Sexual reproduction in desmids with special reference to<i>Micrasterias thomasiana</i>var.<i>notata</i>(Nordst.) Grönblad

Blackduran, Susan I.; Tyler, P.A.

doi:10.1080/00071618100650231

Cited by 16 publications

(11 citation statements)

References 30 publications

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“…Different fibrilar and occasionally looped processes of Gigantosphaeridium fibratum n. gen. et sp., bear similarities to extant marine microalgae Sphaeropsis (Pterospermataceae, Chlorophyta) and Piropsis (Craspedophyta) from the North Sea and Arctic Sea (AlgaeBASE). Secondary wall synthesis during the cyst stage was observed in several extant taxa: chlorophyte Haematococcus pluvialis (Hagen et al, 2002;Damiani et al, 2006) and charophyte M. thomasiana (Blackburn and Tyler, 1981), Volvocales (Hagen et al, 2002), resembling features in the studied taxa.…”

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confidence: 97%

“…The Shuiyousphaeridium macroreticulatum morphotype represents this stage and its morphology resembles cysts seen in several extant species. A common pattern of acanthomorphic zygotic cysts is known in microalgae, such as the chlorophycean Golenkinia radiata (Chodat, 1894;Guiry and Guiry, 2013), the charophyte desmidiaceans Micrasterias papillifera (Kies, 1970) and Micrasterias thomasiana (Blackburn and Tyler, 1981), and the zygnemophycean Staurastrum fungicerum (Lacalli, 1981). During zygotic cyst formation in Micrasterias thomasiana (Blackburn and Tyler, 1981), the cytoplasm begins to shrink inwards and spiny processes are formed by contraction from the outer membrane enclosing the zygote (Belmonte et al 1997;Lee, 2008).…”

Section: Life Cyclementioning

confidence: 99%

“…within the photic and oxygenated surface zone). Eventually they aid descent to the substrate, where cysts remain for releasing offspring or dormant under adverse environmental conditions (e.g., low nutrients supply, temperature change, acidity or anoxia) (Blackburn and Tyler, 1981;van den Hoek et al, 1995;Belmonte et al, 1997;Dale, 2001;Reynolds, 2006;Lee, 2008). Excystment structures (reproductive openings) develop once a cyst has matured to release offspring (Tappan, 1980;Bold and Wynne, 1985;Wicander, 2007;Moczydłowska, 2010).…”

Section: Life Cyclementioning

confidence: 99%

“…Major acritarch characters, including those of the studied Ruyang biota, such as the lavish processes, complex cell wall and excystment structures, share morphological similarities and biochemistry with the cyst stage of extant chlorophytes, charophytes, and dinoflagellates (Lacalli, 1981;Blackburn and Tyler, 1981;Raven et al, 2005;Moczydłowska and Willman, 2009;Moczydłowska et al, 2011;Guiry and Guiry, 2013). As they represent elements of the reproductive cyst in modern taxa, sexual reproduction may also be assumed for the Mesoproterozoic fossils.…”

Section: Introductionmentioning

confidence: 99%

“…Examples are provided by chlorophytes Golenkinia radiata (Chlorococcales; Chodat, 1894;Guiry and Guiry, 2013), and Atractomorpha echinata (Sphaeropleales; Hoffman, 1983), charophytes Micrasterias papillifera (Kies, 1970), Micrasterias thomasiana (Blackburn and Tyler, 1981), and Staurastrum furgicerum (Lacalli, 1981). Distally divided processes in Shuiyousphaeridium resemble the processes in these algal zygocysts.…”

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confidence: 99%

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Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

Agić¹,

Moczydłowska²,

Yin

2015

J. Paleontol.

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Abstract.-Light microscope and scanning electron microscope observations on new material of unicellular microfossils Dictyosphaera macroreticulata and Shuiyousphaeridium macroreticulatum, from the Mesoproterozoic Ruyang Group in China, provide insights into the microorganisms' biological affinity, life cycle and cellular complexity. Gigantosphaeridium fibratum n. gen. et sp., is described and is one of the largest Mesoproterozoic microfossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties of resistance and cell wall structure in Dictyosphaera and Shuiyousphaeridium are all diagnostic of microalgal cysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development of reproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst) stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates a reproductive strategy of alternation of heteromorphic generations. Similarly in Gigantosphaeridium, a metabolically expensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these characters and from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stem group of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers in Dictyosphaera and Shuiyouisphaeridium required a high cellular complexity for their synthesis and the presence of an endomembrane system and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biota reveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryotic evolution and the development of complex life cycles with sexual reproduction by 1200 Ma.

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mentioning

confidence: 97%

Section: Life Cyclementioning

confidence: 99%

Section: Life Cyclementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

Agić¹,

Moczydłowska²,

Yin

2015

J. Paleontol.

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Zygnematophyta

Hall¹,

McCourt²

2017

Handbook of the Protists

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Zygnematophyta

Hall¹,

McCourt²

2016

Handbook of the Protists

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The Zygnematophyta are among the most diverse green algae, with a variety of thallus types (filaments, unicells, colonies), cell wall structure (one to several layers, with varying degrees of ornamentation), and approximately 4,000 described species. The group lacks flagella at all stages of the life cycle. Several types of asexual spores are produced. Sexual reproduction, when present, involves conjugation or the union of two haploid vegetative protoplasts (individual cells of filaments or unicells) to form a zygospore, which undergoes meiosis to produce a new haploid thallus upon germination. Almost exclusively freshwater, these algae are common in ponds, lakes, and streams, in surface mats, or as phytoplankton or benthic growths. Many, but not all, are found in oligotrophic to mesotrophic waters of moderate to low pH, although the diversity of habitats occupied spans a wide range and may be quite specific for individual species. The fossil record extends at least to the Carboniferous. Recent analyses have placed this group as the sister taxon to land plants, despite the dramatic differences in morphology, life cycles, and reproduction. The group includes the well-known Spirogyra and numerous beautiful unicellular forms known as desmids, many of which have elaborate external ornamentations (e.g., spines, granules, large lobes). The conjugating green algae are important as ecological indicator species and for the ecological services they provide.

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Sexual reproduction in desmids with special reference toMicrasterias thomasianavar.notata(Nordst.) Grönblad

Cited by 16 publications

References 30 publications

Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

Zygnematophyta

Zygnematophyta

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