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Wonho Yih - One of the best experts on this subject based on the ideXlab platform.
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feeding by the pfiesteria like heterotrophic dinoflagellate luciella masanensis
Journal of Eukaryotic Microbiology, 2007Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jae Yeon Park, Jong Hyeok Kim, Tae Hoon Kim, Hyung Seop Kim, Wonho YihAbstract:To explore the feeding ecology of the Pfiesteria-like dinoflagellate (PLD) Luciella masanensis (GenBank Accession no. AM050344, previously Lucy), we investigated the feeding behavior and the kinds of prey species that L. masanensis fed on and determined its growth and ingestion rates of L. masanensis when it fed on the dinoflagellate Amphidinium carterae and an unidentified cryptophyte species (equivalent spherical diam., ESD=5.6 microm), which were the dominant phototrophic species when L. masanensis and similar small heterotrophic dinoflagellates were abundant in Masan Bay, Korea in 2005. Additionally, these parameters were also measured for L. masanensis fed on blood cells of the perch Lateolabrax japonicus and the raphidophyte Heterosigma akashiwo in the laboratory. Luciella masanensis fed on prey cells by using a peduncle after anchoring the prey with tow filament, and was able to feed on diverse prey such as cryptophytes, raphidophytes, diatoms, mixotrophic dinoflagellates, and the blood cells of fish and humans. Among the prey species tested in the present study, perch blood cells were observed to be the optimal prey for L. masanensis. Specific growth rates of L. masanensis feeding on perch blood cells, A. carterae, H. akashiwo, and the cryptophyte, either increased continuously or became saturated with increasing the mean prey concentration. The maximum specific growth rate of L. masanensis feeding on perch blood cells (1.46/day) was much greater than that of A. carterae (0.59/day), the cryptophyte (0.24/day), or H. akashiwo (0.20/day). The maximum ingestion rate of L. masanensis on perch blood cells (2.6 ng C/grazer/day) was also much higher than that of A. carterae (0.32 ng C/grazer/day), the cryptophyte (0.44 ng C/grazer/day), or H. akashiwo (0.16 ng C/grazer/day). The kinds of prey species which L. masanensis is able to feed on were the same as those of Pfiesteria piscicida, but very different from those of another PLD Stoeckeria algicida. However, the maximum growth and ingestion rates of L. masanensis on perch blood cells, A. carterae, H. akashiwo, and the cryptophyte were considerably lower than those of P. piscicida. Therefore, these three dinoflagellates may occupy different ecological niches in marine planktonic communities, even though they have a similar size and shape and the same feeding mechanisms.
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Distribution of the heterotrophic dinoflagellate Pfiesteria piscicida in Korean waters and its consumption of mixotrophic dinoflagellates, raphidophytes and fish blood cells
Aquatic Microbial Ecology, 2006Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jae Yeon Park, Jong Hyeok Kim, Sanghee Kim, Jae Seong Kim, Wonho YihAbstract:To explore the distribution of Pfiesteria piscicida in Korean coastal waters, we analyzed the morphology and DNA sequence of several isolates collected from 6 locations along the southern and western Korean coasts. We also investigated the prey species consumed by a Korean isolate and determined the growth and ingestion rates of P. piscicida when it fed on the dinoflagellate Amphidinium carterae, an unidentified cryptophyte species, and the raphidophyte Heterosigma akashiwo. Additionally, these parameters were measured when the isolate was fed perch blood cells and the cryptophyte Rhodomonas salina. Furthermore, we calculated grazing coefficients by combining field data on abundance of P. piscicida (and Pfiesteria-like dinoflagellates) with laboratory data on ingestion rates. The DNA sequence of a P. piscicida isolate from Masan Bay was identical to USA isolates, whereas DNA sequences of isolates from Busan, Incheon, Kunsan, Kwangyang, and Yeosu differed by 1 bp from USA isolates. Among the prey offered, P. piscicida was able to feed on all naked mixotrophic dinoflagellates, the smallest thecate mixotrophic dinoflagellates Heterocapsa rotundata, and all raphidophytes, but not on large thecate dinoflagellates. Perch blood cells were the optimal prey. Maximum growth rates of P. piscicida fed on perch blood cells, R. salina, A. carterae, the cryptophyte, and H. akashiwo were 1.74, 1.41, 1.22, 1.15, and 1.10 d -1 , respectively. The maximum ingestion rate of P. piscicida when fed perch blood cells (4.3 ng C predator -1 d -1 ) was much higher than those when fed R. salina, H. akashiwo, A. carterae, or the cryptophyte (0.4 to 1.7 ng C predator -1 d -1 ). Calculated grazing coefficients on co-occurring Amphidinium spp., H. akashiwo, and cryptophytes were up to 1.07, 0.45, and 0.22 h -1 , respectively. Our results suggest that grazing by P. piscicida potentially has a considerable effect on algal populations.
