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11.
Premjit P. Halarnkar Charles R. Heisler Gary J. Blomquist 《Archives of insect biochemistry and physiology》1987,5(3):189-199
The metabolism of succinate was examined in the housefly Musca domestica L. The labeled carbons from [2,3-14C]succinate were readily incorporated into cuticular hydrocarbon and internal lipid, whereas radioactivity from [1,4-14C]succinate was not incorporated into either fraction. Examination of the incorporation of [2,3-14C]succinate, [1-14C]acetate, and [U-14C]proline into hydrocarbon by radio-gas-liquid chromatography showed that each substrate gave a similar labeling pattern, which suggested that succinate and proline were converted to acetyl-CoA prior to incorporation into hydrocarbons. Carbon-13 nuclear magnetic resonance showed that the labeled carbons from [2,3-13C]succinate enriched carbons 1, 2, and 3 of hydrocarbons with carbon-carbon coupling showing that carbons 2 and 3 of succinate were incorporated as an intact unit. Radio-high-performance liquid chromatographic analysis of [2,3-14C]succinate metabolism by mitochondrial preparations showed that in addition to labeling fumarate, malate, and citrate, considerable radioactivity was also present in the acetate fraction. The data show that succinate was not converted to methylmalonate and did not label hydrocarbon via a methylmalonyl derivative. Malic enzyme was assayed in sonicated mitochondria prepared from the abdomens and thoraces of 1- and 4-day-old insects; higher activity was obtained with NAD+ in mitochondria prepared from thoraces, whereas NADP+ gave higher activity with abdomen preparations. These data document the metabolism of succinate to acetyl-CoA and not to a methylmalonyl unit prior to incorporation into lipid in the housefly and establish the role of the malic enzyme in this process. 相似文献
12.
13.
This essay attempts to summarize some of the best evidence for the role of inositol trisphosphate as a second messenger in signal transduction processes. The following aspects are addressed in the essay: (a) The synthesis of inositol trisphosphate and other inositol lipids, (b) Receptor-phosphatidylinositol bisphosphate phospholipase C coupling and the N-ras protooncogene, (c) Inositol trisphosphate and intracellular calcium, (d) Cell growth and oncogenes, (e) Receptors linked to the phosphatidylinositol cycle, (f) Phototransduction and (g) Interactions between inositol trisphosphate and other second messengers.Abbreviations Cyclic AMP
Adenosine 3,5-cyclic monophosphate
- Cyclic GMP
Guanosine 3,5-cyclic monophosphate
- DG
sn, 1,2-Diacylglycerol
- EGF
Epidermal growth factor
- GDP
Guanosine diphosphate
- GTP
Guanosine triphosphate
- IP
Inositol 1-monophosphate
- IP2
Inositol 1,4-diphosphate
- IP3
Inositol 1,4,5-trisphosphate
- PA
Phosphatidic acid
- PDGF
Platelet-derived growth factor
- PI
Phosphatidylinositol
- PIP
Phosphatidylinositol 4-monophosphate
- PIP2
Phosphatidylinositol 4,5-bisphosphate
- PIP3
Phosphatidylinositol 3,4,5-trisphosphate
- PLC
Phospholipase C 相似文献
14.
Seed dimorphism in Salicornia europaea: Nutrient reserves 总被引:1,自引:0,他引:1
Franz-Arnold Austenfeld 《Physiologia plantarum》1988,73(4):502-504
Median and lateral seeds of Salicornia europaea L. were separately analysed for their sizes and nutrient reserves. The mean air-dry weight of a single median and lateral seed was 0.31 and 0.25 mg, respectively. The composition as well as the concentration of the nutrient reserves were similar in both seed types. The bulk of the cations was derived from K+ , followed by Mg2+ , Na+ and Ca2+ . The chloride content was somewhat higher than the sodium content, and phosphate was equalled by acid soluble Ca2+ and Mg2+ . Starchy compounds and sucrose were present in equal amounts, each of them accounted for about 50% of the carbohydrates. Glucose and fructose were less than 1%. Protein-nitrogen (ethanol-insoluble N) was about 34 g (kg dry seeds)−1 . About 7 g (kg dry seeds)−1 was ethanol-soluble nitrogen, of which 10% was derived from amino acids. The total lipid content was more than 290 g (kg dry seeds)−1 , 65% were calculated to be glycerides. More than 90% of the fatty acids consisted of linoleic and oleic acids, the majority (72%) of which was linoleic acid. 相似文献
15.
Alterations in lipid content and composition in the N-nitrosodiethylamine-induced hepatocarcinoma were investigated. Rats were administrated with N-nitrosodiethylamine in the drinking water for 12 weeks followed by normal tap water for another 6 weeks. The cholesterol content in the liver was increased shortly after the administration of N-nitrosodiethylamine and remained elevated after the removal of the nitrosoamine from the water. The phosphatidylethanolamine level was elevated during N-nitrosodiethylamine administration with a concomitant reduction in phosphatidylcholine level. Lysophosphatidylcholine and sphingomyelin levels were increased during the last four weeks of the study. The level of phosphatidylinositol was substantially reduced after eight weeks of N-nitrosodiethylamine treatment, and remained low during the post-treatment period. We postulate that changes in lysophosphatidylcholine and sphingomyelin may be a compensatory mechanism for maintaining the asymmetrical distribution of choline-containing lipids in the outer leaflet of the membrane. The elevated level of cholesterol may be a useful indicator for the early detection of N-nitrosodiethylamine-induced hepatocarcinoma. 相似文献
16.
