Large Embryos Research Articles

Maize kernel development.

Maize (Zea mays) is a leading cereal crop in the world. The maize kernel is the storage organ and the harvest portion of this crop and is closely related to its yield and quality. The development of maize kernel is initiated by the double fertilization event, leading to the formation of a diploid embryo and a triploid endosperm. The embryo and endosperm are then undergone independent developmental programs, resulting in a mature maize kernel which is comprised of a persistent endosperm, a large embryo, and a maternal pericarp. Due to the well-characterized morphogenesis and powerful genetics, maize kernel has long been an excellent model for the study of cereal kernel development. In recent years, with the release of the maize reference genome and the development of new genomic technologies, there has been an explosive expansion of new knowledge for maize kernel development. In this review, we overviewed recent progress in the study of maize kernel development, with an emphasis on genetic mapping of kernel traits, transcriptome analysis during kernel development, functional gene cloning of kernel mutants, and genetic engineering of kernel traits.

Salamanders: The molecular basis of tissue regeneration and its relevance to human disease.

Salamanders are recognized for their ability to regenerate a broad range of tissues. They have also have been used for hundreds of years for classical developmental biology studies because of their large accessible embryos. The range of tissues these animals can regenerate is fascinating, from full limbs to parts of the brain or heart, a potential that is missing in humans. Many promising research efforts are working to decipher the molecular blueprints shared across the organisms that naturally have the capacity to regenerate different tissues and organs. Salamanders are an excellent example of a vertebrate that can functionally regenerate a wide range of tissue types. In this review, we outline some of the significant insights that have been made that are aiding in understanding the cellular and molecular mechanisms of tissue regeneration in salamanders and discuss why salamanders are a worthy model in which to study regenerative biology and how this may benefit research fields like regenerative medicine to develop therapies for humans in the future.

Breeding Buckwheat for Increased Levels and Improved Quality of Protein.

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) and common buckwheat (Fagopyrum esculentum Moench) are important sources of proteins with balanced amino-acid compositions, and thus of high nutritional value. The polyphenols naturally present in Tartary buckwheat and common buckwheat lower the true digestibility of the proteins. Digestion-resistant peptides are a vehicle for fecal excretion of steroids, and in this way, for bile acid elimination and reduction of cholesterol concentrations in serum. Buckwheat proteins are more effective compared to soy proteins for the prevention of gallstone formation. Tartary and common buckwheat grain that contains appropriate amounts of selenium-containing amino acids can be produced as functional food products. The protein-rich by-products of buckwheat are a good source of bioactive substances that can suppress colon carcinogenesis by reducing cell proliferation. The grain embryo is a rich source of proteins, so breeding buckwheat with larger embryos is a possible strategy to increase protein levels in Tartary and common buckwheat grain. However, chemical analysis of the grain is the most relevant criterion for assessing grain protein levels and quality.

Formation of Venus, Earth and Mars: Constrained by Isotopes

We discuss the current state of knowledge of terrestrial planet formation from the aspects of different planet formation models and isotopic data from 182Hf-182W, U-Pb, lithophile-siderophile elements, 48Ca/44Ca isotope samples from planetary building blocks, 36Ar/38Ar, 20Ne/22Ne, 36Ar/22Ne isotope ratios in Venus' and Earth's atmospheres, the expected solar 3He abundance in Earth's deep mantle and Earth's D/H sea water ratios that shed light on the accretion time of the early protoplanets. Accretion scenarios that can explain the different isotope ratios, including a Moon-forming event after ca. 50 Myr, support the theory that the bulk of Earth's mass (>80%) most likely accreted within 10-30 Myr. From a combined analysis of the before mentioned isotopes, one finds that proto-Earth accreted 0.5-0.6 MEarth within the first ~4-5 Myr, the approximate lifetime of the protoplanetary disk. For Venus, the available atmospheric noble gas data are too uncertain for constraining the planet's accretion scenario accurately. However, from the available Ar and Ne isotope measurements, one finds that proto-Venus could have grown to 0.85-1.0 MVenus before the disk dissipated. Classical terrestrial planet formation models have struggled to grow large planetary embryos quickly from the tiniest materials within the typical lifetime of protoplanetary disks. Pebble accretion could solve this long-standing time scale controversy. Pebble accretion and streaming instabilities produce large planetesimals that grow into Mars-sized and larger planetary embryos during this early accretion phase. The later stage of accretion can be explained well with the Grand-Tack, annulus or depleted disk models. The relative roles of pebble accretion and planetesimal accretion/giant impacts are poorly understood and should be investigated with N-body simulations that include pebbles and multiple protoplanets.

