. The resulting astaxanthin yield was 2–3 times that of using either stressor alone. This astaxanthin induction method has many advantages over current methods including no medium replacement and a short induction time of less than four days.

Performance of the Silverman Andersen Respiratory Severity Score in predicting PCO2 and respiratory support in newborns: a prospective cohort study

Objective:To determine if the Silverman Andersen respiratory severity score, which is assessed by physical exam, within 1 h of birth is associated with elevated carbon dioxide level and/or the need for increased respiratory support.Study design:Prospective cohort study including 140 neonates scored within 1 h of birth. We report respiratory scores and their association with carbon dioxide and respiratory support within 24 h.Results:Carbon dioxide level correlated with respiratory score (n = 33, r = 0.35, p = 0.045). However, mean carbon dioxide for patients with score <5 vs. ≥5 did not differ significantly (56 vs. 67, p = 0.095). Patients with respiratory scores ≥5 had respiratory support increased within 24 h more often than those with scores <5 (79% vs. 28%, p < 0.001).Conclusion:The Silverman Andersen respiratory severity score may be valuable for predicting need for escalation of respiratory support and facilitate decision making for transfer in low-resource settings.

Effect of Elevated Air Temperature and Carbon Dioxide Levels on Dry Season Irrigated Rice Productivity in Bangladesh

Agricultural productivity is affected by air temperature and CO2 concentration. The relationships among grain yields of dry season irrigated rice (Boro) varieties (BRRI dhan28, BRRI dhan29 and BRRI dhan58) with increased temperatures and CO2 concentrations were investigated for futuristic crop management in six regions of Bangladesh using CERES-Rice model (DSSATv4.6). Maximum and minimum temperature increase rates considered were 0°C, +1°C, +2°C, +3°C and +4°C and CO2 concentrations were ambient (380), 421, 538, 670 and 936 ppm. At ambient temperature and CO2 concentration, attainable grain yields varied from 6506 to 8076 kg·ha-1 depending on rice varieties. In general, grain yield reduction would be the highest (13% - 23%) if temperature rises by 4°C and growth duration reduction would be 23 - 33 days. Grain yield reductions with 1°C, 2°C and 3°C rise in temperature are likely to be compensated by increased CO2 levels of 421, 538 and 670 ppm, respectively. In future, the highest reduction in grain yield and growth duration would be in cooler region and the least in warmer saline region of the country. Appropriate adaptive techniques like shifting in planting dates, water and nitrogen fertilizer management would be needed to overcome climate change impacts on rice production.

Analyzing the Long-Term Phenological Trends of Salt Marsh Ecosystem across Coastal LOUISIANA

In this study, we examined the phenology of the salt marsh ecosystem across coastal Louisiana (LA) for a 16-year time period (2000–2015) using NASA’s Moderate Resolution Imaging Spectroradiometer’s (MODIS) eight-day average surface reflectance images (500 m). We compared the performances of least squares fitted asymmetric Gaussian (AG) and double logistic (DL) smoothing functions in terms of increasing the signal-to-noise ratio from the raw phenology derived from the time-series composites. We performed derivative analysis to determine the appropriate start of season (SOS) and end of season (EOS) thresholds. After that, we extracted the seasonality parameters in TIMESAT, and studied the effect of environmental disturbances/anomalies on the seasonality parameters. Finally, we performed trend analysis using the derived seasonality parameters such as base green biomass (GBM) value, maximum GBM value, seasonal amplitude, and small seasonal integral. Based on root mean square error (RMSE) values and residual plots, we selected the best thresholds for SOS (5% of amplitude) and EOS (20% of amplitude), along with the best smoothing function. The selected SOS and EOS thresholds were able to capture the environmental disturbances that have affected the salt marsh ecosystem during the 16-year time period. Our trend analysis results indicate positive trends in the base GBM values in the salt marshes of LA. However, we did not notice as much of a positive trend in the maximum GBM levels. Hence, we observed mostly negative changes in the GBM amplitude and small seasonal integral values. These negative changes indicated the overall progressive decline in the rates of photosynthesis and biomass allocation in the LA salt marsh ecosystem, which is most likely due to elevated atmospheric carbon dioxide levels and sea level rise. The results illustrate both the relative efficiency of MODIS-based biophysical models for analyzing salt marsh phenology, and performances of the smoothing techniques in terms of improving the signal-to-noise ratio of the MODIS-derived phenology.

