AUTHOR=Lima Michele S. , Hamerski Lidilhone , Silva Tatiana A. , da Cruz Maria Luíza R. , Varasteh Tooba , Tschoeke Diogo A. , Atella Georgia C. , de Souza Wanderley , Thompson Fabiano L. , Thompson Cristiane C. 

TITLE=Insights on the biochemical and cellular changes induced by heat stress in the Cladocopium isolated from coral Mussismilia braziliensis

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.973980

DOI=10.3389/fmicb.2022.973980

ISSN=1664-302X

ABSTRACT=<p>Corals are treatened by global warming. Bleaching is one immediate effect of global warming, resulting from the loss of photosynthetic endosymbiont dinoflagellates. Understanding host-symbiont associations are critical for assessing coral’s habitat requirements and its response to environmental changes. <italic>Cladocopium</italic> (formerly family Symbiodiniaceae clade C) are dominant endosymbionts in the reef-building coral, <italic>Mussismilia braziliensis</italic>. This study aimed to investigate the effect of temperature on the biochemical and cellular features of <italic>Cladocopium</italic>. Heat stress increased oxygen (O<sub>2</sub>) and decreased proteins, pigments (Chla + Chlc2), hexadecanoic acid- methyl ester, methyl stearate, and octadecenoic acid (Z)- methyl ester molecules. In addition, there was an increase in neutral lipids such as esterified cholesterol and a decrease in free fatty acids that may have been incorporated for the production of lipid droplets. Transmission electron microscopy (TEM) demonstrated that <italic>Cladocopium</italic> cells subjected to heat stress had thinner cell walls, deformation of chloroplasts, and increased lipid droplets after 3 days at 28°C. These findings indicate that thermal stress negatively affects isolated <italic>Cladocopium</italic> spp. from <italic>Mussismilia</italic> host coral.</p>