The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analys...The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analyses of SDS and RCK and their respective homologs, and identified their putative orthologs in poplar and rice. Quantitative real-time RT-PCR analysis indicated that rice SDS and RCK are expressed preferentially in young flowers, and transgenic RNAi rice lines with reduced expression of these genes exhibited normal vegetative development, but showed significantly reduced fertility with partially sterile flowers and defective pollens. SDS deficiency also caused a decrease in pollen amounts. Further cytological examination of male meiocytes revealed that the SDS deficiency led to defects in homolog interaction and bivalent formation in meiotic prophase I, and RCK deficiency resulted in defective meiotic crossover formation. These results indicate that rice SDS and RCK genes have similar functions to their Arabidopsis orthologs. Because rice and Arabidopsis, respectively, are members of monocots and eudicots, two largest groups of flowering plants, our results suggest that the functions of SDS and RCK are likely conserved in flowering plants.展开更多
In this paper,incorporating the fertility in the utility function and the production function,an improved Ramsey-Cass-Koopmans(RCK)model with endogenous fertility is obtained.In this model,the fertility can be express...In this paper,incorporating the fertility in the utility function and the production function,an improved Ramsey-Cass-Koopmans(RCK)model with endogenous fertility is obtained.In this model,the fertility can be expressed as a function of per capita capital and per capital consumption.It has been proved that at least one equilibrium point exists and the equilibrium point is unique under a condition.The author discusses the possibility of existing multiple equilibria,their geometrical relationship and explains the economic sense of the main results.展开更多
目的分离人知的 c DNAs。方法采用 RT- PCR自人的肝脏细胞分离到一约 1,2 0 0 bp的 c DNA片段 ,将其克隆测序。结果在这一 c DNA片段中包含了两个开放阅读框架。结论一个开放阅读框架代表与人疱疹病毒大衣壳蛋白同源的多肽 ,另一个代表...目的分离人知的 c DNAs。方法采用 RT- PCR自人的肝脏细胞分离到一约 1,2 0 0 bp的 c DNA片段 ,将其克隆测序。结果在这一 c DNA片段中包含了两个开放阅读框架。结论一个开放阅读框架代表与人疱疹病毒大衣壳蛋白同源的多肽 ,另一个代表与沙门氏菌外膜蛋白展开更多
Large-conductance Ca^(2+)-activated K+channels(BK channels)constitute an key physiological link between cellular Ca^(2+) signaling and electrical signaling at the plasma membrane.Thus these channels are critical to th...Large-conductance Ca^(2+)-activated K+channels(BK channels)constitute an key physiological link between cellular Ca^(2+) signaling and electrical signaling at the plasma membrane.Thus these channels are critical to the control of action potential firing and neurotrans-mitter release in several types of neurons,as well as the dynamic control of smooth muscle tone in resis-tance arteries,airway,and bladder.Recent advances in our understanding of K^(+) channel structure and function have led to new insight toward the molecular mecha-nisms of opening and closing(gating)of these chan-nels.Here we will focus on mechanisms of BK channel gating by Ca^(2+),transmembrane voltage,and auxiliary subunit proteins.展开更多
文摘The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analyses of SDS and RCK and their respective homologs, and identified their putative orthologs in poplar and rice. Quantitative real-time RT-PCR analysis indicated that rice SDS and RCK are expressed preferentially in young flowers, and transgenic RNAi rice lines with reduced expression of these genes exhibited normal vegetative development, but showed significantly reduced fertility with partially sterile flowers and defective pollens. SDS deficiency also caused a decrease in pollen amounts. Further cytological examination of male meiocytes revealed that the SDS deficiency led to defects in homolog interaction and bivalent formation in meiotic prophase I, and RCK deficiency resulted in defective meiotic crossover formation. These results indicate that rice SDS and RCK genes have similar functions to their Arabidopsis orthologs. Because rice and Arabidopsis, respectively, are members of monocots and eudicots, two largest groups of flowering plants, our results suggest that the functions of SDS and RCK are likely conserved in flowering plants.
文摘In this paper,incorporating the fertility in the utility function and the production function,an improved Ramsey-Cass-Koopmans(RCK)model with endogenous fertility is obtained.In this model,the fertility can be expressed as a function of per capita capital and per capital consumption.It has been proved that at least one equilibrium point exists and the equilibrium point is unique under a condition.The author discusses the possibility of existing multiple equilibria,their geometrical relationship and explains the economic sense of the main results.
基金supported in part by the National Institute of General Medical Science of the National Institutes of Health(Grant No.R01GM068523).
文摘Large-conductance Ca^(2+)-activated K+channels(BK channels)constitute an key physiological link between cellular Ca^(2+) signaling and electrical signaling at the plasma membrane.Thus these channels are critical to the control of action potential firing and neurotrans-mitter release in several types of neurons,as well as the dynamic control of smooth muscle tone in resis-tance arteries,airway,and bladder.Recent advances in our understanding of K^(+) channel structure and function have led to new insight toward the molecular mecha-nisms of opening and closing(gating)of these chan-nels.Here we will focus on mechanisms of BK channel gating by Ca^(2+),transmembrane voltage,and auxiliary subunit proteins.
