A TWO LITRE SCALE CONTINUOUS CULTURE APPARATUS FOR MICRO-ORGANISMS

SUMMARY: The design and construction of a continuous culture apparatus with a 2 1. culture vessel are described. Aeration is achieved by means of a mechanical stirrer and injected air, automatic temperature and pH control are features of the apparatus, and foaming is controlled by adding antifoam through a manually operated valve. A high degree of agitation ensures that good mixing takes place. Accurate and easily variable control of the medium flow rate is obtained by means of the Mariotte bottle principle. The apparatus can be operated continuously with freedom from contamination for periods in excess of 1000 hr.     

An analytical flat-plate photobioreactor with a spectrally attenuated light source for the incubation of phytoplankton under dynamic light regimes

An inexpensive and simple, analytical microalgal photobioreactor with a highly controllable, dynamic, spectrally attenuated light source is described. Spectral attenuation is achieved through the introduction of a variable thickness of CuSO₄ solution between the photobioreactor and a light source. The level of liquid is precisely determined via a computer-controlled peristaltic pump, which can be programmed to pump at a variety of rates. The resultant light fields consist of a wide range of irradiance intensities with concomitant spectral narrowing, which closely mimics modeled clear water attenuation patterns. Irradiance dynamics associated with virtually any mixing regime can be achieved. The culturing apparatus of the analytical photobioreactor is based on traditional flat-plate, photobioreactor design, but with several modifications: (1) The light path has been reduced to 1 cm to assure a uniform light field is experienced by all phytoplankton at relatively low cell densities; (2) carbon dioxide concentrations are kept constant through a negative feedback mechanism that pulses CO₂ into a constant air stream when culture media pH rises above a set point; (3) temperature is controlled in a similar manner, through the addition of cooling water to a water jacket in response to an increase in culture media temperature. This design is intended for use in photophysiological and bio- physical studies of microalgae under highly controlled culture conditions. It should prove easily adaptable to any number of more complex configurations.     

A methodological approach to rapid and sensitive monoamine histofluorescence using a modified glyoxylic acid technique: The SPG method

Summary A modified approach of the glyoxylic acid (GA) condensation reaction for the visualization of biogenic amines in tissue is described.Cryostat sections are used from brain or extracerebral tissue in dog, monkey, rat and mouse and exposed for 3 s to a room temperature solution containing sucrose-potassium phosphate-glyoxylic acid (SPG). The tissues are air dried and heated in an oven for 5 min. The complete processing time from fresh tissue to microscopic examination takes 18 min. Morphologically sharp and brightly fluorescent monoamine-containing neurons, pre-and terminal axons are seen against a dark parenchymal background without drug pre-treatment. The SPG method retains the high specific sensitivity for monoamines previously described in the original technique but is, in addition, more rapid and simple and is easily accessible as a research tool to investigators inexperienced in histofluorescence techniques.     

A gas-flow cryostat for use in freeze-quench studies: design and application to discontinuous pre-steady-state spectral analyses

A design for an improved freeze-quench apparatus is presented. A freeze-quench apparatus has two main parts: the apparatus which mixes the reactants and after a set time sprays the reacting mixture into the quencher, and the quenching apparatus itself. The quenching apparatus is the novel feature of our design and it comprises a gas-flow cryostat mounted directly onto a liquid nitrogen storage Dewar. The gas flow maintains the temperature of a small volume of isopentane, which acts as the freeze-quench agent, at -140 degrees C. (The apparatus can maintain the quenching temperature over the range -190 degrees C to room temperature.) Because of the small size of the cryostat and the much reduced volume of solvent used by this method it is more convenient to use than its predecessors, can be used in the open laboratory, and is safer. Our apparatus is designed for application to electron paramagnetic resonance studies but could be easily modified for use with other spectroscopic techniques.     

根系温度对光核桃幼苗光合机构热稳定性的影响

以光核桃(Prunus mira)幼苗为材料, 通过控制根系温度研究了根系温度变化与叶片脱落酸(ABA)的关系及其对光合机构热稳定性的影响。结果表明: 1)环境高温(37和40 ℃)胁迫下保持根系温度适宜((25±2) ℃)时, 幼苗叶片相对含水量(Relative water content, RWC)下降较少, 但叶片ABA含量低, 超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)和过氧化氢酶(CAT)活性低, 过氧化氢(H₂O₂)含量和膜质过氧化水平(丙二醛(Malondialdehyde, MDA)浓度)提高, 最大光化学效率(F_v/F_m)下降程度较大; 2)而同等环境高温(37和40 ℃)条件下根系温度逐步升高时, 幼苗叶片RWC降低, 叶片ABA含量增加, SOD、APX、POD、CAT活性高, H₂O₂含量高, MDA生成量低, F_v/F_m降低程度较小。与37 ℃相比, 40 ℃处理条件下各生理指标变化趋势相似, 但差异加大。因此认为: 高温胁迫条件下, 根系温度适宜时RWC高, 但导致光合机构伤害较重; 根系感受高温胁迫能够增加叶片ABA含量, 有助于保护光合机构、提高光合机构的抗热性。     

