The filamentous fungi associated with healthy and decaying Fucus serratus thalli were studied over a 1-year period using isolation methods and molecular techniques such as 28S rRNA gene PCR-denaturing gradient gel electrophoresis (DGGE) and phylogenetic and real-time PCR analyses. The predominant DGGE bands obtained from healthy algal thalli belonged to the Lindra, Lulworthia, Engyodontium, Sigmoidea/Corollospora complex, and Emericellopsis/Acremonium-like ribotypes. In the culture-based analysis the incidence of recovery was highest for Sigmoidea marina isolates. In general, the environmental sequences retrieved could be matched unambiguously to isolates recovered from the seaweed except for the Emericellopsis/Acremonium-like ribotype, which showed 99% homology with the sequences of four different isolates, including that of Acremonium fuci. To estimate the extent of colonization of A. fuci, we used a TaqMan real-time quantitative PCR assay for intron 3 of the beta-tubulin gene, the probe for which proved to be species specific even when it was used in amplifications with high background concentrations of other eukaryotic DNAs. The A. fuci sequence was detected with both healthy and decaying thalli, but the signal was stronger for the latter. Additional sequence types, representing members from the Dothideomycetes, were recovered from the decaying thallus DNA, which suggested that a change in fungal community structure had occurred. Phylogenetic analysis of these environmental sequences and the sequences of isolates and type species indicated that the environmental sequences were novel in the Dothideomycetes.Coastal macrophytes are part of highly productive ecosystems and have essential functions in nutrient cycling and habitat structuring (8,30). Helgoland intertidal marine seaweed populations are dominated by fucoids with diverse associated biocenoses. The complex communities that develop in these systems provide models for investigating algafungus interactions in a natural environment. Pathogens and parasites are the predominant fungi in seaweed communities that have been described (47); however, most of these organisms cannot be cultured in the laboratory and are known only from herbarium specimens (26, 39). Other algicolous fungi include saprobes and mycobionts, and there is little information on the autecology of these organisms. Studies of the interactions between these fungi and their algal hosts, therefore, can be effectively undertaken only by using a molecular approach to detect and differentiate between environmental signal sequences.In a preliminary study of fungi associated with Fucus serratus, Zuccaro et al. (48) developed and described a PCRdenaturing gradient gel electrophoresis (DGGE) system, using novel fungus-specific primers that amplified the second domain (D2) of the nuclear large rRNA region. Fungal sequences retrieved from algal tissue matched sequences from ascomycetous groups known to be active in marine environments, as well as sequences from a group of isolates belonging to the genu...

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Nucleosome assembly proteins have been identified in all eukaryotic species investigated to date and their suggested roles include histone shuttle, histone acceptor during transcriptional chromatin remodelling and cell cycle regulator. To examine the role of these proteins during early development we have isolated the cDNA encoding Xenopus NAP1L, raised an antibody against recombinant xNAP1L and examined the expression pattern of this mRNA and protein. Expression in adults is predominantly in ovaries. This maternal protein remains a major component of xNAP1L within the embryo until swimming tadpole stages. xNAP1L mRNA is initially throughout the embryo but by gastrula stages it is predominantly in the presumptive ectoderm. Later, mRNA is detected in the neural crest, neural tube, eyes, tailbud and ventral blood islands. In order to test whether xNAP1L has a potential role in gene regulation we overexpressed this protein in animal pole explants and tested the effect on expression of a series of potential target genes. The mRNA encoding the transcription factor GATA-2 was markedly up-regulated by this overexpression. These data support a role for xNAP1L in tissue-restricted gene regulation.

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