The experimental opportunities provided by the mouse model will facilitate understanding the role of P4 in the regulation of menstruation and help to identify new targets for the clinical intervention of menstrual disorders.

Bletilla striata is an endangered orchid that has been used for millennia as a medicinal herb, in cosmetics and as a horticultural plant. To construct the first nucleotide database for this species and to develop abundant EST-SSR markers for facilitating further studies, various tissues and organs of plants in the main developmental stages were harvested for mRNA isolation and subsequent RNA sequencing. A total of 106,054,784 clean reads were generated by using Illumina paired-end sequencing technology. The reads were assembled into 127,261 unigenes by the Trinity package; the unigenes had an average length of 612 bp and an N50 of 957 bp. Of these unigenes, 67,494 (51.86%) were annotated in a series of databases. Of these annotated unigenes, 41,818 and 24,615 were assigned to gene ontology categories and clusters of orthologous groups, respectively. Additionally, 20,764 (15.96%) unigenes were mapped onto 275 pathways using the KEGG database. In addition, 25,935 high-quality EST-SSR primer pairs were developed from the 15,433 unigenes by MISA mining. To validate the accuracy of the newly designed markers, 87 of 100 randomly selected primers were effectively amplified; 63 of those yielded PCR products of the expected size, and 25 yielded products with significant amounts of polymorphism among the 4 landraces. Furthermore, the transferability test of the 25 polymorphic markers was performed in 6 individuals of two closely related genus Phalaenopsis and dendrobium. Which results showed a total of 5 markers can successfully amplified among these populations. This research provides a comprehensive nucleotide database and lays a solid foundation for functional gene mining and genomic research in B. striata. The developed EST-SSR primers could facilitate phylogenetic studies and breeding.

Progesterone withdrawal triggers endometrial breakdown and shedding during menstruation. Menstruation results from inflammatory responses; however, the role of reactive oxygen species (ROS) in menstruation remains unclear. In this study, we explored the role of ROS in endometrial breakdown and shedding. We found that ROS levels were significantly increased before endometrial breakdown in a mouse menstrual-like model. Vaginal smear inspection, morphology of uterine horns, and endometrial histology examination showed that a broad range of ROS scavengers significantly inhibited endometrial breakdown in this model. Furthermore, Western blot and immunohistochemical analysis showed that the intracellular translocation of p50 and p65 from the cytoplasm into the nucleus was blocked by ROS scavengers and real-time PCR showed that cyclooxygenase-2 (COX-2) mRNA expression was decreased by ROS scavengers. Similar changes also occurred in human stromal cells in vitro. Furthermore, Western blotting and real-time PCR showed that one ROS, hydrogen peroxide (H2O2), promoted translocation of p50 and p65 from the cytoplasm to the nucleus and increased COX-2 mRNA expression along with progesterone maintenance. The nuclear factor κB inhibitor MG132 reduced the occurrence of these changes in human stromal cells in vitro. Viewed as a whole, our results provide evidence that certain ROS are important for endometrial breakdown and shedding in a mouse menstrual-like model and function at least partially via nuclear factor-κB/COX-2 signaling. Similar changes observed in human stromal cells could also implicate ROS as important mediators of human menstruation.