Zygnema is a genus of filamentous algae whose members characteristically possess two star-shaped chloroplasts per cell. Stancheva R., Hall J.D., Herburger K., Lewis L.A., McCourt R.M., Sheath R.G. Phylogeny of the conjugating green algae (Zygnemophyceae) based on, Cell width as a taxonomic character with special reference to. (2008). Describe this and its shape. These polar hydro-terrestrial algal mats are often formed by algae of the genus Zygnema C. Agardh that are very well adapted to the harsh conditions of the polar climate, as demonstrated by various ecophysiological studies (Hawes, 1990; Holzinger et al., 2009; Pichrtová et al., 2013, 2014a The investigated genotypes were evenly distributed among genotypes of non-polar origin, and did not form any monophyletic polar clusters. (2001). We confirmed the presence of wing-like lamellate appendages surrounding the exospore using light microscopy (Figs 5–9), as well as by TEM (Figs 10–14), which clearly showed that these structures are cellulosic-pectic, with a loose fibrillary appearance (Fig. 3. The original description comprises zygospores with 44–52 μm in diameter, the same pattern of their formation and appearance and vegetative filaments ranging 15–21 μm in width. Describe this and its shape. 2013), and sympatric occurrence of cryptic (or pseudocryptic) species has been described for other microalgal assemblages such as diatoms (Vanormelingen et al., 2008) and desmids (Nemjová et al., 2011). & Holzinger A. Molecular, morphological and ultrastructural characteristics of, MrBayes 3: Bayesian phylogenetic inference under mixed models. Named for their beautiful spiral chloroplasts, spirogyras are filamentous algae that consist of thin unbranched chains of cylindrical cells. Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient. Zygnema Chloroplast shape. The number of strains isolated for each Zygnema/Zygnemopsis genotype and their geographic origin are given in parentheses. Species concept and morphological differentiation of strains traditionally assigned to, Algal flora of subalpine peat bog pools in the Krkonoše Mts. Fig. The Streptophyta comprise all land plants and six monophyletic groups of charophycean green algae. Two parallel Markov chain Monte Carlo runs were carried out for 3 000 000 generations, each with one cold and three heated chains. Antarctic microchlorophytes (De Wever et al., 2009) or Prasiola (Moniz et al., 2012) also possess endemic lineages. 33) and P (Fig. However, this theory has been tested many times, and numerous examples of protist species with limited distribution are known. Weather patterns of the coastal zone of Petuniabukta, central Spitsbergen in the period 2008–2010. 30. We compared the plastid shape of young vegetative cells in fresh exponentially growing cultures (3 weeks after inoculation) for all genotypes, and this was stable in cells grown under controlled laboratory conditions. Sequence evolution models were determined as GTR+gamma for the first codon position, JC+I for the second position and GTR+I+gamma for the third position using MrModel Test 2.3 (Nylander, 2004) with the Akaike Information Criterion. All samples, including PAR-only, had a remarkably dense cytoplasm with chloroplasts practically filling up the whole intracellular space. Moreover, any structural and functional knowledge could help to resolve the diversity and evolution of Zygnematophyceae, the most species-rich charophyte lineage. Cellular diameter is influenced by additional factors such as culture age (Herburger et al., 2015) and environmental conditions (Miller & Hoshaw, 1974; Stancheva et al., 2012). The outer mesospore layer (Me1, Fig. Another theory of protist distribution, the moderate endemicity model, was proposed which admits the existence of endemic species (Foissner, 1999, 2006). Molecular methods have also been used in two recent experimental studies of polar Zygnema strains. Zygnema circumcarinatum, a filamentous charophycean alga with elongated cells and multiple star-shaped chloroplasts per cell, is found in stagnant waters as ‘large bright green colored, tangled, floating masses’ (Guiry and Guiry, 2013). 