The series Variantia Ching et S. H. Wu mainly occur in China and its members are highly variable in morphology. The denomination on this group of Asplenium is very confused in the herbaria. We hop e by means of a bios...The series Variantia Ching et S. H. Wu mainly occur in China and its members are highly variable in morphology. The denomination on this group of Asplenium is very confused in the herbaria. We hop e by means of a biosystematic study to find out their genetic relationships in the reticulate evolution, and to raise a suggestion on their taxonomic treatment. Evidence from cytology, allozyme, morphology, and palynology shows that three ancestor diploids have formed Asplenium sarelii complex comprising 13 members. A. sarelii Hook. should be typified as a diploid. The so-called tetraploid 'A. sarelii' before is an allotetraploid that comes from the doubled hybrid between diploid A. sarelii and A. tenuicaule Hayata, which should be treated as a new species A. wudangense Z. R. Wang et X. Hou. A. pekinense Hance is an autotetraploid that comes from the doubled diploid ancestor A. sarelii. A. lushanense C. Chr., a diploid species and the only ancestor of A. yunnariense group, should not been sunk as a synonym of tetraploid A. yunnariense Franch. Most probably, A. varians Wall. ex Hook. et Grev. is an autotetraploid of A. tenuicaule Hayata. Three new natural tetraploid hybrids and their origins have been found out: they are A. x longmenense ( = A. pekinense x varians), A. x jingyunense ( = A. pekinense x yunnanense) and A. x kidoi ( = A. pekinense x wudangense). Three other new natural triploid hybrids have been found and their origins have been inferred: they are A. X huawuense ( = A. sarelii X wudangense), A. x luyunense ( = A. lushanense x yunnanense) and A. x teniuvaians ( = A. tenuicaule x varians). The method of allozyme comparion combined with cytological observation is employed to reveal the complicated relationships among the members of Asplenium sarelii complex in reticulate evolution and proved to be a highly effective tool to investigate the origin of polyploid and hybrid.展开更多
Mangrove endophytic fungus 1893 was isolated from Kandelia candel from an estuarine mangrove on the South China Sea Coast Two new lactones 1893A and 1893B, together with other known compounds, have been isolated from ...Mangrove endophytic fungus 1893 was isolated from Kandelia candel from an estuarine mangrove on the South China Sea Coast Two new lactones 1893A and 1893B, together with other known compounds, have been isolated from its fermentation broth. To classify the endophyte correctly for further industrial application, a combination of morphological and molecular techniques was used to approach its identity. The endophyte was compared with similar species having trichogynes or trichogyne-like hyphae which apparently fused with an- theridium-like hyphae, and perithecia initials developing from an ascogonial coil surrounded by enveloping hyphae in early developmental stages on pure culture. Further morphological characteristics on host and non-host were used for comparison with similar species when the endophyte was cultivated on leaves ofKandelia candel and Mangifera indica, respectively, which resulted in classifying the endophyte as a Phomopsis specics. The ITS sequence of rDNA was used to infer its phylogenetic relationships with Phomopsis species that resembled the strain in morphology or ecology. Finally, the endophyte was identified as Diaporthe phaseolorum var. sojae based on morphological and molecular evidence. Our study is a first report ofDiaporthephaseolorum var. sojae isolated from mangrove Kandelia candel.展开更多
The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets o...The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics： genome skimming, transcriptome sequencing （RNA- seq）, restriction site associated DNA sequencing （RAD-Seq）, and targeted capture （Hyb-seq）. Of these four genome-partitioning approaches, targeted capture （especially Hyb-seq） shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.展开更多
