Algal allelopathy is a manifold ecological/physiological phenomenon that is focused on chemical interactions and autotoxicity. We investigated the allelopathic interactions between Karenia mikimotoi and Dunaliella sal...Algal allelopathy is a manifold ecological/physiological phenomenon that is focused on chemical interactions and autotoxicity. We investigated the allelopathic interactions between Karenia mikimotoi and Dunaliella salina in laboratory cultures based on different temperature （15℃, 20℃, and 25℃） and lighting （40,80, and 160 umol/（m2·s）） conditions. The growth of D. salina in bi-algae culture （1：1 size/density） was significantly restrained. The results of cell-free filtrate culture indicate that direct cell-to- cell contact was not necessary in interspecific competition. Further experimental results demonstrated that allelochemicals released from K. miMmotoi were markedly influenced by both temperature （P=0.013） and irradiance （P=0.003）, resulting in different growth characteristics olD. salina in filtrate mediums. Compared with the plateau period, K. mikimotoi exudates in the exponential phase had a stronger short-term inhibition effect on D. salina in normal conditions. A clear concentration-dependent relationship was observed in the effect of allelochemicals released from K. mikimotoi with low-promoting and high-repressing effects on D. Salina in a short time-scale. In addition, allelopathic substances remain stable and effective under high temperature and pressure stress. Many flocculent sediments adhering with D. salina cells were observed in all filtrate mediums, while the quantity and color depended on the original culture conditions.展开更多
Nannochloropsis oceanica promises to be an industrial-level producer of polyunsaturated fatty acids. In this study, the fastest and slowest growing N. oceanica mutants were selected through N-methyl-N＇-nitro-N-nitros...Nannochloropsis oceanica promises to be an industrial-level producer of polyunsaturated fatty acids. In this study, the fastest and slowest growing N. oceanica mutants were selected through N-methyl-N＇-nitro-N-nitrosoguanidine mutation, and two mutant strains and the wild type （WT） subjected to transcriptome profiling. It was found that the 0D680 reads at stationary growth phase of both WT and its mutants were proportional to their cell density, thus indicating their division rate and growth speed during culture. This chemical mutation was effective for improving growth performance, and the fast strain divided faster by upregulating the expression of genes functioning in the cell cycle and downregulating genes involved in synthesis of amino acids, fatty acids, and sugars as well as the construction of ribosome and photosynthetic machinery. However, the relationship among the effected genes responsible for cell cycle, metabolism of fatty and amino acids, and construction of ribosome and photosynthetic machinery remained unclear. Further genetic studies are required for clarifying the genetic/metabolic networks underpinning the growth performance ofN. oceanica. These findings demonstrated that this mutation strategy was effective for improving the growth performance of this species and explored a means ofmicroalgal genetic improvement, particularly in species possessing a monoploid nucleus and asexual reproduction.展开更多
Objective: To elucidate the effects of exogenous basic fibroblast growth factor ( bFGF ) on biological characteristics of rat osteoblasts cultured in vitro.Methods: The osteoblasts isolated from a Sprague-Dawley rat a...Objective: To elucidate the effects of exogenous basic fibroblast growth factor ( bFGF ) on biological characteristics of rat osteoblasts cultured in vitro.Methods: The osteoblasts isolated from a Sprague-Dawley rat and cultured in vitro were treated with different concentrations of bFGF (5-50 ng/ml) respectively. At 24 hours after treatment, the proliferating cell nuclear antigen was measured with immunocytochemistry, alkaline phosphatase ( ALP) activity was determined and the expression of transforming growth factor beta 1 (TGF-β1) was detected to observe the effects of bFGF on growth and differentiation of osteoblasts. Results: bFGF ( 5-50 ng/ml ) could obviously promote the growth of osteoblasts. The intracellular expression of TGF-β, mRNA increased significantly, but the intracellular ALP content decreased.Conclusions: bFGF can obviously stimulate the proliferation of osteoblasts and promote the synthesis of TGF-β1, but cannot promote the differentiation of osteoblasts.展开更多
