To establish a micropropagation system of three Laurencia complex species （Laurencia okamurai, Laurencia tristicha, and Chondrophvcus undulatus） by tissue culture techniques, we studied the regeneration characterist...To establish a micropropagation system of three Laurencia complex species （Laurencia okamurai, Laurencia tristicha, and Chondrophvcus undulatus） by tissue culture techniques, we studied the regeneration characteristics and optimal culture conditions of axenic algal fragments cultured on solid medium and in liquid medium. Regeneration structures were observed and counted regularly under a reverse microscope to investigate the regeneration process, polarity and optimal illumination, and temperature and salinity levels. The results show that in most cultures of the three species, we obtained bud regeneration on solidified medium with 0.5% agar and in liquid medium. Rhizoid-like regeneration was filamentous and developed from the lower cut surface of fragments in L. okamurai, but was discoid and developed from the apical back side of bud regeneration in L. tristicha and C. undulatus. Regeneration polarity was localized to the apical part of algal fronds in all three species, and on fragments cut from the basal part of algae buds could develop from both the upper and the lower cut surfaces. Buds could develop from both the medullary and the cortical portions in L. okamurai and C. undulatus, while in L. tristicha, buds only emerged from the cortex. The optimal culture conditions for L. okamurai were 4 500 lx, 20℃ and 35 （salinity）; for C. undulatus, 4 500 lx, 20℃ and 30; and for L. tristicha, 4 500 lx, 25℃ and 30.展开更多
Flavobacterium columnare is the pathogenic agent of columnaris disease in aquaculture. Using a recently developed gene deletion strategy, two genes that encode the Glyco hydro_19 domain （GH19 domain） containing prot...Flavobacterium columnare is the pathogenic agent of columnaris disease in aquaculture. Using a recently developed gene deletion strategy, two genes that encode the Glyco hydro_19 domain （GH19 domain） containing proteins, ghd-1 and ghd-2, were deleted separately and together from the F. columnare G4 wild type strain. Surprisingly, the single-, Aghd-1 and Aghd-2, and double-gene mutants, Aghd-1 Aghd-2, all had rhizoid and non-rhizoid colony morphotypes, which we named Aghd-1, Aghd-2, Aghd-1 Aghd-2, and NAghd-1, NAghd-2, and NAghd-1 Aghd-2. However, chitin utilization was not detected in either these mutants or in the wild type. Instead, skimmed milk degradation was observed for the mutants and the wild type; the non-rhizoid strain NAghd-2 exhibited higher degradation activity as revealed by the larger transparent circle on the skimmed milk plate. Using zebrafish as the model organism, we found that non-rhizoid mutants had higher LDs0 values and were less virulent because zebrafish infected with these survived longer. Transcriptome analysis between the non-rhizoid and rhizoid colony morphotypes of each mutant, i.e., NAghd-1 versus （vs） Aghd-1, NAghd-2 vs Aghd-2, and NAghd-1 Aghd-2 vs Aghd-1 Aghd-2, revealed a large number of differentially expressed genes, among which 39 genes were common in three of the pairs compared. Although most of these genes encode hypothetical proteins, a few molecules such as phage tail protein, rhs element Vgr protein, thiol-activated cytolysin, and TonB-dependent outer membrane receptor precursor, expression of which was down-regulated in non-rhizoid mutants but up-regulated in rhizoid mutants, may play a role F. columnare virulence.展开更多
Algae of the order Laminariales represent main seaweed resource of Russia, Most important commercial species formerly belonged to Laminaria Lamoroux. However, taxonomic revision of this genus and resurrection of Sacch...Algae of the order Laminariales represent main seaweed resource of Russia, Most important commercial species formerly belonged to Laminaria Lamoroux. However, taxonomic revision of this genus and resurrection of Saccharina Stackhouse based on genetic studies resulted in transfer of most Laminaria species to Saccharina. At the Russian Pacific coasts Saccharina now includes 10 species, while only three species for sure represent Laminaria： L. longipes Bory de Saint-Vincent, L. solidungula J. Agardh, L. yezoensis Miyabe, their placement within Laminaria is supported by genetic data. All examined Far Eastern species of Saccharina are noticed to possess haptera in the form of rhizoids, whereas members of Laminaria have disk-like holdfasts （L. solidungula, L. yezoensis）, or creeping rhizomes （L. longipes）. Three unstudied genetically endemics from the Sea of Okhotsk： L. appressirhiza Petrov et Vozzhinskaya, L. inclinatorhiza Petrov et Vozzhinskaya, L. multiplicata Petrov et Suchovejeva, are still left within Laminaria, but they have rhizoids, so most probably belong to Saccharina. This morphological criterion is inapplicable to Atlantic Laminaria since the type species L. digitata （Hudson） Lamouroux has rhizoids.展开更多
