New lipid envelop-containing dsDNA virus isolates infecting Micromonas pusilla reveal a separate phylogenetic group.
Martinez Martinez, J. ; Boere, A. ; Gilg, I. ; Lent, J.W.M. van; Witte, H.J. ; Bleijswijk, J.D.L. van; Brussaard, C.P.D. - \ 2015
Aquatic Microbial Ecology 74 (2015)1. - ISSN 0948-3055 - p. 17 - 28.
emiliania-huxleyi - dna viruses - phaeocystis-globosa - coastal waters - algal viruses - north-sea - abundance - prasinophyceae - diversity - dynamics
Viral infection of phytoplankton has major implications for biochemical and energy cycles, community dynamics, and microbial evolution in the marine environment. The non-bloom forming picoplankter Micromonas pusilla, a significant component of the plankton community worldwide, is known to be susceptible to infection by both dsDNA and dsRNA viruses. Logically, comprehensive knowledge of the ecology of M. pusilla requires a better understanding of the diversity and infection mechanisms of their viruses. Here, we investigated 19 new M. pusilla-specific viruses (MpVs) isolated from different locations and years. We performed partial characterization of those MpVs including structural characteristics, genome size, phylogenetic analysis based on partial DNA polymerase gene sequences, host range, and stability at different temperatures and upon exposure to chloroform. Combined, these characteristics allowed classification of the MpVs into 2 groups. Exposure to chloroform led to loss of infectivity by all MpVs in one group, which suggests the presence of an outer lipid envelope. In addition, all except one of the members in that group formed a monophylogenetic clade that was distinct from all other MpV isolates. The distinctive characteristics of the 2 MpV groups suggest different infection strategies, which may have important implications for the ecology of both host and virus populations in the environment. Knowledge gained from our study adds value to the MpV isolates as a scientific resource as it will aid in developing and testing in the laboratory new hypotheses about the ecological and biogeochemical implications of M. pusilla viral infection in the environment.
Kinetic limitations in measuring stabilities of metal complexes by Competitive Ligand Exchange-Adsorptive Stripping Voltammetry (CLE-AdSV)
Leeuwen, H.P. van; Town, R.M. - \ 2005
Environmental Science and Technology 39 (2005)18. - ISSN 0013-936X - p. 7217 - 7225.
natural organic-ligands - san-francisco bay - copper complexation - atlantic-ocean - fresh-water - emiliania-huxleyi - dissolved copper - estuarine waters - surface waters - chemical speciation
The kinetic limitations of Competitive Ligand Exchange-Adsorptive Stripping Voltammetry, CLE-AdSV, for the determination of very stable metal complexes are explained in detail. For a given type of metal, from a certain lower limit of the complex stability constant, K, the usual simple equilibrium interpretation of CLE-AdSV measurements is not generally valid. By critical assessment of data for natural waters we show that in many cases the reported stability constants appear to derive from nonequilibrium conditions in the bulk sample and hence overestimate the real values. Fe(III) is a special case due to the particular kinetic features of hydroxide as a ligand. Our results call for validation of such data by analysis on the basis of the kinetics involved and/or by independent kinetic-free experimental approaches. Earlier speculations from CLE-AdSV results on very strong ligands and derived features such as the potential bioavailability of trace metals in natural waters require reconsideration.
Increase of atmospheric CO2 promotes phytoplankton productivity
Schippers, P. ; Lürling, M.F.L.L.W. ; Scheffer, M. - \ 2004
Ecology Letters 7 (2004)6. - ISSN 1461-023X - p. 446 - 451.
inorganic carbon acquisition - marine-phytoplankton - emiliania-huxleyi - dioxide - growth - lakes - availability - diatoms - impact - system
It is usually thought that unlike terrestrial plants, phytoplankton will not show a significant response to an increase of atmospheric CO2. Here we suggest that this view may be biased by a neglect of the effects of carbon (C) assimilation on the pH and the dissociation of the C species. We show that under eutrophic conditions, productivity may double as a result of doubling of the atmospheric CO2 concentration. Although in practice productivity increase will usually be less, we still predict a productivity increase of up to 40% in marine species with a low affinity for bicarbonate. In eutrophic freshwater systems doubling of atmospheric CO2 may result in an increase of the productivity of more than 50%. Freshwaters with low alkalinity appeared to be very sensitive to atmospheric CO2 elevation. Our results suggest that the aquatic C sink may increase more than expected, and that nuisance phytoplankton blooms may be aggravated at elevated atmospheric CO2 concentrations.