Animal cells require extrinsic cues for growth, proliferation and survival. The propagation of Drosophila imaginal disc cells in vitro, for example, requires the supplementation of fly extract, the composition of whic...Animal cells require extrinsic cues for growth, proliferation and survival. The propagation of Drosophila imaginal disc cells in vitro, for example, requires the supplementation of fly extract, the composition of which remains largely undefined. Here I report the biochemical purification of iron-loaded ferritin as an active ingredient of fly extract that is required for promoting the growth of clone 8 imaginal disc cells. Consistent with an essential role for iron- loaded ferritin in cultured cells, overexpression of ferritin or addition of iron in a nutrient-poor diet increases animal viability and body weight, promotes cell proliferation, and shortens the duration of postembryonic development. Conversely, overexpression of dominant-negative ferritin or addition of iron chelator causes the opposite effects. Fer- ritin mutant flies arrest development at the first-instar larval stage with a severe starvation phenotype reminiscent of that seen in starved larvae. I conclude that iron-loaded ferritin acts as an essential mitogen for cell proliferation and postembryonic development in Drosophila by maintaining iron homeostasis and antagonizing starvation response.展开更多
The kinetochore composition of rat liver cells was studied by indirect immunofluorescence andimmunoblotting using human anti-kinetochore/centromere autoantibodies(ACAs).Besides threemajor antigens(50kD,42 kD and 34 kD...The kinetochore composition of rat liver cells was studied by indirect immunofluorescence andimmunoblotting using human anti-kinetochore/centromere autoantibodies(ACAs).Besides threemajor antigens(50kD,42 kD and 34 kD),ACAs used in this study could also identify those of 32-30 kD and 20 kD in newborn rat liver cells,90 kD in old rat liver cells,37 kD and 32-30 kD inregenerating liver cells.These results indicate that some kinetochore antigen(s)may be related to cellproliferation or specific for different stages of development.展开更多
The development, survivorship and reproduction of Bemisia tabaci B bi otype on eggplant at seven constant temperatures (17, 20, 23, 26, 29, 32 and 35℃) were studied. The developmental periods from egg to adult varied...The development, survivorship and reproduction of Bemisia tabaci B bi otype on eggplant at seven constant temperatures (17, 20, 23, 26, 29, 32 and 35℃) were studied. The developmental periods from egg to adult varied from 48.7 days at 17℃ to 13.9 days at 29℃ and the develo pmental threshold estimated for a generation by linear regression was 12.4℃. The optimum temperature for B. tabaci population growth was 26℃, both extremely low (<17℃) and high temperature (>32℃) delayed the de velopment. Survivorships from egg to adult was 67.3 % at 26℃, 27.6 % and 29.0 % at 35℃ and 17℃ resp ectively. The average longevity of females ranged from 39.6 days at 20℃ to 12.8 days at 35℃. Ovipo sition per female varied from 164.8 eggs at 20℃ to 78.5 eggs at 32℃. Both the longevity and oviposition of B. tabaci females at different temperatures were significantly different ( P < 0.05), and the intrinsic rate of natural increase ( r m ) for B. tabaci at 29℃ was the highest.展开更多
Erythropoiesis is a process during which multipotential hematopoietic stem cells proliferate, differentiate and eventually form mature erythrocytes. Interestingly, unlike most cell types, an important feature of eryth...Erythropoiesis is a process during which multipotential hematopoietic stem cells proliferate, differentiate and eventually form mature erythrocytes. Interestingly, unlike most cell types, an important feature of erythropoiesis is that following each mitosis the daughter cells are morphologically and functionally different from the parent cell from which they are derived, demonstrating the need to study erythropoiesis in a stage-specific manner. This has been impossible until recently due to lack of methods for isolating erythroid cells at each distinct developmental stage. This review summarizes recent advances in the development of methods for isolating both murine and human erythroid cells and their applications. These methods provide powerful means for studying normal and impaired erythropoiesis associated with hematological disorders.展开更多
文摘Animal cells require extrinsic cues for growth, proliferation and survival. The propagation of Drosophila imaginal disc cells in vitro, for example, requires the supplementation of fly extract, the composition of which remains largely undefined. Here I report the biochemical purification of iron-loaded ferritin as an active ingredient of fly extract that is required for promoting the growth of clone 8 imaginal disc cells. Consistent with an essential role for iron- loaded ferritin in cultured cells, overexpression of ferritin or addition of iron in a nutrient-poor diet increases animal viability and body weight, promotes cell proliferation, and shortens the duration of postembryonic development. Conversely, overexpression of dominant-negative ferritin or addition of iron chelator causes the opposite effects. Fer- ritin mutant flies arrest development at the first-instar larval stage with a severe starvation phenotype reminiscent of that seen in starved larvae. I conclude that iron-loaded ferritin acts as an essential mitogen for cell proliferation and postembryonic development in Drosophila by maintaining iron homeostasis and antagonizing starvation response.
基金This work was supported by the National Natural Science Foundation of China
文摘The kinetochore composition of rat liver cells was studied by indirect immunofluorescence andimmunoblotting using human anti-kinetochore/centromere autoantibodies(ACAs).Besides threemajor antigens(50kD,42 kD and 34 kD),ACAs used in this study could also identify those of 32-30 kD and 20 kD in newborn rat liver cells,90 kD in old rat liver cells,37 kD and 32-30 kD inregenerating liver cells.These results indicate that some kinetochore antigen(s)may be related to cellproliferation or specific for different stages of development.
文摘The development, survivorship and reproduction of Bemisia tabaci B bi otype on eggplant at seven constant temperatures (17, 20, 23, 26, 29, 32 and 35℃) were studied. The developmental periods from egg to adult varied from 48.7 days at 17℃ to 13.9 days at 29℃ and the develo pmental threshold estimated for a generation by linear regression was 12.4℃. The optimum temperature for B. tabaci population growth was 26℃, both extremely low (<17℃) and high temperature (>32℃) delayed the de velopment. Survivorships from egg to adult was 67.3 % at 26℃, 27.6 % and 29.0 % at 35℃ and 17℃ resp ectively. The average longevity of females ranged from 39.6 days at 20℃ to 12.8 days at 35℃. Ovipo sition per female varied from 164.8 eggs at 20℃ to 78.5 eggs at 32℃. Both the longevity and oviposition of B. tabaci females at different temperatures were significantly different ( P < 0.05), and the intrinsic rate of natural increase ( r m ) for B. tabaci at 29℃ was the highest.
基金supported by grants from the National Natural Science Foundation of China(814703628117190581272187)
文摘Erythropoiesis is a process during which multipotential hematopoietic stem cells proliferate, differentiate and eventually form mature erythrocytes. Interestingly, unlike most cell types, an important feature of erythropoiesis is that following each mitosis the daughter cells are morphologically and functionally different from the parent cell from which they are derived, demonstrating the need to study erythropoiesis in a stage-specific manner. This has been impossible until recently due to lack of methods for isolating erythroid cells at each distinct developmental stage. This review summarizes recent advances in the development of methods for isolating both murine and human erythroid cells and their applications. These methods provide powerful means for studying normal and impaired erythropoiesis associated with hematological disorders.