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feeding by the mixotrophic red tide dinoflagellate gonyaulax polygramma mechanisms prey species effects of prey concentration and grazing impact
Aquatic Microbial Ecology, 2005Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Jae Yeon Park, Jong Hyeok Kim, Sanghee Kim, Kyeong Ah Seong, Seung Hyeon Lee, Wonho YihAbstract:The red-tide dinoflagellate Gonyaulax polygramma (GenBank accession number = AJ833631), previously known as an exclusively autotrophic dinoflagellate, has been found to be a mixotrophic species. We investigated feeding mechanisms, types of prey species, and the effects of prey concentration on the growth and ingestion rates of G. polygramma when feeding on an uniden- tified cryptophyte species (equivalent spherical diameter, ESD = 5.6 µm). We also calculated grazing coefficients by combining field data on abundances of G. polygramma and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Among the phytoplankton prey offered, G. polygramma ingested small phytoplankton species with ESD ≤ 17 µm, but did not feed on large phytoplankton species with ESD > 22 µm. G. polygramma fed on prey cells by engulfing them through the apical horn, a previously unknown mechanism, as well as through the sulcus. The feed- ing mechanism of G. polygramma on phytoplankton mainly depended on the prey species. Specific growth rates of G. polygramma on a cryptophyte increased with increasing mean prey concentration, with saturation occurring at a mean prey concentration of approximately 600 ng C ml -1 . The maxi- mum specific (mixotrophic) growth rate of G. polygramma on a cryptophyte was 0.278 d -1 , under a 14:10 h light:dark cycle of 50 µE m -2 s -1 , while its (phototrophic) growth rate under the same light conditions without added prey was 0.186 d -1 . Its maximum ingestion and clearance rates were 0.18 ng C grazer -1 d -1 (10.6 cells grazer -1 d -1 ) and 0.18 µl grazer -1 h -1 , respectively. The grazing coefficients of G. polygramma on cryptophytes were up to 0.479 h -1 . The results of the present study suggest that G. polygramma can have a considerable grazing impact on cryptophyte populations.
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mixotrophy in the phototrophic harmful alga cochlodinium polykrikoides dinophycean prey species the effects of prey concentration and grazing impact
Journal of Eukaryotic Microbiology, 2004Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jong Hyeok Kim, Jae Seong Kim, Tab Hoon Kim, Wonho YihAbstract:We first reported here that the harmful alga Cochlodinium polykrikoides, which had been previously known as an autotrophic dinoflagellate, was a mixotrophic species. We investigated the kinds of prey species and the effects of the prey concentration on the growth and ingestion rates of C. polykrikoides when feeding on an unidentified cryptophyte species (Equivalent Spherical Diameter, ESD = 5.6 microm). We also calculated grazing coefficients by combining field data on abundances of C. polykrikoides and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Cocholdinium polykrikoides fed on prey cells by engulfing the prey through the sulcus. Among the phytoplankton prey offered, C. polykrikoides ingested small phytoplankton species that had ESD's or = 12 microm (e.g. the dinoflagellates Heterocapsa triquetra, Prorocentrum minimum, Scrippsiella sp., Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum). Specific growth rates of C. polykrikoides on a cryptophyte increased with increasing mean prey concentration, with saturation at a mean prey concentration of approximately 270 ng C ml(-1) (i.e. 15,900 cells ml(-1)). The maximum specific growth rate (mixotrophic growth) of C. polykrikoides on a cryptophyte was 0.324 d(-1), under a 14:10 h light-dark cycle of 50 microE m(-2) s(-1), while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.166 d(-1). Maximum ingestion and clearance rates of C. polykrikoides on a cryptophyte were 0.16 ng C grazer(-1)d(-1) (9.4 cells grazer(-1)d(-1)) and 0.33 microl grazer(-1)h(-1), respectively. Calculated grazing coefficients by C. polykrikoides on cryptophytes were 0.001-0.745 h(-1) (i.e. 0.1-53% of cryptophyte populations were removed by a C. polykrikoides population in 1 h). The results of the present study suggest that C. polykrikoides sometimes has a considerable grazing impact on populations of cryptophytes.