A new spectrophotometric cuvette holder for low temperature studies; Its application to the study of carbonmonoxyhemoglobin oxidation rate

A new spectrophotometric cuvette holder to be used for subzero temperature is described. The device is easily adaptable to a commercial spectrophotometer and it was checked down to --40 degrees C. Satisfactory mixing of the reactants contained in the cuvette at low temperatures is attained using a special stirrer and suitable solution volumes. The rate of carbonmonoxyhemoglobin oxidation by K3Fe(CN)6 at different subzero temperatures has been studied using this apparatus; the results are in agreement with the extrapolated data at room temperature.     

Experiments with an apparatus for lyophile desiccation of micro-organisms

Summary Lyophyle desiccation is an extremely valuable method of preserving micro-organisms. The apparatus described above proves satisfactory. The material should be frozen as rapidly as possible at a temperature of −35°C. or lower, and the apparatus should be constructed in such a way that the pressure remains approximatively constant. During the sealing of the ampoules care should be taken that no dry material passes from the latter to the apparatus. A time limit for the desiccation process is hard to fix. When water has condensed on the outside surface of the ampoules, the apparatus is left untouched for about an hour. This brings the total duration of the desiccation as a rule up to 1 1/2 to 2 hours. A volume of 0.25 ml skimmed milk suffices for the preservation of a strain. It is advisable to start from a fresh culture that has been grown on a solid medium and to suspend the required amount in skimmed milk at a pH of 7.4–7.8. The suspension should directly be frozen in a thin layer. Bofore the frozen ampoules are submitted to the desiccation process, they may be kept for some time at a temperature of −35°C. For this as well as for many valuable indications we are greatly indebted to the Staff of the Kamerlingh Onnes Laboratory.     

An automated scintillation counting system with high efficiency for continuous analysis: cross-links of (3H) NaBH4-reduced collagen

A completely mobile apparatus is described for automatic column monitoring and analysis of radioactive-labeled compounds by the scintillation counting of aqueous effluents from chromatographic columns. The system is extremely versatile, is highly efficient for tritium-labeled substances, and uses only approximately 10% of the sample, saving 90% for further work. The system may be easily assembled from readily available items. In physiological studies of the analysis of cross-links from [³H]NaBH₄-reduced collagen, the output of work was increased by ninefold.     

Simulation of scalp cooling by external devices for prevention of chemotherapy-induced alopecia

Hypothermia of the scalp tissue during chemotherapy treatment (scalp cooling) has been shown to reduce or prevent chemotherapy-induced hair loss. In this study, numerical models are developed to investigate the interaction between different types of external scalp cooling devices and the human scalp tissue. This work focuses on improving methods of modeling scalp cooling devices as it relates specifically to the prevention of chemotherapy-induced alopecia. First, the cooling power needed for any type of device to achieve therapeutic levels of scalp hypothermia is investigated. Subsequently, two types of scalp cooling devices are simulated: a pre-cooled/frozen cap design and a liquid-cooled cap design. For an average patient, simulations show that 38.5 W of heat must be extracted from the scalp tissue for this therapy in order to cool the hair follicle to 22 °C. In practice, the cooling power must be greater than this amount to account for thermal losses of the device. Simulations show that pre-cooled and liquid-cooled cap designs result in different tissue temperatures over the course of the procedure. However, it is the temperature of the coolant that largely determines the resulting tissue temperature. Simulations confirm that the thermal resistance of the hair/air layer has a large impact on the resulting tissue temperatures. The results should be correlated with experimental data as an effort to determine the optimal parameter choices for this model.     

