Fig. 2: Evidence of sexual reproduction stages and peduncular phago-heterotrophy discovered for Prorocentrum cf. balticum.
From: Mucospheres produced by a mixotrophic protist impact ocean carbon cycling
Images a-d show the various stages of sexual reproduction (Supplementary Note 2); extraction of the nucleus through the peduncle (white arrow) (a), replication of DNA (b), first meiotic division (c), and second meiotic division resulting in a tetrad (d). e1, e2 Peduncular feeding mechanism (white arrow) used for phago-heterotrophic consumption of a R. salina prey cell and the resulting green-fluorescent food vacuole (black arrow). f, g Fluorescent microscope images showing: the peripheral red-fluorescent chloroplasts and intracellular green-fluorescent food vacuoles following consumption of the cryptophyte R. salina (f), and an ingested green-fluorescently labelled bacterium (g). h Growth of P. cf. balticum in co-culture ± prokaryotic (natural microbiome from xenic culture) and/or eukaryotic prey (Proteomonas sulcata) in light and dark conditions. Mean ± standard deviation (n = 6). Note that the three treatments in the dark did not grow and are overlapping with low P. cf. balticum densities. Images a–e, g were taken with an Inverted Fluorescence Microscope (Nikon Eclipse Ti), fitted with Nikon FITC 480/30 nm ex 535/45 nm em and Texas Red 560/40 nm ex 630/60 nm em filters, and a monochrome camera (Nikon DS-QiMc 12 bit) under 200 or 400× magnification. Image f was taken with a Nikon AR1 confocal microscope using lasers with 405.6–561.0 nm ex and TRITC 595 nm em, Alex610 700 nm em and TD filters at 1000× magnification with oil immersion and represents a collapsed Z-stack of 26 images (6.5 µm total distance) to clearly show the food vacuoles. Scale bars = 5 µm.
