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991.
Aqueous calcium (Ca) concentrations are declining in softwater lakes of the Canadian Shield largely because of decades of
acid deposition and afforestation following timber harvesting. Populations of pelagic cladoceran taxa with high Ca requirements,
especially Daphnia spp., are declining in response to reduced aqueous Ca availability. However, the Ca content, and thus the requirements of
littoral cladoceran taxa are unknown; therefore, the potential vulnerability of this major component of lake ecosystems to
ongoing regional Ca decline remains uncertain. Here, we identify the body Ca concentration of nine littoral cladoceran taxa
collected from three lakes in the Muskoka-Haliburton region of Ontario, Canada. Ca content differed among taxonomic groups,
ranging from 3.6 mg g−1 for Acroperus harpae to 23.2 mg g−1 for Disparalona spp. Perhaps surprisingly, some littoral microcrustacean taxa have Ca burdens comparable to the Ca-rich daphniids. Therefore,
there may be differential responses to ongoing lake water Ca declines among taxa within littoral communities as has been observed
among open-water taxa, with potential ecological repercussions for near-shore food webs. 相似文献
992.
目的:评估关节镜下膝关节前交叉韧带(ACL)与后交叉韧带(PCL)同时重建的技术和临床效果。方法:自2003年6月~2009年10月,27例病人(28膝)经MRI检查及关节镜检查证实ACL和PCL均断裂,其中9膝伴内侧副韧带损伤(MCL),8膝伴后外侧角损伤(PLC),5膝伴内侧半月板破裂,4膝伴外侧半月板损伤。27例患者于伤后3~10周在关节镜下行膝关节前、后交叉韧带联合重建。结果:本组术后早期均未发生严重并发症。术后随访12~88个月,平均(42.67±3.34)个月,Lysholm膝关节功能评分为78~93分,平均(86.67±5.21)分。国际膝关节文件编制委员会(IKDC)综合评定由术前显著异常(D级)28膝,改进为随访时正常(A级)9膝、接近正常(B级)16膝、异常(C级)3膝。结论:关节镜下膝关节前交叉韧带(ACL)与后交叉韧带(PCL)同时重建创伤小、手术操作精细,术后膝关节功能恢复满意。 相似文献
993.
目的:检测葛根素灌胃对冷激诱导的高血压小鼠的血压血脂及肾脏结构的影响。方法:小鼠分为正常对照组、冷激对照组、冷激葛根素饲喂组(2,5,10ms/kg bw3组)(n=12)。以寒冷刺激(4±2℃)建立小鼠高血压模型,每天定时灌胃葛根素治疗,对照组给予聚乙烯吡咯烷酮溶液。连续饲喂18d.检测各组小鼠血压、血脂含量,石蜡切片观察肾脏结构。结果:冷激对照组小鼠血压显著高于正常对照组(P〈0.01),葛根素饲喂组血压显著低于冷激对照组(P〈0.05)。冷激对照组TG含量显著高于正常对照组(P〈0.01),而冷激饲喂组TG含量明显降低(P〈0.05);冷激饲喂组TC含量与冷激对照组相比有所降低但无统计学意义;2mg/kg BW葛根素组LDL-C显著低于冷激对照组(P〈0.01),各组间HDL-C含量比较无统计学意义,但葛根素饲喂组HDL-C/LDL-C值显著高于冷激对照组。冷激对照组肾小管上皮细胞水肿,内腔极度缩小,肾小球明显胀大,肾小囊腔显著变窄,葛根素饲喂组肾小管水肿基本消失,内腔明显增大,肾小球、肾小囊结构趋于正常。结论:葛根素灌服具有降血压、降血脂、改善病变肾脏结构的作用。 相似文献
994.
