Allelopathic mechanism of pyrogallol to Microcystis aeruginosa PCC7806 (Cyanobacteria): From views of gene expression and antioxidant system

Pyrogallol is a potent allelochemical on Microcystis aeruginosa, but its allelopathic mechanism is not fully known. In order to explore this mechanism, gene expressions for prx, mcyB, psbA, recA, grpE, fabZ under pyrogallol stress were studied, and activities of the main antioxidant enzymes were also measured. The results showed that expression of grpE and recA showed no significant change under pyrogallol stress, while psbA and mcyB were up-regulated at 4 mg L-1. Both prx and fabZ were up-regulated even under exposure to 1 mg L-1 pyrogallol concentration. The activities of superoxide dismutase (SOD) and catalase (CAT) were enhanced under pyrogallol stress. Levels of malodialdehyde (MDA) at 2 and 4 mg L-1 pyrogallol were significantly higher than those of the controls. It was concluded that oxidant damage is an important mechanism for the allelopathic effect of pyrogallol on M. aeruginosa. (c) 2009 Elsevier Ltd. All rights reserved.

Growth and antioxidant system of Escherichia coli in response to microcystin-RR

Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. The toxic effects of microcystins on animals and plants have been well studied. However, the reports about the effects of microcystins on microbial cells are very limited. In present paper, Escherichia coli was undertaken to determine the effect of microcystin-RR. These results suggested that microcystin-RR could prolong the growth of E. coli when exposed to high concentrations of microcystin-RR and cause the accumulation of ROS and induce the oxidant stress for a short time. The antioxidant system protects E. coli from oxidative damage.

Prenatal exposures to persistent organic pollutants as measured in cord blood and meconium from three localities of Zhejiang, China

Prenatal exposures to persistent organic pollutants were assessed using the levels of PCBs and organochlorine pesticides (OCPs) measured in cord blood and meconium samples from Luqiao and two other localities of the Zhejiang province in China. Luqiao is a town with the largest site for disassembly of PCB-containing obsolete transformers and electrical waste in China. The other two localities Pingqiao (100 km NW of Luqiao) and Lin'an (500 km NW of Luqiao) are towns without known electronic or electrical waste sites. A total of 23 PCB congeners (including 12 dioxin-like) and 6 OCPs were measured using the traditional GC-mu ECD technique. Micro-EROD bioassay was additionally used to measure TCDD-based TEQ levels of the 12 dioxin-like PCBs. Significant correlations were found between the TEQs measured by the two methods, supporting the application of micro-EROD as a practical toot for complementing the chemical analysis. The data showed that beta-HCH, p,p'-DDE, and 6 PCB congeners (101, 138 153, 180, 183, and 187) were the predominant pollutants, with PCB 138 being the best indicator (predictor) for total PCB levels. Cord blood and meconium from Luqiao have higher levels of PCBs than those from the other two localities, suggesting that a disassembly site for electronic and electric waste would provide an environment for greater exposure to these chemicals. The cord blood or meconium levels of beta-HCH, though likewise considerably high, were comparable in the three localities. Similar findings were observed for p,p'-DDE. Pollution by these OCPs might have come from past use of agricultural pesticides in the three localities. (c) 2007 Published by Elsevier B.V.

Growth and antioxidant system of the cyanobacterium Synechococcus elongatus in response to microcystin-RR

Microcystins, one type of the cyanobacterial toxins, show a broad range of hazardous effects on other organisms. Most of the researches on the toxic effects of microcystins have involved in animals and higher plants. Little work, however, has been done on evaluating the mechanisms of microcystin toxicity on algae. In this study, the toxicological effects of microcystin-RR (MC-RR) on the cyanobacterium Synechococcus elongatus were investigated. For this purpose, six physio-biochemical parameters (cell optical density, reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST)) were tested in algal cells when exposed to 100 mug(-1) microcystin-RR. The results showed that the growth of Synechococcus elongatus ( expressed as optical density) was significantly inhibited compared with the control. At the same time, the treated algae exhibited a pronounced increase in production of ROS and MDA after 6 days exposure to microcystin-RR. Signi. cant changes in GSH levels and GSH-Px, GSH activities were also detected in algal cells, with higher values being observed in the toxin treated algae after 6 days exposure. GST activities in the treated algae exhibited a decline after exposure and rapid augmentation on day 3, thereafter, they kept at a high level when compared to the control group. GSH contents and GSH-Px activities were also significantly raised in the toxin-treated algae cells from day 3, but they showed a sharp decrease on day 4, which was the onward of cell proliferation. These results suggested that oxidative stress manifested by elevated ROS levels and MDA contents might be responsible for the toxicity of microcystin to Synechococcus elongatus and the algal cells could improve their antioxidant ability through the enhancement of enzymatic and non-enzymatic preventive substances.

