Carotenoids play a crucial role in absorbing light energy for photosynthesis, as well as in protecting chlorophyll from photodamage. In contrast to the Streptophyta, few studies have examined carotenoid biosynthetic pathways in algae, owing to a shortage of datasets. As part of the 1000 Plants Project, we sequenced and assembled the transcriptomes of 41 marine macroalgal species, including 22 rhodophytes and 19 phaeophytes, and then combined the datasets with publicly available data from GenBank (National Center for Biotechnology Information) and the U.S. Department of Energy Joint Genome Institute. As a result, we identified 68 and 79 full-length homologs in the Rhodophyta and Phaeophyceae, respectively, of seven inferred carotenoid biosynthetic genes, including the genes for phytoene synthase (PSY), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), ζ-carotene isomerase (Z-ISO), prolycopene isomerase (crtISO), lycopene β-cyclase (LCYB), and lycopene ε-cyclase (LCYE). We found that the evolutionary history of the algal carotenoid biosynthetic pathway was more complex than that of the same pathway in the Streptophyta and, more specifically, that the evolutionary history involved endosymbiotic gene transfer, gene duplication, and gene loss. Almost all of the eukaryotic algae that we examined had inherited the seven carotenoid biosynthesis genes via endosymbiotic gene transfer. Moreover, PSY, crtISO, and the ancestral lycopene cyclase gene (LCY) underwent duplication events that resulted in multiple gene copies, and the duplication and subsequent divergence of LCYB and LCYE specialized and complicated the cyclization of lycopene. Our findings also verify that the loss of LCYE in both the microphytic rhodophytes and phaeophytes explains the differences in their carotenoid patterns, when compared to the macrophytic rhodophytes. These analyses provide a molecular basis for further biochemical and physiological validation in additional algal species and should help elucidate the origin and evolution of carotenoid biosynthetic pathways.

Endogenous viral elements (EVEs) are host-genomic fragments originated from viral genomes. They have been found universally in animal and plant genomes. Here we carried out a systematic screening and analysis of EVEs in algal genomes and found that EVEs commonly exist in algal genomes. We classified the EVE fragments into three categories according to the length of EVE fragments. Due to the probability of sequence similarity by chance, we ignored the potential function of medium-length EVE fragments. However, longlength EVE fragments probably had capability to encode protein domains or even entire proteins, and some short-length EVE fragments had high similarity with host's siRNA sequences and possibly served functions of small RNAs. Therefore, short and long EVE fragments might provide regulomic and proteomic novelty to the host's metabolism and adaptation. We also found several EVE fragments shared by more than 3 algal genomes. By phylogenetic analysis of the shared EVEs and their corresponding species, we found that the integration of viral fragments into host genomes was an ancient event, possibly before the divergence of Chlorophytes and Ochrophytes. Our findings show that there is a frequent genetic flow from viruses to algal genomes. Moreover, study on algal EVEs shed light on the virus-host interaction in large timescale and could also help us understand the balance of marine ecosystems.

The influence of macronitrogen (NO₃^- and NH₄⁺) addition with Ulva pertusa on dissolved inorganic carbon system in seawater was studied. The results indicate that p (CO₂) and HCO₃^- concentration decrease significantly, while pH and CO₃^2- concentration increase significantly. When the concentration of NO₃^- was less than 71 μmol/dm³ or NH₄⁺ was less than 49.7 μmol/dm³, dissolved inorganic carbon (DIC) absorption rates by Ulva pertusa generally increased with the increasing of nitrogen concentration. The DIC decreased 151 μmol/dm³ with the addition of 71 μmol/dm³ NO₃^- and decreased 232 μmol/dm³ with the addition of 49.7 μmol/dm³ NH₄⁺ after the experiment compared with DIC measured without nitrogen addition. A significant negative-correlation was found between △c (DIC) and growth rate (μ) of Ulva pertusa (r=-0.91, P <0.000 1, n=11). NH₄⁺ had more influence on the species of inorganic carbon system than NO₃^-.

Considering that the field is largely unexplored and its importance to aquaculture, outline of oomycetes and fungi parasiting on marine algae was provided in this paper, including 15 species of oomycetes, six species of chytrids, 31 Ascomycota species and one species of mitosporic fungi. In natrue, both the oomycetes and chytrids frequently occurred and induced prevalences of disease which could destroy the populations of host plants greatly. However, the parasites in Ascomycota on algae have never occurred as epidemics so far. Some issues relating to the field were discussed such as performing tests to satisfy Koch's postulates, investigations of host specificity, interactions between host and parasite and the potential effects of environmental factors on occurrence of a disease, which are urgent in need of further investigations.