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ingestion of cryptophyte cells by the marine photosynthetic ciliate mesodinium rubrum
Aquatic Microbial Ecology, 2004Co-Authors: Wonho Yih, Hae Jin Jeong, Hyung Seop Kim, Geumog Myung, Young Geel KimAbstract:We investigated the mechanism of capturing and ingesting cryptophyte cells by a labo- ratory strain of the marine photosynthetic ciliate Mesodinium rubrum Lohmann 1908 (= Myrionecta rubra Jankowski 1976), a cosmopolitan red tide species. When offered cryptophytes as food, M. rubrum, originally grown photosynthetically for 2 wk, used its bifurcated oral tentacles to instantly seize prey cells when encountered. Immediately after capturing a prey cell, M. rubrum swam in a zigzag pattern (30 to 60 µm long linear paths) for >4 s, without showing the large jumps (with ca. 2000 µm long linear paths) that were usually observed when the predator was not feeding. M. rubrum with a cryptophyte attached to its tentacles became motionless while the prey cell was moved to the oral surface of the predator, a process that took <10 s. Engulfment of a captured prey cell by M. rubrum occurred through a cytostome-like structure and took ca. 15 s. Once engulfed, the prey was slowly delivered to the posterior end of the ciliate over a period of ca. 63 s. The whole feeding process lasted approximately 92 s. With increasing mean prey concentration, specific growth rates of M. rubrum feeding on the cryptophyte increased, with saturation at a mean prey concentration of 44 cells ml -1 . The maximum specific growth rate (mixotrophic growth) of M. rubrum feeding on the cryptophyte was 0.521 d -1 , under continuous illumination of 60 µE m -2 s -1 , while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.357 d -1 . The inges- tion rate of M. rubrum feeding on cryptophytes increased continuously with increasing prey concen- tration. The maximum ingestion rate was 8.9 cryptophytes ciliate -l d -1 . M. rubrum may sometimes
John M Archibald - One of the best experts on this subject based on the ideXlab platform.
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Comparative mitochondrial genomics of cryptophyte algae: gene shuffling and dynamic mobile genetic elements
BMC Genomics, 2018Co-Authors: Jong Im Kim, Hwan Su Yoon, Woongghi Shin, John M ArchibaldAbstract:Background Cryptophytes are an ecologically important group of algae comprised of phototrophic, heterotrophic and osmotrophic species. This lineage is of great interest to evolutionary biologists because their plastids are of red algal secondary endosymbiotic origin. Cryptophytes have a clear phylogenetic affinity to heterotrophic eukaryotes and possess four genomes: host-derived nuclear and mitochondrial genomes, and plastid and nucleomorph genomes of endosymbiotic origin. Results To gain insight into cryptophyte mitochondrial genome evolution, we sequenced the mitochondrial DNAs of five species and performed a comparative analysis of seven genomes from the following cryptophyte genera: Chroomonas , Cryptomonas , Hemiselmis , Proteomonas , Rhodomonas , Storeatula and Teleaulax . The mitochondrial genomes were similar in terms of their general architecture, gene content and presence of a large repeat region. However, gene order was poorly conserved. Characteristic features of cryptophyte mtDNAs included large syntenic clusters resembling α-proteobacterial operons that encode bacteria-like rRNAs, tRNAs, and ribosomal protein genes. The cryptophyte mitochondrial genomes retain almost all genes found in many other eukaryotes including the nad , sdh , cox , cob , and atp genes, with the exception of sdh 2 and atp 3. In addition, gene cluster analysis showed that cryptophytes possess a gene order closely resembling the jakobid flagellates Jakoba and Reclinomonas . Interestingly, the cox 1 gene of R. salina , T. amphioxeia , and Storeatula species was found to contain group II introns encoding a reverse transcriptase protein, as did the cob gene of Storeatula species CCMP1868. Conclusions These newly sequenced genomes increase the breadth of data available from algae and will aid in the identification of general trends in mitochondrial genome evolution. While most of the genomes were highly conserved, extensive gene arrangements have shuffled gene order, perhaps due to genome rearrangements associated with hairpin-containing mobile genetic elements, tRNAs with palindromic sequences, and tandem repeat sequences. The cox 1 and cob gene sequences suggest that introns have recently been acquired during cryptophyte evolution. Comparison of phylogenetic trees based on plastid and mitochondrial genome data sets underscore the different evolutionary histories of the host and endosymbiont components of present-day cryptophytes.