Tasa de preñez post vitrificación en los embriones de équidos producidos in vivo. Revisión

Vitrification is a cryo-preservation method often used in embryos obtained from mares or jennies. It consists in the dramatic reduction of temperature to levels close to -196 °C, that allows the cryopreserving solution containing the embryo to pass from liquid to vitreous state. Several improvements to vitrification protocols have made possible to cryo-preserve embryos with different sizes; since during the first decade after the year 2000, only small embryos were successfully vitrified. Embryos collected at the sixth day post ovulation (PO) are usually smaller or equal to 300 micrometers in diameter (≤ 300 µmØ) and can be routinely vitrified following simple protocols; they have a higher post vitrification pregnancy rate (PVPR) when compared to large embryos which have more than 300 micrometers in diameter (˃ 300 µmØ). The high PVPR of embryos ≤ 300 µmØ is due to an embryo capsule (EC) that is not fully developed yet and has a high permeability to cryo-preserving solutions. At present time, embryos collected either the seventh or eighth day PO are ˃ 300 µmØ and are characterized to have a low post vitrification survival; in order to increase their PVPR their EC might be punctured to make it permeable to cryopreserving solutions. Additionally, there are at least two factors that can be manipulated to increase the PVPR of embryos ˃ 300 µmØ; one is to reduce their size by aspiring their blastocoelic liquid (BL), and the other is to induce a high temperature transfer index (TTI) to rapidly reach -196 °C.

Seasonal migrations of pregnant blue sharks Prionace glauca in the northwestern Pacific

Information on the movements of highly migratory species is important to understand their ecology, including habitat use, population connectivity, and stock structure, to implement appropriate management and conservation measures. The blue shark Prionace glauca (Carcharhinidae) is highly migratory, has a global distribution, and is ecologically and economically important as one of the most abundant apex marine predators; however, the migration patterns of pregnant females are unknown. Here, we used pop-up satellite archival tags to elucidate seasonal migration of pregnant blue sharks in the northwestern Pacific. Of 24 tagged adult females, archival data were subsequently obtained for 21 individuals (141.1-243.3 cm precaudal length). Based on ultrasonography or analysis of sex steroid hormones, 17 of these females were confirmed to be pregnant at the time of release. Females with small embryos moved in a northeasterly direction, from subtropical (10-30°N) into temperate (30-40°N) waters during autumn and the following spring; 2 of these females returned to subtropical waters in spring and summer. In contrast, females with large embryos moved in a southwesterly direction, from temperate into subtropical waters during spring and autumn. Tagged sharks also showed regional differences in diving behaviors, reflecting thermal habitats in the ocean environment. Our findings indicate that pregnant blue sharks undergo a seasonal northeast-southwest migration within a year to give birth to pups in productive temperate waters. This is the first report on seasonal reproductive migration of pregnant blue sharks in the global ocean.

Vitrification of Equine In Vivo-Derived Embryos After Blastocoel Aspiration.

Embryo cryopreservation is normally performed with great success in species like humans and cattle. The large size of in vivo-derived equine embryos and the presence of a capsule-impermeable to cryoprotectants-have complicated the use of embryo cryopreservation in equine reproduction. A breakthrough for this technique was obtained when large equine embryos could be successfully cryopreserved after collapsing the blastocoel cavity using a micromanipulation system. High pregnancy rates have been obtained when vitrification is used in combination with embryo collapse.

