A practical and reliable method for measuring ethane and pentane in expired air from humans.

We describe a method for the collection of expired air and further document the performance of our analytical technique that is used to measure ethane and pentane simultaneously. Four minutes of breathing hydrocarbon-free air before collection effectively removed high concentrations of residual ambient ethane and pentane from the lungs, with washout times up to 30 min resulting in no further reductions in breath hydrocarbons. Mean (+/-SE) exhalation rates (pmol/kg b.wt./min) in 11 subjects were 2.4 +/- 0.6 for ethane and 1.5 +/- 1.3 for pentane. Total intraindividual variability in exhalation rates (as percent coefficient of variation, %CV), measured from 4 subjects on at least 6 different days, was greater for pentane (44% CV) than for ethane (29% CV). Analytical variability contributed 6% to the total %CV. Advantages of the method are described, and reasons for the large variability in values reported in the literature are discussed.     

Molecular simulations of adsorption and separation of ethylene/ethane and propylene/propane mixtures on Ni2(dobdc) and Ni2(m-dobdc) metal-organic frameworks

Porous solid adsorbents have received considerable attention as a promising alternative to the traditional cryogenic distillation for separating olefin/paraffin mixtures. In this work, we studied pure components as well as ethylene/ethane and propylene/propane binary mixtures uptakes and selectivities at 318 K and 1 bar into metal-organic frameworks Ni₂(dobdc) and Ni₂(m-dobdc) using GCMC simulations. We used DFT method to modify the potential model of carbon–carbon double bond in unsaturated hydrocarbons. GCMC results show that ethylene and ethane uptakes on Ni₂(m-dobdc) are higher than that of Ni₂(dobdc) but propylene and propane uptakes are equal in Ni₂(m-dobdc) and Ni₂(dobdc). Also, Ni₂(m-dobdc) has higher selectivity than Ni₂(dobdc) for separation of ethylene/ethane and propylene/propane mixtures.     

Ethylene and Ethane Production from Sulfur Dioxide-injured Plants

After alfalfa (Medicago sativa) seedlings were exposed to approximately 0.7 microliter per liter SO₂ for 8 hours, elevated ethylene and ethane production was observed. Ethylene production peaked about 6 hours and returned to control levels by about 24 hours following the fumigation, while ethane production peaked about 36 hours and was still above control levels 48 hours after the fumigation. Light had an opposite effect upon the production of the two gases: ethane production rates were higher from plants held in light, whereas ethylene production rates were higher from those held in the dark. Peak ethylene and ethane production rates from SO₂-treated plants were about 10 and 4 to 5 times greater, respectively, than those of the control plants. Ethylene appeared to be formed primarily from stressed yet viable leaves and ethane from visibly damaged leaves. The different time courses and light requirements for ethylene and ethane production suggest that these two gases were formed via different mechanisms. Light appears to have a dual role. It enhances SO₂-induced cellular damage and plays a role for repairs.     

Reactions of vitamin B12r with polyhalogenated hydrocarbon pesticides

The reaction of vitamin B_12r, generated by photolysis of methylcobalamin under a nitrogen atmosphere, with 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), results in extensive dechlorination and formation of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) as the major products. Minor quantities of 1,1-bis(p-chlorophenyl)-2-chloroethane (DDMS), 1,1-bis(p-chlorophenyl)-2-chloroethylene (DDMU), 1,1-bis(p-chlorophenyl)ethane (DDO), and 1,1-bis(p-chlorophenyl)ethylene (DDNU) were also formed. Reaction of vitamin B_12r with DDD results in the production of DDMU and DDMS, the latter of which can react to produce DDNU and DDO. DDE and DDMU do not react with vitamin B_12r. The results obtained are suggestive of a vitamin B_12r-mediated dechlorination pathway for polyhalogenated hydrocarbon pesticides.     

Mechanism of Ethylene Action: Biological Activity of Deuterated Ethylene and Evidence against Isotopic Exchange and cis-trans-Isomerization

Deuterated ethylene was used to study the mechanism of ethylene action in etiolated pea seedlings (Pisum sativum L. cv. Alaska). No apparent differences were observed in the biological activity of tetradeuteroethylene (C₂D₄) and ordinary ethylene (C₂H₄) using the pea stem straight growth assay. The absence of an isotopic effect is discussed in relation to the possibility that ethylene binds to a metal or that carbon to hydrogen bonds of ethylene are broken during its mechanism of action.     

