Chemoenzymatic Labeling, Detection and Profiling of Core Fucosylation in Live Cells.

Core fucosylation, the attachment of an α-1,6-linked-fucose to the N-glycan core pentasaccharide, is an abundant protein modification that plays critical roles in various biological processes such as cell signaling, B cell development, antibody-dependent cellular cytotoxicity, and oncogenesis. However, the tools currently used to detect core fucosylation suffer from poor specificity, exhibiting cross-reactivity against all types of fucosylation. Herein we report the development of a new chemoenzymatic strategy for the rapid and selective detection of core fucosylated glycans. This approach employs a galactosyltransferase enzyme identified fromCaenorhabditis elegansthat specifically transfers an azido-appended galactose residue onto core fucose via a ß-1,4 glycosidic linkage. We demonstrate that the approach exhibits superior specificity toward core fucose on a variety of complex N-glycans. The method enables detection of core fucosylated glycoproteins from complex cell lysates, as well as on live cell surfaces, and it can be integrated into a diagnostic platform to profile protein-specific core fucosylation levels. This chemoenzymatic labeling approach offers a new strategy for the identification of disease biomarkers and will allow researchers to further characterize the fundamental role of this important glycan in normal and disease physiology.

Oligo(phenylenevinylene)-Based Covalent Organic Frameworks with Kagome Lattice for Boosting Photocatalytic Hydrogen Evolution.

Covalent organic frameworks (COFs) have shown great advantages as photocatalysts for hydrogen evolution. However, the effect of linkage geometry and type of linkage on the extent of π-electron conjugation in the plane of the framework and photocatalytic properties of COFs remains a significant challenge. Herein, two Kagome (kgm) topologic oligo(phenylenevinylene)-based COFs are designed and synthesized for boosting photocatalytic hydrogen evolution via a "two in one" strategy. Under visible light irradiation, COF-954 with 5 wt% Pt as cocatalyst exhibits high hydrogen evolution rate (HER) of 137.23 mmol g-1 h-1 , outperforming most reported COF-based photocatalysts. More importantly, even in natural seawater, COF-954 shows an average HER of 191.70 mmol g-1 h-1 under ultraviolet-visible (UV-vis) light irradiation. Additionally, the water-drainage experiments indoors and outdoors demonstrate that 25 and 8 mL hydrogen gas could be produced in 80 min under UV-vis light and natural sunlight, respectively, corresponding to a high HER of 167.41 and 53.57 mmol h-1 g-1 . This work not only demonstrates an effective design strategy toward highly efficient COF-based photocatalysts, but also shows the great potential of using the COF-based photocatalysts for photocatalytic hydrogen evolution.

Enhanced degradation of chloramphenicol via heterogeneous activation of peroxymonosulfate by Fe3O4 and gallic acid.

In this study, we demonstrated the effective degradation of wide-spectrum antibiotic chloramphenicol (CAP) by Fe3O4/peroxymonosulfate (PMS) system modified by gallic acid (GA). GA/Fe3O4/PMS showed a substantially higher degradation rate (77.6%) than Fe3O4/PMS (8.3%). The active components were detected by electron spin-resonance spectroscopy (ESR) and the quenching experiments. The results showed that the hydroxyl radical (HO•) was the main reason for the degradation of CAP. In the GA/Fe3O4/PMS system, the trace amount of dissolved iron ion were not the main species that activated PMS. Surface characterization and theoretical simulations showed that Fe atoms on Fe3O4 were responsible for PMS activation rather than a homogenous reaction. Five probable CAP degradation pathways were identified by density functional theory (DFT) calculations and liquid-phase mass spectrometry. Finally, the reusability of Fe3O4 was measured, and the GA/Fe3O4/PMS system maintained high efficiency after 5 times applications. The total organic carbon (TOC) removal rate reached 46.5% after reacting for 12 h. The gallic acid effectively promotes the circulation of Fe(II)/Fe(III) on solid surfaces and enhanced the degradation capacity of the original system. The research proposed a new way of directly employing plant polyphenols to boost the degradation ability of contaminants in heterogeneous systems.

