Physiological ecology of a tropical dragon,Lophognathus temporalis

Lophognathus temporalis is an arboreal lizard from the wet–dry tropics of Australia. During the wet season the field metabolic rate (FMR) of the lizards was 209 kJ kg^?1 d^?1, but during the dry season FMR was only 62 kJ kg^?1 d^?1. Similarly, water flux decreased from 73.6 mL kg^?1 d^?1 in the wet season to 18.5 mL kg^?1 d^?1 in the dry season. Body temperatures (T_b) were significantly lower in the dry season, and operative temperatures, calculated by incorporating microclimatic data with characteristics of the lizards, indicated that the seasonal shift was due to changes in thermoregulatory behaviour rather than limitations of the thermal environment. By combining field measurements of T_b and FMR with laboratory measurements of standard metabolic rate over a range of T_b, we were able to subdivide the FMR into its components and to determine which factors contributed to the seasonal reduction in energy expenditure. During the dry season, lizards used 147 kJ kg^?1 d^?1 less energy than during the wet season, and 24% of this decrease was estimated to be due to the passive effects of lower nighttime T_b, 14% was due to the active selection of lower daytime T_b, 27% was due to the physiological shift to lower standard metabolic rates, and 35% was due to reduced activity in the dry season. Although the population size remained relatively constant (107 lizards ha^?1 during the wet season and 125 lizards ha^?1 during the dry season), the population structure changed, reflecting the seasonal patterns of recruitment and mortality. The number of lizards active at any one time was much lower in the dry season, reflecting the lower levels of activity in this season. The energy expenditure of the population of L. temporalis was 612 kJ ha^?1 d^?1 during the wet season and 113 kJ ha^?1 d^?1 during the dry season.     

Energy Content of Antarctic Mesopelagic Fishes: Implications for the Marine Food Web

For a better understanding of the role of mesopelagic fish in the Southern Ocean food web, the energy and water content of Bathylagus antarcticus, Electrona antarctica and Gymnoscopelus braueri from the Lazarev Sea were investigated. Mean dry weight energy content of B. antarcticus (20.4 kJ g⁻¹) was significantly lower than in E. antarctica and G. braueri (both 29.4 kJ g⁻¹). In E. antarctica, an increase of dry weight energy density with age was evident from 26.9 kJ g⁻¹ in juveniles of less than 1 year of age to 32.0 kJ g⁻¹ in 3-year-old fish. Water content decreased with size in all three species. Abundant high-energy species such as E. antarctica are at a key position in the food web. Due to a marked influence of age on energy content, population structure can be an important variable in estimates of energy fluxes in the Southern Ocean ecosystem.     

Effect of UVB radiation on the survival, feeding, and egg production of the brackish-water copepod, Sinocalanus tenellus, with notes on photoreactivation

We examined the effects of UVB radiation on hatching success of eggs, survival of various naupliar and copepodite stages, and feeding and egg production of adult females of the brackish-water copepod, Sinocalanus tenellus, by exposure to varying doses of UVB irradiance in the laboratory. Artificial UVB radiation resulted in an increased mortality of eggs, nauplii and copepodites with increasing UVB doses. UVB induced damage was stage-specific with eggs being most susceptible (LD₅₀= 4.1 kJ m^–2 ) and adult females being least susceptible (LD₅₀= 16.7 kJ m^–2). Effects on feeding and egg production of adult females were significantly evident at UVB doses higher than 11.0 kJ m^–2 and 7.0 kJ m^–2, respectively. We also examined the photorepair response of eggs and various developmental stages in simultaneous irradiation of UVB and enhanced PAR. With enhanced PAR there was a considerable recovery against UVB damage, being higher for younger animals than older ones. In nature, however, solar UVB radiation may rarely cause appreciable damage to S. tenellus population due to optically high attenuation properties of their habitat waters.     

