Evolutionary chromosomal differentiation among four species of Conoderus Eschscholtz, 1829 (Coleoptera, Elateridae, Agrypninae, Conoderini) detected by standard staining, C-banding, silver nitrate impregnation, and CMA(3)/DA/DAPI staining

The speciose Brazilian Elateridae fauna is characterized by high karyotypic diversity, including one species (Chalcolepidius zonatus Eschscholtz, 1829) with the lowest diploid number within any Coleoptera order. Cytogenetic analysis of Conoderus dimidiatus Germar, 1839, C. scalaris (Germar, 1824,) C. ternarius Germar, 1839, and C. stigmosus Germar, 1839 by standard and differential staining was performed with the aim of establishing mechanisms of karyotypic differentiation in these species. Conoderus dimidiatus, C. scalaris, and C. ternarius have diploid numbers of 2n(male) = 17 and 2n(female) = 18, and a X0/XX sex determination system, similar to that encountered in the majority of Conoderini species. The karyotype of C. stigmosus was characterized by a diploid number of 2n=16 and a neoXY/neoXX sex determination system that was highly differentiated from other species of the genus. Some features of the mitotic and meiotic chromosomes suggest an autosome/ancestral X chromosome fusion as the cause of the neoXY system origin in C. stigmosus. C-banding and silver impregnation techniques showed that the four Conoderus species possess similar chromosomal characteristics to those registered in most Polyphaga species, including pericentromeric C band and autosomal NORs. Triple staining techniques including CMA(3)/DA/DAPI also provided useful information for differentiating these Conoderus species. These techniques revealed unique GC-rich heterochromatin associated with NORs in C. scalaris and C. stigmosus and CMA(3)-heteromorphism in C. scalaris and C. ternarius.

High Diversity in CMA(3)/DAPI-Banding Patterns in Heteropterans

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Conserved Karyotypes in Cophomantini: Cytogenetic Analysis of 12 Species from 3 Species Groups of Bokermannohyla (Amphibia: Anura: Hylidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cytogenetic characterization of six species of flatfishes with comments to karyotype differentiation patterns in Pleuronectiformes (Teleostei)

The karyotypes and cytogenetic characteristics of flatfishes species Paralichthys orbignyanus, Paralichthys patagonicus, Citarichthys spilopterus and Etropus crossotus (Paralichthyidae), Bothus ocellatus (Bothidae) and Symphurus tessellatus (Cynoglossidae) were investigated by conventional [Giemsa staining, C-banding, Ag- and chromomycin (CMA(3))-stainings] and molecular [in situ hybridization (ISH)] cytogenetic techniques. The results showed 2n = 46 and FN = 48 (2msm + 46sta) in P. orbignyanus, 2n = 46 and FN = 46 (46sta) in P. patagonicus, 2n = 26 and FN = 44 (18msm + 8sta) in C. spilopterus, 2n = 38 and FN = 64 (26msm + 12sta) in E. crossotus, 2n = 32 and FN = 50 (18msm + 14sta) in B. ocellatus, and 2n = 46 and FN = 62 (46msm + 62sta) in S. tessellatus. All species exhibited weak C-band positive segments in terminal and centromeric positions of some chromosome pairs. Silver staining of the nucleolus organizer regions (Ag-NOR) technique showed a single Ag-NOR-bearing chromosome pair in all species except E. crossotus. All these sites were CMA(3) positive and showed clear ISH signals after probing with a 18S rRNA probe. Etropus crossotus presented until seven chromosomes with Ag-NORs and CMA(3) positively stained segments in five chromosome pairs. Conversely only one chromosome pair was identified with the ISH experiments in this species. The available results show that the fishes of the order Pleuronectiformes experienced a marked chromosome evolution that included reduction in diploid number, mainly due to Robertsonian rearrangements, and several chromosome inversions. (c) 2007 the Authors Journal compilation (c) 2007 the Fisheries Society of the British Isles.

New occurrence of microchromosomes B in Moenkhausia sanctaefilomenae (Pisces, Characidae) from the Parana River of Brazil: analysis of the synaptonemal complex

The Moenkhausia sanctaefilomenae specimens showed a karyotype consisting of 2n = 50 chromosomes with 12 metacentrics, 36 submetacentrics and two subtelocentrics. In addition to the basic karyotype, all the males specimens have cells ranging from zero to two B microchromosomes in mitotic metaphases. These chromosomes were not observed in the female specimens. C-band analysis showed a distribution pattern of characteristic heterochromatin with interstitial and centromeric blocks. However, the B chromosomes were faintly stained with C-banding and were not fluorescent with CMA(3) staining. The meiotic studies showed the formation of bivalents in metaphase I and in pachytene under an optical microscope. Through synaptonemal complex analysis with an electron microscope, the pachytene showed 25 bivalents completely paired and a small bivalent corresponding to the B chromosomes. In the same preparation, one of the B chromosomes was observed in a univalent form. on the basis of pairing behavior and morphology it is assumed that B chromosomes of M. sanctaefilomenae show homology between them and their evolutionary aspects are discussed.

