Transcriptome Analysis of the Cytokinin Response in Medicago truncatula

Zhixiang Zhou,Haicong Liu,Cuina Ma,Yuehui Chao,Liebao Han 한국식물학회 2020 Journal of Plant Biology Vol.63 No.3

As an important legume plant, Medicago truncatula is a preeminent model for the study of the processes of nitrogen fxation, symbiosis, and legume genomics. The regulatory mechanism of the cytokinin response has been studied in many plants, such as rice, Arabidopsis, tomato, and barley, but information about regulatory pathways and genes involved in the cytokinin response in Medicago truncatula is notably limited. In this study, to better understand the cytokinin response in Medicago truncatula, transcriptome analysis of seedlings grown with 6-benzylaminopurine or lovastatin was performed using RNASeq. In this study, 3627 and 3093 transcripts were diferentially expressed in cytokinin-induced/control (Cyto/Ctrl) and cytokinin-inhibited/control (Inh/Ctrl) groups, respectively, and diferentially expressed genes were tested by quantitative real-time PCR (qRT-PCR). Analysis of the cytokinin response in Medicago truncatula revealed a large number of transcripts involved in signal transduction, metabolic process, secondary metabolite biosynthesis, transport and catabolism, growth and development, defense mechanisms, and transcription. There were 43 transcription factor families, including 1845 transcription factor (TF) genes with 2147 TF transcripts, as detected by RNA-Seq. Additionally, 216 TF genes with 220 transcripts were diferentially expressed in Cyto/Ctrl, and 185 TF genes with 189 transcripts were in Inh/Ctrl. A total of 289 and 260 DETs involved in biosynthesis, metabolism, and transduction of plant hormones were identifed in the Cyto/Ctrl and Inh/ Ctrl groups, respectively. Furthermore, 15 transcripts, including A-ARR, IPT, and CKX, were demonstrated to play roles in cytokinin regulation or signal transduction. These fndings were associated with the cytokinin response in other plants. The resulting data provide the frst cytokinin transcriptome analysis in Medicago truncatula. Further analysis and identifcation of cytokinin-regulated transcripts or signal transduction transcripts may help to elucidate the regulatory mechanisms governing the cytokinin response in Medicago truncatula.

Effects of cyclic loads on viscoelastic behavior of brain tissue on the implanting trajectory of STN-DBS

Zhixiang Huang,Chunyang Pan,Panling Huang,Jun Zhou,Xueen Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

During deep brain stimulation of the sub-thalamic nucleus (STN-DBS), frequently adjusting the position of the cannula may lead to changes in tissue viscoelasticity. To investigate the mechanical properties of tissue on implant path at repeated loads, three cyclic tension and relaxation tests were carried out at 10 % and 20 % strains. Results indicated that white matter was about 25 %-140 % stiffer than gray matter. Within 20 % strain, the natural viscoelasticity of tissue was not affected by the repeated tension. Whereas at 20 % strain, irreversible internal structure rearrangements occurred at the first relaxation due to the persistent strain action, and almost 60 % of the attenuation modulus generated in the initial 5 s of the process, which leads to a softer transformation of the tissue. Further simulated puncture experiments revealed that an irreversible depression occurred when the cerebral hemisphere was subjected to a constant pressure of cannula for 5 s.

Immobilization and Performance of Penicillin G Acylase on Magnetic Ni_0.7Co_0.3Fe₂O₄@SiO₂-CHO Nanocomposites

( Zhixiang Lv ),( Qingmei Yu ),( Zhou Wang ),( Ruijiang Liu ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.6

