Origin of changes in electrical impedance during the growth and fermentation process of yeast in batch culture

The electrical impedance of the culture medium shows complex changes during the growth and fermentation process of yeast, and this prevents its possible application for the monitoring of certain yeast activities. Clarification of the mechanism of such changes is thus essential for practical use. As a first step toward this aim, the impedance, yeast concentration, and pH of a batch culture medium were measured using special cells with two compartments and also the usual type of cell with one compartment. In the special cells, the yeast was cultured in one compartment only. Conducting ions and nonconducting substances diffused through an intermediate porous membrane sandwiched between the two compartments. The impedances of the two compartments were measured simultaneously by the four-electrode method. The main mechanism responsible for increasing the impedance was the conducting ions produced by the yeast extract added as a nutrient to the culture broth by certain nonconducting substances during the process of growth. The increase in the yeast concentration was also a minor factor increasing the impedance. These increases surpassed the impedance decrease caused by the increase of H(+) ions produced by some accumulated acidic substances, and the impedance thus increased.     

Dynamics of plasmid maintenance in a CSTR upon square-wave perturbations in the dilution rate

The effects of forced oscillations in the dilution rate on a population of Escherichia coli K12 harboring the plasmid pBR322 in a chemostat with a nonselective medium were studied. In the constant dilution rate control experiments, the percentage of plasmid-containing cells decreased after a long lag time. Eventually, the culture approached a population consisting of 100% plasmid-free ells. However, under forced perturbations of the dilution rate, the culture maintained a mixed population of plasmid-free and plasmid-carrying cells for a longer period of ime. An unstructured model was developed to describe the above observations. Our results indicate that transient conditions created by dilution-rate perturbations provide a favorable environment for the plasmid-carrying population. In addition, experiments with different cycling frequencies suggest that adaptation by the culture to these transient conditions will reduce or totally eliminate such an advantage.     

Change of incidence of antinuclear antibodies in serum of NOD mouse with aging

Extractable nuclear antigens (ENA) were prepared from liver of C57BL/6J mouse and analyzed by SDS PAGE Western-immunoblotting techniques. Some protein components of the ENA, with molecular weights of 94 K, 65 K, 32 K, and 26 K, reacted with antinuclear antibodies in the sera of NOD mice. Incidence of antinuclear antibodies in the sera of NOD mice with aging were measured by ELISA method using the ENA as antigen. The antinuclear antibodies were not detected in young NOD mice (10 weeks old). However, the incidence increased with aging and reached 100% in the female NOD mice of 40 weeks. In the male NOD mice, the incidence of antinuclear antibodies was delayed and low in comparison with that in female.     

Detection of nuclear protein antigens to antinuclear antibodies in serum of NOD mouse

Nuclear protein antigens to the antinuclear antibodies in serum of non-obese diabetic (NOD) mice were investigated. In the serum of diabetic NOD female mice (20 weeks old), the antinuclear antibodies were detected by indirect immunofluorescence assay using frozen sections of liver of C 57 BL/6 J or NOD mice as antigen. Nuclei were separated from the liver of C 57 BL/6 J mice and solubilized. Solubilized nuclear antigens were analyzed by SDS PAGE-Western immunoblotting techniques. Nuclear protein antigens with molecular weights of 26,000, 32,000 and 65,000 showed strongly positive reactions with the antinuclear antibodies in the serum of the NOD mouse.     

A computer program that draws pedigree charts for inbred strains of animals

We produced a computer program that draws pedigree charts for inbred strains of animals such as mice or rats. This program is composed of four subprograms, which are (1) inputting the data, (2) drawing pedigree charts, (3) listing the data which have been input, and (4) backup of the system and the data. Pedigree charts and lists of data can be displayed on a TV screen and printed out on the papers. Using this program, we drew the pedigree charts of the inbred strains of rats which we are maintaining by brother-sister inbreeding in our institute and found that there were three sublines in one of the strains, WKAH/Hkm, because of unsuitable maintenance. This program is very convenient to draw the pedigree charts and useful for checking the maintenance of inbred strains or the strains of animal models of human diseases.     

Measurement of lactose concentrations in milk of Microtus montebelli with methylamine reaction

Concentrations of lactose in milk of Microtus montebelli were measured with the method using with the methylamine reaction. In this method, a small amount of sample (0.5 g) was sufficient for assay, and reproducibility and sensitivity were excellent. This method was very useful for measuring of lactose concentrations in experimental small animals. The average lactose concentration in milk of Microtus montebelli was 1.57g/100g, considerably low in comparison with the value of ICR mice (2.70g/100g). The low concentration of lactose in milk was considered to be one of metabolic characteristics of Microtus montebelli as a herbivorous animal.     

