Physical mapping of the Nile tilapia (Oreochromis niloticus) genome by fluorescent in situ hybridization of repetitive DNAs to metaphase chromosomes - a review

The Nile tilapia (Oreochromis niloticus) has received increasing scientific interest over the past few decades for two reasons: first, tilapia is an enormously important species in aquaculture worldwide, especially in regions where there is a chronic shortage of animal protein; and second, this teleost fish belongs to the fascinating group of cichlid fishes that have undergone a rapid and extensive radiation of much interest to evolutionary biologists. Currently, studies based on physical and genetic mapping of the Nile tilapia genome offer the best opportunities for applying genomics to such diverse questions and issues as phylogeography, isolation of quantitative trait loci involved in behaviour, morphology, and disease, and overall improvement of aquacultural stocks. In this review, we have integrated molecular cytogenetic data for the Nile tilapia describing the chromosomal location of the repetitive DNA sequences, satellite DNAs, telomeres, 45S and 5S rDNAs, and the short and long interspersed nucleotide elements [short interspersed nuclear elements (SINEs) and long interspersed nuclear elements (LINEs)], and provide the beginnings of a physical genome map for this important teleost fish. (C) 2004 Elsevier B.V. All rights reserved.

Cytogenetic studies in three species of Lutjanus (Perciformes: Lutjanidae: Lutjaninae) from the Isla Margarita, Venezuela

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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)

Cytogenetic Markers in Wild Population of Curimbata (Prochilodus lineatus) from Mogi-Guacu River

Within the genus Prochilodus, the species Prochilodus lineatus is certainly the most studied one from a cytogenetic point of view. In this study, a cytogenetic characterization of specimens of P. lineatus from Mogi-Guacu River was performed in the period from 2003 to 2007, through utilization of cytogenetic markers, such as Giemsa, Ag-NOR, C-banding and cytogenetical-molecular markers (FISH) to detect both 5S and 18S ribosomal genes. All analyzed individuals presented 2n=54 meta/submetacentric chromosomes, besides bearing up to 7 supernumerary Microchromosomes. Polymorphic NORs were detected on a single chromosomal pair. The constitutive heterochromatin was distributed at centromeric region of all chromosomes in the A complement, while the microchromosomes were totally heterochromatic. A syntenic distribution of 5S and 18S ribosomal genes was detected, comprising the NOR-bearing chromosomal pair. No additional ribosomal clusters in other chromosomes were observed. Although the karyotype features are commonly conserved within the genus Prochilodus, the few differences on the distribution of both ribosomal genes and heterochromatin when compared to specimens of P lineatus from other localities can be associated to the evolutionary changes that these repetitive sequences have undergone through the years.

Cytogenetic characterization of Eurysternus caribaeus (Coleoptera: Scarabaeidae): evidence of sex-autosome fusion and diploid number reduction prior to species dispersion

Mitotic and meiotic chromosomes of several populations of Eurysternus caribaeus (Coleoptera: Scarabaeidae) were analysed through conventional staining, C-banding, base-specific fluorochromes, silver nitrate staining and fluorescent in situ hybridization (FISH). All specimens showed 2n = 8 in their karyotypes, with a neo-XY sex system (Y is a submetacentric and X a metacentric) and three pairs of submetacentric autosomes. The analysis of constitutive heterochromatin (CH) revealed small blocks located in the centromeric region of all chromosomes which do not present positive staining under the fluorochromes CMA3 and DAPI. Silver nitrate staining revealed that the nucleolar organizer region (NORs) is associated with the sex chromosomes. The FISH technique revealed that rDNA sites in the X and Y are different in size. Data from different populations indicate that the diploid number reduction (2n = 8) observed in E. caribaeus is established and presumably has preceded the dispersion of this species. Moreover, this reduction occasioned the translocation of rDNA sites to the sex chromosomes, X and Y, an uncommon pattern in Scarabaeidae that was observed for the first time by the FISH in this work.

Chromosomal painting and ZW sex chromosomes differentiation in Characidium (Characiformes, Crenuchidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Localization of 18S ribosomal genes in suckermouth armoured catfishes Loricariidae (Teleostei, Siluriformes) with discussion on the Ag-NOR evolution

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

Phylogeny, ultrastructure, histopathology and prevalence of Myxobolus oliveirai sp. nov., a parasite of Brycon hilarii (Characidae) in the Pantanal wetland, Brazil

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

Myxobolus cordeiroi n. sp., a parasite of Zungaro jahu (Siluriformes: Pimelodiade) from Brazilian Pantanal: Morphology, phylogeny and histopathology

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

Cytogenetic characterisation of the ornamental freshwater fish, Piabucus melanostomus (Iguanodectinae) from Brazilian wetlands and its relation with species of Characidae basal group

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Molecular and ultrastructural profiles of the symbionts in Cephalotes ants

The molecular and ultrastructural profiles of the symbionts found in the midgut and ileum of Cephalotes atratus, Cephalotes clypeatus, and Cephalotes pusillus were determined using the V3 region of the bacterial 16S rDNA gene and transmission electron microscopy (T.E.M.). Two samples of C atratus, three of C clypeatus, and six of C. pusillus were analyzed. The coefficients of similarity ranged from 80% to 94% for the samples of symbionts from C. clypeatus and C. atratus, despite being collected in geographically distant sites. The variability within symbionts found in the samples of C. pusillus varied from 29% to 55%, in samples geographically close as well as distant. PCR-DGGE was effective for the purpose of this study and can be considered a versatile tool to analyze gut microbiota. Details of the ultrastructural aspect of these bacteria are presented. (C) 2010 Elsevier Ltd. All rights reserved.

Trends in the karyotypic evolution of the Neotropical catfish family Heptapteridae Bockmann 1998 (Teleostei: Siluriformes)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparative cytogenetics of eight species of Cycloramphus (Anura, Cycloramphidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative karyotype analysis and chromosome evolution in the genus Aplastodiscus (Cophomantini, Hylinae, Hylidae)

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

Cytogenetic analyses of eight species in the genus Leptodactylus Fitzinger, 1843 (Amphibia, Anura, Leptodactylidae), including a new diploid number and a karyotype with multiple translocations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)