Abstract Gymnotus inaequilabiatus has been the subject of few studies concerning organization its macro- and micro-karyotypic structures. This article aims to enhance existing cytogenetic data for G. from upper Paraná River basin by documenting karyotype other chromosomal characteristics, including ribosomal DNA (rDNA) retroelements Rex-1 Rex-3, which have yet be described this genus. The modal diploid number 2n = 54, distributed in 34m + 18sm +2a both sexes, was observed. Single nucleolar...

Rineloricaria is the most species-rich genus of Loricariinae (armored catfish) with 65 valid species. However, karyotype structure known only for eight species in this group. This study provides cytogenetic data lanceolata collected from upper Paraguay basin (Mato Grosso do Sul). The specimens revealed extensive chromosomal polymorphism constituting 10 karyotypes, which differed diploid number (48 to 45 chromosomes) and fundamental (FN) between 52 55. Three types chromosome variants were...

Only one species of armored catfish, Ancistrus cirrhosus Valenciennes 1836, has been historically described in the basin Paraná River, from Misiones (Argentina). However, ample variation found morphology and coloration populations sampled tributaries Brazilian state makes it difficult to establish real taxonomic status evolutionary history specimens, suggesting that is not only this basin. By combining data on mitochondrial DNA (COI gene) chromosomal markers different populations, totaling...

Gymnotiformes a monophyletic group of fish endemic to the Neotropics, represent an important component freshwater ichthyofauna that presents relevant taxonomic problems. Thus, in view morphological complexity involving Eigenmannia (Gymnotiformes) species, this study aimed characterize aff. desantanai upper Paraguay River basin through cytogenetic and molecular analyses, help correct identification delimitation species. This reports multiple sex system type ZW1W2/ZZ, with 2n = 31 for females...

Ancistrus Kner, 1854 is a diverse catfish genus, currently comprising 66 valid species, but karyotype data were recorded for 33 although only ten have their taxonomic status defined. Considerable diversity has been found within this with 2n varying from 34 to 54 and structural variability including heteromorphic sex chromosomes. In many cases, uncertainty on the of study populations hampers reliable interpretation complex chromosomal evolutionary history group. This aims present first...

The repetitive DNAs are the expressive substrate to genomic evolution and directly related chromosomal diversification in eukaryote, including fishes. Ancistrus is an interesting group for studies about interplay between DNA karyotype evolution, given its extensive variation. In this study, we aimed understand evolutionary dynamics genome of distinct populations Paraná basin contribution three classes sequences. Nucleotide sequence was isolated, characterized nonlong terminal repeat...

Abstract Drugs are emerging contaminants that provide concern when it comes to the adverse effects they can cause on organisms not target of therapeutic action. Because water treatment methods do entirely remove them, found in worrying concentrations aquatic environment. Antidiabetic Metformin has been environment worldwide, and studies show a potential endocrine disrupting effect. However, more research is needed regarding its impact bioindicator organisms, such as fish. This work aimed...

is one of the most specious fish groups in Neotropical region, with many cryptic species, which represents a challenge for correct identification through traditional taxonomic methods.

In the present study, we analyzed individuals of Hypostomus soniae (Loricariidae) collected from Teles Pires River, southern Amazon basin, Brazil. has a diploid chromosome number 2n = 64 and karyotype composed 12 metacentric (m), 22 submetacentric (sm), 14 subtelocentric (st), 16 acrocentric (a) chromosomes, with structural difference between chromosomes two sexes: presence block heterochromatin in sm pair No. 26, which appears to represent putative initial stage differentiation an XX/XY sex...

A cytogenetic analysis based on the integration of a number different chromosomal methodologies, including chromosome microdissection was carried out to characterize chromosomally polymorphic Hypostomusregani population from Paraguay River basin, state Mato Grosso do Sul in Brazil. All specimens had 2n=72 (FN=116) but two distinct karyotype formulas: karyomorph (12m+14sm+18s+28a) and B (13m+14sm+17st+28a). Karyomorph differed only for pair 19 that consisted subtelocentrics large metacentric...

One of the main issues in processing sector tambaqui Colossoma macropomum is removal and/or fragmentation intermuscular bones (IBs), which negatively impacts its production chain. In this sense, we quantitatively examined IB variation farmed (n = 127) by comparing direct anatomical dissection with high-resolution X-ray imaging method. The number IBs from on left side fish (27.3 ± 5.70 bones) was comparable to that analysis (26.9 6.03 (p > 0.05). addition, 76% deviation between two studied...

The herbicide Dormex®, a solution of hydrogen cyanamide, is growth regulator capable breaking the dormancy fruit plants, and commonly applied in agriculture. However, biological effects this product on non-target organisms are unknown. present study investigated response Astyanax lacustris (Lütken, 1875) specimens exposed to Dormex® using chromosome aberration test, mitotic index, histological analysis gills. Forty were obtained from local breeding facility divided into 10 groups (nine...

In fish species, heterochromatinization is one process that could trigger sex chromosome differentiation. The present article describes a nascent XX/XY system evidenced by heterochromatin accumulation and microsatellite (GATA)

Abstract Hypostomus is distributed by Central and South America basins, with diverse species taxonomic conflicts. This way, the integration of auxiliary techniques contributes to understanding systematics phylogeny group. Thus, this study aimed investigate cochliodon H. boulengeri from Onça stream (Paraguai River basin) allozyme cytogenetic techniques. showed a diploid number 68 chromosomes (14m+14sm+18st+22a), multiple NOR revealed Ag-NOR 18S rDNA FISH, polymorphism heterochromatin in...

ABSTRACT Moenkhausia is a highly specious genus among the Characidae, composed of 96 valid species. Only twelve species have known karyotype. Thus, here are presented first cytogenetic data two allopatric populations bonita and one M. forestii, both belonging to upper Paraná River basin (PR) with discussion on evolutionary cytotaxonomic aspects genus. The 2n = 50 chromosomes but different karyotype formulas occurrence 1-2 B chromosomes. These elements small metacentrics in acrocentrics...

Abstract The antidiabetic drug metformin is widely prescribed and found in high concentrations the environment around world, raising concern about potential impacts on aquatic life. Fish have a fundamental ecological role are considered excellent experimental models ecotoxicology studies. Gills of fish extremely sensitive to even minor chemical or physical changes surroundings, mainly because large surface respiratory epithelium perfusion rate, which both facilitate entry pollutants into...