Dinâmica populacional de Characidium lauroi e C. alipioi (Teleostei, Crenuchidae) na microbacia do Ribeirão Grande, serra da Mantiqueira Oriental, Estado de São Paulo

In low-order streams, the high and variable water flow rates offer both advantages and disadvantages to the life cycle of fishes. Even closely related species living in similar habitats can show differences in life history patterns. Based on oocyte-size distributions, C. lauroi was classified into the fractional spawning type, and C. alipioi into the total spawning type. The absolute fecundity of C. lauroi ranged from 1,313 to 2,925 oocytes; in C. alipioi the absolute fecundity ranged from 2,213 to 25,550 oocytes. The nonparametric Spearman correlation test showed statistical significance between the gonadosomatic index and fecundity for both species. The growth parameters, natural mortality rate and survival rate for females of C. lauroi were: K = 0.68 yr -1, L ∞ = 8.7 cm, t max = 4.4 years, M= 1.62 yr -1, S = 19.79%, and for males: K = 0.78 yr -1, L ∞ = 6.9 cm, t max = 3.8 years, M = 1.89 yr -1, S = 15.11%. The growth parameters, natural mortality rate and survival rate for females of C. alipioi were: K = 0.90 yr -1, L ∞ = 12.2 cm, t max = 3.3 years, M = 1.81 yr -1, S = 16.37%, and for males: K = 0.76 yr -1, L ∞ = 10.1 cm, t max = 3.9 years, M = 1.71 yr -1, S = 18.10%.

Karyotypic diversity and evolutionary trends in the neotropical catfish genus Hypostomus lacépède, 1803 (Teleostei, Siluriformes, Loricariidae)

The family Loricariidae with 813 nominal species is one of the largest fish families of the world. Hypostominae, its more complex subfamily, was recently divided into five tribes. The tribe Hypostomini is composed of a single genus, Hypostomus Lacépède, 1803, which exhibits the largest karyotypic diversity in the family Loricariidae. With the main objective of contributing to a better understanding of the relationship and the patterns of evolution among the karyotypes of Hypostomus species, cytogenetic studies were conducted in six species of the genus from Brazil and Venezuela. The results show a great chromosome variety with diploid numbers ranging from 2n=68 to 2n=76, with a clear predominance of acrocentric chromosomes. The Ag-NORs are located in terminal position in all species analyzed. Three species have single Ag-NORs (Hypostomus albopunctatus (Regan, 1908), H. prope plecostomus (Linnaeus, 1758), and H. prope paulinus (Ihering, 1905)) and three have multiple Ag-NORs (H. ancistroides (Ihering, 1911), H. prope iheringi (Regan, 1908), and H. strigaticeps (Regan, 1908)). In the process of karyotype evolution of the group, the main type of chromosome rearrangements was possibly centric fissions, which may have been facilitated by the putative tetraploid origin of Hypostomus species. The relationship between the karyotype changes and the evolution in the genus is discussed. © Anderson Luis Alves et al.

Mapping five repetitive DNA classes in sympatric species of Hypostomus (Teleostei: Siluriformes: Loricariidae): analysis of chromosomal variability

Fish belonging to the genus Hypostomus are known for exhibiting a striking diversity in its karyotype structure, however the knowledge concerning the distribution patterns of heterochromatin and location of repetitive DNA sequences in the karyotypes is still limited. Aiming a better understanding of the chromosomal organization in this group, we analyzed three sympatric species of Hypostomus collected in the Hortelã stream, a component of the Paranapanema River basin, Botucatu/SP/Brazil. The analyses involved the cytogenetic characterization and chromosomal mapping of repetitive sequences and intra/interspecific comparisons using sequences of the cytochrome C oxidase subunit I. The results revealed that H. ancistroides presents a karyotype with 2n = 68 chromosomes, H. strigaticeps 2n = 72 chromosomes, and H. nigromaculatus 2n = 76 chromosomes. In addition to differences found in the diploid number, it was also observed variations in karyotypic formulae, amount of constitutive heterochromatin, and location of nucleolus organizer regions. The cytogenetic mapping of 5S and 18S rDNA, as well as of the H3 histone gene, disclosed a differential dispersion process among the three species. In some cases the Rex1 transposable element showed to be co-located with 5S rDNA sites. The molecular analyses support the cytogenetic data and represent an additional tool for the characterization of the analyzed species. The results evidenced that chromosomal variations are not restricted to differences in diploid number or karyotypic macrostructure in the genus Hypostomus, indicating that events such as transposition of heterochromatin and rDNA segments may participate in the differentiation process occurred in these species. © 2013 Springer Science+Business Media Dordrecht.

Hisonotus bocaiuva, a new species from the rio São Francisco basin, Brazil (Teleostei: Loricariidae)

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

Hemiodus iratapuru, a new species of Hemiodontidae from the Rio Jari, Amazon Basin, Brazil (Teleostei, Characiformes)

Hemiodus iratapuru, a new species of the Hemiodontidae from the Rio Iratapuru, a left bank tributary of the Rio Jari, Amazon Basin, Brazil, is described. The new species is diagnosed from other species of Hemiodus by modifications in the ectopterygoid, tooth form, scale counts, dorsal-fin form and colour pattern. The new species is proposed to be related to the Hemiodus quadrimaculatus species group. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

Comparative analysis of sex chromosomes in Leporinus species (Teleostei, Characiformes) using chromosome painting

Background: The Leporinus genus, belonging to the Anostomidae family, is an interesting model for studies of sex chromosome evolution in fish, particularly because of the presence of heteromorphic sex chromosomes only in some species of the genus. In this study we used W chromosome-derived probes in a series of cross species chromosome painting experiments to try to understand events of sex chromosome evolution in this family.Results: W chromosome painting probes from Leporinus elongatus, L. macrocephalus and L. obtusidens were hybridized to each others chromosomes. The results showed signals along their W chromosomes and the use of L. elongatus W probe against L. macrocephalus and L. obtusidens also showed signals over the Z chromosome. No signals were observed when the later aforementioned probe was used in hybridization procedures against other four Anostomidae species without sex chromosomes.Conclusions: Our results demonstrate a common origin of sex chromosomes in L. elongatus, L. macrocephalus and L. obtusidens but suggest that the L. elongatus chromosome system is at a different evolutionary stage. The absence of signals in the species without differentiated sex chromosomes does not exclude the possibility of cryptic sex chromosomes, but they must contain other Leporinus W sequences than those described here. © 2013 Parise-Maltempi et al.; licensee BioMed Central Ltd.

Chromosomal organization of repetitive DNA sequences in Astyanax bockmanni (Teleostei, Characiformes): dispersive location, association and co-localization in the genome

Repetitive DNA sequences constitute a great portion of the genome of eukaryotes and are considered key components to comprehend evolutionary mechanisms and karyotypic differentiation. Aiming to contribute to the knowledge of chromosome structure and organization of some repetitive DNA classes in the fish genome, chromosomes of two allopatric populations of Astyanax bockmanni were analyzed using classic cytogenetics techniques and fluorescent in situ hybridization, with probes for ribosomal DNA sequences, histone DNA and transposable elements. These Astyanax populations showed the same diploid number (2n = 50), however with differences in chromosome morphology, distribution of constitutive heterochromatin, and location of 18S rDNA and retroelement Rex3 sites. In contrast, sites for 5S rDNA and H1, H3 and H4 histones showed to be co-located and highly conserved. Our results indicate that dispersion and variability of 18S rDNA and heterochromatin sites are not associated with macro rearrangements in the chromosome structure of these populations. Similarly, distinct evolutionary mechanisms would act upon histone genes and 5S rDNA, contributing to chromosomal association and co-location of these sequences. Data obtained indicate that distinct mechanisms drive the spreading of repetitive DNAs in the genome of A. bockmanni. Also, mobile elements may account for the polymorphism of the major rDNA sites and heterochromatin in this genus. © 2013 Springer Science+Business Media Dordrecht.

