Homeobox A10 (HOXA10) is a well-known transcription factor that plays an important role in directing endometrial differentiation and establishing the conditions required for implantation. Interestingly, the expression level of HOXA10 may be associated with litter size. To study the effects of the porcine HOXA10 promoter fragment on the expression of HOXA10 gene in vivo, we generated a transgenic mouse model using pronuclear microinjection, and measured the expression of HOXA10 in the endometrium. There was no difference in the expression level of HOXA10 between transgenic and wild-type mice in the absence of hormone stimulation. However, following treatment with progesterone and estradiol benzoate, the expression level of HOXA10 was significantly increased in transgenic mice compared with that of wild-type mice. Furthermore, the litter size of transgenic females was larger than that of wild-type females (7.02±1.73 vs. 6.48±1.85; P=0.14). Moreover, the difference of litter size was greater in the later parities (7.33±1.62 vs. 6.37±2.02; P=0.08) compared with the first parity (6.76±1.81 vs. 6.61±1.67; P=0.77) between transgenic and wild-type mice. Therefore, our transgenic mouse model provides exciting insights regarding the actions of HOXA10 and its hormone-inducible promoter in vivo. The present study offers valuable proof of principle to develop transgenic pigs with a hormone-inducible promoter regulating HOXA10 to alter litter size.

Potassium is an important nutrient element requiring high concentration for photosynthetic metabolism. The potassium deficiency in soil could inhibit soybean (Glycine max (L.) Merr.) photosynthesis and result in yield reduction. Research on the photosynthetic variations of the different tolerant soyben varieties should provide important information for high yield tolerant soybean breeding program. Two representative soybean varieties Tiefeng 40 (tolerance to K+ deficiency) and GD8521 (sensitive to K+ deficiency) were hydroponically grown to measure the photosynthesis, chlorophyll fluorescence parameters and Rubisco activity under different potassium conditions. With the K-deficiency stress time extending, the net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of GD8521 were significantly decreased under K-deficiency condition, whereas the intercellular CO2 concentration (Ci) was significantly increased. As a contrast, the variations of Tiefeng 40 were almost little under K-deficiency condition, which indicated tolerance to K+ deficiency variety could maintain higher efficient photosynthesis. On the 25th d after treatment, the minimal fluorescence (F0) of GD8521 was significantly increased and the maximal fluorescence (Fm), the maximum quantum efficiency of PSII photochemistry (Fv/ Fm), actual photochemical efficiency of PSII (ΦPSII), photochemical quenching (qP), and electron transport rate of PSII (ETR) were significantly decreased under K+ deficiency condition. In addition, the Rubisco content of GD8521 was significantly decreased in leaves. It is particularly noteworthy that the chlorophyll fluorescence parameters and Rubisco content of Tiefeng 40 were unaffected under K+ deficiency condition. On the other hand, the non-photochemical quenching (qN) of Tiefeng 40 was significantly increased. The dry matter weight of Tiefeng 40 was little affected under K+ deficiency condition. Results indicated that Tiefeng 40 could avoid or relieve the destruction of PSII caused by exceeded absorbed solar energy under K-deficiency condition and maintain natural photosynthesis and plant growth. It was an essential physiological mechanism for low-K-tolerant soybean under K-deficiency stress.

Isoprenoids are a functionally and structurally diverse class of natural organic chemicals. The universal precursors of all isoprenoids, isopentenyl diphosphate and dimethylallyl diphosphate are synthesized through the mevalonate and 2C-methyl- D-erythritol 4-phosphate (MEP) pathways, respectively. Many isoprenoids produced through the MEP pathway play an important role in plant acclimation to different light environments. Eupatorium adenophorum, an invasive weed in China, presents a remarkable capacity to acclimate to various light environments, which constitutes its solid foundation of being a successful invasive species. Thus we aimed at gaining a deeper insight into the regulation of MEP pathway in E. adenophorum to further understand the invasive mechanism. 2C-Methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF or MCS) is an essential enzyme in the MEP pathway. In this paper, a novel IspF gene was cloned and characterized from E. adenophorum. Tissue-specific expression assays revealed a higher expression of EaIspF1 in leaves than in stems and roots. The expression of EaIspF1 was responsive to different light conditions. Some up-regulation of EaIspF1 expression was also found after the treatments with signal compounds and after wounding stress. Interestingly, the over-expression of EaIspF1 in Arabidopsis led to increase carotenoids contents, resulting in an enhanced tolerance to high light. Taken together, these results indicate that the EaIspF1-derived enzyme participates in isoprenoid metabolism and among others, the expression of this gene in E. adenophorum is involved in the regulation of plastidial isoprenoids, which play an important role in acclimation to various light environments.