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1.
Daily Rhythms of Metabolic Rate and Body Temperature of Two Murids from Extremely Different Habitats
Daily circadian rhythms of body temperature (Tb) and oxygen consumption (VO2) were measured in two murid species, which occupy extremely different habitats in Israel. The golden spiny mouse (Acomys mssalus) is a diurnal murid distributed in arid and hot parts of the great Syrio-African Rift Valley, while the broad-toothed field mouse (Apodeinns mystacinus) is a nocturnal species that inhabits the Mediterranean woodlands. In both species, the daily rhythms of Tb and VO2 are entrained by the photoperiod. Under laboratory experimental conditions (ambient temperature Ta = 33oC and photoperiod regime of 12L: 12D), Acomys russatus exhibits a tendency towards a nocturnal activity pattern, compared to the diurnal activity displayed by this species under natural conditions. Under the same photoperiod regime and at Ta = 28oC, Apodemus mystacinus displays nocturnal activity, as observed under natural conditions. The maximal values of Tb were recorded in Acomys russatus at midnight (23:50 h), while the maximal values of VO2 were recorded at the beginning of the dark period (18:20 h). In Apodemus mystacinus, the maximal values of Tb and VO2 were recorded at 23:40 and 20:00 h, respectively. The ecophysiological significance of these results is discussed further. 相似文献
2.
Carbon isotope ratios (13C/12C) were measured for the leaves of the seagrass Thalassia testudinum Banks ex König and carbonates of shells collected at the seagrass beds from seven sites along the coast of southern Florida, U.S.A. The δ13C values of seagrass leaves ranged from −7.3 to −16.3‰ among different study sites, with a significantly lower mean value for seagrass leaves from those sites near mangrove forests (−12.8 ± 1.1‰) than those far from mangrove forests (−8.3 ± 0.9‰; P < 0.05). Furthermore, seagrass leaves from a shallow water area had significantly lower δ13C values than those found in a deep water area (P < 0.01). There was no significant variation in δ13C values between young and mature leaves (P = 0.59) or between the tip and base of a leaf blade (P = 0.46). Carbonates of shells also showed a significantly lower mean δ13C value in the mangrove areas (−2.3 ± 0.6‰) than in the non-mangrove areas (0.6 ± 0.3‰; P <0.025). In addition, the δ13C values of seagrass leaves were significantly correlated with those of shell carbonates (δ13C seagrass leaf = −9.1 + 1.3δ13C shell carbonate (R2 = 0.83, P < 0.01)). These results indicated that the input of carbon dioxide from the mineralization of mangrove detritus caused the variation in carbon isotope ratios of seagrass leaves among different sites in this study. 相似文献
3.
At a temperature of 15oC, Gonyaulax polyedra responds to short days (light ≤ 10 h) by transition to the stage of a resting cyst. At 20oC, even an lightdark (LD) cycle of 6:18 is incapable of inducing this process. In otherwise cyst-inducing conditions (15oC; 10 h of light per day), an interruption of the scotophase by 2 h of light (LDLD 8:2:2:12 or 2:2:8:12) prevented encystment. Cyst induction is, therefore, initiated by a photoperiodic mechanism rather than by light deficiency. In Gonyaulax, photoperiodism may be mediated by the action of indoleamines. Melatonin, which exhibits a circadian rhythmicity in this organism, leads to encystment when given 1 h before lights-off in LD 11:13 at 15oC, i.e., under otherwise noninducing conditions. Again, at 20oC, melatonin is inefficient. Some analogues of melatonin, in particular, 5-methoxytryptamine and N,N-dimethyl-5-methoxytryptamine, and, at high concentrations, their respective precursors, serotonin and bufotenin, are capable of inducing cyst formation at 20oC and in LD 12:12, whereas A'-acetyl-serotonin does not show this effect. 相似文献
4.
