Early Stages Of Evolution Research Articles

Early-stage evolution of nanoscale oxides on Ni(111) and Ni-Cr(111) surfaces

The early stages of oxidation on Ni(111) and Ni-18 wt%Cr(111) surfaces were studied with scanning tunneling microscopy/spectroscopy. After exposure to oxygen at 500 °C, chemisorbed p(2 ×2)O adlayers appear on Ni(111) without oxide formation. On the Ni-Cr(111) surface 2D NiO(100) layers rapidly accumulate on the terraces. These coexist with Cr-rich clusters, which coalesce as oxidation progresses. Larger oxide nodules with 3D-island morphology are identified as chromia and are found embedded in the NiO(100). Spectroscopy reveals electronic heterogeneity, highlighting the chemical variation between each oxide species. A schematic is constructed that highlights the associated Ni- and Cr- reaction pathways on Ni-Cr(111) alloy surfaces.

Genome-Wide Prediction and Analysis of Oryza Species NRP Genes in Rice Blast Resistance.

Members of the N-rich proteins (NRPs) gene family play important roles in the plant endoplasmic reticulum stress in response, which can be triggered by plant pathogens’ infection. Previous studies of the NRP gene family have been limited to only a few plants, such as soybean and Arabidopsis thaliana. Thus, their evolutionary characteristics in the Oryza species and biological functions in rice defense against the pathogenic fungus Magnaporthe oryzae have remained unexplored. In the present study, we demonstrated that the NRP genes family may have originated in the early stages of plant evolution, and that they have been strongly conserved during the evolution of the Oryza species. Domain organization of NRPs was found to be highly conserved within but not between subgroups. OsNRP1, an NRP gene in the Oryza sativa japonica group, was specifically up-regulated during the early stages of rice-M. oryzae interactions-inhibited M. oryzae infection. Predicted protein-protein interaction networks and transcription-factor binding sites revealed a candidate interactor, bZIP50, which may be involved in OsNRP1-mediated rice resistance against M. oryzae infection. Taken together, our results established a basis for future studies of the NRP gene family and provided molecular insights into rice immune responses to M. oryzae.

A prebiotic basis for ATP as the universal energy currency.

ATP is universally conserved as the principal energy currency in cells, driving metabolism through phosphorylation and condensation reactions. Such deep conservation suggests that ATP arose at an early stage of biochemical evolution. Yet purine synthesis requires 6 phosphorylation steps linked to ATP hydrolysis. This autocatalytic requirement for ATP to synthesize ATP implies the need for an earlier prebiotic ATP equivalent, which could drive protometabolism before purine synthesis. Why this early phosphorylating agent was replaced, and specifically with ATP rather than other nucleoside triphosphates, remains a mystery. Here, we show that the deep conservation of ATP might reflect its prebiotic chemistry in relation to another universally conserved intermediate, acetyl phosphate (AcP), which bridges between thioester and phosphate metabolism by linking acetyl CoA to the substrate-level phosphorylation of ADP. We confirm earlier results showing that AcP can phosphorylate ADP to ATP at nearly 20% yield in water in the presence of Fe3+ ions. We then show that Fe3+ and AcP are surprisingly favoured. A wide range of prebiotically relevant ions and minerals failed to catalyse ADP phosphorylation. From a panel of prebiotic phosphorylating agents, only AcP, and to a lesser extent carbamoyl phosphate, showed any significant phosphorylating potential. Critically, AcP did not phosphorylate any other nucleoside diphosphate. We use these data, reaction kinetics, and molecular dynamic simulations to infer a possible mechanism. Our findings might suggest that the reason ATP is universally conserved across life is that its formation is chemically favoured in aqueous solution under mild prebiotic conditions.

Petrology and organic geochemistry of the Baishaping and Damaidi Devonian cutinitic liptobioliths, west of the Kangdian Uplift, China

