湛江海域浒苔属Enteromorpha种类的形态与显微结构

用比较解剖学方法观察提江沿海浒苔属（Enteromorpha ）海藻的形态结构,并结合统计分析对其进行 物种鉴定。结果表明,依据藻体分校的有元、数量及分校与主枝直径的大小等形态特征,鉴定的浒苔属j海藻有6种1个变型,分别为缘管浒苔（E. linza）、肠浒苔（ E. intestinalis ）、扁浒苔（ E. compressa ） ,浒苔（E. proliferα）、 条浒苔（E. clathratα）、由浒苔（ E·flexω5α）和肠浒苔宽叶变型（ E. intestinalis f.broadifolium） 0藻体长度由 大到小依次为浒苔、条浒苔、缘管浒苔、肠浒苔、扁浒苔和炀浒苔宽叶变型：细胞呈多角形,藻体的位置不同其细胞大小有所变化,除由浒苔和条浒苔外,其他4种1个变型浒苔的中部细胞最小;所有种类的细胞均有淀粉核,其中肠浒苔、缘管浒苔和扇浒苔仅1个淀粉核,而其他种出现多个淀粉核,尤其条浒苔和曲浒苔数量最多,可达6个以上。定量描述浒苔属6种1个变型的形态特征、内部结构,并发现浒苔属海藻非中空营状的结构特征。     

The Ulva prolifera genome reveals the mechanism of green tides

The genome of green microalgae has rarely been reported.Ulva prolifera is a green microalga that has received much attention.Despite research articles about U.prolifera in recent years,we know very little about its genome.Therefore,the 87.9-Mb haploid genome(containing 10 311 protein-coding genes)of U.prolifera was studied,and the genome was compared with that of U.mutabilis,which is the only published Ulva species.Results showed that the two species are closely related.A phylogenetic tree was constructed among U.prolifera and other green algae available in GenBank,revealing the evolutionary status of U.prolifera in Chlorophyta.To understand why U.prolifer a could grow rapidly,we identified some genes related to growth,such as those involved in cell division,phosphorylation,and cell proliferation.In addition,genes related to stress resistance were found,which supports the notion that U.prolifera grows vigorously in nature.These results help to characterize green tides from a new perspective and reveal some important insight into the biology of U.prolifera.     

Isolation and identification of bacteria associated with the surfaces of several algal species

We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses.Twelve strains of bacteria were obtained from the surfaces of the following four species of algae:Gracilaria textorii,Ulva pertusa,Laminaria japonica,and Polysiphonia urceolata.The isolated strains of bacteria can be divided into two groups:Halomonas and Vibrio,in physiology,biochemical characteristics and 16S rDNA sequence analyses.The phylogenetic tree constructed based on ...     

Long interspersed elements in three species of Gracilaria （Gracilariaceae, Rhodophyta）

In order to find out whether long interspersed elements (LINEs) existed in macro-algae ge- nomes or not, we tested the LINE homologues in representative families (species): Gracilaria (G. eucheumoides Harv., G. tenuistipitata Chang et Xia, and G. textorii (Sur) De-Toni), Laminaria (L. longis- sima Miyabe and L. japonica Aresch.), and Ulva (U. lactuca L. and U. pertusa Kjellm.) during 2004 to 2005. Polymerase Chain Reaction (PCR) was carried out with degenerate oligonucleotide primers de- signed from LINEs of rice homologues and Cin4 of maize. Cloning and nucleotide sequencing of the PCR products revealed that 4 clones that derived from 3 species of Gracilaria have LINE homologues. The nucleotide sequences of the 4 LINE homologues diverged greatly, but the amino acid sequences deduced from them were relatively conserved. The endonuclease regions of the LINE homologues greatly di- verged from that of other plants, but they had closer phylogenetic relationship to Zepp elements in Chlor- ella sp., which indicated that sequence divergence by vertical transmission has been a major influence on the evolution of algal LINEs.     

