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Cuadrado Á, Montiel EE, Mora P, Figueroa RI, Lorite P, de Bustos A. Contribution of the satellitome to the exceptionally large genome of dinoflagellates: The case of the harmful alga Alexandrium minutum. HARMFUL ALGAE 2023; 130:102543. [PMID: 38061820 DOI: 10.1016/j.hal.2023.102543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/30/2023] [Accepted: 11/11/2023] [Indexed: 12/18/2023]
Abstract
Dinoflagellates are known to possess an exceptionally large genome organized in permanently condensed chromosomes. Focusing on the contribution of satellite DNA (satDNA) to the whole DNA content of genomes and its potential role in the architecture of the chromosomes, we present the characterization of the satellitome of Alexandriun minutum strain VGO577. To achieve this, we analyzed Illumina reads using graph-based clustering and performed complementary bioinformatic analyses. In this way, we discovered 180 satDNAs occupying 17.38 % of the genome. The 12 most abundant satDNAs represent the half of the satellitome but no satDNA is overrepresented, with the most abundant contributing ∼1.56 % of the genome. The largest repeat unit is 517 bp long but more than the half of the satDNAs (101) have repeat units shorter than 20 bp. We used FISH to map a selected set of 26 satDNAs. Although some satDNAs generate discrete hybridization signals at specific chromosomal locations (hybridization sites, HS), our cytological analysis showed that most satDNAs are dispersed throughout the genome, probably forming short arrays. Two satDNAs co-localize with the 45S rDNA. With the exception of telomeric DNA, no other satDNA yields HS on all chromosomes. In addition, we analyzed nine satDNAs yielding HS in VGO577 in four other A. minutum strains. Polymorphism at the intraspecific level was found for the presence/absence and/or abundance of some satDNAs, suggesting the amplification/deletion of these satDNAs following geographic separation or during culture maintenance of the strains. We also discuss how these results contribute to the understanding of chromosome architecture and evolution of dinoflagellate genomes.
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Affiliation(s)
- Ángeles Cuadrado
- Department of Biomedicine and Biotecnology, Universidad de Alcalá (UAH), Alcalá de Henares, Madrid 28805, Spain.
| | - Eugenia E Montiel
- Department of Experimental Biology (Genetics Area), Human and Animal Molecular Genetic Group (RNM-924), Universidad de Jaén, Jaén 23071, Spain; Departamento de Biología (Genética), Universidad Autonoma de Madrid, Madrid 28049, Spain
| | - Pablo Mora
- Department of Experimental Biology (Genetics Area), Human and Animal Molecular Genetic Group (RNM-924), Universidad de Jaén, Jaén 23071, Spain
| | - Rosa I Figueroa
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50, Vigo 36390, Spain
| | - Pedro Lorite
- Department of Experimental Biology (Genetics Area), Human and Animal Molecular Genetic Group (RNM-924), Universidad de Jaén, Jaén 23071, Spain
| | - Alfredo de Bustos
- Department of Biomedicine and Biotecnology, Universidad de Alcalá (UAH), Alcalá de Henares, Madrid 28805, Spain
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Mustansar T, Mirza T, Hussain M. RAS gene mutations and histomorphometric measurements in oral squamous cell carcinoma. Biotech Histochem 2023; 98:382-390. [PMID: 37013448 DOI: 10.1080/10520295.2023.2196731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
Abstract
Members of the RAS gene family frequently are mutated in cancers including oral squamous cell carcinoma (OSCC). We investigated the correlation of histological characteristics of OSCC with RAS gene mutations. We graded tumors and extracted genomic DNA from OSCC. The first two exons of KRAS, HRAS and NRAS genes were subjected to PCR amplification and DNA sequencing followed by bioinformatic analysis to explore the structural and functional impact of the mutations on encoding of proteins. Cellular and nuclear diameters in histological sections were varied in all grades of cancer. Using sequence analysis, we identified nonsynonymous mutations in both HRAS (G12S, G15C, D54H, Q61H, Q61L, E62D, E63D, Q70E, Q70V) and NRAS (Q22P, K88R). Stop codon mutations, however, were observed in KRAS. Spatial orientation of substituted amino acids was observed despite conservation of overall structure of variant proteins. Our findings suggest that KRAS may be mutated more frequently in OSCC compared to HRAS and NRAS. Also, the histological features of nuclear and cellular diameter differed significantly between the KRAS mutated and unmutated cases.
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Affiliation(s)
- Tazeen Mustansar
- Department of Pathology, Dow University of Health Sciences, Karachi, Pakistan
| | | | - Mushtaq Hussain
- Bioinformatics and Molecular Medicine Research Group, Dow Research Institute of Biotechnology and Biomedical Sciences, Dow College of Biotechnology, Dow University of Health Sciences, Karachi, Pakistan
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Millette NC, Gast RJ, Luo JY, Moeller HV, Stamieszkin K, Andersen KH, Brownlee EF, Cohen NR, Duhamel S, Dutkiewicz S, Glibert PM, Johnson MD, Leles SG, Maloney AE, Mcmanus GB, Poulton N, Princiotta SD, Sanders RW, Wilken S. Mixoplankton and mixotrophy: future research priorities. JOURNAL OF PLANKTON RESEARCH 2023; 45:576-596. [PMID: 37483910 PMCID: PMC10361813 DOI: 10.1093/plankt/fbad020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/14/2023] [Indexed: 07/25/2023]
Abstract
Phago-mixotrophy, the combination of photoautotrophy and phagotrophy in mixoplankton, organisms that can combine both trophic strategies, have gained increasing attention over the past decade. It is now recognized that a substantial number of protistan plankton species engage in phago-mixotrophy to obtain nutrients for growth and reproduction under a range of environmental conditions. Unfortunately, our current understanding of mixoplankton in aquatic systems significantly lags behind our understanding of zooplankton and phytoplankton, limiting our ability to fully comprehend the role of mixoplankton (and phago-mixotrophy) in the plankton food web and biogeochemical cycling. Here, we put forward five research directions that we believe will lead to major advancement in the field: (i) evolution: understanding mixotrophy in the context of the evolutionary transition from phagotrophy to photoautotrophy; (ii) traits and trade-offs: identifying the key traits and trade-offs constraining mixotrophic metabolisms; (iii) biogeography: large-scale patterns of mixoplankton distribution; (iv) biogeochemistry and trophic transfer: understanding mixoplankton as conduits of nutrients and energy; and (v) in situ methods: improving the identification of in situ mixoplankton and their phago-mixotrophic activity.
