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1.
The accumulation of 65Zn and 54Mn from water by the thornback ray, Raja clavata L., has been studied at tissue level and their levels of accumulation have been related to stable element concentrations. The accumulation of 58Co and 59Fe has also been studied on a whole body basis and comparisons have been made of the 59Fe levels in the tissues after 84 days with those of the stable element. It was found that lower values of accumulation of the radionuclides were obtained than in the case of the teleost Pleuronectes platessa L.. Such differences are discussed in relation to the relative permeabilities of the two species to sea water and the relative ratios of the radionuclides from sea water to blood plasma, and of blood plasma to organ. It is concluded that for both species direct input from water plays only a minor rôle in the accumulation of the four radionuclides studied.  相似文献   

2.
Some further studies on the accumulation and retention of 64Zn and 54Mn by plaice, Pleuronectes platessa L., have been made. Direct accumulation from water, by eggs and larvae, is insufficient to account for the concentrations of these metals in young fish. It appears, therefore, that, from the earliest stages, food constitutes the major pathway for accumulation. Stable element analyses of liver, muscle, and bone samples from fish of differing weights and ages show that their concentrations, in adult fish, remain fairly constant. On this basis it has previously been estimated that biological half-times of these metals via food should be shorter than those observed after accumulation from labelled water. Experiments following the loss of the isotopes from fish which had been fed labelled polychaete worms support this view.  相似文献   

3.
The accumulation of inorganic mercury from sea water by plaice eggs, larvae, and adult fish has been studied using 203HgCl2 as a tracer. The isotope was rapidly accumulated and the levels of accumulation have been related to stable element concentrations. High concentration factors were attained by many organs, but the distribution of the 203Hg was markedly different from that of the stable element. Whereas the largest fraction of the body burden of mercury is contained by muscle, only a slow rate of accumulation into this tissue was observed. In addition, the mercury in fish muscle is of the methyl form: no evidence for the methylation of the tracer was obtained.  相似文献   

4.
After U14C leucine or U14C valine injections into haemolymph of adult female Glossina morsitans during late pregnancy, radioactivity was detected in the post-parturient female and its larval offspring in the injected material, lipids, and a range of non-essential amino acids. The level of radioactivity recorded from the third instar larva was higher than that remaining in the injected adult, and the activity was higher in amino acids than in the lipid fraction. Radiometric analysis of oöcyte and intra-uterine progeny 24 hr after haemocoelic administration to females of labelled leucine or valine revealed a pattern of radioactivity coincident with growth characteristics of these young stages. Rate of leucine uptake by the in utero third instar larva was slightly higher than that of valine, and this instar continues feeding even only a few hours before parturition. For both labelled materials, expired carbon dioxide and excreta from remales in early pregnancy showed significantly higher radioactivity than those in late pregnancy. Uric acid is the main nigrogenous waste of leucine and valine metabolism, though small amounts of these amino acids are also lost during excretion, with valine elimination being higher than leucine.  相似文献   

5.
1-Palmitoyllysophosphatidylcholine has been mixed in equimolar amounts with specifically deuterated palmitic acid and the structural properties of the lipid/water phase have been studied by 2H- and 31P-nuclear magnetic resonance. The order profile of the free palmitic acid is very similar to that of the parent compound 1,2-dipalmitoyl-sn-glycero-3-phosphocholine at temperatures above the gel-to-liquid crystal phase transition. The bending of the sn-2 chain which is typical for diacyl lipids is not observed for the free palmitic acid. The mixture of lysolipid and palmitic acid exhibits well-defined quadrupole splittings even at temperatures below the gel-to-liquid crystal phase transition. Hence it is possible for the first time to establish an order profile in the gel-state of the lipid bilayer phase. Between carbon atoms 5 to 12 the palmitic acid chain is found to assume the extended all-trans conformation with a very small contribution from gauche defects. Towards the methyl terminal a distinct increase in the gauche probability can be noted. The motion of the phosphocholine headgroup was also studied by 2H- and 31P-NMR using selectively deuterated 1-palmitoyllysophosphatidylcholine. The headgroup has a considerably larger motional freedom in the mixture of lysolipid and palmitic acid than in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine. In addition, the average headgroup conformations are also different in the two systems.  相似文献   

