Effect of Glutaraldehyde on the Outer Layers of Escherichia coli

S ummary : Sodium lauryl sulphate (SLS) at pH 3 and 8 lysed cell walls of Escherichia coli. Pretreatment with glutaraldehyde at pH 3 and at pH 8 prevented this lysis. SLS induced maximum lysis of E. coli cells at 40°; pretreatment of cells with glutaraldehyde prevented this lysis also. Electrophoretic studies indicated that glutaraldehyde accumu lated on the surface of E. coli cells more rapidly in acid than in alkaline conditions, and that it blocked amino groups on the surface layer of Bacillus subtilis spores. The relationship of these findings to the bactericidal efficiency of glutaraldehyde in acid and alkaline solution is discussed.     

The in vitro synthesis and characteristics of ribosomal RNA in imaginal discs of Drosophila melanogaster

Summary Late third instar imaginal discs of Drosophila melanogaster cultured in vitro in Robb's tissue culture medium synthesize 38S, 28S and 18S ribosomal RNAs which are qualitatively indistinguishable from their in vivo synthesized counterparts (Fig. 1). As found in other insect systems, the 38S molecule appears to be the precursor for both the 28S and 18S rRNAs (Figs. 2, 3 and 4). The 28S rRNA and a portion of the 38S pre-rRNA shift in sedimentation value upon exposure to heat or dimethylsulfoxide (Figs. 5 and 8). Studies of the thermal denaturations of these molecules (Figs. 6, 7 and 9) indicate the existence of a single class of 28S rRNA, but three classes of 38S pre-rRNAs. The addition of -ecdysone to the in vitro culture medium stimulates the net amount of rRNA synthesized, increases the rate of processing of the 38S precursor and increases the relative amount of 18S material produced (Figs. 10 and 12).This work was supported in part by grants from the National Science Foundation (GB-8176) and from the Atomic Energy Commission (AT-04-3-34).Predoctoral Trainees, PHS Training Grant No. 2-Tl-GM367 from Research Training Grants Branch, National Institute of General Medical Sciences.1 For purposes of simplification we shall refer to the rRNA molecules of D. melanogaster as being 38S, 30S, 28S and 18S; however, it should be noted that these values are approximate (see Hastings and Kirby, 1966; Greenberg, 1969; Tartof and Perry, 1970).     

Inhibition of enzymes by metal ion-chelating reagents. Theory and new graphical methods of study

1. The mechanism of inhibition of enzymes by metal ion-chelating reagents is discussed and equations derived. 2. Two distinct mechanisms are postulated and graphical methods are given for differentiating between them. 3. Where the metal ion is actually removed from the enzyme to form a co-ordination complex in solution, a procedure is described for obtaining the stability constant for metal-enzyme interaction, the number of metal ions involved and the stoicheiometry of metal ion-ligand interaction.     

Purification of human placental alkaline phosphatase. Salt effects in affinity chromatography

Human placental alkaline phosphatase was chromatographed on Sepharose derivatives of d- and l-phenylalanine, l-leucine, glycine, aniline and p-aminobenzoic acid in high concentrations of (NH(4))(2)SO(4). Retention on these columns was greatest at the highest concentrations of (NH(4))(2)SO(4). By using decreasing concentrations and changing the types of salts, elution was effected from each of the columns. The (NH(4))(2)SO(4)-mediated retention appeared to be related to the hydrophobic character of the substituted Sepharose, rather than to any specific binding site of the enzyme. It is suggested that this provides a way of controlling hydrophobic affinity chromatography. By use of chromatography on l-phenylalanine-Sepharose and of DEAE-Sephadex chromatography in the presence of Triton X-100 detergent, a preparation of highly purified (1000-fold) human placental alkaline phosphatase was obtained in 22% yield.     

