Lichtmikroskopische, rasterelektronenmikroskopische und röntgenmik-roanalytische untersuchungen an Hemitonia maeandrocystisSkuja (chlorophyta, phacotaceae)

Krienitz, Lothar; Peschke, Theodor; Giering, B.

doi:10.1016/s0003-9365(11)80158-2

Cited by 9 publications

(2 citation statements)

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“…Although X-ray spectra of Dysmorphococcus Takeda (Porcella, 1976;Porcella & Walne, 1980), Cephalomonas Higinbotham (Hepperle et at., 1994), Hemitoma Skuja (Krienitz et aL, 1990) and Pteromonas Seligo (Gerard, 1980;Gerard & Walne, 1979) indicate the deposition of calcium, magnesium, manganese or even silicon within the lorica, a distinct crystalline layer is not developed. These genera have a layer of lorica which accumulates minerals to some extent but there is no formation of larger crystals.…”

Section: Introductionmentioning

confidence: 99%

The extracellular calcification of zoospores ofPhacotus lenticularis(Chlorophyta, Chlamydomonadales)

Hepperle

Krienitz

1996

European Journal of Phycology

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In nature the zoospores of Phacotus lenticularis usually have a conspicuous, bivalved lorica. It consists of two clearly distinguishable layers: an outer calcite layer formed of rings of staggered calcite crystals with electron-opaque rod-like components between the crystals, and an underlying electron-opaque layer. Underneath the lorica a mucilaginous sheath is present. The ultrastructural development of these extracelluIar layers was studied by scanning electron microscopy and transmission electron microscopy of flat-embedded specimens from the natural habitat, Lake Feldberger Haussee (Baltic Lake District, Germany). During vegetative propagation, the two mother shells separate but remain attached to the mucilaginous zoosporangium which is formed between the shells. Usually two longitudinal cell divisions result in four naked zoospores in the sporangium. These begin to form new extracellular material, consisting initially of an electron-opaque layer that becomes detached by the formation of a mucilaginous inner sheath. During this stage the dictyosomes are highly active and the cells contain vesicles with rod-like structures resembling the electron-opaque material between the crystals of the adult Iorica. Zoospores are motile in the sporangium and the outermost extracellular layer gradually calcifies with small crystals developing on the electron-opaque layer in a regular manner and separated by equal distances (spotted sphere stage). The growing crystals develop in a pattern resembling a tiled roof and merge to form the final, massive calcite layer of the lorica. The zoosporangium ruptures between the former mother shells and the zoospores are released. Several possible nucleation and calcification mechanisms are discussed.

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Section: Introductionmentioning

confidence: 99%

The extracellular calcification of zoospores ofPhacotus lenticularis(Chlorophyta, Chlamydomonadales)

Hepperle

Krienitz

1996

European Journal of Phycology

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“…The elemental compositions of the loricae of Phacotus , Pteromonas , Dysmorphococcus, and Cephalomonas have been studied using energy‐dispersive X‐ray spectroscopy. The major element in the loricae of Phacotus and Pteromonas was calcium (Steinberg & Klee 1983; Krienitz et al. 1990, Giering et al.…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic position of a rare loricated green alga, Cephalomonas granulata N. L. Higinb. (Volvocales, Chlorophyceae)

Nakada¹,

Soga

Tomita

2010

Phycological Research

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Cephalomonas (Cp.) granulata N. L. Higinb. (Volvocales, Chlorophyceae), a rare volvocalean phytoflagellate, has recently been isolated from a paddy field in Japan and examined by light and fluorescence microscopy. The vegetative cells of Cp. granulata have granulate loricae and a characteristic mushroom-like shape with a hemispherical to spherical anterior part and narrower posterior part. Cp. granulata has been classified among the Phacotaceae along with other loricated genera. However, its phylogenetic position has not been investigated using molecular phylogeny. To evaluate the phylogenetic position of Cephalomonas, the 18S rRNA gene sequence of the Japanese strain was determined. The phylogenetic analyses revealed that Cp. granulata was not closely related to other loricated taxa with known phylogenetic affinities, such as Phacotaceae sensu stricto (Phacotus, Pteromonas, and Wislouchiella) and Dysmorphococcus globosus. This indicates at least three independent origins of loricae within the Volvocales.

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Silicification in the Microalgae

Finkel

2016

The Physiology of Microalgae

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Lichtmikroskopische, rasterelektronenmikroskopische und röntgenmik-roanalytische untersuchungen an Hemitonia maeandrocystisSkuja (chlorophyta, phacotaceae)

Cited by 9 publications

References 10 publications

The extracellular calcification of zoospores ofPhacotus lenticularis(Chlorophyta, Chlamydomonadales)

The extracellular calcification of zoospores ofPhacotus lenticularis(Chlorophyta, Chlamydomonadales)

Phylogenetic position of a rare loricated green alga, Cephalomonas granulata N. L. Higinb. (Volvocales, Chlorophyceae)

Silicification in the Microalgae

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