Many molecular and physiological responses to hypoxia are controlled by the transcription factor called hypoxia inducible factor 1 (HIF-1). Metabolic responses are particularly important for marine ...crustaceans that suffer hypoxia in their aquatic environment, including shrimp. HIF-1 is a heterodimer recently described in shrimp and composed by α and β subunits. In the present study, we investigated the effect of silencing HIF-1 using dsRNA in the response to hypoxia in the shrimp
Litopenaeus vannamei in vivo. Intramuscular injection of dsRNA for α and β separately, decreased the concentration of the corresponding transcripts in gills from shrimp maintained in normoxia, while no effect was detected in muscle. In contrasts, during hypoxia, silencing of HIF-1α or HIF-1β, did affect the corresponding transcripts. Moreover, silencing of the α and β subunits of HIF-1 affected the concentrations of glucose and lactate in hemolymph and gills from shrimp exposed to hypoxic conditions, giving insights of the action of HIF-1 in these responses.
We studied the effects of chronic exposure to metals on energy reserves and reproduction in the clam Megapitaria squalida in two nearby populations exposed to different levels of pollution from ...mining operations in the Gulf of California, Mexico. Female M. squalida from San Lucas beach had good reproductive health status, whereas Santa Rosalia specimens consistently showed low energy reserves, massive oocyte resorption throughout the year, high frequencies of undifferentiated individuals, low proportions of ripe and spawning organisms, smaller and fewer oocytes per follicle, and significantly lower follicular areas. Ovarian levels of Co, Cu, Pb, Mn, and Zn were consistently higher in clams from Santa Rosalia. The poor reproductive health of clams inhabiting this site may be attributed to their long-term exposure to high Co, Cu, and Pb concentrations, as these have been shown to cause toxicity and reproductive impairments in other marine organisms.
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•Female M. squalida from two nearby, metal-polluted sites showed contrasting reproductive health status.•Clams from San Lucas beach showed a good reproductive health status.•Clams from Santa Rosalia had lower energy reserves and impaired reproduction.•These negative effects may be attributed to long-term exposure to Co, Cu, and Pb.
The objective of this study was to assess zootechnical and physiological performance of Litopenaeus vannamei postlarvae (PL) reared in three environments (CW, clear water; B, biofloc; BS, biofloc ...with artificial substrates) at three stocking densities (300, 600, 900 PL/m3) for 8 weeks. At the end of experimentation, shrimp were subjected to hypoxia, and physiological response was again assessed. During rearing, low levels of total ammonia nitrogen, nitrite (NO2̄) and nitrate (NO3̄) were observed in B and BS for 600 and 900 PL/m3. For 300 PL/m3, a slight accumulation of NO2̄ and NO3̄ was detected. For the same stocking density, shrimp reared in B and BS showed significantly higher weights than those grown in CW, except for final weight. No significant differences were observed in survival. The use of biofloc and artificial substrates permitted doubling density from 300 to 600 PL/m3 without affecting growth, survival, feed conversion rate and obtaining twice the biomass. Shrimp grown in B and BS stored a surplus of glycogen and carbohydrates in their hepatopancreas, which probably gave them a better physiological capacity to counteract high‐stocking densities and hypoxia. A tendency of a higher adenylate energetic charge was observed in shrimp maintained in B and BS.
Highlights • Annotation results showed several genes not previously reported for L. vannamei. • Transcripts highly expressed in brain, gonad and hepatopancreas. • High expression of vtgr and mcm ...family members during previtellogenesis. • First report of epoxide-like enzymes expression pattern for L. vannamei. • High expression of igfbp and gpcr158 in brain of previtellogenic females. • Membrane progestin receptor highly expressed in hepatopancreas and intestine.
Abstract
The thermal responses and tolerance of organisms can be influenced by synergistic interactions with other environmental stresses. Although the heat sensitivity of the whiteleg shrimp ...(Penaeus vannamei Boone, 1931 = Litopenaeus vannamei) has been extensively researched, little is known about how hypoxia impacts the thermal tolerance of the species. We assessed the thermotolerance of P. vannamei postlarvae under combined hyperthermia and hypoxia conditions. Simultaneous hypoxia significantly decreased the thermotolerance (LT50) of the postlarvae at temperatures close to the upper thermal limit of the species.
