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  • 11
    Online Resource
    Online Resource
    Wiley ; 2019
    In:  Journal of Phycology Vol. 55, No. 5 ( 2019-10), p. 997-1010
    In: Journal of Phycology, Wiley, Vol. 55, No. 5 ( 2019-10), p. 997-1010
    Abstract: We hypothesize that algae with different cell compositions are differently perceived by their predators and consequently subjected to selective grazing. Five populations of the diatom Phaeodactylum tricornutum that differed in organic and elemental composition, but were otherwise identical, were generated by acclimation to distinct growth regimes. The different populations were then mixed in pairs and subjected to predation by either the rotifer Brachionus plicatilis or the copepod Acartia tonsa . The presence of rotifers had no impact on the ratio between any two algal populations. The presence of copepods, however, affected the ratio between algae previously acclimated to a medium containing 1 mM NH 4 + and algae acclimated to 0.5 mM NO 3 − , and to either a lower irradiance or a higher CO 2 concentration. We discuss the possible reason for the influence of different nutritional histories on the vulnerability of algae to predators. The differential impact of grazers on the growth of algae with different nutritional histories may result from direct selective grazing (i.e., grazers can detect algae with the most palatable cell composition), alone or combined to an asymmetric utilization of the nutrients regenerated after predation by co‐existing algal populations. Our results strongly suggest that the nutritional history of algae can influence the relationships between phytoplankton and grazers and hint at the possibility that algal cell composition is potentially subject to natural selection, because it influences the probability that algae survive predation.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2019
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    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 12
    In: Journal of Phycology, Wiley, Vol. 56, No. 5 ( 2020-10), p. 1232-1244
    Abstract: Lake snow, caused by the freshwater centric diatom Lindavia intermedia , has become problematic in several large, oligotrophic New Zealand lakes over the past decade. Macroaggregates produced by L. intermedia foul fishing lines, intake screens, and water filters, and have a negative impact on recreational values. It was confirmed that the fibers constituting lake snow are composed of chitin, two chitin synthase genes ( chs 1 and 2) from L. intermedia were characterized, new qPCR‐based tools to quantify the abundance of the species and measure expression of chs 2 relative to the reference gene act 1 (the product of which has cytoskeletal functions) were developed. The strong heterogeneity and mucilaginous nature of lake snow samples create particular difficulties for calibrations of gene or transcript copy numbers with cell densities and obtaining high yields of mRNA. However, data collected from four lakes during November 2018 and February and May 2019 show that abundance of L. intermedia is always high when lake snow is also abundant, but that a full range of L. intermedia abundance can occur when lake snow is absent, suggesting that chitin production is not obligate in L. intermedia . This result is consistent with the available data for chs 2 expression, which suggest higher transcription when lake snow is abundant. Lake snow production by L. intermedia therefore requires an as yet undetermined stimulus independent of cell abundance.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 13
    In: Journal of Phycology, Wiley, Vol. 51, No. 2 ( 2015-04), p. 332-342
    Abstract: The abundance of Aulacoseira granulata (Ehrenburg) Simonsen and Gloeocystis planctonica (West & G.S.West) Lemmermann was assessed during the summers of 2005 and 2010 in the eutrophic Fox River, Wisconsin, USA . In both years, a mid‐summer bloom of G. planctonica was followed by the rapid growth of A. granulata . Laboratory experiments in which A. granulata was grown in cell‐free filtrate of a G. planctonica culture revealed that the growth of A. granulata was stimulated in the G. planctonica ‐treated medium relative to controls. This effect was detected when dormant A. granulata cells were used as the source culture for the experiment but not when actively growing cells were used. Dormant A. granulata also grew more rapidly in river water collected after the 2010 G. planctonica bloom relative to river water collected before the bloom. These results suggest that the summer bloom of A. granulata in the river was stimulated by G. planctonica . This relationship can be described as stimulated rejuvenation, an interaction where the transition of an algal resting stage into active growth is triggered by exposure to another species.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 14
    In: The Journal of the American Board of Family Medicine, American Board of Family Medicine (ABFM), Vol. 22, No. 6 ( 2009-11-01), p. 638-646
