Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related(1). These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae(2-5), closely related to the kelps(6,7) (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic(2) approaches to explore these and other(4,5) aspects of brown algal biology further

NoteNovosphingobium tardaugens sp. nov., an oestradiol-degrading bacterium isolated from activated sludge of a sewage treatment plant in Tokyo An oestradiol-degrading bacterium isolated at a sewage treatment plant in Tokyo was studied phenotypically, genotypically and phylogenetically. Analysis of its 16S rDNA sequence, DNA base composition, whole-cell fatty acid profile and isoprenoid quinone composition, as well as the presence of sphingoglycolipid, revealed that the isolate is a member of the genus Novosphingobium. However, the sequence similarity of its 16S rDNA to those of known Novosphingobium species was no higher than 97 %, implying that the isolate is distinctive. The results of DNA-DNA hybridization experiments and physiological characterization also indicated that the isolate represents a novel Novosphingobium species, for which the name Novosphingobium tardaugens sp. nov. is proposed; strain ARI-1 T (5JCM 11434 T 5ATCCBAA-531 T 5IFO 16725 T ) is the type strain.There has been increasing concern recently over the potential of sewage treatment plant effluent to cause oestrogenic effects in aquatic fauna. Widespread sexual disruption, or so-called 'feminization', has been observed in riverine fish in several developed nations, including the UK, the USA and Japan (Folmar et al

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The reproductive strategy of a marine alga with a heteromorphic biphasic life cycle was studied by analyzing various sexual reproductive characters in light of the evolution of anisogamy. Gametophytes of Monostroma angicava were dioecious and their gametes were slightly anisogamous. Volume of gametangium, density of gametangia and area of mature gametangial parts on each gametophyte did not differ from male to female. Therefore, the reproductive biomass investment for gamete production was considered to be the same for each sex. Anisogamy in this alga appeared to be derived from the difference in the number of cell divisions during gametogenesis, because the majority of male gametangia each produced 64 (2 6 ) gametes and the female produced 32 (2 5 ) gametes. This corresponded with measurements of cell size in male and female gametes. Further, the sex ratio was 1:1 for sexually mature plants sampled at Charatsunai. Therefore, it was suggested that in the field twice as many male gametes are released as female gametes. Liberated gametes of both sexes showed positive phototaxis. The swimming velocity of freshly liberated male gametes was a little higher than that of female gametes. Male gametes had the potential to swim for ca. 72 h and female gametes for ca. 84 h. The difference in gamete motility between the two sexes seemed to be related to cell size. Planozygotes were negatively phototactic and swam more rapidly than gametes of either sex.& k w d : Key words Evolution of anisogamy · Gamete motility dimorphism · Monostroma angicava · Reproductive investment& b d y :T. Togashi ( u ) · T. Motomura · T. Ichimura

SUMMARY The nuclear ribosomal DNA internal transcribed spacer (ITS‐1 and ITS‐2) sequences were determined for 10 of 12 Japanese non‐digitate Laminaria species, Kjell‐maniella gyrata (Kjellman) Miyabe, Costaria costata (Turner) Saunders, Alaria praelonga Kjellman and Chorda filum (L.) Stackhouse collected at Hokkaido. Phyloge‐netic analyses (maximum parsimony and distance matrix) of these sequences, including published data for L. sac‐charina (L.) Lamouroux from Canada, showed strong nucleotide conservation among these species of Laminaria, but two phylogenetically distinct species groups were recognized. A L. japonica group encompassing L. yapon/ca Areschoug, L. religiosa Miyabe, L. ochotensis Miyabe, L. diabolica Miyabe, L. longipedalis Okamura, L. angustata Kjellman and L. longissima Miyabe; and a L. saccharina group including L. coriacea Miyabe, L. sac‐charina, L. cichorioides Miyabe and L. yendoana Miyabe. As to other laminarialean genera, Kjellmaniella gyrata was most closely related to the genus Laminaria, being related to the second Laminaria species group based on both parsimony and distant tree values.

Brown algae are one of the most developmentally complex groups within the eukaryotes. As in many land plants and animals, their main body axis is established early in development, when the initial cell gives rise to two daughter cells that have apical and basal identities, equivalent to shoot and root identities in land plants, respectively. We show here that mutations in the Ectocarpus DISTAG (DIS) gene lead to loss of basal structures during both the gametophyte and the sporophyte generations. Several abnormalities were observed in the germinating initial cell in dis mutants, including increased cell size, disorganization of the Golgi apparatus, disruption of the microtubule network, and aberrant positioning of the nucleus. DIS encodes a TBCCd1 protein, which has a role in internal cell organization in animals, Chlamydomonas reinhardtii, and trypanosomes. Our study highlights the key role of subcellular events within the germinating initial cell in the determination of apical/basal cell identities in a brown alga and emphasizes the remarkable functional conservation of TBCCd1 in regulating internal cell organization across extremely distant eukaryotic groups.

The new type blue light (BL) receptor aureochrome (AUREO) was recently discovered in a stramenopile alga, Vaucheria (Takahashi et al. Proc Natl Acad Sci USA 104(49):19625-19630, 2007). AUREO has a bZIP (basic region/leucine zipper) and BL-sensing light-oxygen-voltage (LOV) domain and functions as a BL-activated transcription factor. It mediates BL-induced branching and regulates the development of the sex organ in V. frigida. Although AUREO sequences have previously been found in Fucus and some diatoms, here we report that AUREO orthologs are commonly conserved in photosynthetic stramenopiles. Five AUREO orthologs were isolated from three stramenopile genera (Fucus, Ochromonas, and Chattonella). By BLAST search, several AUREO sequences were also detected in genomes in Aureococcus anophagefferens (Pelagophyceae). However, AUREO was not found in heterotrophic stramenopiles or in closely related phyla, such as haptophytes and cryptophytes, or in green plants. Stramenopiles do not possess phototropin, the well-known BL receptor for phototropism of green plants. From comparative analysis of LOV domains, together with kinship analysis of AUREO bZIP domains, AUREO can be regarded as the BL receptor specific to phototrophic stramenopiles. The evolution of AUREO and the phylogeny of LOV domains in stramenopiles and green plants are discussed.

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