Solution NMR views of dynamical ordering of biomacromolecules

Background

To understand the mechanisms related to the ‘dynamical ordering’ of macromolecules and biological systems, it is crucial to monitor, in detail, molecular interactions and their dynamics across multiple timescales. Solution nuclear magnetic resonance (NMR) spectroscopy is an ideal tool that can investigate biophysical events at the atomic level, in near-physiological buffer solutions, or even inside cells.

Phoenixin-14 stimulates differentiation of 3T3-L1 preadipocytes via cAMP/Epac-dependent mechanism

Phoenixin-14 (PNX) is a newly discovered peptide produced by proteolytic cleavage of the small integral membrane protein 20 (Smim20). Previous studies showed that PNX is involved in controlling reproduction, pain, anxiety and memory. Furthermore, in humans, PNX positively correlates with BMI suggesting a potential role of PNX in controlling fat accumulation in obesity. Since the influence of PNX on adipose tissue formation has not been so far demonstrated, we investigated the effects of PNX on proliferation and differentiation of preadipocytes using 3T3-L1 and rat primary preadipocytes. We detected Smim20 and Gpr173 mRNA in 3T3-L1 preadipocytes as well as in rat primary preadipocytes. Furthermore, we found that PNX peptide is produced and secreted from 3T3-L1 and rat primary adipocytes. PNX increased 3T3-L1 preadipocytes proliferation and viability. PNX stimulated the expression of adipogenic genes (Pparγ, C/ebpβ and Fabp4) in 3T3-L1 adipocytes. 3T3-L1 preadipocytes differentiated in the presence of PNX had increased lipid content. Stimulation of cell proliferation and differentiation by PNX was also confirmed in rat preadipocytes. PNX failed to induce AKT phosphorylation, however, PNX increased cAMP levels in 3T3-L1 cells. Suppression of Epac signalling attenuated PNX-induced Pparγ expression without affecting cell proliferation. Our data show that PNX stimulates differentiation of 3T3-L1 and rat primary preadipocytes into mature adipocytes via cAMP/Epac-dependent pathway. In conclusion our data shows that phoenixin promotes white adipogenesis, thereby may be involved in controlling body mass regulation.     

肠出血性大肠埃希菌O157:H7噬菌体FEC14和FEC19特性及污染牛肉杀菌潜在应用探究

【背景】肠出血性大肠埃希菌O157:H7是重要的食源性致病菌之一,并且其耐药性越来越严重,寻找裂解性强噬菌体用于防治大肠埃希菌感染具有广阔的应用前景。【目的】从环境中分离鉴定能特异裂解大肠埃希菌O157:H7的噬菌体,通过对生物学特性及裂解细菌功效的探究,为其在食品安全防控中提供理论依据和研究基础。【方法】通过双层平板法分离并纯化噬菌体,透射电镜观察噬菌体形态,测定最佳感染复数、一步生长曲线、pH稳定性、温度稳定性,对噬菌体进行全基因组测序及噬菌体裂解细菌功效。【结果】2株大肠埃希菌O157:H7噬菌体FEC14和FEC19的头部皆呈二十面体立体对称,FEC14头部直径约80nm,尾丝呈星形,FEC19头部直径约58 nm,尾丝呈针形;噬菌体FEC14的最佳感染复数为0.001,潜伏期为15 min,裂解期为65 min,平均暴发量为156 PFU/cell,FEC19的最佳感染复数为0.1,潜伏期为10 min,裂解期为80 min,平均暴发量为800 PFU/cell;噬菌体FEC14能在60℃、pH 4.0-11.0条件下存活,噬菌体FEC19在70℃、pH5.0-9.0条件下存...     

O139霍乱弧菌检测方法的研究─诊断血清的制备

本文以Ｏ１３９死菌免疫健康家兔,经吸收去除非特异性凝集素制成的特异性诊断血清,专供诊断霍乱弧菌Ｏ１３９之用。采用玻片凝集试验对５株Ｏ１３９菌株及１２６株肠道菌进行验证,在敏感性和特异性方面均获得满意的结果。     

