Gas exchange and photosynthetic water use efficiency in response to light, CO2 concentration and temperature in Vicia faba

Light and temperature-response curves and their resulting coefficients, obtained within ecophysiological characterization of gas exchanges at the leaf level, may represent useful criteria for breeding and cultivar selection and required tools for simulation models aimed at the prediction of potential plant behaviour in response to environmental conditions.

Leaf-scale gas exchanges, by means of an IRGA open-flow system, were measured in response to light intensity (8 levels from 0 up to 2000 μmol m⁻² s⁻¹), CO₂ concentrations (ambient—350 μmol mol⁻¹ and short-term enriched—700 μmol mol⁻¹) and air temperature (from 7 up to 35 °C) on three Vicia faba L. genotypes, each representing one of the three cultivated groups: major, equina and minor. The net assimilation rate response to light intensity was well described by an exponential rise to max function. The short-term CO₂ enrichment markedly increased the values of light response curve parameters such as maximum photosynthetic rate (+80%), light saturation point (+40%) and quantum yield (+30%), while less homogenous behaviour was reported for dark respiration and light compensation point. For each light intensity level, the major and minor genotypes studied showed assimilation rates at least a 30% higher than equina.

The positive effects of short-term CO₂ enrichment on photosynthetic water use efficiency (WUE) indicate a relevant advantage in doubling CO₂ concentration. In the major and minor genotypes studied, similar assimilation rates, but different WUE were observed.

The optimum leaf temperature for assimilation process, calculated through a polynomial function, was 26–27 °C and no relevant limitations were observed in the range between 21 and 32 °C.

Analysis at the single leaf level provided both rapid information on the variations in gas exchange in response to environmental factors and selection criteria for the screening of genotypes.     

Reversible adsorption of carbon dioxide on amine surface-bonded silica gel

Carbon dioxide adsorbs reversibly on a silica gel containing 3-aminopropyl groups bonded to surface atoms of silicon. These act as the active sites for the chemisorption of CO₂ at room temperature which is liberated by temperature programmed desorption at about 100 °C. The material is capable of adsorbing about 10 STP cm³ of dry CO₂ per gram and can be regenerated upon heating. It might be used as scrubber for carbon dioxide from industrial gaseous streams. Adsorption of humid CO₂ produces a small amount of formaldehyde which suggests activation of the carbon dioxide molecule.     

Photosynthetic response of Myriophyllum salsugineum A.E. orchard to photon irradiance, temperature and external free CO2

The photosynthetic capacity of Myriophyllum salsugineum A.E. Orchard was measured, using plants collected from Lake Wendouree, Ballarat, Victoria and grown subsequently in a glasshouse pond at Griffith, New South Wales. At pH 7.00, under conditions of constant total alkalinity of 1.0 meq dm⁻³ and saturating photon irradiance, the temperature optimum was found to be 30–35°C with rates of 140 μmol mg⁻¹ chlorophyll a h⁻¹ for oxygen production and 149 μmol mg⁻¹ chlorophyll a h⁻¹ for consumption of CO₂. These rates are generally higher than those measured by other workers for the noxious Eurasian water milfoil, Myriophyllum spicatum L., of which Myriophyllum salsugineum is a close relative. The light-compensation point and the photon irradiance required to saturate photosynthetic oxygen production were exponentially dependent on water temperature. Over the temperature range 15–35°C the light-compensation point increased from 2.4 to 16.9 μmol (PAR) m⁻² s⁻¹ for oxygen production while saturation photon irradiance increased from 41.5 to 138 μmol (PAR) m⁻² s⁻¹ for oxygen production and from 42.0 to 174 μmol (PAR) m⁻² s⁻¹ for CO₂ consumption. Respiration rates increased from 27.1 to 112.3 μmol (oxygen consumed) g⁻¹ dry weight h⁻¹ as temperature was increased from 15 to 35°C. The optimum temperature for productivity is 30°C.     