6.
The dynamics of Na+, K+, and proline accumulation in various organs of non nodulated Vigna sinensis and Phaseolus aureus was followed during their acclimation to two levels of salinities for a period of 35 days and was correlated to the vegetative growth of the two species. The rate of Na+ and K+ absorption is at a maximum during the first 15 to 20 days of culture. K+ absorption is not completely inhibited even at 100 mM NaCl although the endogenous Na+ largely surpasses that of K+ in certain organs. Low salinity rather accelerates K+ absorption in both species. The relative growth rates (RGR) correlate with the rate of Na+ and K+ accumulation. At low salinity (10 mM NaCl), the RGR of V. sinensis is greater than that of P. aureus. However, at high salinity (100 mM NaCl) the RGR is the same for both species. The growth of the younger parts of the two species is not arrested by salt treatment. Very high accumulation of Na+ is avoided in organs with less vacuolated tissues. At no time does the endogenous K : Na ratio in these organs fall below 1.0. Certain organs, especially the roots, hypocotyls, and the lower parts of the stems are capable of storing large quantities of Na+. In V. sinensis, the accumulated Na+ and K+ are evenly distributed among the various organs while in P. aureus they are rather concentrated in the roots. External salinity creates water deficiency in the younger plant parts and as a consequence, proline accumulates especially in the youngest aerial organs - more in P. aureus than in V. sinensis. The accumulation of this amino acid in both the species is dependent on time and correlates directly, not only with the water deficit, but also with the K+ contents. In contrast, it does not seem to depend directly on the endogenous Na+ content. The relative salt tolerance of the two species and the possible role of K+, Na+ and proline in the osmotic adjustments of the two species under saline conditions are discussed.  相似文献   

7.
Alkaloid biosynthesis has been demonstrated in the young expanding tissues of Erythrina crista-galli shoots, the stem part of which elaborated, from [2-14C]-tyrosine, alkaloid of specific radioactivity 2μuCi mmol?1, 10-fold greater than previously reported.  相似文献   

8.
Incorporation of leucine and changes in different protein fractions have been studied during Sorghum grain development. Most of the label from the injected leucine-[14C] was found in glutelin and residue fraction towards later stages of maturity. The label in albumin, globulin and prolamin decreased with a concomitant increase in label in glutelin and residue proteins. The concentration of lysine, aspartic acid and glycine decreased while that of leucine, proline, alanine, tyrosine, phenylalanine, and cystine increased during grain development. Increase in serine, methionine, valine and isoleucine was only marginal. The proportion of glutamic acid was high at all stages of grain development. Glutelin fraction resolved into two peaks on gel chromatography, only one of which with higher MW was labelled, while in albumin both the peaks were found to be labelled. Tannin content also increased during grain development.  相似文献   

9.
The formation of an enzyme-inhibitor adduct between bovine trypsin and [2-13C]p-amidinophenylpyruvic acid has been investigated by 13C NMR spectroscopy. The observation of a resonance at 100.8 ppm demonstrates that the hemiketal formed between the hydroxyl of serine-195 and the 2-13C carbon of p-amidinophenylpyruvic acid is sp3 hybridized with no significant deviation from tetrahedral geometry. It is shown that stabilization of the hemiketal oxyanion if it occurs is less effective than in chloromethylketone inhibitor complexes. The tetrahedral adduct is stable from pH 3 to 8. The mechanisms of breakdown of the tetrahedral adduct at pH extremes are discussed.  相似文献   

10.
A possible receptor for thrombin on the platelet membrane has been identified. Whole platelets were treated with 125I-labelled thrombin followed by washing of the platelets, solubilization in Triton X-100, crossed immunoelectrophoresis and autoradiography. A heavily labelled antigen which migrated slightly more slowly than albumin was observed. No corresponding arc was seen on the same immunoplate when stained with Coomassie brilliant blue, indicating that the antigen possessed weak antigenic properties and/or was present in very small amounts. When 125I-labelled thrombin that had been inactivated by phenylmethylsulphonyl fluoride was used, no such labelled arc was seen. The radiolabelled immunoprecipitate does not represent any of the antigens identified hitherto in the immunoelectrophoretic patterns obtained with platelets or platelet material. The electrophoretic mobility of the antigen was influenced neither by neuraminidase treatment of the platelets prior to the 125I-labelled thrombin exposure nor by inclusion of concanavalin A, wheat-germ lectin or lentil lectin in the gel during the first-dimension electrophoresis. This suggests that the antigen does not represent a glycoprotein. Upon subcellular fractionation the radioactively labelled arc was observed in the cytosol fraction following crossed immunoelectrophoresis and autoradiography. Analysis of the secreted proteins after induction of the release reaction with 125I-labelled thrombin revealed labelling of immunoprecipitates representing thrombospondin, albumin and the ‘line’ form of platelet factor 4. This confirms that stable complexes of 125I-labelled thrombin and platelet proteins can exist in the presence of Triton X-100 and during electrophoresis.  相似文献   