An efficient and inexpensive method for measuring long-term thermoregulatory behavior

Thermoregulatory ability and behavior influence organismal responses to their environment. By measuring thermal preferences, researchers can better understand the effects that temperature tolerances have on ecological and physiological responses to both biotic and abiotic stressors. However, because of funding limitations and confounders, measuring thermoregulation can often be difficult. Here, we provide an effective, affordable (~$50 USD per unit), easy to construct, and validated apparatus for measuring the long-term thermal preferences of animals. In tests, the apparatus spanned temperatures from 9.29 to 33.94 °C, and we provide methods to further increase this range. Additionally, we provide simple methods to non-invasively measure animal and substrate temperatures and to prevent temperature preferences of the focal organisms from being confounded with temperature preferences of its prey and its humidity preferences. To validate the apparatus, we show that it was capable of detecting individual-level consistency and among individual-level variation in the preferred body temperatures of Southern toads (Anaxyrus terrestris) and Cuban tree frogs (Osteopilus septentrionalis) over three-weeks. Nearly every aspect of our design is adaptable to meet the needs of a multitude of study systems, including various terrestrial amphibious, and aquatic organisms. The apparatus and methods described here can be used to quantify behavioral thermal preferences, which can be critical for determining temperature tolerances across species and thus the resiliency of species to current and impending climate change.     

Temperature and emergence effects on the net photosynthesis of two Zostera noltii Hornem. morphotypes

Apparent photosynthetic rates (APS) of two Zostera noltii Hornem. morphotypes were measured in air and in water at different temperatures with a closed infra-red gas analysis system (IRGA).Hyperbolic functions accurately described the photosynthesis-CO₂ relationships when the leaves were exposed to air. The photosynthetic behaviour in water, on the contrary, could not be described by Michaelis type kinetics, due to the existence of a rapid transition from the initial slope to the saturation phase. Both morphotypes (narrow-leaved, NLM and large-leaved, LLM) showed higher APS rates in water than in air, although the highest APS rates, in air as well in water, were recorded for the NLM.Temperature had a significant influence on the photosynthetic parameters: APS_max (maximum photosynthetic rate) decreased (in air and in water) with increased temperature in both morphytypes; compensation points (CP) in air increased at high temperature, especially in the LLM. NLM specimens showed enhanced affinity (lower Km) with increasing temperature in air. On the contrary, Km values in water were not significantly affected by temperature.The results suggest that NLM specimens are better adapted than the LLM to occur exposed to air. The distributional pattern of the two morphotypes in the Palmones Estuary is discussed on the basis of their photosynthetic behaviour.     

Method and apparatus for soft tissue material parameter estimation using tissue tagged Magnetic Resonance Imaging

We describe an experimental method and apparatus for the estimation of constitutive parameters of soft tissue using Magnetic Resonance Imaging (MRI), in particular for the estimation of passive myocardial material properties. MRI tissue tagged images were acquired with simultaneous pressure recordings, while the tissue was cyclically deformed using a custom built reciprocating pump actuator A continuous three-dimensional (3D) displacement field was reconstructed from the imaged tag motion. Cavity volume changes and local tissue microstructure were determined from phase contrast velocity and diffusion tensor MR images, respectively. The Finite Element Method (FEM) was used to solve the finite elasticity problem and obtain the displacement field that satisfied the applied boundary conditions and a given set of material parameters. The material parameters which best fit the FEM predicted displacements to the displacements reconstructed from the tagged images were found by nonlinear optimization. The equipment and method were validated using inflation of a deformable silicon gel phantom in the shape of a cylindrical annulus. The silicon gel was well described by a neo-Hookian material law with a single material parameter C1=8.71+/-0.06kPa, estimated independently using a rotational shear apparatus. The MRI derived parameter was allowed to vary regionally and was estimated as C1 =8.80+/-0.86kPa across the model. Preliminary results from the passive inflation of an isolated arrested pig heart are also presented, demonstrating the feasibility of the apparatus and method for isolated heart preparations. FEM based models can therefore estimate constitutive parameters accurately and reliably from MRI tagging data.     

Microchemical synthesis of the serotonin receptor ligand, 125I-LSD

The synthesis and properties of 2-[125I]-lysergic acid diethylamide, the first 125I-labeled serotonin receptor ligand, are described. A novel microsynthesis apparatus was developed for this synthesis. The apparatus employs a micromanipulator and glass micro tools to handle microliter to nanoliter volumes on a microscope stage. This apparatus should be generally useful for the synthesis of radioligands and other compounds when limited amounts of material must be handled in small volumes.     

An Apparatus for the Measurement of Sap Flow in Unexcised Leafy Shoots

An apparatus is described for the measurement of water flowin shoots of woody plants by a steady-state heat-flow method.Two thermocouples are set up on either side of a heating elementinserted into the stem. The temperature difference between eachof these thermocouples and the surrounding air is measured.Theoretical considerations show that the logarithm of the ratioof this difference in the ‘downstream’ to that inthe ‘upstream’ position gives a measure of sap flow-rate.The apparatus provides a system that can be used in field orlaboratory conditions to follow water transport in the leafyshoot over periods of at least 24 h.     