Growth and photosynthesis of Hydrocotyle ranunculoides L. fil. in Central Europe

Floating Pennywort (Hydrocotyle ranunculoides L. fil.) is a worldwide distributed aquatic plant. The species is native to North America and quite common also in Central and South America. In Europe, Japan and Australia it is known as an alien plant, sometimes causing serious problems for affected ecosystems and human use of water bodies. Starting from Western Europe with an eastwards directed spread, Floating Pennywort was recorded in Germany in 2004 for the first time. Since then, the species spread out and got established in western parts of Central Europe. For a definite prediction of the potential of a further spread, data about biology, in particular growth and photosynthesis are needed. Here, regeneration capacity, growth at different nutrient availabilities and photosynthesis of H. ranunculoides were investigated. In addition biomass samples were taken in the field. Results show an enormous regeneration capacity (e.g., by forming new shoots from small shoot fragments), increasing growth rates under increasing nutrient availability and a maximum increase of biomass reaching 0.132±0.008 g g⁻¹ dw d⁻¹. Dense populations of H. ranunculoides growing in ponds and oxbows were found at high nutrient content of the substrate, the biomass reaching there up to 532.4±14.2 g dw m⁻². Gas exchange analysis showed a physiological optimum of H. ranunculoides CO₂ uptake at temperatures between 25 and 35 °C and high photon flux densities (PPFD) above 800 μmol photons m⁻² s⁻¹. In comparison, native Hydrocotyle vulgaris showed an optimum of net photosynthesis at 20–30 °C and a light saturation of CO₂ gas exchange at 350 μmol photons m⁻² s⁻¹.     

Carbon exchange and water use efficiency of a growing, irrigated olive orchard

We measured eddy covariance fluxes of CO₂ and H₂O over a flat irrigated olive orchard during growth, in different periods from Leaf Area Index (LAI) of 0.3–1.9; measurements of soil respiration were also collected. The daily net ecosystem exchange flux (F_NEE) was practically zero at LAI around 0.4 or when the orchard intercepted 11% of the incoming daily radiation; at the end of the experiment, with LAI of 1.9 (and the fraction of intercepted daily radiation close to 0.5), F_NEE was around 10 g CO₂ m⁻² day⁻¹. The night-time ecosystem respiration (R_eco), calculated from eddy fluxes in well-mixed night conditions, show a clear but non-linear dependence with LAI; it ranged from 0.05 to 0.15 mg CO₂ m⁻² s⁻¹ (in average), being the lower limit ideally close to the heterotrophic soil respiration at the site. The gross primary production flux (F_GPP) was linearly related to LAI within the LAI range of this experiment (with 11 g CO₂ m⁻² day⁻¹ increments per unit of LAI) and to the fraction of intercepted radiation. The maximum rates of F_GPP (0.75 mg CO₂ m⁻² s⁻¹) were obtained in the summer mornings of 2002, at LAI close to 1.9. F_GPP was strongly modulated by vapour pressure deficit (VPD) through the canopy conductance, even in absence of water stress. Hence, especially in the summer, the maximum rates of carbon assimilation are reached always before noon. The daily course of F_GPP shows a two-phase pattern, first related to irradiance and then to canopy conductance. The water use efficiency (WUE) was, in average, 3.8, 6.3 and 7 g CO₂ L⁻¹ in 1999, 2001 and 2002, respectively, with maxima always in the early morning. Hourly WUE was strongly related to VPD (WUE = −10.25 + 22.52 × VPD^−0.34). Our results suggest that drip irrigated orchards in general, and olive in particular, deserve specific carbon exchange and carbon budget studies and cannot be easily included in other biomes.     

The effect of water concentration on the activity and stability of CLECs in supercritical CO2 in continuous operation

In this study the effect of the water concentration on a crystallized enzyme of Candida antarctica lipase B (ChiroCLEC™-CAB) in supercritical carbon dioxide (scCO₂) is studied. The model reaction used is the enantioselective esterification of racemic 1-phenyl ethanol with vinyl acetate; the reaction is performed in scCO₂ at 40 °C and 90 bar in batch and in continuous operation. Kinetic parameters have been derived from continuous experiments, leading to a catalytic turnover number of 0.95 s⁻¹. The optimum activity is reached at low water concentrations (0.05 g L⁻¹). At lower concentrations, CO₂ is stripping water from the enzyme leading to deactivation. However, adding a small amount of water to the substrates can reverse this deactivation and the enzyme activity is restored.     

