Effects of Solidago canadensis L. on mineralization-immobilization turnover enhance its nitrogen competitiveness and invasiveness.

The effects of exotic plants on soil nitrogen (N) transformations may influence species invasion success. However, the complex interplay between invasive plant N uptake and N transformation in soils remains unclear. In the present study, a series of 15N-labeled pot experiments were carried out with Solidago canadensis L. (S. canadensis), an invasive plant, and the Ntrace tool was used to clarify the preferred inorganic N form and its effects on soil N transformation. According to the results, nitrate-N (NO3--N) uptake rates by S. canadensis were 2.38 and 2.28 mg N kg-1 d-1 in acidic and alkaline soil, respectively, which were significantly higher than the ammonium-N (NH4+-N) uptake rates (1.76 and 1.56 mg N kg-1 d-1, respectively), indicating that S. canadensis was a NO3--N-preferring plant, irrespective of pH condition. Gross N mineralization rate was 0.41 mg N kg-1 d-1 in alkaline soil in the presence of S. canadensis L., which was significantly lower than that in the control (no plant, CK, 2.44 mg N kg-1 d-1). Gross autotrophic nitrification rate also decreased from 5.95 mg N kg-1 d-1 in the CK to 0.04 mg N kg-1 d-1 in the presence of S. canadensis in alkaline soil. However, microbial N immobilization rate increased significantly from 1.09 to 2.16 mg N kg-1 d-1, and from 0.02 to 2.73 mg N kg-1 d-1 after S. canadensis planting, in acidic and alkaline soil, respectively. Heterotrophic nitrification rate was stimulated in the presence of S. canadensis to provide NO3--N to support the N requirements of plants and microbes. The results suggested that S. canadensis can influence the mineralization-immobilization turnover (MIT) to optimize its N requirements while limiting N supply for other plants in the system. The results of the present study enhance our understanding of the competitiveness and mechanisms of invasion of alien plants.

Improvement of Astragalin on Spermatogenesis in Oligoasthenozoospermia Mouse Induced by Cyclophosphamide.

More than 40% of infertile men are diagnosed with oligoasthenozoospermia and the incidence is still rising, but the effective treatments are not been found until now. Astragalin, one of the main active ingredients in traditional Chinese medicine, may be effective in the treatment of oligoasthenozoospermia. This study investigated the pharmacological effects of astragalin for treatment of oligoasthenozoospermia in male mice, induced by cyclophosphamide (CTX). Male mice were intraperitoneally injected by CTX (50 mg/kg), and astragalin (30 mg/kg) was given via oral gavage once daily. RNA-seq analysis highlighted astragalin upregulated gene expression of anti-apoptosis (AKT1and BCL2-XL), cell proliferation (ETV1, MAPKAPK2, and RPS6KA5) and synthesis of testosterone (STAR, CYP11A1, and PRKACB), but downregulated gene expression of cell apoptosis (BAD, BCL-2, CASPASE9, and CASPASE3) in mouse testis. Astragalin also significantly reversed the reduction in body weight, reproductive organs index, and sperm parameters (sperm concentration, viability, and motility) induced by CTX, and restored testicular abnormal histopathologic morphology induced by CTX. Furthermore, astragalin dramatically rescued the gene expression related to spermatogenesis (AKT1, BCL-2, CASPASE9, CASPASE3, MAPKAPK2, RPS6KA5, STAR, and PRKACB), and increased the level of testosterone by improving related proteins (STAR, CYP11A1, PRKACB) for oligoasthenozoospermia induced by CTX. In conclusion, astragalin may be a potential beneficial agent for oligoasthenozoospermia by increasing the testosterone levels in testis.