Showing papers by "University of Groningen published in 1972"
TL;DR: An eightfold auxotrophic strain of Bacillus subtilis was constructed and its transformability was strongly reduced as compared with both the UV-resistant parental strain and the other, moderately UV-sensitive, strain.
Abstract: An eightfold auxotrophic strain of Bacillus subtilis was constructed. It was about equally well transformable for all markers. When this strain was used as recipient in transformation, single marker transformation frequencies of 0.5–2.0% were obtained. The markers were located relatively to each other using marker frequency analysis. Two UV-sensitive derivatives, equally well transformable as the parental multiple auxotroph, were isolated. One was highly sensitive to UV irradiation, was host cell reactivation-negative and did not show DNA breakdown or recovery of DNA synthesis after exposure to UV. Using UV-inactivated transforming DNA, this strain's transformability was strongly reduced as compared with both the UV-resistant parental strain and the other, moderately UV-sensitive, strain.
198 citations
TL;DR: In this paper, the electronic absorption and emission spectra of TCNQ and its mono-and divalent anions were measured and an SCMO CI calculation in the PPP approximation was performed with one set of parameters for the three species yielding good agreement with experiment.
127 citations
TL;DR: Two glucans were isolated from the hyphal wall of Schizophyllum commune and analyzed by complete and partial acid hydrolysis, enzymatic hydroleysis, periodate oxidation, optical rotation, X-ray diffraction and electron microscopy, finding both the S-glucan in the wall and chemically isolated S- glucan have a typical rodlet structure.
114 citations
TL;DR: In this paper, the elemental composition of a surface can be derived from the energy spectrum of singly reflected noble gas ions, and it is shown that it is also possible to obtain information about certain structural features on the surface from energy spectra of multiply reflected ions.
109 citations
TL;DR: It is concluded that binaural additivity of loudness holds for non-zero stimulation of the ears, derived from extensive measurement such as magnitude estimation.
Abstract: A definition of binaural additivity is given in terms of the theory of simultaneous conjoint measurement. Additivity is then tested and verified by a conjoint measurement procedure. Methods for deriving psychophysical scales from such procedures are discussed, and the experimental scales are compared with the usual ratio scales for loudness, derived from extensive measurement such as magnitude estimation. The functions are in good agreement and it is concluded that binaural additivity of loudness holds for non-zero stimulation of the ears.
104 citations
TL;DR: The data show that at least some purple nonsulfur bacteria may play a role in the dissimilatory sulfur cycle in nature, and sulfide was converted into extracellular elemental sulfur at all dilution rates tested.
Abstract: The purple nonsulfur bacteria Rhodospirillum rubrum SMG 107, Rhodopseudomonas capsulata SMG 155, Rps. sphaeroides SMG 158 and Rps. palustris SMG 124 were tested for a possible utilization of sulfide. The first three strains were found to oxidize sulfide to extracellular elemental sulfur only, whereas Rps. palustris SMG 124 converted sulfide into sulfate without intermediate accumulation of elemental sulfur. Growth ceased at lower sulfide concentrations than usually found with purple sulfur bacteria. In consequence of the low sulfide tolerance information on the specific growth rates obtainable with sulfide as photosynthetic electron donor could not be provided by cultivation in batch cultures. Sulfide-limited chemostat cultures of Rps. capsulata SMG 155 showed that the maximum specific growth rate was close to 0.14 h-1 (doubling time 5 h). Sulfide was converted into extracellular elemental sulfur at all dilution rates tested. The maximum specific growth rate of Rps. palustris SMG 124 was found to be much lower (less than 0.03 h-1). Sulfate was the only product of the conversion of sulfide.
104 citations
TL;DR: An enrichment procedure for the isolation of stalked bacteria of the genus Hyphomicrobium is described, based on the use of an organic C1 compound as carbon and energy source for growth together with anaerobic incubation in the presence of nitrate as an electron acceptor.
Abstract: An enrichment procedure for the isolation of stalked bacteria of the genusHyphomicrobium is described. The method is based on the use of an organic C1 compound as carbon and energy source for growth together with anaerobic incubation in the presence of nitrate as an electron acceptor. Optimal conditions for the growth of a number ofHyphomicrobium isolates have been investigated. Applying these conditions,Hyphomicrobium spp. have been enriched from a wide range of natural habitats within 1–2 weeks.
102 citations
TL;DR: Tms.
