RESUMO
Mazzaella, a genus with no genomic resources available, has extensive distribution in the cold waters of the Pacific, where they represent ecologically and economically important species. In this study, we aimed to sequence, assemble, and annotate the complete mitochondrial and chloroplast genomes from two Mazzaella spp. and characterize the intraspecific variation among them. We report for the first time seven whole organellar genomes (mitochondria: OR915856, OR947465, OR947466, OR947467, OR947468, OR947469, OR947470; chloroplast: OR881974, OR909680, OR909681, OR909682, OR909683, OR909684, OR909685) obtained through high-throughput sequencing for six M. laminarioides sampled from three Chilean regions and one M. membranacea. Sequenced Mazzaella mitogenomes have identical gene number, gene order, and genome structure. The same results were observed for assembled plastomes. A total of 52 genes were identified in mitogenomes, and a total of 235 genes were identified in plastomes. Although the M. membranacea plastome included a full-length pbsA gene, in all M. laminarioides samples, the pbsA gene was split in three open reading frames (ORFs). Within M. laminarioides, we observed important plastome lineage-specific variations, such as the pseudogenization of the two hypothetical protein-coding genes, ycf23 and ycf45. Nonsense mutations in the ycf23 and ycf45 genes were only detected in the northern lineage. These results are consistent with phylogenetic reconstructions and divergence time estimation using concatenated coding sequences that not only support the monophyly of M. laminarioides but also underscore that the three M. laminarioides lineages are in an advanced stage of divergence. These new results open the question of the existence of still undisclosed species in M. laminarioides.
Assuntos
Genoma de Cloroplastos , Genoma Mitocondrial , Rodófitas , Rodófitas/genética , Rodófitas/classificação , Filogenia , ChileRESUMO
A reclassification of Cyanidium chilense under the new genus Cavernulicola was recently proposed together with a new family (Cavernulicolaceae) and a new order (Cavernulicolales). Unfortunately, due to an error in the required citation of the basionym, the name "Cavernulicola chilensis" was invalid and cannot be accepted as the generitype of Cavernulicola. This means that Cavernulicola, Cavernulicolaceae, and Cavernulicolales are likewise invalid names under the provisions of the International Code of Nomenclature for algae, fungi, and plants (ICN, Shenzhen Code). In this contribution, each of these names is validated.
Assuntos
Rodófitas , Terminologia como Assunto , Rodófitas/classificação , Rodófitas/genéticaRESUMO
Changes in the sea level during the Holocene are regarded as one of the most prevalent drivers of the diversity and distribution of macroalgae in Brazil, influenced by the emergence of the Vitória-Trindade seamount chain (VTC). Gracilariopsis tenuifrons has a wide geographic distribution along the Brazilian coast, from Maranhão state (2°48'64.3" S) to Santa Catarina state (27.5°73'83" S). The knowledge of historical processes affecting diversity may allow the development of conservation strategies in environments against anthropogenic influence. Therefore, knowledge about phylogeography and populational genetic diversity in G. tenuifrons is necessary. Six populations were sampled along the northeastern tropical (Maranhão-MA, Rio Grande do Norte-RN, Alagoas-AL, and Bahia-BA States) and southeastern subtropical (São Paulo "Ubatuba"-SP1 and São Paulo "Itanhaém"-SP2 States) regions along the Brazilian coast. The genetic diversity and structure of G. tenuifrons were inferred using mitochondrial (COI-5P and cox2-3 concatenated) DNA markers. Gracilariopsis tenuifrons populations showed an evident separation between the northeast (from 2°48'64.3" S to 14°18'23" S; 17 haplotypes) and the southeast (from 23°50'14.9" S to 24°20'04.7" S; 10 haplotypes) regions by two mutational steps between them. The main biogeographical barrier to gene flow is located nearby the VTC. The southeast region (São Paulo State) is separated by two subphylogroups (SP1, three haplotypes and SP2, six haplotypes), and Santos Bay (estuary) has been considered a biogeographical barrier between them. The presence of genetic structure and putative barriers to gene flow are in concordance with previous studies reporting biogeographic breaks in the southwest Atlantic Ocean, including the genetic isolation between northeast and southeast regions for red and brown algae in the vicinity of the VTC.
