DIRECT ISOLATION OF NATIVE THIN FILAMENTS FROM EMBRYONIC MUSCLE CELLS*

A method is presented for the release of “native” thin filaments from 13-day old embryonic chick muscle without tryptic digestion or desoxycholate (DOC) solubilization of Z bands. The isolated filaments were 50–60 Å in diameter, of variable length, and formed “arrowhead-like” complexes with heavy meromyosin (HMM). In addition, the filaments interacted with purified myosin to form actomyosin as effectively as action extracted from an acetone powder of muscle. The Mg⁺⁺-dependent ATPase activity and extent of superprecipitation of the synthetic actomyosin required a low concentration of Ca⁺⁺, strongly suggesting the presence of troponin and tropomyosin on the thin filaments isolated from muscle at this stage of embryogenesis. The native thin filaments were more sensitive to trypsin than synthetic F-actin prepared from an acetone powder based on measurements of flow birefrengence, viscosity and the ability to activate myosin ATPase.     

Germination responses of a seed population of Taraxacum officinale Weber to constant temperatures including the supra-optimal range

Abstract The germination responses of a nondormant fraction of a seed population of Taraxacum officinale Weber at constant temperatures in the range 7–34°C were analysed through a time-course study. Maximal percentage germination (approximately 90%) was attained at temperatures 10–18°C, where simple linear relationships were observed between the temperature and the germination rates, i.e. the reciprocals of the time taken to germinate by subpopulations with 20–80% germination. There was a variation in the required ‘thermal times’ (θ) which characterized the linear relationships, the distribution of which could be approximated for the seed population by the following distribution function: where m is the median of the distribution, and A is a shape parameter characterizing the pattern of the distribution. Final percentage germination decreased with increasing temperature from 20 to 32°C, where the final percentage germination vs. temperature plotted on a normal probability scale yielded a straight line, indicating the normality of the distribution of the upper limit temperature in the seed population. The estimated mean and standard deviation were 27.25 ± 3.75°C. The rate of germination for the subpopulation with 20–80% germination also decreased with increases in the temperature from 22 to 30°C. If the relationships between the temperature within this range and the rate for the subpopulations with 20–80% germination were approximated by the regression lines, the negative ‘thermal time’ characterizing the yielded linear relationship would have a distribution which could be approximated by the same function with the required thermal time for the relationship of suboptimal range. The parameters m and A for the negative ‘thermal time’ were determined to be 2870 K h and 1.7 × 10^-10 K^-3 h^-3.     

Behavior of a Virus in a Symbiotic System, Paramecium bursaria—Zoochlorella

SYNOPSIS In a culture system of Paramecium bursaria , virus particles were found in large number. The particle was able to infect and multiply in certain cells of the zoochlorella, an intracellular symbiotic alga of P. bursaria. The infective particle, designated as zoochlorella cell virus (ZCV), was icosahedral and 120–180 nm in edge to edge diameter. The ZCV particle was found to differ from any of the already established viruses attacking the green and the blue-green algae. Within the system where P. bursaria cells were growing, ZCV particles were detected in the depression of the pellicle, among the cilia growing in the cytopharynx, and in the food vacuole of P. bursaria. ZCV particles were infective only for the zoochlorella cells which were recently released from the cytoplasm of P. bursaria. The multiplication process of ZCV comprised the adsorption of the particle to the cell wall of the zoochlorella, the penetration of nucleic acid into the host cell interior, the replication of viral constituents, the maturation of viral particles and their final release by the burst of the zoochlorella cell. ZCV particles appeared only in the cytoplasmic region of the zoochlorella cell in which many ribosomes were distributed. A possible ecosystem among the 3 members consisting of P. bursaria , zoochlorella and ZCV is discussed.     

