Genetic evaluation of migratory fish: Implications for conservation and stocking programs.

Fish stocking programs have been implemented to mitigate the blockage of original riverbeds by the construction of hydropower dams, which affects the natural migration of fish populations. However, this method raises concerns regarding the genetic rescue of the original populations of migratory fish species. We investigated the spatial distribution of genetic properties, such as genetic diversity, population structure, and gene flow (migration), of the Neotropical migratory fish Prochilodus costatus in the Três Marias dam in the São Francisco River basin, Brazil, and examined the possible effects of fish stocking programs on P. costatus populations in this region. In total, 1,017 specimens were sampled from 12 natural sites and a fish stocking program, and genotyped for high-throughput sequencing at 8 microsatellite loci. The populations presented low genetic variability, with evidence of inbreeding and the presence of only four genetic pools; three pools were observed throughout the study region, and the fourth was exclusive to one area in the Paraopeba River. Additionally, we identified high unidirectional gene flow between regions, and a preferred migratory route between the Pará River and the upper portion of the São Francisco River. The fish stocking program succeeded in transposing the genetic pools from downstream to upstream of the Três Marias dam, but, regrettably, promoted genetic homogenization in the upper São Francisco River basin. Moreover, the data show the fragility of this species at the genetic level. This monitoring strategy could be a model for the development of conservation and management measures for migratory fish populations that are consumed by humans.

Leporinus elongatus (Characiformes, Anostomidae): complete mtDNA sequence of an economically important fish from the Paraná and La Plata river basins.

Leporinus elongatus is an important commercial fish found in the La Plata and Paraná River basins. Next-generation sequencing was used to sequence the mitochondrial DNA (mtDNA) of L. elongatus. The mtDNA was assembled using the CLC Workbench software v. 9.0 and subsequently aligned to other 10 complete fish mitochondrial sequences to enable phylogenetic analysis using MEGA 7.0. The complete mtDNA molecule had 16,784 bp and its GC content was 43%. The mtDNA structure was similar to that of other vertebrates: two ribosomal RNA, 22 transfer RNA, 13 protein-coding genes, and a D-loop region containing 1115 bp. Phylogenetic analysis yielded a tree with high bootstrap value that was coherent with the current phylogeny proposed for Characiformes.

Description and comparison of two economically important fish species mitogenomes: Prochilodus argenteus and Prochilodus costatus (Characiformes, Prochilodontidae).

Prochilodus spp. are important Brazilian freshwater migratory fishes with substantial economic and ecological importance. Prochilodus argenteus and Prochilodus costatus are morphologically similar and a molecular species delimitation is impaired due to high degree of sequence identity among the available genetic markers. Here, the complete mitochondrial genome of P. argenteus and P. costatus and their comparison to the mitogenome of P. lineatus are described. The three species displayed a similar mtDNA annotation. A phylogenetic analysis was performed with other Characiformes species. The genus Prochilodus was recovered as a monophyletic group, as well as the family Prochilodontidae, both with high bootstrap probability.

Pimelodus maculatus (Siluriformes, Pimelodidae): complete mtDNA sequence of an economically important fish from the São Francisco river basin.

Pimelodus maculatus is an important commercial fish found in the São Francisco and Paraná river basins. NGS was used to sequence the mtDNA of P. maculatus. The mtDNA was annotated and aligned with that of 25 other fish species to enable phylogenetic analysis. The complete mtDNA molecule had 16,561 bp and its GC content was 43.7%; the structure was similar to that of other vertebrates: 2 rRNA, 22 tRNA, 13 protein-coding genes, and a D-loop region containing 914 bp. Phylogenetic analysis yielded a tree with a high bootstrap coefficient that was coherent with the actual phylogeny of the species.

Aspectos clínico-macroscópicos da agenesia pulmonar unilateral esquerda em filhote de jabuti (Chelonoidis carbonarius) / Clinical and macroscopic aspects of left unilateral pulmonary agenesis in tortoise hatchling (Chelonoidis carbonarius)

A agenesia pulmonar é uma anomalia congênita extremamente rara, representada pela falha no desenvolvimento dos brotamentos pulmonares, que geralmente acontece unilateralmente. O objetivo do trabalho foi relatar aspectos clínico-macroscópicos da ocorrência de agenesia pulmonar unilateral em filhote de Chelonoidis carbonarius. Ovos de jabutis (n = 83) foram incubados artificialmente a 29ºC durante 131 dias, sendo que somente 10 eclodiram. No momento da eclosão, todos os filhotes apresentavam aspecto morfológico normal. Os filhotes foram alimentados diariamente com frutas e verduras até completarem aproximadamente dois meses de idade, quando foram eutanasiados. Durante este período, observou-se que um dos filhotes apresentou como sinais clínicos respiração ofegante e pela boca, dificuldade em se alimentar e pouco deslocamento dentro da caixa, ficando isolado dos demais filhotes. À necropsia, este apresentou ausência do pulmão esquerdo, baixo desenvolvimento de órgãos e dilatação cardíaca. O caso traz como relevância a ocorrência da agenesia pulmonar unilateral à esquerda, sem associação com outras malformações.

Pulmonary agenesis is an extremely rare congenital anomaly, represented by the failure in the development of lung buds, which usually occurs unilaterally. The aim of study is present a report of clinical and macroscopical aspects and consequences for body development in the event of unilateral lung agenesis in tortoise's hatchlings (Chelonoidis carbonarius). The eggs of tortoises were incubated artificially at 29 °C for 131 days. Eighty-three eggs were incubated and only 10 hatched. At hatching, all hatchlings had presented normal morphological appearance. The hatchlings were fed daily with fruits and vegetables for two months, when they were euthanized. We observed a case in which the tortoise showed signs of pulmonary agenesis of the left side, without association with other malformations. Clinical signs included wheezing, breathing through the mouth, difficulty in feeding and little movement within the box. At necropsy, we observed the absence of the left lung, reduced size of viscera and cardiac dilatation. The case brings relevance to the occurrence of unilateral lung agenesis at left in tortoise's hatchling, with description of the clinical signs and macroscopic findings during necropsy.