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M R Câmara - One of the best experts on this subject based on the ideXlab platform.
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ovarian development in the amazonian red discus Symphysodon discus heckel osteichthyes cichlidae
Brazilian Journal of Biology, 2005Co-Authors: Sarah Laxhmi Chellappa, M R Câmara, J R VeraniAbstract:The Neotropical red discus fish, Symphysodon discus, originates from the Amazonian basin and has a discoid body. Although this species is popularly used in aquaria and is exported as an ornamental fish, it has not been intensively studied. The purpose of this work was to study the morphological and histological aspects of the ovarian development in the red discus. Forty females of S. discus of varying body sizes and different stages of gonadal development were used in this study. The ovaries were weighed and examined macroscopically in order to observe the maturation stages. Histological staining of hematoxilin-eosin was used for microscopic observations of the ovaries. Macroscopic observations showed immature, maturing, mature and partially spent stages of ovarian development. Microscopic examination of the ovaries revealed five stages and five phases of ovarian development. The ovaries of the mature females showed all the different phases of oocyte development, indicating the multiple spawning habit of this species.
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Biologia reprodutiva do cíclídeo neotropical ornamental acará disco, Symphysodon discus Heckel, 1840 (Osteichthyes: Perciformes: Cichlidae).
Programa de Pós-graduação em Ecologia e Recursos Naturais, 2004Co-Authors: M R CâmaraAbstract:The Neotropical cichlid fish red discus, Symphysodon discus Heckel, 1840 originates from the Amazonian basin. Though this species is popularly used in aquaria and is exported as an ornamental fish, it has not been intensively studied. As such, this work was carried out with an objective to study the reproductive biology of this species. Eighty individuals of both sexes of different body sizes and in different stages of gonadal development were used in this study. The gonads were examined macroscopically in order to observe the maturation stages and histological staining was used for microscopic observations. The fecundity, type of spawning and the gonadosomatic index were determined. Aggressive interactions and territoriality between mature males of different body sizes were observed in neutral situation. The results of macroscopic observations of the gonads of both sexes showed the four stages of gonadal development, such as, immature, maturing, mature and partially spent. Microscopic examinations showed five different phases of the ovarian development and four testicular developmental stages. The average fecundity per batch was 536 oocytes. The gonads of the mature females showed all the different phases of oocyte development indicating the multiple spawning habit of this species. The mature males in the reproductive phase manifested aggression, territoriality and defence of territory, exhibiting differences in body size, degree of aggression and capacity of territorial defence. The bigger males were more aggressive than the smaller males. The males with established territories were preferred by the females for courtship.Financiadora de Estudos e ProjetosO acará disco, Symphysodon discus Heckel, 1840, é um ciclídeo originário dos igarapés da bacia Amazônica. Apesar do fato desta espécie estar sendo popularmente utilizada em aquariofilia e exportada como peixe ornamental, ainda é pouco estudada. Portanto, este trabalho teve como objetivo estudar a biologia reprodutiva desta espécie. Foram utilizados oitenta exemplares, quarenta de cada sexo, de tamanhos variados de S. discus, em diferentes fases de desenvolvimento gonadal. As gônadas foram examinadas macroscopicamente para avaliar os estádios de maturação e microscopicamente utilizando-se técnicas histológicas. A fecundidade, o tipo de desova e o índice gonadossomático foram avaliados. Interações agressivas e territorialidade entre machos maduros de diferentes tamanhos foram observadas em situação neutra. Os resultados da análise macroscópica das gônadas de ambos os sexos permitiram caracterizar quatro estádios de desenvolvimento: imaturo, em maturação, maduro e parcialmente esgotado. Microscopicamente, foram identificadas cinco diferentes fases de desenvolvimento ovariano e quatro fases de desenvolvimento testicular. A fecundidade média por lote foi de 536 óvulos. As gônadas das fêmeas maduras apresentaram todas as diferentes fases de desenvolvimento ovocitário, indicando tratar-se de desova do tipo parcelada. Os machos na fase reprodutiva manifestaram agressividade, territorialidade e defesa do território, apresentando diferenças entre si, tanto em relação ao tamanho do corpo, quanto ao nível de agressividade e à capacidade de defesa de território. Os machos maiores apresentaram maior agressividade que os menores. Os que estabeleceram território foram preferidos pelas fêmeas para acasalamento
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Biologia reprodutiva do cíclídeo neotropical ornamental acará disco, Symphysodon discus Heckel, 1840 (Osteichthyes: Perciformes: Cichlidae).
