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.

Cytogenetic analysis of five Hypostomus species (Siluriformes, Loricariidae)

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

Cytogenetic Mapping of rRNAs and Histone H3 Genes in 14 Species of Dichotomius ( Coleoptera, Scarabaeidae, Scarabaeinae) Beetles

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

Chromosome differentiation patterns during cichlid fish evolution

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

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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Karyotype differentiation patterns in species of the subfamily Scarabaeinae (Scarabaeidae, Coleoptera)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aspectos moleculares do câncer tiroideano

A proliferação da célula tiroideana normal é regulada por fatores de crescimento estimuladores e inibidores, que atuam através de seus receptores de membrana e, subseqüentemente, através de transdutores citoplasmáticos. Na glândula normal adulta, o equilíbrio de sinais é tal que a proliferação é mínima, enquanto nas neoplasias o crescimento resulta de um distúrbio irreversível desse equilíbrio. Apesar do número de moléculas envolvidas nesse processo ser grande, apenas um pequeno subgrupo parece estar envolvido na tumorigênese tiroideana. Tais proteínas são codificadas pelos genes RAS, RET, NTRK1 e TP53. O transdutor de sinais ras é ativado por mutações em ponto e constitui uma alteração genética precoce nos tumores com histologia folicular. Os genes dos receptores de crescimento RET e NTRK1 são alterados por rearranjos cromossômicos do tipo translocação ou inversão nos carcinomas papilares e por mutações em ponto nos medulares. As alterações do gene TP53, por sua vez, têm sido observadas em carcinomas tiroideanos pobremente diferenciados e na maioria dos indiferenciados, o que sugere sua participação na progressão dessas lesões. O modelo molecular da carcinogênese tiroideana, embora ainda incompleto, pode fornecer instrumentos importantes para o diagnóstico diferencial e para o desenvolvimento de novas técnicas terapêuticas nesse grupo de neoplasias.

First radiation hybrid map of the river buffalo X chromosome (BBUX) and comparison with BTAX

We report the first radiation hybrid map of the river buffalo X chromosome generated from a recently constructed river buffalo (Bubalus bubalis) whole-genome radiation hybrid panel (BBURH5000). This map contains a total of 33 cattle-derived markers, including 10 genes, four ESTs and 19 microsatellites. The markers are distributed in two linkage groups: LG1 contains eight markers spanning 125.6 cR, and LG2 contains 25 markers spanning 366.3 cR. LG1 contains six markers in common with bovine sequence assembly BUILD 3.1. With the exception of BMS2152, the order of these markers on our BBUX map is shuffled when compared to the cow X chromosome (Bos taurus; BTAX). From LG2, two markers (AMELX and BL22) map to a more distal portion of BTAX compared to BBUX. In addition, two pairs of LG2 markers exhibit inversions compared to BTAX (ILSTS017 and ATRX; XBM38 and PPEF1). Alternatively, when compared to the most recent bovine RH map (Bov-Gen 3000rads), BL1098 and BMS2227 from LG1 as well as PLS3 and BMS1820 from LG2 showed inverted positions on the BBUX map. These discrepancies in buffalo and cattle maps may reflect evolutionary divergence of the chromosomes or mapping errors in one of the two species. Although the set of mapped markers does not cover the entire X chromosome, this map is a starting point for the construction of a high-resolution map, which is necessary for characterization of small rearrangements that might have occurred between the Bubalus bubalis and Bos taurus X chromosomes.

Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil

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

Chromosome studies in some Stevia. Cav. (Compositae) species from Southern Brazil

Karyotypes of six species of the genus Stevia from Southern Brazil were studied, utilizing root tip metaphases. All species were diploid with 2n = 22 chromosomes. It was possible to identify each species by chromosome morphology. The basic chromosome number for Brazilian species of Stevia is X = 11. This number is also found in almost all South American species. We suggest that in Stevia there is an evolutionary trend toward chromosomal rearrangement, caused mainly by pericentric inversions. It was found that, in addition to aneuploidy and polyploidy, chromosomal rearrangements are common in the tribe Eupatorieae.