Devonian cutinitic liptobiolith is a special type of coal formed during the early evolutionary stage of land plants. The Baishaping and Damaidi Devonian coals are notable for their distinct papery, sheet-like texture, and unusually high cutinite content (>50%), belonging to typical cutinitic liptobiolith. They are bituminous coals and have a suppressed vitrinite reflectance. Compared with typical type III kerogen, these liptobioliths are characterized by extremely high yields of volatile matter and high hydrogen contents owing to their enhanced cutinite contents. As indicated by pyrolysis and elemental analysis results, the Devonian cutinitic liptobioliths are dominated by type I-II kerogens and have an excellent potential to generate liquid hydrocarbons. The Baishaping cutinitic liptobioliths are mainly composed of ribbon-like thick-walled cutinites, with small amounts of thin-walled type. Vitrinite is only present in trace amounts and is dominated by telinite. Meanwhile, the Damaidi Devonian coals are primarily composed of ribbon-like thin-walled cutinites, followed by collotelinites which are usually sandwiched by cutinites. The different petrological characteristics of the Baishaping and Damaidi liptobioliths might indicate a structural variation in the coal-forming plant cuticles and two distinct coal-forming conditions. The molecular biomarkers in the Devonian coals are mainly composed of C 18 –C 20 tetracyclic diterpenoids, which are assumed to be the dominant soluble constituent of the Devonian land-plant cuticles and might have played an important role in early land plant radiation. Other molecules include aromatic tetracyclic diterpenoids, 3–5 ring polycyclic aromatic hydrocarbons and their methylated counterparts, and C 16 - and C 18 -monocarboxylic acids. n -Alkanes are present only in small amounts. The molecular composition of the cutinite-rich coals is unexpected, because cuticular waxes are one of the most important sources of n -alkanes. In general, the petrology and geochemistry of the Devonian cutinitic liptobiolith indicate a distinct structure and composition for the early land-plant cuticles, which is significantly different from that of the plant cuticles since Carboniferous. Devonian cutinitic liptobioliths are of great interest because of their unique petrography, geochemistry, coal-forming plants, and oil-prone potential. Studies on this unique coal type provide a better understanding of coal-forming plants, paleoenvironment, paleoclimate, and early land-plant evolution in the Devonian.

Costs and benefits of isolation from siblings during family life in adult earwigs

The benefits of parental care are often seen as a cornerstone of family life evolution. However, recent studies show that sibling interactions can also confer substantial benefits to juveniles. Here, we tested a new hypothesis suggesting that the need for juveniles to access sibling interactions may encourage juveniles to remain in a family group, thereby consolidating the early stages of family life evolution when parental care is facultative. We set up juveniles of the European earwig, Forficula auricularia (a family-living insect in which maternal care is facultative and juveniles can forage for themselves and cooperate with siblings) either alone, with siblings, or with siblings and their mother, and then quantified effects on the development, morphology and four fitness-related behaviours of the resulting adults. We found that isolated juveniles reached adulthood more quickly and that these adults were overall larger but showed impaired aggregation behaviour when compared with juveniles raised together with siblings or with siblings and their mother. By contrast, sibling deprivation did not affect offspring survival, male forceps length (an ornament involved in reproductive success) and three other behaviours in adults (boldness, general activity and exploration). All these results were independent of adult sex, although females overall reached adulthood earlier and were larger than males. Altogether, our findings suggest that the potential benefits of sibling interactions measured in this study play a minor role in the maintenance of earwig family life. They also emphasize the need to study the evolutionary drivers of family life in species where all members can switch from family to solitary life, a scenario that probably prevailed in the early evolution of sociality. • Do the benefits of sibling interactions support the maintenance of family life? • We addressed this question by testing the effects of sibling deprivation in earwigs. • We found that it produces adults with impaired aggregation and faster development. • But it has no effect on survival and three other fitness-related behaviours. • This questions the role of sibling interactions in the emergence of family life.

ХАРАКТЕРИСТИКА СЕМЕЙСТВА КАТИОННЫХ TRPА1-КАНАЛОВ TRICHOPLAX SP. H2 (PLACOZOA)

Mechanoreceptors can transform external mechanical forces into electrochemical signals that induce cell membrane depolarization and initiate waves propagating along the cell surface. The TRPN1/NompC mechanotransduction channel is known to contain ankyrin repeats that act as a gating helix in Drosophila melanogaster [Jin et al., 2017]. In this work, we present for the first time a family of cationic TRPA1-channels in Trichoplax sp. H2 (Placozoa), which consists of 42 homologs ranging from 468 to 3240 aa in length. Three isolated clusters with different polypeptide chain lengths and various contents of ankyrin repeats were identified within the family. The spatial structure of TRPA1-channel RDD36842.1 was reconstructed, and aspirin, a possible TRP-channel blocker, was docked. The structure of the family members is analyzed, the mechanical model of channel operation is considered, and the probable function and physiology of these protein molecules and their role in the behavior of trichoplax are discussed. Variations in the number of ankyrin repeats at the N-terminus of TRP-proteins studied, and the differences detected at the C-terminus can indicate the polyfunctionality of these proteins in Placozoa. Perhaps TRP channels arose in early evolutionary stages before the appearance of multicellularity, but diversified in multicellular animals as the structural organization of those became more complex.

