Summary

Nitrate reductase A: In anaerobic cultures of several Enterobacteriaceae on a complex medium without NO₃^-, the biosynthesis of enzyme A is induced by 5.88·10^-3 M nitrite or by 10^-4 M azide. In the case of several bacteria, the activity of extracts of cultures induced by both NO₃^- and N₃^- is higher than that of extracts of cultures induced by only one of these 2 compounds.

Nitrate reductase B: 10^-4 M azide does not induce the biosynthesis of enzyme B in the 3 bacteria studied.

Summary

Four acid rice-soils (0–20 cm, air-dry, and <2 mm) were subjected to 3 cycles, each consisting of 30-day submergence followed by air-drying at room temperature or oven-drying at 105°C for 3 days. The available phosphorus was determined colorimetrically by Bray's P-2 extractant (0.03N NH₄F+0.1N HCl) using 1:20 soil extractant ratio.

The beneficial effect of 30-day submergence followed by drying of soil prior to resubmergence on native phosphorus was apparent in all soils studied except Shirgaon clay soil, which was probably due to presence of relatively more active Fe in that soil.

Synopsis

This paper describes a general method for the determination of the molar extinction ceefficient of a chromophore covalently bound to structure-linked groups, without isolating the compound formed. The method is illustrated by the determination of the molar extinction coefficient of the reaction product of 2,4-dinitro-1-fluorobenzene (DNFB) with films of aminoethyl-cellulose (AE-cellulose). The method is based on the relation between the decrease in extinction of a DNFB staining solution and the increase in extinction of the AE-cellulose after staining as measured in a film-spectrophotometer. In addition, the value of the molar extinction coefficient was used in establishing reaction conditions for a quantitative staining procedure for determining amino groups with DNFB and picric acid. Conditions of optimum DNFB staining were determined and the measured extinction was converted into concentration of amino groups using the molar extinction coefficient. The amino group concentration of the same batch of AE-cellulose was also determined, after finding the optimum reaction conditions, by staining with picric acid. The results, when compared, showed a linear relationship with a slope of unity for batches of AE-cellulose of varying amino group concentrations. This is consistent with the same stoichiometry in both cases and indicates that in both procedures one chromophore molecule has reacted with one amino group and that this reaction has proceeded to completion. The general applicability of the method is discussed.

Summary

Comparison of clay and plastic pots for tomato propagation in six experiments showed plastic pots to give significantly better results than clay pots in winter and the converse to be true in summer. In each experiment the ratio of plant growth (dry weight) in clay and plastic pots was related to both the mean daily solar radiation and the mean outside night minimum temperature. In winter, plants in both types of container made significantly more growth when stood on open benches than when stood on benches with solid surfaces.

These differences in growth were related to soil temperature, clay pots being cooler than plastic pots, the temperature difference between the types of pot ranging from approximately 1°C by night in winter to 4°C under high intensity solar radiation in summer. In winter, soil temperatures were often below the optimum, and in summer in excess of the optimum.

By day, temperature within the pots showed highly significant correlation with solar radiation, and by night in winter pot temperature was negatively correlated with the difference between the glasshouse and the outside air temperature.

Well-defined horizontal thermal gradients were found, and these were positively correlated with soil temperature. In wet soils the thermal gradients were less than in dry soils, and because of their higher thermal conductivity wet soils were warmer than dry soils.

When the normal evaporative cooling from the porous walls of clay pots was prevented by a bituminous coating, the soil temperature during the night was not significantly different from that in plastic pots. By day, however, soil temperature in non-evaporating clay pots was less than that in evaporating clay pots, due to the lower thermal conductivity of the dry clay wall.

Owing to a critical examination of the taxonomic characteristics ofOscillatoria, such as gas vacuoles, calyptra, sheath, arrangement of the trichome, etc., this family has to be redefined. It is divided into two tribes: 1.

The ‘Vaginariées’ or rather the Schizothricées (Oscillatoria which have developed sheaths withseveral trichomes).

2.

The ‘Lyngbyées’, with or without sheath which only contain one trichome.

The first tribe includes the speciesSchizothrix (encompassingHydrocoleum, Dasygloe, Oligoclonium, Lyngbyopsis), Microcoleus (withSirocoleus) andPorphyrosiphon. The tribe of the ‘Lyngbyées’ is composed of theOscillatoria species (includingSpirulina, Arthrospira, Spirulinopsis, Glaucospira [?] andJuguspira [?]),Lyngbya (withPhormidium, Symploca, Katagnymene, Pelagothrix, Haliarachne, Proterendothrix, Cirrosiphon, Cyanohydnum) andCrinalium.

