Colonies of Phaeocystis globosa are protected by a thin but tough skin

Hamm, Christian; Simson, Doris A.; Merkel, Rudolf; Smetacek, Victor

doi:10.3354/meps187101

Cited by 132 publications

(94 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This question was raised already by Jacobsen et al in 1996 upon isolation of PpV, and it was speculated at the time that the gelatinous material the colonial cells are surrounded by serves as a protection against viral infection (Jacobsen et al 1996;. The presence of an outer thin, yet mechanically stable "skin", likely with pores <4.4 nm, has also been suggested as a defense against viral attack of the cells within the colony (Hamm et al 1999). To test these hypotheses is nevertheless not easy as colonies will always shed at least some single cells, which become readily infected.…”

Section: Resistance To Viral Infectionmentioning

confidence: 99%

Phaeocystis and its interaction with viruses

et al. 2007

View full text Add to dashboard Cite

Over the years, viruses have been shown to be mortality agents for a wide range of phytoplankton species, including species within the genus Phaeocystis (Prymnesiophyceae). With its polymorphic life cycle, its worldwide distribution, and the capacity of several of the Phaeocystis species to form dense blooms, this genus is a key player for our understanding of biogeochemical cycling of elements. This paper provides an overview of what is know to date about the ecological role of viruses in regulating Phaeocystis population dynamics. It explores which variables aVect the algal host-virus interactions, and examines the impact of virally induced cell lysis of Phaeocystis on the function and structure of the pelagic food web as well as on the Xow of organic carbon and nutrients.

show abstract

Section: Resistance To Viral Infectionmentioning

confidence: 99%

Phaeocystis and its interaction with viruses

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The mucopolysaccharides consist of at least nine different aldoses, are watersoluble, and polymers are larger than 1,000 kDa (Janse et al 1999). Qualitative staining of the colony matrix indicated the absence of lipophilic compounds and chitin, but the presence of amino groups (Hamm et al 1999). Matrix-assisted laser desorption/ionization (MALDI) analysis showed that N was not proteineous, but probably present in aminosugars (Solomon et al 2003).…”

Section: Mucopolysaccharidesmentioning

confidence: 99%

“…The negatively charged mucopolysaccharides become entangled and form ionic links, such as calcium bridges (Van Boekel 1992). They then form a thin, yet strong, semipermeable colony matrix, with a pore size between 1 and 4.4 nm diameter, with plastic and to a limited extent also elastic properties (Kornmann 1955;Hamm et al 1999). Electron microscope studies of a Phaeocystis sp.…”

Section: Mucopolysaccharidesmentioning

confidence: 99%

The carbohydrates of Phaeocystis and their degradation in the microbial food web

2007

View full text Add to dashboard Cite

The ubiquity and high productivity associated with blooms of colonial Phaeocystis makes it an important contributor to the global carbon cycle. During blooms organic matter that is rich in carbohydrates is produced. We distinguish five different pools of carbohydrates produced by Phaeocystis. Like all plants and algal cells, both solitary and colonial cells produce (1) structural carbohydrates, (hetero) polysaccharides that are mainly part of the cell wall, (2) mono-and oligosaccharides, which are present as intermediates in the synthesis and catabolism of cell components, and (3) intracellular storage glucan. Colonial cells of Phaeocystis excrete (4) mucopolysaccharides, heteropolysaccharides that are the main constituent of the mucous colony matrix and (5) dissolved organic matter (DOM) rich in carbohydrates, which is mainly excreted by colonial cells. In this review the characteristics of these pools are discussed and quantitative data are summarized. During the exponential growth phase, the ratio of carbohydrate-carbon (C) to particulate organic carbon (POC) is approximately 0.1. When nutrients are limited, Phaeocystis blooms reach a stationary growth phase, during which excess energy is stored as carbohydrates. This so-called overflow metabolism increases the ratio of carbohydrate-C to POC to 0.4-0.6 during the stationary phase, leading to an increase in the C/N and C/P ratios of Phaeocystis organic matter. Overflow metabolism can be channeled towards both glucan and mucopolysaccharides. Summarizing the available data reveals that during the stationary phase of a bloom glucan contributes 0-51% to POC, whereas mucopolysaccharides contribute 5-60%. At the end of a bloom, lysis of Phaeocystis cells and deterioration of colonies leads to a massive release of DOM rich in glucan and mucopolysaccharides. Laboratory studies have revealed that this organic matter is potentially readily degradable by heterotrophic bacteria. However, observations in the field of accumulation of DOM and foam indicate that microbial degradation is hampered. The high C/N and C/P ratios of Phaeocystis organic matter may lead to nutrient limitation of microbial degradation, thereby prolonging degradation times. Over time polysaccharides tend to self-assemble into hydrogels. This may have a profound effect on carbon cycling, since hydrogels provide a vehicle to move DOM up the size spectrum to sizes subject to sedimentation. In

show abstract

“…The colonial stage, with cells very loosely interconnected and enclosed in a thin skin (Hamm et al 1999), is most easily recognized, although some species may form mucilaginous colonies or do not seem to have a colonial stage. Thousands of cells can occur in a colony that may reach 2 cm in diameter (Jahnke and Baumann 1987;Verity et al 1988;Rousseau et al 1994;Davidson and Marchant 1992).…”

Section: Introductionmentioning

confidence: 99%

A taxonomic review of the genus Phaeocystis

Medlin

Zingone

2007

Biogeochemistry

View full text Add to dashboard Cite

Phaeocystis is recognized both as a nuisance and as an ecologically important phytoplankton species. Its polymorphic life cycle with both colonial and Xagellated cells causes many taxonomic problems. Sequence variation among 22 isolates representing a global distribution of the genus has been compared using three molecular markers. The ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) spacer is too conserved to resolve species. The most conserved 18S ribosomal deoxyribonucleic acid (rDNA) analysis suggests that an undescribed unicellular Phaeocystis sp. (isolate PLY559) is a sister taxon to the Mediterranean unicellular Phaeocystis jahnii; this clade branched prior to the divergence of all other Phaeocystis species, including the colonial ones. The internal transcribed spacer (ITS) region shows suYcient variation that some spatial population structure can be recovered, at least in P. antarctica. P. globosa and P. pouchetii have multiple diVerent ITS copies, suggestive of cryptic species that are still able to hybridize. A molecular clock has been constructed that estimates the divergence of the cold water colonial forms from the warm-water colonial forms to be about 30 Ma and the divergence of P. antarctica and P. pouchetii to be about 15 Ma. A short description of the colonial stage and the Xagellated stage for each formally recognized species is provided. Morphological information is also provided on a number of undescribed species. These include the strain Ply 559, consisting of non-colonial cells with peculiar tubular extrusomes, a second non-colonial species from the north western Mediterranean Sea producing a lot of mucus, and a colonial species with scale-less Xagellates found in Italian waters. In addition, three Xagellated morphotypes with scales diVerent from those of P. antarctica were reported in the literature from Antarctic waters. The picture emerging from both molecular and morphological data is that the number of species in the genus is still underestimated and that cryptic or pseudocryptic diversity requires a sound assessment in future research of this genus. Based on all published observations, an emended description of the genus is provided.

show abstract

Colonies of Phaeocystis globosa are protected by a thin but tough skin

Cited by 132 publications

References 24 publications

Phaeocystis and its interaction with viruses

Phaeocystis and its interaction with viruses

The carbohydrates of Phaeocystis and their degradation in the microbial food web

A taxonomic review of the genus Phaeocystis

Contact Info

Product

Resources

About