Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

DEPOSITIONAL HYPOTHESES FOR THE EMPLACEMENT OF THE MARGIN UNIT, JEZERO CRATER, MARS

International audienceAfter 910 sols, the Mars 2020 Perse-verance rover has begun exploring the margin unit, the region with the strongest and clearest orbital signature of carbonate minerals (Figure1) [1, 2]. Stratigraphically, the margin unit is older than the Upper Delta/Fan Top units and lies unconformably below curved and inclined sandstone deposits, interpreted as fluvial deposits, and below the boulder-rich unit (Figure 2). On Mars, rovers and orbiters have only detected carbonates in trace amounts in only a few locations on the surface [3]; how-ever, their sources are primarily unclear. Some car-bonate material is also found in martian meteorites such as ALH 84001 and Nakhla [3]. The sources are aqueous alteration of igneous material, both in Comanche rock and ALH84001 [3]. Carbonates generally form due to aqueous processes in solutions that contain inorganic carbon. However, the meteorites do not preserve a rec-ord of specific surface processes in past habitable envi-ronments. Based on orbital detections, the carbonate material in Jezero is hypothesized to have precipitated from a lacustrine environment [1]

DEPOSITIONAL HYPOTHESES FOR THE EMPLACEMENT OF THE MARGIN UNIT, JEZERO CRATER, MARS

International audienceAfter 910 sols, the Mars 2020 Perse-verance rover has begun exploring the margin unit, the region with the strongest and clearest orbital signature of carbonate minerals (Figure1) [1, 2]. Stratigraphically, the margin unit is older than the Upper Delta/Fan Top units and lies unconformably below curved and inclined sandstone deposits, interpreted as fluvial deposits, and below the boulder-rich unit (Figure 2). On Mars, rovers and orbiters have only detected carbonates in trace amounts in only a few locations on the surface [3]; how-ever, their sources are primarily unclear. Some car-bonate material is also found in martian meteorites such as ALH 84001 and Nakhla [3]. The sources are aqueous alteration of igneous material, both in Comanche rock and ALH84001 [3]. Carbonates generally form due to aqueous processes in solutions that contain inorganic carbon. However, the meteorites do not preserve a rec-ord of specific surface processes in past habitable envi-ronments. Based on orbital detections, the carbonate material in Jezero is hypothesized to have precipitated from a lacustrine environment [1]

Complete avian malaria parasite genomes reveal features associated with lineage specific evolution in birds and mammals

Avian malaria parasites are prevalent around the world, and infect a wide diversity of bird species. Here we report the sequencing and analysis of high quality draft genome sequences for two avian malaria species, Plasmodium relictum and Plasmodium gallinaceum. We identify 50 genes that are specific to avian malaria, located in an otherwise conserved core of the genome that shares gene synteny with all other sequenced malaria genomes. Phylogenetic analysis suggests that the avian malaria species form an outgroup to the mammalian Plasmodium species and using amino acid divergence between species, we estimate the avian and mammalian-infective lineages diverged in the order of 10 million years ago. Consistent with their phylogenetic position, we identify orthologs of genes that had previously appeared to be restricted to the clades of parasites containing P. falciparum and P. vivax the species with the greatest impact on human health. From these orthologs, we explore differential diversifying selection across the genus and show that the avian lineage is remarkable in the extent to which invasion related genes are evolving. The subtelomeres of the P. relictum and P. gallinaceum genomes contain several novel gene families, including an expanded surf multigene family. We also identify an expansion of reticulocyte binding protein homologs in P. relictum and within these proteins, we detect distinct regions that are specific to non-human primate, humans, rodent and avian hosts. For the first time in the Plasmodium lineage we find evidence of transposable elements, including several hundred fragments of LTR-retrotransposons in both species and an apparently complete LTR-retrotransposon in the genome of P. gallinaceum

Depositional and Diagenetic Sulfates of Hogwallow Flats and Yori Pass, Jezero Crater: Evaluating Preservation Potential of Environmental Indicators and Possible Biosignatures From Past Martian Surface Waters and Groundwaters

The Mars 2020 Perseverance rover has examined and sampled sulfate-rich clastic rocks from the Hogwallow Flats member at Hawksbill Gap and the Yori Pass member at Cape Nukshak. Both strata are located on the Jezero crater western fan front, are lithologically and stratigraphically similar, and have been assigned to the Shenandoah formation. In situ analyses demonstrate that these are fine-grained sandstones composed of phyllosilicates, hematite, Ca-sulfates, Fe-Mg-sulfates, ferric sulfates, and possibly chloride salts. Sulfate minerals are found both as depositional grains and diagenetic features, including intergranular cement and vein- and vug-cements. Here, we describe the possibility of various sulfate phases to preserve potential biosignatures and the record of paleoenvironmental conditions in fluid and solid inclusions, based on findings from analog sulfate-rich rocks on Earth. The samples collected from these outcrops, Hazeltop and Bearwallow from Hogwallow Flats, and Kukaklek from Yori Pass, should be examined for such potential biosignatures and environmental indicators upon return to Earth

Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars

International audienceThe Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon

Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars

International audienceThe Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon

Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars

International audienceThe Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon