Routine Metabolism Research Articles

Parental early life environments drive transgenerational plasticity of offspring metabolism in a freshwater fish (Danio rerio).

Parental experiences can lead to changes in offspring phenotypes through transgenerational plasticity (TGP). TGP is expected to play a role in improving the responses of offspring to changes in climate, but little is known about how the early lives of parents influence offspring TGP. Here, we use a model organism, zebrafish (Danio rerio), to contrast the effects of early and later life parental thermal environments on offspring routine metabolism. To accomplish this, we exposed both parents to either constant optimal (27°C) or environmentally realistic diel fluctuating (22-32°C) temperatures during early (embryonic and larval) and later (juvenile and adult) life in a factorial design. We found significant reduction of routine metabolic rates (greater than 20%) at stressful temperatures (22°C and 32°C) after biparental early life exposure to fluctuating temperatures, but little effect of later life parental temperatures on offspring metabolism. This reduction reflects metabolic compensation and is expected to enhance offspring body sizes under stressful temperatures. These changes occur over and above the effects of parental environments on egg size, suggesting alternate non-genetic mechanisms influenced offspring metabolic rates.

Application of a stoichiometric bioenergetic approach and whole-body protein synthesis to the nutritional assessment of juvenile Thenus australiensis

The present study successfully combined a stoichiometric bioenergetic approach with an endpoint stochastic model to simultaneously determine specific dynamic action, metabolic substrate use and whole-body protein synthesis in juvenile slipper lobster Thenus australiensis. Juvenile lobsters were fasted for 48 h to investigate routine metabolism before receiving a single meal of formulated feed containing 1% 15N-labeled Spirulina. Postprandial oxygen consumption rate, dissolved inorganic carbon, and total nitrogen excretion returned to the pre-feeding level within 24 h. The rate of whole-body protein synthesis was 0.76 ± 0.15 mg CP g−1 day−1, with a significant reduction from 24 to 48 h post-feeding. The postprandial increase in whole-body protein synthesis accounted for 13–19% of total oxygen uptake. Protein was the primary energy substrate for 48 h fasted (45% oxygen consumption) and post-feeding lobster (44%), suggesting that dietary protein was not efficiently used for growth. The secondary energy substrate differed between carbohydrates in 48 h fasted and lipids in post-feeding lobsters. The present study recommends integrating protein synthesis into protein requirement experiments of marine ectotherms to acquire a more comprehensive picture of protein and energy metabolism and nutritional physiology crucial for formulating cost-effective aquafeeds.

High PCO2does not alter the thermal plasticity of developing Pacific herring embryos during a marine heatwave.

ABSTRACTForage fish tend to respond strongly to environmental variability and therefore may be particularly sensitive to marine climate stressors. We used controlled laboratory experiments to assess the vulnerability of Pacific herring (Clupea pallasii) embryos to the combined effects of high partial pressure of carbon dioxide (PCO2) and a simulated marine heatwave. The two PCO2 treatments reflected current conditions (∼550 µatm) and a future extreme level (∼2300 µatm). The dynamics of the heatwave (i.e. rate of onset: ∼0.85°C day−1; maximum intensity: +4.4°C) were modeled from the most extreme events detected by a long-term regional temperature dataset. Simultaneous exposure to these potential stressors did not affect embryo survival. However, the heatwave did elicit significant metabolic effects that included higher rates of routine metabolism (Q10=1.15–1.72), growth (Q10=1.87), rate of development to hatch (Q10=3.01) and yolk consumption (Q10=3.21), as well as a significant reduction in production efficiency (−10.8%) and a three-fold increase in the rate of developmental anomalies. By contrast, high PCO2 conditions produced comparatively small effects on vital rates, including a significant increase in time to hatch (+0.88 days) and a reduction in routine metabolic rate (−6.3%) under the ambient temperature regime only. We found no evidence that high PCO2 increased routine metabolic rate at either temperature. These results indicate that Pacific herring embryos possess sufficient physiological plasticity to cope with extreme seawater acidification under optimal and heatwave temperature conditions, although lingering metabolic inefficiencies induced by the heatwave may lead to important carryover effects in later life stages.

BIOENERGETICA DEL LANGOSTINO Macrobrachium tenellum (SMITH, 1871) EN FUNCION DE LA SALINIDAD DEL AGUA

<p><strong>Background. </strong>The <em>Macrobrachium tenellum</em> prawn is captured and commercialized by local fishermen along its distribution interval. It is considered an euryhaline palemonid prawn. If its cultivation is wanted, the best conditions for its growth and reproduction should be investigated, including proper intervals of temperature, salinity, density and dissolved oxygen. <strong>Objective.</strong> To determine the effect of two different salinities (0 and 15PSU) on the physiological rates that balance the energy equation in <em>M. tenellum</em> adults and to determine if energy use is more efficient under isosmotic conditions. <strong>Methodology</strong>. Specimens were collected in Guasave, Sinaloa, Mexico, in July 2018 and taken to the Aquaculture Laboratory at UAdeO. The energy balance was calculated in hyposmotic (0 PSU) and isosmotic (15 PSU) conditions at preferred temperature (28.5 ± 1 ° C). The energy invested in respiration and excretion, the feces lost and the ingested food and the growth potential was calculated using a semi-open respirometer. <strong>Results.</strong> The highest energy expenditure occurred in the respiratory rate (routine metabolism), then feces production and finally ammonia production in both salinities. The highest total energy expenditure was observed in fresh water. The highest amount of energy directed to the growth or reproduction was observed in brackish water (15 PSU), as well as the highest rate of food ingestion. <strong>Implications.</strong> Knowledge on the use of energy in the feed in the best saline condition for its cultivation useful for culture purposes. <strong>Conclusion.</strong> The saline condition in where more energy is channeled for the growth of <em>M. tenellum</em> is 15UPS (isosmotic point) and in it is also in where less energy is spent.</p>

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.

Intracranial Sensors for Continuous Monitoring of Neurophysiology

AbstractMonitoring physiological parameters in the brain is important to identify early signs of secondary brain injuries. A variety of different intracranial sensors enable continuous monitoring of important brain parameters in clinical applications. However, many of the clinically approved and established technologies show drawbacks in zero‐drift properties, accuracy and magnet resonance imaging (MRI) compatibility. This review gives a comparative overview of the established technologies and provides an outlook on fiber‐optic sensors (FOS) with potential use in future intracranial monitoring applications. Neurophysiological parameters recorded by bioelectrical signals include intracranial pressure (ICP), brain temperature, brain tissue oxygenation, cerebral blood flow, and cerebral metabolism. The comparison of ICP sensors revealed that piezoresistive strain gauge sensors provide the highest accuracy and the smallest zero‐drift in clinical catheters. Fiber‐optic pressure sensors show a potential to be used in future intracranial applications. Thermistors and thermocouples prove to be reliable for temperature measurement in intracranial catheters, but have limited MRI compatibility. FOS show potential to be used in future intracranial catheters for temperature and oxygen measurement, as they provide higher accuracy and a better response time. Microdialysis catheters, in combination with new automated electrochemical and optical analyzers, provide the possibility of routine metabolism monitoring in clinics.

Expression of ion transport proteins and routine metabolism in juveniles of tropical gar (Atractosteus tropicus) exposed to ammonia

Tropical gar (Atractosteus tropicus) thrives in aquatic habitats with high levels of total nitrogen (TAN) and unionized ammonia (NH3). However, the tolerance of TAN and NH3, the excretion mechanisms involved, and the effects of these chemicals on routine metabolism are still unknown. Therefore, our objectives were to assess the acute toxicity of TAN and NH3 in A. tropicus juveniles after a 96-h exposure (LC50-96 h) to NH4Cl and after chronic exposure to two concentrations (15% and 30% of LC50-96 h TAN) for 12 days, as well as to evaluate the transcriptional effects associated with Rhesus proteins (rhag, rhbg, rhcg) and ion transporters (NHE, NKA, NKCC, and CFTR) in gills and skin; and to determine the effects of TAN and NH3 on routine metabolism through oxygen consumption (μM g-1 h-1) and gill ventilation frequency (beats min-1). LC50-96 h values were 100.20 ± 11.21 mg/L for TAN and 3.756 ± 0.259 mg/L for NH3. The genes encoding Rhesus proteins and ion transporters in gills and skin showed a differential expression according to TAN concentrations and exposure time. Oxygen consumption on day 12 showed significant differences between treatments with 15% and 30% TAN. Gill ventilation frequency on day 12 was higher in fish exposed to 30% TAN. In conclusion, A. tropicus juveniles are highly tolerant to TAN, showing upregulation of the genes involved in TAN excretion through gills and skin, which affects routine oxygen consumption and energetic cost. These findings are relevant for understanding adaptations in the physiological response of a tropical ancestral air-breathing fish.

