Community structure and controlled factor of attached green algae on the Porphyra yezoensis aquaculture rafts in the Subei Shoal, China

This study analyzes the community structure, the quantity changes of the algae and the effect of important environmental factors and estimates the total biomass of the attached green algae in the survey areas. The study uses data from surveys of the attached green algae on the Porphyra yezoensis aquaculture rafts and data regarding the environmental factors from October 2010 to April 2011 in the Subei Shoal. The attached green algae on the rafts included Ulva prolifera, Capsosiphon groenlandicus, U. linza, U. intestinalis, U. clathrata, and U. cornpressa. The biomass changes of the attached green algae exhibited an inverted parabola： the biomass was the highest （14 898 t） in April, and was the second highest （2 034 t） in November; it was lowest in February （only 729 t） and increased sharply from March to April. The species diversity differed significantly among the seasons. In September and October, when the P. yezoensis aquaculture rafts were initially set up, the attached green algae had a high biodiversity, while from December to the next February, a variety of green algae species coexisted on the rafts, although the biomass was low, and from March to April, as the biomass increased sharply, the species diversity dropped to the minimum. During this time, C. groenlandicus was apparently dominant with the maximum biomass proportion up to 80%, while the U. prolifera proportion increased exponentially to 20% to 40%. The water temperature had a direct regulating effect on the biomass and the species succession of the attached green algae. The estimation of the community dynamics and the biomass of the green algae provided the evidence needed to track the origin of the large-scale green tide in the southern Yellow Sea.

Flavor Characteristics of Different Crops of Laver(Porphyra yezoensis)During One Harvest Cycle

The taste and odor analysis of the first,second,fourth and sixth crops of laver(Porphyra yezoensis)was obtained by electronic tongue,taste-related compound,electronic nose and gas chromatography-ion mobility spectrometer(GC-IMS).Through the detection of the electronic tongue,the pleasant tastes such as umami and richness are more intense in the early crops,which is consistent with the analysis results of free amino acids and flavored nucleotides.The electronic nose can clearly distinguish between different laver crops.GC-IMS separated and identified 36 volatile components from lavers,mainly including aldehydes,ketones,alcohols,esters,acids and aromatic substances.For the early harvested crops,nonanal,octanal,hexanal and benzaldehyde have a significant contribution to odor because of the high concentration and low threshold of these compounds.For the later harvested crops,the concentration of most ketones and some aldehydes increased.1-Octen-3-ol,malondialdehyde and heptanal constituted the main odor characteristics.

Efficient gusA Transient Expression in Porphyra yezoensis Protoplasts Mediated by Endogenous Beta-tubulin Flanking Sequences

Endogenous tubulin promoter has been widely used for expressing foreign genes in green algae, but the efficiency and feasibility of endogenous tubulin promoter in the economically important Porphyra yezoensis (Rhodophyta) are unknown. In this study, the flanking sequences of beta-tubulin gene from P. yezoensis were amplified and two transient expression vectors were con-structed to determine their transcription promoting feasibility for foreign gene gusA. The testing vector pATubGUS was constructed by inserting 5’- and 3’-flanking regions (Tub5’ and Tub3’) up- and down-stream of β-glucuronidase (GUS) gene (gusA), respectively, into pA, a derivative of pCAT?3-enhancer vector. The control construct, pAGUSTub3, contains only gusA and Tub3’. These con-structs were electroporated into P. yezoensis protoplasts and the GUS activities were quantitatively analyzed by spectrometry. The results demonstrated that gusA gene was efficiently expressed in P. yezoensis protoplasts under the regulation of 5’-flanking sequence of the beta-tubulin gene. More interestingly, the pATubGUS produced stronger GUS activity in P. yezoensis protoplasts when com-pared to the result from pBI221, in which the gusA gene was directed by a constitutive CaMV 35 S promoter. The data suggest that the integration of P. yezoensis protoplast and its endogenous beta-tubulin flanking sequences is a potential novel system for foreign gene expression.

