十六烷基三甲基氯化铵抑制小球藻生长的效应及作用机制

以普通小球藻为受试生物, 采用批量培养方法研究了阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)的抑藻效应,通过营养元素吸收、Zeta电位、酸性磷酸酶和亚显微结构的测定探讨了其作用机制. 结果表明, CTAC浓度在0.1～1 mg/L范围内随浓度升高对小球藻的抑制作用增强, 96 h抑制小球藻生长的半效应浓度(96 h-EC₅₀)为0.18 mg/L. 0.3 mg/L CTAC作用8 d后, 对小球藻生物量的抑制率为70.7%, 对氮和铁单位吸收量的抑制率分别为83.9%和86.2%, 藻细胞Zeta电位从-12.5 mV提高至-6.7 mV, 酸性磷酸酶相对活力降至23.1%, 藻细胞出现明显的质壁分离、蛋白核扭曲和溶酶体膨胀等现象. 根据实验结果分析, CTAC提高了藻细胞Zeta电位,抑制了小球藻对氮和铁的吸收, 影响磷的代谢并引起亚显微结构的改变.     

环境因子对湖泊沉积物碱性磷酸酶活性的影响

文章对云龙湖和骆马湖2种不同类型湖泊沉积物的碱性磷酸酶进行了测定,分析了水体理化特性、季节变化及水生植物对湖泊沉积物碱性磷酸酶活性的影响,结果表明:pH值、温度对沉积物碱性磷酸酶活性影响较大,呈显著正相关(r=0.220,P70.05;r=0.478,P70.01),而DO值的影响较小,相关不显著;随着季节的变化,云龙湖沉积物碱性磷酸酶活性变化较明显,其变化规律为夏季>秋季>冬季>春季,夏季最高,为330.27 mg/(kg·h),春季最低,为154.65 mg/(kg·h);随着季节的变化,水体pH、DO变化较小,分别为8.12～8.50、6.84～8.47 mg/L,温度变化较大,为3.3～26.5℃;水生植物对骆马湖沉积物碱性磷酸酶活性影响较大,有草区均大于无草区且有草区碱性磷酸酶活性随季节变化显著。因此,水体理化特性、季节变化及水生植物等环境因子对不同湖泊沉积物中碱性磷酸酶活性有重要影响。     

处理生活污水湿地植物的筛选与净化潜力评价

为了建立一套科学的湿地植物筛选与净化潜力评价体系,以17种湿地植物为材料,在综合应用原有各种湿地植物筛选与评价指标的基础上,增加植物逆境酶和基质酶,对所有指标进行聚类分析.结果表明,17种植物的根系数量、长度、活力、叶片过氧化物酶活性、生长量、氮磷平均浓度、氮磷的积累能力存在一定的差异,根系附近基质脲酶活性与磷酸酶活性也存在一定的差异.根据净化潜力的综合评价体系,可以把17种植物聚类为3大类,第1大类净化潜力较强,包括美人蕉、芦苇、风车草、水葱、再力花、千屈菜、花叶美人蕉;第2大类净化潜力中等,包括菖蒲、花叶芦竹、香蒲、梭鱼草;第3大类净化潜力较弱,包括野芋、鸢尾、灯心草、葱兰、泽泻、花菖蒲.     

大型水生植物对骆马湖氮、磷元素的影响

对骆马湖有草区和无草区水体和沉积物中氮、磷元素含量分析,结果表明:无草区水体中总氮、总磷含量高于有草区;有草区表层沉积物总氮含量随时间变化明显,而无草区表层沉积物总氮含量随时间的变化很小;有草区与无草区表层沉积物中总磷含量的时间变化并无明显差异;有草区表层沉积物总氮含量基本上均高于无草区,而有草区表层沉积物总磷含量均要低于无草区。骆马湖有草区与无草区采样点沉积物碱性磷酸酶活性大小在58.41～315.07 mg/(kg.h)范围内变化,有草区的碱性磷酸酶的活性普遍低于无草区的碱性磷酸酶活性。在湖泊中种植大型水生植物确实可以减少水体污染,达到净化水质的目的。     

超声波促进好氧/缺氧污泥消化过程中水解酶活性变化研究

为评价超声波促进污泥好氧/缺氧消化的作用,采用频率28 kHz,声能密度为0.15 kW.L-1和超声时间10 min的超声参数与好氧/缺氧消化衔接,研究了污泥的SS、VSS及水解酶活性(淀粉酶、α-葡萄糖苷酶、蛋白酶、磷酸酶)在消化过程中的变化趋势,同时以未经超声处理的消化污泥作为对照.结果表明,经过超声波-好氧/缺氧消化13 d,VSS去除率为44.3%,高出对照污泥14.9%.污泥中水解酶活性随消化天数增加呈先增加后减少的变化趋势,其中超声污泥的淀粉酶和葡萄糖苷酶活性在第5 d达到峰值,此时VSS淀粉酶活性为0.104μmol.g-1,葡萄糖苷酶活性为0.637μmol.g-1.超声污泥中胞内蛋白酶和胞外蛋白酶在第7 d达到峰值,胞内蛋白酶活性为23.68μmol.g-1,远远大于胞外蛋白酶,在污泥消化过程中起主导作用.超声污泥中酸性磷酸酶活性高于对照污泥,而碱性磷酸酶对环境改变较为敏感,超声波预处理改变污泥内部性质,导致碱性磷酸酶活性减少.     

