遮荫对彩叶植物矾根夏季适应性表型的影响

以彩叶植物矾根(Heuchera micrantha)‘蜜桃’(‘Georgia Peach’)、‘小珍珠’(‘Petite pearl fairy’)、‘花毯’ (‘Tapestry’)为材料,研究不同遮荫处理对矾根观赏特征、高温半致死温度以及成活率的影响。结果表明,在遮荫条件下,三个矾根品种株高增加、叶面积变大、花序变长、开花推迟,‘蜜桃’和‘小珍珠’花期延长,‘花毯’花期缩短。遮荫引起‘蜜桃’和‘小珍珠’叶绿素含量、类胡萝卜素含量显著上升,花色素苷含量明显下降,叶色由红、紫色向灰绿色转变,叶片彩化度下降;‘花毯’的叶绿素、类胡萝卜素和花青素含量均随遮荫度增加显著上升,其叶色由浅绿转为深绿,叶脉紫红色加重,彩化度提高,观赏性增强。随着遮荫度提高,三个矾根品种的高温半致死温度明显升高,成活率显著上升。相关性分析表明,三个矾根品种的成活率与最高气温、最大光强、气温、光强分别存在极显著负相关关系,与相对湿度以及该品种的高温半致死温度分别存在极显著正相关关系。多元逐步回归分析表明,高光强是引起‘蜜桃’成活率下降的关键因素,‘小珍珠’的成活率主要取决于高温半致死温度,‘花毯’的成活率主要受极端高温的影响。     

Understanding the key characteristics and challenges of pine barrens restoration: insights from a Delphi survey of forest land managers and researchers

Pine barrens are open‐canopy ecological communities once prevalent on sandy soils across the northern Great Lakes Region of the United States and Canada, though fire suppression and plantation forestry have now reduced them to a few isolated areas. Efforts to restore pine barrens are underway on some public lands, but lack of knowledge on the social and ecological issues and challenges that affect these projects impedes fuller progress. As a precursor to designing a public preference survey for pine barrens restoration, we sought input from those with expert knowledge about pine barrens. Using a three‐round modified Delphi survey, forest land managers and researchers identified the key characteristics of pine barrens and important current and future management challenges. Key characteristics were related to fire, landscape structure, plant and animal species, soils, and social themes. Current and future challenges were related to landscape, invasive species, social, economic, climate change, and science themes. Four social issues (education, fire acceptance, fire risk, aesthetics) were rated among the top current challenges but none of them maintained prominence as future challenges. Potential explanations for this shift are that the experts felt these social concerns would be resolved in time or that other issues, such as development pressures and budgets for carrying out restoration, would become greater future challenges. Our approach can be used by managers and researchers to better understand the ecosystems they seek to restore and to communicate with public stakeholders about restoration efforts.     

玉米灵芝菌粮营养成分及加工特性变化研究

玉米作为主要的杂粮谷物,营养价值高,维生素、膳食纤维等含量丰富,可以预防多种亚健康疾病,受到市场追捧。但是玉米粉营养结构不均衡、加工性差,限制其应用。有研究表明,微生物发酵技术可以改善谷物的营养成分、大分子物质结构和加工特性。基于此,利用灵芝固态发酵玉米,得到玉米灵芝菌粮（简称菌粮）,从营养成分、大分子物质结构和加工特性3个方面对其进行评价。结果显示,与未发酵玉米相比,菌粮中碳水化合物、蛋白质含量分别提高了748%、28.00%,且蛋白质的氨基酸评分提高,而脂肪含量降低了52.56%;维生素C、核黄素和烟酸含量均显著提高（P<0.05）,分别提高了56.19%、73.91%和20.27%,且玉米中缺乏的硫胺素在菌粮中被检测到;菌粮中各类淀粉和纤维的含量也发生了显著变化（P<0.05）,淀粉、支链淀粉含量分别降低了11.17%、34.70%,直链淀粉含量提高了26.66%,粗纤维、不溶性膳食纤维含量分别降低了21.07%、21.47%,可溶性膳食纤维含量提高了13.57%;菌粮粉粘度降低,水溶性指数提高,吸水性指数和溶胀力降低;此外,与灵芝子实体相比,菌粮中灵芝三萜和灵芝酸含量均显著提高（P<0.05）,分别为灵芝子实体的1.68和2.07倍。灵芝固态发酵玉米得到的玉米灵芝菌粮,营养结构更加均衡,功能活性提高,具有更高的营养价值;大分子物质结构发生改变,加工特性得到改善,冲调特性更好。研究结果为食用菌发酵改良谷物特性的研究提供了参考和指导。     

