The association between serum selenium and gestational diabetes mellitus: A systematic review and meta-analysis

BackgroundResults of the studies about association between serum selenium concentration and gestational hyperglycemia are inconsistent. Some studies have demonstrated that women with gestational diabetes mellitus (GDM) have lower Se concentrations while contrary results are reported in other studies.AimThe aim of this study is to compare the serum Se concentration in women with GDM and normoglycemic pregnant women via a systematic review and meta-analysis.MethodsA computerized literature search on four databases (PubMed, Cochrane register of control trials, Scopus and Google scholar) was performed from inception through August 2013. Necessary data were extracted and random effects model was used to conduct the meta-analysis.ResultsSix observational studies (containing 147 women with GDM and 360 normoglycemic pregnant women) were found, which had compared serum Se concentration in women suffering from GDM with normal pregnant ones. Our meta-analysis revealed that serum Se concentration was lower in women with GDM compared to normoglycemic pregnant women (Hedges = −1.34; 95% CI: −2.33 to −0.36; P < 0.01). Stratified meta-analysis demonstrated that concentration of Se in the sera of women with GDM was lower than normal pregnant women both in second and third trimesters, but the result was not significant in second trimester (second trimester: Hedges = −0.68; 95% CI: −1.60−0.25; P = 0.15, third trimester: Hedges = −2.81; 95% CI: −5.21 to −0.42; P < 0.05). It was also demonstrated that serum Se status was lower in pregnant women with impaired glucose tolerance (IGT) compared to normoglycemic pregnant women (Hedges = −0.85; 95% CI: −1.18 to −0.52).ConclusionThe available evidences suggest that serum Se concentration is significantly lower in pregnant women with gestational hyperglycemia compared to normal pregnant women.     

Crystal structure of quinone‐dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes. A versatile dehydrogenase oxidizing alcohols and carbohydrates

The quinone‐dependent alcohol dehydrogenase (PQQ‐ADH, E.C. 1.1.5.2) from the Gram‐negative bacterium Pseudogluconobacter saccharoketogenes IFO 14464 oxidizes primary alcohols (e.g. ethanol, butanol), secondary alcohols (monosaccharides), as well as aldehydes, polysaccharides, and cyclodextrins. The recombinant protein, expressed in Pichia pastoris, was crystallized, and three‐dimensional (3D) structures of the native form, with PQQ and a Ca²⁺ ion, and of the enzyme in complex with a Zn²⁺ ion and a bound substrate mimic were determined at 1.72 Å and 1.84 Å resolution, respectively. PQQ‐ADH displays an eight‐bladed β‐propeller fold, characteristic of Type I quinone‐dependent methanol dehydrogenases. However, three of the four ligands of the Ca²⁺ ion differ from those of related dehydrogenases and they come from different parts of the polypeptide chain. These differences result in a more open, easily accessible active site, which explains why PQQ‐ADH can oxidize a broad range of substrates. The bound substrate mimic suggests Asp333 as the catalytic base. Remarkably, no vicinal disulfide bridge is present near the PQQ, which in other PQQ‐dependent alcohol dehydrogenases has been proposed to be necessary for electron transfer. Instead an associated cytochrome c can approach the PQQ for direct electron transfer.     

枸杞L-半乳糖酸内酯脱氢酶基因的克隆及表达分析

以青海枸杞(Lycium barbarum L.)为模板,采用RT-PCR和RACE技术,克隆枸杞L-半乳糖酸-1,4-内酯脱氢酶(GLDH)基因序列,命名为LbGLDH。LbGLDH基因全长为2 114bp,包含一个开放读码框1 767bp(编码588个氨基酸)、5′末端序列57bp、3′末端序列290bp。LbGLDH基因核苷酸序列与番茄、马铃薯、烟草GLDH基因具有88%~90%的一致性。LbGLDH编码氨基酸序列包含GLDH蛋白酶具备的FAD-binding-4和ALO结构域。qRT-PCR分析结果显示,在枸杞不同组织中LbGLDH基因的表达、抗坏血酸含量和GLDH活性变化趋势相同,表现为在枸杞的花和果实中表达量最高,成熟叶中表达量最少。推测LbGLDH基因表达促进枸杞果实中抗环血酸含量的积累。     

