Ammonia Excretion Research Articles

The carbon and nitrogen budget of Desmophyllum dianthus-a voracious cold-water coral thriving in an acidified Patagonian fjord.

In the North Patagonian fjord region, the cold-water coral (CWC) Desmophyllum dianthus occurs in high densities, in spite of low pH and aragonite saturation. If and how these conditions affect the energy demand of the corals is so far unknown. In a laboratory experiment, we investigated the carbon and nitrogen (C, N) budget of D. dianthus from Comau Fjord under three feeding scenarios: (1) live fjord zooplankton (100–2,300 µm), (2) live fjord zooplankton plus krill (>7 mm), and (3) four-day food deprivation. In closed incubations, C and N budgets were derived from the difference between C and N uptake during feeding and subsequent C and N loss through respiration, ammonium excretion, release of particulate organic carbon and nitrogen (POC, PON). Additional feeding with krill significantly increased coral respiration (35%), excretion (131%), and POC release (67%) compared to feeding on zooplankton only. Nevertheless, the higher C and N losses were overcompensated by the threefold higher C and N uptake, indicating a high assimilation and growth efficiency for the krill plus zooplankton diet. In contrast, short food deprivation caused a substantial reduction in respiration (59%), excretion (54%), release of POC (73%) and PON (87%) compared to feeding on zooplankton, suggesting a high potential to acclimatize to food scarcity (e.g., in winter). Notwithstanding, unfed corals ‘lost’ 2% of their tissue-C and 1.2% of their tissue-N per day in terms of metabolism and released particulate organic matter (likely mucus). To balance the C (N) losses, each D. dianthus polyp has to consume around 700 (400) zooplankters per day. The capture of a single, large krill individual, however, provides enough C and N to compensate daily C and N losses and grow tissue reserves, suggesting that krill plays an important nutritional role for the fjord corals. Efficient krill and zooplankton capture, as well as dietary and metabolic flexibility, may enable D. dianthus to thrive under adverse environmental conditions in its fjord habitat; however, it is not known how combined anthropogenic warming, acidification and eutrophication jeopardize the energy balance of this important habitat-building species.

Establishment of an RI for the urine ammonia-to-creatinine ratio in dogs.

BackgroundAmmonia is produced and excreted by the kidney, contributing to systemic acid‐base homeostasis through the production of bicarbonate. Disorders of acid‐base balance can lead to many clinical problems and measuring ammonia excretion helps in determining if the kidneys are responding to acid‐base challenges appropriately. Reference intervals are integral to clinical decision‐making, and there is no current RI for the urine ammonia‐to‐creatinine ratio (UACR) in dogs.ObjectiveThis study aimed to generate an RI for the UACR in healthy adult dogs.MethodsThe study used adult, client‐owned dogs that were presented to the University of Florida Primary Care and Dentistry service (n = 60). Physical examinations were performed and serum chemistry and urinalysis samples were obtained. Urine ammonia and creatinine concentrations were determined. Dogs were excluded if there were significant abnormalities in either their urinalysis or serum chemistry results. The RI for the UACR was calculated according to the recommendation of the American Society for Veterinary Clinical Pathology. Data were evaluated for correlation with serum bicarbonate, weight, age, and sex.ResultsThe RIs for the UACR were 0.16‐23.69 with 90% confidence intervals for the lower and upper limits of (0.13‐1.17) and (20.50‐23.75), respectively. No significant impact of age, sex, or weight was found. There was no discernable relationship between serum bicarbonate and UACR.ConclusionsEstablishing an RI for UACR in healthy adult dogs will allow for further studies to determine if alterations are observed during specific disease states.

