Genome-scale analysis of interactions between genetic perturbations and natural variation.

Interactions between genetic perturbations and segregating loci can cause perturbations to show different phenotypic effects across genetically distinct individuals. To study these interactions on a genome scale in many individuals, we used combinatorial DNA barcode sequencing to measure the fitness effects of 7,700 CRISPRi perturbations targeting 1,712 distinct genes in 169 yeast cross progeny (or segregants). We identified 460 genes whose perturbation has different effects across segregants.

The interplay of additivity, dominance, and epistasis on fitness in a diploid yeast cross.

In diploid species, genetic loci can show additive, dominance, and epistatic effects. To characterize the contributions of these different types of genetic effects to heritable traits, we use a double barcoding system to generate and phenotype a panel of ~200,000 diploid yeast strains that can be partitioned into hundreds of interrelated families. This experiment enables the detection of thousands of epistatic loci, many whose effects vary across families.

Genetic basis of a spontaneous mutation's expressivity.

Genetic background often influences the phenotypic consequences of mutations, resulting in variable expressivity. How standing genetic variants collectively cause this phenomenon is not fully understood. Here, we comprehensively identify loci in a budding yeast cross that impact the growth of individuals carrying a spontaneous missense mutation in the nuclear-encoded mitochondrial ribosomal gene MRP20.

Molecular basis for interactions between an acyl carrier protein and a ketosynthase.

Fatty acid synthases are dynamic ensembles of enzymes that can biosynthesize long hydrocarbon chains efficiently. Here we visualize the interaction between the Escherichia coli acyl carrier protein (AcpP) and β-ketoacyl-ACP-synthase I (FabB) using X-ray crystallography, NMR, and molecular dynamics simulations. We leveraged this structural information to alter lipid profiles in vivo and provide a molecular basis for how protein-protein interactions can regulate the fatty acid profile in E.

Intermittent motion in desert locusts: behavioural complexity in simple environments.

Animals can exhibit complex movement patterns that may be the result of interactions with their environment or may be directly the mechanism by which their behaviour is governed. In order to understand the drivers of these patterns we examine the movement behaviour of individual desert locusts in a homogenous experimental arena with minimal external cues. Locust motion is intermittent and we reveal that as pauses become longer, the probability that a locust changes direction from its previous direction of travel increases.

Visual attention and the acquisition of information in human crowds.

Pedestrian crowds can form the substrate of important socially contagious behaviors, including propagation of visual attention, violence, opinions, and emotional state. However, relating individual to collective behavior is often difficult, and quantitative studies have largely used laboratory experimentation. We present two studies in which we tracked the motion and head direction of 3,325 pedestrians in natural crowds to quantify the extent, influence, and context dependence of socially transmitted visual attention.

Nutritional state and collective motion: from individuals to mass migration.

In order to move effectively in unpredictable or heterogeneous environments animals must make appropriate decisions in response to internal and external cues. Identifying the link between these components remains a challenge for movement ecology and is important in understanding the mechanisms driving both individual and collective motion. One accessible way of examining how internal state influences an individual's motion is to consider the nutritional state of an animal.

Collective motion and cannibalism in locust migratory bands.

Plagues of mass migrating insects such as locusts are estimated to affect the livelihood of one in ten people on the planet [1]. Identification of generalities in the mechanisms underlying these mass movements will enhance our understanding of animal migration and collective behavior while potentially contributing to pest-management efforts. We provide evidence that coordinated mass migration in juvenile desert locusts (Schistocerca gregaria) is influenced strongly by cannibalistic interactions.