Since very few previous studies have carried out the quantitative analysis for the colocalization of nitric oxide (NO) and vasoactive intestinal peptide (VIP) in the submucous neurons in the rat digestive tract, we applied in vivo treatment of colchicine to enhance the immunoreactivity and examined the colocalization of NO synthase (nNOS) and VIP in neurons of the submucous plexus throughout the rat digestive tract. The density of nNOS-containing neurons in the submucous plexus in the stomach corpus (103±25 cells/cm2, n=3) and that in the antrum (157±9 cells/cm2, n=3) were significantly lower than those in small and large intestine. However no difference was detected in the cell density among duodenum (1967±188 cells/cm2, n=3), jejunum (2640±140 cells/cm2, n=3), ileum (2070±42 cells/cm2, n=3), proximal colon (2243±138 cells/cm2, n=3) and distal colon (2633±376 cells/cm2, n=3). The proportion of nNOS-immunoreactive (IR), nNOS/VIP-IR and VIP-IR neurons to the total number of submucous neurons was examined. nNOS/VIP-IR neurons comprised 45–55% of total number of submucous neurons from the duodenum to the proximal colon, however those comprised 66.4±5.1% in the distal colon. The results showed that the dense distribution of nNOS-containing neurons was found in the submucous plexus throughout the small and large intestine, and large population of submucous neurons co-stored nNOS and VIP. 相似文献
5.
Robin M. Andrews 《Journal of thermal biology》1998,23(6):329-334
1. Using data from the literature, I assessed how broad climatic patterns affected field body temperatures (Tb’s) of lizards in the genus Sceloporus.
2. Sceloporus at temperate latitudes had mean Tb’s of 35°C throughout their elevational range. This pattern is associated with “tropical” temperatures that extend into high north latitudes during the summer and the relatively low elevations occupied by the lizards.
3. At tropical latitudes, mean Tb declined from 35°C at low elevations to 31°C at high elevations. This pattern is associated with low seasonal variation in temperature at tropical latitudes and the relatively high elevations occupied by the lizards. 相似文献
6.
The in vitro metabolism of cortisol in human liver fractions is highly complex and variable. Cytosolic metabolism proceeds predominantly via A-ring reduction (to give 3,5β-tetrahydrocortisol; 3,5β-THF), while microsomal incubations generate upto 7 metabolites, including 6β-hydroxycortisol (6β-OHF), and 6β-hydroxycortisone (6β-OHE), products of the cytochrome P450 (CYP) 3A subfamily. The aim of the present study was, therefore, to examine two of the main enzymes involved in cortisol metabolism, namely, microsomal 6β-hydroxylase and cytosolic 4-ene-reductase. In particular, we wished to assess the substrate specificity of these enzymes and identify compounds with inhibitory potential. Incubations for 30 min containing [3H]cortisol, potential inhibitors, microsomal or cytosolic protein (3 mg), and co-factors were followed by radiometric HPLC analysis. The Km value for 6β-OHF and 6β-OHE formation was 15.2 ± 2.1 μM (mean ± SD; n = 4) and the Vmax value 6.43 ± 0.45 pmol/min/mg microsomal protein. The most potent inhibitor of cortisol 6β-hydroxylase was ketoconazole (Ki = 0.9 ± 0.4 μM; N = 4), followed by gestodene (Ki = 5.6 ± 0.6 μM) and cyclosporine (Ki = 6.8 ± 1.4 μM). Both betamethasone and dexamethasone produced some inhibition (Ki = 31.3 and 54.5 μ, respectively). However, substrates for CYP2C (tolbutamide), CYP2D (quinidine), and CYP1A (theophylline) were essentially non-inhibitory. The Km value for cortisol 4-ene-reductase was 26.5 ± 11.2 μM (n = 4) and the Vmax value 107.7 ± 46.0 pmol/min/mg cytosolic protein. The most potent inhibitors were androstendione (Ki = 17.8 ± 3.3 μM) and gestodene (Ki = 23.8 ± 3.8 μM). Although both compounds have identical A-rings to cortisol, and undergo reduction, inhibition was non-competitive. 相似文献
7.