IDENTIFICATION OF CYTOKININ IN A GREEN ALGAE EXTRACT

Isopentnyladenosine(i~6Ado) was identified, and trans-zeatin (trans-Z) and trans-zeatin riboside(trans-ZR) were detected by high pressure liquld chrmoatoguphy (HPLC) but not verified withchromatography - mass spectrometry (GC - M S ) analysis of cytokinin from the extracts of green algae (Ulvapertusa (Kjellm), Enteromopha compressa and Monostma sp). This indicated that the green algae mixturecontained cytokinin -like substances.     

Ulva and Enteromorpha (Ulvaceae, Chlorophyta) from two sides of the Yellow Sea: analysis of nuclear rDNA ITS and plastid rbcL sequence data

Ulvacean green seaweeds are common worldwide; they formed massive green tides in the Yellow Sea in recent years, which caused marine ecological problems as well as a social issue. We investigated two major genera of the Ulvaceae, Ulva and Enteromorpha, and collected the plastid rbcL and nuclear ITS sequences of specimens of the genera in two sides of the Yellow Sea and analyzed them. Phylogenetic trees of rbcL data show the occurrence of five species of Enteromorpha (E. compressa, E. flexuosa, E. intestinalis, E. linza and E. prolifera) and three species of Ulva (U. pertusa, U. rigida and U. ohnoi). However, we found U. ohnoi, which is known as a subtropical to tropical species, at two sites on Jeju Island, Korea. Four ribotypes in partial sequences of 5.8S rDNA and ITS2 from E. compressa were also found. Ribotype network analysis revealed that the common ribotype, occurring in China, Korea and Europe, is connected with ribotypes from Europe and China/Japan. Although samples of the same species were collected from both sides of the Yellow Sea, intraspecific genetic polymorphism of each species was low among samples collected worldwide.     

Growth inhibition to three red tide microalgae by extracts of Ulva pertusa

1 INTRODUCTION In recent decades, red tides that induced by in- creasing eutrophication occur frequently in coastal areas worldwide. This has caused serious problems in marine environment, aquaculture industries and human health (Qi et al., 1993; Horner e…     

A New Molecular Label Applied to the Study of the Yellow Sea Green Tide

From 2007 to 2017, large-scale green tides occurred every year in the Yellow Sea of China, and Ulva prolifera was the main species leading to the green tide. In this study, we used the Polymerase chain reaction and 3' Rapid-amplification of c DNA ends technique to amplify the nr DNA-LSU and IGS sequences in U. prolifera and one species of Blidingia. These techniques showed 3259 bp of nrD NA-LSU and 3388 bp of IGS in U. prolifera and 3282 bp nr DNA-LSU and 3059 bp IGS in Blidingia sp. At the same time, tandem repeats, short dyads, palindromic and multiple simple repeat sequences in the IGS sequence were found by analyzing the structure of the IGS sequence in U. prolifera and Blidingia sp. G + C contents of the IGS sequence in U. prolifera and Blidingia sp. were 52.42% and 53.09%, respectively. We divided the U. prolifera into two types according to the morphological characteristics. Although the specimens of U. prolifera from the Qingdao coastal area, Jiangsu coastal area and the Yellow Sea have different morphologies, their ITS and IGS sequences are almost identical. Therefore, the main species of the green tides in the Qingdao coastal area, Jiangsu coastal area and the Yellow Sea are the same and have the same origin.     

Molecular phylogenetic analysis of attached Ulvaceae species and free-floating Enteromorpha from Qingdao coasts in 2007

Based on the sequence data of the nuclear ribosomal DNA internal transcribed spacer(ITS) 1,5.8 S,and ITS 2,the molecular phylogeny was analyzed on Ulvaceae species collected from Qingdao coasts in summer of 2007,including 15 attached Ulva and Enteromorpha samples from 10 locations and 10 free-floating Enteromorpha samples from seven locations.The result supported the monophyly of all free-floating Enteromorpha samples,implying the unialgal composition of the free-floating Enteromorpha,and the attached Ulvaceae species from Qingdao coasts were grouped into other five clades,suggesting that they were not the biogeographic origin of the free-floating Enteromorpha in that season.     