Comparison in Growth, Feeding, and Metabolism Between a Fast-Growing Selective Strain and a Cultured Population of Pearl Oyster (Pinctada fucata martensii)

Pearl oyster (Pinctada fucata martensii) is the main species cultured for marine pearls in the world. A breeding program was carried out for desirable production traits, including high growth rate, and a fast-growing selective strain of pearl oysters was established. In the current study, we compared the growth characteristics between a selective strain and a cultured population of P. f. martensii in Beihai, Guangxi Province, China. Large size (SL) and small size (SS) individuals of the selective strain were selected, and the differences of physiological and metabolic indexes, such as feeding, respiration, excretion, and enzyme activities between SL and SS and cultured population (CL), were also compared. The results showed that at the age of 6 months, pearl oysters of the selective strain were 14.61% larger than CL, and the proportion of SL (30–40 mm) was 59%, which was two times higher than CL (28%). SL with a rapid growth rate had a high clearance rate (CR), and the CR of SL was about 1.8 times higher than that of CL and 5 times higher than that of SS. In addition, the activities of digestive enzymes (amylase, pepsin, and lipase) and growth-related carbonic anhydrase enzymes in SL were higher than those in the other two groups (p < 0.05). SS with a slow growth rate had higher oxygen consumption (OCR) and ammonia excretion (AER) rates than SL and CL (p < 0.05). Our results suggest that the rapid growth of the selective strain P. f. martensii can be attributed to increased energy intake and reduced energy consumption.

Combined analysis of mRNA–miRNA reveals the regulatory roles of miRNAs in the metabolism of clam Cyclina sinensis hepatopancreas during acute ammonia nitrogen stress

Clam Cyclina sinensis behaves a stronger ammonia nitrogen tolerance, whereas the molecular regulation mechanism remains unknown. In the present study, C. sinensis was exposed to ammonia nitrogen (32.90 mg/L) for 0 h (the control), 12 h (T1) and 24 h (T2). Integrated analysis of miRNA-mRNA was conducted to reveal the regulatory roles of miRNAs in the metabolism of C. sinensis exposed to acute ammonia nitrogen. Numerous genes involved in detoxification and ammonia excretion expressed differently indicate that nitrogen assimilation and utilization is adjusted to accommodate ammonia exposure. The clam has to alter their glucose and lipid metabolism to meet energy requirements to adapt acute ammonia exposure in the environment. 12, 948 genes were identified as target genes of the differently expressed miRNAs. Most of mRNA–miRNA pairs were involved in metabolisms of carbohydrate, lipid and amino acid. miRNA-mRNA integrated analysis revealed involvement of Purine metabolism, Wnt signalling pathway, Hippo signalling pathway, PI3K-Akt signalling pathway in ammonia-stress response of C. sinensis. Exposed to ammonia, clam may suffer hypoxia exposure. Overall, exposed to ammonia, clam has to alter their glucose and lipid metabolism to meet energy requirements. Numerous mRNA–miRNA pairs were involved in metabolisms of carbohydrate, lipid and amino acid and miRNA can regulate the metabolism of C. sinensis by regulating the expression of target genes during acute ammonia nitrogen stress. The net result is that nitrogen assimilation and utilization is adjusted to accommodate ammonia exposure. The current study is helpful for further investigation into the ammonia nitrogen response mechanisms in mollusks.

Use of eugenol, benzocaine or salt during the transport of panga, Pangasianodon hypophthalmus (Sauvage, 1878): Effects on water quality, haematology and blood biochemistry

Sedatives and salt have been used to mitigate the effects of stress during the transport of live fish. This work evaluates the use of benzocaine, eugenol or salt during the transport of panga. Juveniles (22.9 ± 5.3 g) were transported for 5 h in 15-L bags containing 6 L of water (one juvenile per litre). Seven transport treatments containing four repetitions (control 0 mg/L; 5 and 10 mg/L of eugenol; 5 and 10 mg/L of benzocaine; 4 and 8 g/L of salt) and a basal pre-transport treatment were evaluated. No mortality was observed during the experiment and no differences were found among treatments for dissolved oxygen, haematocrit, haemoglobin and total protein. Immediately after transport, lower ammonia levels were found using 5 mg/L of benzocaine and 10 mg/L of eugenol; a lower glucose concentration was observed for the fish submitted to 5 mg/L of eugenol; and a higher triglycerides were observed for the fish submitted to 4 g/L of salt. After 24 h post-transport, the highest glucose level was for 8 g/L of salt, while the highest cholesterol level was for 4 g/L of salt. After 48 h post-transport, the lowest triglyceride level was for 5 mg/L of eugenol. In conclusion, we recommend adding 5 mg/L of benzocaine or 10 mg/L of eugenol to water to reduce ammonia excretion during panga transport.