Abstract: From marine mud flats a very thin, comma- or spiral-shaped bacterium was isolated. The new organism was an obligately chemolithotrophic sulfur bacterium. Its physiology was found to be essentially similar to that ofThiobacillus thioparus. Because of the spirillum-like appearance it was proposed to classify this bacterium into a new genusThiomicrospira, with the species nameTms. pelophila. Tms. pelophila and a marineT. thioparus, which was isolated from the same mud, occupy different niches in this habitat.Tms. pelophila has a remarkable sulfide-tolerance as compared withT. thioparus. This property could be used for the specific enrichment ofTms. pelophila. The organism was also readily isolated in pure culture by filtering mud suspensions through a 0.22 Μm membrane filter.
84 citations
TL;DR: There are strong indications that this threshold principle does not hold for spermatogenesis and egg growth up to the first step of vitellogenesis, but only for interstitial cell development and further egg growth with completion of vITEllogenesis.
77 citations
01 Oct 1972
TL;DR: It is suggested that carotene plays no primary role in the protection against photo-oxidation during chilling, and xanthophyll has the shortest lag phase and is most sensitive to photo- Coxidative process.
Abstract: SUMMARY
The effect of light on Cucumis leaf pigments at 1 °C has been studied. Pigment degradation is a photo-oxidative process. Kinetics of pigment degradation show a slow degradation rate (lag phase) followed by a fast one. The sensitivity to photo-oxidation corresponds to the length of the lag phase. Carotene has the shortest lag phase and is most sensitive to photo-oxidation, followed by xanthophyll, chlorophyll a, and chlorophyll b.
The lag phase decreases at 100% oxygen and disappears after boiling. Some possible factors causing the biphasic nature of chlorophyll degradation are discussed. It is suggested that carotene plays no primary role in the protection against photo-oxidation during chilling.
70 citations
TL;DR: It is suggested that drought as well as predation by shrews, toads and frogs are the major factors affecting juvenile survival, and that survival of small juveniles is the key factor in the dynamics of populations of Cepaea.
Abstract: Oviposition in Cepaea nemoralis occurs mainly from the end of May until the beginning of August, but there is a second peak, probably small, in egg production in October. Most of the eggs produced in late autumn die, but some survive during the winter and produce juveniles. During the summer the number of clutches produced per snail was 2.4 and mean clutch size was 72 eggs. It is suggested that some substance, possibly digestible protein and carbohydrates in the food is limiting clutch size, that the seasonal decrease in clutch size is caused by a decreasing concentration of that substance in the food and that larger snails produce larger clutches because they eat more. A comparison is made between a population which was rapidly increasing in size and one that declined. In the former egg production per snail was more than twice that in the latter and egg survival 25% better so that production of juveniles was 3 times larger. In the former some 25% of the snails that became adult did so in their first year while in the latter nu such fast growers have been observed. However, survival of juveniles in their first year in the expanding population was 20 times better. This suggests that survival of small juveniles is the key factor in the dynamics of populations of Cepaea. It is suggested that drought as well as predation by shrews, toads and frogs are the major factors affecting juvenile survival. It is argued that there may be some density governing processes acting but that their influence in population size is almost negligible.
TL;DR: The anatomy of the upper and lower jaws of the carp, together with the associated maxillaris and mandibularis muscles of the adductor mandibulae complex, is described and the muscle coordination of the diverse mouth movements during feeding has been studied.
Abstract: 1. The anatomy of the upper and lower jaws of the carp, together with the associated maxillaris and mandibularis muscles of the adductor mandibulae complex, is described. 2. From the electromyograms of the adductor mandibulae muscles, recorded simultaneously with a 16 mm film of the mouth movements in a free-swimming carp, the muscle coordination of the diverse mouth movements during feeding has been studied. 3. The interpretation of the results has been verified by electrical stimulation of the muscles, in different combinations, in a fish in which spontaneous movements were abolished by heavy anaesthesia.
TL;DR: In this article, restricted Hartree-Fock molecular-orbital calculations have been carried out for various states of the cluster Ni${\mathrm{F6}^{4\ensuremath{-}}$ "in vacuo" and in a surrounding of several sets of point charges representing the perovskite lattice KNi${F}}_{3} ).
Abstract: Restricted Hartree-Fock molecular-orbital calculations have been carried out for various states of the cluster Ni${\mathrm{F}}_{6}^{4\ensuremath{-}}$ "in vacuo" and in a surrounding of several sets of point charges representing the perovskite lattice KNi${\mathrm{F}}_{3}$. All electrons were included. A "double-$\ensuremath{\zeta}$" basis set of contracted Gaussian orbitals has been used. The calculations were performed with the computer program IBMOL IV. The Hartree-Fock approximation gives a reasonable description of the covalency effects and the spectral properties of KNi${\mathrm{F}}_{3}$. The calculated hyperfinefield parameters ${f}_{s}$ and ${f}_{\ensuremath{\sigma}}$ and the $10Dq$ value are about 10-25% smaller than the experimental values. Similar deviations were found for the spectral transition energies. It is argued that magnitude and sign of the crystal field splitting in this compound can be understood in terms of the well-known ionic electrostatic model provided the Born repulsion is properly taken into account.
