Summary
Apical sterol‐rich plasma membrane domains (SRDs), which can be viewed using the sterol‐binding fluorescent dye filipin, are gaining attention for their important roles in polarized growth of ...filamentous fungi. The microdomain scaffolding protein flotillin/reggie and related stomatin were thought to be good candidates involved in the formation of SRDs. Here, we show that the flotillin/reggie orthologue FloA tagged with GFP localized as stable dots along the plasma membrane except hyphal tips. Deletion of floA reduced the growth rate, often resulted in irregularly shaped hyphae and impaired SRDs. In contrast, the stomatin orthologue StoA, tagged with GFP, localized at the cortex of young branch tips and at the subapical cortex in long hyphal tips, and was transported bi‐directionally along microtubules on endosomes. Deletion of stoA resulted in irregular hyphal morphology and increased branching especially in young hyphae, but did not obviously affect SRDs. Double deletion of floA and stoA enhanced the defects of growth and hyphal morphology. Our data suggest that the plasma membrane of hyphal tips and in subapical regions are distinct and that FloA is involved in membrane compartmentalization and probably indirectly in SRD maintenance.
Light sensing is very important for organisms in all biological kingdoms to adapt to changing environmental conditions. It was discovered recently that plant-like phytochrome is involved in light ...sensing in the filamentous fungus
Aspergillus nidulans
1. Here, we show that phytochrome (FphA) is part of a protein complex containing LreA (WC-1) and LreB (WC-2)
2, 3, two central components of the
Neurospora crassa blue-light-sensing system. We found that FphA represses sexual development and mycotoxin formation, whereas LreA and LreB stimulate both. Surprisingly, FphA interacted with LreB and with VeA, another regulator involved in light sensing and mycotoxin biosynthesis. LreB also interacted with LreA. All protein interactions occurred in the nucleus, despite cytoplasmic subfractions of the proteins. Whereas the FphA-VeA interaction was dependent on the presence of the linear tetrapyrrole in FphA, the interaction between FphA and LreB was chromophore independent. These results suggest that morphological and physiological differentiations in
A. nidulans are mediated through a network consisting of FphA, LreA, LreB, and VeA acting in a large protein complex in the nucleus, sensing red and blue light.
Light regulates several aspects of the biology of many organisms, including the balance between asexual and sexual development in some fungi. To understand how light regulates fungal development at ...the molecular level we have used Aspergillus nidulans as a model. We have performed a genome-wide expression analysis that has allowed us to identify >400 genes upregulated and >100 genes downregulated by light in developmentally competent mycelium. Among the upregulated genes were genes required for the regulation of asexual development, one of the major biological responses to light in A. nidulans, which is a pathway controlled by the master regulatory gene brlA. The expression of brlA, like conidiation, is induced by light. A detailed analysis of brlA light regulation revealed increased expression after short exposures with a maximum after 60 min of light followed by photoadaptation with longer light exposures. In addition to brlA, genes flbA-C and fluG are also light regulated, and flbA-C are required for the correct light-dependent regulation of the upstream regulator fluG. We have found that light induction of brlA required the photoreceptor complex composed of a phytochrome FphA, and the white-collar homologs LreA and LreB, and the fluffy genes flbA-C. We propose that the activation of regulatory genes by light is the key event in the activation of asexual development by light in A. nidulans.
It is shown here that the H2O content of hydrous minerals can be determined from their mean refractive indices with high accuracy. This is especially important when only small single crystals are ...available. Such small crystals are generally not suitable for thermal analyses or for other reliable methods of measuring the amount of H2O. In order to determine the contribution of the H2O molecules to the optical properties, the total electronic polarizability is calculated from the anhydrous part of the chemical composition using the additivity rule for individual electronic polarizabilities of cations and anions. This anhydrous contribution is then compared with the total observed electronic polarizability calculated from the mean refractive index of the hydrous compound using the Anderson–Eggleton relationship. The difference between the two values represents the contribution of H2O. The amount can be derived by solving the equation αcalc=∑iniαicat+∑jαjo×10-NjVm1.2×nj+nW1.2+nw×αW for the number nw of H2O molecules per formula unit (pfu), with the electronic polarizabilities αcat for cations, the values N and αo describing the anion polarizabilities, the number n of cations and anions, and the molar volume Vm, using a value of αW=1.62 Å3 for the electronic polarizability of H2O. The equation is solved numerically, yielding the number nw of H2O molecules per formula unit. The results are compared with the observed H2O content evaluating 157 zeolite-type compounds and 770 non-zeolitic hydrous compounds, showing good agreement. This agreement is expressed by a factor relating the calculated to the observed numbers being close to 1 for the majority of compounds. Zeolites with occluded anionic or neutral species (SO3, SO4,CO2, or CO3) show unusually high deviations between the calculated and observed amount of H2O, indicating that the polarizabilities of these species should be treated differently in zeolites and zeolite-type compounds.
Mullite-2c – a natural polytype of mullite Lenz, Stephan; Birkenstock, Johannes; Fischer, Lennart A ...
