Mutation of Protoporphyrinogen IX Oxidase Gene Causes Spotted and Rolled Leaf and Its Overexpression Generates Herbicide Resistance in Rice.

Protoporphyrinogen IX (Protogen IX) oxidase (PPO) catalyzes the oxidation of Protogen IX to Proto IX. PPO is also the target site for diphenyl ether-type herbicides. In plants, there are two PPO encoding genes, PPO1 and PPO2. To date, no PPO gene or mutant has been characterized in monocotyledonous plants. In this study, we isolated a spotted and rolled leaf (sprl1) mutant in rice (Oryza sativa). The spotted leaf phenotype was sensitive to high light intensity and low temperature, but the rolled leaf phenotype was insensitive. We confirmed that the sprl1 phenotypes were caused by a single nucleotide substitution in the OsPPO1 (LOC_Os01g18320) gene. This gene is constitutively expressed, and its encoded product is localized to the chloroplast. The sprl1 mutant accumulated excess Proto(gen) IX and reactive oxygen species (ROS), resulting in necrotic lesions. The expressions of 26 genes associated with tetrapyrrole biosynthesis, photosynthesis, ROS accumulation, and rolled leaf were significantly altered in sprl1, demonstrating that these expression changes were coincident with the mutant phenotypes. Importantly, OsPPO1-overexpression transgenic plants were resistant to the herbicides oxyfluorfen and acifluorfen under field conditions, while having no distinct influence on plant growth and grain yield. These finding indicate that the OsPPO1 gene has the potential to engineer herbicide resistance in rice.

LPS1, Encoding Iron-Sulfur Subunit SDH2-1 of Succinate Dehydrogenase, Affects Leaf Senescence and Grain Yield in Rice.

The iron-sulfur subunit (SDH2) of succinate dehydrogenase plays a key role in electron transport in plant mitochondria. However, it is yet unknown whether SDH2 genes are involved in leaf senescence and yield formation. In this study, we isolated a late premature senescence mutant, lps1, in rice (Oryza sativa). The mutant leaves exhibited brown spots at late tillering stage and wilted at the late grain-filling stage and mature stage. In its premature senescence leaves, photosynthetic pigment contents and net photosynthetic rate were reduced; chloroplasts and mitochondria were degraded. Meanwhile, lps1 displayed small panicles, low seed-setting rate and dramatically reduced grain yield. Gene cloning and complementation analysis suggested that the causal gene for the mutant phenotype was OsSDH2-1 (LOC_Os08g02640), in which single nucleotide mutation resulted in an amino acid substitution in the encoded protein. OsSDH2-1 gene was expressed in all organs tested, with higher expression in leaves, root tips, ovary and anthers. OsSDH2-1 protein was targeted to mitochondria. Furthermore, reactive oxygen species (ROS), mainly H2O2, was excessively accumulated in leaves and young panicles of lps1, which could cause premature leaf senescence and affect panicle development and pollen function. Taken together, OsSDH2-1 plays a crucial role in leaf senescence and yield formation in rice.

[Retrospective and comparative analysis of therapy for degenerative chronic discogenic low back pain with end plate Modic changes with discography and intradiscal injection blockage].

OBJECTIVE: To evaluate the prognosticating effects of discography and intradiscal injection blockage for patients with degenerative chronic discogenic low back pain and end plate Modic changes when posterior lumbar interbody fusion (PLIF) was adopted. METHODS: Patients who received diagnostic discography for suspected degenerative discogenic low back pain were recruited. A total of 60 patients (42 males and 18 females) with positive discography and end plate Modic changes at a single level were enrolled in the study and allocated into Groups A and B: Group A was both positive sign of discography and negative sign of intradiscal injection blockage two weeks later, which further was subdivided into Group A1 (Modic I endplate change) and Group A2 (Modic II endplate change). Group B was both positive sign of discography and intradiscal injection blockage two weeks later, which further was subdivided into Group A1 (Modic I endplate change) and Group A2 (Modic II endplate change). There were 15 cases in each subgroup, with a mean age of 43.2 years old (29 to 62 years old). The lumbar decompression combined with interbody fusion was performed for these patients. The clinical outcome of each patient was evaluated and recorded by using the VAS and ODI before operation and at 24 months after the procedure. The bone fusion state was evaluated by both dynamic X-ray and CT reconstruction films. RESULTS: There was no statistical difference of the scales of VAS and ODI before operation.Compared with the scales before operation, although the scales of VAS and ODI of both group A and group B at 24 months after the procedure were significantly improved, the scales of both VAS and ODI of group B were significantly superior to group A. The statistics analysis showed that comparing the improvement rate of VAS and ODI before and after operation, group B was significantly superior to group A, but there was no obviously correlations between the type of Modic endplate change and the the improvement rate of VAS and ODI. CONCLUSION: The combination the discography with intradiscal injection blockage before operation would effectively prognosticate the therapy of posterior lumbar interbody fusion. There was no obviously correlations between the type of Modic endplate change and the improvement rate of VAS and ODI.

[A model of acute compression spinal cord injury by a mini-invasive expandable balloon in goats].

