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Our previous study indicated that a chiral compound 071031B was a novel serotonin and noradrenaline reuptake inhibitor with superior antidepressant activity compared to duloxetine. The present study aimed to investigate chiral pharmacology differences of 071031B enantiomers, S-071031B and R-071031B, and disclose mechanisms underlying the behavioral differences based on target profiles and pharmacokinetic profiles. In vivo behavioral tests indicated that S-071031B was more potent than R-071031B in two depression models (the forced swimming test in mice and rats) and two pain models (the acetic acid-induced writhing and formalin tests in mice). In vitro assays revealed that both S-071031B and R-071031B showed high affinity for human serotonin transporters and norepinephrine transporters with equal potency, and showed consistently equipotent inhibitory effects on serotonin and norepinephrine uptake. Pharmacokinetic studies demonstrated that oral availability and hepatic metabolism, rather than pH stability, intestinal transport, and plasma binding, contributed to enantiomers’ behavioral differences. Based on these findings, it is suggested that S-071031B is a more active enantiomer, and the differential pharmacokinetic profiles, but not target affinity, contribute to differences of S-071031B and R-071031B in behavioral pharmacology. Moreover, current PK-PD study may provide positive exploration for chiral antidepressants development.

Rice false smut has become an increasingly serious disease in rice (Oryza sativa L.) production worldwide. The typical feature of this disease is that the fungal pathogen Ustilaginoidea virens (Uv) specifically infects rice flower and forms false smut ball, the ustiloxin‐containing ball‐like fungal colony, of which the size is usually several times larger than that of a mature rice seed. However, the underlying mechanisms of Uv‐rice interaction are poorly understood. Here, we applied time‐course microscopic and transcriptional approaches to investigate rice responses to Uv infection. The results demonstrated that the flower‐opening process and expression of associated transcription factors, including ARF6 and ARF8, were inhibited in Uv‐infected spikelets. The ovaries in infected spikelets were interrupted in fertilization and thus were unable to set seeds. However, a number of grain‐filling‐related genes, including seed storage protein genes, starch anabolism genes and endosperm‐specific transcription factors (RISBZ1 and RPBF), were highly transcribed as if the ovaries were fertilized. In addition, critical defense‐related genes like NPR1 and PR1 were downregulated by Uv infection. Our data imply that Uv may hijack host nutrient reservoir by activation of the grain‐filling network because of growth and formation of false smut balls.

Gametophyte development is an important process in flowering plants. Seeds are the primary organs for harvesting, and therefore spikelet fertility is especially vital for rice yield. Here, we report the characterization and genetic mapping of a novel rice male and female sterile mutant, mfs1, which was generated from a transgenic line of japonica rice variety Zhonghua 9. Anther transverse sections indicate that the microspores in these plants were abnormally degenerated at the meiotic leptotene stage, while the tapetum layer was not degenerated and remained present; therefore, no functional pollen grains formed in the mutant anther locules. In addition, the majority of mutant embryo sacs did not undergo differentiation or the differentiation was incomplete, resulting in the absence of functional embryo sac formation. Genetic analysis of three F2 populations indicated that the mutant phenotype was controlled by a single recessive gene. The mutant phenotype was confirmed by linkage analysis to be not due to a foreign T-DNA insertion. A map-based cloning strategy was employed to map the mutant gene, and, finally, the mfs1 locus was mapped to a 99-kb physical interval between simple sequence repeat markers RM12585 and D051 on rice chromosome 2. Sequence analysis indicates that 11 rice candidate genes are located in this region, including three encoded putative proteins and eight encoded known proteins, such as transcription factors having WRKY and zinc finger domains, a ubiquitin fusion degradation protein, chaperone protein clpB 1, a two-component response regulator, the ZOS2-04-C2H2 zinc finger protein, a peptidase of the T1 family and a protein kinase.