Magnetic Ni_0.7Co_0.3Fe₂O₄ nanoparticles that were prepared via the rapid combustion process were functionalized and modified to obtain magnetic Ni_0.7Co_0.3Fe2O₄@SiO₂-CHO nanocomposites, on which penicillin G acylase (PGA) was covalently immobilized. Selections of immobilization concentration and time of fixation were explored. Catalytic performance of immobilized PGA was characterized. The free PGA had greatest activity at pH 8.0 and 45 ℃ while immobilized PGA’s a ctivities p eaked at p H 7.5 and 4 5 ℃. Immobilized PGA had better thermal stability than free PGA at the range of 30-50 ℃ for different time intervals. The activity of free PGA would be 0 and that of immobilized PGA still retained some activities at 60 ℃ after 2 h. V_max and K_m of immobilized PGA were 1.55 mol/min and 0.15 mol/l, respectively. Free PGA’s V_max and K_m separately were 0.74 mol/min and 0.028 mol/l. Immobilized PGA displayed more than 50% activity after 10 successive cycles. We concluded that immobilized PGA with magnetic Ni_0.7Co_0.3Fe₂O₄@SiO₂-CHO nanocomposites could become a novel example for the immobilization of other amidohydrolases.

Antioxidant enzyme activity and microRNA are associated with growth of Poa pratensis callus under salt stress

Luo Hongsong,Zhou Zhixiang,Song Guilong,Yao Hongxiang,Han Liebao 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.4

Kentucky bluegrass (Poa pratensis L.) is an important species of turfgrass that is commonly planted on golf courses and landscapes all over the world. It is sensitive to salt stress; however, details relating to its molecular mechanisms of salt resistance are not available. We, therefore, analyzed the changes in growth, antioxidant enzyme activity, and microRNA expression in the callus 1 week after treatment with 200 mM NaCl for 12 h, 24 h, 48 h, 96 h, and 144 h. The results demonstrated that callus growth declined and thiobarbituric acid-reactive substance production and cell membrane permeability increased. Treatment with salt increased ascorbate peroxidase, glutathione reductase, superoxide dismutase, catalase, peroxidase, and polyphenol oxidase activity. Changes in the expression levels of microRNAs were observed under salt treatment. The expression of miR162, miR173, miR391, miR408, miR773, and miR857 increased by 70% after 24 h of salt treatment, after which it declined to a level similar to that of the control. The expression level of miR775 and miR827 decreased by 20% after 24 h, and then further decreased by 80% after 144 h. The expression level of miR841 increased by 50% after 24 h of salt treatment, and then stabilized. In contrast, salt treatment increased the expression of the auxin response factors ARF6, ARF8, ARF10, and ARF16 in the callus from 12 to 144 h of salt treatment, during which the expression increased twofold. Gene expression analysis indicated that salt-responsive gene families were regulated by microRNAs in the callus under salinity stress. The activity of antioxidant enzymes is also changing. MiR841 is considered to be a positive regulator of antioxidant enzyme biosynthesis. The present investigation elucidates the manner in which P. pratensis responds to salt stress in the callus, and could be used to inform further studies on the molecular mechanisms of stress tolerance.

Cracking of a prefabricated steel truss-concrete composite beam with pre-embedded shear studs under hogging moment

Yinhui Wang,Yanmei Gao,Zhixiang Zhou,Dong Liu 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5

To avoid the cracks of cast-in-place concrete in shear pockets and seams in the traditional composite beam with precast decks, this paper proposed a new type of prefabricated steel truss-concrete composite beam (ab. PSTC beam) with pre-embedded shear studs (ab. PSS connector). To study the initial cracking load of concrete deck, the development and distribution laws of the cracks, 3 PSTC beams were tested under hogging moment. And the crack behavior of the deck was compared with traditional precast composite beam, which was assembled by shear pockets and cast-in-place joints. Results show that: (i) the initial crack appears on the deck, thus avoid the appearance of the cracks in the traditional shear pockets; (ii) the crack of the seam appears later than that of the deck, which verifies the reliability of epoxy cement mortar seam, thus solves the complex structure and easily crack behavior of the traditional cast-in-place joints; (iii) the development and the distribution laws of the cracks in PSTC beam are different from the conventional composite beam. Therefore, in the deduction of crack calculation theory, all the above factors should be considered.