The longfin yellowtail Seriola rivoliana is an emerging species for aquaculture diversification worldwide and production relies on fertilized eggs from captive broodstock. Temperature is the main ...factor that influences the developmental process and success during fish ontogeny. However, the effects of temperature on the utilization of the main biochemical reserves and bioenergetics are scarcely investigated in fish, whereas protein, lipid and carbohydrate metabolism have critical roles in maintaining cellular energy homeostasis. In this context, we aimed to evaluate metabolic fuels (protein, lipids, triacylglicerides, carbohydrates), adenylic nucleotides and derivates (ATP, ADP, AMP, IMP), and the adenylate energy charge (AEC) during embryogenesis and in hatched larvae in S. rivoliana at different temperatures. For this purpose, fertilized eggs were incubated at six constant (20, 22, 24, 26, 28 and 30 °C) and two oscillating (21⇄29 °C) temperatures. Biochemical analyses were made at blastula, optic vesicles, neurula, prehatch and hatch periods. Results indicated that the developmental period had a major influence on the biochemical composition at any temperature regime tested during the incubation. Protein content decreased only at hatching mainly due to the loss of the chorion, total lipids tended to increase at the neurula period and variations in carbohydrates depended on the particular spawn analyzed. Triacylglicerides were a critical egg fuel during hatching. The high AEC during embryogenesis and even in hatched larvae suggested an optimal energy balance regulation. The lack of critical biochemical changes from different temperature regimes during embryo development confirmed that this species exhibits a high adaptive capacity in response to constant and fluctuating temperatures. However, the timing of hatching was the most critical period of development, where biochemical components and energy utilization significantly changed. The oscillating temperatures tested may have physiological advantages without detrimental energetic effects that will require further research on larval quality after hatching.
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•S. rivoliana embryonic development was analyzed at constant and oscillating temperatures.•Development had a major influence on biochemical components, while temperature did not.•The adenylate energy charge indicated an optimal embryo energy homeostasis.•Protein content decreased at hatch associated with chorion breakdown and release.•Triacylglicerides were the primarily metabolic fuel, mainly used during hatching.
The neuroendocrine mechanisms mediating stress in crustaceans are different and less understood than those of vertebrates, although indirect evidence suggests the participation of catecholamines ...(CA). However, few studies have analyzed their levels during stress response of crustaceans. We examined hemolymph and tissue levels of catecholamines and other biochemical indicators, in response to handling stress in whiteleg shrimp
Litopenaeus vannamei. Shrimp were stressed by transfer, chasing, and confinement and the responses were analyzed at several intervals (10–240
min). Lactate levels in hemolymph increased from 10 to 30
min, glucose increased at 60
min, and both returned to baseline levels by 240
min. An increase in lactate levels before hyperglycemia suggests a possible activation of gluconeogenesis as a main clearance pathway for lactate. Epinephrine increased in hepatopancreas from 10 to 20
min, which indicates it could mediate lactate uptake, glucogenogenesis, and lipid catabolism in this organ. Norepinephrine levels in the eyestalk decreased by 92% between 20 and 30
min and a concomitant 10-fold increase in levels of dopamine was observed. This response suggested that the putative norepinephrine release in the X-organ sinus gland complex could mediate lactate effects in this organ (e.g. lactate positive feedback of crustacean hyperglycemic hormone release).