36. Pichrtová M., Remias D., Lewis L.A. & Holzinger A. Ulothrix has band-shaped Chloroplasts: Zygnema has Star-shaped Chloroplasts: Chalmydomonas has one cup-shaped Chloroplast: Cladophora has many small oval Chloroplasts: Mougeotia has a flat Chloroplast. Its phylogenetic position has already been determined in our previous work (Pichrtová et al., 2014b (2012) reported two species of Zygnema in Korea despite more than 3 years of collecting. already built in. The line within the box marks the median, boundaries indicate the 25th and 75th percentiles, error bars indicate the 10th and 90th percentiles, and individual points denote outliers (samples with values outside this range). DNA was isolated from vegetative filaments in log-phase of growth according to the protocol of Ryšánek et al. Láska K., Witoszová D. & Prošek P. (2012). Hidden levels of phylodiversity in Antarctic green algae: further evidence for the existence of glacial refugia. Arctic, chloroplast shape, cryptic diversity, microscopy, molecular phylogeny, Map showing the locations of original sampling sites of strains investigated in this study. & Frise E. (2012). This genetic similarity is not surprising, since the ubiquity theory, assuming cosmopolitan distribution and unlimited dispersal of protists, was proposed as an explanation for the worldwide distribution of protists (Finlay et al., 1996; Finlay, 2002). Pichrtová M., Kulichová J. 23. L sample as Z. lamellata. V; Fig. (2004). Additionally, we also investigated all Antarctic Zygnema strains currently available, consisting of three newly sequenced strains (CCCryo 280-06, 279-06 and MB1) and published sequences of strains Zygnema sp. Genotype A; Fig. Although most specimens were sterile, we also observed conjugation and zygospore formation in our field samples, representing the first record of sexual reproduction in Zygnema and Zygnemopsis from Svalbard. The zygospore was already surrounded by a lamellate wall (exospore) after zygospore formation, and this was surrounded by a pectic-cellulosic appendage with a wing-like shape (Fig. Global ubiquity and local endemism of free-living terrestrial protists: phylogeographic assessment of the streptophyte alga. Fig: Different parts of chloroplast (a simplified figure seen through the electron microscope) Structure of chloroplast: The structure of the chloroplast is very complicated. McCourt R.M., Karol K.G., Bell J., Helm-Bychowski K.M., Grajewska A., Wojciechowski M.F. & Marvan P. (1997). Genotypes that do not significantly differ from each other share at least one letter, while those significantly different from each other do not share any letters (p < 0.05; Kruskal–Wallis test with multiple comparisons). Unrelated genotypes may possess a similar chloroplast type and, conversely, genotypes from one lineage (e.g. one species) of Zygnema from New Zealand. Spirogyra chloroplast shape. 31. The Bayesian tree was midpoint-rooted and further processed using Mega 6 (Tamura et al., 2013) and Adobe Illustrator CS3 (Adobe Systems, San Jose, California, USA). Green algae of the genus Zygnema form extensive mats and produce large amounts of biomass in shallow freshwater habitats. By contrast, most lineages of the filamentous green algal genus Klebsormidium (Streptophyta) have a geographically limited distribution, and only one cosmopolitan lineage comprises both Arctic and Antarctic isolates (Ryšánek et al., 2016). Capital letters were assigned to individual genotypes based on our recent publications on polar Zygnema spp. Supplementary material 3. Stroma is the homogenous matrix which contains grana and is similar to the cytoplasm in cells in which all the organelles are embedded. Distribution, morphological diversity and evidence for polyploidy in North American Zygnemataceae (Chlorophyta). To estimate the limits of survival at subzero temperatures, freezing resistance of young Zygnema sp. Prasiolales (Trebouxiophyceae, Chlorophyta) of the Svalbard Archipelago: diversity, biogeography and description of the new genera. Chloroplast-encoded rbcL sequences were obtained for 143 Arctic strains with vegetative Zygnema-like morphology isolated from 39 different mats at 20 different localities on Svalbard (Fig. N; Fig. Recent molecular investigations showed that the Antarctic morphospecies Prasiola crispa, in fact, comprises three cryptic species (Moniz et al., 