Zeocin can cause double strand breaks of DNA and thus is frequently used as a selective antibiotic of eukaryotic Sh ble transformants. In non-transformation system, Zeocin may function as a mutagen if not totally leth...Zeocin can cause double strand breaks of DNA and thus is frequently used as a selective antibiotic of eukaryotic Sh ble transformants. In non-transformation system, Zeocin may function as a mutagen if not totally lethal. To verify such function of Zeocin, we mutated Nannochloropsis oceanica by increasing the concentration of Zeocin in medium gradually, and isolated a N. oceanica strain(single cell culture) which survived Zeocin up to 10.0μg mL^(-1). The Zeocin-tolerant strain entered the exponential growth phase later and grew slower than the wild strain. Transcriptome profiling showed that the Zeocin-tolerant N. oceanica strain survived Zeocin mainly by adapting(heritable), rather than acclimating(plastic) to Zeocin. Hence mutating N. oceanica with Zeocin was approved effective. Meanwhile, the physiological characteristics of this Zeocin-tolerant strain were demonstrated. As we proposed, N. oceanica tolerated Zeocin by strengthening its protein degradation and antioxidation. The genes controlling cell division and cellular response to stimuli may also have played important roles in the reduction of growth and the tolerance to Zeocin. Our findings evidenced that Zeocin can serve as an appropriate mutagen of microalgae. Creating variations through mutation with Zeocin may help to study the genetic basis of the traits of this monoploidy and asexual microalga, as well as improve its production.展开更多
Zeocin can cause double strand breaks of DNA and thus may be employed as a mutagen.In this study,two strains of Nannochloropsis oceanica,the wild and the Zeocin-tolerant strains,were re-sequenced to verify such functi...Zeocin can cause double strand breaks of DNA and thus may be employed as a mutagen.In this study,two strains of Nannochloropsis oceanica,the wild and the Zeocin-tolerant strains,were re-sequenced to verify such function of Zeocin.The results showed that Zeocin can mutate the N.oceanica genome and cause the structural variation.Zeocin either swept away or selected the alleles of genes functioning in ubiquitin-mediated proteolysis,alpha-linolenic acid metabolism,ascorbate and aldarate metabolism,ribosome biogenesis,and circadian rhythm,indicating that N.oceanica may have adjusted its metabolic performances for protein,carbohydrate,and lipid,and changed its ribosome biosynthesis and living rhythm to survive in Zeocin containing medium.In addition,Zeocin caused mutation may have influenced the expression of a set of transcription factors.It was concluded that Zeocin effectively caused the structural variation of the genome of N.oceanica,and forced the microalgae to select out the alleles of a set of genes around these variations in order to adapt to Zeocin containing medium.Further studies on the genetic basis of the phenotypic adaptation of this haploid and asexual microalga and the application of Zeocin to its genetic improvement are very important.展开更多
Saccharina japonica is an economically important cold water brown alga extensively cultivated in China. It is cultivated upside down under a floating rope net with its holdfast and meristematic area facing sunlight an...Saccharina japonica is an economically important cold water brown alga extensively cultivated in China. It is cultivated upside down under a floating rope net with its holdfast and meristematic area facing sunlight and UV irradiation and its blade tip toward dark, and other worse cultivation environmental factors also make S . japonic a face more stresses. In this study, S . japonica transcriptomes corresponding to its four developmental stages were analyzed. In total, 7 800 genes predicted in the genome were transcribed. We found that 1 208 of the 7 800 expressed and 2 697 annotated were virus associating genes. Of 778 diff erentially expressed genes (DEGs), 372 were annotatable and 209 were virus associating. Such portion of virus associating genes indicated that the S . japonica genome contained a large portion of active virus originating genes. It was found that the transcripts abundance associated with sugar biosynthesis was about 2.13 folds of all the expressed, indicating that the biosyntheses of structural and storage sugars were very important cellular processes. The total abundance of genes involved in the biosynthesis of alginate and laminarin were similar among all developmental stages, however, that of genes involved in the biosynthesis of mannitol increased about 2-folds from mushroom and adult stages to mature and aging stages. This trend explained our observation that the content of alginate was almost constant at diff erent development stages, while that of mannitol increased sharply. In addition, we found that a set of defense and cell recurring genes highly expressed and many of them expressed diff erentially among stages. On average, the sum abundance of the transcripts of these genes at four stages were 3.40-and 4.96-folds of all the annotated and all the expressed, respectively. This indicated that S . japonica sporophytes persistently respond possible pathogen and environment stresses. The findings are important for timing S . japonica harvest and amending the current cultivation mode.展开更多
Genus Grateloupia is one of the most speciose genera in family Halymeniales. It is also one of the sources for natural materials, food and medicine. With different environments, Grateloupia change their morphological ...Genus Grateloupia is one of the most speciose genera in family Halymeniales. It is also one of the sources for natural materials, food and medicine. With different environments, Grateloupia change their morphological characteristics, making their morphological identification very difficult. In addition, few of the species diversity in this genus has been described before. In this study, phylogenetic analysis based on rbc L gene sequence was employed to group Grateloupia collected from three locations along Chinese coast. The microsatellites were also used to evaluate their genetic diversity. In total, the tissue parts of 6 putative species were collected from G. asiatica, G. livida, G. lanceolate, G. catenata, G. turuturu and G. filicina. In order to evaluate their genetic diversity and then conserve them better, 40 microsatellites available for Grateloupia were used to evaluate their genetic diversity, and 11 microsatellites were found to be applicable to determine the genetic diversity of G. asiatica. It was found that the genetic diversity of G. asiatica around Qingdao was very rich. We suggested that the species of genus Grateloupia should be identified based on rbc L phylogenetic analysis before the diversity evaluation with microsatellites. The microsatellites should be developed for each species of Grateloupia so that their genetic diversity can be evaluated appropriately.展开更多
基金funded by the National Natural Science Foundation of China (No. 31270408)National High Technology Research and Development Program (863 Program) of China (No. 2014AA022001)
文摘Zeocin can cause double strand breaks of DNA and thus is frequently used as a selective antibiotic of eukaryotic Sh ble transformants. In non-transformation system, Zeocin may function as a mutagen if not totally lethal. To verify such function of Zeocin, we mutated Nannochloropsis oceanica by increasing the concentration of Zeocin in medium gradually, and isolated a N. oceanica strain(single cell culture) which survived Zeocin up to 10.0μg mL^(-1). The Zeocin-tolerant strain entered the exponential growth phase later and grew slower than the wild strain. Transcriptome profiling showed that the Zeocin-tolerant N. oceanica strain survived Zeocin mainly by adapting(heritable), rather than acclimating(plastic) to Zeocin. Hence mutating N. oceanica with Zeocin was approved effective. Meanwhile, the physiological characteristics of this Zeocin-tolerant strain were demonstrated. As we proposed, N. oceanica tolerated Zeocin by strengthening its protein degradation and antioxidation. The genes controlling cell division and cellular response to stimuli may also have played important roles in the reduction of growth and the tolerance to Zeocin. Our findings evidenced that Zeocin can serve as an appropriate mutagen of microalgae. Creating variations through mutation with Zeocin may help to study the genetic basis of the traits of this monoploidy and asexual microalga, as well as improve its production.
