Biophysical studies on subcellular particles V. Effects of temperature on the ferricyanide-Hill reaction, the light-induced pH shift and the light scattering response of isolated spinach chloroplasts

Effects of temperature on the ferricyanide-Hill reaction, thelight-induced pH shift (JpH) and the light scattering response(4LS) of isolated spinach chloroplasts were studied at temperaturesranging from 5 to 60°C. Activities which produce JpH and JLS under actinic illuminationdecreased with a rise in the reaction temperature above 30°Cand disappeared at 50°C. The ferricyanide-Hill reactionat pH 6.0 was stimulated by raising the reaction temperaturefrom 5 to 35°C, was slowed at higher temperatures and wasinactivated at 50°C. 4LS activity at temperatures below20°C depended on the activity of electron transport. With a rise in temperature of a suspension of chloroplasts whichexhibited JLS under actinic illumination, the scattering intensitydecreased. The decrease in scattering intensity was limited,at most, to an extent equal to ALS. The behavior of JLS whichdiffered from that of basal scattering is discussed in connectionwith a mechanism of JLS formation other than the shrinkage-swellingcycle. When activities were measured at 25°C with chloroplastswarmed transiently (2 min) at various temperatures (25–60°C),the dependence of JLS on the wanning temperature was identicalwith that on the reaction temperature, while the activitiesof both ferricyanide reduction and JpH formation were higherthan those measured at the corresponding reaction temperature.This suggested that the mechanism for 4LS formation could beirreversibly altered by a warming treatment and that it wasless stable against heat than the mechanisms of ferricyanidephotoreduction and 4pH formation. That is, transiently warmedchloroplasts showed a similar behavior to alkane-treated chloroplasts.The similarity is discussed in relation to the activity changethrough the possible and common cause of disordering of theorganized structures of lipophilic components in the lamellarmembranes. (Received June 5, 1971; )     

Temperature-Sensitive Behavior of Paramecium caudatum

SYNOPSIS. The effect of temperature on the behavior of swimming cells of Paramecium caudatum has been investigated by photographic analyses of their tracks in uniform temperature, in temperature gradient, or in temperature changing with time. When the cells were placed in the temperature gradient, the frequency of discontinuous directional changes of cells swimming toward the optimal temperature, the temperature of the culture, was much lower than that of the cells swimming in the opposite direction. This difference in the frequency of directional changes explained the observed accumulation of the cells at - the optimal temperature. When the temperature was suddenly changed toward the optimum, a transient decrease of the frequency of directional changes was observed and when the temperature was changed in the reverse direction, a transient increase of the frequency was noted. This transient response to the temperature change was the origin of the dependence of the frequency of directional changes on the swimming direction in the temperature gradient. Finally, the relation between the magnitude of the transient response and the rate of the temperature change was derived.     

K-Casein Suppresses Melanogenesis in Cultured Pigment Cells

The effects of bovine milk proteins on melanogenesis in B16 cells were examined. Both whey protein isolate and casein exhibited depigmenting properties. Among the major protein components of milk—including β-lactoglobulin, α-lactalbumin, α-, β-, and k-casein—only K-casein exhibited the depigmenting effect. However, the carboxyl terminal peptide of K-casein, glycomacropeptide, did not show this activity. Also, K-casein promoted the proliferation of the cells and inhibited the activity of tyrosinase in the cells. These results indicate that K-casein acts as a melanogenesis-suppressing modulator.     

Early oogenesis in the ascidian Ciona savignyi

Summary

Morphology of the germinal epithelium and the early follicular oocyte in the ascidian Ciona savignyi as examined by electron microscopy. The oogenetic part of the germinal epithelium contains oocytes at two different stages and the dark and clear cells. The smaller oocyte contains synaptonemal complexes. The larger oocyte in the initial phase of growth has a conspicuous nucleolus, electron-dense materials and some mitochondria close to the nuclear envelope. The nucleus of the larger oocyte is round and has the smooth contour. The dark cell contains a relatively large nucleus and is sometimes connected to each other by an intercellular bridge. Therefore, the dark cell, which has been suggested to be the progenitor cell of two kinds of accessory cells, may be also the oogonium. The early follicular oocyte just after migration from the germinal epithelium retains most of cytological features similar to those of the larger oocyte. However, the nuclear contour of the early follicular oocyte is uneven. This difference in the nuclear contour probably indicates that such a follicular oocyte is in the second phase of growth.     

Host immunoglobulin G titre and antibody activity in haemolymph of the tick, Ornithodoros moubata

Immunoglobulin G (IgG) in tick haemolymph was analysed immunochemically and biochemically for its antigenicity, antibody activity and relative concentration in a soft tick, Ornithodoros moubata (Murray) sensu Walton 1962 (Acari: Argasidae). Ouchterlony immunodiffusion tests showed that haemolymph from a tick engorged on rabbit IgG (or human IgG) through an artificial membrane, reacted with anti-rabbit IgG (anti-human IgG) but not with anti-human IgG (anti-rabbit IgG). This indicates that haemolymph of the fed tick contains IgG with a similar antigen specificity to host blood IgG. IgG from tick haemolymph was demonstrated by enzyme immunoassay to have the same antibody activity as ingested IgG. The IgG concentration in tick haemolymph was measured by a quantitative single immunodiffusion test. Changes of IgG titre after a bloodmeal were correlated with IgG activity, which was low for 5 days after a bloodmeal and then suddenly increased. The IgG titre reached a maximum 7 days post-engorgement, and remained high for over 4 months during and after oviposition. 125I-labelled IgG was injected into the tick haemocoel to determine the persistence of IgG in the haemolymph. Recovery of labelled IgG was low at 1 and 3 days, and high at 5, 8 and 16 days after engorgement. The data suggest that IgG in haemolymph disappears quickly soon after engorgement possibly by degradation and/or absorption (adhesion to tissues).     