11.
With the successful development of methods for the isolation and purification of ethanol-insoluble cinnamic acid esters in mint it became possible to initiate kinetic, isotopic studies on purified, ‘insoluble’ derivatives of caffeic acid, ferulic acid and p-coumaric acid. Pulse-feeding experiments were conducted with 14CO2, phenylalanine-U-14C and cinnamic acid-3-14C. The ferulic acid derivative exhibited a significant turnover as compared to the other insoluble derivatives which were relatively stable. Time-course tracer studies were performed to compare the turnover of soluble caffeic acid derivatives with ‘insoluble’ forms of caffeic acid. Caffeic acid associated with a macromolecular fraction consistently showed a higher specific activity than either soluble caffeic acid or the caffeic acid associated with a second insoluble derivative.  相似文献   

12.
The accumulation levels of anthropogenic 90Sr and 134Cs and 137Cs radionuclides in the marsh frog have been studied in the areas of the Beloyarskii water-storage reservoir (an industrial storm-water discharge channel of the nuclear power station) and the Verkhnii Tagil water-storage reservoir (the Tagil River down-stream of the dam). No significant distinction in the radionuclide accumulation (90Sr and 137Cs) depending on the amphibian sex and age is detected. Comparable levels of the accumulation of radionuclides in the marsh frog, when compared to the other representatives of the water ecosystem, are estimated. An assumption of the presence of some unidentified source of radioactive contamination of marsh frogs has been made; cesium-137 may be transferred from it to the Tagil River by the frogs.  相似文献   

13.
The metabolism of the prostaglandin F analogues, 15-methyl-Δ4-cis-PGF and 16,16-dimethyl-Δ4-cis-PGF, has been investigated in the cynomolgus monkey and the human female. The two analogues, tritium labelled in the 9β-position, were administered by intramuscular injections into the monkeys and by subcutaneous injections into the human. Excretion of tritium labelled products were followed in urine (in both species) and feces (in monkeys only) and several metabolites were identified by GC/MS. The analogues were found to be resistant to the 15-hydroxy dehydrogenase and furthermore the degradation by β-oxidation was delayed. About 13% of the given dose of 15-methyl-Δ4-cis-PGF was excreted unchanged into urine and feces from the monkey. The corresponding figure for 16,16-dimethyl-Δ4-cis-PGF was about 20%. In addition, a large part of the metabolites had the carbon skeleton intact and were only metabolized by ω-oxidation. The relative resistance to degradation of these two analogues is likely to be the basis for their prolonged pharmacological activity.  相似文献   

14.
J. Lavorel 《BBA》1973,325(2):213-229
The decay of luminescence in the 6–600-μs range following a microsecond flash has been studied in Chlorella. The decay is highly polyphasic; three kinetic components are outlined, in confirmation of the results of K. L. Zankel (1971, Biochim. Biophys. Acta 245, 373–385).Extrapolation of the decay to zero dark time suggests that a unique metastable species C?+, resulting from photochemical charge separation in the System II reaction center, is the substrate of the recombination reaction which gives rise to luminescence.The fast (5–10 μs) and medium (50–70 μs) phases of the decay denote different stabilization steps, preceding relaxation of the centers by electron and proton transduction to the photosynthetic chain.NH2OH specifically inhibits the fast phase and enhances the medium phase. This effect is explained by assuming that the fast phase results from electron transfer from the water splitting system Z to the oxidized primary donor Y.3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU), in the presence of NH2OH elicits another fast phase. It is believed that DCMU affords a parasitic stabilization of C?+ by forming a complex with Q?.  相似文献   

15.
Detailed records of the carbon and oxygen isotopic ratios of Neogloboquadrina pachyderma are compared between nine high-latitude sediment cores, from the Northern and Southern Hemispheres, covering the last 140 000 yrs. The strong analogies between the δ13C records permit to define a δ13C stratigraphic scale, with three clear cut transitions simultaneous with the oxygen isotopic transitions 6/5 (125 kyrs.), 5/4 (65 kyrs.), and 2/1 (13 kyrs.). The δ13C records of N. pachyderma in the high-latitude cores, which follow the changes in δ13C of the surface water TCO2 near areas of deep water formation present trends similar to the benthic foraminifera δ13C records in cores V19–30 and M12-392, although amplitudes of the isotopic shifts are different. This implies that a large part of the observed variations represents global changes in the carbon distribution between biosphere and ocean.The 13C/12C ratios of N. pachyderma in the North Atlantic cores display larger regional variations at 18 kyrs. B.P. than at present. To explain these differences, we have plotted the 18 kyrs. B.P. δ13C values of N. pachyderma from 17 cores distributed N of 40°N. Comparison with published surface water temperature distribution at 18 kyrs. B.P. indicates that a strong divergent cyclonic cell, centered approximatively 55°N and 15°W, was active during most of the last ice-age maximum This hydrology, analogous to the present Weddell Sea, explains the published evidences of bottom water formation, if located on the northern flank of the gyre, and the strong polar front on the southern flank, probable location of intermediate water formation.  相似文献   