Inherited and/or conditioned changes in host-plant preference in Pieris

The ability to survive of a phytophagous insect, as illustrated by the genus Pieris, is a quantitative phenomenon, not an all or none reaction. This has been shown by various tests involving Pieris rapae and P. protodice on each of six different larval food plants. There are significant genetic differences between these species with regard to survival, growth rate and size differences. Strains of P. rapae have been induced to prefer one or another host-plant by prior conditioning on that plant. Prior conditioning is effective during the life of the larva (1 st to 5th instars), or the individual (larva to adult) or subsequent generations. Hybridization between conditioned strains gives (1) the effect of hybrid vigor and (2) multiple factor differentiation of F₁ and F₂ progeny. Testing of conditioned strains indicates that the larvae select not only different plants but also different concentrations of mustard oil. The F₁ larvae select a concentration intermediate between parental strains. The F₂ select a wider range. Similar tests on oviposition selection by adult females derived from conditioned strains indicate that the females follow the larval conditioning pattern, with similar results on inheritance. Conditioned strains have been shown to be alterable; that is, a strain conditioned to one plant can be reconditioned to another and vice versa. The process is constantly reversable as long as there are individuals which survive the changes.

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Zusammenfassung Wie an der Gattung Pieris gezeigt wird, ist die Fähigkeit eines phytophagen Insekts, zu überleben, ein quantitatives Phänomen, keine Alles-oder-Nichts-Reaktion. Dies hat sich bei verschiedenen Untersuchungen mit Pieris rapae und P. protodice an jeder von 6 verschiedenen Larven-Futterpflanzen gezeigt. Im Hinblick auf Überlebensdauer, Wachstumsrate und Größenunterschiede bestehen zwischen diesen Arten signifikante genetische Unterschiede. Stämme von P. rapae können durch vorangehende Gewöhnung (conditioning) an eine oder die andere Wirtspflanze zur Bevorzugung der betreffenden Fraßpflanze gebracht werden. Anpassung durch vorangehende Gewöhnung ist während des Larvenlebens (vom 1. bis 5. Stadium) oder während der einzelnen Entwicklung (Larve bis Imago) oder während aufeinanderfolgender Generationen wirksam. Kreuzungen zwischen so angepaßten Stämmen ergaben 1. den Effekt der Hybridsteigerung und 2. die Vielfach-Faktoren-Trennung in der F₁-und F₂-Nachkommenschaft. Prüfung der angepaßten Stämme zeigten, daß die Larven nicht nur verschiedene Pflanzen, sondern auch verschiedene Konzentrationen von Senföl wählen. Die F₁-Larven wählen eine Konzentration, die intermediär zu den von den Ausgangsstämmen bevorzugten liegt. Die F₂ wählt einen weiteren Bereich. Entsprechende Untersuchungen über die Wahl der Eiablage-Pflanzen durch reife Weibchen aus angepaßten Stämmen erwiesen, daß die Weibchen den larvalen Gewöhnungsmustern folgen, mit entsprechenden Konsequenzen für die Vererbung. Es ließ sich zeigen, daß angepaßte Stämme abgeändert werden können, d.h. daß ein an eine Wirtspflanzenart gewöhnter Stamm auf eine andere umgestimmt werden kann und umgekehrt. Dieser Vorgang ist konstant umkehrbar, solange nur einzelne Individuen die Veränderungen überleben.

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Aided by the National Science Foundation, Washington, D.C., the California Arboretum Foundation, Inc. and the California State College, Los Angeles.     

Preparation and some properties of stable and carbon-14 and tritium-labeled short-chain aliphatic hydroxamic acids

A simple and safe procedure has been described for the preparation of short-chain aliphatic hydroxamic acids in quantities as large as 1 mole and as small as 0.01 mole. The procedure is equally suitable for the preparation of isotopically labeled hydroxamates, as has been demonstrated in the case of 1-¹⁴C-acetohydroxamic acid and ³H-acetohydroxamic acid. Some physical and chemical characteristics, including infrared spectra of formo-, aceto-, propiono-, and isobutyro-hydroxamic acids prepared by this method have been described.     

