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The potential contribution of maternal age to tetrahydrocannabinol's (THC) in utero effects in rats was studied. Pregnant animals were intubated with 25, 10 or 0 mg/kg of THC from gestation day six to parturition. Animals in the 10 and 0 mg/kg groups were pair fed to those given the 25 mg/kg dose. Each series of doses was administered to females three, four or six months of age. THC lowered maternal weight gain and weights of offspring at birth and at 21 days of age, but did not affect litter size, spontaneous alternation or passive avoidance learning in offspring. Increased maternal age was associated with smaller litter size and lower birth weight and weight at 21 days, but did not interact significantly with THC. 相似文献
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We have isolated a gene, AAT1, encoding an aspartate aminotransferase (AspAT) from a Saccharomyces cerevisiae genomic library. AAT1 encodes a 451 amino acid protein with a predicted molecular weight of 51,687, which is likely to be the yeast mitochondrial AspAT. Sequence comparison of this yeast AspAT with AspATs from other organisms shows a high degree of homology in regions previously shown to be important for catalysis. However, the yeast mitochondrial AspAT contains four obvious insertions with respect to all other known AspATs, suggesting that the AAT1-encoded protein represents a distinct AspAT. 相似文献
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The N-1-Naphthylphthalamic Acid-Binding Protein Is an Integral Membrane Protein 总被引:6,自引:3,他引:3 下载免费PDF全文
N-1-Naphthylphthalmic acid (NPA)-binding protein is a plasmalemma (PM) protein involved in the control of cellular auxin efflux. We re-evaluated the spatial relationship of this protein with the PM of zucchini (Cucurbita pepo L.) hypocotyls. First, Triton X-114 partitioning indicated that the NPA-binding protein was more hydrophobic than most PM proteins. Second, the NPA-binding activity was found to be resistant to proteolytic digestion in membranes. Maximum concentrations of binding sites for NPA were virtually identical in untreated and proteinase K-treated PMs: 19.2 and 20.6 pmol [3H]NPA bound/mg protein, respectively. The insensitivity of the NPA-binding protein was not due to its presence inside tightly sealed vesicles or due to lack of protease activity in the conditions tested. This protein could be made sensitive to proteolytic degradation upon solubilization by 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate in the presence of sodium molybdate. Proteinase K treatment decreased the concentration of binding sites to 0.84 pmol [3H]NPA bound/mg protein from 9.2 for untreated, solubilized PM. Third, this activity could not be solubilized by chaotropic agents or sodium carbonate treatment of intact PM. This study indicates that the NPA-binding protein may be an integral membrane protein and contradicts previously reported findings that suggested that this protein was peripheral to the PM. 相似文献
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Adenylosuccinate synthetase: site of action of hydantocidin, a microbial phytotoxin. 总被引:6,自引:1,他引:5 下载免费PDF全文
D L Siehl M V Subramanian E W Walters S F Lee R J Anderson A G Toschi 《Plant physiology》1996,110(3):753-758
The site of action of hydantocidin was probed using Arabidopsis thaliana plants growing on agar plates. Herbicidal effects were reversed when the agar medium was supplemented with AMP, but not IMP or GMP, suggesting that hydantocidin blocked the two-step conversion of IMP to AMP in the de novo purine biosynthesis pathway. Hydantocidin itself did not inhibit adenylosuccinate synthetase or adenylosuccinate lyase isolated from Zea mays. However, a phosphorylated derivative of hydantocidin, N-acetyl-5'-phosphohydantocidin, was a potent inhibitor of the synthetase but not of the lyase. These results identify the site of action of hydantocidin and establish adenylosuccinate synthetase as an herbicide target of commercial potential. 相似文献
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The crystal structure of a dipeptide L -leucyl–L -leucine (C12H24N2O3) has been determined. The crystals are monoclinic, space group P21, with a = 5.434(4) Å, b = 15.712(7) Å, c = 11.275(2) Å, β = 100.41(1)°, and Z = 2. The crystals contain one molecule of dimethyl sulfoxide (DMSO) as solvent of crystallization for each dipeptide molecule. The structure has been solved by direct methods and refined to a final R index of 0.059 for 920 reflections (sinθ/λ ? 0.60 Å?1) with I ? 2σ (I). The trans peptide unit shows substantial degree of non-planarity (Δω = 14°). The peptide backbone adopts an extended conformation with torsion angles of ψ1 = 138(1)°, ω1 = 166(1)°, ?2 = ? 149.3(7)°, ψ21 = 164.2(7)°, and ψ22 = ? 15(1)°. For the first leucyl residue, the side-chain conformation is specified by the torsion angles 1χ1 = 176.7(7)°, 1χ21 = 62(1)°, 1χ22 = ? 177.4(8)°; the second leucyl residue adopts a Sterically unfavorable conformation with 2χ1 = 61(1)°, 2χ21 = 97(1)°, and 2χ22 = ?151(1)°. The packing involves head-to-tail interaction of peptide molecules and segregation of polar and nonpolar regions. The DMSO molecule is strongly hydrogen bonded to the terminal NH group. © 1994 John Wiley & Sons, Inc. 相似文献
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Biological Trace Element Research - We report the final part of our “on-line yield” pilot program in this article. This last part deals with aspects of accuracy and precision of the... 相似文献