Furfural uptake by Neurospora ascospores

Summary Furfural uptake was studied with regard to possible mechanisms of inducing germination in ascospores. Uptake was found to involve a large, weakly bound reversible component and a small tightly bound irreversible component. Localization experiments indicate that almost all of the furfural removed from the media is bound to the spore wall. However, a small amount may penetrate into the cytoplasm. The results so far suggest that furfural induces germination by solubilizing or activating a bound or compartmentalized enzyme(s) on the cell membrane or other diffusion barrier of the cell.This paper is part of a dissertation submitted to the Rackham Graduate School of the University of Michigan in partial fulfillment of the requirement for the Doctor of Philosophy degree in Botany by Frederick I. Eilers.     

Concentration of Rift Valley Fever and Chikungunya Viruses by Precipitation

Simple and efficient methods for concentrating Rift Valley fever (RVF) virus and chikungunya (CHIK) virus are described. Ammonium sulfate, potassium sulfate, or alcohol was used as a precipitating agent and the precipitate was resuspended to volumes suitable for further processing and purification. The methods permitted concentration of live RVF virus and CHIK virus about 100-fold with negligible losses of virus. RVF virus retained a high level of infectivity with potassium aluminum sulfate and alcohol, but CHIK virus retained a higher infectivity level with ammonium sulfate than with potassium aluminum sulfate. The data indicate that serum plays an important role in the concentration of both viruses, at least when the sulfate methods are used.     

A quantitative description of the dynamics of excitation and inhibition in the eye of Limulus

By means of intracellular microelectrode techniques, we have measured the dynamics of the several processes which translate light stimulation into spike activity in the Limulus eye. The transductions from light to voltage and from voltage to spike rate, and the lateral inhibitory transduction from spike rate to voltage, we have characterized by transfer functions. We have checked the appropriateness of treating the eye as a system of linear transducers under our experimental conditions. The response of the eye to a large spot of light undergoing sine flicker has been correctly predicted.     

Phenolic metabolites of Ceratocystis ulmi

The C₁₀ acid 2,4-dihydroxy-6-(1-hydroxyacetonyl) benzoic acid, together with the 6-acetonyl- and 6-pyruvyl-analogues, has been identified as a metabolic product of Ceratocystis ulmi, the causative agent of Dutch elm disease. In a comparison of aggressive “fluffy” and non-aggressive “waxy” strains of C. ulmi, the C₁₀ acids were produced more rapidly and in greater yield by the former group.     

Enzymes related to lactate metabolism in green algae and lower land plants

Cell-free extracts of Chlorella pyrenoidosa contained two enzymes capable of oxidizing d-lactate; these were glycolate dehydrogenase and NAD(+)-dependent d-lactate dehydrogenase. The two enzymes could be distinguished by differential centrifugation, glycolate dehydrogenase being largely particulate and NAD(+)-d-lactate dehydrogenase being soluble. The reduction of pyruvate by NADH proceeded more rapidly than the reverse reaction, and the apparent Michaelis constants for pyruvate and NADH were lower than for d-lactate and NAD(+). These data indicated that under physiological conditions, the NAD(+)-linked d-lactate dehydrogenase probably functions to produce d-lactate from pyruvate.Lactate dehydrogenase activity dependent on NAD(+) was found in a number of other green algae and in the green tissues of a few lower land plants. When present in species which contain glycolate oxidase rather than glycolate dehydrogenase, the enzyme was specific for l-lactate rather than d-lactate. A cyclic system revolving around the production and utilization of d-lactate in some species and l-lactate in certain others is proposed.     

Independence of brachymesophalangia-5 from brachymesophalangia-5 with cone mid-5

Analysis of hand radiographs of juvenile siblings of juvenile propositi indicates that brachymesophalangia-5 alone (without cones) is separately inherited without apparent sex bias while brachymesophalangia-5 with the cone-epiphysis of mid-5 and the cone-epiphysis of mid-5 alone are both apparently inherited as a complex and with a marked excess of females over males.     

Ribosome Patterns in Escherichia coli Growing at Various Rates

The distribution of ribosomes, 30 and 50S subunits and polysomes, at three different growth rates of Escherichia coli strains B and K-12 has been studied. The usual percentage of subunits is about 20%. However, at the lowest growth rate (mu = generations/hour), mu = 0.45 at 30C, the proportion of subunits is about 30%. An exceptional situation exists in K-12 strains growing at maximum growth rate, mu = 1.35, where the percentage of subunits is 45%. Several points of control over ribosome production are thus indicated. It is suggested that "subunit pool" is essentially a reserve. Furthermore, the polysome content when related to deoxyribonucleic acid content varies directly with the growth rate, which indicates the average efficiency of polysomes in protein synthesis does not vary over the range of growth rates tested.