Electron-opaque microscopic fibrils in lakes: Their demonstration, their biological derivation and their potential significance in the redistribution of cations

Leppard, Gary G.; Massalski, A.; Lean, D. R. S.

doi:10.1007/bf01279466

Cited by 71 publications

(32 citation statements)

References 46 publications

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“…The sugar residues of the coat may well be engaged in substrate-sugar reactions which can affect or facilitate transport of ions and other substances across the plasma membrane (Gupta and Hall, 1979). Material with similar affinities to that of the cell coat has been shown in other organisms, including a variety of unicellular algae, to bind cations and to retain them in an exchangeable form (Leppard, Massalski and Lean, 1977).…”

Section: Discussionmentioning

confidence: 99%

ULTRASTRUCTURAL OBSERVATION OF THE SURFACE COAT OF DUNALIELLA TERTIOLECTA FROM STAINING WITH CATIONIC DYES AND ENZYME TREATMENTS*

1980

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SUMMARYThe surface coat of the cell-wall-lacking alga Dunaliella tertiolecta has been examined with the use of the cationic dyes, alcian blue atid ruthenium red. The previously undetected existence of a glycocalyx-type cell envelope is described. The results from enzymic digestions suggest a gross similarity in the biochemical nature of the coat of Dunaliella with that reported for other eukaryotic cell types. The biological significance of this surface coat is discussed in relation to the absence of a rigid cell wall and the known ability of such algae to withstand extreme changes in the osmotic potential of the growth medium.

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Section: Discussionmentioning

confidence: 99%

ULTRASTRUCTURAL OBSERVATION OF THE SURFACE COAT OF DUNALIELLA TERTIOLECTA FROM STAINING WITH CATIONIC DYES AND ENZYME TREATMENTS*

1980

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“…Their fibrillar nature, enables TEP-precursors to pass through 8 KDa pore size membranes (Passow, 2000), although polysaccharides have high molecular weights (100-300 KDa) (Decho, 1990). During exponential growth phytoplankton cells release fibrillar TEP-precursors from their cell surfaces into the water (Leppard, Massalski & Lean, 1977;Leppard, Burnison, & Buffle, 1990;Leppard, 1995;Leppard, West, Flannigan, Carson, & Lott, 1997). Polysaccharide fibrils are also released from capsular material of metabolically active bacteria (Stoderegger & Herndl, 1998).…”

Section: Formation Mechanismsmentioning

confidence: 99%

“…Colloidal TEP-precursors consist of fibrils 1-3 nanometers in diameter, and 100s of nanometers long (Leppard, Massalski, & Lean, 1977). Their fibrillar nature, enables TEP-precursors to pass through 8 KDa pore size membranes (Passow, 2000), although polysaccharides have high molecular weights (100-300 KDa) (Decho, 1990).…”

Section: Formation Mechanismsmentioning

confidence: 99%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

958

951

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Since the development of methods to quantify transparent exopolymer particles (TEP) 1993, it has been shown that these gel-particles are not only ubiquitous and abundant, but also play a significant role in the biogeochemical cycling of elements and the structuring of food webs. TEP may be quantified either microscopically or colorimetrically. Although data based on measurements using one or other of these methods are not directly comparable, the results are consistent. TEP abundances in fresh and marine waters are in the same range as those of phytoplankton, with peak values occurring during phytoplankton blooms. TEP are very sticky particles that exhibit the characteristics of gels, and consist predominantly of acidic polysaccharides. In marine systems the majority of TEP are formed abiotically from dissolved precursors, which are released by phytoplankton that are either actively growing or are senescent. TEP are also generated during the sloughing of cell surface mucus and the disintegration of colonial matrices. The impact of exopolymers in the creation of microhabitats and in the cycling of trace compounds varies with the state in which the polymers occur, either as particles or as solute slimes. As particles, TEP provide surfaces for the colonization by bacteria and transfer by adsorption, trace solute substances into the particulate pool. As dissolved polymers they are mixed with the water and can neither be filtered nor aggregated. Because of their high abundances, large size and high stickiness, TEP enhance or even facilitate the aggregation of solid, non-sticky particles. They have been found to form the matrices of all marine aggregates investigated to date. By aggregating solid particles, TEP promote the sedimentation of particles, and, because their carbon content is high, their direct contribution to fluxes of carbon into deep water is significant. The direct sedimentation of TEP may represent a mechanism for the selective sequestration of carbon in deep water, because the C:N ratios of TEP lie well above the Redfield ratio. The turnover time of TEP as a result of bacterial degradation appears to range from hours to months, depending on the chemical composition and age of TEP. TEP may also be utilized not only by filter feeders (some protozoans and appendicularian) but TEP-rich microaggregates, consisting of pico-and nano-plankton are also readily grazed by euphausiids, thus permitting the uptake of particles that would otherwise be too small to be grazed directly by euphausiids. This short-circuits food chains and links the microbial food-web to the classical food-web. It is suggested that this expansion of the concept of food webs, linking the microbial loop with an aggregation web will provide a more complete description of particle dynamics. 

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“…The process by which excreted exopolymers form colloids has been documented in freshwater using TEM techniques (Leppard et al 1977, Strycek et al 1992) and more recently in marine waters (G. G. Leppard unpubl.). Benner et al (1992) found that in surface waters more than 30 % of the DOM is colloidal and comprises up to -50% of the 'reactive' polysaccharides.…”

Section: Introductionmentioning

confidence: 99%

Formation and significance of transparent exopolymeric particles in the northern Adriatic Sea

Schuster¹,

Herndl

1995

Mar. Ecol. Prog. Ser.

106

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We examined the abundance and bacterial colonization pattern of transparent exopolymeric particles (TEP) during 2 different ecological conditions along a trophic gradient in the northern Adriatic Sea. Generally, neither TEP density (ranging from 0 to 600 TEP ml-') nor mean TEP area were found to bc correlated with chlorophyll a concentrations, although a tendency was discernible of increasing TEP density and area towards more eutrophic conditions. TEP area ranged from 12 to 7500 pm2 with TEP-attached bactena inversely correlated with TEP aera. In laboratory experiments using water amended with dissolved organic matter released by a Chaetoceros sp. batch culture, we examined the influence of bacteria and turbulence on the formation of TEP. In both biotic and abiotic treatments subjected to turbulence, TEP density and area reached maximum levels within 24 h and retained this level over a period of -40 h. In the stagnant treatment, however, TEP area declined rapidly after reaching a peak -24 h after starting the experiment. Based on our experments, w e conclude that turbulence of the water column is more important than bacteria in the formation of TEP. In situ fluctuations in TEP abundance might reflect not only differences in phytoplankton growth stage but also different turbulent regimes.

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Electron-opaque microscopic fibrils in lakes: Their demonstration, their biological derivation and their potential significance in the redistribution of cations

Cited by 71 publications

References 46 publications

ULTRASTRUCTURAL OBSERVATION OF THE SURFACE COAT OF DUNALIELLA TERTIOLECTA FROM STAINING WITH CATIONIC DYES AND ENZYME TREATMENTS*

ULTRASTRUCTURAL OBSERVATION OF THE SURFACE COAT OF DUNALIELLA TERTIOLECTA FROM STAINING WITH CATIONIC DYES AND ENZYME TREATMENTS*

Transparent exopolymer particles (TEP) in aquatic environments

Formation and significance of transparent exopolymeric particles in the northern Adriatic Sea

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