ABSTRACT
The use of two inhibitors of Mek1/2 and Gsk3β (2i) promotes the generation of mouse diploid and haploid embryonic stem cells (ESCs) from the inner cell mass of biparental and uniparental blastocysts, respectively. However, a system enabling long-term maintenance of imprints in ESCs has proven challenging. Here, we report that the use of a two-step a2i (alternative two inhibitors of Src and Gsk3β, TSa2i) derivation/culture protocol results in the establishment of androgenetic haploid ESCs (AG-haESCs) with stable DNA methylation at paternal DMRs (differentially DNA methylated regions) up to passage 60 that can efficiently support generating mice upon oocyte injection. We also show coexistence of H3K9me3 marks and ZFP57 bindings with intact DMR methylations. Furthermore, we demonstrate that TSa2i-treated AG-haESCs are a heterogeneous cell population regarding paternal DMR methylation. Strikingly, AG-haESCs with late passages display increased paternal-DMR methylations and improved developmental potential compared to early-passage cells, in part through the enhanced proliferation of H19-DMR hypermethylated cells. Together, we establish AG-haESCs that can long-term maintain paternal imprints.
ABSTRACT
A novel method was developed for the determination of the 15+1 European priority polycyclic aromatic hydrocarbons in edible oil by online solid-phase extraction coupled with high performance liquid chromatography-ultraviolet/ fluorescence detection ( online-SPE-HPLC-UV/FL-D ) . The edible oil samples were diluted with isopropyl alcohol, and then filtered. The online extraction was performed on a solid phase extraction ChromSpher Pi column (80 mmí3 mm) and the separation was carried out on a C18 reversed-phase PAH column (250 mmí4. 6 mm i. d, 5μm) using ultraviolet detection at 220 nm and fluorescence detection. Isopropyl alcohol, acetonitrile and water were served as mobile phase in gradient elution. The results showed good linearity for the 15+1 polycyclic aromatic hydrocarbons with all the correlation coefficients (R2)>0. 99. The limits of detection ( LODs ) were between 0. 03 and 12. 23 μg/kg. The recoveries of the sixteen components in the three levels of spiked samples were in the range of 65 . 3%-110 . 5% with the relative standard deviation (RSD, n=6) from 0. 1% to 9. 8%.
ABSTRACT
A method based on HPLC-ICP-MS was established to separate the reaction products of ( ethylenediamine) palladium(Ⅱ) chloride([Pd ( en ) Cl2])and 5’-deoxyguanylic acid ( 5’-dGMP). Two reaction products were detected at pH 8. 0 with 25 mmol/L phosphate buffer solution as chromatography eluent. One was the main product with HPLC retention time of 2. 8 min, the other product’s retention time was 3.2 min. According to ESI-MS(MS/MS) study, m/z=510, 511, 512, 514, 516[M+1]+ parent ions ( abundances same to palladium isotopes) were detected. Further analysis showed that the main product was[Pd( en) ( N1-5’-dGMP) ]. However the other product was hardly to be detected by ESI-MS. By using HPLC-DAD and HPLC-ICP-MS, we found that the two reaction products had the same UV absorption spectra and palladium percentage content. Combined with other groups’research, the other reaction product was deduced as dimmer, trimer or tetramer form of[Pd( en) ( N1-5’-dGMP) ]. Further study revealed that[Pd( en) ( N1-5’-dGMP) ] was easily formed in acid solution while its polymer form was generated in alkaline solution. At pH 6. 0, [Pd(en)(N1-5’-dGMP)] was formed within 12 hours with good stability. Research also revealed that the total amount of two reaction products declined as reaction pH climbed.
ABSTRACT
A method for the simultaneous determination of 34 pesticides in sunflower oil, soybean oil and corn oil was developed. The samples were extracted and purified by a modified QuEChERS method, and then the supernatant was analyzed by on-line gel permeation chromatography-gas chromatography-mass spectrometry ( GPC-GC-MS ) . The linear range was from 0 . 01 to 0 . 2 mg/L with a good correlation coefficients ( r≥0. 9913). The average recoveries of 31 pesticides (except p,p′-DDE, p,p′-DDD, p,p′-DDT. For detail, please reference to section 3 . 6 ) ranged from 70 . 3% to 115 . 4%, 69 . 5% to 112 . 6% and 70 . 2% to 116 . 1%spiked at 0. 05 μg/g and 0. 1 μg/g with the relative standard deviations (RSDs, n=6) less than 13. 3%, 13. 5% and 12. 1% in sunflower oil, soybean oil and corn oil samples, respectively. The LODs of this method ranged from 0. 0692 to 2. 28, 0. 0559 to 2. 01 and 0. 0584 to 2. 14μg/kg (S/N=3) in sunflower oil, soybean oil and corn oil samples respectively. The convenient operation and versatility of this method are suitable for the fast screening and detection of 34 pesticide residues in sunflower oil, soybean oil and corn oil.
ABSTRACT
Objective To investigate the water source contamination in Jiangsu Province. Methods Using blowing and arresting device and GC-MS, 90 water samples collected from 15 city drinking water sources in Jiangsu Province were analyzed. Results The main detected compounds were 1, 2-dichloroethane, chloroform, benzene, trichloroethene, toluene, tetrachloroethene, chlorobenzene, m-xylene, p-xylene, o-xylene, 1, 4-dichlorobenzene, 1, 2-dichlorobenzene, 1, 2, 4-trichlorobenzene and hexachlorobutadiene, while 1, 1-dichloroethene, trans-1, 2-dichloroethene, cis-1, 2-dichloroethene, 1, 1, 1-trichloroethane, carbon tetrachloride, bromodichloromethane, dibromochloromethane, bromoform, isopropylbenzene, 1, 2, 3-trichlorobenzene and styrene were not found. The highest concentration of 1, 2-dichloroethane was 27.79 ?g/L, which was close to the limit of surface water. It should be noticed that the detected concentrations of chlorobenzene in water source of district 3 and water source of district 4 were a little higher. Compared with the others, in water source of district 1, water source of district 9 and water source district of 14 a higher concentration of toluene and xylene were detected and the concentration of benzene in water source of district 1, water source of district 2, water source of district 3 and water source district 4 was higher. Only in water source of district 13, none of 25 volatile organic compounds was detected. Conclusion Some drinking water sources have been contaminated by volatile organic compounds in Jiangsu Province.