基金Supported by the State Key Laboratory of Satellite Ocean Environment Dynamics(Second Institute of Oceanography,SOA)(No.SOED1418)the Public Science and Technology Research Funds Projects of Ocean(No.201305027)+1 种基金the National Natural Science Foundation of China(No.91128212)the Research Fund for the Doctoral Program of Higher Education of China(No.20110132120025)
文摘Algal allelopathy is a manifold ecological/physiological phenomenon that is focused on chemical interactions and autotoxicity. We investigated the allelopathic interactions between Karenia mikimotoi and Dunaliella salina in laboratory cultures based on different temperature （15℃, 20℃, and 25℃） and lighting （40,80, and 160 umol/（m2·s）） conditions. The growth of D. salina in bi-algae culture （1：1 size/density） was significantly restrained. The results of cell-free filtrate culture indicate that direct cell-to- cell contact was not necessary in interspecific competition. Further experimental results demonstrated that allelochemicals released from K. miMmotoi were markedly influenced by both temperature （P=0.013） and irradiance （P=0.003）, resulting in different growth characteristics olD. salina in filtrate mediums. Compared with the plateau period, K. mikimotoi exudates in the exponential phase had a stronger short-term inhibition effect on D. salina in normal conditions. A clear concentration-dependent relationship was observed in the effect of allelochemicals released from K. mikimotoi with low-promoting and high-repressing effects on D. Salina in a short time-scale. In addition, allelopathic substances remain stable and effective under high temperature and pressure stress. Many flocculent sediments adhering with D. salina cells were observed in all filtrate mediums, while the quantity and color depended on the original culture conditions.
基金Supported by the National Natural Science Foundation of China(No.31270408)the National High Technology Research and Development Program of China(863 Program)(No.2014AA022001)
文摘Nannochloropsis oceanica promises to be an industrial-level producer of polyunsaturated fatty acids. In this study, the fastest and slowest growing N. oceanica mutants were selected through N-methyl-N＇-nitro-N-nitrosoguanidine mutation, and two mutant strains and the wild type （WT） subjected to transcriptome profiling. It was found that the 0D680 reads at stationary growth phase of both WT and its mutants were proportional to their cell density, thus indicating their division rate and growth speed during culture. This chemical mutation was effective for improving growth performance, and the fast strain divided faster by upregulating the expression of genes functioning in the cell cycle and downregulating genes involved in synthesis of amino acids, fatty acids, and sugars as well as the construction of ribosome and photosynthetic machinery. However, the relationship among the effected genes responsible for cell cycle, metabolism of fatty and amino acids, and construction of ribosome and photosynthetic machinery remained unclear. Further genetic studies are required for clarifying the genetic/metabolic networks underpinning the growth performance ofN. oceanica. These findings demonstrated that this mutation strategy was effective for improving the growth performance of this species and explored a means ofmicroalgal genetic improvement, particularly in species possessing a monoploid nucleus and asexual reproduction.
文摘Objective: To elucidate the effects of exogenous basic fibroblast growth factor ( bFGF ) on biological characteristics of rat osteoblasts cultured in vitro.Methods: The osteoblasts isolated from a Sprague-Dawley rat and cultured in vitro were treated with different concentrations of bFGF (5-50 ng/ml) respectively. At 24 hours after treatment, the proliferating cell nuclear antigen was measured with immunocytochemistry, alkaline phosphatase ( ALP) activity was determined and the expression of transforming growth factor beta 1 (TGF-β1) was detected to observe the effects of bFGF on growth and differentiation of osteoblasts. Results: bFGF ( 5-50 ng/ml ) could obviously promote the growth of osteoblasts. The intracellular expression of TGF-β, mRNA increased significantly, but the intracellular ALP content decreased.Conclusions: bFGF can obviously stimulate the proliferation of osteoblasts and promote the synthesis of TGF-β1, but cannot promote the differentiation of osteoblasts.
