Search

Species with mixed mating systems often demonstrate variable expression of breeding system characteristics and thus represent the opportunity to understand the factors and mechanisms that promote both outcrossed and selfed seed production. Here, we investigate variation in levels of herkogamy (variation in stigma-anther separation distance) in a Puerto Rican population of hummingbird pollinated Gesneria citrina Urban. There is significant variation in herkogamy levels among individuals of this species and stigma-anther separation is negatively associated with the ability to set fruits and seeds in the absence of pollinators. The variation in levels of herkogamy may represent a mechanism to ensure the production of some self-fertilized progeny in the absence of hummingbird pollinators. We also describe a novel breeding system in G. citrina, where stamens elongate over time to reach stigma height, but stamen elongation is accelerated by pollination. These results suggest that once the flowers are pollinated, stamen elongation may favor increased pollen removal and siring success, while the reduction in stigma-anther distance no longer imposes the risk of interference between male and female functions. We discuss our findings of breeding system variation in the context of pollination system evolution in an island setting (Antillean islands). [ABSTRACT FROM AUTHOR]

To reveal the effects of different restoration modes after returning farmland to lake on the soil biological characteristics in Dongting Lake area, the activities of soil saccharase, urease, phosphatase, and catalase at three typical sites (Xiaojicheng, Guanyuan, and Qingshanyuan)were studied. AT the Xiaojicheng site where poplar was planted, soil catalase activity increased significantly, but the activities of other three test enzymes had no significant change. At the Guanyuan site where reed was planted, the activities of soil saccharase and phosphatase had somewhat decrease, and those of urease and catalase had less change. At the Qingshanyuan site where natural water area was restored, the test enzyme activities had less changes except that the phosphatase activity decreased. Correlation analysis showed that the test enzyme activities had significant positive correlations with soil organic matter content (P <0.01), illustrating that the changes in the soil organic matter content under different restoration modes could be the main cause inducing the changes in soil enzyme activity. [ABSTRACT FROM AUTHOR]

Sediment accretion (burial) and nutrient enrichment may exert a synergistic influence on the growth and distribution of macrophytes in floodplain wetlands; however, this phenomenon has rarely been examined. In this study, we investigated the effects of sediment accretion and nutrient enrichment on the growth and vegetative propagation of Phalaris arundinacea within a Carex thunbergii stand (one P. arundinacea ramet within 25 C . thunbergii ramets) using a factorial sediment burial (0, 3, and 6 cm) and nutrient addition (low, medium, and high) experimental design. High sediment burial (6 cm) without nutrient addition decreased the aboveground and total biomass of C. thunbergii but did not affect P. arundinacea , indicating that P. arundinacea is more tolerant to sediment burial than C. thunbergii . Moderate sediment burial (3 cm) with nutrient addition enhanced the aboveground and total biomass of P. arundinacea but did not affect C. thunbergii , indicating that P. arundinacea may gain a growth advantage over C. thunbergii under moderate sedimentation. High sediment burial with nutrient addition increased the number of rhizomes and ramets produced by P. arundinacea but did not affect C. thunbergii , indicating that the relative abundance of P. arundinacea may increase within the Carex community under high sedimentation conditions. Based on these results, it can be concluded that an increased sedimentation rate facilitates the invasion of P. arundinacea into Carex grasslands, and this invasion is further enhanced by nutrient enrichment. Therefore, management measures should be taken to reduce the sediment load and nutrient input to prevent Carex grasslands invasion by P. arundinacea and maintain the ecological function of floodplain wetlands., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision. The reviewer ZD declared a past co-authorship with the author X-SC to the handling editor., (Copyright © 2024 Guo, Zhong, Sun, Song, Liu and Chen.)

Based on multi-temporal Landsat MSS/TM/ETM+ images, and by using decision tree method, this paper extracted the areas of emergent herbaceous wetlands with different water levels in 1989-2011 in the East Dongting Lake, China. The change characteristics and change trends of the emergent herbaceous wetlands areas were investigated based on the DEM data and the daily water level data from the Chenglingji Hydrological Station. The area of the emergent herbaceous wetlands was significantly affected by water level (R2 = 0.875, P < 0.001), presenting a significant linear relationship between the two. Moreover, the emergent herbaceous wetlands area decreased with increasing water level. The higher the water level, the smaller the effects of the water level on the emergent area were. The emergent area changed regularly with water level. In January-July, water level increased, and the emergent area decreased; in July-December, it was opposite. In 1989-2011, the areas of emergent herbaceous wetlands had a continual increase. The newly emergent herbaceous wetlands area was mainly transformed from mudflat. The emergent herbaceous wetlands expansion was the co-effects of the increase of the emergent herbaceous wetlands areas at different elevations, and the rapid expansion of the emergent herbaceous wetlands in low bottomland (22-25 m of Yellow Sea elevation) played the most important role in the expansion. The change of water level at different elevations was the dominant cause for the changes of emergent herbaceous wetlands areas in the East Dongting Lake in the past 20 years.

To reveal the effects of different restoration modes after returning farmland to lake on the soil biological characteristics in Dongting Lake area, the activities of soil saccharase, urease, phosphatase, and catalase at three typical sites (Xiaojicheng, Guanyuan, and Qingshanyuan) were studied. At the Xiaojicheng site where poplar was planted, soil catalase activity increased significantly, but the activities'of other three test enzymes had no significant change. At the Guanyuan site where reed was planted, the activities of soil saccharase and phosphatase had somewhat decrease, and those of urease and catalase had less change. At the Qingshanyuan site where natural water area was restored, the test enzyme activities had less changes except that the phosphatase activity decreased. Correlation analysis showed that the test enzyme activities had significant positive correlations with soil organic matter content (P < 0.01), illustrating that the changes in the soil organic matter content under different restoration modes could be the main cause inducing the changes in soil enzyme activity.

Aim: To study the effect of 5-lipoxygenase inhibitors on the expression of intercellular adhesion molecule-1 (ICAM-1) in melanoma cells., Methods: ICAM-1 protein of human melanoma cell a375 was detected by enzyme-linked immunosorbent, flow cytometry and Western blot analysis. Level of ICAM-1 mRNA in a375 was evaluated by Northern blot analysis. Adhesion of a375 to endothelial cell EC304 was analyzed by isotopic tracing., Results: 5-Lipoxygenase inhibitors nordihydroguaiaretic acid, AA861 and MK886, could suppress the expression of ICAM-1 protein as well as of its mRNA in a375 cells and reduce the adhesion of a375 to EC304., Conclusion: 5-Lipoxygenase inhibitors can inhibit the expression of ICAM-1 in human melanoma cells and may be valuable for treatment of melanoma metastasis.