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C ooley D.R., M ullins R.F., B radley P.M. and W ilce R.T. 2011. Culturing the upper littoral zone marine alga induces pathogenic interaction with the fungus . Phycologia 50: 541-547. DOI: 10.2216/10-84.1 The green marine alga (Willie 1901) occurs on hard substratum in the upper littoral in the North Atlantic Ocean. In recent field and laboratory studies, grew normally in situ but declined in vitro. Microscopic examination showed the alga inoculum to be associated with a filamentous fungus, where the fungus grew in close association with the alga. samples collected from Ipswich, MA during a two-year period were consistently associated with the fungus. In cultures with the fungus present, algal thalli declined and became necrotic, while the fungus produced hyphae and conidia. The fungus failed to grow in sterile algal medium in the absence of but could be isolated and grown on standard mycological culture media. Light and scanning electron microscopy showed fungal hyphae infiltrated intercellular areas of the algal filaments but did not penetrate algal cell walls. Pathogenicity is apparently a result of the in vitro environment, and it is hypothesized that the fungus produces one or more secondary metabolites, which accumulate in culture. These metabolites produced by the fungus eventually killed algal cells. Fungal ribosomal DNA sequences were compared to sp. in GenBank, indicating that the fungus is (Fresenius) de Vries. Widely distributed, has been shown to be a facultative parasite, endophyte and saprophyte on terrestrial plants and some algae. The fungus has not been described in association with an ulvophyte, a green marine alga. [ABSTRACT FROM AUTHOR]

Study of the north Alaskan brown algal epiphyte Chukchia pedicellata sp. nov. suggests an apparently close relationship to Phaeostroma. Phaeostroma endophyticum S. Lund from east Greenland, Bylot Island, Nunavut, Canada, shows generic identity with Chukchia and specific differences from C. pedicellata. Comparison of C. pedicellata and P. pustulosum Kuck. (the type species of Phaeostroma) shows morphological, cytological, reproductive, and distributional differences. We recognize novelty of C. pedicellata and necessity to broaden the species description of P. endophyticum, which becomes Chukchia endophytica. C. endophytica is distinguished by its dimorphic vegetative habit, its large plurilocular sporangia, and the putative ability of the sporangia to digest host tissue to accommodate development within the host. Absence of pyrenoids and novel plurilocular sporangia in both species suggests that they are not members of the Ectocarpales, sensu lato. [ABSTRACT FROM AUTHOR]

Waernia mirabilis Wilce, Maggs et Sears, gen. et sp. nov., is described for an encrusting red alga endemic to the northeastern North Atlantic Ocean. Its perennial thalli form major understory populations that may outcompete Corallinaceae and Hildenbrandiaceae in some habitats. Crustose red algae with isomorphic gametophytes and tetrasporophytes other than Corallinaceae are poorly known; Waernia differs vegetatively and reproductively from any other such algae. Gametangia are similar to those of the monotypic uncalcified crustose genera Blinksia and Gainia endemic to the Antarctic and central coastal California, respectively. Comparison of Waernia with type material of Blinksia californica Abbott & Hollenberg and Gainia mollis Moe shows that it differs from Blinksia in lacking cohesive crusts in which adjacent cells cohere by direct fusions and by its strongly recurved, rather than straight, carpogonial branches. Gainia and Waernia both have strongly recurved carpogonial branches and laxly constructed crusts that lack secondary pit connections. Gainia differs from Waernia in its considerably larger and thicker crusts, non-nemathecial tetrasporangia, shorter carpogonial branches, and its consistently single gonimoblast initial. We continue to recognize the family Blinksiaceae as a probable member of the Gigartinales with uncertain affinities. Waernia is assigned to the Dumontiaceae (Gigartinales), as its first described isomorphic crustose member. It is also the only genus and one of few algal species endemic to northeastern North America. Waernia either arrived at its present distribution via migration from a Tertiary polar ocean or evolved from an unknown ancestor in a newly formed boreal northwest Atlantic Ocean during post-Oligocene millennia. [ABSTRACT FROM AUTHOR]

Waernia mirabilis Wilce, Maggs et Sears, gen. et sp. nov., is described for an encrusting red alga endemic to the northeastern North Atlantic Ocean. Its perennial thalli form major understory populations that may outcompete Corallinaceae and Hildenbrandiaceae in some habitats. Crustose red algae with isomorphic gametophytes and tetrasporophytes other than Corallinaceae are poorly known; Waernia differs vegetatively and reproductively from any other such algae. Gametangia are similar to those of the monotypic uncalcified crustose genera Blinksia and Gainia endemic to the Antarctic and central coastal California, respectively. Comparison of Waernia with type material of Blinksia californica Abbott & Hollenberg and Gainia mollis Moe shows that it differs from Blinksia in lacking cohesive crusts in which adjacent cells cohere by direct fusions and by its strongly recurved, rather than straight, carpogonial branches. Gainia and Waernia both have strongly recurved carpogonial branches and laxly constructed crusts that lack secondary pit connections. Gainia differs from Waernia in its considerably larger and thicker crusts, non-nemathecial tetrasporangia, shorter carpogonial branches, and its consistently single gonimoblast initial. We continue to recognize the family Blinksiaceae as a probable member of the Gigartinales with uncertain affinities. Waernia is assigned to the Dumontiaceae (Gigartinales), as its first described isomorphic crustose member. It is also the only genus and one of few algal species endemic to northeastern North America. Waernia either arrived at its present distribution via migration from a Tertiary polar ocean or evolved from an unknown ancestor in a newly formed boreal northwest Atlantic Ocean during post-Oligocene millennia. [ABSTRACT FROM AUTHOR]

