CHEMICAL CHARACTER AND PHYSIOLOGICAL ACTION OF THE POTASSIUM ION

1. It is shown that the NH₄ ion acts in cases of antagonism on the egg of Fundulus more like the K ion than the Na ion; this corresponds to the fact that in its general chemical behavior the NH₄ ion resembles the K ion more closely than the Na ion. 2. It is shown that the tolerance of sea urchin eggs towards the Li ion can be increased 500 per cent or more if at the same time a certain amount of Na ion is replaced by K, Rb, or Cs ions. Since in the periodic table Na occupies a position between K and Li it is inferred that the Li and K ions deviate in their physiological action in the opposite direction from the Na ion. 3. These data indicate that the behavior of the K ion in antagonistic salt action (which forms the basis of the physiologically balanced action of ions) is due to its purely chemical character, i.e. its position in the periodic table or rather to its atomic number, and not to those explosions in its nucleus which give rise to a trace of radioactivity.     

DEMONSTRATION OF A FIBRILLAR COMPONENT IN THE CELL WALL OF THE YEAST SACCHAROMYCES CEREVISIAE AND ITS CHEMICAL NATURE

The ultrastructure of isolated cell walls of Saccharomyces cerevisiae from the log and stationary phases of growth was studied after treatment with the following enzymes: purified endo-β-(1 → 3)-glucanase and endo-β-(1 → 6)-glucanase produced by Bacillus circulans; purified exo-β-glucanase and endo-β-(1 → 3)-glucanase produced by Schizosaccharomyces versatilis; commercial Pronase. While exo-β-glucanase from S. versatilis had no electron microscopically detectable effect on the walls, Pronase removed part of the external amorphous wall material disclosing an amorphous wall layer in which fibrils were indistinctly visible. Amorphous wall material was completely removed by the effect of either endo-β-(1 → 3)- or endo-β-(1 → 6)-glucanase of B. circulans or by a mixture of the two enzymes. As a result of these treatments a continuous fibrillar component appeared, composed of densely interwoven microfibrils resisting further action by both of the B. circulans enzymes. The fibrillar wall component was also demonstrated in untreated cell walls by electron microscopy after negative staining. Because of the complete disappearance of the fibrils following treatment with the S. versatilis endo-β-(1 → 3)-glucanase it can be concluded that this fibrillar component is composed of β-(1 → 3)-linked glucan. Bud scars were the only wall structures resistant to the effect of the latter enzyme.     

STUDIES ON CELL METABOLISM AND CELL DIVISION : VII. OBSERVATIONS ON THE AMOUNT AND POSSIBLE FUNCTION OF DIPHOSPHOTHIAMINE (COCARBOXYLASE) IN EGGS OF ARBACIA PUNCTULATA

1. Methods suitable for the determination of diphosphothiamine (cocarboxylase) in eggs of Arbacia punctulata have been developed. Quantitative extraction of the cocarboxylase was effected by combining the use of thiamine hydrochloride in the extraction fluid with critical adjustment of the pH of extraction to pH 6.3–6.7. 2. The unfertilized eggs were found to contain the equivalent of 2 to 3 micrograms of natural yeast cocarboxylase per gm. of wet eggs; the cocarboxylase content of the 30 minute and 10 hour fertilized eggs was somewhat less (Table III). 3. In preliminary experiments, Arbacia egg cytolysates were found to cause pyruvic acid to disappear. The rate of such disappearance was apparently greater under aerobic than under anaerobic conditions; it was also greater for cytolysates from fertilized eggs than for cytolysates from unfertilized eggs (Table IV).     

SOME OBSERVATIONS ON DNA CONTENT AND CELL AND NUCLEAR VOLUME GROWTH IN THE DEVELOPING XYLEM CELLS OF CERTAIN HIGHER PLANTS

List , Albert , Jr . (Douglass Coll., Rutgers U., New Brunswick, N. J.) Some observations on DNA content and cell and nuclear volume growth in the developing xylem cells of certain higher plants. Amer. Jour. Bot. 50(4): 320–329. Illus. 1963.—The developing metaxylem cells of Acorus calamus roots undergo an over-all growth in cell and nuclear volume that may be expressed roughly as a constant ratio of relative growth rates. Within this over-all growth picture, however, there is a periodicity of both nuclear and cell volume growth. Other plants such as Peltandra, Eleocharis, and Dennstaedtia undergo a similar volume growth. Marsilea tracheary elements have an increase in nuclear number per cell by simultaneous divisions. Arisaema metaxylem nuclei go through a series of DNA doublings correlated with nuclear volume doubling and cell volume increase, at least up to the 16- or 32-ploid level. The cells display some tendency to fall into size classes, expressing a pulsation in growth. A fluctuating alternation or stepwise growth of cell and nucleus appears to describe the data more suitably than the allometric growth equation. In Zea, the cell and nuclear volumes for metaxylem cells fit a fluctuating envelope better than the straight line, and there is again the probability that cell volumes fall into size classes related to nuclear volume class. The DNA content of the nuclei was determined to fall into a frequency distribution having peaks at the 4-, 8-, 16-, and 32-ploid equivalent, agreeing with an earlier report for diploid maize. DNA content was highly correlated with nuclear volume in the over-all growth of the metaxylem cells.     

SPHEROSOMES AND MITOCHONDRIA IN THE LIVING FUNGAL CELL

Study of living hyphae of Fusarium oxysporum Schlect., Fomes annosus (Fries) Cooke, Ceratocystis fagacearum (Bretz) Hunt, Basidiobolus ranarum Eidam, and Mycotypha microspora Fenner with phase contrast revealed that these fungi have spherosomes similar to those in vascular plants. The spherosomes are conspicuous in the hyphal tip, suggesting some function other than fat synthesis. It may be that the Woronin bodies reported by other workers are spherosomes. Mitochondria in these fungi are highly pleomorphic and exhibit saltatory movement. They often interact with nuclei in a manner suggesting close membrane contact.     

关于复合呼吸机械负荷生理、心理效应的观察与分析

以12名男性成年为被试者,观察了外加死腔(V_(ADS))与吸气阻力(RI)对呼吸型式、通气功能以及呼吸不适感觉的联合影响。结果表明:(1)V_(ADS)及R_I对吸气相面罩腔(口腔)压力(P_I)及外呼吸功率(W_I)具有协同的增强作用;复合呼吸机械负荷的强度越大,此种协同作用也越加明显。(2)无论V_(ADS)及R_I的比例关系如何,反应呼吸不适感觉强度的类别量值(S)与P_I(或W_I)之间,总是符合共同的线性关系,故可以P_I(或W_I)作为复合呼吸机械负荷的综合强度指标。(3)在所观察范围内,V_(ADS)并不影响对阻力性机械负荷的呼吸调节功能。以上结果对制订呼吸防护装备生理标准有一定意义。