Effects of ROS and caspase-3-like protein on the growth and aerenchyma formation of Potamogeton perfoliatus stem

Protoplasma - Aerenchyma formation plays an important role in the survival of Potamogeton perfoliatus in submerged environment. To understand the regulatory role of reactive oxygen species (ROS)...     

The Effect of High-Temperature Stress on the Physiological Indexes,Chloroplast Ultrastructure,and Photosystems of two Herbaceous Peony Cultivars

In this study, two herbaceous peony cultivars with different heat tolerances (‘Fenyunu’ FYN low sensitivity and ‘Qiaoling’ QL high sensitivity) were used as research materials. An integrated view of the factors underlying the decrease in photosynthetic rate under high-temperature (HT) stress was provided by analyzing the biochemical parameters, chloroplast ultrastructure, gas-exchange parameters, chlorophyll fluorescence, and modulated 820 nm reflection of herbaceous peony leaves. The results showed that hydrogen peroxide, superoxide anion, malondialdehyde, and electrical conductivity increased significantly, while the photosynthetic pigments content and photosynthetic capacity decreased significantly in QL than in FYN under HT. The contents of soluble sugars and proline increased greatly in FYN than in QL, while the activity of SOD decreased markedly in QL than in FYN after HT. Compared with FYN, the ultrastructure of QL was more seriously disrupted under HT. Chlorophyll fluorescence analysis showed that HT changed the shapes of OJIP curve, resulting in the increase of K phase and J phase. The PSII acceptor side was more damaged than the donor side, and the electron transfer was seriously blocked. The energy flow in the process of light energy absorption, capture, and electron transfer were significantly changed after HT stress. Meanwhile, PSI was also significantly inhibited, and the coordination of both photosystems decreased. The variation of these parameters in FYN was less than that in QL. These results suggested that FYN featured a more heat-tolerance ability as evidenced by the good performances on the antioxidant system, osmoregulatory capacity, and the thermostability of membranes and photosystems.

     

黄瓜子叶扩张与细胞分裂素的关系

BA(benzyl adenine)专一性地促进离体黄瓜子叶的扩张。为了研究 BA 的作用机理,我们采用间接 EIISA 和 HPLC 的方法测定了子叶扩张过程中内源玉米素(Z)和玉米素核苷(ZR)含量的变化。离体黄瓜(Cucumis sativus,津研4号)子叶用10mg/l 的 BA 培养,72小时之后,处理子叶鲜重的增加比对照高70%。Z+ZR 在 BA 处理的子叶中有大量的积累。结果表明 BA 可能诱发了黄瓜子叶中的细胞分裂素生物合成和代谢的某些基因。     

细胞分裂素在离体蒜苔内的运转

离体蒜苔饲喂带~3H 标记的6-苄基腺嘌呤(BA)后在暗中25℃下放置,分别在第3、5、10、15、20天取样,进行放射性物质的分布分析。结果表明:(1)BA 能沿着苔茎大量、长距离地上运,并在顶端的珠蒜中积累;(2)BA 的这种运转具有很强的向顶极性;(3)这种运转是一个平缓而稳定的过程,珠蒜中 BA 的积累与时间成较好的线性关系;(4)顶端的珠蒜对 BA 的上运是必不可少的。根据以上结果,本文对蒜苔内 BA 的运转机理及意义进行了讨论。     

A new strategy for cellulases application in high temperature industrial scenarios with syringic acid assisting

In the process of bioethanol production, more stable and active cellulase in high temperature condition is required. In this study, syringic acid was applied in cellulase hydrolysis system. At 70°C, TvEG3 activity increased 201.36%, CtBglA activity decreased 72.79% by syringic acid. With syringic acid assisting, TvEG3 thermostability was improved, CtBglA thermostability was reduced. Syringic acid scarcely affected CtCBH. In hydrolysis system with the cellulases containing TvEG3, CtCBH, and CtBglA, the reducing sugar yield improved by 28.37% with syringic acid assisting. With the molecular dynamic simulation in syringic acid system, the backbone root-mean-square deviation (RMSD) and the residue root-mean-square fluctuation (RMSF) of TvEG3, CtCBH reduced, while the RMSD and RMSF of CtBglA increased. The reduction in the number of secondary structures, especially α-helix, caused the structure of CtBglA in the presence of syringic acid to collapse at high temperature. More secondary structures in TvEG3 and more α-helix in CtCBH in the presence of syringic acid make them more stable at high temperatures. These means syringic acid can stabilize TvEG3 and CtCBH structure, destabilize CtBglA structure at high temperature. In summary, this study not only provides insight into cellulase hydrolysis at high temperature with syringic acid assisting but also demonstrates the promoting mechanism of syringic acid.     

Development of acute thermotolerance in L929 cells: lack of HSP28 synthesis and phosphorylation.

We investigated the correlation between the development of acute thermotolerance and the phosphorylation, synthesis, and expression of the HSP28 family in murine L929 cells. Following heating at 43 degrees C for 30 min, thermotolerance developed rapidly in exponential-phase cells and reached its maximum 4-9 h after heat shock. Maximal thermal resistance was maintained for 24 h and then gradually decayed. However, heat-induced phosphorylation of HSP28 was not detected. Furthermore, HSP28 synthesis during incubation at 37 degrees C for 12 h following heat shock was not detected by [3H]-leucine labeling followed by two-dimensional polyacrylamide gel electrophoresis. In addition, Northern blots failed to demonstrate expression of the HSP28 gene. Unlike HSP28, the expression of constitutive and inducible HSP70 genes, along with the synthesis of their proteins, was observed during incubation at 37 degrees C after heat shock. These results demonstrate that HSP28 synthesis and its phosphorylation are not required to develop acute thermotolerance in L929 cells.     

Dasymaschalon tibetense (Annonaceae): a new species from China

A new species, Dasymaschalon tibetense, has been described from South Tibet, China. The species is related to D. rostratum, but can be easily distinguished by its rounded apex of fruitlets and its 7.7–9.5 cm long petals.     

A rapid method for determination of Proteus vulgaris with a piezoelectric quartz crystal sensor coated with a thin liquid film

A rapid method for microorganism detection using a piezoelectric quartz crystal sensor (PQC) coated with a thin liquid culture medium film was developed and applied to detect the cell number of Proteus vulgaris. This method employed the viscosity and density response of PQC and utilized the coagulation of gelatine medium solution in which the microorganisms had grown to determine the microorganism indirectly. Three time points (TT₁, DT, TT₂) were obtained from the coagulation curve and were found to be in good linear relationship with the logarithm of the initial number of P. vulgaris in the range 1·3 × 10²−1·3 × 10⁵ cells/ml. The detection was rapid and accurate because the coagulation of the thin liquid culture medium film was quick and the time points in the response curve were sharp and so were easy to determine accurately. The detection time was less than 4 h and only a micro sample was needed. A 5 h preincubation was needed before detection. Some experimental conditions are discussed in detail.