A comparative study on Fe(III)/H2O2 and Fe(III)/S2O82- systems modified by catechin for the degradation of atenolol.

The processes of Fe(III) activated persulfate (PS) and H2O2 modified by catechin (CAT) had been shown to be effective in degrading contaminants. In this study, the performance, mechanism, degradation pathways and products toxicity of PS (Fe(III)/PS/CAT) and H2O2 (Fe(III)/H2O2/CAT) systems were compared using atenolol (ATL) as a model contaminant. 91.0% of ATL degradation was reached after 60 min in H2O2 system which was much higher than that in PS system (52.4%) under the same experimental condition. CAT could react directly with H2O2 to produce small amounts of HO• and the degradation efficiency of ATL was proportional to CAT concentration in H2O2 system. However, the optimal CAT concentration was 5 µM in PS system. The performance of H2O2 system was more susceptible to pH than that of PS system. Quenching experiments were conducted indicating that SO4•- and HO• were produced in PS system while HO• and O2•- accounted for ATL degradation in H2O2 system. Seven pathways with nine byproducts and eight pathways with twelve byproducts were put forward in PS and H2O2 systems respectively. Toxicity experiments showed that the inhibition rates of luminescent bacteria were both decreased about 25% after 60 min reaction in two systems. Although the software simulation result showed few intermediate products of both systems were More toxic than ATL, but the amounts of them were 1-2 orders of magnitude lower than ATL. Moreover, the mineralization rates were 16.4% and 19.0% in PS and H2O2 systems respectively.

Mechanism of the improved Fe(III)/persulfate reaction by gallic acid for ibuprofen degradation.

Gallic acid (GA), a natural plant polyphenol, was applied as amendment of Fe(III)/persulfate (PS) system for ibuprofen (IBP) degradation in this study. The impacts of all agentia (GA, Fe(III), PS) concentration and initial pH values on IBP removal efficiency were investigated, and their corresponding observed pseudo-first-order rate constants (kobs) were calculated. The addition of GA has significantly improved elimination efficiency of IBP due to the enhanced Fe(III)/Fe(II) cycle. Electron paramagnetic resonance (EPR) results confirmed that SO4•-, HO• and O2•- were involved in GA/Fe(III)/PS system. However, quenching experiments further affirmed the impact of SO4•- and HO• towards IBP decomposition instead of O2•-, with contribution ratio to IBP removal was 69.12% and 30.88%, respectively. SO4•- was the main radicals formed by directly activation of PS with Fe(II), while HO• was the transformation product of SO4•-. Based on instrumental analysis (stopped-flow UV-vis spectrum and MS) and theoretical calculation, the potential reaction mechanism between GA and Fe(III) in the presence of PS was further proposed. GA complexed with Fe(III) firstly and the Fe(III)-GA complex was then converted into quinone substance, accompanied by the generation of Fe(II). Furthermore, the application of GA extended the optimal pH range to neutral as well, which made it a promising treatment in practical application.

De-sialylation of glycopeptides by acid treatment: enhancing sialic acid removal without reducing the identification.

Sialic acid, a common terminal monosaccharide on many glycoconjugates, plays essential roles in many biological processes such as immune responses, pathogen recognition, and cancer development. For various purposes, sialic acids may need to be removed from glycopeptides or glycans, mainly using enzymatical or chemical approaches. In this study, we found that most commonly used chemical methods couldn't completely remove sialic acids from glycopeptides. Although the de-sialylation efficiency could be further enhanced by increasing the treatment time or acid concentration, the undesirable side reactions on the peptide portion would decrease glycopeptide identification. By adding the deamidation on carbamidomethyl-cysteine (C), asparagine (N), and glutamine (Q) residues as a variable modification during database search, most of the unidentified spectra could be recovered. This optional acid-treatment and database search method for the complete removal of sialic acids without losing much spectral identification should be quite useful for many glycomic and glycoproteomic studies.

