Re-expression by Candida albicans germ tubes of antigens lost during subculture of blastospores

The effect of germ tube induction on the antigenic variability in C. albicans was studied in strains from blood cultures (Group I) and superficial candidiasis (Group II). When compared by immunoblotting with a rabbit antiserum, antigenic extracts from Group I strains grown as blastospores showed a higher reactivity than that of Group II strains. Major bands in Group I strains (45–47, 33, 30 kDa) were continuously expressed through the subcultures in vitro but, with the exception of the 45 kDa band, the reactivity of all of them decreased or disappeared after the tenth subculture in Group II strains. The induction of the germ tubes produced the re-expression of the antigens lost during subculture in the yeast form, the effect being very clear in Group II strains. The re-expression by C. albicans germ tubes of antigens lost during subculture of blastospores in vitro and the higher reactivity shown by Group I strains grown in mycelial phase should be taken into consideration when a test to detect anti-C. albicans antibodies is to be developed.Abbreviations GYE glucose-yeast extract agar     

Wheat ear carbon assimilation and nitrogen remobilization contribute significantly to grain yield

The role of wheat ears as a source of nitrogen (N) and carbon (C) in the grain filling process has barely been studied. To resolve this question, five wheat genotypes were labeled with ¹⁵N‐enriched nutrient solution. N remobilization and absorption were estimated via the nitrogen isotope composition of total organic matter and Rubisco. Gas exchange analyses showed that ear photosynthesis contributed substantially to grain filling in spite of the great loss of C due to respiration. Of the total kernel N, 64.7% was derived from the N acquired between sowing and anthesis, while the remaining 35.3% was derived from the N acquired between anthesis and maturity. In addition, 1.87 times more N was remobilized to the developing kernel from the ear than from the flag leaf. The higher yielding genotypes showed an increased N remobilization to the kernel compared to the lower yielding genotypes. In addition, the higher yielding genotypes remobilized more N from the ears to the kernel than the lower yielding genotypes, while the lower yielding genotypes remobilized more N from the flag leaf to the kernel. Therefore, the ears contribute significantly toward fulfilling C and N demands during grain filling.     

Homopolygalacturonan Molecular Size in Plant Cell Wall Matrices Via Paramagnetic Ion and Nitroxyl Amide Dipolar Spin-Spin Interactions

Mn²⁺, Cu²⁺, and nitroxyl amines have been shown to bond to plant homopolygalacturonan matrices in a spatially sequential fashion. As a consequence of this special form of cooperativity the lattice constant (κ), determined from Van Vleck's second moment relationship, approaches 1 only when the average number of dipolar interactions per spin approaches 1 (e.g., an array of dimers). Assuming that one paramagnetic ion or nitroxyl amide pair is bonded per polymer block within the matrix when κ = 1, the anionic ligand's average degree of polymerization ([unk]) can be estimated from the concentration of bonded paramagnetic dimers (e.g., [1/χ]_κ~1 = [unk]; χ is the mole fraction of bonded paramagnetic dimers). We have utilized this technique to estimate the average molecular size of homopolygalacturonan blocks in intact higher plant cortical cell walls ([unk] ~83), Nitella cell walls ([unk] ~27) and a commercially available galacturonic acid polymer ([unk] ~35). The [unk] determined from both the intact cortical cell wall lattice and the polygalacturonan were similar to literature values; these findings argue that the electron paramagnetic resonance, (EPR) dipolar spin-spin interaction technique reported herein is a valid approach for estimating molecular size in plant cell walls.     

Development of Candida albicans hyphae in different growth media--variations in growth rates, cell dimensions and timing of morphogenetic events

In six liquid culture media, all of which stimulated Candida albicans to grow in the hyphal form, the rates of hyphal extension and increase in cellular ATP concentration, hyphal diameters, times of evagination of hyphae, times of septum formation and positions of septa in the hyphae appeared to vary independently. There were no discernible associations between properties such as length or volume of hyphal compartments at the time of septation and temporal parameters of hyphal growth. The results suggest that growth environment influences many of the processes contributing to hyphal development, but that these processes are not necessarily interrelated.     

Growth and macromolecular content of the dimorphic fungus Aureobasidium pullulans and the effect of hydroxyurea and other inhibitors

The growth kinetics and the macromolecular content of the yeast and ethanol-induced hyphal forms of Aureobasidium pullulans were studied. During the morphological transition from yeasts to hyphae, both the protein and RNA content decreased significantly, the mycelial form containing only 76% of the amount of protein in the yeasts, and 38% of the RNA. The DNA was the only component tested whose level increased during the transition. Among several compounds inhibiting macromolecular synthesis, only hydroxyurea showed a remarkable effect on the morphology of A. pullulans, inducing the mycelial morphology. The macromolecular composition of hydroxyurea-treated cultures changed with time in a way similar to that of the ethanol-Tween 80-ammonia medium, and to that of carbon-starved cultures, without ethanol or glucose.