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nucleomorph genome sequence of the cryptophyte alga chroomonas mesostigmatica ccmp1168 reveals lineage specific gene loss and genome complexity
Genome Biology and Evolution, 2012Co-Authors: Christa E Moore, Bruce A Curtis, Tyler Mills, Goro Tanifuji, John M ArchibaldAbstract:Cryptophytes are a diverse lineage of marine and freshwater, photosynthetic and secondarily nonphotosynthetic algae that acquired their plastids (chloroplasts) by “secondary” (i.e., eukaryote–eukaryote) endosymbiosis. Consequently, they are among the most genetically complex cells known and have four genomes: a mitochondrial, plastid, “master” nuclear, and residual nuclear genome of secondary endosymbiotic origin, the so-called “nucleomorph” genome. Sequenced nucleomorph genomes are ∼1,000-kilobase pairs (Kbp) or less in size and are comprised of three linear, compositionally biased chromosomes. Although most functionally annotated nucleomorph genes encode proteins involved in core eukaryotic processes, up to 40% of the genes in these genomes remain unidentifiable. To gain insight into the function and evolutionary fate of nucleomorph genomes, we used 454 and Illumina technologies to completely sequence the nucleomorph genome of the cryptophyte Chroomonas mesostigmatica CCMP1168. At 702.9 Kbp in size, the C. mesostigmatica nucleomorph genome is the largest and the most complex nucleomorph genome sequenced to date. Our comparative analyses reveal the existence of a highly conserved core set of genes required for maintenance of the cryptophyte nucleomorph and plastid, as well as examples of lineage-specific gene loss resulting in differential loss of typical eukaryotic functions, e.g., proteasome-mediated protein degradation, in the four cryptophyte lineages examined.
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complete sequence and analysis of the mitochondrial genome of hemiselmis andersenii ccmp644 cryptophyceae
BMC Genomics, 2008Co-Authors: Eunsoo Kim, Christopher E Lane, Catherine Kozera, Bruce A Curtis, Sharen Bowman, John M ArchibaldAbstract:Cryptophytes are an enigmatic group of unicellular eukaryotes with plastids derived by secondary (i.e., eukaryote-eukaryote) endosymbiosis. Cryptophytes are unusual in that they possess four genomes–a host cell-derived nuclear and mitochondrial genome and an endosymbiont-derived plastid and 'nucleomorph' genome. The evolutionary origins of the host and endosymbiont components of cryptophyte algae are at present poorly understood. Thus far, a single complete mitochondrial genome sequence has been determined for the cryptophyte Rhodomonas salina. Here, the second complete mitochondrial genome of the cryptophyte alga Hemiselmis andersenii CCMP644 is presented. The H. andersenii mtDNA is 60,553 bp in size and encodes 30 structural RNAs and 36 protein-coding genes, all located on the same strand. A prominent feature of the genome is the presence of a ~20 Kbp long intergenic region comprised of numerous tandem and dispersed repeat units of between 22–336 bp. Adjacent to these repeats are 27 copies of palindromic sequences predicted to form stable DNA stem-loop structures. One such stem-loop is located near a GC-rich and GC-poor region and may have a regulatory function in replication or transcription. The H. andersenii mtDNA shares a number of features in common with the genome of the cryptophyte Rhodomonas salina, including general architecture, gene content, and the presence of a large repeat region. However, the H. andersenii mtDNA is devoid of inverted repeats and introns, which are present in R. salina. Comparative analyses of the suite of tRNAs encoded in the two genomes reveal that the H. andersenii mtDNA has lost or converted its original trnK(uuu) gene and possesses a trnS-derived 'trnK(uuu)', which appears unable to produce a functional tRNA. Mitochondrial protein coding gene phylogenies strongly support a variety of previously established eukaryotic groups, but fail to resolve the relationships among higher-order eukaryotic lineages. Comparison of the H. andersenii and R. salina mitochondrial genomes reveals a number of cryptophyte-specific genomic features, most notably the presence of a large repeat-rich intergenic region. However, unlike R. salina, the H. andersenii mtDNA does not possess introns and lacks a Lys-tRNA, which is presumably imported from the cytosol.
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nucleomorph genome of hemiselmis andersenii reveals complete intron loss and compaction as a driver of protein structure and function
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Christopher E Lane, Catherine Kozera, Bruce A Curtis, Byron J Parsons, Sharen Bowman, Krystal Van Den Heuvel, John M ArchibaldAbstract:Abstract Nucleomorphs are the remnant nuclei of algal endosymbionts that took up residence inside a nonphotosynthetic eukaryotic host. The nucleomorphs of cryptophytes and chlorarachniophytes are derived from red and green algal endosymbionts, respectively, and represent a stunning example of convergent evolution: their genomes have independently been reduced and compacted to <1 megabase pairs (Mbp) in size (the smallest nuclear genomes known) and to a similar three-chromosome architecture. The molecular processes underlying genome reduction and compaction in eukaryotes are largely unknown, as is the impact of reduction/compaction on protein structure and function. Here, we present the complete 0.572-Mbp nucleomorph genome of the cryptophyte Hemiselmis andersenii and show that it is completely devoid of spliceosomal introns and genes for splicing RNAs—a case of complete intron loss in a nuclear genome. Comparison of H. andersenii proteins to those encoded in the slightly smaller (0.551-Mbp) nucleomorph genome of another cryptophyte, Guillardia theta, and to their homologs in the unicellular red alga Cyanidioschyzon merolae reveal that (i) cryptophyte nucleomorph genomes encode proteins that are significantly smaller than those in their free-living algal ancestors, and (ii) the smaller, more compact G. theta nucleomorph genome encodes significantly smaller proteins than that of H. andersenii. These results indicate that genome compaction can eliminate both coding and noncoding DNA and, consequently, drive the evolution of protein structure and function. Nucleomorph proteins have the potential to reveal the minimal functional units required for basic eukaryotic cellular processes. endosymbiosis genome evolution genome reduction
Uwe G. Maier - One of the best experts on this subject based on the ideXlab platform.
