Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex...Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor, we experimentally paired the competition of one Brachionus angularis clone against three Brachionus ealyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction, while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence, but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment, while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density, it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary, higher mixis investment promoted resting egg production before being excluded and thus promised a long- term benefit. In conclusion, our results suggest that mixis investment, to some extent, favored the excluded inferior competitor under fierce competition or some other adverse conditions.展开更多
OBJECTIVE: To detect the expression of basic fibroblast growth factor (bFGF) in human ocular tissues, and to assess the effect of bFGF on the proliferation of human cataract lens epithelial cells (LECs) and its correl...OBJECTIVE: To detect the expression of basic fibroblast growth factor (bFGF) in human ocular tissues, and to assess the effect of bFGF on the proliferation of human cataract lens epithelial cells (LECs) and its correlation with age. METHODS: Enucleated eyes were subjected to immunostaining for bFGF protein. Human cataract LECs were cultured in vitro, and treated with bFGF for 48 hr. Proliferation was estimated by the positive area ratio of proliferating cell nuclear antigen (PCNA) in immunohistochemistry. RESULTS: bFGF protein was found in various human ocular tissues. bFGF stimulated human cataract LEC proliferation, and there was an age-related decrease in responsiveness of human cataract LECs to bFGF (P展开更多
基金Supported by the National Natural Science Foundation of China(No.30970349)
文摘Sexual reproduction adversely affects the population growth of cyclic parthenogenetic animals. The density-dependent sexual reproduction of a superior competitor could mediate the coexistence. However, the cost of sex may make the inferior competitor more vulnerable. To investigate the effect of sexual reproduction on the inferior competitor, we experimentally paired the competition of one Brachionus angularis clone against three Brachionus ealyciflorus clones. One of the B. calyciflorus clones showed a low propensity for sexual reproduction, while the other two showed high propensities. The results show that all B. calyciflorus clones were excluded in the competition for resources at low food level. The increased food level promoted the competition persistence, but the clones did not show a clear pattern. Both the cumulative population density and resting egg production increased with the food level. The cumulative population density decreased with the mixis investment, while the resting egg production increased with the mixis investment. A trade-off between the population growth and sexual reproduction was observed in this research. The results indicate that although higher mixis investment resulted in a lower population density, it would not determinately accelerate the exclusion process of the inferior competitor. On the contrary, higher mixis investment promoted resting egg production before being excluded and thus promised a long- term benefit. In conclusion, our results suggest that mixis investment, to some extent, favored the excluded inferior competitor under fierce competition or some other adverse conditions.
文摘OBJECTIVE: To detect the expression of basic fibroblast growth factor (bFGF) in human ocular tissues, and to assess the effect of bFGF on the proliferation of human cataract lens epithelial cells (LECs) and its correlation with age. METHODS: Enucleated eyes were subjected to immunostaining for bFGF protein. Human cataract LECs were cultured in vitro, and treated with bFGF for 48 hr. Proliferation was estimated by the positive area ratio of proliferating cell nuclear antigen (PCNA) in immunohistochemistry. RESULTS: bFGF protein was found in various human ocular tissues. bFGF stimulated human cataract LEC proliferation, and there was an age-related decrease in responsiveness of human cataract LECs to bFGF (P