Specimens from Scotland, S. and C. Norway were grown in the botanical garden of Bergen, Norway. Some of the Scottish specimens came from a meristem tissue culture. The specimens were compared by a principal component analysis of lipids and related compounds, and of morphological characters from leaves and flowers. The populations differed from each other, but some overlap was found in leaf characters. The results are discussed in relation to distribution and immigration history, and it is argued that the differences among the populations may have evolved in postglacial time. 相似文献
17.
Pigment and lipid compositions of algal and bacterial communities in Ace Lake,Vestfold Hills,Antarctica 总被引:1,自引:0,他引:1
The compositions of carotenoids, chlorophylls and lipids at four depths in Ace Lake have been determined as a means of studying the vertical zonation of species in the lake and for comparison with the lipids found in the bottom sediments. The four major species of phytoplankton found in the lake were identified by electron microscopy. The most abundant phytoplankter was Pyramimonas gelidicola McFadden (Chlorophyta, Prasinophyceae) which occurred in greatest numbers at 10 m, the base of the oxylimnion. The pigments and lipids at this depth were mainly derived from this alga. At 11 m (the top of the anoxylimnion) only traces of lipids and pigments attributable to P. gelidicola were found, indicating only limited settling of algal cells through to the anoxylimnion, at least in summer. The pigments at 11 m were dominated by bacteriochlorophylls c derived from green photosynthetic bacteria Chlorobium spp. These pigments were also abundant at 23 m suggesting the presence of intact bacterial cells which had settled out from higher in the water column. Major non-polar lipid classes in the sediments included sterols, alcohols, hydrocarbons and an unusual suite of very long-chain unsaturated ketones and esters which have not previously been reported from antarctic environments. Several novel compounds, not found previously in either sediments or organisms, are reported. These include tri- and tetra-unsaturated straight-chain C39 methyl ketones and C40 ethyl ketones and the methyl ester of a tetra-unsaturated straight-chain C36 fatty acid. The distributions of lipids in the sediment were markedly different from those in the water column indicating extensive bacterial degradation and recycling of labile lipids. 相似文献
18.
Summary Preparations of basal-lateral plasma membranes from rat intestinal epithelial cells were analyzed with the analytical centrifuge. In these preparations a number of well-defined membrane fractions were observed. The particle weights of these fractions appear to fit in two geometric series. Until now only relatively small vesicles up to a diameter of about 1 m were observed. In our preparation we have observed vesicles up to a diameter of 7.5 m. Therefore, even vesicles with the same size as the plasma membranes of intact cells fit in the two geometric series. 相似文献
19.
S. O. Aisien F. I. Opute S. N. Ali B. A. Obiamiwe 《International journal for parasitology》1986,16(6):655-657
& Obiamiwe B. A. 1986. Lipid composition of adult Foleyella agamae. International Journal for Parasitology 16: 655–657. The lipid and fatty acid composition of the filarial parasite Foleyella agamae were investigated. Total lipids accounted for 7.05% of the parasite fresh weight. Neutral lipids comprised 56.34% of the total and polar lipids 43.66%. The major lipid classes detected include sterol esters, cholesterol, phosphatidyl choline and phosphatidyl ethanolamine. Fatty acids varying in chain length from 10 carbon atoms through 20 carbon atoms were identified in the total lipid extract. The 18 carbon fatty acids formed the predominant components. The 20 carbon fatty acids were confined to the polar lipds. 相似文献
20.
S. Bruno S. Cannistraro A. Gliozzi M. De Rosa A. Gambacorta 《European biophysics journal : EBJ》1985,13(2):67-76
A spin label study has been carried out on bipolar lipids extracted from Sulfolobus solfataricus, an extreme thermophilic archaebacterium growing at about 85°C and pH 3. These lipids are cyclic diisopranyl tetraether molecules, quite different from the usual fatty acid lipids. Two hydrolytic fractions of the membrane complex lipids have been studied: the symmetric lipid glycerol-dialkyl-glycerol-tetraether (GDGT) and the asymmetric lipid glyceroldialkyl-nonitol-tetraether (GDNT). The ESR spectra confirm the results previously obtained from calorimetric and X-ray diffraction experiments showing a polymorphic behaviour of these lipids and indicating the critical temperature ranges at which structural transitions occur. Moreover, the present study adds information on the dynamics of the different portions of the hydrophobic chain. ST-ESR measurements show correlation times ranging from 10-8 s up to 10-5 s, depending upon the lipid sample, the label position and the degree of hydration. At very high temperatures, i.e. the physiological temperatures of Sulfolobus solfataricus, the nonitol head groups of the asymmetric lipids form a strongly immobilized structure. Indeed, the molecular correlation times of the outermost hydrophobic portion of GDNT are higher, by a factor up to 103, than those of usual monopolar lipids. Anisotropic motional behaviour is observed even at such very high temperatures. Possible biological implications are discussed.Abbreviations used are ESR
electron spin resonance
- St-ESR
saturation transfer electron spin resonance
- GDGT
glyceroldialkyl-glycerol-tetracther
- GDNT
glycerol-dialkyl-nonitoltetraether
- 5 SASL
12SASL and 16SASL, stearic acid spin labels, N-oxyl-4,4-dimethyloxazolidine derivatives of 5-ketostearic acid, 12-ketostearic acid and 16-ketostearic acid, respectively
- DSC
differential scanning calorimetry 相似文献