Universidade Federal de São Carlos, 2004Co-Authors: M R CâmaraAbstract:O acará disco, Symphysodon discus Heckel, 1840, é um ciclídeo originário dos igarapés da bacia Amazônica. Apesar do fato desta espécie estar sendo popularmente utilizada em aquariofilia e exportada como peixe ornamental, ainda é pouco estudada. Portanto, este trabalho teve como objetivo estudar a biologia reprodutiva desta espécie. Foram utilizados oitenta exemplares, quarenta de cada sexo, de tamanhos variados de S. discus, em diferentes fases de desenvolvimento gonadal. As gônadas foram examinadas macroscopicamente para avaliar os estádios de maturação e microscopicamente utilizando-se técnicas histológicas. A fecundidade, o tipo de desova e o índice gonadossomático foram avaliados. Interações agressivas e territorialidade entre machos maduros de diferentes tamanhos foram observadas em situação neutra. Os resultados da análise macroscópica das gônadas de ambos os sexos permitiram caracterizar quatro estádios de desenvolvimento: imaturo, em maturação, maduro e parcialmente esgotado. Microscopicamente, foram identificadas cinco diferentes fases de desenvolvimento ovariano e quatro fases de desenvolvimento testicular. A fecundidade média por lote foi de 536 óvulos. As gônadas das fêmeas maduras apresentaram todas as diferentes fases de desenvolvimento ovocitário, indicando tratar-se de desova do tipo parcelada. Os machos na fase reprodutiva manifestaram agressividade, territorialidade e defesa do território, apresentando diferenças entre si, tanto em relação ao tamanho do corpo, quanto ao nível de agressividade e à capacidade de defesa de território. Os machos maiores apresentaram maior agressividade que os menores. Os que estabeleceram território foram preferidos pelas fêmeas para acasalamento.The Neotropical cichlid fish red discus, Symphysodon discus Heckel, 1840 originates from the Amazonian basin. Though this species is popularly used in aquaria and is exported as an ornamental fish, it has not been intensively studied. As such, this work was carried out with an objective to study the reproductive biology of this species. Eighty individuals of both sexes of different body sizes and in different stages of gonadal development were used in this study. The gonads were examined macroscopically in order to observe the maturation stages and histological staining was used for microscopic observations. The fecundity, type of spawning and the gonadosomatic index were determined. Aggressive interactions and territoriality between mature males of different body sizes were observed in neutral situation. The results of macroscopic observations of the gonads of both sexes showed the four stages of gonadal development, such as, immature, maturing, mature and partially spent. Microscopic examinations showed five different phases of the ovarian development and four testicular developmental stages. The average fecundity per batch was 536 oocytes. The gonads of the mature females showed all the different phases of oocyte development indicating the multiple spawning habit of this species. The mature males in the reproductive phase manifested aggression, territoriality and defence of territory, exhibiting differences in body size, degree of aggression and capacity of territorial defence. The bigger males were more aggressive than the smaller males. The males with established territories were preferred by the females for courtship
Edson A Adriano - One of the best experts on this subject based on the ideXlab platform.