An approach to integrating specific dynamic action (SDA) with routine metabolism for improved estimation of the realistic metabolism of marine metazooplankton in the field

An increase in respiration (RSDA) associated with food ingestion (I) was estimated from routine rates (Rroutine) determined in the absence of food with sealed-chamber methods. Based on regression analyses of RSDA on I for metazooplankton in the laboratory, the fraction of I allocated to RSDA was calculated to be 0.10. Likely food ingestion of metazooplankton in the field (Ifield) was derived from “basic balanced equations” in which parameters such as Rroutine, laboratory-obtained food absorption efficiency (AE) and gross growth efficiency (K1) were incorporated (I&M model). Based on differences in AE values, metazooplankton were separated into particle-feeders (herbivores, omnivores) and carnivores and RSDA was computed to be 0.37 times Rroutine for the former and 0.25 times Rroutine for the latter. Hence, realistic respiration rates of metazooplankton feeding in the field (Rfield = RSDA + Rroutine) accounted for 1.37 times Rroutine for particle-feeders and 1.25 times Rroutine for carnivores. The increase in ammonia excretion (ESDA) accompanied by SDA in particle-feeders and carnivores was calculated from RSDA coupled with carbon-to-nitrogen (C:N by mass) ratios of possible natural foods (6.5 for the former and 4.5 for the latter). Results indicated that ESDA is 0.080 times RSDA for particle-feeders, and 0.116 times RSDA for carnivores.

Thermal reaction norms of key metabolic enzymes reflect divergent physiological and behavioral adaptations of closely related amphipod species

Lake Baikal is inhabited by more than 300 endemic amphipod species, which are narrowly adapted to certain thermal niches due to the high interspecific competition. In contrast, the surrounding freshwater fauna is commonly represented by species with large-scale distribution and high phenotypic thermal plasticity. Here, we investigated the thermal plasticity of the energy metabolism in two closely-related endemic amphipod species from Lake Baikal (Eulimnogammarus verrucosus; stenothermal and Eulimnogammarus cyaneus; eurythermal) and the ubiquitous Holarctic amphipod Gammarus lacustris (eurythermal) by exposure to a summer warming scenario (6–23.6 °C; 0.8 °C d−1). In concert with routine metabolic rates, activities of key metabolic enzymes increased strongly with temperature up to 15 °C in E. verrucosus, whereupon they leveled off (except for lactate dehydrogenase). In contrast, exponential increases were seen in E. cyaneus and G. lacustris throughout the thermal trial (Q10-values: 1.6–3.7). Cytochrome-c-oxidase, lactate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase activities were found to be higher in G. lacustris than in E. cyaneus, especially at the highest experimental temperature (23.6 °C). Decreasing gene expression levels revealed some thermal compensation in E. cyaneus but not in G. lacustris. In all species, shifts in enzyme activities favored glycolytic energy generation in the warmth. The congruent temperature-dependencies of enzyme activities and routine metabolism in E. verrucosus indicate a strong feedback-regulation of enzymatic activities by whole organism responses. The species-specific thermal reaction norms reflect the different ecological niches, including the spatial distribution, distinct thermal behavior such as temperature-dependent migration, movement activity, and mating season.

Non-invasive MRI Studies of Ventilatory and Cardiovascular Performance in Edible Crabs Cancer pagurus During Warming Under Elevated CO2 Levels.

