A Peptidoglycan Recognition Protein (PGRP) from Haliotis discus hannai: Possible Roles in Antibacterial Properties

In this study, peptide PGRP (designated HdPGRP) was identified and characterized from the abalone Haliotis discus hannai. Multiple alignments and phylogenetic analyses strongly suggested that HdPGRP is a new member of the PGRP superfamily and belongs to the short PGRP family, similar to peptides from other marine mollusks. The full length of HdPGRP is 1467 bp, encoding a polypeptide of 354 amino acids (aa) with a signal peptide (1~18 aa), an SH3b domain (93~160 aa), a typical PGRP domain (179~322 aa), and an Ami_2 domain (191~322 aa). In addition, four conserved Zn~(2+)-binding sites (H~(209), Y~(255), H~(318), and C~(330)) and five conserved amide-catalysis sites (H~(209), Y~(255), H~(318), T328, and C~(330)) were found in the HdPGRP sequence. In abalone, hdpgrp exhibited different tissue expression patterns, and was strongly expressed in the hepatopancreas, moderately expressed in hemocytes, mantle, and gills, and slightly expressed in muscle. Vibrio anguillarum is one of the main pathogens of H. discus hannai; after V. anguillarum infection, expression of hdpgrp in hemocytes showed a trend of first increasing and then decreasing, reaching a maximum at 24 h. Subsequently, expression of HdPGRP decreased, and there was no significant difference compared with the control group at 72 h, demonstrating that expression of HdPGRP had returned to normal levels. SDS-PAGE results showed that recombinant HdPGRP (rHdPGRP) has a molecular mass of 30 kDa, which is in line with the value predicted for HdPGRP. PGRPs usually have amidase activity, degrading peptidoglycan by hydrolyzing the amide bond that links peptide units to muramic acid residues of glycan strands. rHdPGRP exhibited Zn~(2+)-dependent amidase activity and catalyzed the degradation of insoluble peptidoglycan. In addition, rHdPGRP exhibited significant antibacterial activity against the gram-positive bacterium Micrococcus luteus in the logarithmic phase in the presence of Zn~(2+), indicating that the antibacterial activity of HdPGRP might be dependent on amidase activity. In summary, HdPGRP plays an important role in PGRP-mediated antibacterial mechanisms, especially for eliminating invading bacteria

胸腺肽联合干扰素治疗慢性乙型肝炎临床疗效观察

厦门市科委资助项目!29880

EFFECTS OF THYMOSIN ON CONCENTRATIONS OF CYTOKINE IN SERUM OF PATIENTS WITH CHRONIC HEPATITIS B

目的观察大剂量国产胸腺肽对慢性活动性乙肝患者血清细胞因子的影响，探讨胸腺肽治疗慢性乙肝的机制。方法选择慢性活动性乙肝患者34例，分成两组：胸腺肽组19例，一般护肝组15例。比较观察治疗前后患者血清IFN—α、sIL－2r、TNF，和β2－MG为指标的变化。结果胸腺肽治疗后，患者PBMIFN—α诱生能力较治疗前上升119．99％，血清sIL—2r和TNF含量分别下降了35．56％和41．80％，治疗初期对β2—MG有提升作用。一般护肝组对慢性乙肝患者PBMIFN－α诱生能力和下调血清sIL-2r、TNF的作用弱于胸腺肽，对β2—MG指标没有影响。结论胸腺肽治疗慢性乙肝疗效与促进IFN产生和下调sIL-2r和TNF等多项免疫调节功能有关。Aim To dtudy the effects of high-dose thymosin on the cytokine conentration in serum of the patients with chronic hepatitis B and its therapy mechanism.Methods 34 patients with chronic active hepatitis B were divided into two groups; 19 patients were treated with thymosin and 15 patients with common drugs of protecting liver cells (PLC) .Level changes of IFN-α,sIL-2r, TNF, and β2-MG in the patients' serum were analyzed comparatively before and after treatment.Results After treating of thymosin, ability of induced-producing IFN-αin patients' PBMC was increased 119.99% over before treatment; concentrations of sIL-2r anu TNF in serum were decreased by 33.56% and 41.80%, respectively;and β2-MG in serum were increased in the early days of thymosin treatment.PLC showed similar, weaker effect on IFN-α, sII-2r, and TNF than that thymosin did; but no significant effects on β2-MG. Conclusions Mechanism of thymosin against HBV reproducing is relative to the the effets enhancing IFN-α producing abilities ,downing the serum levels of sIL-β2r and TNF,and so on.厦门市科委资助!Z9880

干旱内陆河灌区节水农业综合技术体系研究与集成

本课题从工程节水、农艺节水、管理节水三个方面,集成了农业高效节水、水肥盐调控、生态保护、监测与管理等关键技术,提出了干旱内陆河灌区农业节水技术集成体系与应用模式。提出了仅需根据水流推进过程确定土壤入渗参数和田面糙率系数的新方法,简化了地面灌溉设计。提出了根据土壤剖面含水率变化估算柽柳生长条件下潜水蒸发的理论方法与数学模型,为解决天然植被实际生态耗水问题提供了简易可行的方法