Cold and hungry: combined effects of low temperature and resource scarcity on an edge-of-range temperate primate,the golden snub-nose monkey

Both biotic and abiotic factors play important roles in influencing ecological distributions and niche limits. Where biotic and abiotic stressors co-occur in space and time, homeostatic systems face a scenario in which stressors can compound to impose a challenge that is greater than the sum of the separate factors. We studied the homeostatic strategies of the golden snub-nosed monkey Rhinopithecus roxellana, a species living in temperate deciduous forests at the edge of the global distribution range for folivorous primates, to cope with the co-occurrence of cold temperatures and resource scarcity during winter. We discovered that in winter the monkeys experience a dietary energy deficit of 101 kJ mbm⁻¹ d⁻¹ compared with calculated needs, despite increased feeding. This is partly offset by behavioral changes (reduced locomotion and increased resting) and reducing skin temperature by an average of 3.2°C through a cutaneous vasoconstriction to decrease heat loss. However, their major strategy is ingesting surplus energy and accumulating fat reserves when food was not limiting during summer and autumn. Their 14% of body mass lost over the winter represented an energy yield of 102 kJ mbm⁻¹ d⁻¹, which closely matched the calculated winter energy deficit of 101 kJ mbm⁻¹ d⁻¹. However, the latter value assumes that all the 75.41 kJ mbm⁻¹ d⁻¹ of protein ingested in winter was available for energy metabolism. This is almost certainly an over-estimate, suggesting that the study population was in negative energy balance over the study period. Our study therefore suggests that despite its suit of integrated homeostatic responses, the confluence of low temperatures and resource limitation during winter places this edge-of-range primate close the threshold of what is energetically viable. It also provides a framework for quantitative models predicting the vulnerability of temperate primates to global change.     

Energetics of Acidianus ambivalens growth in response to oxygen availability

All life requires energy to drive metabolic reactions such as growth and cell maintenance; therefore, fluctuations in energy availability can alter microbial activity. There is a gap in our knowledge concerning how energy availability affects the growth of extreme chemolithoautotrophs. Toward this end, we investigated the growth of thermoacidophile Acidianus ambivalens during sulfur oxidation under aerobic to microaerophilic conditions. Calorimetry was used to measure enthalpy (ΔH_inc) of microbial activity, and chemical changes in growth media were measured to calculate Gibbs energy change (ΔG_inc) during incubation. In all experiments, Gibbs energy was primarily dissipated through the release of heat, which suggests enthalpy‐driven growth. In microaerophilic conditions, growth was significantly more efficient in terms of biomass yield (defined as C‐mol biomass per mole sulfur consumed) and resulted in lower ΔG_inc and ΔH_inc. ΔG_inc in oxygen‐limited (OL) and oxygen‐ and CO₂‐limited (OCL) microaerophilic growth conditions resulted in averages of ?1.44 × 10³ kJ/C‐mol and ?7.56 × 10² kJ/C‐mol, respectively, and average ΔH_inc values of ?1.11 × 10⁵ kJ/C‐mol and ?4.43 × 10⁴ kJ/C‐mol, respectively. High‐oxygen experiments resulted in lower biomass yield values, an increase in ΔG_inc to ?1.71 × 10⁴ kJ/C‐mol, and more exothermic ΔH_inc values of ?4.71 × 10⁵ kJ/C‐mol. The observed inefficiency in high‐oxygen conditions may suggest larger maintenance energy demands due to oxidative stresses and a preference for growth in microaerophilic environments.     

Energy requirements of the red kangaroo (<Emphasis Type="Italic">Macropus rufus</Emphasis>): impacts of age,growth and body size in a large desert-dwelling herbivore.

Generally, young growing mammals have resting metabolic rates (RMRs) that are proportionally greater than those of adult animals. This is seen in the red kangaroo (Macropus rufus), a large (>20 kg) herbivorous marsupial common to arid and semi-arid inland Australia. Juvenile red kangaroos have RMRs 1.5–1.6 times those expected for adult marsupials of an equivalent body mass. When fed high-quality chopped lucerne hay, young-at-foot (YAF) kangaroos, which have permanently left the mother's pouch but are still sucking, and recently weaned red kangaroos had digestible energy intakes of 641±27 kJ kg^–0.75 day^–1 and 677±26 kJ kg^–0.75 day^–1, respectively, significantly higher than the 385±37 kJ kg^–0.75 day^–1 ingested by mature, non-lactating females. However, YAF and weaned red kangaroos had maintenance energy requirements (MERs) that were not significantly higher than those of mature, non-lactating females, the values ranging between 384 kJ kg^–0.75 day^–1 and 390 kJ kg^–0.75 day^–1 digestible energy. Importantly, the MER of mature female red kangaroos was 84% of that previously reported for similarly sized, but still growing, male red kangaroos. Growth was the main factor affecting the proportionally higher energy requirements of the juvenile red kangaroos relative to non-reproductive mature females. On a good quality diet, juvenile red kangaroos from permanent pouch exit until shortly after weaning (ca. 220–400 days) had average growth rates of 55 g body mass day^–1. At this level of growth, juveniles had total daily digestible energy requirements (i.e. MER plus growth energy requirements) that were 1.7–1.8 times the MER of mature, non-reproductive females. Our data suggest that the proportionally higher RMR of juvenile red kangaroos is largely explained by the additional energy needed for growth. Energy contents of the tissue gained by the YAF and weaned red kangaroos during growth were estimated to be 5.3 kJ g^–1, within the range found for most young growing mammals.Abbreviations BMR basal metabolic rate - DEI digestible energy intake - MER maintenance energy requirement - MER_g maintenance plus growth energy requirement - PPE permanent pouch exit - RMR resting metabolic rate - YAF young-at-foot Communicated by I.D. Hume     

Large‐scale distribution and activity patterns of an extremely low‐light‐adapted population of green sulfur bacteria in the Black Sea

The Black Sea chemocline represents the largest extant habitat of anoxygenic phototrophic bacteria and harbours a monospecific population of Chlorobium phylotype BS‐1. High‐sensitivity measurements of underwater irradiance and sulfide revealed that the optical properties of the overlying water column were similar across the Black Sea basin, whereas the vertical profiles of sulfide varied strongly between sampling sites and caused a dome‐shaped three‐dimensional distribution of the green sulfur bacteria. In the centres of the western and eastern basins the population of BS‐1 reached upward to depths of 80 and 95 m, respectively, but were detected only at 145 m depth close to the shelf. Using highly concentrated chemocline samples from the centres of the western and eastern basins, the cells were found to be capable of anoxygenic photosynthesis under in situ light conditions and exhibited a photosynthesis–irradiance curve similar to low‐light‐adapted laboratory cultures of Chlorobium BS‐1. Application of a highly specific RT‐qPCR method which targets the internal transcribed spacer (ITS) region of the rrn operon of BS‐1 demonstrated that only cells at the central station are physiologically active in contrast to those at the Black Sea periphery. Based on the detection of ITS‐DNA sequences in the flocculent surface layer of deep‐sea sediments across the Black Sea, the population of BS‐1 has occupied the major part of the basin for the last decade. The continued presence of intact but non‐growing BS‐1 cells at the periphery of the Black Sea indicates that the cells can survive long‐distant transport and exhibit unusually low maintenance energy requirements. According to laboratory measurements, Chlorobium BS‐1 has a maintenance energy requirement of ～1.6–4.9·10^?15 kJ cell^?1 day^?1 which is the lowest value determined for any bacterial culture so far. Chlorobium BS‐1 thus is particularly well adapted to survival under the extreme low‐light conditions of the Black Sea, and can be used as a laboratory model to elucidate general cellular mechanisms of long‐term starvation survival. Because of its adaptation to extreme low‐light marine environments, Chlorobium BS‐1 also represents a suitable indicator for palaeoceanography studies of deep photic zone anoxia in ancient oceans.     

Winter energy deficits and the importance of fruit versus insects in a tropical island bird population

The sedentary population of 200 to 500 silver-eyes on Heron Island, Australian Great Barrier Reef, experiences high mortality during the winter non-breeding season. The omnivorous silvereyes feed mainly on small insects gleaned from foliage, and on fruits, especially the fig Ficus opposita. Estimates of the energy content of food items reveal that small insects (2–5 mm long) provide little assimilable energy (9 J), whereas large insects (>8 mm) and bites of fig provide most assimilable energy (217 J and 181 J respectively). An analysis of the average daily intakes and expenditures (estimated by the time-budget method) for three sampling occasions showed that the rates of insect consumption (10,15 and 11 kJ day^-1) were significantly less than the energy requirements (37, 38 and 37 kJ day^-1). While many individuals may have been able to balance their energy budgets by eating figs, the calculated fruit intake rates (38, 9 and 0.5 kJ day^-1 respectively), together with high inter-individual variation in fig consumption, suggest that figs were often in short supply. The birds visited fig trees most frequently during the first 2 h after sunrise, and the feeding success rate in fig trees (approximately 20% of visits successful) during this time was significantly greater than that during the rest of the day (approximately 10% of visits successful). Alternative hypotheses for these patterns, based on protein requirements, on diurnal rhythms imposed by insect availability, or on satiation, are considered and rejected. These results indicate that the pre-breeding population size is limited by winter energy shortage, the extent of which is dependent on the size and phenology of the fig crop. Natural selection should favour individual strategies for maximization of net energy intake.     