Comparative Studies on Phosphorus Uptake and Growth Kinetics of the Microalga Tetraselmis subcordiformis and the Macroalga Ulva pertusa

Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate (Vm^sp) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.     

Pyrolytic characteristics and kinetics of the marine green tide macroalgae, Enteromorpha prolifera

The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of biomass and could be used as a biofuel. In this study, the pyrolytic characteristics and kinetics of E. prolifera were investigated using thermogravimetric analysis (TGA) method. Cornstalk and sawdust were used as comparisons. Pyrolytic characteristics were studied using TG-DTG (thermogravimetry-derivative thermogravimetry) curves. Three stages in the pyrolytic process were determined: dehydration, dramatic weight loss and slow weight loss. E. prolifera was pyrolyzed at a lower initial temperature than the two terrestrial biomass forms. The apparent activation energy values for the three types of biomass were calculated and the mechanism functions were determined using 16 different mechanism functions, frequently used in thermal kinetics analysis. Activation energy values varied with mechanism function and the range of activation energy values for E. prolifera, cornstalk, and sawdust were 25-50 kJ/mol, 60-90 kJ/mol and 120-155 kJ/mol, respectively. This indicates that E. prolifera has low thermal stability for pyrolysis and good combustion characteristics.     

Investigation of the decline of Ulva prolifera in the Subei Shoal and Qingdao based on physiological changes

It has been a scientific consensus that Ulva prolifera green tide that break out annually between May and August in the recent decade off eastern coast of Yellow Sea. To investigate the ecological mechanism of the decline of U. prolifera green tide, we compared the physiological characteristics of U. prolifera samples collected in three stages of the green tide in Subei Shoal north Jiangsu, the initiation point, on May 10(early, the initiation), July 10(middle, the outbreak), and in Taipingjiao, Qingdao on August 10(late, the decline). Compared to the early samples, the middle, and late samples showed a lower chlorophyll content and photosynthetic e fficiency at a higher lipid peroxidation level. The middle and later samples had fewer chloroplasts in the cells of U. prolifera than those in the early samples. In addition, the cells of U. prolifera sampled in the late stage showed ruptured and deformed cell walls. Differences in physiological function were reflected in the growth rate. Both the middle and late U. prolifera samples presented negative growth rates. Correlation analysis results show that the rising temperature was mainly responsible for the local decline of U. prolifera green tide. The high light-intensity that could induce the photoinhibition was also an important factor for the decline. Therefore, U. prolifera population that remained in the Subei Shoal and those that northward drifted to Qingdao experienced the same decline processes: rising temperature and continuous high light conditions in the late phase of green tide reduced the photosynthetic capacity and destroyed the antioxidant system of the thallus, which lead to decrease of biomass. The only difference is that the temperature in the Subei Shoal rose earlier than that in Qingdao; thus, U. prolifera remaining in the Subei Shoal went disappeared first.     

Effect of temperature and irradiance on the growth and reproduction of Enteromorpha prolifera J. Ag. （Chlorophycophyta, Chlorophyceae）

Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate (SGR) of 10.47 at 25°C/40 μmol m-2s-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative ceils could still divide actively in the algal tissues.     

Molecular diversity of Enteromorpha from the coast of Yantai: a dual-marker assessment

We collected nine Enteromorpha specimens from the coast of Yantai and evaluated their diversity based on analyses of their ITS （internal transcribed spacer） and 5S rDNA NTS （non-transcribed spacer） sequences. The ITS sequences showed slight nucleotide divergences between Enteromorpha linza and Enteromorpha prolifera. In contrast, multiple highly variable regions were found in the ITS region of Enteromorpha flexuosa. In general, there were more variable sites in the NTS region than in the ITS region in the three species. The variations in 5S rDNA NTS sequences indicated that the molecular diversity of Enteromorpha from the coast of Yantai is very high. However, a phylogenetic tree constructed using 5S rDNA NTS sequence data indicated that genetic differences were not directly related to geographical distribution.     