TL;DR: In this article, the melting behavior of isotactic polystyrene, crystallized from the melt and from dilute solutions in trans-decalin, has been studied by differential scanning calorimetry and solubility measurements.
Abstract: The melting behavior of isotactic polystyrene, crystallized from the melt and from dilute solutions in trans-decalin, has been studied by differential scanning calorimetry and solubility measurements. The melting curves show 1, 2, or 3 melting endotherms. At large supercooling, crystallization from the melt produces a small melting endotherm just above the crystallization temperature Tc. This peak originates from secondary crystallization of melt trapped within the spherulites. The next melting endotherm is related to the normal primary crystallization process. Its peak temperature increases linearly with Tc, yielding an extrapolated value for the equilibrium melting temperature Tc° of 242 ± 1°C as found before. By self-seeding, crystallization from the melt could be performed at much higher temperature to obtain melting temperatures as high as 243°C, giving rise to doubt about the value of Tc° found by extrapolation. For normal values of Tc and heating rate, an extra endotherm appears on the melting curve. Its peak temperature is the same for both melt-crystallized and solution-crystallized samples, and independent of Tc, but rises with decreasing heating rate. From the effects of heating rate and partial scanning on the ratio of peak areas and of previous heat treatment on dissolution temperature, it is concluded that this peak arises from the second one by continuous melting and recrystallization during the scan.
TL;DR: In this article, it was shown that at low enough temperature all translationally invariant equilibrium states for the Ising ferromagnet are a superposition of only two extremal states, i.e., the positively and negatively magnetized pure phases.
Abstract: We prove that at low enough temperature all translationally invariant equilibrium states for the Ising ferromagnet are a superposition of only two extremal states, i.e., the positively and negatively magnetized pure phases. In particular this proves, at low temperature and in two dimensions, the identity of the spontaneous magnetization and the Onsager's value ${M}_{0}={[1\ensuremath{-}{(sh\ensuremath{\beta})}^{\ensuremath{-}4}]}^{\frac{1}{8}}$.
TL;DR: The main effects of vitamin E deficiency on cellular membranes reflect in the lipid moiety more than in the protein part, which is of paramount importance for the maintenance of cellular compartmentalization and cell metabolism.
Abstract: Publisher Summary This chapter discusses the effect of vitamin E deficiency on cellular membranes The main effects of vitamin E deficiency on cellular membranes reflect in the lipid moiety more than in the protein part It can be stated that these effects differ for various cellular membranes This diversity in reaction pattern might, at higher levels of structural organization, be correlated with the characteristic course of vitamin E deficiency: a gradual, but unmistakable worsening in the general condition is followed by a relatively sudden death of the animal concerned The first period of the illness is determined by an altered membrane function based on the proven changes in membrane composition This problem of permeability is of paramount importance for the maintenance of cellular compartmentalization and cell metabolism The second phase of the illness, a phase in which the animals die suddenly, may coincide with a deterioration of lysosomal membranes The vitamin E deficiency affects species differently, and within one species marked tissue specificity in susceptibility to vitamin E deficiency can be observed
TL;DR: The effect of NO and NO~ on hemocyanin of H. pomatia is reported and in the case of NO-treated hemOCyanin the authors find dipolar coupling between 2 Cu 2+ ions in the active site.
TL;DR: A tulip extract gave a positive reaction in this patient, but extracts of onion did not do so and the allergenic material was found to be of low molecular weight, heat labile and present in the outer parts of the bulb.
Abstract: Summary.— A case of contact dermatitis to garlic is described. Patch tests with a piece of garlic bulb and extracts of garlic were positive. A tulip extract gave a positive reaction in this patient, but extracts of onion did not do so. The active substance proved to be readily soluble in water, alcohol and acetone. The allergenic material was found to be of low molecular weight, heat labile and present in the outer parts of the bulb.
TL;DR: Isolated mitochondria from two wild-type strains of Neurospora crassa were disrupted by osmotic shock in order to release mitochondrial DNA, in the electron microscope this DNA appeared to consist for a large part of circular molecules, characteristic for closed circular duplex DNA.
