Isotope Labeling Research Articles

Exploiting 19F NMR in a Multiplexed Assay for Small GTPase Activity.

Small GTPases (smG) are a 150-member family of proteins, comprising five subfamilies: Ras, Rho, Arf, Rab, and Ran-GTPases. These proteins function as molecular switches, toggling between two distinct nucleotide-bound states. Using traditional multidimensional heteronuclear NMR, even for single smGs, numerous experiments, high protein concentrations, expensive isotope labeling, and long analysis times are necessary. 19F NMR of fluorinated proteins or ligands can overcome these drawbacks. Using indole position-specific 19F labeling of the proteins, the activities of several smGs were measured in a multiplexed fashion. We investigated 4-, 5-, 6-, and 7-fluoro tryptophan containing smGs to study nucleotide binding. Distinct resonances for GDP- or GTP-bound states of three different 19F-labeled smGs, RhoA, K-Ras, and Rac1, were observed, and the kinetics of exchange and hydrolysis were measured. This multiplexed system will permit screening of nucleotide-specific ligands of smGs under true physiological conditions.

The Association of Fructose Metabolism With Anesthesia/Surgery-Induced Lactate Production.

In elderly individuals, excessive lactate levels in the brain may be associated with the development of cognitive impairment after surgery, including delayed neurocognitive recovery (dNCR). Since the origin of this increased lactate is unknown, here we assessed associations between metabolic pathways and postoperative dNCR. This study included 43 patients (≥60 years old) who had surgery under general anesthesia. We also used a mouse model in which 20-month-old mice were exposed to sevoflurane to induce postoperative dNCR, while control mice were exposed to 40% oxygen. Mice in the control group and anesthesia/surgery group were injected with fructose or glucose intracerebroventricularly, or fructose metabolism inhibitor intraperitoneally. Barnes maze test and Y maze were used to measure cognitive function in mice. Metabolomics was used to measure metabolites in the serum of patients and the brains of mice after anesthesia/surgery. Isotope labeling and metabolic flux were used to analyze flow and distribution of specific metabolites in metabolic pathways. Among 43 patients, 17 developed dNCR. Metabolomics showed significantly decreased postoperative serum fructose 1-phosphate levels in dNCR compared to nondNCR patients (mean difference [×104] = -0.164 ± 0.070; P = .024). Similar results were found in the brains of mice (mean difference = -1.669 ± 0.555; *P = .014). Isotope labeling and metabolic flux experiments in mice showed fructose but not glucose entered glycolysis, increasing lactate levels in the brain after anesthesia/surgery (P < .05). Administration of intraperitoneal fructose inhibitors to mice effectively inhibited increased lactate levels in the brain (mean difference =96.0 ± 4.36, P = .0237) and cognitive dysfunction after anesthesia/surgery (mean difference =69.0 ± 3.94, P = .0237). In a small subsample, we also found anesthesia/surgery increased interleukin-6 (IL-6) levels in the brains of mice (mean difference =88.3 ± 3.44, P = .0237) and that IL-6 may function upstream in fructose activation. These results suggest that anesthesia/surgery activates fructose metabolism, producing excessive lactate in the brain that is associated with postoperative cognitive impairment. Fructose metabolism is thus a potential therapeutic target for dNCR.

Microbial Network Complexity Helps to Reduce the Deep Migration of Chemical Fertilizer Nitrogen Under the Combined Application of Varying Irrigation Amounts and Multiple Nitrogen Sources

The deep migration of soil nitrogen (N) poses a significant risk of N leaching, contributing to non-point-source pollution. This study examines the influence of microbial networks on the deep migration of chemical fertilizer N under varying irrigation management and multiple N fertilizer sources. A soil column experiment with eight treatments was conducted, utilizing 15N isotope labeling and metagenomic sequencing technology. The findings revealed that reduced irrigation significantly curbs the deep migration of chemical fertilizer N, and straw returning also mitigates this migration under conventional irrigation. Microbial network complexity and stability were markedly higher under reduced irrigation compared to conventional practices. Notably, network node count, average degree, and modularity exhibited significant negative correlations with the deep migration of chemical fertilizer N. The network topology indices, including node count, average clustering coefficient, average degree, modularity, and edge count, were found to be relatively more important for the deep migration of chemical fertilizer N. In conclusion, microbial networks play an important role in reducing the deep migration of chemical fertilizer N.