The thermal tolerance of marine decapod crustacea is defined through their capacities for oxygen uptake and distribution. High ambient CO2 levels were previously shown to reduce hemolymph oxygen levels at enhanced cardiac performance during warming. This study investigated the impacts of warming under two CO2 levels on ventilation and hemolymph circulation in edible crabs Cancer pagurus. It also highlights changes in the ventilatory and cardiac pauses displayed by Decapoda under routine metabolism. Animals were exposed to step-wise, sub-critical warming (12–20°C over 5 days) under control (470 μatm) and high (1,350 μatm) water PCO2. Flow-through respirometry was combined with magnetic resonance imaging and infra-red photoplethysmography to allow for simultaneous, non-invasive measurements of metabolic rates (), ventilation and cardiovascular performance. Crabs spent significantly more time in a low state (metabolic pause), when experiencing high CO2 conditions above 16°C, compared to normocapnic warming. Heart rates leveled off beyond 18°C at any CO2 level. Cardiac output continued to increase with high-CO2-warming, due to elevated cardiac stroke volumes. Consequently, temperature-dependent branchial hemolymph flow remained unaffected by CO2. Instead, a suppressing effect of CO2 on ventilation was found beyond 16°C. These results indicate constrained oxygen uptake at stable cardiovascular performance in a decapod crustacean.Cancer pagurus: urn:lsid:zoobank.org:act:B750F89A-84B5-448B-8D80-EBD724A1C9D4

Impacts on Metabolism and Gill Physiology of Darter Species (Etheostoma spp.) That Are Attributed to Wastewater Effluent in the Grand River

The effluent from municipal wastewater treatment plants is a major point source of contamination in Canadian waterways. The improvement of effluent quality to reduce contaminants, such as pharmaceuticals and personal care products, before being released into the environment is necessary to reduce the impacts on organisms that live in the river downstream. Here, we aimed to characterize the metabolic and gill physiological responses of rainbow (Etheostoma caeruleum), fantail (Etheostoma flabellare), and greenside (Etheostoma blennioides) darters to the effluent in the Grand River from the recently upgraded Waterloo municipal wastewater treatment plant. The routine metabolism of darters was not affected by effluent exposure, but some species had increased maximum metabolic rates, leading to an increased aerobic scope. The rainbow darter aerobic scope increased by 2.2 times and the fantail darter aerobic scope increased by 2.7 times compared to the reference site. Gill samples from effluent-exposed rainbow darters and greenside darters showed evidence of more pathologies and variations in morphology. These results suggest that darters can metabolically adjust to effluent-contaminated water and may also be adapting to the urban and agricultural inputs. The modification and damage to the gills provide a useful water quality indicator but does not necessarily reflect how well acclimated the species is to the environment due to a lack of evidence of poor fish health.

First estimates of metabolic rate in Atlantic bluefin tuna larvae.

Atlantic bluefin tuna is an iconic scombrid species with a high commercial and ecological value. Despite their importance, many physiological aspects, especially during the larval stages, are still unknown. Metabolic rates are one of the understudied aspects in scombrid larvae, likely due to challenges associated to larval handling before and during respirometry trials. Gaining reliable estimates of metabolic rates is essential to understand how larvae balance their high growth needs and activity and other physiological functions, which can be very useful for fisheries ecology and aquaculture. This is the first study to (a) estimate the relationship between routine metabolic rate (RMR) and larval dry weight (DW) (mass scaling exponent) at a constant temperature of 26°C, (b) measure the RMR under light and darkness and (c) test whether the interindividual differences in the RMR are related to larval nutritional status (RNA/DNA and DNA/DW). The RMR scaled nearly isometrically with body size (b = 0.99, 0.60-31.56 mg DW) in contrast to the allometric relationship observed in most fish larvae (average b = 0.87). The results show no significant differences in larval RMR under light and darkness, suggesting similar larval activity levels in both conditions. The size explained most of the variability in RMR (97%), and nutritional condition was unrelated to the interindividual differences in routine metabolism. This is the first study to report the metabolic rates of Atlantic bluefin tuna larvae and discuss the challenges of performing bioenergetic studies with early life stages of scombrids.

Routine metabolism of Antarctic krill (Euphausia superba) in South Georgia waters: absence of metabolic compensation at its range edge

Routine respiration rates in the South Georgia stock of Antarctic krill (Euphausia superba) were measured to compare with previously published measurements on stocks from colder locations further south. Within the natural temperature range of this species (− 1.8° to 5.5 °C), respiration rate data from both the present and previous studies were adequately fitted by a single Arrhenius regression (Q10 of 2.8), although South Georgia krill showed an upward deviation from this regression between 0° and 2 °C (the lower temperature range at South Georgia). Metabolic compensation (i.e. the comparative lowering of respiration rate) at the high temperatures experienced at South Georgia was not apparent, although the higher than predicted metabolic rates at low temperatures suggests acclimation of South Georgia krill to a warm water lifestyle. Weight-specific respiration rate was significantly higher in sub-adults and adults compared to juveniles, highlighting the metabolic burden of reproduction. South Georgia krill showed no further increase in respiration rate when exposed to acute temperatures (5.5–12.2 °C), indicating that they were already at the limit of aerobic capacity by 5.5 °C. Overall, this study shows that even small degrees of additional warming to South Georgia waters are likely to make conditions there metabolically unsustainable for Antarctic krill.