The high tolerance of
to a wide range of salinity (1-50 psu) makes this species an excellent candidate for culture under low salinity, decreasing shrimp epidemics and water pollution in some coastal ...areas. However, salinity levels outside the optimal range could impose several physiological constraints that would in turn affect growth and survival, particularly in the presence of additional stressors (e.g. high densities, handling practices, and hypoxia). Despite shrimp susceptibility to individual stressors has been widely addressed, information regarding response to chronic and acute stressors combined and its relation to diet is scarce. Thus, the aim of our study was to determine the effect of diet on the susceptibility to chronic (low salinity) and acute (hypoxia and escape response) stressors in terms of culture performance and physiological indicators. We evaluated overall performance during culture of
at low salinity (6 psu), fed with an experimental diet with low protein and high carbohydrate content (26% protein and 6% fish meal plus probiotic mixture) and compared to a commercial formula with high protein and low carbohydrate content (40% crude protein and 20% fish meal without probiotic mixture). At the end of the rearing experiment, shrimp were exposed to two types of acute stress, hypoxia and escape. Biochemical (hemocyanin, total proteins, glucose, and lactate) and bioenergetic (adenylic energy charge and arginine phosphate levels) variables were measured to assess chronic stress response (salinity) and acute stress response (hypoxia or escape). The experimental diet resulted in higher muscle energy status that was not affected by low salinity, although lipid levels were lower under this condition. This diet partially counteracted the low performance at low salinity and promoted greater protein efficiency. Hypoxia induced strong hyperglycemic and lactate increase as response, whereas escape response was characterized by a depletion of arginine phosphate levels, with a stronger decrease in shrimp fed experimental diet, due to the high initial level of this reserve. Some data (glucose levels in hemolymph and lipids in hepatopancreas) suggest that shrimp under chronic stress conditions (low salinity and high densities) present a low ability to respond to subsequent acute stressors such as hypoxia or escape. This work indicates that diet can increase the energy status of shrimp, enabling them to overcome potential multifactorial stressors, which are common in farming systems.
Wild female Crassostrea corteziensis oyster (n=245) were analyzed over one year to understand the main ecophysiological events associated to gonad development. Different indicators (mainly ...biochemical) were analyzed to infer: i) utilization and accumulation of energy reserves (e.g. neutral lipids, carbohydrates, proteins; vitellogenin), ii) membrane components provided by the diet as essential nutrients and indicative of cell proliferation (e.g. highly unsaturated fatty acids linked to phospholipids, sterols), iii) indicators of food availability (chlorophyll a in water, pigments in tissues, specific fatty acids and sterols), iv) gonad development (e.g. gonad coverage area, vitellin). A PCA analysis was applied to 269 measured variables. The first PC (PC1) was composed of total carbohydrate and lipid concentration, percentage of esterified sterols, fatty acids specific of diatoms; 16:1n−7/16:0, 20:5n−3 in neutral lipids with positive loadings and non methylene−interrupted fatty acids (NMI) in neutral lipids with negative loadings. The second PC (PC2) was composed of 18:4n−3 in lipid reserves and the concentration of zeaxanthin, a pigment typical of cyanobacteria with positive loadings and the proportion of 20:4n−6 in polar lipids with negative loading. The third PC (PC3) was composed of gonad coverage area (GCA) and the concentration of vitellin. Variation in GCA confirms that gonad development began in April with an extended period of spawning and rematuration from April to November. The PCA further shows that a second period of minimal maturation from November to March corresponds to the accumulation of reserves (PC1) together with an initial high availability of food (PC2) at the beginning of this period. These two periods are in accordance with the classical periods of allocation of energy to reserves followed by gonad development reported for several mollusks.
Neuroendocrine mechanisms involved in crustacean stress response are different and less understood than those of vertebrates. Although indirect evidence suggests the participation of catecholamines ...(CA), few studies have analyzed their levels during stress response in crustaceans. This study examined CA levels in hemolymph and tissue of whiteleg shrimp Penaeus vannamei besides other biochemical indicators in response to hypoxia (0.8-1.0 mg L.sup.-1). Shrimp were stressed by hypoxia exposure, and their responses were analyzed at several intervals (10-480 min). Hemolymph glucose levels decreased gradually due to a higher demand not compensated by the gluconeogenesis process from hepatopancreas or muscle after 10 min. Lactate levels in hemolymph showed a 5-fold increase after 10 min, and a correlation with CA levels in hemolymph was observed suggesting its possible role in signaling catecholaminergic activation from eyestalk in a period from 10 to 120 min. Protein levels in muscle and hepatopancreas increased gradually throughout the trial indicating the possible use of another energetic substrate as arginine phosphate. A decrease in triacylglyceride levels denotes its preferential utilization as an immediate energy source in the scape response during the first minutes of hypoxia exposure. Heart adrenaline and noradrenaline levels increased rapidly at the beginning of the trial showing a correlation with the use of triacylglycerides and carbohydrates in hepatopancreas and muscle (r = 0.89 and r = 0.93, P < 0.05, respectively). This manuscript reports evidence of CA participation in response to stress due to hypoxia and discusses possible adaptation mechanisms.
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