Keith A Christian 《Journal of thermal biology》1998,23(6):395-399
The short-horned lizard Phrynosoma douglassi was studied in a montane habitat (elevation of 2290 m) in the Guadalupe Mountains of Texas. The body temperatures (Tb) of active lizards were consistently between 35–36°C (grand mean=35.5°C) in the period from 0900 to 1800 h during the months of May through September. The lizards began their spring activity during April when environmental temperatures were still low. Although Tbs in April were significantly lower than during May through September, on sunny April days the lizards were able to maintain Tbs near 30°C even when air temperatures were as low as 1.5°C. P. douglassi at this site thermoregulated very effectively whenever they were not limited by the physical environment. 相似文献
8.
The reaction of ReH92− with Mo(diglyme)(CO)3 leads to the formation of the mixed metal cluster trianion, ReMo3H4(CO)123−. This species has been characterized analytically, spectroscopically and through X-ray diffraction analysis. A pseudo-tetrahedral arrangement of M(CO)3 fragments is adopted, such that each set of three carbonyl ligands eclipses the adjacent three tetrahedral edges, an apparent result of the location of the hydride ligands on the tetrahedral faces. Variable temperature NMR studies revealed a fluctional process for some of the carbonyl ligands, but not for the hydrides. Crystal data for [Me4N]3[ReMo3H4(CO)12]·THF; space group P21/n, a = 12.157(2), B = 21.480(4), C = 15.964(3) Å, β = 98.26(1)°, Z = 4, R = 0.067 and Rw = 0.076. 相似文献
9.
10.
Complexes of type A4[VO(tart)]2·nH2O, where A = Rb or Cs and tart =d,l-tartrate(4−) (n = 2) or d,d-tartrate(4−) (n = 2 for Rb and n = 3 for Cs), were prepared from an aqueous mixture of V2O5, AOH and H4tart. These complexes were studied by single-crystal X-ray diffraction methods: Rb4[VO(d,l-tart)]2·2H2O, space group P1 with a = 8.156(1),b = 8.246(1),c = 8.719(1)Å, = 66.09(1)°, β = 65.07(1)°, γ = 82.40(1)°,Z = 2, 1917 observed reflections, and final Rw = 0.035; Cs4[VO(d,l-tart)]2·2H2O, space group P21/c with a = 9.350(1),b = 13.728(2),c = 8.479(1)Å, β = 106.77(1)°,Z = 4, 2235 observed reflections, and final Rw = 0.054; Rb4[VO(d,d-tart)]2·2H2O, space group P4122 with a = 8.072(1),c = 32.006(3)Å,Z = 8, 1014 observed reflections and final Rw = 0.038; Cs4[VO(d,d-tart)]2·3H2O, space group P122 with a = 8.184(1),c = 33.680(5)Å,Z = 8, 1310 observed reflections, and final Rw = 0.063. Bulk magnetic susceptibility data (1.5–300 K) for these compounds and A4[VOl,l-tart)]2·nH2O (A = Rb, Cs) were obtained on polycrystalline samples. These data were analyzed in terms of a Van Vleck exchange coupled S = 1/2 model which was modified to include an interdimer exchange parameters Θ. Analysis of the low-temperature (1.5–20 K) susceptibility data gave 2J = +1.30 cm−1 and Θ = −1.86 K for Rb4[VO(d,l-tart)]2·2H2O, 2J = +1.16 cm−1 and Θ = −1.69 K for Cs4[VO(d,l-tart)]2·2H2O, 2J = +1.90 cm−1 and Θ = −0.82 K for Rb4[VO(d,d-tart)]2·2H2O, 2J = +2.04 cm−1 and Θ = −0.80 K for Rb4[VO(l,l-tart)]2·2H2O, 2J = +1.52 cm−1 and Θ = −0.25 K for Cs4[VO(d,d-tart)]2·3H2O, and 2J = +1.64 cm−1 and Θ = −0.31 K for Cs4[VO(l,l-tart)]2·3H2O. These results suggest the magnitudes of intradimer (ferromagnetic and interdimer (antiferromagnetic) exchange interactions are similar in these complexes, as observed for the analogous Na salts. 相似文献
11.