Metabolomic characterization of a new strain of microalgae by GC-MS method with the introduction of a deuterium label.

Microalgae are active producers of various compounds, including toxic substances. However, their metabolism is very diverse and insufficiently known. We demonstrate an approach that includes growing a new strain of cyanobacterium Leptolyngbya sp. (IPPAS B-1204) on an isotopically labeled medium (D2O) and evaluating the metabolomic composition of these microorganisms after deuterium uptake. Despite the low resolution of the GC-MS method, the interpretation of the obtained spectra allowed us to find out not only the amount of the embedded isotope label but also to assume the position in the structure where the label is embedded. We present the results of reliably detecting more than 30 compounds with isotope labels belonging to various classes of biological compounds produced by this cyanobacterium, revealing the metabolic pathways of entry of this label. We also demonstrate that the synthesis of unsaturated fatty acids is suppressed under the growth on D2O medium. In addition, we found an isotopic effect in the chromatographic separation of isotopically labeled compounds in gas chromatography. These data can be used in the future both for the identification of compounds and the analysis of the biosynthesis pathways of secondary biologically active compounds and in the analysis of the production of isotopically labeled standards of compounds.

Coupling methane oxidation and N2 fixation under methanogenic conditions in contrasting environments

Microbial methane oxidation under widespread suboxic environment is crucial for understanding methane emission. However, the role of aerobic methanotrophs in mediating methane oxidation and nitrogen fixation is less understood in oxygen-limiting environments. In this study, we identified diazotrophic methanotrophs under oxygen-limited conditions (initial O2 of 6–8 μM) in two contrasting habitats (paddy soil and marine sediment) using DNA-based stable isotope probing combined with amplicon sequencing. Consistently, we documented significant 13CH4 oxidation and 15N2 fixation after 740 days of suboxic isotope labeling. Sequencing analysis revealed the predominance of Methylobacter–affiliated aerobic methanotrophs in the 13C-labeled DNA fractions. These Methylobacter-like OTUs accounted for 97.86 % in paddy soil and 99.49 % in marine sediment of the total pmoA gene sequences; while relative abundances for the nifH gene sequences were 91.59 % in paddy soil and 99.49 % in marine sediment. Taken together, our analyses revealed that Methylobacter is responsible for methane oxidation and nitrogen fixation under oxygen limitation in both habitats, demonstrating convergent emergence of this aerobic methanotroph under oxygen deficiency.

Natural Abundance 195Pt-13C Correlation NMR Spectroscopy on Surfaces Enabled by Fast MAS Dynamic Nuclear Polarization

Surface organometallic chemistry has developed as an effective strategy for the rational design and synthesis of well-defined, single-site Pt-based heterogeneous catalysts. Given its high sensitivity to changes in electronic structure, 195Pt solid-state NMR spectroscopy offers a unique approach to investigate the chemical structure and local environment of Pt surface sites, providing invaluable insights for establishing structure-activity relationships. However, this approach is typically hindered by severe sensitivity issues, due to the low loading of Pt sites and the often-encountered large 195Pt chemical shift anisotropies. To overcome this limitation, 195Pt NMR signature of surface metal centers can be indirectly detected through protons. Indirect detection on 13C spins, has also been demonstrated to be feasible by combining isotopic labeling with dynamic nuclear polarization (DNP). Here, we extend this methodology to a supported Pt complex at natural abundance. The material was prepared by grafting (COD)PtMeOSi(OtBu)3 (COD = 1,5-cyclooctadiene, Me = methyl and tBu = tert-butyl) onto partially dehydroxylated silica. DNP enhanced two-dimensional through-bond 13C{195Pt} heteronuclear correlation experiments were successfully implemented at fast magic angle spinning. They enabled the detection of the 0.37% NMR-responsive surface species, thereby showcasing the remarkable sensitivity of this approach and its broad applicability. Key bonding information was obtained by measuring the correlated 13C and 195Pt isotopic chemical shifts as well as 1J(13C-195Pt) coupling constants, confirming directly the coordination structure of the surface Pt sites.

