Shrimp Macrobrachium Borellii Research Articles

Impact of dietary lipid level on esterase enzyme activities in the non-target freshwater shrimp Macrobrachium borellii exposed to chlorpyrifos.

This study increases our understanding of how diet-driven phenotypic plasticity can help non-target aquatic invertebrates deal with chlorpyrifos (CPO) exposure. A bioassay was performed over 6 days with the freshwater shrimp Macrobrachium borellii. Experimental treatments included CPO-treated shrimps (10 μg L-1) were fed with (i) a lipid-rich diet, (ii) a lipid-medium diet, or (iii) a lipid-poor diet. Control shrimps (no CPO exposure) received the same diets as detailed above. Cholinesterases and carboxylesterases were determined as an indicator of CPO exposure. Results showed that diets with a medium-to-high lipid content were important inducers of esterase activity, while shrimps exposed to CPO under a lipid-poor diet showed a significant enzymatic inhibition. This diet-dependent esterase induction suggests that the intake of fatty dietary items mitigates the esterase enzyme inhibition caused by CPO exposure.

Tissue-specific Isotopic Incorporation Turnover Rates and Trophic Discrimination Factors in the Freshwater Shrimp Macrobrachium borellii (Crustacea: Decapoda: Palaemonidae).

The interpretation of isotopic data in ecology requires knowledge about two factors: turnover rate and the trophic discrimination factor, which have not been well described in freshwater shrimps. We performed a 142-day diet shift experiment on 174 individuals of the omnivorous shrimp Macrobrachium borellii, measured their growth, and temporally serially sampled muscle and hepatopancreas tissue to quantify carbon and nitrogen incorporation rates and isotope discrimination factors. Shrimps were fed with artificial diets (δ13C = -26.1‰, δ15N= 2.1‰) for 45 days in attempt to standardize the shrimps' initial δ13C and δ15N values for subsequent experiments. Shrimps were then fed with another artificial diet (δ13C = -16.1‰, δ15N = 15.8‰) and the change in δ13C and δ15N was observed for a period of 97 days. The trophic discrimination factor (∆) for δ13C was significantly higher in hepatopancreas (0.7 ± 0.36‰) than in muscle (-0.1 ± 0.83‰); however, the opposite was the case for δ15N (1.7 ± 0.43‰ and 3.6 ± 0.42‰, respectively). In the hepatopancreas the mean residence time (τ) of 13C was 26.3 ± 4.3 days compared to a residence time of 16.6 ± 5.51 days for δ15N, whereas the τ in muscle was 75.8 ± 25 days for δ13C and 40 ± 25 days for δ15N. The rate of incorporation of carbon into muscle was higher than that predicted by allometric equations relating isotopic incorporation rate to body mass that was developed previously for invertebrates. Our results support ranges of traditional trophic discrimination factor values observed in muscles samples of different taxa (∆15N around 3‒3.5‰ and ∆13C around 0‒1‰), but our work provides evidence that these traditionally used values may vary in other tissues, as we found that in the hepatopancreas ∆15N is around 1.7‰.

Behavioural responses of freshwater zooplankton vary according to the different alarm signals of their invertebrate predators

Single behavioural interactions between two freshwater planktonic crustaceans and invertebrate predators from different zones of the common environment were studied. The planktonic prey organisms were the cladoceran Ceriodaphnia dubia and the copepod Notodiaptomus conifer. The three invertebrate predators were the shrimp Macrobrachium borellii, the crab Trichodactylus borellianus and the larva of the dipteran midge Chaoborus. Feeding experiments were first performed to document the effects of exposure time and prey density on predation. All the selected predators fed on C. dubia and N. conifer, and predation rates were dependent on prey density and exposure time. The ability of microcrustaceans to modify their swimming and avoidance behaviour when faced with cues from each predator was then analysed. The cladoceran was more vulnerable to decapod predation, whereas the prey microcrustaceans were taken equally by the dipteran larvae. The analysis showed that the microcrustaceans detected the presence of at least one invertebrate predator through the predator alarm signals. The cladoceran responded to chemical signals from the three predators but copepods modified their behaviour only in the presence of infochemicals of M. borellii. The different outcomes suggest that macrocrustaceans have different vulnerabilities when faced with the same predator and so have evolved specific and different strategies to reduce invertebrate predation.