Differential responses of the dinoflagellate Cochlodinium polykrikoides bloom to episodic typhoon events

To better understand the effect of typhoons on the harmful alga Cochlodinium polykrikoides, we investigated cell population dynamics in relation to hydrographic conditions in Korean coastal waters before and after the passage of typhoons. After typhoon Lingling passed through the Yellow Sea, significant accumulation of C. polykrikoides on the southern coast of Namhae Island was associated with southerly winds on September 8, 2019. Similar to field observations of red tide, a particle transport model simulation showed that the virtual particles were greatly influenced by wind-driven currents associated with typhoons, particularly when diel vertical migration was included in the model. However, a bloom of C. polykrikoides disappeared immediately after the passage of typhoon Tapah on September 23, 2019. Because of the different patterns of bloom behavior after the passage of these typhoons, characteristics of other typhoons that affected the Korean peninsula during previous C. polykrikoides blooms were investigated. Analysis of typhoon properties including wind direction, precipitation, and wave height and energy suggested that high wave energy during the passage of a typhoon plays a critical role in the termination of C. polykrikoides blooms, because of its generation of high turbulence relative to other factors. In our study, the wave energy associated with typhoon Tapah (753.6 kJ m^?2 over 48 h) was much higher than that associated with typhoon Lingling (441.7 kJ m^?2 over 48 h). The results indicate that typhoons have an important role in determining the accumulation and termination of C. polykrikoides blooms through the physical effects of wind direction and wave energy.

     

The ecology of Lake Nakuru

Summary The major pathways of energy flow in Lake Nakuru (East Africa) are presented. The trophic structure of this equatorial alkaline-saline lake shows no predictable long term continuity. During the five years of this study it had a bloom of Spirulina platensis that persisted at least two years, it had periods with low algal densities and in addition it had various transitional phases with dramatic fluctuations of species composition and density.The Spirulina platensis bloom is characterized by a rich and almost unialgal bloom of the cyanophyte Spirulina platensis minor, with a mean biomass of 3,500 kJ m^-3 (20 kJ 1 g dry weight). Net photosynthetic rates were very high at depths with optimal light conditions (230 kJ m^-3 h^-1), but algal self-shading made integrated rates modest (45 kJ m^-3 24 h^-1) relative to the high biomass. Of the eight primary consumers only five species contributed significantly to the consumer biomass of 220 kJ m^-3: the flamingo Phoeniconaias minor, the cichlid fish Sarotherodon alcalicus grahami, the copepod Lovenula africana, the dipteran larva Leptochironomus deribae, and the rotifer Brachionus dimidiatus. Consumption rates were 50% of net photosynthetic rates, production rates 10%. Secondary consumers (90% being the pelican Pelecanus onocrotalus and the Greater Flamingo Phoenicopterus ruber) had a biomass of about 6.8 kJ m^-3. Pelicans consumed almost the whole fish production (7.5 metric tons wet weight/day).At low algal densities the lake had a more diverse algal population but a reduced mean biomass of 1,500 kJ m^-3 and mean net photosynthetic rates of 12 kJ m^-3 24 h^-1. Primary consumer species diversity and biomass were also reduced. Consumption rates sometimes exceeded primary production rates. Rotifers probably contributed 50% to total consumption and 75% to total secondary production but the estimates of their role is speculative as the relative contributions of algae, bacteria and detritus to rotifer consumption are not known. Transitional phases are characterized by rapidly changing abiotic and biotic conditions with algal breakdowns and sudden population peaks at all levels. Rotifers dominated secondary consumers, they contributed 25% to the total biomass of 380 kJ m^-3, 90% to the total consumption rate of 290 kJ m^-3d^-1 and 95% to the total production of 41 kJ m^-3d^-1.The discussion focusses on problems of measuring primary production in alkaline-saline lakes, and the control of producer and consumer densities. The difficulty in assessing the importance of bacteria and rotifers is emphasized. Also questions of ecological stability and efficiency are addressed. Finally, some recommendations for conservational policy are included.     