Current challenges and future prospect of biomass cooking and heating stoves in Asian Countries

The utilization of biomass for cooking and heating is old, occurring from the early stages of human evolution because of its wide and easy availability. In Asia, a majority of the population is dependent on solid biomass for cooking and heating applications. Biomass cookstove produces emissions like carbon monoxide (CO), and particulate matter with aerodynamic diameter ≤2.5 μm (PM2.5) which are dependent on the classifications and characteristics of fuel used in stoves. These emissions trigger many health risks because of the utilization of traditional cookstoves (TCS) which have less thermal efficiency. The literature contains a considerable amount of information on biomass cookstoves; however, it is dispersed particularly in Asian countries. In this principle, this paper gives an overview of available literature on biomass cookstoves for cooking and heating in Asian countries which are involving Bangladesh, China, India, Mongolia, Nepal, Pakistan, Sri Lanka, and Laos. This paper covers a detailed discussion on various aspects of biomass cookstoves: history, classification, fuel characteristics, health risks, design criteria, the scenario in selected Asian countries, thermal efficiency and emission comparison, and barriers to dissemination of improved biomass cookstoves (ICS). Learning from the review and comparison made conclude that the ICS has better thermal efficiency, and lesser emissions, as well as health risks but, have some potential barriers to dissemination.

Whole genome-wide analysis of DEP family members in sheep (Ovis aries) reveals their potential roles in regulating lactation

BackgroundSheep milk is an attractive nutritional and functional food source. Some Dishevelled, Egl-10 and pleckstrin (DEP) domain-containing proteins can regulate lactation performance in mammals. However, systematic study of the role of sheep DEP family members in regulating lactation is currently lacking. This study aimed to reveal the roles of sheep DEP family members in lactation by exploring their genetic characteristics and functional features at the whole genome-wide level.ResultsTwenty DEP family members were identified in the sheep genome, and they can be divided into four major groups. Ka/Ks calculations suggest that the purifying selection is the main pressure acting on DEP genes. In the late pregnancy and lactation periods, the expression levels of eight DEP genes exhibited significant differences in the mammary gland. In addition, nutritional conditions have a great influence on the expression of DEP family members, and the DEP gene family underwent more expansion than the average gene family in the early stages of biological evolution. The Mirrortree assays indicated that the DEP family members coevolved in biological evolution.ConclusionsOur research provides a better understanding of the characters of the DEP domain-containing protein family and their potential roles in regulating lactation in sheep. Moreover, these results of our study may contribute to the genetic improvement of milk performance in dairy sheep breed.Graphical

Relaxed risk of predation drives parallel evolution of stickleback behavior.

The occurrence of similar phenotypes in multiple independent populations derived from common ancestral conditions (viz. parallel evolution) is a testimony of evolution by natural selection. Parallel evolution implies that populations share a common phenotypic response to a common selection pressure associated with habitat similarity. Examples of parallel evolution at genetic and phenotypic levels are fairly common, but the driving selective agents often remain elusive. Similarly, the role of phenotypic plasticity in facilitating early stages of parallel evolution is unclear. We investigated whether the relaxation of predation pressure associated with the colonization of freshwater ponds by nine-spined sticklebacks (Pungitius pungitius) likely explains the divergence in complex behaviors between marine and pond populations, and whether this divergence is parallel. Using laboratory-raised individuals exposed to different levels of perceived predation risk, we calculated vectors of phenotypic divergence for four behavioral traits between habitats and predation risk treatments. We found a significant correlation between the directions of evolutionary divergence and phenotypic plasticity, suggesting that divergence in behavior between habitats is aligned with the response to relaxation of predation pressure. Finally, we show alignment across multiple pairs of populations, and that relaxation of predation pressure has likely driven parallel evolution of behavior in this species.

New Data on Nephron Microanatomy and Ultrastructure of Senegal Bichir (Polypterus senegalus).

