Rhodophycean Pit Plugs: An Ultrastructural Survey with Taxonomic Implications

Pueschel, Curt M.; Cole, Kathleen M.

doi:10.2307/2442960

Cited by 90 publications

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“…New anatomical features, including the presence or absence of cap membranes and the number of cap layers formed at the cytoplasmic faces of pit plugs, further supported recognition of the Palmariales (Pueschel & Cole, 1982), while heterogeneity observed in pit-plug ultrastructure in the Nemaliales and Cryptonemiales resulted in the proposal of several new orders. Pueschel & Cole (1982) made a number of taxonomic recommendations including, for the Nemaliales: resurrecting the Gelidiales, moving the Bonnemaisoniaceae and Naccariaceae to the Bonnemaisoniales, and assigning the freshwater families Batrachospermaceae, Lemaneaceae and Thoreaceae to the new order Batrachospermales. The heterogeneous Cryptonemiales was also reduced by the removal of discordant families to new orders, the Hildenbrandiales (Pueschel & Cole, 1982) and the Corallinales (Silva & Johansen, 1986).…”

Section: Introductionmentioning

confidence: 92%

Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov.

Withall

Saunders

2006

European Journal of Phycology

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Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov. Published phylogenies based on nuclear small-subunit (SSU) ribosomal DNA have largely failed to resolve ordinal relationships within the Rhodymeniophycidae. Of the nine orders currently recognized, SSU analyses only consistently resolved an association between the Halymeniales and Rhodymeniales. This situation was confounded by an unexpected association between the Rhodymeniales and Gracilariales shown in published combined SSU þ LSU (large subunit ribosomal DNA) phylogenies. To investigate this conundrum further, nuclear SSU and LSU sequences were determined to produce a comprehensive combined data set of 61 ingroup taxa, representing 22 families within the Rhodymeniophycidae, emphasizing disparate lineages of the Gigartinales sensu lato. Molecular phylogenies were constructed from individual gene and combined data sets in an effort to achieve increased ordinal resolution. The new analyses realized little increased resolution among the orders, but they did resolve the conflicting taxonomic affinities of the Rhodymeniales indicating that they ally with the Halymeniales and not the Gracilariales. The latter order was affiliated to the Nemastomatales in all SSU-only analyses, as well as for SSU þ LSU combined Bayesian results with the covarion option invoked. In addition, the resulting phylogenetic hypotheses have shed light on the taxonomic associations of a few rogue families of the Gigartinales sensu lato. Notably, the Acrosymphytaceae failed to join other families of the Gigartinales and we therefore propose the Acrosymphytales ord. nov. to accommodate this family. The Sebdeniaceae was generally weakly allied as sister to the Rhodymeniales rather than with the Halymeniales where it is currently placed. Owing to its consistently equivocal placement in contemporary molecular analyses, as well as a suite of anatomical characters intermediate between the Halymeniales sensu stricto and Rhodymeniales, we here propose the Sebdeniales ord. nov.

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Section: Introductionmentioning

confidence: 92%

Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov.

Withall

Saunders

2006

European Journal of Phycology

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“…The presence of additional structural components such as cap membranes and/or cap layers depends on the taxonomic group involved (Pueschel and Cole, 1982;Pueschel, 1989). Although the size and shape of the plugs vary greatly in representatives of the Ceramiales, the absence of plug caps has been consistent (Pueschel and Cole, 1982;Pueschel, 1989).…”

Section: Discussionmentioning

confidence: 99%

“…Pit-plug ultrastructure in combination with molecular data have led to a considerable restructuring of red algal classification at the ordinal level (Pueschel and Cole, 1982;Pueschel, 1989;Harper and Saunders, 2001). However, recent molecular systematic studies have not dealt with the taxonomic levels of families or genera and taxa within the families.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructure of auxiliary and gonimoblast cells during carposporophyte development in the red alga Cryptopleura ruprechtiana (Delesseriaceae, Ceramiales, Rhodophyta)

Delivopoulos

2003

Biology of the Cell

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The ultrastructure sequence for the complete post-fertilization development is described in Cryptopleura ruprechtiana (C. Agardh) Kylin, a member of the Delesseriaceae. Following fertilization the diploid nucleus is transferred to the auxiliary cell. This contains typical red algal proplastids, cytoplasmic concentric membranes, numerous small vacuoles and lipid bodies. Crystalline inclusions and virus-like particles are also present. In addition darkly staining spherical masses possibly represent dehydrated haploid chromatin. The multinucleate auxiliary cell produces initially one large gonimoblast initial and subsequently many smaller gonimoblast initials. The first formed generative gonimoblast cell is similar in cellular structure to the auxiliary cell. Gonimoblast initials are uninucleate but through caryokinesis they become multinucleate. They undergo repeated cleavage to form more gonimoblast cells. Subsequent, centripetal cytokinesis results in the formation of clusters of gonimoblast cells. A new type structural cap or association is observed in the septal plugs that interconnect gonimoblast initials. Terminal or generative gonimoblast cells cleave to form additional gonimoblast cells. Only terminal gonimoblast cells are differentiated to carpospores.