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Affiliation(s)
| | - Rebecca J Gast
- Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
| | - Jessica Y Luo
- NOAA Geophysical Fluid Dynamics Laboratory, 201 Forrestal Rd., Princeton, NJ 08540, USA
| | - Holly V Moeller
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, 1120 Noble Hall, Santa Barbara, CA 93106, USA
| | - Karen Stamieszkin
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Ken H Andersen
- Center for Ocean Life, Natl. Inst. of Aquatic Resources, Technical University of Denmark, Kemitorvet, Bygning 202, Kongens Lyngby 2840, Denmark
| | - Emily F Brownlee
- Department of Biology, St. Mary’s College of Maryland, 18952 E. Fisher Road, St. Mary’s City, MD 20686, USA
| | - Natalie R Cohen
- Skidaway Institute of Oceanography, University of Georgia, 10 Ocean Science Circle, Savannah, GA 31411, USA
| | - Solange Duhamel
- Department of Molecular and Cellular Biology, The University of Arizona, 1007 E Lowell Street, Tucson, AZ 85721, USA
| | - Stephanie Dutkiewicz
- Center for Global Change Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02874, USA
| | - Patricia M Glibert
- Horn Point Laboratory, University of Maryland Center for Environmental Science, 2020 Horns Point Rd, Cambridge, MD 21613, USA
| | - Matthew D Johnson
- Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
| | - Suzana G Leles
- Department of Marine and Environmental Biology, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| | - Ashley E Maloney
- Geosciences Department, Princeton University, Guyot Hall, Princeton, NJ 08544, USA
| | - George B Mcmanus
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Rd., Groton, CT 06340, USA
| | - Nicole Poulton
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Sarah D Princiotta
- Biology Department, Pennsylvania State University, Schuylkill Campus, 200 University Drive, Schuylkill Haven, PA 17972, USA
| | - Robert W Sanders
- Department of Biology, Temple University, 1900 N. 12th St., Philadelphia, PA 19122, USA
| | - Susanne Wilken
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, Amsterdam, 1098 XH, The Netherlands
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Gudagudi KB, d'Entrèves NP, Ollewagen T, Myburgh KH. Total mRNA and primary human myoblasts' in vitro cell cycle progression distinguishes between clones. Biochimie 2022; 196:161-170. [PMID: 35114349 DOI: 10.1016/j.biochi.2022.01.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 01/08/2022] [Accepted: 01/20/2022] [Indexed: 12/11/2022]
Abstract
Satellite cells are generally quiescent in vivo. Once activated, progression through the cell cycle begins. Immortalised myoblasts from a single cell line are fairly homogenous in culture, but primary human myoblasts (PHMs) demonstrate heterogeneity. This phenomenon is poorly understood however may impact on PHM expansion. This study aimed to evaluate cell cycle transition from growth to synthesis phases of the cell cycle (G1 to S phase) and total mRNA relevant to this transition in PHM clones derived from 2 donor biopsies. Proportions of cells transitioning from G1 to S phase were evaluated at 2-hourly intervals for 24 h (n = 3 for each) and total mRNA quantified. Both PHM clones revealed an exponential transition from G1 to S phase over time, with a significantly slower rate for PHMs from S9.1 compared to S6.3, which had a higher proportion of PHMs in S phase for most time-points (p < 0.05). After 24 h the proportion of PHMs in S phase was ∼13% (S6.3) compared to ∼22% (S9.1). Gene transcription increased as cells progressed from G1 to S phase. Although total RNA increased with similar linearity in both clones, S6.3 PHMs had consistently (10 out of 12 time points) significantly higher concentrations. Validating the 2-hourly assessment over 24 h, a 4-hourly assessment from 8 to 32 h revealed similar differences but included the beginning of a plateau. This study demonstrates that PHMs from different donors differ in both cell cycle progression and overall transcriptome revealing new aspects in the heterogeneity of isolated satellite cells in vitro.
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Affiliation(s)
- Kirankumar B Gudagudi
- Department of Physiological Sciences, Stellenbosch University, Matieland, Private Bag X1, Stellenbosch, 7602, South Africa.
| | - Niccolò Passerin d'Entrèves
- Department of Physiological Sciences, Stellenbosch University, Matieland, Private Bag X1, Stellenbosch, 7602, South Africa.
| | - Tracey Ollewagen
- Department of Physiological Sciences, Stellenbosch University, Matieland, Private Bag X1, Stellenbosch, 7602, South Africa.
| | - Kathryn H Myburgh
- Department of Physiological Sciences, Stellenbosch University, Matieland, Private Bag X1, Stellenbosch, 7602, South Africa.
