Fig. 5

Fluorescent in situ hybridization of Ca. D. californiensis in skin tissue of the nudibranch Doriopsilla fulva. The upper series of images shows an identical histological section labeled with a, a' universal eukaryotic probe EUK516 (pseudocolored in gray); b, b' universal bacterial EUB338 I-III 16S rRNA probe mixture (green); c, c' Ca. D. californiensis-specific 16S rRNA probes (red); and counterstained with Hoechst 33,342 DNA stain (d, d'; blue). All channels (a-d, a'-d') are merged in e, e' showing proportions of Ca. D. californiensis (yellow–red) to other bacteria (green). Inserts (a'-e') show localization of Ca. D. californiensis within epithelial tissue. Ca. D. californiensis (arrows, e') is mostly affiliated with mucus secreting goblet cells (identifiable by large vacuolate space labeled with asterisks: a', e'). The bottom series of images shows co-localization of Ca. D. californiensis and KC-12 probe signals (f–k). Eukaryotic EUK516 probe (f), bacterial EUB338 I-III probes (g), Ca. D. californiensis specific probes (e), and KC-12 probe (i, pseudocolored in purple) are merged in j ( Ca. D. californiensis, bacterial, and eukaryotic probes) and k (bacterial, eukaryotic, and KC-12 probe). Note that bacteria not hybridized with Ca. D. californiensis specific probes (arrowheads) also lack the KC-12 probe signal (j, k)