STAGING OF NEWT BLASTULA EMBRYOS AND FIRST APPEARANCE OF PRIMARY MESODERMAL COMPETENCE

Using the swimbladder of the crusian carp ( Carrasius auratus ) as an inductor, the first appearance of mesodermal competence in the presumptive ectoderm of the newt ( Triturus pyrrhogaster ) blastula was investigated. The time course of embryonic development before the gastrula stage was determined by counting the number of surface cells on a 0.25 mm line at the animal pole. Pregastrula embryos with 2–3, 4–5, 6–7 and 7–8 cells roughly correspond to those at 14, 14–12, 8–6 and 4–0 hr before the beginning of gastrulation. Using presumptive ectoderm of the early gastrula stage, 15 min was found to be the minimum time of contact necessary for the realization of induction. The reactivity of the presumptive ectoderm from pregastrula embryos was tested by 30 min contact. Presumptive ectoderm up to the 4–5 cell stage did not react to the inductor. It may become competent within the next 4–8 hr, since the ectoderm from embryos in the 6–7 cell stage was reactive.     

Post‐pollination process in a partially self‐compatible distylous plant,Primula sieboldii (Primulaceae)

Pollen germination and pollen‐tube growth under natural conditions were observed in a population of a distylous species, Primula sieboldii, in which partial self‐compatibility has been demonstrated in some long‐styled genets. We observed post‐pollination processes microscopically in styles collected after self‐morph and inter‐morph hand pollination (with standardized pollen load on the stigmas) in four genets each from the following three ‘genet types’: self‐incompatible long‐styled (SI), partially self‐compatible long‐styled (SC) and self‐incompatible short‐styled morph genets. Irrespective of the genet type, pollen germination began within 24 h after pollination and tubes of pollen reached to the style base with 48–96 h after inter‐morph pollination. Although pollen tubes germinated after self‐pollination in the SC genets, the number of germinated pollen tubes was significantly lower than in the case of inter‐morph pollination. Few pollen tubes germinated after self‐pollination of the SI or short‐styled genets. In SC genets, the rate of pollen‐tube growth did not differ between self‐morph and inter‐morph pollination (～1.9 mm/day). Therefore, differences in self‐compatibility between SC and SI genets in P. sieboldii are likely to be attributable to differential pollen germination rates rather than to differential pollen‐tube growth rates.     

DIFFERENTIATION OF ACTIVITY PATTERNS IN THE SUPRAHYOID MUSCLES DURING SWALLOWING OF FOODS WITH FIVE TASTE QUALITIES

Activity patterns of the suprahyoid muscles were examined using a new analytical technique. The suprahyoid activities were recorded during swallowing of tasteless foods and foods with taste qualities (sweet, salty, sour, bitter and umami). The technique involved: (1) division of cumulative integrated suprahyoid activities from each swallow into 10 equal sections and (2) assignment of individually sectioned activities to a standardized timescale as T_P (from T₁₀To T₁₀₀; relative time for P% of the cumulative electromyogram) to enable comparison of data from different trials. Three significant differences were found in T _p between the following foods: tasteless and sour, tasteless and bitter, and sour and umami. However, the differences were not repeatedly confirmed. These results suggest that gustatory signals from food tastes affect differentially the activity patterns of the suprahyoid muscles during pharyngeal swallowing, although the effect is not permanent. This method may be used to measure taste impressions in infants and in certain disabled subjects.     

Anti-oxidation activity of ethanol extracts from natural thalli of lichens

Screening test on anti-oxidation activity using 1,1-diphenyl-2-picrylhydrazyl(DPPH) was performed for 99 ethanol extracts of 85 species of natural thalli of lichens in order to find novel anti-oxidation compounds.The 17 extracts of natural thalli showed high anti-oxidation activity.Among them,the activities of extracts from Hypogymnia vittata,Peltigera aphthosa,Nephromopsis ornata,Pseudevernia furfuracea,Cladonia vulcani and Peltigera elizabethae were higher.Extracts of Peltigera spp.showed higher activity than those of other genera.The ethanol extract of P.aphthosa had been separated into ethyl acetate-soluble and water-soluble fractions.Two anti-oxidative spots were found only in the water-soluble fractions by thin-layer chromatography.The compound in the lower spot had the same Rf value,UV spectrum,and color as authentic solorinine that was previously found as a unique quaternary ammonium compound from Peltigera spp.We now report that the hydrophilic lichen substance,solorinine showed a nearly same anti-oxidation activity(EC50=120?mol/Lol/L) as standard antioxidant Trolox(EC50=150?mol/L).