Ethylene and ethane production in response to salinity stress

Abstract Ethylene and ethane production in mung bean hypocotyl sections were evaluated as possible indicators of stress due to contact with four salts that are common in natural sites. Ethylene production decreased with increasing concentrations of applied NaCl and KCl. When CaCl₂ was applied, the ethylene evolution was greater. However, when MgCl₂ was applied, ethylene evolution remained high then decreased and at higher salt concentrations again showed an increase. NaCl (up to 0.1 kmol m^?1) and KCl (up to 0.5 kmol m^?3) caused a concentration-dependent increase in ethane production. The ethane production with CaCl₂ was the lowest among the salts tested and only a minute increase was noticed with the increase of concentration from 0.01 to 1 kmol m^?3. Ethane production showed a distinct maximum at 0.2 kmol m^?3 MgCl₂. The introduction of 0.01 kmol m^?3 CaCl₂, as well as anaerobic conditions obtained by purging vials with N₂, eliminated that high ethane production. Respiratory activity of the mung bean hypocotyl sections in MgCl₂ concentrations from 0 to 0.5 kmol m^?3 was correlated with ethane but not with ethylene production. The ethane/ethylene ratio showed three patterns for the four salts tested.     

Drought-inhibited ribulose-1,5-bisphosphate carboxylase activity is mediated through increased release of ethylene and changes in the ratio of polyamines in pakchoi

To study the mechanisms of drought inhibiting photosynthesis and the role of PAs and ethylene, the photosynthetic rate (P_n), the maximal photochemical efficiency of PSII (F_v/F_m), the intercellular CO₂ concentration (C_i), photorespiratory rate (P_r), the amount of chlorophyll (chl), antioxidant enzyme activity, ethylene levels, RuBPC (ribulose-1,5-bisphosphate carboxylase) activity and endogenous polyamine levels of pakchoi were examined, and an inhibitor of S-adenosylmethionine decarboxylase (SAMDC) and an inhibitor of ethylene synthesis and spermidine (Spd) were used to induce the change of endogenous polyamine levels. The results show that drought induced a decrease in P_n and RuBPC activity, an increase in the intercellular CO₂ concentration (C_i), but no change in the actual photochemical efficiency of PSII (Φ_PSII), and chlorophyll content. In addition, drought caused an increase in the free putrescine (fPut), the ethylene levels, a decrease in the Spd and spermine (Spm) levels, and the PAs/fPut ratio in the leaves. The exogenous application of Spd and amino oxiacetic acid (AOAA, an inhibitor of ethylene synthesis) markedly reversed these drought-induced effects on polyamine, ethylene, P_n, the PAs/fPut ratio and RuBPCase activity in leaves. Methylglyoxal-bis(guanylhydrazone) (MGBG), an inhibitor of SAMDC resulting in the inability of activated cells to synthesize Spd and Spm, exacerbates the negative effects induced by drought. These results suggest that the decrease in P_n is at least partially attributed to the decrease of RuBPC activity under drought stress and that drought inhibits RuBPC activity by decreasing the ratio of PAs/fPut and increasing the release of ethylene.     

Nonphysiological binding of ethylene by plants

Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest that the binding was not physiological. Inhibitors of ethylene action such as Ag⁺ ions and CO₂ did not decrease binding. Mushrooms which have no known sites of ethylene action also demonstrated ethylene binding. The binding of acetylene, propylene, ethylene, propane, and ethane more closely followed their solubility in water than any known physiological activity.     

Variations in the Specific Activity of Ribulose-1,5-bisphosphate Carboxylase between Species Utilizing Differing Photosynthetic Pathways

The in vitro specific activity of ribulose-1,5-bisphosphate carboxylase (RuBPCase) (micromoles CO₂ fixed per minute per milligram enzyme) from a number of C₃ and C₄ species and one green alga were measured. RuBPCases from species which utilize the C₄ pathway have a specific activity ~2-fold higher than those from C₃ species. RuBPCase from Chlamydomonas reinhardtii has a specific activity similar to the C₄ enzyme. Higher specific activity forms of RuBPCase are associated with a decreased enzyme affinity for CO₂ (increased K_m[CO₂]). A small but significant difference in the specific activity of RuBPCase from two C₄ decarboxylation types was also observed. The relationship between enzymic properties and the presence or absence of a CO₂ concentrating mechanism is discussed.     

