News Article | April 22, 2016
SANTIAGO (Reuters) - Salmon producer AquaChile said on Friday that it has discovered the presence of the ISA virus, which is potentially deadly for the fish, at one of its pens in Chile's southern Aysen region.
News Article | January 26, 2016
An India-led global coalition of nations with substantial solar energy resources has announced grand plans to raise financial resources to expedite development in the solar power sector. A high-ranking official of the Indian Ministry of New & Renewable Energy (MNRE) recently stated that the International Solar Alliance (ISA) aims to raise as much as $1 trillion. The funds will be used for exercises of capacity building, developing new and innovative policies, and setting up financial mechanisms to set up projects and for research and development. The idea of the International Solar Alliance was first floated by the Indian Government to enhance cooperation among nations with significant solar power resources. The current membership of the ISA is said to be over 120 countries, mostly those located between the Tropics of Cancer and Capricorn. However, countries lying outside these latitudes are also welcome to join, the MNRE official clarified. The first international steering committee meeting was held 18 January in Abu Dhabi. The Alliance will look to international development banks and financial institutions like the World Bank, Asian Development Bank, and KfW. Private sector companies will also be tapped for rating capital. Fortum Energy, a Finland-based solar power project developer, has already expressed interest in contributing. Fortum Energy recently placed a new record-low tariff bid for solar PV project in the state of Rajasthan. The interim Secretariat of the ISA was recently inaugurated in India by Indian Prime Minister Narendra Modi and French President Francois Hollande. President Hollande also made a commitment of €300 million on behalf of the French Development Agency for the ISA. India, itself, has one of the most ambitious solar power targets in the world. The country plans to have an operational solar power capacity of 100 GW by March 2022. The current installed capacity is just over 5 GW. The solar power target is the mainstay of India’s commitment to reduce greenhouse gas emissions submitted to the United Nations last year. Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
The following reagents were purchased from Sigma Aldrich (St Louis, MO): calcium chloride dihydrate (ACS Reagent, 99+%), sodium oxalate (Na C O , >99%), sodium hydroxide (98%), hydrochloric acid (37%), sodium citrate tribasic dihydrate (ACS reagent, ≥99.0%), and potassium hydroxycitrate tribasic monohydrate (95%). Sodium chloride (99.9% ultrapure bioreagent) was purchased from JT Baker. Deionized water used in all experiments was purified with an Aqua Solutions RODI-C-12A purification system (18.2 MΩ). All reagents were used as received without further purification. Garcinia cambogia was purchased from Swanson Health Products (Super CitriMax Clinical Strength Garcinia Cambogia Extract, item SWD051). The recommended serving size (2 capsules) contained the following components and corresponding mass per serving: calcium (120 mg), chromium (130 μg), potassium (180 mg), and garcinia cambogia extract (1.5 g) containing HCA (900 mg). Batch crystallization was carried out in a 20-ml glass vial by dissolving NaCl in deionized water, then adding 0.7 ml of 10 mM CaCl stock solution. A clean glass slide (about 1.3 × 1.3 cm2) was placed at the bottom of the vial to collect the crystals for microscopy. The sample vial was then placed in an oven set to 60 °C for 1 h to ensure the solution reached the set point temperature for crystallization. Subsequently, 0.7 ml of 10 mM Na C O stock solution was added to the vial dropwise while continuously stirring at a rate of about 400 r.p.m. To investigate the effect of growth inhibitors (that is, CA or HCA) on COM crystallization, an appropriate quantity of the inhibitor was added to the growth solution before Na C O addition. The final growth solution had a composition of 0.7 mM CaCl :0.7 mM Na C O :150 mM NaCl:x μg ml−1 inhibitor (where x = 0–100) and a total volume of about 10 ml. Crystallization was performed at 60 °C for 3 days at static conditions (that is, without stirring or agitation). The glass slide (substrate) was removed from the solution, gently washed with deionized water, and dried at room temperature before analysis. The pH of COM growth solution was measured before and after crystallization using an Orion 3-Star Plus pH benchtop meter with a ROSS Ultra electrode (8102BNUWP). The size and morphology of COM crystals prepared in the absence and presence of inhibitors was assessed by optical microscopy using a Leica DM2500-M instrument. Brightfield images were obtained in reflectance mode to quantify the crystal dimensions, which we report as length L in the  direction, width W in the  direction, and the length-to-width (L/W) aspect ratio. A minimum of 150 crystals from three separate batches were measured to obtain an average aspect ratio for data reported in Fig. 1f. COM crystal number