An improved electroantennogram apparatus with a new automatic sample injection system

ABSTRACT. An improved electroantennogram (EAG) apparatus with a new automatic sample injection system, based on a cyclic timer connected to a 12VD.C. electrovalve, is described. The device is fully automatic and allows insertion of constant cyclic air puffs of the test compounds to the antenna at predetermined intervals.     

Application of supercritical CO2 for extraction of polyisoprenoid alcohols and their esters from plant tissues

In this study, a method of supercritical fluid extraction (SFE) with carbon dioxide of polyisoprenoids from plant photosynthetic tissues is described. SFE was an effective extraction method for short- and medium-chain compounds with even higher yield than that observed for the “classical extraction” method with organic solvents. Moreover, SFE-derived extracts contained lower amounts of impurities (e.g., chlorophylls) than those obtained by extraction of the same tissue with organic solvents. Elevated temperature and extended extraction time of SFE resulted in a higher rate of extraction of long-chain polyisoprenoids. Ethanol cofeeding did not increase the extraction efficiency of polyisoprenoids; instead, it increased the content of impurities in the lipid extract. Optimization of SFE time and temperature gives the opportunity of prefractionation of complex polyisoprenoid mixtures accumulated in plant tissues. Extracts obtained with application of SFE are very stable and free from organic solvents and can further be used directly in experimental diet supplementation or as starting material for preparation of semisynthetic polyisoprenoid derivatives, e.g., polyisoprenoid phosphates.     

An Apparatus for Maintaining Disks of Tissue in a Uniform Environment

An apparatus is described in which tissue disks may be convenientlymaintained in uniform environmental conditions. Particular attentionis paid to temperature control.     

Bacteriology of Air-Conditioning Ducts with Special Reference to Operating Rooms

The number of bacteria in air, before filtration with five different easily available filters in the low positive-pressure type of airconditioning system of the Winnipeg General Hospital, was between 3 and 4/cu. ft., and after filtration between 1 and 2/cu. ft. with all types of filters. Cl. welchii contributed about 1% and Staph. pyogenes about 0.1% of this total. Sampling the exhaust air from an operating room during an operation showed that the bacterial count fluctuated with the degree of activity in the room and was from two to 10 times as high as in the air delivered to the room.Atlhough every reasonable attempt should be made to diminish the bacterial count of air in hospitals, if much energy and money is to be spent it would probably be wiser to investigate sources of hospital infection other than the type of air-conditioning system described in this report.     

Gas exchange and water relations of spring wheat under full‐season infrared warming

Gas exchange and water relations were evaluated under full‐season in situ infrared (IR) warming for hard red spring wheat (Triticum aestivum L. cv. Yecora Rojo) grown in an open field in a semiarid desert region of the southwest USA. A temperature free‐air controlled enhancement (T‐FACE) apparatus utilizing IR heaters maintained canopy air temperature above 3.0 m Heated plots of wheat by 1.3 and 2.7 °C (0.2 and 0.3 °C below the targeted set‐points of Reference plots with dummy heaters) during daytime and nighttime, respectively. Control plots had no apparatus. Every 6 weeks during 2007–2009 wheat was sown under the three warming treatments (i.e., Control, Heated, Reference) in three replicates in a 3 × 3 Latin square (LSQ) design on six plantings during 4 months (i.e., January, March, September, December), or in a natural temperature variation treatment (i.e., Control) in three replicates in a randomized complete block (RCB) design on nine plantings during 7 months (i.e., January, February, April, June, July, August, October). Soil temperature (T_s) and volumetric soil‐water content (θ_s) were 1.3 °C warmer and 14% lower in Heated compared with Reference plots, respectively. Other than a 1% shading effect, no artifacts on gas exchange or water relations were associated with the IR warming apparatus. IR warming increased carbon gain characteristic of an increase in metabolic rates to higher temperature that may have been attributed to the well‐watered wheat crop and the supplemental irrigation that minimized plant‐to‐air water vapor pressure differences between IR‐warmed and nonwarmed plots. Nevertheless, seasonal oscillations in the IR warming response on carbon gain occurred. IR warming decreased leaf water status and provided thermal protection during freeze events. IR warming is an effective experimental methodology to investigate the impact of global climate change on agronomic cropping and natural ecosystems to a wide range of natural and artificially imposed air temperatures.