Cytogenetic analysis of A- and B-chromosomes of Prochilodus lineatus (Teleostei, Prochilodontidae) using different restriction enzyme banding and staining methods

Different cytogenetic techniques were used to analyse the chromosomes of Prochilodus lineatus with the main objective of comparing the base composition of A- and B-chromosomes. The results of digestion of chromosomes with 10 different restriction endonucleases (REs), silver staining, CMA(3) staining and C-banding indicated the existence of different classes of highly repetitive DNA in the A-set and also suggested the existence of compositional differences between the chromatin of A- and B-chromosomes. The 5-BrdU incorporation technique showed a late replicating pattern in all B-chromosomes and in some heterochromatic pericentromeric regions of A-chromosomes. The cleavage with RE BamHI produced a band pattern in all chromosomes of P. lineatus which permitted the tentative pairing of homologues in the karyotype of this species. We concluded that the combined use of the above techniques can contribute to the correct identification of chromosomes and the karyotypic analysis in fishes. on the basis of the results, some aspects of chromosome structure and the origin of the B-chromosomes in P. lineatus are discussed.

Cytogenetic characterization of a supernumerary chromosome segment and of B-chromosomes in Astyanax scabripinnis (Teleostei, Characidae)

The chromosome complement of a local population of Astyanax scabripinnis in Brazil was investigated with emphasis on the study of the heterochromatin attached to the A-chromosomes and present in the macro B-chromosome. Analysis after C-banding, silver and CMA(3) staining, incorporation of 5-bromo-2'-deoxyuridine and chromosome digestion with nine restriction endonucleases revealed that the heterochromatin in the B-chromosomes was different from that found in the A-chromosomes. A polymorphism due to the presence of a supernumerary heterochromatic chromosome segment was observed in the population investigated. Some aspects related to the origin of the heterochromatin polymorphism in Astyanax scabripinnis are discussed.

Sex chromosome evolution in fish: the formation of the neo-Y chromosome in Eigenmannia (Gymnotiformes)

Chromosomes of a species of Eigenmannia presenting a X1X1X2X2:X1X2Y sex chromosome system, resulting from a Y-autosome Robertsonian translocation, were analyzed using the C-banding technique, chromomycin A(3) (CMA(3)) and mithramycin (MM) staining and in situ digestion by the restriction endonuclease AluI. A comparison of the metacentric Y chromosome of males with the corresponding acrocentrics in females indicated that a C-band-positive, CMA(3)/MM-fluorescent and AluI digestion-resistant region had been lost during the process of translocation, resulting in a diminution of heterochromatin in the males. It is hypothesized that the presence of a smaller amount of G+C-rich heterochromatin in the sex chromosomes of the heteromorphic sex when compared with the homomorphic sex may be associated with the sex determination mechanism in this species and may be a more widely occurring phenomenon in fish with differentiated sex chromosomes than was initially thought.

Heterochromatin, Sex Chromosomes and rRNA Gene Clusters in Coprophanaeus Beetles (Coleoptera, Scarabaeidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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)

Occurrence of ZZ/ZW sex chromosomes in Thoracocharax stellatus fish (Characiformes, Gasteropelecidae) from the Araguaia River, south America

The karyotypic and chromosomal characteristics of the hatchetfish Thoracocharax stellatus from the Araguaia River, Brazil (Araguaia-Tocantins basin) were analyzed using Giemsa, AgNO3, and CMA(3) fluorescent staining, and C-banding. The diploid chromosome number was 54 and the karyotypes of females and males were composed of six metacentrics, six submetacentrics, six subtelocentrics and 36 acrocentrics. Two impaired acrocentric chromosomes were detected in the female karyotype. C-banding showed heterochromatic blocks at several chromosomes and an entirely heterochromatic acrocentric chromosome in females that was lacking in the male karyotype. This discovery indicated a heteromorphic sex chromosome system of the ZZ/ZW type. Ag-staining and CMA(3) fluorescence revealed one major chromosome pair bearing the NORs with the presence of additional signals in some metaphases. Both heterochromatic segments associated with Ag-NORs and the W chromosome were positively stained by CMA(3). Considering the present data and previous findings it is hypothesized that the occurrence of ZW sex chromosome system is widespread in the genus Thoracocharax.

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)

Molecular cytogenetic study of heterochromatin in Hisonotus leucofrenatus (Teleostei, Loricariidae, Hypoptopomatinae)

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

Karyotypic diversity in four species of the genus Gymnotus Linnaeus, 1758 (Teleostei, Gymnotiformes, Gymnotidae): physical mapping of ribosomal genes and telomeric sequences

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetic analysis in the incertae sedis species Astyanax altiparanae Garutti and Britzki, 2000 and Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae) from the upper Parana river basin

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