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101.
102.
Several cDNA clones encoding subunit XI of photosystem I reaction center (PSI-L) have been isolated from two INE" BORDER="0">gt11 expression libraries based on polyadenylated RNA of spinach seedlings illuminated for 4 and 16 h, respectively. The precursor polypeptide made from these recombinant DNAs in vitro can be efficiently imported into isolated spinach chloroplasts. It is correctly processed to the size of the authentic polypeptide and integrates into the photosystem I assembly. The 834 nucleotide sequence of the longest cDNA insert encodes a precursor polypeptide of 24 kDa (216 residues) and a mature protein of probably 18.8 kDa (169 residues). Hydropathy analysis suggests that the polypeptide contains two transmembrane segments. The protein appears to originate in a single-copy gene in spinach and to be decoded from RNA species of ca. 900 bases. 相似文献
103.
104.
The present study disclosed the cross-reactivity between Bermuda grass pollen (BGP) and other grass pollens using monoclonal antibodies (MAbs) and polyclonal antiserum. MAb 9–13, directed against a group of minor allergens of BGP (Cyn d Bd68K, 48K, 38K) was found to cross-react with extracts of ten other grass pollens. Immunoblotting assays illustrated that MAb 9–13 cross-reacted with multiple components of most of these pollens, and the major cross-reactive components had molecular weights of 29–36 kD. The cross-reactivity between BGP andLol pI, the group I allergen of rye grass pollen, was further evaluated;Lol pI was recognized by MAb 9–13, but not by our MAbs/polyclonal antiserum againstCyn dI, the major allergen of BGP. These results suggest that the epitope recognized by MAb 9–13 is a common (C) epitope shared byLol pI andCyn d Bd68K, 48K, 38K, andCyn dI does not share significant antigenicity withLol pI. In a modified radio-allergosorbent test, IgE antibodies in the serum of BGP-allergic patients reacted mildly with C-epitope-bearing components of both BGP and rye grass pollens, and this binding could be blocked specifically by MAb 9–13. This suggests that in addition to an antigenic cross-reaction, the C epitope can also lead to an allergenic cross-reaction. 相似文献
105.
Age-Dependent Impairment of Mitochondrial Function in Primate Brain 总被引:11,自引:2,他引:9
Allen C. Bowling Elizabeth M. Mutisya Lary C. Walker† Donald L. Price†‡§ Linda C. Cork† M. Hint Beal 《Journal of neurochemistry》1993,60(5):1964-1967
Abstract: It has been hypothesized that some of the functional impairments associated with aging are the result of increasing oxidative damage to mitochondrial DNA that produces defects in oxidative phosphorylation. To test this hypothesis, we examined the enzymes that catalyze oxidative phosphorylation in crude mitochondrial preparations from frontoparietal cortex of 20 rhesus monkeys (5-34 years old). Samples were assayed for complex I, complex II-III, complex IV, complex V, and citrate synthase activities. When enzyme activities were corrected for citrate synthase activities (to account for variable degrees of mitochondrial enrichment), linear regression analysis demonstrated a significant negative correlation of the activities of complex I (p < 0.002) and complex IV (p < 0.03) with age but no significant change in complex II-III or complex V activities. Relative to animals 6.9 ± 0.9 years old (n = 7), the citrate synthase-corrected activity of complex I was reduced by 17% in animals 22.5 ± 0.9 years old (n = 6) (p < 0.05) and by 22% in animals 30.7 ± 0.9 years old (n = 7) (p < 0.01). Similar age-related reductions in the activities of complexes I and IV were obtained when enzyme activities were corrected for complex II-III activity. These findings show an age-associated progressive impairment of mitochondrial complex I and complex IV activities in cerebral cortices of primates. 相似文献
106.
Aurintricarboxylic Acid Protects Hippocampal Neurons from NMDA-and Ischemia-Induced Toxicity In Vivo 总被引:2,自引:1,他引:1
Jill M. Roberts-Lewis Val R. Marcy Yonghua Zhao Jeffry L. Vaught Robert Siman Michael E. Lewis 《Journal of neurochemistry》1993,61(1):378-381
Abstract: The polymeric dye aurintricarboxylic acid (ATA) has been shown to protect various cell types from apoptotic cell death, reportedly through inhibition of a calcium-dependent endonuclease activity. Recent studies have indicated that there may be some commonalities among apoptosis, programmed cell death, and certain other forms of neuronal death. To begin to explore the possibility of common biochemical mechanisms underlying ischemia-or excitotoxin-induced neuronal death and apoptosis in vivo, gerbils or rats subjected to transient global ischemia or NMDA microinjection, respectively, received a simultaneous intracerebral infusion of ATA or vehicle. As a biochemical marker of neuronal death, spectrin proteolysis, which is mediated by activation of calpain I, was measured in hippocampus after 24 h. ATA treatment resulted in a profound reduction of both NMDA-and ischemia-induced spectrin proteolysis, consistent with the possibility of some common mechanism in apoptosis and other forms of neuronal death in vivo. 相似文献
107.
