Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of...Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of turbulences in the very early universe in sustaining intense and persistent fluctuations in energy or mass density,which could provide a natural mechanism for PBH formation in the primordial universe. We analyze the mass range and abundance of PBHs produced in the magnetohydrodynamic turbulence induced by the electroweak phase transition. Remarkably, we find that the mass range of the produced PBHs falls within the most viable“asteroid mass” window from the present-day observations, and within natural parameter regions their abundance can be sufficiently large. These findings suggest that PBHs produced during magnetohydrodynamic turbulence in the very early universe may comprise a dominant part of dark matter.展开更多
The cell fate of primordial germ cell(PGC)in zebrafish is pre-determined by maternally deposited germ plasm,which is packaged into ribonucleoprotein complex in oocytes and inherited into PGC-fated cells in embryos.How...The cell fate of primordial germ cell(PGC)in zebrafish is pre-determined by maternally deposited germ plasm,which is packaged into ribonucleoprotein complex in oocytes and inherited into PGC-fated cells in embryos.However,the maternal factors regulating the assembly of germ plasm and PGC development remain poorly understood.In this study,we report that the maternal transcription factor Znf706 regulates the assembly of germ plasm factors into a granule-like structure localized perinuclearly in PGC during migration.Maternal and zygotic mutants of znf706 exhibit deficient germ plasm scattering at the early embryonic stage,decreased PGC numbers with some mislocation during PGC migration,and a lower female ratio in adulthood.Notably,the implementation of Znf706 CUT&Tag and RNA-seq on immature oocytes uncovers that Znf706 in stage I oocytes may promote transcription of several mitochondrial genes in addition to other functions.Hence,we propose that Znf706 is implicated in germ plasm assembly and PGC development in zebrafish.展开更多
Primordial germ cells(PGCs),the precursors of oocytes and spermatozoa,are highly pluripotent.In recent years,the in vitro induction of human primordial germ cell-like cells(h PGCLCs)has advanced significantly.However,...Primordial germ cells(PGCs),the precursors of oocytes and spermatozoa,are highly pluripotent.In recent years,the in vitro induction of human primordial germ cell-like cells(h PGCLCs)has advanced significantly.However,the stability and efficacy of obtaining h PGCLCs in vitro still require improvement.In the current study,we identified a novel induction system using Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12(DMEM/F-12)as the basal medium,supplemented with B27 and N2(referred to as N2B27)in combination with four cytokines:bone morphogenetic protein 4,stem cell factor,epidermal growth factor,and leukemia inhibitory factor.The h PGCLCs induced under these conditions closely resembled PGCs from 4-to 5-week-old embryos at the transcriptomic level.Compared with traditional GK15(GMEM supplemented with 15%Knockout?Serum Replacement)-based induction conditions,the N2B27 system significantly increased the speed and efficacy of h PGCLC induction.RNA sequencing analysis revealed that this improvement was due to an increased cellular capacity to cope with hypoxic stress and avoid apoptosis.The N2B27 medium promoted enhanced mitochondrial activity,enabling cells to better manage hypoxic stress while reducing the production of reactive oxygen species.Moreover,through gradient concentration experiments,we demonstrated that the addition of the common antioxidant N-acetyl-L-cysteine at an optimized concentration further enhanced the efficiency of PGCLC induction under GK15 conditions.In summary,we have established an optimized induction system that enhances the efficiency of h PGCLC differentiation by improving cellular resilience to hypoxic stress and apoptosis.展开更多
[Objective] The paper was to establish embryonic stem cell system of goats. [Method] Numerous primordial germ cell colonies were derived from gonadal ridge and the surrounding tissues in 20 millimeter fetuses of down ...[Objective] The paper was to establish embryonic stem cell system of goats. [Method] Numerous primordial germ cell colonies were derived from gonadal ridge and the surrounding tissues in 20 millimeter fetuses of down producing goat. Primordial germ cells and goats embryonic fibroblasts obtained from conceptus of equivaient gestational age were co-cultured. [Result] The colonies showed some characteristics of embryonic stem cells, such as the morphology of nest-like, they continued to be AKP positive and the ability to be continuously passed [Conclusion] These cells were pluripotent and ES-like cells.展开更多
[Objective] The aim was to probe into developing changes of spontaneous electrical activities of primordial hippocampus in Bufo bufo gargarizans in postembryonic phase. [Method] Microelectrode technique was used to re...[Objective] The aim was to probe into developing changes of spontaneous electrical activities of primordial hippocampus in Bufo bufo gargarizans in postembryonic phase. [Method] Microelectrode technique was used to record extracellularly spontaneous electrical activities of neurons in primordial hippocampus of B.bufo gargarizans in postembryonic phase. [Result] Single, consecutive single, burst, consecutive burst and anomalous spontaneous firing were recorded in primordial hippocampus, in which four kinds of spontaneous firings were recorded in forepart of postembryonic development except the anomalous spontaneous firing, and the burst spontaneous firing and consecutive burst spontaneous firing were predominant. The five kinds of spontaneous firings mentioned were recorded in anaphase of postembryonic development and the single and burst spontaneous firing were predominant.Following with the development of primordial hippocampus, the amplitudes of action potential of single firing and consecutive firing enhanced gradually, and it reaches the maximum in the metamorphosis phase; the differences of the frequencies of consecutive single firing and consecutive burst firing were not significant. [Conclusion] Following with the development of primordial hippocampus, the neuronal electrical activities showed diversification, the developmental degree of the primordial hippocampus in the metamorphosis phase was close to the subadult and adult.展开更多
