Effects of circadian rhythms of fluctuating temperature on growth and biochemical composition of <Emphasis Type="Italic">Ulva pertusa</Emphasis>

The marcoalga Ulva pertusa was cultured under (20 ± 2)°C, (20 ± 4)°C, (20 ± 6)°C, (20 ± 8)°C and (20 ± 10)°C circadian rhythms of fluctuating temperature conditions, and constant temperature of 20°C was used as the control. The growth rate of macroalga at (20 ± 2)°C, (20 ± 4)°C and (20 ± 6)°C were significantly higher than that at constant temperature of 20°C, while growth rate at (20 ± 8)°C and (20 ± 10)°C were significantly lower than that at constant temperature of 20°C. The growth rate of macroalga was a quadratic function of the thermal amplitude. Such a growth model can be described by G = β ₀ + β ₁(TA) + β ₂(TA)², where G represents the relative growth rate, TA is thermal amplitude in degree Celsius, β ₀ is the intercept on the G axis, and β ₁ and β ₂ are the regression coefficients. The optimal thermal amplitude for the growth of thallus at mean temperature of 20°C was estimated to be ± 3.69°C. Analysis of biochemical composition at the final stages of thaulls growth revealed that diel fluctuating temperature caused various influences (P < 0.05). The content of chlorophyll, protein and total solute carbohydrate at (20 ± 2)°C and (20 ± 4)°C were slightly higher than those at constant temperature of 20°C, however no statistically significant differences were found among them (P > 0.05). While osmolytes (total solute carbohydrate and free proline) at (20 ± 10)°C were significantly higher than that at 20°C (P < 0.05). Therefore, more chlorophyll and carbohydrate production might account for the enhancement in the growth of macroalga at the diel fluctuating temperatures in the present study. Handling editor: S. M. Thomaz     

Insecticidal activity of proteinous venom from tentacle of jellyfish Rhopilema esculentum Kishinouye

Insecticidal activity of proteinous venom from tentacle of jellyfish Rhopilema esculentum Kishinouye was determined against three pest species, Stephanitis pyri Fabriciusa, Aphis medicaginis Koch, and Myzus persicae Sulzer. R. esculentum full proteinous venom had different insecticidal activity against S. pyri Fabriciusa, A. medicaginis Koch, and M. persicae Sulzer. The 48 h LC50 values were 123.1, 581.6, and 716.3 microg/mL, respectively. Of the three pests, R. esculentum full proteinous venom had the most potent toxicity against S. pyri Fabriciusa, and the corrected mortality recorded at 48 h was 97.86%. So, S. pyri Fabriciusa could be a potential target pest of R. esculentum full proteinous venom.     

PA2800 Plays an Important Role in Both Antibiotic Susceptibility and Virulence in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an important human pathogen which causes a variety of infections. P. aeruginosa infections are often difficult to treat due to the pathogen’s resistance to many antibiotics. Previously, it has been reported that a transposon insertion mutant in gene PA2800 of P. aeruginosa PAO1 was more sensitive to tetracycline and ciprofloxacin. Further characterization of this gene, a vacJ homolog, in this study indicated that this gene plays an important role in both antibiotic susceptibility and virulence in P. aeruginosa. The role of PA2800 in antibiotic susceptibility probably signifies its involvement in maintaining outer membrane stability, similar to the role of vacJ in E. coli and Shigella flexneri. However, in contrast to vacJ in other bacteria, PA2800 also affects antibiotic susceptibility by affecting the expression of oprH in P. aeruginosa. As shown by in vivo studies using a Drosophila melanogaster infection model, significantly increased virulence was observed in the PA2800 mutant when compared to the wild type, and such a difference is likely a result of disrupted outer membrane stability and altered expression of znuA in the mutant. The role of PA2800 or vacJ in antibiotic susceptibility and pathogenicity seems to be unique in P. aeruginosa in which it affects both outer membrane stability as well as gene expression.     

Immune Sculpting of Norepinephrine on MHC-I,B7-1, IDO and B7-H1 Expression and Regulation of Proliferation and Invasion in Pancreatic Carcinoma Cells

Background

The sympathetic neurotransmitter Norepinephrine (NE) contributes to tumorigenesis and cancer progression. This study aims to investigate the role of NE in modulating the immune phenotype and allowing pancreatic carcinoma (PC) cells to escape the immune response.

Methods

Varied concentrations of NE and interferon-gamma (IFN-γ) were administrated to MIA PaCa-2 and BxPC-3 cell lines for 48 hours. Proliferation and invasion were then investigated using an MTT assay and a membrane invasion culture system respectively. MHC-I, B7-1, IDO and B7-H1 expression were measured using real-time quantitative RT-PCR, western blotting and immunocytochemistry. The synergistic and time-dependent effects of NE/IFN-γ were also investigated. Adrenergic antagonists were used to identify the relevant target receptor of NE.

Results

The results showed that NE had dose-dependent and time-dependent effects on cell biological processes as well as on the expression of MHC-I, B7-1, IDO and B7-H1. These effects occurred mainly via the β₂-adrenergic receptor. Long-term NE treatment was able to antagonize some of the effects of IFN-γ (after 2 weeks of treatment), but NE and IFN-γ had significant synergistic stimulatory effects on IDO and B7-H1 expression. The residual effects on biological activities lasted for 2 weeks, while the immunophenotypic changes decreased at early time points after treatment.

Conclusions

NE plays important roles in modulating PC cell biological activities and affecting MHC-I, B7-1, IDO and B7-H1 expression in vitro, mainly via the β2-adrenergic receptor (β2-AR) in a time- and dose-dependent fashion. Only at extended treatment durations could NE affect PC cell progression and immune evasion.     

重组L-天冬氨酸-β-脱羧酶融合蛋白复性条件的研究

以本实验室构建保存的天冬氨酸脱羧酶工程菌为研究材料,通过基因表达,对所得到的重组胞内融合表达型天冬氨酸脱羧酶蛋白进行体外复性研究,考察温度、复性液的pH、复性时间、复性液种类等因素对重组天冬氨酸脱羧酶体外复性的影响。结果表明:最佳复性液为pH8.7的Tris-HCl缓冲液,在保温时间2h,温度40℃下,复性效果最好。另外一些pH能达到8.7的缓冲液复性效果都不如Tris-HCl缓冲液。     

对虾-罗非鱼-缢蛏封闭式综合养殖的水质研究

研究了对虾、罗非鱼和缢蛏封闭式综合养殖的环境状况.结果表明,混养各组环境状况总体要优于单养组.实验期间混养组DO的波动幅度略小于单养组,最低值则高于单养组;各混养组COD值和水层细菌数量相互差异不显著,但各混养组均显著低于单养组(t检验,α<0.05),混养围隔水体有机质含量明显低于单养;混养各围隔组中浮游生物生物量、Chl.a均低于单养组,滤食性动物对浮游生物的压制作用明显.在底泥中,混养组N、P的积累量比单养组低39.76%和51.26%,混养组细菌总数则比单养组低7.63%.本研究表明,封闭式综合养殖可以大大减少注入近海的养殖污水的排放量,从而降低对近海水质的污染.