The systematic position fo the four speciesIsocystis, Borzia, Sinaiella andPseudanabaena is somewhat doubtful and must be examined more closely for clarification.

Fungi, or Eumycota (eu = true; mykes = fungus), are eukaryotic organisms that lack chlorophyll. Being nonphotosynthetic, fungi depend on the products of other organisms, either living or dead, for food. Their ability to break down and utilize a wide variety of complex compounds accounts for their being able to live on a myriad of organic substrates. While fungi are ubiquitous as a group, the individual species usually are more limited in their nutritional tolerances. Fungi are of great economic importance. Some are parasites of animals and man. Many are virulent parasites of crop plants, resulting in considerable loss of food to man. Some fungi have by-products such as antibiotics and organic acids which man can use. Yeasts are indispensable to baking and brewing industries. Characteristic flavors of cheeses result from the presence of certain fungi; for example, Roquefort and Camembert cheeses are flavored (and colored) by the growths in the cheeses of Penicillium roqueforti and P. camemberti, respectively. A large industry is devoted to the culture of mushrooms for market. In addition, several fungi, such as morels and truffles, are highly prized by gourmets.

Summary

Sixteen-cell stages of the sea urchin Paracentrotus lividus were separated into animal and vegetal halves. The former were reared in four different media: pure sea water, sea water with 10 μg/ml actinomycin D, sea water with 0.043 mol lithium, sea water containing the same concentration of lithium together with 10 μg/ml actinomycin D. The main result of the study was that the development had a more animal character after combined exposure to actinomycin D and lithium than after exposure to lithium alone. The inference from this result is that transcription processes are involved in the vegetalization of lithium treated sea urchin embryos.

The differentiation of the animal halves occurring in normal sea water is widely repressed in the presence of actinomycin D. Particularly obvious is the fact that the transformation of the acron with ensuing substitution of the long stereocilia by short motile cilia fails to occur in the presence of actinomycin D. The transformation of the acron and its stereocilia seem thus to be dependent on transcription processes.

In animal halves reared in normal medium droplets, dark in phase contrast, may appear near the tip of the stereocilia. This is followed very soon by the shedding of the stereocilia. In animal halves treated with actinomycin D, the droplets appear in a somewhat later stage than in the halves reared in normal sea water. After their appearance, the stereo cilia acquire a certain motility. The droplet formation may correspond to the elimination of a component which stiffens the stereocilia. The elimination of this component does not seem to be directly dependent of transcription processes. On the other hand, the stability of the stereocilia decreases with the distance from the animal pole.

The data obtained in this investigation may be integrated into the double gradient concept, also in its recent elaboration (Runnström, 1967).

The present investigation was carried out at Stazione Zoologica, Naples. We are deeply indebted to Professor M. Pantaleo, head of this institution, for his interest and generous support. We express also our gratitude to Professors R. Martin and R. Rocca for their help and friendly interest. One of us expresses his gratitude to Professor M. Pantaleo for the award of a research grant from the Stazione. He recognizes also his indebtedness to Professor M. De Vincentiis, director of the Department of Histology and Embryology at the University of Naples. The second of us expresses his thanks for financial support from the “Swedish Natural Sciences Research Council”, from the “Swedish Cancer Society” and from the “Research group of embryology for the study of cellular differentiation ” of the Department of Zoology, University of Rome. He expresses his sincere thanks to the Director of this Department, Professor P. Pasquini, for his stimulating interest.

The setal pattern of Pterophorid first larval stages is homologized to the hypothetical pattern of the Ditrysia ancestor; it is utilized to reconstruct the ancestral pattern of the three European subfamilies and to classify them genealogically. For infra- and interspecific analysis, the setal characters of Pterophorinae are discussed in combination with the morphologic characters of the genitalia, which for this purpose are presented in detail.

The physiological regulation of coronary flow is still a matter of dispute (Berne 1964, Schaper 1967). It has been speculated that kinins may play a major role in coronary regulation (Parrat 1964, Scholtholt et al. 1965), since they have a powerful action on the coronary system. Four different approaches were made in order to elucidate the significance of the kinin system in coronary regulation: (a)

Use of kinin antagonists

(b)

Experimental increase of carboxypeptidase B concentration by constant intracoronary infusion

(c)

Administration of kininase inhibitors

(d)

Perfusion with a kininogen-free red cell suspension in a buffered dextran solution