Key active mercury methylating microorganisms and their synergistic effects on methylmercury production in paddy soils

Rice contamination with neurotoxic methylmercury (MeHg) from paddy soils is an escalating global concern. Identifying the microorganisms responsible for mercury (Hg) methylation in these soils is essential for controlling Hg contamination in the food chain and mitigating health impacts. Current research often focuses on total Hg-methylating microorganisms, overlooking the contributions of active ones, which can lead to either overestimating or neglecting the specific roles of microorganisms in Hg methylation within paddy soils. In this study, active Hg-methylating microorganisms in paddy soils were identified using a combination of DNA-SIP, Hg isotope labelling, and Hg methylation gene sequencing techniques. Our findings revealed that Geobacter and Anaerolinea are pivotal active Hg-methylating microorganisms across a contamination gradient in paddy soils. Transcriptomic analysis of soils from major rice-producing provinces in China confirmed the widespread and synergistic involvement of these microorganisms. Microbial incubation further validated their interaction significantly enhances Hg methylation, with Me198Hg concentrations increasing 2.8-fold compared to Geobacter alone and 5.2-fold compared to Anaerolinea alone. These findings enhance our understanding of microbial Hg methylation in paddy soils, providing critical insights for accurately predicting soil MeHg load, rice grain MeHg contamination, and human MeHg exposure risks.

Adaptive expression of phage auxiliary metabolic genes in paddy soils and their contribution toward global carbon sequestration

Habitats with intermittent flooding, such as paddy soils, are crucial reservoirs in the global carbon pool; however, the effect of phage-host interactions on the biogeochemical cycling of carbon in paddy soils remains unclear. Hence, this study applied multiomics and global datasets integrated with validation experiments to investigate phage-host community interactions and the potential of phages to impact carbon sequestration in paddy soils. The results demonstrated that paddy soil phages harbor a diverse and abundant repertoire of auxiliary metabolic genes (AMGs) associated with carbon fixation, comprising 23.7% of the identified AMGs. The successful annotation of protein structures and promoters further suggested an elevated expression potential of these genes within their bacterial hosts. Moreover, environmental stressors, such as heavy metal contamination, cause genetic variation in paddy phages and up-regulate the expression of carbon fixation AMGs, as demonstrated by the significant enrichment of related metabolites (P < 0.05). Notably, the findings indicate that lysogenic phages infecting carbon-fixing hosts increased by 10.7% under heavy metal stress. In addition, in situ isotopic labeling experiments induced by mitomycin-C revealed that by increasing heavy metal concentrations, 13CO2 emissions from the treatment with added lysogenic phage decreased by approximately 17.9%. In contrast, 13C-labeled microbial biomass carbon content increased by an average of 35.4% compared to the control. These results suggest that paddy soil phages prominently influence the global carbon cycle, particularly under global change conditions. This research enhances our understanding of phage-host cooperation in driving carbon sequestration in paddy soils amid evolving environmental conditions.

Cooperative Iodine and Nitrate Catalyzed Oxidation of Stilbenes to α-Diketones in Water.

