When K was set at 4, consistent groupings were noted (Fig. 1A). Extensive reticulation was observed within the grouping as inferred from the ITS NeighborNet (Fig. 1B). The network revealed six clusters corresponding to the groupings in the concatenated phylogeny (Fig. 1A). The secondary structure Proteases inhibitor of ITS2 revealed no CBCs among the 37 sequences of A. ostenfeldii/A. peruvianum that were analyzed. A consensus structure of ITS2 is shown in Figure 3. The transcripts

revealed four universal helices (helix I–IV) in all ITS2 sequences analyzed, with conserved length, ranging from 168 to 171 nucleotides. The GC content in the helices ranged from 37% to 50%. The G–U pairings in helices were relatively low indicating high stability of helices (Fig. 3). A hemi-CBC

was observed in AONOR4, NCH85, K0287, CCMP1773, CCAP1119/45 and 47, BYK04, S6_P12_E11, S06/013/01, AOPC1 and IMPLBA033; Selleckchem AZD8055 i.e., all the investigated strains belonging to group 6. Cells size measurements of examined strains belonging to groups 1, 2, 5, and 6 are shown in Table S2, in the Supporting Information. Means of cell length, width, and the length/width (L/W) ratio varied considerably within and among strains of each group. All of the cultures examined contained both large and small cells as well as cells which were wider than long and vice versa. In group 1, the smallest strain, ASBH01, was approximately half the size of the largest strain, AOPL17, and the Baltic strains were on average more elongated with higher L/W ratios compared to the genetically nearly identical U.S. East coast strains. In group

2, Avelestat (AZD9668) cell size parameters varied significantly (P < 0.05) among the two Spanish strains (IEOVGOAM10C and IEOVGOAMD12) isolated from the same local population. The mean length and length/width rations of the group 5 strains were relatively uniform among strains (Table S2) size and shape but within strain variability was considerable. Group 6 contained the very small sized Norwegian strain AONOR4, but also a strain with large dimensions, AOPC1 from Pacific Canada. Though most strains of group 6 were slightly elongated, cells of the Peruvian strain IMPLBA033 were consistently wider than long. In general, within strain variation of size parameters was of the same magnitude as among strain variation. Despite the large variability within and among strains, there were differences in the mean size of the different groups. The cells of groups 1 and 5, for instance, were significantly larger (P < 0.05) than cells of groups 2 and 6 when means of combined measurements of all cells and strains of each group were compared (Fig. 4A). Group means in the L/W ratio were comparable in groups 1, 2, and 6 (Fig. 4B) whereas the L/W ratio of group 5 cells was significantly higher (P < 0.05) than in cells of the other groups. Strains with a particularly low L/W ratio conformed mostly to the original A. peruvianum morphotype description.