Regulation of alkaline phosphatase synthesis in Phaeocystis sp.

Vanboekel, Whm; Veldhuis, Mjw

doi:10.3354/meps061281

Cited by 38 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We would classify the high V,,,,, values found for alkaline phosphatase activities as an indication of deficiency, but not necessarily as an indication of limitation, since some species have been shown to induce this enzyme before their internal stores of P are exhausted (Boekel and Veldhuis 1990). Values found here were comparable to values found in the brackish layer of a Norwegian fjord, an environment suggested to have strong physiological P limitation due to the influence of fresh water (Thingstad et al 1993).…”

Section: Discussionmentioning

confidence: 99%

P limitation of heterotrophic bacteria and phytoplankton in the northwest Mediterranean

Thingstad

Zweifel²,

Rassoulzadegan

1998

Limnology & Oceanography

343

244

View full text Add to dashboard Cite

Surface-water microbial populations were investigated in the northwest Mediterranean for possible indicators of phosphate deficiency and limitation. Low phosphorus availability was suggested by short turnover time (min. observed 0.68 h), high-alkaline phosphatase activity (V,,,,, = 28 nM hydrolyzed h-l), subsaturation of phosphate uptake (2.6-9% of V,,,), and high-pulse uptake capacity of added orthophosphate. Based on high pulse uptake capacity and subsaturated uptake in both the >l-pm and in the 0.2-l-pm size fractions, P deficiency is suggested for both phytoplankton and heterotrophic bacteria. P limitation of heterotrophic bacteria was also supported by fast positive responses after phosphate addition in both thymidine incorporation in whole-water samples and increased bacterial cell numbers in predator-free water. No effects were found after addition of carbon or nitrogen sources alone. Combined with other published evidence, we suggest that the growth rates of not only phytoplankton, but also of heterotrophic bacteria, are P limited in this environment in summer. The finding has important implications for the dynamics of accumulation of dissolved organic carbon in the photic zone and thus for the carbon cycle of oceans.

show abstract

Section: Discussionmentioning

confidence: 99%

P limitation of heterotrophic bacteria and phytoplankton in the northwest Mediterranean

Thingstad

Zweifel²,

Rassoulzadegan

1998

Limnology & Oceanography

343

244

View full text Add to dashboard Cite

show abstract

“…We checked the cultures for positive APA. It has been debated whether APA is a sign of depletion of external phosphate or of a more severe P-starvation where the internal cell quota approaches minimum and growth is truly P-limited (Van Boekel & Veldhuis 1990). We only used APA as additional information to measurements of SRP and cell counts, confirming that the cells were in a phase of P-starvation.…”

Section: Discussionmentioning

confidence: 99%

Relationship between phosphate affinities and cell size and shape in various bacteria and phytoplankton

Tambi¹,

Flaten²,

Egge³

et al. 2009

Aquat. Microb. Ecol.

View full text Add to dashboard Cite

Substrate affinity expresses the ability of an osmotroph organism to compete for a substrate at permanently low external concentrations and is thus a central parameter in conceptual and mathematical models of aquatic food webs. Assuming diffusion transport in the surrounding medium to be the limiting process at low external substrate concentrations, the theoretical maximum affinity (α max ) and its dependence on cell size and shape for a given osmotroph organism can be calculated from Fick's law of diffusion in combination with knowledge of the amount of substrate required to form a new cell. For a non-respired substrate, the actual affinity (α) can also be expressed as the biomass-specific turnover rate of the substrate, α = (TB) -1. Combining a measure of biomass (B), with determination of substrate turnover time (T), the affinity can thus be determined experimentally. We used this approach to compare measured with theoretical maximum affinities for phosphate in laboratory cultures of osmotrophic microorganisms. For bacteria and autotrophic flagellates, we found relatively good agreement between experimental and theoretical maximum values, suggesting that diffusion limitation is actually approached in P-limited cultures. Assuming P-free vacuoles, the theory predicts diatom affinities to exceed that of similarly sized flagellates. This prediction is consistent with our experimental observations. Previous reports of diatoms being unsuccessful under P-limited conditions may therefore need a more complex explanation than lack of competitive ability in diatoms.