Neglected analytes in the 24-h urine: ammonium and sulfate.

Evaluation of the kidney stone patient includes measurement of 24 h urine chemistries. This review summarizes the application of physiologic principles to the interpretation of urine chemistries, using sulfate and ammonium to estimate diet acid load, and the renal response. There has been increased recognition of the need to measure urine ammonium excretion in the clinical setting in order to understand renal acid excretion. Some 24 h urine kidney stone panels include ammonium measurements, providing an opportunity to apply this measurement to clinical practice. In order to better interpret ammonium excretion, one needs an estimate of dietary acid load to understand the driving forces for ammonium excretion. Sulfate is also included in some kidney stone panels and functions as an estimate of diet acid load. Combining these analytes with urine pH, the clinician can quickly estimate dietary stone risk as well as potential bowel disease, acidification disorders, and the presence of urease producing bacteria; all of which can affect stone risk. Measurement of ammonium and sulfate excretion along with urine pH provide important insights into the acid/alkali content of diet, presence and severity of bowel disease, presence of renal acidification disorders, and urinary infection.

Inhibition of argininosuccinate synthase (ASS) affected ammonia excretion in yellow catfish Pelteobagrus fulvidraco during acute ammonia poisoning

Ammonia is toxic to most fish. Different fish have different treatment methods for ammonia toxicity, mainly including urea cycle and glutamine synthesis pathway, depending on their physiological status. A two-stage study was carried out to test the inhibition of argininosuccinate synthase (ASS) effects on ammonia detoxification in hyperammonemia yellow catfish. At the stage 1, fish were injected lethal half concentration (LC50) of ammonium acetate and sampled at 0, 1, 3, 6, 12 and 24 h post-injection. The result found that plasma ammonia content of fish was injected with ammonium acetate reached its highest level at hour 1, which was used as the optimal sampling time in stage 2. At the stage 2, the four experimental groups were carried out: NaCl group was injected intraperitoneally with 0.9% sodium chloride as control; NH3 group was injected with LC50 ammonium acetate; NH3+BPP group was injected with mixture of ammonium acetate and bradykinin-potentiating peptide (BPP); BPP group was injected with BPP. The results showed that inhibition of ASS can lead to accumulation of ammonia in plasma and kidney, and glutamine in liver and kidney; and decreases ASS, argininosuccinate lyase, arginase activates, and ornithine, glutamate, alanine, proline, tyrosine, methionine contents, and increases ornithine transcarbamylase, glutaminase activates, and citrulline, aspartate, arginine, glutamine, histidine, isoleucine, phenylalanine, lysine contents; and result in upregulation of ASS, ASL, CPS 1, OTC, GS and GLS genes expression. This result indicates that the inhibition of ASS in yellow catfish with ammonia poisoning will lead to the urea cycle disorder; yellow catfish can enhance the detoxification capacity of ammonia by improving glutamine synthesis when the urea cycle is inhibited; argininase played an important role in ammonia detoxification of yellow catfish.

Adaptive changes in the ornithine cycle and amino acid synthesis in sheep liver with different meat productivity

The aim of the research was to study the ornithine cycle as the process of fixing ammonia and the formation of urea in the body of highly productive animals. In our experiments, we used a protein-deficient diet and urea as a nitrogen substitute for nitrogen-containing materials in the diet to reveal the mechanism of action of urea on animals, in particular on the biochemical processes of the ornithine cycle. There are some differences between Bukovinian sheep of the Askanian meat-wool breed and outbreds in terms of the ability to build muscle tissue. Our study reveals that the slaughter yield and the average daily gain consumption of Bukovinian-type meat of the Askanian meat-wool breed were higher in summer and in autumn, compare with purebred sheep. Sheep of the Bukovynian type of Askanian meat-wool breed have the intensity of enzymatic formation of urea in liver homogenates that is much higher in all experiments than in outbred sheep. A sharp drop in the activity of all stages of urea formation and glutamic acid synthesis in liver homogenates and significantly weakened urea formation was found in all experiments of the fourth series in comparison with the experiments in the third series. Increased muscle growth, high nitrogen deposition, and a much lower percentage of urinary excretion of ammonia and urea nitrogen, as well as higher activity of enzymes of the ornithine cycle and glutamic acid synthesis in the Bukovinian sheep type of Askanian meat-wool breed compared to outbreeds allow concluding that ammonia and urea in highly productive animals act less as finishing products of nitrogen metabolism than in low-productive animals.