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Obesity-linked circular RNA circTshz2-2 regulates the neuronal cell cycle and spatial memory in the brain. Mol Psychiatry 2021; 26:6350-6364. [PMID: 34561612 PMCID: PMC8760052 DOI: 10.1038/s41380-021-01303-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/26/2022]
Abstract
Metabolic syndromes, including obesity, cause neuropathophysiological changes in the brain, resulting in cognitive deficits. Only a few studies explored the contribution of non-coding genes in these pathophysiologies. Recently, we identified obesity-linked circular RNAs (circRNA) by analyzing the brain cortices of high-fat-fed obese mice. In this study, we scrutinized a conserved and neuron-specific circRNA, circTshz2-2, which affects neuronal cell cycle and spatial memory in the brain. Transcriptomic and cellular analysis indicated that circTshz2-2 dysregulation altered the expression of cell division-related genes and induced cell cycle arrest at the G2/M phase of the neuron. We found that circTshz2-2 bound to the YY1 transcriptional complex and suppressed Bdnf transcription. Suppression of circTshz2-2 increased BDNF expression and reduced G2/M checkpoint proteins such as Cyclin B2 and CDK1 through BDNF/TrkB signaling pathway, resulting in cell cycle arrest and neurite elongation. Inversely, overexpression of circTshz2-2 decreased BDNF expression, induced cell cycle proteins, and shortened the neurite length, indicating that circTshz2-2 regulates neuronal cell cycle and structure. Finally, we showed that circTshz2-2 affects spatial memory in wild-type and obese mice. Our data have revealed potential regulatory roles of obesity-related circTshz2-2 on the neuronal cell cycle and memory function providing a novel link between metabolic syndromes and cognitive deficits.
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de Bustos A, Figueroa RI, Sixto M, Bravo I, Cuadrado Á. The 5S rRNA genes in Alexandrium: their use as a FISH chromosomal marker in studies of the diversity, cell cycle and sexuality of dinoflagellates. HARMFUL ALGAE 2020; 98:101903. [PMID: 33129460 DOI: 10.1016/j.hal.2020.101903] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/25/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
Chromosomal markers of the diversity and evolution of dinoflagellates are scarce because the genomes of these organisms are unique among eukaryotes in terms of their base composition and chromosomal structure. Similarly, a lack of appropriate tools has hindered studies of the chromosomal localization of 5S ribosomal DNA (rDNA) in the nucleosome-less chromosomes of dinoflagellates. In this study, we isolated and cloned 5S rDNA sequences from various toxin-producing species of the genus Alexandrium and developed a fluorescence in situ hybridization (FISH) probe that allows their chromosomal localization. Our results can be summarized as follows: 1) The 5S rDNA unit is composed of a highly conserved 122-bp coding region and an intergenic spacer (IGS), the length and sequence of which are variable even within strains. 2) Three different IGS types, one containing the U6 small nuclear RNA (snRNA) gene, were found among four of the studied species (A. minutum, A. tamarense, A. catenella and A. pacificum). 3) In all strains investigated by FISH (A. minutum, A. tamarense, A. pacificum, A. catenella, A. andersonii and A. ostenfeldii), 5S rDNA gene arrays were separate from the nucleolar organizer region, which contains the genes for the large 45S pre-ribosomal RNA. 4) One to three 5S rDNA sites per haploid genome were detected, depending on the strains/species. Intraspecific variability in the number of 5S rDNA sites was determined among strains of A. minutum and A. pacificum. 5) 5S rDNA is a useful chromosomal marker of mitosis progression and can be employed to differentiate vegetative (haploid) vs. planozygotes (diploid) cells. Thus, the FISH probe (oligo-Dino5Smix5) developed in this study facilitates analyses of the diversity, cell cycle and life stages of the genus Alexandrium.
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Affiliation(s)
- Alfredo de Bustos
- Universidad de Alcalá (UAH), Dpto Biomedicina y Biotecnología, 28805 Alcalá de Henares, Madrid, Spain.
| | - Rosa I Figueroa
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain.
| | - Marta Sixto
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain; Campus do Mar, Facultad de Ciencias del Mar, Universidad de Vigo, 36311 Vigo, Spain.
| | - Isabel Bravo
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain.
| | - Ángeles Cuadrado
- Universidad de Alcalá (UAH), Dpto Biomedicina y Biotecnología, 28805 Alcalá de Henares, Madrid, Spain.
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Sneider A, Hah J, Wirtz D, Kim DH. Recapitulation of molecular regulators of nuclear motion during cell migration. Cell Adh Migr 2019; 13:50-62. [PMID: 30261154 PMCID: PMC6527386 DOI: 10.1080/19336918.2018.1506654] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/05/2018] [Accepted: 07/18/2018] [Indexed: 01/12/2023] Open
Abstract
Cell migration is a highly orchestrated cellular event that involves physical interactions of diverse subcellular components. The nucleus as the largest and stiffest organelle in the cell not only maintains genetic functionality, but also actively changes its morphology and translocates through dynamic formation of nucleus-bound contractile stress fibers. Nuclear motion is an active and essential process for successful cell migration and nucleus self-repairs in response to compression and extension forces in complex cell microenvironment. This review recapitulates molecular regulators that are crucial for nuclear motility during cell migration and highlights recent advances in nuclear deformation-mediated rupture and repair processes in a migrating cell.