Phytochrome Control of Nyetinasty in Samanea as Modified by Oxgen, Submergence, and Chemicals

Samanea saman has rapid phytochrome-regulated nyctinasty: red light preceding darkness causes pinnules to close while far-rod light allows opening- Not only the initial angle of the pinnules, but the degree of control by phytochrome depends on the “subjective time of day” at which the tissue is exposed. Excised pairs of pinnules close rapidly when submerged in water; such closure is prevented by bubbling oxygen through the water. However, if submergence closure were due solely to low oxygen levels, then nonsubmerged pinnules in a pure nitrogen atmosphere should also close. Instead, they neither close nor respond to light, but they do respond when air is readmitted, indicating that oxygen is necessary for movement rather than for photoreception. The closure of submerged pinnules remains unexplained. Attempts to detect effects of red or far-red on oxygen uptake by pulvinus tissue were unsuccessful. The following method has been used to test the effects of various inhibitors and other substances: pinnules are excised at the first hour of the day, trimmed, submerged in a sealed chamber, given far-red light, and left in darkness while oxygen is bubbled through the medium. Concentrated test solutions are injected either initially or when the red and far-red exposures are given. Thus far, the substances tested have had little or no effect on the phytochrome response.     

Capsella embryogenesis: The suspensor and the basal cell

Summary The suspensor and basal cell ofCapsella were examined with the electron microscope and analyzed by histochemical procedures. The suspensor cells are more vacuolate and contain more ER and dictyosomes, but fewer ribosomes and stain less intensely for protein and nucleic acids than the cells of the embryo. The end walls of the suspensor cells contain numerous plasmodesmata but there are no plasmodesmata in the walls separating the suspensor from the embryo sac. The lower suspensor cells fuse with the embryo sac wall and the lateral walls of the lower and middle suspensor cells produce finger-like projections into the endosperm. At the heart stage the suspensor cells begin to degenerate and gradually lose their ability to stain for protein and nucleic acids.The basal cell is highly vacuolate and enlarges to a size of 150 X 70. An extensive network of wall projections develops on the micropylar end wall and adjacent lateral wall. The nucleus becomes deeply lobed and suspended in a strand of cytoplasm traversing the large vacuole. The cytoplasmic matrix darkens at the late globular stage and histochemical staining for protein becomes very intense. The basal cell remains active after the suspensor cytoplasm has degenerated. It is proposed that the suspensor and basal cell function as an embryonic root in the absorption and translocation of nutriments from the integuments to the developing embryo.Research supported by NSF grant GB 3460 and NIH grant 5-RO 1-CA-03656-09.     

Inactivation of Poliovirus Type 1 by the Kelly-Purdy Ultraviolet Seawater Treatment Unit

Three experiments were conducted to determine the effect of ultraviolet (UV) radiation on poliovirus-contaminated seawater. In two of the experiments, the effectiveness of the Kelly-Purdy UV Seawater Treatment Unit to inactivate poliovirus type 1 (T(1)) suspended in continuously flowing seawater was determined. In experiment 1, the observed survival ratio of poliovirus T(1) was 2.3 x 10(-4) (99.98% reduction) in 15.7 sec. No virus was detected (<0.2 plaque-forming unit/ml) in 20.6 seconds. The calculated half-life value was 1.29 sec. In experiment 2, the observed survival ratio of poliovirus T(1) was 5.9 x 10(-4) (99.94% reduction) in 11.7 sec. No virus was detected in 15.7 sec. The calculated half-life value was 1.37 sec. In experiment 3, a laboratory-controlled UV experiment designed to closely simulate the geometry of the continuously flowing seawater system, the observed survival ratios of poliovirus T(1) were 9.7 x 10(-3) (99.03% reduction) and 3.6 x 10(-4) (99.96% reduction) in 15 and 30 sec, respectively; the calculated half-life value was 2.38 sec. A statistically significant difference was found between the inactivation rates of poliovirus T(1) in the two test systems. This rate difference was attributed primarily to UV dosage and stirring effects. The data indicated that UV radiation effectively inactivated poliovirus T(1) in flowing seawater. These results validate the efficacy of the Kelly-Purdy UV Seawater Treatment Unit for use in commercial depuration systems.