PMC

Fungi isolated from seeds of a commercial sprout cultivar in VA, the United States. (a) surface side of a colony on a PDA plate of Alternaria alternata, (b) reverse side of A. alternata colony, (c) surface side of a colony on a PDA plate of Fusarium equiseti, (d) reverse side of F. equiseti colony, (e) surface side of a colony on PDA plate of Fusarium proliferatum, (f) reverse side of F. proliferatum colony, (g) surface side of a colony on PDA plate of Fusarium chlamydosporum, (h) reverse side of F. chlamydosporum colony, (i) surface side of a colony on a PDA plate of Penicillium citrinum, (j) reverse side of P. citrinum colony, (k) surface side of a colony on a PDA plate of Diaphorte longicolla, (l) reverse side of D. longicolla colony, (m) surface side of a colony on PDA plate of Cladosporium cladosporioides, (n) reverse side of C. cladosporioides colony, (o) surface side of a colony on PDA plate of Phoma sp., (p) reverse side of Phoma sp. colony

Representative colonies of five phenotypes from isolate 49.07 of C. tropicalis (A) parental smooth colony; (D) crepe colony; (G) rough colony; (J) revertant of crepe (RC) and (M) revertant of rough (RR) were photographed using a stereoscopic microscope (Nikon SMZ-745). Scanning electron micrographs showing the microarchitecture of colonies following 96 h incubation on YPD agar at 28°C: (B) electron micrograph of the parental smooth colony; (E) electron micrograph of crepe variant colony; (H) electron micrograph of rough variant colony; (K) electron micrograph of the revertant of crepe colony and (N) electron micrograph of revertant of rough colony. Electron micrographs of cells types: (C) cells from parental smooth colony; (F) cells from crepe variant colony; (I) cells from rough variant colony; (L) cells from revertant of crepe colony and (O) cells from revertant of rough colony. White bar: 2 mm (A,D,G,J,M); 1 mm (B,E,H,K,N); 20µm (C,F,I,L,O).

Lissoclinum and Trididemnum species. (A, B), Lissoclinum bistratum at Gonzibi (A, colony; B, tunic spicules). (C–E), Lissoclinum midui at Gonzibi (C, colony; D, thorax; E, tunic spicules). (F–H), Lissoclinum punctatum at Gonzibi (F, colony; G tunic phycocyte; H, tunic spicules). (I–L), Trididemnum clinides at Shimen (I, colony; J, tunic spicules; K, unicellular cyanobacteria in the tunic; L, filamentous, multicellular cyanobacteria in the tunic). (M–P), Trididemnum cyclops at Shimen (M, colony; N, tunic spicules; O, enlargement of colony surface showing a zooid; P, thorax). Arrows in O and P indicate pigmentation at the top of endostyle (pigment cap). an, anus; fp, fecal pellet; g, greenish cyanobacteria; n, nucleus of tunic phycocyte; r, reddish cyanobacterium; un, unknown organ. Scale bars: B, E, G, H, J–L, N, and O = 20 μm; D and P = 0.1 mm; O = 0.2 mm.

In response to unspecified environmental cue(s) sensed by HK11, the 53^rd conserved aspartic acid residue of RR11 is phosphorylated by HK11 or an alternative donor(s) of phosphoryl group, which in turn activates the comW and hyaluronate utilization locus. By the undefined mechanism(s), the RR11-activated genes act to drive the directions of the hsdS inversions toward the hsdS_A1 allelic configuration and eventually the O colony phase. Likewise, RR06, RR08 and RR09 promote the hsdS_A1 allelic configuration and O colony phase by the uncharacterized mechanisms. RR14 modulates colony phases in a non-epigenetic manner.