Structural characterization of the lipovitellin from the shrimp Macrobrachium borellii

In oviparous species, proteins and lipids are found in the vitellus forming lipoproteins called lipovitellins. They are an important energy source for embryos development and larvae growth and survival. We have previously isolated and partially characterized the sole egg cytosolic lipovitellin from the freshwater shrimp Macrobrachium borellii. It is a native protein of 440 kDa, composed of two subunits of 94 and 112 kDa. In the present work we studied size, shape and structure of M. borellii lipovitellin using electron microscopy, crosslinking reagents, MALDI-TOF, circular dichroism, fluorescence and partial proteolysis. The results showed that lipovitellin has a quasi spherical morphology with an estimated diameter of 18.5 ± 3.5 nm. It appears to be composed of two subunits of 94 kDa, and one of 112 kDa. The larger subunit is more susceptible to trypsinolysis, indicating that it is less compactly folded and/or more exposed to the aqueous medium than the 94 kDa subunits. The hetero-trimer is held together by non-covalent interactions. Peptide mass fingerprinting by MALDI-TOF, produced 42 polypeptides matching to a vitellogenin of a related species ( Macrobrachium rosenbergii). Circular dichroism indicated that this protein contains 35.7% α-helix, 16.6% β-sheet and 20% turns. Tryptophan fluorescence emission, at a maximum of 334 nm, indicated that the environment polarity of these aromatic residues is similar to that of other crustacean lipoproteins.

Lipid and fatty acid composition and energy partitioning during embryo development in the shrimp Macrobrachium borellii.

Energy partitioning, composition of lipids and fatty acids, and their utilization by embryos were determined in the lecithotrophic shrimp Macrobrachium borellii during seven development stages. The biochemical composition at stage I is represented by lipids, proteins, and carbohydrates, with 29.3, 28.7, and 0.2% dry weight, respectively. The former two were identified as the major energy-providing components, contributing 131 and 60 cal/100 mg egg, dry weight, respectively. The overall conversion efficiency (CE) was 45.0% (calculated as percentage of vitelline energy transformed into embryonic tissues). Lipids were the most important energy reserve (CE 39.3%), followed by proteins (CE 57.1%), both being simultaneously utilized during development while carbohydrates were synthesized de novo (CE 587.5%). Variation in the lipid class composition of embryos and vitellus showed an accumulation of triacylglycerols (TAG) and phospholipids (PL) up to stage IV, a more active accumulation and selective utilization phase (stages V and VI), and a consumption and de novo synthesis period until hatching. Structural lipids (PL and cholesterol) and pigment astaxanthin were selectively conserved in embryos, but TAG, hydrocarbons, and esterified sterols were preferentially depleted. Monounsaturated fatty acids (FA) were the major group in TAG, whereas polyunsaturated FA (PUFA) were the major group in PL after organogenesis. Certain PUFA such as 22:6n-3 and 20:5n-3 were selectively accumulated in PL.

Enzyme activities involved in lipid metabolism during embryonic development ofMacrobrachium borellii

The activities of the enzymatic systems involved in the activation and degradation of fatty acids, and in the synthesis of triacylglycerols and phospholipids were studied in vitro using total cellular homogenate and subcellular fractions of eggs of the shrimp Macrobrachium borellii at different developing stages. Egg development was divided into seven stages based on morphological features of the embryo. Palmitoyl-CoA ligase activity increased as the embryo developed and showed its maximum at stage V. An increase in the synthesis of triacylglycerols and diacylglycerols was also observed at this stage. Diacylglycerylethers were synthesized more actively during the first stages of development. The higher specific activity observed in total homogenate than in microsomal fraction suggested that their synthesis was not exclusively microsomal. Phospholipid synthesis was very active all along development, reflecting active membrane biosynthesis. The highest activity of the cytosolic triacylglycerol lipase was observed at stage V. Fatty acid degradation, measured as mitochondrial beta-oxidation activity, did not vary significantly during development. We conclude that both the anabolic and catabolic processes concerning lipid metabolism are very active, with values similar to those described for adult hepatopancreas, revealing the major role of lipids during shrimp embryogenesis energetics, and that the highest activities of lipid synthesis-hydrolysis take place at stage V when embryos are under active organogenesis. J. Exp. Zool. 286:231-237, 2000.

