DSpace Coleção: Mestrado em reprodução animal na Amazônia

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

Thu, 01 Jan 2026 00:00:00 GMT

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.

Thu, 01 Jan 2026 00:00:00 GMT

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).

Thu, 19 Mar 2026 00:00:00 GMT

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.

Avaliação do gene do hormônio anti-mulleriano (AMH) em fêmeas bubalinas submetidas à sincronização de cio, na Amazônia.

Tue, 08 Apr 2025 00:00:00 GMT

Título: Avaliação do gene do hormônio anti-mulleriano (AMH) em fêmeas bubalinas submetidas à sincronização de cio, na Amazônia. Autor(es): FIGUEIREDO, Juliana Vasconcelos Abstract: Reproductive management in buffaloes is essential for the productivity of the Brazilian agricultural sector, especially in the Amazon region. The anti-Müllerian hormone (AMH) is considered a significant marker of ovarian reserve, and understanding the relationship between genotypes and fertility is important for sustainable livestock production. Thus, the present study aimed to investigate the presence of polymorphism in exon 5 of the AMH gene and its associations with the reproductive efficiency of female buffaloes. The research was conducted with 54 multiparous Murrah breed buffaloes, located on a farm in the municipality of Bujaru, Pará. The females were subjected to a fixed-time artificial insemination (FTAI) protocol. Initially, all females selected for the study were non-pregnant. Only after estrus synchronization and pregnancy diagnosis were the animals subdivided into two groups: pregnant and non-pregnant. Blood collection for DNA extraction and ultrasonographic evaluation of the ovaries were performed on day 11 of the protocol.Following collection, DNA extraction was carried out, and the AMH gene was amplified using the PCR technique; subsequently, the products were purified for sequencing. Statistical analyses were performed using SAS software, with a significance level of 0.05, and ANOVA methods were employed to compare the means of reproductive variables.The results showed the absence of polymorphisms in exon 5 of the AMH gene in buffaloes. However, a significant difference was observed in antral follicle count (AFC) via transrectal ultrasonography between pregnant and non-pregnant buffaloes (p = 0.02). Additionally, variables such as ovarian volume (V) and dominant follicle (DF) did not present significant differences, suggesting these factors may play a less prominent role in reproductive performance. These findings demonstrate the conservation of the AMH gene and highlight the presence of antral follicles as predictors of reproductive efficiency in this study. The research underscores the need for future studies in other regions of the AMH gene and the association with genetic factors that may influence fertility. Finally, the results presented contribute to the development of more effective future strategies in assisted reproduction, aiming to increase productive efficiency in buffalo herds in the Amazon region.