Coccoliths of Coccolithus huxleyi seen in an Electron Microscope

Braarud, Trygve; Nordli, E

doi:10.1038/170361a0

Cited by 20 publications

(9 citation statements)

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“…A hypothesis which has been discussed at great length is the role of calcification as an intracellular source of CO 2 , based on the entry of HCO 3 − into the cells for calcification (Sikes et al 1980, Brownlee et al 1995a, Anning et al 1996, von Dassow et al 2009, Mackinder et al 2010 Nejstgaard et al (1994) Harris (1994) PAR Photoprotective at the Braarud & Nordli (1952) Paasche (1964, Paasche & Klaveness (1970), surface Nanninga & Tyrrell (1996), Houdan et al (2005), Trimborn et al (2007) PAR Focuses light to chloroYoung (1994) Nanninga & Tyrrell (1996), Raven & Waite (2004), plasts in deep water Trimborn et al (2007) …”

Section: Functions Of Coccolithsmentioning

confidence: 99%

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Environmental controls on coccolithophore calcification

Raven

Crawfurd²

2012

Mar. Ecol. Prog. Ser.

116

107

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Coccolithophores are major contributors to global marine planktonic calcification, and in nature coccolithophores are invariably calcified through almost all of their life cycle. The response of calcification to environmental factors is essential in understanding the persistence of coccolithophores through at least 220 million years of changing global environments, and their prospects for current environmental change. So far the responses examined have been at the level of acclimation rather than adaptation in evolution. Variation in results of CO 2 manipulation experiments can be tentatively attributed to variation among genotypes rather than differences in experimental procedure. Comparisons of methods using the same genotype, and of several genotypes using a single method, suggest significant variation among genotypes. The general response is a decreased particulate inorganic carbon (PIC) to particulate organic carbon (POC) ratio in higher than present CO 2 concentrations and vice versa for lower CO 2 concentrations. Fewer studies have investigated the effect of other environmental factors. Decreased availability of phosphorus and, to a lesser extent, nitrogen, as well as decreasing photosynthetically active radiation (PAR) down to a certain low value increase PIC:POC, while variable results have been found for changes in ultraviolet radiation (UVR). Many of these results can be accommodated by considering the restriction of calcification to the G1 phase of the cell cycle and the length of this phase under different growth conditions. Fewer studies have investigated the interactions among environmental factors which change with increased CO 2 and increasing sea surface temperature; the shoaling of the thermocline will increase the mean PAR and UVR whilst decreasing nitrogen and phosphorus availability. More studies of these interactions, as well as of genetic adaptation in response to changed environmental factors, are needed.

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Section: Functions Of Coccolithsmentioning

confidence: 99%

“…Coccolithophores produce characteristic coccoliths, comprising an organic template with crystalline calcite deposited on it in species-specific patterns (Braarud & Nordli 1952, Young 1994, Young & Henriksen 2003, Young et al 2005 according to Eqs. (2) and (3).…”

Section: Heterococcoliths and Holococcolithsmentioning

confidence: 99%

Environmental controls on coccolithophore calcification

Raven

Crawfurd²

2012

Mar. Ecol. Prog. Ser.

116

107

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“…The sequence of heterococcolith formation has been the subject of many biochemical (van der Wal et al, 1983a, b) and ultrastructural studies (Braarud & Nordli, 1952;Manton & Leedale, 1969;Klaveness, 1972Klaveness, , 1976 and involves the formation of an organic scale or baseplate within a Golgi-derived compartment followed by nucleation of calcite crystals, which alternate in their c-axis orientations, on the peripheral rim of the baseplate (Westbroek et al, 1989;Marsh, 1999;Young et al, 1999). The so-called protococcolith ring thus comprises alternating V-and R-crystal units, but it is the R-units that continue to extend proximally as the coccolith matures (Young et al, 1992.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of formation and secretion of heterococcoliths byCoccolithus pelagicusssp.braarudii

