NanoSIMS and tissue autoradiography reveal symbiont carbon fixation and organic carbon transfer to giant ciliate host.
Jean-Marie VollandArno SchintlmeisterHelena ZambalosSiegfried ReipertPatricija MozetičSalvador Espada-HinojosaValentina TurkMichael WagnerMonika BrightPublished in: The ISME journal (2018)
The giant colonial ciliate Zoothamnium niveum harbors a monolayer of the gammaproteobacteria Cand. Thiobios zoothamnicoli on its outer surface. Cultivation experiments revealed maximal growth and survival under steady flow of high oxygen and low sulfide concentrations. We aimed at directly demonstrating the sulfur-oxidizing, chemoautotrophic nature of the symbionts and at investigating putative carbon transfer from the symbiont to the ciliate host. We performed pulse-chase incubations with 14C- and 13C-labeled bicarbonate under varying environmental conditions. A combination of tissue autoradiography and nanoscale secondary ion mass spectrometry coupled with transmission electron microscopy was used to follow the fate of the radioactive and stable isotopes of carbon, respectively. We show that symbiont cells fix substantial amounts of inorganic carbon in the presence of sulfide, but also (to a lesser degree) in the absence of sulfide by utilizing internally stored sulfur. Isotope labeling patterns point to translocation of organic carbon to the host through both release of these compounds and digestion of symbiont cells. The latter mechanism is also supported by ultracytochemical detection of acid phosphatase in lysosomes and in food vacuoles of ciliate cells. Fluorescence in situ hybridization of freshly collected ciliates revealed that the vast majority of ingested microbial cells were ectosymbionts.
Keyphrases
- induced apoptosis
- cell cycle arrest
- mass spectrometry
- endoplasmic reticulum stress
- gene expression
- blood pressure
- computed tomography
- oxidative stress
- ms ms
- cell proliferation
- heart rate
- human health
- sensitive detection
- liquid chromatography
- pi k akt
- quantum dots
- free survival
- loop mediated isothermal amplification
- rare case
- gas chromatography
- label free
- simultaneous determination
- water soluble
- protein kinase