Construction of the mutants of rice nonspecific lipid transfer protein and expression comparison in two kinds of thioredoxin fusion expression vectors / 生物工程学报

Five structural important residues of rice nonspecific lipid transfer protein LTP110 were mutated by site-directed mutagenesis. Sequence results showed that they were all mutated successfully. After trying various E. coli expression systems, thioredoxin fusion expression system was found to be a proper system to express wild type and mutant LTP110. cDNA sequences encoding wild type LTP110 and the mutants Y17A, P72L, R46A, D43A, C50A were cloned into two kinds of thioredoxin fusion expression vectors. The expression results were compared. In pTrxFus/GI724 expression system, wild type LTP110 and the mutants Y17A, P72L, R46A could be expressed at low level while D43A and C50A could not be expressed normally; in pET32a(+)/BL21 (DE3) trxB- expression system, wild type LTP110 and all mutant proteins could be expressed very well and the levels were higher than that in pTrxFus/GI724 system. LTP110 fusion protein expressed in pET32a(+) vector was purified and its activity was checked by fluorescence labeled fatty acid. Results indicated that the recombinant LTP110 fusion protein has lipid binding activity. This work provides good basis for the further study.

Diffusion tensor tractography of normal and compressed spinal cord:a preliminary study at 3.0 T MR / 中华放射学杂志

Objective To study the feasibility and clinical values of diffusion tensor tractography (DTT)in the spinal cord at 3.0 T MR.Methods Forty patients with spinal cord compression including cervical cord herniation and cervical spondylosis(30 cases),tumors in spinal canal(9 cases)and old injury in cervical vertebrae(1 cases)and 20 healthy volunteers participated in this study.Single-shot spin- echo echo-planar diffusion tensor sequence for tractography of the spinal cord was performed.The fibers of spinal cord were visualized by using fiber tracking software.Results On the DTT maps,the normal spinal cord was depicted as a fiber tract showing color-encoded cephaloeaudally,which indicated anisotropy in the cephalocaudal direction.By setting two ROI,the main spinal cord fiber tracts,such as corticospinal or spinothalamic tract,were visualized.The tracts from two sides of the brain did not completely cross.It was asymmetric in the number of tracts on the two sides in most normal subjects(8/10).The tracts of all patients with cord compression were seen oppressed or damaged in different degrees.The DrrT in patients with cervical spondylosis and extramedullary-intradural neurolemmoma demonstrated that tracts were oppressed but not damaged.The DTT in one ependymoma showed that tract was markedly compressed and slightly damaged.Conclusion DTT is a promising tool for demonstrating the spinal cord tracts and abnormalities,can provide useful information for the localization of compression and evaluation of the impairment extent on the white matter tracts of the spinal cord.