Henneguya nagelii n. sp. (Myxozoa: Myxobolidae) in Cyphocharax nagelii (Steindachner, 1881) (Teleostei: Characiformes: Curimatidae) from the Peixe's River, São Paulo State, Brazil

A new species of Myxosporea, Henneguya nagelii n. sp., is described parasitizing the gills of Cyphocharax nagelii collected from Peixe's River, São Paulo State, Brazil. Among the fish examined, 16.7 % had gills parasitized by myxosporeans. The plasmodia were white, round, or oval and measured 150-250 μm. The mature spores were fusiform and had smooth wall. The spores measurements were the following: total length, 34.5 ± 4.2 (26.4-39.9) μm; body length, 12.0 ± 0.5 (11.2-11.9) μm; body width, 4.9 ± 0.3 (4.4-5.5) μm; and caudal process length, 22.4 ± 4.0 (14.7-27.3) μm. The polar capsules were elongated and of unequal size, with lengths of 4.9 ± 0.4 (4.0-5.9) μm and 5.2 ± 0.4 (4.6-6.0) μm for the longest and shortest axes, respectively. Capsule width was 1.8 ± 0.2 (1.5-2.2) μm. Each capsule contained a polar filament with six to eight turns. There was no mucous envelope or iodinophilous vacuole. Morphometric differences between this parasite and other species of the genus Henneguya indicated that the parasite observed in C. nagelii is a new species. This is the first species of Myxosporea described in Peixe's River. © 2013 Springer-Verlag Berlin Heidelberg.

Involvement of pituitary gonadotropins, gonadal steroids and breeding season in sex change of protogynous dusky grouper, Epinephelus marginatus (Teleostei: Serranidae), induced by a non-steroidal aromatase inhibitor

Two experiments were performed using the aromatase inhibitor (AI) letrozole (100mg/kg) to promote sex change, from female-to-male, in protogynous dusky grouper. One experiment was performed during the breeding season (spring) and the other at the end of the breeding season (summer). During the spring, AI promoted sex change after 9weeks and the sperm produced was able to fertilize grouper oocytes. During the summer, the sex change was incomplete; intersex individuals were present and sperm was not released by any of the animals. Sex changed gonads had a lamellar architecture; cysts of spermatocytes and spermatozoa in the lumen of the germinal compartment. In the spring, after 4weeks, 11ketotestosterone (11KT) levels were higher in the AI than in control fish, and after 9weeks, coincident with semen release, testosterone levels increased in the AI group, while 11KT returned to the initial levels. Estradiol (E2) levels remained unchanged during the experimental period. Instead of decreasing throughout the period, as in control group, 17 α-OH progesterone levels did not change in the AI-treated fish, resulting in higher values after 9weeks when compared with control fish. fshβ and lhβ gene expression in the AI animals were lower compared with control fish after 9weeks. The use of AI was effective to obtain functional males during the breeding season. The increase in androgens, modulated by gonadotropins, triggered the sex change, enabling the development of male germ cells, whereas a decrease in E2 levels was not required to change sex in dusky grouper. © 2013 Elsevier Inc.

Desenvolvimento embrionário e larval de Brycon gouldingi (Teleostei, Characidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ciclo reprodutivo e análise ultraestrutural da espermatogênese de Cichla kelberi (TeLeostei: Perciformes: Cichlidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variações bioquímicas em Pterygoplichthys anisitsi e Oreochromis niloticus (Pisces: Teleostei) após exposição a cloreto de mercúrio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biologia de Knodus moenkhausii (Teleostei, Characidade) em riachos do Alto Paraná: alimentação, ocorrência e reprodução

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

Relações filogenéticas e história evolutiva do gênero Astyanax (Teleostei: Characidade), com base em caracteres moleculares

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Desenvolvimento gonadal inicial e reversão sexual em Astyanax altiparanae (Teleostei, characidae)

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC