外泌体在白血病中的重要调控作用

目前,白血病复发是患者死亡的主要原因之一。肿瘤细胞和微环境的相互作用,以及隐匿在骨髓中的肿瘤干细胞,促进了白血病的复发和向淋巴组织的转移,因此白血病的治疗、转移和复发问题受到广泛关注。外泌体是由绝大多数细胞分泌的双层脂质膜囊泡,可以调控细胞间的交流和信息传递。在白血病细胞、基质细胞和内皮细胞之间的相互联系中都涉及到外泌体,白血病细胞来源的外泌体存在于白血病患者的血浆中,能把其携带的白血病相关抗原及微小RNA呈递给靶细胞,促进白血病肿瘤细胞的增殖,有助于肿瘤细胞实现免疫逃避,保护白血病细胞抵抗化疗药物导致的细胞毒性作用,促进血管生成及肿瘤细胞的迁移。因此,外泌体与白血病的转移、治疗及预后密切相关,可以用来检测和监测白血病的进展。本文综述了外泌体的来源、形成与分泌机制,以及外泌体在白血病发生前、发展中、预后和免疫治疗中所扮演的重要角色。     

Natural 15N abundance in soils and plants in relation to N cycling in a rangeland in Inner Mongolia

Aims Natural 15 N abundance provides integrated information about nitrogen (N) input, transformation and output, indirectly reflecting N cycling traits within terrestrial ecosystems. However, relationships between natural 15 N abundance and N cycling processes are poorly understood in China. Here, our primary objectives were to (i) examine the effects of grazing at varying levels of intensity on δ 15 N of soils and plants in a semi-arid grassland; (ii) detect the relationships between δ 15 N of soils and four major N cycling processes (i.e. mineralization, nitrification, denitrification and ammonia volatilization); and (iii) determine whether δ 15 N of soils can be used as an indicator of N cycling in this semi-arid grassland.Methods The field experiment was conducted within the long-term (17-year) grazing enclosures in a semi-arid grassland in Inner Mongolia. Five grazing intensities (0.00, 1.33, 2.67, 4.00 and 5.33 sheep ha^-1) were designed. δ 15 N values of topsoils (0–10 cm), surface soils (0–2 cm) and plants were measured in 2006. Differences in δ 15 N of soils and plants between the five grazing intensities were examined. Rates of four soil N cycling processes were measured periodically during the 2005 and 2006 growing seasons. The δ 15 N values of topsoils were linked to the four N cycling processes to investigate their relationships.Important findings The δ 15 N values of topsoils (5.20–5.96‰) were substantially higher than the δ 15 N values of plants (2.51–2.93‰) and surface soils (1.44–2.92‰) regardless of grazing intensities. The 15 N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher δ 15 N values in topsoils than in surface soils. In addition, the δ 15 N values of topsoils were positively correlated with the δ 15 N values of both plants and surface soils. Grazing, especially the high-intensity grazing (5.33 sheep ha^-1), resulted in a significant decrease in δ 15 N of surface soils. However, no statistically significant variations in δ 15 N of topsoils and plants were found in response to grazing. The δ 15 N values of topsoils exhibited significant dependence on the cumulative rates of NH 3 volatilization, net nitrification and denitrification in 2005 but not in 2006.     

Automated High-throughput Behavioral Analyses in Zebrafish Larvae

We have created a novel high-throughput imaging system for the analysis of behavior in 7-day-old zebrafish larvae in multi-lane plates. This system measures spontaneous behaviors and the response to an aversive stimulus, which is shown to the larvae via a PowerPoint presentation. The recorded images are analyzed with an ImageJ macro, which automatically splits the color channels, subtracts the background, and applies a threshold to identify individual larvae placement in the lanes. We can then import the coordinates into an Excel sheet to quantify swim speed, preference for edge or side of the lane, resting behavior, thigmotaxis, distance between larvae, and avoidance behavior. Subtle changes in behavior are easily detected using our system, making it useful for behavioral analyses after exposure to environmental toxicants or pharmaceuticals.     

