A tandemly repetitive centromeric DNA sequence of the fish Hoplias malabaricus (Characiformes : Erythrinidae) is derived from 5S rDNA

A substantial fraction of the eukaryotic genome consists of repetitive DNA sequences that include satellites, minisatellites, microsatellites, and transposable elements. Although extensively studied for the past three decades, the molecular forces that generate, propagate and maintain repetitive DNAs in the genomes are still discussed. To further understand the dynamics and the mechanisms of evolution of repetitive DNAs in vertebrate genome, we searched for repetitive sequences in the genome of the fish species Hoplias malabaricus. A satellite sequence, named 5SHindIII-DNA, which has a conspicuous similarity with 5S rRNA genes and spacers was identified. FISH experiments showed that the 5S rRNA bona fide gene repeats were clustered in the interstitial position of two chromosome pairs of H. malabaricus, while the satellite 5SHindIII-DNA sequences were clustered in the centromeric position in nine chromosome pairs of the species. The presence of the 5SHindIII-DNA sequences in the centromeres of several chromosomes indicates that this satellite family probably escaped from the selective pressure that maintains the structure and organization of the 5S rDNA repeats and become disperse into the genome. Although it is not feasible to explain how this sequence has been maintained in the centromeric regions, it is possible to hypothesize that it may be involved in some structural or functional role of the centromere organization.

Comparative chromosome mapping of 5S rDNA and 5SHindIII repetitive sequences in Erythrinidae fishes (Characiformes) with emphasis on the Hoplias malabaricus 'species complex'

Chromosomal localization of 5S rDNA and 5SHindIII repetitive sequences was carried out in several representatives of the Erythrinidae family, namely in karyomorphs A, D, and F of Hoplias malabaricus, and in H. lacerdae, Hoplerythrinusunitaeniatus and Erythrinus erythrinus. The 5S rDNA mapped interstitially in two chromosome pairs in karyomorph A and in one chromosome pair in karyomorphs D and F and in H. lacerdae. The 5SHindIII repetitive DNA mapped to the centromeric region of several chromosomes (18 to 22 chromosomes) with variations related to the different karyomorphs of H. malabaricus. on the other hand, no signal was detected in the chromosomes of H. lacerdae, H. unitaeniatus and E. erythrinus, suggesting that the 5SHindIII-DNA sequences have originated or were lost after the divergence of H. malabaricus from the other erythrinid species. The chromosome distribution of 5S rDNA and 5SHindIII-DNA sequences contributes to a better understanding of the mechanisms of karyotype differentiation among the Erythrinidae members.Copyright (c) 2007 S. Karger AG, Basel.

Ultrastructure of spermatogenic cells and spermatozoa in Hoplias malabaricus (teleostei, characiformes, erythrinidae)

The differentiation of spermatids in Hoplias malabaricus is characterized by chromatin compaction, flagellum development, nuclear rotation, nuclear fossa formation, and excess cytoplasm elimination. In the resulting spermatozoon, the head is round and the nucleus contains chromatin compacted in thick filaments, peripherically arranged, to a central electron-lucent area. The acrosome is absent. The nuclear fossa is eccentric but not pronounced. The proximal centriole penetrates it and is oblique to the flagellum. The long midpiece has several converging elongate vesicles, forming membranous hoops in the initial segment of the flagellum, but has no cytoplasmic channel. The mitochondria are elongate and branched or C-shaped and located around the initial segment of the axoneme. The lateral flagellum does not show lateral projections. The ultrastructural characteristics of H. malabaricus spermatozoa are similar to the Cypriniformes. (C) 2001 the Fisheries Society of the British Isles.

Spermatogonia and spermatocyte ultrastructure in Hoplias malabaricus (Teleostei, Characiformes : Erythrinidae)

The Hoplias malabaricus primary spermatogonium shows a large nucleus, central nucleolus, and low electron-dense cytoplasm containing nuages. In cysts, they undergo several mitotic divisions with incomplete cytokinesis, giving rise to secondary spermatogonia. These are smaller than the primary spermatogonia and their nuclei have one or two eccentric nucleoli. Spermatocytes I can be identified by the presence of synaptonemal complexes. Spermatocytes II are smaller than spermatocytes 1, displaying roughly compacted chromatin. All these cell types remain interconnected by thick-walled intercellular bridges, which have membranous reinforcements during mitosis and meiosis. These cell types show a well-developed endomembranous system, one of the centrioles anchored to the plasma membrane and small nuages. Their mitochondria are large and circular, with few cristae. In the last generations of spermatogonia, the mitochondria are smaller, elongate and have more cristae. In the spermatocytes, the mitochondria are small and round. Similarities found in relation to germ cells of other teleosts are discussed.