根际低氧胁迫对网纹甜瓜幼苗植株碳水化合物含量的影响

以耐低氧性明显不同的2个网纹甜瓜品种为试材,研究了低氧胁迫下植株体内碳水化合物含量的变化特征,探讨植株体内碳水化合物含量与低氧耐性之间的关系。结果表明,低氧胁迫下网纹甜瓜根系淀粉含量下降,而茎部和叶片中有淀粉积累的现象,且在耐低氧性强的‘东方星光’叶片中淀粉积累更明显;低氧胁迫下网纹甜瓜体内可溶性糖、蔗糖、果糖含量增加,且在茎部和叶片中增加幅度较大,并以耐低氧性强的‘东方星光’中增加更明显;低氧胁迫下网纹甜瓜根系葡萄糖含量降低且低于通气对照,茎部和叶片中葡萄糖含量先增加后降低,在处理8d后低于通气对照。研究发现,网纹甜瓜体内碳水化合物含量与植株的耐低氧性密切相关;耐低氧性强的品种体内可溶性糖、蔗糖、果糖含量在低氧胁迫下比耐低氧性弱的品种更高,增幅更大;体内较高的可溶性糖、蔗糖和果糖含量是植株对低氧胁迫的一种适应性反应。     

辣椒雄性不育系葡萄糖-6-磷酸脱氢酶基因的克隆及表达分析

为了深入研究辣椒雄性不育与能量代谢之间的关系,该研究以辣椒近缘物种番茄的葡萄糖-6-磷酸脱氢酶基因(G6PDH)同源序列为基础,采用电子克隆的方法克隆出辣椒CaG6PDH基因。利用荧光定量PCR技术,对辣椒雄性不育系9704A与其保持系9704B花蕾发育的不同阶段,以及保持系9704B不同组织(茎、叶、花、果皮、胎座、种子)中CaG6PDH基因进行表达分析。结果表明:两系中获得的CaG6PDH基因的编码序列一致,全长1 533bp,编码510个氨基酸残基;辣椒CaG6PDH基因在保持系不同组织中表达量存在差异,胎座中表达量最高,茎中表达量最低;辣椒CaG6PDH基因的表达量在花蕾发育的不同阶段雄性不育系均高于保持系,此种差异在小孢子发育的单核期与成熟期尤为明显,这种差异可能使雄性不育系能量代谢供应出现异常,从而影响小孢子的正常发育而导致雄性败育。     

Long-chain Acylcarnitines Reduce Lung Function by Inhibiting Pulmonary Surfactant

The role of mitochondrial energy metabolism in maintaining lung function is not understood. We previously observed reduced lung function in mice lacking the fatty acid oxidation enzyme long-chain acyl-CoA dehydrogenase (LCAD). Here, we demonstrate that long-chain acylcarnitines, a class of lipids secreted by mitochondria when metabolism is inhibited, accumulate at the air-fluid interface in LCAD^−/− lungs. Acylcarnitine accumulation is exacerbated by stress such as influenza infection or by dietary supplementation with l-carnitine. Long-chain acylcarnitines co-localize with pulmonary surfactant, a unique film of phospholipids and proteins that reduces surface tension and prevents alveolar collapse during breathing. In vitro, the long-chain species palmitoylcarnitine directly inhibits the surface adsorption of pulmonary surfactant as well as its ability to reduce surface tension. Treatment of LCAD^−/− mice with mildronate, a drug that inhibits carnitine synthesis, eliminates acylcarnitines and improves lung function. Finally, acylcarnitines are detectable in normal human lavage fluid. Thus, long-chain acylcarnitines may represent a risk factor for lung injury in humans with dysfunctional fatty acid oxidation.