Assuntos
Variação Genética , Rodófitas , Filogeografia , Brasil , Rodófitas/genética , Oceano Atlântico , Haplótipos , DNA Mitocondrial/genética , FilogeniaRESUMO
The coastline is a heterogeneous and highly dynamic environment influenced by abiotic and biotic variables affecting the temporal stability of genetic diversity and structure of marine organisms. The aim of this study was to determine how much the genetic structure of four species of marine Bangiales vary in time and space. Partial sequences of the cytochrome oxidase I (COI) gene obtained from two Pyropia (Py. sp. CHJ and Py. orbicularis) and two Porphyra (P. mumfordii and P. sp. FIH) species were used to compare the effect of the 40° S/41° S biogeographic break (spatial-regional scale) and the one of the Valdivia River discharges (spatial-local scale) and determine their temporal stability. Four seasonal samplings were taken during 1 year at five sites, one site located in Melinka (Magallanes province) and four sites along the coast of Valdivia (Intermediate area), on both sides of the river mouth. Results showed a strong genetic spatial structure at regional scale (ΦST > 0.4) in Py. sp. CHJ, Py. orbicularis, and P. mumfordii, congruent with the 41° S/42° S biogeographic break. A potential barrier to gene flow, related to the Valdivia River discharge, was detected only in P. mumfordii. In P. sp. FIH, spatial genetic structure was not detected at any scale. The genetic structure of all four species is stable throughout the year. The potential effect of main currents and river discharge in limiting the transport of Bangiales spores are discussed. We propose that both a restricted propagule dispersal and the formation potential for persistent banks of microscopic stages could lead to a temporally stable spatial partitioning of genetic variation in bladed Bangiales.
Assuntos
Porphyra , Rodófitas , Filogenia , Chile , Rodófitas/genética , Organismos Aquáticos , Variação GenéticaRESUMO
Gracilariales is a clade of florideophycean red macroalgae known for being the main source of agar. We present a de novo genome assembly and annotation of Gracilaria domingensis, an agarophyte alga with flattened thallus widely distributed along Central and South American Atlantic intertidal zones. In addition to structural analysis, an organizational comparison was done with other Rhodophyta genomes. The nuclear genome has 78 Mbp, with 11,437 predicted coding genes, 4,075 of which did not have hits in sequence databases. We also predicted 1,567 noncoding RNAs, distributed in 14 classes. The plastid and mitochondrion genome structures were also obtained. Genes related to agar synthesis were identified. Genes for type II galactose sulfurylases could not be found. Genes related to ascorbate synthesis were found. These results suggest an intricate connection of cell wall polysaccharide synthesis and the redox systems through the use of L-galactose in Rhodophyta. The genome of G. domingensis should be valuable to phycological and aquacultural research, as it is the first tropical and Western Atlantic red macroalgal genome to be sequenced.
Assuntos
Genoma Mitocondrial , Gracilaria , Rodófitas , Ágar/metabolismo , Galactose/metabolismo , Gracilaria/genética , Rodófitas/genética , Rodófitas/metabolismoRESUMO
The Peyssonneliaceae represents the only family in the order Peyssonneliales, a clade of red encrusting algae distributed worldwide, including 136 species in eleven currently accepted genera. Delineation of genera in the Peyssonneliaceae has mostly been based on vegetative characteristics. Previous molecular phylogenies have shown that some traditionally circumscribed genera are not monophyletic and relationships among them are uncertain. We contribute to the knowledge of the evolutionary history of this clade, presenting a robust rbcL phylogeny that provides new insights on the origin and diversification of the Peyssonneliales. Based on a broad dataset and morphological analyses, we propose a revised taxonomic scheme for the Peyssonneliales resolved as monophyletic with well-supported main lineages. Our results show that Peyssonnelia is polyphyletic, and, therefore, we propose three new genera, Agissea, Olokunia, and Rhodowynnea to accommodate species currently assigned to Peyssonnelia, but distantly related to the clade with the type species of the genus. Additionally, barcoding techniques and analyzed criteria for specific delimitation supported the establishment of one new genus, Brasilophycus, and seven new species, from northeastern Brazil: Agissea amadoi, A. densissima, A. taberniforma, A. villatlantica, A. yemonjasagbae, Brasilophycus similis, and B. roseomarginatus. Our integrative taxonomic approach reveals underestimated diversity of Brazilian Peyssonneliales. Investment in broader sampling along the Brazilian coast and other tropical areas may reveal that its marine biodiversity can be expanded, enlightening our knowledge about this ecologically important group of red algae.
Assuntos
Rodófitas , Biodiversidade , Evolução Biológica , Brasil , Filogenia , Rodófitas/genéticaRESUMO
A partial rbcL sequence of the lectotype specimen of Corallina berteroi shows that it is the earliest available name for C. ferreyrae. Multilocus species delimitation analyses (ABGD, SPN, GMYC, bPTP, and BPP) using independent or concatenated COI, psbA, and rbcL sequences recognized one, two, or three species in this complex, but only with weak support for each species hypothesis. Conservatively, we recognize a single worldwide species in this complex of what appears to be multiple, evolving populations. Included in this species, besides C. ferreyrae, are C. caespitosa, the morphologically distinct C. melobesioides, and, based on a partial rbcL sequence of the holotype specimen, C. pinnatifolia. Corallina berteroi, not C. officinalis, is the cosmopolitan temperate species found thus far in the NE Atlantic, Mediterranean Sea, warm temperate NW Atlantic and NE Pacific, cold temperate SW Atlantic (Falkland Islands), cold and warm temperate SE Pacific, NW Pacific and southern Australia. Also proposed is C. yendoi sp. nov. from Hokkaido, Japan, which was recognized as distinct by 10 of the 13 species discrimination analyses, including the multilocus BPP.
Assuntos
Rodófitas , Japão , Mar Mediterrâneo , Filogenia , Rodófitas/genética , Análise de Sequência de DNARESUMO
Diatoms are unicellular organisms containing red algal-derived plastids that probably originated as result of serial endosymbioses between an ancestral heterotrophic organism and a red alga or cryptophyta algae from which has only the chloroplast left. Diatom mitochondria are thus believed to derive from the exosymbiont. Unlike animals and fungi, diatoms seem to contain ancestral respiratory chains. In support of this, genes encoding gamma type carbonic anhydrases (CAs) whose products were shown to be intrinsic complex I subunits in plants, Euglena and Acanthamoeba were found in diatoms, a representative of Stramenopiles. In this work, we experimentally show that mitochondrial complex I in diatoms is a large complex containing gamma type CA subunits, supporting an ancestral origin. By using a bioinformatic approach, a complex I integrated CA domain with heterotrimeric subunit composition is proposed.
Assuntos
Anidrases Carbônicas/metabolismo , Diatomáceas/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Mitocôndrias/metabolismo , Sequência de Aminoácidos , Anidrases Carbônicas/genética , Cloroplastos/genética , Cloroplastos/metabolismo , Diatomáceas/genética , Complexo I de Transporte de Elétrons/genética , Evolução Molecular , Mitocôndrias/genética , Filogenia , RNA-Seq , Rodófitas/genética , Alinhamento de Sequência , Simbiose/genéticaRESUMO
The classification of Cystoclonium obtusangulum has been questioned since the species was first described by Hooker and Harvey as Gracilaria? obtusangula. The objective of this study was to provide the first comprehensive taxonomic analysis of Cystoclonium obtusangulum, based on DNA sequences coupled with morphological observations made on syntype specimens and new collections. Sequence divergences of rbcL, UPA, and COI-5P, and maximum-likelihood phylogenies for rbcL and 18S demonstrated that specimens identified as Cystoclonium obtusangulum represent a clade of two distinct species that are distantly related to the generitype Cystoclonium purpureum. A new genus, Meridionella gen. nov., is proposed for this clade. The two species placed in this new genus were morphologically indistinguishable cryptic species, but have disjunct distributions, with Meridionella obtusangula comb. nov. found from temperate to cold coasts of South America and the Falkland Islands and Meridionella antarctica sp. nov., occurring in Antarctic waters. Vegetative and reproductive characters of Meridionella gen. nov. are described, and implications of our results for the biogeography of the family Cystocloniaceae are discussed.