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morphology and small subunit rdna based phylogeny of ceratomyxa amazonensis n sp parasite of Symphysodon discus an ornamental freshwater fish from amazon
Parasitology Research, 2016Co-Authors: Patrick D Mathews, Juliana Naldoni, Antonio Augusto Mendes Maia, Edson A AdrianoAbstract:The specious genus Ceratomyxa Thelodan, 1892, infect mainly gallbladder of marine fishes, with only five species reported infecting species from freshwater environment. This study performed morphological and phylogenetic analyses involving a new Ceratomyxa species (Ceratomyxa amazonensis n. sp.) found in gallbladder of Symphysodon discus Heckel, 1840 (Perciformes: Cichlidae), an important ornamental fish endemic to Amazon basin. Mature spores were strongly arcuate shaped and measured 7.0 ± 0.3 (6.2-7.6) μm in length, 15.8 ± 0.4 (15.0-16.7) μm in thickness, and polar capsules 3.22 ± 0.34 (2.4-3.6) μm in length and 2.63 ± 0.17 (2.4-2.9) μm in width. This was the first small subunit ribosomal DNA (SS rDNA) sequencing performed to Ceratomyxa species parasite of freshwater fish, and the phylogenetic analysis showed C. amazonensis n. sp. clustering in the early diverging subclade of the ceratomyxids, together with species of parasites of amphidromous/estuaries fishes, suggesting some role of the transition of the fishes between marine/freshwater environments in the evolutionary history of these parasites.
Adalberto Luis Val - One of the best experts on this subject based on the ideXlab platform.
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Functional Categorization of Transcriptome in the Species Symphysodon aequifasciatus Pellegrin 1904 (Perciformes: Cichlidae) Exposed to Benzo[a]pyrene and Phenanthrene
2013Co-Authors: Lemgruber, Renato De Souza Pinto, Marshall, Nislanha Ana Dos Anjos, Ghelfi Andrea, Fagundes, Daniel Barros, Adalberto Luis ValAbstract:This study aims to evaluate the transcriptome alterations, through cDNA libraries, associated with the combined effects of two PAHs, benzo[a]pyrene (0.5 µg/L) and phenanthrene (50 µg/L), present in crude oil, on specimens of Symphysodon aequifasciatus (discus fish) after 48 h of exposure. The cDNA libraries were constructed according to the SOLiD™ SAGE™ protocol for sequencing in the SOLiD v.3 Plus sequencer. The results were analyzed by bioinformatics and differentially expressed genes were categorized using the gene ontology program. The functional categories (terms) found in the gene ontology and the gene network generated using STRING software were used to predict the adverse effects of benzo[a]pyrene and phenanthrene in the liver. In the present study, 27,127 genes (compared to Danio rerio database) were identified. Considering only those genes with a p-value less than or equal to 0.05 and greater than or equal to two-fold change in expression across libraries, we found 804 genes, 438 down-regulated (54%) and 366 up-regulated (46%), in the experimental group compared to the control. Out of this total, 327 genes were successfully categorized, 174 down-regulated and 153 up-regulated, using gene ontology. Using String, the gene network was composed by 199 nodes, 124 of them resulting in 274 interactions. The results showed that even an acute exposure of 48 h caused metabolic change in response to environmental contaminants, resulting in changes of cell integrity, in oxidation-reduction processes, in the immune response and disturbances of intracellular signaling of discus fish. Also the gene network has showed no central interplay cluster, exhibiting instead interconnected clusters interactions and connected sub-networks. These findings highlight that even an acute sublethal exposure of PAHs can cause metabolism changes that may affect survival of discus. Our findings using SOLiD coupled with SAGE-method resulted in a powerful and reliable means for gene expression analysis in discus, a non-model Amazonian fish
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A toxic diet: transfer of contaminants to offspring through a parental care mechanism
