Use of an ultrasound device to determine sex and to perform gonad biopsy in the European eel Anguilla Anguilla / Uso de um dispositivo ultrasonográfico para determinar o sexo e efetuar a biópsia das gônadas da Enguia-Européia Anguilla anguilla

The European eel Anguilla anguilla is a highly important market species which is also increasingly in danger of extinction in Europe. One of the ways of protecting the species in the natural environment, while maintaining its market supply, is its aquaculture, e.g. due to much higher survival rate under controlled conditions than in the wild. However, this can be done only when an effective artificial reproduction biotechnique is developed. The aim of this study was to use an ultrasound device to determine the sex and to perform a biopsy of the gonads, which is a part of complete protocol of eel artificial reproduction. The findings indicate that ultrasonography is highly useful in determining the sex in migrating eel (100% of sureness) and in performing high-precision biopsy of the gonads. The present method gives the possibility to quick determine the maturity of the female gonads. The application of ultrasonography (USG) is totally safe for fish and a portable ultrasound device can be used in both the laboratory and in the field...

A Enguia-Européia Anguilla anguilla é uma espécie de grande importância comercial e que apresenta também grande risco de extinção na Europa. Uma das formas para a proteção das espécies em seu ambiente natural e de manter o seu suprimento no comércio é a aquicultura, por exemplo, devido à taxa de sobrevivência em condições controladas ser muito superior a existente em condições naturais. Contudo isto só pode ser obtido quando é desenvolvida uma biotécnica de reprodução artificial eficiente. O presente trabalho foi delineado para utilizar um dispositivo ultrassonográfico a fim de determinar o sexo e de possibilitar a realização de biópsias das gônadas, o que é parte do protocolo complete de reprodução artificial de enguias. As constatações indicaram que a ultrassonografia é muito útil para a determinação do sexo das enguias (100% de exatidão) e também é capaz de possibilitar a realização de uma biópsia das gônadas de alta precisão. O método descrito oferece possibilidades para a rápida determinação da maturidade das gônadas das fêmeas. A aplicação da ultrassonografia é totalmente segura para peixes e o dispositivo portátil de ultrassonografia pode ser utilizado tanto no laboratório como em condições de campo...

Heterosporis anguillarum infections in farm cultured eels (Anguilla japonica) in Korea

Ten eels (Anguilla japonica) from a fish farm in Korea were examined and diagnosed with a Heterosporis infection. The gross lesions on the trunk were uneven and the concave parts were pasty. Histopathologically, lyses of the trunk muscles, degenerative muscle fibers and the scattered spores were observed. The sporophorocyst (SPC) contained several spores with a variety of shapes. Some SPC were disrupted and the spores in the SPC were scattered in the muscle tissues. Macrophages existed near the scattered spores. Electron microscopy revealed special structures such as sporophorocyst containing various developmental parasitic stages such as meronts, sporonts, sporophorous vesicles and spores.

Pathological and parasitological investigations of eels [anguilla anguilla] naturally infested with anguillicola crassus and pseudergasilus zacconi in Egypt

For the first time in Egypt Anguillicola crassus and Pseudergasilus zacconi were recognized and identified from Anguilla anguilla. The naturally diseased fish showed skin hemorrhages, low body gain and occasionally abdominal swelling. In anguillicolosis, the infected swim bladders showed great thickening of their wall and multiple areas of hemorrhages together with the presence of round worms floating in chocolate like material within their luminae. The prevalence of infection was 30% and the intensity of parasite ranged from 1- 15 worms per fish. Histopathologically, cross sections of adult worms and numerous ensheathed larvae were present inside the lumen of the examined swim bladders. Severe congestion, submucosal hemorrhages and mononuclear cellular infiltration were recorded. Epithelial hyperplasia and desquamation with fibrosis of the swim bladder wall were also detected. In pseudergasilosis, the gill lesions were represented by excess mucous secretion with presence of grayish white elongated nodules firmly attached to the gill filaments. Microscopical examination of the gills revealed presence of parasitic elements in-between destructed gill filaments with diffuse hemorrhages, mononuclear cellular infiltration and fusion of gill lamellae. The morphological description used in identification of recognized parasites is discussed in the text

Changes in the electrophysiological parameters of the posterior intestine of Anguilla anguilla (Pisces) induced by oxytocin, urotensin II and aldosterone