density, ρ , was measured as the number of crystals per area of glass slide. The ρ values reported in Fig. 1i are an average of at least ten areas on glass slides from three separate batches (each micrograph area is 647 μm × 484 μm). The COM  thickness was measured from a combination of optical and electron micrographs. Scanning electron microscopy (SEM) was performed using a FEI 235 Dual-Beam Focused Ion-beam instrument equipped with a SEM sample extraction probe. SEM samples were prepared by gently pressing COM crystals on the glass slide to carbon tape to transfer crystals to the sample disk. Each sample was coated with a layer of carbon (about 20 nm thick) to reduce the effects of electron beam charging. The average values reported in Fig. 1g were obtained from measurements of more than 150 crystals from three separate batches. The effect of growth inhibitors on the kinetics of COM crystallization was measured using a calcium ISE from ThermoScientific equipped with an Orion 9720BNWP ionplus electrode. ISE measurements track the temporal reduction in free calcium ion concentration in the growth solution during crystallization (including the effects of both nucleation and crystal growth)34. Growth solutions were prepared similar to COM bulk crystallization, but at room temperature using a solution with supersaturation ratio S = 3.8 and a composition of 0.5 mM CaCl :0.5 mM Na C O :150 mM NaCl:x μg ml−1 inhibitor (where x = 0–100). For ISE studies, we used the calcium oxalate solubility product reported by ref. 35 in order to calculate the calcium oxalate supersaturation. ISE measurements were performed at room temperature under constant stirring (about 1,200 r.p.m.) to minimize the induction time22, 34. Plots of consumed calcium ion concentration as a function of time were generated for each inhibitor concentration. A minimum of eight measurements were performed for each data point reported in Fig. 1h. The data were normalized by subtracting the concentration of the initial time point (see Extended Data Fig. 1). The approximate linear slope of these curves during the first 40 min of crystallization corresponds to the rate of Ca2+ depletion. The efficacy of growth inhibitors was determined by the percentage inhibition, which was calculated by comparing the change in slope of the growth curve in the presence of inhibitor relative to that in the absence of inhibitor (that is, the control). Prior to ISE measurements, the electrode was calibrated using a standard calcium solution (0.1 M, Orion Ion Plus), which was diluted with deionized water to three concentrations: 0.1 mM, 1.0 mM and 10.0 mM. The ionic strength of each solution was adjusted using a standard solution (ISA, Thermo Scientific), which was added in a 1:50 volume ratio of ISA-to-standard. In situ AFM was performed using a Digital Instruments Multimode IV (Santa Barbara, CA) to examine topographical images of COM crystals and capture the dynamics of surface growth in real time. COM crystals (about 50 μm in length) were mounted on an AFM specimen disk (Ted Pella) covered with a thin layer of thermally curable epoxy (MasterBond EP21AOLV), in accordance with previously reported protocols22, 36, 37. The epoxy was partially cured in an oven for about 20 min at 60 °C. COM crystals on glass slides from bulk crystallization assays (in the absence of inhibitor) were immobilized on the partially cured epoxy by gently pressing the glass slide to transfer crystals with either their (100) or (010) faces oriented normal to the specimen surface. The sample was then placed in an oven at 60 °C for an additional 3 h to completely cure the epoxy. All AFM measurements were performed using silicon nitride probes with gold reflex coating and a spring constant of 0.15 N m−1 (Olympus, TR800PSA). In situ experiments were performed to monitor surface growth in supersaturated calcium oxalate solution. We measured the velocity of step advancement and changes in hillock morphology on COM (010) and (100) surfaces in the absence or presence of inhibitors. The reported step velocity (Fig. 2e) is the average of at least 5 measurements of different steps. For in situ AFM measurements, a growth solution with supersaturation ratio S = 4.1 was prepared, similar to the solution used for ISE measurements, but with a composition of 0.18 mM CaCl :0.18 mM Na C O :x μg ml−1 inhibitor (where x = 0–2.1). The inhibitor concentration used in AFM measurements is lower than that employed in bulk crystallization22, 37 owing to fewer crystals (that is, smaller COM surface area) on the AFM specimen disk. The AFM instrument was equipped with a fluid cell (model MTFML) containing two ports for inlet and outlet flow to maintain constant supersaturation during continuous imaging. The growth solution was delivered to the liquid cell using a dual syringe pump (CHEMYX, Fusion 200) with an in-line mixing configuration38 to combine CaCl and Na C O solutions with a combined flow rate of 0.2 ml min−1. Inhibitors were introduced into the Na C O solution at the appropriate concentration (taking into account the effect of dilution at the in-line flow connection). Continuous imaging was performed in