Selectivity of a ZnO@ZIF-71@PDMS Nanorod Array Gas Sensor Enhanced by Coating a Polymer Selective Separation Membrane.

It is important for noninvasive diagnosis of diabetes to develop acetone gas sensors with high selectivity. ZnO@ZIF-71 has been reported as a highly sensitive and selective gas sensor on acetone detection. However, it is difficult to exclude the interference with similar molecular sizes gas in the gas-sensing process, like ethanol. To solve this problem, polydimethylsiloxane (PDMS) was synthesized on the surface of ZnO@ZIF-71 to form a ZnO@ZIF-71@PDMS sensor by vapor deposition. The new sensor shows inert response to ethanol and effective response to acetone simultaneously. The PDMS membrane acts as a molecular sieve, which shows the acetone selectivity performance and can totally eliminate the response to low concentration ethanol at low temperature. Theory calculations and solubility test are also employed to prove the role PDMS plays in this process. It demonstrated that the acetone selectivity performance comes from the hydrogen bond interaction between the ethanol gas molecules and PDMS, which increases difficulty for ethanol gas molecules to penetrate the PDMS membrane. Further, this work provides a new method for enhancing gas-sensing selectivity and promoting for miniaturization of gas sensors.

The Role of Non-Catalytic Domains of Hrp3 in Nucleosome Remodeling.

The Helicase-related protein 3 (Hrp3), an ATP-dependent chromatin remodeling enzyme from the CHD family, is crucial for maintaining global nucleosome occupancy in Schizosaccharomyces pombe (S. pombe). Although the ATPase domain of Hrp3 is essential for chromatin remodeling, the contribution of non-ATPase domains of Hrp3 is still unclear. Here, we investigated the role of non-ATPase domains using in vitro methods. In our study, we expressed and purified recombinant S. pombe histone proteins, reconstituted them into histone octamers, and assembled nucleosome core particles. Using reconstituted nucleosomes and affinity-purified wild type and mutant Hrp3 from S. pombe we created a homogeneous in vitro system to evaluate the ATP hydrolyzing capacity of truncated Hrp3 proteins. We found that all non-ATPase domain deletions (∆chromo, ∆SANT, ∆SLIDE, and ∆coupling region) lead to reduced ATP hydrolyzing activities in vitro with DNA or nucleosome substrates. Only the coupling region deletion showed moderate stimulation of ATPase activity with the nucleosome. Interestingly, affinity-purified Hrp3 showed co-purification with all core histones suggesting a strong association with the nucleosomes in vivo. However, affinity-purified Hrp3 mutant with SANT and coupling regions deletion showed complete loss of interactions with the nucleosomes, while SLIDE and chromodomain deletions reduced Hrp3 interactions with the nucleosomes. Taken together, nucleosome association and ATPase stimulation by DNA or nucleosomes substrate suggest that the enzymatic activity of Hrp3 is fine-tuned by unique contributions of all four non-catalytic domains.

Enhanced activation of persulfate by Fe(III) and catechin without light: Reaction kinetics, parameters and mechanism.

An environmental-friendly plant polyphenol, catechin (CAT), was applied in Fe(III) activated persulfate (PS) system for naproxen (NPX) degradation in this research. Reaction kinetics, parameters, NPX degradation products and reaction mechanism were investigated. Combining the results of quenching experiments as well as Electron Spin Resonance (ESR), it was observed that SO4•- was critical in NPX degradation, and the contribution of HO• was minor in the Fe(III)/CAT/PS system. O2•- was generated during the reaction but did not contribute to NPX degradation. SO4•- and HO• were produced from the PS activation by Fe(II), which was formed from the transient complexing and reduction process between Fe(III) and CAT. The effects of Fe(III), CAT, PS concentration and pH value on NPX degradation were evaluated. Moreover, the mineralization rate was 20.2%, and the toxicity of the treated solution were lower than the initial solution. Nine possible intermediates were determined when using LC-QTOF-MS to analyze, and three degradation pathways were put ward. The results proved that CAT could accelerate the redox cycle of Fe(III)/Fe(II), consequently to strengthen PS activation without light. It was a promising oxidation technology as it offered an energy-saving and hypo-toxic way for refractory organic pollutants treatment, and it was applicable at a comparatively wide pH range.