Toshiaki Yonemura Kimi Shibuya Ken-ichi Okamoto Tomoharu Ama Hiroshi Kawaguchi Takaji Yasui 《Inorganica chimica acta》1997,260(2):m1127-128
Cobalt(III) complexes with a thiolate or thioether ligand, t-[Co(mp)(tren)]+ (2), t-[Co(mtp)(tren)]2+ (1Me) and t-[Co(mta)(tren)]2+ (2Me), (mp = 3-mercaptopropionate, MA = 3-(methylthio)propionate and MTA = 2-(methylthio)acetate) have been prepared in aqueous solutions. The crystal structures of 1, 2, 1Me and 2Me were determined by X-ray diffraction methods. The crystal data are as follows, t-[Co(mp)(tren)]ClO4 (1CIO4): monoclinic, P21/n, A = 10.877(8), B = 11.570(4), c = 12.173(7) Å, β = 92.20(5)°, V = 1531(1) Å3, Z = 4 and R = 0.060; t-[Co(ma)(tren)]Cl·3H2O (2Cl·3H2O): monoclinic, P21/n, a = 7.7688(8), B = 27.128(2), C = 7.858(1) Å, β = 100.63(1)°, V = 1627.7(3) Å3, Z = 4 and R = 0.066; (+)465CD-t-[Co(mtp)(tren)](ClO4)2 ((+)465CD-1Me(ClO4)2): orthorhombic, P212121, A = 10.6610(7), B = 11.746(1), C = 15.555(1) Å, V = 1947.9(3) Å3, Z = 4 and R = 0.068; (+)465CD-t-[Co(mta)(tren)](ClO4)2 ((+)465CD-2Me(ClO4)2): orthorhombic, P212121, a = 10.564(1), B = 11.375(1), C = 15.434(2) Å, V = 1854.7(4) Å3, Z = 4 and R = 0.047. All central Co(III) atoms have approximately octahedral geometry, coordinated by four N, one O, and one S atoms. All of the complexes are only isomer, of which the sulfur atom in the didentate-O,S ligands are located at the trans position to the tertiary amine nitrogen atom of tren. 1 and 1Me contain six-membered chelate ring, and 2 and 2Me do five-membered chelate ring in the didentate ligand. The chirality of the asymmetric sulfur donor atom in (+)465CD-1Me is the S configuration and that in (+)465CD-2Me is the R one. The 1H NMR, 13C NMR and electronic absorption spectral behaviors and electrochemical properties of the present complexes are discussed in relation to their stereochemistries. 相似文献
12.
The locomotor activity of the millipede Glyphiulus cavernicolus (Spirostreptida), which occupies the deeper recesses of a cave, was monitored in light-dark (LD) cycles (12h light and 12h darkness), constant darkness (DD), and constant light (LL) conditions. These millipedes live inside the cave and are apparently never exposed to any periodic factors of the environment such as light-dark, temperature, and humidity cycles. The activity of a considerable fraction of these millipedes was found to show circadian rhythm, which entrained to a 12:12 LD cycle with maximum activity during the dark phase of the LD cycle. Under constant darkness (DD), 56.5% of the millipedes (n = 23) showed circadian rhythms, with average free-running period of 25.7h ± 3.3h (mean ± SD, range 22.3h to 35.0h). The remaining 43.5% of the millipedes, however, did not show any clear-cut rhythm. Under DD conditions following an exposure to LD cycles, 66.7% (n = 9) showed faint circadian rhythm, with average free-running period of 24.0h ± 0.8h (mean ± SD, range 22.9h to 25.2h). Under constant light (LL) conditions, only 2 millipedes of 11 showed free-running rhythms, with average period length of 33.3h ± 1.3h. The results suggest that these cave-dwelling millipedes still possess the capacity to measure time and respond to light and dark situations. (Chronobiology International, 17(6), 757-765, 2000) 相似文献
13.