Generation of a fertile ask1 mutant uncovers a comprehensive set of SCF-mediated intracellular functions.

Many eukaryotic intracellular processes employ protein ubiquitylation by ubiquitin E3 ligases for functional regulation or protein quality control. In plants, the multi-subunit Skp1-Cullin1-F-box (SCF) complexes compose the largest group of E3 ligases whose specificity is determined by a diverse array of F-box proteins. Although both sequence divergence and polymorphism of F-box genes well support a broad spectrum of SCF functions, experimental evidence is scarce due to the low number of identified SCF substrates. Taking advantage of the bridge role of Skp1 between F-box and Cullin1 in the complex, we systematically analyzed the functional influence of a well-characterized Arabidopsis Skp1-Like1 (ASK1) Ds insertion allele, ask1, in different Arabidopsis accessions. Through 10 generations of backcrossing with Columbia-0 (Col-0), we partially rescued the fertility of this otherwise sterile ask1 allele in Landsberg erecta, thus providing experimental evidence showing the polymorphic roles of SCF complexes. This ask1 mutant produces twisted rosette leaves, a reduced number of petals, fewer viable pollen grains, and larger embryos and seeds compared to Col-0. RNA-Seq-based transcriptome analysis of ask1 uncovered a large spectrum of SCF functions, which is greater than a 10-fold increase compared with previous studies. We also identified its hyposensitive responses to auxin and abscisic acid treatments and enhanced far-red light/phyA-mediated photomorphogenesis. Such diverse roles are consistent with the 20-30% reduction of ubiquitylation events in ask1 estimated by immunoblotting analysis in this work. Collectively, we conclude that ASK1 is a predominant Skp1 protein in Arabidopsis and that the fertile ask1 mutant allowed us to uncover a comprehensive set of SCF functions.

The aeolian-erosion barrier for the growth of metre-size objects in protoplanetary discs

ABSTRACT Aeolian erosion is a destructive process that can erode small-size planetary objects through their interaction with a gaseous environment. Aeolian erosion operates in a wide range of environments and under various conditions. Aeolian erosion has been extensively explored in the context of geophysics in terrestrial planets. Here we show that aeolian erosion of cobbles, boulders, and small planetesimals in protoplanetary discs can constitute a significant barrier for the early stages of planet formation. We use analytic calculations to show that under the conditions prevailing in protoplanetary discs small bodies ($10\!-\!10^4 \, \rm {m}$) are highly susceptible to gas-drag aeolian erosion. At this size-range aeolian erosion can efficiently erode the planetesimals down to tens-cm size and quench any further growth of such small bodies. It thereby raises potential difficulties for channels suggested to alleviate the metre-size barrier. Nevertheless, the population of ∼decimetre-size cobbles resulting from aeolian erosion might boost the growth of larger (>km size) planetesimals and planetary embryos through increasing the efficiency of pebble-accretion, once/if such large planetesimals and planetary embryos exist in the disc.

Embryo transfers in Criollo horses: what is known about economic impacts

Many years of poor results of equine embryo cryopreservation has produced a lack of confidence in this technique. Embryo cryopreservation has been successfully used for more than 20 years in other species like bovine and human. The large size of the embryos and the presence of a capsule impermeable to cryoprotectants have been the two main reasons for the failure. In the last few years, a mayor breakthrough for this technique was obtained when large equine embryos could be successfully cryopreserved after breaching the capsule and collapsing the blastocoel cavity. In the present study, we compared the pregnancy rates obtained by vitrification or cryopreservation by slow freezing of embryos smaller than 300 μm. No difference was found between vitrification and slow freezing of embryos <180 μm (pregnancy rate on day 16: 34/61, 55.7%; 6/8, 75%) but produced very low results for embryos between 180 and 300 μm in diameter (0/11, 0%; 1/7, 14.3%). Embryos larger than 300 μm were collapsed before cryopreservation, and two different types of carriers, hemi-straw or Stripper-Tip, were used for vitrification. High pregnancy rates were obtained when the hemi-straw was used as a carrier (7/10, 70% vs. 0/5, 0%), demonstrating that a minimum vitrification volume was essential to preserve the embryo viability. These findings establish that, due to the large range in diameter, equine embryos need to be cryopreserved using different protocols depending on their size.