2013Co-Authors: Richard J Maunder, Adalberto Luis Val, Buckley Jonathan, Katherine A SlomanAbstract:The transfer of maternal contaminants to offspring during oogenesis and gestation is documented in many animals, and in mammals, contaminants may pass from mother to offspring during lactation. Although other non-mammalian vertebrates provide parental care in the form of nutritive secretions for offspring to feed from, the potential for toxicant transfer during non-mammalian parental care is rarely considered. The discus fish, Symphysodon spp., employs an unusual parental care strategy where fry feed on parental epidermal mucus for several weeks after hatching. This strategy has the potential to act as a method of contaminant transfer. In discus adults, both waterborne and dietary toxicants are sequestered and secreted into their epidermal mucus, the food on which fry depend. To determine whether parents could channel these contaminants directly to offspring, we exposed parents to aqueous cadmium (Cd) and recorded the subsequent feeding behaviour and Cd content of fry. Fry continued to feed normally from contaminated mucus and accumulated significant tissue concentrations of Cd. In conclusion, this parental care mechanism of the discus fish can expose offspring to harmful contaminants during the sensitive early stages of life and highlights that parent to offspring contaminant transfer after birth may be more widespread than previously thought
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biparental mucus feeding a unique example of parental care in an amazonian cichlid
The Journal of Experimental Biology, 2010Co-Authors: Jonathan Buckley, Richard J Maunder, Andrew D Foey, Janet Pearce, Adalberto Luis Val, Katherine A SlomanAbstract:Vertebrates display a wide variety of parental care behaviours, including the guarding of offspring pre and post nutritional independence as well as the direct provision of nutrients during the early development period. The Amazonian cichlid Symphysodon spp. (discus fish) is unusual among fish species, in that both parents provide offspring with mucus secretions to feed from after hatching. This extensive provision of care, which can last up to a month, imposes a physiological demand on both parents and gives rise to conflict between the parent and offspring. Here, we investigated the relationship between parents and offspring during a breeding cycle, determining both mucus composition (total protein, cortisol, immunoglobulin, and Na(+), K(+) and Ca(2+) concentrations) and the behavioural dynamics of the parent-offspring relationship. Over the course of a breeding cycle, a significant increase in offspring bite rate was recorded, with a concomitant increase in the frequency of turns the male and female parent took at caring for their young. A peak in mucus antibody provision was seen as offspring reached the free-swimming stage, suggesting a role analogous to colostrum provision in mammals. Mucus protein content was lowest during the second and third weeks of free swimming, and a weaning period, similar to that seen in mammalian parental care, occurred when the offspring had been free swimming for ∼3 weeks. In many ways, the parental behaviour of discus fish is more similar to mammalian and avian parental care than other fish species, and represents an exciting aquatic model for studying the parent-offspring conflict.
Gross, Maria Claudia - One of the best experts on this subject based on the ideXlab platform.
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Chromosomal distribution of microsatellite repeats in Amazon cichlids genome (Pisces, Cichlidae)
2015Co-Authors: Schneider, Carlos Henrique, Gross, Maria Claudia, Terencio, Maria Leandra, Tavares, Edika Sabrina Girão Mitozo, Martins Cesar, Feldberg EiianaAbstract:Fish of the family Cichlidae are recognized as an excellent model for evolutionary studies because of their morphological and behavioral adaptations to a wide diversity of explored ecological niches. In addition, the family has a dynamic genome with variable structure, composition and karyotype organization. Microsatellites represent the most dynamic genomic component and a better understanding of their organization may help clarify the role of repetitive DNA elements in the mechanisms of chromosomal evolution. Thus, in this study, microsatellite sequences were mapped in the chromosomes of Cichla monoculus Agassiz, 1831, Pterophyllum scalare Schultze, 1823, and Symphysodon discus Heckel, 1840. Four microsatellites demonstrated positive results in the genome of C. monoculus and S. discus, and five demonstrated positive results in the genome of P. scalare. In most cases, the microsatellite was dispersed in the chromosome with conspicuous markings in the centromeric or telomeric regions, which suggests that sequences contribute to chromosome structure and may have played a role in the evolution of this fish family. The comparative genome mapping data presented here provide novel information on the structure and organization of the repetitive DNA region of the cichlid genome and contribute to a better understanding of this fish family's genome
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Chromosomal evolution of neotropical cichlids: The role of repetitive DNA sequences in the organization and structure of karyotype