Complexation of Fe(III)/Catechols in atmospheric aqueous phase and the consequent cytotoxicity assessment in human bronchial epithelial cells (BEAS-2B).

Recent research has shown that the complexation of metals-organics plays an important role in atmospheric particulate matter, whose health effects should be taken into account. This work investigates the interactions between catechols (CAs), i.e., 4-nitrocatechol (4NC) and 4-methylcatechol (4MC), and transition metals (i.e., Fe) in the aqueous phase dark reaction. The formation of Fe/CAs complexes and secondary organics products are analyzed by UV-Vis spectroscopy, stopped-flow spectroscopy, high-resolution mass spectrometry and Raman spectroscopy, while the insoluble particulate matter formed from the CAs/Fe mixtures are characterized by the FTIR, X-ray photoelectron spectroscopy (XPS) and thermogravimetric-quadrupole-mass spectrometry (TG-Q-MS). On the basis of the density functional theory (DFT) calculation and experimental results, the possible formation pathways for the complexes of Fe(III) with 4NC (a proxy for organics) are proposed. The Fe/CAs complexes and organics products perhaps have significant sources of light absorption which play an important role in influencing the intensity of atmospheric radiation and particulate phase photochemistry. Besides, the cytotoxicity is tested as a function of concentrations for CAs/Fe mixtures in BEAS-2B cells. Our results show that CAs/Fe mixtures have strong association with cytotoxicity, indicating the mixtures have potential influence to human health.

Modified MIL-100(Fe) for enhanced photocatalytic degradation of tetracycline under visible-light irradiation.

Iron-based metal-organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.

A regulatory role for CHD2 in myelopoiesis.

The transcriptional program that dictates haematopoietic cell fate and differentiation requires an epigenetic regulatory and memory function, provided by a network of epigenetic factors that regulate DNA methylation, post-translational histone modifications and chromatin structure. Disturbed epigenetic regulation causes perturbations in the blood cell differentiation program that results in various types of haematopoietic disorders. Thus, accurate epigenetic regulation is essential for functional haematopoiesis. In this study, we used a CRISPR-Cas9 screening approach to identify new epigenetic regulators in myeloid differentiation. We designed a Chromatin-UMI CRISPR guide library targeting 1092 epigenetic regulators. Phorbol 12-myristate 13-acetate (PMA) treatment of the chronic myeloid leukaemia cell line K-562 was used as a megakaryocytic myeloid differentiation model. Both previously described developmental epigenetic regulators and novel factors were identified in our screen. In this study, we validated and characterized a role for the chromatin remodeller CHD2 in myeloid proliferation and megakaryocytic differentiation.

Enhancement of iron-mediated activation of persulfate using catechin: From generation of reactive species to atenolol degradation in water.

Persulfate (PS) activation reaction, which forms sulfate radical (SO4-), can be used to degrade organic pollutants in water. However, a drawback of this reaction is that the regeneration of ferrous ions requires a high concentration of hydrogen peroxide (Fenton-like reaction) or use of UV radiation. Catechin (CAT), a non-toxic antioxidant of natural origin from tea, is used in this work to improve the sulfate radical-mediated degradation of atenolol (ATL, a model pollutant) in water using relatively low concentrations of reactive chemical species (less than 100 µM). To the best of the author's knowledge, the direct effect of CAT on the oxidation state of iron, which is promoted by the reduction of ferric into ferrous ions with the enhancement of SO4- formation in the presence of PS, is demonstrated for the first time. The enhancement versus inhibition effect of CAT and the chemical mechanism of the iron-based activation process are explained. Results show that UVA radiation, which is representative of solar light, accelerates the initial degradation of ATL by more than 30% through ferric iron photolysis. Finally, a reaction mechanism leading to the formation of hydroxyl radicals (HO) and SO4- is proposed considering the implication of different activation/reaction chemical steps.

