Progress in molecular and subcellular biology最新文献

The siliceous sponges, the demosponges and hexactinellid glass sponges, are unique in their ability to form biosilica structures with complex architectures through an enzyme-catalyzed mechanism. The biosilica skeleton of these sponges with its hierarchically structure and exceptional opto-mechanical properties has turned out to be an excellent model for the design of biomimetic nanomaterials with novel property combinations. In addition, biosilica shows morphogenetic activity that offers novel applications in the field of bone tissue engineering and repair. In recent years, much progress has been achieved towards the understanding of the principal enzymes, the silicateins that form the sponge skeletal elements, the spicules, and their self-assembling and structure-guiding properties. The discovery of the silicatein-interacting, scaffolding proteins provided new insights in the mechanism of spiculogenesis. The now available toolbox of enzymes and proteins that are involved in biosilica formation and the biosilica material synthesized by them are of great interest for a variety of applications from nanobiotechnology to nanomedicine.

Fungal diseases are problematic in cultured fish and shellfish, their seeds, and sometimes wild marine animals. In this chapter fungal diseases found in marine animals, especially in Japan, are described. Pathogens in the fungal diseases are divided into two groups. One of them is marine Oomycetes, which cause fungal diseases in marine shellfish and abalones. The diseases caused by the fungi of this group and the fungal characteristics are introduced. The pathogens include members of the genera Lagenidium, Haliphthoros, Halocrusticida, Halioticida, Atkinsiella, and Pythium. On the other hand, some fungal diseases caused by mitosporic fungi are also known in marine fish and shellfish. The diseases caused by these fungi and the fungal characteristics are described. The pathogens include members of the genera Fusarium, Ochroconis, Exophiala, Scytalidium, Plectosporium, and Acremonium.

Solar salterns are constructed as shallow multi-pond systems for the production of halite through evaporation of seawater. The main feature of salterns is the discontinuous salinity gradient that provides a range of well-defined habitats with increasing salinities, from moderate to hypersaline. These present one of the most extreme environments, because of the low levels of biologically available water and the toxic concentrations of ions. Up to the year 2000, hypersaline environments were considered to be populated almost exclusively by prokaryotic microorganisms till fungi were reported to be active inhabitants of solar salterns. Since then, numerous fungal species have been described in hypersaline waters around the world. The mycobiota of salterns is represented by different species of the genus Cladosporium and the related meristematic melanized black yeasts, of non-melanized yeasts, of the filamentous genera Penicillium and Aspergillus and their teleomorphic forms (Eurotium and Emericella), and of the basidiomycetous genus Wallemia. Among these, two species became new model organisms for studying the mechanisms of extreme salt tolerance: the extremely halotolerant ascomycetous black yeast Hortaea werneckii and the obligate halophilic basidiomycete Wallemia ichthyophaga.

Three hundred and fifty woody litter and one hundred and forty seaweed litter sampled from seven beaches of Northwest Portugal were assessed for the filamentous fungal assemblage and diversity. The woody litter was screened for fungi up to 42 months using damp chamber incubation. They consisted of 36 taxa (ascomycetes, 21; basidiomycetes, 3; anamorphic taxa, 12) comprising 10 core group taxa (≥10%) (ascomycetes, 8; basidiomycete, 1; anamorphic taxa, 1). The total fungal isolates ranged between 150 and 243, while the number of fungal taxa per wood ranged between 3 and 4.9. The seaweed litter was screened up to four months in damp chamber incubation. They encompassed 29 taxa (ascomycetes, 16; basidiomycetes, 2; anamorphic taxa, 11) comprising 15 core group taxa (ascomycetes, 9; basidiomycete, 1; anamorphic taxa, 5). Total fungal isolates ranged between 56 and 120, while the number of fungal taxa per seaweed segment ranged between 4.8 and 6.3. Fifteen taxa of ascomycetes, two of basidiomycetes, and four anamorphic taxa were common to wood and seaweed litter. On both the substrates, two arenicolous fungi Arenariomyces trifurcates and Corollospora maritima were the predominant fungi (72.6-85.9%). The species abundance curves showed higher frequency of occurrence of fungal taxa in seaweed than woody litter. Our study revealed rich assemblage and diversity of marine fungi on wood and seaweed litter of Northwest Portugal beaches. The fungal composition and diversity of this survey have been compared with earlier investigations on marine fungi of Portugal coast.

Molecular diversity surveys of marine fungi have demonstrated that the species richness known to date is just the tip of the iceberg and that there is a large extent of unknown fungal diversity in marine habitats. Reports of novel fungal lineages at higher taxonomic levels are documented from a large number of marine habitats, including the various marine oxygen-deficient environments (ODEs). In the past few years, a strong focus of eukaryote diversity research has been on a variety of ODEs, as these environments are considered to harbor a large number of organisms, which are highly divergent to known diversity and could provide insights into the early eukaryotic evolution. ODEs that have been targeted so far include shallow water sediments, hydrothermal vent systems, deep-sea basins, intertidal habitats, and fjords. Most, if not all, molecular diversity studies in marine ODEs have shown, that contrary to previous assumptions, fungi contribute significantly to the micro-eukaryotic community in such habitats. In this chapter, we have reanalyzed the environmental fungal sequences obtained from the molecular diversity survey in 14 different sites to obtain a comprehensive picture of fungal diversity in these marine habitats. The phylogenetic analysis of the fungal environmental sequences from various ODEs have grouped these sequences into seven distinct clades (Clade 1-7) clustering with well-known fungal taxa. Apart from this, four environmental clades (EnvClade A, B, C, and D) with exclusive environmental sequences were also identified. This has provided information on the positioning of the environmental sequences at different taxonomic levels within the major fungal phylums. The taxonomic distribution of these environmental fungal sequences into clusters and clades has also shown that they are not restricted by geographical boundaries. The distribution pattern together with the reports on the respiratory abilities of fungi under reduced oxygen conditions shows that they are highly adaptive and may have a huge ecological role in these oxygen deficient habitats.