The carbon concentrating mechanism in Chlamydomonas reinhardtii: finding the missing pieces

The photosynthetic, unicellular green alga, Chlamydomonas reinhardtii, lives in environments that often contain low concentrations of CO₂ and HCO₃ ^?, the utilizable forms of inorganic carbon (C_i). C. reinhardtii possesses a carbon concentrating mechanism (CCM) which can provide suitable amounts of C_i for growth and development. This CCM is induced when the CO₂ concentration is at air levels or lower and is comprised of a set of proteins that allow the efficient uptake of C_i into the cell as well as its directed transport to the site where Rubisco fixes CO₂ into biomolecules. While several components of the CCM have been identified in recent years, the picture is still far from complete. To further improve our knowledge of the CCM, we undertook a mutagenesis project where an antibiotic resistance cassette was randomly inserted into the C. reinhardtii genome resulting in the generation of 22,000 mutants. The mutant collection was screened using both a published PCR-based approach (Gonzalez-Ballester et al. 2011) and a phenotypic growth screen. The PCR-based screen did not rely on a colony having an altered growth phenotype and was used to identify colonies with disruptions in genes previously identified as being associated with the CCM-related gene. Eleven independent insertional mutations were identified in eight different genes showing the usefulness of this approach in generating mutations in CCM-related genes of interest as well as identifying new CCM components. Further improvements of this method are also discussed.     

Ethane in pine needles preventing the feeding of the beetle, Monochamus alternatus

Since the remarkable repulsion activity for Monochamus alternatus of a gas from freshly ground needles of Pinus densiflora was observed by feeding tests, volatile components in the gas were submitted for further feeding tests. Among six components, five were known monoterpenic hydrocarbons, all of which showed a relatively low activity. The most abundant residual volatile in the gas was ethane, whose presence in gymnosperms has not been reported so far. Ethane showed a strong repulsion activity and was proved to be present also in the gases from other conifer needles of nine species but in less quantity than in the gas from the needles of P. densiflora. However, the order of repulsion due to various conifer needles was found to be roughly consistent with the order of ethane concentration in the gases from the respective needles. Saturated hydrocarbons with straight-chain C₅ to C₁₀ were also shown to be active for the beetle.     

Mechanisms of hormone action: use of deuterated ethylene to measure isotopic exchange with plant material and the biological effects of deuterated ethylene

We observed no exchange between deuterated ethylene (C₂D₄) and the hydrogen of pea seedlings (Pisum sativum L. cv. Alaska). This suggests that bonding forces in which exchange could readily occur are not important in the physiological action of ethylene. Deuterated ethylene was just as effective as normal ethylene in inhibiting the growth of pea root sections. These results indicate that splitting carbon to hydrogen bonds did not occur during ethylene action.     

Abnormal exhaled ethane concentrations in scleroderma

Abstract

Scleroderma (systemic sclerosis) is a chronic multisystem autoimmune disease in which oxidative stress is suspected to play a role in the pathophysiology. Therefore, it was postulated that patients with scleroderma would have abnormally high breath ethane concentrations, which is a volatile product of free-radical-mediated lipid peroxidation, compared with a group of controls. There was a significant difference (p<0.05) between the mean exhaled ethane concentration of 5.27 pmol ml^–1 CO₂ (SEM=0.76) in the scleroderma patients (n=36) versus the mean exhaled concentration of 2.72 pmol ml^?1 CO₂ (SEM=0.71) in a group of healthy controls (n=21). Within the scleroderma group, those subjects taking a calcium channel blocker had lower ethane concentrations compared with patients who were not taking these drugs (p=0.05). There was a significant inverse association between lung diffusion capacity for carbon monoxide (per cent of predicted) and ethane concentration (b=?2.8, p=0.026, CI=?5.2 to ?0.35). These data support the presence of increased oxidative stress among patients with scleroderma that is detected by measuring breath ethane concentrations.     