Activity alters how temperature influences intraspecific metabolic scaling: testing the metabolic-level boundaries hypothesis.

A common belief is that the body-mass scaling of metabolic rate is the result of intrinsic (physical) constraints related to body design. However, many recent studies have shown that extrinsic (ecological) factors significantly affect metabolic scaling relationships, both within and among species. One of these factors is ambient temperature (T), but its influence on the intraspecific (ontogenetic) scaling slope (b) of metabolic rate varies widely. I tested whether the metabolic-level boundaries hypothesis (MLBH) can explain this variation, at least in part. The MLBH predicts that b should correlate negatively with T for resting metabolism, but show variable associations (from negative to positive) for metabolism measured during varying levels of locomotor activity. I tested the MLBH by using a literature survey of T effects on b for resting or routine metabolic rates of 179 animal and plant species. As predicted, sedentary species of ectothermic animals and plants exhibiting no locomotor activity mostly show negative associations between b and T, whereas mobile species exhibiting various low levels of uncontrolled, spontaneous, routine locomotor activity during measurements of resting or routine metabolism show varied associations. A similar difference occurs between teleost fish species exhibiting no locomotor activity versus varying levels of routine locomotor activity. These results show that intrinsic and extrinsic factors (e.g., activity and ambient temperature, respectively) can interactively affect metabolic scaling. Metabolic scaling is highly malleable, and not the simple result of universal physical constraints.

Thermal Tolerance and Metabolism of Archocentrus nigrofasciatus Acclimated to a Large Daily Temperature Fluctuation Reflect its Success as an Invasive Species

Fish exhibit thermal tolerance and metabolism correlated to recent thermal history, and more studies should examine species’ responses to large fluctuations in daily temperatures. We compared thermal tolerance and metabolic responses between fish acclimated to constant temperatures and a large, daily thermal cycle of 10°C. Black Convict cichlid (Archocentrus nigrofasciatus) is a freshwater teleost native to Central America, with non‐native populations established in numerous locations. Black Convict cichlid were acclimated for two weeks to constant 20°C or 30°C, or a daily cycle of 20–30°C (“cycling group”, ~0900–1500 hrs). Following acclimation, routine metabolism (oxygen consumption, Mo2) and Critical thermal maxima/minima (CTmax/CTmin) were measured. Critical thermal limits were compared via ANOVA, with the cycling group sampled from both the daily minimum at 20°C (0900 hrs) and daily maximum at 30°C (1600 hrs). CTmax (0.3°C per degree of acclimation) and CTmin (0.4 °C per degree of acclimation) increased with acclimation. CTmax for the cycling group were 0.7°C higher when sampled from the maximum 30°C (39.3°C) of the daily cycle compared to 20°C (38.6°C). CTmin values for the cycling group were 2.2°C higher when sampled from the maximum 30°C (14.6°C) of the daily cycle compared to 20°C (12.4°C). Mo2 was measured acutely at 20°C and 30°C for each acclimation group, with the cycling group sampled from the daily minimum at 20°C (0900 hrs) and daily maximum at 30°C (1600 hrs). ANOVA showed that mass‐specific Mo2 decreased with increasing acclimation temperature for fish measured acutely at 30°C, where fish acclimated to 20°C (Mo2 = 0.329 mg/h/g) demonstrated an 84% higher Mo2 than fish acclimated to 30°C (Mo2 = 0.178 mg/h/g). Mass‐specific Mo2 also decreased with increasing acclimation temperature for fish measured acutely at 20°C, where fish acclimated to 20°C (Mo2 = 0.170 mg/h/g) demonstrated a 139% higher Mo2 than fish acclimated to 30°C (Mo2 = 0.071 mg/h/g). Mo2 was measured continually across the 24h daily thermal acclimation cycle of 20 – 30°C for all groups. Total oxygen consumption across the 24h cycle was highest for the constant 30°C group naively exposed to the cycle and lowest for the cycling group. Black Convict cichlid retains more upper thermal tolerance than lower thermal tolerance with altered thermal acclimation, and this hardy species shows metabolic compensation following high temperature acclimation (30°C) and large, daily cycling temperature acclimation (20 – 30°C). These aspects of fish thermal physiology phenotypes are reflective of a successful invasive fish species that may respond more robustly to impacts from anthropogenic climate change.Support or Funding InformationFunding was provided through startup funds to JE from CSUSM.