2013Co-Authors: Schneider, Carlos Henrique, Gross, Maria Claudia, Terencio, Maria Leandra, Martins Cesar, Artoni, Roberto Ferreira, Vicari, Marcelo Ricardo, Feldberg ElianaAbstract:Cichlids are important in the aquaculture and ornamental fish trade and are considered models for evolutionary biology. However, most studies of cichlids have investigated African species, and the South American cichlids remain poorly characterized. Studies in neotropical regions have focused almost exclusively on classical cytogenetic approaches without investigating physical chromosomal mapping of specific sequences. The aim of the present study is to investigate the genomic organization of species belonging to different tribes of the subfamily Cichlinae (Cichla monoculus, Astronotus ocellatus, Geophagus proximus, Acaronia nassa, Bujurquina peregrinabunda, Hoplarchus psittacus, Hypselecara coryphaenoides, Hypselecara temporalis, Caquetaia spectabilis, Uaru amphiacanthoides, Pterophyllum leopoldi, Pterophyllum scalare, and Symphysodon discus) and reexamine the karyotypic evolutionary patterns proposed for this group. Variations in some cytogenetic markers were observed, although no trends were found in terms of the increase, decrease, or maintenance of the basal diploid chromosome number 2n = 48 in the tribes. Several species were observed to have 18S rDNA genetic duplications, as well as multiple rDNA loci. In most of the taxa analyzed, the 5S rDNA was located in the interstitial region of a pair of homologous chromosomes, although variations from this pattern were observed. Interstitial telomere sites were also observed and appear to be involved in chromosomal rearrangement events and the accumulation of repeat-rich satellite DNA sequences. Our data demonstrated the karyotypic diversity that exists among neotropical cichlids, suggesting that most of this diversity is due to the repetitive sequences present in heterochromatic regions and that repeat sequences have greatly influenced the karyotypic evolution of these fishes. © 2012 Springer Science+Business Media B.V
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Comparative cytogenetic analysis of the genus Symphysodon (Discus Fishes, Cichlidae): Chromosomal characteristics of retrotransposons and minor ribosomal DNA
'S. Karger AG', 2010Co-Authors: Gross, Maria Claudia, Schneider, Carlos Henrique, Targino Valente Guilherme, Porto, Jorge Ivan Rebelo, Martins, Cesar Henrique Rossinoli, Feldberg ElianaAbstract:As part of a genetic screening program for wild Discus fishes, we analyzed karyotypes and cytogenetic characteristics of Symphysodon aequifasciatus, S. discus and S. haraldi using C-banding and fluorescent in situ hybridization (FISH) with the Rex3 retrotransposon and 5S rDNA probes in mitotic and meiotic chromosomes. In the 3 species, diploid chromosome number was 2n = 60 and karyotypes contained predominantly meta-submetacentric chromosomes. C-banding showed blocks of constitutive heterochromatin mainly in the pericentromeric region. Physical mapping of repetitive 5S rDNA sequences and Rex3 retrotransposons in mitotic and meiotic chromosomes showed partial colocalization of constitutive heterochromatin and repetitive elements. Correlations among the accumulation of repetitive elements, heterochromatinization and chromosome rearrangements have been hypothesized to explain the karyotype differentiation in the Symphysodon genus. The role of repetitive elements in adaptation to highly diverse habitats, as well as in the generation of the phenotypic and genetic variability found in wild Discus populations, needs to be further investigated. Copyright © 2010 S. Karger AG, Basel
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Citogenética comparativa das variedades selvagens de acará-disco (Symphysodon spp., Cichlidae, Perciformes) endêmicos da Amazônia: uma abordagem molecular dos cromossomos mitóticos e meióticos
Instituto Nacional de Pesquisas da Amazônia, 2009Co-Authors: Gross, Maria ClaudiaAbstract:O gênero Symphysodon compreende três espécies endêmicas da bacia amazônica, conhecidas popularmente como acarás-disco e muito apreciadas na aquariofilia. Dentro da família Cichlidae, essas espécies apresentam o maior número diploide já descrito, e para compreender os aspectos carioevolutivos das mesmas, análises citogenéticas clássica e molecular (utilizando sondas de DNAr 5S, DNAr 18S e retrotransposon Rex3) foram realizadas, assim como análise do complexo sinaptonêmico. Foram utilizados 22 S. aequifasciatus (14 ♂, oito ♀), 37 S. discus (15 ♂, 22 ♀) e 49 S. haraldi (21 ♂, 28 ♀). Symphysodon aequifasciatus apresentou 