Characterization and source identification of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in different seasons from Shanghai, China.

PM2.5 samples in four representative periods were collected from a highly industrialized district in Shanghai, China. The concentrations of PM2.5 and PM2.5-bound PAHs were analyzed. Positive matrix factorization (PMF) model was used to identify the potential sources. Relationship between PAHs distribution and meteorological parameters was assessed meanwhile. The incremental lifetime cancer risks (ILCRs) model was applied to quantitatively evaluate the exposure risk of PAHs. Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLT) model was used to track the potential pollution area of PM2.5 along with a Potential Source Contribution Function (PSCF) and Concentration Weighted Trajectory (CWT) methods. The results showed concentrations of PM2.5 and PAHs ranged from 14.83 to 185.58 µg/m3, 2.58 to 123.62 ng/m3, respectively. The source apportionment model indicated that traffic emissions were the most important sources in each sampling season, which accounted for 38.44%, 34.48%, 39.04% and 45.03%, respectively. Spearman correlation coefficient showed that PAHs had negative correlation with ambient temperature and relative humidity in some periods, while had no significant correlation with atmospheric pressure and visibility. The average estimated lifetime cancer risk for total PAHs reached 4.7 × 10-5, 4.5 × 10-5 and 4.1 × 10-5, 4.0 × 10-5 to exposed children and adults in winter and autumn, respectively, meaning that PM2.5-bound PAHs had high potential risk. HYSPLIT model suggested that monsoon greatly influenced the air quality in both winter and autumn.

Degradation of sunscreen agent p-aminobenzoic acid using a combination system of UV irradiation, persulphate and iron(II).

Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe(2+)/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe(2+) concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl(-), NO3 (-), H2PO4 (-) and HCO3 (-), impeded PABA degradation because of ion (Fe(2+)) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO4 (·-)) radicals were two main radicals observed in the UV/Fe(2+)/PS system; of these, SO4 (·-) showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO2) and water (H2O) by the UV/Fe(2+)/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation.

Occurrence, distribution and risk assessment of estrogens in surface water, suspended particulate matter, and sediments of the Yangtze Estuary.

The occurrence and distribution of six selected estrogen compounds were investigated in samples of surface water, suspended particulate matter (SPM), and sediment in the Yangtze Estuary and its coastal areas over four seasons. With the exception of 17α-ethinylestradiol (EE2), all estrogens were detected at least once in all three phases with bisphenol A (BPA) and estriol (E3) as the dominant estrogens in all phases. EE2 was not detected in any surface water samples. In addition, the highest total estrogen concentrations were found in January in all phases, which could be due to the low flow conditions and temperature during this season. A significant positive correlation was found between total estrogen concentrations and organic carbon (OC) contents, both in the water phase and solid phase (i.e. SPM and sediment), indicating the vital role played by OC. Based on a yeast estrogen screen (YES) bioassay, the higher estrogenic risk was found in the SPM and sediment phase when compared to the water phase. These results were confirmed by a risk assessment which revealed that the Yangtze Estuary was displayed a low to high risk over the seasons for all selected estrogens.

Environmental estrogens in a drinking water reservoir area in Shanghai: occurrence, colloidal contribution and risk assessment.

The occurrence and multi-phase distribution of six environmental estrogen compounds were investigated in a drinking water reservoir area by analyzing estrogens in suspended particulate matter (SPM), filtrate (conventional dissolved phase, <1 µm), permeate (truly soluble phase, <1 kDa) and retentate (colloidal phase, 1 kDa to 1 µm). The estrogen concentrations at different sites occurred in the following order: animal feed operation (AFO) wastewater-affected streams>tributaries>main stream channel. Correlation analysis showed that organic carbon (OC) contents had significantly positive correlations with environmental estrogens in filtrate, SPM and colloidal phases, respectively, indicating the important role played by OC. Aquatic colloids, often neglected, showed a much higher sorption capability of environmental estrogens compared to SPM. Similar Kcoc values in three types of sampling sites showed that colloids could be transported from AFO wastewater to tributaries and further into the main river channel. Mass balance calculations showed that 14.5-68.4% of OP, 4.5-32.1% of BPA, 2.0-58.4% of E1, 8.36-72.0% of E2, 0-20.6% of EE2, 3.4-62.7% of E3 and 8.3-36.1% of total estrogens were associated with colloidal fractions, suggesting that the colloids could act as a significant sink for environmental estrogens. Risk assessment demonstrated that the occurrence of environmental estrogens might pose a risk to aquatic organisms in the study area.

