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11.
Left-handed Z-DNA 总被引:7,自引:0,他引:7
M Leng 《Biochimica et biophysica acta》1985,825(4):339-344
Since the Watson-Crick proposal of right-handed B-DNA, numerous studies have been devoted to the conformation of DNA. Both natural DNAs of heterogeneous sequences and synthetic DNAs are capable of adopting more than one conformation. The specific conformation a DNA adopts appears to depend mainly on its base sequence and its environmental conditions. For a given DNA, changes in environmental conditions can induce conformational transitions which occur according to cooperative or non-cooperative processes (for general reviews see Ref. 1a, b). Despite many results, molecular biologists did not put much emphasis on the polymorphism of DNA. The discovery of the intraconversion in helical sense between the right-handed B and left-handed Z conformers of DNA has brought a new interest in the polymorphism of DNA. It is now proposed that this polymorphism has important functions in biological reactions. A recent review, 'The Chemistry and Biology of Left-handed Z-DNA', by Rich et al. has just been published. We here report some of the results published in 1984 on Z-DNA. 相似文献
12.
Junjie Yu Yunfei Xing Chaoliang Hu Zhijie Huang Qinyi Qiu Chao Wang Kaiyang Xia Zhenyi Wang Shengqiang Bai Xinbing Zhao Lidong Chen Tiejun Zhu 《Liver Transplantation》2020,10(25)
Half‐Heusler (HH) compounds have shown great potential in waste heat recovery. Among them, p‐type NbFeSb and n‐type ZrNiSn based alloys have exhibited the best thermoelectric (TE) performance. However, TE devices based on NbFeSb‐based HH compounds are rarely studied. In this work, bulk volumes of p‐type (Nb0.8Ta0.2)0.8Ti0.2FeSb and n‐type Hf0.5Zr0.5NiSn0.98Sb0.02 compounds are successfully prepared with good phase purity, compositional homogeneity, and matchable TE performance. The peak zTs are higher than 1.0 at 973 K for Hf0.5Zr0.5NiSn0.98Sb0.02 and at 1200 K for (Nb0.8Ta0.2)0.8Ti0.2FeSb. Based on an optimal design by a full‐parameters 3D finite element model, a single stage TE module with 8 n‐p HH couples is assembled. A high conversion efficiency of 8.3% and high power density of 2.11 W cm?2 are obtained when hot and cold side temperatures are 997 and 342 K, respectively. Compared to the previous TE module assembled by the same materials, the conversion efficiency is enhanced by 33%, while the power density is almost the same. Given the excellent mechanical robustness and thermal stability, matchable thermal expansion coefficient and TE properties of NbFeSb and ZrNiSn based HH alloys, this work demonstrates their great promise for power generation with both high conversion efficiency and high power density. 相似文献
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Bin Liang Yu Zheng Juan Wang Wenbo Zhang Ying Fu Wenbin Kai Yandan Xu Bing Yuan Qian Li Ping Leng 《The Plant journal : for cell and molecular biology》2020,102(6):1220-1233
β‐Glucosidases (BG) are present in many plant tissues. Among these, abscisic acid (ABA) β‐glucosidases are thought to take part in the adjustment of cellular ABA levels, however the role of ABA‐BG in fruits is still unclear. In this study, through RNA‐seq analysis of persimmon fruit, 10 full‐length DkBG genes were isolated and were all found to be expressed. In particular, DkBG1 was highly expressed in persimmon fruits with a maximum expression 95 days after full bloom (DAFD). We verified that, in vitro, DkBG1 protein can hydrolyze ABA‐glucose ester (ABA‐GE) to release free ABA. Compared with wild‐type, tomato plants that overexpressed DkBG1 significantly upregulated the expression of ABA receptor PYL3/7 genes and showed typical symptoms of ABA hypersensitivity in fruits. DkBG1 overexpression (DkBG1‐OE) accelerated fruit ripening onset by 3–4 days by increasing ABA levels at the pre‐breaker stage and induced early ethylene release compared with wild‐type fruits. DkBG1‐OE altered the expression of ripening regulator NON‐RIPENING (NOR) and its target genes; this in turn altered fruit quality traits such as coloration. Our results demonstrated that DkBG1 plays an important role in fruit ripening and quality by adjusting ABA levels via hydrolysis of ABA‐GE. 相似文献
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A Single Nucleotide Polymorphism of Chicken Acetyl-CoA Carboxylase A Gene Associated with Fatness Traits 总被引:1,自引:0,他引:1
Acetyl-CoA carboxylase α (ACCα) is a major rate-limiting enzyme in the biogenesis of long-chain fatty acids. It can catalyze the carboxylation of acetyl-CoA to form malonyl-CoA that plays a key role in the regulation of fatty acid metabolism. The objective of the present study was to investigate the associations of ACCα gene polymorphisms with chicken growth and body composition traits. The Northeast Agricultural University broiler lines divergently selected for abdominal fat content and the Northeast Agricultural University F2 Resource Population were used in the current study. Body weight and body composition traits were measured in the aforementioned two populations. A synonymous mutation was detected in the exon 19 region of ACCα gene, then polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was developed to genotype all the individuals derived from the aforementioned populations. Association analysis revealed that the polymorphism was associated with abdominal fat weight and percentage of abdominal fat in the two populations. The results suggested that ACCα gene could be a candidate locus or linked to a major gene that affects abdominal fat content in the chicken. 相似文献
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18.
Guangxia Cui Huijie Leng Ke Wang Jianwei Wang Sainan Zhu Jing Jia Xing Chen Weiguang Zhang Lihua Qin Wenpei Bai 《PloS one》2013,8(12)
This study aims to evaluate the effects of Remifemin (isopropanolic extract of Cimicifuga Racemosa) on postmenopausal osteoporosis. 120 female Sprague-Dawley rats were randomly assigned to four groups: sham surgery with vehicle, ovariectomy with vehicle, ovariectomy with estradiol valerate, or ovariectomy with Remifemin. Daily oral administrations of the vehicle, estradiol valerate, or Remifemin began 2 weeks after surgery and lasted to 4, 8, or 12 weeks. Ten rats in each group were sacrificed at each timestep with assessment of bone mineral density, trabecular bone structure, and biomechanical parameters of the femur and lumbar vertebra. Bone turnover markers were evaluated 12 weeks after surgery. Both drugs prevented bone density loss in the distal end of the femur and preserved the trabecular bone structure in both the lumbar vertebra and distal end of the femur following ovariectomy. Both drugs protected bone stiffness at the tested regions and reduced bone reabsorption in ovariectomized rats. The preventive effects of Remifemin against bone-loss can rival those of estradiol valerate if treatment duration is adequately extended. In conclusion, Remifemin may demonstrate equivalent effects to estradiol valerate in terms of preventing postmenopausal osteoporosis. 相似文献
19.
Jindong Shi Juan Xie Zebao He Yunwen Hu Yanchao He Qihui Huang Beizheng Leng Wei He Ying Sheng Fangming Li Yuanlin Song Chunxue Bai Yong Gu Zhijun Jie 《PloS one》2013,8(10)
Background
The world’s first reported patient infected with avian influenza H7N9 was treated at the Fifth People’s Hospital of Shanghai. Shortly thereafter, several other cases emerged in the local area. Here, we describe the detailed epidemiological and clinical data of 6 cases of avian influenza H7N9.Methods and Findings
We analyzed the epidemiologic and clinical data from clustered patients infected with H7N9 in the Minhang District of Shanghai during a 2-week period. Of the 6 patients, 2 were from a single family. In addition, 3 patients had a history of contact with poultry; however, all 6 patients lived in the proximity of 2 food markets where the H7N9 virus was detected in chickens and pigeons. The main symptoms were fever, cough, and hemoptysis. At onset, a decreased lymphocyte count and elevated creatine kinase, lactate dehydrogenase, procalcitonin, and C-reactive protein levels were observed. As the disease progressed, most patients developed dyspnea and hypoxemia. Imaging studies revealed lung consolidation and multiple ground-glass opacities in the early stage, rapidly extending bilaterally. All patients were treated with oseltamivir tablets beginning on days 3–8 after onset. The main complications were as follows: acute respiratory distress syndrome (ARDS; 83.3%), secondary bacterial infection (66.7%), pleural effusion (50%), left ventricular failure (33.3%), neuropsychiatric symptoms (33.3%), and rhabdomyolysis (16.7%). Of the 6 patients, 4 died of ARDS, with 2 patients recovering from the infection.Conclusions
An outbreak of H7N9 infection occurred in the Minhang District of Shanghai that easily progressed to acute respiratory distress syndrome. Two cases showed family aggregation, which led us to identify the H7N9 virus and indicated that human transmission may be involved in the spread of this infection. 相似文献20.
Vasopressin neurons generate distinctive phasic patterned spike activity in response to elevated extracellular osmotic pressure. These spikes are generated in the cell body and are conducted down the axon to the axonal terminals where they trigger Ca2+ entry and subsequent exocytosis of hormone-containing vesicles and secretion of vasopressin. This mechanism is highly non-linear, subject to both frequency facilitation and fatigue, such that the rate of secretion depends on both the rate and patterning of the spike activity. Here we used computational modelling to investigate this relationship and how it shapes the overall response of the neuronal population. We generated a concise single compartment model of the secretion mechanism, fitted to experimentally observed profiles of facilitation and fatigue, and based on representations of the hypothesised underlying mechanisms. These mechanisms include spike broadening, Ca2+ channel inactivation, a Ca2+ sensitive K+ current, and releasable and reserve pools of vesicles. We coupled the secretion model to an existing integrate-and-fire based spiking model in order to study the secretion response to increasing synaptic input, and compared phasic and non-phasic spiking models to assess the functional value of the phasic spiking pattern. The secretory response of individual phasic cells is very non-linear, but the response of a heterogeneous population of phasic cells shows a much more linear response to increasing input, matching the linear response we observe experimentally, though in this respect, phasic cells have no apparent advantage over non-phasic cells. Another challenge for the cells is maintaining this linear response during chronic stimulation, and we show that the activity-dependent fatigue mechanism has a potentially useful function in helping to maintain secretion despite depletion of stores. Without this mechanism, secretion in response to a steady stimulus declines as the stored content declines. 相似文献