Effects of elevated carbon dioxide and temperature on crop yield: a modeling study

Food security is one of the burning issues at present. The elevated levels of atmospheric carbon dioxide (\(\hbox {CO}_2\)) and temperature are anticipated to affect the yield of staple food crops. In this paper, we have formulated a nonlinear mathematical model to study the crop response to the elevated levels of \(\hbox {CO}_2\) and temperature. Qualitative analysis of the model is performed to assess the long-term behavior of the system. The model analysis provides a condition under which the increase in anthropogenic \(\hbox {CO}_2\) emission leads to decrease in the equilibrium level of crop yield. The analytical results are validated through numerical simulation for the case of wheat yield in India. The future projections of wheat yield in India are depicted in various scenarios. Sensitivity analysis is performed to explore the effect of changes in the key parameters on the wheat yield.

The effect of carbon dioxide on growth and energy metabolism in pikeperch (Sander lucioperca)

Pikeperch (Sander lucioperca) is a popular fish for human consumption and decreasing wild catches increase the demand for aquaculture production. Limited knowledge of the species' requirements under intense recirculating aquaculture system (RAS) culture conditions has motivated this study to focus on the effect of elevated carbon dioxide (CO2) levels on pikeperch metabolism. The trial was conducted in a recirculating aquaculture respirometer system with pikeperch (average body weight 251.9g) and three hypercapnia regimes over 58 feeding days. Food grade CO2 gas was gradually added to the medium (15mgL−1) and high (30mgL−1) treatments while no gas was added to the low treatment (hence 4mgL−1). Fish were fed daily for 10min with a commercial diet (ALLER Metabolica). O2, T, pH, CO2 were measured individually for each tank and logged every 2h to calculate oxygen consumption rates of each treatment. Total Ammonia-Nitrogen was measured monthly for individual tanks and used to calculate TAN excretion. Results showed a linear decrease of 6% in final body weight with increasing CO2 levels between the low and the high CO2 treatment. Feed intake was linearly increased after four weeks of the experiment from 0.97±0.07% in the low CO2 treatment to 0.86±0.03% in the high CO2 treatment but the effect faded after eight weeks, indicating a habituation to the hypercapnia conditions. High levels of CO2 were associated with reductions in haematocrit and metabolic oxygen consumption. The results suggest that adult pikeperch can survive carbon dioxide concentrations of up to 30mgL−1 when other water quality parameters are in acceptable levels but will be affected in metabolism already at moderate CO2 levels of 15mgL−1.

Direct climate change impacts on growth and drought risk in blue gum (Eucalyptus globulus) plantations in Australia

ABSTRACTAustralia’s climate is changing and Australia’s forests have been identified as vulnerable to climate change impacts. The process-based model CABALA, an ensemble of global circulation models, and a range of scenarios on plant response to elevated CO2 (eCO2) and site conditions, were used to predict the direct effects of climate change on the productivity and mortality risks for Australia’s blue gum (Eucalyptus globulus) plantation estate. The modelling showed considerable uncertainty about future outcomes across large parts of the estate, with best-case and worst-case scenarios varying from decreased to increased production. In some areas we can be confident of future outcomes. Nevertheless, it is clear that, across the whole estate, appropriate management can reduce risk and ensure that we are able to capitalise on potential beneficial aspects of climate change. Under most future scenarios, without adaptation, the drier parts of the plantation estate are at risk. However, in all but the eastern areas of Western Australia, and at the driest margins of the estate in South Australia and Victoria, adaptation options can reduce risk and ensure productivity. Other areas currently at the cold margins of the estate, notably the highlands of Victoria and across Tasmania, appear to increase in productivity under most future scenarios. Even in those areas where productivity may potentially increase, experience suggests that pests and diseases may pose a risk. If we are to benefit from any aspect of climate change, then pursuit of best-practice sustainable forest management is critical. The greatest source of uncertainty in forecasts is associated with how photosynthesis in field-grown trees will respond to elevated atmospheric carbon dioxide levels (eCO2). Regional differences in global circulation model forecasts are important, particularly in Western Australia, where the extent of future rainfall decline significantly impacts predictions. Local site factors, exemplified in this study by soil depth, will play an important role in modulating climate change impacts, particularly through their role in constraining responses to eCO2.