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Affiliation(s)
- Alexandra Sneider
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Jungwon Hah
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Denis Wirtz
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Dong-Hwee Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
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Jia Y, Gao H, Tong M, Anderson DM. Cell cycle regulation of the mixotrophic dinoflagellate Dinophysis acuminata: Growth, photosynthetic efficiency and toxin production. HARMFUL ALGAE 2019; 89:101672. [PMID: 31672228 PMCID: PMC6914227 DOI: 10.1016/j.hal.2019.101672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/24/2019] [Accepted: 09/26/2019] [Indexed: 06/10/2023]
Abstract
The mixotrophic dinoflagellate Dinophysis acuminata is a widely distributed diarrhetic shellfish poisoning (DSP) producer. Toxin variability of Dinophysis spp. has been well studied, but little is known of the manner in which toxin production is regulated throughout the cell cycle in these species, in part due to their mixotrophic characteristics. Therefore, an experiment was conducted to investigate cell cycle regulation of growth, photosynthetic efficiency, and toxin production in D. acuminata. First, a three-step synchronization approach, termed "starvation-feeding-dark", was used to achieve a high degree of synchrony of Dinophysis cells by starving the cells for 2 weeks, feeding them once, and then placing them in darkness for 58 h. The synchronized cells started DNA synthesis (S phase) 10 h after being released into the light, initiated G2 growth stage eight hours later, and completed mitosis (M phase) 2 h before lights were turned on. The toxin content of three dominant toxins, okadaic acid (OA), dinophysistoxin-1 (DTX1) and pectenotoxin-2 (PTX2), followed a common pattern of increasing in G1 phase, decreasing on entry into the S phase, then increasing again in S phase and decreasing in M phase during the diel cell cycle. Specific toxin production rates were positive throughout the G1 and S phases, but negative during the transition from G1 to S phase and late in M phase, the latter reflecting cell division. All toxins were initially induced by the light and positively correlated with the percentage of cells in S phase, indicating that biosynthesis of Dinophysis toxins might be under circadian regulation and be most active during DNA synthesis.
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Affiliation(s)
- Ying Jia
- Ocean College, Zhejiang University, Zhoushan, 316021, China
| | - Han Gao
- Ocean College, Zhejiang University, Zhoushan, 316021, China
| | - Mengmeng Tong
- Ocean College, Zhejiang University, Zhoushan, 316021, China.
| | - Donald M Anderson
- Biology Department, Woods Hole Oceanographic Institute, Woods Hole, MA, 02543, USA
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Fagín E, Bravo I, Garrido JL, Rodríguez F, Figueroa RI. Scrippsiella acuminata versus Scrippsiella ramonii: A Physiological Comparison. Cytometry A 2019; 95:985-996. [PMID: 31273941 PMCID: PMC6771724 DOI: 10.1002/cyto.a.23849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 05/08/2019] [Accepted: 06/12/2019] [Indexed: 11/11/2022]
Abstract
Scrippsiella is a cosmopolitan dinoflagellate genus that is able to form Harmful Algal Blooms in coastal waters. The large physiological, morphological, and genetic variability that characterizes this genus suggest the existence of cryptic species. In this study, flow cytometric analyses were carried out to compare the cell cycle and life cycle of two Scrippsiella strains from two different species: Scrippsiella ramonii (VGO1053) and Scrippsiella acuminata (S3V). Both species were also investigated by internally transcribed spacer rDNA sequencing and high‐performance liquid chromatography‐based pigment analyses. The reddish‐brown color of S. acuminata and yellowish‐green hue of S. ramonii were consistent with the quantitative differences determined in their pigment profiles. Our results indicate that the cell cycle is light‐controlled and that it differs in the two species. S‐phase was detected during the light period in both, whereas the G2/M phase occurred during the light period in S. ramonii but under dark conditions in S. acuminata. The detection of 4C stages, mobile zygotes (planozygotes), and resting cysts in S. ramonii (nonclonal) provided convincing evidence of sexuality in this species. Sexual related processes were not found in the clonal S. acuminata strain, suggesting its heterothallic behavior (i.e., the need for outcrossing). The differences in the genome size of these species were examined as well. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.
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Affiliation(s)
- Elena Fagín
- Departamento de Microalgas Nocivas, IEO, Vigo, Spain
| | - Isabel Bravo
- Departamento de Microalgas Nocivas, IEO, Vigo, Spain
| | - José Luis Garrido
- Grupo de Fotobiología y Pigmentos del Fitoplancton, IIM-CSIC, Vigo, Spain
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Cuadrado Á, De Bustos A, Figueroa RI. Chromosomal markers in the genus Karenia: Towards an understanding of the evolution of the chromosomes, life cycle patterns and phylogenetic relationships in dinoflagellates. Sci Rep 2019; 9:3072. [PMID: 30816125 PMCID: PMC6395649 DOI: 10.1038/s41598-018-35785-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 11/07/2018] [Indexed: 12/12/2022] Open
Abstract
Dinoflagellates are a group of protists whose genome is unique among eukaryotes in terms of base composition, chromosomal structure and gene expression. Even after decades of research, the structure and behavior of their amazing chromosomes-which without nucleosomes exist in a liquid crystalline state-are still poorly understood. We used flow cytometry and fluorescence in situ hybridization (FISH) to analyze the genome size of three species of the toxic dinoflagellate genus Karenia as well the organization and behavior of the chromosomes in different cell-cycle stages. FISH was also used to study the distribution patterns of ribosomal DNA (45S rDNA), telomeric and microsatellites repeats in order to develop chromosomal markers. The results revealed several novel and important features regarding dinoflagellate chromosomes during mitosis, including their telocentric behavior and radial arrangement along the nuclear envelope. Additionally, using the (AG)10 probe we identified an unusual chromosome in K. selliformis and especially in K. mikimotoi that is characterized by AG repeats along its entire length. This feature was employed to easily differentiate morphologically indistinguishable life-cycle stages. The evolutionary relationship between Karenia species is discussed with respect to differences in both DNA content and the chromosomal distribution patterns of the DNA sequences analyzed.