Lake Dianchi has undergone accelerated alternations resulting from human activities during the last 50 years, and provides an exceptional example for the study of regime shift in a shallow lake. Focusing on regime shi...Lake Dianchi has undergone accelerated alternations resulting from human activities during the last 50 years, and provides an exceptional example for the study of regime shift in a shallow lake. Focusing on regime shift, we systematically studied and analysed alternations of key components of its ecosystem, including water parameters, phytoplankton and zooplankton biomass, macrophyte composition and fish populations. We found that the shifting course of Lake Dianchi went through three major phases, corresponding to three distinct states: Phase I clean, stable state during the 1950 s; Phase II transitional state during the 1970 s–1980 s; and phase III stable, turbid state since 1993. We analysed all data and samples, identifying the threshold concentrations at which regime shift occurred: total nitrogen(TN) and phosphorus(TP) reaching 1.2 mg/L and 0.13 mg/L, respectively. Results from this study strongly suggest that the increasing input of external nutrients, reclaiming land from the lake and foreign fish invasion were major inducements to the accelerated shift of Lake Dianchi to its turbid, stable state. These findings provide valuable guidelines for potential efforts to reverse this unnatural process in Lake Dianchi. The restoration may need to:(1) thoroughly and accurately identify pollution sources to control and reduce excessive external nutrients flowing into the lake;(2) return reclaimed land to the lake and recover the littoral zone to its natural state to facilitate increased restoration of macrophytes; and(3) strategically adjust fish populations by reducing benthivorous and filter-feeding fish populations that prey on zooplankton, while enlarging zooplankton populations to control phytoplankton biomass.展开更多
Haustorium formation is the characteristic feature of all parasitic plants and a vital process for successful parasitism.Previous investigations on haustorium initiation and development are constricted to induced proc...Haustorium formation is the characteristic feature of all parasitic plants and a vital process for successful parasitism.Previous investigations on haustorium initiation and development are constricted to induced processes by host-derived signals or synthetic analogs.Spontaneous haustorium formation in the absence of host signals,a process representing an early stage in the evolution of parasitic plants,remains largely unexplored.Lack of fast and frequent formation of spontaneous haustoria greatly hinders full understanding of haustorium formation in root hemiparasites.In this study,seedlings of Pedicularis kansuensis Maxim.,a facultative root hemiparasitic species in Orobanchaceae observed to produce many spontaneous haustoria,were grown in autoclaved water agar in the absence of any known haustoriuminducing stimulants.We aimed to test the temporal and developmental pattern of spontaneous haustorium formation.Also,effects of sucrose supply and root contact on spontaneous haustorium formation were tested.Spontaneous haustoria were observed starting from six days after germination,much earlier than previously reported root hemiparasites.A majority of the spontaneous haustoria formed on lateral roots.Percentage of seedlings with spontaneous haustoria was 28.8% when grown on water agar plates,with a mean of four haustoria per seedling two weeks after germination.Haustorium formation by seedlings grown in water agar amended with 2% sucrose was more than twice of those without sucrose amendment.Singly grown seedlings were able to develop spontaneous haustoria at similar levels as those grown with another conspecific seedling.In view of the fast and abundant formation of spontaneous haustoria,P.kansuensis may be developed as an excellent experimental system in future investigations for unraveling endogenous regulation of haustorium initiation and development in root hemiparasitic plants.展开更多
Harmful cyanobacterial blooms, especially Microcystis blooms, occur worldwide and draw widespread attention. The dynamics of microcystin-producing Microcystis and competition between microcystin-producing Microcystis ...Harmful cyanobacterial blooms, especially Microcystis blooms, occur worldwide and draw widespread attention. The dynamics of microcystin-producing Microcystis and competition between microcystin-producing Microcystis and non-microcystin-producing Microcystis are key to predicting and treating Microcystis blooms. Multiplex qPCR is a useful tool to assess such issues. In this study, we developed multiplex qPCR methods with newly-designed probes and primers for the microcystin-synthesis related genes mcyA and mcyE. We used seven toxic Microcystis strains and four non-toxic Microcystis strains to compare the differences in the ratios of toxic and non-toxic Microcystis in mixed cultures, which were calculated using abundances of the genes mcyA, mcyB, mcyD, mcy E and phycocyanin( PC). We also compared traditional cell counting and multiplex qPCR. Hierarchical clustering and principal component analysis indicated that mcyD was the most suitable mcy gene for quantification in laboratory experiments. mcyB abundances were always higher; we suggest that the amount of toxic Microcystis measured using mcyB might overestimate the actual percentages.展开更多
