DSpace Communidade: Programa de Pós-Graduação em Reprodução Animal na Amazônia

Biologia reprodutiva do Peixe Voador Hemiodus unimaculatus na Vila Tauiry, área de influência da Usina Hidrelétrica de Tucuruí - PA

2026-07-23T15:31:52Z

Título: Biologia reprodutiva do Peixe Voador Hemiodus unimaculatus na Vila Tauiry, área de influência da Usina Hidrelétrica de Tucuruí - PA Autor(es): SILVA, Maria Clara Rosa Abstract: This study compiles information on the ecological and reproductive aspects of the flying fish Hemiodus unimaculatus in the area influenced by the Tucuruí Hydroelectric Power Plant (PA, Brazil). The literature review showed that this species, a member of the family Hemiodontidae, has a wide distribution throughout the Amazon basin and exhibits remarkable trophic plasticity. Previous studies indicate that, prior to river impoundment, its diet was predominantly detritivorous and periphytic. After the formation of the reservoir, it began to display more diversified feeding habits, including omnivorous strategies. Additionally, changes in the average body size of individuals and a reduction in relative frequency in sampling surveys were observed, suggesting significant effects of damming on the local population. From a reproductive perspective, the species reaches first sexual maturation between 11 and 15 cm and exhibits an extended reproductive period from October to April, associated with the seasonality of the Amazonian flood pulse. A predominance of females has been recorded, a strategy that may maximize reproductive success but raises concerns regarding the potential reduction of genetic diversity. In Chapter 2, the histological analysis of spermatogenesis revealed testes with an anastomosed tubular pattern, typical of Characiformes, and cystic spermatogenesis characterized by synchronized development of germ cells. Four types of spermatogonia, different meiotic stages, three types of spermatids, and type III spermiogenesis were described, evidencing a continuous process of gamete production. The spermatozoa exhibited a rounded head and a long flagellum, a conformation adapted to external fertilization in aquatic environments. These findings reinforce the importance of understanding the reproductive biology and ecology of the species, providing essential support for management and conservation strategies in the face of pressures from impounded environments and hydrological modifications imposed by Amazonian dams.

Ontogenia inicial do Tetra Olho-de-Fogo amazônico Moenkhausia oligolepis (Characiformes: characidae)

2026-05-22T20:22:51Z

Título: Ontogenia inicial do Tetra Olho-de-Fogo amazônico Moenkhausia oligolepis (Characiformes: characidae) Autor(es): COIMBRA, Vanessa Conceição Abstract: This study describes, for the first time, the morphophysiological development, allometric growth patterns, and the main early ontogenetic events of Moenkhausia oligolepis, a species of ecological and ornamental importance in the Amazon region. Hatching occurred 16 hours after fertilization under a mean temperature of 25.36 ± 0.64°C and pH of 7.28 ± 1.11. From hatching onward, larvae were sampled at regular intervals (0-6 h post-hatching with collections every 2 h; 6-22 h every 4 h; and subsequently daily) for morphological, morphometric, meristic, and histological analyses. Larval development extended from the yolk-sac stage to post-flexion (0-30 days after hatching – DAH), with a well-defined sequence of events: mouth opening and the onset of exogenous feeding at 3 DAH, observation of cannibalistic behavior at 4 DAH, notochord flexion at 15 DAH (mean SL = 6.33 ± 0.56 mm), and the larva–juvenile transition at 30 DAH with the development of fin rays and the appearance of scales. Allometric analyses revealed positive cephalic growth in relation to standard length (b = 1.389 for HL/SL), indicating prioritization of the development of structures associated with feeding and sensory perception. Structures such as notochord length and pre-anal distance showed growth close to isometry, whereas body depth exhibited negative allometry. Histological analysis demonstrated the progressive differentiation of the digestive tract, with the presence of the buccopharyngeal cavity, esophagus, segmented intestine (anterior, middle, and posterior), and mucous cells at 3 DAH. Cytoplasmic vacuolization in hepatocytes was observed from 23 DAH onward, associated with the presence of digested material in the intestinal lumen. Secondary gill lamellae exhibited evident buds at 4 DAH, and the swim bladder showed division into two chambers by the end of the flexion stage (22 DAH). Gonadal evaluation indicated undifferentiated gonads up to 50 DAH and ovarian differentiation at 60 DAH, characterized by the presence of primary meiotic oocytes; testicular differentiation was not observed during the analyzed period. Based on the observed morphological and ontogenetic characteristics, four larval stages were described: yolk-sac, pre-flexion, flexion, and post-flexion. The results expand the knowledge of the early biology of this species, providing relevant information for taxonomic, ecological, and conservation studies, as well as for improving management strategies and larviculture of native ornamental fishes.