Yukiko Shimizu Carol Yarborough Yoshio Osawa 《The Journal of steroid biochemistry and molecular biology》1993,44(4-6):651-656
In order to better understand the function of aromatase, we carried out kinetic analyses to asses the ability of natural estrogens, estrone (E1), estradiol (E2), 16-OHE1, and estriol (E3), to inhibit aromatization. Human placental microsomes (50 μg protein) were incubated for 5 min at 37°C with [1β-3H]testosterone (1.24 × 103 dpm 3H/ng, 35–150 nM) or [1β-3H,4-14C]androstenedione (3.05 × 103 dpm 3H/ng, 3H/14C = 19.3, 7–65 nM) as substrate in the presence of NADPH, with and without natural estrogens as putative inhibitors. Aromatase activity was assessed by tritium released to water from the 1β-position of the substrates. Natural estrogens showed competitive product inhibition against androgen aromatization. The Ki of E1, E2, 16-OHE1, and E3 for testosterone aromatization was 1.5, 2.2, 95, and 162 μM, respectively, where the Km of aromatase was 61.8 ± 2.0 nM (n = 5) for testosterone. The Ki of E1, E2, 16-OHE1, and E3 for androstenedione aromatization was 10.6, 5.5, 252, and 1182 μM, respectively, where the Km of aromatase was 35.4 ± 4.1 nM (n = 4) for androstenedione. These results show that estrogens inhibit the process of andrigen aromatization and indicate that natural estrogens regulate their own synthesis by the product inhibition mechanism in vivo. Since natural estrogens bind to the active site of human placental aromatase P-450 complex as competitive inhibitors, natural estrogens might be further metabolized by aromatase. This suggests that human placental estrogen 2-hydroxylase activity is catalyzed by the active site of aromatase cytochrome P-450 and also agrees with the fact that the level of catecholestrogens in maternal plasma increases during pregnancy. The relative affinities and concentration of androgens and estrogens would control estrogen and catecholestrogen biosynthesis by aromatase. 相似文献
14.
The thermal and photochemical reactions of CpRe(PPh3)2H4 and CpRe(PPh3)H4 (Cp = η5-C5H5) with PMe3, P(p-tolyl)3, PMe2Ph, DMPE, DPPE, DPPM, CO, 2,6-xylylisocyanide and ethylene have been examined. While CpRe(PPh3)2H2 is thermally inert, it will undergo photochemical substitution of one or two PPh3 ligands. With ethylene, substitution is followed by insertion of the olefin into the C-H bond of benzene, giving ethylbenzene. CpRe(PPh3)H4 undergoes thermal loss of PPh3, which leads to substituted products of the type CpRe(L) H4. Photochemically, reductive elimination of dihydrogen occurs preferentially. The complex trans-CpRe(DMPE)H2 was structurally characterized, crystallizing in the monoclinic space group P21/n (No. 14) with a = 6.249(6), b = 16.671(8), c = 13.867(7) Å, β = 92.11(6)°, V = 1443.7(2.9) Å and Z = 4. The complex trans-CpRe(PMe2Ph)2H2 was structurally characterized, crystallizing in the monoclinic space group P21/n (No. 14) with a = 7.467(3), b = 23.874(14), c = 11.798(6) Å, β = 100.16(4)°, V = 2070.2(3.4) Å3 and Z = 4. 相似文献
15.
Cezary Watala Jacek Golański Henryk Witas Ryszard Gurbiel Krzysztof Gwo?dziński Zygmunt Trojanowski 《The international journal of biochemistry & cell biology》1996,28(12):1393-1403
The erythrocyte deformability, which is related to erythrocyte internal viscosity, was suggested to depend upon the physico-chemical properties of haemoglobin. In the present study we employed ESR spectroscopy in order to explore further the extent to which the in vivo or in vitro glycation and/or glycoxidation might affect haemoglobin structure and conformation. We revealed that under both in vivo and in vitro conditions the attachment of glucose induced a mobilization of thiol groups in the selected domains of haemoglobin molecules (the increased h+1/h0 parameter of maleimide spin label, MSL; 0.377 ± 0.021 in diabetics vs 0.338 ± 0.017 in controls, n = 12, P < 0.0001). The relative rotational correlation time (τc) of two spin labels, TEMPONE and TEMPAMINE, respectively, in erythrocyte insides (5.22 ± 0.42 in diabetics, n = 21 vs 4.79 ± 0.38, n = 16 in controls, P < 0.005) and in the solutions of in vitro glycated haemoglobin, were increased. Neither oxidation nor crosslinking of thiol groups was evidenced in glycated and/or oxidized haemoglobin. In addition, erythrocyte deformability was found to be reduced in type 2 diabetic patients (6.71 ± 1.08, n = 28 vs 7.31 ± 0.96, n = 21, P < 0.015). In conclusion, these observations suggest that: the attachment of glucose to haemoglobin might have decreased the mobility of the Lys-adjacent Cys residues, thus leading to the increased h+1/h0 parameter of MSL. Such structural changes in haemoglobin owing to non-enzymatic glycosylation may contribute to the increased viscosity of haemoglobin solutions (r = 0.497, P < 0.0035) and the enhanced internal viscosity of diabetic erythrocytes (r = 0.503, P < 0.003). We argue that such changes in haemoglobin, and consequently in red blood cells, might contribute to the handicapped oxygen release under tissue hypoxia in the diabetic state. 相似文献
16.