Loss and Fractionation of Noble Gas Isotopes and Moderately Volatile Elements from Planetary Embryos and Early Venus, Earth and Mars

Here we discuss the current state of knowledge on how atmospheric escape processes can fractionate noble gas isotopes and moderately volatile rock-forming elements that populate primordial atmospheres, magma ocean related environments, and catastrophically outgassed steam atmospheres. Variations of isotopes and volatile elements in different planetary reservoirs keep information about atmospheric escape, composition and even the source of accreting material. We summarize our knowledge on atmospheric isotope ratios and discuss the latest evidence that proto-Venus and Earth captured small H$_2$-dominated primordial atmospheres that were lost by EUV-driven hydrodynamic escape after the disk dispersed. All relevant thermal and non-thermal atmospheric escape processes that can fractionate various isotopes and volatile elements are discussed. Erosion of early atmospheres, crust and mantle by large planetary impactors are also addressed. Further, we discuss how moderately volatile elements such as the radioactive heat producing element $^{40}$K and other rock-forming elements such as Mg can also be outgassed and lost from magma oceans that originate on large planetary embryos and accreting planets. Outgassed elements escape from planetary embryos with masses that are $\geq$\,M$_{\rm Moon}$ directly, or due to hydrodynamic drag of escaping H atoms originating from primordial- or steam atmospheres at more massive embryos. We discuss how these processes affect the final elemental composition and ratios such as K/U, Fe/Mg of early planets and their building blocks. Finally, we review modeling efforts that constrain the early evolution of Venus, Earth and Mars by reproducing their measured present day atmospheric $^{36}$Ar/$^{38}$Ar, $^{20}$Ne/$^{22}$Ne noble gas isotope ratios and the role of isotopes on the loss of water and its connection to the redox state on early Mars.

Escape of rock-forming volatile elements and noble gases from planetary embryos

Large planetesimals and planetary embryos ranging from several hundred to a few thousand kilometers can develop magma oceans through mutual collisions, gravitational energy, and the heating of short-lived radioactive elements. During their solidification after the dissipation of the disk a steam atmosphere will be catastrophically outgassed and may be lost efficiently via hydrodynamic escape, as long as it does not condense. The escaping H-atoms that originate from the dissociation of H2O and H2 will drag heavier trace elements like noble gases such as Ne and Ar and outgassed moderately volatile rock-forming elements such as K, Na, Si, Mg, etc. into space. Under consideration of various EUV flux evolution scenarios of young solar-type stars, we apply an upper atmosphere hydrodynamic escape model that includes the dragging of heavier species by escaping H-atoms. We investigate the atmospheric/elemental escape and fractionation from planetary embryos with masses of 1 MMoon, 0.5 MMars, 1 MMars, and 1.5 MMars at different orbital distances between the orbits of Venus and Mars. Our results indicate that the steam atmospheres and the embedded trace elements will be lost efficiently before they condense for masses ≤0.5 MMars and orbital distances up to 1 AU. For heavier embryos of up to 1.5 MMars almost all of the considered steam atmospheres can be lost within ≈12 Myr, which lies within the time frame of the formation of the first Martian protocrust after ≈20 Myr, i.e. for such steam atmospheres to be lost completely a shallow magma ocean must remain below the atmosphere, which might be achieved through frequent impacts onto the planetary embryo. The considered outgassed noble gases and rock-forming elements will be completely dragged away together with the steam atmospheres under the assumption that the trace elements will reach the thermosphere. For embryos with masses ≤MMoon the gravity is too weak for a dense atmosphere to build up for the high magma ocean related surface temperatures and all outgassed elements will escape immediately to space. For all considered planetary masses and orbits the loss rates of Ar and Ne are so high that there will be no fractionation of their isotopes. The studied planetary embryos, even though not isotopically fractionated, will therefore be severely depleted in noble gases and moderately volatile elements. Hydrodynamic escape might then also affect the final composition of terrestrial planets that accrete out of such planetary embryos, such as the volatile content and the Fe/Mg ratio of a planet.