Implementing conservation actions on-the-ground is not a straightforward process,especially when faced with high scientific uncertainty due to limited available information. This is especially acute in regions of the ...Implementing conservation actions on-the-ground is not a straightforward process,especially when faced with high scientific uncertainty due to limited available information. This is especially acute in regions of the world that harbor many unique species that have not been well studied,such as the alpine zone of the Hengduan Mountains of Northwest Yunnan (NWY),a global biodiversity hotspot and site of The Nature Conservancy’s Yunnan Great Rivers Project. We conducted a quantitative,but rapid regional-level assessment of the alpine flora across NWY to provide a broad-based understanding of local and regional patterns of the alpine flora,the first large-scale analysis of alpine biodiversity patterns in this region. Multivariate analyses were used to classify the major plant community types and link community patterns to habitat variables. Our analysis indicated that most species had small distributions and/or small population sizes. Strong patterns emerged with higher diversity in the more northern mountains,but beta diversity was high,averaging only 10% among sites. The ordinations indicated that elevation and geographic location were the dominant environ-mental gradients underlying the differences in the species composition among communities. The high beta diversity across the alpine of these mountains implies that conservation strategies ultimately will require the protection of large numbers of species over a large geographical area. However,prioritiza-tion should be given to areas where potential payoffs are greatest. Sites with high species richness also have a greater number of endemic species,and,by focusing efforts on these sites,conservation investments would be maximized by protecting the greatest number of unique species.展开更多
Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-gly...Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-glycerophosphate or polyphosphate) phosphorus and at different N:P ratios with 50:1, 30:1, 16:1, 4:1 and 1:4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy(SEM) and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration(2.21×10~6 cells/mL), chlorophyll-a(0.39 pg/cell) and phycocyanin(1.57 pg/cell) quotas and high levels of chlorophyll fluorescence parameters( rETR, E_k, α, φ_(PSⅡ) and F_v/F_m) were obtained when phosphorus was supplied as K_2 HPO_4 at a N:P ratio of 16–30. Organic sources of phosphorus(β-glycerophosphate and polyphosphate) were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate(N:P=1:4) resulted in the oxidative stress and lipid peroxidation of cell membrane(identified by the antioxidant system activity), and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N:P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes(due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases).展开更多
A normalized full-length cDNA library was constructed from the coralloid roots of Cycas debaoensis by the DSN （duplex-specific nuclease） normalization method combined with the SMART （Switching Mechanism At 5＇ end ...A normalized full-length cDNA library was constructed from the coralloid roots of Cycas debaoensis by the DSN （duplex-specific nuclease） normalization method combined with the SMART （Switching Mechanism At 5＇ end of the RNA Transcript） technique. The titer of the original cDNA library was about 1.5 × 10^6 cfu·mL^-1 and the average insertion size was about 1 kb with a high recombination rate （97%）. The 5011 high-quality expressed sequence tags （ESTs） were obtained from 5393 randomly picked cDNA clones. Clustering and assembly of ESTs resulted in 2984 unique sequences, consisting of 618 contigs and 2366 singlets. EST sequence annotation revealed that 2333 and 1901 unigenes were functionally anno- tated in the NCBI non-redundant database and Swiss-Prot protein database, respectively. Functional analysis demonstrated that 1495 （50.1%） unigenes were associated with 4082 Gene Ontology （GO） terms. A total of 847 unigenes were grouped into 22 Cluster of Orthologous Groups （COG） functional categories. Based on the EST dataset, 22 ESTs that encoded putative receptor-like protein kinase （RLK） genes were screened. Furthermore, a total of 94 simple sequence repeats （SSRs） were discovered, of which 20 loci were successfully amplified in C debaoensis. This study is the first EST analysis for the coralloid roots of C debaoensis and provides a valuable genomic resource for novel gene discovery, gene expression and comparative genomics, conservation and management studies as well as applications in C debaoensis and related cycad species.展开更多