Infraciliature and myoneme system of Campanella umbellaria (Protozoa, Ciliophora, Peritrichida)

The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes. (C) 2004 Wiley-Liss, Inc.

大蹼铃蟾皮肤分泌物中βγ-CAT对血液和心血管系统作用及机制研究

非晶状体βγ-晶状体蛋白(non-lens βγ-crystallin, α-亚基)和三叶因子(trefoil factor, β-亚基) 复合物（non-lens βγ-crystallin and trefoil factor complex, 缩写为βγ-CAT）是从大蹼铃蟾皮肤中分离、纯化的一种新型蛋白, 具有促进细胞迁移、伤口愈合功能，同时还可通过核定位、调节转录因子和炎症相关蛋白诱导细胞脱落、凋亡。βγ-CAT对心血管和血液系统的作用和机制还不清楚。本研究的目的在于深入研究这些问题，为人类重大疾病的研究提供新思路。 首先，我们利用各种整体动物模型，研究了βγ-CAT对心血管系统和血液系统的影响。结果发现βγ-CAT可对白细胞、红细胞、血小板、肝细胞、肾细胞和心血管系统产生毒理作用。βγ-CAT可导致白细胞计数、红细胞计数和血小板计数减少、低血压、心律失常、心肌细胞轻度水肿、部分肺泡淤血、炎症细胞浸润肺泡壁、肝细胞水样变性、肾小管水肿、肾小球淤血和脾脏淤血、高钾血症、血糖升高、转氨酶和乳酸脱氢酶升高。我们推测βγ-CAT造成实验动物死亡的主要原因是心功能衰竭、高钾血症和白细胞毒素效应。 其次，为研究βγ-CAT对血管的效应，我们用兔胸主动脉进行了一系列的实验。结果表明，βγ-CAT可引起兔胸主动脉环剂量依赖性收缩，半数有效浓度为（EC50）10 nM; α-肾上腺素能受体阻断剂（酚妥拉明）和5-羟色胺受体阻断剂（S006）不能抑制βγ-CAT的血管收缩效应。因此，我们认为，整体实验观察到的低血压不是由于血管舒张造成的，而是由于βγ-CAT对心肌了产生了抑制效应，并且，βγ-CAT产生的血管收缩效应是通过新的途径引起的。 最后，我们把βγ-CAT导致兔死亡的原因归结为心血管系统衰竭，因为，一方面βγ-CAT抑制心肌使每搏量减少，另一方面它可收缩动脉使心脏的后负荷增加，从而导致重要器官、组织灌注不良而死亡。但导致心功能衰竭的机制还不清楚，于是，我们进行了离体心脏灌流、内皮细胞培养、细胞因子测定、免疫组化、凋亡实验，试图阐明导致动物心力衰竭的机制。首先，我们在离体心脏灌流装置上以恒压和恒流的灌流模式来研究βγ-CAT的心肌变力效应。接下来，我们用高钾去除冠脉血管内皮细胞，以评估内皮细胞在βγ-CAT对心肌的直接效应。最后，我们用βγ-CAT刺激培养的心内皮细胞和主动脉内皮细胞，之后检测细胞因子的释放；并用免疫组化的方法定位冠脉内皮和心肌细胞细胞因子的释放和对这些细胞的凋亡效应。实验一的结果表明，βγ-CAT导致心力衰竭的部分原因是由于βγ-CAT引起的冠脉血管收缩造成；实验二的结果表明，βγ-CAT引起的心力衰竭是内皮依赖的。实验三检测到心内皮、主动脉内皮和冠脉内皮释放TNF-α（TNF-α），高浓度的βγ-CAT还可诱导冠脉内皮凋亡，但不引起心肌细胞凋亡。综上所述，我们认为，冠脉内皮在βγ-CAT引起的心力衰竭中具有较大的贡献，通过冠脉内皮释放细胞因子（如TNF-α）作用于心肌细胞，从而导致收缩能力降低，引起心力衰竭。