Filamentous fungi are the most widely used eukaryotes in industrial and pharmaceutical applications. Their biotechnological uses include the production of enzymes, vitamins, polysaccharides, pigments, lipids and others. Marine fungi are a still relatively unexplored group in biotechnology. Taxonomic and habitat diversity form the basis for exploration of marine fungal biotechnology. This review covers what is known of the potential applications of obligate and marine-derived fungi obtained from coastal to the oceanic and shallow water to the deep-sea habitats. Recent studies indicate that marine fungi are potential candidates for novel enzymes, bioremediation, biosurfactants, polysaccharides, polyunsaturated fatty acids and secondary metabolites. Future studies that focus on culturing rare and novel marine fungi, combined with knowledge of their physiology and biochemistry will provide a firm basis for marine mycotechnology.

In the Halosphaeriaceae, taxa with unfurling ascospore appendages and related species constitute 61 species (in 21 genera). Recent phylogenetic analyses of the rRNA genes have advanced our knowledge on the relationships between genera in the family, especially the group with unfurling ascospore appendages. However, many new genera resulting from these studies lack distinctive morphological characteristics from closely related taxa. In this chapter, peridial wall layers of the ascomata and morphology of asci and ascospores are re-examined to determine if these structures offer useful information for the delineation of genera. In particular, shape parameters (aspect ratio, convexity, elongation, shape factor, sphericity, area, perimeter, diameter max, diameter mean and diameter min) of ascospores were calculated to determine if these parameters can provide extra characters for the delineation of taxa. Results suggest that peridial wall structure alone is insufficient to separate genera in the Halosphaeriaceae. Shape parameters of ascospores can provide additional characters but more taxa are required to test their efficacy. Ascus shape and length of stalk are further characters that should be calculated for taxonomical consideration. Morphology of the ascomatal wall and shape of asci and ascospores in genera with unfurling ascospore appendages in the Halosphaeriaceae are partially concordant with their phylogeny, suggesting a more thorough examination of these characters for the delineation of taxa in the family.

The importance of fungi found in deep-sea extreme environments is becoming increasingly recognized. In this chapter, current scientific findings on the fungal diversity in several deep-sea environments by conventional culture and culture-independent methods are reviewed and discussed, primarily focused on culture-independent approaches. Fungal species detected by conventional culture methods mostly belonged to Ascomycota and Basidiomycota phyla. Culture-independent approaches have revealed the presence of highly novel fungal phylotypes, including new taxonomic groups placed in deep branches within the phylum Chytridiomycota and unknown ancient fungal groups. Future attempts to culture these unknown fungal groups may provide key insights into the early evolution of fungi and their ecological and physiological significance in deep-sea environments.

Phthalate esters (PAEs) are important industrial compounds mainly used as plasticizers to increase flexibility and softness of plastic products. PAEs are of major concern because of their widespread use, ubiquity in the environment, and endocrine-disrupting toxicity. In this study, two fungal strains, Fusarium sp. DMT-5-3 and Trichosporon sp. DMI-5-1 which had the capability to degrade dimethyl phthalate esters (DMPEs), were isolated from mangrove sediments in the Futian Nature Reserve of Shenzhen, China, by enrichment culture technique. These fungi were identified on the basis of spore morphology and molecular typing using 18S rDNA sequence. Comparative investigations on the biodegradation of three isomers of DMPEs, namely dimethyl phthalate (DMP), dimethyl isophthalate (DMI), and dimethyl terephthalate (DMT), were carried out with these two fungi. It was found that both fungi could not completely mineralize DMPEs but transform them to the respective monomethyl phthalate or phthalate acid. Biochemical degradation pathways for different DMPE isomers by both fungi were different. Both fungi could transform DMT to monomethyl terephthalate (MMT) and further to terephthalic acid (TA) by stepwise hydrolysis of two ester bonds. However, they could only carry out one-step ester hydrolysis to transform DMI to monomethyl isophthalate (MMI). Further metabolism of MMI did not proceed. Only Trichosporon sp. was able to transform DMP to monomethyl phthalate (MMP) but not Fusarium sp. The optimal pH for DMI and DMT degradation by Fusarium sp. was 6.0 and 4.5, respectively, whereas for Trichosporon sp., the optimal pH for the degradation of all the three DMPE isomers was at 6.0. These results suggest that the fungal esterases responsible for hydrolysis of the two ester bonds of PAEs are highly substrate specific.

Microbial communities play critical biogeochemical roles in the functioning of marine ecosystems. Recent advances in molecular methods and environmental genomics have greatly advanced our understanding of microbial prokaryotes and their diversity and functional ecology in the world's oceans. Large populations of heterotrophic eukaryotes are well documented in the oceans and yet, their diversity and function remain relatively unknown. Particularly, large populations of planktonic fungi have long been known to exist in coastal and oceanic waters but the diversity and ecology of planktonic fungi remain one of the most under-studied microbial topics. Recent studies have revealed novel diversity and interesting ecological functions of planktonic fungi and suggest that they are a potentially important component in marine microbial food web. This chapter will review the diversity and ecology of planktonic fungi in the world's oceans and discuss their significance in ocean carbon and nutrient cycling.