Number Of Pyrenoids Research Articles

A New Deep-Water Epilithic Green Alga, Ulvella lacustris, from an Alpine Brackish Lake in Qinghai–Tibet Plateau

Ulvella species are widely distributed in ocean and freshwater habitats and from high latitudes to the tropics. However, no species of this genus have been found in the Qinghai–Tibetan Plateau. In the present study, five rock specimens were collected from the bottom of Qinghai Lake at a depth of about 15–28 m, from which three unialgal strains were isolated. These strains were characterized by prostrate pseudoparenchyma, irregular or radial branch filaments, and mono- or polystromatic discs or rosettes formed by consecutive filaments, with thalli that can grow up to 180 um in length, suggesting that they may be Ulvella species. Phylogenetic analysis based on 18S rDNA and tufA cpDNA sequences revealed that the isolates formed a strong branch among other Ulvella species and were closely related to Ulvella leptochaete and Ulvellawaernii. This result was also confirmed by neighbor-joining tree inference based on ITS2 secondary structure. Unlike other members of Ulvella, the isolated strain was characterized by its unique habitat, field morphology of thallus, size of vegetative cells, and number of pyrenoids. Based on these morphological differences, the phylogenetic analysis, and the comparison of ITS2 secondary structure with relative species, the strain isolated in this study was proposed to be a novel Ulvella sp. The alga was found on the bottom of brackish lakes on the Qinghai–Tibetan Plateau, which meant that our sampling range needed to be expanded further.

Rhodachlya westii sp. nov. (Rhodachlyales, Rhodophyta), a new species from Brazil, revealed by an integrative taxonomic approach

ABSTRACT A small red alga was isolated into culture from rhodoliths collected on the Piauí coast, northeastern Brazil. Molecular data from the plastid-encoded rbcL gene, combined with morphological and ultrastructural evidence, demonstrated that it belongs to the genus Rhodachlya and supports the proposal of a new species, R. westii. The new species was characterised by basal and erect uniseriate filaments, cells with parietal H-shaped or lobed plastids with one or two prominent pyrenoids, absence of unicellular hairs, and with monosporangia sessile or on branched stalks. Ultrastructure revealed pit plugs with two cap layers without a cap membrane, typical of Rhodachlyales. In our rbcL phylogeny, R. westii sp. nov. was recovered in a well-supported clade containing R. hawaiiana and R. madagascarensis (generitype) with interspecific divergence ranging from 5% to 10%, respectively. Characters previously used for species-level taxonomy (e.g. cell dimensions, number of pyrenoids and presence or absence of colourless hairs) are often plastic and overlap. We conclude that Rhodachlya species can be accurately identified only based on DNA sequence data and their geographic distribution. Rhodachlya westii becomes the third species of the genus, representing the first record in the Atlantic Ocean. Our data suggest that the genus is probably widely distributed. In view of the scarcity of reliable morphological features available for comparison, molecular-assisted alpha taxonomy is needed for uncovering the long-overlooked diversity in this red algal group.

Revision of herbarium specimens of freshwater Enteromorpha-like Ulva (Ulvaceae, Chlorophyta) collected from Central Europe during the years 1849–1959

This paper presents results concerning the taxonomic revision of Ulva taxa originating from herbarium specimens dating back to 1849–1959. A staining and softening mixture was applied to allow a detailed morphometric analysis of thalli and cells and to detect many morphological details. The study focused on individuals collected exclusively from inland water ecosystems (having no contact with sea water). Detailed analysis concerned the following items: structures of thalli and cells, number of pyrenoids per cell, configuration of cells inside the thallus, occurrence or not of branching thallus, shapes of apical cells, and shape of chromatophores. The objective of the study was to confirm the initial identifications of specimens of Ulva held in herbaria. The study sought to determine whether saltwater species of the genus Ulva, e.g., Ulva compressa and U. intestinalis, could have been found in European freshwater ecosystems in 19th and 20th centuries. Moreover, the paper presents a method for the initial treatment of voucher specimens for viewing stained cellular structures that are extremely vulnerable to damage (the oldest specimens were more than 160 years old). The use of a glycerine-based softening mixture allowed the detailed analysis of the anatomic structure of cells as well as the determination of the number and size of pyrenoids, i.e., some of the key taxonomic features of Ulva taxa. Most of specimens were identified as belonging to the species U. flexuosa. Marine species such as Ulva intestinalis or U. compressa were not confirmed to occur in the inland water ecosystems of Central Europe in the 19th and 20th centuries.

