We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identifie...We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as A lteromonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that： （1）The blades of L.japonica exhibited symptoms of lesion,bleaching and deteriortion when infected by the bacterium. and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species （ROS） generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde （MDA） and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. （2） The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase （SOD） and catalase （CAT） increased greatly when infected by the bacterium, but glutathione peroxidase （Gpx） and ascorbate peroxidase （APX） did not exhibit active responses to the bacterium throughout the experiment. （3） The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.展开更多
For the population genetics analysis of the naturally grown brown seaweed Laminaria japonica （Laminariales,Phaeophyta） sampled from Dalian,Yantai,Weihai,Rongcheng and Qingdao in China,ten primers were employed to pr...For the population genetics analysis of the naturally grown brown seaweed Laminaria japonica （Laminariales,Phaeophyta） sampled from Dalian,Yantai,Weihai,Rongcheng and Qingdao in China,ten primers were employed to produce 88 bands as revealed by randomly amplified polymorphic DNA （RAPD） markers,and all these bands were polymorphic.According to these band patterns,there were 94 distinct phenotypes occurred in 100 samples indicating the high heterozygosity of this kelp.Dalian population samples showed the highest percentage of polymorphism （71.67%）,and also the higher diversity estimated on the basis of the Shannon’s index （8.498）,suggesting that this population could be chosen as the best resource for genetic breeding.The highest diversity of Yantai population possibly resulted from the introduction of L.longissima used for interspecific cross breeding with L.japonica cultivated in China.From Dalian southwards to Qingdao,the genetic variation of the five populations became less with a decrease in latitude,possibly due to the natural selection especially of high temperature.The genetic distance （Φ ST values） of the five populations was a little significantly correlated with the geographical distance （r=0.496） at P =0.05 by Mantel’s test.Weihai,Rongcheng and Yantai populations were closely grouped genetically together by Neighbor-joining cluster analysis probably in that the dispersal of the kelp by propagules more easily occurring in the range of relatively short distance.The analysis of molecular variance （AMOVA） also demonstrated that the relatively higher variation occurred among populations （71.49%） at an extremely significant level （P 0.000 1）.All these evidence showed that there was a relatively distinct genetic differentiation among the sampled kelp populations,and L.japonica grown in China was also rather heterozygous in heredity.展开更多
In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ...In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A^2 + 2490.79B^2+873.04C^2. The equation regression coefficient value(R^2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R^2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL^(-1), which was fourfold higher than initial polysaccharide.展开更多
The parthenogenesis and natural doubling of chromosomes in wild type female gametophytes of Laminaria japonica were studied. The results indicate that not all the female gametophytes from the wild type hybrid parent c...The parthenogenesis and natural doubling of chromosomes in wild type female gametophytes of Laminaria japonica were studied. The results indicate that not all the female gametophytes from the wild type hybrid parent can propagate through parthenogenesis. Most parthenosporophytes can mature, their spores germinate into gametophytes, the latter then developed into female sporophytes. To form these parthenosporophytes the natural doubling of chromosomes occurred mainly at the first and second cell divisions of the spores. It is thus considered that the parthenogenesis of L. japonica is inheritable and the relative genes link closely with the genes controlling the natural doubling of chromosomes and the female determination.展开更多
Laminaria （Saccharina） is one of the economic important seaweeds. Through sequence analysis of 4 099 ESTs from Laminaria （971 were generated from our own cDNA laboratories and 3 128 were downloaded from updated EST...Laminaria （Saccharina） is one of the economic important seaweeds. Through sequence analysis of 4 099 ESTs from Laminaria （971 were generated from our own cDNA laboratories and 3 128 were downloaded from updated EST databases） with SSRIT software, two hundred and fifty-four SSRs in 206 ESTs were found. From the 254 SSRs, sixty-three SSR primer-pairs were designed. In order to test their practicability, the 63 primer-pairs were tested in commonly used SSR reaction conditions using 12 Laminara DNA samples as templates. The results show that 23 SSR primer-pairs gave good amplification patterns on most （more than 80%） of the 12 Laminara DNA templates. Genetic diversity study of 12 Laminaria lines, which were widely used in breeding and economic cultivation in China, was performed based on the obtained SSR data.展开更多