50m-sm+6st-a+4mi, S. discus 50msm+ 10st-a e S. haraldi 52m-sm+4st-a+4mi. Uma cadeia cromossômica multivalente, com número variável de elementos e até 20 bivalentes, foi observada no diplóteno/diacinese de espermatócitos e oócitos de S. aequifasciatus e S. haraldi. Em S. discus, 30 bivalentes foram detectados. Análise do complexo sinaptonêmico sugere homologia entre elementos formadores da cadeia, sendo verificada a presença de quiasmas ao longo de sua extensão. As três espécies possuem região organizadora de nucléolo múltipla, que variaram inter e intraespecíficamente, porém nunca mais que duas marcações foram evidenciadas por célula metafásica. Variabilidade, intra e interespecífica, também foi evidenciada nos sítios de DNAr 18S, sendo observados de 2 a 5 por metáfase: Symphysodon aequifasciatus apresentou dois padrões de distribuição, enquanto S. discus e S. haraldi mostraram quatro padrões. Sítios de DNAr 18S também estiveram presentes, algumas vezes, na cadeia meiótica das duas espécies portadoras. O DNAr 5S foi identificado no par 10 de S. aequifasciatus, enquanto em S. discus e S. haraldi este sítio foi evidenciado no par 18. Nos cromossomos meióticos das três espécies, os sítios de DNAr 5S foram localizados em bivalentes típicos. Com relação à localização do elemento Rex3, as três espécies apresentaram um padrão de distribuição compartimentalizada em alguns cromossomos e com sinais tênues de hibridização na região centromérica da maioria dos cromossomos. Tais sinais foram coincidentes com a heterocromatina na maioria das vezes. A somatória destes dados indica a ocorrência de inúmeros rearranjos cromossômicos, acúmulo e movimentação de elementos repetitivos, bem como heterocromatinização na carioevolução do gênero Symphysodon. A variabilidade dos sítios de DNAr 18S pode refletir a existência de translocações envolvendo regiões heterocromáticas ricas em elementos transponíveis, que teriam ocorrido independentemente em populações/espécies ancestrais de Symphysodon. Em um dado momento estas populações/espécies teriam formado híbridos, que formaram a cadeia cromossômica meiótica para que o ajustamento sináptico entre os segmentos cromossômicos homólogos das espécies parentais ocorresse. Estes híbridos seriam o que hoje reconhecemos como S. aequifasciatus e S. haraldi, enquanto S. discus seria uma espécie pura.The genus Symphysodon comprises three endemic species of the Amazon basin, commonly known as discus and highly prized by the aquarium trade. Within the family Cichlidae, these species have the highest diploid number described thus far. To understand the karyoevolutionary aspects of these species, classic and molecular (5S rDNA, 18S rDNA and retrotransposon Rex3) cytogenetic analyses were carried out, along with an analysis of the synaptonemal complex. Sixteen specimens of S. aequifasciatus (eight ♂, eight ♀), 37 specimens of S. discus (15 ♂, 22 ♀) and 43 specimens of S. haraldi (15 ♂, 28 ♀) were analyzed. Symphysodon aequifasciatus had 50m-sm+6st-a+4mi, S. discus 50m-sm+10st-a and S. haraldi 52m-sm+4st-a+4mi. A multivalent chromosomal chain with a variable number of elements and up to 10 bivalents was found in the diplotene/diakinesis of sperm and oocyte cells in S. aequifasciatus and S. haraldi. Analysis of synaptonemal complex suggests homology among the elements that make up the chain, with the presence of chiasms throughout its length. In S. discus thirty bivalents were detected in the diplotene/diakinesis of sperm and oocyte cells. The three species have multiple nucleolus organizer regions that vary in both inter-species and intra-species terms. However, no more than two NOR sites were found per metaphasic cell. Inter-species and intra-species variability was also found for the 18S rDNA sites, with two to five sites per metaphase: Symphysodon aequifasciatus exhibited two distribution patterns, whereas S. discus and S. haraldi exhibited four patterns. 18S rDNA sites were also sometimes found in the meiotic chain of the two species. 5S rDNA was identified in pair 10 in S. aequifasciatus, whereas this site was identified in pair 18 in S. discus and S. haraldi. In the meiotic chromosomes of the three species, 5S rDNA sites were located in typical bivalents. Regarding the localization of Rex3, the three species exhibited a compartmentalized distribution pattern in some chromosomes and tenuous sites of hybridization in the centromeric region of the majority of chromosomes. Such sites most often coincided with the heterochromatin. These data indicates theoccurrence of innumerous chromosome rearrangements, the accumulation and displacement of repetitive elements and heterochromatinization in the karyoevolution of the genus Symphysodon. The variability in 18S rDNA sites may reflect the existence of translocations involving heterochromatin regions rich in transposable elements, which may have occurred independently in ancestral populations/species of Symphysodon. At some point, these populations/species may have formed hybrids, which formed a meiotic chromosome chain so that synaptic adjustment could occur between the homologous chromosome segments of the parent species. These hybrids may be what we recognize today as S. aequifasciatus and S. haraldi, whereas S. discus may be a pure species
