Abstract: The present invention achieves a smaller difference between a dissolved oxygen concentration in an upper part of a culture tank and a dissolved oxygen concentration in a lower part of the culture tank. The present invention comprises: a culture tank; a sparger means arranged in a lower part of the culture tank; and multiple impellers being arranged in multiple stages in a vertical direction of the culture tank and having a larger mass transfer capacity coefficient KLa per unit number of revolutions in an upper stage than in a lower stage.

Abstract: In order to investigate an object, such as a culture of micro-organisms, the object is repeatedly captured at two different magnifications by a suitable image pick-up device. The images at the two different magnifications are then analysed by a suitable picture image recognition device and the results of the repeated analysis are compared, thereby to derive a measurement of the change in the object with time. Thus, for a culture of micro-organisms, the number of cells can be determined at one magnification and the number of microscopic spherical bodies can be determined at another magnification, to obtain a measure of the activity of the culture. Preferably, one or more conditions of the object are then controlled on the basis of the measurement of change.

Abstract: An inverted microscope is adapted so that a specimen thereon e.g. cells can be irradiated by a laser beam. The laser beam is guided from a laser source by a series of adjustably movable reflectors which introduce it into the microscope optical pathway at a parallel-beam region thereof, and through the objective lens of the microscope. A point to be irradiated can be selected by moving the reflectors which may be galvanometrically-movable. The laser beam can be focused together with the microscope image. The movable reflectors are kept within 200 mm behind the objective lens principal plane (PP) to ensure that the laser can be applied all over the microscope viewing field.

Abstract: The present invention provides a process for dissolving oxygen comprising forming a liquid membrane of an oxygen-permeable liquid on a support layer made of a hydrophobic porous material, bringing one side of the liquid membrane into contact with an oxygen-containing gas and the other side with an aqueous liquor, and thereby dissolving oxygen in the aqueous liquor; a process for culturing cells in an oxygen-containing aqueous liquor obtained by the oxygen-dissolving process; and apparatus for practicing these processes. According to the present invention, oxygen can be dissolved in an aqueous liquor efficiently and economically, and aerobic cell-culturing can be stably effected even at a high cell concentration.

Abstract: In the instrument for determination of the base sequence of the present invention, the ionic strength of a buffer solution in a gel is made lower at a detection part than in a region from the detection part towards a negative electrode. Therefore, at the detection part, the electric field intensity can be increased, resulting in a higher migration speed, and hence the electrophoretic pattern can be extended, so that the distance between two adjacent electrophoretic bands can be elongated.Consequently, according to the present invention, the slit width can be narrowed relatively to the electrophoretic pattern without actually narrowing the slit width, and the resolving power can be enhanced without lowering the detection sensitivity.

Abstract: An instrument for determination of the base sequence of deoxyribonucleic acid (DNA) which is designed to dectect DNA fragments in course of gel electrophoresis in real time to determine the base sequence of DNA, and comprises a gel electrophoretic panel part wherein DNA fragments labeled with a radioisotope are supplied to four places in a gel for four kinds of complementary strand synthesis reaction systems, respectively, and subjected to electrophoresis to form an electrophoretic pattern of the DNA fragments, and a detection part for detecting the electrophoretic pattern of the DNA fragments provided at a predetermined position in said gel electrophoretic panel part so as to have a position resolving power in a direction perpendicular to the direction of electrophoretic migration of the DNA fragments, and which instrument has a means for making the temperature of the gel in the vicinity of the detection part for detecting the electrophoretic pattern of the DNA fragments higher than that on the DNA fragment