Pyropia species grow in the intertidal zone and are cold-water adapted. To date, most of the information about the whole plastid and mitochondrial genomes(ptDNA and mtDNA) of this genus is limited to Northern Hemisphe...Pyropia species grow in the intertidal zone and are cold-water adapted. To date, most of the information about the whole plastid and mitochondrial genomes(ptDNA and mtDNA) of this genus is limited to Northern Hemisphere species. Here, we report the sequencing of the ptDNA and mtDNA of the Antarctic red alga Pyropia endiviifolia using the Illumina platform. The plastid genome(195 784 bp, 33.28% GC content) contains 210 protein-coding genes, 37 tRNA genes and 6 rRNA genes. The mitochondrial genome(34 603 bp, 30.5% GC content) contains 26 protein-coding genes, 25 tRNA genes and 2 rRNA genes. Our results suggest that the organellar genomes of Py. endiviifolia have a compact organization. Although the collinearity of these genomes is conserved compared with other Pyropia species, the genome sizes show significant differences, mainly because of the different copy numbers of rDNA operons in the pt DNA and group II introns in the mtDNA. The other Pyropia species have 2–3 distinct intronic ORFs in their cox 1 genes, but Py. endiviifolia has no introns in its cox 1 gene. This has led to a smaller mtDNA than in other Pyropia species. The phylogenetic relationships within Pyropia were examined using concatenated gene sets from most of the available organellar genomes with both the maximum likelihood and Bayesian methods. The analysis revealed a sister taxa affiliation between the Antarctic species Py. endiviifolia and the North American species Py. kanakaensis.展开更多
文摘The series Variantia Ching et S. H. Wu mainly occur in China and its members are highly variable in morphology. The denomination on this group of Asplenium is very confused in the herbaria. We hop e by means of a biosystematic study to find out their genetic relationships in the reticulate evolution, and to raise a suggestion on their taxonomic treatment. Evidence from cytology, allozyme, morphology, and palynology shows that three ancestor diploids have formed Asplenium sarelii complex comprising 13 members. A. sarelii Hook. should be typified as a diploid. The so-called tetraploid 'A. sarelii' before is an allotetraploid that comes from the doubled hybrid between diploid A. sarelii and A. tenuicaule Hayata, which should be treated as a new species A. wudangense Z. R. Wang et X. Hou. A. pekinense Hance is an autotetraploid that comes from the doubled diploid ancestor A. sarelii. A. lushanense C. Chr., a diploid species and the only ancestor of A. yunnariense group, should not been sunk as a synonym of tetraploid A. yunnariense Franch. Most probably, A. varians Wall. ex Hook. et Grev. is an autotetraploid of A. tenuicaule Hayata. Three new natural tetraploid hybrids and their origins have been found out: they are A. x longmenense ( = A. pekinense x varians), A. x jingyunense ( = A. pekinense x yunnanense) and A. x kidoi ( = A. pekinense x wudangense). Three other new natural triploid hybrids have been found and their origins have been inferred: they are A. X huawuense ( = A. sarelii X wudangense), A. x luyunense ( = A. lushanense x yunnanense) and A. x teniuvaians ( = A. tenuicaule x varians). The method of allozyme comparion combined with cytological observation is employed to reveal the complicated relationships among the members of Asplenium sarelii complex in reticulate evolution and proved to be a highly effective tool to investigate the origin of polyploid and hybrid.
基金supported partly by the Guangzhou Natural Science Foundation (Grant No.2007Z3-EO581)the Guangdong Provincial Natural Science Foundation (Grant No.2007A0200300001-7)+1 种基金the Chinese High-Tech 863 Project (Grant No.2006AA09Z422)the National Natural Science Foundation of China(Grant No. 20572136).
