Objective： To explore the mechanism of native Tibetan fetuses adaptation to hypoxia, we tried to find the different expression genes about mitochondrial function in the native Tibetan placents. Methods： In this stud...Objective： To explore the mechanism of native Tibetan fetuses adaptation to hypoxia, we tried to find the different expression genes about mitochondrial function in the native Tibetan placents. Methods： In this study, the placents of native Tibetan and the high-altitude Hart （ha-Hart） were collected. After the total RNA extraction, the finally synthesized cDNAs were hybridized to mitochondrial array to find the altered expression genes between them. Then, the cytochrome c oxidase 17 （Coxl7）, dynactin 2 （DCTN2, also known as p50）, and vascular endothelial growth factor receptor （VEGFR, also known as KDR） were chosen from the altered expression genes to further verify the array results using the SYBR Green real-time PCR. Because the altered expression genes （such as Cybb and Cox 17） in the array results related to the activities of COXI and COXIV, the placental mitochondria activities of COXI and COXIV were measured to find their changes in the hypoxia. Results： By a standard of≥1.5 or ≤0.67, there were 24 different expressed genes between the native Tibetan and the ha-Han placents, including 3 up-regulated genes and 21 down-regulated genes. These genes were related to energy metabolism, signal transduction, cell proliferation, electron transport, cell adhesion, nucleotide-excision repair. The array results of Cox17, DCTN2 and KDR were further verified by the real-time RT-PCR. Through the mitochondria respiration measurements, the activity of COXI in the native Tibetan placents were higher than that of ha-Han, there was no difference in COXIV activity between them. Conclusion： The altered mitochondrial related genes in the native Tibetan placents may have a role in the high altitude adaptation for fetuses through changing the activity of mitochondrial COX.展开更多
Both tryptophan （Trp） and auxin are essential for plant growth and Trp is a precursor for auxin biosynthesis. Concentrations of Trp and auxin need to be tightly con- trolled to ensure optimal growth and development....Both tryptophan （Trp） and auxin are essential for plant growth and Trp is a precursor for auxin biosynthesis. Concentrations of Trp and auxin need to be tightly con- trolled to ensure optimal growth and development. It has been very difficult to study the homeostasis of these two essential and inter-dependent compounds. Auxin is mainly synthesized from Trp via a two-step pathway using indole- 3-pyruvate （IPA） as the intermediate. Here we used a bacterial Trp oxidase RebO, which does not exist in Ara- bidopsis and which converts Trp to the imine form of IPA, to modulate IPA levels in Arabidopsis. Our results demonstrate that Arabidopsis plants use two strategies to ensure that no excess IPA is made from Trp. IPA is made from Trp by the TAA family of aminotransferases, which we show catalyzes the reverse reaction when IPA level is high. Moreover, excess IPA is converted back to Trp by the YAS1 aminotransferase. We show that the VASl-cat- alyzed reaction is very important for Trp homeostasis. This work not only elucidates the intricate biochemical mech- anisms that control the homeostasis of Trp, IPA, and auxin, but also provides novel tools for further biochemical studies on Tip metabolism and auxin biosynthesis in plants.展开更多
基金Supported by the National Basic Research Program of China (973 Program, 2006CB504101)the National Natural Science Foundation of China (30393131)
文摘Objective： To explore the mechanism of native Tibetan fetuses adaptation to hypoxia, we tried to find the different expression genes about mitochondrial function in the native Tibetan placents. Methods： In this study, the placents of native Tibetan and the high-altitude Hart （ha-Hart） were collected. After the total RNA extraction, the finally synthesized cDNAs were hybridized to mitochondrial array to find the altered expression genes between them. Then, the cytochrome c oxidase 17 （Coxl7）, dynactin 2 （DCTN2, also known as p50）, and vascular endothelial growth factor receptor （VEGFR, also known as KDR） were chosen from the altered expression genes to further verify the array results using the SYBR Green real-time PCR. Because the altered expression genes （such as Cybb and Cox 17） in the array results related to the activities of COXI and COXIV, the placental mitochondria activities of COXI and COXIV were measured to find their changes in the hypoxia. Results： By a standard of≥1.5 or ≤0.67, there were 24 different expressed genes between the native Tibetan and the ha-Han placents, including 3 up-regulated genes and 21 down-regulated genes. These genes were related to energy metabolism, signal transduction, cell proliferation, electron transport, cell adhesion, nucleotide-excision repair. The array results of Cox17, DCTN2 and KDR were further verified by the real-time RT-PCR. Through the mitochondria respiration measurements, the activity of COXI in the native Tibetan placents were higher than that of ha-Han, there was no difference in COXIV activity between them. Conclusion： The altered mitochondrial related genes in the native Tibetan placents may have a role in the high altitude adaptation for fetuses through changing the activity of mitochondrial COX.
基金supported by the NIH(R01GM114660 to YZ)supported by NIH(GM52413to JC)HHMI
文摘Both tryptophan （Trp） and auxin are essential for plant growth and Trp is a precursor for auxin biosynthesis. Concentrations of Trp and auxin need to be tightly con- trolled to ensure optimal growth and development. It has been very difficult to study the homeostasis of these two essential and inter-dependent compounds. Auxin is mainly synthesized from Trp via a two-step pathway using indole- 3-pyruvate （IPA） as the intermediate. Here we used a bacterial Trp oxidase RebO, which does not exist in Ara- bidopsis and which converts Trp to the imine form of IPA, to modulate IPA levels in Arabidopsis. Our results demonstrate that Arabidopsis plants use two strategies to ensure that no excess IPA is made from Trp. IPA is made from Trp by the TAA family of aminotransferases, which we show catalyzes the reverse reaction when IPA level is high. Moreover, excess IPA is converted back to Trp by the YAS1 aminotransferase. We show that the VASl-cat- alyzed reaction is very important for Trp homeostasis. This work not only elucidates the intricate biochemical mech- anisms that control the homeostasis of Trp, IPA, and auxin, but also provides novel tools for further biochemical studies on Tip metabolism and auxin biosynthesis in plants.