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“…Les synapses des Rhodophycées ont été classées en trois types fondamentaux (Pueschel et Cole, 1982;Pueschel, 1987). Chez H. kjellmanii et D. ramentacea, son hôte, les synapses appartiennent au même type, avec un capuchon (plug cap) composé de deux couches de densités différentes.…”

Section: Discussionunclassified

“…Malgré cela, elles restent parfaitement identifiables. Chez l'hôte, la couche externe est toujours continue dans les synapses hien diffé-renciées ; par contre, dans les synapses du parasite, la couche externe du capuchon pré-sente régulièrement de nombreuses interruptions ce qui a été interprété comme une forme juvénile de la synapse chez Palmaria palmata et Rhodophysema georgii (Pueschel et Cole, 1982). Cet aspect semble représenter l'image permanente de l'appareil synaptique de l'H.…”

Section: Discussionunclassified

Halosacciocolax kjellmaniiparasite arctique deDevaleraea ramentacea(Palmariales,Rhodophyta): Organisation et rapports hôte-parasite

Jónsson¹,

Chesnoy²

1988

Bulletin de la Société Botanique de France. Lettres Botaniques

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Résumé.-Halosacciocolax kjellmanii Lund, parasite du Devaleraea ramentacea (L.) Guiry de l'Islande est une Floridée incolore dont les plastes ne contiennent que rarement quelques thylacoïdes. Le parasite possède des synapses avec un capuchon (plug cap) constitué de deux couches de densité différente. Le capuchon diffère de celui de son hôte par des interruptions dans la couche externe. Des anastomoses cellulaires existent entre les cellules d'un même filament et entre filaments voisins; il n'a pas été observé de synapses secondaires.Les cellules du cortex de l'hôte réagissent au parasite par augmentation du volume vacuolaire. Le parasite et son hôte établissent des liens par fusions cellulaires qui aboutissent à de grandes cellules mixtes nécrosées.Des spermatocystes, identiques à ceux connus seulement dans du matériel du Groënland, ont été observés dans le matériel islandais. Les tétrasporocystes, très fréquents, sont régénérés par une cellule pied. Les tétraspores mises en culture en l'absence de l'hôte germent, mais sont incapables de survie. Des organes femelles n'ont pas été obseNés. La position systématique du parasite reste donc incertaine.Summary.-Light and electron microscope studies of llalosacciocolax kjellmanii Lund, parasite on Devaleraea ramentacea (L.) Guiry from lceland, have revealed that the parasite is basically an uniseriate filamentous and ramified organism, bearing spermatangia and tetrasporangia. Cell fusions occur between parasite cells as weil as between host cells.Piastids are highly reduced, almost lacking internai thylacoid development. Two layered plug caps were found bath in parasite and host. However, the outer plug layer is constantly composed of electron dense plaques in parasite. Secondary pit connections between parasite cells or between parasite and host cells were not observed.Evidence suggests that host-parasite association is established by cell fusions leading to formation of large mixed cells situated between parasite and host. After fusion mixed cells contain altered but recognizable organelles from bath host and parasite. Later these cells campletely degenerate.Host responses to the parasite were fou nd to be an hypertrophy of cortical cells as a result of increased vacuolation and a cytoplasmic alteration. Occasionally conspicuous cytoplasmic con-(*)Manuscrit reçu le 10 décembre 1987; accepté le 5 février 1988. LETTRES BOTANIQUEStractions occur in parasite cells. They are presumably due to swelling of cell walls during fixation.Spermatangia, exhibiting characteristic clavate androphores similar to those previously known only in material from Greenland, appear to be rare in the lcelandic material. They were met with in the northernmost area of our survey during late summer. Tetrasporangia which are much more constant, are regenerated many times after release of tetraspores by a stalk cell which structurally does not differ from ordinary vegetative cells of the thallus. Tetraspores kept in hostfree culture gave rise to small colourless non-viable dises. Female organs w...

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Rhodophycean Pit Plugs: An Ultrastructural Survey with Taxonomic Implications

Cited by 90 publications

References 0 publications

Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov.

Combining small and large subunit ribosomal DNA genes to resolve relationships among orders of the Rhodymeniophycidae (Rhodophyta): recognition of the Acrosymphytales ord. nov. and Sebdeniales ord. nov.

Ultrastructure of auxiliary and gonimoblast cells during carposporophyte development in the red alga Cryptopleura ruprechtiana (Delesseriaceae, Ceramiales, Rhodophyta)

Halosacciocolax kjellmaniiparasite arctique deDevaleraea ramentacea(Palmariales,Rhodophyta): Organisation et rapports hôte-parasite

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