contact mode with a scan rate of 7.0–9.2 Hz at 256 lines per scan. The upper limit of metastability was measured using a modified version of the method described by ref. 30. Urine aliquots were obtained over a 24-h urine collection period from eight patients with kidney stones. All urine samples were brought to a pH of 5.7 by the addition of potassium hydroxide or HCl as needed. Each urine sample was studied with no additive or with either CA or HCA added to increase their concentration by 2 mM. For each sample, 200 μl of urine was added to 12 wells of a 96-well microlitre plate. Solutions of increasing concentration of Ox were pipetted into the urine aliquots in the wells. The plate was placed on a shaker for 3 h at 37 °C and then the turbidity of solutions in each well were measured at 620 nm wavelength using a VMax kinetic ELISA microplate reader (Molecular Devices, Sunnyvale, CA). The well at which turbidity increased determined the point of crystallization and the Ox concentration at this point is the amount of Ox in the urine measured at baseline plus the amount of Ox added to the urine in the well showing increased turbidity. The results are presented as the calcium oxalate concentration product (used as a surrogate of supersaturation) at the point of crystallization (see Fig. 4a). In addition to their crystal inhibition activity, both CA and HCA complex calcium in solution, lowering the concentration of ionized calcium. Both mechanisms should contribute to changes in the upper limit of metastability relative to the control, indicative of an inhibition of nucleation. Each urine sample was run in duplicate and the results were averaged. Statistical comparison was performed using the non-parametric Wilcoxon test. There were no prior reports of measurements of HCA in human urine in people not consuming HCA supplement. We tested the hypothesis that HCA is not a normal constituent of human urine by measuring the concentration of HCA in random urine samples from five healthy subjects (protocol number 1061857 Western Institutional Review Board). The hypothesis of the human trial study was that HCA, when orally administered, will be excreted in urine. To test this hypothesis, we assessed urinary excretion to confirm the bioavailability of HCA through oral administration. The protocol was approved by the University of Houston Internal Review Board (case 15176-01). Recruitment was limited to subjects between 21 and 65 years of age. Pregnant women and subjects with known severe chronic kidney disease (stage 4 or 5) were excluded. All samples were collected and analysed with informed consent. The supplement used in the human trial was Super CitriMax Clinical Strength Garcinia Cambogia Extract. The active ingredient, HCA, is an inhibitor of ATP citrate lyase and is presumed to reduce lipogenesis as its mechanism of action for inducing weight loss31. Each serving (2 capsules) contained 1.5 g garcinia cambogia extract with 900 mg active ingredient. The subjects were asked to take garcinia cambogia extract for three days at the dose recommended by the manufacturer (that is, two capsules three times a day). On the third day of garcinia cambogia treatment, the subjects collected urine for 24 h. The urine was collected unrefrigerated using an antimicrobial preservative. HCA concentration was measured by ion chromatography using an ICS-2000 system (Dionex Corp., Sunnyvale, CA) with AS11 guard and analytic columns, potassium hydroxide eluent, and a conductivity detection system. Because isocitrate co-elutes with HCA on this system, urine samples were pre-treated with isocitrate dehydrogenase to remove isocitrate interference. Hydroxycitric acid calcium salt, (−)-(P), purchased from ChromaDex Inc. (Irvine, CA) was used as a standard. Molecular orbital DFT calculations were performed using the Turbomole/6.6 program package39. We used the BP86 functional40, 41 and accounted for dispersion energy corrections through the D3 method42 appropriate for capturing hydrogen bonds originating by the presence of HCA and CA inhibitors. The BP86 method has been shown to successfully capture the aggregation behaviour of metal–cation complexed organic acids43. The resolution of identity44 approximation along with multipole accelerated resolution of indices (MARI-J)45 were used to accelerate the calculations. We used the def2-SV(P) basis set46 and accounted for solvent effects through the COSMO continuum solvation model (the solvent was water; dielectric constant ε = 78.46)47. The COM nanoparticle with a (100) surface termination consisted of 168 atoms (Ca C O ), whereas the one with a (021) termination consisted of 133 atoms (Ca C O ). The (001)-to-(100) step consisted of 224 atoms (Ca C O ). We have used the whewellite (monoclinic) crystal unit cell48 to build the COM nanoparticles (with H O molecules being removed and simulated by implicit solvent effects). The (100) and (021) surfaces and (001)-to-(100) step were kept frozen and the inhibitors were allowed to fully relax in our calculations. We also performed calculations where the surface of COM was allowed to relax and the overall adsorption trends remained the same (see partial relaxation calculations in Extended Data Fig. 7). The isomer of HCA in garcinia cambogia was taken into account, consistent with the natural extract used in human trials49. The binding energy of inhibitors and oxalate to crystal surfaces is defined as: where E represents the total electronic energy of species x. For calculations of the ‘inhibitor + COM’ species, the deprotonated forms of the acids were placed on the COM surfaces and their hydrogens (from the deprotonation) were placed at a position far away from the interaction centre and anti-diametric on the COM nanoparticle to bring the system to a neutral charge state and avoid calculations under high charge states (that is, charge counterbalance). The energy of the inhibitor in the gas phase, labelled as E , corresponds to molecules in their protonated (neutral) state. Analogously to the previous expression, the binding energy of the complexes used in determining the affinity of HCA, CA and Ox for Ca2+ is defined as: where n represents the number of organic molecules in the complex, d is the deprotonation state of the inhibitor (that is, d = 1 corresponds to single, d = 2 to double, and d = 3 to triple deprotonated states, equivalently), and E represents the electronic energy of species x. The inhibitor is in the protonated form in the gas phase and we use H as a reference state for the hydrogen of the acids. Approximately four different initial conformations were taken into consideration for each inhibitor–surface and complexation calculation, wherein we report the lowest-energy conformations. Our obtained minima from the optimization calculations were further validated by the absence of any imaginary frequencies on the complexes and on the inhibitors interacting with COM crystal surfaces. To quantify crystal lattice strain, we employ a geometric comparison between the frozen and relaxed structures of COM surfaces in the presence and absence of adsorbates (growth inhibitors). We developed a distance metric to quantify the displacement of relaxed atoms (relative to their frozen state) on COM crystal surfaces by taking the average absolute value of the (x, y, z) coordinate displacements. The average displacement δ is represented as: where N represents the number of atoms that are relaxed on the surface of the COM crystallographic plane. The pH of crystallization media impacts the net charge of the inhibitor. Both CA and HCA have three dissociation constants corresponding to each of their carboxylic acid groups. In physiologically relevant environments, such as the kidney, the pH of urine varies between 5 and 8 (ref. 50). In vitro COM crystallization assays are performed at approximately neutral pH. For instance, the growth solutions employed in this study have pH = 6.2 ± 0.2, which is identical to previous in vitro assays published by Rimer and co-workers22, 34, 37, 51. As shown in Extended Data Fig. 2a, equilibrium calculations at pH 6.2 predict HCA to be predominantly in the fully dissociated state (that is, net charge = −3) while approximately 40% of CA species are in the fully dissociated state, labelled as CA3− or C H O 3−. The acid–base speciation reactions for CA along with the respective dissociation constants, , are the following: The reported pK values were obtained from Martell and Smith52. There are discrepancies in the reported value owing to the ionic strength dependency of the dissociation constant. For instance, some references report = 5.66 when the ionic strength is 100 mM (ref. 52), which is less than the ionic strength of calcium oxalate solutions used in ISE and bulk crystallization assays. On this basis, it is likely that the dominant species in calcium oxalate growth solutions is CA3−. DFT calculations of CA–crystal interactions and CA–calcium ion complexes in the manuscript were performed using CA3−; however, equivalent DFT calculations were performed with CA2−. The results of these calculations, which are presented in Extended Data Figs 6 and 8, reveal that the conclusions reached in the manuscript are not altered by CA charge. Moreover, we conducted bulk crystallization, ISE, and in situ AFM measurements in growth solutions at pH 6.2 (nominal condition) and pH 8.0 to assess the influence of CA charge on its efficacy as a COM crystal inhibitor. At pH 8.0, approximately 99.8% of CA species are in the fully dissociated state (neglecting the effect of ionic strength). Bulk crystallization assays reveal approximately no change in crystal morphology and size at these two pH values. Similarly, in situ AFM measurements at pH 6.2 and 8.0 at C = 0.1 μg ml−1 showed no apparent change in etch pit formation on COM (100) surfaces. ISE experiments at pH 6.2 and 8.0 reveal subtle differences in the percent inhibition of COM growth at C = C = 20 μg ml−1 (Extended Data Fig. 2b). The percent inhibition of COM growth is slightly reduced at higher pH, but HCA is the most effective inhibitor irrespective of solution alkalinity. The speciation reactions and corresponding equilibrium dissociation constants for HCA are the following53: As shown in Extended Data Fig. 2a, the percentage of fully dissociated HCA (labelled as