2012). Zygnemopsis possesses two compact lobate chloroplasts per cell (Fig. 2). Select the incorrect match w.r.. shape of chloroplast 1) Ulothri - Pyriform 2) Chlamydomonas - Cup shaped 3) Zygnema - Star shaped 4) Selaginella - Discoid It is screw-like in Spirogyra -species, star-shaped in Zygnema and Zygnemopsis and netlike in Oedogonium. This species was originally described from China, with spherical or almost spherical brown zygospores from 29×35 to 32×38 μm in size and with filament width range 20–26 mm. Thus, option B is correct. Zygnema is actually a rather common freshwater alga and often it's found growing with Spirogyra. Young vegetative cells (3 weeks after transfer to fresh medium) of the investigated genotypes. Vegetative Body of Zygnema (Fig. 12. chloroplasts in zygospores; Fig. Molecular and morphological characterization of the. Pigmentation. Chl a Chl b Accessory pigments NO phycobilins. Wang J.-C., Hoshaw R.W. Abbreviations are Chl = chloroplast, CW = cell wall of the mother cell, Ex = exospore, L = lipids, Me1 = outer mesospore layer, Me2 = inner mesospore layer, En = endospore. We did not observe formation of asexual spores (aplanospores, akinetes) in this study, sexual reproduction was observed only twice. They are morphologically diverse and visually attractive. A recent phylogenetic study of Zygnema split the genus into two main well-supported clades (Stancheva et al., 2012), which corresponded to the zygospore colour in Zygnema, i.e. 2012). The chloroplast is contained within a semipermeable double membrane. Herburger K., Lewis L.A. & Holzinger A. The 12 Arctic Zygnema genotypes investigated in this study cluster into two main clades of the genus (Fig. 39); (iii) chloroplasts with flat, wide terminal lobes as shown for U (Fig. ), and further determined the species as Zygnemopsis lamellata by morphological characterization of a fertile sample observed in the field. A preliminary study, Comparative study of chloroplast morphology and ontogeny in, Confocal microscopy of the green-algal chloroplast, Ecological differentiation of cryptic species within an asexual protist morphospecies: a case study of filamentous green alga. , 2014b Pichrtová M., Hájek T. & Elster J. McCourt R.M., Hoshaw R.W. Ketpin Chong, Yuru Deng, in Methods in Cell Biology, 2012. Some of the Arctic genotypes were very closely related to others, such as Zygnema sp. Our light microscopy observations of spore layers were consistent with the differences in the electron density of the two mesospore layers observed by TEM: while the outer layer (Me1) is electron-translucent and thin (Fig. A case study using SSU rDNA and, Taxonomy and nomenclature of the Conjugatophyceae (= Zygnematophyceae). About a hundred Zygnema species are recognized but even specialists have a hard time distinguishing them. Tamura K., Stecher G., Peterson D., Filipski A. Conjugating green algae (class Zygnematophyceae) are the most species-rich group of charophyte algae, with more than 4000 described species (Gerrath, 2003). Freshwater diatom biogeography and the genus. N; Fig. A new understanding of the phylogenetic position of the genus Zygogonium was recently proposed based on atpB, psbC and rbcL genes, as well as morphological features (Stancheva et al., 2014). In Antarctic Tribonemataceae (Stramenopiles), phylogenetically distant, yet ecologically and morphologically similar filamentous freshwater algae, cryptic genera were also revealed (Rybalka et al., 2009), and no biogeographic limitation of individual clades and endemism was revealed (Rybalka et al., 2009). Currently, both Zygnema and Zygnemopsis genera belong to order Zygnematales and family Zygnemataceae (Guiry, 2013). & Guiry M.D. & Delwiche C.F. Nitrogen limitation and slow drying induce desiccation tolerance in conjugating green algae (Zygnematophyceae, Streptophyta) from polar habitats. In addition, during 2015 sampling, temperature, pH and conductivity were measured using a portable meter WTW pH/Cond 340i. Interestingly, sites that were investigated repeatedly (sites 10, 11 and 15, and mat 2 at site 9; Fig. Novis (2004) reported only one fertile specimen (i.e. Pinseel E., Vanormelingen P., Hamilton P.B., Vyverman W., Van de Vijver B.
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