Kinetic and thermodynamics study of the pyrolytic process of the freshwater macroalga,Chara vulgaris

This is the first study where the pyrolysis of the freshwater macroalga Chara vulgaris was explored to reveal its bioenergy potential. The suitability of C. vulgaris to bioenergy conversion via pyrolysis was accessed in terms of kinetic triplet and thermodynamic parameters. For this purpose, pyrolysis experiments under a thermogravimetric scale were conducted at multiple heating rates (5, 10, and 20 °C min^?1) in an inert atmosphere. The mass-loss profiles of C. vulgaris pyrolysis showed that there are two dominant decomposition stages that are related to distinct chemical components inside its structure and that directly affect the calculated kinetic triplet and thermodynamics parameters. The average activation energy obtained using isoconversional methods of Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Friedman was in the range of 52.87–72.91 kJ mol^?1 for the first decomposition stage and 156.14–174.65 kJ mol^?1 for the second decomposition stage. The pyrolytic conversion of C. vulgaris initially follows a second-order reaction model (first decomposition stage), while in second decomposition stage is controlled by a second-order Avrami-Erofeev reaction model. The kinetic results derived from the non-isothermal decomposition of C. vulgaris proved its suitable characteristics for pyrolysis. Additionally, multi-stage kinetic interpretation was successfully attained based on two kinetic triplets, where reconstructed pyrolysis behavior correlated well with experimental pyrolysis behavior. The changes in enthalpy, Gibbs free energy, and entropy for first decomposition stage were 67.58±0.25 kJ mol^?1, 180.77±5.30 kJ mol^?1, and ?176.65±0.41 J mol^?1 K^?1, and for the second decomposition stage the values were 166.70±0.09 kJ mol^?1, 285.51±1.29 kJ mol^?1, and ?124.29±0.09 J mol^?1 K^?1, respectively. Based on thermodynamic aspects, C. vulgaris is particularly interesting for use as a raw material to produce biofuels and bioenergy.

     

Determination of glucose-fructose oxidoreductase activity in whole cells of Zymomonas mobilis

A method for the determination of glucose-fructose oxidoreductase (GFOR) activity in whole cells of Zymomonas mobilis is described. The K _m and the theoretical V _max for GFOR were 192 g glucose.l^-1 and 17 g gluconic acid.g^-1 cell.h^-1, respectively. The changes in enthalpy (31.1 kJ.mol^-1), entropy (0.41 kJ.K^-1), and Gibbs free energy (-97.5 kJ.mol^-1) related to glucose to gluconic acid conversion were also determined.     

Partitioning of late gestation energy expenditure in ewes using indirect calorimetry and a linear regression approach

Abstract

Late gestation energy expenditure (EE_gest) originates from energy expenditure (EE) of development of conceptus (EE_conceptus) and EE of homeorhetic adaptation of metabolism (EE_homeorhetic). Even though EE_gest is relatively easy to quantify, its partitioning is problematic. In the present study metabolizable energy (ME) intake ranges for twin-bearing ewes were 220 – 440, 350 – 700, 350 – 900 kJ per metabolic body weight (W^0.75) at week seven, five, two pre-partum respectively. Indirect calorimetry and a linear regression approach were used to quantify EE_gest and then partition to EE_conceptus and EE_homeorhetic. Energy expenditure of basal metabolism of the non-gravid tissues (EE_bmng), derived from the intercept of the linear regression equation of retained energy [kJ/W^0.75] and ME intake [kJ/W^0.75], was 298 [kJ/W^0.75]. Values of the intercepts of the regression equations at week seven, five, and two pre-partum were 311, 398, and 451 [kJ/W^0.75], respectively. The difference between the intercepts for different weeks was used to calculate EE_homeorhetic. The remaining part of EE_gest was considered to be EE_conceptus. In conclusion, the good agreement between our values of EE_conceptus and those in the literature indicates the method's validity.     