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Affiliation(s)
- Ángeles Cuadrado
- Universidad de Alcala (UAH), Dpto Biomedicina y Biotecnología, 28805 Alcalá de Henares, Madrid, Spain.
| | - Alfredo De Bustos
- Universidad de Alcala (UAH), Dpto Biomedicina y Biotecnología, 28805 Alcalá de Henares, Madrid, Spain
| | - Rosa I Figueroa
- Instituto Español de Oceanografia (IEO), Subida a Radio Faro 50, 36390, Vigo, Spain.
- Aquatic Ecology, Biology Building, Lund University, 22362, Lund, Sweden.
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Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net. Sci Rep 2019; 9:839. [PMID: 30696854 PMCID: PMC6351617 DOI: 10.1038/s41598-018-37065-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 11/28/2018] [Indexed: 12/12/2022] Open
Abstract
Dinoflagellates are some of the most common eukaryotic cells in the ocean, but have very unusual nuclei. Many exhibit a form of closed mitosis (dinomitosis) wherein the nuclear envelope (NE) invaginates to form one or more trans-nuclear tunnels. Rather than contact spindles directly, the chromatids then bind to membrane-based kinetochores on the NE. To better understand these unique mitotic features, we reconstructed the nuclear architecture of Polykrikos kofoidii in 3D using focused ion beam scanning electron microscopy (FIB-SEM) in conjunction with high-pressure freezing, freeze-substitution, TEM, and confocal microscopy. We found that P. kofoidii possessed six nuclear tunnels, which were continuous with a reticulating network of membranes that has thus far gone unnoticed. These membranous extensions interconnect the six tunnels while ramifying throughout the nucleus to form a “nuclear net.” To our knowledge, the nuclear net is the most elaborate endomembrane structure described within a nucleus. Our findings demonstrate the utility of tomographic approaches for detecting 3D membrane networks and show that nuclear complexity has been underestimated in Polykrikos kofoidii and, potentially, in other dinoflagellates.
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Figueroa RI, de Bustos A, Cuadrado Á. A novel FISH technique for labeling the chromosomes of dinoflagellates in suspension. PLoS One 2018; 13:e0204382. [PMID: 30356238 PMCID: PMC6200182 DOI: 10.1371/journal.pone.0204382] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/11/2018] [Indexed: 11/19/2022] Open
Abstract
Dinoflagellates possess some of the largest known genomes. However, the study of their chromosomes is complicated by their similar size and their inability to be distinguished by traditional banding techniques. Dinoflagellate chromosomes lack nucleosomes and are present in a liquid crystalline state. In addition, approaches such as fluorescent in situ hybridization (FISH) are problematic because chromosomes are difficult to isolate from the nuclear membrane, which in dinoflagellates remains intact, also during mitosis. Here we describe a novel, reliable and effective technique to study dinoflagellate chromosomes by physical mapping of repetitive DNA sequences in chromosomes in suspension (FISH-IS), rather than on a microscope slide. A suspension of non-fixed chromosomes was achieved by lysing the cells and destabilizing the nuclear envelope. This treatment resulted in the release of the permanently condensed chromosomes in a high-quality chromosomal suspension. Nevertheless, slide preparations of the chromosomes were not suitable for conventional FISH because the nuclear integrity and chromosomal morphology was destroyed. Our newly developed, simple and efficient FISH-IS technique employs fluorescently labeled, synthetic short sequence repeats that are hybridized with suspended, acetic-acid-pretreated chromosomes for 1 h at room temperature. The method can be successfully used to discriminate single chromosomes or specific chromosomal regions, depending on the specificity of the repeat sequences used as probes. The combination of FISH-IS and flow sorting will improve genomic studies of dinoflagellates, overcoming the difficulties posed by their huge genomes, including long stretches of non-coding sequences in multiple copies and the presence of high-copy-number tandem gene arrays.
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Affiliation(s)
- Rosa I Figueroa
- Instituto Español de Oceanografia (IEO), Subida a Radio Faro 50, Vigo, Spain
| | - Alfredo de Bustos
- Universidad de Alcala (UAH), Dpto Biomedicina y Biotecnología, Alcalá de Henares, Madrid, Spain
| | - Ángeles Cuadrado
- Universidad de Alcala (UAH), Dpto Biomedicina y Biotecnología, Alcalá de Henares, Madrid, Spain
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13
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Golovynska I, Kalmukova O, Svitina HM, Kyryk VM, Shablii VA, Senchylo NV, Ostrovska GV, Dzerzhinskyi M, Stepanov YV, Golovynskyi S, Ohulchanskyy TY, Liu L, Garmanchuk LV, Qu J. Morpho-Functional Characteristics of Bone Marrow Multipotent Mesenchymal Stromal Cells after Activation or Inhibition of Epidermal Growth Factor and Toll-Like Receptors or Treatment with DNA Intercalator Cisplatin. Cytometry A 2018; 95:24-33. [PMID: 30240134 DOI: 10.1002/cyto.a.23593] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 07/25/2018] [Accepted: 07/30/2018] [Indexed: 12/11/2022]
Abstract
This study is aimed to reveal morphological and functional changes in multipotent mesenchymal stromal cells (MSCs) isolated from the rat bone marrow after: (i) activation of Toll-like receptors (TLRs) with teichoic acid (TA), (ii) impact on epidermal growth factor (EGF) receptors with activator EGF or inhibitor Herceptin, and (iii) treatment with DNA intercalator Cisplatin. According to our results, TA and EGF cause an increase in the synthesis of glycosaminoglycans, c-Myc content, and protein in the MSC cytoplasm. It was observed that the cell population in G0 phase decreased and the cell population in G1 phase increased, when compared with control. At the same time, the cell population with a higher nuclear-cytoplasmic ratio (NCR) in S and G2 phases also increased. This indicates the manifestation of the MSC mesenchymal phenotype, exhibiting indirect metabolic signs of the regenerative potential increase. In other experiments, Herceptin was shown to suppress only the stemness signs of MSCs, while Cisplatin seriously affected cell viability in general, reducing synthetic and proliferative activities and causing cell morphology disturbances. © 2018 International Society for Advancement of Cytometry.
