Prevention of freeze denaturation of carp actomyosin by sodium glutamate.

1) Denaturation of carp actomyosin during storage at -20 degrees was studied with particular interest in the cryoprotective effect of sodium glutamate, the most cryoprotective of the compounds tested previously. 2) Storage with glutamate prevented the rapid decrease in solubility, viscosity, and ATPase (EC 3.6.1.3)activity of actomyosin during storage. Ultracentrifugal studies suggested that aggregation occurred in the frozen state without glutamate, but that added glutamate prevented aggregation or denaturation. 3) Electron microscopy showed that the original actomyosin consisted of long filaments with typical "arrowhead" structures, and that these decomposed into small fragments and sticked with globular portions, forming loosely packed aggregates during storage without glutamate. On storage with glutamate, the filaments were well preserved, and their fine structure was clearer than that of the original sample. 4) Preparations of actomyosin extracted with 10 mM glutamate were of better quality and their ultrastructure and physicochemical and biochemical properties showed increased stability on freezing. 5) Freeze-denaturation seems to involve complicated aggregation with transconformation of proteins besides the side-to-side aggregation discussed previously.     

Diauxic Growth of Propionibacterium shermanii

Propionibacterium shermanii has been anaerobically propagated in batch and continuous culture with glucose and/or lactate as energy source. Specific growth rate on lactate was observed to be the same as that on glucose. In terms of cell density, the yield on glucose is higher than the yield on lactate. But the molar ratio of yield on glucose to that on lactate, 8.35, is in good agreement with the theoretical value of 8. In a mixture of glucose and lactate, P. shermanii showed diauxic growth. It used lactate before glucose utilization began. Neither temporary growth cessation nor two distinct growth phases were observed. A mathematical model is proposed to describe the diauxic growth.     

Predator-Prey Interactions of Dictyostelium discoideum and Escherichia coli in Continuous Culture

Dictyostelium discoideum and Escherichia coli were aerobically propagated in mixed continuous culture in a predator-prey relationship, and the effects of temperature and holding times were examined. Oscillations developed in the concentration of glucose, the limiting substrate for E. coli, and in the densities of the two populations, but eventually steady-state populations were reached. The experimental data were analyzed according to the Lotka-Volterra model for prey-predator relationships and by the Monod model for saturation kinetics. A comparison of the adequacy of the two models in describing predation is given.     

Identification of Candida isolated from the cutaneous candidiasis by the combined use of confirmatory medium and slide agglutination with monofactorial antibodies

Forty strains ofCandida and one ofTorulopsis were isolated from patients with cutaneous candidiasis. The isolates comprised 29 strains ofC. albicans, 7 strains ofC. tropicalis, 2 strains ofC. guilliermondii, and one each ofC. parakrusei, C. lipolytica, andT. famata were identified by the ordinary method. Besides the common pathogenC. albicans, a few other species ofCandida may be etiologic organisms of cutaneous candidiasis. These strains were re-examined by combined use of sucrose agar slants and slide agglutination tests with IgG monofactorial antibodies as a rapid identification method, especially for determining serotypes ofC. albicans. The new method was useful and reliable for rapid identification ofC. albicans and related species. All strains ofC. albicans isolated from skin lesions proved to be standard serotypes ofC. albicans.

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Zusammenfassung Vierzig Stämme vonCandida und eins vonTorulopsis wurden aus Kranken mit kutanen Candidamykosen isoliert. Neunundzwanzig Stämme vonC. albicans, 7 vonC. tropicalis, 2 vonC. guilliermondii, und je einer vonC. parakrusei, C. lipolytica undT. famata wurden mit dem ordinären Methode identifiziert. Außer dem gewohnlichen Erreger,C. albicans, konnten auch ein Paar andere Spezies vonCandida als den Erreger betrachtet werden. Sechsunddreißig Stämme vonC. albicans undC. tropicalis wurden mit der von uns verbesserten kombinierten serologischen und biologischen Methode untersucht, besonders um den Serotypus vonC. albicans festzusetzen. Die neue Methode war gut und zuverlässig als die rapide Identification vonC. albicans und verwandten Spezies. Alle aus der Hautläsion isoliertenC. albicans waren der in Japan allgemeine Serotypus vonC. albicans.

     

Direct Fick application for measurement of cardiac output in rat.

The direct Fick procedure for cardiac output determination in rat was validated by simultaneous comparison with electromagnetic flowmeter techniques. Significant coefficients of correlation were obtained between absolute cardiac output values (r = 0.789, P less than 0.001), increases (r = 0.768, P less than 0.001) and decreases (r = 0.672, P less than 0.01) in cardiac output detected by the two methods. As demonstrated in other species, cardiac output values of the Fick procedure in the rat were between 40 and 58% greater than respective electromagnetic flow probe values; however, percent changes in cardiac output obtained by the two methods were similar. The larger values of cardiac output obtained by the direct Fick method may be related, to a great extent, to the distribution of blood flow to the coronary and bronchial circulations. Fick cardiac output measurements were reproducible within rats, and the degree of variation in values among rats was similar to that obtained with the flowmeter procedure. The result indicate that the Fick meth od provides a valid estimation of cardiac output in the rat, with the ability to detect moderate changes (22-36%) in cardiac output.     

Tritiated thymidine autoradiographic study on the origin and renewal of argentaffin cells in the pyloric gland of hamsters

Summary The origin and renewal of the argentaffin cells in the pyloric glands of hamsters were studied by flash, cumulative and pulse labelling autoradiography with ³H-thymidine. The argentaffin cells were identified by the Diazo Method using Fast Red B Salt.By flash labelling autoradiography, it was shown that the argentaffin cells located from the middle to the lower level of the pyloric mucosa were not labelled with ³H-thymidine, indicating that this cell type has no proliferative activity. On the 10th and the 20th day of cumulative labelling, 31% and 63% of the argentaffin cells in the gland were found to be labelled, respectively. The labelled argentaffin cells were concentrated in the upper part of the gland (around the region of the isthmus), and no label was found over nuclei of the cells at the lowermost level of the gland. These labelled cells were shown to undergo a downward migration in the days following pulse labelling. They were replaced by unlabelled (and weakly or very weakly labelled) cells which arose at the region of the isthmus. The argentaffin cells in the pyloric gland are thought to arise from epithelial precursor cells at the region of the isthmus.The labelled argentaffin cells in the gland were found to decrease in number almost exponentially after pulse labelling. This indicates that the life span of argentaffin cells is not fixed, but their renewal conforms to the random loss system. The half time of turnover of this cell population was 15 days on average.Supported by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan     

Na+ (Li+)-proline cotransport inEscherichia coli

Summary Na⁺ and Li⁺ were found to stimulate the transport ofl-proline by cells ofEscherichia coli induced for proline utilization. The gene product of the put P gene is involved in the expression of this transport activity since the put P⁺ strains CSH 4 and WG 148 show activity and the put P^– strain RM 2 fails to show this cation coupled transport. The addition of proline was found to stimulate the uptake of Li⁺ and of Na⁺. Attempts to demonstrate proline stimulated H⁺ uptake were unsuccessful. It is concluded that the proline carrier (coded by the put P gene) is responsible for Na⁺ (or Li⁺)-proline cotransport.