The SGLT2 inhibitor dapagliflozin promotes systemic FFA mobilization,enhances hepatic β-oxidation,and induces ketosis

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to increase ketone bodies in patients with type 2 diabetes; however, the underlying mechanisms have not been fully elucidated. Here we examined the effect of the SGLT2 inhibitor dapagliflozin (1 mg/kg/day, formulated in a water, PEG400, ethanol, propylene glycol solution, 4 weeks) on lipid metabolism in obese Zucker rats. Fasting FFA metabolism was assessed in the anesthetized state using a [9,10-³H(N)]-palmitic acid tracer by estimating rates of plasma FFA appearance (R_a), whole-body FFA oxidation (R_ox), and nonoxidative disposal (R_st). In the liver, clearance (K_β-ox) and flux (R_β-ox) of FFA into β-oxidation were estimated using [9,10-³H]-(R)-bromopalmitate/[U-¹⁴C]palmitate tracers. As expected, dapagliflozin induced glycosuria and a robust antidiabetic effect; treatment reduced fasting plasma glucose and insulin, lowered glycated hemoglobin, and increased pancreatic insulin content compared with vehicle controls. Dapagliflozin also increased plasma FFA, R_a, R_ox, and R_st with enhanced channeling toward oxidation versus storage. In the liver, there was also enhanced channeling of FFA to β-oxidation, with increased K_β-ox, R_β-ox and tissue acetyl-CoA, compared with controls. Finally, dapagliflozin increased hepatic HMG-CoA and plasma β-hydroxybutyrate, consistent with a specific enhancement of ketogenesis. Since ketogenesis has not been directly measured, we cannot exclude an additional contribution of impaired ketone body clearance to the ketosis. In conclusion, this study provides evidence that the dapagliflozin-induced increase in plasma ketone bodies is driven by the combined action of FFA mobilization from adipose tissue and diversion of hepatic FFA toward β-oxidation.     

FD香葱生产中的危害分析与关键环节控制

将HACCCP体系引入FD(真空冷冻干燥)香葱生产过程中,经危害分析找出关键控制点,通过过程控制提高产品合格率,降低危害发生的风险,形成一套行之有效的食品安全管理体系.     

短芽胞杆菌对香蕉采后炭疽病的防治

【背景】香蕉炭疽病是香蕉贮运过程中常见的病害,危害严重。【目的】评价短芽胞杆菌菌株FJAT-17214和FJAT-10657的抗菌活性,并进行菌株鉴定。【方法】采用抑菌圈法和菌丝生长速率法对菌株FJAT-17214和FJAT-10657的拮抗活性进行测定,采用香蕉果实回接法测定这2株菌对香蕉采后炭疽病病原菌的抗菌活性;根据菌株FJAT-17214和FJAT-10657的形态观察、特异性鉴定和16SrRNA基因序列进行种属鉴定。【结果】菌株FJAT-17214和FJAT-10657发酵上清液对香蕉炭疽病病原菌菌丝生长具有抑制作用,抑菌圈直径分别达到15.30 mm和15.35 mm。随着菌株培养时间的延长,菌株FJAT-17214和FJAT-10657发酵上清液抑菌效果也逐渐增强,培养72 h时,抑菌圈直径分别增大至17.37 mm和20.96 mm。不同添加量发酵上清液对香蕉炭疽病病原菌生长均具有一定的抑制作用。当培养基中添加50 m L菌株FJAT-17214和FJAT-10657的发酵上清液时,其抑菌率可分别达到83.90%和85.84%。接种炭疽病病原菌4 d后,防治效果分别为67.88%和54.55%,处理后香蕉果皮β-1,3-葡聚糖酶活性均明显高于对照。对菌株FJAT-17214和FJAT-10657进行形态学观察、特异性鉴定和16SrRNA基因种属鉴定的结果表明,这2株菌分别被鉴定为短短芽胞杆菌(Brevibacillus brevis)和人参土壤短芽胞杆菌(Brevibacillus panacihumi)。【结论】菌株FJAT-17214和FJAT-10657对香蕉采后炭疽病具有较好的防治效果,可作为采后病害防治微生物的材料。     

