Detecting the oldest geodynamo and attendant shielding from the solar wind: Implications for habitability

The onset and nature of the earliest geomagnetic field is important for understanding the evolution of the core, atmosphere and life on Earth. A record of the early geodynamo is preserved in ancient silicate crystals containing minute magnetic inclusions. These data indicate the presence of a geodynamo during the Paleoarchean, between 3.4 and 3.45 billion years ago. While the magnetic field sheltered Earth's atmosphere from erosion at this time, standoff of the solar wind was greatly reduced, and similar to that during modern extreme solar storms. These conditions suggest that intense radiation from the young Sun may have modified the atmosphere of the young Earth by promoting loss of volatiles, including water. Such effects would have been more pronounced if the field were absent or very weak prior to 3.45 billion years ago, as suggested by some models of lower mantle evolution. The frontier is thus trying to obtain geomagnetic field records that are >>3.45 billion-years-old, as well as constraining solar wind pressure for these times. In this review we suggest pathways for constraining these parameters and the attendant history of Earth's deep interior, hydrosphere and atmosphere. In particular, we discuss new estimates for solar wind pressure for the first 700 million years of Earth history, the competing effects of magnetic shielding versus solar ion collection, and bounds on the detection level of a geodynamo imposed by the presence of external fields. We also discuss the prospects for constraining Hadean-Paleoarchean magnetic field strength using paleointensity analyses of zircons.Comment: 78 pages, 8 figures, Supplementary Content: Reconstructing the Past Sun + table of solar parameters from ZAMS to present through geological tim

Yeast as a Versatile Tool in Biotechnology

Yeasts represent a very diverse group of microorganisms, and even strains that are classified as the same species often show a high level of genetic divergence. Yeasts biodiversity is closely related to their applicability. Biotechnological importance of yeast is almost immeasurable. For centuries, people have exploited its enzymatic potential to produce fermented food as bread or alcoholic beverages. Admittedly, yeasts application was initially instinctual, but with science and technology development, these microorganisms got the object of thorough scientific investigations. It must be recognized that yeast represents an excellent scientific model because of its eukaryotic origin and knowledge of genetics of yeast cells as well as metabolism examined in detail. In 1996, the genome of baker yeast Saccharomyces cerevisiae has been elucidated, what opened the opportunity for the global study of the expression and functioning of the eukaryotic genome. Also, currently, an international team is working on the synthesis of the 16 yeast chromosomes by synthetic biology tools, and the results are expected till the end of the year. Nowadays, yeast is regarded as a versatile tool for biotechnological purposes

The \u3ci\u3eChlorella variabilis\u3c/i\u3e NC64A Genome Reveals Adaptation to Photosymbiosis, Coevolution with Viruses, and Cryptic Sex

Chlorella variabilis NC64A, a unicellular photosynthetic green alga (Trebouxiophyceae), is an intracellular photobiont of Paramecium bursaria and a model system for studying virus/algal interactions. We sequenced its 46-Mb nuclear genome, revealing an expansion of protein families that could have participated in adaptation to symbiosis. NC64A exhibits variations in GC content across its genome that correlate with global expression level, average intron size, and codon usage bias. Although Chlorella species have been assumed to be asexual and nonmotile, the NC64A genome encodes all the known meiosis-specific proteins and a subset of proteins found in flagella. We hypothesize that Chlorella might have retained a flagella-derived structure that could be involved in sexual reproduction. Furthermore, a survey of phytohormone pathways in chlorophyte algae identified algal orthologs of Arabidopsis thaliana genes involved in hormone biosynthesis and signaling, suggesting that these functions were established prior to the evolution of land plants. We show that the ability of Chlorella to produce chitinous cell walls likely resulted from the capture of metabolic genes by horizontal gene transfer from algal viruses, prokaryotes, or fungi. Analysis of the NC64A genome substantially advances our understanding of the green lineage evolution, including the genomic interplay with viruses and symbiosis between eukaryotes

<i>APETALA2</i> functions as a temporal factor together with <i>BLADE-ON-PETIOLE2</i> and <i>MADS29</i> to control flower and grain development in barley

Cereal grain develops from fertilised florets. Alterations in floret and grain development greatly influence grain yield and quality. Despite this, little is known about the underlying genetic control of these processes, especially in key temperate cereals such as barley and wheat. Using a combination of near-isogenic mutant comparisons, gene editing and genetic analyses, we reveal that HvAPETALA2 (HvAP2) controls floret organ identity, floret boundaries, and maternal tissue differentiation and elimination during grain development. These new roles of HvAP2 correlate with changes in grain size and HvAP2-dependent expression of specific HvMADS-box genes, including the B-sister gene, HvMADS29 Consistent with this, gene editing demonstrates that HvMADS29 shares roles with HvAP2 in maternal tissue differentiation. We also discovered that a gain-of-function HvAP2 allele masks changes in floret organ identity and grain size due to loss of barley LAXATUM.A/ BLADE-ON-PETIOLE2 (HvBOP2) gene function. Taken together, we reveal novel, pleiotropic roles and regulatory interactions for an APETALA2-like gene controlling floret and grain development in a temperate cereal.Jennifer R. Shoesmith, Charles Ugochukwu Solomon, Xiujuan Yang, Laura G. Wilkinson, Scott Sheldrick, Ewan van Eijden ... et al

Many-core and heterogeneous architectures: programming models and compilation toolchains

1noL'abstract è presente nell'allegato / the abstract is in the attachmentopen677. INGEGNERIA INFORMATInopartially_openembargoed_20211002Barchi, Francesc

Role of Light, Humidity, and Nutrition in Sporulation of Phytophthora Species

Oomycetes, a class in the kingdom Stramenopila, are filamentous eukaryotic microorganisms that are known informally as water molds, but have adapted to many environmental niches. Phytophthora, an oomycete genus of approximately 100 plant-pathogenic species, has specifically adapted to several environmental niches. Environmental conditions play an influential role in the development of Phytophthora, particularly in sporangium formation. Sporangia, the main driver of Phytophthora epidemics, are especially susceptible to damage by environmental conditions, such as light-induced DNA lesions or desiccation by drying. Variable by species, light can stimulate (e.g. P. infestans) or repress (e.g. P. capsici) the production of sporangia. Light may have two developmental roles: an early pre-sporangiophore induction signal, and a later post-sporangiophore repression signal. In this work, I found that although many types of photoreceptors are described in eukaryotes, Phytophthora genomes encode only cryptochrome photoreceptors. The foliar-adapted species P. infestans encodes three cryptochromes, while the soilborne species P. capsici encodes two cryptochromes. Silencing of the P. infestans gene encoding cryptochrome PITG_01718, which lacks an ortholog in P. capsici, inhibits sporulation. While cryptochromes have traditionally been described in other organisms as blue light receptors, each red and blue light represses P. infestans sporulation. In contrast, P. capsici sporulation responds to blue light but not red light. This work also describes the use of RNA-seq to study the genetic control of sporulation by light and humidity. Constant light was found to repress the expression of genes induced in the post-sporangiophore stage by P. infestans, while constant darkness repressed the expression of genes in the pre-sporangiophore stage in P. capsici. Humidity also had a strong effect on repressing gene expression in the pre-sporangiophore stage of sporulation in P. infestans. This work also describes that specific types of nitrogen starvation induce sporulation. In addition to advancing our knowledge of sporulation control in oomycetes, this work also provides a better understanding of the homology-based gene silencing method. While this technique is an effective method for functional genomics in Phytophthora, work in this dissertation shows that the technique must be used with prudence due to the frequency of off-target effects