Natural content of gases: Carbon monoxide, carbon dioxide, hydrogen and unsaturated hydrocarbons of ethylene, propylene and acetylene in selected bituminous coal seams

Chromatographic analysis of gas desorbed from coal reveals the presence of carbon monoxide, carbon dioxide, hydrogen, ethylene, propylene and acetylene, i.e. gaseous components liberated into the mine atmosphere with the increasing temperature of self-heating coal. Elevated levels of carbon monoxide, dioxide and ethylene were registered as well. Investigations showed that these gases are contained in the coal structure and their liberation to the mine air can be triggered by other factors apart from coal self-heating, for example coal fragmentation or disturbing of the virgin coalbeds by mining operations. The amounts of thus desorbed gases can alter their actual concentrations in the mine air, which serve as indicators of the self-heating propensity of coal. No straightforward relationship was established between the concentrations of individual gaseous components in the mixed-gas desorbed from coals sample and the rank and other physico-chemical properties of coals.Sorption and desorption tests by the volumetric method demonstrated that the volume of sorbed carbon monoxide and dioxide, hydrogen, ethylene, propylene and acetylene is closely related to the coal rank and its porous structure. Low-rank coals with well-developed pore systems tend to absorb/adsorb greater amounts of gases than low-rank coals with a less developed pore structure.Tests established the intensity of gas desorption from coals, showing that nearly 80–90% of carbon monoxide, dioxide and hydrogen accumulated in coals would be released. In the case of adsorbed ethylene, propylene and acetylene that proportion is the lowest (50%–70%).Recalling the Ideal Adsorbed Solution (IAS) theory, simulations were performed to predict the mixed-gas adsorption isotherms for binary gas mixtures containing non-saturated hydrocarbons-gas components that are indicators of the self-heating propensity of coal. It appears that acetylene adsorption in the systems C2H2C2H4 and C2H2C3H6 is a favoured process whilst preferential adsorption in the system C3H6C2H4 is that of propylene.

The effect of respiratory gas composition on kidney stone detection with the color Doppler ultrasound twinkling artifact

The color Doppler ultrasound twinkling artifact, which is thought to arise from microbubbles on and within the stone, has the potential to improve kidney stone detection in space; however, bubbles are known to be sensitive to the elevated levels of carbon dioxide (CO2) found on space vehicles. Here, we investigate the effect of respiratory gas composition on twinkling in swine implanted with kidney stones. Thirteen swine were initially exposed to either 100% oxygen (O2) or room air and then to air with elevated CO2 at 0.8%, 0.54%, or 0.27%. Stones were imaged with a Verasonics ultrasound system and ATL P4-2 transducer. The 9 swine initially breathing 100% O2 showed a significant reduction in twinkling when exposed to air with elevated CO2, with the degree of decrease in twinkling occurring in the order: 0.8%>0.54%>0.27% CO2. An additional 4 swine were oscillated between air with 0.04% CO2 (normal air) and 0.5% CO2. A reduction in twinkling was observed over the course of the experiment. The effect of respiratory gas composition should be further investigated before using twinkling to diagnose a kidney stone in space. [Work supported by NSBRI through NASA NCC 9-58 and NIH DK043881.]

Innovative strategies for improved outcomes in nephrolithiasis

Edwin Carstensen, Ph.D., was an advisor of NIH NIDDK Program Project Grant DK043881, created to investigate shock wave lithotripsy (SWL). We now develop solutions to improve all aspects of the management of stone disease. Our goal in this paper is to report progress built on Dr. Cartsensen's advice and inspiration. The work ranges from numerical simulation to clinical trials and from device development to bioeffects and metrology. Much of our work involves bubbles and cavitation. This work has contributed to the body of knowledge defining limits for the safe use of ultrasound which Dr. Carstensen worked hard to establish. Specifically, an update will be given on the development of ultrasound to image, fragment, trap, and reposition stones. In particular, we demonstrated bubbles contribute to the twinkling artifact used by NASA and others to image stones, and we drew on Dr. Carstensen's paper [UMB, 19(2) 147-165 1993] to demonstrate that breathing the elevated carbon dioxide levels present in NASA vehicles...

Elevated carbon dioxide level along with phosphorus application and cyanobacterial inoculation enhances nitrogen fixation and uptake in cowpea crop

ABSTRACTClimate change, as a result of increase in the concentration of greenhouse gases, influences growth and productivity of leguminous crops. A study was carried out to analyse the impacts of elevated carbon dioxide (CO2) and cyanobacterial inoculation on growth, N2 fixation and N availability and uptake in cowpea crop, under different doses of phosphorus. Cowpea crop was grown under ambient (400 µmol mol−1) and elevated (550 ± 20 µmol mol−1) CO2 levels using Free-Air Carbon dioxide Enrichment facility. Elevated CO2 level increased chlorophyll content in leaves, improved nodulation and nitrogen fixation by the crop. Increase in P dose up to 16 mg kg−1 soil enhanced nodule development and N2 fixation under high CO2 condition. Cyanobacterial inoculation increased nodule weight, leghaemoglobin content in nodules and total nitrogenase activity. Although nitrogen concentration in cowpea seeds decreased in high CO2 treatment, higher N uptake was recorded. Under elevated CO2 condition, cyanobacterial inoculation and higher P doses led to enhanced root growth and N2 fixation and availability of soil nitrogen. The study illustrated the synergistic effect of high CO2 and cyanobacterial inoculation in enhancing crop growth and availability of soil N, mediated by biological N2 fixation in cowpea under different levels of P.