Mougeotia ag. and Spirogyra Link (Zygnemaceae) - new species for the European flora

In samples collected in Norway the following species new for Europe, <em>Mougeotia olivacea</em> Y.J. Ling,<em> Mougeotia mysorensis</em> Iyengar, <em>Spirogyra reflexa</em> Transeau and <em>Spirogyra schmidtii</em> W. et G.S. West, are identified. The diagnosis of <em>M. olivacea</em> has been supplemented with data on the dimensions of vegetative cells and zygotes and the number of pyrenoids. The diagnosis of <em>M. mysorensis</em> has been supplemented with data on the number and distribution of pyrenoids and, often curved, vegetative filaments. The sites of <em>M. olivaceas</em> and <em>M. mysorensi</em>'s occurrence are the second one in the world. Morphological features and dimensions of <em>S. reflexa</em> and <em>S. schmidtii</em> are congruent with those given from other non-European sites.

New species of freshwater Ulva, Ulva limnetica (Ulvales, Ulvophyceae) from the Ryukyu Islands, Japan

SUMMARY Ulva limnetica Ichihara et Shimada, sp. nov. (Ulvales, Ulvophyceae) is described from the Ryukyu Islands, Japan, and is characterized by thalli that are: (i) branched, tubular, fragile and wrinkled; (ii) up to 80 cm in height and up to 2 cm in diameter; (iii) light to yellowish green in color; and (iv) having an asexual reproduction by means of quadriflagellate swarmers. Rhizoidal cells bear tubular extensions on the outside of the cell layer in the stipe. Ulva limnetica is distinguished from species with similar thalli by chloroplast disposition, branching pattern, number of pyrenoids per cell and gross morphology. It is also distinguished by sequences of the nuclear‐encoded 18S ribosomal RNA gene, internal transcribed spacer 2 region and the plastid‐encoded large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxgenase gene (rbcL). Ulva limnetica was clustered with other Ulva species in an early diverging lineage within the genus.

Revision of the Genus Cryptomonas (Cryptophyceae): a Combination of Molecular Phylogeny and Morphology Provides Insights into a Long-Hidden Dimorphism

Seventy-three strains of cryptophytes assigned to the genera Cryptomonas, Campylomonas or Chilomonas were studied by light microscopy, spectrophotometry and whole-mount electron microscopy. Twelve groups of strains were distinguished by light and whole mount electron microscopy using a combination of characters, mainly cell size, type of periplast and presence/absence and number of pyrenoids. However, characters previously used to distinguish Cryptomonas from Campylomonas (e.g. the type of periplast: polygonal periplast plates vs. a continuous periplast sheet) were found to occur together in dimorphic strains, indicating that periplast types relate to different life-history stages of a single taxon. To evaluate the taxonomic significance of the type of periplast and other characters previously used to distinguish genera and species, representatives of each strain group were subjected to molecular phylogenetic analyses using two nuclear ribosomal DNA regions (ITS2, partial LSU rDNA) and a nucleomorph ribosomal gene (SSU rDNA). The results of the phylogenetic study provide molecular evidence for a life history-dependent dimorphism in the genus Cryptomonas: the genus Campylomonas represents the alternate morph of Cryptomonas. Campylomonas and Chilomonas are reduced to synonyms of Cryptomonas, the genus Cryptomonas is revised and typified, two new species are described and six species are emended.

The taxonomy ofUlva(Chlorophyceae) in the Netherlands

On the basis of 160 living samples from 26 different stations five Ulva species were distinguished, and described for the Netherlands coast, namely U. pseudocurvata nov. spec., U. curvata (Kutz.) De Toni, U. lactuca L., U. rigida C.Ag. and U. scandinavica Bliding. Unialgal cultures were isolated from these samples in order to test the validity of the taxonomic criteria and to test the growth response of germlings and young blades to varying salinities. The following criteria appeared to be taxonomically valid, though most of them are subject to wide variation: (1) macroscopic morphology (including colour and texture); (2) form and arrangement of the cells in surface view; (3) the structure of the basal region (form and size of rhizoidal cells; the presence or absence of small-celled marginal wings; the presence or absence of longitudinal rhizoidal ribs; and the presence or absence of a flat central cavity in the lower basal region and the stipe); (4) the number of pyrenoids in a vegetative cell; (5) the a...