Takayoshi Yoshida Koji Yamamoto Masao Udo 《European journal of applied physiology and occupational physiology》1993,66(2):155-160
The purpose of the present study was to assess the relationship between the rapidity of increased gas exchange (i.e. oxygen uptake
IFIE1.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
) and increased cardiac output (
IFIE2.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
) during the transient phase following the onset of exercise. Five healthy male subjects performed multiple rest-exercise or light exercise (25 W)-exercise transitions on an electrically braked ergometer at exercise intensities of 50, 75, or 100 W for 6 min, respectively. Each transition was performed at least eight times for each load in random order. The
IFIE3.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
was obtained by a breath-by-breath method, and
IFIE4.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
was measured by an impedance method during normal breathing, using an ensemble average. On transitions from rest to exercise,
IFIE5.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
rapidly increased during phase I with time constants of 6.8–7.3 s. The
IFIE6.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
also showed a similar rapid increment with time constants of 6.0–6.8 s with an apparent increase in stroke volume (SV). In this phase I,
IFIE7.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
increased to about 29.7%–34.1% of the steady-state value and
IFIE8.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
increased to about 58.3%–87.0%. Thereafter, some 20 s after the onset of exercise a mono-exponential increase to steady-state occurred both in
IFIE9.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
and
IFIE10.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
with time constants of 26.7–32.3 and 23.7–34.4 s, respectively. The insignificant difference between
IFIE11.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
and
IFIE12.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
time constants in phase I and the abrupt increase in both
IFIE13.gif" alt="
$$\dot Q_c $$
" align="middle" border="0">
and SV at the onset of exercise from rest provided further evidence for a IDDLE" border="0">cardiodynamicIDDLE" border="0"> contribution to
IFIE14.gif" alt="
$$\dot VO_2 $$
" align="middle" border="0">
following the onset of exercise from rest. 相似文献
108.
分离了苏芸金杆菌库斯塔克变种MS07A(Bacillus thuringiensis var.kurstaki MS07A)的质粒,经HindⅢ酶解、凝胶电泳和Southern转移后,用DIGdUTP标记的质粒pES1的EcoR Ⅰ—F片段作探针进行DNA分子杂交,发现5.3、6.6和7kb左右的DNA片段含Cry Ⅰ基因。用Glass milk合并回收这些片段,克隆到pUC18的HindⅢ位点上并转化大肠杆菌JM109。通过菌落原位杂交、重组质粒的限制性消解等分析方法,选出带有Cry Ⅰ基因并能在大肠杆菌中表达其毒蛋白的转化子。初步生物测定结果表明。转化子TM48和TM76对松毛虫和菜青虫有毒杀活性。 相似文献
109.
Seiji Ichida Tetsuyuki Wada Satori Nakazaki Naruhisa Matsuda Hiroyuki Kishino Takafumi Akimoto 《Neurochemical research》1993,18(5):633-638
The characteristics of the specific bindings of [3H](+)PN200-110 (PN: L-type Ca channel antagonist) and [125I]INE" BORDER="0">-conotoxin G VI A (INE" BORDER="0">-CgTX: neuronal L-or N-type Ca channel antagonist) to crude membranes from undifferentiated neuroblastoma x glioma hybrid NG108-15 (NG108-15) cells and differentiated cells induced with dibutyryl cAMP (Bt2cAMP) were examined, because we have already observed that the magnitude and rate of KCL-stimulated45Ca uptake by NG108-15 cells increased progressively during differentiation of the cells induced with Bt2cAMP (unpublished results). The specific binding of [3H](+)PN to these crude membranes was saturable at various concentrations of 2.5–5.0 nM [3H](+)PN. Scatchard analysis showed that the specific binding of [3H](+)PN at equilibrium was significantly increased after differentiation of the NG108-15 cells with Bt2cAMP, but that the apparent Kd value for the specific binding of [3H](+)PN was not influenced by treatment with Bt2cAMP. The specific binding of [3H](+)PN to crude membranes from Bt2cAMP-treated NG108-15 cells was inhibited by a calcium agonist and antagonists, the order of their inhibitory potencies being (+)PN>nitrendipine>(–)PNIDDLE" BORDER="0">Bay K 8644IDDLE" BORDER="0">diltiazem = verapamil. Thus, PNs showed significant stereoselective inhibition of the specific binding of [3H(+)PN. On the other hand, [125I]INE" BORDER="0">-CgTX at concentrations of 0.075–0.6 nM showed scarcely any specific binding to these crude membranes, although at 0.6 nM it showed specific binding to crude membranes from rat brain in the same experimental conditions. These results suggest that the increase in magnitude or rate of KCl-stimulated45Ca uptake during differentiation of NG108-15 cells is partially due to quantitative alteration of voltage-sensitive Ca channels in the cells, and that there are scarcely any specific binding sites for [125I]INE" BORDER="0">-CgTX on Bt2cAMP-treated or untreated NG108-15 cells. 相似文献
110.
Sequence analyses and evolutionary relationships among the energy-coupling proteins Enzyme I and HPr of the bacterial phosphoenolpyruvate: sugar phosphotransferase system. 总被引:8,自引:0,他引:8 下载免费PDF全文