Chromosomal polymorphism in 12 populations of Mikania micrantha (Compositae)

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

Karyotypic patterns of seven species of molossid bats (Molossidae, Chiroptera)

G- and C- banding patterns of seven species of the bat family Molossidae, Eumops glaucinus, E. perotis; Molossops abrasus, M. remminckii, Molossus ater, M. molossus, and Nyctinomops laticaudatus, were identified. Comparisons among the karyotypes of these species showed extensive homologies between E. perotis, M. ater, M. molossus, M. abrasus, and N. laticaudatus, demonstrating inter- and intrageneric conservatism, and a lesser degree of homologies in M. temminckii and glaucinus, reflecting intrageneric variation, Chromosomal variation was due to inversions, Robertsonian rearrangements, translocations, and variations in the location of constitutive heterochromatin and nucleolus organizer regions. The chromosome corresponding to No. 5 in the M. ater karyotype is discussed. We suggest that the Nyctinomops and Molossops karyotypes represent the primitive condition and that Molossus and Eumops have derived karyotypes.

Inversion polymorphism in laboratory strains and natural samples of Drosophila sturtevanti (saltans group, sturtevanti subgroup)

Drosophila sturtevanti (37 strains) showed eighteen inversions, five new and thirteen previously described. Among these strains, 24 were maintained for seven to 21 years under laboratory conditions, eight for less than 1 year, and six were natural samples analysed in the first generation after collection. Flies from natural samples were the most polymorphic in the number of different inversions as well as in the frequency of flies bearing heterozygous inversions. In all cases, chromosome III presented the greatest number of inversions, and most of them occurred in strains from the Amazonian region. The data obtained were consistent with the hypothesis that the inversion variability of a species is proportional to the variability of its habitats.

Genetic relationships between Brazilian species of Molossidae and Phyllostomidae (Chiroptera, Mammalia)

A comparative analysis of G-banded karyotypes was performed for seven species of Chiroptera, representing two families (Phyllostomidae and Molossidae). Despite the differences in diploid and fundamental numbers, extensive homologies between six karyotypes were identified: A . planirostris, P. lineatus, S. lilium, G. soricina, P. hastatus (Phyllostomidae) and M. rufus (Molossidae). Robertsonian rearrangements and pericentric inversions account for the differences between the karyotypes of phyllostomid and molossid species. The homologies and rearrangements observed reinforce the monophiletic origin of phyllostomids and the inclusion of species in different subfamilies. In situ hybridization with genomic DNA revealed considerable conservation of the karyotypes, including C. perspicillata, that did not show G-band homologies with the other species analyzed. For the first time, chromosomal evidence is presented of a common origin for Phyllostomidae and Molossidae.

KARYOTYPE STUDIES IN 22 SPECIES OF PARROTS (PSITTACIFORMES, AVES)

The karyotypes of 12 species of Psittaciformes new to cytology are described: Lorius hypoinochrous, L. lory and Phigys solitarius of the Loriidae, and Amazona autumnallis, Aratinga jandaya, Eclectus roratus, Pionus maximiliani, P. menstruus, P. senilis, P. seniloides, Poicephalus senegalus and Polytelis alexandrae of the Psittacidae. The karyotypes of Amazona ochrocephala, Ara ararauna, Ara macao, Psittacula krameri, Psittacus erithacus and Pyrrhura molinae of the Psittacidae have been previously described. For reasons of comparison the karyotypes of Aratinga aurea, Forpus xanthopterygius, Brotogeris sanctithomae and B. versicolorus of the Psittacidae are also described. These karyotypes are compared to those in the literature and the karyological relationships in the Psittaciformes are briefly discussed. Microchromosome fusions and translocations and pericentric inversions probably are responsible for the heterogeneity of karyotypes in the Psittaciformes.