ABSTRACT
Austrodiplostomum compactum and Ithyoclinostomum dimorphum are two trematodes commonly found in trahira, but these parasites were never reported in trahiras from Rio Doce. Thus, the aim of this study is to describe the occurrence of A. compactum and I. dimorphum metacercariae in trahira from the middle course of the Rio Doce and to record the presence of eggs in I. dimorphum metacercariae. The parasites were identified and analyzed using methods described previously. There were found 10 A. compactum metacercariae in the aqueous humor of eyes in four of the trahiras and 12 I. dimorphum metacercariae encysted in the peritoneal cavity in five of the trahiras. Maceration of the I. dimorphum metacercariae revealed the presence of eggs. These results demonstrate the broad distribution of these parasites and the first report of these parasites in trahira from Rio Doce.
Austrodiplostomum compactum e Ithyoclinostomum dimorphum são dois trematódeos comumente encontrados em traíras, contudo, esses parasitas nunca foram relatados em traíras do Rio Doce. O objetivo do estudo é descrever a ocorrência de metacercárias de A. compactum e I. dimorphum, e presença de ovos em metacercárias de I. dimorphum em traíras provenientes do médio curso do Rio Doce. Os parasitas foram analisados e identificados utilizando métodos descritos anteriormente. Foram encontradas 10 metacercárias de A. compactum no humor aquoso dos olhos em quatro traíras e 12 metacercárias de I. dimorphum encistadas na cavidade peritoneal de cinco traíras. A maceração de metacercárias de I. dimorphum revelou a presença de ovos nestes parasitos. Esses resultados demonstram a ampla distribuição desses trematódeos e este é o primeiro relato destes parasitos em traíra do Rio Doce.
Subject(s)
Animals , Erythrinus , Trematoda , ParasitesABSTRACT
The sedentary, predatory characin Hoplias malabaricus has one of the widest distributions of freshwater fishes in South America and is characterized by seven karyomorphs (A-G) that occur in sympatric and allopatric populations. Karyotypical patterns of variation in wild populations have been interpreted as evidence of multiple lineages within this nominal species, a possibility that may limit the validity of experimental data for particular karyomorphs. This study used the phylogeographic and genealogical concordance between cytogenetic (N = 49) and molecular (mitochondrial DNA) (N = 73) data on 17 samples, collected in 12 basins from south-eastern and north-eastern Brazil, to assess the systematic value of cytogenetic data. Cytogenetic patterns show a sex chromosome system in the 2n = 40F karyomorph. Molecular and cytogenetic data indicate a long, independent evolutionary history of karyomorphs and a coastal origin of continental populations in south-eastern Brazil. The lack of fit with molecular clock expectations of divergence between groups is likely to be due to strong demographic fluctuations during the evolution of this species complex. The results indicate that karyotypical identification provides a reliable baseline for placing experimental studies on Hoplias spp. in a phylogenetic context.
Subject(s)
Fishes/genetics , Karyotyping , Phylogeography , Animals , Brazil , DNA, Mitochondrial/genetics , Evolution, Molecular , Fishes/classification , Genetics, Population , Phylogeny , Sequence Analysis, DNA , Sex Chromosomes/geneticsABSTRACT
Adaptations of the nucleolar organizer regions (NOR) banding technique using precipitation of silver salts significantly improved the NOR characterization of some species of hymenopterans and one coleopteran. The bee Melipona marginata (2n = 18) showed one metacentric pair of chromosomes with a NOR in the pericentromeric position. The parasitic wasp Mellitobia australica (2n = 12) also showed one metacentric pair with a strongly Ag-positive NOR. The male lady-beetle Cycloneda sanguinea (2n = 18 + Xy(p)) displayed a NOR on a pair of acrocentric autosomes. In the male Euglossa sp. (a haplodiploid species) (n = 21) the NOR were multiple, and occurred in five chromosomes. In the bee Plebeia sp. 1 (2n = 34) the NOR seemed restricted to one of the homologues of a metacentric pair. The systematic advances brought out by using this technique in the context of current theories of karyotypic evolution of these taxa are described and discussed.
Subject(s)
Chromosomes/ultrastructure , Coleoptera/cytology , Hymenoptera/cytology , Nucleolus Organizer Region/ultrastructure , Silver Staining/methods , Animals , Cytogenetics , Insecta , MaleABSTRACT
Hoplias malabaricus, a widely distributed neotropical freshwater fish, shows a conspicuous karyotypic diversification. An overview of this diversity is presented here comprising several Brazilian populations, and some others from Argentina, Uruguay and Surinam. Seven general cytotypes are clearly identified on the basis of their diploid number (2n = 39 to 2n = 42), chromosomal morphology and sex chromosome systems, which can be clustered into two major karyotypic groups. This clustering suggests that karyotype structure would be more informative than the diploid number regarding cytotype relationships in this fish group. While some cytotypes show a wide geographical distribution, some others appear to be endemic to specific hydrographic basins. Sympatric cytotypes can occur without detection of hybrid forms; this situation points to a lack of gene flow, a fact that is also reinforced by studies with genomic markers. The karyotypic data support the view that the nominal taxon H. malabaricus corresponds to a species complex comprising distinct evolutionary units, each with well-established chromosomal differences.
Subject(s)
Ecosystem , Fishes/classification , Fishes/genetics , Animals , Cytogenetic Analysis , Diploidy , Female , Karyotyping , Male , South AmericaABSTRACT
Karyotypic analyses of 366 specimens of the solitary wasp Trypoxylon (Trypargilum) albitarse collected from ten populations in the municipalities of Viçosa and Porto Firme (Minas Gerais, Southeastern Brazil), revealed the presence of two morphological types of supernumerary (B) chromosomes. C-banding and fluorochrome banding suggest that the B chromosomes of T. albitarse may have originated from heterochromatin breaks within the standard (A) chromosome complement.
