Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mu...Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mutants,while the physiological role of their residual plastid DNAs remains unclear.In this study,we obtained five bleached mutants by ofloxacin(Ofl)treatment,identified 12 residual plastid genes in five bleached mutants,and determined the mRNA levels in the wild type E.gracilis(WT)and one bleached mutant(OflB2)under dark and light stimulation conditions by quantitative reverse transcribed PCR(qRTPCR).Results show that the expression of all selected plastid genes in both WT and OflB2 mutant did not change significantly in darkness,while their responses to light stimulation were different.Under the light stimulation conditions,half of the genes did not change significantly,while most of the other genes were down-regulated in OflB2 mutant and up-regulated in WT.Therefore,the bleached mutant retains part of the plastid genome and the plastid relic is responsive to light.Our research will help to understand the functions of residual plastid DNA and evolution of chloroplasts.展开更多
The cDNA of the metallothionein-like(MT-like)gene from Festuca rubra cv.Merlin was optimized with bias codon of Chlamydomonous reinhardtii chloroplast genome.The optimized MT-like gene was de-livered into C.reinhardti...The cDNA of the metallothionein-like(MT-like)gene from Festuca rubra cv.Merlin was optimized with bias codon of Chlamydomonous reinhardtii chloroplast genome.The optimized MT-like gene was de-livered into C.reinhardtii chloroplast and the transgenic strains expressing MT-like gene was obtained.PCR-Southern blot and RT-PCR-Southern blot analysis demonstrated that the MT-like gene was inte-grated into chloroplast genome of C.reinhardtii and expressed at the transcriptional level.The cad-mium binding capacity of the transgenic C.reinhardtii was determined by hydride generation-atomic fluorescence spectrometry(HG-AFS)and the binding properties were analyzed.Results showed that the transgenic C.reinhardtii expressing the MT-like gene exhibited remarkably higher Cd2+binding capacity and grew to higher densities at toxic Cd2+concentrations(40-100μmol/L)than the wild type strain,and that the IC50 of Cd2+(3-d treating)to algal cell growth of transgenic strain was 55.43%higher than that of the wild type strain,indicating that the Cd2+binding capacity and Cd2+tolerance of C.reinhardtii was enhanced through the expression of the foreign MT-like gene in chloroplast.展开更多
基金Supported by the National Natural Science Foundation of China(No.31670116)the Guangdong Innovation Research Team Fund(No.2014ZT05S078)the Shenzhen Grant Plan for Science&Technology(Nos.JCYJ20160308095910917,JCYJ20170818100339597,JCYJ 20130329114940668)。
文摘Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mutants,while the physiological role of their residual plastid DNAs remains unclear.In this study,we obtained five bleached mutants by ofloxacin(Ofl)treatment,identified 12 residual plastid genes in five bleached mutants,and determined the mRNA levels in the wild type E.gracilis(WT)and one bleached mutant(OflB2)under dark and light stimulation conditions by quantitative reverse transcribed PCR(qRTPCR).Results show that the expression of all selected plastid genes in both WT and OflB2 mutant did not change significantly in darkness,while their responses to light stimulation were different.Under the light stimulation conditions,half of the genes did not change significantly,while most of the other genes were down-regulated in OflB2 mutant and up-regulated in WT.Therefore,the bleached mutant retains part of the plastid genome and the plastid relic is responsive to light.Our research will help to understand the functions of residual plastid DNA and evolution of chloroplasts.
基金Supported by the Natural Science Foundation of Guangdong Province(Grant No.5010492)the Plan of Science and Technology of Shenzhen Municipality,China
文摘The cDNA of the metallothionein-like(MT-like)gene from Festuca rubra cv.Merlin was optimized with bias codon of Chlamydomonous reinhardtii chloroplast genome.The optimized MT-like gene was de-livered into C.reinhardtii chloroplast and the transgenic strains expressing MT-like gene was obtained.PCR-Southern blot and RT-PCR-Southern blot analysis demonstrated that the MT-like gene was inte-grated into chloroplast genome of C.reinhardtii and expressed at the transcriptional level.The cad-mium binding capacity of the transgenic C.reinhardtii was determined by hydride generation-atomic fluorescence spectrometry(HG-AFS)and the binding properties were analyzed.Results showed that the transgenic C.reinhardtii expressing the MT-like gene exhibited remarkably higher Cd2+binding capacity and grew to higher densities at toxic Cd2+concentrations(40-100μmol/L)than the wild type strain,and that the IC50 of Cd2+(3-d treating)to algal cell growth of transgenic strain was 55.43%higher than that of the wild type strain,indicating that the Cd2+binding capacity and Cd2+tolerance of C.reinhardtii was enhanced through the expression of the foreign MT-like gene in chloroplast.