Effect of temperature and irradiance on the growth and reproduction of Enteromorpha prolifera J. Ag. （Chlorophycophyta,Chlorophyceae）

Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate （SGR） of 10.47 at 25℃/40 μmol m^-2s^-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative cells could still divide actively in the algal tissues.     

ASPECTS OF IRON NUTRITION IN MACROALGAE ULVA PERTUSA (CHLOROPHYTA) UNDER IRON STRESS

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The possibility analysis of habitats, origin and reappearance of bloom green alga （Enteromorpha prolifera） on inshore of western Yellow Sea

Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was ...     

Analysis of expressed sequence tags from the Ulva prolifera (Chlorophyta)

In 2008, a green tide broke out before the sailing competition of the 29th Olympic Games in Qingdao. The causative species was determined to be Enteromorpha prolifera (Ulva prolifera O. F. Müller), a familiar green macroalga along the coastline of China. Rapid accumulation of a large biomass of floating U. prolifera prompted research on different aspects of this species. In this study, we constructed a nonnormalized cDNA library from the thalli of U. prolifera and acquired 10 072 high-quality expressed sequence tags (ESTs). These ESTs were assembled into 3 519 nonredundant gene groups, including 1 446 clusters and 2 073 singletons. After annotation with the nr database, a large number of genes were found to be related with chloroplast and ribosomal protein, GO functional classification showed 1 418 ESTs participated in photosynthesis and 1 359 ESTs were responsible for the generation of precursor metabolites and energy. In addition, rather comprehensive carbon fixation pathways were found in U. prolifera using KEGG. Some stress-related and signal transduction-related genes were also found in this study. All the evidences displayed that U. prolifera had substance and energy foundation for the intense photosynthesis and the rapid proliferation. Phylogenetic analysis of cytochrome c oxidase subunit I revealed that this green-tide causative species is most closely affiliated to Pseudendoclonium akinetum (Ulvophyceae).     

奥尼罗非鱼杂交子代及亲本mtDNA D-loop基因序列的多态性

利用PCR技术扩增奥利亚罗非鱼(Oreochromis aureus)、尼罗罗非鱼(O.niloticus)及其杂交子代(O.aureus♂×O.niloticus♀)3个群体mtDNA控制区全序列,分析其变异和遗传结构。结果显示:3个群体的mtDNA控制区序列长度多态性并不十分明显,全长921～933bp;3个群体间存在丰富的DNA序列多态性,共检测到138个变异位点(14.9%),44个个体具有44种单倍型(haplotype);3群体间的序列差异平均为4%,Tamura-Nei遗传距离平均为5.1%;采用NJ法和ME法构建的分子系统树中,奥利亚罗非鱼群体内所有的单倍型聚成一支,尼罗罗非鱼与其杂交子代的单倍型混杂在一起,聚成一支,表明杂交后代mtDNAD-loop表现为母系遗传。     

Taxonomic reassessment of Polysiphonia hainanensis(Rhodomelaceae,Rhodophyta) based on molecular and morphological analyses

Polysiphonia hainanensis was previously described from Hainan, China, but DNA sequence had never been provided and its phylogenetic position in Polysiphonieae has not been clear so far. The classification of Polysiphonieae has changed recently based on the molecular analyses and detail morphological anatomy, consequently, the generic assignment of some species must be reassessed. In this study, we analyzed phylogenetic relationships of P. hainanensis and the related taxa in Polysiphonieae and Streblocladieae based on rbcL sequences, with specimens collected from the type locality and the area around. Two genetic types were detected, and formed a clade with Bryocladia thyrsigera with strong bootstrap support, in which the divergence was less than 0.81%. Furthermore, based on morphological analyses, we found characteristics of Chinese specimens, number of pericentral cells, percurrent axis, determinate branchlets, branching pattern, spermatangial axes development, and arrangement of tetrasporangia, etc., were consistent with those of Bryocladia. Combined with morphological and molecular analyses, P. hainanensis was taken a synonymous of B. thyrsigera, and gametophytes of this species were found from China for the first time.