Objective To compare perinatal outcomes of the singleton and twin pregnancies , and explore risk factors associated with twin pregnancies. Methods The data of 1 026 patients in single and twin pregnancies treated with IVF/ICSI between January 2014 to March 2015 were retrospectively analyzed. Results The early miscarriage rate and early pregnancy loss rate in the singleton group was significantly higher than the twin group (16% vs 5.41%; 16% vs 6.98%) and the late abortion rate in the singleton group was significantly lower than the twin group (1.93% vs 7.12%), but the total pregnancy loss rate was not significantly different between the groups. The premature delivery rate in the twin group was significantly increased (9.19% vs 41.89%), the term taking-baby-home rate was significantly lower (56% vs 37.89%), but the total taking-baby-home rate was significantly higher in the twin group than the singleton group. The low weight delivery rate in the twin group was significantly increased (1.2% vs 14.8%), but the rate of birth defects was no significantly different between the groups. There were significant differences in age and number of embryo transfer between the two groups. Conclusions Twin pregnancies may increase the risk of late abortion and premature delivery and low weight delivery significantly. Age and number of embryo transfer may be the risk factors for twin pregnancies.

Artemisnin is a novel sesquiterpene lactone with an internal peroxide bridge structure, which is extracted from traditional Chinese herb Artemisia annua L. (Qinghao). Recommended by World Health Organization, artemisinin is the first-line drug in the treatment of encephalic and chloroquine-resistant malaria. In the present study, transgenic A. annua plants were developed by overexpressing the key enzymes involved in the biosynthetic pathway of artemisinin. Based on Agrobacterium-mediated transformation methods, transgenic plants of A. annua with overexpression of both HDR and ADS were obtained through hygromycin screening. The genomic PCR analysis confirmed six transgenic lines in which both HDR and ADS were integrated into genome. The gene expression analysis given by real-time quantitative PCR showed that all the transgenic lines had higher expression levels of HDR and ADS than the non-transgenic control (except ah3 in which the expression level of ADS showed no significant difference compared with control); and the HPLC analysis of artemisinin demonstrated that transgenic A. annua plants produced artemisinin at significantly higher level than non-transgenic plants. Especially, the highest content of artemisinin was found in transgenic line ah70, in which the artemisinin content was 3.48 times compared with that in non-transgenic lines. In summary, overexpression of HDR and ADS facilitated artemisinin biosynthesis and this method could be applied to develop transgenic plants of A. annua with higher yield of artemisinin.

Atropa belladonna L. is the officially medicinal plant species and the main commercial source of scopolamine and hyoscyamine in China. In this study, we reported the simultaneous overexpression of two functional genes involved in biosynthesis of scopolamine, which respectively encoded the upstream key enzyme putrescine N-methyltransferase (PMT; EC 2.1.1.53) and the downstream key enzyme hyoscyamine 6beta-hydroxylase (H6H; EC 1.14.11.11) in transgenic hair root cultures of Atropa belladonna L. HPLC results suggested that four transgenic hair root lines produced higher content of scopolamine at different levels compared with nontransgenic hair root cultures. And scopolamine content increased to 8.2 fold in transgenic line PH2 compared with that of control line; and the other four transgenic lines showed an increase of scopolamine compared with the control. Two of the transgenic hair root lines produced higher levels of tropane alkaloids, and the content increased to 2.7 fold in transgenic line PH2 compared with the control. The gene expression profile indicated that both PMT and H6H expressed at a different levels in different transgenic hair root lines, which would be helpful for biosynthesis of scopolamine. Our studies suggested that overexpression of A. belladonna endogenous genes PMT and H6H could enhance tropane alkaloid biosynthesis.