Temporal Dynamics of Antioxidant Defence System in Relation to Polyamine Catabolism in Rice under Direct-Seeded and Transplanted Conditions

Six rice cultivars viz. PR120, PR116, Feng Ai Zan, PR115, PAU201 and Punjab Mehak 1 under the direct-seeded and transplanted conditions were used to investigate the involvement of antioxidative defence system in relation to polyamine catabolism in temporal regulation of developing grains. Activities of ascorbate peroxidase （APx）, guaiacol peroxidase （GPx）, catalase （CAT）, superoxide dismutase （SOD）, polyamine oxidases （PAO） and contents of ascorbate, a-tocopherol, proline and polyamines increased gradually until mid-milky stage and then declined towards maturity stage under both planting conditions. The transplanted condition led to higher activities of antioxidative enzymes （APx, GPx and CAT） and contents of ascorbate, a-tocopherol and proline whereas the direct-seeded condition had elevated levels of PAO and SOD activities and contents of polyamines, lipid peroxide and hydrogen peroxide. Cultivars Feng Ai Zan and PR120 exhibited superior tolerance over other cultivars by accumulating higher contents of ascorbate, a-tocopherol and proline with increasing level of PAO and SOD activities under the direct-seeded condition. However, under the transplanted condition PR116 and PAU201 showed higher activities of antioxidative enzymes with decreasing content of lipid peroxide. Therefore, we concluded that under the direct-seeded condition, enhancements of polyamines content and PAO activity enabled rice cultivars more tolerant to oxidative stress, while under the transplanted condition, antioxidative defence with decreasing of lipid peroxide content was closely associated with the protection of grains by maintaining membrane integrity during rice grain filling. The results indicated that temporal dynamics of H2O2 metabolic machinery was strongly up-regulated especially at the mid-milky stage.

Application of autologous peripheral blood stem cell transplantation in children with malignant tumor

Objective To investigate if low dose total body irradiation (TBI, 6.0- 9.0 Gy) combined with intensified chemotherapy followed by autologous peripheral blood stem cell transplantation results in better survival in children with refractory leukemia or solid tumors.Methods Twenty-one children with malignant tumors were included in this study. There were 14 males and 7 females aged 3.5- 12 years. Underlying disease included high-risk acute lymphoblastic leukemia (ALL, CR1 in 3 children and CR2 in 5 children), acute myeloblastic leukemia (AML, 9 children), nonHodgkin' s lymphoma stage Ⅳ (2 children), and neuroblastoma stage Ⅳ (2 children). The peripheral hematopoietic stem cells were collected six to eleven months after complete response, mobilized with high dose chemotherapy alone or combined with GM-CSF or G-CSF. The conditioning regimen consisted of chemotherapy with two to three combinations of the following drugs: cyclophosphamide,arabinosylcytosine, McNU, etopside, and Idarubicin on the basis of TBI (6.0-9.0Gy). A mean of (1.8 ± 0.5) × 108/kg autologous mononuclear cells were transplanted. The patients were followed up after transplantation.Results Severe bone marrow suppression occurred in all patients around day + 7. Peripheral white blood cell count decreased to 0 in all patients at day + 4.8 ± 2.9, and platelet count decreased to less than 20× 109/L at day + 9.0 ± 2.6. Successful engraftment was achieved in 21 patients, but four died of infection at day + 17, + 20, + 31 and + 67, respectively. Recovery of white blood cell (WBC) to 10 × 109/L, absolute neutrophil count to 0.5 × 109/L, platelet count to 20 × 109/L occurred on 21 ± 12,26± 13, and 27 ± 10 days, respectively. During the follow up period, three patients relapsed at + 5months, + 1.5 years, and + 2 years 10 months, respectively. One patient died of intracranial hemorrhage at +8 months. Thirteen patients had event-free survival for 2 - 12 years, with a mean of 6.7±3.4 years.Conclusion Our preliminary data suggest that myeloablative therapy with low dose TBI (6.0 - 9.0 Gy)combined with intensified chemotherapy followed by autologous paripheral blood stem cell transplantation might be associated with favorable results in children with refractory leukemia or solid tumors.

TSC1 enables plastid development under dark conditions, contributing to rice adaptation to transplantation shock

Since its domestication from wild rice thousands of years ago, rice has been cultivated largely through transplantation. During transplantation from the nursery to the paddy field, rice seedlings experience transplantation shock which affects their physiology and production.However, the mechanisms underlying transplantation shock and rice adaptation to this shock are largely unknown. Here,we isolated a transplant-sensitive chloroplast-deficient（tsc_1）rice mutant that produces albino leaves after transplantation.Blocking light from reaching the juvenile leaves and leaf primordia caused chloroplast deficiencies in transplanted tsc_1 seedlings. TSC_1 encodes a noncanonical adenosine triphosphate-binding cassette（ABC） transporter homologous to At NAP_（14） and is of cyanobacterial origin. We demonstrate that TSC_1 controls plastid development in rice under dark conditions, and functions independently of light signaling.However, light rescued the tsc_1 mutant phenotype in a spectrum-independent manner. TSC_1 was upregulated following transplantation, and modulated the iron and copper levels, thereby regulating prolamellar body formation during the early P_4 stage of leaf development. Therefore, TSC_1 is indispensable for plastid development in the absence of light,and contributes to adaptation to transplantation shock.Our study provides insight into the regulation of plastid development and establishes a framework for improving recovery from transplantation shock in rice.