Solubility of iron from combustion source particles in acidic media linked to iron speciation.

In this study, iron solubility from six combustion source particles was investigated in acidic media. For comparison, a Chinese loess (CL) dust was also included. The solubility experiments confirmed that iron solubility was highly variable and dependent on particle sources. Under dark and light conditions, the combustion source particles dissolved faster and to a greater extent relative to CL. Oil fly ash (FA) yielded the highest soluble iron as compared to the other samples. Total iron solubility fractions measured in the dark after 12 h ranged between 2.9 and 74.1% of the initial iron content for the combustion-derived particles (Oil FA > biomass burning particles (BP) > coal FA). Ferrous iron represented the dominant soluble form of Fe in the suspensions of straw BP and corn BP, while total dissolved Fe presented mainly as ferric iron in the cases of oil FA, coal FA, and CL. Mössbauer measurements and TEM analysis revealed that Fe in oil FA was commonly presented as nanosized Fe(3)O(4) aggregates and Fe/S-rich particles. Highly labile source of Fe in corn BP could be originated from amorphous Fe form mixed internally with K-rich particles. However, Fe in coal FA was dominated by the more insoluble forms of both Fe-bearing aluminosilicate glass and Fe oxides. The data presented herein showed that iron speciation varies by source and is an important factor controlling iron solubility from these anthropogenic emissions in acidic solutions, suggesting that the variability of iron solubility from combustion-derived particles is related to the inherent character and origin of the aerosols themselves. Such information can be useful in improving our understanding on iron solubility from combustion aerosols when they undergo acidic processing during atmospheric transport.

Removal of H2S from gas stream using combined plasma photolysis technique at atmospheric pressure.

In this paper, H(2)S in gas stream was successfully decomposed at atmospheric pressure by dielectric barrier discharge plasma and VUV-UV radiation from a combined plasma photolysis reactor (CDBD). In comparison with DBD, CDBD enhanced H(2)S removal efficiency significantly at the same applied voltage, inlet H(2)S concentration and gas residence time. H(2)S removal efficiency was determined as a function of Kr pressure, applied voltage, inlet H(2)S concentration, and gas residence time. H(2)S removal efficiency could reach as high as 93% at inlet H(2)S concentration of 27.1 mg m(-3), residence time of 0.4 s, and applied voltage of 7.5 kV. The main products were discerned as H(2)O and SO(4)(2-) based on FTIR and IC analysis.

Disturbed tooth germ development in the absence of MINT in the cultured mouse mandibular explants.

The Msx2-interacting nuclear target protein (MINT) is a nuclear matrix protein that regulates the development of many tissues. However, little is known regarding the role of MINT in tooth development. In this study, we prepared polyclonal antibodies against MINT, and found that that MINT was expressed in different cells at each stage of tooth germ development by immunohistochemistry. The role of MINT in tooth development was further illustrated by the misshapen and severely hypoplastic tooth organ in the cultured mandibular explants of MINT deficient mice. From the initiation to cap stage, the differences between mutants and wild-type molars were more and more distinguished histologically. In the MINT-deficient mandibular explants, the tooth germ was reduced in the overall size and lacked enamel knot, with abnormal dental lamina and collapsed stellate reticulum. Furthermore, the BrdU incorporation experiment showed that the proliferation activity was significantly reduced in MINT-deficient dental epithelium. Our results suggest that MINT plays an important role in tooth development, in particular, epithelial morphogenesis.