Assuntos
Rodófitas , Regiões Antárticas , Filogenia , RNA Ribossômico 16S , Rodófitas/genética , Análise de Sequência de DNA , América do SulRESUMO
A partial rbcL sequence from the type material of Spongites discoideus from southern Argentina showed that it was distinct from rbcL sequences of South African specimens to which that name had been applied based on morpho-anatomy. A partial rbcL sequence from an original syntype specimen, herein designated the lectotype, of Lithophyllum marlothii, type locality Camps Bay, Western Cape Province, South Africa, was identical to rbcL sequences of South African field-collected specimens assigned to S. discoideus. Based on phylogenetic analyses of rbcL and/or psbA sequences, both of these species belong in Pneophyllum and are transferred there as P. discoideum comb. nov. and P. marlothii comb. nov. The two species exhibit a distinct type of development where thick, secondary, monomerous disks are produced from thin, primary, dimerous crusts. Whether this type of development represents an example of convergent evolution or is characteristic of a clade of species within Pneophyllum remains to be resolved.
Assuntos
Rodófitas , Argentina , Filogenia , RNA Ribossômico 16S , Rodófitas/genética , Análise de Sequência de DNA , África do SulRESUMO
The filamentous red algal genus Gayliella, typified by G. flaccida, was segregated from Ceramium for a group of epiphytic species on the basis of morphological data and molecular phylogenetic analyses. However, while the genus was well investigated in some geographical areas, the treatment of the Brazilian taxa "Ceramium flaccidum" and "C. dawsonii" was incomplete and they were not transferred to Gayliella due to the problematic status of the specific epithets. Brazilian "C. flaccidum" did not fit within the circumscription of Gayliella flaccida; Brazilian "C. dawsonii" was positioned in three distinct lineages, none of which corresponded to known Gayliella species. Since the establishment of Gayliella, there has been no re-evaluation of Brazilian species, so this study revises the genus in Brazil using molecular and morphological data. Brazilian "C. flaccidum", "C. dawsonii", and other Brazilian collections were investigated by an integrative approach using phylogenetic analysis, genetic divergence, two species delimitation methods using three molecular markers (rbcL, cox1, and partial LSU), and comparative morphological and quantitative analyses. This molecular-assisted alpha taxonomy (MAAT) analysis placed Brazilian samples in five distinct well-supported lineages. For these, we propose a new combination, Gayliella dawsonii comb. nov. (lineage 2), based on analysis of type specimens and molecular data obtained from specimens collected near the type locality, and four new species: Gayliella ardissonei sp. nov. ("Ceramium flaccidum" from Brazil), G. iemanja sp. nov. ("C. dawsonii" lineage 3), G. tamoiensis sp. nov., and G. jolyana sp. nov. ("C. dawsonii" lineage 1).
