Gene copy number (CN) variation is known to be important in nearly every species where it has been examined. Alterations in gene CN may provide a fast way of acquiring diversity, allowing rapid adaptation under strong selective pressures, and may also be a key component of standing genetic variation within species. Cannabis sativa plants produce a distinguishing set of secondary metabolites, the cannabinoids, many of which have medicinal utility. Two major cannabinoids—THCA (delta-9-tetrahydrocannabinolic acid) and CBDA (cannabidiolic acid)—are products of a three-step biochemical pathway. Using whole-genome shotgun sequence data for 69 Cannabis cultivars from diverse lineages within the species, we found that genes encoding the synthases in this pathway vary in CN. Transcriptome sequence data show that the cannabinoid paralogs are differentially expressed among lineages within the species. We also found that CN partially explains variation in cannabinoid content levels among Cannabis plants. Our results demonstrate that biosynthetic genes found at multiple points in the pathway could be useful for breeding purposes, and suggest that natural and artificial selection have shaped CN variation. Truncations in specific paralogs are associated with lack of production of particular cannabinoids, showing how phytochemical diversity can evolve through a complex combination of processes.
We explore the variation in plasma conditions through the middle magnetosphere of Jupiter with latitude and radial distance using Juno‐JADE measurements of plasma density (electrons, protons, sulfur, and oxygen ions) surveyed on Orbits 5–26 between March 2017 and April 2020. On most orbits, the densities exhibit regular behavior, mapping out a disk between 10 and 50 RJ (Jovian radii). In the disk, the heavy ions are confined close to the centrifugal equator which oscillates relative to the spacecraft due to the ∼10° tilt of Jupiter's magnetic dipole. Exploring each crossing of the plasma disk shows there are some occasions where the density profiles are smooth and well‐defined. At other times, small‐scale structures suggest temporal and/or spatial variabilities. There are some exceptional orbits where the outer regions (30–50 RJ) of the plasma disk show uniform depletion, perhaps due to enhanced ejection of plasmoids down the magnetotail, possibly triggered by solar wind compression events.
We present observations of Jupiter's magnetic field and plasma obtained with the NASA Juno spacecraft during February 2018, along with simultaneous Hubble Space Telescope (HST) observations of the planet's auroras. We show that a few‐day transient enhancement of the azimuthal and radial magnetic fields and plasma temperature was coincident with a significant brightening of Jupiter's dawn‐side main auroral emission. This presents the first evidence of control of Jupiter's main auroral emission intensity by magnetosphere‐ionosphere coupling currents. We support this association by self‐consistent calculation of the magnetosphere‐ionosphere coupling and radial force balance currents using an axisymmetric model, which broadly reproduces the Juno magnetic field and plasma observations and the HST auroral observations. We show that the transient enhancement can be explained by increased hot plasma pressure in the magnetosphere together with increased iogenic plasma mass outflow rate. Overall, this work provides important observational and modeling evidence revealing the behavior of Jupiter's giant magnetosphere.
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