Population structure and stock assessment of Hoplias malabaricus (Characiformes: Erythrinidae) caught by artisanal fishermen in river-reservoir transition area in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Differentiation of the XY Sex Chromosomes in the Fish Hoplias malabaricus (Characiformes, Erythrinidae): Unusual Accumulation of Repetitive Sequences on the X Chromosome

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosomal Variability among Allopatric Populations of Erythrinidae Fish Hoplias malabaricus: Mapping of Three Classes of Repetitive DNAs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of invasive fish species in a river transposition region: evolutionary chromosome studies in the genus Hoplias (Characiformes, Erythrinidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spawning and parental care in Hoplias malabaricus (Teleostei, Characiformes, Erythrinidae) in the Southern Pantanal, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Larval Contracaecum sp (Nematoda : Anisakidae) in Hoplias malabaricus and Hoplerythrinus unitaeniatus (Osteichthyes : Erythrinidae) of economic importance in occidental marshlands of Maranhao, Brazil

This work describes the presence of Contracaecum sp. larvae (Nematoda: Anisakidae) found in food fish of economic importance captured in occidental marshlands in the State of Maranhao, Brazil. Hoplias malabaricus (Erythrinidae) and Hoplerythrinus unitaeniatus (Erythrinidae), commonly called traira and jeju, respectively, were examined. All H. malabaricus were infected with a mean intensity of 24.6 +/- 38.3 (1-137 parasites per host) while eighty percent of H. unitaeniatus showed a mean intensity of 10.4 +/- 9.2 (2-31) parasites. Nematodes were most similar to larvae of a type 2 described by Moravec, Kohn and Fernandes [Moravec, F., Kohn, A., Fernandes, B.M.M., 1993. Nematode parasites of fishes of the Parana River, Brazil. Part 2. Seuratoidea, Ascaridoidea, Habronematoidea and Acuarioidea. Folia Parasitol. 40, 115-134], but differed in having a longer intestinal caecum and greater caecum/ventricular appendix ratio. Larval measurements and a description of their Brazilian fish hosts are presented. (C) 2004 Elsevier B.V. All rights reserved.

Cytogenetic and DNA barcoding reveals high divergence within the trahira, Hoplias malabaricus (Characiformes: Erythrinidae) from the lower Amazon River

Dados moleculares e citogenéticos tem evidenciado especiação críptica na traíra sul-americana, Hoplias malabaricus. No presente estudo, cariótipos e sequências de DNA barcode de espécimes de sete populações, habitando a região do baixo rio Amazonas, foram analisadas a fim de caracterizar o nível de divergência genética dentro de um único cariomorfo. Todos os espécimes possuem 2n = 40 cromossomos (20m+20sm) os quais são inseridos no grupo de traíras do cariomorfo C. DNA barcode revelou seis haplogrupos, com clara divergência entre populações do Brasil e da Argentina. Os resultados apoiam a hipótese de complexo de espécies e indicam que um único cariomorfo de Hoplias malabaricus pode conter mais de uma espécie.

Genetic differentiation among distinct karyomorphs of the wolf fish Hoplias malabaricus species complex (Characiformes, Erythrinidae) and report of unusual hybridization with natural triploidy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uma Nova Abordagem do Ciclo Reprodutivo dos Machos e Fêmeas, e da Origem e Desenvolvimento dos Oócitos dos Ostariophysi e Perciformes Neotropicais Aplicada a Representantes da Série Otophysi, Gymnotus sp. (Gymnotidae), Hoplias Malabaricus (Erythrinidae), Sorubim Lima (Pimelodidae) e Tanichthys Albonubes (Cyprinidae), e dos Perciformes, Cichla Temensis (Cichlidae)

Nos peixes, durante a vida reprodutiva o desenvolvimento gonadal é cíclico e anual. As alterações estruturais das gônadas de machos e fêmeas provêm parâmetros úteis para a sua classificação macroscópica e microscópica. Porém, o desenvolvimento das células germinativas, nem sempre é consoante com os diferentes tipos de classificação e, machos e fêmeas nem sempre parecem concatenados. Neste estudo, aplicando-se propostas recentes, utilizadas primariamente para peixes derivados, notadamente os Perciformes marinhos, e tomando como modelo experimental representantes da série Otophysi, Hoplias malabaricus (Characiformes), Tanichthys albonubes (Cypriniformes), Sorubim lima (Siluriformes) e Gymnotus sp. (Gymnotiformes), e dos Perciformes Neotropicais, Cichla temensis, foram descritos, comparativamente, os eventos iniciais da oogênese e da espermatogênese, assim como o desenvolvimento oocitário a fim de traçar um paralelo entre grupos basais e derivados. A partir dos resultados, verificou-se que a maioria dos eventos morfológicos durante o desenvolvimento oocitário é similar entre grupos basais e derivados. Os Perciformes de água doce divergem dos grupos basais por duas características: a presença de inclusões lipídicas, que surgem no citoplasma perinuclear após o início da formação dos alvéolos corticais e deposição de vitelo e por uma tênue proteólise do vitelo durante a maturação final. A foliculogênese e espermatogênese não apresentam divergências e parecem ser processos conservados entre os Teleostei. Durante a fase de Regeneração, os eventos iniciais desses processos em fêmeas e machos, respectivamente, são responsáveis por altos índices de proliferação das células germinativas, quando comparado às demais fases. Além disso, analisou-se ...(Resumo completo, clicar acesso eletrônico abaixo)

Primeiro relato de larvas de Eustrongylides sp. (Nematoda: Dioctophymatidae) em Hoplias malabaricus (Characiformes: Erythrinidae) no Estado de Rondônia, Amazônia Ocidental, Brasil

O presente artigo descreve o primeiro relato de larvas de Eustrongylides sp. em Hoplias malabaricus Bloch, 1794 (Characiformes: Erythrinidae) no Estado de Rondônia, Amazônia Ocidental, Brasil, sendo mais um parasita com a possibilidade de contaminar humanos no Estado.