Toward a theory for diversity gradients: the abundance–adaptation hypothesis

The abundance–adaptation hypothesis argues that taxa with more individuals and faster generation times will have more evolutionary ‘experiments’ allowing expansion into, and diversification within, novel habitats. Thus, as older taxa have produced more individuals over time, and smaller taxa have higher population sizes and faster generation times, the Latitudinal Diversity Gradients (LDGs) of these clades should show shallower slopes. We describe the LDGs for archaea, bacteria, fungi, invertebrates and trees from six North American forests. For three focal groups – bacteria, ants, and trees – older taxa had shallower LDG slopes than the more recent, terminal taxa. Across 12 orders of magnitude of body mass, LDG slopes were steeper in larger taxa. The slopes of LDGs vary systematically with body size and clade age, underscoring the non‐canonical nature of LDGs. The steepest LDG slopes were found for the largest organisms while the smallest, from bacteria to small litter‐soil invertebrates, have shallower‐ to zero‐slope LDGs. If tropical niche conservatism is the failure of clades to adapt to, and diversify in temperate habitats, then the steep LDGs of chordates and plants likely arise from the decreased ability of clades with large individuals to adapt to the multiple challenges of extra‐tropical life.     

Cloning,expression, and characterization of a novel diketoreductase from Acinetobacter baylyi

Reductions of carbonyl groups catalyzed by oxidoreductases are involved in all biological processes and are often a class of important biocatalyst. In this article, we report a novel enzyme designated as diketoreductase （DKR） that was able to reduce two carbonyl groups in a diketo ester to corresponding dihydroxy ester with excellent stereoselectivity. The DKR was cloned from Acinetobacter baylyi by reverse genetic method, heterogeneously expressed in Escherichia coli, and purified to homogeneity by two chromatographic steps. This novel enzyme exhibited dual cofactor specificity, with a preference of NADH over NADPH. The dihydroxy ester product catalyzed by the DKR was only 3R,5S-stereoisomer with both diastereomeric excess and enantiomeric excess values more than 99.5%. In addition, some biochemical properties of the enzyme, such as the optimal pH and temperature, were also characterized. Furthermore, sequence analysis indicated that this new enzyme was homologous to bacterial 3-hydroxyacyl coenzyme-A dehydrogenase. More importantly, based on the unique catalytic activity and excellent stereoselectivity, the DKR could be utilized in the synthesis of valuable chiral drug intermediates, such as Lipitor.     

Complete genome sequence of the bacterium Ketogulonicigenium vulgare Y25

Ketogulonicigenium vulgare is characterized by the efficient production of 2KGA from L-sorbose. Ketogulonicigenium vulgare Y25 is known as a 2-keto-L-gulonic acid-producing strain in the vitamin C industry. Here we report the finished, annotated genome sequence of Ketogulonicigenium vulgare Y25.     

Comparison of mucosal adhesion and species identification of bifidobacteria isolated from healthy and allergic infants

Fifty bifidobacteria strains were isolated from fecal samples of allergic and age matched healthy infants. Allergic infants were found to have an adult type Bifidobacterium flora with high levels of Bifidobacterium adolescentis. Healthy infants had a typical infant Bifidobacterium flora with high levels of Bifidobacterium bifidum. These isolates were tested for their adhesive properties to human intestinal mucus. The adhesion of the fecal bifidobacteria from healthy infants was significantly higher (P<0.0001) than for allergic infants. This suggests a correlation between allergic disease and the composition of the intestinal bifidobacteria flora which has reduced adhesive abilities to the intestinal mucus. Therefore, dietary supplementation of bifidobacteria typical for healthy infants, may be beneficial in the treatment of allergic disorders.     

改性聚二甲基硅氧烷 (iPDMS) 蛋白芯片在肿瘤相关抗原自身抗体筛查中的应用

肿瘤标记的快速筛查是临床早期诊断的难题。利用化学发光蛋白质芯片技术,对低丰度的肿瘤相关抗原的自身抗体进行高灵敏度的筛选,是一种有益的尝试。本研究首先将带烯烃末端的、引发聚合反应的表面引发剂加入到常规聚二甲基硅氧烷材料中,再通过热交联反应固定到聚二甲基硅氧烷的三维结构中,形成改性聚二甲基硅氧烷 (iPDMS)。为了使iPDMS材料具有抗蛋白质非特异性吸附的特性,在活性引发位点处通过表面引发的原子转移自由基聚合反应合成poly(OEGMA) 高分子刷。最后将20种肿瘤相关的抗原利用高通量喷点打印技术打印到芯片的特定区域,并组装成iPDMS芯片的48孔检测微孔板。对临床上常见的8种肿瘤患者血清进行分析,发现VEGFR1和VEGF121自身抗体对常见的8种肿瘤具有检测价值,有望成为肿瘤快速筛查的检测指标。     

不同培养条件对猪卵母细胞IVM、IVF的影响

通过优化猪卵母细胞体外成熟、体外受精和胚胎体外发育体系,以进一步提高体外胚胎的生产效率和质量.研究了激素存在时间、不同激素和不同血清对猪卵母细胞体外成熟的影响;共培养体系、精卵作用时间、去除卵丘细胞的方法对猪体外受精及早期胚胎发育的影响.猪卵母细胞IVM培养48h,前24h内加入PMSG、hCG,后24h将其去除,卵母细胞总成熟率为79.54%;培养液添加15?S或15%NCS,卵母细胞成熟率分别为79.48%和74.81%;PMSG、HCG和E2配合使用后卵母细胞成熟率为81.42%.在IVF前用吹打法获得的卵裂率、桑椹胚率分别为37.89%和8.54%,精卵共孵育6h或8h的卵裂率(40.52%,37.24%)、桑椹胚率(8.42%,7.85%),以及用输卵管上皮细胞共培养所获得的卵裂率(40.84%)、桑椹胚率(9.53%)均显著高于其它各组.     

睫状神经营养因子对大鼠去神经骨骼肌的营养作用

目的：了解睫状神经营养因子（CNTF）对去神经引起的肌肉萎缩的治疗作用。方法：离断SD大鼠一侧坐骨神经,连续给予CNTF20d,观察肌肉湿重、蛋白含量、肌纤维横截面积、收缩性能和残肢程度。结果：①给予0.2mg/kg的CNTF,可使损务侧肌纤维横截面积增加35％,肌肉湿重增加38％,胫前肌总蛋白含量增加24％,腓长肌强直收缩强度提高40％,显著改善肢残程度;②0.2mg/kg的CNTF作用明显强于0.05mg/kg的CNTF;③此目鱼肌（慢肌）比伸趾长肌（快肌）对CNTF更敏感。结论：CNTF能显著改善成年大鼠坐骨神经离断后骨骼肌的萎缩和功能丧失,该效应的强弱与用药剂量和肌肉类型有关。     

早期人胚胎cDNA文库构建及目的基因筛选

收集受精后３、４和５周龄药物流产胚胎,用改良一步法提取总ＲＮＡ,ｏｌｉｇｏ（ｄＴ）纤维素柱纯化ｍＲＮＡ,逆转录合成一链ｃＤＮＡ,完成二链ｃＤＮＡ的合成后,经碱变性电泳检测,合成ｃＤＮＡ的大小为０．４～９．０ｋｂ之间,且主要集中在１．０～２．０ｋｂ。除去多余的接头,收集大于４００ｂｐ的ｃＤＮＡ片段,与载体ｐＳＰＯＲＴ１和和γＺｉｐＬｏｘ连接,分别得到３、４、５周龄人胚胎质粒文加和噬菌体文库。另外,采