TRA1: A Locus Responsible for Controlling Agrobacterium-Mediated Transformability in Barley.

In barley (Hordeum vulgare L.), Agrobacterium-mediated transformation efficiency is highly dependent on genotype with very few cultivars being amenable to transformation. Golden Promise is the cultivar most widely used for barley transformation and developing embryos are the most common donor tissue. We tested whether barley mutants with abnormally large embryos were more or less amenable to transformation and discovered that mutant M1460 had a transformation efficiency similar to that of Golden Promise. The large-embryo phenotype of M1460 is due to mutation at the LYS3 locus. There are three other barley lines with independent mutations at the same LYS3 locus, and one of these, Risø1508 has an identical missense mutation to that in M1460. However, none of the lys3 mutants except M1460 were transformable showing that the locus responsible for transformation efficiency, TRA1, was not LYS3 but another locus unique to M1460. To identify TRA1, we generated a segregating population by crossing M1460 to the cultivar Optic, which is recalcitrant to transformation. After four rounds of backcrossing to Optic, plants were genotyped and their progeny were tested for transformability. Some of the progeny lines were transformable at high efficiencies similar to those seen for the parent M1460 and some were not transformable, like Optic. A region on chromosome 2H inherited from M1460 is present in transformable lines only. We propose that one of the 225 genes in this region is TRA1.

Natural size variation among embryos leads to the corresponding scaling in gene expression

Xenopus laevis frogs from laboratory stocks normally lay eggs exhibiting extensive size variability. We find that these initial size differences subsequently affect the size of the embryos prior to the onset of growth, and the size of tadpoles during the growth period. Even though these tadpoles differ in size, their tissues, organs, and structures always seem to be properly proportioned, i.e. they display static allometry. Initial axial patterning events in Xenopus occur in a spherical embryo, allowing easy documentation of their size-dependent features. We examined the size distribution of early Xenopus laevis embryos and measured diameters that differed by about 38% with a median of about 1.43 ​mm. This range of embryo sizes corresponds to about a 1.9-fold difference in surface area and a 2.6-fold difference in volume. We examined the relationship between embryo size and gene expression and observed a significant correlation between diameter and RNA content during gastrula stages. In addition, we investigated the expression levels of genes that pattern the mesoderm, induce the nervous system and mediate the progression of ectodermal cells to neural precursors in large and small embryos. We found that most of these factors were expressed at levels that scaled with the different embryo sizes and total embryo RNA content. In agreement with the changes in transcript levels, the expression domains in larger embryos increased proportionally with the increase in surface area, maintaining their relative expression domain size in relation to the total size of the embryo. Thus, our study identified a mechanism for adapting gene expression domains to embryo size by adjusting the transcript levels of the genes regulating mesoderm induction and patterning. In the neural plate, besides the scaling of the expression domains, we observed similar cell sizes and cell densities in small and large embryos suggesting that additional cell divisions took place in large embryos to compensate for the increased size. Our results show in detail the size variability among Xenopus laevis embryos and the transcriptional adaptation to scale gene expression with size. The observations further support the involvement of BMP/ADMP signaling in the scaling process.

Larval Performance of Amphidromous and Landlocked Atyid Shrimp Species in the Genus Paratya under Different Feeding Conditions.

Freshwater shrimps in the family Atyidae exhibit two life history traits: 1) amphidromy, with many small embryos hatching into planktotrophic larvae that develop in the sea, and 2) landlocked, with few large embryos hatching into non-feeding lecithotrophic larvae, or facultative lecithotrophic larvae that develop in freshwater. The lecithotrophy of larvae is considered an adaptation to limited food conditions in the freshwater environment. Furthermore, faster development and settlement behaviours that large larvae exhibit are considered adaptations that allow the larvae to stay in or near parental habitats in fast-flowing streams. We therefore hypothesized that the facultative lecithotrophic larvae of landlocked shrimps might better adapt to limited food conditions as their large body size develops, an adaptation to maintain habitat position in flowing streams, than do planktotrophic larvae of companion amphidromous species developing in the sea. To test this hypothesis, we compared the larval feeding habits and size of two closely related species in the genus Paratya: the amphidromous P. compressa, with planktotrophic larvae, and the landlocked P. improvisa, with facultative lecithotrophic larvae. Larvae were reared by being fed commercially preserved or cultured phytoplankton (Tetraselmis sp.) and cultured zooplankton rotifers. Paratya compressa larvae did not survive, but P. improvisa larvae did develop into the juvenile stage under poor feeding conditions with preserved Tetraselmis alone, supporting our hypothesis of the effects of different larval feeding habits in amphidromous and landlocked atyid shrimp species. Hatchlings were larger and larval duration was shorter in P. improvisa than in P. compressa. Paratya improvisa larvae exhibited settlement behaviour beginning with the early zoeal stage. Our results also highlighted the retention strategy by which landlocked P. improvisa larvae stay in or near parental habitats.

A rice mutant with a giant embryo has increased levels of lipophilic antioxidants, E vitamers, and γ‐oryzanol fraction

AbstractBackground and objectiveLipophilic compounds in rice bran have health beneficial and functional properties. These lipophilic antioxidants in a giant embryo mutant (GEDrew) derived from a tropical japonica variety Drew were determined to evaluate its potential as a specialty variety.FindingsGEDrew had double the size of embryo and lower kernel weight than Drew. The majority of the tocols in the embryo were in the form of tocopherols with α‐tocopherol accounting for approximately 70%, while the tocopherols in bran ranged from 22% to 43% of total tocols. On a per embryo basis, GEDrew had a higher quantity of tocols compared with Drew; however, on a weight basis, the concentration of tocols in GEDrew was less than Drew. The γ‐oryzanol concentration in embryos was the same for both the mutant and wild type. The smaller brown rice kernel size and bigger embryo size of GEDrew resulted in higher proportion of bran + embryo (w/w), which led to higher total tocopherols, tocotrienols, and γ‐oryzanol in the whole grain of GEDrew relative to Drew.ConclusionA rice mutant with a large embryo had an elevated level of γ‐oryzanol and tocols, both as a group and as individual homologs, in whole grains as compared to the wild type.Significance and noveltyGEDrew has the potential to be grown as a specialty rice variety for the purposes of isolating its bran, oil, and lipophilic antioxidants for use by the food and cosmetic industries.

Effects of Short Term Methylmercury Exposure on Growth and Development of the Large Yellow Croaker Embryos and Larvae

The toxic effects of methylmercury (MeHg) on organisms have caused widespread concerns, but little has been reported on its effects in marine fish. This study investigated the acute and sub-lethal toxicities of MeHg chloride to large yellow croaker (Pseudosciaena crocea) embryos and larvae. Acute toxicity tests showed that the 48-h LC50 values of methylmercury to the embryos and larvae were 28.39 (21.33-33.98) and 18.27 (11.33-29.29) μg L -1 , respectively, while the 96-h LC50 value for larvae was 9.28 (4.41-14.49) μg L -1 , indicating that larvae were more sensitive to MeHg than the embryos. On the other hand, MeHg could cause low hatching success, increase larvae heart rate at concentrations ≥ 20 μg L -1 , as well as delayed hatching process, reduced survival and higher morphological malformations at concentrations ≥ 10 μg L -1 to the embryos and larvae. Results showed that the early life stages of large yellow croaker were sensitive to MeHg exposure.

A unified model for hydrogen in the Earth and Moon: No one expects the Theia contribution

The Moon is thought to have formed after a planetary embryo, known as Theia, collided with the proto-Earth 4.5 billion years ago. This so-called Giant Impact was the last major event during Earth’s accretion, and its effects on the composition of the Earth and the newly forming Moon would be measureable today. Recent work on lunar samples has revealed that the Moon’s water was not lost as a result of this giant impact. Instead, the Moon appears to contain multiple hydrogen reservoirs with diverse deuterium-to-hydrogen (D/H) ratios. For the first time, we incorporate hydrogen isotopic measurements of lunar samples to help constrain the composition of Theia. We show that the Moon incorporated very low-D/H (δD ≈ -750‰) materials that only could have derived from solar nebula H2 ingassed into the magma ocean of a large (∼0.4 ME) planetary embryo that was largely devoid of chondritic water. We infer Theia was a very large body comparable in size to the proto-Earth, and was composed almost entirely of enstatite chondrite-like material. These conclusions limit the type of impact to a “merger” model of similarly-sized bodies, or possibly a “hit-and-run” model, and they rule out models that mix isotopes too effectively.

Planets in Binaries: Formation and Dynamical Evolution

Binary systems are very common among field stars, yet the vast majority of known exoplanets have been detected around single stars. While this relatively small number of planets in binaries is probably partly due to strong observational biases, there is, however, statistical evidence that planets are indeed less frequent in binaries with separations smaller than 100 au, strongly suggesting that the presence of a close-in companion star has an adverse effect on planet formation. It is indeed possible for the gravitational pull of the second star to affect all the different stages of planet formation, from proto-planetary disk formation to dust accumulation into planetesimals, to the accretion of these planetesimals into large planetary embryos and, eventually, the final growth of these embryos into planets. For the crucial planetesimal-accretion phase, the complex coupling between dynamical perturbations from the binary and friction due to gas in the proto-planetary disk suggests that planetesimal accretion might be hampered due to increased, accretion-hostile impact velocities. Likewise, the interplay between the binary’s secular perturbations and mean motion resonances lead to unstable regions, where not only planet formation is inhibited, but where a massive body would be ejected from the system on a hyperbolic orbit. The amplitude of these two main effects is different for S- and P-type planets, so that a comparison between the two populations might outline the influence of the companion star on the planet formation process. Unfortunately, at present the two populations (circumstellar or circumbinary) are not known equally well and different biases and uncertainties prevent a quantitative comparison. We also highlight the long-term dynamical evolution of both S and P-type systems and focus on how these different evolutions influence the final architecture of planetary systems in binaries.

The formation of Jupiter’s diluted core by a giant impact

The Juno mission1 has provided an accurate determination ofJupiter's gravitational field2, which hasbeenusedto obtain information about the planet's compositionand internal structure. Severalmodels of Jupiter's structure that fit the probe's data suggest that the planet has a diluted core, with a total heavy-element mass ranging from ten to a few tens of Earth masses(about5 to 15 per cent of the Jovian mass), and that heavy elements(elements otherthan hydrogen and helium)are distributed within a region extending to nearly half of Jupiter's radius3,4. Planet-formation models indicate that most heavy elements are accreted during the earlystages ofa planet's formation to create a relativelycompact core5-7 and that almost no solids are accreted duringsubsequent runaway gas accretion8-10. Jupiter's diluted core, combined with its possible high heavy-element enrichment, thus challenges standard planet-formation theory. A possible explanation is erosion of the initially compact heavy-element core, but the efficiency of such erosion is uncertain and depends on both the immiscibility of heavy materials in metallic hydrogen and on convective mixing as the planet evolves11,12. Another mechanism that canexplain this structure is planetesimal enrichment and vaporization13-15 during the formation process, although relevant modelstypically cannotproduce an extended diluted core. Here we show that a sufficiently energetic head-on collision (giant impact) between a large planetary embryo and the proto-Jupiter could have shattered its primordial compact core and mixed the heavy elements with the inner envelope. Models of such a scenario lead to an internal structure that is consistent with a diluted core, persisting over billions of years. We suggest that collisions were common in the young Solar system and thata similar event may have also occurred for Saturn, contributing to the structural differences between Jupiter and Saturn16-18.