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Nucleus-to-nucleus gene transfer and protein retargeting into a remnant cytoplasm of cryptophytes and diatoms
Molecular Biology and Evolution, 2006Co-Authors: Sven B. Gould, Gillian H Gile, Maik S Sommer, Peter G Kroth, Uwe G. MaierAbstract:The complex plastid of the cryptophyte Guillardia theta and of the diatom Phaeodactylum tricornutum can both be traced back to an engulfed eukaryotic red alga. The eukaryotic origin of these plastids is most obvious in cryptophytes, where the organelle still possesses a remnant nucleus, the nucleomorph. The nucleomorph itself is embedded in the periplastid compartment (PPC), the remnant of the former red algal cytosol. In the cryptophyte and diatom, the complex plastid is surrounded by 4 membranes, the outer one being continuous with the host rough endoplasmatic reticulum. In a recent report, we have shown that a nuclear encoded PPC protein of G. theta expressed in P. tricornutum leads to a localization, recently described as being a "bloblike structure," which can be obtained by mutation of plastid protein-targeting sequences of the diatom itself. Here we present further nucleus-encoded PPC proteins from G. theta, such as the eukaryotic translation elongation factor-1alpha, evidence for their nucleus-to-nucleus gene transfer, and retargeting of the proteins. We also investigated the first nuclear encoded PPC-targeted protein of P. tricornutum (Hsp70) and analyzed it for in vivo localization together with the identified G. theta PPC proteins. This revealed that all localize to the bloblike structures, which we suggest is the highly reduced PPC of P. tricornutum. Furthermore, the described cryptophyte PPC proteins possibly allow the elucidation of the processes by which proteins are involved in different levels of host control over its eukaryotic organelle.
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molecular phylogeny of the stress 70 protein family with reference to algal relationships
European Journal of Phycology, 1997Co-Authors: Stefan A Rensing, Caudia Jb Hofmann, Petr Obrdlik, Nicole Roberkleber, Sabine Muller, Yves Van De Peer, Uwe G. MaierAbstract:The stress-70 protein family has previously been shown to be a useful tool for molecular phylogeny at the kingdom to family levels. Although sequences of many members of the stress-70 family are available, few genes from the Protoctista have been sequenced to date. Phylogenetic analyses of algae based on various molecules have not, as yet, provided clear results concerning relationships between major divisions. We cloned and sequenced several algal stress-70 genes in order to provide additional data and to further analyse phylogenetic relationships among algal divisions. New nuclear sequences were obtained from Guillardia theta (Cryptophyta), Ascophyllum nodosum (Heterokontophyta) and Cyanophora paradoxa (Glaucocystophyta). Phylogenetic trees of the stress-70 protein family calculated using different methods are presented. In our trees, the heterokont alga Ascophyllum nodosum is closely related to the slime mould Dictyostelium discoideum, while the nucleomorph (eukaryotic endosymbiont) of the cryptophyte ...
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the four genomes of the alga pyrenomonas salina Cryptophyta
BioSystems, 1992Co-Authors: Uwe G. MaierAbstract:Cryptomonads are a group of unicellular eukaryotic algae with unusual features. First, their plastids are surrounded by four membranes and second, between the two pairs of membranes there is a plasmatic compartment. This supernumerary eukaryotic compartment of the cryptomonad cell is devoid of mitochondria but contains starch grains, 80S ribosomes and a small vestigial eukaryotic nucleus called the nucleomorph. Isolation and characterization of the four genomes (from mitochondrion, plastid, nucleus and nucleomorph) of one cryptomonad, Pyrenomonas salina, demonstrates that the cryptomonads have originated from an unicellular organism related to green algae which endosymbiotically took up a eukaryotic protist related to the red algae.
Hae Jin Jeong - One of the best experts on this subject based on the ideXlab platform.