Ascaris suum Nutrient Uptake and Metabolic Release, and Modulation of Host Intestinal Nutrient Transport by Excretory-Secretory and Cuticle Antigens In Vitro.

Ascaris suum, the most important pig parasite, also infects humans as a zoonotic pathogen. Malabsorption upon infection probably results from impaired nutrient transport, presumably mediated by the parasite’s excretory-secretory (ES) or cuticle somatic (CSO) antigens. The present study investigated the electrogenic transport (ΔIsc) of glucose, alanine and the dipeptide glycyl-l-glutamine (glygln), as well as glucose net flux rates in pig jejunal tissue after in vitro exposure to adult A. suum total ES or CSO antigens in Ussing chambers. ΔIsc of glucose, alanine and glucose net flux rate were significantly decreased after one hour of exposure to total ES antigen. In contrast, CSO antigens increased the transport of glygln. Additionally, nutrient uptake and ES antigen pattern were compared in culture medium from untreated adult worms and those with sealed mouth and anal openings. Untreated worms completely absorbed glucose, while cuticular absorption in sealed worms led to 90% reduction. Amino acid absorption was 30% less effective in sealed worms, and ammonia excretion decreased by 20%. Overall, the results show that A. suum total ES antigen rapidly impairs nutrient transport in vitro. Future studies confirming the results in vivo, narrowing down the ES components responsible and investigating underlying molecular mechanisms are needed.

Urinary Chloride Excretion Postcardiopulmonary Bypass in Pediatric Patients-A Pilot Study.

The aim of this study was to describe renal chloride metabolism following cardiopulmonary bypass (CPB) surgery in pediatric patients. A prospective observational trial in a tertiary pediatric intensive care unit (PICU) with 20 recruited patients younger than 2 years following CPB surgery was conducted. Urinary electrolytes, plasma urea, electrolytes, creatinine, and arterial blood gases were collected preoperatively, on admission to PICU and at standardized intervals thereafter. The urinary and plasma strong ion differences (SID) were calculated from these results at each time point. Fluid input and output and electrolyte and drug administration were also recorded. Median chloride administration was 67.7 mmol/kg over the first 24 hours. Urinary chloride (mmol/L; median interquartile range [IQR]) was 30 (19, 52) prior to surgery, 15 (15, 65) on admission, and remained below baseline until 24 hours. Plasma chloride (mmol/L; median [IQR]) was 105 (98, 107) prior to surgery and 101 (101, 106) on admission to PICU. It then increased from baseline, but remained within normal limits, for the remainder of the study. The urinary SID increased from 49.8 (19.1, 87.2) preoperatively to a maximum of 122.7 (92.5, 151.8) at 6 hours, and remained elevated until 48 hours. Plasma and urinary chloride concentrations were not associated with the development of acute kidney injury. Urinary chloride excretion is impaired after CPB. The urinary SID increase associated with the decrease in chloride excretion suggests impaired production and/or excretion of ammonium by the nephron following CPB, with gradual recovery postoperatively.

Oxygen Consumption and Ammonia Excretion of Marphysa sanguinea (Polychaeta: Eunicidae) in Relation to Body Mass and Temperature