The combination of low salinity and low temperature can limit the colonisation success of the non-native bivalve Rangia cuneata in brackish Baltic waters

We studied the behavioural (burrowing and valves gaping) and metabolic responses of Atlantic rangia Rangia cuneata (G.B. Sowerby I, 1832) at different salinities and temperatures. Three salinities (S = 0.5, 7.0, 10.0) were tested at 20 °C, with an additional control of 2.4. The control salinity (S = 2.4) was also tested at 10 °C to examine responses specific to colder temperatures. Clams exposed to the lowest (S = 0.5, T = 20 °C) and the highest salinity (S = 10.0, T = 20 °C), as well as lower temperature (T = 10 °C, S = 2.4) significantly (p < .05) reduced the rate of routine metabolism. At the lowest salinity (S = 0.5, T = 20 °C) and temperature (T = 10 °C, S = 2.4), they were also more abundant on the surface of the sediment, however the differences in relation to control conditions (S = 2.4, T = 20 °C) were not significant (p > .05). Clams kept their shells open in the lowest salinity, but closed in the highest salinity and at lower temperature. The closure time was longer in salinity of 10.0 than at temperature of 10 °C, where the highest reduction in the metabolic rate occurred in relation to the control conditions. This latter fact, in combination with shell closure, may indicate the activation of an anaerobic pathway. Thus, in the long term, lower temperatures may adversely affect R. cuneata, especially at very low salinity (S = 0.5, 2.4), in which this hyper-osmoregulating species has to strongly pump water with ions and oxygen to compensate for energy demand. In salinity of 10.0, where the species is isosmotic to the environment, changes in behaviour (moving to the sediment surface and closing the shell) with a simultaneous reduction in the metabolic rate may be due to lower costs of osmoregulation. Our results may help explain the strong inter-annual fluctuations in the population size of this subtropical species in the Baltic coastal waters resulting from the mass mortality of adults after long winters.

Mitochondria, sex and variation in routine metabolic rate.

Variation in the metabolic costs associated with organismal maintenance may play a key role in determining fitness, and thus these differences among individuals are likely to be subject to natural selection. Although the evolvability of maintenance metabolism depends on its underlying genetic architecture, relatively little is known about the nature of genetic variation that underlies this trait. To address this, we measured variation in routine metabolic rate (ṀO2routine ), an index of maintenance metabolism, within and among three populations of Atlantic killifish, Fundulus heteroclitus, including a population from a region of genetic admixture between two subspecies. Polygenic association tests among individuals from the admixed population identified 54 single nucleotide polymorphisms (SNPs) that were associated with ṀO2routine , and these SNPs accounted for 43% of interindividual variation in this trait. However, genetic associations with ṀO2routine involved different SNPs if females and males were analysed separately, and there was a sex-dependent effect of mitochondrial genotype on variation in routine metabolism. These results imply that there are sex-specific genetic mechanisms, and potential mitonuclear interactions, that underlie variation in ṀO2routine . Additionally, there was evidence for epistatic interactions between 17% of the possible pairs of trait-associated SNPs, suggesting that epistatic effects on ṀO2routine are common. These data demonstrate not only that phenotypic variation in this ecologically important trait has a polygenic basis with considerable epistasis among loci, but also that these underlying genetic mechanisms, and particularly the role of mitochondrial genotype, may be sex-specific.

