Evidence for interactions between the energy-dependent transport of sugars and the membrane potential in the yeastRhodotorula gracilis (Rhodosporidium toruloides)

Summary A membrane potential (inside negative) across the plasma membrane of the obligatory aerobic yeastRhodotorula gracilis is indicated by the intracellular accumulation of the lipid-soluble cations tetraphenylphosphonium and triphenylmethylphosphonium. The uptake of these ions is inhibited by anaerobic conditions, by uncouplers, by addition of diffusible ions, or by increase of the leakiness of the membrane caused by the polyene antibiotic nystatin. The membrane potential is strongly pH-dependent, its value increasing with decreasing extracellular proton concentration. Addition of transportable monosaccharides causes a depolarization of the electrical potential difference, indicating that the H⁺-sugar cotransport is electrogenic. The effect on the membrane potential is enhanced by increasing the sugar concentration. The half-saturation constants of depolarization ford-xylose andd-galactose were comparable to those of the corresponding transport system for the two sugars. All agents that depressed the membrane potential inhibited monosaccharide transport; hence the membrane potential provides energy for active sugar transport in this strain of yeast.     

Identification of the oligonucleotide and oligopeptide involved in an RNA--protein crosslink induced by ultraviolet irradiation of Escherichia coli 30 S ribosomal subunits.

When 30 S ribosomal subunits are irradiated with ultraviolet light, we have found that an RNA-protein crosslinking reaction occurs whose primary target is protein S7. This paper describes the identification of the oligopeptide and oligonucleotide at the crosslinking point, by direct analysis (a) of the peptide remaining attached to an oligonucleotide (after total digestion of the RNA in the crosslinked complex with ribonucleases A and T₁, followed by digestion with trypsin), and (b) of the nucleotides remaining attached to the crosslinked protein (after digestion of the RNA in the complex with ribonuclease T₁ alone).The crosslinking site was found to lie within a single short peptide, Ser-Met-Ala-Leu-Arg (positions 113 to 117 in the S7 sequence), with methionine as the probable amino acid concerned. The principal RNA site was found to lie within an oligonucleotide three to six bases long, the underlined portion of the partially ordered sequence $\text{C-U-A-C-}\text{A-A-U-G.G.C}\text{-G}$ in section P of the 16 S RNA. The methodology involved has been designed with a view to being generally applicable in future RNA-protein crosslinking studies, where several proteins are simultaneously attached to the RNA.     

Binding of opiates and endogenous opioid peptides to neuroleptic receptor sites in the corpus striatum.

Some opiates with morphinan- and benzomorphan-structures possess affinities for neuroleptic receptors as revealed by their abilities to compete with ³H-spiroperidol for common binding sites in rat striatum $\text{in vitro}$ (IC₅₀ in the range between 10^?6 and 10^?5M). The binding of these opiates to neuroleptic receptors appears to be of pharmacological significance, since $\text{in vivo}$ studies in mice revealed a small but significant displacement of spiroperidol by high doses of the opiate antagonist levallorphan from specific binding sites in the striatum. In addition, there exists some correlation between the ability of opiates to bind to neuroleptic receptor sites $\text{in vitro}$ and their potency to evoke “bizarre behavior” in rats $\text{in vivo}$. In contrast, a wide variety of other opiates having morphine-, morphinone- or oripavine-structure showed no affinity for neuroleptic binding sites $\text{in vitro}$ (IC₅₀ greater than 10^?4 M). Of the opioid peptides (methionine-enkephalin, leucine-enkephalin and β-endorphin) none has an affinity for neuroleptic binding sites. A variety of other peptides were also investigated but did not interfere with spiroperidol binding. Only ACTH showed a moderate affinity for neuroleptic binding sites.     

Lack of effect on the chromosomal non-disjunction in aged female mice after low dose X-irradiation.

Karyotypes were determined in 1064 embryos of aged C57/BL mothers. The virgin female mice were irradiated with 0, 4, 8 or 16 R of X-rays, respectively, and placed with young untreated males 5 days after irradiation. 10.5-days old embryos were recovered from the uterus. Aneuploid embryos classified as alive (heart beats observed at the dissection) were 1 monosomic in the control group (496 embryos) and 2 trisomics in the irradiated group (568 embryos). The number of aneuploid embryos classified as dead was 4 trisomic cases in the control group and 3 trisomics in the irradiated group. The data indicate that trisomic embryos are not uncommon in the mouse but are eliminated in post-implantation death. In contrast to the results of Yamamoto et al. the present data do not demonstrate an increased frequency of chromosome abnormalities in embryos of aged mice X-irradiated before mating as compared to non-irradiated ones.     