TL;DR: Intravenous injection or infusion of prostaglandin E 1 effectively suppressed bigeminy occurring in the course of thialbarbitone anaesthesia in dogs, and ventricular tachycardia due to acute myocardial ischaemia was reversed.
TL;DR: It is proposed that most of the isolated RD1A mtDNA is present in large fishnets concatenanes; the unwinding restriction imposed on DNA of which the strands are plaited into a fishnet concatenate explains the restricted ethidium uptake.
TL;DR: The ustilaginaceous fungi, traditionally synonymous with the smuts, now include recent taxa derived from the yeasts, and it is proposed to accommodate them in a new taxon of equal rank, the Division Ustomycota.
Abstract: The ustilaginaceous fungi, traditionally synonymous with the smuts, now include recent taxa derived from the yeasts. Although generally placed next to the rusts, these fungi only superficially resemble the Uredinales-the resistant cell, here termed a ustospore, is not a teliospore and its one or more germ hyphae bear somatic sporidia, not meiotically derived basidiospores. Examination of the ultrastructure of a number of species shows the septa to be basidiomycetously layered but with pores lacking a dolipore/parenthesome complex. Further, inLeucosporidium andRhodosporidium, in which the clamps also have simple pores, the electron microscopic observations admit the interpretation that the ustospore is an encysted proascus. Because the characteristics of these fungi do not allow them to be satisfactorily included among either the Ascomycota or the Basidiomycota, it is proposed to accommodate them in a new taxon of equal rank, the Division Ustomycota.
TL;DR: The NMR spectra of 7 Li and 23 Na in oriented DNA fibers show a splitting into three lines, due to quadrupolar interactions, which are relevant for an alternative interpretation of sodium NMR signals in biological tissues.
TL;DR: In this article, the rotational correlation times and activation energies for the anisotropic motion of the spin label molecules were determined at different degrees of hydration, and strong evidence was obtained that the cholesterol and alkyl chains of lecithin are well oriented and are in rapid anisoustropic motion.
TL;DR: An area about one degree square centred at α = 22 h 33.80 m, δ = 33° 41.0′ (1950) near Stephan's Quintet of galaxies has been observed with the Westerbork Synthesis Radio Telescope, and an unusual, approximately semicircular arc of emission which appears to partially envelope this galaxy.
Abstract: AN area about one degree square centred at α = 22 h 33.80 m, δ = 33° 41.0′ (1950) near Stephan's Quintet of galaxies has been observed with the Westerbork Synthesis Radio Telescope at 21.2 cm. The measurements consist of 12 h registrations at 40 interferometer spacings from 36 to 1,440 m in intervals of 36 m. The observations were Fourier-transformed to produce a map of the radio brightness of the region with a synthesized beam 25 arc s wide at the half-power points. The results in the immediate neighbourhood of Stephan's Quintet are shown in Fig. 1. The radio contours are drawn over a photograph of the Quintet which has been taken from ref. 1. The radio features detected consist of an unresolved source (indicated by the white cross on the photograph) located very near the nucleus of the spiral galaxy NGC 7319, and an unusual, approximately semicircular arc of emission which appears to partially envelope this galaxy. Any radio emission from the nucleus of NGC 7320 is less than 2.5×10−29 W m−2 Hz−1; a similar limit also applies to NGC 7317.
TL;DR: It is suggested that one type activates water elimination, while the other type stimulates ion-uptake mechanisms in osmoregulation, similar to that found around water and ion transporting epithelia in insects.
TL;DR: It appeared that undisturbed organization of the blood clot, regardless of its volume, fully depended on an optimal primary closure, which generally fails to organize, resulting in suppuration.
TL;DR: In this paper, it was shown that in the inelastic region one may have infinitely many different scattering amplitudes with a given differential cross-section, which is potentially important in phase shift analysis, since it means that there is a continuous ambiguity in the determination of phases and elasticities from scattering data.
Abstract: When the differential cross-section for spin-zero elastic scattering is given, the elastic unitarity condition constitutes a nonlinear integral equation for the phase of the scattering amplitude. Existence and uniquences theorems for solutions of the equation were obtained by Newton and Martin. Some improvements of the Newton-Martin results on uniqueness and iterative construction of solutions are obtained. Certain details of rigour in the applications of Schauder's theorem by Newton and by Martin are supplied. The case of inelastic spin-zero scattering is treated by adding a term to the unitarity condition to account for absorption. It is shown that in the inelastic region one may have infinitely many different scattering amplitudes with a given differential cross-section. This result is potentially important in phase-shift analysis, since it means that there is a “continuum ambiguity” in the determination of phases and elasticities from scattering data.