METABOLIC AND HISTOLOGICAL ALTERATIONS AFTER EXPOSING Deuterodon iguape TO DIFFERENT SALINITIES

The decrease of the live bait stock for the sport fishing, in estuarine and marine environments, has stimulated studies looking for species tolerant to the different salinities. Lambari Deuterodon iguape Eigenmann, 1907 has been widely used as live bait in Brazilian estuaries has a significant market and being a native animal to Brazil, it becomes a promising substitute. In order to analyze tolerance, the objective was to evaluate routine metabolism (oxygen consumption and ammonia excretion), hematological parameters (glucose, hemoglobin and total proteins), and histological parameters (gills and kidneys) of D. iguape after exposure to different salinities. The data were evaluated according to the means and standard deviations obtained by ANOVA (one-way) analysis followed by the Tukey post-test, after verification of the normal distributions (Kolmogorov-Smirnov test) and homoscedasticity (Levene test), p&lt;0.05. In the higher salinities (12.5) tested, increased oxygen consumption, serum glucose, hemoglobin levels, decreased ammonia and total protein excretion were observed. It was concluded that 1 hour of exposure to different salinities, changes the metabolism of D. iguape, characterized by increased oxygen consumption and decreased ammonia excretion. Changes in hematological parameters (serum glucose, hemoglobin, and total protein) are also observed in groups exposed in the higher salinities (7.5, 10 and 12.5). Gill and kidney histological alterations were classified as mild to moderate, showing that D. iguape adapted well to the saline environment, which can make its use as live bait possible in estuarine sport fishing, preserving the natural stocks of Litopenaeus schimitti shrimp.

Analysis of relevant between iron metabolism indexes and intelligence quotient for primary school students in Dongxiang Nationality and Han Nationality of Gansu

Objective To investigate the correlation between iron metabolism index and intelligence development of Dongxiang and Han students in Dongxiang county and Lanzhou city of Gansu province. Methods A total of 396 students aged from 6 to 11 years old were randomly selected for venous blood collection from two primary schools with Dongxiang and Han children in Dongxiang county and Lanzhou city.Blood routine and serum iron metabolism indicators were detected and iron metabolism indicators from different ethnic groups were analyzed.Students diagnosed with iron deficiency anemia(IDA) named as IDA group, and students without IDA who had similar background were enrolled in the control group.The correlation between iron metabolism index and intelligence quotient was analyzed. Results The ferritin level of Dongxiang students(51.81 μg/L)was lower than that of Han students(65.73 μg/L), and total iron binding capacity of students in Dongxiang county [(65.04±6.68) μmol/L] was higher than that of students in Lanzhou city[(59.92±5.91) μmol/L]. The transferrinsaturation of students in Dongxiang county[0.23(0.19~0.30)] was lower than that of students in Lanzhou city[0.26(0.20~0.32)]. The differences were statistically significant(P<0.05). Analysis of multiple linear regression showed that ferritin and serum iron were correlated to intelligence quotient score of the IDA students(P<0.05). Conclusion Ferritin and serum iron are associated with primary school students′ intelligence quotient.Religious practice, regional economic and cultural level have a certain influence on iron metabolism of local primary school students.It is very important to strengthen the supplement of dietary iron in primary school students in Dongxiang County and reduce the prevalence of iron deficiency. Key words: Iron metabolism indexes; Intelligent development; Primary school students; Dongxiang nationality; Han nationality

Co-exposure of graphene oxide with trace elements: Effects on acute ecotoxicity and routine metabolism in Palaemon pandaliformis (shrimp)

Graphene oxide (GO) has been evaluated for application in environmental remediation and pollution control strategies. However, the side effects caused by the interactions of GO with classical pollutants in aquatic environments are still largely unknown. In this work, the ecotoxicological effects of GO, cadmium, zinc and the interactions between GO and these trace elements (co-exposure) were evaluated through acute toxicity tests and routine metabolism (i.e., oxygen consumption and ammonia excretion) in Palaemon pandaliformis (shrimp). After 96 h of exposure, GO did not present acute ecotoxicity at concentrations up to 5.0 mg L−1. However, the association of GO with Cd or Zn increased the toxicity of these trace elements as demonstrated by the decrease in LC50 values. The 96 h LC50 of Cd associated with GO was 1.7 times less than the 96 h LC50 of Cd alone. Similarly, the 96 h LC50 of Zn associated with GO was 1.8 times less than the 96 h LC50 of Zn alone. Additionally, the co-exposure of GO with trace elements impaired the routine metabolism of P. pandaliformis. Finally, the GO potentiated the ecotoxicological effects of Cd and Zn in the shrimp model. Future research on this emerging nanomaterial should focus on its use and disposal in aquatic ecosystems.