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Affiliation(s)
- Iuliia Golovynska
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
| | - Olesia Kalmukova
- ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine.,State Institute of Genetic and Regenerative Medicine, National Academy of Medical Sciences of Ukraine, 04114, Kyiv, Ukraine
| | - Hanna M Svitina
- Pharmacen, Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Vitaliy M Kyryk
- State Institute of Genetic and Regenerative Medicine, National Academy of Medical Sciences of Ukraine, 04114, Kyiv, Ukraine
| | | | - Nataliya V Senchylo
- ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - Galyna V Ostrovska
- ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - Mykola Dzerzhinskyi
- ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - Yurii V Stepanov
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
| | - Sergii Golovynskyi
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
| | - Tymish Y Ohulchanskyy
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
| | - Liwei Liu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
| | - Liudmila V Garmanchuk
- ESC Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - Junle Qu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, People's Republic of China
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14
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Figueroa RI, Estrada M, Garcés E. Life histories of microalgal species causing harmful blooms: Haploids, diploids and the relevance of benthic stages. HARMFUL ALGAE 2018; 73:44-57. [PMID: 29602506 DOI: 10.1016/j.hal.2018.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 05/25/2023]
Abstract
In coastal and offshore waters, Harmful Algal Blooms (HABs) currently threaten the well-being of coastal countries. These events, which can be localized or involve wide-ranging areas, pose risks to human health, marine ecosystems, and economic resources, such as tourism, fisheries, and aquaculture. Dynamics of HABs vary from one site to another, depending on the hydrographic and ecological conditions. The challenge in investigating HABs is that they are caused by organisms from multiple algal classes, each with its own unique features, including different life histories. The complete algal life cycle has been determined in <1% of the described species, although elucidation of the life cycles of bloom-forming species is essential in developing preventative measures. The knowledge obtained thus far has confirmed the complexity of the algal life cycle, which is composed of discrete life stages whose morphology, ecological niche (plankton/benthos), function, and lifespan vary. The factors that trigger transitions between the different stages in nature are mostly unknown, but it is clear that an understanding of this process provides the key to effectively forecasting bloom recurrence, maintenance, and decline. Planktonic stages constitute an ephemeral phase of the life cycle of most species whereas resistant, benthic stages enable a species to withstand adverse conditions for prolonged periods, thus providing dormant reservoirs for eventual blooms and facilitating organismal dispersal. Here we review current knowledge of the life cycle strategies of major groups of HAB producers in marine and brackish waters. Rather than providing a comprehensive discussion, the objective was to highlight several of the research milestones that have changed our understanding of the plasticity and frequency of the different life cycle stages as well as the transitions between them. We also discuss the relevance of benthic and planktonic forms and their implications for HAB dynamics.
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Affiliation(s)
- Rosa Isabel Figueroa
- Instituto Español de Oceanografía (IEO), C.O. Vigo, 36280 Vigo, Spain; Aquatic Ecology Division, Department of Biology, Lund University, S-22362 Lund, Sweden.
| | - Marta Estrada
- Departament de Biología Marina i Oceanografía, Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Pg. Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain
| | - Esther Garcés
- Departament de Biología Marina i Oceanografía, Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Pg. Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain
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15
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Fujise L, Nitschke MR, Frommlet JC, Serôdio J, Woodcock S, Ralph PJ, Suggett DJ. Cell Cycle Dynamics of Cultured Coral Endosymbiotic Microalgae (
Symbiodinium
) Across Different Types (Species) Under Alternate Light and Temperature Conditions. J Eukaryot Microbiol 2018; 65:505-517. [DOI: 10.1111/jeu.12497] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/17/2017] [Accepted: 12/19/2017] [Indexed: 01/02/2023]
Affiliation(s)
- Lisa Fujise
- Climate Change Cluster University of Technology Sydney Broadway New South Wales 2007 Australia
| | - Matthew R. Nitschke
- Climate Change Cluster University of Technology Sydney Broadway New South Wales 2007 Australia
- Department of Biology and Center for Environmental and Marine Studies University of Aveiro Aveiro 3810‐193 Portugal
| | - Jörg C. Frommlet
- Department of Biology and Center for Environmental and Marine Studies University of Aveiro Aveiro 3810‐193 Portugal
| | - João Serôdio
- Department of Biology and Center for Environmental and Marine Studies University of Aveiro Aveiro 3810‐193 Portugal
| | - Stephen Woodcock
- Climate Change Cluster University of Technology Sydney Broadway New South Wales 2007 Australia
| | - Peter J. Ralph
- Climate Change Cluster University of Technology Sydney Broadway New South Wales 2007 Australia
| | - David J. Suggett
- Climate Change Cluster University of Technology Sydney Broadway New South Wales 2007 Australia
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16
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Lau WLS, Law IK, Liow GR, Hii KS, Usup G, Lim PT, Leaw CP. Life-history stages of natural bloom populations and the bloom dynamics of a tropical Asian ribotype of Alexandrium minutum. HARMFUL ALGAE 2017; 70:52-63. [PMID: 29169568 DOI: 10.1016/j.hal.2017.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/30/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
In 2015, a remarkably high density bloom of Alexandrium minutum occurred in Sungai Geting, a semi-enclosed lagoon situated in the northeast of Peninsular Malaysia, causing severe discoloration and contaminated the benthic clams (Polymesoda). Plankton and water samples were collected to investigate the mechanisms of bloom development of this toxic species. Analysis of bloom samples using flow cytometry indicated that the bloom was initiated by the process of active excystment, as planomycetes (>4C cells) were observed in the early stage of the bloom. Increase in planozygotes (2C cells) was evident during the middle stage of the bloom, coinciding with an abrupt decrease in salinity and increase of temperature. The bloom was sustained through the combination of binary division of vegetative cells, division of planozygotes, and cyst germination through continuous excystment. Nutrient depletion followed by precipitation subsequently caused the bloom to terminate. This study provides the first continuous record of in situ life-cycle stages of a natural bloom population of A. minutum through a complete bloom cycle. The event has provided a fundamental understanding of the pelagic life-cycle stages of this tropical dinoflagellate, and demonstrated a unique bloom development characteristic shared among toxic Alexandrium species in coastal embayments.