文摘Mangrove endophytic fungus 1893 was isolated from Kandelia candel from an estuarine mangrove on the South China Sea Coast Two new lactones 1893A and 1893B, together with other known compounds, have been isolated from its fermentation broth. To classify the endophyte correctly for further industrial application, a combination of morphological and molecular techniques was used to approach its identity. The endophyte was compared with similar species having trichogynes or trichogyne-like hyphae which apparently fused with an- theridium-like hyphae, and perithecia initials developing from an ascogonial coil surrounded by enveloping hyphae in early developmental stages on pure culture. Further morphological characteristics on host and non-host were used for comparison with similar species when the endophyte was cultivated on leaves ofKandelia candel and Mangifera indica, respectively, which resulted in classifying the endophyte as a Phomopsis specics. The ITS sequence of rDNA was used to infer its phylogenetic relationships with Phomopsis species that resembled the strain in morphology or ecology. Finally, the endophyte was identified as Diaporthe phaseolorum var. sojae based on morphological and molecular evidence. Our study is a first report ofDiaporthephaseolorum var. sojae isolated from mangrove Kandelia candel.
基金supported by the Large-scale Scientific Facilities of the Chinese Academy of Sciences (Grant No: 2017-LSFGBOWS-01)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31000000)the Program of Science and Technology Talents Training of Yunnan Province (2017HA014)
文摘The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics： genome skimming, transcriptome sequencing （RNA- seq）, restriction site associated DNA sequencing （RAD-Seq）, and targeted capture （Hyb-seq）. Of these four genome-partitioning approaches, targeted capture （especially Hyb-seq） shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.
基金Supported by the National Key Technology R&D Program of China(No.2011BAC12B01)
文摘Lake Dianchi has undergone accelerated alternations resulting from human activities during the last 50 years, and provides an exceptional example for the study of regime shift in a shallow lake. Focusing on regime shift, we systematically studied and analysed alternations of key components of its ecosystem, including water parameters, phytoplankton and zooplankton biomass, macrophyte composition and fish populations. We found that the shifting course of Lake Dianchi went through three major phases, corresponding to three distinct states: Phase I clean, stable state during the 1950 s; Phase II transitional state during the 1970 s–1980 s; and phase III stable, turbid state since 1993. We analysed all data and samples, identifying the threshold concentrations at which regime shift occurred: total nitrogen(TN) and phosphorus(TP) reaching 1.2 mg/L and 0.13 mg/L, respectively. Results from this study strongly suggest that the increasing input of external nutrients, reclaiming land from the lake and foreign fish invasion were major inducements to the accelerated shift of Lake Dianchi to its turbid, stable state. These findings provide valuable guidelines for potential efforts to reverse this unnatural process in Lake Dianchi. The restoration may need to:(1) thoroughly and accurately identify pollution sources to control and reduce excessive external nutrients flowing into the lake;(2) return reclaimed land to the lake and recover the littoral zone to its natural state to facilitate increased restoration of macrophytes; and(3) strategically adjust fish populations by reducing benthivorous and filter-feeding fish populations that prey on zooplankton, while enlarging zooplankton populations to control phytoplankton biomass.