Leaf litter processing and energy flow through macroinvertebrates in a woodland pond (Switzerland)

Energy generated by leaf litter processing and its flow through the associated macroinvertebrate community was quantified in a pond near Geneva (Switzerland). Annual density, biomass, and production on oak (Quercus robur) leaf litter were assessed for all macroinvertebrate taxa with emphasis on predators. Empirical energetic relations provided an energy budget for the macroinvertebrate community. On 1 m² of pond bottom, the processing of 5641 kJ of oak leaf litter resulted in 8.5% of leachate (6 days), and after 1 year 32% of material remained; the other 59.5% was biologically (animal or microbial) converted, including 11.2% processed by shredders. The mean annual density of associated macroinvertebrates was 51374 individuals, mean biomass was 3.53 g (dry mass) and production was about 1451 kJ (or 65 g). Predator production was 170 kJ/m², non-chironomid primary consumer production was 101 kJ/m² (including 57 kJ from shredders) and chironomid primary consumer production was estimated at 1180 kJ/m². Predators contributed to a high proportion of total biomass (39%) but to a smaller amount of production (12%) or density (6%). In this two-stepped food-chain mainly based on detritus, the transfer coefficient between first level (detritus + primary producers) and third level (secondary consumers) was high (2–2.5%) and indicated efficient conversion of energy. This high efficiency was partly related to the reutilization of fine particulate organic matter by the collectors. The production estimate measured on leaf litter was compared with two other predominant substrates (Typha latifolia stems and Chara sp.), and exhibited the highest value. This study shows how leaf litter can constitute a direct source for high secondary production and be an efficient energy source in freshwater ecosystems. It is also demonstrated that a woodland pond can support a high macroinvertebrate production as compared with other freshwater ecosystems.     

Purification and characterization of caprine kidney uricase, possessing novel kinetic and thermodynamic properties

Purified uricase from a caprine kidney, possessed K _m and V _max values of 1.1 mg ml⁻¹ and 3512 IU (mg protein)⁻¹ for uric acid hydrolysis, respectively. The optimum temperature and pH for catalytic activity were 40 °C and 8.5, respectively. The activation energy for formation of ES complex was 13.6 kJ mol⁻¹. Enthalpy (ΔH*), entropy of activation (ΔS*) and Gibbs free energy demand of uricase inactivation were 62.8 kJ mol⁻¹, −102 J mol⁻¹ K⁻¹ and 104.3 kJ mol⁻¹, respectively. Gibbs free enrgy demand for substrate binding and transition state stabilization were also determined which were comparable with those for themostable enzymes.     

Mate guarding in relation to seasonal changes in the energy reserves of two freshwater amphipods (Gammarus fossarum and G. pulex)

1. We assessed sex‐specific seasonal changes in major energy storage compounds (triglycerides, glycogen) in Gammarus fossarum and Gammarus pulex collected from the field, with respect to their reproductive activity. 2. The dynamics of stored energy followed a seasonal pattern in both species and sexes. Moreover, over a 4‐year period, these changes were independent of the year in which they were investigated. Stored energy reached a peak in late winter, but was depleted in late summer and early autumn, coinciding with the reproductive periods. 3. Triglyceride (annual mean ± SD) accounted for 79.7 ± 11.9% of the total stored energy and was responsible for the seasonal pattern. In contrast, glycogen contributed a lesser percentage (20.3 ± 11.9%). Over the study period, the amount of stored energy ranged between 0.39 and 4.08 kJ g^?1 dry mass (triglyceride: 0.19–3.69 kJ g^?1 dry mass; glycogen: 0.14–0.80 kJ g^?1 dry mass). 4. In both species, the energy reserves of males were drastically depleted shortly before the cessation of precopulatory mate guarding in the field, thus offering a bioenergetic explanation for the reproductive period in these two widespread species.     

Kinetics and thermodynamics of catalysis and thermal inactivation of a novel α-amylase (Tp-AmyS) from Thermotoga petrophila

Abstract

This research is focussed on kinetic, thermodynamic and thermal inactivation of a novel thermostable recombinant α-amylase (Tp-AmyS) from Thermotoga petrophila. The amylase gene was cloned in pHIS-parallel1 expression vector and overexpressed in Escherichia coli. The steady-state kinetic parameters (V_max, K_m, k_cat and k_cat/K_m) for the hydrolysis of amylose (1.39?mg/min, 0.57?mg, 148.6?s^?1, 260.7), amylopectin (2.3?mg/min, 1.09?mg, 247.1?s^?1, 226.7), soluble starch (2.67?mg/min, 2.98?mg, 284.2?s^?1, 95.4) and raw starch (2.1?mg/min, 3.6?mg, 224.7?s^?1, 61.9) were determined. The activation energy (E_a), free energy (ΔG), enthalpy (ΔH) and entropy of activation (ΔS) at 98?°C were 42.9?kJ mol^?1, 74?kJ mol^?1, 39.9?kJ mol^?1 and ?92.3 J mol^?1 K^?1, respectively, for soluble starch hydrolysis. While ΔG of substrate binding (ΔG_E-S) and ΔG of transition state binding (ΔG_E-T) were 3.38 and ?14.1?kJ mol^?1, respectively. Whereas, EaD, Gibbs free energy (ΔG*), increase in the enthalpy (ΔH*) and activation entropy (ΔS*) for activation of the unfolding of transition state were 108, 107, 105?kJ mol^?1 and ?4.1 J mol^?1 K^?1. The thermodynamics of irreversible thermal inactivation of Tp-AmyS revealed that at high temperature the process involves the aggregation of the protein.     

Thermodynamic interaction between urea and the peptide group in aqueous solutions at 25°C

Isopiestic vapor pressure measurements of the ternary systems water + triglycine + urea and water + glycine-L-alanine + urea were made and used to calculate the Gibbs free energy of these systems. Together with recently published analogous results on systems, in which the first solute was glycine or alanine or diglycine, and measurements of the excess enthalpy of all these solutions, it is possible to calculate the Gibbs free energy of transfer and the enthalpy of transfer of the peptide group from water to aqueous urea solutions. The transfer can be described as a binding of urea to the peptide group with ΔG = ?1.85 kJ mol^?1 and ΔH = ?18.7 kJ mol^?1 at 298.1 K.     

Biomass plasticity of the leaves and inflorescences of Acaena magellanica (Lam.) Vahl (Rosaceae) on Subantarctic Iles Kerguelen

Summary The relative allocation of biomass within monospecific stands of Acaena magellanica that vary in level of wind and water stress differ greatly. Populations in January 1983 varied in leaf biomass from 192 to 2373 g wet wt m^-2 (1105 to 10023 kJ m^-2) Inflorescences were not produced at either of these extremes of leaf biomass. In two populations with intermediate levels of leaf biomass (597 and 640 g wet wt m^-2, 3185 and 2664 kJ m^-2), inflorescent biomass was 104 and 273 g wet wt m^-2 (385 and 1127 kJ m^-2). The relative allocation to sexual reproduction is thus not constant in A. magellanica. The levels of energy in the leaves and inflorescences did not differ greatly despite differences in proximate composition.     

Ecological energetics of Central European grasshoppers (Orthoptera: Acrididae)

Summary Biomass and energy budgets and food utilization efficiencies of laboratory and wild populations of three Central European grasshopper species, Chorthippus parallelus (Zetterstedt), C. biguttulus (L.), and Gomphocerus rufus (L.), were studied between 1979 and 1984. Larval consumption is relatively low in C. biguttulus (C=4.3 kJ/ind.) compared with C. parallelus and G. rufus (4.9 kJ/ind.). In the adult phase (maturity) consumption rates of C. biguttulus and G. rufus (6.9 kJ/ind.) are similar, but higher in C. parallelus (7.3 kJ/ind.). The energy content decreases from the egg (23.2–24.3 J/mg dw) and body tissue (22.1–23.2 J/mg dw) to faeces (16.6–18.1 J/mg dw). The energy contents of faeces differ significantly between the species, indicating different rates of food conversion (on Dactylis glomerata). On average, the assimilation rates are about 30%, slightly lower in G. rufus. Approximate digestibility (A/C) ranges from 28.2 (G. rufus) to 35.7 (C. biguttulus) without great differences between larvae and adults. In contrast, the efficiency of conversion of ingested food (P/C) differs significantly between larval (10–11) and adult stages (3.4–3.6), and so to a much higher degree does the efficiency of conversion of digested food (P/A), from 30.3–33.5 in the larval to 9.5–14.9 in the adult period. Based on 5-year (C. parallelus) and 2-year studies (G. rufus) of the population dynamics and life tables, the energy budgets of wild populations were calculated and summarized into diagrams. Depending on the annually fluctuating densities, in both populations about 1%–2% of net primary production was consumed, and another 5%–9% was cut and dropped. The proportion of production of the grasshopper populations (body tissue) used for egg production differs in C. parallelus (28%) and G. rufus (44%). The energy cycling owing to energy storage in the living eggs amounts to 2%–3% of the total energy consumed by the population. The results are compared with the available data for grasshoppers in the literature.