蕹菜类囊体膜磷酸酯酶的分离纯化和部分性质

使用NaCl抽提、硫酸铵分步沉淀、离子交换和疏水柱层析等方法 ,从蕹菜叶绿体类囊体膜中分离纯化到一种蛋白磷酸酯酶 .SDS -PAGE检测表明 ,这种磷酸酯酶的分子量 (Mr)为 14 .9× 10 3 .该酶具有水解磷酸单酯类物质的活性 ,水解pNPP的Km值为 1.76× 10 -6mol/L ;体外测活时最适pH为 5 ,属于酸性磷酸酯酶 ;该酶耐热 ,在 5 0℃时活力达到最高 ,对NaCl不太敏感 ;但EDTA和NaF可以明显影响该酶的活性 .图 6表 3参 2 4     

岛屿生境下苦槠丛枝菌根(AM)与根际土壤磷酸酶活性的相关性研究

以浙江千岛湖典型生境片断化区域苦槠(Castanopsis sclerophylla)为材料,研究了水库形成后岛屿化导致的群落生境差异对苦槠AM侵染率的影响以及AM侵染率与根际土壤磷酸酶活性的相关性.结果表明,以生境面积为因子进行单因素方差分析,则不同岛屿生境对苦槠AM侵染率影响差异不显著;但以Pearson相关性分析,AM侵染率与岛屿面积之间呈显著负相关.苦槠根际土壤酸性磷酸酶活性在中岛、大岛与陆地间差异显著,但与AM侵染率之间无显著相关性.     

Transient expression of protein tyrosine phosphatases encoded in <Emphasis Type="Italic">Cotesia plutellae</Emphasis> bracovirus inhibits insect cellular immune responses

Several immunosuppressive factors are associated with parasitism of an endoparasitoid wasp, Cotesia plutellae, on the diamondback moth, Plutella xylostella. C. plutellae bracovirus (CpBV) encodes a large number of putative protein tyrosine phosphatases (PTPs), which may play a role in inhibiting host cellular immunity. To address this inhibitory hypothesis of CpBV-PTPs, we performed transient expression of individual CpBV-PTPs in hemocytes of the beet armyworm, Spodoptera exigua, and analyzed their cellular immune responses. Two different forms of CpBV-PTPs were chosen and cloned into a eukaryotic expression vector under the control of the p10 promoter of baculovirus: one with the normal cysteine active site (CpBV-PTP1) and the other with a mutated active site (CpBV-PTP5). The hemocytes transfected with CpBV-PTP1 significantly increased in PTP activity compared to control hemocytes, but those with CpBV-PTP5 exhibited a significant decrease in the PTP activity. All transfected hemocytes exhibited a significant reduction in both cell spreading and encapsulation activities compared to control hemocytes. Co-transfection of CpBV-PTP1 together with its double-stranded RNA reduced the messenger RNA (mRNA) level of CpBV-PTP1 and resulted in recovery of both hemocyte behaviors. This is the first report demonstrating that the polydnaviral PTPs can manipulate PTP activity of the hemocytes to interrupt cellular immune responses.     

First-trimester maternal serum biochemical indicators in Down syndrome

A set of 21 early maternal serum samples (19 first-trimester and two at 14 weeks) from pregnancies resulting in a child with Down syndrome was matched for gestation and length of storage with 63 samples from unaffected pregnancies. The concentrations of alpha-fetoprotein (AFP), unconjugated oestriol (uE₃), human chorionic gonadotrophin (hCG), pregnancy-specific β₁–glycoprotein (SP₁), and placental alkaline phosphatase (PALP) were measured. The ratios of the medians for Down syndrome pregnancies compared with the medians for controls were AFP 0·71, uE₃ 0·67, hCG 1·43, SP₁ 0·79, and PALP 0·92. Although the differences between the medians for affected and unaffected pregnancies were not significant, the trends for AFP, uE₃, and hCG confirm earlier findings on first-trimester samples.     

First-trimester prenatal diagnosis of hypophosphatasia: Experience with 16 cases

We have carried out first-trimester prenatal diagnosis of hypophosphatasia in 1 6 pregnancies with a 1 in 4 risk of this condition. The liver/bone/kidney isoenzyme of alkaline phosphatase was measured in chorionic villus samples using a specific monoclonal antibody and an enzymatic amplification system. Fifteen of the 16 pregnancies were correctly predicted, while one has been lost to follow up. We suggest that this assay system is likely to be superior to DNA-base methods for the first-trimester prenatal diagnosis of hypophosphatasia.