Simple SummaryTransitional forms of animals between Pisces and Amphibia are interesting to study, as they are the first to begin the development of a new environment - terrestrial. Such a transitional form are amphibious fish. The study of the structure of the nephron, the main structure that performs an osmoregulatory function, makes it possible to build evolutionary series that describe the processes of transition from the aquatic environment to the terrestrial one. Bichirs is a monophyletic group that arose in the Devonian and formed a species complex only in the Neogene. They share features with lungfish and amphibians, which formed convergently in the early stages of evolution. Therefore Bichirs are of great interest as a transitional form of animals. This study presents new data on the nephron age of Polypterus senegalus. Two groups of features are described. The first group consists of ancestral traits that have been preserved in the modern population of P. senegalus and are associated with habitat conditions in the aquatic environment. The second group is a complex of characters associated with the adaptation of P. senegalus to air breathing and periodic ground migrations.This study presents new data on the microanatomy and ultrastructure of Polypterus senegalus nephrons. It was shown that the diameter and ultrastructure of renal corpuscles, a well-developed neck segment, and ultrastructure of two types of epithelial cells of the proximal tubule are ancestral signs of the modern population of P. senegalus associated with habitat conditions in the aquatic environment. The outer diameter of the tubules, the height of the epitheliocytes, the presence of two types of epithelial cells of the intermediate and distal tubules of the corresponding ultrastructure, and a large area of nephrogenic tissue are progressive features of the modern population of P. senegalus, associated with adaptation to air respiration and periodic terrestrial migrations, which were formed at the early stages of evolution of P. senegalus convergently with lungfish and amphibians.

Characterising the orbit and circumstellar environment of the high-mass binary MWC 166 A

Context. Stellar evolution models are highly dependent on accurate mass estimates, especially for highly massive stars in the early stages of stellar evolution. The most direct method for obtaining model-independent stellar masses is derivation from the orbit of close binaries. Aims. Our aim was to derive the first astrometric plus radial velocity orbit solution for the single-lined spectroscopic binary star MWC 166 A, based on near-infrared interferometry over multiple epochs and ∼100 archival radial velocity measurements, and to derive fundamental stellar parameters from this orbit. A supplementary aim was to model the circumstellar activity in the system from K band spectral lines. Methods. The data used include interferometric observations from the VLTI instruments GRAVITY and PIONIER, as well as the MIRC-X instrument at the CHARA Array. We geometrically modelled the dust continuum to derive relative astrometry at 13 epochs, determine the orbital elements, and constrain individual stellar parameters at five different age estimates. We used the continuum models as a base to examine differential phases, visibilities, and closure phases over the Br γ and He I emission lines in order to characterise the nature of the circumstellar emission. Results. Our orbit solution suggests a period of P = 367.7 ± 0.1 d, approximately twice as long as found with previous radial velocity orbit fits. We derive a semi-major axis of 2.61 ± 0.04 au at d = 990 ± 50 pc, an eccentricity of 0.498 ± 0.001, and an orbital inclination of 53.6 ± 0.3°. This allowed the component masses to be constrained to M1 = 12.2 ± 2.2 M⊙ and M2 = 4.9 ± 0.5 M⊙. The line-emitting gas was found to be localised around the primary and is spatially resolved on scales of ∼11 stellar radii, where the spatial displacement between the line wings is consistent with a rotating disc. Conclusions. The large spatial extent and stable rotation axis orientation measured for the Br γ and He I line emission are inconsistent with an origin in magnetospheric accretion or boundary-layer accretion, but indicate an ionised inner gas disc around this Herbig Be star. We observe line variability that could be explained either with generic line variability in a Herbig star disc or V/R variations in a decretion disc scenario. We have also constrained the age of the system, with relative flux ratios suggesting an age of ∼(7 ± 2)×105 yr, consistent with the system being composed of a main-sequence primary and a secondary still contracting towards the main-sequence stage.

Shell histology of the Triassic turtle, Proterochersis porebensis Szczygielski & Sulej, 2016, provides novel insights about shell ankylosis

Shell suture obliteration (ankylosis) was exceptionally frequent in the earliest turtles, in contrast to post-Triassic taxa. Since modern turtles grow mostly along sutures, early ankylosis in Triassic taxa is intriguing. The Triassic turtle Proterochersis porebensis Szczygielski & Sulej, 2016 is known from numerous specimens, allowing observation of shell microstructure changes during ontogeny. Shell ankylosis occurred seemingly randomly in individuals of variable size, including small and morphologically juvenile, and completely obscured the initial bony composition. We propose that this phenomenon in the Triassic turtles can be an effect of early evolutionary stages of shell histogenesis and physiological mechanisms still used in shell regeneration in modern species. We also describe some parallels between the unusual peripheral microstructure of another Triassic turtle, Waluchelys cavitesta Sterli, Martínez, Cerda & Apaldetti, 2020, and Proterochersis porebensis. Microstructural changes imply that Proterochersis porebensis could change habitat during ontogeny, small individuals appearing more aquatic and larger more terrestrial.