Taylor

Russell

Harper

et al. 2007

European Journal of Phycology

100

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The formation and secretion of heterococcoliths by the non-motile life phase of the coccolithophore Coccolithus pelagicus was investigated using electron microscopy and time-lapse bright field imaging. Coccolithogenesis in C. pelagicus exhibited sequential mineralization of single coccoliths in Golgi-derived and nuclear-associated vesicles, a pattern similar to the formation of heterococcoliths in Emiliania huxleyi. Our TEM data show that only on maturation does the single coccolith vesicle migrate away from the nucleus before secretion. A reticular body, distinct from the Golgi body, was also clearly visible at the distal surface of the developing coccolith vesicle, suggesting this is a common structural feature in placolith cells that mineralize and secrete coccoliths one at a time. Time-lapse imaging revealed that the coccolith secretion process is rapid, taking 60-190 seconds, and involves considerable contractile activity to eject and position the coccolith on the surface of the cell. An intact flagellar root apparatus was discovered at the anterior pole of this non-motile cell from which polarized secretion of coccoliths occurs, which may indicate a novel role for such cytoskeletal structures. Freeze-fracture preparations revealed columnar deposits and adhesions linking the scales and coccolith baseplates to the cell, across the periplasmic space providing points of attachment for cellular movement. Rotatory movements of the cell relative to external coccoliths were exhibited by all actively calcifying cells. These movements enable the cell, while exhibiting morphologically polarized secretion, to locate and secrete a mature coccolith in a spatially well-defined manner. Finally, the time-lapse imaging approach described here provides an opportunity to quantify the regulation of coccolith production in single cells with high temporal resolution allowing responses of calcification to rapidly fluctuating environmental conditions such as light-dark transitions to be examined in detail, which has not been possible with bulk calcification studies.

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“…[10] have studied the geodynamic ophiolite importance in late Paleozoic rocks in the north east of Iran. [11] has studied calcareous Nannoplankton of the sedimentary sequence starting Maastrichtian-Tertiary in Sarakhs region. [12] has studied and examined the calcareous Nannoplankton of North Khorasan, it is worth mentioning that several doctoral dissertations and master's degree has been written in the Kopet Dagh area based on calcareous foraminifera and Nannofossil, because of a plurality we ignore to mention them.…”

Section: Introductionmentioning

confidence: 99%

Determining the Gender of Nano-Fossils in the Lower Part of the Abtalkh Formation (150 M Primary)

Ghomi¹,

Moradzadeh²

2016

OJG

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A structural zone of Dagh Kopet as sediment (Trough) has created in the late Triassic. There are two different views of Dagh Kopet zone: A) Eurasian theory; B) Gondwana theory. The main fault zones are divided into two groups of foundation faults and overthrust. Abtalkh formation is one of the most important Late Cretaceous rock units in the Kopet Dagh sediment Basin and the geographic location of the study area is "03'43˚37 north latitude and "47'35˚55 the east. The calcareous nan-noplanktons are the first links in the food chain and are the main producers in the seas and oceans. The calcareous Nannoplankton is found in fine sediments such as shale and marl and for study and examination; the presence of trace amounts of sample is enough. The calcareous Lannoplankton is used to identify and introduce Nannofossils of Abtalkh in the bottom of the cut, to determine biozones available at the cutting zone and comparing it with the world standard, to determine their age. In the study section, Nannofossil is in glauconitic sandstone, conglomerate, siltstone, marl, shale, limestone, clay, marl and clay marl and Chuck. Their small size makes that a very small amount of samples are sufficient for the study. The most important method for sample preparation in this study is a smear slide method. In laboratory studies and identification of Nannofossil and counting them, the optical microscope and the object lens 50* and 100* are used. To take pictures of samples, 100× objective lens and digital camera were used. In the course of this study, for the lower part of Abtalkh, Aytamir cutting was studied and 12 genera were identified. The calcareous Nannofossils were recognized and have relatively good diversity and abundance. In general, the greater thickness of the study samples had an average preservation. In some cases, the impact of dissolution was so great that the wall or part of the main sections of the species was corroded.

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Coccoliths of Coccolithus huxleyi seen in an Electron Microscope

Cited by 20 publications

References 0 publications

Environmental controls on coccolithophore calcification

Environmental controls on coccolithophore calcification

Dynamics of formation and secretion of heterococcoliths byCoccolithus pelagicusssp.braarudii

Determining the Gender of Nano-Fossils in the Lower Part of the Abtalkh Formation (150 M Primary)

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