(1) Background: Marphysa sanguinea is a polychaete with high economic value and ecological importance. Information on metabolism is important to understand the physiological action of organisms. (2) Methods: The rates of oxygen consumption (R) and ammonia excretion (U) were measured using different temperatures (T) and body mass (M) levels. The activation energy (E) was calculated using the universal temperature dependence theory. (3) Results: Oxygen consumption presented a curve with an upward trend first, and then a downward trend, and ammonia excretion displayed a “U” curve. The effects of temperature and body size on oxygen consumption and ammonia excretion rates were extremely significant. Small individuals had higher metabolic rates than large polychaetes at the same temperature. The relationship between oxygen consumption, ammonia excretion, and M was expressed as Y = a·Mb, bR = 0.56 ± 0.09, and bU = 0.35 ± 0.30. The oxygen consumption activation energy was ER = 0.68 eV, and the ammonia excretion activation energy was EU = 0.53 eV. The O:N ratio at different temperatures and body sizes was in the range of 3.55–56.44. (4) Conclusions: The results not only provide basic data on the metabolism of M. sanguinea but also insights to understand the relationship between animal metabolism and ecological factors from different perspectives.

Metal Accumulation and Ion Regulation in the Fish Hyphessobrycon luetkenii Living in a Site Chronically Contaminated by Copper: Insights from Translocation Experiments.

Fish living in the João Dias creek (southern Brazil) have to deal with trace-metal contamination in the long-term basis, as this aquatic environment has been historically impacted by copper mining activities. In order to survive in this harsh environment, the local biota had to develop adaptations related to pollution tolerance. The aim of this study was to test if biochemical mechanisms related to osmoregulation were among these adaptations, using translocation experiments. Water ionic and trace-metal compositions were measured in a nonmetal impacted site (NMIS) and in a metal impacted site (MIS) of this creek. Also, whole-body metal accumulation, ion concentration and branchial enzyme activity (Na,K-ATPase and carbonic anhydrase) were evaluated in Hyphessobrycon luetkenii. In both NMIS and MIS, fish were collected and immediately stored, kept caged or translocated from sites. The result shows that waterborne Cu was 3.4-fold higher at the MIS. Accordingly, animals that had contact with this site showed elevated whole-body Cu levels. Moreover, both translocated groups showed elevated Na,K-ATPase activity. Additionally, fish translocated from the NMIS to the MIS showed lower carbonic anhydrase activity. These findings indicate that H. luetkenii chronically or acutely exposed to naturally elevated waterborne Cu showed a rapid Cu bioaccumulation but was unable to readily excrete it. Moreover, classic Cu osmoregulatory toxicity related to Na,K-ATPase inhibition was not observed. Conversely, impacts in ammonia excretion related to carbonic anhydrase inhibition may have occurred.

The Importance of Larval Stages for Considering Crab Microbiomes as a Paradigm for the Evolution of Terrestrialization.