Toxicity of propylene oxide alone and in combination with low pressure or carbon dioxide against life stages of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) under laboratory conditions

A series of tests was carried out in the laboratory for comparison of the insecticidal effect of propylene oxide (PPO) alone and in combination with low pressure and/or elevated levels of carbon dioxide against eggs, larvae, pupae and adults of Ephestia cautella (Walker) (Lepidoptera: Pyralidae). All life stages of E. cautella were exposed to PPO alone and in combination with either a low pressure of 100 mm Hg or 92% CO2 for 4 h at 26 ± 1 °C and 65 ± 5% relative humidity (r.h.). The results indicated that PPO alone was moderately effective with concentration x time products (Ct products) required to obtain 99% mortality of the different life stages of E. cautella ranging between 66.1 and 536.2 mg h/L. The life stages differed in their susceptibility to PPO. Eggs were the most susceptible with a LC99 value of 16.5 mg/L, whereas pupae were the most tolerant with a LC99 value of 134.1 mg/L. Mortality of all life stages was extremely low (1.3–18.8%), when exposed to either the low pressure or 92% CO2 alone for 4 h. However, when low pressure or 92% CO2 were combined with PPO, the LC50 and LC99 values for all stages of E. cautella were notably reduced. Combination of PPO with low pressure or 92% CO2 caused reductions in the LC99 values for all life stages, compared with those exposed to PPO alone. These results indicated that low pressure (100 mm Hg, equals to 13,332 Pa or 0.13 atm) and 92% CO2 clearly increased the efficacy of PPO to E. cautella. By considering the overall insecticidal efficacy data, the combination of PPO with low pressure was, in all cases, more effective than the combination of PPO with CO2.

KrillDB: A de novo transcriptome database for the Antarctic krill (Euphausia superba).

Antarctic krill (Euphausia superba) is a key species in the Southern Ocean with an estimated biomass between 100 and 500 million tonnes. Changes in krill population viability would have catastrophic effect on the Antarctic ecosystem. One looming threat due to elevated levels of anthropogenic atmospheric carbon dioxide (CO2) is ocean acidification (lowering of sea water pH by CO2 dissolving into the oceans). The genetics of Antarctic krill has long been of scientific interest for both for the analysis of population structure and analysis of functional genetics. However, the genetic resources available for the species are relatively modest. We have developed the most advanced genetic database on Euphausia superba, KrillDB, which includes comprehensive data sets of former and present transcriptome projects. In particular, we have built a de novo transcriptome assembly using more than 360 million Illumina sequence reads generated from larval krill including individuals subjected to different CO2 levels. The database gives access to: 1) the full list of assembled genes and transcripts; 2) their level of similarity to transcripts and proteins from other species; 3) the predicted protein domains contained within each transcript; 4) their predicted GO terms; 5) the level of expression of each transcript in the different larval stages and CO2 treatments. All references to external entities (sequences, domains, GO terms) are equipped with a link to the appropriate source database. Moreover, the software implements a full-text search engine that makes it possible to submit free-form queries. KrillDB represents the first large-scale attempt at classifying and annotating the full krill transcriptome. For this reason, we believe it will constitute a cornerstone of future approaches devoted to physiological and molecular study of this key species in the Southern Ocean food web.

Effect of Carbon Dioxide on the Twinkling Artifact in Ultrasound Imaging of Kidney Stones: A Pilot Study

Bone demineralization, dehydration and stasis put astronauts at increased risk of forming kidney stones in space. The color-Doppler ultrasound “twinkling artifact,” which highlights kidney stones with color, can make stones readily detectable with ultrasound; however, our previous results suggest twinkling is caused by microbubbles on the stone surface which could be affected by the elevated levels of carbon dioxide found on space vehicles. Four pigs were implanted with kidney stones and imaged with ultrasound while the anesthetic carrier gas oscillated between oxygen and air containing 0.8% carbon dioxide. On exposure of the pigs to 0.8% carbon dioxide, twinkling was significantly reduced after 9–25 min and recovered when the carrier gas returned to oxygen. These trends repeated when pigs were again exposed to 0.8% carbon dioxide followed by oxygen. The reduction of twinkling caused by exposure to elevated carbon dioxide may make kidney stone detection with twinkling difficult in current space vehicles.