Separation and quantification of serum alkaline phosphatase isozymes in the rat by affinity electrophoresis

The purpose of this study was to examine the possibility of separation and quantification of serum alkaline phosphatase (ALP) isozymes in rats by wheatgerm lectin affinity electrophoresis. Cellulose acetate electrophoresis of the liver and bone ALPs without lectin results in overlapping bands, but in the presence of lectin, the mobility of the band of bone enzyme was retarded and well separated from the liver enzyme band. With this affinity electrophoretic method, we determined the serum ALP isozymes in fed and fasting rats grouped by age. As a result, the absolute activity of bone isozyme showed a downward trend with age in the fed and fasting rats. The serum ALP activity was steadily higher in fed rats than in fasting rats, and the increase was due to intestinal ALP isozyme. There was low activity bordering complete absence in liver isozyme under both nutritional conditions. The affinity electrophoretic method provided a rapid, reproducible, and relatively simple technique for further clinical characterization of ALP isozyme in the rat serum.     

Identifying the fluorescent body (F-body) with quinacrine mustard staining of canine

The fluorescent body (F-body) was identified with quinacrine mustard (Q-M) staining in spermatozoon and lymphocyte of canine. Well washed sperm suspension was treated with protease (125 mg/ml) or dispase (2000p. u./ml) and staining with Q-M (final dilution 50 micrograms/ml) for 15 min to 24 hr at 37 degrees C. The lymphocyte cultures from whole blood were prepared as routine human investigation. The chromosomal preparation made by air dry method was stained with Q-M (final dilution 0.5 to 50 micrograms/ml) after pretreatment of enzyme digestion. The examination using a reflected fluorescent microscope revealed that the same F-body in human was present in both spermatozoon (20.1-39.7%) and interphase of lymphocyte (0.37.2%) of male origin.     

Development of nephrotic ICGN mice--the origin, reproductive ability, and incidence of glomerulonephritis

ICGN is a strain of spontaneous nephrotic mice with nonproliferative glomerular lesions. It was derived from an outbred Yok: ICR colony in our laboratory. The renal disease constantly occurred in animals of the first to the tenth generations (greater than 13.0%; 70 days of age). When affected males were mated with unaffected females, the incidence of the disease in their offspring was 38.8% (n = 49) at 70 days after birth. When both parents were affected, their offspring were all affected (n = 12). The disease evenly progressed in both sexes. It usually began 40 to 150 days after birth and death occurred within two months after onset. The animals usually showed sufficient reproductive ability as long as unaffected females were used for mating.     

Does in vitro activation of postsynaptic alpha 2-adrenoceptor utilize intracellular Ca2+ for contraction in dog saphenous vein?

Dog saphenous vein spiral strips were employed to determine whether an intracellular source of Ca2+ is used for contraction upon activation of the alpha 2-adrenoceptor by B-HT 920 in Ca2+-free Krebs solution containing 50 microM EGTA. The studies were carried out in parallel with the activation of the alpha 1-adrenoceptor by phenylephrine (Phe) under the condition that B-HT 920 (10(-5) M) and Phe (2 x 10(-6) M) gave rise to a similar level of responses in Ca2+-containing Krebs solution. A similar level of responses to these agonists at equieffective concentrations in Ca2+-free medium were also observed. Such responses to Phe and B-HT 920 were inhibited by 10(-7) M rauwolscine and 10(-7) M prazosin, respectively, and were not affected by 10(-7) M nifedipine or 5 mM Mn2+. The responses to B-HT 920 (10(-5) M) and submaximal concentration of Phe (2 x 10(-6) M) in Ca2+-free medium were additive. However, if the vascular strips were first contracted maximally with 10(-4) M Phe in Ca2+-free medium to deplete the intracellular Ca store, subsequent addition of B-HT 920 failed to induce additional response. Our results strongly suggest that activation of alpha 2-adrenoceptor in dog saphenous vein in Ca2+-free medium indeed utilizes intracellular Ca2+ for contraction. We also found that the failure of earlier studies to demonstrate the contractile effects of B-HT 920 in dog saphenous vein was due to experimental artifacts derived from the use of high concentration of EGTA and artificial pH-buffering reagent.