The transition from an aquatic to a terrestrial lifestyle has evolved multiple times, and in numerous different phyla, in earth's history. In many crab species, this process is still underway (Bliss and Mantel, 1968), providing a unique opportunity to study the evolution of terrestrialization, as well as the role of associated microbiomes during this process (Cannicci et al., 2020). Recently, Cannicci et al. (2020) reported on the potential importance of microbiomes in the transition of crabs, formally wholly aquatic species, to life, fully or in part, in terrestrial environments. The authors argue that symbiotic bacteria, such as those of gill and gut microbiomes, may play a key role in easing this transition, by helping crabs to overcome physiological and morphological challenges associated with conquering the terrestrial environment, such as impaired respiration and osmotic regulation, and a new, often primary plant-based low nitrogen diet. Here we focus on the microbiomes of crab larvae and their potential role for the evolution of terrestrialization. Crabs that are transitioning to life on land fall into two broad categories: terrestrial species that spend their whole adult life (except for larval release) on land independent of tidal inundation or freshwater bodies, and semi-terrestrial species that spend their adult life on land but are dependent on tidal inundation or freshwater (Burggren and McMahon, 1988; Anger, 1995). Many marine organisms form symbiotic relationships with microorganisms to aid life in extreme environments (Sogin et al., 2020). In line with the hologenome theory, this suggests that host-microbe interactions play an important role in an organism's evolution, where the genes of both the host and its microbes co-evolve in the collective “holobiont” (Zilber-Rosenberg and Rosenberg, 2008), potentially allowing the colonization of formerly hostile environments (Bang et al., 2018). Microbial symbionts, as individual species or in mixed-species assemblages, are present in many crustaceans, such as the marine isopod Idotea balthica (diet-specific gut microbiomes, Mattila et al., 2014), the intertidal brachyuran crab Eriocheir sinensis (gill and gut microbiomes, Zhang et al., 2016), and the freshwater signal crayfish Pacifastacus leniusculus (intestinal bacteria, Hernandez-Perez et al., 2021). Given that microbial assemblages are often specific to certain organs of their hosts (Chomicki et al., 2020), symbioses have likely evolved in support of a specific function. The microbial assemblages associated with the guts of semi-terrestrial crabs have been proposed to aid in the adaptation of a low nitrogen, herbivorous diet during terrestrialization (Bui and Lee, 2015), like microbial assemblages of other aquatic invertebrates, e.g., isopods, where they enable the digestion of cellulose (Zimmer et al., 2002; O'Connor et al., 2014). The bacteria specifically associated with crab gills (Zhang et al., 2016, 2017) may facilitate ammonia excretion (Weihrauch et al., 2004), utilize gaseous CO2 (Morris, 2001), and buffer exposure to oxygen, which occurs at a concentration 30 times higher (Hsia et al., 2013) in the terrestrial compared to the marine environment where the host organism evolved. The microbiomes of both gut and gills could therefore provide terrestrial and semi-terrestrial crabs (here collectively called semi-/terrestrial) with means to cope with life in marine as well as in terrestrial environments. Whilst the presence of microbiomes and their role in buffering the stresses imposed on crabs by terrestrialization is beginning to be discussed (Bui and Lee, 2015; Cannicci et al., 2020), there are many unknowns. For example, the mode of bacterial acquisition, bacterial diversity, topological association, and the precise functions of their organ-specific microbial assemblages are still poorly understood, both for adult semi-/terrestrial crabs and their early life stages. Most semi-/terrestrial crab species, like their aquatic counterparts, have a biphasic life cycle including fully aquatic larvae, via which they transition to semi-/terrestrial juvenile/adult life (Anger, 1995; Hartnoll et al., 2014). Understanding microbial colonization of the larvae would likely provide critical insights into how these crabs have been able to move from water to land, and whether the bacteria themselves facilitate this transition.

Diel metabolic patterns in a migratory oceanic copepod

Diel vertical migration of zooplankton profoundly impacts the transport of nutrients and carbon through the water column. Despite the acknowledged importance of this active flux to ocean biogeochemistry, these contributions remain poorly constrained, in part because daily variations in metabolic rates are not considered or are modeled as simple functions of temperature. To address this uncertainty, we sampled the subtropical copepod Pleuromamma xiphias at 4- to 7-h intervals throughout the daily migration and measured rates of oxygen consumption, ammonium excretion, fecal pellet production and metabolic enzyme activity. No significant patterns were detected in rates of oxygen consumption or ammonium excretion for freshly caught animals over the diel cycle. Fecal pellet production was highest during mid-night, consistent with several hours of feeding near the surface. Surface feeding resulted in fecal pellet production at depth in the morning, providing direct evidence that active flux of particulate organic carbon occurs in this region. Electron transport system activity was highest during the afternoon, contrary to our prediction of reduced daytime metabolism. Activity of both glutamate dehydrogenase and citrate synthase increased during early night, reflecting higher capacity for excretion and aerobic respiration, respectively. Overall, these results show that activities of metabolic enzymes vary during diel vertical migration. The surprising observation of elevated afternoon enzyme activity coupled with daytime fecal pellet and ammonium production suggests that additional characterization of the daytime activity of migratory zooplankton is warranted.

Increasing Acid Retention with Progressive GFR Decline Is Associated with Decreasing Urine Ammonium Excretion

Increasing Acid Retention with Progressive GFR Decline Is Associated with Decreasing Urine Ammonium Excretion

Effects of salinity on survival, growth, haemolymph osmolality, gill Na + ‐K + ‐ATPase activity, respiration and excretion of the sword prawn Parapenaeopsis hardwickii

