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This study aimed to analyze the influence of different temperatures on the embryonic and larval development of discus fish Symphysodon aequifasciatus and determine the time required for the beginning of exogenous feeding. Eggs and larvae were obtained from natural spawns and distributed in five treatments: 24.0, 26.0, 28.0, 30.0, and 32.0 °C. To assess the developmental stages and embryonic structures, samples were taken at regular intervals and checked under an optical microscope. At the end of the experimental period, statistical analysis was performed, followed by Tukey's test. As a result, it was possible to observe the significant effects of temperature on the variables. It was noted that the temperature accelerated the embryonic and larval development of the discus and also contributed to a reduction in the time between the incubation period and the feeding transition. It was also noted that the incubation of eggs and larvae at a temperature of 24.0 °C can cause damage to embryos, such as malformation of the body as well as anomalies in the circulatory system.

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Primordial germ cells (PGCs) are embryonic pluripotent cells that can differentiate into spermatogonia and oogonia, and therefore, PGCs are a genetic source for germplasm conservation through cryobanking and the generation of germline chimeras. The knowledge of PGC migration routes is essential for transplantation studies. In this work, the mRNA synthesized from the ddx4 3'UTR sequence of Pseudopimelodus mangurus, in fusion with gfp or dsred, was microinjected into zygotes of three neotropical species (P. mangurus, Astyanax altiparanae, and Prochilodus lineatus) for PGC labeling. Visualization of labeled PGCs was achieved by fluorescence microscopy during embryonic development. In addition, ddx4 and dnd1 expressions were evaluated during embryonic development, larvae, and adult tissues of P. mangurus, to validate their use as a PGC marker. As a result, the effective identification of presumptive PGCs was obtained. DsRed-positive PGC of P. mangurus was observed in the hatching stage, GFP-positive PGC of A. altiparanae in the gastrula stage, and GFP-positive PGCs from P. lineatus were identified at the segmentation stage, with representative labeling percentages of 29% and 16% in A. altiparanae and P. lineatus, respectively. The expression of ddx4 and dnd1 of P. mangurus confirmed the specificity of these genes in germ cells. These results point to the functionality of the P. mangurus ddx4 3'UTR sequence as a PGC marker, demonstrating that PGC labeling was more efficient in A. altiparanae and P. lineatus. The procedures used to identify PGCs in P. mangurus consolidate the first step for generating germinal chimeras as a conservation action of P. mangurus.

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Fetal alcohol exposure may lead to a condition known as fetal alcohol spectrum disorder (FASD), which comprises a set of consequences, including cognitive and behavioral impairments. Although zebrafish has been applied as a reliable model for studying FASD, there is no approach to the disorder's ontogeny and population differences. Here, we evaluated the behavioral outcomes of AB, Outbred (OB), and Tübingen (TU) zebrafish populations embryonically exposed to alcohol throughout the development to the adult stage. We exposed 24hpf eggs to 0 %, 0.5 %, or 1.0 % alcohol for 2 h. Fish were let grow and locomotor and anxiety-like behaviors were tested in a novel tank at larval - 6dpf, juvenile - 45dpf, and adult- 90dpf stages. At 6dpf, both AB and OB treated with 1.0 % alcohol showed hyperactivity, while 0.5 % and 1.0 % TU fish exhibited hypolocomotion. At 45dpf, AB and TU fish maintained the larval pattern of locomotion. At the adult stage - 90dpf, both AB and TU populations showed increased locomotor activity and anxiogenic responses, while the OB population did not show altered behavior. Our results show for the first time that zebrafish populations exhibit behavioral differences in response to embryonic alcohol exposure and that it varies along animals' ontogeny. AB fish showed the most consistent behavioral pattern through developmental stages, TU fish showed behavioral changes only in adulthood, and OB population showed high interindividual variability. These data reinforce that different populations of zebrafish are better adapted to translational studies, offering reliable results in contrast to domesticated OB populations obtained from farms, which exhibit more variable genomes.

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Fish populations that reside in completely isolated freshwater ecosystems are rare worldwide. The Vila Velha State Park (VVSP), located in southern Brazil, is recognized for its arenitic formations called sinkholes (furnas), which are completely isolated. Fish populations within, such as those of Psalidodon aff. fasciatus, often develop vertebral malformations due to this isolation from other conspecifics and other species. In this study, we analyzed geometric morphology in digital radiographs to identify congenital deformations of Psalidodon aff. fasciatus in Furna 2 of VVSP. We found many fish with spinal deformities, including wide variation in the number of caudal vertebrae and corporal deformations related to a flattened body and spinal curvature. Females were more affected than males. We also demonstrated that these deformations reflect inbreeding and an absence of gene flow in the population. In conclusion, isolated populations such as fish species in furnas are potential models for evo-devo research.

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Representatives of the Class Ostracoda are widely used as tools in applied paleoecological and biostratigraphical studies in all continents. In the Araripe Basin, located in the northeastern of Brazil, the Romualdo Formation is one of the most studied, not only for the preservation but also for the abundance of its fossils. The ostracod genus Pattersoncypris Bate, 1972 is well-represented in this formation and it is the most abundant, which reinforces the importance of its taxonomic study. In this work, Pattersoncypris minima sp. nov. is described for the Romualdo Formation as a contribution to the knowledge on Brazilian Cretaceous non-marine ostracods. Taphonomic aspects are also presented, considering the complete ontogenetic stages of the material.

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