M. D. GreaneyD. L. MarshallB. A. BaileyI. N. Acworth 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,622(2):125-135
An improved high-performance liquid chromatographic (HPLC) method using electrochemical detection (ED) is described capable of routinely measuring the low levels of acetylcholine (ACh) typically found in rat brain microdialysis samples. Microdialysis was performed in the striatum of the urethane anesthetized rat using a 4-mm membrane length, high recovery (40% at 1.0 μl/min; ambient conditions), loop-design probe perfused with an artificial cerebrospinal fluid (aCSF) solution containing physiologically normal calcium levels (1.2 mM). The HPLC method utilizes a polymeric stationary phase to resolve choline (Ch) from ACh. These analytes are then converted to hydrogen peroxide (H2O2) by a solid-phase reactor (containing immobilized choline oxidase and acetylcholinesterase enzymes). The H2O2 is detected amperometrically and quantitated on a platinum (Pt) working electrode (+300 mV; with a unique analytical cell featuring a solid-state palladium reference electrode). Two designs of the Pt working electrode were examined, differing only in the support material used (Kel-F or PEEK). The Kel-F/Pt electrode had a limit of detection (LOD) for both analytes of <30 fmol per 10 μl with a signal-to-noise ratio of 3:1. Striatal microdialysis perfusates were monitored for ACh and Ch over a 0–1000 nM range of neostigmine (NEO) in the CSF perfusion medium. Using the 4-mm probe, basal ACh and Ch levels were detected with a NEO level as low as 10 nM and were found to be 37 ± 3 fmol and 22 ± 1 pmol per 10 μl (mean ± S.E.M., n = 6 replicates) respectively. In similar experiments using 3-mm concentric probes comparable (lower) levels of ACh were found with the 50 and 1000 nM NEO doses (n = 4–21 animals). ACh could not be reliably quantitated when animals were perfused with the 10 nM dose of NEO (n = 4). The PEEK/Pt electrode had an improved LOD of < 20 fmol per 10 μl due to a two- to three-fold decrease in the background noise component. Basal striatal levels of ACh in the absence of NEO approached the LOD and were found to be 15 ± 2 fmol per 10 μl; Ch was 5 ± 1 pmol per 10 μl (n = 2, mean of five basal samples). The analytical system requires very little maintenance; a simple electrochemical electrode cleaning step eliminates the need for routine polishing of the Pt electrode and the mobile phase is stable for up to one week. Both ACh and Ch are resolved in under 7 min making this method highly suitable for analysis of microdialysis samples. 相似文献
17.
利用设置在浙江省淳安县姥山林场和湖北省太子山石龙林场2个试验点的33年生马尾松种源试验林,选取不同纬度的10个代表性种源,研究其在种源间的差异、地理变异模式及对水热因子的响应.结果表明: 马尾松平均年轮δ13C在种源间的差异极显著,高纬度种源的平均年轮δ13C高于低纬度种源.马尾松年轮δ13C呈纬向的地理变异模式,形成了对种源原地环境的适应性.年轮δ13C与种源地年均温(MAT)、1月均温(T1)、年降水量(MAP)、5—9月降水量(P5-9)及≥10 ℃年积温(CT)均呈显著或极显著负相关,与干燥度指数(AI)呈显著正相关.淳安和太子山点马尾松年轮δ13C对种源地干燥度指数的响应函数可分别解释年轮δ13C变化的37.5%和42.5%,种源地AI是年轮δ13C适应性的重要环境限制因子.马尾松稳定碳同位素δ13C的年际变化与生长环境关系密切,湖北太子山试验点处于相对干旱的中西部地区,干燥度指数高,平均年轮δ13C比淳安试验点高1.8%.太子山点和淳安点的马尾松年轮δ13C分别对7月和8月的气温响应敏感,夏季降水量是年轮稳定碳同位素分馏的主要限制因子,而不同种源对未来气候变化的响应敏感性不同. 相似文献
18.