MGMT 甲基化影响替莫唑胺对胶质母细胞瘤疗效的研究

目的:探讨MGMT甲基化如何影响替莫唑胺对胶质母细胞瘤的治疗效果。方法:选取41个胶质母细胞瘤患者(根据相同替莫唑胺化疗方案治疗下临床结局的不同分为两组)的肿瘤组织,采用甲基化特异性聚合酶链反应分析胶质瘤组织中MGMT基因启动子区过甲基化状态,同时采用免疫组织化学法分析胶质瘤组织中MGMT蛋白表达情况。结果:临床结局不佳组中,以MGMT蛋白表达阳性的肿瘤为主(72.2%),而在结局相对良好组中,MGMT蛋白表达的阳性率仅为39.1%;在MGMT蛋白表达阳性的22例胶质母细胞瘤组织中,7例MGMT启动子甲基化,阳性率为31.8%,在MGMGT蛋白表达阴性的19例中,14例MGMT启动子甲基化,阳性率为73.7%(P<0.05)。结论:MGMT基因启动子区的甲基化状态与MGMT蛋白的表达相关。MGMT基因启动子过甲基化,MGMT蛋白表达较低;MGMT基因启动子去甲基化,MGMT蛋白表达较高。MGMT启动子过甲基化通过抑制MGMT基因的表达而增加替莫唑胺的疗效。     

氮沉降和施生物质炭对毛竹林土壤N2O通量的影响

本研究于2019年7月-2020年7月在浙江省杭州市典型毛竹林布置野外控制实验,采用静态箱-气相色谱法测定毛竹林土壤N2O通量,分析生物质炭(10 t·hm-2)、氮沉降(60 kg N·hm-2·a-1)、生物质炭+氮沉降混合处理对土壤N2O通量的影响,并探讨了土壤N2O通量与环境因子的关系.结果 表明:与对照相比,...     

Effect of feeding sun-dried seaweed (Ascophyllum nodosum) on fecal shedding of Escherichia coli O157:H7 by feedlot cattle and on growth performance of lambs

Thirty-two steers orally inoculated with a four-strain mixture (10¹⁰ CFU) of nalidixic acid-resistant Escherichia coli O157:H7 had sun-dried Ascophyllum nodosum seaweed (Tasco-14™) added to their barley-based diet (860 g/kg barley grain and 90 g/kg whole crop barley silage, dry matter basis) to assess its effectiveness in reducing fecal shedding of the pathogen. Steers were housed in four groups of eight and received Tasco-14™ in the diet, in place of barley, at levels (as fed) of 10 g/kg for 14 days (T1-14), 20 g/kg for 7 days (T2-7), 20 g/kg for 14 days (T2-14), or not at all (i.e., control, CON). The dietary treatments commenced 7 days after E. coli O157:H7 inoculation and fecal shedding patterns were examined over 14 weeks. Water, water–trough interface, feed and fecal pat samples were also collected weekly and cultured for E. coli O157:H7. Detection of the pathogen in fecal samples was less frequent (P<0.05) in T1-14 (99/168) and T2-7 (84/168) versus CON (135/168) and T2-14 (115/168), and the concentrations of E. coli O157:H7 recovered in feces from T1-14 and T2-7 steers were lower (P<0.005) than from CON or T2-14 steers. Rates of decline in shedding of E. coli O157:H7 were similar among treatments, but final numbers of E. coli O157:H7 were lower (P<0.05) in T1-14 and T2-7 as compared to T2-14 and CON. Fecal volatile fatty acid concentrations and pH were similar among treatments, suggesting no fecal alterations that were antagonistic to survival. E. coli O157:H7 was present in 1 (from T2-7) of 56 cattle drinking water samples, 2 of 56 (T1-14, CON) feed samples and 32 of 56 fecal pats. A second experiment investigated effects of the dietary treatment on growth performance of non-inoculated sheep. Tasco-14™ was administered to 40 individually fed Canadian Arcott lambs beginning at day 56 of a 105-day finishing period. The lambs received Tasco-14™ at 0 g/kg (control, CON), at 10 g/kg for 14 days (T1-14), 20 g/kg for 14 days (T2-14), 10 g/kg for 28 days (T1-28) or at 20 g/kg for 7 days (T2-7) as a top-dress on their pelleted, barley grain-based diet (n = 8). E. coli O157:H7 was not isolated from fecal samples collected at 4-week intervals, but generic E. coli populations were lower (P<0.05) in T1-28 lambs than in other treatments. Average daily gain, feed intake, feed efficiency and carcass traits did not differ among treatments. Our challenge study supports past studies showing that Tasco-14™ decreases shedding of E. coli O157:H7 by cattle. The lamb study shows that this additive did not directly affect feed intake or animal growth.