基金funded by the National Natural Science Foundation of China(No.31270408)the National High Technology Research and Development Program(863 Program) of China(No.2014AA022001)
文摘Zeocin can cause double strand breaks of DNA and thus may be employed as a mutagen.In this study,two strains of Nannochloropsis oceanica,the wild and the Zeocin-tolerant strains,were re-sequenced to verify such function of Zeocin.The results showed that Zeocin can mutate the N.oceanica genome and cause the structural variation.Zeocin either swept away or selected the alleles of genes functioning in ubiquitin-mediated proteolysis,alpha-linolenic acid metabolism,ascorbate and aldarate metabolism,ribosome biogenesis,and circadian rhythm,indicating that N.oceanica may have adjusted its metabolic performances for protein,carbohydrate,and lipid,and changed its ribosome biosynthesis and living rhythm to survive in Zeocin containing medium.In addition,Zeocin caused mutation may have influenced the expression of a set of transcription factors.It was concluded that Zeocin effectively caused the structural variation of the genome of N.oceanica,and forced the microalgae to select out the alleles of a set of genes around these variations in order to adapt to Zeocin containing medium.Further studies on the genetic basis of the phenotypic adaptation of this haploid and asexual microalga and the application of Zeocin to its genetic improvement are very important.
基金Supported by the Fundamental Research Funds for the Central Universities(No.201762017)
文摘Saccharina japonica is an economically important cold water brown alga extensively cultivated in China. It is cultivated upside down under a floating rope net with its holdfast and meristematic area facing sunlight and UV irradiation and its blade tip toward dark, and other worse cultivation environmental factors also make S . japonic a face more stresses. In this study, S . japonica transcriptomes corresponding to its four developmental stages were analyzed. In total, 7 800 genes predicted in the genome were transcribed. We found that 1 208 of the 7 800 expressed and 2 697 annotated were virus associating genes. Of 778 diff erentially expressed genes (DEGs), 372 were annotatable and 209 were virus associating. Such portion of virus associating genes indicated that the S . japonica genome contained a large portion of active virus originating genes. It was found that the transcripts abundance associated with sugar biosynthesis was about 2.13 folds of all the expressed, indicating that the biosyntheses of structural and storage sugars were very important cellular processes. The total abundance of genes involved in the biosynthesis of alginate and laminarin were similar among all developmental stages, however, that of genes involved in the biosynthesis of mannitol increased about 2-folds from mushroom and adult stages to mature and aging stages. This trend explained our observation that the content of alginate was almost constant at diff erent development stages, while that of mannitol increased sharply. In addition, we found that a set of defense and cell recurring genes highly expressed and many of them expressed diff erentially among stages. On average, the sum abundance of the transcripts of these genes at four stages were 3.40-and 4.96-folds of all the annotated and all the expressed, respectively. This indicated that S . japonica sporophytes persistently respond possible pathogen and environment stresses. The findings are important for timing S . japonica harvest and amending the current cultivation mode.
基金supported by the Marine Industry Research Special Funds for Public Welfare Projects(No.201205024)
文摘Genus Grateloupia is one of the most speciose genera in family Halymeniales. It is also one of the sources for natural materials, food and medicine. With different environments, Grateloupia change their morphological characteristics, making their morphological identification very difficult. In addition, few of the species diversity in this genus has been described before. In this study, phylogenetic analysis based on rbc L gene sequence was employed to group Grateloupia collected from three locations along Chinese coast. The microsatellites were also used to evaluate their genetic diversity. In total, the tissue parts of 6 putative species were collected from G. asiatica, G. livida, G. lanceolate, G. catenata, G. turuturu and G. filicina. In order to evaluate their genetic diversity and then conserve them better, 40 microsatellites available for Grateloupia were used to evaluate their genetic diversity, and 11 microsatellites were found to be applicable to determine the genetic diversity of G. asiatica. It was found that the genetic diversity of G. asiatica around Qingdao was very rich. We suggested that the species of genus Grateloupia should be identified based on rbc L phylogenetic analysis before the diversity evaluation with microsatellites. The microsatellites should be developed for each species of Grateloupia so that their genetic diversity can be evaluated appropriately.