Solar irradiance level alters the growth of basil (Ocimum basilicum L.) and its content of volatile oils

The experiments were commenced in March 2003 and repeated in June 2003 at Sutton Bonington Campus, the University of Nottingham, UK, to investigate the effect of irradiance on plant growth and volatile oil content and composition in plants of basil. Four levels of irradiance were provided in the glasshouse, i.e. no shade (control), 25, 50 and 75% glasshouse irradiance. It suggested that basil grows well in full sun, however it can tolerate light shade. Heavy shading (75%) to provide a light integral of 5.3 moles m⁻² d⁻¹ resulted in shorter plants, lower weight, smaller leaf area, less shoots and higher specific leaf area, and also strongly reduced the rate of photosynthesis. There was no difference in CO₂ assimilation rate between 24.9 moles m⁻² d⁻¹ light integrals (no shading) and 13.5 moles m⁻² d⁻¹ light integrals (25% shading). Shading effectively reduced leaf temperature when air temperature was less than 30 °C, but heavy shading (75%) could not reduce leaf temperature when air temperature was above 36 °C due to a limitation of free air convection. Consequently, leaf temperature increased. Heavy shading strongly reduced total volatile oil content in fresh leaves, especially in older plants (shading treatment applied at the 3 leaf-pair growth stage). There were three chemical compounds in basil leaves, namely linalool, eugenol and methyl eugenol, influenced by the shading treatments. Linalool and eugenol, which contribute to the characteristic taste of basil, were significantly increased by high daily light integrals, whereas methyleugenol was increased by lower daily light integrals. No differences in the relative content of 1,8-cineole, one of the key aromatic compounds of Ocimum species, were observed.     

Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia Mello-Leitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae)

In this study, the maximum and minimum lethal temperatures (LT₅₀) of L. intermedia and L. laeta were determined in two treatments: gradual heating (25–50°C) and cooling (25°C to −5°C), and 1 h at a constant temperature. In gradual temperatures change, L. intermedia mortality started at 40°C and the LT₅₀ was 42°C; for L. laeta, mortality began at 35°C and the LT₅₀ was 40°C. At low temperatures, mortality was registered only at −5°C for both species. In the constant temperature L. intermedia showed a maximum LT₅₀ at 35°C and L. laeta at 32°C; the minimum LT for both species was −7°C.     

Supercritical carbon dioxide extraction of astaxanthin from Haematococcus pluvialis with vegetable oils as co-solvent

Soybean oil and olive oil were investigated as continuous co-solvents for supercritical carbon dioxide (SC-CO₂) extraction of astaxanthin from Haematococcus pluvialis. Without co-solvents, only 25.40 ± 0.79% efficiency was achieved with SC-CO₂ extraction at 70 °C and 40 MPa at a continuous flow rate of 3 mL min⁻¹ for 5 h. In the presence of soybean oil or olive oil as a co-solvent, the extraction efficiency was enhanced, with the most appropriate level of soybean oil in the solvent mixture being 10% by volume. At this concentration and the above extraction conditions, the highest extraction efficiency of 36.36 ± 0.79% was obtained for soybean oil, a 30% increase in extraction efficiency compared with SC-CO₂ extraction without soybean oil, whereas the 10% olive oil increased the extraction efficiency further to 51.03 ± 1.08%, which was comparable to that obtained using ethanol as co-solvent.     

A study in UF-membrane reactor on activity and stability of nitrile hydratase from Microbacterium imperiale CBS 498-74 resting cells for propionamide production

The bioconversion of propionitrile to propionamide was catalysed by nitrile hydratase (NHase) using resting cells of Microbacterium imperiale CBS 498-74 (formerly, Brevibacterium imperiale). This microorganism, cultivated in a shake flask, at 28 °C, presented a specific NHase activity of 34.4 U mg_DCW⁻¹ (dry cell weight). The kinetic parameters, K_m and V_max, tested in 50 mM sodium phosphate buffer, pH 7.0, in the propionitrile bioconversion was evaluated in batch reactor at 10 °C and resulted 21.6 mM and 11.04 μmol min⁻¹ mg_DCW⁻¹, respectively. The measured apparent activation energy, 25.54 kJ mol⁻¹, indicated a partial control by mass transport, more likely through the cell wall.

UF-membrane reactors were used for kinetic characterisation of the NHase catalysed reaction. The time dependence of enzyme deactivation on reaction temperature (from 5 to 25 °C), on substrate concentrations (from 100 to 800 mM), and on resting cell loading (from 1.5 to 200 μg  ml⁻¹) indicated: lower diffusional control (E_a=37.73 kJ mol⁻¹); and NHase irreversible damage caused by high substrate concentration. Finally, it is noteworthy that in an integral reactor continuously operating for 30 h, at 10 °C, 100% conversion of propionitrile (200 mM) was attained using 200 μg  ml⁻¹ of resting cells, with a maximum volumetric productivity of 0.5 g l⁻¹ h⁻¹.     

