Effects of Florida Red Tides on histone variant expression and DNA methylation in the Eastern oyster Crassostrea virginica.
Massive algal proliferations known as Harmful Algal Blooms (HABs) represent one of the most important threats to coastal areas. Among them, the so-called Florida Red Tides (FRTs, caused by blooms of the dinoflagellate Karenia brevis and associated brevetoxins) are particularly detrimental in the southeastern U.S., causing high mortality rates and annual losses in excess of $40 million. The ability of marine organisms to cope with environmental stressors (including those produced during HABs) is influenced by genetic and epigenetic mechanisms, the latter resulting in phenotypic changes caused by heritable modifications in gene expression, without involving changes in the genetic (DNA) sequence. Yet, studies examining cause-effect relationships between environmental stressors, specific epigenetic mechanisms and subsequent responses are still lacking. The present work contributes to increase this knowledge by investigating the effects of Florida Red Tides on two types of mechanisms participating in the epigenetic memory of Eastern oysters: histone variants and DNA methylation. For that purpose, a HAB simulation was conducted in laboratory conditions, exposing oysters to increasing concentrations of K. brevis. The obtained results revealed, for the first time, the existence of H2A.X, H2A.Z and macroH2A genes in this organism, encoding histone variants potentially involved in the maintenance of genome integrity during responses to the genotoxic effect of brevetoxins. Additionally, an increase in H2A.X phosphorylation (γH2A.X, a marker of DNA damage) and a decrease in global DNA methylation were observed as the HAB simulation progressed. Overall, the present work provides a basis to better understand how epigenetic mechanisms participate in responses to environmental stress in marine invertebrates, opening new avenues to incorporate environmental epigenetics approaches into management and conservation programs.
Environmental Epigenetics Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA.
Rodrigo
R
Gonzalez-Romero
Environmental Epigenetics Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA.
Victoria
V
Suarez-Ulloa
Environmental Epigenetics Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA; Ecotoxicology and Risk Assessment Laboratory, Southeast Environmental Research Center, Florida International University, North Miami, FL 33181, USA.
Javier
J
Rodriguez-Casariego
Departamento de Bioquimica, Xenetica e Inmunoloxia, Universidade de Vigo, E-36310 Vigo, Spain.
Daniel
D
Garcia-Souto
Environmental Epigenetics Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA.
Gabriel
G
Diaz
Ecotoxicology and Risk Assessment Laboratory, Southeast Environmental Research Center, Florida International University, North Miami, FL 33181, USA.
Abraham
A
Smith
Departamento de Bioquimica, Xenetica e Inmunoloxia, Universidade de Vigo, E-36310 Vigo, Spain.
Juan Jose
JJ
Pasantes
Ecotoxicology and Risk Assessment Laboratory, Southeast Environmental Research Center, Florida International University, North Miami, FL 33181, USA.
Gary
G
Rand
Environmental Epigenetics Group, Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA. Electronic address: jeirinlo@fiu.edu.
Jose M
JM
Eirin-Lopez
D000818:Animals; D049896:Crassostrea / Q000187:drug effects / Q000235:genetics*; D019175:DNA Methylation / Q000187:drug effects; D004141:Dinoflagellida / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects; D005431:Florida; D005786:Gene Expression Regulation / Q000187:drug effects; D057097:Harmful Algal Bloom / Q000187:drug effects; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D008387:Marine Toxins / Q000633:toxicity; D035964:Oxocins / Q000633:toxicity; D010766:Phosphorylation / Q000187:drug effects; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity; D000095702:Polyether Toxins
D006657:Histones; D008387:Marine Toxins; D035964:Oxocins; D014874:Water Pollutants, Chemical; C053342:brevetoxin; D000095702:Polyether Toxins
Brevetoxins; DNA methylation; Environment; Epigenetics; Harmful algal blooms; Histone variants; Oysters