Uninucleate spores of Phycomyces

Summary Under most culture conditions only 0.3% of the vegetative spores of Phycomyces blakesleeanus are uninucleate. On an acidified minimal medium, the uninucleate fraction can be raised up to 4.5% of the spores. The spore population can be fractionated in a gradient under gravity (1xg) yielding fractions that contain over 80% uninucleate spores. These uninucleate spores are fully viable. When the spores to be fractionated are obtained from a heterokaryotic mycelium, the uninucleate fraction produces homokaryotic mycelia.     

Fusarium andDidymella-neglected spores in the air

Summary This paper reports about the occurence ofFusarium- andDidymella spores in the air of Essen/FRG. During the spore season 1990, the spore concentration was measured on several days with a volumetric pollen trap by hourly analysis. The calculated amount of spores per hour is compared to the data of a pluviometer and the values of the relative humidity during the same period.The occurence of both spore types in the air and high relative humidity (>80%) are correlated in a highly significant way (P<0.001). The dispersion of spores starts when rain begins or directly after the precipitation.Didymella reaches higher concentrations thanFusarium in the air (Maximum values:Didymella 30000 spores/m³,Fusarium only 800 spores/m³). During the emission of the spores the temperature varied between 10°C und 20°C degrees. Didymella andFusarium must be an important allergenic source in the outdoor area, because of their allergen-loaded biological aerosols. The question of providing well defined extracts ofDidymella exitialis is given to the pharmaceutical industry.     

The source of the heat resistance of bacterial spores: Study of water in spores by NMR

It has been postulated that the heat stabilization of the essential macromolecules in the core of the spore may be produced by dehydration at two levels: (i) the spore is drier at high relative humidity than the vegetative cell and (ii) the core of the spore may be less hydrated than the cortex and the coat. The latter postulate was subjected to experimental testing by ¹H-NMR studies of the water signal in the five species of spores and coat and (coat + cortex) preparations. The transverse relaxation rate $\text{(}\text{1}\text{T}{}_2\text{)}$ was determined in samples equilibrated at constant relative humidity. To allow for the effect of paramagnetic ions on $\text{1}\text{T}{}_2$ a model system (wool keratin) was studied in the presence of known amounts of Ca(II), Mn(II), Cu(II), Ni(II) and Fe(III). Because of the dominant effect of Mn(II) on $\text{1}\text{T}{}_2$, the effect of small amounts of other metal ions in spores was neglected. The relaxation rate of water at a particular relative humidity and manganese concentration was consistently less for intact spores than for coat or coat + cortex, hence the water in the core is more mobile than in the outer integuments. Sorption isotherm studies have shown that at a particular relative humidity there is about as much water in the core as in the cortex and coat. These two results taken together indicate that the hypothesis that the core is drier than the cortex and coat is incorrect, hence the spore is not heat-stabilized in this way. A theory is proposed in which heat stabilization is attributed to immobilization of essential enzymes and nuclei acids by a solid support, calcium dipicolinate, in a similar fashion to the heat stabilization of enzymes in a charged polymer matrix. It is proposed that stabilization is effected by electrostatic and hydrogen bonds between the calcium dipicolinate and the essential macromolecules. Experiments in progress show that enzymes and DNA are heat-stabilized in vitro by calcium dipicolinate.     

Glycoconjugates for the recognition of Bacillus spores

Carbohydrates act as ligands in many biological processes, including the folding and secretion of proteins, cell-cell recognition, adhesion, and sporulation in the Bacillus genus. Fluorescent-labeled disaccharide glycoconjugates have been applied to evaluate binding to bacterial spores assuming that the spore surface is covered with carbohydrates. This study has shown that specific recognition of bacterial spores is based on interactions between disaccharide glycoconjugates acting as ligands and monosaccharide units expressed on the exterior of bacterial spores. Using fluorophore-assisted carbohydrate electrophoresis (FACE), carbohydrates that are expressed on the exterior of the spores were enumerated. The findings have an impact on how to improve ligand selection, essential for sensor development. In addition, the findings provide new information for inhibition of bacterial spores, and in general, demonstrate how carbohydrates function as recognition signals in nature.     

Germination of the decoated spores of Bacillus megaterium

Decoated spores of Bacillus megaterium ATCC 12872 were prepared by extracting the inner coat components with an alkaline solution containing sodium dodecyl sulfate and dithiothreitol (SDS-DTT) from outer coat-deficient mutant spores, which were produced from one of the mutants isolated and named MAE-05 by us. The decoated mutant spores germinated as well as the intact spores of the mutant and the parent, indicating that the outer and inner spore cats cannot be essential structures for the initiation of germination. When the SDS-DTT-treated MAE-05 spores were converted to H-spores by incubation in citrate-phosphate buffer (pH 3.5) at 30 C for 3 hr, they lost their germinability by glucose and KNO3. Ca-spores, prepared by treating H-spores with 10 mM calcium acetate at 37 C for 60 min, regained the germinability. Experiments on the interaction of 45Ca with the cortex and the inner membrane isolated from H-spores suggested that the calcium present in the inner membrane might be related to germinability.     

Molecular biology of the germination of Bacillus spores

The review deals with recent results and problems of gene expression during germination of Bacillus spores. Three problems were selected: 1. The activation of metabolism as a prerequisite for the synthesis of nucleic acids and proteins. 2. The activation of nucleic acid and protein synthesis during germination. 3. The gene expression programme of germinating spores. Using the highly sensitive two-dimensional polyacrylamide gel analysis three major classes of proteins were distinguished, depending on the time of onset and duration of their syntheses: a) proteins made throughout germination (main class), b) proteins whose synthesis started only after a lag phase and then continued throughout germination, and c) proteins which are synthesized only during the early phases of germination. The programme of protein synthesis is an indicator for the control of gene expression during germination. The regulation of expression of these major gene groups during spore outgrowth is discussed.     

Role of trehalose in the spores of Streptomyces

Abstract Dormant spores of Streptomyces antibioticus contain large amounts of trehalose (11–12% of dry weight) and can be subjected to a dehydration treatment without a significant loss of viability. Loss of dehydration resistance coincided with a decrease in the trehalose level of the spores, under different conditions of incubation. The viability of dehydration-sensitive cells was enhanced by the presence of exogenous trehalose during dehydration. The morphology and functional activity of isolated membranes of S. antibioticus can be retained when dehydrated in the presence of trehalose. It is suggested that, in dormant spores of S. antibioticus , trehalose may serve to protect cellular components during dehydration by acting as a substitute for water.