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feeding by the pfiesteria like heterotrophic dinoflagellate luciella masanensis
Journal of Eukaryotic Microbiology, 2007Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jae Yeon Park, Jong Hyeok Kim, Tae Hoon Kim, Hyung Seop Kim, Wonho YihAbstract:To explore the feeding ecology of the Pfiesteria-like dinoflagellate (PLD) Luciella masanensis (GenBank Accession no. AM050344, previously Lucy), we investigated the feeding behavior and the kinds of prey species that L. masanensis fed on and determined its growth and ingestion rates of L. masanensis when it fed on the dinoflagellate Amphidinium carterae and an unidentified cryptophyte species (equivalent spherical diam., ESD=5.6 microm), which were the dominant phototrophic species when L. masanensis and similar small heterotrophic dinoflagellates were abundant in Masan Bay, Korea in 2005. Additionally, these parameters were also measured for L. masanensis fed on blood cells of the perch Lateolabrax japonicus and the raphidophyte Heterosigma akashiwo in the laboratory. Luciella masanensis fed on prey cells by using a peduncle after anchoring the prey with tow filament, and was able to feed on diverse prey such as cryptophytes, raphidophytes, diatoms, mixotrophic dinoflagellates, and the blood cells of fish and humans. Among the prey species tested in the present study, perch blood cells were observed to be the optimal prey for L. masanensis. Specific growth rates of L. masanensis feeding on perch blood cells, A. carterae, H. akashiwo, and the cryptophyte, either increased continuously or became saturated with increasing the mean prey concentration. The maximum specific growth rate of L. masanensis feeding on perch blood cells (1.46/day) was much greater than that of A. carterae (0.59/day), the cryptophyte (0.24/day), or H. akashiwo (0.20/day). The maximum ingestion rate of L. masanensis on perch blood cells (2.6 ng C/grazer/day) was also much higher than that of A. carterae (0.32 ng C/grazer/day), the cryptophyte (0.44 ng C/grazer/day), or H. akashiwo (0.16 ng C/grazer/day). The kinds of prey species which L. masanensis is able to feed on were the same as those of Pfiesteria piscicida, but very different from those of another PLD Stoeckeria algicida. However, the maximum growth and ingestion rates of L. masanensis on perch blood cells, A. carterae, H. akashiwo, and the cryptophyte were considerably lower than those of P. piscicida. Therefore, these three dinoflagellates may occupy different ecological niches in marine planktonic communities, even though they have a similar size and shape and the same feeding mechanisms.
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Distribution of the heterotrophic dinoflagellate Pfiesteria piscicida in Korean waters and its consumption of mixotrophic dinoflagellates, raphidophytes and fish blood cells
Aquatic Microbial Ecology, 2006Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jae Yeon Park, Jong Hyeok Kim, Sanghee Kim, Jae Seong Kim, Wonho YihAbstract:To explore the distribution of Pfiesteria piscicida in Korean coastal waters, we analyzed the morphology and DNA sequence of several isolates collected from 6 locations along the southern and western Korean coasts. We also investigated the prey species consumed by a Korean isolate and determined the growth and ingestion rates of P. piscicida when it fed on the dinoflagellate Amphidinium carterae, an unidentified cryptophyte species, and the raphidophyte Heterosigma akashiwo. Additionally, these parameters were measured when the isolate was fed perch blood cells and the cryptophyte Rhodomonas salina. Furthermore, we calculated grazing coefficients by combining field data on abundance of P. piscicida (and Pfiesteria-like dinoflagellates) with laboratory data on ingestion rates. The DNA sequence of a P. piscicida isolate from Masan Bay was identical to USA isolates, whereas DNA sequences of isolates from Busan, Incheon, Kunsan, Kwangyang, and Yeosu differed by 1 bp from USA isolates. Among the prey offered, P. piscicida was able to feed on all naked mixotrophic dinoflagellates, the smallest thecate mixotrophic dinoflagellates Heterocapsa rotundata, and all raphidophytes, but not on large thecate dinoflagellates. Perch blood cells were the optimal prey. Maximum growth rates of P. piscicida fed on perch blood cells, R. salina, A. carterae, the cryptophyte, and H. akashiwo were 1.74, 1.41, 1.22, 1.15, and 1.10 d -1 , respectively. The maximum ingestion rate of P. piscicida when fed perch blood cells (4.3 ng C predator -1 d -1 ) was much higher than those when fed R. salina, H. akashiwo, A. carterae, or the cryptophyte (0.4 to 1.7 ng C predator -1 d -1 ). Calculated grazing coefficients on co-occurring Amphidinium spp., H. akashiwo, and cryptophytes were up to 1.07, 0.45, and 0.22 h -1 , respectively. Our results suggest that grazing by P. piscicida potentially has a considerable effect on algal populations.
