ABSTRACT
Ecdysis is a common phenomenon that happens throughout the life phase of the giant freshwater prawn Macrobrachium rosenbergii. It is vital to better understand the correlation between cannibalism and biochemical compound that exists during the moulting process. The objective of the present study was to determine the amino acid profile released by M. rosenbergii during the ecdysis process that promotes cannibalism. To accomplish this, changes in amino acid levels (total amino acid (TAA) and free amino acid (FAA)) of tissue muscle, exoskeleton, and sample water of culture medium from the moulting (E-stage) and non-moulting (C-stage) prawns were analysed using high-performance liquid chromatography (HPLC). Comparison study revealed that among the TAA compounds, proline and sarcosine of tissues from moulting prawn were found at the highest levels. The level of FAA from water that contains moulting prawns (E-stage) was dominated by tryptophan and proline. Significant values obtained in the present study suggested that these amino acid compounds act as a chemical cue to promote cannibalism in M. rosenbergii during ecdysis. The knowledge of compositions and compounds that were released during the moulting process should be helpful for better understanding of the mechanism and chemical cues that play roles on triggering cannibalism, and also for future dietary manipulation to improve feeding efficiencies and feeding management, which indirectly impacts productivity and profitability.
ABSTRACT
Ecdysis is a common phenomenon that happens throughout the life phase of the giant freshwater prawn Macrobrachium rosenbergii. It is vital to better understand the correlation between cannibalism and biochemical compound that exists during the moulting process. The objective of the present study was to determine the amino acid profile released by M. rosenbergii during the ecdysis process that promotes cannibalism. To accomplish this, changes in amino acid levels (total amino acid (TAA) and free amino acid (FAA)) of tissue muscle, exoskeleton, and sample water of culture medium from the moulting (E-stage) and non-moulting (C-stage) prawns were analysed using high-performance liquid chromatography (HPLC). Comparison study revealed that among the TAA compounds, proline and sarcosine of tissues from moulting prawn were found at the highest levels. The level of FAA from water that contains moulting prawns (E-stage) was dominated by tryptophan and proline. Significant values obtained in the present study suggested that these amino acid compounds act as a chemical cue to promote cannibalism in M. rosenbergii during ecdysis. The knowledge of compositions and compounds that were released during the moulting process should be helpful for better understanding of the mechanism and chemical cues that play roles on triggering cannibalism, and also for future dietary manipulation to improve feeding efficiencies and feeding management, which indirectly impacts productivity and profitability.
Subject(s)
Animals , Amino Acids/chemistry , Aquaculture , Cannibalism , Chromatography, High Pressure Liquid , Feeding Behavior , Fresh Water , Malaysia , Molting , Palaemonidae/physiology , Proline/chemistry , Tryptophan/chemistryABSTRACT
Effects of estradiol-17β on the giant freshwater prawn were observed in case of the embryonic tolerance, growth, development, survival rate, yolk adsorption, eye appearance, and muscular compactness. The methods were designed in two steps; those were the tolerance and the growth. In the two hours after spawning, embryos were immersed in 10, 50, 100, or 150 µg/ml estradiol-17β solution for two days, and the controls were treated with 15% artificial seawater. The tolerance was monitored in a separate experiment; they were immersed in 10, 50, 100, or 150 µg/ml estradiol-17β solutions showed that the mortality rate at 150 µg/ml estradiol-17β was 31.66%. The growth represented by yolk adsorption, hatching rate, and eye appearance. The results showed that the eyes appeared earlier than those of the controls. The survival rates were investigated in other experiments. The results showed that the highest survival rate was 48.16%, observed in the 50 µg/ml estradiol-17β treatment. Therefore, estradiol might accelerate the growth as indicated by the number of days for eye appearance being shorter period than in the control treatment. The eyes of the embryos treated with 50, 100, and 150 µg/ml estradiol-17β appeared on day 10, whereas those in the control were observed on day 16. Hatching rate was tending to high in 150 µg/ml estradiol-17β but those were not significance with the control. Yolk adsorption was found in treated embryo rather than those of the controls. The pattern of yolk cluster distribution was differing from the control. The muscle tissue was observed on day 20 after the histological process. The results showed that the bundles muscle cells were more compactness and were larger, denser, and stronger with increasing concentrations of estradiol-17β than that the controls. Therefore, estradiol-17β should be applied to stimulate growth and might be introduced with the feed to the prawn industry and manufacturing
ABSTRACT
Erythromycin A (EA) is now one of antibiotics limited in seafood products in general and in giant freshwater prawns (Macrobrachium rosenbergii) and tilapia (Oreochromis niloticus) in particular while exporting to the US, EU, Japan, Canada. There are many methods used for analyzing this antibiotic in these aqua species such as ELISA, HPLC, LC-MS/MS, GC-MS, etc. A new sensitive analytical approach for determination of erythromycin A using stripping square wave voltammetry at the slowly dropping mercury electrode was primarily developed and validated to quantify this antibiotic with simple and short time analysis, not too pure analytical solutions, not high price equipments. Electrochemical signals were measured at potential wave -1430 mV. The optimal experimental parameters for the method were: supporting electrolyte ammonium acetate 0.1 M, pH 8.0, the solvents for dissolving erythromycin standard: acetonitril, Vstart = -400 mV, Vstop = -1700 mV, Vstep = 6 mV, Vpulse = 40 mV, Tdrop = 5000 ms , Velctrolise = -1100 mV, Telectrolyse = 5 s. The method showed high recovery (85.07 ÷ 96.50 %), high sensitivity (lower limit of detection, LoD = 0.57 μg kg-1 in giant prawn and LoD = 0.52 μg kg-1 in tilapia) and high precision (RSD 0.91 ÷ 2.1 %) as well as excellent linearity (r2 adjusted ≥ 0.99999).