Impaired pulmonary gas exchange in ewes naturally infected by small lungworms

Respiratory rate and blood gases were studied in 2 groups of ewes: the ewes in group 1 (9 ewes) acted as uninfected controls and those in group 2 (6 ewes) were infected with small lungworms (Muellerius, Cystocaulus, Protostrongylus and < 1% Neostrongylus). The respiratory rate was higher in infected (49 ± 19 breath min⁻¹) than in uninfected ewes (20 ± 3 breath min⁻¹); it was strongly reduced after treatment (49 vs 22) in infected ewes. The partial carbon dioxide arterial tension (PCO₂), total CO₂ and HCO₃⁻ were higher (respectively 77 vs 39 mmHg, 38 vs 23 mmoll⁻¹ and 35 vs 23 mmoll⁻¹) in infected compared with uninfected ewes, whereas arterial pH (7.2 vs 7.4) and partial oxygen tension PO₂ were lower (41 vs 81 mmHg) in infected ewes. Group 2 was treated with fenbendazole (at 15mg kg⁻¹ bodyweight) to eliminate small lungworms, and the respiratory rate and blood gases were measured 3 weeks after treatment. The values after treatment were similar to those in uninfected ewes. It is concluded that heavy infections by small lungworms in ewes impairs gas exchange, but that gas exchange improves rapidly after treatment.     

Pyrolysis of safflower (Charthamus tinctorius L.) seed press cake: part 1. The effects of pyrolysis parameters on the product yields

Safflower (Charthamus tinctorius L.) seed press cake was pyrolysed in a fixed-bed reactor. The effects of pyrolysis temperature, heating rate and sweep gas flow rates on the yields of the products were investigated. Pyrolysis runs were performed using pyrolysis temperatures between 400 and 600 °C with heating rates of 10, 30 and 50 °C min⁻¹. The obtained bio-char, gas and bio-oil yields ranged between 25 and 34 wt%, 19 and 25 wt%, and 28 and 36 wt%, respectively, at different pyrolysis conditions. The highest liquid yield was obtained at 500 °C pyrolysis temperature with a heating rate of 50 °C min⁻¹ under the sweep gas of N₂ with a flow rate of 100 cm³ min⁻¹. Employing the higher heating rate of 50 °C min⁻¹ results in maximum bio-oil yield, probably due to the decrease in mass transfer limitations. According to the results obtained under the conditions of this study, the effects of pyrolysis temperature and sweep gas flow rate are more significant than the effect of heating rate on the yields.     

Effect of leaf age on CAM activity in Littorella uniflora

In this study the effect of ontogenetic drift on crassulacean acid metabolism (CAM) was investigated in the aquatic CAM-isoetid Littorella uniflora. The results of this study strengthen the general hypothesis of CAM being a carbon-conserving mechanism in aquatic plants, because high-CAM capacity (45–183 μequiv. g⁻¹ FW) was present in all leaves of L. uniflora irrespective of age. Since possession of CAM in aquatic plants allows CO₂ uptake throughout the light/dark cycle, presence of CAM in all leaves influences the carbon balance of L. uniflora positively. On average for all lakes, different leaf classes accounted for 11–36% of the total dark CO₂ uptake by the individual plant.

The capacity for both CAM and photosynthesis declined with increasing leaf age, and was in the oldest leaves only 25–53% of the capacity in the youngest. The photosynthetic capacity was estimated to be sufficiently high to ensure refixation of the CO₂ released from malate during decarboxylation in the daytime. In line with this, a linear coupling between CAM capacity and photosynthetic capacity was found. Parallel to the change in photosynthetic capacity, an age-related change in total ribulose-bisphosphate carboxylase/oxygenase (rubisco) activity from 732 μmol C g⁻¹ DW h⁻¹ in the youngest leaves to 346 μmol C g⁻¹ DW h⁻¹ in the oldest was observed. In contrast, no significant change in phosphoenolpyruvate carboxylase (PEPcase) activity with leaf age was observed (means ranged between 46 and 156 μmol C g⁻¹ DW h⁻¹).     

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.     

