https://repositorio.ufra.edu.br/jspui/handle/123456789/1173 Mestrado em reprodução animal na Amazônia 2026-09-28T22:12:22Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2910 Título: Ocorrência de mixosporídeos em (Mylossoma duriventre) e possíveis implicações fisiológicas na região de Santarém-PA Autor(es): PACHECO, Acácio Heitor Barros Abstract: Mylossoma duriventre (pacu manteiga) is a species widely distributed in the Amazon Basin, of food and ornamental importance in the Northern region. This study aimed to characterize morphologically, histopathologically, and molecularly the myxosporidia that infect M. duriventre from the Santarém-PA region, evaluating their tissue distribution and possible physiopathological implications. One hundred and twenty specimens acquired at the Santarém-PA Fish Market between December 2024 and October 2025 were used, subjected to necropsy, histopathological, molecular, and phylogenetic analyses, as well as biometrics. The laboratory procedures were performed at the Laboratory of Morpho-molecular Integration and Technologies (LIMT) of the Federal Rural University of the Amazon (UFRA, Belém campus). Parasitized tissues were processed for histology, electron microscopy, and molecular biology. Based on spore morphology, representatives of the genera Sphaeromyxa, Myxobolus, Henneguya, and Ortholinea were identified, distributed in different organs, including the kidney, gills, and urinary bladder. Histological analyses revealed tissue alterations compatible with myxozoan infection, especially in the gills, suggesting potential local functional impairment. However, no parasitic structures or histopathological alterations were observed in the gonads of the analyzed individuals. Therefore, it is recommended that future studies include experimental designs and physiological biomarkers capable of directly and quantitatively evaluating possible interactions between parasitism and the reproductive performance of M. duriventre. 2026-07-15T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2900 Título: Expressão de micrornas em neoplasias mamárias de gatas Autor(es): RAIOL, Letícia da Silva Abstract: Feline mammary neoplasms are frequently malignant and biologically aggressive, supporting the investigation of markers that may improve tumor characterization. This study described clinicopathological features of cats with mammary neoplasia and explored RT-qPCR quantification profiles of selected microRNAs according to contraceptive history. The study sample comprised six cats: four with mammary neoplasia, classified as no-contraceptive (FSA; n=2) or contraceptive-exposed (FCA; n=2), and two classified as controls (FC; n=2). Tumor characterization used the four neoplastic cases, whereas molecular analysis included all six animals with RT-qPCR results. The targets were let-7a, miR-29b, miR-191, miR-200b, miR-200c, miR-484, miR-10b, and miR-21. Tumor-bearing cats had a mean age of 10.75 years, a median age of 10 years, and a range of 8–15 years. Maximum tumor dimension ranged from 2.20 to 7.00 cm; two of four lesions were ulcerated, both in FSA. Histopathological diagnoses included solid carcinoma, grade II/III solid carcinoma, cribriform carcinoma, and grade II tubulopapillary carcinoma. Technical replicates were consolidated at the animal level, and Cq values equal to zero were treated as missing in the calculations. Mean Cq values for FC/FSA/FCA were, respectively: let-7a 19.61/17.57/23.71; miR-29b 25.79/31.65/31.22; miR-191 25.11/28.28/31.18; miR-200b 25.53/26.71/26.70; miR-200c 25.47/30.72/30.54; miR-484 25.87/27.21/28.74; miR-10b 29.77/29.35/29.57; and miR-21 26.03/28.04/28.97. Because a higher Cq corresponds, under comparable conditions, to a lower starting target quantity, the data were interpreted as an exploratory quantification profile. The ΔΔCq method was not applied because a validated endogenous normalizer and assay efficiencies were not available. The findings demonstrate clinical, histological, biological, and technical heterogeneity and support further investigation, but they do not demonstrate differential expression or a causal effect of contraceptive exposure. 2026-09-01T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2893 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. 2026-05-22T00:00:00Z https://repositorio.ufra.edu.br/jspui/handle/riufra/2879 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. 2026-01-01T00:00:00Z