This study on the effects of ultrasonic treatment on female gametophytes of Laminariajaponica showed that:1. Ultrasonic treatment had shortening effect on filaments of female gametophytes. Within certainperiod of time...This study on the effects of ultrasonic treatment on female gametophytes of Laminariajaponica showed that:1. Ultrasonic treatment had shortening effect on filaments of female gametophytes. Within certainperiod of time, the average length of filamentous female gametophytes was shortened.2. Ultrasonic treatment had emptying effect on cells. The number of empty cells increased with timeof treatment. Ultrasonic treatment had harmful effect on cells.3. Ultrasonic treatment could break down cell walls. The combination of frequency of 20 kHz, out-put of 15 W, 40 s and 60 s of treatment was best for this purpose. After ultrasonic treatment, the regner-ation of female gametophytes into sporophytes was effected. Female gametophytes could not recover aftertoo long period of treatment.展开更多
After continuous breeding gametophyte of Laminaria, then breaking protonema, heterosis seedling is got by bilineal hybridization. The result shows that the weight-increasing rate of female and male gametophyte clone c...After continuous breeding gametophyte of Laminaria, then breaking protonema, heterosis seedling is got by bilineal hybridization. The result shows that the weight-increasing rate of female and male gametophyte clone cells are 14.03% and 13.87%, after 16 d crossbreeding, the rate of ovulation is up to100%; the length of juvenile sporophyte after 40 d breeding is 2-3 cm. By farming on the sea, a hybrid combination is primarily screened.展开更多
In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and...In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and half months. In such a case, sometimes the sporelings died within a few days due to destructive diseases. In Order to overcome the mentioned problems, a new sporeling culture technique, the clone technique, is developed. The method includes three stead: (1) Gametophyte clone culture. The spores and the gametophytes are cloned in flasks under favorable environments. (2) Sporeling cul ture. Male and female clones are crushed and spread onto a frame to allow the gametophytes to attach to the substrata. The frames are cultured in tanks, and the sporophytes reach 1 cm in length within one and a half months. (3) Outgrowing of the plant. The frames are put in the open sea when seawater temperature decreased to 20℃. After one month, the sporelings are large enough to be transplanted. It is concluded that the clone technique has the following advantages: (1)Large amount of clones can be produced in a short period of time. (2) Clone seeding method makes it free from the biological rhythm, one can seed the plant anytime all the year round. (3) It takes only one and a half months to complete the process of sporeling cultivation in the greenhouse. At present, this technique is used in the breeding of new strains of Laminaria.展开更多
In the past two decades, many studies have focused on the classification within genus Laminaria, ultimately trying to divide it into two subgroups or genera： Laminaria and Saccharina. A significant debate still surro...In the past two decades, many studies have focused on the classification within genus Laminaria, ultimately trying to divide it into two subgroups or genera： Laminaria and Saccharina. A significant debate still surrounds the question of its division, as the conflicting phylogenetic hypotheses that have resulted from the classification studies are based on different taxon sampling, molecular markers, or analysis methods. It is aimed at elucidate the molecular phylogeny within Laminaria and Saccharina. The nine species of Lami- nariales are sampled from northern Asia and Europe, and 23 new sequences in the nuclear, plastid, and mitochondrial genomes are determined to identify their taxonomic status. The phylogenetic analyses of 71 species are performed, including representatives from six of the seven families of the order Laminariales, based on three separate data sets. An evidence is provided to strongly support a clear split that maintains the two recognized genera, Laminaria and Saccharina, with Laminaria appearing to be the ancestor group. Further, analyses indicate that all taxa in Saccharina and Laminaria did not form a monophyletic lineage, instead Laminariaceae and Lessoniaceae grouped together interlacedly, and Costariaceae appeared as the sister taxon of the Lessoniaceae-Laminariaceae clade. In the phylogenetic analysis, mitochondrial c oxi- dase I （COI） sequences appeared to be the most credible molecular marker which was more befitting than nuclear encoded internal transcribed spacer （ITS） and plastid encoded rbcL for establishment of Laminariales systematics. It is the most comprehensive phylogeny of the order Laminariales, and contributes to an enhanced understanding and estimation of the phylogenetic relationships for the economically important seaweeds, Laminaria and Saccharina.展开更多