Morphological and physiological responses of canola (Brassica napus) siliquas and seeds to UVB and CO2 under controlled environment conditions

Combined effects of UVB radiation and CO₂ concentration on plant reproductive parts have received little attention. We studied morphological and physiological responses of siliquas and seeds of canola (Brassica napus L. cv. 46A65) to UVB and CO₂ under four controlled experimental conditions: UVB radiation (4.2 kJ m⁻² d⁻¹) with ambient level of CO₂ (370 μmol mol⁻¹) (control); UVB radiation (4.2 kJ m⁻² d⁻¹) with elevated level of CO₂ (740 μmol mol⁻¹); no UVB radiation (0 kJ m⁻² d⁻¹) with ambient level of CO₂ (370 μmol mol⁻¹); and no UVB radiation (0 kJ m⁻² d⁻¹) with elevated level of CO₂ (740 μmol mol⁻¹). UVB radiation affected the outer appearance of siliquas, such as colour, as well as their anatomical structures. At both CO₂ levels, the UVB radiation of 4.2 kJ m⁻² d⁻¹ reduced the size of seeds, which had different surface patterns than those from no UVB radiation. At both CO₂ levels, 4.2 kJ m⁻² d⁻¹ of UVB decreased net CO₂ assimilation (A_N) and water use efficiency (WUE), but had no effect on transpiration (E). Elevated CO₂ increased A_N and WUE, but decreased E, under both UVB conditions. At both CO₂ levels, the UVB radiation of 4.2 kJ m⁻² d⁻¹ decreased chlorophyll fluorescence, total chlorophyll (Chl), Chl a and Chl b, but had no effect on the ratio of Chl a/b and the concentration of UV-screening pigments. Elevated CO₂ increased total Chl and the concentration of UV-screening pigments under 4.2 kJ m⁻² d⁻¹ of UVB radiation. Neither UVB nor CO₂ affected wax content of siliqua surface. Many significant relationships were found between the above-mentioned parameters. This study revealed that UVB radiation exerts an adverse effect on canola siliquas and seeds, and some of the detrimental effects of UVB on these reproductive parts can partially be mitigated by CO₂.     

New extracellular resistance mechanism for cisplatin

The HSQC NMR spectrum of ¹⁵N-cisplatin in cell growth media shows resonances corresponding to the monocarbonato complex, cis-[Pt(NH₃)₂(CO₃)Cl]⁻, 4, and the dicarbonato complex, cis-[Pt(NH₃)₂(CO₃)₂]⁻², 5, in addition to cisplatin itself, cis-[Pt(NH₃)₂Cl₂], 1. The presence of Jurkat cells reduces the amount of detectable carbonato species by (2.8 ± 0.7) fmol per cell and has little effect on species 1. Jurkat cells made resistant to cisplatin reduce the amount of detectable carbonato species by (7.9 ± 5.6) fmol per cell and also reduce the amount of 1 by (3.4 ± 0.9) fmol per cell. The amount of detectable carbonato species is also reduced by addition of the drug to medium that has previously been in contact with normal Jurkat cells (cells removed); the reduction is greater when drug is added to medium previously in contact with resistant Jurkat cells (cells removed). This shows that the platinum species are modified by a cell-produced substance that is released to the medium. Since the modified species have been shown not to enter or bind to cells, and since resistant cells modify more than non-resistant cells, the modification constitutes a new extracellular mechanism for cisplatin resistance which merits further attention.     

Nutrient removal by thermophilic Fischerella (Mastigocladus laminosus) in a simulated algaculture process

A novel nutrient removal/waste heat utilization process was simulated using semicontinuous cultures of the thermophilic cyanobacterium Fischerella. Dissolved inorganic carbon (DIC)-enriched cultures, maintained with 10 mg l⁻¹ daily productivity, diurnally varying temperature (from 55°C to 26–28°C), a 12:12 light cycle (200 μE sec⁻¹ m⁻²) and 50% biomass recycling into heated effluent at the beginning of each light period, removed > 95% of NO₃⁻ + NO₂⁻−N, 71% of NH₃-N, 82% of PO₄³⁻ −P, and 70% of total P from effluent water samples containing approximately 400 μg l⁻¹ combined N and 60 μg l⁻¹ P. Nutrient removal was not severely impaired by an altered temperature gradient, doubled light intensity, or DIC limitation. Recycling 75% of the biomass at the end of each light period resulted in unimpaired NO₃⁻ + NO₂⁻ removal, 38–45% P removal and no net NH₃ removal. Diurnally varying P removal, averaging 50–60%, and nearly constant > 80% N removal, are therefore projected for a full-scale process with continuous biomass recycling.     

Effect of elevated CO2, temperature and drought on dry matter partitioning and photosynthesis before and after cutting of nodulated alfalfa

The rising atmospheric CO₂ concentration resulting from industrial development may enhance photosynthesis and plant growth. However, there is a lack of research concerning the effect of combined factors such as CO₂, temperature and water availability on plant regrowth following cutting or grazing, which represent the usual methods of managing forage legumes like alfalfa. Elevated CO₂, temperature and drought can interact with cutting factors (e.g. cutting frequency or height), and source-sink balance differences before and after defoliation can modify photosynthetic behaviour and dry matter accumulation, as well as dry matter partitioning between above- and belowground organs. The aim of our study was to determine the interactive effect of CO₂ (ambient, around 350 μmol mol⁻¹ versus 700 μmol mol⁻¹), temperature (ambient versus ambient + 4 °C) and water availability (well-irrigated versus partially irrigated) on dry matter partitioning and photosynthesis in nodulated alfalfa after vegetative normal growth and during regrowth. At the end of vegetative normal growth, CO₂ enhanced dry matter accumulation despite photosynthesis being down-regulated at the end of this period. Photosynthesis was stimulated by elevated CO₂ and resulted in greater dry matter accumulation during the regrowth period. Aboveground organs were affected more by drought than belowground organs during the entire experiment, particularly during vegetative normal growth. The higher drought tolerance (greater growth) observed during the regrowth period may be related to higher mass and greater reserves accumulated in the roots of plants.     

Inorganic carbon uptake kinetics of the stream macrophyte Callitriche cophocarpa Sendt.

Photosynthetic carbon uptake of Callitriche cophocarpa Sendt. was examined in plants collected from six Danish streams and in plants grown under variable inorganic carbon conditions in the laboratory. Both field and laboratory plants showed a low affinity for inorganic carbon (CO₂ compensation points ranging from 0.7 to 22 μM, and K_0.5(CO₂) from 51 to 121 μM), consistent with C-3 photosynthesis and use of CO₂ alone. Variation in inorganic carbon uptake characteristics was low in both groups of plants. Only in laboratory-grown plants was a coupling found between carbon uptake and the inorganic carbon regime of the medium. The carbon extraction capacity, expressed as a percentage of the initial amount of dissolved inorganic carbon (DIC) assimilated in PH-drift experiments, increased from −1.4 to 11.8% with declining external carbon availability, and the initial slope of the CO₂ response curve increased from 6.4 to 15.3 g⁻¹ h⁻¹ dm³. The plasticity of the inorganic carbon uptake system of C. cophocarpa was very low compared to the plasticity observed for submerged macrophytes with accessory carbon uptake systems (i.e. HCO₃⁻ use or C-4 photosynthesis), suggesting that the plasticity of the C-3 photosynthetic apparatus as such is restricted. The low carbon affinity of C. cophocarpa indicates that this species depends on CO₂ oversaturation for a sufficient supply of CO₂ for photosynthesis and growth.     

Metabolism and thermoregulation in Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli)

1 Metabolic rates (Vo₂), body temperature (T_b), and thermal conductance (C) were first determined in newly captured Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli) from the Inner Mongolian grasslands at a temperature range from 5 to 35 °C.

2 The thermal neutral zone (TNZ) was between 25 and 32.5 °C for Maximowiczi's voles and between 25 and 30 °C for Djungarian hamsters. Mean T_b was 37.0±0.1 °C for voles and 36.2±0.1 °C for hamsters. Minimum thermal conductance was 0.172±0.004 ml O₂/g h °C for voles and 0.148±0.003 ml O₂/g h °C for hamsters.

3 The mean resting metabolic rate within TNZ was 2.21±0.05 ml O₂/g h in voles and 2.01±0.07 ml O₂/g h in hamsters. Nonshivering thermogenesis was 5.36±0.30 ml O₂/g h for voles and 6.30±0.18 ml O₂/g h for hamsters.

4 All these thermal physiological properties are adaptive for each species and are shaped by both macroenvironmental and microenvironmental conditions, food habits, phylogeny and other factors.