Effects of temperature and salinity on the standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi

The standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi to changes in temperature (15-30 °C), salinity (0-45‰) and a combination thereof was investigated. The rate of oxygen consumption of the shrimp was determined using a YSI oxygen meter. At a constant salinity of 35‰ the respiration rate of P. peringueyi increased with an increase in temperature and ranged between 0.260 and 0.982 μl O₂ mg wwt^− 1 h^− 1. The Q₁₀ value over the temperature range 15-25 °C was estimated at 3.13. At a constant temperature of 15 °C the respiration rate of P. peringueyi also increased with an increase in salinity and ranged between 0.231 and 0.860 μl O₂ mg wwt^− 1 h^− 1. For combination experiments the absence of any significant difference in the respiration rate of P. peringueyi at the four temperatures over the salinity range 15-35‰ suggests that the shrimp is well adapted to inhabiting environments characterised by variations in salinity and temperature such as those encountered within the middle and lower reaches of permanently open estuaries with substantial freshwater inflow. On the other hand, the total mortality of the shrimp recorded at salinities < 5‰ at all four temperatures suggests that the upper distribution of the shrimp may reflect physiological constraints. Similarly, the increase in the respiration rate of the shrimp at the four temperatures at salinities > 35‰ suggests that the shrimp may experience osmotic stress in freshwater deprived permanently open and intermittently open estuaries where hypersaline conditions may develop.     

An information-theoretic approach to evaluating the size and temperature dependence of metabolic rate

The effects of body mass and temperature on metabolic rate (MR) are among the most widely examined physiological relationships. Recently, these relationships have been incorporated into the metabolic theory of ecology (MTE) that links the ecology of populations, communities and ecosystems to the MR of individual organisms. The fundamental equation of MTE derives the relation between mass and MR using first principles and predicts the temperature dependence of MR based on biochemical kinetics. It is a deliberately simple, zeroth-order approximation that represents a baseline against which variation in real biological systems can be examined. In the present study, we evaluate the fundamental equation of MTE against other more parameter-rich models for MR using an information-theoretic approach to penalize the inclusion of additional parameters. Using a comparative database of MR measurements for 1359 species, from 11 groups ranging from prokaryotes to mammals, and spanning 16 orders of magnitude in mass and a 59°C range in body temperature, we show that differences between taxa in the mass and temperature dependence of MR are sufficiently large as to be retained in the best model for MR despite the requirement for estimation of 22 more parameters than the fundamental equation of MTE.     

Effect of body mass and water temperature on the standard metabolic rate of juvenile yellow perch, Perca flavescens (Mitchill)

Fish respiration rates that are presumed to represent standard metabolic rates (SMR) may sometimes include an unspecified energy expenditure associated with activity and digestion. This situation may introduce a bias in bioenergetics models because standard metabolism, digestion, and activity may not be affected by the same environmental conditions. The aim of this study was to (1) develop a SMR model for juvenile yellow perch, Perca flavescens (Mitchill), that represent the minimum energy expenditure required to maintain life and (2) compare the results of this study with published perch metabolic rates and bioenergetics models. SMR was estimated for yellow perch over a range of body␣mass (4.4–24.7 g) and water temperature (12–20°C). The intercept of the relationship between fish respiration and swimming velocity obtained during forced swimming experiments was used to determine SMR. SMR estimated by the present study were comparable to values presented by two published studies on Eurasian perch, Perca fluviatilis L. However, estimated SMR were 4.1–20.9 times lower than values of a third respirometry study and predictions of bioenergetics models for perch. The present study suggests that published SMR models may sometimes include a significant fraction of energy expenditures (39.2–75.9%) associated with digestion and activity. This may complicate the implementation and the interpretation of fish bioenergetics models. The present study indicates that the intercept of respiration-velocity relationships and long-term respiration rates during starvation experiments may provide similar and reliable SMR values.     

Effect of temperature on metabolic rate of the mud turtle (Kinosternon subrubrum)

Temperature plays an important role in various aspects of the life history and physiology of ectotherms. We examined the effect of temperature on standard metabolic rate in the mud turtle, Kinosternon subrubrum. We measured O₂ consumption and CO₂ production at 20°C and 30°C using a flow through respirometery system. Standard metabolic rate was significantly higher at 30°C (9.25 ml O₂/h, 6.35 ml CO₂/h) compared to 20°C (2.10 ml O₂/h, 1.96 ml CO₂/h). The Q₁₀ value for O₂ was 5.10, and for CO₂ was 3.40. Our findings generally agree with those of other studies of metabolism in vertebrate ectotherms.     

