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The Brassicaceae, including Arabidopsis thaliana and Brassica crops, is unmatched among plants in its wealth of genomic and functional molecular data and has long served as a model for understanding gene, genome, and trait evolution. However, genome information from a phylogenetic outgroup that is essential for inferring directionality of evolutionary change has been lacking. We therefore sequenced the genome of the spider flower (Tarenaya hassleriana) from the Brassicaceae sister family, the Cleomaceae. By comparative analysis of the two lineages, we show that genome evolution following ancient polyploidy and gene duplication events affect reproductively important traits. We found an ancient genome triplication in Tarenaya (Th-alpha) that is independent of the Brassicaceae-specific duplication (At-alpha) and nested Brassica (Br-a) triplication. To showcase the potential of sister lineage genome analysis, we investigated the state of floral developmental genes and show Brassica retains twice as many floral MADS (for MINICHROMOSOME MAINTENANCE1, AGAMOUS, DEFICIENS and SERUM RESPONSE FACTOR) genes as Tarenaya that likely contribute to morphological diversity in Brassica. We also performed synteny analysis of gene families that confer self-incompatibility in Brassicaceae and found that the critical SERINE RECEPTOR KINASE receptor gene is derived from a lineage-specific tandem duplication. The T. hassleriana genome will facilitate future research toward elucidating the evolutionary history of Brassicaceae genomes.
The near-polar orbit satellites of Swarm mission provide a good opportunity to investigate the conjugacy of equatorial plasma irregularities (EPIs) since their trajectories at low latitudes are basically aligned with fixed geographical longitude. However, the Swarm in situ electron density occasionally shows EPIs at only one hemisphere at this longitude. In this study, we provide detailed analysis of such EPI events from the in situ electron densities and onboard global positioning system (GPS) measurements of Swarm low pair satellites, and simultaneous GPS data from two geomagnetically conjugate ground stations at the Africa longitudes. The result indicates that when Swam in situ electron density sometime shows EPIs at only one hemisphere, the GPS scintillations are still observed from the Swarm onboard receiver and by the two conjugate ground stations. It implies that the EPIs should generally elongate along the geomagnetic flux tube. More than two-year statistic results show that the onset time of scintillation in the northern station is on average 16 and 18 min earlier than that in the southern station for September equinox and December solstice in 2015, while for March equinox in 2016 the onset time of scintillation of northern station is about 11 min later than that of southern station, which indicates the asymmetry features of EPIs along the flux tube. Further analysis of nearly three-year GPS data from two conjugate stations at the Asia longitudes, we find that during solar maximum years the local sunset time plays an important role for causing the difference of onset time of scintillation between two conjugate stations.
Historically, the giant panda was widely distributed from northern China to southwestern Asia [1]. As a result of range contraction and fragmentation, extant individuals are currently restricted to fragmented mountain ranges on the eastern margin of the Qinghai-Tibet plateau, where they are distributed among three major population clusters [2]. However, little is known about the genetic consequences of this dramatic range contraction. For example, were regions where giant pandas previously existed occupied by ancestors of present-day populations, or were these regions occupied by genetically distinct populations that are now extinct? If so, is there any contribution of these extinct populations to the genomes of giant pandas living today? To investigate these questions, we sequenced the nuclear genome of an similar to 5,000-year-old giant panda from Jiangdongshan, Teng-chong County in Yunnan Province, China. We find that this individual represents a genetically distinct population that diverged prior to the diversification of modern giant panda populations. We find evidence of differential admixture with this ancient population among modern individuals originating from different populations as well as within the same population. We also find evidence for directional gene flow, which transferred alleles from the ancient population into the modern giant panda lineages. A variable proportion of the genomes of extant individuals is therefore likely derived from the ancient population represented by our sequenced individual. Although extant giant panda populations retain reasonable genetic diversity, our results suggest that this represents only part of the genetic diversity this species harbored prior to its recent range contractions.
Background: Recent studies show that preterm birth is associated with hypertension in later life. The renin-angiotensin system (RAS) during pregnancy influences fetal growth and development. In the current study, we investigated the impact of fetal as well as maternal angiotensin (1-7) [Ang (1-7)] and angiotensin II (Ang II) plasma concentrations on the risk of preterm birth.
Methods: Three hundred and nine pregnant women were prospectively included into the study. The pregnant women were divided into two groups, for example, preterm birth of lower than 37 gestational weeks (n = 17) and full-term birth of 37 gestational weeks or more (n = 292). Maternal and neonatal plasma Ang (1-7) and Ang II concentrations were analyzed at birth from maternal venous blood and umbilical cord blood, respectively. Risk factors for premature birth were determined by multiple logistic regression analysis.
Results: Fetal and maternal plasma Ang (1-7) concentrations in the preterm group were lower than those of the term group fetal Ang (1-7) preterm birth: 486.15 +/- 337.34 ng/l and fetal Ang (1-7) term birth: 833.84 +/- 698.12 ng/l and maternal Ang (1-7) preterm birth: 399.86 +/- 218.93 ng/l; maternal Ang (1-7) term birth: 710.34 +/- 598.22 ng/l. Multiple logistic regression analysis considering confounding factors revealed that preeclampsia (P < 0.001), premature rupture of membranes (P = 0.001), lower concentration of maternal Ang (1-7) (P = 0.013) and fetal plasma Ang (1-7) (P = 0.032) were independently associated with preterm birth. We could furthermore demonstrate that the maternal Ang (1-7)/Ang II ratio is independently associated with gestational hypertension or preeclampsia, factors causing preterm birth.
Conclusions: Lower concentrations of maternal and fetal Ang (1-7) are independently associated with preterm birth - a risk factor of hypertension in later life.
Magnetic reconnection is a fundamental process of topology change and energy release, taking place in plasmas on the Sun, in space, in astrophysical objects and in the laboratory. However, observational evidence has been relatively rare and typically only partial. Here we present evidence of fast reconnection in a solar filament eruption using high-resolution H-alpha images from the New Vacuum Solar Telescope, supplemented by extreme ultraviolet observations. The reconnection is seen to occur between a set of ambient chromospheric fibrils and the filament itself. This allows for the relaxation of magnetic tension in the filament by an untwisting motion, demonstrating a flux rope structure. The topology change and untwisting are also found through nonlinear force-free field modelling of the active region in combination with magnetohydrodynamic simulation. These results demonstrate a new role for reconnection in solar eruptions: the release of magnetic twist.