TAXONOMIC STUDIES ON THE GENUS ULOTHRIX (ULOTRICHALES, CHLOROPHYCEAE). II

In this second report on the taxonomy of the Dutch species of Ulothrix Kützing, the morphological and reproductive characters of three other freshwater species, viz. U. mucosa Thuret, U. crenulata (Kützing) Kützing and U. verrucosa Lokhorst (nom. nov.) are discussed. U. mucosa shows some relationship with Binuclearia tectorum (Kützing) Beger ex Wichmann. These species are shown to differ in several respects, e.g. number of pyrenoids, morphology of the chloroplast, thickness of the H-pieces, morphology of basal and apical cells and structure of the zoosporangium cell wall. Close morphological resemblance exists between U. crenulata and U. verrucosa. Cell dimensions, morphology of the chloroplast and number of pyrenoids are the most important features for distinguishing these species. Both show taxonomic affinity to Klebsormidium Silva, Mattox & Blackwell. On account of chloroplast morphology, number of pyrenoids and shortening of cells the species are classified under Ulothrix. Under all photoperiods studied U. mucosa is the only species capable of reproduction by means of zoospores, whereas both other species referred to in this paper only show multiplication by fragmentation of filaments. Probably for this reason these species do not show seasonal periodicity in their occurrence in nature.

Acrochaetium botryocarpum(Harv.) J. Ag. (Rhodophyta) in Southern Australia

The morphology, ecology, cytology and systematics of Acrochaetium botryocarpum (Harv.) J. Ag. have been studied. This species occurs throughout the year in southern Australia and grows on a variety of hosts. The variable appearance of the prostrate system results from the effect of the substratum upon its morphology. Plants reach a height of 6 mm; cells of the erect filaments contain a single chromoplast with a variable number of pyrenoids. Tetrasporangial plants occur mainly in winter and sexual plants occur mainly in spring and early summer; the two generations are isomorphic. Stages of fertilisation have been observed and photographed. Acrochaetium polyrhizum (Harv.) J. Ag. is referred to the synonomy of A. botryocarpum, and A. codicolum Brg., A. grande (Levr.) De Toni fil. and A. rhizoideum (Drew) Sm. are regarded as probable synonyms. This study of A. botryocarpum indicates that host specificity, substrate relations, form of spermatangia and immediate post-fertilisation activity may not be as reliabl...

Observations on the Morphology, Cytology, and Asexual Reproduction of Schizomeris leibleinii

Abstract The morphology, cytology, and asexual reproduction of Schizomeris leibleinii was studied, using material in culture as well as from nature. The previously described “alternation of septa” is interpreted as a condition related to a particular developmental stage. The nature of the basal cell is believed to be a more reliable taxonomic feature than either the arrangement of cells in multiseriate filaments or the number of pyrenoids per cell. The somatic chromosome number is 28. Liberation of swarmers from lateral walls of filaments, but not from apices of filaments, was observed. The number of flagella per swarmer varies from 2 to 8 or more.

Nuclear Division in Zygnema

(WITH PLATES III AND IV) THE species of Zygnema chosen for this investigation possesses a nucleus unobscured by chromatophores, and hence one in which division stages can be easily followed. No zygospores were found in the material, so the species could not be identified with any degree of accuracy. The number of pyrenoids are normally two, one on each side of the nucleus. The material was gathered from the same locality, the margin of a brook, during the months of August and September of two successive years. The filaments were studied in a living condition to make sure of the presence of dividing nuclei, and were then killed in chromacetic acid and the weaker solution of Flemming for later study. The greater part of them were killed in the evening, as it was also desired to secure division stages of other Conjugatae, which grew in great abundance in the locality and have been reported by investigators as dividing more actively at night. Of these, three species of Spirogyra and two of Mesocarpus will furnish the material for a later contribution. As nearly all the literature upon the cytology of the Conjugatae relates to forms of Spirogyra, its consideration will be deferred until the completion of further studies in the nuclear division of the group. It is hoped then to bring into accord all the observations as to the character of chromatin and nucleoli. Filaments of Zygnema treated with the combination stain of safranin and gentian violet, were found upon examination to have retained the violet only in the cell sheath, while the nuclear structures and pyrenoids retained the safranin. Various results were obtained with those treated with Heidenhain's haematoxylin in combination with iron alum and eosin. As the same length of exposure to the stain did not suffice for Spirogyra and Mesocarpus growing entangled with the Zygnema, the material was allowed to remain in the staining fluids for a shorter or longer time. Filaments show pyrenoids stained black by the haematoxylin, the nuclear structures retaining the eosin; or the pyrenoids may be stained red by the eosin, and the 43] [Botanical Gazette, vOl. 41