Characterization of nucleosides and nucleobases in natural Cordyceps by HILIC-ESI/TOF/MS and HILIC-ESI/MS.

A method combining hydrophilic interaction chromatography (HILIC) and electrospray ionization mass spectrometry (ESI-MS) was developed for the characterization and determination of natural Cordyceps. Separation was achieved on a Waters Xbridge Amide column with gradient elution. Identification of 15 target nucleosides and nucleobases was based on retention time, UV spectra and mass measurements of the protonated molecules ([M+H]⁺) and main fragment ions (ESI-TOF/MS). Eight non-target compounds were tentatively identified by ESI-TOF/MS. The 15 target compounds were quantified by HILIC-ESI-MS/MS using time-programmed selective ion monitoring or multiple reaction monitoring in positive-ion mode under optimized mass conditions. This technique showed good linearity, repeatability and recovery. This approach was also successfully implemented in the analysis of nucleosides and nucleobases in 12 batches of natural Cordyceps samples that were collected from different regions in China. The developed HILIC-ESI-MS method exhibited clear advantages in identifying and determining highly polar bioactive components in Cordyceps, as well as their quality control.

[Identification of active components in Styela clava by HPLC-eSI-Tof/MS and the study on their HPLC specific chromatograms].

A new method based on high performance liquid chromatography-electrospray ionization time of flight-mass spectrometry (HPLC-ESI-TOF/MS) was developed for the rapid identification of active compounds in Styela clava and the development of its specific chromatograms. Samples were extracted by ultrasonic-assisted extraction, and the extraction conditions were optimized. The developed HPLC-ESI-TOF/MS method was used to identify the components in Styela clava extract, and a specific chromatogram based on HPLC analysis was established. Ten compounds in Styela clava extract have been primary identified by HPLC-ESI-TOF/MS on-line detection combined with literature review. The result of similarity evaluation for specific chromatograms indicated that the quality of different Styela clava samples was not entirely consistent. This method has the advantages of simple operation, rapid measurement and it is a powerful tool for identification of active components in Styela clava and its quality control.

The Circular RNome of Developmental Retina in Mice.

Circular RNAs (circRNAs) represent a class of noncoding RNAs with a wide expression pattern, and they constitute an important layer of the genome regulatory network. To date, the expression pattern and regulatory potency of circRNAs in the retina, a key part of the central nervous system, are not yet well understood. In this study, RNAs from five stages (E18.5, P1, P7, P14, and P30) of mouse retinal development were sequenced. A total of 9,029 circRNAs were identified. Most circRNAs were expressed in different stages with a specific signature, and their expression patterns were different from those of their host linear transcripts. Some circRNAs could act as sponges for several retinal microRNAs (miRNAs). Furthermore, circTulp4 could function as a competitive endogenous RNA (ceRNA) to regulate target genes. Remarkably, silencing circTulp4 in vivo led to mice having a thin outer nuclear layer (ONL) and defective retinal function. In addition, we found that circRNAs were dysregulated at a much earlier time point than that of disease onset in a retinal degeneration model (rd8 mice). In summary, we provide the first circRNA expression atlas during retinal development and highlight a key biological role for circRNAs in retinal development and degeneration.

Molecularly imprinted polymer for selective extraction of domoic acid from seafood coupled with high-performance liquid chromatographic determination.

In this work, a highly selective sample cleanup procedure that combining molecular imprinting technique (MIT) and solid phase extraction (SPE) was developed for the isolation of domoic acid (a fascinating marine toxin) from seafood samples. The molecular imprinting polymer (MIP) for domoic acid was prepared using 1,3,5-pentanetricarboxylic acid as the template molecule instead of domoic acid. 4-Vinyl pyridine was used as the functional monomer and ethylene glycol dimethacrylate was used as the cross-linking monomer. The obtained imprinted polymer showed high affinity to domoic acid and was used as selective sorbent for the SPE of domoic acid from seafood samples. An off-line molecularly imprinted solid phase extraction (MISPE) method followed by high-performance liquid chromatography (HPLC) with diode-array detection for the detection of domoic acid was also established. Good linearity was obtained from 0.5 mg L(-1) to 25 mg L(-1) (R(2)>0.99) with a quantitation limit of 0.1 mg L(-1), which was sufficient to determine domoic acid at the maximum level permitted by several authorities. The mean recoveries of domoic acid from mussel extracts were 93.4-96.7%. It was demonstrated that the proposed MISPE-HPLC method could be applied to direct determination of domoic acid from seafood samples.

[Water-soluble anions of atmosphere on Tianwan nuclear power station].

Three major water-soluble anions (Cl-, SO4(2-) and NO3-) in the atmosphere of the Tianwan nuclear power station in Lianyungang were determined by ion chromatography from June 2005 to May 2006. The results showed that the annual average concentration of Cl-, SO4(2-) and NO3- in the atmosphere of Tianwan nuclear power station was (33.12 +/- 53.63) microg x m(-3), (53.34 +/- 30.34) microg x m(-3) and (8.34 +/- 4.47) microg x m(-3), respectively. The concentrations of the three water-soluble anions showed evident trend of seasonal variation. The concentrations of Cl-, SO4(2-) reached the highest level in summer and the lowest level in winter, while the concentration of NO3- in autumn and winter was higher than those in summer and spring. Meteorological parameters such as wind direction, wind speed, temperature and relative humidity were studied and showed definite influence to the anions concentration of the atmosphere. This is the first simultaneous monitoring of corrosive anions in the atmosphere of Chinese coastal nuclear power plant, and it will provide basis for the prevention of marine atmospheric corrosion, which will ensure the safely operating of our nuclear power industry.

Molecularly imprinted polymer as SPE sorbent for selective extraction of melamine in dairy products.

In this paper, a highly selective sample cleanup procedure combining molecular imprinting and solid-phase extraction (MI-SPE) was developed for the isolation of melamine in dairy products. The molecularly imprinted polymer (MIP) was prepared using melamine as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The melamine imprinted polymer was used as selective sorbent for the solid-phase extraction of melamine from dairy products. An off-line MI-SPE method followed by high-performance liquid chromatography with diode-array detection for the detection of melamine was also established. The mean recoveries of melamine from ultra-heat treatment (UHT) milk and milk powders were 92.9-98.0% and 91.6-102.8%, respectively. Good linearity was obtained from 0.5 microM to 10 microM (r>0.999) with a quantitation limit of 0.5 micromol/L (0.06 ppm) which was sufficient to analyse melamine at the maximum level permitted by U.S. Food and Drug Administration (1 ppm) in dairy products. It was demonstrated that the proposed MI-SPE-HPLC method could be applied to direct determination of melamine in dairy products.