基于生物膜干涉技术检测PDL1抗体与PDL1抗原的亲和力

生物膜干涉（biolayer interferometry,BLI）技术可对抗体与抗原的相互作用进行亲和力、动力学的全面分析。在抗体克隆筛选、动力学常数测定中对链霉亲和素（streptavidin,SA）生物传感器的需求量较大,但目前鲜有关于SA传感器重复利用的报道。基于BLI技术、再生SA生物传感器建立一种使用再生后的传感器检测PDL1抗体与PDL1抗原亲和力的方法。通过将生物素化的PDL1抗原偶联至SA生物传感器上,再与单链抗体、双价单链抗体、完整抗体和双特异性抗体这4类PDL1抗体结合,计算抗原抗体的亲和力常数,利用甘氨酸（10 mmol·L^-1,pH 1.7）再生SA传感器,再次进行分子间相互作用力分析。结果显示,重复性相对标准偏差（relative standard deviation,RSD）均值为6.87%,批间重复性RSD为0.82%,稳定性RSD均值为6.13%,说明运用甘氨酸再生后的SA生物传感器测分子间的亲和力数据可靠、重现性好、稳定性高,再生后的传感器可继续用于本样品的实时、无标记的抗原抗体相互作用力分析。BLI技术可节省检测成本,为SA传感器的重复利用提供理论依据。     

半乳糖凝集素‑3对骨关节炎成骨细胞矿化的作用研究

炎症反应以炎症因子为代表,是骨关节炎（osteoarthritis,OA）中软骨下骨发生病变的重要机制。炎症因子半乳糖凝集素?3（galectin?3,Gal?3）会引起软骨下骨OA样变,但机制尚不清楚。利用因膝关节OA行全膝关节置换患者的胫骨平台标本,培养成骨细胞。分别在正常氧和缺氧条件下用Gal?3处理成骨细胞后,检测骨钙素、ERRα和Sirtuin 1的表达情况。同时,给予矿化液培养的成骨细胞以Gal?3处理,28 d后使用茜素红染色检测成骨细胞矿化程度并进行定量分析。结果显示,Gal?3抑制成骨细胞骨钙素的表达,在缺氧条件下诱导ERRα和Sirtuin1的表达,在正常氧条件下Gal?3促进OA成骨细胞的矿化。正常氧条件下,Gal?3可以诱导OA成骨细胞的异常矿化,缺氧条件下Gal?3促进成骨,表明Gal?3在OA成骨细胞的矿化中扮演重要角色。     

人成体心源间充质样细胞表型分析及向心脏谱系诱导分化潜能的研究

目的探讨成人心源性间充质样细胞 (CDMCs)的分子表型及向心脏谱系的分化潜能。方法实验分为:不同培养时间CDMCs (第3、5、7代),并以脐带间充质干细胞 (UCMSCs)为对照。分析各细胞分子表型并向心脏谱系诱导分化。显微镜观察细胞形态;计算生长倍增时间并绘制细胞生长曲线;流式细胞术分析表面标志抗原表达;实时定量PCR和Western blot分别测干细胞多能分子及组织特异性分子mRNA和蛋白表达。结果采用重复测量资料方差分析、单因素方差分析和配对t检验。结果 CDMCs具有UCMSCs形态特征与增殖能力,体外培养1 ~ 7 d,与UCMSCs比较,P3、5、7代CDMCs增殖能力差异无统计学意义 (P> 0.05)。与UCMSCs相比,不同培养时间CDMCs表面标志抗原 (CD90)表达 (冻存前:97.13%±2.00%比59.87%±34.14%、38.83%±11.04%、34.77±14.78%;冻存后:99.83%±0.17%比56.00%±19.47%、47.48±11.88%、41.15±8.68%)降低(P< 0.05)。与UCMSCs相比,不同培养时间CDMCs中Rex1 (0.00±0.00比0.68±0.50、0.29±0.17、0.38±0.50)、Oct3/4 (1.00±0.02比5.28±0.78、3.88±0.95、3.63±0.34)、Nanog(1.00±0.16比7.57±4.69、5.40±3.58、5.34±0.76)以及心脏特异转录因子Nkx2.5 (1.00±0.12比30.60±22.43、19.69±9.65、8.82±4.94)、Gata4 (1.00±0.85比60467±25266、44350±25800、35067±23113)表达均增高,差异有统计学意义 (P均< 0.05)。与诱导前比较,向心肌诱导分化15 d后,不同培养时间CDMCs中cTnT蛋白表达水平 (0.40±0.13比0.98±0.16、0.38±0.18 比0.69±0.15、0.17±0.11比0.70±0.17)增高 (P< 0.05)。结论 CDMCs不仅具备部分干细胞和间充质细胞表型,还具有心脏组织特异性。其具备心脏谱系分化潜能,心肌细胞分化能力可能优于UCMSCs。     