体重和温度对褐牙鲆标准代谢的影响

研究表明,褐牙鲆标准代谢率随体重的增加而增加,二者呈幂函数关系;褐牙鲆标准代谢率随温度的升高而增加,二者为指数关系;褐牙鲆标准代谢率与体重和温度的关系用Rs=0.2340W^0.6695e^0.0372T表示。体重和温度对褐牙鲆的标准代谢率没有显著的交互作用。     

Metabolic responses of sand fiddler crabs, Uca pugilator, in northwest Florida to seasonal temperature change

Metabolic responses of sand fiddler crab, Uca pugilator, populations in northwest Florida are greatly influenced by seasonal temperature fluctuations. Crabs acclimated at 20 °C and immediately transferred to either 14 or 26 °C produced an acute metabolic response with respective temperature quotient (Q₁₀) values of 3.46 and 3.91. Crabs acclimated at 10 and 20 °C exhibited a Q₁₀ of 2.62 indicating a partial compensation response. A brumation (reverse) response (Q₁₀ value of 20.11) was observed for acclimated crabs between 5 and 10 °C. Brumation is advantageous during winter when food supplies are scarce and crabs must survive extensive periods of inactivity.     

Lack of correlation between body mass and metabolic rate in Drosophila melanogaster

We examined the association between body mass and metabolic rate in Drosophila melanogaster under a variety of conditions. These included comparisons of body mass and metabolic rate in flies from different laboratory lines measured at different ages, over different metabolic sampling periods, and comparisons using wet versus dry mass data. In addition, the relationship between body mass and metabolic rate was determined for flies recently collected from wild populations. In no case was there a significant correlation between body mass and metabolic rate. These results indicate that care must be taken when attempting to account for the effects of body mass on metabolic rate. Expressing such data in mass-specific units may be an inappropriate method of attempting to control for the effects of differences in body mass.     

The reversible depletion and reconstitution of a copper ion in Coprinus cinereus laccase followed by spectroscopic techniques

The specific activities of crude and purified Coprinus cinereus laccase preparations could be enhanced by a factor of 10-12 by activation with copper ions. The copper to protein contents of purified non-activated laccase were 2.3 ± 0.1 compared to 3.3 ± 0.1 in purified activated laccase indicating that only a fraction of the laccase can be activated. Purified laccase not activated with copper ions shows in isoelectric focusing four bands in order of decreasing pI in a ratio 1/5/3/1 where only bands I and II had laccase activity. Purified activated laccase showed only three bands (I, II and III) in the ratio 5/4/1 all with some laccase activity. The pH profile of the activity for activated and non-activated laccase showed identical behavior indicating that the active forms were the same. The change in UV-Vis around 330 nm following the depletion and reconstitution of the enzyme combined with activity measurements supports the reversibility of the selective removal and insertion of copper ions at the type 2 site. The circular dichroism spectrum of activated purified laccase has characteristic changes around 350 nm relative to non-activated laccase indicative of changes at the type 2/type 3 sites. The difference between the electron paramagnetic resonance spectra of non-activated and activated C. cinereus laccase indicates that a fraction of the non-activated purified laccase contained a copper(II) signal with a coupling constant between a type 1 and a type 2 copper(II). This electron paramagnetic resonance signal could be explained by an induced asymmetry in the type 3 site due to a missing type 2 copper ion.     

The environmental effects of salinity and temperature on the oxygen consumption and total body osmolality of the marine flatworm Procerodes littoralis

The present study examined the effect of salinity and temperature on the rate of oxygen consumption and total body osmolality of the triclad turbellarian Procerodes littoralis, a common marine flatworm normally found in areas where freshwater streams run out over intertidal areas. Extremes in environmental factors encountered by P. littoralis were recorded at the study site. These were salinity (0-44 psu), temperature (2.7-24.9 °C) and oxygen concentration (2.8-16.1 mg l⁻¹). Respirometry experiments showed minimal oxygen consumption rates at the salinity extremes encountered by the study species (0 and 40 psu). Further experiments showed relatively constant oxygen consumption rates over the temperature range 5-20 °C and elevated consumption rates at temperatures above 25 °C. Total body osmolality of P. littoralis increased with increasing salinity. The study illustrates how a marine flatworm uses integrated physiological and behavioural mechanisms to successfully inhabit an environment that is predominantly freshwater for up to 75% of the tidal cycle.     

