内蒙古察哈尔丘陵啮齿动物种群数量的波动和演替

根据内蒙古自治区正镶白旗乌宁巴图苏木９７４－１９９３年随啮齿动物密度监测资料进行分析,得到如下结果。共捕啮齿动物１３种,其中达乌尔黄鼠为优势种（６７．８５％）、一趾鼠为次优势种（１０．１６％）,长爪沙鼠、布氏田鼠、达乌尔鼠兔为常见种,余为少见种。黄鼠密度与个体数呈正相关（Ｐ〈０．０００１）、五趾跳鼠与个体数、黄鼠密度呈负相关（Ｐ〈０．００１）。个体数与黄鼠、五趾跳鼠密度的回归模型为：（个体数）＝１     

Light-induced swimming of Daphnia: can laboratory experiments predict diel vertical migration?

Vertical displacement velocity of a Daphniagaleata × hyalina clone was quantified inrelation to changes in the relative rate of lightchange. An increase in the latter variable triggers anenhanced swimming response, and this response is againelicited when a second increase in the rate ofrelative light increase is applied. Decreases in therate of light increase affect phototactic swimming ina similar way. The acceleration/deceleration assistedstimulus-response system is an extension of the ideaof phototaxis as the underlying behavioural mechanismfor vertical migration, and suggests that continuousaccelerations in light change also affect verticaldisplacements observed in the field. A simple dielvertical migration simulation model was used tocalculate the vertical displacement of Daphniain relation to the natural light change at sunrise.The calculated vertical displacement fits nicely inthe temporal range of the observed averaged downwardmigration of adult Daphnia in Lake Maarsseveen.The calculated migration amplitude, however, islarger than the change in mean population depthobserved in nature.     

Effects of NEM on Voltage-activated Chloride Conductance in Toad Skin

The regulation of the voltage-activated chloride current conductance (G _Cl ) in toad skin was investigated by the use of the SH reagents N-ethylmaleimide (NEM) and p-chloro-mercuricbenzenesulfonic acid PCMBS. This anion pathway is controlled by a voltage-sensitive gating regulator. Mucosal application of NEM decreased the voltage-activation in a time and concentration dependent manner, half-maximal inhibition being exerted at a concentration of 30 μm within 20 min. At concentrations higher than 100 μm, the voltage-activated G _Cl was near-completely and irreversibly inhibited in less than 10 min. Resting, deactivated conductance was essentially unaffected. NEM had no effect on active sodium transport (measured as I _sc ) under conditions, which fully dissipated the voltage-activated G _Cl . After complete inhibition of the voltage-activated G _Cl with NEM, chloride conductance could still be stimulated by CPT-cAMP as in control tissues. Under these conditions, NEM at concentrations above 1 mm decreased G _Cl reversibly. Mucosal application of PCMBS at 500 μm inhibited the activated conductance by 35%, which was slightly reversible. Inhibition of voltage-activated G _Cl , which was observed after mucosal addition of the membrane-impermeable NEM analogue, eosin-5-maleimide, was completely reversible after washout. This suggests that the binding site for the maleimide is not accessible from the external face of the apical membrane. Brief application of NEM at lower concentrations (1–3 min, ≤100 μm) led to partial inhibition of G _Cl , followed by occasionally complete recovery upon washout of NEM. Recovery of voltage-activated G _Cl was progressively attenuated and eventually disappeared after subsequent brief applications of NEM. This could reflect recruitment of permeation/control sites from a finite pool. The data are discussed in the frame of a working model for the voltage-activated Cl⁻-pathway, that contains two principle components, i.e., an anion-selective permeation path which is controlled by regulatory protein(s). Received: 18 December 1996/Revised: 28 April 1997     

两种吸血水蛭对光闪烁和水扰动刺激的反应

利用自制的控温实验槽在暗室内进行医蛭科两种吸血水蛭对光闪烁和水扰动刺激的模拟个体生态实验,实验结果的统计分析表明,日本医蛭在１６℃时与照度有极好的正相关关系,而在２２℃时成负相关关系,０．２克体重的个体在两种温度对照度的敏感度均大于０．５－０．６克和１．０－１．３克体重的个体,湖北牛蛭在两种温度时与照度均成正相关关系;０．５克体重的个体在１６℃时对照度的敏感度大于１．０－３．３克体重的个体９．５－     