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Affiliation(s)
- Winnie Lik Sing Lau
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Ing Kuo Law
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Guat Ru Liow
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Kieng Soon Hii
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Gires Usup
- Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia
| | - Po Teen Lim
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
| | - Chui Pin Leaw
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
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17
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Rane AS, Rutkauskaite J, deMello A, Stavrakis S. High-Throughput Multi-parametric Imaging Flow Cytometry. Chem 2017. [DOI: 10.1016/j.chempr.2017.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Salgado P, Figueroa RI, Ramilo I, Bravo I. The life history of the toxic marine dinoflagellate Protoceratium reticulatum (Gonyaulacales) in culture. HARMFUL ALGAE 2017; 68:67-81. [PMID: 28962991 DOI: 10.1016/j.hal.2017.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/20/2017] [Accepted: 07/20/2017] [Indexed: 06/07/2023]
Abstract
Asexual and sexual life cycle events were studied in cultures of the toxic marine dinoflagellate Protoceratium reticulatum. Asexual division by desmoschisis was characterized morphologically and changes in DNA content were analyzed by flow cytometry. The results indicated that haploid cells with a C DNA content occurred only during the light period whereas a shift from a C to a 2C DNA content (indicative of S phase) took place only during darkness. The sexual life cycle was documented by examining the mating type as well as the morphology of the sexual stages and nuclei. Gamete fusion resulted in a planozygote with two longitudinal flagella, but longitudinally biflagellated cells arising from planozygote division were also observed, so one of the daughter cells retained two longitudinal flagella while the other daughter cell lacked them. Presumed planozygotes (identified by their longitudinally biflagellated form) followed two life-cycle routes: division and encystment (resting cyst formation). Both the division of longitudinally biflagellated cells and resting cyst formation are morphologically described herein. Resting cyst formation through sexual reproduction was observed in 6.1% of crosses and followed a complex heterothallic pattern. Clonal strains underwent sexuality (homothallism for planozygote formation and division) but without the production of resting cysts. Ornamental processes of resting cysts formed from the cyst wall under an outer balloon-shaped membrane and were fully developed in <1h. Obligatory dormancy period was of ∼4 months. Excystment resulted in a large, rounded, pigmented, longitudinally biflagellated but motionless, thecate germling that divided by desmoschisis. Like the planozygote, the first division of the germling yielded one longitudinally biflagellated daughter cell and another without longitudinal flagella. The longitudinal biflagellation state of both sexual stages and of the first division products of these cells is discussed.
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Affiliation(s)
- Pablo Salgado
- Instituto de Fomento Pesquero (IFOP), Enrique Abello 0552, Casilla 101, Punta Arenas, Chile; Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390, Vigo, Spain.
| | - Rosa I Figueroa
- Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390, Vigo, Spain.
| | - Isabel Ramilo
- Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390, Vigo, Spain.
| | - Isabel Bravo
- Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390, Vigo, Spain.
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19
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Dashkova V, Malashenkov D, Poulton N, Vorobjev I, Barteneva NS. Imaging flow cytometry for phytoplankton analysis. Methods 2017; 112:188-200. [DOI: 10.1016/j.ymeth.2016.05.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/13/2016] [Indexed: 10/21/2022] Open
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20
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Hémonnot CYJ, Ranke C, Saldanha O, Graceffa R, Hagemann J, Köster S. Following DNA Compaction During the Cell Cycle by X-ray Nanodiffraction. ACS NANO 2016; 10:10661-10670. [PMID: 28024349 DOI: 10.1021/acsnano.6b05034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
X-ray imaging of intact biological cells is emerging as a complementary method to visible light or electron microscopy. Owing to the high penetration depth and small wavelength of X-rays, it is possible to resolve subcellular structures at a resolution of a few nanometers. Here, we apply scanning X-ray nanodiffraction in combination with time-lapse bright-field microscopy to nuclei of 3T3 fibroblasts and thus relate the observed structures to specific phases in the cell division cycle. We scan the sample at a step size of 250 nm and analyze the individual diffraction patterns according to a generalized Porod's law. Thus, we obtain information on the aggregation state of the nuclear DNA at a real space resolution on the order of the step size and in parallel structural information on the order of few nanometers. We are able to distinguish nucleoli, heterochromatin, and euchromatin in the nuclei and follow the compaction and decompaction during the cell division cycle.