Assuntos
Rodófitas , Brasil , Filogenia , Rodófitas/genéticaRESUMO
Gracilariaceae has a worldwide distribution including numerous economically important species. We applied high-throughput sequencing to obtain organellar genomes (mitochondria and chloroplast) from 10 species of Gracilariaceae and, combined with published genomes, to infer phylogenies and compare genome architecture among species representing main lineages. We obtained similar topologies between chloroplast and mitochondrial genomes phylogenies. However, the chloroplast phylogeny was better resolved with full support. In this phylogeny, Melanthalia intermedia is sister to a monophyletic clade including Gracilaria and Gracilariopsis, which were both resolved as monophyletic genera. Mitochondrial and chloroplast genomes were highly conserved in gene synteny, and variation mainly occurred in regions where insertions of plasmid-derived sequences (PDS) were found. In mitochondrial genomes, PDS insertions were observed in two regions where the transcription direction changes: between the genes cob and trnL, and trnA and trnN. In chloroplast genomes, PDS insertions were in different positions, but generally found between psdD and rrs genes. Gracilariaceae is a good model system to study the impact of PDS in genome evolution due to the frequent presence of these insertions in organellar genomes. Furthermore, the bacterial leuC/leuD operon was found in chloroplast genomes of Gracilaria tenuistipitata, G. chilensis, and M. intermedia, and in extrachromosomal plasmid of G. vermiculophylla. Phylogenetic trees show two different origins of leuC/leuD: genes found in chloroplast and plasmid were placed with proteobacteria, and genes encoded in the nucleus were close to Viridiplantae and cyanobacteria.
Assuntos
Evolução Molecular , Genoma de Cloroplastos/genética , Genoma Mitocondrial/genética , Rodófitas/genética , Filogenia , Análise de Sequência de DNARESUMO
Little is known about genome organization in members of the order Batrachospermales, and the infra-ordinal relationship remains unresolved. Plastid (cp) genomes of seven members of the freshwater red algal order Batrachospermales were sequenced, with the following aims: (i) to describe the characteristics of cp genomes and compare these with other red algal groups; (ii) to infer the phylogenetic relationships among these members to better understand the infra-ordinal classification. Cp genomes of Batrachospermales are large, with several cases of gene loss, they are gene-dense (high gene content for the genome size and short intergenic regions) and have highly conserved gene order. Phylogenetic analyses based on concatenated nucleotide genome data roughly supports the current taxonomic system for the order. Comparative analyses confirm data for members of the class Florideophyceae that cp genomes in Batrachospermales is highly conserved, with little variation in gene composition. However, relevant new features were revealed in our study: genome sizes in members of Batrachospermales are close to the lowest values reported for Florideophyceae; differences in cp genome size within the order are large in comparison with other orders (Ceramiales, Gelidiales, Gracilariales, Hildenbrandiales, and Nemaliales); and members of Batrachospermales have the lowest number of protein-coding genes among the Florideophyceae. In terms of gene loss, apcF, which encodes the allophycocyanin beta subunit, is absent in all sequenced taxa of Batrachospermales. We reinforce that the interordinal relationships between the freshwater orders Batrachospermales and Thoreales within the Nemaliophycidae is not well resolved due to limited taxon sampling.
Assuntos
Genoma de Cloroplastos , Genoma de Planta , Rodófitas/genética , Sequência de Bases , Filogenia , Alinhamento de Sequência , Sequenciamento Completo do GenomaRESUMO
Chimerism is produced by the somatic fusion of two or more genetically distinct conspecific individuals. In animals, the main cost of fusion is competition between genetically different cell lineages and the probability of original cell line replacement by more competitive invasive lines, which limits its natural frequency (3%-5%). In red and brown seaweeds, chimerism is widespread (27%-53%), seemingly without the negative outcomes described for animals. The rigidity of cell walls in macroalgae prevents cell motility and invasions. In addition, in moving waters, most somatic fusions involve the holdfast. Histological observations in laboratory-built bicolor macroalgal chimeras indicated that upright axes emerge from the base of plants by proliferation and vertical growth of discrete cell groups that include one or just a few of the cell lineages occurring in the holdfasts. Laboratory experiments showed growth competition between cell lineages, thus explaining lineage segregation during growth along originally chimeric erect axes. Genotyping of the axes showed more heterogeneous tissues basally, but apically more homogeneous ones, generating a vertical gradient of allele abundance and diversity. The few chimeric primary branches produced, eventually became homogenous after repeated branching. Therefore, coalescing macroagae exhibit a unique pattern of post-fusion growth, with the capacity to reverse chimerism. This pattern is significantly different from those in animals and land plants, suggesting chimerism is a biologically heterogeneous concept.