Fucoxanthin was extracted from the intact rhizoid of Laminariajaponica Aresch with dimethyl sulfoxide （DMSO）, and then recovered from the DMSO extract by partitioning into ethyl acetate and subsequent evaporation. S...Fucoxanthin was extracted from the intact rhizoid of Laminariajaponica Aresch with dimethyl sulfoxide （DMSO）, and then recovered from the DMSO extract by partitioning into ethyl acetate and subsequent evaporation. Some isolation conditions such as solvent volume and extraction time were screened. The quantity and quality of the extracted fucoxanthin were determined by spectral analysis （absorption spectra and fluorescence emission spectra）. The results indicated that： （1） the average total content of fucoxanthin was 122.1μg in 1 g of fresh L. japonica rhizoid; （2） in comparison with the widely used organic solvent, acetone, DMSO was much more effective for the extraction of fucoxanthin; （3） both DMSO volume and extraction time influenced extraction efficiency such as the recovery rate and purity of fucoxanthin （1 g of fresh L. japonica rhizoid treated with 4 mL DMSO for 60 min, yielded 〉 88% of the total fucoxanthin with purity 0.63）; （4） when （NH4）2SO4 concentration was in the range of 0.5-1.0 mol/L, the pigments rapidly and entirely moved from DMSO into the ethyl acetate phase; （5） the ethyl acetate and DMSO were recycled using a rotary evaporator.展开更多
Newly regenerated thalli were used to study the phototropism of Bryopsis hypnoides Lamouroux under different qualities of light. Positive phototropism in the thalli and negative phototropiam In the rhizoida of B. hypn...Newly regenerated thalli were used to study the phototropism of Bryopsis hypnoides Lamouroux under different qualities of light. Positive phototropism in the thalli and negative phototropiam In the rhizoida of B. hypnoides were investigated and analyzed in terms of bending. Both thaiii and rhlzoids developed from thallus segments exhibited typical tip growth, and their photoreceptive sites for phototroplam were also restricted to the apical hemisphere. The bending curvature of rhizoids and thalli were determined with unilateral lights at various wavelengths and different fluence rates after a fixed duration of Illumination. The trends of bending from the rhizoid and thallus were coincident, which showed that the action spectrum had a large range, from ultraviolet radiation （366.5 nm） to green light （524 nm）. Based on the bending curvatures, blue light had the highest efficiency, while the efficiency of longer wavelengths （〉500 nm） was significantly lower. External Ca^2＋ had no effect on the bending curvature of thalli and rhlzolda. Blue light （440 nm） induced thallus branching from rhizoids, while red light （650 nm） had no such effect. Fast-occurring chloroplast accumulation In the outermost cytoplasmic layer of the blue light （440 nm）-Irradiated region In the rhizoid was observed, from which protrusions （new thalli） arose after 4 h of the onset of illumination, and this action was thought to be driven by the dynamics of actin microfilamenta.展开更多
基金Supported by the fund from Jiangsu Key Laboratory of Marine Biotechnology (No. 2006HS006)Huaihai Institute of Technology, Lianyungang, China211-Project Funding of Soochow University (No. 14134908)
文摘To establish a micropropagation system of three Laurencia complex species （Laurencia okamurai, Laurencia tristicha, and Chondrophvcus undulatus） by tissue culture techniques, we studied the regeneration characteristics and optimal culture conditions of axenic algal fragments cultured on solid medium and in liquid medium. Regeneration structures were observed and counted regularly under a reverse microscope to investigate the regeneration process, polarity and optimal illumination, and temperature and salinity levels. The results show that in most cultures of the three species, we obtained bud regeneration on solidified medium with 0.5% agar and in liquid medium. Rhizoid-like regeneration was filamentous and developed from the lower cut surface of fragments in L. okamurai, but was discoid and developed from the apical back side of bud regeneration in L. tristicha and C. undulatus. Regeneration polarity was localized to the apical part of algal fronds in all three species, and on fragments cut from the basal part of algae buds could develop from both the upper and the lower cut surfaces. Buds could develop from both the medullary and the cortical portions in L. okamurai and C. undulatus, while in L. tristicha, buds only emerged from the cortex. The optimal culture conditions for L. okamurai were 4 500 lx, 20℃ and 35 （salinity）; for C. undulatus, 4 500 lx, 20℃ and 30; and for L. tristicha, 4 500 lx, 25℃ and 30.