Respiration rate and oxy-regulatory capacity in cold stenothermal chironomids

The effects of temperature and oxygen saturation on the respiration rate of two cold stenothermal chironomids, Diamesa insignipes and Pseudodiamesa branickii were investigated. Fourth instar larvae were collected in winter in a glacio-rhithral stream (1300 m a.s.l., Alps, NE-Italy) and their respiration rate was measured with a Clark's electrode in the range 0-14 °C. The respiration rate was significantly higher in D. insignipes than in P. branickii at low temperatures (≤4 °C), higher in P. branickii between 8 and 12 °C and comparable at 14 °C. Higher values of R (regulation value), R_25% (respiration rate at 25% oxygen saturation) and b₁/b₂ (slope ratio in piecewise linear regression), and lower values of P_c (critical pressure) and I (initial decrease) were recorded in P. branickii than in D. insignipes. These values are compatible with oxy-regulatory behaviour in P. branickii, whereas D. insignipes appeared to be almost an oxy-conformer. On the basis of this autoecological information, new implications regarding survival of species from cold, high altitude habitats under changing climatic conditions are made.     

Effects of food concentration on clearance rate and energy budget of the Arctic bivalve Hiatella arctica (L) at subzero temperature

The influence of food concentration on clearance rate, respiration, assimilation, and excretion at −1.3 °C was studied on individuals of the bivalve Hiatella arctica (L.) from Young Sound, NE Greenland. Clearance rate, assimilation efficiency, respiration, and excretion rates were determined over a range of food concentrations using the microalga Rhodomonas baltica as food source. Physiological rates were generally low but responded significantly to increased food levels. Clearance rates and assimilation efficiency were reduced at increased food levels, whereas respiration and excretion increased. Assimilation efficiency was generally high, which may be an adaptation to the low food concentration during most of the year in NE Greenland. Low filtration rates limited ingestion rates and resulted in a low maximum assimilation of 3 J h⁻¹. Despite the low food intake, very low food concentrations were required for individual specimens to obtain a positive energy budget. Predicted growth based on rates of assimilation and respiration were compared to published estimates of annual growth in Young Sound. We estimate that 3 weeks of growth in the laboratory under optimal food conditions could match annual growth in situ. We interpret this as evidence that food limitation is the primary impediment to growth in this Arctic population.     

Influence of oxygen and temperature on growth and metabolic performance of Paralichthys lethostigma (Pleuronectiformes: Paralichthyidae)

In this study, we apply Fry's classification of environmental factors to demonstrate the limiting effects of oxygen and its interaction with temperature on the growth of juvenile P. lethostigma. We also evaluated the properties of two metabolic indices, marginal metabolic scope (MMS) and limiting oxygen concentration (LOC), as indicators of metabolic scope. We found that oxygen limitation has its greatest impact near the optimum temperature for growth of the species. At 29 °C a reduction from 6.00 mg/L to 4.00 mg/L caused a 50% reduction in growth rate while at 27 °C the reduction had no significant effect on growth rate. The results are particularly relevant because these temperatures and oxygen concentrations are commonly observed in nursery areas during summer months. At all temperatures fish from the lowest oxygen treatment (1.75 mg/L) had negative growth rates. Comparisons between daily oscillating oxygen treatments and constant treatments failed to demonstrate significant effects. At temperatures past the optimum, growth rates between the 6.00 mg/L and 4.00 mg/L treatments were not statistically different. LOC was significantly affected by temperature, oxygen, and their interaction. Estimates were positively correlated with oxygen treatment (R² > 0.71) and negatively correlated with temperature at moderate and low oxygen concentrations (R² > − 0.84). MMS was significantly affected by temperature and oxygen and was significantly correlated with oxygen treatment (R² > − 0.91), but correlations with temperature were not as clear. In conclusion, oxygen and temperature interactions have significant effects on metabolic scope and growth rates of fish, well above the accepted hypoxia threshold of 2.00 mg/L and MMS has proved a useful estimator of the metabolic scope of the organism within an environment.     