System error removal and structure optimization based on Fizeau interferometer

In the process of interferometric testing, the measurement result is influenced by the system structure, which reduces the measurement accuracy. To obtain an accurate test result, it is necessary to analyze the test system, and build the relationship between the measurement error and the system parameters. In this paper, the influences of the system elements which include the collimated lens and the standard surface on the interferometric testing are analyzed, the expressions of phase distribution and wavefront error on the detector are obtained, the method to remove some element errors is introduced, and the optimization structure relationships are given. (C) 2006 Elsevier GmbH. All rights reserved.

Detection of serum and mucosal antibody production and antibody secreting cells (ASCs) in large yellow croaker (Pseudosciaena crocea) following vaccination with Vibrio harveyi via different routes

The kinetics of mucosal and serum antibody response is well as antibody secreting cells (ASCs) production were studied in large yellow croaker following vaccination with inactivated Vibrio harveyi by different routes: oral administration. intraperitoneal (IP) injection and immersion. Indirect ELISA was used to measure the antibody level in serum and cutaneous mucus, and ELISPOT was used to monitor the ASCs derived from gill, blood and head kidney. The data demonstrated that IP injection resulted in the highest antibody levels in the systemic circulation, whereas immersion induced significant antibody levels in mucous. As for the ASCs response, IP injection induced high numbers of ASCs in the head kidney and blood; oral intubation only induced a slight ASCs response in the head kidney: immersion induced a much stronger ASCs response in the gill. These results indicate that mucosal antibodies following immersion immunization are independent of a systemic response and more sensitive, since it could be triggered earlier than serum antibodies. The mucosal antibodies following IP injection immunization may depend oil a systemic immune response. The protective effects of the three vaccination methods were compared by challenging with live V. harveyi. Survival of the three groups of vaccinated fish varied front 40 to 60%. while 100% mortality was found in control fish. Compared with IP and oral vaccination, immersion stimulated higher specific antibody titers in the mucosal system and achieved similar protection, so it is in effective and efficient method for immunizing a large number of fish against V harveyi (C) 2008 Elsevier B.V. All rights reserved.

Electronic states of a two-dimensional electron system in a lateral superlattice and a perpendicular magnetic field

The electronic state of a two-dimensional electron system (2DES) in the presence of a perpendicular uniform magnetic field and a lateral superlattice (LS) is investigated theoretically. A comparative study is made between a LS induced by a spatial electrostatic potential modulation (referred to as a PMLS) and that induced by a spatial magnetic-field modulation (referred ro asa MMLS). By utilizing a finite-temperature self-consistent Hartree-Fock approximation scheme; the dependence of the electronic state on different system parameters (e.g., the modulation period, the modulation strength, the effective electron-electron interaction strength, the averaged electron density, and the system temperature) is studied in detail. The inclusion of exchange effect is found to bring qualitative changes to the electronic state of a PMLS, leading generally to a nonuniform spin splitting, and consequently the behavior of the electronic state becomes similar to that of a MMLS. The Landau-level coupling is taken into account, and is found to introduce some interesting features not observed before. It is also found that, even in the regime of intermediate modulation strength, the density dependence of the spin splitting of energy levels, either for a PMLS or a MMLS, can be qualitatively understood within the picture of a 2DES in a perpendicular magnetic field with the modulation viewed as a perturbation. [S0163-1829(97)02248-0].

Research for a clean and large throughput differential pumping system

The research is to design a differential pumping system not only to achieve the pressure transition with a large throughput, but also to achieve a clean system without back-oil. In the paper, the pressure in differential stages is calculated; the differential pumping system design and equipment choice are introduced; the tests of Molecular/Booster Pump (MBP), a new kind of molecular-drag pump with large throughout and clean vacuum are described and the system experimental result and analysis are presented.