title: Transcript levels of phytoene desaturase gene inDunaliella salinaTeod. as affected by PbS nanoparticles and light intensity.
abstract: Phytoene synthase (Psy) and Phytoene desaturase (Pds) are the first two regulatory enzymes in the carotenoids biosynthetic pathway. The genesPsyandPdsare under transcriptional control in many photosynthetic organisms. In the present study, using quantitative real time- PCR (qRT-PCR), the effects of uncoated and gum-Arabic coated PbS nanoparticles (GA-coated PbS NPs) and light intensity on the mRNA levels ofPdswere investigated. Relative to mRNA level ofPdsat 100 µmol photon m-2 s-1 light intensity (control culture), 2.2-fold increase in transcript levels occurred after 12 h of exposure to higher light intensity, which is significantly (P<0.05) different compared to control. After 48 h of exposure, the mRNA level ofPdswas reduced to that in control. This indicates that light intensity regulatesPdsat the mRNA level. In the presence of uncoated and GA-coated PbS NPs, the transcript levels ofPdswere decreased over time, with uncoated PbS NPs having more inhibitory effects on mRNA levels compared to GA- coated PbS NPs. This shows that PbS NPs have adverse effects on transcription or post transcriptional processing and coating nanoparticles with biopolymers reduces their toxicity to organisms. Being under control, it seems that genetic manipulation ofPdsmay result in increased biotechnological production of carotenoids byD. salina.
authors.affiliation: Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
authors.forename: Hajar
authors.initials: H
authors.lastname: Zamani
authors.affiliation: Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Moradshahi
keywords: Carotenoids; Lead sulfide; Phytoene desaturase; qRT-PCR