The routine metabolic rate of mulloway (Argyrosomus japonicus: Sciaenidae) and yellowtail kingfish (Seriola lalandi: Carangidae) acclimated to six different temperatures

This study compared the mass-specific routine metabolic rate (RMR) of similar sized mulloway (Argyrosomus japonicus), a sedentary species, and yellowtail kingfish (Seriola lalandi), a highly active species, acclimated at one of several temperatures ranging from 10–35 °C. Respirometry was carried out in an open-top static system and RMR corrected for seawater–atmosphere O₂ exchange using mass-balance equations. For both species RMR increased linearly with increasing temperature (T). RMR for mulloway was 5.78T − 29.0 mg O₂ kg^− 0.8 h^− 1 and for yellowtail kingfish was 12.11T − 39.40 mg O₂ kg^− 0.8 h^− 1. The factorial difference in RMR between mulloway and yellowtail kingfish ranged from 2.8 to 2.2 depending on temperature. The energetic cost of routine activity can be described as a function of temperature for mulloway as 1.93T − 9.68 kJ kg^− 0.8 day^− 1 and for yellowtail kingfish as 4.04T − 13.14 kJ kg^− 0.8 day^− 1. Over the full range of temperatures tested Q₁₀ values were approximately 2 for both species while Q₁₀ responses at each temperature increment varied considerably with mulloway and yellowtail kingfish displaying thermosensitivities indicative of each species respective niche habitat. RMR for mulloway was least thermally dependent at 28.5 °C and for yellowtail kingfish at 22.8 °C. Activation energies (E_a) calculated from Arrhenius plots were not significantly different between mulloway (47.6 kJ mol^− 1) and yellowtail kingfish (44.1 kJ mol^− 1).     

Metabolic readjustment in juvenile South African abalone (Haliotis midae) acclimated to combinations of temperature and dissolved oxygen levels

When ectotherms are exposed to high temperatures, cellular oxygen demand increases. When oxygen demand exceeds oxygen availability, animals may experience functional hypoxia regardless of environmental oxygen levels.     

In silico and in vitro characterization of phospholipase A2 isoforms from soybean (Glycine max)

At the present, no secreted phospholipase A₂ (sPLA₂) from soybean (Glycine max) was investigated in detail. In this work we identified five sequences of putative secreted sPLA₂ from soybean after a BLAST search in G. max database. Sequence analysis showed a conserved PA2c domain bearing the Ca²⁺ binding loop and the active site motif. All the five mature proteins contain 12 cysteine residues, which are commonly conserved in plant sPLA₂s. We propose a phylogenetic tree based on sequence alignment of reported plant sPLA₂s including the novel enzymes from G. max. According to PLA₂ superfamily, two of G. max sPLA₂s are grouped as XIA and the rest of sequences as XIB, on the basis of differences found in their molecular weights and deviating sequences especially in the N- and C-terminal regions of the isoenzymes. Furthermore, we report the cloning, expression and purification of one of the putative isoenzyme denoted as GmsPLA₂-XIA-1. We demonstrate that this mature sPLA₂ of 114 residues had PLA₂ activity on Triton:phospholipid mixed micelles and determine the kinetic parameters for this system. We generate a model based on the known crystal structure of sPLA₂ from rice (isoform II), giving first insights into the three-dimensional structure of folded GmsPLA₂-XIA-1. Besides describing the spatial arrangement of highly conserved pair HIS-49/ASP-50 and the Ca⁺² loop domains, we propose the putative amino acids involved in the interfacial recognition surface. Additionally, molecular dynamics simulations indicate that calcium ion, besides its key function in the catalytic cycle, plays an important role in the overall stability of GmsPLA₂-XIA-1 structure.     

Septal pore complex morphology in the Agaricomycotina (Basidiomycota) with emphasis on the Cantharellales and Hymenochaetales

The ultrastructure of septa and septum-associated septal pore caps are important taxonomic markers in the Agaricomycotina (Basidiomycota, Fungi). The septal pore caps covering the typical basidiomycetous dolipore septum are divided into three main phenotypically recognized morphotypes: vesicular-tubular (including the vesicular, sacculate, tubular, ampulliform, and globular morphotypes), imperforate, and perforate. Until recently, the septal pore cap-type reflected the higher-order relationships within the Agaricomycotina. However, the new classification of Fungi resulted in many changes including revision of existing and addition of new orders. Therefore, the septal pore cap ultrastructure of more than 325 species as reported in literature was related to this new classification. In addition, the septal pore cap ultrastructures of Rickenella fibula and Cantharellus formosus were examined by transmission electron microscopy. Both fungi have dolipore septa associated with perforate septal pore caps. These results combined with data from the literature show that the septal pore cap-type within orders of the Agaricomycotina is generally monomorphic, except for the Cantharellales and Hymenochaetales.It appears from the fungal phylogeny combined with the septal pore cap ultrastructure that the vesicular-tubular and the imperforate type both may have arisen from endoplasmic reticulum. Thereafter, the imperforate type eventually gave rise to the perforate septal pore cap-type.