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Affiliation(s)
- Clément Y J Hémonnot
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
| | - Christiane Ranke
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
| | - Oliva Saldanha
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
| | - Rita Graceffa
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
| | - Johannes Hagemann
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
| | - Sarah Köster
- Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, Göttingen 37077, Germany
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21
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Figueroa RI, Dapena C, Bravo I, Cuadrado A. The Hidden Sexuality of Alexandrium Minutum: An Example of Overlooked Sex in Dinoflagellates. PLoS One 2015; 10:e0142667. [PMID: 26599692 PMCID: PMC4979955 DOI: 10.1371/journal.pone.0142667] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/26/2015] [Indexed: 12/02/2022] Open
Abstract
Dinoflagellates are haploid eukaryotic microalgae in which rapid proliferation causes dense blooms, with harmful health and economic effects to humans. The proliferation mode is mainly asexual, as the sexual cycle is believed to be rare and restricted to stressful environmental conditions. However, sexuality is key to explaining the recurrence of many dinoflagellate blooms because in many species the fate of the planktonic zygotes (planozygotes) is the formation of resistant cysts in the seabed (encystment). Nevertheless, recent research has shown that individually isolated planozygotes in the lab can enter other routes besides encystment, a behavior of which the relevance has not been explored at the population level. In this study, using imaging flow cytometry, cell sorting, and Fluorescence In Situ Hybridization (FISH), we followed DNA content and nuclear changes in a population of the toxic dinoflagellate Alexandrium minutum that was induced to encystment. Our results first show that planozygotes behave like a population with an “encystment-independent” division cycle, which is light-controlled and follows the same Light:Dark (L:D) pattern as the cycle governing the haploid mitosis. Resting cyst formation was the fate of just a small fraction of the planozygotes formed and was restricted to a period of strongly limited nutrient conditions. The diploid-haploid turnover between L:D cycles was consistent with two-step meiosis. However, the diel and morphological division pattern of the planozygote division also suggests mitosis, which would imply that this species is not haplontic, as previously considered, but biphasic, because individuals could undergo mitotic divisions in both the sexual (diploid) and the asexual (haploid) phases. We also report incomplete genome duplication processes. Our work calls for a reconsideration of the dogma of rare sex in dinoflagellates.
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Affiliation(s)
- Rosa I. Figueroa
- Aquatic Ecology, Biology Building, Lund University, 22362 Lund, Sweden
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain
- * E-mail: ;
| | - Carlos Dapena
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain
| | - Isabel Bravo
- Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, 36390 Vigo, Spain
| | - Angeles Cuadrado
- Universidad de Alcalá (UAH), Dpto de Biomedicina y Biotecnologia, 28801 Alcalá de Henares, Spain
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22
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Stüken A, Riobó P, Franco J, Jakobsen KS, Guillou L, Figueroa RI. Paralytic shellfish toxin content is related to genomic sxtA4 copy number in Alexandrium minutum strains. Front Microbiol 2015; 6:404. [PMID: 25983733 PMCID: PMC4416454 DOI: 10.3389/fmicb.2015.00404] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 04/17/2015] [Indexed: 11/27/2022] Open
Abstract
Dinoflagellates are microscopic aquatic eukaryotes with huge genomes and an unusual cell regulation. For example, most genes are present in numerous copies and all copies seem to be obligatorily transcribed. The consequence of the gene copy number (CPN) for final protein synthesis is, however, not clear. One such gene is sxtA, the starting gene of paralytic shellfish toxin (PST) synthesis. PSTs are small neurotoxic compounds that can accumulate in the food chain and cause serious poisoning incidences when ingested. They are produced by dinoflagellates of the genera Alexandrium, Gymnodium, and Pyrodinium. Here we investigated if the genomic CPN of sxtA4 is related to PST content in Alexandrium minutum cells. SxtA4 is the 4th domain of the sxtA gene and its presence is essential for PST synthesis in dinoflagellates. We used PST and genome size measurements as well as quantitative PCR to analyze sxtA4 CPN and toxin content in 15 A. minutum strains. Our results show a strong positive correlation between the sxtA4 CPN and the total amount of PST produced in actively growing A. minutum cells. This correlation was independent of the toxin profile produced, as long as the strain contained the genomic domains sxtA1 and sxtA4.
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Affiliation(s)
- Anke Stüken
- Department of Biosciences, University of Oslo Oslo, Norway
| | - Pilar Riobó
- U.A. Microalgas Nocivas (Consejo Superior de Investigaciones Científicas - Instituto Español de Oceanografía), Instituto de Investigaciones Marinas Vigo, Spain
| | - José Franco
- U.A. Microalgas Nocivas (Consejo Superior de Investigaciones Científicas - Instituto Español de Oceanografía), Instituto de Investigaciones Marinas Vigo, Spain
| | - Kjetill S Jakobsen
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo Oslo, Norway
| | - Laure Guillou
- Laboratoire Adaptation et Diversité en Milieu Marin, CNRS, UMR 7144 Roscoff, France ; Sorbonne Universités - Université Pierre et Marie Curie, UMR 7144 Roscoff, France
| | - Rosa I Figueroa
- Aquatic Ecology, Lund University Lund, Sweden ; U.A. Microalgas Nocivas (Consejo Superior de Investigaciones Científicas - Instituto Español de Oceanografía), Instituto Español de Oceanografía Vigo, Spain
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