Effect of transient forebrain ischemia-reperfusion on the binding of brain-derived neurotrophic factor promoters to histone deacetylase 3 in hippocampus of rat and its mechanism / 中国生物制品学杂志

Transient forebrain ischemia-reperfusion(I/R);Brain-derived neurotrophic factor(BDNF);Histone deacetylase 3(HDAC3);Hippocampus@#Objective To evaluate the effect of transient forebrain ischemia-reperfusion(I/R)on the binding of brainderived neurotrophic factor(BDNF)promoters to histone deacetylase 3(HDAC3)in the hippocampus of rat and investigate its mechanism.Methods The I/R model of SD rats(I/R group)was established by Pulsinelli four-vessel clamping method,and sham operation group(Sham group)was set at the same time,which were observed for the survival of neurons in the hippocampus of rats by Nissl staining,detected for the binding of BDNF promoters(Bdnf-p1,Bdnf-p2,Bdnf-p4 and Bdnf-p6)to HDAC3 by chromatin immunoprecipitation(ChIP)and determined for the expression of brain derived neurotrophic factor antisense(BDNF-AS)by qPCR.Results Compared with Sham group,the quantity of neurons in hippocampal CA1 region of rats decreased significantly in I/R group,while those in CA3 region and DG region showed no significant changes.The binding levels of Bdnf-p1 and Bdnf-p2 to HDAC3 in hippocampal CA1 region decreased significantly in I/R Group(t = 2.575 and 2.241 respectively,each P<0.05),while there was no significant difference in the binding levels of Bdnf-p4 and Bdnf-p6 to HDAC3(t = 1.033 and 0.348 respectively,each P>0.05);The binding levels of Bdnf-p1 and Bdnf-p2 to HDAC3 in CA3 region increased significantly(t = 12.600 and 3.191,P<0.001 and<0.05,respectively),while the binding level of Bdnf-p6 to HDAC3 decreased significantly(t = 4.029,P<0.05)and no significant difference was observed in the binding level of Bdnf-p4 to HDAC3(t = 0.175,P>0.05);In DG region,the binding level of each BDNF promoter to HDAC3 showed no significantly difference(t = 0.630 ～ 1.687,each P>0.05).Meanwhile,the expression level of BDNF-AS in hippocampal CA1 region of rats decreased significantly(t = 2.560,P<0.05),but increased significantly in hippocampal CA3 and DG regions(t = 3.543 and 3.637 respectively,each P<0.01)in I/R group.Conclusion I/R showed a significant effect on the binding level of BDNF promoter to HDAC3 in rat hippocampus,which may play a role by changing the expression level of BDNF-AS.

The Putative Methyltransferase TlLAE1 Is Involved in the Regulation of Peptaibols Production in the Biocontrol Fungus Trichoderma longibrachiatum SMF2.

The biocontrol fungus Trichoderma longibrachiatum SMF2 secretes a large quantity of peptaibols that have been shown to have a range of biological activities and therefore great application values. However, the mechanism of the regulatory expression of peptaibols is still unclear. The putative methyltransferase LaeA/LAE1 is a global regulator involved in the biosynthesis of some secondary metabolites in filamentous fungi. In this study, we demonstrated that the ortholog of LaeA/LAE1 in the biocontrol fungus T. longibrachiatum SMF2, TlLAE1, plays an important role in the regulation of peptaibols production. Deletion of Tllae1 resulted in a slight negative impact on mycelial growth, and a significant defect in conidial production. Deletion of Tllae1 also compromised the production of peptaibols to a large degree. Further analyses indicated that this defect occurred at the transcriptional level of the two synthetases-encoding genes, tlx1 and tlx2, which are responsible for peptaibols production. By contrast, constitutive expression of Tllae1 in T. longibrachiatum SMF2 led to 2-fold increased peptaibols production, suggesting that this is a strategy to improve peptaibols production in Trichoderma fungi. These results demonstrate the important role of LAE1 in the regulation of peptaibols production in T. longibrachiatum SMF2.