The clustered regularly interspaced short palindromic repeats(CRISPR)/Cas9 technology has been widely utilized for knocking out genes involved in various biological processes in zebrafish. Despite this technology is e...The clustered regularly interspaced short palindromic repeats(CRISPR)/Cas9 technology has been widely utilized for knocking out genes involved in various biological processes in zebrafish. Despite this technology is efficient for generating different mutations, one of the main drawbacks is low survival rate during embryogenesis when knocking out some embryonic lethal genes. To overcome this problem, we developed a novel strategy using a combination of CRISPR/Cas9 mediated gene knockout with primordial germ cell(PGC) transplantation(PGCT) to facilitate and speed up the process of zebrafish mutant generation, particularly for embryonic lethal genes. Firstly, we optimized the procedure for CRISPR/Cas9 targeted PGCT by increasing the efficiencies of genome mutation in PGCs and induction of PGC fates in donor embryos for PGCT. Secondly, the optimized CRISPR/Cas9 targeted PGCT was utilized for generation of maternal-zygotic(MZ) mutants of tcf7l1a(gene essential for head development), pou5f3(gene essential for zygotic genome activation) and chd(gene essential for dorsal development) at F1 generation with relatively high efficiency. Finally, we revealed some novel phenotypes in MZ mutants of tcf7l1 a and chd, as MZtcf7l1 a showed elevated neural crest development while MZchd had much severer ventralization than its zygotic counterparts. Therefore, this study presents an efficient and powerful method for generating MZ mutants of embryonic lethal genes in zebrafish. It is also feasible to speed up the genome editing in commercial fishes by utilizing a similar approach by surrogate production of CRISPR/Cas9 targeted germ cells.展开更多
Recent advances in avian transgenic studies highlight the possibility of utilizing lentiviral vectors as tools to generate transgenic chickens. However, low rates of gonadal chimerism and germ line transmission effici...Recent advances in avian transgenic studies highlight the possibility of utilizing lentiviral vectors as tools to generate transgenic chickens. However, low rates of gonadal chimerism and germ line transmission efficiency still limit the broad usage of this method in creating transgenic chickens. In this study, we implemented a simple strategy using modified lentiviral vectors targeted to chicken primordial germ cells(PGCs) to generate transgenic chickens. The lentiviral vectors were pseudotyped with a modified Sindbis virus envelope protein(termed M168) and conjugated with an antibody specific to PGC membrane proteins. We demonstrated that these optimized M168-pseudotyped lentiviral vectors conjugated with SSEA4 antibodies successfully targeted transduction of PGCs in vitro and in vivo. Compared with the control, 50.0%–66.7% of chicken embryos expressed green fluorescent protein(GFP) in gonads transduced by the M168-pseudotyped lentivirus. This improved the targeted transduction efficiency by 30.0%–46.7%. Efficient chimerism of exogenous genes was also observed. This targeting technology could improve the efficiency of germ line transmission and provide greater opportunities for transgenic poultry studies.展开更多
Background:NANOG is a core transcription factor(TF)in embryonic stem cells(ESCs)and primordial germ cells(PGCs).Regulation of the NANOG gene by TFs,epigenetic factors,and autoregulatory factors is well characterized i...Background:NANOG is a core transcription factor(TF)in embryonic stem cells(ESCs)and primordial germ cells(PGCs).Regulation of the NANOG gene by TFs,epigenetic factors,and autoregulatory factors is well characterized in ESCs,and transcriptional regulation of NANOG is well established in these cells.Although NANOG plays a key role in germ cells,the molecular mechanism underlying its transcriptional regulation in PGCs has not been studied.Therefore,we investigated the mechanism that regulates transcription of the chicken NANOG(cNANOG)gene in PGCs and ESCs.Results:We first identified the transcription start site of cNANOG by 5′-rapid amplification of cDNA ends PCR analysis.Then,we measured the promoter activity of various 5′flanking regions of cNANOG in chicken PGCs and ESCs using the luciferase reporter assay.cNANOG expression required transcriptional regulatory elements,which were positively regulated by POU5F3(OCT4)and SOX2 and negatively regulated by TP53 in PGCs.The proximal region of the cNANOG promoter contains a positive transcriptional regulatory element(CCAAT/enhancer-binding protein(CEBP)-binding site)in ESCs.Furthermore,small interfering RNA-mediated knockdown demonstrated that POU5F3,SOX2,and CEBP played a role in cell type-specific transcription of cNANOG.Conclusions:We show for the first time that different trans-regulatory elements control transcription of cNANOG in a cell type-specific manner.This finding might help to elucidate the mechanism that regulates cNANOG expression in PGCs and ESCs.展开更多
Transgenesis and genome editing in birds are based on a unique germline transmission system using primordial germ cells(PGCs), which is quite different from the mammalian transgenic and genome editing system. PGCs are...Transgenesis and genome editing in birds are based on a unique germline transmission system using primordial germ cells(PGCs), which is quite different from the mammalian transgenic and genome editing system. PGCs are progenitor cells of gametes that can deliver genetic information to the next generation. Since avian PGCs were first discovered in nineteenth century, there have been numerous efforts to reveal their origin, specification, and unique migration pattern, and to improve germline transmission efficiency. Recent advances in the isolation and in vitro culture of avian PGCs with genetic manipulation and genome editing tools enable the development of valuable avian models that were unavailable before. However, many challenges remain in the production of transgenic and genome-edited birds,including the precise control of germline transmission, introduction of exogenous genes, and genome editing in PGCs.Therefore, establishing reliable germline-competent PGCs and applying precise genome editing systems are critical current issues in the production of avian models. Here, we introduce a historical overview of avian PGCs and their application, including improved techniques and methodologies in the production of transgenic and genome-edited birds, and we discuss the future potential applications of transgenic and genome-edited birds to provide opportunities and benefits for humans.展开更多
There is growing evidence that cellular metabolism can directly participate in epigenetic dynamics and consequently modulate gene expression.However,the role of metabolites in activating the key gene regulatory networ...There is growing evidence that cellular metabolism can directly participate in epigenetic dynamics and consequently modulate gene expression.However,the role of metabolites in activating the key gene regulatory network for specialization of germ cell lineage remains largely unknown.Here,we identified some cellular metabolites with significant changes by untargeted metabolomics between mouse epiblast-like cells(EpiLCs)and primordial germ cell-like cells(PGCLCs).More importantly,we found that inhibition of glutaminolysis by bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide(BPTES)impeded PGCLC specialization,but the impediment could be rescued by addition ofα-ketoglutarate(αKG),the intermediate metabolite of oxidative phosphorylation and glutaminolysis.Moreover,adding aKG alone to the PGCLC medium accelerated the PGCLC specialization through promoting H3 K27 me3 demethylation.Thus,our study reveals the importance of metabolite aKG in the germ cell fate determination and highlights the essential role of cellular metabolism in shaping the cell identities through epigenetic events.展开更多