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feeding by the mixotrophic red tide dinoflagellate gonyaulax polygramma mechanisms prey species effects of prey concentration and grazing impact
Aquatic Microbial Ecology, 2005Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Jae Yeon Park, Jong Hyeok Kim, Sanghee Kim, Kyeong Ah Seong, Seung Hyeon Lee, Wonho YihAbstract:The red-tide dinoflagellate Gonyaulax polygramma (GenBank accession number = AJ833631), previously known as an exclusively autotrophic dinoflagellate, has been found to be a mixotrophic species. We investigated feeding mechanisms, types of prey species, and the effects of prey concentration on the growth and ingestion rates of G. polygramma when feeding on an uniden- tified cryptophyte species (equivalent spherical diameter, ESD = 5.6 µm). We also calculated grazing coefficients by combining field data on abundances of G. polygramma and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Among the phytoplankton prey offered, G. polygramma ingested small phytoplankton species with ESD ≤ 17 µm, but did not feed on large phytoplankton species with ESD > 22 µm. G. polygramma fed on prey cells by engulfing them through the apical horn, a previously unknown mechanism, as well as through the sulcus. The feed- ing mechanism of G. polygramma on phytoplankton mainly depended on the prey species. Specific growth rates of G. polygramma on a cryptophyte increased with increasing mean prey concentration, with saturation occurring at a mean prey concentration of approximately 600 ng C ml -1 . The maxi- mum specific (mixotrophic) growth rate of G. polygramma on a cryptophyte was 0.278 d -1 , under a 14:10 h light:dark cycle of 50 µE m -2 s -1 , while its (phototrophic) growth rate under the same light conditions without added prey was 0.186 d -1 . Its maximum ingestion and clearance rates were 0.18 ng C grazer -1 d -1 (10.6 cells grazer -1 d -1 ) and 0.18 µl grazer -1 h -1 , respectively. The grazing coefficients of G. polygramma on cryptophytes were up to 0.479 h -1 . The results of the present study suggest that G. polygramma can have a considerable grazing impact on cryptophyte populations.
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mixotrophy in the phototrophic harmful alga cochlodinium polykrikoides dinophycean prey species the effects of prey concentration and grazing impact
Journal of Eukaryotic Microbiology, 2004Co-Authors: Hae Jin Jeong, Yeong Du Yoo, Nam Seon Kang, Jong Hyeok Kim, Jae Seong Kim, Tab Hoon Kim, Wonho YihAbstract:We first reported here that the harmful alga Cochlodinium polykrikoides, which had been previously known as an autotrophic dinoflagellate, was a mixotrophic species. We investigated the kinds of prey species and the effects of the prey concentration on the growth and ingestion rates of C. polykrikoides when feeding on an unidentified cryptophyte species (Equivalent Spherical Diameter, ESD = 5.6 microm). We also calculated grazing coefficients by combining field data on abundances of C. polykrikoides and co-occurring cryptophytes with laboratory data on ingestion rates obtained in the present study. Cocholdinium polykrikoides fed on prey cells by engulfing the prey through the sulcus. Among the phytoplankton prey offered, C. polykrikoides ingested small phytoplankton species that had ESD's or = 12 microm (e.g. the dinoflagellates Heterocapsa triquetra, Prorocentrum minimum, Scrippsiella sp., Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum). Specific growth rates of C. polykrikoides on a cryptophyte increased with increasing mean prey concentration, with saturation at a mean prey concentration of approximately 270 ng C ml(-1) (i.e. 15,900 cells ml(-1)). The maximum specific growth rate (mixotrophic growth) of C. polykrikoides on a cryptophyte was 0.324 d(-1), under a 14:10 h light-dark cycle of 50 microE m(-2) s(-1), while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.166 d(-1). Maximum ingestion and clearance rates of C. polykrikoides on a cryptophyte were 0.16 ng C grazer(-1)d(-1) (9.4 cells grazer(-1)d(-1)) and 0.33 microl grazer(-1)h(-1), respectively. Calculated grazing coefficients by C. polykrikoides on cryptophytes were 0.001-0.745 h(-1) (i.e. 0.1-53% of cryptophyte populations were removed by a C. polykrikoides population in 1 h). The results of the present study suggest that C. polykrikoides sometimes has a considerable grazing impact on populations of cryptophytes.