A genetic transformation model for the seaweed Laminaria japonica mainly includesthe following aspects:1. The method to introduce foreign genes into the kelp, L. japonicaBiolistic bombardment has been proved to be an ...A genetic transformation model for the seaweed Laminaria japonica mainly includesthe following aspects:1. The method to introduce foreign genes into the kelp, L. japonicaBiolistic bombardment has been proved to be an effective method to bombard foreign DNA throughcell walls into intact cells of both sporophytes and gametophytes. The expression of cat and lacZ was de-tected in regenerated sporophytes, which suggests that this method could induce the integration of for-eign genes. 2. Promoters to drive gene expressionThe CaMV35S promoter was first used by us to induce the expression of GUS gene in brown algae.But results of further studies suggested that CaMV35S could be a tissue-specific promoter. Our use ofSV40 promoter resulted in both transient and stable expression of lacZ and cat in sporophytes or gameto-phytes. No GUS or LacZ background was found in either sporophytes or gametophytes.3. The regeneration route of transgenic kelpThe regeneration efficiency of explants is still very low. By using female gametophytes as gene hostsand parthenogenesis as regeneration route, CAT activity and LacZ activity were detected in regeneratedsporophytes of parthenogenetic kelp.4. The way to select transgenic kelpResults of sensitivity tests showed that kelp was only sensitive to chloramphenicol and hygromycin a-mong many antibiotics. The regenerated sporophytes by parthenogenesis were more sensitive to hygromycinthan to chloramphenicol. Resistant kelp was created by transforming female gametophytes with pSV40-CAT and stimulating parthenogenesis followed by selection in medium with lethal concentration of chloram-phenicol,.5. Safety consideration of transgenic kelp1) L. japonica was originally introduced from Japan. In China it is a cultured population. The pos-sibility of its negative impact on natural populations is very low. 2) The vectors and target genes used fortransformation should be restricted In order to avoid any negative impacts on human health and environ-ment. 3)Specially devised containers (3. 6 L, made of 200 μm membrane) were used to ensure that thekelp cannot escape or be eaten by marine animals. 4) To avoid the release of spores, it is very necessaryto harvest the kelp at suitable age before the sporangium forms.展开更多
Four media (PESI solid, MS liquid, MS solid and ASP-C-I solid medium) were usedto induce callus from excised tissues of the kelp Laminaria japonica. Only PESI solid medium and MSsolid medium produced calli. Modified M...Four media (PESI solid, MS liquid, MS solid and ASP-C-I solid medium) were usedto induce callus from excised tissues of the kelp Laminaria japonica. Only PESI solid medium and MSsolid medium produced calli. Modified MS solid medium supplemented with mannitol (3%, W/V), yeastextract (0.1%, W/V), VB2(0. 5 mg/ml), VB12(0.5 mg/ml), kinetin (0. 108 μg/ml) and NAA(1.860μg/ml) showed much better effect on callus induction than non-modified MS solid medium. After24 days of induction 75 .5% of tissues in PESI solid medium showed callus formation. For modified MSsolid medium, after three months of induction 67. 3% of tissues dedifferentiated into calli. No calluscould be found after five months of induction in either MS liquid or ASP-C-I solid medium. When calliwere squashed and cultured in N-P enriched autoclaved seawater, MS liquld medium and ASP12-NTAliquid medium (both modified with kelp extract), differentiation of cells and regeneration of sporophyteswere only observed in ASP12-NTA medium supplemented with kelp extract. Gametophyte-like filamentsformed first, then eggs were released. It was suggested that sporophyte formation could be a process ofparthenogenesis. Sterilization techniques in tissue culture of L. japonica were also tested in this study.展开更多
Five fucoidan fractions from Laminaria japonica with different sulfate content and molecular weight were prepared by anion-exchange chromatography and mild acid hydrolysis. Their antioxidant effects on azo radicals 2-...Five fucoidan fractions from Laminaria japonica with different sulfate content and molecular weight were prepared by anion-exchange chromatography and mild acid hydrolysis. Their antioxidant effects on azo radicals 2-2＇-Azobis （2-amidinopropane） dihydrochloride （AAPH） induced oxidation of human low-density lipoprotein （LDL） were evaluated by monitoring cholesteryl ester hydroperoxides （CHL-OOH） formation kinetics through reverse-phase high performance liquid chromatography （RP-HPLC） analysis. Fucoidan F - C with a low molecular mass of 2 000 ～8 000 and a sulfate content of 24.3% had much stronger protective antioxidant effect than other four fucoidan fractions on the hydrophilic radical AAPH induced LDL oxidation. However, the highly sulfated fucoidan fraction L - B with a molecular mass of 20 000 was completely ineffective in protecting LDL from the AAPH induced oxidation. The results suggested that both molecular mass and sulfate content of fucoidan played very important roles in their effects on the AAPH induced LDL oxidation.展开更多
Experiments with Lamnaria japonica were conducted in Meidao Bay and Pier Bay,Qingdao,China,Nitrogen-starved plants were fertilized intermittently with 7.1 mM NH4-N solution for 1 hour at 3 day intervals, after which c...Experiments with Lamnaria japonica were conducted in Meidao Bay and Pier Bay,Qingdao,China,Nitrogen-starved plants were fertilized intermittently with 7.1 mM NH4-N solution for 1 hour at 3 day intervals, after which chlorophyll a, fucoxanthin, chlorophyll c and B-carotene contents were analyzed. Photosynthetic and growth rates of plants and nitrogen content of seawater were determined. Photosynthetic and growth rates of the nitrogen-enriched plants were higher than those of the controls, and their contents of chlorophyll a, fucoxanthin, chlorophyll c and B-carotene were 1.65,0.67,0.33 and 0.06 mg . dm-2 respectively, or 2.46,2.03,1.86 and 1.81 times those of the controls. The ratio of fiicoxanthin to chlorophyll a in nitrogen-enriched plants was lower than that of the controls. Normal growth rate of the plants (2 cm.day-1 in length)were reached when the chlorophyll a content exceeded 0.1 mg.g-1 fresh wt., indicating that chlorophyll a content can serve as an indicator of normal growth.Experimental展开更多