蚤数量与宿主数量和气象因子的关系

根据内蒙古自治区鄂托克旗和鄂托克前旗1975一1989年长爪沙鼠密度、蚤指数监测数据和本地区气象站的,项气象因子资料,分别求出了蚤指数与鼠密度的直线和曲线的回归模型,与气象因子的最优回因子集模型和标准回归模型,给出了鼠蚤因子和气象因子间的典型棺关分析。结论：宿主数量变化导致蚤指数变化;气象因子综合影响蚤指数;相对湿度和地表温度是影响蚤数量变动的重要因子;气象因于对蚤指数的影响大于对鼠密度的影响。     

A conceptual model for the assessment of depressional wetlands in the prairie pothole region

The U.S. Environmental Protection Agency's (EPA's), Environmental Monitoring and Assessment Program (EMAP) is developing a landscape-level conceptual model to evaluate the condition of depressional (basin-type) wetlands in the prairie pothole region (PPR) of the United States. This effort is underway to determine the current condition of the Nation's wetlands and to track how it is improving or degrading over time, as well as to identify management priorities over major geographic areas. The depressional wetlands in the PPR were selected by EMAP both because of the importance of this region for waterfowl and because of the efforts currently being conducted by federal agencies and academic institutions in this region. The PPR provides nesting habitat for more than 15 species of ducks, and supports as much as half of the total production of dabbling and diving ducks in North America. Wetlands in this area became a vulnerable resource after extensive draineage in the 1800s. We propose a conceptual model that represents a framework for guiding the development of ecological indicators, research activities, and data collection for the evaluation of wetland conditions. In princple, this conceptual model is applicable to wetlands in any part of the world.     

Removal of toluene in waste gases using a biological trickling filter

The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h^–1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m^–3 h^–1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m^–3 h^–1, corresponding to a zero order removal rate of 0.11±0.03 g m^–2 h^–1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m^–3, corresponding to inlet gas concentrations above 0.7–0.8 g m^–3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k_1A , was estimated to be 0.08–0.27 m h^–1 (k_1A a=24–86 h^–1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, K_La, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface.     

Electrical consequences of spine dimensions in a model of a cortical spiny stellate cell completely reconstructed from serial thin sections

We built a passive compartmental model of a cortical spiny stellate cell from the barrel cortex of the mouse that had been reconstructed in its entirety from electron microscopic analysis of serial thin sections (White and Rock, 1980). Morphological data included dimensions of soma and all five dendrites, neck lengths and head diameters of all 380 spines (a uniform neck diameter of 0.1 m was assumed), locations of all symmetrical and asymmetrical (axo-spinous) synapses, and locations of all 43 thalamocortical (TC) synapses (as identified from the consequences of a prior thalamic lesion). In the model, unitary excitatory synaptic inputs had a peak conductance change of 0.5 nS at 0.2 msec; conclusions were robust over a wide range of assumed passive-membrane parameters. When recorded at the soma, all unitary EPSPs, which were initiated at the spine heads, were relatively iso-efficient; each produced about 1 mV somatic depolarization regardless of spine location or geometry. However, in the spine heads there was a twentyfold variation in EPSP amplitudes, largely reflecting the variation in spine neck lengths. Synchronous activation of the TC synapses produced a somatic depolarization probably sufficient to fire the neuron; doubling or halving the TC spine neck diameters had only minimal effect on the amplitude of the composite TC-EPSP. As have others, we also conclude that from a somato-centric viewpoint, changes in spine geometry would have relatively little direct influence on amplitudes of EPSPs recorded at the soma, especially for a distributed, synchronously activated input such as the TC pathway. However, consideration of the detailed morphology of an entire neuron indicates that, from a dendro-centric point of view, changes in spine dimension can have a very significant electrical impact on local processing near the sites of input.     

双碳源单细胞蛋白间歇培养及流加培养的动力学模型

应用非结构的逻辑增殖模型研究了两种酵母的单碳源和双碳源单细胞蛋白间歇培养的动力学,用改进的逻辑增殖模型研究了双碳源流加培养过程的动力学,从实验数据拟合了动力学模型参数,模型计算值与实验数据吻合良好。