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ingestion of cryptophyte cells by the marine photosynthetic ciliate mesodinium rubrum
Aquatic Microbial Ecology, 2004Co-Authors: Wonho Yih, Hae Jin Jeong, Hyung Seop Kim, Geumog Myung, Young Geel KimAbstract:We investigated the mechanism of capturing and ingesting cryptophyte cells by a labo- ratory strain of the marine photosynthetic ciliate Mesodinium rubrum Lohmann 1908 (= Myrionecta rubra Jankowski 1976), a cosmopolitan red tide species. When offered cryptophytes as food, M. rubrum, originally grown photosynthetically for 2 wk, used its bifurcated oral tentacles to instantly seize prey cells when encountered. Immediately after capturing a prey cell, M. rubrum swam in a zigzag pattern (30 to 60 µm long linear paths) for >4 s, without showing the large jumps (with ca. 2000 µm long linear paths) that were usually observed when the predator was not feeding. M. rubrum with a cryptophyte attached to its tentacles became motionless while the prey cell was moved to the oral surface of the predator, a process that took <10 s. Engulfment of a captured prey cell by M. rubrum occurred through a cytostome-like structure and took ca. 15 s. Once engulfed, the prey was slowly delivered to the posterior end of the ciliate over a period of ca. 63 s. The whole feeding process lasted approximately 92 s. With increasing mean prey concentration, specific growth rates of M. rubrum feeding on the cryptophyte increased, with saturation at a mean prey concentration of 44 cells ml -1 . The maximum specific growth rate (mixotrophic growth) of M. rubrum feeding on the cryptophyte was 0.521 d -1 , under continuous illumination of 60 µE m -2 s -1 , while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.357 d -1 . The inges- tion rate of M. rubrum feeding on cryptophytes increased continuously with increasing prey concen- tration. The maximum ingestion rate was 8.9 cryptophytes ciliate -l d -1 . M. rubrum may sometimes
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grazing of two euplotid ciliates on the heterotrophic dinoflagellates pfiesteria piscicida and cryptoperidiniopsis sp
Aquatic Microbial Ecology, 2003Co-Authors: Scott G Gransden, Alan J. LewitusAbstract:Pfiesteria piscicida and Cryptoperidiniopsis spp. are common co-occurring heterotrophic dinoflagellates in estuaries along the Atlantic coast of the United States. We isolated P. piscicida, Cryptoperidiniopsis sp., and 2 benthic ciliates (Euplotes vannus and E. woodruffi) from North Inlet estuary, South Carolina, and examined the growth and graz- ing properties of the ciliates on cultures of the dinoflagellates maintained with cryptophyte (Storeatula major) prey. Ciliate growth and grazing parameters on cryptophyte monocultures and mixed diets of cryptophytes and P. piscicida were signifi- cantly higher with E. woodruffi than E. vannus. Also, the net grazing impact of E. woodruffi on P. piscicida prey was higher than the impact on Cryptoperidiniopsis sp., while the E. van- nus grazing effect did not differ with dinoflagellate prey. The results indicate the potential for effective predatory con- trol by euplotid ciliates on nontoxic P. piscicida and Crypto- peridiniopsis sp. under defined laboratory conditions.
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kleptoplastidy in the toxic dinoflagellate pfiesteria piscicida dinophyceae
Journal of Phycology, 1999Co-Authors: Alan J. Lewitus, Jo Ann M. BurkholderAbstract:The ichthyotoxic dinoflagellate Pfiesteria piscicida Steidinger et Burkholder has a complex life cycle with several heterotrophic flagellated and amoeboid stages. A prevalent flagellated form, the nontoxic zoospore stage, has a proficient grazing ability, especially on cryptophyte prey. Although P. piscicida zoospores lack the genetic capability to synthesize chloroplasts, they can obtain functional chloroplasts from algal prey (i.e. kleptoplastidy), as demonstrated here with a cryptophyte prey. Zoospores grown with Rhodomonas sp. Karsten CCMP757 (Cryptophyceae) grazed the cryptophyte population to minimal densities. After placing the cultures in near darkness where cryptophyte recovery was restricted and further prey ingestion did not occur, the time-course patterns in growth, prey chloroplast content·zoospore−1, and prey nucleus content·zoospore−1 were followed. Ingested chloroplasts were selectively retained in the dinoflagellate, as indicated by the decline and, ultimately, near absence of cryptophyte nuclei in plastid-containing zoospores. Chloroplasts retained inside P. piscicida cells for at least a week were photosynthetically active, as indicated by starch accumulation and microscope-autoradiographic measurements of bicarbonate uptake. Recognition that P. piscicida can function as a phototroph broadens our perspective of the physiological ecology of the dinoflagellate because it suggests that, at least during part of its life cycle, P. piscicida’s growth and survival might be affected by photoregulation and nutritional control of photosynthesis.