C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves

Attempts are being made to introduce C₄ photosynthetic characteristics into C₃ crop plants by genetic manipulation. This research has focused on engineering single‐celled C₄‐type CO₂ concentrating mechanisms into C₃ plants such as rice. Herein the pros and cons of such approaches are discussed with a focus on CO₂ diffusion, utilizing a mathematical model of single‐cell C₄ photosynthesis. It is shown that a high bundle sheath resistance to CO₂ diffusion is an essential feature of energy‐efficient C₄ photosynthesis. The large chloroplast surface area appressed to the intercellular airspace in C₃ leaves generates low internal resistance to CO₂ diffusion, thereby limiting the energy efficiency of a single‐cell C₄ concentrating mechanism, which relies on concentrating CO₂ within chloroplasts of C₃ leaves. Nevertheless the model demonstrates that the drop in CO₂ partial pressure, pCO₂, that exists between intercellular airspace and chloroplasts in C₃ leaves at high photosynthetic rates, can be reversed under high irradiance when energy is not limiting. The model shows that this is particularly effective at lower intercellular pCO₂. Such a system may therefore be of benefit in water‐limited conditions when stomata are closed and low intercellular pCO₂ increases photorespiration.     

Emission of ethylene and ethane by leaf tissue exposed to injurious concentrations of sulfur dioxide or bisulfite ion

Leaf tissues injured with SO₂ gas or bisulfite ion in solution emit ethylene and ethane. The amounts of these gases produced by the tissues depend on the degree of exposure to SO₂ or bisulfite. The amount of ethylene produced in response to SO₂ fumigation correlates positively with SO₂ exposure (0 to 5.5 microliters per liter for 16 hours), SO₂ absorbed, and the amount of visible injury sustained by the leaf tissues. Ethane production is correlated positively with the injury resulting from treatment with bisulfite ion. The rate of emission of ethane from leaf discs of cucurbit cultivars as a result of exposure to bisulfite solutions is in agreement with the order and the degree of their resistance to injury by SO₂. Thus, exposure to bisulfite and the subsequent release of ethane can be used to determine the relative resistance of different species and cultivars to SO₂ gas.     

Breath ethane as a marker of reactive oxygen species during manipulation of diet and oxygen tension in rats

Breath ethane, O₂consumption, and CO₂ productionwere analyzed in 24-mo-old female Fischer 344 rats that had been fedcontinuously ad libitum (AL) or restricted 30% of AL level (DR) dietssince 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then with a gas mixture containing 12%O₂. After equilibration, a sampleof the outflow was collected in gas sampling bags for subsequentanalyses of ethane and CO₂. TheO₂ andCO₂ levels were also directlymonitored in the outflow of the chamber. O₂ consumption andCO₂ production increased for DRrats. Hypoxia decreased O₂consumption and CO₂ production forthe AL-fed and DR rats. These changes reflect changes in metabolic ratedue to diet and PO₂. A significantdecrease in ethane generation was found in DR rats compared with AL-fedrats. Under normoxic conditions, breath ethane decreased from 2.20 to1.61 pmol ethane/ml CO₂. Duringhypoxia the levels of ethane generation increased, resulting in aDR-associated decrease in ethane from 2.60 to 1.90 pmol ethane/mlCO₂. These results support thehypothesis that DR reduces the level of oxidative stress.     

Zitronensäuregärung Auf Stärkehydrolysaten

Summary It was the aim of the authors to examine the purification methods of the starch hydrolizate using the following adsorbents: Fuller's Earth, CaSO₄- dead burnt, activated coal, Amberlit IRA-410, Duolit C-20, Kaolin S, Kaolin NS and Al₂O₃ for Chromatography. Fermentation of the purified starch hydrolizate carried out withAspergillus niger C₂, showed that it could be used as a substrate for the citric acid fermentation. We obtained the best results using starch hydrolizates with a concentration of 10,24% of sugars purified with Amberlit IRA-410, 0,1–0,25% activated coal, Fuller's Earth and CaSO₄.