Utilização de Plasma Rico em Plaquetas no Meio de Fertilização in vitro de Oócitos Bovinos.

2026-04-13T14:52:29Z

Título: Utilização de Plasma Rico em Plaquetas no Meio de Fertilização in vitro de Oócitos Bovinos. Autor(es): LIMA, Patrícia de Cássia da Silva Abstract: Culture media represent the physicochemical and utritional support necessary for maintaining the survival and promoting the development of gametes and embryos in vitro. Aiming to replicate a microenvironment closer to in vivo conditions, new formulations and the addition of various substances have been tested. Platelet-rich plasma (PRP) contains serotonin, adhesion molecules, growth factors (FGF, TGFβ, PDGF, IGF, and EGF), as well as cytokines that may positively modulate the fertilization microenvironment and favor embryonic development. Due to its bioactive properties, this study investigated the effect of adding PRP to the fertilization medium on in vitro bovine embryo production. Bovine cumulus–oocyte complexes (COCs) obtained from a local slaughterhouse were fertilized in the presence of 2.5%, 5%, and 10% PRP. The gene expression of OCT4, IFNT, HSP70, SOD2, and GLUT1 was evaluated only in the Control, 2.5%, and 5% groups by RT-PCR, with three replicates consisting of pools of five embryos each, using the 2ΔΔCT method. Cleavage (D2) and blastocyst (D7) rates and gene expression data were analyzed by ANOVA (p<0.05). Regarding cleavage and blastocyst formation rates, differences were observed between the Control (91.9 ± 3.9; 44.6 ± 9.0), 2.5% (87.9 ± 6.4; 39.0 ± 14.1), and 5% (85.8 ± 7.4; 35.1 ± 11.4) groups compared with the 10% group (61.1 ± 9.9; 17.6 ± 4.9). The OCT4 and IFNT genes were more highly expressed in the 5% group, whereas HSP70 showed greater expression in the 2.5% and 5% groups. The SOD2 gene was less expressed in the 2.5% group, while GLUT1 showed lower expression in the 5% group. Therefore, the effect of PRP was dose-dependent, with the 10% concentration exhibiting a detrimental effect on cleavage and blastocyst formation rates. In contrast, 5% PRP during the fertilization process improved the quality of bovine embryos, as evidenced by the higher expression of genes associated with preimplantation embryonic competence.

Exposição aguda à amônia compromete a reprodução e a viabilidade embrionária do lambari Amazônico Astyanax bimaculatus (Linnaeus, 1758).

2026-03-20T18:31:23Z

Título: Exposição aguda à amônia compromete a reprodução e a viabilidade embrionária do lambari Amazônico Astyanax bimaculatus (Linnaeus, 1758). Autor(es): FERREIRA, Evagno Junior da Silva Abstract: This study evaluated the effects of acute ammonia exposure on the reproduction and embryonic and larval viability of the Amazonian tetra species (Astyanax bimaculatus). Adult breeders were exposed to a sublethal concentration of ammonia (NH₄Cl, 180 mg/L) for 4 hours before artificial reproduction. The results showed a significant reduction in hatching rates (82.3 ± 0.577 (41,2%) vs. 129 ± 1.73 (64,5%) in the control) and an acceleration in hatching time (1005 ± 2.58 vs. 1026 ± 3.65 minutes). Gonadal histology revealed alterations in gametogenesis, with exposed females exhibiting fewer vitellogenic oocytes and a higher number of post-ovulatory follicular complexes, while males presented a larger number of spermatocytes and interstitial tissue, and a reduction in spermatozoa. In both cases, indicating early release of gametes. Morphometric analysis of larvae from exposed breeders indicated delayed growth at 10 days post-hatching, although no morphological abnormalities were observed. These findings demonstrate the impact of ammonia on reproductive success and larval development in fish, emphasizing the importance of strict water quality management in aquaculture to mitigate such effects.