Phylogenomic structure and speciation in an emerging model: the Sphagnum magellanicum complex (Bryophyta).

Sphagnum magellanicum is one of two Sphagnum species for which a reference-quality genome exists to facilitate research in ecological genomics. Phylogenetic and comparative genomic analyses were conducted based on resequencing data from 48 samples and RADseq analyses based on 187 samples. We report herein that there are four clades/species within the S. magellanicum complex in eastern North America and that the reference genome belongs to Sphagnum divinum. The species exhibit tens of thousands (RADseq) to millions (resequencing) of fixed nucleotide differences. Two species, however, referred to informally as S. diabolicum and S. magni because they have not been formally described, are differentiated by only 100 (RADseq) to 1000 (resequencing) of differences. Introgression among species in the complex is demonstrated using D-statistics and f4 ratios. One ecologically important functional trait, tissue decomposability, which underlies peat (carbon) accumulation, does not differ between segregates in the S. magellanicum complex, although previous research showed that many closely related Sphagnum species have evolved differences in decomposability/carbon sequestration. Phylogenetic resolution and more accurate species delimitation in the S. magellanicum complex substantially increase the value of this group for studying the early evolutionary stages of climate adaptation and ecological evolution more broadly.

Dynamic molecular evolution of a supergene with suppressed recombination in white-throated sparrows.

In white-throated sparrows, two alternative morphs differing in plumage and behavior segregate with a large chromosomal rearrangement. As with sex chromosomes such as the mammalian Y, the rearranged version of chromosome two (ZAL2m) is in a near-constant state of heterozygosity, offering opportunities to investigate both degenerative and selective processes during the early evolutionary stages of 'supergenes.' Here, we generated, synthesized, and analyzed extensive genome-scale data to better understand the forces shaping the evolution of the ZAL2 and ZAL2m chromosomes in this species. We found that features of ZAL2m are consistent with substantially reduced recombination and low levels of degeneration. We also found evidence that selective sweeps took place both on ZAL2m and its standard counterpart, ZAL2, after the rearrangement event. Signatures of positive selection were associated with allelic bias in gene expression, suggesting that antagonistic selection has operated on gene regulation. Finally, we discovered a region exhibiting long-range haplotypes inside the rearrangement on ZAL2m. These haplotypes appear to have been maintained by balancing selection, retaining genetic diversity within the supergene. Together, our analyses illuminate mechanisms contributing to the evolution of a young chromosomal polymorphism, revealing complex selective processes acting concurrently with genetic degeneration to drive the evolution of supergenes.

Lava deltas, a key landform in oceanic volcanic islands: El Hierro, Canary Islands

Marine and subaerial erosion of volcanic ocean islands form coastal cliffs and shore platforms, particularly during stable sea levels. Posterosional lava flows can spill over these coastal cliffs and fill the platforms, leading to the progradation of lava deltas. This work aims to analyze this volcanic rocky coast setting at the island scale and to assess the volcanic constructional and erosive degradational effects on the coast at the scale of one volcanic edifice. El Hierro Island, Canary Islands, exemplifies a rocky coast with an active sea-cliff profile, reflecting its early evolutionary stage as a young ocean volcanic island with no fringing reef. The occurrence of a contemporary insular shelf formed during the Holocene sea-level highstand (<7 ka) allows constraining the ages of those eruptions forming lava deltas affecting this geomorphological landform. A detailed bathymetry around the island allowed us to distinguish 17 eruptions fulfilling this criterion. The Montaña del Tesoro, which occurred about 1050 years BP, is one of these eruptions and was selected as a case study for morphometric modeling integrating subaerial and submarine data at the scale of a volcanic edifice. This eruption was a Strombolian basaltic volcanic event that produced a scoria cone, pyroclastic fall deposits, and lava flows that reached the ocean in the eastern rift zone of El Hierro island. We combine field-based observations with topographic and bathymetric data analysis to reconstruct the pre- and post-eruption Digital Elevation Models (DEMs) and, comparing with present-day DEM, to analyze morphometrically the influence of volcanism on the coastal landscape's development. The resulting landform complexity required the discretization of the lava field according to the coastline evolution and lava front sectors, and the subaerial or submarine lava placement. The pyroclastic materials' total erupted bulk volume (12,829,578 m3) corresponds to a volcanic eruption index (VEI) of 3. This event was primarily effusive. From a dense rock equivalent (DRE) volume of 25,615,424 m3, 87 % flowed as lava, 10 % formed the cinder cone, and 3 % the tephra fall deposits. We quantitatively demonstrate that dominant degradation occurs in the lava field, mainly disturbed by marine erosion. Marine erosion removed 9 % of the erupted volume of lava flows against 1 % by fluvial erosion. This work provides methods and results of great interest with different implications in oceanic volcanic islands, among which we can mention coastal planning (e.g., rock coast evolution) and volcanic risk assessment (e.g., the importance of Holocene sea-level rise on the development of shore platforms facilitating the progradation of lava deltas).

The formation and development of avulsions and splays of submarine channel systems: Insights from 3D seismic data from the northeastern Bengal Fan

Avulsions and splays of submarine channels are important autogenic responses affecting sediment distribution in deep-water areas; however, their formation and development are still not well understood. Using high-resolution 3D seismic data and spectral decomposition red–green–blue (RGB) color blends, two seismically well-imaged submarine channel systems (SCS1 and SCS2) on the northeastern Bengal Fan are used to document the formation and development of avulsions and splays. The results suggest that avulsions occur mainly during the early evolution stage of submarine channel systems. SCS1 and SCS2 are respectively accompanied by one and four avulsions and accordingly produce two and five independent submarine channels. During this early phase, these channels collectively incise into the underlying stratigraphy but lack levee deposits. Splays, in contrast, develop consistently during the late evolution stage of the submarine channel systems. Three crevasse splays and three overbank splays develop on the overbank areas of SCS1 and SCS2. During that late stage, channel and levee deposits build over the site of former erosion, thus forming the aggradational phase of channel evolution. Crevasse and overbank splays are two different types of splays observed on this part of the Bengal Fan. The former are created by flow breaching of the adjacent levees, producing large-scale elongated shapes; they are related to relatively stable sediment gravity flows, a high-degree of channel instability, and steep levee topography. Overbank splays, however, are created by flow overtopping adjacent levees and produce small-scale, fan-like shapes; they are related to gradually-weaking sediment gravity flows, a low-degree channel unstability, and gentle levee topography.

Characteristics and controls of inorganic and organic phosphorus transformation during long-term paddy soil evolution

Information on phosphorus (P) transformation during long-term paddy soil evolution is important for maintaining rice yield and nutrient management. This study was aimed to reveal the characteristics and controls of inorganic and organic P transformation during paddy soil evolution over a millennial time scale using both sequential chemical extraction and solution 31P nuclear magnetic resonance spectroscopy. Results show that the rate and trajectory of P evolution in the topsoil differ markedly from that of the illuvial horizon. The amount of apatite P, non-occluded P, occluded P and total P in the topsoils increased rapidly during the early stage of paddy soil evolution (< 50 yrs) due to anthropogenic P additions, but declined in the older paddy soils due to the leaching loss of P sorbents (CaCO3 and Fe/Al oxides); thus, the added P cannot be efficiently retained by the older paddy soils. Total organic P including phosphate monoester in the topsoils reached maximum in the 300-yr paddy soil and declined thereafter. However, the phosphate diester pool (including DNA) and its proportion in the topsoil increased continuously across the paddy soil chronosequence, suggesting that long-term paddy cultivation promoted labile organic P accumulation. In the deeper soil horizons with less human impacts, the temporal trends in inorganic and organic P across the paddy soil chronosequence can be fully predicted by previous established P transformation models during natural pedogenesis, although the rates of P changes differ among different sites. Our study demonstrates that long-term paddy cultivation alters the rate and trajectory of inorganic and organic P transformation in the topsoils over a millennial time scale, and highlights the importance of labile organic P activation for nutrient supply in the older paddy soils.