This article presents an instrumental analysis of the kinds and contents of basic amino acids contained in 9 planktonic algae specimens and a comparison between the nutritive value of amino acids in the 9 planktonic aglae and that of amino acids in prawn.Moreover, a comparison is made between contents of various planktonic algae amino acids essential to animails.It is concluded that such algae as N.Closterium., f.finutissima, C.Simplex var, CaIcitrans, P.tricornutum, Pla.Subcordiformis and S.costatum are nutritive foodstuffs.

phosphomannomutase (PMM; EC 5.4.2.8) is an enzyme that catalyzes the interconversion reaction between mannose-6-phosphate and mannose-1-phosphate. However, its systematic molecular and functional investigations in algae have not hitherto been reported. In this work, with the accomplishment of the 1 000 Plant Project (OneKP) in which more than 218 species of Chromista, including 19 marine phaeophytes, 22 marine rhodophytes, 171 chlorophytes, 5 cryptophytes, 4 haptophytes, and 5 glaucophytes were sequenced, we used a gene analysis method to analyze the PMM gene sequences in algae and confirm the existence of the PMM gene in the transcriptomic sequencing data of Rhodophyta and Ochrophyta. Our results showed that only one type of PMM with four conserved motifs exists in Chromista which is similar to human PMM. Moreover, the phylogenetic tree revealed that algae PMM possibly originated from archaea.

Experiments on the effects of nitric oxide (NO) and iron on the growth of marine microalgae Skeletonema costatum were conducted.The results are as follows:exogenous NO could increase the growth rate of marine algae and raise the biomass remarkably under iron-deficient conditions.But it was a complicated process that the phytoplankton growth was influenced by NO and iron, which was controlled by the NO concentration, the nutrition level of the culture medium and the iron concentration, etc.Meanwhile, the iron concentration in the medium also has a direct influence on the growth and NO release capacity of the algae.Therefore, the effects of NO and iron on the growth of marine phytoplankton were mutual.

Brown algae (Chromista, Ochrophyta, Phaeophyceae) are a large group of multicellular algae that play important roles in the ocean's ecosystem and biodiversity. However, poor molecular bases for studying their phylogenetic evolutions and novel metabolic characteristics have hampered progress in the field. In this study, we sequenced the de novo transcriptome of 18 major species of brown algae in China, covering six orders and seven families, using the high-throughput sequencing platform Illumina HiSeq 2000. From the transcriptome data of these 18 species and publicly available genome data of Ectocarpus siliculosus and Phaeodactylum tricornutum, we identified 108 nuclear-generated orthologous genes and clarified the phylogenetic relationships among these brown algae based on a multigene method. These brown algae could be separated into two clades: Clade Ishigeales-Dictyotales and Clade Ectocarpales-Laminariales-Desmarestiale-Fucales. The former was at the base of the phylogenetic tree, indicating its early divergence, while the latter was divided into two branches, with Order Fucales diverging from Orders Ectocarpales, Laminariales, and Desmarestiale. In our analysis of taxonomy-contentious species, Sargassum fusiforme and Saccharina sculpera were found to be closely related to genera Sargassum and Saccharina, respectively, while Petalonia fascia showed possible relation to genus Scytosiphon. The study provided molecular evidence for the phylogenetic taxonomy of brown algae.

Coralline algae (CA), a type of primary calcifying producer presented in coastal ecosystems, are considered one of the highly sensitive organisms to marine environmental change. However, experimental studies on coralline algae responses to elevated seawater temperature and reduced pH have documented either contradictory or opposite results. In this study, we analysed the growth and physiological responses of coralline algae Porolithon onkodes to the elevated temperature (30.8°C) and reduced pH (7.8). The aim of this analysis was to observe the direct and combined effects, while elucidating the growth and photosynthesis in this response. It was demonstrated that the algae thallus growth rate and photosynthesis under elevated temperature were depressed by 21.5% and 14.9% respectively. High pCO₂ enhanced the growth and photosynthesis of the thallus at ambient temperature, while they were deceased when both temperature and pCO₂ were elevated. CA is among the most sensitive organisms to ocean acidification (OA) because of their precipitate high Mg-calcite. We hypothesize that coralline algae could increase their calcification rate in order to counteract the effects of moderate acidification, but offset by the effect of elevated temperature. Accordingly, our results also support the conclusion that global warming (GW) is a stronger threat to algal performance than OA. Our findings are also proposed that coralline algae may be more resilient under OA than GW.

The process of adsorption of Cu²⁺, Cd²⁺ by immobilized marine algae was investigated.It can be noted from the results that, the process for biosorption of heavy metals (copper, cadmium) by immobilized Laminaria japonica can be described by the Banerm model.According to the model, the adsorption rate constant calculated was 0.107 8 and 0.030 28 min^-1 for Cu²⁺ and Cd²⁺ respectively.The experimental biosorption equilibrium data for Cu²⁺ and Cd²⁺ were in good agreement with those calculated by the Langmuir model.The maximum uptake capacity calculated was 83.3 and 112.4 mg/g for Cu²⁺ and Cd²⁺ according to the Langmuir model, respectively.The appetency of Laminaria japonica to Cu²⁺was better than Cd²⁺.