DEVELOPMENT OF THE SEA-STAR, ASTERINA BATHERI GOTO

Using natural spawning and artificial fertilization, the entire process of development from eggs to juveniles was observed in the sea-star, Asterina batheri Goto.
The breeding season of this animal in Tsukumo Bay and Toyama Bay is estimated to be late summer. The spawned eggs are approximately 430 μm in diameter and float near the surface of sea water. They develop, through a wrinkled blastula stage by holoblastic. radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis takes place while the brachiolariae are swimming. Ten days after fertilization, metamorphosis is complete; the resulting juveniles are about 800 μm in diameter and colored pale brown with a green tint. They bear 2 pairs of tube-feet and a terminal tentacle in each arm.
Development of this species is thus of the direct type, and very similar in every respect to that of Asterina coronata japonica , which is closely related to the present species.     

Meiotic Protein in Spermatocytes of Mammals

THE DNA-binding protein in meiotic cells of Lilium¹ has a very high binding affinity for single stranded DNA and also the unusual property of catalysing the renaturation of thermally denatured lily DNA at room temperature. Significantly, these and other in vitro properties are very similar to those of the “gene 32-protein” which is essential to genetic recombination in T4 bacteriophage² and the possibility that this protein may have a function in meiotic recombination of Lilium led us to a more extensive study of its behaviour³.     

Implications of Differential Chemotaxis and Cohesiveness for Cell Sorting in the Development of Dictyostelium discoideum

Cell sorting behavior was observed during the development of Dictyostelium discoideum Ax-2, between cells grown with [G(+) cells] and without [G(−) cells] glucose. Development of the G(−) cells was about 2-3 hr faster, as reflected by differences in chemotactic sensitivity of the cells and cell cohesiveness. Among various mixing combinations of G(−) and G(+) cells, the most clear sorting occured when vegetative G(+) cells were mixed with G(−) cells which had been allowed to develop for 3 hr, the G(−) cells being located in the anterior prestalk region of a migrating slug. In contrast, vegetative G(−) cells moved to the posterior prespore region of a slug when mixed with G(+) cells which had developed for 6 hr. These findings indicate a close relationship of the cellular developmental stage to the sorting behavior. Possible implications of the differential chemotactic ability and cohesiveness for the sorting mechanism are disscussed.     

Ultrastructural Changes of the Two Types of Differentiated Cells during the Migration and Early Culmination Stages of Dictyostelium discoideum

Changes of fine structure during prolonged migration of Dictyostelium discoideum slugs were studied by electronmicroscopy. Prespore specific vacuoles of cells located near the substratum gradually degenerated and the prespore antigen contained in them was lost. During the process, mitochondria in the prespore cells were transformed dramatically: as the mitochondrion elongates, its central part becomes thinner and the cristae become localized at its two ends. Then it bends and its two ends fuse to segregate part of the cytoplasm. The cristae then accumulate in the original ends. Similar mitochondrial transformation was observed in prespore cells of cell masses induced to culminate after a long period of migration.     

The Inhibitory Effect of Glabridin from Licorice Extracts on Melanogenesis and Inflammation

Glabridin is the main ingredient in hydrophobia fraction of licorice extract affecting on skins. In this study, we investigated inhibitory effects of glabridin on melanogenesis and inflammation using cultured B16 murine melanoma cells and guinea pig skins. The results indicated that glabridin inhibits tyrosinase activity of these cells at concentrations of 0.1 to 1.0 μg/ml and had no detectable effect on their DNA synthesis. Combined analysis of SDS-polyacrylamide gel electrophoresis and DOPA staining on the large granule fraction of these cells disclosed that glabridin decreased specifically the activities of Tl and T3 tyrosinase isozymes. It was also shown that UVB-induced pigmentation and erythema in the skins of guinea pigs were inhibited by topical applications of 0.5% glabridin. Anti-inflammatory effects of glabridin in vitro were also shown by its inhibition of superoxide anion productions and cyclooxygenase activities. These data indicated that glabridin is a unique compound possessing more than one function; not only the inhibition of melanogenesis but also the inhibition of inflammation in the skins. By replacing each of hydroxyl groups of glabridin with others, it was revealed that the inhibitory effect of 2′-O-ethyl glabridin was significantly stronger than that of 4′-O-ethyl-glabridin on melanin synthesis in cultured B16 cells at the concentration of 1.0 mg/inl. With replacement of both of two hydroxyl groups, the inhibitory effect was totally lost. Based on these data, we concluded that two hydroxyl groups of glabridin are important for the inhibition of melanin synthesis and that the hydroxyl group at the 4’ position of this compound is more closely related to melanin synthesis.