An efficient oxidation of stilbenes to α-diketones co-catalyzed by bismuth nitrate and iodine is reported. The utilization of molecular oxygen as a terminal oxidant and water as the reaction solvent provides a low-cost and environmentally friendly approach to preparing the α-diketone derivatives from readily available stilbenes. Isotope labeling experiments suggest that the two oxygen atoms of the α- diketone products mainly originate from water. The method displays high functional group tolerance and we have demonstrated a concise route for preparing trifenagrel and HIV-1 integrase inhibitors from 1,2-diphenylethene.

Distance-dependent, species-specific effects of legumes on nitrogen utilization by companion non-legumes in the Gurbantunggut desert, Northern China

Legumes, as an important biological nitrogen (N) fixation resource, could effectively supplement N inputs to terrestrial ecosystems, especially in N-poor desert ecosystems. However, there is limited research on the N utilization strategies of different plant life forms coexisting under the “fertilizer island effect” created by leguminous shrubs. The study aims to explore the N acquisition patterns of herbaceous plants adjacent to Eremosparton songoricum (Litv.) Vassilcz. in the Gurbantungut Desert of northern China. In this study, the 15N isotope labeling method was used to track the N acquisition of the companion plants Ceratocarpus arenarius L. and Centaurea pulchella Ledeb. within 0–10 cm (D1), 30–40 cm (D2), 60–70 cm (D3), and 90–100 cm (D4) from a dominant legume species E. songoricum. The results showed that: (1) The “N acquisition” by herbaceous plants near leguminous shrubs showed distinct effects related to distance, with a preference for N-NH4+ (contribution rate: 25.42 % ∼ 58.94 %) at a closer distance from the shrub, and a preference for N-NO3−(contribution rate: 17.17 %–54.65 %) at a farther distance. (2) There was niche separation in the acquisition of organic N by the associated species of different life forms, in which the 15N-Glycine recovery and absorption rate of Cer. arenarius decreased with the increase of distance level (D1 > D2 > D3 > D4). However, Cen. pulchella had the maximum 15N-Glycine recovery at D4 (90–100 cm) (D1 < D2 < D3 < D4). (3) By analyzing the key driving factors that influence the N form preferences of non-leguminous plants associated with leguminous shrubs, it was found that the biomass of the 2 species tended to increase with increasing distance levels, and the preference for N forms changed from ammonium N to nitrate N. However, increased distance had a positive effect on the acquisition of N-Glycine and N-NO3−, whereas it negatively impacted the uptake of N-NH4+. These findings revealed that in N-poor desert ecosystems, herbaceous plants near leguminous shrubs adjusted their N preferences based on distance to optimize N uptake and facilitate niche coexistence. This study provides data that support a deeper understanding of the mechanisms of species coexistence and ecological stability assessments among diverse plant species in desert environments.

Hydrogen Isotope Labeling of Pharmaceuticals Via Dual Hydrogen Isotope Exchange Pathways Using CdS Quantum Dot Photocatalyst.

Isotopic labeling is a powerful technique extensively used in the pharmaceutical industry. By tracking isotope-labeled molecules, researchers gain unique and invaluable insights into the pharmacokinetics and pharmacodynamics of new drug candidates. Hydrogen isotope labeling is particularly important as hydrogen is ubiquitous in organic molecules in biological systems, and it can be introduced effectively through late-stage hydrogen isotope exchange (HIE). However, hydrogen isotope methods that simultaneously label multiple sites with varying types of C-H bonds in the different types of molecules are still lacking. Herein, we demonstrate a heterogeneous photocatalytic system using a CdS quantum dot catalyst that proceeds via a unique dual HIE pathway mechanism─one occurs in the reaction solution and the other on the catalytic surface─to address it. This unique mechanism unlocked several unique labeling capabilities, including simultaneous labeling of multiple and challenging sites such as secondary α-amino, α-ethereal, allyl, and vinyl sites, providing great versatility in practical uses for pharmaceutical labeling.

