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Ritter C, Gonçalves V, Pla-Rabes S, de Boer EJ, Bao R, Sáez A, Hernández A, Sixto M, Richter N, Benavente M, Prego R, Giralt S, Raposeiro PM. The vanishing and the establishment of a new ecosystem on an oceanic island - Anthropogenic impacts with no return ticket. Sci Total Environ 2022; 830:154828. [PMID: 35346708 DOI: 10.1016/j.scitotenv.2022.154828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/22/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
A multiproxy approach was applied to a sediment core retrieved from the deep crater Lake Funda, located in the middle of the North Atlantic Ocean on Flores Island, Azores archipelago (Portugal). The purpose of this study was to determine how this ecosystem responded to natural and anthropogenic forces over the last millennium. We distinguished three main phases in lake evolution using multiproxy reconstructions and documentary sources. (A) Climate and lake catchment processes, as well as internal ones, were the main drivers of ecosystem variability before 1335 CE, when human disturbances were absent in the Lake Funda catchment. (B) The second phase is marked by unprecedented changes in all studied proxies between 1335 and 1560 CE, including abrupt changes in the composition and diversity of diatom and chironomid assemblages. Synergistic effects from high climate variability and the onset of human disturbances in the catchment (e.g., introduction of livestock) during the Medieval Climate Anomaly-Little Ice Age transition, led to an increase in lake trophic state from mesotrophic to eutrophic conditions. (C) In the last phase (1560 CE to the present), the eutrophic conditions in Lake Funda were maintained through a positive feedback loop between lake productivity and in-lake phosphorous recycling. Variability within the lake ecosystem was mainly associated with climate variability and internal lake dynamics (e.g., phosphorus remobilization). Our results show that a paleoecological approach is crucial to understanding lake ecological states in the present-day in order to develop locally adapted management and restoration strategies. A long-term perspective enables us to understand the harmful consequences of ongoing climate change and human disturbances on lake ecosystems.
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Affiliation(s)
- Catarina Ritter
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal.
| | - Vítor Gonçalves
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal; Faculdade de Ciências e Tecnologia, Universidade dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal
| | - Sergi Pla-Rabes
- CREAF, Campus de Bellaterra (UAB), Edifici C, 08193 Cerdayola del Valles, Spain; Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, Corner Ditton and University Avenue, Auckland Park, Johannesburg, South Africa
| | - Erik J de Boer
- UB-Geomodels Research Institute. Department de Dinàmica de la Terra i de l'Oceà, Facultat de Ciències de la Terra, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
| | - Roberto Bao
- Universidade da Coruña, GRICA Group, Centro de Investigacións Científicas Avanzadas (CICA), Rúa as Carballeiras, 15071, A Coruña, Spain
| | - Alberto Sáez
- UB-Geomodels Research Institute. Department de Dinàmica de la Terra i de l'Oceà, Facultat de Ciències de la Terra, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain
| | - Armand Hernández
- Universidade da Coruña, GRICA Group, Centro de Investigacións Científicas Avanzadas (CICA), Rúa as Carballeiras, 15071, A Coruña, Spain
| | - Marta Sixto
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CISC), Subida a Radio Faro 50-52, 36390 Vigo, Spain; Campus do Mar, Facultad de Ciencias del Mar, Universidad de Vigo, 36311 Vigo, Spain
| | - Nora Richter
- NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, the Netherlands; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
| | - Mario Benavente
- Geosciences Barcelona (Geo3BCN-CSIC), Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain
| | - Ricardo Prego
- Department of Oceanography, Marine Research Institute (CSIC), Eduardo Cabello, 6. 36208 Vigo, Spain
| | - Santiago Giralt
- Geosciences Barcelona (Geo3BCN-CSIC), Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain
| | - Pedro M Raposeiro
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal; Faculdade de Ciências e Tecnologia, Universidade dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal
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Cuadrado Á, Figueroa RI, Sixto M, Bravo I, De Bustos A. First record of the spatial organization of the nucleosome-less chromatin of dinoflagellates: The nonrandom distribution of microsatellites and bipolar arrangement of telomeres in the nucleus of Gambierdiscus australes (Dinophyceae). J Phycol 2022; 58:297-307. [PMID: 35038777 DOI: 10.1111/jpy.13236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Dinoflagellates are a group of protists whose exceptionally large genome is organized in permanently condensed nucleosome-less chromosomes. In this study, we examined the potential role of repetitive DNAs in both the structure of dinoflagellate chromosomes and the architecture of the dinoflagellate nucleus. Non-denaturing fluorescent in situ hybridization (ND-FSH) was used to determine the abundance and physical distribution of telomeric DNA and 16 microsatellites (1- to 4-bp repeats) in the nucleus of Gambierdiscus australes. The results showed an increased relative abundance of the different microsatellite motifs with increasing GC content. Two ND-FISH probes, (A)20 and (AAT)5 , did not yield signals whereas the remainder revealed a dispersed but nonrandom distribution of the microsatellites, mostly in clusters. The bean-shaped interphase nucleus of G. australes contained a region with a high density of trinucleotides. This nuclear compartment was located between the nucleolar organizer region (NOR), located on the concave side of the nucleus, and the convex side. Telomeric DNA was grouped in multiple foci and distributed in two polarized compartments: one associated with the NOR and the other peripherally located along the convex side of the nucleus. Changes in the position of the telomeres during cell division evidenced their dynamic distribution and thus that of the chromosomes during dinomitosis. These insights into the spatial organization of microsatellites and telomeres and thus into the nuclear architecture of G. australes will open up new lines of research into the structure and function of the nucleosome-less chromatin of dinoflagellates.
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Affiliation(s)
- Ángeles Cuadrado
- Departamento de Biomedicina y Biotecnología, Universidad de Alcalá (UAH), Alcalá de Henares, Madrid, 28805, Spain
| | - Rosa I Figueroa
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50, Vigo, 36390, Spain
| | - Marta Sixto
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50, Vigo, 36390, Spain
- Campus do Mar, Facultad de Ciencias del Mar, Universidad de Vigo, Vigo, 36311, Spain
| | - Isabel Bravo
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50, Vigo, 36390, Spain
| | - Alfredo De Bustos
- Departamento de Biomedicina y Biotecnología, Universidad de Alcalá (UAH), Alcalá de Henares, Madrid, 28805, Spain
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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