A Computer-based image analysis system for biocide screening

A computer-based image analysis system that measures the behavioral response of the marine diatom Amphora coffeaeformis to potentially toxic challenges is described. At any one time the system is capable of measuring in a population of about 80 cells, changes in the number motile, their speed, direction, and if they are turning, their angular velocity and acceleration. Chemical compounds that interfere with the generation of energy, protein or glycoprotein synthesis, calcium homeostasis and cytoskeletal activity, change the motile behavior of the cell. A pre-requisite of motility is that the cells be attached to a substratum. It is proposed that the system, which requires only a 1-2 minute data collection period per replicate, could be used to screen for potential antifouling activity in chemical agents, and it is speculated that it could be used also for measuring the physicochemical interaction between attached motile organisms and their substratum, as well as in environment toxicology measurements.     

Determination of volumetric oxygen transfer coefficient by off-gas analysis

In various aerobic bioreactors including activated sludge aeration tanks, the volumetric mass transfer coefficient K_La is frequently used as an estimate of the rate of oxygen dissolution into the liquid phase. The K_La measurement in such bioreactors is widely applied with the aid of sodium sulfite (Na₂SO₃) as an oxygen-consuming substance used to maintain low dissolved oxygen concentration. In the present study, the effect of the addition of Na₂SO₃ on K_La, determined by an off-gas analysis, was investigated specifically from the viewpoint of variations in the size of air bubbles and the enhancement factor associated with the change in sulfite concentration. Experiments were conducted in a draft-tube bubble column, using a zirconia electrode oxygen analyzer for measurement of the O₂ mole fraction in the exhaust gas and a dual electrical resistivity probe for measurement of the bubble size. It was found that the increase in the specific gas-liquid interfacial area, resulting from bubble size reduction effected by Na₂SO₃ functioning as an electrolyte, is more pronounced than the enhancement of the absorption rate through the interface. The upper limit of Na₂SO₃ concentration for sustaining physical absorption, in the absence of any catalyst, ranges from 30 to 70 mol/m³, while that for preventing the average bubble size from decreasing is about 15 mol/m³. Furthermore, to secure a reliable K_La measurement, the K_La value should not exceed 50 h⁻¹ for the liquid depth of 3 m even when the limiting conditions are not exceeded. The off-gas analysis proposed in this study for K_La determination is expected to be extremely useful provided that the above conditions are fulfilled, since it only requires moderate addition of the sulfite as the oxygen-consuming substance and will not interrupt the reactor operation as long as oxygen uptake occurs in the system.     

A simple computer-based video image analysis system and potential applications to microbiology

An inexpensive microcomputer-based image analysis system is described in which an Apple microcomputer acquires data from a video camera or video cassette recorder and measures the brightness of the image received at specified points or areas. Suggested uses for this apparatus include measurements of chlorophyll fluorescence in algal cells, determination of the effects of ultraviolet illumination on chlorophyll fluorescence, estimation of total amounts of chlorophyll in a microscope field, and microspectrophotometic and microdensitometic measurements. A similar ssytem using the IBM personal computer with a different interface is also described.     

Computer-based testing system for experiments in visual perception

This paper discusses the increasing scope for the application of computing systems to the investigation of problems in the field of visual perception. A simple language for the generation of various perceptual testing schemes is described and some examples of possible applications are given.     

A simple system for pea transformation

The lateral cotyledonary meristems of germinatingPisum sativum cv. Puget seeds were used to develop a reproducibleAgrobacterium tumefaciens-mediated transformation system. This procedure exhibits distinct advantages over those previously reported, in that it uses dry seed as starting material, and the highly regenerable cotyledonary meristems rapidly produce transgenic shoots without an intermediate callus phase. This transformation regime facilitates the rapid generation of phenotypically normal, self-fertile plants containing functional transgenes inherited in a Mendelian fashion.Abbreviations bar Bialaphos resistance gene - BAP 6-Benzylaminopurine - GA₃ Gibberellic acid - IBA Indole-3-butyric acid - PAT Phosphinothricin acetyltransferase - PPT Phosphinothricin     

A simple,reliable, and expandable monitor and control system for gas-exchange analysis

A system of relatively low-cost but reliable components was assembled for time sharing a single analytical instrument in gas-exchange studies. Aside from an analytical instrument, recorder, gas standards, and study vessels or compartments, only a simple assembly of timers, motor-driven cams, microswitches, gas solenoid valves, and a single electronic relay were required. The system was developed for biological studies of photosynthesis and respiration, but can be readily adapted to air pollution and basic chemical problems.     

A simple analysis system for the estimation of recombination efficiency using fluorescence-activated cell sorting

A simple and accurate analysis system for the estimation of recombination efficiency in vivo using fluorescence-activated cell sorting (FACS) was designed and was subsequently used to compare the efficiency of recombination related to different spacer mutants. F(3) and F(5) mutant sequences were used for Flpe-mediated cassette exchange, and m2 and lox2272 mutant sequences were used for Cre-mediated cassette exchange due to their high incompatibility with wild-type sequences. The incompatibilities with wild-type were almost the same between mutant sequences. However, the recombination efficiencies were different. F(3) and m2 could mediate more efficient recombination than F(5) and lox2272, respectively. These results are consistent with the fact that the sequence of spacer region affects not only the reactivity upon wild-type sequence but also the recombination efficiency. It was also confirmed that the recombination process was mediated in a site-specific manner through PCR analysis using different sizes of exchange cassettes. In this experiment, the feasibility of the FACS analysis system for the estimation of recombination efficiency was verified. This system should be readily applicable for estimating recombination efficiency of other various mutant candidates, which will contribute to more precise and efficient site-specific recombination.     

A simple model for the arterial system

We present a simple model for the arterial part of the cardiovascular system, based on Poiseuille flow constrained by the power dissipated into the cells lining the vessels. This, together with the assumption of a volume-filling network, leads to correct predictions for the evolution of vessel radii, vessel lengths and blood pressure in the human arterial system. The model can also be used to find exponents for allometric scaling, and gives good agreement with data on mammals.     

A simple parallel gas chromatography column screening system

A simple approach to the automated screening of four different columns on a single gas chromatography (GC) instrument is used for rapid chiral GC method development. Configuration of a conventional GC instrument with a second autosampler and several inexpensive Y-splitters enables simultaneous evaluation of two different columns, allowing a total of four different columns to be evaluated in two automated back to back runs. The resulting system affords a simple and effective approach to chiral GC method development that speeds analysis while eliminating the need for slow and tedious manual interchange of columns. An example of developing a rapid isothermal GC method from the screening results obtained by the instrument is also shown.