Assuntos
Quimerismo , Rodófitas/crescimento & desenvolvimento , Rodófitas/genética , Linhagem da Célula , Frequência do Gene , Alga Marinha/genética , Alga Marinha/crescimento & desenvolvimentoRESUMO
Hypnea has an intricate nomenclatural history due to a wide pantropical distribution and considerable morphological variation. Recent molecular studies have provided further clarification on the systematics of the genus; however, species of uncertain affinities remain due to flawed taxonomic identification. Detailed analyses coupled with literature review indicated a strong relationship among H. aspera, H. cervicornis, H. flexicaulis, and H. tenuis, suggesting a need for further taxonomic studies. Here, we analyzed sequences from two molecular markers (COI-5P and rbcL) and performed several DNA-based delimitation methods (mBGD, ABGD, SPN, PTP and GMYC). These molecular approaches were contrasted with morphological and phylogenetic evidence from type specimens and/or topotype collections of related species under a conservative approach. Our results demonstrate that H. aspera and H. flexicaulis represent heterotypic synonyms of H. cervicornis and indicate the existence of a misidentified Hypnea species, widely distributed on the Brazilian coast, described here as a new species: H. brasiliensis. Finally, inconsistencies observed among our results based on six different species delimitation methods evidence the need for adequate sampling and marker choice for different methods.
Assuntos
Filogenia , Rodófitas/classificação , Proteínas de Algas/genética , Brasil , Código de Barras de DNA Taxonômico , Rodófitas/anatomia & histologia , Rodófitas/genética , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
Mazzaella laminarioides is a common haploid-diploid red alga that forms dense beds. This alga has a wide distributional range, covering 3,500 km of the Chilean coast, but is restricted to high rocky intertidal zones. Recently, the existence of three highly divergent genetic lineages was demonstrated for this taxon, and two cytoplasmic markers were used to determine that these lineages are distributed in strict parapatry. Here, using 454 next-generation sequencing, we developed polymorphic microsatellite loci that cross amplify in all three cytoplasmic lineages. Six sites (i.e., two sites within each lineage) were analyzed using nine microsatellite loci. Our work shows that, although substantial cytoplasmic differentiation occurs within M. laminarioides, the microsatellite loci did not retrieve three nuclear genetic clusters as expected. Indeed, while the northernmost and southernmost cytoplasmic lineages form two strongly divergent nuclear groups characterized by diagnostic alleles, the third cytoplasmic lineage did not form a third nuclear independent group. It is possible that inter-lineage gene exchange has occurred, particularly at sites along the contact zone between the different cytoplasmic lineages. This nuclear-cytoplasmic incongruence in M. laminarioides could be explained by incomplete lineage sorting of the nuclear genes or asymmetric introgressive hybridization between the lineages. Finally, highly significant heterozygote deficiencies (suggesting occurrence of intergametophytic selfing) were observed in the three small northernmost sites while the large southernmost sites generally approached panmixia.
Assuntos
Marcadores Genéticos , Variação Genética , Repetições de Microssatélites , Rodófitas/genética , Chile , DNA de Algas/genética , Análise de Sequência de DNARESUMO
A molecular taxonomic study of the bladed Bangiales of the South Eastern Pacific (coast of Chile) was undertaken based on sequence data of the mitochondrial COI and chloroplast rbcL for 193 specimens collected from Arica (18°S) in the north to South Patagonia (53°S) in the south. The results revealed for the first time that four genera, Porphyra, Pyropia, Fuscifolium and Wildemania were present in the region. Species delimitation was determined based on a combination of a General Mixed Yule Coalescence model (GMYC) and Automatic Barcode Gap Discovery (ABGD) coupled with detection of monophyly in tree reconstruction. The overall incongruence between the species delimitation methods within each gene was 29%. The GMYC method led to over-splitting groups, whereas the ABGD method had a tendency to lump groups. Taking a conservative approach to the number of putative species, at least 18 were recognized and, with the exception of the recently described Pyropia orbicularis, all were new to the Chilean flora. Porphyra and Pyropia were the most diverse genera with eight 'species' each, whereas only a 'single' species each was found for Fuscifolium and Wildemania. There was also evidence of recently diverging groups: Wildemania sp. was distinct but very closely related to W. amplissima from the Northern Hemisphere and raises questions in relation to such disjunct distributions. Pyropia orbicularis was very closely related to two other species, making species delimitation very difficult but provides evidence of an incipient speciation. The difference between the 'species' discovered and those previously reported for the region is discussed in relation to the difficulty of distinguishing species based on morphological identification.
Assuntos
Rodófitas/classificação , Evolução Biológica , Chile , Código de Barras de DNA Taxonômico/métodos , Marcadores Genéticos , Especiação Genética , Variação Genética , Filogenia , Porphyra , Rodófitas/genéticaRESUMO
Nuclear DNA content in gametophytes and sporophytes or the prostrate phases of the following species of Bonnemaisoniaceae (Asparagopsis armata, Asparagopsis taxiformis, Bonnemaisonia asparagoides, Bonnemaisonia clavata and Bonnemaisonia hamifera) were estimated by image analysis and static microspectrophotometry using the DNA-localizing fluorochrome DAPI (4', 6-diamidino-2-phenylindole, dilactate) and the chicken erythrocytes standard. These estimates expand on the Kew database of DNA nuclear content. DNA content values for 1C nuclei in the gametophytes (spermatia and vegetative cells) range from 0.5 pg to 0.8 pg, and for 2C nuclei in the sporophytes or the prostrate phases range from 1.15-1.7 pg. Although only the 2C and 4C values were observed in the sporophyte or the prostrate phase, in the vegetative cells of the gametophyte the values oscillated from 1C to 4C, showing the possible start of endopolyploidy. The results confirm the alternation of nuclear phases in these Bonnemaisoniaceae species, in those that have tetrasporogenesis, as well as those that have somatic meiosis. The availability of a consensus phylogenetic tree for Bonnemaisoniaceae has opened the way to determine evolutionary trends in DNA contents. Both the estimated genome sizes and the published chromosome numbers for Bonnemaisoniaceae suggest a narrow range of values consistent with the conservation of an ancestral genome.
Assuntos
DNA de Algas/metabolismo , Estágios do Ciclo de Vida , Rodófitas/crescimento & desenvolvimento , Rodófitas/genética , Núcleo Celular/genética , DNA de Algas/genética , Genoma/genética , Células Germinativas Vegetais/metabolismo , Microespectrofotometria , Ploidias , Poliploidia , Rodófitas/classificaçãoRESUMO
The association of metazoan, protist, and microbial communities with Scleractinian corals forms the basis of the coral holobiont. Coral bleaching events have been occurring around the world, introducing changes in the delicate balance of the holobiont symbiotic interactions. In this study, Archaea, bacteria, and eukaryotic phototrophic plastids of bleached colonies of the Brazilian coral Siderastrea stellata were analyzed for the first time, using 16S rRNA gene libraries. Prokaryotic communities were slightly more diverse in healthy than in bleached corals. However, the eukaryotic phototrophic plastids community was more diverse in bleached corals. Archaea phylogenetic analyses revealed a high percentage of Crenarchaeota sequences, mainly related to Nitrosopumilus maritimus and Cenarchaeum symbiosum. Dramatic changes in bacterial community composition were observed in this bleaching episode. The dominant bacterial group was Alphaproteobacteria followed by Gammaproteobacteria in bleached and Betaproteobacteria in healthy samples. Plastid operational taxonomic units (OTUs) from both coral samples were mainly related to red algae chloroplasts (Florideophycea), but we also observed some OTUs related to green algae chloroplasts (Chlorophyta). There seems to be a strong relationship between the Bacillariophyta phylum and our bleached coral samples as clones related to members of the diatom genera Amphora and Nitzschia were detected. The present study reveals information from a poorly investigated coral species and improves the knowledge of coral microbial community shifts that could occur during bleaching episodes.