Enhancing peptaibols production in the biocontrol fungus Trichoderma longibrachiatum SMF2 by elimination of a putative glucose sensor.

Trichoderma spp. are main producers of peptide antibiotics known as peptaibols. While peptaibols have been shown to possess a range of biological activities, molecular understanding of the regulation of their production is largely unclear, which hampers the production improvement through genetic engineering. Here, we demonstrated that the orthologue of glucose sensors in the outstanding biocontrol fungus Trichoderma longibrachiatum SMF2, TlSTP1, participates in the regulation of peptaibols production. Deletion of Tlstp1 markedly impaired hyphal growth and conidiation, but significantly increased peptaibols yield by 5-fold for Trichokonins A and 2.6-fold for Trichokonins B. Quantitative real-time polymerase chain reaction analyses showed that the increased peptaibols production occurs at the transcriptional levels of the two nonribosomal peptide synthetase encoding genes, tlx1 and tlx2. Transcriptome analyses of the wild type and the Tlstp1 mutant strains indicated that TlSTP1 exerts a regulatory effect on a set of genes that are involved in a number of metabolic and cellular processes, including synthesis of several other secondary metabolites. These results suggest an important role of TlSTP1 in the regulation of vegetative growth and peptaibols production in T. longibrachiatum SMF2 and provide insights into construction of peptaibol-hyperproducing strains through genetic engineering.

Anatomy of leaf abscission in the Amur honeysuckle (Lonicera maackii, Caprifoliaceae): a scanning electron microscopy study.

Lonicera maackii (Rupr.) Maxim. (Amur honeysuckle) is native to Asia and an important ornamental in China. However, the anatomy of leaf abscission (shedding) in L. maackii had not been studied previously. Such work is needed not only because knowledge of the leaf abscission process is important for a horticultural species like L. maackii but also because leaf abscission is probably the least understood abscission process, as it occurs so rapidly. Therefore, our objective was to use scanning electron microscopy (SEM) to examine the progression of leaf abscission in L. maackii at the cellular level. L. maackii branches with leaves were regularly collected in Beijing, China over the 2-month period in which leaves abscise, and examined with SEM. We found that, unlike in model species, the cortex is involved in abscission, forming an "abaxial gap." We discovered that there is no discrete abscission zone prior to the onset of abscission and that no cell divisions precede abscission. An abscission zone did become evident well after the abscission process had begun, but its cells were enlarged, not constricted as in typical abscission zones. In the abaxial gap, intact cells separated at their middle lamella, but in the abscission zone, cell separation involved the entire wall, which is not typical. We did observe expected mechanical fission of vascular tissues. While the leaf abscission process we observed in L. maackii has similarities with model systems, aspects deviate from the expected.

[Effects of argon atmosphere at high pressure on electron temperature of laser-induced Cu plasmas].

Copper plasma was induced with a high energy neodymium glass laser(0-25J) beam ablating the Cu target in argon atmosphere. It was observed that the line intensity of the emission spectra increases when the ambient pressure(0.1-0.5 MPa) rises. In order to study the enhancement mechanism, with the model of local thermodynamic equilibrium, the electron temperature was measured in argon atmosphere. The experimental results showed that electron temperature increases as the pressure rises. In addition, spatially resolved electron temperature was measured in Ar atmosphere at 0.1, 0.3, 0.5 MPa.

[Enhancement effect of argon atmosphere at high pressure on radiation intensity of laser-induced soil plasmas].

In the present paper, the effects of argon atmosphere at high pressure (0. 2-1.1 MPa) on the radiation intensity of the plasma induced by a high energy neodymium glass laser (energy -30 J, pulse width 0.7 ms) were studied by recording the photograph and spectra of the plasma as well as measuring the ablated mass. The experimental results show that the volume of the plasma was compressed, the temperature increased, and the lightness enhanced significantly when pressure was raised. Under our experimental condition, the radiation intensities of the plasmas were enhanced with the increase in the gas pressure; but the ablated mass of the sample decreased. The measured results are discussed, combined with the process of the experiment.