基金financially supported by the Natural Science Foundation of China(31370512,U1303201,and 31400440)Natural Science Foundation of Yunnan Province(2016FB059)+1 种基金funding for Airong Li from The Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Young Academic and Technical Leader Raising Foundation of Yunnan Province(2014HB047)
文摘Haustorium formation is the characteristic feature of all parasitic plants and a vital process for successful parasitism.Previous investigations on haustorium initiation and development are constricted to induced processes by host-derived signals or synthetic analogs.Spontaneous haustorium formation in the absence of host signals,a process representing an early stage in the evolution of parasitic plants,remains largely unexplored.Lack of fast and frequent formation of spontaneous haustoria greatly hinders full understanding of haustorium formation in root hemiparasites.In this study,seedlings of Pedicularis kansuensis Maxim.,a facultative root hemiparasitic species in Orobanchaceae observed to produce many spontaneous haustoria,were grown in autoclaved water agar in the absence of any known haustoriuminducing stimulants.We aimed to test the temporal and developmental pattern of spontaneous haustorium formation.Also,effects of sucrose supply and root contact on spontaneous haustorium formation were tested.Spontaneous haustoria were observed starting from six days after germination,much earlier than previously reported root hemiparasites.A majority of the spontaneous haustoria formed on lateral roots.Percentage of seedlings with spontaneous haustoria was 28.8% when grown on water agar plates,with a mean of four haustoria per seedling two weeks after germination.Haustorium formation by seedlings grown in water agar amended with 2% sucrose was more than twice of those without sucrose amendment.Singly grown seedlings were able to develop spontaneous haustoria at similar levels as those grown with another conspecific seedling.In view of the fast and abundant formation of spontaneous haustoria,P.kansuensis may be developed as an excellent experimental system in future investigations for unraveling endogenous regulation of haustorium initiation and development in root hemiparasitic plants.
基金Supported by the National Natural Science Foundation of China(Nos.31370418,41561144008)the Jiangxi Water Science and Technology Fund(No.KT201602)the State Key Laboratory of Freshwater Ecology and Biotechnology(No.2016FBZ07)
文摘Harmful cyanobacterial blooms, especially Microcystis blooms, occur worldwide and draw widespread attention. The dynamics of microcystin-producing Microcystis and competition between microcystin-producing Microcystis and non-microcystin-producing Microcystis are key to predicting and treating Microcystis blooms. Multiplex qPCR is a useful tool to assess such issues. In this study, we developed multiplex qPCR methods with newly-designed probes and primers for the microcystin-synthesis related genes mcyA and mcyE. We used seven toxic Microcystis strains and four non-toxic Microcystis strains to compare the differences in the ratios of toxic and non-toxic Microcystis in mixed cultures, which were calculated using abundances of the genes mcyA, mcyB, mcyD, mcy E and phycocyanin( PC). We also compared traditional cell counting and multiplex qPCR. Hierarchical clustering and principal component analysis indicated that mcyD was the most suitable mcy gene for quantification in laboratory experiments. mcyB abundances were always higher; we suggest that the amount of toxic Microcystis measured using mcyB might overestimate the actual percentages.
文摘Implementing conservation actions on-the-ground is not a straightforward process,especially when faced with high scientific uncertainty due to limited available information. This is especially acute in regions of the world that harbor many unique species that have not been well studied,such as the alpine zone of the Hengduan Mountains of Northwest Yunnan (NWY),a global biodiversity hotspot and site of The Nature Conservancy’s Yunnan Great Rivers Project. We conducted a quantitative,but rapid regional-level assessment of the alpine flora across NWY to provide a broad-based understanding of local and regional patterns of the alpine flora,the first large-scale analysis of alpine biodiversity patterns in this region. Multivariate analyses were used to classify the major plant community types and link community patterns to habitat variables. Our analysis indicated that most species had small distributions and/or small population sizes. Strong patterns emerged with higher diversity in the more northern mountains,but beta diversity was high,averaging only 10% among sites. The ordinations indicated that elevation and geographic location were the dominant environ-mental gradients underlying the differences in the species composition among communities. The high beta diversity across the alpine of these mountains implies that conservation strategies ultimately will require the protection of large numbers of species over a large geographical area. However,prioritiza-tion should be given to areas where potential payoffs are greatest. Sites with high species richness also have a greater number of endemic species,and,by focusing efforts on these sites,conservation investments would be maximized by protecting the greatest number of unique species.