Fatty Acid Metabolism of Macrobrachium borellii: Dietary Origin of Arachidonic and Eicosapentaenoic Acids

To determine the origin of arachidonic (20:4n-6) and eicosapentaenoic (20:5n-3) acids in the freshwater shrimp Macrobrachium borellii, the capacity of bioconversion of radioactive α-linolenic (18:3n-3) and dihomogammalinolenic (20:3n-6) acids was assayed in vivo and in vitro. No conversion of these two fatty acids into 20:4n-6 and 20:5n-3 was observed. Both 20:4n-6 and 20:5n-3 acids were detected in the stomach contents of wild animals. When we analyzed the natural diet of M. borellii, these fatty acids were found in the associated periphyton and detritus. When shrimps were fed artificial diets rich in either linoleic (18:2n-6) or α-linolenic acids, a sharp decrease of 20:4n-6 and 20:5n-3 was observed in vitamin- and mineral-deficient treatment groups. When the animals were fed diets with added minerals and vitamins, the same effect was observed after longer treatment times. Under our experimental conditions, it can be concluded that shrimps are unable to synthesize either 20:4n-6 or 20:5n-3 from shorter chain fatty acids, and these fatty acids must be supplied by the diet.

Genetic Diversity of Populations of the Fresh-Water Shrimp Macrobrachium borellii (Caridea: Palaemonidae) Evaluated by Rapd Analysis

Genetic Diversity of Populations of the Fresh-Water Shrimp Macrobrachium borellii (Caridea: Palaemonidae) Evaluated by Rapd Analysis

GENETIC DIVERSITY OF POPULATIONS OF THE FRESH-WATER SHRIMP MACROBRACHIUM BORELLII (CARIDEA: PALAEMONIDAE) EVALUATED BY RAPD ANALYSIS

ABSTRACT We evaluated the genetic diversity of 2 populations of the pampean fresh-water shrimp Macrobrachium borellii at its most southern geographical distribution by means of the PCR-based technique RAPD (random amplified polymorphic DNA). As a result of either small population size, greater degree of isolation, or greater inbreeding, genetic diversity was lower in an artificial pond population than in a population from a small tributary of the Rio de la Plata. The high level of diversity scored in this species with RAPD markers is striking in comparison to the low H values reported by other authors for decapods, including Macrobrachium rosenbergii, with allozyme markers. These results demostrate that RAPD polymorphisms can be useful measures of diversity in these taxa.

Effect of environmental temperature on mitochondrial β-oxidation activity in gills and hepatopancreas of the freshwater shrimp Macrobrachium borellii

1. 1. To elucidate the effect of environmental temperature on mitochondrial palmitic (16:0) and oleic (18:1 n-9) fatty acid β-oxidation of the freshwater shrimp Macrobrachium borellii, groups of animals were maintained at 11 and 29°C, respectively. 2. 2. These are the extreme temperatures of the water stream that they inhabit. After 21 days of acclimation, gills and hepatopancreas mitochondria were isolated and their oxidative capabilities were measured. 3. 3. There were no significant changes in mitochondrial fatty acid β-oxidation activity in gills and hepatopancreas of animals acclimated at 11°C, compared with controls (16–20°C) 4. 4. An increment in the fatty acid β-oxidation in those animals acclimated at 20°C was observed. It was several-fold higher compared to controls. 5. 5. Acclimation affects the optimal temperature for β-oxidation specific activity. 6. 6. There were no differences in the lipid rotational mobility ( r) of mitochondrial membranes as a consequence of temperature acclimation.

Lipid classes' consumption related to fasting and thermal stress in the shrimp Macrobrachium borellii

1. 1. The effect of the environmental temperature on lipids of unfed and fed shrimps, was studied. Lipid and fatty acid classes from the hepatopancreas, gills and muscle, were analyzed. 2. 2. Each organ responds in a different way to food deprivation or to changes in the water temperature. The hepatopancreas is the main organ where lipids are stored and great variations are observed. 3. 3. A 4-week fasting did not modify energetic lipid levels of the hepatopancreas either at low environmental temperature (13°C) or moderate temperature (14–20°C). In contrast, a significant consumption of triacylglycerols and free fatty acids at high temperature (29°C) was found. 4. 4. Consumption of neutral lipids due to thermal stress also appeared in the fed animals. 5. 5. The changes in the fatty acid composition could be attributed to those found in the lipids they belong to. Besides, such changes partially reflected the composition of the diet.