Journal: bioRxiv
Article Title: Dynamic Reprogramming of Fungal Cell Walls Underlies Germination and Immune Exposure in Zygomycetous Fungal Pathogens
doi: 10.64898/2026.05.12.724644
Figure Lengend Snippet: ( A ) TEM images of the dormant conidia reveal a multilayered cell wall architecture, including an electron-dense outer layer and inner polysaccharide-rich regions. ( B ) At high magnification, osmium-fixed, epoxy-embedded samples (left) preserve structural integrity, whereas LR White–embedded samples prepared without OsO 4 (right) enhance contrast in the outer wall. Sub-labels denote (i) outer electron-dense region, (ii) granular region, and (iii) electron-lucent inner layer. Without OsO 4 , the outer layer appears as a thin electron-lucent band consistent with melanin, with the remaining regions largely electron-lucent. ( C ) Rigid molecules in the dormant conidial cell walls were detected by 2D 13 C- 13 C CORD spectra, showing signals from β-1,3-glucan (B), chitin (Ch), and chitosan (Cs). Superscripts indicate different structural forms of each polysaccharide, and the numbers denote carbon positions. For example, Cs a 1-2 represents the correlation between carbons 1 and 2 in type-a chitosan. ( D ) Structural representations of carbohydrates. Yellow bars indicate whether each molecule is detected in the rigid phase, the mobile phase, or in both. NMR abbreviations are given. Key carbon sites are numbered. ( E ) Composition of rigid carbohydrates in dormant conidia based on intensity analysis of the 2D CORD spectrum. ( F ) Overlay of 2D CORD spectra of dormant conidia (blue) and 3-day-old mycelia (orange). ( G ) Cytochemical labeling of dormant conidia shows gold-specific staining for β-1,3-glucan with Fc-Dectin-1, chitin (with Wheat germ agglutinin lectin (WGA-lectin), and anti-chitosan rabbit antiserum. Black dots represent electron-dense gold particles indicating probe binding. Scale bars: 500 nm. ( H ) Mobile molecules in dormant conidia detected by the 2D 13 C-DP refocused J-INADEQUATE spectrum. In addition to β-1,3-glucan and two forms of chitosan, signals are detected for Fuc (F), Gal, α-1,2-Man (Mn , ), and α-1,6-Man (Mn , ). ( I ) Cytochemical binding of Concanavalin-A lectin (ConA) to dormant conidial cell walls confirms the presence of mannans and/or glycoproteins. Zoomed-in view of 2D 13 C-DP J-INADEQUATE spectrum was presented for ( J ) C5-C6 correlations of polymeric fucoses and ( K ) glucuronic acid (GlcA). Polymeric fucoses show five forms (a,b, c, d, i) as traced by dashed lines in dormant conidia (blue) while type-e is present only in mycelia (orange).
Article Snippet: Grids were washed with endotoxin-free water and incubated for 1 h with 100 μg mL -1 recombinant human Fc-Dectin-1 (Fc-hDectin-1a, InvivoGen).
Techniques: Labeling, Staining, Binding Assay