HCA3− or C H O 3−) at pH 6.2 is 92%. At pH 8.0 (that is, the upper limit of urine), the percentage of HCA3− is nearly 100%. As such, DFT calculations in the manuscript were performed using the dominant species, HCA3−. In Extended Data Fig. 4 we provide a detailed analysis of etch pit formation on a COM (100) surface in the presence of C = 0.25 μg ml−1. Time-resolved in situ AFM images at periodic times reveal the formation and growth of etch pits (Extended Data Fig. 4a–c). For each dashed line in the AFM image, the corresponding height profiles are provided in Extended Data Fig. 4d–f, respectively. The nominal growth of hillocks on the (100) surface in the absence of inhibitor (Extended Data Fig. 4d) occurs by the advancement of single steps. Each step has an average height of 0.4 nm, which is the approximate size of the unit cell parameter in the a direction. Upon the addition of HCA, etch pits monotonically evolve in both depth (Extended Data Fig. 4g) and width (Extended Data Fig. 4h) with imaging time. The concentration of inhibitor in this study is approximately three orders of magnitude less than the concentration of Ca2+ ions in supersaturated solution, indicating the effect of etch pit formation is not solely attributed to reduced calcium oxalate supersaturation as a result of inhibitor–calcium ion complexation. Common mechanisms of crystal growth inhibition include step pinning and kink blocking24, 54. The former involves the adsorption of inhibitors on terraces or step edges, which impede the advancement of steps. Inhibitors adsorbed with their average adsorbate-to-adsorbate spacing comparable to the critical radius of curvature r for the step (that is, high surface coverage at high inhibitor concentration) impedes step advancement, leading to reduced step velocity and ultimately suppressed growth when the step radius approaches r (refs 54 and 55). The mode of action for HCA on COM crystallization at low inhibitor concentration, as inferred from time-resolved AFM images of the COM (010) surface, does not appear to be step pinning owing to the absence of protrusions on steps (which is a characteristic trait of inhibitors that operate by a step-pinning mode of action54). AFM measurements of COM (100) surface growth at high concentration of either CA or HCA reveal the formation of irregular-shaped steps, which may indicate that inhibitors bind to step edges on this surface (consistent with a previously proposed mechanism for CA inhibition21). Kink blocking is commonly observed when the crystal grows by a screw dislocation mechanism56, 57 wherein inhibitors adsorb to kink sites and reduce the kink density and extend the critical length of the step13. The net result is a decreased rate of step advancement within the plane of measurement, as well as reduced growth of hillocks in the direction normal to this plane. AFM studies of COM growth have shown that steps emanating from screw dislocations on the (100) and (010) surfaces advance across the crystal plane. Burton, Cabrera and Frank56 derived a theoretical model of spiral growth predicting the rate of crystal growth normal to the basal face, G , as follows: where h is the height of (hkl) steps advancing along the COM (100) plane, y is the interstep distance, and v is the velocity of step advancement58, 59, 60. The subscript refers to the ith edge of growth hillocks, which advance across the surface in spiral patterns with a characteristic rotation time τ. Observations of decreased COM  thickness in Fig. 1g are qualitatively consistent with this theoretical equation. It is energetically more favourable for inhibitors to adsorb on kink sites rather than on step edges. Both modes of action can alter the shape of crystals through specific inhibitor–step or inhibitor–kink interactions. In our studies of COM crystallization, the mode of action for CA and HCA at low inhibitor concentration inferred from in situ AFM images does not appear to be kink blocking. To quantitatively analyse AFM data, we constructed Bliznakov plots, which represent the relationship between relative step velocity and inhibitor concentration. In Extended Data Fig. 5a we plot a hypothetical v/v trend with increasing inhibitor concentration as a function of calcium oxalate supersaturation where v and v are step velocities in the presence and absence of inhibitor, respectively. For the step-pinning mode of action, this plot should exhibit a monotonic decrease in v/v with increasing inhibitor concentration (see ref. 8 for example). Plots for HCA (Extended Data Fig. 5b) deviate from this trend, suggesting that HCA does not bind to the (010) surface. For inhibitors that operate in a kink-blocking mode of action, a plot of v /(v − v) with increasing inverse inhibitor concentration should produce a linear trend; however, plots for HCA exhibit no apparent trend, which leads us to believe that HCA preferentially binds to steps, as illustrated in Fig. 3c. Note that the plateau region for v (Fig. 2e) observed at low inhibitor concentration (C < 0.04 μg ml−1) has also been reported by others examining the effects of proteins and polyamino acids on COM (010) and (100) step advancement38. In