目的:探讨四逆散对疲劳大鼠学习记忆及脑内GABA_B1受体的影响。方法:应用游泳训练和睡眠剥夺方法复制疲劳动物模型,运用Y-迷宫检测各组大鼠的学习记忆能力,采用免疫组化方法检测大鼠脑内GABA_B1受体阳性反应物的变化。结果:模型组与正常组相比,大鼠Y-迷宫正确反应率明显下降,错误反应率明显升高,大鼠脑内GABA_B1的阳性反应物数目明显增多;中药治疗组与模型组相比,正确反应率明显升高,错误反应次数明显下降,脑内GABA_B1受体的阳性反应物数目明显减少。结论:四逆散对疲劳大鼠学习记忆能力的下降具有改善作用。 相似文献
995.
996.
A cDNA encoding chymotrypsin inhibitor was constructed from the cellular RNA isolated from the venom glands of Naja atra (Taiwan cobra). The resultant amino acid sequence showed that the mature protein is comprised of 57 amino acid residues with six cysteine residues. Cloned protein was expressed and isolated from the inclusion bodies of E. coli and refolded into a functional protein in vitro. Deleting the first three residues at its N-terminus caused a moderate increase in the inhibitory constant (K(i)) against chymotrypsin. The genomic DNA encoding the chymotrypsin inhibitor was amplified by PCR. The gene shares virtually an identical structural organization with the beta-bungarotoxin B1 chain (a snake Kunitz/BPTI neurotoxic homolog) gene. Moreover, the overall sequence identity of the N. atra chymotrypsin inhibitor and beta-bungarotoxin B1 chain genes was up to 83%. These findings strongly suggest that snake Kunitz/BPTI protease inhibitors and neurotoxic homologs may have originated from a common ancestor. 相似文献
997.
998.
Guangwen Lu Jie Zhang Yan Li Zhixin Li Na Zhang Xiang Xu Tingting Wang Zhenhong Guan George F. Gao Jinghua Yan 《蛋白质与细胞》2011,2(1):64
Human NUDT16 (hNUDT16) is a decapping enzyme initially identified as the human homolog to the Xenopus laevis X29. As a metalloenzyme, hNUDT16 relies on divalent cations for its cap-hydrolysis activity to remove m7GDP and m227GDP from RNAs. Metal also determines substrate specificity of the enzyme. So far, only U8 small nucleolar RNA (snoRNA) has been identified as the substrate of hNUDT16 in the presence of Mg2+. Here we demonstrate that besides U8, hNUDT16 can also actively cleave the m7GDP cap from mRNAs in the presence of Mg2+ or Mn2+. We further show that hNUDT16 does not preferentially recognize U8 or mRNA substrates by our cross-inhibition and quantitative decapping assays. In addition, our mutagenesis analysis identifies several key residues involved in hydrolysis and confirms the key role of the REXXEE motif in catalysis. Finally an investigation into the subcellular localization of hNUDT16 revealed its abundance in both cytoplasm and nucleus. These findings extend the substrate spectrum of hNUDT16 beyond snoRNAs to also include mRNA, demonstrating the pleiotropic decapping activity of hNUDT16. 相似文献
999.
固醇调节元件结合蛋白与脂质代谢 总被引:3,自引:0,他引:3
固醇调节元件结合蛋白(sterol regulatory element-binding proteins,SREBPs)是脊椎动物细胞脂质稳态的转录调节物,可直接激活多个参与胆固醇、脂肪酸、甘油三酯、磷脂合成和摄取,以及辅助因子NADPH等基因的表达,从而调控胆固醇及脂肪酸等脂类的代谢过程。本文综述了SREBPs转运和活化的过程,以及调节细胞脂质稳态功能的分子机制,并探讨了其在脂代谢紊乱相关疾病发生中的重要作用。 相似文献
1000.
Microarray and genetic analysis reveals that csa‐miR159b plays a critical role in abscisic acid‐mediated heat tolerance in grafted cucumber plants 下载免费PDF全文
Hao Li Yu Wang Ze Wang Xie Guo Feng Wang Xiao‐Jian Xia Jie Zhou Kai Shi Jing‐Quan Yu Yan‐Hong Zhou 《Plant, cell & environment》2016,39(8):1790-1804