Confined synthesis and thermal conductivity of deuterated graphene nanoribbons

In contrast to gapless graphene, armchair graphene nanoribbons (AGNRs) exhibit a width-dependent band gap. Theoretical calculations predicted that the thermal conductivity of graphene nanoribbons (GNRs) is significantly lower than that of graphene and can be customized through isotopic labeling. However, experimental validation of this phenomenon is still challenging. In this study, hydrogen-terminated 6-AGNRs and deuterated 6-AGNRs with varying deuteration ratios were synthesized inside single-walled carbon nanotubes. By applying Raman spectroscopy, the thermal conductivity of 6-AGNRs was determined to be approximately 1150 W m−1 K−1, which is only one third of graphene and is consistent to the theoretical prediction. Furthermore, the thermal conductivity of deuterated 6-AGNRs is reduced by more than 50 % compared to that of the 6-AGNRs, suggesting an effective route to modulate the thermal conductivity of GNRs, in addition to the width and edge structure of the GNRs.

Catalytic Asymmetric Cycloaddition of Olefins with In Situ Generated N-Boc-Formaldimine.

Chiral 1,3-amino alcohols are ubiquitous structural motifs in natural products and active pharmaceutical ingredients. We present a highly enantioselective, inverse-electron-demand hetero-Diels-Alder reaction of olefins with in situ generated N-Boc-formaldimine catalyzed by strong and confined Bro̷nsted acids. This transformation provides direct access to valuable 1,3-amino alcohols from styrenes and 1,1-disubtituted alkenes. Isotope labeling studies and kinetic analysis reveal an unusual mechanism involving an oxazinium intermediate and a catalyst order greater than one.

Investigating the impacts of charge composition and temperature on ammonia/hydrogen combustion in a heavy-duty spark-ignition engine

Ammonia, as a hydrogen carrier with mature production technology and convenient storage, has become one of the most promising zero carbon fuels in recent years. The use of ammonia/hydrogen mixture fuel in spark ignition (SI) engines has drawn significant attentions since it solves the problems of low flame speed, high ignition energy requirement and narrow flammable range of pure ammonia. In this study, the combustion and emission processes of an ammonia/hydrogen port fuel injection (PFI) engine at high load operation are numerically analyzed to investigate the effects of intake hydrogen energy ratio (HER), equivalence ratio (φ), intake temperature and combustion chamber wall temperature on energy distribution and pollutants. The results indicate that under the same HER of 25%, the lean-burned mode provides favorable thermal efficiency compared to stoichiometric mode due to reduced combustion and wall heat loss. However, lower cylinder temperature at lean condition inhibits the participation of NH3 in the reduction reactions and the consumption of N2O, increasing the residuals of both pollutants. The NOx emission is promoted by excessive O radicals at lean conditions, and the pathways of fuel NOx and thermal NOx are also discussed using an isotope labeling method. At stoichiometric mode, increasing fuel HER (10%–25%) only has minor impacts on improving thermal efficiency, but can promote the consumption of NH3 and N2O by increasing H radicals and cylinder temperature. The study also shows that optimizing the intake and wall temperatures can effectively reduce NH3 and N2O emissions by 87.5% and 71.7%, respectively, while slightly reducing NOx.

The Trifluorooxygenate Anion [OF3]-: Spectroscopic Evidence for a Binary, Hypervalent Oxygen Species.

Experimental evidence for hypervalent compounds of second-row elements is still scarce in literature. Here, we present the first report of the long-sought binary, hypervalent trifluorooxygenate anion [OF3]-. It was isolated in solid Ne matrices under cryogenic conditions after reacting oxygen difluoride with free fluoride ions from laser ablation of alkali metal fluorides MF (M=Li-Cs). VSEPR theory and calculations at the CCSD(T) level predict a C2v-symmetric T-shape structure with one short and two long O-F bond lengths in [OF3]-. This is confirmed experimentally by FTIR spectroscopy in combination with isotopic labeling. Analysis of the natural local molecular orbitals shows the presence of one 2c-2e and one 3c-4e bond each. Natural resonance theory indicates the importance of the stability of [OF2]⋅- for the stability of [OF3]-. Although free [OF2]⋅- was not detected, the species MOF2 (M=Na-Cs) could be observed in the same experiments, which are best described as contact ion pairs of M+[OF2]⋅-.

Das Trifluoroxygenat‐Anion [OF3]−: Spektroskopischer Nachweis einer Binären, Hypervalenten Sauerstoffspezies

AbstractExperimentelle Belege für hypervalente Verbindungen von Elementen der zweiten Periode sind in der Literatur selten. In dieser Arbeit berichten wir erstmals über das lange gesuchte binäre, hypervalente Trifluoroxygenat‐Anion [OF3]−. Es wurde gebildet durch die Reaktion von Sauerstoffdifluorid mit freien Fluorid‐Ionen, welche durch Laserablation von Alkalimetallfluoriden MF (M=Li−Cs) erzeugt wurden, und konnte unter kryogenen Bedingungen in Neonmatrizen isoliert werden. Das VSEPR‐Modell und Berechnungen auf CCSD(T)‐Niveau sagen eine C2v‐symmetrische T‐förmige Struktur mit einer kurzen und zwei langen O−F‐Bindungen für [OF3]− voraus. Dies wird durch FTIR‐Spektroskopie in Kombination mit Isotopenmarkierungs‐Experimente bestätigt. Eine Analyse der natürlichen lokalisierten Molekülorbitale zeigt das Vorliegen einer 2Z–2E‐Bindung und einer 3Z–4E‐Bindung an. Natural Resonance Theory weist auf die Bedeutung der Stabilität von [OF2]⋅− für die Stabilität von [OF3]− hin. Obwohl freies [OF2]⋅− nicht nachgewiesen wurde, konnten in denselben Experimenten die Spezies MOF2 (M=Na−Cs) beobachtet werden, die sich am besten als Kontaktionenpaar M+[OF2]⋅− beschreiben lassen.

Plant organic nitrogen nutrition: costs, benefits, and carbon use efficiency.

Differences in soil mobility and assimilation costs between organic and inorganic nitrogen (N) compounds would hypothetically induce plant phenotypic plasticity to optimize acquisition of, and performance on, the different N forms. Here we evaluated this hypothesis experimentally and theoretically. We grew Arabidopsis in split-root setups combined with stable isotope labelling to study uptake and distribution of carbon (C) and N from l-glutamine (l-gln) and NO3 - and assessed the effect of the N source on biomass partitioning and carbon use efficiency (CUE). Analyses of stable isotopes showed that 40-48% of C acquired from l-gln resided in plants, contributing 7-8% to total C of both shoots and roots. Plants grown on l-gln exhibited increased root mass fraction and root hair length and a significantly lower N uptake rate per unit root biomass but displayed significantly enhanced CUE. Our data suggests that organic N nutrition is linked to a particular phenotype with extensive growth of roots and root hairs that optimizes for uptake of less mobile N forms. Increased CUE and lower N uptake per unit root growth may be key facets linked to the organic N phenotype.

Mechanistic insights into the pH-driven radical transformation of the Fe(II)/nCP in groundwater remediation

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid H2O2 source, have attracted significant research interst for their application potential in groundwater remediation. Compared to the traditional Fenton system, the nCP-based Fenton-like system has a wider pH-working window for contaminants degradation. This results from the dominant radical transformation under different pH. Unlike the traditional Fenton system which is only effective in acid conditions with hydroxyl radical (•OH) as the main active species, the release of H2O2 and O2 from nCP provides multiple contaminants degradation pathways. In acidic environments, •OH and Fe(IV) predominate as the active species, facilitated by substantial H2O2 production which activates the Fenton reaction. In neutral or alkaline conditions, the production of H2O2 was dramatically decreased. While the O2 released from nCP can be catalyzed by Fe(II) to form superoxide radical (•O2-), which subsequently generate singlet oxygen (1O2). The formation pathway of •O2- was tracked by O18 isotope labeling experiment. The impact of the water matrix on radical generation in the Fe(II)/nCP Fenton-like system was also studied. This research deepens the understanding of the radical formation mechanisms in nCP-based Fenton-like system, offering insights to support their application in remediating contaminated groundwater.

Lactylation of Hdac1 regulated by Ldh prevents the pluripotent-to-2C state conversion

BackgroundCellular metabolism regulates the pluripotency of embryonic stem cells (ESCs). Yet, how metabolism regulates the transition among different pluripotent states remains elusive. It has been shown that protein lactylation, which uses lactate, a metabolic product of glycolysis, as a substrate, plays a critical role in various biological events. Here we focused on that glycolysis regulates the conversion between ESCs and 2-cell-like cells (2CLCs) through protein lactylation.MethodsRNA-seq revealed the activation of 2-cell (2C) genes by suppression of Ldh. Stable isotope labeling by amino acids in cell culture (SILAC) coupled with lactylated peptide enrichment and quantitative mass spectrometric analysis was carried out to investigate the mechanism how protein lactylation regulates the pluripotent-to-2C transition. And we focused on Hdac1. Lactylation of Hdac1 required for silencing 2C genes was proved by quantitative reverse-transcription PCR (qRT-PCR), immunofluorescence (IF), Western blot and chimeric embryos. Chromatin immunoprecipitation coupled with sequencing (ChIP-seq) and in vitro deacetylation assay confirmed lactylation of Hdac1 promoting its binding at 2C genes and enhancing its deacetylase activity, thereby facilitating the removal of H3K27ac and the silencing of 2C genes.ResultsWe found that inhibition or depletion of Ldha, the enzyme converting pyruvate to lactate, leads to the activation of 2C genes, as well as reduced global lactylation in ESCs. To investigate the mechanism how protein lactylation regulates the pluripotent-to-2C transition, quantitative lactylome analysis was performed, and 1716 lactylated proteins were identified. We then focused on Hdac1, a histone deacetylase involved in the silencing of 2C genes. Lactylation of Hdac1 promotes its binding at 2C genes and enhances its deacetylase activity, thus facilitating the removal of H3K27ac and the silencing of 2C genes.ConclusionsIn summary, our study reveals a mechanistic link between cellular metabolism and pluripotency regulation through protein lactylation. Our research is the first time to reveal that quantitative lactylome analysis in mouse ESCs. We found that lactylated Hdac1 promotes its binding at 2C genes and enhances its deacetylase activity, thus facilitating the removal of H3K27ac and the silencing of 2C genes.

Ultra-inert lanthanide chelates as mass tags for multiplexed bioanalysis

Coordination compounds of lanthanides are indispensable in biomedical applications as MRI contrast agents and radiotherapeutics. However, since the introduction of the chelator DOTA four decades ago, there has been only limited progress on improving their thermodynamic stability and kinetic inertness, which are essential for safe in vivo use. Here, we present ClickZip, an innovative synthetic strategy employing a coordination-templated formation of a 1,5-triazole bridge that improves kinetic inertness up to a million-fold relative to DOTA, expanding utility of lanthanide chelates beyond traditional uses. Acting as unique mass tags, the ClickZip chelates can be released from (biological) samples by acidic hydrolysis, chromatographically distinguished from interfering lanthanide species, and sensitively detected by mass spectrometry. Lanthanides enclosed in ClickZip chelates are chemically almost indistinguishable, providing a more versatile alternative to chemically identical isotopic labels for multiplexed analysis. The bioanalytical potential is demonstrated on tagged cell-penetrating peptides in vitro, and anti-obesity prolactin-releasing peptides in vivo.