Measurement of reactive oxygen intermediate production in haemocytes of the penaeid shrimp, Penaeus vannamei

Abstract

Ž. A spectrophotometric nitroblue tetrazolium NBT reduction assay was used to demonstrate the Ž y . production of superoxide anions O by haemocytes of the white shrimp Penaeus Õannamei. It 2 was found that haemocytes, without receiving an experimental stimulant, showed a rather high Ž background activity. Therefore, optimal parameters number of haemocytes, type of incubation . medium, type and concentration of stimulants were first established, in order to obtain a reliable and reproducible quantitative assay. With this optimized assay, and using specific inhibitors, it was shown that it is indeed the production of O y that was measured. Activities varied strongly 2 among individual shrimp specimens. Live bacteria, among these Vibrio strains, induced O y 2 production in the haemocytes, in a dose-dependent manner. Whereas Vibrio anguillarum and a probiotic strain of V. alginolyticus evoked clear reactions, a pathogenic strain of V. harÕeyi failed to elicit O y production in the haemocytes. It is discussed that this may explain this strain's 2 capability of evading the host's oxidative microbicidal activity, which would be a virulence factor in these bacteria. Heat-killed bacteria hardly induced NBT reduction in the cells. The fungicide propiconazole or Tilt w , found as a pollutant in the aquatic environment where the shrimp are reared, was tested for its effect on NBT reduction by the haemocytes. In haemocytes that did not receive an experimental stimulant, Tilt w induced the reduction of NBT in a dose-dependent manner. In experimentally stimulated haemocytes, however, Tilt w strongly reduced the reaction upon the stimulant PMA. Probable explanations for these seemingly controversial effects of Tilt w are discussed, as are possible consequences of this sort of pollutants for shrimp aquaculture. This easy to perform and relatively cheap and simple quantitative assay for measuring the activity of an oxidative microbicidal mechanism in shrimp haemocytes, appears quite reliable and may therefore prove to be a valuable tool for monitoring shrimp health and immunologic status. q

Effect of replacement of fish meal by meat and bone meal and poultry by-product meal in diets on the growth and immune response of Macrobrachium nipponense

“…The highest final body weight in PBM 15 group was 20% higher than that of the control, which might be due to the higher digestibility of PBM [31], thereby enhancing growth. However, the fact that 50% replacement of PBM caused low SGR as compared to the replacement of PBM at 15% might be due to the poorer essential amino acid balance than PMB 15 . The utilization of PBM depends on the quality of the products, which vary among producers [32].…”

“…Phagocytosis is an important reaction of cell defense to eliminate microorganisms or foreign particles in invertebrate animals since they lack true antibodies and have to rely solely on the innate immune mechanism [15]. During phagocytosis, reactive oxygen species are produced.…”

“…This phenomenon, known as respiratory burst, plays an important role in microbicidal activity [13]. Because O 2 ÿ is the first product released from a respiratory burst, O 2 ÿ measurement has been accepted as an accurate method for estimating the cell's capability to generate a respiratory burst [13,15]. It is well known that O 2 ÿ production can be affected by environmental factors [7] and can be enhanced by treatment with immunostimulants [46], but the effect of nutritional factors on O 2 ÿ production has received little attention.…”

“…Replacement of fish meal by MBM in diets did not affect growth performance of shrimp (P > 0:05), while SGR in PBM 15 was significantly higher than that in other groups (P ! 0:05).…”

“…Song and Hsieh [13] first demonstrated a respiratory burst in Penaeus monodon haemocytes. It has been reported in haemocytes of Penaeus stylirostris [14], Penaeus vannamei [15], Macrobrachium rosenbergii [16] and Litopenaeus vannamei [17].…”