The light demands of seaweeds is an interesting and rather complex phenomenon because they depend not only on the species but also on their different development stages. Even different parts of the same plant sometime...The light demands of seaweeds is an interesting and rather complex phenomenon because they depend not only on the species but also on their different development stages. Even different parts of the same plant sometimes have different light demands. Light control is an important procedure at large scale Lamnaria nursery stations in China. Technicians and scientists have different viewpoints on the best method to regulate light. A culture study on Lamnaria japonica starting from zoospores to several centimeter sporophytes to find the optimal and critical irradiance ranges for juvenile Laminaria at different development stages added more knowledge on this aspect. Experiment results show gametophytes can not tolerate irradiance of more than 150uEm-2s-1 while sporophytes can tolerate more than 519 uEm-2s-1. This big difference starts from the very early stage of 1-to 2-celled sporophytes. The biological basis and mechanism of this phenomenon need further research.展开更多
Sori formation in Laminaria japonica was studied from the ecological and physiological point of view. Cutting through the medulla of Laminaria japonica improved the formation of sori.Sori formation under different wat...Sori formation in Laminaria japonica was studied from the ecological and physiological point of view. Cutting through the medulla of Laminaria japonica improved the formation of sori.Sori formation under different water temperature, photoperiod, and light intensity was investigated and total nitrogen and reducible sugar content determined. The result showed that son of L. japonica can be formed in 1-22℃ water in Dalian. No sori were found in water over 23℃. High temperature inhibits the formation of son, but low temperature has no effect. Apparently, light intensity affects the formation of sori, but photoperiod does not. In shallow water L. japonica grows slower but stores dry material faster and forms sori rapidly. In deeper water it grows faster in length but stores dry material slower and the sori formation is slow. Analysis of dry material shows that during sori formation the water content decreases but total nitrogen and total reducible sugar increase.Only when the storage of sugar reaches a展开更多
We extracted a glycoprotein from the brown alga Laminaria japonica (LJGP). We previously demonstrated that LJGP induced apop- tosis in HT-29 colon cancer cells via the Fas- and the mitochondrial signaling pathway, and...We extracted a glycoprotein from the brown alga Laminaria japonica (LJGP). We previously demonstrated that LJGP induced apop- tosis in HT-29 colon cancer cells via the Fas- and the mitochondrial signaling pathway, and cell-cycle arrest. However, its effect on the cell membrane remained unknown. In this study, we identified the involvement of matrix metalloproteinase (MMP), integrin, and Epi- thelial (E)-cadherin in LJGP-induced apoptosis in HT-29 cells. LJGP treatment increased the expression and activity of MMP-2 and MMP-9. Furthermore, LJGP decreased the expression of integrin αν, β3, β5, β6 and E- cadherin. Consistent with a decreased expression of E-cadherin, LJGP inhibited the Wnt signaling pathway. Moreover, activation of downstream molecules of integrin, including focal adhesion kinase (FAK), the Src family of protooncogenic tyrosine kinases, extracellular signal-related kinase (ERK), and phosphatidyl inositol 3 kinase (PI-3K) were also decreased. These findings suggest that LJGP-induced apoptosis of HT-29 cells involves possible ECM disruption and cell detachment, which are executed principally through the activation of MMPs and by a decrease of adhesion molecules, contributing to a down-regulation of the PI-3K, MAPK, and Wnt signaling pathways. Apoptosis induced by ECM disruption or cell detachment is also known as anoikis. We can say that LJGP induces anoikis in HT-29 cells.展开更多
基金The Hi-Tech Research and Development Program (863) of China (Youth Program) (No. 2004AA639770) and the Chinese NationalBasic Research Priorities Program (No. G1999012004)
文摘We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as A lteromonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that： （1）The blades of L.japonica exhibited symptoms of lesion,bleaching and deteriortion when infected by the bacterium. and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species （ROS） generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde （MDA） and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. （2） The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase （SOD） and catalase （CAT） increased greatly when infected by the bacterium, but glutathione peroxidase （Gpx） and ascorbate peroxidase （APX） did not exhibit active responses to the bacterium throughout the experiment. （3） The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.
基金The National Natural Science Foundation of China under grant Nos 39800105 and 30471328the Shanghai Development Foundation of Education under grant No. 98-SG-32Key Discipline of Shanghai Municipal Education Commission (J50701)
文摘For the population genetics analysis of the naturally grown brown seaweed Laminaria japonica （Laminariales,Phaeophyta） sampled from Dalian,Yantai,Weihai,Rongcheng and Qingdao in China,ten primers were employed to produce 88 bands as revealed by randomly amplified polymorphic DNA （RAPD） markers,and all these bands were polymorphic.According to these band patterns,there were 94 distinct phenotypes occurred in 100 samples indicating the high heterozygosity of this kelp.Dalian population samples showed the highest percentage of polymorphism （71.67%）,and also the higher diversity estimated on the basis of the Shannon’s index （8.498）,suggesting that this population could be chosen as the best resource for genetic breeding.The highest diversity of Yantai population possibly resulted from the introduction of L.longissima used for interspecific cross breeding with L.japonica cultivated in China.From Dalian southwards to Qingdao,the genetic variation of the five populations became less with a decrease in latitude,possibly due to the natural selection especially of high temperature.The genetic distance （Φ ST values） of the five populations was a little significantly correlated with the geographical distance （r=0.496） at P =0.05 by Mantel’s test.Weihai,Rongcheng and Yantai populations were closely grouped genetically together by Neighbor-joining cluster analysis probably in that the dispersal of the kelp by propagules more easily occurring in the range of relatively short distance.The analysis of molecular variance （AMOVA） also demonstrated that the relatively higher variation occurred among populations （71.49%） at an extremely significant level （P 0.000 1）.All these evidence showed that there was a relatively distinct genetic differentiation among the sampled kelp populations,and L.japonica grown in China was also rather heterozygous in heredity.
基金the financial support from the National Natural Science Foundation of China (No.21506220)
文摘In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A^2 + 2490.79B^2+873.04C^2. The equation regression coefficient value(R^2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R^2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL^(-1), which was fourfold higher than initial polysaccharide.
文摘The parthenogenesis and natural doubling of chromosomes in wild type female gametophytes of Laminaria japonica were studied. The results indicate that not all the female gametophytes from the wild type hybrid parent can propagate through parthenogenesis. Most parthenosporophytes can mature, their spores germinate into gametophytes, the latter then developed into female sporophytes. To form these parthenosporophytes the natural doubling of chromosomes occurred mainly at the first and second cell divisions of the spores. It is thus considered that the parthenogenesis of L. japonica is inheritable and the relative genes link closely with the genes controlling the natural doubling of chromosomes and the female determination.
基金The National Natural Science Foundation of China under contract No.40776072 and 40606035the National High Technology Research and Development Program(863 Program)of China under contract Nos 2006AA10A412 and 2010AA10A401the Key Projects in the National Science & Technology Pillar Program under contract No.2006BAD01A13
文摘Laminaria （Saccharina） is one of the economic important seaweeds. Through sequence analysis of 4 099 ESTs from Laminaria （971 were generated from our own cDNA laboratories and 3 128 were downloaded from updated EST databases） with SSRIT software, two hundred and fifty-four SSRs in 206 ESTs were found. From the 254 SSRs, sixty-three SSR primer-pairs were designed. In order to test their practicability, the 63 primer-pairs were tested in commonly used SSR reaction conditions using 12 Laminara DNA samples as templates. The results show that 23 SSR primer-pairs gave good amplification patterns on most （more than 80%） of the 12 Laminara DNA templates. Genetic diversity study of 12 Laminaria lines, which were widely used in breeding and economic cultivation in China, was performed based on the obtained SSR data.
文摘This study on the effects of ultrasonic treatment on female gametophytes of Laminariajaponica showed that:1. Ultrasonic treatment had shortening effect on filaments of female gametophytes. Within certainperiod of time, the average length of filamentous female gametophytes was shortened.2. Ultrasonic treatment had emptying effect on cells. The number of empty cells increased with timeof treatment. Ultrasonic treatment had harmful effect on cells.3. Ultrasonic treatment could break down cell walls. The combination of frequency of 20 kHz, out-put of 15 W, 40 s and 60 s of treatment was best for this purpose. After ultrasonic treatment, the regner-ation of female gametophytes into sporophytes was effected. Female gametophytes could not recover aftertoo long period of treatment.
文摘After continuous breeding gametophyte of Laminaria, then breaking protonema, heterosis seedling is got by bilineal hybridization. The result shows that the weight-increasing rate of female and male gametophyte clone cells are 14.03% and 13.87%, after 16 d crossbreeding, the rate of ovulation is up to100%; the length of juvenile sporophyte after 40 d breeding is 2-3 cm. By farming on the sea, a hybrid combination is primarily screened.
基金Key Project, the Ninth Five-Year Plan of China! 96-008-01-02-06Project of Bio-Engineering Center of China! SSTC 96-C01-05-01
文摘In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and half months. In such a case, sometimes the sporelings died within a few days due to destructive diseases. In Order to overcome the mentioned problems, a new sporeling culture technique, the clone technique, is developed. The method includes three stead: (1) Gametophyte clone culture. The spores and the gametophytes are cloned in flasks under favorable environments. (2) Sporeling cul ture. Male and female clones are crushed and spread onto a frame to allow the gametophytes to attach to the substrata. The frames are cultured in tanks, and the sporophytes reach 1 cm in length within one and a half months. (3) Outgrowing of the plant. The frames are put in the open sea when seawater temperature decreased to 20℃. After one month, the sporelings are large enough to be transplanted. It is concluded that the clone technique has the following advantages: (1)Large amount of clones can be produced in a short period of time. (2) Clone seeding method makes it free from the biological rhythm, one can seed the plant anytime all the year round. (3) It takes only one and a half months to complete the process of sporeling cultivation in the greenhouse. At present, this technique is used in the breeding of new strains of Laminaria.
基金The National Natural Science Foundation of China under contract No.41206116the Postdoctoral Science Foundation of China under contract No.2011M501167+1 种基金the National Public Benefit Research Foundation of China under contract No.201105021the Fundamental Research Funds for the Central Universities under contract No.201362040
文摘In the past two decades, many studies have focused on the classification within genus Laminaria, ultimately trying to divide it into two subgroups or genera： Laminaria and Saccharina. A significant debate still surrounds the question of its division, as the conflicting phylogenetic hypotheses that have resulted from the classification studies are based on different taxon sampling, molecular markers, or analysis methods. It is aimed at elucidate the molecular phylogeny within Laminaria and Saccharina. The nine species of Lami- nariales are sampled from northern Asia and Europe, and 23 new sequences in the nuclear, plastid, and mitochondrial genomes are determined to identify their taxonomic status. The phylogenetic analyses of 71 species are performed, including representatives from six of the seven families of the order Laminariales, based on three separate data sets. An evidence is provided to strongly support a clear split that maintains the two recognized genera, Laminaria and Saccharina, with Laminaria appearing to be the ancestor group. Further, analyses indicate that all taxa in Saccharina and Laminaria did not form a monophyletic lineage, instead Laminariaceae and Lessoniaceae grouped together interlacedly, and Costariaceae appeared as the sister taxon of the Lessoniaceae-Laminariaceae clade. In the phylogenetic analysis, mitochondrial c oxi- dase I （COI） sequences appeared to be the most credible molecular marker which was more befitting than nuclear encoded internal transcribed spacer （ITS） and plastid encoded rbcL for establishment of Laminariales systematics. It is the most comprehensive phylogeny of the order Laminariales, and contributes to an enhanced understanding and estimation of the phylogenetic relationships for the economically important seaweeds, Laminaria and Saccharina.