基金Supported by the National Key R&D Program of China(No.2016YFC0502700)the Major Program of National Social Science Foundation of China(No.14ZDB140)the National Science Foundation(USA)(Nos.IOS1451528,DEB1240870)
文摘Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-glycerophosphate or polyphosphate) phosphorus and at different N:P ratios with 50:1, 30:1, 16:1, 4:1 and 1:4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy(SEM) and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration(2.21×10~6 cells/mL), chlorophyll-a(0.39 pg/cell) and phycocyanin(1.57 pg/cell) quotas and high levels of chlorophyll fluorescence parameters( rETR, E_k, α, φ_(PSⅡ) and F_v/F_m) were obtained when phosphorus was supplied as K_2 HPO_4 at a N:P ratio of 16–30. Organic sources of phosphorus(β-glycerophosphate and polyphosphate) were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate(N:P=1:4) resulted in the oxidative stress and lipid peroxidation of cell membrane(identified by the antioxidant system activity), and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N:P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes(due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases).
基金supported by the Grant(201522)from Shenzhen Urban Management
文摘A normalized full-length cDNA library was constructed from the coralloid roots of Cycas debaoensis by the DSN （duplex-specific nuclease） normalization method combined with the SMART （Switching Mechanism At 5＇ end of the RNA Transcript） technique. The titer of the original cDNA library was about 1.5 × 10^6 cfu·mL^-1 and the average insertion size was about 1 kb with a high recombination rate （97%）. The 5011 high-quality expressed sequence tags （ESTs） were obtained from 5393 randomly picked cDNA clones. Clustering and assembly of ESTs resulted in 2984 unique sequences, consisting of 618 contigs and 2366 singlets. EST sequence annotation revealed that 2333 and 1901 unigenes were functionally anno- tated in the NCBI non-redundant database and Swiss-Prot protein database, respectively. Functional analysis demonstrated that 1495 （50.1%） unigenes were associated with 4082 Gene Ontology （GO） terms. A total of 847 unigenes were grouped into 22 Cluster of Orthologous Groups （COG） functional categories. Based on the EST dataset, 22 ESTs that encoded putative receptor-like protein kinase （RLK） genes were screened. Furthermore, a total of 94 simple sequence repeats （SSRs） were discovered, of which 20 loci were successfully amplified in C debaoensis. This study is the first EST analysis for the coralloid roots of C debaoensis and provides a valuable genomic resource for novel gene discovery, gene expression and comparative genomics, conservation and management studies as well as applications in C debaoensis and related cycad species.
基金Supported by the National Natural Science Foundation of China(No.31372517)the Scientific and Technological Innovation Project Financially Supported by Qingdao National Laboratory for Marine Science and Technology(No.2015ASKJ02)the National Infrastructure of Fishery Germplasm Resources(No.2016DKA30470)
文摘Pyropia species grow in the intertidal zone and are cold-water adapted. To date, most of the information about the whole plastid and mitochondrial genomes(ptDNA and mtDNA) of this genus is limited to Northern Hemisphere species. Here, we report the sequencing of the ptDNA and mtDNA of the Antarctic red alga Pyropia endiviifolia using the Illumina platform. The plastid genome(195 784 bp, 33.28% GC content) contains 210 protein-coding genes, 37 tRNA genes and 6 rRNA genes. The mitochondrial genome(34 603 bp, 30.5% GC content) contains 26 protein-coding genes, 25 tRNA genes and 2 rRNA genes. Our results suggest that the organellar genomes of Py. endiviifolia have a compact organization. Although the collinearity of these genomes is conserved compared with other Pyropia species, the genome sizes show significant differences, mainly because of the different copy numbers of rDNA operons in the pt DNA and group II introns in the mtDNA. The other Pyropia species have 2–3 distinct intronic ORFs in their cox 1 genes, but Py. endiviifolia has no introns in its cox 1 gene. This has led to a smaller mtDNA than in other Pyropia species. The phylogenetic relationships within Pyropia were examined using concatenated gene sets from most of the available organellar genomes with both the maximum likelihood and Bayesian methods. The analysis revealed a sister taxa affiliation between the Antarctic species Py. endiviifolia and the North American species Py. kanakaensis.
