Effects Of Various Drugs On The Growth Of Tetrahymena Thermophila

Oregano Essential Oil（OEO）,White Spot Clear（WSC）,Finger Ring Clear（Mebendazole solution,FRC）,Spore Worm Clear（Copper naphthenate solutionare,SWC）are common drugs to kill parasites of aquaculture organisms.The metabolic processes and molecular mechanisms of their effects are complex and need to be further explored.OEO is a natural plant extract with a wide range of action and clear composition,which is a good material to study the molecular mechanism of the effect of plant extracts on parasites.In this study,we used T.thermophila,a unicellular protozoan,as the experimental material,and determined the effects of OEO,WSC,FRC and SWC on the growth of T.thermophila by measuring its cell density,and analyzed the possible mechanisms of action of oregano essential oil on the growth of T.thermophila at the cellular and genetic levels by using transcriptome sequencing.The main results are as follows:（1）The growth curves of T.thermophila at different time points were plotted,and it was determined that T.thermophila reached a growth plateau at 48 hour under normal culture conditions,with a cell growth density of about 1.3 million cells/m L,The cell population density of T.thermophila at the beginning of logarithmic growth（～120,000cells/m L）was also used as the initial density of cells for subsequent drug treatment.（2）T.thermophila was exposed to a series of different concentrations of OEO,WSC,FRC,SWC,and the results showed that all of them had inhibitory effects on the growth of T.thermophila.The 24h median effect concentration(EC₅₀)of T.thermophila under the action of OEO,WSC,FRC and SWC were 2.16×10^-4g/m L,3.57×10^-3g/m L,7.75×10^-5g/m L and 1.41×10^-4g/m L respectively.（3）Analysis of gene expression in T.thermophila at 0 h and 24 h under the action of OEO.Based on the anaysis of high-throughput transcriptome sequencing,GO functional enrichment and KEGG pathway analysis revealed no functional enrichment of specific up-regulated differentially expressed genes and functional enrichment of specific down-regulated differentially expressed genes mainly in RNA processing,proteolytic metabolism,cellular localization and signal transduction.The specific down-regulated differentially expressed genes were mainly involved in cellular autophagy and cell cycle pathways.The downregulation of gene expression levels in these processes or pathways may inhibit cell growth.（4）Based on the analysis of gene expression changes and pathways related to T.thermophila under the action of OEO,we mapped the possible model of its influence on the cell growth of T.thermophila,which provides clues to explore the molecular regulatory mechanisms of different drugs affecting cell growth and helps to understand and appreciate the role of insecticidal drugs on the regulation of cell growth.