Ammoniteli der GattungParapatoceras aus dem Oberen Mitteljura des Süntels (östliches Wesergebirge,Niedersachsen)

The Parapatocerates from the Süntel (Weser mountains, Northwest Germany) are described being an utmost variable subspecies respectively geographical raceParapatoceras distans (?) bentzi (Potonié) with two possibly modificatorily separated form groups. They differ from the similarP. distans(?) crioconus (Buckman) (=Crioconites Buckman) of Chippenham (England) in primary quadrilobaty and further characteristics accessible only by precise analysis. To establish the speciesdistans Baugier & Sauzé and with this the genusParapatoceras, recovery of the holotype or a determination of a neotype is required. A very similar but probably quinquelobate specimen (Parapatoceras sp.) from the Macrocephalus oolite of Hanover seems to accentuate once more the taxonomically minor degree of the quadri- or quinquelobaty inParapatoceras.     

Light-induced fluorescence decay during the greening of normal and lincomycin-treated maize leaves

Light-induced fluorescence decay was examined during the greening of control and lincomycintreated maize (Zea mays L.) leaves. Assuming that this decay to a first approximation is the result of two parallel first-order reactions, the fluorescence induction curves were linearized on the logarithm plot and the parameters were determined. The variable fluorescence increased, and the parameters of the two linear sections of the fluorescence decay—that is, the kinetics of the induction curves—changed during the greening of the control leaves. Lincomycin treatment caused some chlorophyll deficiency and the lowering of the chlorophyll a/b ratio, changed the fluorescence emission spectra and the effect of Mg²⁺ on the regulation of the excitation energy distribution. The structure of the thylakoids and the kinetics of the fluorescence decay were also changed in the treated leaves. The possible relationship between the change of the kinetics of the fluorescence decay and the change of spillover during greening and after lincomycin treatment is discussed.Abbreviations LHC light-harvesting complex - Chl chlorophyll - LM lincomycin - PS photosystem - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea     

Cell wall regeneration by protoplasts of Chlamydomonas

Protoplasts from Chlamydomonas smithii prepared by the action of C. reinhardii gamete autolysine have been studied with respect to cell wall regeneration. Natural protoplasts within sporangia were also investigated for purposes of comparison. In both cases a new cell wall is completed within 2–3 h of the onset of regeneration. The first visible stages of wall regeneration are to be seen after 40–60 min as a fine fringe outside of the plasmalemma. The development of the typical central triplet follows within the next 1 h. Cell wall regeneration is reversibly inhibited by cycloheximide (10g ml^-1) and reversibly disturbed by concanavalin A (50 g ml^-1). Actinomycin D at concentration over 100g ml^-1 also inhibit but the inhibition is irreversible and peculiar membrane effects are observed. Chelators (ethylenediamine tetraacetic acid; ethyleneglycol-bis-aminoethyl ether) and 2-deoxyglucose slightly retard or have no effect on cell wall regeneration.Abbreviations EDTA ethylenediamine tetraacetic acid - EGTA ethyleneglycol-bis(aminoethyl ether) - N,N tetraacetic acid     

Dynamics of the ectoplasmic walls during pulsation of plasmodial veins ofPhysarum polycephalum

Summary The thickness of ectoplasmic walls decreases at the contraction phase and increases at the expansion phase of each pulsation cycle. In average, 29% of material forming the walls of expanded veins is evacuated during contraction with the endoplasm streaming.     

Differential response to irradiation in offspring of freshwater and seawater substrains of Poecilia (Lebistes) reticulata peters in the “guppy male courtship activity test”

Summary An inbred strain (Istanbul) of guppies was divided into two substrains, one of which was maintained and bred in seawater. The offspring of irradiated animals of both substrains (1000 R X-rays to spermatogonia and oogonia of neonatal fish) were tested in a new gruppy male courtship activity test and compared with control groups. The postirradiation response in the seawater substrain was more intense than in the freshwater substrain.Dedicated to Prof.Dr.Dr.h.c.mult. Curt Kosswig on the occasion of his 75th birthday