The present study aims to evaluate the effects of salinity (8‰, 12‰, 16‰, 20‰, 24‰, 28‰, 32‰ and 36‰) on survival, growth, haemolymph osmolality, gill Na+-K+-ATPase activity, respiration and excretion of the sword prawn Parapenaeopsis hardwickii. Only one shrimp at 8‰ lived, while there was no significant difference in survival rates from salinity 16‰ to 36‰. Growth performances were improved at salinity from 16‰ to 28‰, and the greatest growth performance was predicted to occur at 22.1‰ using the quadratic equation. The haemolymph osmolality of the sword prawn significantly increased with an increase in salinity (from 12 to 36.4‰). The isosmotic point was equivalent to 0.8067OsM kg−1, which corresponds to salinity 27.0‰. The gill Na+-K+-ATPase activities at 12‰ and 16‰ were significantly higher (p < 0.05) than those at 28‰ and 32‰; the lowest gill Na+-K+-ATPase activity was predicted to occur at 27.7‰. The oxygen consumption rate at 16‰ was significantly lower than that at 28‰, the highest oxygen consumption rate was obtained at 28‰, and it slightly decreased at either side of the 28‰ salinity. The ammonia excretion rates at 12‰ and 16‰ were significantly higher than those at salinities from 24‰ to 32‰; it linearly decreased with an increase in salinity from 12 to 36‰. The O/N ratio linearly increased with an increase in salinity from 12 to 36‰. Therefore, the sword prawn subadults can tolerate a range of salinity (12–36‰), and the optimal salinity range was from 20‰ to 28‰. Therefore, the sword prawn can feasibly be cultured in the majority of coastal areas.

Cardiac and respiratory metabolic analysis of low-temperature tolerance in two geographic genotypes of Haliotis diversicolor and the hybrid

Evident survival heterosis exists in the hybrid (HdDY) of two Haliotis diversicolor geographic genotypes (maternal genotype HdTW and paternal genotype HdJP). To explore the physiological basis underlying the heterosis, we compared the survival rate, cardiac performance, oxygen consumption rate, and ammonia excretion rate of the three H. diversicolor genotypes at the low temperature. After one year of cultivation in the abalone farm, the survival rates of HdTW, HdJP, and HdDY were 27.76%, 86.90%, and 88.57%, respectively. The 50% lethal low temperature (LLT50) of HdTW was higher than HdJP and HdDY. During low-temperature exposure, the abalone’s heartbeat variation pattern appeared as three stages: the heartbeat decreasing stage, arrhythmia stage, and cardiac recovery stage. Four cardiac indices were developed to compare the three genotypes’ cardiac differences: the low-temperature heartbeat decreasing rate (LDR), cardiac arrhythmia temperature (CAT), low-temperature heartbeat recovering rate (LRR), and cardiac recovery time (CRT). HdTW had lower LDR and higher CAT than HdJP and HdDY, while HdJP had lower LRR and higher CRT than HdTW and HdDY, suggesting the hybrid’s cardiac function is parent-like in low-temperature tolerance and mother-like in low-temperature recovery. Meanwhile, the heart rates of HdJP and HdDY were always higher than HdTW at both normal temperature (20 °C) and low temperature (12 °C). The oxygen consumption rate and ammonia excretion rate of HdJP and HdDY were also higher than HdTW after low-temperature exposure. The results indicate the hybrid’s advantageous respiratory and metabolic functions at low temperatures, which could be a vital physiological mechanism of the hybrid’s survival heterosis. This study elucidates the cardiac and respiratory metabolic differences among different abalone genotypes at low temperatures, which may help us understand the physiological basis of mollusks’ low-temperature tolerance. The evaluation protocol and indices developed in this study could be helpful in mollusks’ physiological researches, such as the low-temperature tolerance heterosis, low-temperature adaption, and habitat differentiation.