基金Supported by the Chinese Academy of Sciences(No.XDA08010207)the National Key Technology R&D Program of China(No.2012BAD25B02)the State Key Laboratory of Freshwater Ecology and Biotechnology(No.2016FBZ04)
文摘Flavobacterium columnare is the pathogenic agent of columnaris disease in aquaculture. Using a recently developed gene deletion strategy, two genes that encode the Glyco hydro_19 domain （GH19 domain） containing proteins, ghd-1 and ghd-2, were deleted separately and together from the F. columnare G4 wild type strain. Surprisingly, the single-, Aghd-1 and Aghd-2, and double-gene mutants, Aghd-1 Aghd-2, all had rhizoid and non-rhizoid colony morphotypes, which we named Aghd-1, Aghd-2, Aghd-1 Aghd-2, and NAghd-1, NAghd-2, and NAghd-1 Aghd-2. However, chitin utilization was not detected in either these mutants or in the wild type. Instead, skimmed milk degradation was observed for the mutants and the wild type; the non-rhizoid strain NAghd-2 exhibited higher degradation activity as revealed by the larger transparent circle on the skimmed milk plate. Using zebrafish as the model organism, we found that non-rhizoid mutants had higher LDs0 values and were less virulent because zebrafish infected with these survived longer. Transcriptome analysis between the non-rhizoid and rhizoid colony morphotypes of each mutant, i.e., NAghd-1 versus （vs） Aghd-1, NAghd-2 vs Aghd-2, and NAghd-1 Aghd-2 vs Aghd-1 Aghd-2, revealed a large number of differentially expressed genes, among which 39 genes were common in three of the pairs compared. Although most of these genes encode hypothetical proteins, a few molecules such as phage tail protein, rhs element Vgr protein, thiol-activated cytolysin, and TonB-dependent outer membrane receptor precursor, expression of which was down-regulated in non-rhizoid mutants but up-regulated in rhizoid mutants, may play a role F. columnare virulence.
文摘Algae of the order Laminariales represent main seaweed resource of Russia, Most important commercial species formerly belonged to Laminaria Lamoroux. However, taxonomic revision of this genus and resurrection of Saccharina Stackhouse based on genetic studies resulted in transfer of most Laminaria species to Saccharina. At the Russian Pacific coasts Saccharina now includes 10 species, while only three species for sure represent Laminaria： L. longipes Bory de Saint-Vincent, L. solidungula J. Agardh, L. yezoensis Miyabe, their placement within Laminaria is supported by genetic data. All examined Far Eastern species of Saccharina are noticed to possess haptera in the form of rhizoids, whereas members of Laminaria have disk-like holdfasts （L. solidungula, L. yezoensis）, or creeping rhizomes （L. longipes）. Three unstudied genetically endemics from the Sea of Okhotsk： L. appressirhiza Petrov et Vozzhinskaya, L. inclinatorhiza Petrov et Vozzhinskaya, L. multiplicata Petrov et Suchovejeva, are still left within Laminaria, but they have rhizoids, so most probably belong to Saccharina. This morphological criterion is inapplicable to Atlantic Laminaria since the type species L. digitata （Hudson） Lamouroux has rhizoids.
文摘Fucoxanthin was extracted from the intact rhizoid of Laminariajaponica Aresch with dimethyl sulfoxide （DMSO）, and then recovered from the DMSO extract by partitioning into ethyl acetate and subsequent evaporation. Some isolation conditions such as solvent volume and extraction time were screened. The quantity and quality of the extracted fucoxanthin were determined by spectral analysis （absorption spectra and fluorescence emission spectra）. The results indicated that： （1） the average total content of fucoxanthin was 122.1μg in 1 g of fresh L. japonica rhizoid; （2） in comparison with the widely used organic solvent, acetone, DMSO was much more effective for the extraction of fucoxanthin; （3） both DMSO volume and extraction time influenced extraction efficiency such as the recovery rate and purity of fucoxanthin （1 g of fresh L. japonica rhizoid treated with 4 mL DMSO for 60 min, yielded 〉 88% of the total fucoxanthin with purity 0.63）; （4） when （NH4）2SO4 concentration was in the range of 0.5-1.0 mol/L, the pigments rapidly and entirely moved from DMSO into the ethyl acetate phase; （5） the ethyl acetate and DMSO were recycled using a rotary evaporator.
基金Supported by the National Natural Science Foundation of China(30170499, 40476059,and 39890390)the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-211)the Hi-Tech Research and Development(863) Program of China(2004AA603220)
文摘Newly regenerated thalli were used to study the phototropism of Bryopsis hypnoides Lamouroux under different qualities of light. Positive phototropism in the thalli and negative phototropiam In the rhizoida of B. hypnoides were investigated and analyzed in terms of bending. Both thaiii and rhlzoids developed from thallus segments exhibited typical tip growth, and their photoreceptive sites for phototroplam were also restricted to the apical hemisphere. The bending curvature of rhizoids and thalli were determined with unilateral lights at various wavelengths and different fluence rates after a fixed duration of Illumination. The trends of bending from the rhizoid and thallus were coincident, which showed that the action spectrum had a large range, from ultraviolet radiation （366.5 nm） to green light （524 nm）. Based on the bending curvatures, blue light had the highest efficiency, while the efficiency of longer wavelengths （〉500 nm） was significantly lower. External Ca^2＋ had no effect on the bending curvature of thalli and rhlzolda. Blue light （440 nm） induced thallus branching from rhizoids, while red light （650 nm） had no such effect. Fast-occurring chloroplast accumulation In the outermost cytoplasmic layer of the blue light （440 nm）-Irradiated region In the rhizoid was observed, from which protrusions （new thalli） arose after 4 h of the onset of illumination, and this action was thought to be driven by the dynamics of actin microfilamenta.