European journal of mineralogy (Stuttgart),
03/2020, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A single crystal (∼ 20 µm × 20 µm × 330 µm) of mullite-2c, a natural polytype of mullite, was separated from a radially grown cluster of acicular crystals from Ettringer Bellerberg (Quarternary Eifel ...volcanic fields, Germany). The chemical composition determined from electron microprobe analysis (EMPA) isNa0.01Mg0.05Al8.52Fe0.293+Si3.13Ti0.02O19.55, corresponding to x=0.22(8) in the generalised mineral formulaMy+Mgz2+M8+4x+y-2z3+M4-4x-y+z4+O20-2x. Only Fe3+ as foreign cation was considered in the refined structure model, partially replacing Al3+ in the octahedral chains. A crystal of a similar type, though exhibiting a significantly different composition withx=0.02, was first described in 2015, tentatively named “sillimullite” by Fischer et al. (2015). This crystal and our new sample have similar structural properties, now classified as a polytype of mullite, designated mullite-2c. Single-crystal X-ray diffraction showed that the mullite-2c crystal investigated here exhibits partial Si / Al ordering in the double chains of (Si,Al)O4 tetrahedra in contrast to the sample described in 2015 as being completely ordered. The ordering in mullite-2c results in a doubled c lattice parameter with respect to mullite. It crystallises in space group Pnam, with cell parameters for the new sample ofa=7.5432(5) Å, b=7.7048(5) Å, c=5.7965(3) Å,V=336.89(6) Å3 and Z=1. X-ray powder diffraction data are presented with a detailed discussion of the differences between the diffraction patterns of sillimanite, mullite and mullite-2c. Crystals of mullite-2c are translucent to lightly violet, they possess a vitreous lustre and the calculated density is 3.199 g cm-3. The optical character is biaxial (+), with refractive indices determined by spindle-stage microscopy of nx=1.6673, ny=1.6687 andnz=1.680(4) (adjusted to conform to 2VZ=39(4)∘). Applying the Gladstone–Dale approach, the compatibility index is 0.007, representing superior compatibility. In terms of chemical composition and structural features mullite-2c is an outstanding example of mullite-type compounds falling into the postulated miscibility gap between sillimanite and mullite. Its crystal structure combines characteristics from both mullite (oxygen vacancies, triclusters of tetrahedral building units) and sillimanite (high degree of Si / Al ordering in the tetrahedral building units, causing the doubled c parameter). The lattice parameters (normalised to 1c) of the new sample lie between those of sillimanite and 3 / 2 mullite; the chemical composition is close to 3 / 2 mullite and thus differs significantly from the silica-rich composition of the species previously determined by Fischer et al. (2015), indicating a relatively large compositional variation.
ABSTRACT
Eight yeast strains that asexually reproduce by cell fission were isolated from bee bread of different solitary bees in Germany. DNA sequence analysis revealed that the strains shared the ...same sequence in the D1/D2 domain of the nuclear large subunit (LSU) rRNA gene with a strain that was previously isolated from a fig snack from Spain. The closest related type strain was that of Schizosaccharomyces octosporus, which showed 98.2% sequence similarity (11 substitutions) with the new strains. By clone sequence analysis of the internal transcribed spacer (ITS) region (ITS1, 5.8S rDNA, and ITS2) a total of nine different copy types were identified. The new strains differed from S. octosporus by approximately 31% in the ITS region. Sequence analysis of the RNAse P gene further supported the description of a new species. The strains isolated during this study show some phenotypic characteristics that separate them from the closest related species, S. octosporus and S. cryophilus. Since all strains showed true osmophily the name of the new species is S. osmophilus (holotype: CBS 15793T; isotype: CLIB 3267 T = NCAIM Y.02225 T, MycoBank no.: MB829586).
Schizosaccharomyces osmophilus sp. nov., a true osmophilic yeast that is associated with solitary bees is described.
VO and VO
vanadyl groups with short (typically 1.57-1.68 Å), essentially covalent, V-O bonds are common for V
-bearing oxysalts with 5- and 6-coordinated vanadium. There is a clear negative ...correlation between vanadyl bond lengths and wavenumbers of the bands of V-O stretching vibrations in infrared spectra (in the range 1000-880 cm
). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone-Dale compatibility coefficients. Gladstone-Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V
. Unlike compounds of 5-coordinated Ti
, for most minerals with V
=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.
VO and VO2 vanadyl groups with short (typically 1.57–1.68 Å), essentially covalent, V—O bonds are common for V4+‐bearing oxysalts with 5‐ and 6‐coordinated vanadium. There is a clear negative ...correlation between vanadyl bond lengths and wavenumbers of the bands of V—O stretching vibrations in infrared spectra (in the range 1000–880 cm−1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone–Dale compatibility coefficients. Gladstone–Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V4+. Unlike compounds of 5‐coordinated Ti4+, for most minerals with V4+=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.
There is a clear negative correlation between the vanadyl bond lengths and wavenumbers of the bands of V—O stretching vibrations in infrared spectra. For most minerals with vanadyl bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.
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