文摘A genetic transformation model for the seaweed Laminaria japonica mainly includesthe following aspects:1. The method to introduce foreign genes into the kelp, L. japonicaBiolistic bombardment has been proved to be an effective method to bombard foreign DNA throughcell walls into intact cells of both sporophytes and gametophytes. The expression of cat and lacZ was de-tected in regenerated sporophytes, which suggests that this method could induce the integration of for-eign genes. 2. Promoters to drive gene expressionThe CaMV35S promoter was first used by us to induce the expression of GUS gene in brown algae.But results of further studies suggested that CaMV35S could be a tissue-specific promoter. Our use ofSV40 promoter resulted in both transient and stable expression of lacZ and cat in sporophytes or gameto-phytes. No GUS or LacZ background was found in either sporophytes or gametophytes.3. The regeneration route of transgenic kelpThe regeneration efficiency of explants is still very low. By using female gametophytes as gene hostsand parthenogenesis as regeneration route, CAT activity and LacZ activity were detected in regeneratedsporophytes of parthenogenetic kelp.4. The way to select transgenic kelpResults of sensitivity tests showed that kelp was only sensitive to chloramphenicol and hygromycin a-mong many antibiotics. The regenerated sporophytes by parthenogenesis were more sensitive to hygromycinthan to chloramphenicol. Resistant kelp was created by transforming female gametophytes with pSV40-CAT and stimulating parthenogenesis followed by selection in medium with lethal concentration of chloram-phenicol,.5. Safety consideration of transgenic kelp1) L. japonica was originally introduced from Japan. In China it is a cultured population. The pos-sibility of its negative impact on natural populations is very low. 2) The vectors and target genes used fortransformation should be restricted In order to avoid any negative impacts on human health and environ-ment. 3)Specially devised containers (3. 6 L, made of 200 μm membrane) were used to ensure that thekelp cannot escape or be eaten by marine animals. 4) To avoid the release of spores, it is very necessaryto harvest the kelp at suitable age before the sporangium forms.
文摘Four media (PESI solid, MS liquid, MS solid and ASP-C-I solid medium) were usedto induce callus from excised tissues of the kelp Laminaria japonica. Only PESI solid medium and MSsolid medium produced calli. Modified MS solid medium supplemented with mannitol (3%, W/V), yeastextract (0.1%, W/V), VB2(0. 5 mg/ml), VB12(0.5 mg/ml), kinetin (0. 108 μg/ml) and NAA(1.860μg/ml) showed much better effect on callus induction than non-modified MS solid medium. After24 days of induction 75 .5% of tissues in PESI solid medium showed callus formation. For modified MSsolid medium, after three months of induction 67. 3% of tissues dedifferentiated into calli. No calluscould be found after five months of induction in either MS liquid or ASP-C-I solid medium. When calliwere squashed and cultured in N-P enriched autoclaved seawater, MS liquld medium and ASP12-NTAliquid medium (both modified with kelp extract), differentiation of cells and regeneration of sporophyteswere only observed in ASP12-NTA medium supplemented with kelp extract. Gametophyte-like filamentsformed first, then eggs were released. It was suggested that sporophyte formation could be a process ofparthenogenesis. Sterilization techniques in tissue culture of L. japonica were also tested in this study.
基金supported by the National Natural Science Foundation of China under contract No.30471349Guangdong Natural Science Foundation under contract No.011256.
文摘Five fucoidan fractions from Laminaria japonica with different sulfate content and molecular weight were prepared by anion-exchange chromatography and mild acid hydrolysis. Their antioxidant effects on azo radicals 2-2＇-Azobis （2-amidinopropane） dihydrochloride （AAPH） induced oxidation of human low-density lipoprotein （LDL） were evaluated by monitoring cholesteryl ester hydroperoxides （CHL-OOH） formation kinetics through reverse-phase high performance liquid chromatography （RP-HPLC） analysis. Fucoidan F - C with a low molecular mass of 2 000 ～8 000 and a sulfate content of 24.3% had much stronger protective antioxidant effect than other four fucoidan fractions on the hydrophilic radical AAPH induced LDL oxidation. However, the highly sulfated fucoidan fraction L - B with a molecular mass of 20 000 was completely ineffective in protecting LDL from the AAPH induced oxidation. The results suggested that both molecular mass and sulfate content of fucoidan played very important roles in their effects on the AAPH induced LDL oxidation.
