Effects of in vitro exposure to diarrheic toxin producer Prorocentrum lima on gene expressions related to cell cycle regulation and immune response in Crassostrea gigas.
BACKGROUND
Crassostrea gigas accumulates diarrheic shellfish toxins (DSP) associated to Prorocentrum lima of which Okadaic acid (OA) causes specific inhibitions of serine and threonine phosphatases 1 and 2A. Its toxic effects have been extensively reported in bivalve mollusks at cellular and physiological levels, but genomic approaches have been scarcely studied.


RESULTS
Acute and sub-chronic exposure effects of P. lima were investigated on farmed juvenile C. gigas (3-5 mm). The Pacific oysters were fed with three dinoflagellate concentrations: 0.3, 3, and 30 ×10(3) cells mL-1 along with a nontoxic control diet of Isochrysis galbana. The effects of P. lima on C. gigas were followed by analyzing expression levels of a total of four genes, three involved in cell cycle regulation and one in immune response by polymerase chain reaction and real time quantitative PCR, where changes in time and cell concentration were found. The highest expression levels were found in oysters fed 3 × 10(3) cells mL-1 at 168 h for the cycle regulator p21 protein (9 fold), chromatin assembly factor 1 p55 subunit (8 fold), elongation factor 2 (2 fold), and lipopolysaccharide/β-1, 3 glucan binding protein (13 fold above base line). Additionally, the transcript level of all the genes decreased in oysters fed wich the mixed diet 30 × 10(3) cells mL-1 of dinoflagellate after 72 h and was lowest in the chromatin assembly factor 1 p55 subunit (0.9 fold below baseline).


CONCLUSIONS
On C. gigas the whole cell ingestion of P lima caused a clear mRNA modulation expression of the genes involved in cell cycle regulation and immune system. Over-expression could be related to DNA damage, disturbances in cell cycle continuity, probably a genotoxic effect, as well as an activation of its innate immune system as first line of defense.
Molecular Genetics Laboratory, Centro de Investigaciones Biológicas del Noroeste, S.C. La Paz, Baja California Sur, México; Department of Engineering, Instituto Tecnológico de La Paz, Baja California Sur, México.
Reyna
R
de Jesús Romero-Geraldo
Molecular Genetics Laboratory, Centro de Investigaciones Biológicas del Noroeste, S.C. La Paz, Baja California Sur, México.
Norma
N
García-Lagunas
Molecular Genetics Laboratory, Centro de Investigaciones Biológicas del Noroeste, S.C. La Paz, Baja California Sur, México.
Norma Yolanda
NY
Hernández-Saavedra
D000704:Analysis of Variance; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D049896:Crassostrea / Q000469:parasitology*; D017931:DNA Primers / Q000235:genetics; D004141:Dinoflagellida / Q000737:chemistry*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007113:Immunity, Innate / Q000187:drug effects*; D008387:Marine Toxins / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D060888:Real-Time Polymerase Chain Reaction
D018797:Cell Cycle Proteins; D017931:DNA Primers; D008387:Marine Toxins