Homogenization of zircon Hf isotopes during late-stage granite crystallization

Zircon Hf isotope compositions provide valuable constraints on granite petrogenesis and the evolution of continental crust. However, the causes of variations in zircon Hf isotope ratios during magma evolution are poorly understood. Here we compiled zircon UPb ages and LuHf isotope compositions of the Permian-Triassic granites in South China to demonstrate that Hf isotope variability is common in the early stages of granitic magma evolution, but Hf isotope ratios are homogenized during the final stages of granite crystallization. Late-grown zircons have relatively high concentrations of U and have εHf(t) values approximating the median values of multiple analyses for the low-U zircon in the same samples. Hafnium isotope variations measured in low-U zircon could be related to incremental assembly of multiple isotopically distinct magma batches derived from partial melting of heterogeneous crustal rocks; these discrete magma batches may have remained isolated from each other during segregation and extraction in the source and during ascent through the crust. After emplacement, these magma batches may have experienced variable degrees of mixing resulting in homogenization of Hf isotopes in late crystallized zircon. Coupled with whole-rock geochemical data of the Permian-Triassic granites, we argue that the Hf isotope homogenization is related to crystallization of zircon from late-stage magmas or precipitation of hydrothermal zircon from exsolved hydrothermal fluids during the final stages of magma solidification. Hafnium isotope homogenization in late-stage melts/fluids may have been driven by an increased concentration of fluorine and the efficient diffusion of hafnium-fluoride complexes through silicic melt. These results provide a deeper understanding of the mechanisms that contribute to Hf isotope heterogeneity in zircon during granite crystallization.

Interstellar Complex Organic Molecules in SiO-traced Massive Outflows

The interstellar medium contains dust and gas, in which molecules can proliferate at high densities and in cold conditions. Interstellar complex organic molecules (iCOMs) are C-bearing species that contain at least six atoms. As they are detected in young stellar objects, iCOMs are expected to inhabit early stages of star formation evolution. In this study, we try to determine which iCOMs are present in the outflow component of massive protostars. To do this, we analyzed the morphological extension of blue- and redshifted iCOM emission in a sample of 11 massive protostars employing mapping observations at 1 mm within a ∼1 GHz bandwidth for both the IRAM-30 m and APEX telescopes. We modeled the iCOM emission of the central pointing spectra of our objects using the XCLASS local thermal equilibrium radiative transfer code. We detected the presence of several iCOMs such as CH3OH, 13CH3OH, CH3OCHO, C2H5C15N, and (c-C3H2)CH2. In G034.41+0.24, G327.29-0.58, G328.81+0.63, G333.13-0.43, G340.97-1.02, G351.45+0.66, and G351.77-0.54, the iCOM lines show a faint broad-line profile. Due to the offset peak positions of the blue- and redshifted emission, covering from ∼0.1 to 0.5 pc, these wings are possibly related to movements external to the compact core, such as large-scale low-velocity outflows. We have also established a correlation between the parent iCOM molecule CH3OH and the shock tracer SiO, reinforcing the hypothesis that shock environments provide the conditions to boost the formation of iCOMs via gas-phase reactions.

Fast evaluation of the Boltzmann collision operator using data driven reduced order models

We consider application of reduced order models (ROMs) to accelerating solutions of the spatially homogeneous Boltzmann equation for the class of problems of spatially homogeneous relaxation of sums of two homogeneous Gaussian densities. Approximation spaces for the ROMs are constructed by performing singular value decomposition of the solution data matrix and extracting principal singular vectors/modes. The first ROM results from a straightforward Galerkin discretization of the spatially homogeneous Boltzmann equation using a truncated basis of the singular vectors. The model approximates solutions to the Boltzmann equation accurately during early stages of evolution. However, it suffers from presence of ROM residuals at later stages and exhibits slowly growing modes for larger ROM sizes. In order to achieve stability, the second ROM evolves the difference between the solution and the steady state. The truncated singular vectors are orthogonalized to the steady state and modified locally to enforce zero density, momentum, and temperature moments. Exponential damping of ROM residuals is introduced to enforce physical accuracy of the steady state solution. Solutions obtained by the second ROM are asymptotically stable in time and provide accurate approximations to solutions of the Boltzmann equation. Complexity for both models is O(K3) where K is the number of singular vectors retained in the ROMs. For the considered class of problems, the models result in up to three orders of magnitude reduction in computational time as compared to the O(M2) nodal discontinuous Galerkin (DG) discretization, where M is the total number of velocity points.