these studies, it was suggested that the size of the step relative to the size of the inhibitor can lead to complex sorbate–crystal binding (including the possibility of cooperative effects among multiple HCA molecules at step sites). Inhibitor complexation of free calcium ions in solution reduces the rate of COM growth by lowering the supersaturation. The solubility of COM crystals C (that is, equilibrium concentration of solute) is as follows: where K is the solubility product (1.66 × 10−9 mol2 l−2 at 25 °C)35 and γ is the activity coefficient (i = Ca or Ox). For the equimolar growth solutions used in this study (C = C ), the activity coefficients for Ca and Ox are calculated using the expression: where z is ion valence and I is ionic strength. The addition of either HCA or CA to a calcium oxalate growth solution lowers supersaturation by (i) forming complexes with free calcium ions to reduce C , and (ii) increasing the ionic strength, which alters the activity coefficients, thereby increasing the solubility of COM crystals. Inhibitor concentrations used in AFM experiments (about 3 μM) are insufficient to reduce supersaturation by complexation (that is, Ca2+/HCA ≈ 103), and impose only minor changes in solubility due to activity effects (that is, C increases by about 0.05%). If the inhibitor concentration in bulk crystallization is increased to values that are commensurate with supersaturation, the effects of complexation and activity are important. For example, we performed bulk crystallization in the presence of about 0.3 mM HCA (or 100 μg ml−1) and observed few COM crystals, indicating almost complete suppression of COM crystallization. In the literature, alternative mechanisms have been proposed to describe the potential effects of inhibitors (or impurities) on crystal solubility. At low supersaturation, it is suggested that inhibitors can increase local solubility at crystal interfaces, potentially inducing dissolution when the mother liquor is close to saturation61. Under similar conditions, it is also possible to observe the effects of Ostwald ripening, where small crystals dissolve at the expense of larger particles that grow based on the Gibbs–Thompson effect62. Others have proposed that changes in surface free energy can be caused by the site occupancy in crystal lattices with embedded solid particles or impurities63, which induce stress on the crystal (analogous to the simulations by ref. 26 described in Fig. 3a). Additionally, the formation of defects on crystal surfaces (such as vacancies or dislocations) can induce stress on the crystal lattice, leading to reduced rates of growth under supersaturated conditions64.
Embryos edited Researchers at Guangzhou Medical University in China have reported editing the genes of non-viable human embryos to try to make them resistant to HIV infection. The team collected a total of 213 fertilized human eggs, donated by 87 patients, that were unsuitable for implantation as part of in vitro fertility therapy because they contained an extra set of chromosomes. The researchers then used the CRISPR–Cas9 genome-editing technique to introduce into some of the embryos a mutation that cripples an immune-cell gene called CCR5. Some people naturally carry this mutation, which alters the CCR5 protein in a way that prevents the HIV virus from entering the cells it tries to infect. Genetic analysis showed that 4 of 26 human embryos targeted were modified with the CCR5 mutation. But in some embryos, not all sets of chromosomes harboured the mutation; some contained the unmodified gene, whereas others had acquired different mutations. In April 2015, a different China-based team announced that it had modified a gene linked to a blood disease in non-viable human embryos, igniting a worldwide storm of ethics concerns. See go.nature.com/igymgu for more. SpaceX rocket touches down at sea SpaceX took a major step towards re-usable rockets when it flawlessly landed the first stage of its Falcon 9 rocket on an unmanned ship in the Atlantic Ocean, after an 8 April launch from Cape Canaveral, Florida. It was the first successful landing of the rocket at sea, following four attempts that resulted in crashes. The company, based in Hawthorne, California, returned an intact Falcon rocket to land in December last year. The latest flight delivered cargo to the International Space Station (ISS), including an expandable astronaut habitat designed by Bigelow Aerospace of North Las Vegas, Nevada. The previous SpaceX mission to the ISS failed when a Falcon 9 rocket broke apart after launch in June 2015. Kepler scare NASA mission managers were shocked to discover on 7 April that the exoplanet-hunting Kepler space telescope had entered emergency mode. Mission control was able to return it to normal operations three days later, but the cause of the malfunction remained a mystery as Nature went to press. This was the first software glitch in Kepler’s seven years in space, although it previously suffered hardware breakdowns. The spacecraft has lost at least the first several days of a planet-hunting campaign that it was scheduled to begin on 7 April and conduct until 1 July. See go.nature.com/mu7woc for more. China satellite lab China has launched its largest-ever suite of microgravity and life-science experiments into orbit. The country’s Shijian-10 probe left the Jiuquan Satellite Launch Center in Gansu province, northern China, on 7 April. It is carrying 19 experiments that include tests to assess the effects of radiation on genes as well as the influence of microgravity on materials, fluid physics and combustion. The early development of mouse embryos in microgravity will also be examined. After its 15-day mission, the bullet-shaped craft will re-enter Earth’s atmosphere to be recovered from a landing site in Inner Mongolia. Self-driving lorries Six squads of automated lorries successfully arrived in Rotterdam in the Netherlands on 6 April after having driven themselves from Sweden, Belgium and Germany, with one fleet travelling more than 2,000 kilometres from Stockholm. The trial was part of the Dutch-government-led European Truck Platooning Challenge and included lorries from six different manufacturers. ‘Truck platooning’ involves two or more lorries connected by WiFi and driving in a convoy, with the first vehicle determining the speed and route. The technology aims to save fuel by enabling lorries to travel closer together, which reduces air drag. Bank climate plan The World Bank announced a Climate Change Action Plan on 7 April to help countries to meet their commitments under the United Nations climate agreement signed in Paris in December 2015, and to prepare for unavoidable impacts of climate change. Under the plan, the bank will mobilize US$25 billion in private financing for clean energy by 2020. Among other actions, it will quadruple funding for clean transportation programmes and help to bring early-warning systems for natural disasters to 100 million people. Reef catastrophe Huge swathes of coral in Australia’s Great Barrier Reef are undergoing severe bleaching (pictured), according to aerial surveys. Many corals in the northern part of the reef are likely to die, because raised sea temperatures have caused them to expel the symbiotic algae that give them their colour. Researchers at the ARC Centre of Excellence for Coral Reef Studies in Townsville, Queensland, who are assessing the damage, say that more than 1,200 kilometres of the roughly 2,300-kilometre-long reef have bleached, and that the situation is substantially worse than in the two previous bleaching episodes in 1998 and 2002. See go.nature.com/ys7bau for more. Cambodia tiger loss Tigers are no longer breeding in Cambodia and the population there should be considered “functionally extinct”, the conservation group WWF announced on 6 April in Phnom Penh. The last wild tiger there was seen on a camera trap in 2007 in the Mondulkiri Protected Forest. But the WWF noted that national estimates and data compiled by the International Union for Conservation of Nature suggest that global tiger populations have rebounded to 3,890, from about 3,200 in 2010. Cambodia plans to bring eight young tigers from India into its dry forests in the Eastern Plains by 2019, as part of the global Tx2 initiative aiming to double wild tiger populations by the year 2022. Pharma merger off A marriage between two large pharmaceutical companies has been called off. Pfizer of New York City and Allergan of Dublin announced on 6 April that they had terminated a proposed merger process, which would have enabled the resulting company to take advantage of lower taxes in Ireland. The news came two days after the US Department of the Treasury unveiled stricter rules on companies that seek to move abroad to avoid US taxes. Pfizer pledged to announce by the end of the year whether it will spin off some parts of the company. NASA science chief Former astronaut John Grunsfeld, who has overseen NASA’s science portfolio since 2012, announced his retirement from the space agency on 5 April. The physicist and space-telescope expert flew five times on the space shuttle — including three visits to the Hubble Space Telescope — and was the lead spacewalker on the final flight to maintain and upgrade the telescope in 2009. As associate administrator for NASA’s Science Mission Directorate, he was responsible for more than 100 missions, such as the New Horizons spacecraft that visited Pluto last year. Grunsfeld’s deputy, Geoff Yoder, will take charge until a successor is chosen. Contracts with the International Seabed Authority (ISA), which regulates sea-bed mining in international waters, have picked up in recent years. Although commercial mining operations have not yet started, governments and corporations have signed contracts with the ISA to allow them to explore areas of the world’s oceans for materials including manganese nodules, copper, zinc, cobalt and platinum. Researchers have warned about the environmental impacts, saying that stricter regulation is needed. 16–20 April The American Association for Cancer Research holds its annual meeting in New Orleans, Louisiana. go.nature.com/q1t4fp 17–22 April The American Meteorological Society’s 32nd meeting on hurricanes and tropical meteorology convenes in San Juan, Puerto Rico. go.nature.com/pvszif
News Article | December 1, 2015
Indian Prime Minister Narendra Modi and French President François Hollande, along with world leaders, launched the International Solar Alliance on the inaugural day of the U.N. Climate Summit in Paris. The solar alliance brings together key countries and invites over 100 solar-rich countries to propel clean energy and protect the climate. The cooperation demonstrated by both developed and developing countries in launching the solar alliance gives a head start to the collective, flexible cooperation needed to hammer out an international agreement in Paris to sustainably and effectively fight climate pollution. “We must turn to solar to power our future,” urged Prime Minister Modi in launching the International Solar Alliance. President Hollande praised India’s leadership and called for France and others to mobilize finance and technology to achieve climate justice during the summit. Indian Power Minister Piyush Goyal explained, “We share collective ambition to take innovative, concerted efforts to reduce the cost of finance and technology for solar energy.” The International Solar Alliance invites countries located between the Tropics of Cancer and Capricorn to join, including many African and Asian nations, Australia, New Zealand, Brazil, France, China and the United States. Prime Minister Modi estimates $100 billion will be needed annually by 2020 to finance the clean power initiative. India’s National Institute of Solar Energy will lead the coordination of the solar alliance initiative for the first five years. The International Solar Alliance is part of India’s effort to advance a low-carbon economy, including domestic targets to install 100 gigawatts of solar energy by 2022. Prime Minister Modi also marked India’s progress, noting that India’s current installed solar energy capacity of 4 gigawatts will jump to 12 gigawatts by the end of 2016. The launch of the International Solar Alliance shows the flexibility and cooperation needed at the negotiations to achieve a strong agreement to reduce global warming pollution. In applauding India for its innovation and leadership in solar energy, UN Secretary General Ban Ki-moon urged leaders to take even great action this week and to come together to protect our planet and fight climate change. NRDC’s full statement is available here. Following is a statement by Rhea Suh, President of the Natural Resources Defense Council: “This unprecedented international solar collaboration sets an encouraging tone as country representatives gather today to reach a new global climate agreement. India’s leading role in forming an International Solar Alliance anchors its own climate commitment to ramp up renewable energy. It also has the potential to propel international solar markets forward, all while fighting climate change, improving global health and boosting economies.” Following is a statement by Anjali Jaiswal, India Initiative Director for the Natural Resources Defense Council: “Coupled with its comprehensive solar program aiming to reach 100 gigawatts by 2022, India has once again positioned itself as a global leader in clean energy. The International Solar Alliance aims to expand solar power primarily in countries that are resource-rich but energy poor, where clean energy solutions are most needed. Developing affordable solar technologies and attracting the considerable investment required to finance the envisioned solar transition are critical steps to support India and other countries to achieve their ambitious clean energy goals set as part of the Paris negotiations.” Following is a statement by JingJing Qian, China Program Director for the Natural Resources Defense Council: “As the world’s solar market leader, China has much to offer and can benefit greatly from its participation in the International Solar Alliance. China has pledged to cap its carbon emissions within 15 years, primarily through transitioning to solar and wind energy to power its development. With the U.S. and China joining India, along with over 100 other nations, to support this solar alliance on the first day of the UN climate negotiations, the majority of greenhouse gas emitters are demonstrating tremendous leadership to develop sustainably while curbing climate change.” Following is a statement by Dr. Arunabha Ghosh, CEO of the Council on Energy, Environment and Water: “The launch of the International Solar Alliance (ISA) is a historic step for global cooperation and a much needed boost for a low-carbon future. Under India’s leadership, the ISA could inspire and support several developed and developing countries to advance on a clean energy pathway by lowering financing costs, developing common standards, encouraging knowledge sharing and facilitating R&D collaborations and co-development of technologies to meet the Sustainable Development Goals (SDGs) announced earlier this year. India has emerged as the natural leader for this alliance, with its ambitious targets to install 175 GW of renewable energy by 2022, and non-fossil fuel electricity generating systems accounting for 40% of the cumulative installed capacity by 2030.”