show abstract

“…Growth and colony formation in each culture was followed in time. Cell counts were performed according to van Boekel & Veldhuis (1990). In all experiments cultures were examined regularly for bacterial contamination using fluorescence microscopy after staining of samples with Hoechst dye no.…”

mentioning

confidence: 99%

Phaeocystis colony mucus components and the importance of calcium ions for colony stability

Boekel

1992

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The composition and properties of Phaeocystis colony mucus are st~ll largely obscure. In this study some components of the mucus were i d e n t~f~e d using a specific staining technique and the role of Ca2* and other cations as binding agent was investigated. In addition, the effect of Ca2' concentration on colony formation in batch cultures was studied. Colonies of Phaeocystis sp. were stained with alcian blue at 2 different pH values. This revealed that the colony mucus contained both carboxylated and sulfated polymers. Incubation of colonies in medium lacking one or more cations showed that calcium and magnesium ions were essential for the gelling of colony mucus, while potasslum ions had no influence. The percentage colony cells formed by Phaeocystis in batch cultures was reduced in medium with calcium concentrations below 2.5 mm01 I-'. No colonies were formed in medium with calcium concentrations below 1.5 mm01 1.' Growth rate was not dependent on calcium concentration. It is suggested that under natural conditions Phaeocystis colony firmness and morphology might depend on the composition of mucus polymers.In the marine environment mucus production is known to occur in bacteria (Decho 1990), macroalgae (Boney 1981) and several groups of microalgae such as diatoms (Decho 1990), green algae (Crayton 1982) and the Prymnesiophyceae (Painter 1983). The composition of mucus produced by these groups is often rather complex, consisting of heteropolymeric chains containing a wide variety of simple sugars, aminosugars, uronic acids, sulfated or phosphated sugars, amino acids, etc. The gelling capacity of mucus depends on the binding of negatively charged groups in the molecule (mostly carboxyl groups) with cations (mostly Ca2+). In this way ionic bridges are formed between polymer strands. The number of ionic bridges formed in a polymer depends on the number of anionic groups and the steric arrangement of these groups in the molecule (Kohn et al. 1968). Colony-forming algae such as the Volvocaceae produce mucus with large amounts of carboxyl and sulfate groups (Crayton 1982).The alga Phaeocystis sp. is an important component of the phytoplankton of several marine ecosystems, such as the North Sea and the Arctic and Antarctic oceans (Barnard et al. 1984, Cadee & Hegeman 1986, Palrnisano et al. 1986, Lancelot et al. 1987, Gibson et al. 1990, Wassmann et al. 1990. Phaeocystis forms colonies consisting of mucus in which cells are randomly distributed. The colonies are spherical or elongated and reach sizes of up to 5 mm in diameter, containing over 10 000 cells (Rouseau et al. 1990). During bloom situations in the North Sea, when Phaeocystis cell number often exceeds Mar. Ecol. Prog. Ser. 87: 301-305, 1992 Materials and methods. All experiments were performed with axenic Phaeocystis sp. (strain K) isolated from the Dutch Wadden Sea. This strain formed globosa-type colonies (Jahnke 1989). Phaeocystis was grown in 1 1 serum bottles incubated on a rolling device at 10 "C and a light intensity of 40 pE m-' S-' ...

show abstract

Regulation of alkaline phosphatase synthesis in Phaeocystis sp.

Cited by 38 publications

References 21 publications

P limitation of heterotrophic bacteria and phytoplankton in the northwest Mediterranean

P limitation of heterotrophic bacteria and phytoplankton in the northwest Mediterranean

Relationship between phosphate affinities and cell size and shape in various bacteria and phytoplankton

Phaeocystis colony mucus components and the importance of calcium ions for colony stability

Contact Info

Product

Resources

About