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Comportamento cromossômico meiótico e mitótico de acarás-disco (Symphysodon aequifasciatus e Symphysodon discus, Cichlidae, Perciformes) da Amazônia Central
Instituto Nacional de Pesquisas da Amazônia, 2006Co-Authors: Gross, Maria ClaudiaAbstract:Foram realizados estudos citogenéticos mitóticos e meióticos das espécies: Symphysodon aequifasciatus do rio Manacapuru- Manacapuru (AM) e Symphysodon discus do rio Negro- Novo Airão (AM). Todos os indivíduos apresentaram número diplóide igual a 60 cromossomos e não foram verificados cromossomos heteromórficos com características indicativas de cromossomos sexuais nas espécies analisadas. Em relação à fórmula cromossômica, S. aequifasciatus mostrou 46 M-SM + 14 microcromossomos e S. discus 50 M-SM + 10ST-A. Porém, alguns indivíduos de S. aequifasciatus exibiram constrições secundárias que não se coravam com Giemsa, parecendo haver uma variabilidade cariotípica. Quanto à heterocromatina constitutiva, ambas as espécies exibiram grandes blocos pericentroméricos em quase todos os cromossomos do complemento, porém, somente S. aequifasciatus apresentou seis pares cromossômicos inteiramente heterocromáticos. Com relação às regiões organizadoras de nucléolo, ambas as espécies evidenciaram RON múltiplas, contudo, sítios ribossomais foram detectados nos pares cromossômicos 4, 5, 11 e 21 em S. aequifasciatus e nos pares 17 e 23 em S. discus, porém nunca mais que dois sítios estiveram ativos. Na meiose, a diferença mais marcante encontrada entre as duas espécies foi durante o diplóteno/diacinese, visto que S. aequifasciatus apresentou, além de 20 bivalentes, uma cadeia envolvendo 20 cromossomos e S. discus apenas 30 bivalentes. Assim, 2n=60 cromossomos em ambas as espécies e a presença de cadeia cromossômica na meiose de S. aequifasciatus podem ser explicados por uma origem poliplóide para as duas espécies do gênero Symphysodon, uma vez que o número ancestral para a família Cichlidae é 2n=48 cromossomos, a maioria do tipo acrocêntrico. A cadeia cromossômica, encontrada apenas em S. aequifasciatus, pode indicar que esta se encontra em um período transiente, enquanto S. discus já teria terminado a sua diploidização, provavelmente por ser mais antiga que a primeira.Meiotic and mitotic cytogenetics studies were carried out on species: Symphysodon aequifasciatus collected from the Manacapuru River- Manacapuru (AM) and Symphysodon discus from the Negro River- Novo Airão (AM). All individuals showed a modal number of 2n=60 chromosomes and there was no sex chromosomal heteromorphism in these species. Regarding the chromosomal formulae, S. aequifasciatus showed 46 M-SM + 14 microchromosomes and S. discus 50 M-SM + 10ST-A. However, some S. aequifasciatus individuals showed a Giemsa non-stained secondary constriction, looking like a chromosomal polymorphism. The constitutive heterochromatin was seen as large pericentromeric blocks on most chromosomes, of both species, however only S. aequifasciatus showed six wholly heterochromatic pairs. Multiple nucleolus organizing regions were identified in both species, S. aequifasciatus presented ribosomal sites on chromosomal pairs 4, 5, 11 and 21, and S. discus on the pairs 17 and 23, but never more than two sites showed to be active. In the meiosis, the greater difference observed between the two species was during diplotene/diacinesis, because S. aequifasciatus showed a chromosomal chain with 20 elements and 20 bivalents, while S. discus presented only 30 bivalents. Thus, 2n=60 chromosomes, in both species, and a meiotic chromosomal chain, in S. aequifasciatus, can be accounted for the Symphysodon polyploidy origin, since the ancestral number to the Ciclhidae family is 2n=48 chromosomes, most of them of the acrocentric type. Moreover, the S. aequifasciatus chromosomal chain points that this species is probably found in a transience period, while S. discus finished its diploidization process, on account of it being the older species
Patrick D Mathews - One of the best experts on this subject based on the ideXlab platform.
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Molecular diagnostic based on 18S rDNA and supplemental taxonomic data of the cnidarian coelozoic Ceratomyxa (Cnidaria, Myxosporea) and comments on the intraspecific morphological variation
'Pensoft Publishers', 2021Co-Authors: Fabricio B. Sousa, Tiago Milanin, André C. Morandini, Luis L. Espinoza, Anai Flores-gonzales, Ana L.s. Gomes, Daniele A. Matoso, Patrick D MathewsAbstract:Ceratomyxa amazonensis is a cnidarian myxosporean originally described with strongly arcuate crescent-shaped myxospores, absence of vegetative stages and infecting Symphysodon discus, an important Amazonian ornamental fish in the aquarium industry. As part of a long-term investigation concerning myxosporeans that infect discus fish Symphysodon spp. from different rivers of the Amazon Basin, thirty specimens of S. discus collected from Unini River were examined. Plasmodial vegetative stages therefrom were found freely floating in the bile of gall bladders from eighteen fish. Mature myxospores were slightly crescent-shaped, measuring 4.72 ± 0.1 (4.52–4.81) μm in length, 24.2 ± 0.4 (23.9–25.3) μm in thickness with polar capsules 2.31 ± 0.1 (2.29–2.33) μm in length and 2.15 ± 0.1 (2.13–2.17) μm in width. Strong morphological differences were observed between the newly isolated myxospores obtained and the previously described C. amazonensis; however, molecular assessment, based on 18S rDNA, revealed a high similarity (99.91%), with only a single nucleotide base change. This study provides new data, expanding the original description of the species with a discussion on differences in myxospore-morphology in the context of intraspecific morphological plasticity
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morphology and small subunit rdna based phylogeny of ceratomyxa amazonensis n sp parasite of Symphysodon discus an ornamental freshwater fish from amazon
Parasitology Research, 2016Co-Authors: Patrick D Mathews, Juliana Naldoni, Antonio Augusto Mendes Maia, Edson A AdrianoAbstract:The specious genus Ceratomyxa Thelodan, 1892, infect mainly gallbladder of marine fishes, with only five species reported infecting species from freshwater environment. This study performed morphological and phylogenetic analyses involving a new Ceratomyxa species (Ceratomyxa amazonensis n. sp.) found in gallbladder of Symphysodon discus Heckel, 1840 (Perciformes: Cichlidae), an important ornamental fish endemic to Amazon basin. Mature spores were strongly arcuate shaped and measured 7.0 ± 0.3 (6.2-7.6) μm in length, 15.8 ± 0.4 (15.0-16.7) μm in thickness, and polar capsules 3.22 ± 0.34 (2.4-3.6) μm in length and 2.63 ± 0.17 (2.4-2.9) μm in width. This was the first small subunit ribosomal DNA (SS rDNA) sequencing performed to Ceratomyxa species parasite of freshwater fish, and the phylogenetic analysis showed C. amazonensis n. sp. clustering in the early diverging subclade of the ceratomyxids, together with species of parasites of amphidromous/estuaries fishes, suggesting some role of the transition of the fishes between marine/freshwater environments in the evolutionary history of these parasites.