Genetic variation of Porphyra yezoensis by using AFLP1

Genetic variation of 11 lines of Porphyra yezoensis from the coastline of Kagoshima of Japan, Qingdao, Nantong, Putuo and Nanji Islands of China were studied by using amplified fragment length polymorphism (AFLP). 778 bands were obtained with AFLP analysis of 16 primer combinations, among which 15 were unique, about 98.07% were polymorphic. The AFLP data showed that the closest genetic distance was 0 - 180 between two Kagoshima samples, and the farthest one was 0.397 between Kagoshima No. 1 and Nantong No - 9 line. The genetic distance showed that the variation was within the inner species scope. Neighbor-joining cluster and UPGMA cluster indicated that samples from Kagoshima and Qingdao were with high similarity and either with the samples of Nantong, Putuo and Nanji Islands. P. yezoensis in China shared high genetic diversity, and the genetic distance showed positive correlation with the geographic distance.

Extraction of plasmid-like DNA and high-quality total DNA from Porphyra yezoensis

Somatic cells were prepared from sea snail enzyme digests of Porphyra yezoensis thalli. Us ing SDS - Proteinase K as extraction solution, total DNA was isolated from the somatic cells. The crude extracts of total DNA were purified with glassmilk, and the resulting DNA was of sufficient quality for digestion of restriction endonuclease. DNA bands were clearly observed in the restriction patterns of EcoRI, PstI and HaeIII respectively. The presence of DNA hands in the restriction pattern of total DNA indicated that the genome of Porphyra yezoensis may be small. Unexpectedly, using guanidinium isoth iocyanate and sarcosyl as extraction solution, a plasmid-like DNA band (2.3 Kb) was directly found in the isolated total DNA of Porphyra yezoensis. A very simple and convenient method for plasmid-like DNA isolation has been established.

乳酸菌分离鉴定及其条斑紫菜乳酸菌混合发酵理化因子的变化

对泡菜老坛水中的乳酸菌进行分离鉴定,获得3株乳酸菌,确定为短乳杆菌(Lactobacillus brevis)、植物乳杆菌(Lactobacillus plantarum)、干酪乳杆菌(Lactobacillus casei)。以条斑紫菜(Porphyra yezoensis)为原料,以4种不同配比的上述乳酸菌对条斑紫菜进行直投式发酵,探讨发酵过程中发酵液部分理化因子的变化规律。结果显示,4种发酵液的pH下降趋势相似,从开始的4.51下降到2.90;1∶1∶2(体积比)混合乳酸菌发酵液的产酸能力最强,发酵终点总酸含量为13.75 g/L,为发酵开始的6倍;1∶1∶2混合乳酸菌发酵液的总糖含量由开始的29.95 g/L下降为发酵终点的18.97 g/L;1∶1∶2混合乳酸菌发酵液亚硝酸盐含量的峰值最小,为3.75 mg/kg;1∶1∶1混合乳酸菌发酵液氨基酸含量较高,最大值为58.16μmol/mL;蛋白质含量下降幅度最大的是1∶1∶3混合乳酸菌发酵液。

条斑紫菜叶绿体基因密码子偏爱性分析

条斑紫菜是一种具有重要经济价值的藻类植物,广泛应用于医学、纺织和食品等领域。本研究通过Python、OGDRAW、CodonW、CUSP、DNAstar及SPSS20等软件进行多元统计和密码子偏爱性分析,并获得了56个条斑紫菜叶绿体基因序列的GC_(1)、GC_(2)、GC_(3)、ENC值和RSCU值,同时获得了条斑紫菜叶绿体基因组结构图和密码子使用热图。结果显示,条斑紫菜叶绿体基因的AT碱基含量高于GC碱基含量,说明其密码子偏爱于A/T碱基结尾。中性绘图分析、ENC绘图分析和PR2-plot分析结果表明影响条斑紫菜叶绿体基因密码子偏爱性的主要影响因素是自然选择。将高频密码子和高表达优越密码子结合,最终获得了9个条斑紫菜叶绿体基因的最优密码子,如UUU、UCA和CCU,均偏爱于A/U碱基结尾。研究结果为条斑紫菜的资源开发和培育利用,以及外源基因的稳定表达提供了重要的科学依据。