The vegetative development of juvenile and mature Dumontia contorta (S. G. Gmelin) Ruprecht is characterized. New patterns of red algal thallus development are described. Dumontia contorta has an isomorphic life history with similarity branched erect gametophytes and tetrasporophytes. Erect plants winter-spring annuals that develop from a perennating crustose stage. Vegetative development of D. contorta includes both maultiaxial and uniaxial systems. Juvenile thalli emerging from crustose bases are unbranched and entirely multiaxial; the main axis of a mature thallus is also multiaxial with the number of axial filaments decreasing acropetally as branches are initiated. Most lateral branches are uniaxial and do not rebranch. Thus, mature D. contorta is characterized by multiaxiality in the lower main axis and by uniaxiality in its branches and in the tip region of the main axis. Our study corrects a number of inaccuracies in the literature and reinterprets the pattern of thallus development in D. contorta in relation to stages of its vegetative growth. Development of D. contorta is compared with that of other higher red algae. Our results suggest an evolutionary derivation of D. contorta from the uniaxial, unbranched D. simplex. [ABSTRACT FROM AUTHOR]

Rhamnocharysis aestuarinae from Ipswich, Massachusetts, is a new species of benthic marine chrysophyta. Details are given describing its gross and fine structure morphology, its reproductive life history as understood from both field and culture studies, and its ecology and probable systematic position in the Chrysomeridaceae (Sarcinochrysidales). [ABSTRACT FROM AUTHOR]

The ultrastructure of zoosporogenesis in unilocular sporangia of Pylaiella littoralis is described. Zoosporogenesis begins with the formation of spore mother cells from intercalary vegetative cells. A meiotic division then occurs in each spore mother cell, which is usually not synchronous in each member of a spore mother cell pair. Centrioles replicate at 1 pole of the nucleus during the meiotic division, and during centriole migration, Golgi bodies and microtubules are present near the centrioles. Synaptonemal complexes have been observed in spore mother cells. Following meiosis, four nuclei are present in each sporangium and a series of mitotic divisions takes place as the sporangium enlarges. At the beginning of the mitotic period nuclei and plastids migrate to the sporangium periphery and vacuoles and vesicles gather in the middle of the sporangium. Eventually nuclei and plastids are redistributed throughout the sporangium and the mitotic divisions continue. Centriole behavior during the early stages of mitosis is similar to that which occurs in meiosis. Microtubules end near the centrioles often in amorphous material. The formation of flagella and mastigonemes occurs after the end of the mitotic period. Flagella form within the cytoplasm in vesicles, the two flagella developing in a slightly different manner. Flagella show various degrees of enclosure within the cytoplasm, this probably being related to their development. Mastigoneme formation occurs in ER cisternae and Golgi cisternae but mastigonemes were not observed in the perinuclear continuum, although it is believed this stage does occur but was overlooked. Mastigonemes are often tightly packed together in the flagellar vesicle and occur over about half of the flagellar circumference at this time. During the time of flagellum and mastigoneme formation the mass of cytoplasm in the sporangium shrinks away from the cell wall and cleavage divides up the cytoplasm into individual zoospores. During later stages of zoosporogenesis, characteristic vesicles, previously rare in the cytoplasm, develop in large numbers. Also at this time mitochondrial cristae contain tubular structures 5-10 mμ in diameter. Zoospores, when mature, are released through an aperture in the cell wall. The inner half of the cell wall of a sporangium undergoing release is partially broken down. The remnants of the inner half of the wall surround the zoospores as they are released. Flagellum and mastigoneme formation in Pylaiella are discussed in detail and compared to other organisms. Zoospore release is also discussed. [ABSTRACT FROM AUTHOR]

The ultrastructure of mitosis and cytokinesis in plurilocular gametangia of the brown alga Pylaiella littoralis is described. Interphase cells in the plurilocular gametangia are similar in most respects to cells of other brown algae. Centrioles are present in these cells but it has not been determined whether all vegetative cells have centrioles or whether they form de novo as the plurilocular gametangia begin to develop. Dark-staining amorphous material is present near the centrioles which may be involved in microtubule formation. After centriole replication and migration, a pair of centrioles is found at each nuclear pole, in an indentation or pocket of the nuclear envelope. The nucleus is then spindle-shaped. Microtubules are seen extranuclear in prophase but never intranuclear. In metaphase, microtubules are solely intranuclear, the nuclear envelope is still present, but gaps are present which are especially evident at the poles (polar fenestrae). Chromatin separation probably occurs in anaphase, although this has not been observed. In telophase, the daughter nuclei are completely separated by a large number of vacuoles and vesicles. Cytokinesis begins with the formation of a partition membrane by centripetal furrowing and also probably by fusion of small vesicles. After the partition membrane is complete, cell wall material is layed down which may originate in the Golgi complex. The mitotic and cytokinetic processes in plurilocular gametangia of Pylaiella littoralis are compared with similar mechanisms in other algae. The suggestion that both dark-staining amorphous material near the centrioles and the Golgi bodies may be responsible for microtubule formation is also discussed. [ABSTRACT FROM AUTHOR]