Co-exposure of carbon nanotubes with carbofuran pesticide affects metabolic rate in Palaemon pandaliformis (shrimp)

Palaemon pandalirformis (shrimp) is a species widely distributed in the Brazilian coastal region and with an important economic role. In addition, this organism is considered an indicator of environmental pollution in estuaries; however, its physiological responses to toxic environmental pollutants, including pesticides and nanomaterials, are not well known, mainly, the effects of co-exposure. Thus, the purpose of this study was to evaluate the ecotoxicological effects of co-exposure between oxidized multiwalled carbon nanotubes (HNO3-MWCNT) and carbofuran pesticide on the routine metabolism of P. pandalirformis. The shrimps were exposed to different concentrations of HNO3-MWCNT (0; 10; 100; 500; 1000 μg L−1), carbofuran (0; 0.1; 1.0; 5.0; 10 μg L−1) and to co-exposure with 100 μg L−1 of HNO3-MWCNT + carbofuran (0; 0.1; 1.0; 5.0; 10 μg L−1), to evaluate the effects on metabolic rate (O2 consumption) and excretion of ammonia (NH4+NH3). Our results showed that the shrimps exposed to HNO3-MWCNT (10 μg L−1) increased the metabolic rate by 292% and the excretion of ammonia by 275%; those exposed to carbofuran (10 μg L−1) increased their metabolic rate by 162% and the excretion of ammonia by 425%; and with the co-exposure of HNO3-MWCNT + carbofuran there was also an increase in the metabolic rate by 317% and an excretion of ammonia by 433% when compared to control. These findings provides useful information toward better understanding the physiological responses of shrimps after combined exposure to nanomaterials and pesticides in aquatic environments.

Supplementation of coated and uncoated crystalline amino acid mix in formulating a low‐fishmeal diet for Penaeus monodon (Fabricius, 1798): Effect on growth, digestibility, body composition, haemolymph indices and nitrogen metabolism

A sixty-day feeding trial was conducted to elucidate the effect of coated and uncoated crystalline amino acid mix (CAA) in Penaeus monodon. The control diet (CNT) was formulated with 250 g/kg fishmeal, and three more test diets were prepared by replacing 50% (125 g/kg) of fishmeal (w/w) using a blend of plant proteins with no supplementation of CAA (AA-NL), supplementation of uncoated (AA-NC) and coated (AA-CT) CAA. The AA-CT diet showed (p < .05) lower leaching of amino acids (1.13%) than other diets (2.78%–3.04%). DGC was high (p < .05) in shrimp fed on CNT and AA-CT (1.48%–1.49%/day) than other groups (1.32%–1.37%/day). Of all the treatments, FCR was poor (p < .05) in AA-NL (2.25). The dietary treatments did not influence survival (p = .841) and whole-body composition. The peak of free amino acid was synchronized (60 min) between AA-CT and CNT groups. The control group showed a higher nitrogen intake, oxygen consumption and O:N ratio and lower ammonia-N excretion. Haemolymph indices varied (p < .05) among the dietary groups. As a result of the N-metabolism study, the experimental diets were ranked as CNT>AA-CT>AA-NC. In conclusion, a blend of CAA could be effective in formulating low-fishmeal diets and could replace 50% (125 g/kg) of dietary fishmeal using a plant protein mix in P. monodon.

Mechanistic insights into ureolysis mediated calcite precipitation

Microbially induced calcite precipitation (MICP) has applications in self-healing concrete, soil consolidation and bio-grouting. Development of models of processes involved in MICP is a step towards gaining mechanistic insights and building reliable predictive models of MICP. This work deals with understanding the reactions and transport processes involved in ureolysis mediated calcite precipitation in Sporosarcina pasteurii (S. pasteurii). Particularly, a simple structured model that describes urea uptake, ureolysis, ammonium assimilation and ammonium excretion processes is developed. The structured model describes extra-cellular processes like transport processes and important intra-cellular reactions involved in ureolysis. The model parameters are estimated using measured concentrations of extracellular and intracellular metabolites during experiments. In this work, The maximum specific growth rate and yield coefficient of S. pasteurii are found to be 0.78 d−1 and 4.93 gDW/g, respectively. The maximum urease activity of 1.79 μmoles/min/gDW biomass was observed during the fourth day of growth when grown in minimal media. It is shown that the urea uptake can be described by a first-order kinetics suggesting active transport. The estimated parameter of rate constant of first-order kinetics is 9.8 × 10−2d−1. On the other hand, the ammonium ion excretion takes place through free diffusion. The estimated parameter of permeability coefficient for ammonium ion diffusion is 9.2 × 10−3 m d−1.