Heat Shock Induced Lipid Changes and Solute Leakage in Germinating Seeds of Pigeonpea

Heat shock (HS) reduced total lipid and phospholipid contents and their synthesis in germinating seeds of pigeonpea [Cajanus cajan (L.) Millspaugh]. Lipid peroxidation was also enhanced with increasing temperature and HS duration. HS influenced lipid metabolism to a higher extent at 45°C than at 40°C. This altered lipid metabolism and lipid peroxidation was associated with the loss of various solutes from the germinating seeds, and modification of growth and development. Pretreatment of germinating seeds at 40°C for 1 h or at 45°C for 10 min followed by incubation at 28°C for 3 h prior to 45°C for 2 h ameliorated solute leakage due to reduced lipid peroxidation and improvement in lipid content and membrane function.     

Partial arousals from hibernation in hedgehogs in outdoor hibernacula

Summary Thermal properties of hibernacula and sequences of arousals have been studied in four adult hedgehogs for seven months starting in October. Departures and entries to the nesting chamber were continuously monitored together with ambient temperature and the temperature in the hibernacula.During the two first months of the experimental period nest departures were intermittently recorded, predominantly in the two females which also occasionally foraged. The longest periods spent continuously in the hibernaculum ranged from 129 to 178 days. The natural hibernation season for Danish hedgehogs was found to comprise the six months from October onwards when there is little shelter where hedgehogs normally roam.Ambient temperatures recorded were —11 to +13° C being subzero for half the total time measured. The nest temperatures generally were higher, and above 0° C during 78–99% of total time, most commonly ranging from 0° to 4° C and thus reflecting deep hibernation.Between December and May spontaneous increases in nest temperatures amounting to 7–26° C (average 18° C) and bringing these temperatures to 10–29.5° C were recorded in 58 cases. Fiftyfour arousals did not involve departure from the hibernaculum (partial arousals). In the remaining cases (full arousals) the preceding rewarming lasted 4 1/2–6 1/2 h and nest departures amounted to 10,2 and 5 min in one female hedgehog and 90 min in another.The hedgehogs showed 12–18 arousals, the mean duration of which was 34–44 h. The high energy expenditure associated with arousals however, was found to last on average 21 h during each arousal. It is hypothesized that the body temperature during arousals chiefly was below 35–37° C.The time between arousals was 3–15 days. Periods in hibernation averaged 7–8 days in the females and 9–10 days in the heavier males, being generally longest in January-February. Neither arousals nor re-entries into deep hibernation occurred at any particular time of the day. It is suggested that for undisturbed hedgehogs arousals are induced and controlled by endogenous factors. In conclusion it is stressed that future studies on hibernation should recognize the importance of individual variability in the response pattern and focus interest on the endogenous factors which govern this important process.     

Seasonal thermogenic capacity in a hibernator,Spermophilus richardsonii

Summary The maximum thermogenic capacity (HPmax) and the maximum capacity for non-shivering thermogenesis (NSTmax) were assessed in a hibernator, the Richardson's ground squirrel at different times of year. The HPmax was elicited by exposing animals to He–O₂ (21% oxygen, balance helium) at –10 to –25°C. The NSTmax was estimated by i.v. infusion of isoproterenol in anesthetized animals at thermoneutrality. Non-hibernating phase adults were collected and tested in April and June, and youngs in June and August for effects of seasonal acclimatization; animals were also tested after acclimation to cold (5°C) or warm (20°C). Hibernating phase animals were tested both shortly after the onset of hibernation season and after several months into the hibernation season. Although HPmax differed significantly between the lowest [101 cal (wt^0.73·h)^–1 in the June-Young group] and the highest [142 cal (wt^0.73·h)^–1 in the June-Adult group], it was not significantly different between other groups regardless of hibernation status or temperature acclimation (Fig. 4). The NSTmax, however, increased from 40–50 cal (wt^0.73·h)^–1 in the Warm-Acclimated, August-Young, June-Adult, and April-Adult to 66.5 and 79.2 cal (wt^0.73·h)^–1 in the two hibernating groups (Fig. 3). No significant difference in NSTmax was observed between Cold- and Warm-Acclimated groups. Since HPmax was maintained essentially constant at different times of year or after temperature acclimation, the increase of NSTmax during the hibernating phase can best be viewed as an adjustment for facilitation of periodic rewarmings from depressed body temperature during hibernation rather than to counter cold.Abbreviations HP heat production - HPmax maximum heat production - NST non-shivering thermogenesis - NSTmax maximum non-shivering thermogenesis - ST shivering thermogenesis - T _a ambient temperature - T _b body temperature     

Seasonal and daily rhythms of body temperature in the European hamster (Cricetus cricetus) under semi-natural conditions

Body temperature of five European hamsters exposed to semi-natural environmental conditions at 47° N in Southern Germany was recorded over a 1.5-year period using intraperitoneal temperature-sensitive radio transmitters. The animals showed pronounced seasonal changes in body weight and reproductive status. Euthermic body temperature changed significantly throughout the year reaching its maximum of 37.9±0.2°C in April and its minimum of 36.1±0.4°C in December. Between November and March the hamsters showed regular bouts of hibernation and a few bouts of shallow torpor. During hibernation body temperature correlated with ambient temperature. Monthly means of body temperature during hibernation were highest in November (7.9±0.8°C) and March (8.2±0.5°C) and lowest in January (4.4±0.7°C). Using periodogram analysis methods, a clear diurnal rhythm of euthermic body temperature could be detected between March and August, whereas no such rhythm could be found during fall and winter. During hibernation bouts, no circadian rhythmicity was evident for body temperature apart from body temperature following ambient temperature with a time lag of 3–5 h. On average, hibernation bouts lasted 104.2±23.8 h with body temperature falling to 6.0±1.7°C. When entering hibernation the animals cooled at a rate of -0.8±0.2°C·h^-1; when arousing from hibernation they warmed at a rate of 9.9±2.4°C·h^-1. Warming rates were significantly lower in November and December than in January and February, and correlated with ambient temperature (r=-0.46, P<0.01) and hibernating body temperature (r=-0.47, P<0.01). Entry into hibrnation occured mostly in the middle of the night (mean time of day 0148 hours ±3.4 h), while spontaneous arousals were widely scattered across day and night. For all animals regression analysis revealed free-running circadian rhythms for the timing of arousal. These results suggest that entry into hibernation is either induced by environmental effects or by a circadian clock with a period of 24 h, whereas arousal from hibernation is controlled by an endogenous rhythm with a period different from 24 h.Abbreviations bw body weight - CET central European time - T _a ambient temperature - T _b body temperature - TTL transistor-transistor logic     

Protective Role of the Polysaccharide-containing Capsular Components of Azospirillum brasilense

The involvement of the carbohydrate components of the Azospirillum brasilenseSp245 capsules in bacterial protection from the action of extreme factors was investigated. The survival of encapsulated and non-encapsulated azospirilla exposed to elevated (46–48°C) and below-freezing (–20 and –70°C) temperatures, extreme pH values (2 and 10), and to drying was studied. High-molecular-weight carbohydrate-containing complexes (lipopolysaccharide–protein complex and polysaccharide–lipid complex) were isolated from the capsular material of azospirilla. It was shown that the addition of these complexes to the suspension of decapsulated cells before exposing them to extreme factors enhanced their survival rates by 15 to 51%.     

Arsenite as an Inducer of Lipid Peroxidation in Saccharomyces cerevisiae Cells

The ability of sodium arsenite at concentrations of 10^–2, 10^–4, and 10^–6 M to induce lipid peroxidation in Saccharomyces cerevisiae cells was studied. Arsenite at the concentrations 10^–2 and 10^–4 M enhanced lipid peroxidation and inhibited the growth of yeast cells. Enhanced lipid peroxidation likely induced oxidative damage to various cellular structures, which led to suppression of the metabolic activity of cells. Arsenite at the concentration 10^–6 M did not activate lipid peroxidation in cells. All of the tested arsenite concentrations inhibited the activity of -ketoglutarate dehydrogenase and pyruvate dehydrogenase in cells. The inference is made that the toxicity of arsenite may be related to its stimulating effect on intracellular lipid peroxidation.     

On the hibernation of Spongilla lacustris (L.)

Summary The osmotic pressure of the summer-sponge is about 25–30 mM NaCl. At and after gemmulation it increases to about 110 mM (in a single case 175 mM was found), due to a liberation of small organic molecules. Osmotic pressure remains constant for a time, but in January and February (i. e. before the germination) it is again reduced to the summer values. The shell allows a high hydrostatic pressure to develop and thereby prevents osmotic rupture of the gemmula. The hibernation may be divided into three periods: The prehibernation, the posthibernation and intercalated between them the hibernation proper. In the prehibernation and in the posthibernation definite changes take place in the tissue, but in the hibernation proper no changes are observed. In Nature the hibernation lasts about six months at, say, 4°, but at 22 degrees the whole hibernation will abbreviate to about 13 days.This is due to an abbreviation of all the three periods of hibernation, but whereas the pre- and the posthibernation will only be accelerated in a manner similiar to that of other physiological processes, such as processes of growth, development and metabolism, the hibernation proper will be accelerated much more, and in fact it will be almost abolished at 22°. This strange effect of temperature on hibernation proper is discussed. Since development often occurs at very low temperatures (2–5°), we may conclude that a mechanism must be present in the gemmulae which ensures development after a certain time, here 6 months. The different phases of hibernation may serve as an indicator of this mechanism. It is suggested, that the transformations taking place during prehibernation and posthibernation, and resulting in the germination of the gemmula are inhibited during hibernation proper by a substance formed in prehibernation.     

The Antioxidant System of Wheat Seeds during Germination

The dynamics of peroxidase activity and antioxidant contents in wheat seeds were studied in the course of 24-hour swelling at 5°C (group 1) and 23°C (group 2). Both parameters were 1.5 times higher in seeds of the first group. In the same seeds, peroxidase activity in the endosperm and seed coat increased by factors of 1.5 and 1.8, respectively. Catalytic constants of wheat seed peroxidase were determined in the reactions of o-dianisidine and ascorbic acid peroxidation. In the pH range studied (pH 5–7), K _m proved to change only slightly. In seedlings, an increase in the lipid peroxidation rate was accompanied by an increase in the content of antioxidants. Peroxidase activity increased as the content of antioxidants decreased, and vice versa. Thus, the reciprocal influence of peroxidase and low-molecular antioxidants during seed germination in wheat was revealed.     

Thermokinetic and energetic profiles of the yeast Debaryomyces hansenii in the presence of sodium chloride

Summary Sodium chloride decreased the growth yield with respect to glucose by 60% (at 17% NaCl, w/v), and narrowed the temperature span of growth of Debaryomyces hansenii from 6.8–40.5°C without the salt to 13.2–34.5°C with 16% NaCl. The thermokinetic profile (conjunct display of the Arrhenius plots of the specific rates of growth and thermal death) was dissociative either without or with NaCl, the minimum temperature of thermal death increasing from 42 to 45°C with 10% NaCl.     

The effect of temperature on the growth and lipid composition of the extremely halophilic coccus,Sarcina marina

Sarcina marina (NCMB 778) grew over the temperature range 20–45°C but no growth was recorded at 15°C or 50°C. At the optimum growth temperature of 34°C the doubling time was 14.5 h.The major polar lipid components, tentatively identified as the diether analogues of phosphatidyl glycerophosphate (PGP), phosphatidyl glycerol (PG), diglycosyl diglyceride (DGD) and triglycosyl diglyceride (TGD), and the major neutral lipid components, tentatively identified as squalene, dihydrosqualene, tetrahydrosqualene, vitamin MK8, geranyl geraniol and di-O-phytanyl glycerol, are identical to those found in other extremely halophilic rods and cocci.The total lipid content varied with growth conditions from 0.6 – 3.2% of the dry cell weight, polar lipids accounted for between 94.3 and 83.6% of the total lipid, the remainder being neutral lipid.In response to both the transition from exponential to stationary phase and a reduction of 14°C in growth temperature, batch cultures showed: (i) an increase in total lipid content; (ii) a decrease in PG and (iii) an increase in PGP. Specific responses to the temperature decrease were (i) increased total lipid content; (ii) no decrease in neutral lipids in stationary phase; (iii) marked reduction in PG and (iv) raised DGD. (i) and (ii) could be mechanisms for increasing membrane fluidity.In common with all other extreme halophiles investigated the alkyl side chains of S. marina polar lipids were identified as the phytanyl (3R, 7R, 11R, 15-tetramethylhexadecyl) group. Its structure did not appear to vary with temperature so that the normal mechanisms for modifying the structure of lipid alkyl side chains to modulate membrane fluidity in response to temperature changes probably does not occur in this group of microorganisms.     

Behaviour of proteolytic Clostridium botulinum types A and B near the lower temperature limits of growth

Summary The behaviour of spores of Clostridium botulinum type A and proteolytic C. botulinum type B has been studied in cooked meat medium at 10°C, 12°C, 15°C, and 20°C, using mixed cultures (9 groups of in total 41 strains) and pure cultures (41 strains).At 10°C a decrease of 1–1.5 log cycles for type B and of 2–4 log cycles for type A Clostridia was observed. Neither growth nor toxin formation could be demonstrated.At 12°C spores of some strains developed and formed toxin with 3–4 weeks, whereas other strains did not develop within 7 weeks.At 15°C growth and toxin formation could be observed within 1 week, whereas at 20°C toxin was formed mostly within 2 or 3 days. Incubation at 10°C prior to incubation at 20°C seemed to have some effect on the lag time.     

Chilling Tolerance of Potato Plants Transformed with a Yeast-Derived Invertase Gene under the Control of the B33 Patatin Promoter

Tolerance to chilling was compared under in vitro conditions in potato plants (Solanum tuberosum L., cv. Désirée) transformed with a yeast-derived invertase gene under the control of the B33 class 1 tuber-specific promoter (the B33-inv plants) and potato plants transformed only with a reporter gene (the control plants). The expression of the inserted yeast invertase gene was proved by following the acid and alkaline invertase activities and sugar contents in the leaves under the optimum temperature (22°C). The total activities of acid and alkaline invertases in the B33-inv plants exceeded those in the control plants by the factors of 2–3 and 1.3, respectively. In the B33-inv plants, the activity of acid invertase twice exceeded that of the alkaline invertase, whereas the difference equaled 12% in the control plants. The contents of sucrose and glucose increased in the B33-inv plants by 21 and 13%, respectively, as compared to the control. Chilling at +3 and –1°C for 1, 3, and 6 h did not affect the rate of lipid peroxidation, as measured by the content of malonic dialdehyde (MDA) in the leaves of the genotypes under study. Only the longer exposures (24 h at +3 and –1°C and 7 days at +5°C) produced a significant decline in the MDA content in the B33-invplants, as compared to the control. Following short freezing (20 min at –9°C), the content of MDA increased by 50% in the leaves of the control plants, while in the B33-inv plants, cold-treated and control plants did not differ in the MDA content. The authors presume that the potato plants transformed with the yeast invertase gene acquire a higher tolerance to low temperatures as compared to the control plants, apparently due to the changes in sugar ratio produced by the foreign invertase.     

Effect of incubation temperature on zearalenone production by strains of Fusarium crookwellense

After 6 weeks incubation on rice 2 strains of Fusarium crookwellense produced more zearalenone (6060–5010 mg/kg dry wt of culture) at ambient temperature (16–29°C) in daylight than at ambient temperature (18–23 °C) in darkness or at controlled temperatures of 11 °C, 20 °C or 25 °C in darkness. Yields at 25 °C were low. Incubation at 11 °C during the second 3 weeks incubation increased yields only when preliminary incubation had been at 25 °C. After 6 weeks incubation at controlled temperatures in darkness, 4 strains produced most zearalenone at 20 °C (2460-21 360 mg/kg), 1 strain at 11 °C (6570 mg/kg). Yields at a temperature oscillating daily from 10–20 °C were less than at 15 °C. One of the 5 strains produced appreciable amounts of a-zearalenol (1645 mg/kg at 20°C) and 2 of nivalenol (340 and 499 mg/kg at 20 °C).     

Interactions between photoperiodism and temperature with respect to the control of dormancy in the adult stage of Pterostichus oblongopunctatus F. (Col., Carabidae)

Summary Pterostichus oblongopunctatus belongs to the type of spring breeding carabids with adult hibernation. Ovarian maturation is under the control of photoperiod: the females need a change of day length to mature. The first step of egg maturation (previtellogenesis) is bound to short day, the second step (vitellogenesis) to long day.The short day effect is achieved almost only at temperatures of 10 to 15°C; it is completely suppressed by 20°.The males mature under very different photoperiods and temperatures, but long day diminishes the percentage of mature males slightly, as well as does the higher temperature of 20°C in short day as compared with 15°C.Simulation of climatic conditions as experienced by the beetles from autumn throughout winter until spring in the laboratory showed that a short span of favourable temperatures at short day as experienced in nature in autumn allows the females to accomplish the short day development. But this maturation effect is still more diminished the longer temperatures below 5°C act on the beetles. Following that, a second period of temperatures between 10–15°C must restore the short day maturation effect if full maturity shall be gained in the following long day.The beetles are able to store reserve materials under long day at 20°C. After such a period they are able to have a normal previtellogenesis in spite of a severe shortage of food during short day. These experiments indicate that the failure in short day development outside the temperature range of 10–15°C is not a matter of an especially well balanced over-all metabolism in this favourable temperature range. It seems rather that hormonal systems involved in the short day phase of oogenesis act only within this span of temperature.Supportet by the Deutsche Forschungsgemeinschaft.     

Some aspects of the metabolism of hibernating and recently aroused common dormouse Muscardinus avellanarius L. (Rodentia,Gliridae)

Summary A dormouse found in hibernation in its winter nest on January 26 was studied continously from February 5 until May 11 by recording ambient temperature, temperatures inside the nest ball and 5 cm from it, and by recording any possible motor activity. The first emergence from hibernaculum occurred on April 3 after which the animal was active each day with the exception of April 11, 13 and 14. Activity mainly occurred during evening and night hours and lasted on average 4 hrs (2–8 hrs) per day. Outside periods of activity the winter nest was consistently used as a place of shelter and for sleep.The ambient temperature ranged from-0.5° to 21.0°C being chiefly 1°C less the nestbox temperature. The difference between the nest-box and nest temperature was also about 1°C when the animal was inactive, thus clearly indicating torpidity. Steep increases in nest temperature, amounting to 14–18°C and raising nest temperature up to 30°C, were recorded on four occasions. This is interpreted as shallow torpor, since no activity occurred on these days.The spontaneous warming up from deep hypothermia to shallow torpor lasted on average 40 min (30–70 min), while the duration of passive cooling when returning to the hypothermic condition amounted to 5 hrs. In the weeks following continuous hibernation the dormouse alternated between activity, shallow torpor, and relatively deep torpor each day. The species should be considered as a true aestivator.     

Studies on the rust,Maravalia cryptostegiae,a potential biological control agent of rubber-vine weed,Cryptostegia grandiflora (Asclepiadaceae: Periplocoideae), in Australia,II: Infection

The parameters which govern infection of rubber-vine weed by the rustMaravalia cryptostegiae were investigated. The infection process, from appressorial formation to sporulation, is described and illustrated. Uredinioid teliospores have an optimum temperature range for germination at 22–27 °C, both in vitro and in vivo. However, germination on the rubber-vine leaf was more than double (81–92%) that in the absence of the host, and appressoria were formed only in vivo. An optimum temperature of 20–22°C and a dew period of 12 hours or more gave the highest level of infection as measured by sporulation density. The latent period from inoculation to pustule formation decreased with increasing temperature; the shortest period (8–11 days) being recorded at 25–27°C. At the lower temperatures (18°C), this was significantly extended (19–21 days). Four successive inoculations significantly reduced plant height and dry weight, although a compensatory growth flush occurred after the third inoculation. The addition of cryoprotectants had a negative affect on spore viability and subsequent infectivity. Cooling dry spores to –196°C at the rate of 10°C min^–1 gave the best results, with high germination (93–65%) up to 8 days after thawing.     

Lipid formation in the oleaginous mould Entomophthora exitalis grown in continuous culture: effects of growth rate,temperature and dissolved oxygen tension on polyunsaturated fatty acids

Summary The oleaginous fungus Entomophthora exitalis was grown in continuous culture at a constant dilution rate (0.04 h^–1) and over a range of temperatures (20–30° C). As the growth temperature was decreased from 30 to 20° C the percentage of polyunsaturated fatty acids (PUFA) increased proportionally from 18 to 27% (w/w) of the total fatty acids. The increase in unsaturation was as a result of an increased proportion of n-6 PUFA (particularly arachidonic acid) in the phospholipid and sphingo- plus glycolipid fractions. The triacylglycerol fraction of lipids displayed a negligible change. The proportion of phospholipids within the extracted lipid increased between 26 and 20° C without any change in the lipid content of the fungus. Although the changes in lipid unsaturation correlated, at first inspection, to the culture dissolved O₂ tension (DOT), growth of the fungus at a constant dilution rate and temperature (22° C) over a range of DOT values failed to influence lipid unsaturation. Thus temperature is the principal regulation factor of the degree of unsaturation in the lipids of this organism. Offprint requests to: C. Ratledge     

Behavioural response and winter survival of mated and unmated diapausing females of the Tetranychus atlanticus-urticae complex (Acari, Tetranychidae)

Behavioural responses were studied in mated and unmated females of a Dutch strain of the spider mite Tetranychus urticae which were destined to enter diapause. Observations were confined to the period between acquirement of the winter coloration by the females (a few days after the last moult) and their entering of artificial hibernation sites offered to the mites on the host leaves. Unmated females were found to stay longer on the leaf surface than mated females; they entered the hibernation sites significantly later than mated females. The delay in the search for hibernation sites shown by unmated females may be seen as a behavioural adaptation to enhance the chance of being fertilized before hibernation. Winter survival of mated and unmated diapausing females of the same strain of mites was studied both in the laboratory at a constant temperature of 2±1°C and outdoors under natural climatic conditions in Amsterdam during the winter of 1990–1991. Survival was high under both conditions for mated as well as unmated females; no significant differences in survival were found between both types of female. Observations on post-diapause females of Tetranychus atlanticus (a mite belonging to the T. urticae complex) sampled from strawberry fields near Moscow in spring, showed that at most 10% of the females of this natural spider mite population were unmated. Both mated and unmated females had survived winter temperatures of -28 to -30°C.     

Composition of the lipids of <Emphasis Type="Italic">Nanoarchaeum equitans</Emphasis> and their origin from its host <Emphasis Type="Italic">Ignicoccus</Emphasis> sp. strain KIN4/I

The contents and nature of the membrane lipids of Nanoarchaeum equitans and Ignicoccus sp. strain KIN4/I, grown at 90°C, and Ignicoccus sp. strain KIN4/I, cultivated at its lowest and highest growth temperatures (75°C and 95°C) were analyzed. Both organisms contained very simple and qualitatively identical assemblages of glycerol ether lipids, showing only differences in the amounts of certain components. LC–MS analyses of the total lipid extracts revealed that archaeol and caldarchaeol were the main core lipids. The predominant polar headgroups consisted of one or more sugar residues attached either directly to the core lipid or via a phosphate group. GC–MS analyses of hydrolyzed total lipid extracts revealed that the co-culture of N. equitans and Ignicoccus sp. strain KIN4/I, as well as Ignicoccus sp. strain KIN4/I grown at 90°C, contained phytane and biphytane in a ratio of approximately 4:1. Purified N. equitans cells and Ignicoccus sp. strain KIN4/I cultivated at 75°C and 95°C had a phytane to biphytane ratio of 10:1. Sugar residues were mainly mannose and small amounts of glucose. Consistent ¹³C fractionation patterns of isoprenoid chains of N. equitans and its host indicated that the N. equitans lipids were synthesized in the host cells.     

Effects of sodium chloride on the plasma membrane of halotolerant Dunaliella primolecta: an electron spin resonance study

Electron spin resonance spectroscopy was used to monitor the in vivo microviscosity of the plasma membrane and lipid extracts of the salt tolerant alga, Dunaliella primolecta. The fluidity of the plasma membrane decreased as the algae were adapted to and suspended in higher sodium chloride concentrations [2–24% (w/v)]. Both biochemical modification and a physical interaction between Na⁺ and lipids were implicated.When the microviscosity of the plasma membrane and that of lipid extracts were determined as a function of temperature, two or three lipid phase transformations were observed. There were always transformations at 9–14° C and 39–43° C. These were interpreted as the onset and completion of the lipid phase transition of at least a major lipid component of the membrane, possibly the entire membrane. These transformation temperatures were independent of the salt concentration to which the algae were adapted or suspended. This suggests that D. primolecta exists with some of its membrane in the solid-fluid mixed lipid state. With a NaCl concentration of 8% (w/v) or greater in the growth medium, a third transformation occurred around 20–22° C. It was the result of a lipid-lipid interaction and was not related to adaptation.Abbreviations ESR electron spin resonance spectroscopy - 2 T hyperfine splitting - S order parameter - 5-DS or 5-doxyl-stearate 2-(3-carboxylpropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl