A cDNA encoding novel type III polyketide synthase (PKS) was cloned and sequenced from young leaves of Chinese club moss Huperzia serrata (Thunb.) Trev. by RT-PCR using degenerated primers based on the conserved sequences of known CHSs, and named as H. serrata PKS2. The terminal sequences of cDNA were obtained by the 3'- and 5'-RACE method. The full-length cDNA of H. serrata PKS2 contained a 1212 bp open reading frame encoding a 46.4 kDa protein with 404 amino acids. The deduced amino acid sequence of H. serrata PKS2 showed 50%-66% identities to those of other chalcone synthase super family enzymes of plant origin. The recombinant H. serrata PKS2 was functionally expressed in Escherichia coli with an additional hexahistidine tag at the N-terminus and showed unusually versatile catalytic potency to produce various aromatic tetraketides, including chalcones, benzophenones, phloroglucinols, and acridones. In particular, the enzyme accepted bulky starter substrates N-methylanthraniloyl-CoA, and carried out three condensations with malonyl-CoA to produce 1, 3-dihydroxy-N-methylacridone. Interestingly, H. serrata PKS2 lacks most of the consensus active site sequences with acridone synthase from Ruta graveolens (Rutaceae).

Objective: To discuss the application effect of relaxing therapy with a decompression ball on anxieties of patients facing tooth extraction. Methods: Totally 72 dental anxieties patients facing tooth extraction were divided into control group and intervention group. Control group was carried out routine nursing, while intervention group was implemented relaxing therapy with a decompression ball on the basic of routine nursing. The changes of anxiety score, blood pressure and heart rate of both groups before and after intervention were compared. Besides, the cooperation of both groups during operation after intervention was compared, too. Results: After intervention, anxiety score of intervention group and control group was 9.92±3.20 and 12.44±3.32 respectively, indicating that the difference had statistical significance (t=-3.272, P<0.05). The difference value of anxiety score was 4.02±2.69 and the control group was 1.56±2.20. There was statistically significant difference of the two groups (t=4.273, P<0.01). The FRANKL behavior score of the cooperation degree during operation was 3.94±0.23 in intervention group and 3.67±0.48 in control group with statistically significant difference (t=3.136, P<0.05). Before and after intervention, there was no statistically significant difference regarding to systolic pressure, diastolic pressure and the heart rate (P>0.05). Conclusions Relaxing therapy with a decompression ball is beneficial to relieve the anxieties of dental patients facing tooth extraction, which can also improve the cooperation degree during operation and ensure the dental treatment carried out smoothly, thus it′s worth to be extended clinically.