文摘Experiments with Lamnaria japonica were conducted in Meidao Bay and Pier Bay,Qingdao,China,Nitrogen-starved plants were fertilized intermittently with 7.1 mM NH4-N solution for 1 hour at 3 day intervals, after which chlorophyll a, fucoxanthin, chlorophyll c and B-carotene contents were analyzed. Photosynthetic and growth rates of plants and nitrogen content of seawater were determined. Photosynthetic and growth rates of the nitrogen-enriched plants were higher than those of the controls, and their contents of chlorophyll a, fucoxanthin, chlorophyll c and B-carotene were 1.65,0.67,0.33 and 0.06 mg . dm-2 respectively, or 2.46,2.03,1.86 and 1.81 times those of the controls. The ratio of fiicoxanthin to chlorophyll a in nitrogen-enriched plants was lower than that of the controls. Normal growth rate of the plants (2 cm.day-1 in length)were reached when the chlorophyll a content exceeded 0.1 mg.g-1 fresh wt., indicating that chlorophyll a content can serve as an indicator of normal growth.Experimental
文摘The light demands of seaweeds is an interesting and rather complex phenomenon because they depend not only on the species but also on their different development stages. Even different parts of the same plant sometimes have different light demands. Light control is an important procedure at large scale Lamnaria nursery stations in China. Technicians and scientists have different viewpoints on the best method to regulate light. A culture study on Lamnaria japonica starting from zoospores to several centimeter sporophytes to find the optimal and critical irradiance ranges for juvenile Laminaria at different development stages added more knowledge on this aspect. Experiment results show gametophytes can not tolerate irradiance of more than 150uEm-2s-1 while sporophytes can tolerate more than 519 uEm-2s-1. This big difference starts from the very early stage of 1-to 2-celled sporophytes. The biological basis and mechanism of this phenomenon need further research.
文摘Sori formation in Laminaria japonica was studied from the ecological and physiological point of view. Cutting through the medulla of Laminaria japonica improved the formation of sori.Sori formation under different water temperature, photoperiod, and light intensity was investigated and total nitrogen and reducible sugar content determined. The result showed that son of L. japonica can be formed in 1-22℃ water in Dalian. No sori were found in water over 23℃. High temperature inhibits the formation of son, but low temperature has no effect. Apparently, light intensity affects the formation of sori, but photoperiod does not. In shallow water L. japonica grows slower but stores dry material faster and forms sori rapidly. In deeper water it grows faster in length but stores dry material slower and the sori formation is slow. Analysis of dry material shows that during sori formation the water content decreases but total nitrogen and total reducible sugar increase.Only when the storage of sugar reaches a
文摘We extracted a glycoprotein from the brown alga Laminaria japonica (LJGP). We previously demonstrated that LJGP induced apop- tosis in HT-29 colon cancer cells via the Fas- and the mitochondrial signaling pathway, and cell-cycle arrest. However, its effect on the cell membrane remained unknown. In this study, we identified the involvement of matrix metalloproteinase (MMP), integrin, and Epi- thelial (E)-cadherin in LJGP-induced apoptosis in HT-29 cells. LJGP treatment increased the expression and activity of MMP-2 and MMP-9. Furthermore, LJGP decreased the expression of integrin αν, β3, β5, β6 and E- cadherin. Consistent with a decreased expression of E-cadherin, LJGP inhibited the Wnt signaling pathway. Moreover, activation of downstream molecules of integrin, including focal adhesion kinase (FAK), the Src family of protooncogenic tyrosine kinases, extracellular signal-related kinase (ERK), and phosphatidyl inositol 3 kinase (PI-3K) were also decreased. These findings suggest that LJGP-induced apoptosis of HT-29 cells involves possible ECM disruption and cell detachment, which are executed principally through the activation of MMPs and by a decrease of adhesion molecules, contributing to a down-regulation of the PI-3K, MAPK, and Wnt signaling pathways. Apoptosis induced by ECM disruption or cell detachment is also known as anoikis. We can say that LJGP induces anoikis in HT-29 cells.
