Interfacial immobilization of monoclonal antibody and detection of human prostate-specific antigen.

Antibody orientation and its antigen binding efficiency at interface are of particular interest in many immunoassays and biosensor applications. In this paper, spectroscopic ellipsometry (SE), neutron reflection (NR), and dual polarization interferometry (DPI) have been used to investigate interfacial assembly of the antibody [mouse monoclonal anti-human prostate-specific antigen (anti-hPSA)] at the silicon oxide/water interface and subsequent antigen binding. It was found that the mass density of antibody adsorbed at the interface increased with solution concentration and adsorption time while the antigen binding efficiency showed a steady decline with increasing antibody amount at the interface over the concentration range studied. The amount of antigen bound to the interfacial immobilized antibody reached a maximum when the surface-adsorbed amount of antibody was around 1.5 mg/m(2). This phenomenon is well interpreted by the interfacial structural packing or crowding. NR revealed that the Y-shaped antibody laid flat on the interface at low surface mass density with a thickness around 40 Å, equivalent to the short axial length of the antibody molecule. The loose packing of the antibody within this range resulted in better antigen binding efficiency, while the subsequent increase of surface-adsorbed amount led to the crowding or overlapping of antibody fragments, hence reducing the antigen binding due to the steric hindrance. In situ studies of antigen binding by both NR and DPI demonstrated that the antigen inserted into the antibody layer rather than forming an additional layer on the top. Stability assaying revealed that the antibody immobilized at the silica surface remained stable and active over the monitoring period of 4 months. These results are useful in forming a general understanding of antibody interfacial behavior and particularly relevant to the control of their activity and stability in biosensor development.

内蒙古草原CH4 通量的DNDC 模型模拟

甲烷（CH4）是增温效应仅次于二氧化碳（CO2）的重要温室气体。内蒙古草原是欧亚温带草原的重要类型，具有典型的生态地域代表性。如何理解该区域CH4 交换的时空格局与环境控制、不同土地利用类型的源汇特征以及CH4 通量对气候变化的响应、对于我们进一步理解全球变化与陆地生态系统关系具有十分重要的意义。本研究以内蒙古草原锡林河流域为对象，首次在国内应用DNDC 生物地球化学模型模拟干草原和河漫滩湿地的CH4 通量，预测CH4 循环对未来气候变化的响应，并对该区域干草原的CH4 吸收进行了区域模拟估算。结果表明： 1.在模型中添加植被生长节律与土壤CH4 吸收的关系函数后，DNDC 模型能够准确地模拟锡林河流域干草原CH4 吸收的大小及其年变化。土壤温度、土壤水分和植被生长状况是影响干草原大气CH4 吸收的主要因素。 2.水位，土壤温度，质地和植被生长节律是控制河漫滩湿地CH4 通量的主要因子。根据有限水位测定值估算模拟周期内全部水位数据的方法能够应用于模拟水位相对比较稳定区域的未知时期水位。经过该修正的DNDC 模型能够较为准确的捕获锡林河流域河边湿地的CH4 排放通量的大小及年变化。 3.干草原和湿地年CH4 通量对温度变化敏感，而对降水量变化不敏感，其中湿地比干草原对温度变化的响应更加敏感。 4.温度升高可显著地促进干草原和湿地的日CH4 吸收和排放能力，其CH4 通量的增加均表现出明显的季节性差异。干草原日CH4 通量对降水量增加20% 的响应并不显著，而河漫滩湿地的响应虽显著，变幅却很小且增减程度不同。 5.与2005 年相比，2050 年干草原河漫滩湿地的CH4 吸收和排放量将分别增加10%和77%。锡林河流域CH4 通量对未来气候变化产生正反馈作用，并且湿地CH4 排放对未来气候变化的响应大于干草原CH4 吸收的响应。未来气候变化将增加锡林河流域CH4 源强度。 6. 锡林河流域干草原CH4 吸收量达2.42Gg C•yr-1。干草原CH4 吸收量的空间异质性较大，各栅格单元（0.01 ×0.01 度）的CH4 吸收量变化为0-404.6 kg C，其中大部分区域CH4 吸收量变化在150-250 kg C•yr-1 之间。草甸草原的大气CH4 吸收能力显著高于典型草原。干草原CH4 吸收率平均为2.59 kg C• ha-1 •yr-1。干草原CH4 吸收量的空间异质性是土壤有机质含量、土壤质地、土壤温度湿度，植被类型等因素共同作用的结果，与单一变量的关系并不明显。

Influence of size, station time and satiation amount on prey handling time in Anabas testudineus (Bloch)

Satiation amount, satiation time and handling time of Anabas testudineus (Bloch), an air breathing predatory fish was experimentally estimated using guppy (Lebistes reticulatus) as prey. Weight of the fish and satiation time influenced prey handling time. As satiation time is related to the level of hunger, level of hunger was found to influence handling time of prey.

Effect of chloral hydrate on metabolic rate of Labeo rohita (Ham) and Poecilia reticulata (Peters)

Comparative impact of chloral hydrate anaesthesia on the metabolic rate of Indian major carp Labeo rohita and larvivorous fish Poecilia reticulata was assessed. Observation on the Oxygen Consumption Rate (OCR) revealed that in common guppies OCR was substantially low (1.105 and 1.097 mg/g/hr) at 0.1 and 0.25 g/l concentrations of chloral hydrate as against OCR of 1.487 mg/g/hr in the control. Fry of L. rohita in group showed lower metabolic rates in the control as well as treated conditions as compared to the individuals of this fish. This may be due to sympathetic psychophysiological reflex of grouped fish. Higher dose of chloral hydrate (0.25 g/l) also caused higher OCR probably due to distress. Application of chloral hydrate also favoured lesser release of metabolic wastes (ammonia and carbon dioxide). There was significant positive correlation between time and oxygen consumption, whereas, for time and OCR this relationship was negative. Regression of chloral hydrate doses for OCR and time has also been calculated.