16.
2H and 31P spin-lattice relaxation times (T1) were studied for invented egg phosphatidylcholine micelles in CCl4 as functions of 2H2O concentration. When the 2H2O/phosphatidylcholine mole ratio changed from 1.0 to 18.0, T1 of 31P increased by about 2.6 fold, whereas T1 of 2H increased by about 50 fold. A quantitative analysis of the deuterium T1 data showed that there is only one water molecule tightly bound to the polar head, and it is in rapid exchange with the rest of the water molecules. The activation energy for the deuterium T1 was 7.1 ± 0.8 kcal/mol (30 ± 3 kJ/mol), and was independent of the 2H2O concentration.  相似文献   

17.
A method is described for the efficient incorporation of radioactive arachidonic acid into the lipids of rabbit hearts and kidneys. Infusion of 14C-arachidonate through perfused tissues resulted in the quantitative removel of label from the media. Analysis of the lipids from tissues labeled by this procedure revealed that the majority of the 14C-arachidonate was incorporated into phospholipids. Essentially all of the radioactivity in phosphatidylcholine was found in the 2-position. Subsequent to the 14C-arachidonate infusion, stimulation of prostaglandin biosynthesis (e.g. by bradykinin) resulted in the release of radioactive prostaglandins. This suggests that the 14C-arachidonate is incorporated in a manner such that it is available for homone-stimulated prostaglandin biosynthesis. The method described allows both qualitative and quantitative analysis of arachidonate metabolism in intact tissues and offers significant advantages over other presently used methods.  相似文献   

18.
Fully assigned 13C-NMR spectra confirm the C40 (16,16 -biphytanyl) structures of the alkyl chains in the ether lipids of extreme thermoacidophile bacteria of the Caldariella group. The incorporations of 13C- and 14C- labelled acetate and mevalonate provide further structural confirmation and define their biosynthetic origin.  相似文献   

19.
Epidermal growth factor receptor (EGFR) has gained significant attention as a therapeutic target. Several EGFR targeting drugs (Gefitinib and Erlotinib) have been approved by US Food and Drug Administration (FDA) and have received high approval in clinical treatment. Nevertheless, the curative effect of these medicines varied in many solid tumors because of the different levels of expression and mutations of EGFR. Therefore, several PET radiotracers have been developed for the selective treatment of responsive patients who undergo PET/CT imaging for tyrosine kinase inhibitor (TKI) therapy. In this study, a novel fluorine-18 labeled 4-anilinoquinazoline based PET tracer, 1N-(3-(1-(2-18F-fluoroethyl)-1H-1,2,3-triazol-4-yl)phenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine (18F-FEA-Erlotinib), was synthesized and biological evaluation was performed in vitro and in vivo. 18F-FEA-Erlotinib was achieved within 50 min with over 88% radiochemical yield (decay corrected RCY), an average specific activity over 50 GBq/μmol, and over 99% radiochemical purity. In vitro stability study showed no decomposition of 18F-FEA-Erlotinib after incubated in PBS and FBS for 2 h. Cellular uptake and efflux experiment results indicated the specific binding of 18F-FEA-Erlotinib to HCC827 cell line with EGFR exon 19 deletions. In vivo, Biodistribution studies revealed that 18F-FEA-Erlotinib exhibited rapid blood clearance both through hepatobiliary and renal excretion. The tumor uptake of 18F-FEA-Erlotinib in HepG2, HCC827, and A431 tumor xenografts, with different EGFR expression and mutations, was visualized in PET images. Our results demonstrate the feasibility of using 18F-FEA-Erlotinib as a PET tracer for screening EGFR TKIs sensitive patients.  相似文献   

20.
The interaction between the plant hormone, 3-indoleacetic acid (IAA), and some phospholipids in CDCL3 has been studied by 1H, 13C and 31P nuclear magnetic resonance (NMR) spectroscopy. Upon interaction with IAA, significant changes occurred in resonance positions of the phospholipid head group nuclei. Alteration of the fatty acid composition influenced the effects of IAA on these nuclei. These effects were observed in the ethanolamine and phosphate groups of the phosphatidylethanolamines, and in the choline, phosphate and glycerol groups of the phosphatidylcholines. Changes in resonance positions of the phospholipid head group nuclei were used for the determination of dissociation constants (Kd). In all cases, Kd values were approx. 10?2 molal for 1 : 1 interaction. The NMR results suggest an interaction orientation in which the aromatic ring system of IAA interacts with the quaternary nitrogen function of the head group, and the phosphate group becomes hydrogen-bonded to the NH or carboxyl proton of 1AA.  相似文献   

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