    Type of Medium: Online Resource
    ISSN: 1557-2625 , 1558-7118
    Language: English
    Publisher: American Board of Family Medicine (ABFM)
    Publication Date: 2009
    detail.hit.zdb_id: 2059550-5
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  • 15
    In: Journal of Phycology, Wiley, Vol. 55, No. 1 ( 2019-02), p. 104-117
    Abstract: Monoclonal strains of Chaetoceros species were collected from Chinese warm waters. Vegetative cells and resting spores were examined using light microscopy as well as scanning and transmission electron microscopy. Combined morphological and DNA sequence data from the hypervariable D1–D3 region of the nuclear ribosomal large subunit showed the presence of two new species within the section Compressa , herein described as Chaetoceros bifurcatus sp. nov. and C. millipedarius sp. nov. Both species possessed features typical of the section Compressa , but C. bifurcatus was characterized by the heavy intercalary setae fusing and extending together for a distance before diverging. The heavy setae were not visually contorted, lacking poroids and spines, in contrast with how the section Compressa has been defined. Chaetoceros millipedarius was characterized by a horizontal stagger of ordinary intercalary setae when the chain was seen in broad girdle view, making the chain look like a millipede. The two new species were supported by molecular phylogenetic analyses with C. bifurcatus sister to C. contortus var. ornatus , while C. millipedarius was sister to C. contortus var. contortus . Based on the morphological features exhibited in C. bifurcatus , the diagnosis of the section Compressa was emended to exclude “contorted” heavy setae and compressed valve faces.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 16
    In: Journal of Phycology, Wiley, Vol. 55, No. 2 ( 2019-04), p. 442-456
    Abstract: The taxonomic history of the diatom genus Amphora is one of a broad early morphological concept resulting in the inclusion of a diversity of taxa, followed by an extended period of revision and refinement. The introduction of molecular systematics has increased the pace of revision and has largely resolved the relationships between the major lineages, indicating homoplasy in the evolution of amphoroid symmetry. Within the two largest monophyletic lineages, the genus Halamphora and the now taxonomically refined genus Amphora , the intrageneric morphological and ecological relationships have yet to be explored within a phylogenetic framework. Critical among this is whether the range of morphological features exhibited within these diverse genera are reflective of evolutionary groupings or, as with many previously studied amphoroid features, are nonhomologous when examined phylogenetically. Presented here is a four‐marker molecular phylogeny that includes 31 taxa from the genus Amphora and 77 taxa from the genus Halamphora collected from fresh, brackish, and salt waters from coastal and inland habitats of the United States and Japan. These phylogenies illustrate complex patterns in the evolution of frustule morphology and ecology within the genera and the implications of this on the taxonomy, classification, and organization of the genera are discussed.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 17
    In: Journal of Phycology, Wiley, Vol. 55, No. 4 ( 2019-08), p. 948-970
    Abstract: This paper explores the diversity and taxonomy of species within Fragilaria sensu stricto, an abundant and ecologically important diatom genus, taking advantage of cultured and DNA ‐barcoded material. The goal is to facilitate the identification of European taxa within this complex, providing a unified view on morphological and molecular diversity. There is a general agreement that the separation of species within the group of Fragilaria is difficult because morphological descriptions of species are not consistent between authorities, ongoing taxonomic revisions have resulted in species described with standards of the late 20th and 21st centuries alongside descriptions based on 19th century (light microscopical) criteria, and because not all diagnostic characters can be seen in all specimens encountered in routine analyses. Consequent confusion could blur potentially important ecological distinctions between species. Our study demonstrated that some species defined on morphological criteria could be confirmed using the rbc L chloroplast gene as a genetic marker, for example, Fragilaria gracilis , Fragilaria tenera , Fragilaria perminuta , and Fragilaria subconstricta . However, even for those species, preliminary identifications based on morphology often differed from identifications based on phylogenetic clustering combined with detailed morphological study. Clades were well‐defined by rbc L, but based on morphology, the terminal taxa of these clades did not match the currently described Fragilaria species. To clarify recognition of these taxa, we describe three new species: Fragilaria agnesiae , Fragilaria heatherae , and Fragilaria joachimii .
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 18
    Online Resource
    Online Resource
    Marshfield Clinic Research Institute ; 2012
    In:  Clinical Medicine & Research Vol. 10, No. 3 ( 2012-08-01), p. 164-165
    In: Clinical Medicine & Research, Marshfield Clinic Research Institute, Vol. 10, No. 3 ( 2012-08-01), p. 164-165
    Type of Medium: Online Resource
    ISSN: 1539-4182 , 1554-6179
    Language: English
    Publisher: Marshfield Clinic Research Institute
    Publication Date: 2012
    detail.hit.zdb_id: 2155929-6
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  • 19
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  Journal of Phycology Vol. 52, No. 5 ( 2016-10), p. 716-731
    In: Journal of Phycology, Wiley, Vol. 52, No. 5 ( 2016-10), p. 716-731
    Abstract: Diatoms are highly productive single‐celled algae that form an intricately patterned silica cell wall after every cell division. They take up and utilize silicic acid from seawater via silicon transporter ( SIT ) proteins. This study examined the evolution of the SIT gene family to identify potential genetic adaptations that enable diatoms to thrive in the modern ocean. By searching for sequence homologs in available databases, the diversity of organisms found to encode SIT s increased substantially and included all major diatom lineages and other algal protists. A bacterial‐encoded gene with homology to SIT sequences was also identified, suggesting that a lateral gene transfer event occurred between bacterial and protist lineages. In diatoms, the SIT genes diverged and diversified to produce five distinct clades. The most basal SIT clades were widely distributed across diatom lineages, while the more derived clades were lineage‐specific, which together produced a distinct repertoire of SIT types among major diatom lineages. Differences in the predicted protein functional domains encoded among SIT clades suggest that the divergence of clades resulted in functional diversification among SIT s. Both laboratory cultures and natural communities changed transcription of each SIT clade in response to experimental or environmental growth conditions, with distinct transcriptional patterns observed among clades. Together, these data suggest that the diversification of SIT s within diatoms led to specialized adaptations among diatoms lineages, and perhaps their dominant ability to take up silicic acid from seawater in diverse environmental conditions.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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  • 20
    In: Journal of Phycology, Wiley, Vol. 53, No. 6 ( 2017-12), p. 1159-1170
    Abstract: Carbon dioxide concentrating mechanisms ( CCM s) act to improve the supply of CO 2 at the active site of ribulose‐1,5‐bisphosphate carboxylase/oxygenase. There is substantial evidence that in some microalgal species CCM s involve an external carbonic anhydrase ( CA ext ) and that CA ext activity is induced by low CO 2 concentrations in the growth medium. However, much of this work has been conducted on cells adapted to air‐equilibrium concentrations of CO 2 , rather than to changing CO 2 conditions caused by growing microalgal populations. We investigated the role of CA ext in inorganic carbon (C i ) acquisition and photosynthesis at three sampling points during the growth cycle of the cosmopolitan marine diatom Chaetoceros muelleri . We observed that CA ext activity increased with decreasing C i , particularly CO 2 , concentration, supporting the idea that CA ext is modulated by external CO 2 concentration. Additionally, we found that the contribution of CA ext activity to carbon acquisition for photosynthesis varies over time, increasing between the first and second sampling points before decreasing at the last sampling point, where external pH was high. Lastly, decreases in maximum quantum yield of photosystem II (F v /F m ), chlorophyll, maximum relative electron transport rate, light harvesting efficiency (α) and maximum rates of C i ‐ saturated photosynthesis (V max ) were observed over time. Despite this decrease in photosynthetic capacity an up‐regulation of CCM activity, indicated by a decreasing half‐saturation constant for CO 2 (K 0.5 CO 2 ), occurred over time. The flexibility of the CCM during the course of growth in C. muelleri may contribute to the reported dominance and persistence of this species in phytoplankton blooms.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
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