OBJECTIVE: To establish a reproducible and manipulable model of acute spinal cord compression injury in large mammals so as to provide a technical and experimental platform for the repair and reconstruction of spinal cord injury (SCI). METHODS: A total of 15 adult male goats, weighting 35 - 45 kg, were selected. After intravenous anesthesia, a model of acute spinal cord compression injury was established with the balloon of kyphoplasty through mini-open laminotomy. The animals were divided into 4 groups, i.e. 3 in group A and 4 each in groups B, C and D. Goats in group A received mini-open laminotomy without insertion of balloon. In group B, balloons were surgically positioned within the T10-T11 spinal canal but not inflated. The spinal cords of goats in group C were partially compressed by inflating the balloon to approximately 30% of anterior/posterior diameter of vertebral canal. In group D, the balloon was inflated to occupy approximately 90% of canal on a lateral view. X-ray and thin-section computed tomography (CT) scans were used to determine the balloon location. CT scans were also used to calculate the magnitude of balloon inflation and the degree of spinal cord compression within vertebral canal. Improved Tarlov motor function grade test and somatosensory evoked potentials (SSEP) were employed to evaluate the goat neurofunction 24 hours before and 7 days after surgery. RESULTS: Dye volumes of 0, 1.26 ± 0.18 and 2.82 ± 0.20 ml were injected into the balloon to produce spinal occupancies of 0%, 33% ± 2% and 89% ± 4% on X-ray and CT scan. There was a significant dose response for the different levels of injury, with reduced conduction of somatosensory evoked potentials and impaired mobility 7 days after injury. CONCLUSION: A model of acute spinal cord injury by a tunable compression with a mini-invasive balloon in goats is a useful experiment model of spinal cord injury. It may simulate the clinical situations of acute SCI.

[Characterisation of a rice dwarf and twist leaf 1 (dtl1) mutant and fine mapping of DTL1 gene].

Plant height is one of the most important agronomic traits, which determines grain yield. By a largescale screening of our mutant population, we identified a dwarf with twisty leaf mutant (dwarf and twist leaf 1, dtl1). Besides dwarf with twisty leaf, dtl1 also showed reduced tiller number and sterile phenotypes. Based on the internode length of dtl1, this mutant belongs to the nl type of dwarfing phenotype. Physiological assay with two phytohormones, gibberellin (GA), and brassinosteroid (BR), suggested that dtl1 was neither deficient nor insensitive to GA and BR. Genetic analysis showed that the phenotype of dtl1 was controlled by a single recessive gene. Using F2 population derived from a cross between dtl1 and an indica cultivar Taichung Native 1, the DTL1 gene was narrowed down to a 70.4 kb between two SSR markers, RM25923 and RM6673, on the long arm of chromosome 10, and co-segregated with InDel marker Z10-29, where thirteen open reading frames were predicted without known gene involved in controlling plant height. Thus, the DTL1 gene might be a novel gene which is related to plant height in rice.

[Utility of nickel-titanium shape memory alloys of vertebral body reduction fixator with assisted distraction bar].

OBJECTIVE: To test the nickel-titanium (Ni-Ti) shape memory alloys of vertebral body reduction fixator with assisted distraction bar for the treatment of traumatic and osteoporotic vertebral body fracture. METHODS: A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar was implanted into the compressed fracture specimens through vertebral pedicle with the radiographic monitoring to reduce the collapsed endplate as well as distract the compressed vertebral fracture. Radiographic film and computed tomographic reconstruction technique were employed to evaluate the effects of reduction and distraction. A biomechanic test machine was used to measure the fatigue and the stability of deformation of fixation segments. RESULTS: Relying on the effect of temperature shape memory, such an assembly could basically reduce the collapsed endplate as well as distract the compressed vertebral fracture. And when unsatisfied results of reduction and distraction occurred, its super flexibility could provide additional distraction strength. CONCLUSION: A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar may provide effective endplate reduction, restore the vertebral height and the immediate biomechanic spinal stability. So the above assembly is indicated for the treatment of traumatic and osteoporotic vertebral body fracture.

[An overview of flowering transition in higher plants].

In higher plant, flowering transition represents a crucial transition from the vegetative stage to the reproductive stage in life cycle. This process is controlled by both endogenous and environmental factors. In Arabidopsis thaliana, four pathways, photoperiod pathway, vernalization pathway, autonomous pathway, and GA pathway were involved in flowering control. These flowering transition pathways are shown to be highly conserved in Arabidopsis and other higher plants including rice (Oryza sativa L.). This review summarizes recent progresses on flowering time control.

The implantation of a Nickel-Titanium shape memory alloy ameliorates vertebral body compression fractures: a cadaveric study.

OBJECTIVE: To evaluate the effect of a Nickel-Titanium (Ni-Ti) shape memory alloy in the treatment of vertebral body compression fractures. METHODS: The experimental thoracic-lumbar fracture units were made with adult human fresh-frozen vertebral specimens. A total of 30 fresh-frozen vertebral units were randomly assigned to 3 experimental groups: control group, percutaneous kyphoplasty group (PKP group), and percutaneous Ni-Ti shape memory alloys implant group (Ni-Ti implant group). Vertebral height and ultimate compression load of the vertebral body before and after procedures were measured to determine the restoration of vertebral heights and compressive strength, respectively. RESULTS: The Ni-Ti implant group achieved a vertebrae endplate reduction effect comparable to the PKP group. The vertebral height of the PKP group was restored from 2.01±0.21 cm to 2.27±0.18 cm after procedure, whereas that of the Ni-Ti implant group was restored from 2.00±0.18 cm to 2.31±0.17 cm. The ultimate loads of the vertebrae body of the PKP and the Ni-Ti implant groups were 2880.75±126.17 N and 2888.00±144.69 N, respectively, both of which were statistically significantly higher than that of the control group (2017.17±163.71 N). There was no significant difference in ultimate compression load of vertebrae body between the Ni-Ti implant and PKP groups. CONCLUSIONS: The implantation of Ni-Ti shape memory alloys of vertebral body induced effective endplate reduction, restored vertebral height, and provided immediate biomechanical spinal stability.