In view of the importance of the intestine in the osmoregulation of freshwater fishes, we determined the effects of oxytocin, urotensin II (UII), and aldosterone added to the serosal side of the isolated posterior intestine of the freshwater-adapted teleost Anguilla anguilla on electrophysiological parameters. Oxytocin decreased the short-ciruit current (SCC) and transepithelial potential difference (TPD) at a centrations of 1 and 10 mU/ml (to 50 per cent and 42 per cent of control values, respectively), but did not alter these parameters at a concentration of 0.1 mU/ml. UII reduced SCC and TPD at concentrations of 10 nM, 50nM and 100 nM (to 85 per cent of control values), but increased these parameters at the concentration of 500 nM (to 115 per cent of control values). Aldosterone did not alter SCC or TPD at the concentrations tested (10 nM and 100 nM). Oxytocin may open Na+ channels in the apical membrane, allowing the flow of Na+ to the serosa, reduced SCC and TPD. Should this hypothesis be correct, oxytocin would be important for freshwater adaptation, since it would increase absorption. The reduction of SCC and TPD in the posterior intestine A. anguilla induced by UII is evidence that this neurohormone is also important for freshwater adaptation in teleosts. Aldosterone did not show this effect probaly due to the lack of receptors in this organ.

Effect of HCO3 and pH on ion transport in the posterior intestine of the freshwater-adapted teleost Anguilla anguilla

The intestinal mucosa may be exposed to acidic or alcaline solutions due to liberation of digestive secretions. In several situations blood pH may also change. Consequently, the effects of HCO-3, CO2, and pH variation of medium on the ion transport acrross the posterior intestine of the eel (Anguilla anguilla) adapted to freshwater were studied in terms of fractional values of short-circuit current (SCC), transepithelial potential difference (TPD) and conductance (G). Immature eels weighing 100-200 g were used. The control physiological solution contained: 118.5 mM NaCl, 25.0 mM NaHCO3, 3.0 mM CaCl2.2H2O, 4.7 mM KCl, 1.0 mM MgCl2.6H2O, 5.0 mMD-glucose, 10.0 mM D-mannitol, pH 7.80, and was gassed with 98 percent O2-2 percent CO2. Control values(N = 21) were: SCC = 51.90 + or - 51.90 + or - 2.8 µA.cm-2, TPD = 2.33 + or - 0.1 mV, G = 22.43 + or - 0.6 mS.cm-2. At constant pH, the reduction of HCO-3 concentration to 50 percent and 10 percent did not alter the values of SCC and TPD, but G increased with HCO-3 reduction to 10 percent. In the absence of HCO-3, SCC, TPD and G (slightly) decreased, but 1.5 mM HCO-3 still maintained the ion transport within control values, at constant pH. Comparing PH values from 6.65 to 8.61, higher values of SCC and TPD were observed at PH 7.45, but were little affected below and above this pH. There was a significant correlation between pH and SCC and TPD values; from the regression equations (1) SCC was zero at pHs below 6.62 and above 8.78 and (2) TPD was zero below 6.50 and above 8.71

Effects of cadmium on the electrocardiogram of the EEl, anguilla anguilla L

The effects of exposure to 5.0 mg/l Cd for 24 hours on the bioelectrical activity of the eel heart were studied. Fish exhibited a negative chronotropic effect and increase in the waves amplitude after Cd-treatment. These changes are found to be identical to the effects of hypoxia which point to a similar mechanism of toxicity. On the other hand, Cd-treatment induced lesions and disturbances in the eel heart muscle. The most important diagnostic features of the electrocardiogram changes are myocardial infarction, disturbances in the ionic equilibrium and low nodal rhythm. It was suggested that changes in the bioelectrical activity may be caused by gill impairment as toxic response to cadmium

Mercury levels and haematological correlations in Anguilla vulgaris

1. Mercury residues among different tissues and organs [liver, kidney, blood and muscles of Anguilla vulgaris were determined after their treatment with 1 mg Hg[+2/L]. 2. The uptake of mercury by fish organs and tissues was rapid, specially the kidneys which had levels mercury about 60 times as high as present in controls after 96 hr exposure. 3. Cellular blood constituents including erythrocuyte count, haemoglobin content, haematocrit value, total leucocytic and differential counts were measured. 4. A significant decrease was observed in erythrocyte count, haemoglobin content and haematocrit value after exposure to mercury resulting in anaemia which was interpreted as due to reduction in renal erythropoietin production due to toxicity. Leucopenia has also been observed in mercury intoxicated fish 5. Considerable changes were observed in differential leucocytic count