Aim： To assess whether exogenous estradiol has any effect on migration of primordial germ cells （PGCs） in the chick. Methods： Fertilized eggs were treated with 17beta-estradiol （E2） （80 lag/egg） at stage X （d...Aim： To assess whether exogenous estradiol has any effect on migration of primordial germ cells （PGCs） in the chick. Methods： Fertilized eggs were treated with 17beta-estradiol （E2） （80 lag/egg） at stage X （day 0 of incubation）, stages 8-10 （incubation 30 h） and 13-15 （incubation 55 h）. Controls received vehicle （emulsion） only. Changes in PGC number were measured on different days according to developmental stages. Results： In male right gonads, but not in female left gonads, at stages 28-30 （incubation 132 h） significant decreases in the mean number of PGCs aggregating were observed compared with the controls （P 〈 0.05） while the total PGC number in the right and left gonads at each stage did not change （P 〉 0.05）. Conclusion： The present study provides evidence that E2 has significant effects on the localization of PGCs in male right, but not female left, gonads of chicken embryos at stages 28-30, compared with controls. （Asian J Andro12008 Mar; 10： 243-248）展开更多
The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s s...The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.展开更多
The Hadean history of Earth is shrouded in mystery and it is considered that the planet was born dry with no water or atmosphere.The Earth-Moon system had many features in common during the birth stage.Solidification ...The Hadean history of Earth is shrouded in mystery and it is considered that the planet was born dry with no water or atmosphere.The Earth-Moon system had many features in common during the birth stage.Solidification of the dry magma ocean at 4.53 Ga generated primordial continents with komatiite.We speculate that the upper crust was composed of fractionated gabbros and the middle felsic crust by anorthosite at ca.21 km depth boundary,underlain by meta-anorthosite（grossular ＋ kyanite 4 quartz）down to 50-60 km in depth.The thickness of the mafic KREEP basalt in the lower crust,separating it from the underlying upper mantle is not well-constrained and might have been up to ca.100-200 km depending on the degree of fractionation and gravitational stability versus surrounding mantle density.The primordial continents must have been composed of the final residue of dry magma ocean and enriched in several critical elements including Ca,Mg,Fe,Mn,P,K,and Cl which were exposed on the surface of the dry Earth.Around 190 million years after the solidification of the magma ocean, ＂ABEL bombardment＂ delivered volatiles including H_2O,CO_2,N_2 as well as silicate components through the addition of icy asteroids.This event continued for 200 Myr with subordinate bombardments until 3.9 Ga,preparing the Earth for the prebiotic chemical evolution and as the cradle of first life.Due to vigorous convection arising from high mantle potential temperatures,the primordial continents disintegrated and were dragged down to the deep mantle,marking the onset of Hadean plate tectonics.展开更多
The Standard Model of Particle Physics treats four fields—the gravitational, electromagnetic, weak and strong fields. These fields are assumed to converge to a single field at the big bang, but the theory has failed ...The Standard Model of Particle Physics treats four fields—the gravitational, electromagnetic, weak and strong fields. These fields are assumed to converge to a single field at the big bang, but the theory has failed to produce this convergence. Our theory proposes<em> one </em>primordial field and analyzes the evolution of this field. The key assumption is that <em>only</em> the primordial field exists—if any change is to occur, it must be based upon self-interaction, as there is nothing other than the field itself to interact with. This can be formalized as the <em>Principle</em> <em>of </em><em>Self-interaction</em> and the consequences explored. I show that this leads to the linearized Einstein field equations and discuss the key ontological implications of the theory.展开更多
The history of the early Earth is shrouded in mystery, and one of the major outcomes of the Apollo Program, lunar sampling, and the data acquired by subsequent orbiting missions, is that the Moon is an important analo...The history of the early Earth is shrouded in mystery, and one of the major outcomes of the Apollo Program, lunar sampling, and the data acquired by subsequent orbiting missions, is that the Moon is an important analogue for the Hadean Earth, which includes primordial planet-forming materials. We assemble two special issues of ＂Geoscience Frontiers＂ with state-of-the-art contributions that provide insights into planetary formation, Earth＇s early history and primordial life. New theories show why the Earth began as a dry planetary system and was later seeded by an ocean-atmosphere system through the bombardment of carbonaceous chondrites. A combination of the information concerning the evolution of Earth, Mars, and the other terrestrial planets is important in understanding the fate of the primordial continental crustal materials and the making of habitable planets.展开更多
Background： Primordial germ cells（PGCs）, the precursors of functional gametes, have distinct characteristics and exhibit several unique molecular mechanisms to maintain pluripotency and germness in comparison to so...Background： Primordial germ cells（PGCs）, the precursors of functional gametes, have distinct characteristics and exhibit several unique molecular mechanisms to maintain pluripotency and germness in comparison to somatic cells. They express germ cel-specific RNA binding proteins（RBPs） by modulating tissue-specific cis-and trans-regulatory elements. Studies on gene structures of chicken vasa homologue（CVH）, a chicken RNA binding protein, involved in temporal and spatial regulation are thus important not only for understanding the molecular mechanisms that regulate germ cel fate, but also for practical applications of primordial germ cells. However, very limited studies are available on regulatory elements that control germ cel-specific expression in chicken. Therefore, we investigated the intricate regulatory mechanism（s） that governs transcriptional control of CVH.Results： We constructed green fluorescence protein（GFP） or luciferase reporter vectors containing the various 5′ flanking regions of CVH gene. From the 5′ deletion and fragmented assays in chicken PGCs, we have identified a CVH promoter that locates at-316 to ＋275 base pair fragment with the highest luciferase activity. Additional y, we confirmed for the first time that the 5′ untranslated region（UTR） containing intron 1 is required for promoter activity of the CVH gene in chicken PGCs. Furthermore, using a transcription factor binding prediction, transcriptome analysis and siR NA-mediated knockdown,we have identified that a set of transcription factors play a role in the PGC-specific CVH gene expression.Conclusions： These results demonstrate that cis-elements and transcription factors localizing in the 5′ flanking region including the 5′ UTR and an intron are important for transcriptional regulation of the CVH gene in chicken PGCs. Final y,this information wil contribute to research studies in areas of reproductive biology, constructing of germ cel-specific synthetic promoter for tracing primordial germ cells as wel as understanding the transcriptional regulation for maintaining germness in PGCs.展开更多
We use the wide-used Einstein Toolkit to solve the Einstein constraints and then simulate the expansion of primordial black hole lattices(PBHLs) with different value of f PBH and m PBH. We find that f PBH plays an imp...We use the wide-used Einstein Toolkit to solve the Einstein constraints and then simulate the expansion of primordial black hole lattices(PBHLs) with different value of f PBH and m PBH. We find that f PBH plays an important role during the evolution of PBHLs. Since the motion of primordial black holes(PBHs) caused by the expansion of PBHLs occurs at speeds close to that of light, we expect the emission of gravitational waves(GWs) during the expansion of PBHLs. We use both analytical estimates and numerical simulations to cross check the production of GWs in expanding PBHLs.展开更多
Developmental potency of primitive and embryonic ectoderm cells from 4.50-day to 6.25-day post-coitum (p.c.) mouse embryos and primordial germ cells from 12.50-day p.c.male genital ridges of fetal mice were studied by...Developmental potency of primitive and embryonic ectoderm cells from 4.50-day to 6.25-day post-coitum (p.c.) mouse embryos and primordial germ cells from 12.50-day p.c.male genital ridges of fetal mice were studied by direct introducing them into 3.50-day p.c.blastocysts.Sixteen (61.5) overt chimaeras out of 26(50%) offsprings were obtained after transfer of 52 blastocysts injected with 4.50-day primitive ectoderm cells;four (16.0%) overt chimaeras were obtained out of 25 (51.0%) offsprings with 4.75-day primitive ectoderm cells from 49 transferred blastocysts.However,no overt chimaera was obtained with either 5.25-day or 6.25-day embryonic ectoderm cells or 12.50-day male primordial germ cells.GPI analysis of mid-gestation conceptuses developed from injected blastocysts showedthat 5.25-day embryonic ectoderm cells could only contributed to yolk sac of conceptus.Results suggested that implantation acts as a trigger for the determination of primitive ectoderm cells,and their developmental potency becomes limited within a short period of time in normal development.展开更多
Mineralogy of the Lunar surface provides important clues for understanding the composition and evo- lution of the primordial crust in the Earth-Moon system. The primary rock forming minerals on the Moon such as pyroxe...Mineralogy of the Lunar surface provides important clues for understanding the composition and evo- lution of the primordial crust in the Earth-Moon system. The primary rock forming minerals on the Moon such as pyroxene, olivine and plagioclase are potential tools to evaluate the Lunar Magma Ocean （LMO） hypothesis. Here we use the data from Moon Mineralogy Mapper （M3） onboard the Chandrayaan- 1 project of India, which provides Visible/Near Infra Red （NIR） spectral data （hyperspectral data） of the Lunar surface to gain insights on the surface mineralogy. Band shaping and spectral profiling methods are used for identifying minerals in five sites： the Moscoviense basin, Orientale basin, Apollo basin, Wegener crater-highland, and Hertzsprung basin. The common presence of plagioclase in these sites is in conformity with the anorthositic composition of the Lunar crust. Pyroxenes, olivine and Fe-Mg-spinel from the sample sites indicate the presence of gabbroic and basaltic components. The compositional difference in pyroxenes suggests magmatic differentiation on the Lunar surface. Olivine contains OH/H20 band, indicating hydrous phase in the primordial magmas.展开更多
Recently torsion fields were introduced in CP-violating cosmic axion a2-dynamos [Garcia de Andrade, Mod Phys Lett A, (2011)] in order to obtain Lorentz violating bounds for torsion. Here instead, oscillating axion sol...Recently torsion fields were introduced in CP-violating cosmic axion a2-dynamos [Garcia de Andrade, Mod Phys Lett A, (2011)] in order to obtain Lorentz violating bounds for torsion. Here instead, oscillating axion solutions of the dynamo equation with torsion modes [Garcia de Andrade, Phys Lett B (2012)] are obtained taking into account dissipative torsion fields. Magnetic helicity torsion oscillatory contribution is also obtained. Note that the torsion presence guarantees dynamo efficiency when axion dynamo length is much stronger than the torsion length. Primordial axion oscillations due to torsion yield a magnetic field of 109 G at Nucleosynthesis epoch. This is obtained due to a decay of BBN magnetic field of 1015 G induced by torsion. Since torsion is taken as 10–20 s–1, the dynamo efficiency is granted over torsion damping. Of course dynamo efficiency is better in the absence of torsion. In the particular case when the torsion is obtained from anomalies it is given by the gradient of axion scalar [Duncan et al., Nuclear Phys B 87, 215] that a simpler dynamo equation is obtained and dynamo mechanism seems to be efficient when the torsion helicity, is negative while magnetic field decays when the torsion is positive. In this case an extremely huge value for the magnetic field of 1015 Gauss is obtained. This is one order of magnitude greater than the primordial magnetic fields of the domain wall. Actually if one uses tDW ~ 10-4 s one obtains BDW ~ 1022 G which is a more stringent limit to the DW magnetic primordial field.展开更多
基金supported by the International Partnership Program of the Chinese Academy of Sciences (Grant No.025GJHZ2023106GC)。
文摘Primordial black holes(PBHs) offer a compelling candidate for dark matter. The production of PBHs through well-tested and accepted physical processes is highly worthy of investigation. This work highlights the role of turbulences in the very early universe in sustaining intense and persistent fluctuations in energy or mass density,which could provide a natural mechanism for PBH formation in the primordial universe. We analyze the mass range and abundance of PBHs produced in the magnetohydrodynamic turbulence induced by the electroweak phase transition. Remarkably, we find that the mass range of the produced PBHs falls within the most viable“asteroid mass” window from the present-day observations, and within natural parameter regions their abundance can be sufficiently large. These findings suggest that PBHs produced during magnetohydrodynamic turbulence in the very early universe may comprise a dominant part of dark matter.
基金supported by the National Natural Science Foundation of China(31988101 to A.M.)the National Key Research and Development Program of China(2023YFA1800300 to X.W.and 2018YFC1003304 to A.M.)the Yunnan Provincial Science and Technology Project at Southwest United Graduate School(202302A0370011 to A.M.).
文摘The cell fate of primordial germ cell(PGC)in zebrafish is pre-determined by maternally deposited germ plasm,which is packaged into ribonucleoprotein complex in oocytes and inherited into PGC-fated cells in embryos.However,the maternal factors regulating the assembly of germ plasm and PGC development remain poorly understood.In this study,we report that the maternal transcription factor Znf706 regulates the assembly of germ plasm factors into a granule-like structure localized perinuclearly in PGC during migration.Maternal and zygotic mutants of znf706 exhibit deficient germ plasm scattering at the early embryonic stage,decreased PGC numbers with some mislocation during PGC migration,and a lower female ratio in adulthood.Notably,the implementation of Znf706 CUT&Tag and RNA-seq on immature oocytes uncovers that Znf706 in stage I oocytes may promote transcription of several mitochondrial genes in addition to other functions.Hence,we propose that Znf706 is implicated in germ plasm assembly and PGC development in zebrafish.
基金funded by the National Key R&D Program(Grant Nos.2022YFC2702800 and 2021YFC2700302 to Y.Y.)the National Natural Science Foundation of China(Grant Nos.82122025 to Y.Y.,82221005 to J.S.,and 82201763 to L.L.)。
文摘Primordial germ cells(PGCs),the precursors of oocytes and spermatozoa,are highly pluripotent.In recent years,the in vitro induction of human primordial germ cell-like cells(h PGCLCs)has advanced significantly.However,the stability and efficacy of obtaining h PGCLCs in vitro still require improvement.In the current study,we identified a novel induction system using Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12(DMEM/F-12)as the basal medium,supplemented with B27 and N2(referred to as N2B27)in combination with four cytokines:bone morphogenetic protein 4,stem cell factor,epidermal growth factor,and leukemia inhibitory factor.The h PGCLCs induced under these conditions closely resembled PGCs from 4-to 5-week-old embryos at the transcriptomic level.Compared with traditional GK15(GMEM supplemented with 15%Knockout?Serum Replacement)-based induction conditions,the N2B27 system significantly increased the speed and efficacy of h PGCLC induction.RNA sequencing analysis revealed that this improvement was due to an increased cellular capacity to cope with hypoxic stress and avoid apoptosis.The N2B27 medium promoted enhanced mitochondrial activity,enabling cells to better manage hypoxic stress while reducing the production of reactive oxygen species.Moreover,through gradient concentration experiments,we demonstrated that the addition of the common antioxidant N-acetyl-L-cysteine at an optimized concentration further enhanced the efficiency of PGCLC induction under GK15 conditions.In summary,we have established an optimized induction system that enhances the efficiency of h PGCLC differentiation by improving cellular resilience to hypoxic stress and apoptosis.
基金Supported by Project of Baotou University(BSY2010-23)~~
文摘[Objective] The paper was to establish embryonic stem cell system of goats. [Method] Numerous primordial germ cell colonies were derived from gonadal ridge and the surrounding tissues in 20 millimeter fetuses of down producing goat. Primordial germ cells and goats embryonic fibroblasts obtained from conceptus of equivaient gestational age were co-cultured. [Result] The colonies showed some characteristics of embryonic stem cells, such as the morphology of nest-like, they continued to be AKP positive and the ability to be continuously passed [Conclusion] These cells were pluripotent and ES-like cells.
基金Supported by grants from the Liaoning Provincial Department of Education(2011196)~~
文摘[Objective] The aim was to probe into developing changes of spontaneous electrical activities of primordial hippocampus in Bufo bufo gargarizans in postembryonic phase. [Method] Microelectrode technique was used to record extracellularly spontaneous electrical activities of neurons in primordial hippocampus of B.bufo gargarizans in postembryonic phase. [Result] Single, consecutive single, burst, consecutive burst and anomalous spontaneous firing were recorded in primordial hippocampus, in which four kinds of spontaneous firings were recorded in forepart of postembryonic development except the anomalous spontaneous firing, and the burst spontaneous firing and consecutive burst spontaneous firing were predominant. The five kinds of spontaneous firings mentioned were recorded in anaphase of postembryonic development and the single and burst spontaneous firing were predominant.Following with the development of primordial hippocampus, the amplitudes of action potential of single firing and consecutive firing enhanced gradually, and it reaches the maximum in the metamorphosis phase; the differences of the frequencies of consecutive single firing and consecutive burst firing were not significant. [Conclusion] Following with the development of primordial hippocampus, the neuronal electrical activities showed diversification, the developmental degree of the primordial hippocampus in the metamorphosis phase was close to the subadult and adult.
基金supported by the National Key R&D Project of China (2018YFA0801000 and 2018YFD0901205)National Natural Science Foundation of China (Nos. 31721005, 31671501 and 31222052)+1 种基金the Youth Innovation Association of CASthe State Key Laboratory of Freshwater Ecology and Biotechnology (No. 2019FBZ05).
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)/Cas9 technology has been widely utilized for knocking out genes involved in various biological processes in zebrafish. Despite this technology is efficient for generating different mutations, one of the main drawbacks is low survival rate during embryogenesis when knocking out some embryonic lethal genes. To overcome this problem, we developed a novel strategy using a combination of CRISPR/Cas9 mediated gene knockout with primordial germ cell(PGC) transplantation(PGCT) to facilitate and speed up the process of zebrafish mutant generation, particularly for embryonic lethal genes. Firstly, we optimized the procedure for CRISPR/Cas9 targeted PGCT by increasing the efficiencies of genome mutation in PGCs and induction of PGC fates in donor embryos for PGCT. Secondly, the optimized CRISPR/Cas9 targeted PGCT was utilized for generation of maternal-zygotic(MZ) mutants of tcf7l1a(gene essential for head development), pou5f3(gene essential for zygotic genome activation) and chd(gene essential for dorsal development) at F1 generation with relatively high efficiency. Finally, we revealed some novel phenotypes in MZ mutants of tcf7l1 a and chd, as MZtcf7l1 a showed elevated neural crest development while MZchd had much severer ventralization than its zygotic counterparts. Therefore, this study presents an efficient and powerful method for generating MZ mutants of embryonic lethal genes in zebrafish. It is also feasible to speed up the genome editing in commercial fishes by utilizing a similar approach by surrogate production of CRISPR/Cas9 targeted germ cells.
基金the National Transgenic Breeding Project of China(2016ZX08009003006)National Natural Science Foundation of China(31672411)Discipline Innovative Engineering Plan(B12008)。
文摘Recent advances in avian transgenic studies highlight the possibility of utilizing lentiviral vectors as tools to generate transgenic chickens. However, low rates of gonadal chimerism and germ line transmission efficiency still limit the broad usage of this method in creating transgenic chickens. In this study, we implemented a simple strategy using modified lentiviral vectors targeted to chicken primordial germ cells(PGCs) to generate transgenic chickens. The lentiviral vectors were pseudotyped with a modified Sindbis virus envelope protein(termed M168) and conjugated with an antibody specific to PGC membrane proteins. We demonstrated that these optimized M168-pseudotyped lentiviral vectors conjugated with SSEA4 antibodies successfully targeted transduction of PGCs in vitro and in vivo. Compared with the control, 50.0%–66.7% of chicken embryos expressed green fluorescent protein(GFP) in gonads transduced by the M168-pseudotyped lentivirus. This improved the targeted transduction efficiency by 30.0%–46.7%. Efficient chimerism of exogenous genes was also observed. This targeting technology could improve the efficiency of germ line transmission and provide greater opportunities for transgenic poultry studies.
基金This work was supported by a National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)[2015R1A3A2033826]and[2018R1D1A1B07049376].
文摘Background:NANOG is a core transcription factor(TF)in embryonic stem cells(ESCs)and primordial germ cells(PGCs).Regulation of the NANOG gene by TFs,epigenetic factors,and autoregulatory factors is well characterized in ESCs,and transcriptional regulation of NANOG is well established in these cells.Although NANOG plays a key role in germ cells,the molecular mechanism underlying its transcriptional regulation in PGCs has not been studied.Therefore,we investigated the mechanism that regulates transcription of the chicken NANOG(cNANOG)gene in PGCs and ESCs.Results:We first identified the transcription start site of cNANOG by 5′-rapid amplification of cDNA ends PCR analysis.Then,we measured the promoter activity of various 5′flanking regions of cNANOG in chicken PGCs and ESCs using the luciferase reporter assay.cNANOG expression required transcriptional regulatory elements,which were positively regulated by POU5F3(OCT4)and SOX2 and negatively regulated by TP53 in PGCs.The proximal region of the cNANOG promoter contains a positive transcriptional regulatory element(CCAAT/enhancer-binding protein(CEBP)-binding site)in ESCs.Furthermore,small interfering RNA-mediated knockdown demonstrated that POU5F3,SOX2,and CEBP played a role in cell type-specific transcription of cNANOG.Conclusions:We show for the first time that different trans-regulatory elements control transcription of cNANOG in a cell type-specific manner.This finding might help to elucidate the mechanism that regulates cNANOG expression in PGCs and ESCs.
基金supported by a National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP)(No.2015R1A3A2033826)
文摘Transgenesis and genome editing in birds are based on a unique germline transmission system using primordial germ cells(PGCs), which is quite different from the mammalian transgenic and genome editing system. PGCs are progenitor cells of gametes that can deliver genetic information to the next generation. Since avian PGCs were first discovered in nineteenth century, there have been numerous efforts to reveal their origin, specification, and unique migration pattern, and to improve germline transmission efficiency. Recent advances in the isolation and in vitro culture of avian PGCs with genetic manipulation and genome editing tools enable the development of valuable avian models that were unavailable before. However, many challenges remain in the production of transgenic and genome-edited birds,including the precise control of germline transmission, introduction of exogenous genes, and genome editing in PGCs.Therefore, establishing reliable germline-competent PGCs and applying precise genome editing systems are critical current issues in the production of avian models. Here, we introduce a historical overview of avian PGCs and their application, including improved techniques and methodologies in the production of transgenic and genome-edited birds, and we discuss the future potential applications of transgenic and genome-edited birds to provide opportunities and benefits for humans.
基金supported by grants from the National Natural Science Foundation of China(No.31871445 and No.31501211)the National Key R&D program of China(No.2017YFC1001302 and No.2016YFA0503300)。
文摘There is growing evidence that cellular metabolism can directly participate in epigenetic dynamics and consequently modulate gene expression.However,the role of metabolites in activating the key gene regulatory network for specialization of germ cell lineage remains largely unknown.Here,we identified some cellular metabolites with significant changes by untargeted metabolomics between mouse epiblast-like cells(EpiLCs)and primordial germ cell-like cells(PGCLCs).More importantly,we found that inhibition of glutaminolysis by bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide(BPTES)impeded PGCLC specialization,but the impediment could be rescued by addition ofα-ketoglutarate(αKG),the intermediate metabolite of oxidative phosphorylation and glutaminolysis.Moreover,adding aKG alone to the PGCLC medium accelerated the PGCLC specialization through promoting H3 K27 me3 demethylation.Thus,our study reveals the importance of metabolite aKG in the germ cell fate determination and highlights the essential role of cellular metabolism in shaping the cell identities through epigenetic events.
基金Acknowledgment This work was supported by the National Natural Science Foundation of China （No. 30270648 and No. 30500270）, Zhejiang Province Scientific and Technological Project （No. 2005C22052） and Zhejiang Province Science Foundation （No. Y304194）. We thank Dr Ji- Min Zhang of the University of California for linguistic revision of the manuscript.
文摘Aim： To assess whether exogenous estradiol has any effect on migration of primordial germ cells （PGCs） in the chick. Methods： Fertilized eggs were treated with 17beta-estradiol （E2） （80 lag/egg） at stage X （day 0 of incubation）, stages 8-10 （incubation 30 h） and 13-15 （incubation 55 h）. Controls received vehicle （emulsion） only. Changes in PGC number were measured on different days according to developmental stages. Results： In male right gonads, but not in female left gonads, at stages 28-30 （incubation 132 h） significant decreases in the mean number of PGCs aggregating were observed compared with the controls （P 〈 0.05） while the total PGC number in the right and left gonads at each stage did not change （P 〉 0.05）. Conclusion： The present study provides evidence that E2 has significant effects on the localization of PGCs in male right, but not female left, gonads of chicken embryos at stages 28-30, compared with controls. （Asian J Andro12008 Mar; 10： 243-248）
基金supported partly by KAKENHI 26800237 and 26287105
文摘The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.
基金supported by Foreign Expert Funding from China University of Geosciences Beijing
文摘The Hadean history of Earth is shrouded in mystery and it is considered that the planet was born dry with no water or atmosphere.The Earth-Moon system had many features in common during the birth stage.Solidification of the dry magma ocean at 4.53 Ga generated primordial continents with komatiite.We speculate that the upper crust was composed of fractionated gabbros and the middle felsic crust by anorthosite at ca.21 km depth boundary,underlain by meta-anorthosite（grossular ＋ kyanite 4 quartz）down to 50-60 km in depth.The thickness of the mafic KREEP basalt in the lower crust,separating it from the underlying upper mantle is not well-constrained and might have been up to ca.100-200 km depending on the degree of fractionation and gravitational stability versus surrounding mantle density.The primordial continents must have been composed of the final residue of dry magma ocean and enriched in several critical elements including Ca,Mg,Fe,Mn,P,K,and Cl which were exposed on the surface of the dry Earth.Around 190 million years after the solidification of the magma ocean, ＂ABEL bombardment＂ delivered volatiles including H_2O,CO_2,N_2 as well as silicate components through the addition of icy asteroids.This event continued for 200 Myr with subordinate bombardments until 3.9 Ga,preparing the Earth for the prebiotic chemical evolution and as the cradle of first life.Due to vigorous convection arising from high mantle potential temperatures,the primordial continents disintegrated and were dragged down to the deep mantle,marking the onset of Hadean plate tectonics.
文摘The Standard Model of Particle Physics treats four fields—the gravitational, electromagnetic, weak and strong fields. These fields are assumed to converge to a single field at the big bang, but the theory has failed to produce this convergence. Our theory proposes<em> one </em>primordial field and analyzes the evolution of this field. The key assumption is that <em>only</em> the primordial field exists—if any change is to occur, it must be based upon self-interaction, as there is nothing other than the field itself to interact with. This can be formalized as the <em>Principle</em> <em>of </em><em>Self-interaction</em> and the consequences explored. I show that this leads to the linearized Einstein field equations and discuss the key ontological implications of the theory.
文摘The history of the early Earth is shrouded in mystery, and one of the major outcomes of the Apollo Program, lunar sampling, and the data acquired by subsequent orbiting missions, is that the Moon is an important analogue for the Hadean Earth, which includes primordial planet-forming materials. We assemble two special issues of ＂Geoscience Frontiers＂ with state-of-the-art contributions that provide insights into planetary formation, Earth＇s early history and primordial life. New theories show why the Earth began as a dry planetary system and was later seeded by an ocean-atmosphere system through the bombardment of carbonaceous chondrites. A combination of the information concerning the evolution of Earth, Mars, and the other terrestrial planets is important in understanding the fate of the primordial continental crustal materials and the making of habitable planets.
基金supported by a National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP)(No.2015R1A3A2033826)
文摘Background： Primordial germ cells（PGCs）, the precursors of functional gametes, have distinct characteristics and exhibit several unique molecular mechanisms to maintain pluripotency and germness in comparison to somatic cells. They express germ cel-specific RNA binding proteins（RBPs） by modulating tissue-specific cis-and trans-regulatory elements. Studies on gene structures of chicken vasa homologue（CVH）, a chicken RNA binding protein, involved in temporal and spatial regulation are thus important not only for understanding the molecular mechanisms that regulate germ cel fate, but also for practical applications of primordial germ cells. However, very limited studies are available on regulatory elements that control germ cel-specific expression in chicken. Therefore, we investigated the intricate regulatory mechanism（s） that governs transcriptional control of CVH.Results： We constructed green fluorescence protein（GFP） or luciferase reporter vectors containing the various 5′ flanking regions of CVH gene. From the 5′ deletion and fragmented assays in chicken PGCs, we have identified a CVH promoter that locates at-316 to ＋275 base pair fragment with the highest luciferase activity. Additional y, we confirmed for the first time that the 5′ untranslated region（UTR） containing intron 1 is required for promoter activity of the CVH gene in chicken PGCs. Furthermore, using a transcription factor binding prediction, transcriptome analysis and siR NA-mediated knockdown,we have identified that a set of transcription factors play a role in the PGC-specific CVH gene expression.Conclusions： These results demonstrate that cis-elements and transcription factors localizing in the 5′ flanking region including the 5′ UTR and an intron are important for transcriptional regulation of the CVH gene in chicken PGCs. Final y,this information wil contribute to research studies in areas of reproductive biology, constructing of germ cel-specific synthetic promoter for tracing primordial germ cells as wel as understanding the transcriptional regulation for maintaining germness in PGCs.
基金Supported by the National Natural Science Foundation of China under Grant No.11690024the Strategic Priority Program of the Chinese Academy of Sciences under Grant No.XDB 23040100
文摘We use the wide-used Einstein Toolkit to solve the Einstein constraints and then simulate the expansion of primordial black hole lattices(PBHLs) with different value of f PBH and m PBH. We find that f PBH plays an important role during the evolution of PBHLs. Since the motion of primordial black holes(PBHs) caused by the expansion of PBHLs occurs at speeds close to that of light, we expect the emission of gravitational waves(GWs) during the expansion of PBHLs. We use both analytical estimates and numerical simulations to cross check the production of GWs in expanding PBHLs.
文摘Developmental potency of primitive and embryonic ectoderm cells from 4.50-day to 6.25-day post-coitum (p.c.) mouse embryos and primordial germ cells from 12.50-day p.c.male genital ridges of fetal mice were studied by direct introducing them into 3.50-day p.c.blastocysts.Sixteen (61.5) overt chimaeras out of 26(50%) offsprings were obtained after transfer of 52 blastocysts injected with 4.50-day primitive ectoderm cells;four (16.0%) overt chimaeras were obtained out of 25 (51.0%) offsprings with 4.75-day primitive ectoderm cells from 49 transferred blastocysts.However,no overt chimaera was obtained with either 5.25-day or 6.25-day embryonic ectoderm cells or 12.50-day male primordial germ cells.GPI analysis of mid-gestation conceptuses developed from injected blastocysts showedthat 5.25-day embryonic ectoderm cells could only contributed to yolk sac of conceptus.Results suggested that implantation acts as a trigger for the determination of primitive ectoderm cells,and their developmental potency becomes limited within a short period of time in normal development.
文摘Mineralogy of the Lunar surface provides important clues for understanding the composition and evo- lution of the primordial crust in the Earth-Moon system. The primary rock forming minerals on the Moon such as pyroxene, olivine and plagioclase are potential tools to evaluate the Lunar Magma Ocean （LMO） hypothesis. Here we use the data from Moon Mineralogy Mapper （M3） onboard the Chandrayaan- 1 project of India, which provides Visible/Near Infra Red （NIR） spectral data （hyperspectral data） of the Lunar surface to gain insights on the surface mineralogy. Band shaping and spectral profiling methods are used for identifying minerals in five sites： the Moscoviense basin, Orientale basin, Apollo basin, Wegener crater-highland, and Hertzsprung basin. The common presence of plagioclase in these sites is in conformity with the anorthositic composition of the Lunar crust. Pyroxenes, olivine and Fe-Mg-spinel from the sample sites indicate the presence of gabbroic and basaltic components. The compositional difference in pyroxenes suggests magmatic differentiation on the Lunar surface. Olivine contains OH/H20 band, indicating hydrous phase in the primordial magmas.
文摘Recently torsion fields were introduced in CP-violating cosmic axion a2-dynamos [Garcia de Andrade, Mod Phys Lett A, (2011)] in order to obtain Lorentz violating bounds for torsion. Here instead, oscillating axion solutions of the dynamo equation with torsion modes [Garcia de Andrade, Phys Lett B (2012)] are obtained taking into account dissipative torsion fields. Magnetic helicity torsion oscillatory contribution is also obtained. Note that the torsion presence guarantees dynamo efficiency when axion dynamo length is much stronger than the torsion length. Primordial axion oscillations due to torsion yield a magnetic field of 109 G at Nucleosynthesis epoch. This is obtained due to a decay of BBN magnetic field of 1015 G induced by torsion. Since torsion is taken as 10–20 s–1, the dynamo efficiency is granted over torsion damping. Of course dynamo efficiency is better in the absence of torsion. In the particular case when the torsion is obtained from anomalies it is given by the gradient of axion scalar [Duncan et al., Nuclear Phys B 87, 215] that a simpler dynamo equation is obtained and dynamo mechanism seems to be efficient when the torsion helicity, is negative while magnetic field decays when the torsion is positive. In this case an extremely huge value for the magnetic field of 1015 Gauss is obtained. This is one order of magnitude greater than the primordial magnetic fields of the domain wall. Actually if one uses tDW ~ 10-4 s one obtains BDW ~ 1022 G which is a more stringent limit to the DW magnetic primordial field.