用RAPD标记研究蚱属五个种间的亲缘关系

用RAPD技术对蚱属5种蚱基因组DNA的多态性进行研究。在事先优化的反应条件下用12个随机引物扩增, 共得到84条清晰稳定的多态性片段,片段长度为200～2 000 bp。统计这些片段,根据扩增片段的共享度计算出相对遗传距离指数,然后用UPGMA和NJ聚类方法对其进行分析,构建系统树,确定了它们相互间的亲缘关系。     

Cooperative strand invasion of supercoiled plasmid DNA by mixed linear PNA and PNA-peptide chimeras

Peptide nucleic acid (PNA) is a DNA analog with broad biotechnical applications, and possibly also treatment applications. Its suggested uses include that of a specific anchor sequence for biologically active peptides to plasmids in a sequence-specific manner. Such complexes, referred to as Bioplex, have already been used to enhance non-viral gene transfer in vitro. To investigate how hybridization of PNAs to supercoiled plasmids would be affected by the binding of multiple PNA-peptides to the same strand of DNA, we have developed a method of quantifying the specific binding of PNA using a PNA labeled with a derivative of the fluorophore thiazole orange (TO). Cooperative effects were found at a distance of up to three bases. With a peptide present at the end of one of the PNAs, steric hindrance occurred, reducing the increase in binding rate when the distance between the two sites was less than two bases. In addition, we found increased binding kinetics when two PNAs binding to overlapping sites on opposite DNA strands were used, without the use of chemically modified bases in the PNAs.     

中国中生代早期甲虫化石修订(英文)

提要本文重新描述华南和新疆上三叠统和下侏罗统20枚甲虫模式标本,共识别出Cupedidae科3属5种,Elateridae科4属4种,Permosynidae科4属5种,Schizocoleidae科2属3种,未定科3属3种。将Notocupoides fasciatus Ponomarenko,1966归入Notocupes,建立一新种Notocupes lini sp.nov.;基于Ademosynoides chinaticus Lin,1992建立一新属Toksunius gen.nov.,形成一新组合Toksunius chinaticus(Lin,1922)comb.nov.。     

Introduction to Special Issue on ‘Statistical Methods for Cancer Immunotherapy’

Statistics in Biosciences -     

Exogenous maltose enhances Zebrafish immunity to levofloxacin-resistant Vibrio alginolyticus

Understanding the interplay between bacterial fitness, antibiotic resistance, host immunity and host metabolism could guide treatment and improve immunity against antibiotic-resistant pathogens. The acquisition of levofloxacin (Lev) resistance affects the fitness of Vibrio alginolyticus in vitro and in vivo. Lev-resistant (Lev-R) V. alginolyticus exhibits slow growth, reduced pathogenicity and greater resistance to killing by the host, Danio rerio (zebrafish), than Lev-sensitive (Lev-S) V. alginolyticus, suggesting that Lev-R V. alginolyticus triggers a weaker innate immune response in D. rerio than Lev-S V. alginolyticus. Differences were detected in the metabolome of D. rerio infected with Lev-S or Lev-R V. alginolyticus. Maltose, a crucial metabolite, is significantly downregulated in D. rerio infected with Lev-R V. alginolyticus, and exogenous maltose enhances the immune response of D. rerio to Lev-R V. alginolyticus, leading to better clearance of the infection. Furthermore, we demonstrate that exogenous maltose stimulates the host production of lysozyme and its binding to Lev-R V. alginolyticus, which depends on bacterial membrane potential. We suggest that exogenous exposure to crucial metabolites could be an effective strategy for treating and/or managing infections with antibiotic-resistant bacteria.     

Lipase-catalyzed alcoholysis of triglycerides for the preparation of 2-monoglycerides

Rhizopus arrhizus lipase immobilized on celite was used to prepare isomerically pure 2-monoglycerides by alcoholysis of triglycerides in organic media. Reaction parameters such as choice of solvent, choice of alcohol, and alcohol concentration were studied. When 12.5 mM tripalmitin was used as substrate, methyl-tert-butyl ether was the best solvent for alcoholysis at water activity 0.11. Ethanol gave the highest yield (97%) at an optimal ethanol concentration of 200–300 mM. At higher alcohol concentrations, the enzyme activity was substantially lowered. The enzyme preparation showed high stability in repeated-batch reactions.