Bartira Guerra-Santos

Parâmetros hematológicos e alterações histopatológicas em bijupirá (Rachycentron canadum Linnaeus, 1766) com amyloodiniose

O objetivo do trabalho foi descrever os parâmetros hematologicos e as alteracoes histopatologicas em bijupiras infectados por Amyloodinium ocellatum. Um grupo de 27 peixes foi anestesiado para coleta de amostras de sangue e eutanasiados para coleta de muco e fragmentos de tecido cutâneo e branquial. Foram avaliadas a prevalencia e a intensidade parasitaria da infeccao, assim como os valores de parâmetros hematologicos e alteracoes histopatologicas. A prevalencia parasitaria nas brânquias foi de 100% e no muco foi de 80,8% e as intensidades parasitarias medias foram de 683,5 nas brânquias, e 67,1 no muco cutâneo. Os valores medios dos parâmetros hematologicos foram: eritrocitos 4,3x106µL; VG 26%; VGM 64,2fL; proteina plasmatica 5,8mg/dL; trombocitos 5,2 x103/µL e leucocitos 3,6 x103/µL. Alem disso, foram verificadas hiperplasia do epitelio respiratorio acompanhada de fusao lamelar, descolamento do epitelio, dilatacao do seio venoso, formacao de aneurisma, ruptura do epitelio lamelar, hemorragia, necrose, reacao inflamatoria linfocitica. O parasito foi observado nas lamelas branquiais, o VMA variou do grau discreto ao severo e o IAH foi de 76,8. A pesquisa assume importância por se tratar dos primeiros estudos em Rachycentron canadum, um peixe que se destaca com potencial ao cultivo.

Synchronization to light and mealtime of daily rhythms of locomotor activity, plasma glucose and digestive enzymes in the Nile tilapia (Oreochromis niloticus)

The light-dark cycle and feeding can be the most important factors acting as synchronizers of biological rhythms. In this research we aimed to evaluate synchronization to feeding schedule of daily rhythms of locomotor activity and digestive enzymes of tilapia. For that purpose, 120 tilapias (65.0±0.6g) were distributed in 12 tanks (10 fish per tank) and divided into two groups. One group was fed once a day at 11:00h (zeitgeber time, ZT6) (ML group) and the other group was fed at 23:00h (ZT18) (MD group). The fish were anesthetized to collect samples of blood, stomach and midgut at 4-hour intervals over a period of 24h. Fish fed at ML showed a diurnal locomotor activity (74% of the total daily activity occurring during the light phase) and synchronization to the feeding schedule, as this group showed anticipation to the feeding time. Fish fed at MD showed a disruption in the pattern of locomotor activity and became less diurnal (59%). Alkaline protease activity in the midgut showed daily rhythm with the achrophase at the beginning of the dark phase in both ML and MD groups. Acid protease and amylase did not show significant daily rhythms. Plasma glucose showed a daily rhythm with the achrophase shifted by 12h in the ML and MD groups. These results revealed that the feeding time and light cycle synchronize differently the daily rhythms of behavior, digestive physiology and plasma metabolites in the Nile tilapia, which indicate the plasticity of the circadian system and its synchronizers.

Daily rhythms after vaccination on specific and non-specific responses in Nile tilapia (Oreochromis niloticus)

ABSTRACT We evaluated the daily changes in immunological and hematological factors in tilapia (Oreochromis niloticus) after an immunization period with a subsequent challenge. Experiments were divided into two phases: Phase 1 (immunization): 144 fish were distributed into two groups with 72 fish in six tanks. One group (T1) was immunized, comprising six vaccination time points (ZT schedule = ZT2 h, ZT6 h, ZT10 h, ZT14 h, ZT18 h, ZT22 h). The same schedule was applied to the other group, but with saline solution (non-vaccinated: T2). Both groups remained in the laboratory for 30 days (considered the immunization period). Phase 2 (challenge): on day 30, both vaccinated and non-vaccinated groups were challenged with Streptococcus agalactiae (2.0 × 107 CFU mL−1) following the same ZT schedule to stimulate the immune response without leading to widespread infection and mortality. On day 45, blood and head kidney samples were collected during the same ZT schedule. The variations in time of the following parameters within each group were evaluated: hematology, peroxidase activity, IgM, tnf-α3, tgf-β1, il-1β and il-12 gene expression. No significant mortality was observed for the groups or the ZT schedule (p > 0.05). Daily rhythms with diurnal acrophases were found in T2 for il12, tnf-α3 and tgf-β1 expression gene, while the acrophases of the peroxidase level, hematocrit and thrombocytes were at nighttime (p < 0.05). In contrast, most of the parameters in the vaccinated tilapia showed no daily rhythms (p > 0.05), except IgM. For all the parameters, the interaction effect between time and treatment (vaccinated and non-vaccinated groups) depended on ZT. Our results reveal that the humoral and non-specific immune system displayed a circadian rhythm based on the light-dark cycle, which could be affected by the vaccination procedure in tilapia.

Comparação de metodologias utilizadas na análise dos parâmetros sanguíneos e da proteína total de tilápia do Nilo (Oreochromis niloticus)

A hematologia em peixes contribui para a compreensao da fisiologia, relacao filogenetica, condicoes alimentares e outros parâmetros ecologicos. Este estudo comparou os efeitos dos anticoagulantes, acido etilenodiaminotetraacetico - EDTA e heparina, sobre os constituintes sanguineos de tilapia do Nilo. Foram utilizados 25 animais com peso medio de 28,6 ± 13,0g para a colheita da amostra sanguinea e determinacao do numero de eritrocitos, concentracao de hemoglobina, volume globular, proteinas totais, contagem total e diferencial de leucocitos e de trombocitos. Tambem foram comparadas algumas das tecnicas utilizadas para a analise desses constituintes, como diluentes e corantes. Os dados foram submetidos a analise de variância, e comparados pelo teste de Wilcoxon (P>0,05%). Os anticoagulantes utilizados foram eficientes quanto a inibicao da coagulacao e da ocorrencia de hemolise. Foram observadas diferencas no numero total de eritrocitos, tanto na comparacao dos anticoagulantes como na comparacao entre os diluentes utilizados (solucao salina e Natt-Herrick). Alem disso, foi encontrada diferenca entre as tecnicas utilizadas para analise da concentracao de hemoglobina e, entre os corantes utilizados para preparo das extensoes sanguineas (Panotico rapido e Rosenfeld). Os resultados dessa pesquisa permitiram concluir que ambos os anticoagulantes sao eficientes na preservacao das caracteristicas sanguineas de tilapia do Nilo. Porem, a combinacao do EDTA com o corante Rosenfeld apresentou melhores resultados na analise morfotintorial dos leucocitos, principalmente no que se refere a diferenciacao celular.