模拟氮沉降对长白山苔原灌草混合群落中植物光合特性的影响

由于草本植物持续上侵长白山灌木苔原,形成了强烈的灌草群落种间竞争。本研究以牛皮杜鹃-小叶章群落（Comm.Rhododendron aureum-Deyeuxia purpurea）为对象,根据小叶章的入侵程度设置4种盖度差异显著的样方（无、轻度、中度、重度入侵）,并设3个施氮水平（自然状态、添加11.8 kgN·hm^-2·a^-1及添加23.6 kgN·hm^-2·a^-1）,进行原位氮沉降模拟实验,监测灌木牛皮杜鹃和草本植物小叶章光合特性的差异和变化趋势,研究小叶章入侵苔原带的内在生理机制。结果显示：（1）小叶章净光合速率大于牛皮杜鹃,小叶章盖度越高、其叶绿素含量越高,而牛皮杜鹃叶绿素含量降低,随着小叶章入侵程度的增加,其净光合速率增强;（2）施氮可以提高牛皮杜鹃和小叶章的叶绿素含量和净光合速率,促进植物生长,但小叶章的增幅更大,从而增强了小叶章的竞争优势;（3）施氮和小叶章入侵具有复合作用,小叶章盖度越大,对其施氮导致小叶章净光合速率与叶绿素含量的增幅越大,而牛皮杜鹃的增幅减小。所以小叶章的成功入侵可能与其具有较高的净光合速率有关,并且施氮有利于提高小叶章的净光合速率,随着氮沉降的继续增加,更有利于小叶章的生长并提高其竞争力。     

Gaussia分泌型萤光素酶的研究进展及其应用

Gaussia分泌型萤光素酶是近年发现的一种来源于海洋桡脚类动物Gaussia princeps的新型分泌型萤光素酶,是目前已知的可自然分泌的最小萤光素酶,因其分子小、灵敏度高、半衰期短和可高效分泌,而成为一种理想的报告基因,广泛应用于体内外研究。我们就Gaussia分泌型萤光素酶的发光原理、荧光特性及其应用等进行简要综述。     

Seasonal changes in entrainment cues for the circadian rhythm of the supratidal amphipod Talorchestia longicornis

The supratidal amphipod Talorchestia longicornis Say has a circadian rhythm in activity, in which it is active on the substrate surface at night and inactive in burrows during the day. The present study determined: (1) the circadian rhythms in individual versus groups of amphipods; (2) the range of temperature cycles that entrain the circadian rhythm; (3) entrainment by high-temperature cycles versus light?:?dark cycles, and (4) seasonal substrate temperature cycles. The circadian rhythm was determined by monitoring temporal changes in surface activity using a video system. Individual and groups of amphipods have similar circadian rhythms. Entrainment occurred only to temperature cycles that included temperatures below 20°C (10–20, 15–20, 17–19, 15–25°C) but not to temperatures above 20°C (20–25, 20–30°C), and required only a 2°C temperature cycle (17–19°C). Diel substrate temperatures were above 20°C in the summer and below 20°C during the winter. Upon simultaneous exposure to a diel high-temperature cycle (20–30°C) and a light?:?dark cycle phased differently, amphipods entrained to the light?:?dark cycle. Past studies found that a temperature cycle below 20°C overrode the light?:?dark cycle for entrainment. The functional significance of this change in entrainment cues may be that while buried during the winter, the activity rhythm remains in phase with the day?:?night cycle by the substrate temperature cycles. During the summer, T. longicornis switches to the light?:?dark cycle for entrainment, perhaps as a mechanism to phase activity precisely to the short summer nights.     

DNA staining in agarose and polyacrylamide gels by methyl green

ABSTRACT

Methyl green (MG) is an inexpensive, nonproprietary, traditional histological stain for cell nuclei. When bound to DNA and upon excitation with orange-red light, it fluoresces brightly in the far red region. We compared MG with ethidium bromide (EtBr), the conventional stain for DNA in gels, and Serva DNA stain G? (SDsG), a proprietary stain marketed as a safer alternative to EtBr for staining of electrophoresed DNA bands in agarose and polyacrylamide gels. DNA-MG fluorescence was recorded and 2.4 μg/ml MG produced crisp images of electrophoresed DNA after incubation for 10 min. Stain solutions were stable and detection limits for faint bands as well as relative densitometric quantitation were equivalent to EtBr. MG, EtBr and SDsG cost 0.0192, 0.024 and 157.5 US cents/test, respectively. MG is an effective stain for visualizing DNA in agarose and polyacrylamide gels. Its major advantages including low cost, comparable quality of staining, storage at room temperature, photo-resistance and low mutagenic profile outweigh its disadvantages such as staining of tracking dye and requirement for a gel documentation system with a red filter.