Role of neuroendocrine modulation and biochemistry in the sepsis in Piaractus mesopotamicus.

Sepsis is a systemic process with multifactorial pathophysiology that affects most animal species. It is responsible for high rates of morbidity and mortality. This work aimed to study the biochemical and neuroendocrine changes of the sepsis process in Piaractus mesopotamicus after Aeromonas hydrophila inoculation analyzing changes in blood leukocyte and differences in neuroendocrine-biochemical modulation using RNA-seq. Fish showed hypercortisolemia, inhibition of glucose absorption, followed by hypocortisolemia and then hyperglycemia. Thyroid hormones (T3 and T4) showed immediate decrease in serum and T4 increased 6 h post-inoculation (HPI). Sepsis-induced hormonal alterations triggered changes in the metabolic pathways increasing protein and lipid catabolism, use of transient anaerobic glycolysis and liver injury. A reference transcriptome was constructed based on blood leukocytes from P. mesopotamicus. The assembly resulted in total 266,272 contigs with a N50 of 2786 bp. There was a reorganization of plasma membrane of leukocytes at the beginning of the septic process with increased expression of neuroendocrine receptors and with continuous flow of neurotransmitters, hormones and solutes with compensatory regulation at 6 HPI. Three and nine HPI seemed to be critical, the expression of a number of transcription factors was increased, including the modulatory DEGs related to glucocorticoid and thyroid hormones induced and suppressed (FDR < 0.05). Neuroendocrine modulation can regulate leukocytes and biochemical parameters of peripheral blood, being important sources for the study of the pathophysiology of sepsis. These finding highlights the importance of further studies focusing on biochemical-neuroendocrine changes in blood leukocytes and systemic sepsis.

Dietary camu camu, Myrciaria dubia, enhances immunological response in Nile tilapia.

Camu camu, Myrciaria dubia, is an Amazon plant that presents high levels of vitamin C in its composition. Several studies in animals and humans have demonstrated their efficiency in the prevention and treatment of various diseases. However, there are no reports of its properties in fish. The aim of this study was to evaluate the effect of the oral administration of the extract of this plant in the immune parameters in Nile tilapia, Oreochromis niloticus. 400 Nile tilapia (80 ± 5 g) were randomly distributed into 20 tanks with 1500 L capacity each (20 fish/tank). After a week of adaptation to environmental conditions, it was provided a diet for 5 weeks, using different levels of inclusion of camu camu extract: 0, 50, 100, 250, and 500 mg/kg of feed. Each treatment consisted of four replicates. It was obtained 40.5 mg of vitamin C/g of camu camu pulp powder by high-performance liquid chromatography. At the end of the trial period, fish were inoculated with Aeromonas hydrophila in the swim bladder. Samples were taken after 6; 24 and 48 h of the challenge. Results revealed that fish supplemented with this herb showed significant increase (P < 0.05) in white blood cells counts in blood and exudate, burst respiratory activity, lysozyme activity, serum bactericidal activity, direct agglutination, and melanomacrophage centers count. Red blood cells count, hemoglobin, hematocrit, and biochemical profile of fish supplemented with the herb presented no statistical differences compared to control group (P > 0.05). No histopathological lesions were observed in intestine, kidney, spleen, and gills. It can be concluded that the addition of Myrciaria dubia in tilapia feed improves the immune response and the growth after 5 weeks, especially, at a dose of 500 mg/kg.

Uncaria tomentosa increases growth and immune activity in Oreochromis niloticus challenged with Streptococcus agalactiae.

Cat's claw (Uncaria tomentosa) is an Amazon herb using in native cultures in Peru. In mammals, it has been described several effects of this herb. However, this is the first report of its use on the diet of fish. The aim of this study was to determinate the effect of this plant on the growth and immune activity in Oreochromis niloticus. Nile tilapia (81.3 ± 4.5 g) were distributed into 5 groups and supplemented with 0 (non-supplement fish), 75, 150, 300, and 450 mg of U. tomentosa.kg(-1) of diet for a period of 28 days. Fish were inoculated in the swim bladder with inactivated Streptococcus agalactiae and samples were taken at 6, 24, and 48 h post inoculation (HPI). Dose dependent increases were noted in some of the evaluated times of thrombocytes and white blood cells counts (WBC) in blood and exudate, burst respiratory activity, lysozyme activity, melanomacrophage centers count (MMCs), villi length, IgM by immunohistochemistry in splenic tissue, and unexpectedly on growth parameters. However, dietary supplementation of this herb did not affect red blood cells count (RBC), hemoglobin, and there were no observed histological lesions in gills, intestine, spleen, and liver. The current results demonstrate for the first time that U. tomentosa can stimulate fish immunity and improve growth performance in Nile tilapia.

[Estimative method for quantitative sampling of Rondonia rondoni (Nematoda: Atractidae) parasite of fish]. / Método estimativo para amostragem quantitativa de Rondonia rondoni (Nematoda: Atractidae) parasito de peixes.

The present work evaluated the number of Rondonia rondoni in intestine of Piaractus mesopotamicus, for difference of dry and wet weight of parasites samples by each host, from the relation dry weight and number of parasites. Totals samples of R. rondoni of 37 specimens of P. mesopotamicus for attaiment of wet weight, dehydrated in stove with temperature between 55 degrees C and 60 degrees C, the wet weight was measured after 24 h. The number of parasites was calculated with rule of three, considering the average number of 1,010 +/- 6.027 specimens quantified in previous assay. The equation of linear regression is y = 13.138x - 162.01 and r(2) = 0.9989. The normality of the data was proven with Kolmogorov-Smirnov (p < 0.01).

[Effects of parasitism on gill structure of Leporinus macrocephalus Garavello and Britsk, 1988 (Anastomidae) and Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes:Characidae)]. / Efeitos do parasitismo sobre a estrutura branquial de Leporinus macrocephalus Garavello e Britsk, 1988 (Anastomidae) e Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes:Characidae).

This work described the lesions caused in different species of fish by gill parasites from fee-fishing at Guariba, State of São Paulo. The research was developed from april, 1997 to march to 1999, seeking to verified the kind tissues lesions from fish. Of these, forty and seven were Leporinus macrocephalus and fifty and five Piaractus mesopotamicus. About 87.2% of the L. macrocephalus, and 58.1% of the P. mesopotamicus were sponged by several species of parasites. The parasite most abundant in L. macrocephalus was Piscinoodinium pillulare, while monogenean, Trichodina sp and myxosporidian infected P. mesopotamicus. Severe gill lesions have been observed in L. macrocephalus and P. mesopotamicus caused by monogenean, P. pillulare e Trichodina sp. parasitism, such as intersticial hemorrhage, sub-epithelium edema, inflammation, epitelial hiperplasy in filaments and lamina, proliferation of mucosal cells and laminar fusion.