Tamotsu Yamamoto Kazuki Mikata Katsuhiko Miyoshi Hayami Yoneda 《Inorganica chimica acta》1988,150(2):237-244
The crystal structures of Li[Fe(trtda)]·3H2O and Na[Fe(eddda)]·5H2O (trtda = trimethylenediaminetetraacetate and eddda = ethylenediamine-N,N′-diacetate-N,N′-di-3-propionate) have been determined by single crystal X-ray diffraction techniques. The former crystal was monoclinic with the space group P21/n,a = 17.775(3),b = 10.261(1),c = 8.883(2)Å, β = 95.86(4)° and Z = 4. The latter was also monoclinic with the space group P21/n,a = 6.894(2),b = 20.710(6),c = 13.966(3)Å, β = 101.44(2)° and Z = 4. Both complex anions were found to adopt an octahedral six-coordinated structure with all of six ligand atoms of trdta4− or eddda4− coordinated to the Fe(III) ion, unlike the corresponding edta4− complex which is usually seven-coordinate with the seventh coordination site occupied by H2O. Of the three geometrical isomers possible for the eddda complex, the trans(O5) isomer was actually found in the latter crystal. Factors determining the structural types of metal–edta complexes are discussed in detail. 相似文献
19.
P.A. Ruell M.W. Thompson K.M. Hoffman J.R. Brotherhood D.A.B. Richards 《Journal of thermal biology》2007,32(7-8):406-412
Heat shock protein 72 (HSP72) is the most inducible HSP, but is not always increased in lymphocytes following exercise. This field study examined whether lymphocyte HSP72 was increased in hyperthermic (Trec>39.0 °C) male athletes following a 14 km competitive race in cool conditions (ambient temperature 11.2 °C). A comparison was also made between control runners (n=7) and those treated for exertional heat illness (n=9). Lymphocyte HSP72 was not increased in control runners immediately post- compared with pre-race, and there was no difference between both groups of runners. A second study of the race (ambient temperature 14.6 °C) found that lymphocyte HSP72 in control (n=7) and treated (n=9) athletes was higher 2 days post- compared with immediately post-race (p<0.01) and these increases were correlated with post-exercise Trec (p<0.05). 相似文献
20.
Liu J Noble PJ Xiao G Abdelrahman M Dobrzynski H Boyett MR Lei M Noble D 《Progress in biophysics and molecular biology》2008,96(1-3):294-304
Cardiac pacemaking in the sinoatrial (SA) node and atrioventricular (AV) node is generated by an interplay of many ionic currents, one of which is the funny pacemaker current (If). To understand the functional role of If in two different pacemakers, comparative studies of spontaneous activity and expression of the HCN channel in mouse SA node and AV node were performed. The intrinsic cycle length (CL) is 179±2.7 ms (n=5) in SA node and 258±18.7 ms (n=5) in AV node. Blocking of If current by 1 μmol/L ZD7288 increased the CL to 258±18.7 ms (n=5) and 447±92.4 ms (n=5) in SA node and AV node, respectively. However, the major HCN channel, HCN4 expressed at low level in the AV node compared to the SA node. To clarify the discrepancy between the functional importance of If and expression level of HCN4 channel, a SA node cell model was used. Increasing the If conductance resulted in decreasing in the CL in the model, which explains the high pacemaking rate and high expression of HCN channel in the SA node. Resistance to the blocking of If in the SA node might result from compensating effects from other currents (especially voltage sensitive currents) involved in pacemaking. The computer simulation shows that the difference in the intrinsic CL could explain the difference in response to If blocking in these two cardiac nodes. 相似文献