Gene drives may be capable of addressing ecological problems by altering entire populations of wild organisms, but their use has remained largely theoretical due to technical constraints. Here we consider the potential for RNA-guided gene drives based on the CRISPR nuclease Cas9 to serve as a general method for spreading altered traits through wild populations over many generations. We detail likely capabilities, discuss limitations, and provide novel precautionary strategies to control the spread of gene drives and reverse genomic changes. The ability to edit populations of sexual species would offer substantial benefits to humanity and the environment. For example, RNA-guided gene drives could potentially prevent the spread of disease, support agriculture by reversing pesticide and herbicide resistance in insects and weeds, and control damaging invasive species. However, the possibility of unwanted ecological effects and near-certainty of spread across political borders demand careful assessment of each potential application. We call for thoughtful, inclusive, and well-informed public discussions to explore the responsible use of this currently theoretical technology.DOI: http://dx.doi.org/10.7554/eLife.03401.001

Gene drives may be capable of addressing ecological problems by altering entire populations of wild organisms, but their use has remained largely theoretical due to technical constraints. Here we consider the potential for RNA-guided gene drives based on the CRISPR nuclease Cas9 to serve as a general method for spreading altered traits through wild populations over many generations. We detail likely capabilities, discuss limitations, and provide novel precautionary strategies to control the spread of gene drives and reverse genomic changes. The ability to edit populations of sexual species would offer substantial benefits to humanity and the environment. For example, RNA-guided gene drives could potentially prevent the spread of disease, support agriculture by reversing pesticide and herbicide resistance in insects and weeds, and control damaging invasive species. However, the possibility of unwanted ecological effects and near-certainty of spread across political borders demand careful assessment of each potential application. We call for thoughtful, inclusive, and well-informed public discussions to explore the responsible use of this currently theoretical technology.

The Yin and Yang of Plant Caspases The function of plant metacaspases, identified by limited sequence homology to the animal caspases that control cell death, has remained elusive. Coll et al. (p. 1393 ) have now elucidated the actions of two metacaspases in the small plant Arabidopsis . One metacaspase, AtMC1, promoted cell death, and the other, AtMC2, acted antagonistically to stall cell death. The results help to elucidate the mechanisms by which plants control cell survival during development and defend against pathogen attack.

Regulatory gaps must be filled before gene drives could be used in the wild

Graphical AbstractHighlights d Human malaria parasites interact non-competitively with their mosquito vectors d Mosquito hormone signaling co-regulates egg and parasite development d Parasites use host lipids for their growth via a mosquito lipid transporter d Parasites respond to mosquito metabolism with consequences for vector controlThe development of the malaria-causing parasite Plasmodium falciparum depends on its ability to exploit the sexual cycle of its mosquito host in a noncompetitive manner. SUMMARYTransmission of malaria parasites occurs when a female Anopheles mosquito feeds on an infected host to acquire nutrients for egg development. How parasites are affected by oogenetic processes, principally orchestrated by the steroid hormone 20hydroxyecdysone (20E), remains largely unknown.Here we show that Plasmodium falciparum development is intimately but not competitively linked to processes shaping Anopheles gambiae reproduction. We unveil a 20E-mediated positive correlation between egg and oocyst numbers; impairing oogenesis by multiple 20E manipulations decreases parasite intensities. These manipulations, however, accelerate Plasmodium growth rates, allowing sporozoites to become infectious sooner. Parasites exploit mosquito lipids for faster growth, but they do so without further affecting egg development. These results suggest that P. falciparum has adopted a non-competitive evolutionary strategy of resource exploitation to optimize transmission while minimizing fitness costs to its mosquito vector. Our findings have profound implications for currently proposed control strategies aimed at suppressing mosquito populations.