Optogenetic Perturbation of Neural Activity with Laser Illumination in Semi-intact Drosophila Larvae in Motion

Drosophila larval locomotion is a splendid model system in developmental and physiological neuroscience, by virtue of the genetic accessibility of the underlying neuronal components in the circuits^1-6. Application of optogenetics^7,8 in the larval neural circuit allows us to manipulate neuronal activity in spatially and temporally patterned ways^9-13. Typically, specimens are broadly illuminated with a mercury lamp or LED, so specificity of the target neurons is controlled by binary gene expression systems such as the Gal4-UAS system^14,15. In this work, to improve the spatial resolution to "sub-genetic resolution", we locally illuminated a subset of neurons in the ventral nerve cord using lasers implemented in a conventional confocal microscope. While monitoring the motion of the body wall of the semi-intact larvae, we interactively activated or inhibited neural activity with channelrhodopsin^16,17 or halorhodopsin^18-20, respectively. By spatially and temporally restricted illumination of the neural tissue, we can manipulate the activity of specific neurons in the circuit at a specific phase of behavior. This method is useful for studying the relationship between the activities of a local neural assembly in the ventral nerve cord and the spatiotemporal pattern of motor output.     

培菌白蚁菌圃微生物降解木质纤维素的研究进展

白蚁及其共生微生物协同降解植物细胞壁的机理一直被世界各国科学家所关注。培菌白蚁作为高等白蚁,相比低等食木白蚁具有更多样化的食性,其利用外共生系统“菌圃”,对多种植物材料进行处理。本文综述了菌圃微生物降解木质纤维素的研究进展,以期为深入研究菌圃中木质纤维素降解过程及其机制,并挖掘利用菌圃降解木质纤维素的能力及仿生模拟菌圃开发新的生物质利用系统提供参考。培 菌白蚁在其巢内利用由植物材料修建的多孔海绵状结构——“菌圃”来培养共生真菌鸡枞菌Termitomyces spp.,形成了独特的木质纤维素食物降解和消化策略,使木质纤维素在培菌白蚁及其共生微生物协同作用下被逐步降解。幼年工蚁取食菌圃上的共生真菌菌丝组成的小白球和老年工蚁觅得食物并排出粪便堆积到菌圃上成为上层菌圃。这一过程中,被幼年工蚁取食的共生真菌释放木质素降解酶对包裹在植物多糖外部的木质素屏障进行解聚。菌圃微生物(包括共生真菌)对解聚的木质素基团进一步降解,将多糖长链或主链剪切成短链,使菌圃基质自下而上被逐步降解。最后下层的老熟菌圃被老年工蚁取食,其中肠的内源酶系及后肠微生物将这些短链进一步剪切和利用。因此,蚁巢菌圃及其微生物是培菌白蚁高效转化利用木质纤维素的基础。化学层面的研究表明,菌圃能够实现对植物次生物质解毒和植 物纤维化学结构解构。对共生真菌相关酶系的研究显示可能其在菌圃的植物纤维化学结构和植物次生物质的降解中发挥了作用,但不同属共生真菌间其效率和具体功能不尽相同。而菌圃中的细菌是否发挥了作用和哪些细菌类群发挥了作用等仍有待进一步的研究。相比于低等食木白蚁利用其后肠共生微生物降解木质纤维素,培菌白蚁利用菌圃降解木质纤维素具有非厌氧和能处理多种类型食物两大优势,仿生模拟菌圃降解木质纤维素的机制对林地表面枯枝落叶的资源化利用具有重要意义。     

Phospholipase Dδ is Involved in Wounding Induced Phosphatidic Acid Formation in Arabidopsis

Phosphalipase D (PLD) hydrolyzes phospholipids into phosphatidic acid (PA). PLDα1 and δ are the two most abundant members of the 12 member PLD family in Arabidopsis. PLDα1 has been demonstrated having role in the wounding induced PA signalling. However, whether and how PLDδ is involved in wounding induced PA formation remained unclear. In the present study, the membrane lipids response to wounding was profiled in Wassilewskija (WS) and PLDδ knockout mutant (PLDδ KO) of Arabidopsis. The levels of most lipids, including monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylcholine and phosphatidylglycerol had decreased rapidly within 30min after wounding in the two Arabidopsis genotypes. In contrast, the level of PA increased sharply and significantly 30min after wounding. It continued to increase until peaking at 1h post wounding in WS and 3h post wounding in PLDδ KO, and then decreased. The PA levels were similar in the two genotypes in untreated leaves and in leaves 6h after wounding. However, these levels were lower in PLDδ KO than in WS from 30min to 3h post wounding. The significant difference of PA level between the two genotypes occurred 30min after wounding, when it was about 20% lower in PLDδ KO than in WS. These results show that PLDδ is involved in wounding induced PA formation in Arabidopsis, but its absence induces PA response later and with less intensity than PLDα1.     

Getting to Compliance in Forced Exercise in Rodents: A Critical Standard to Evaluate Exercise Impact in Aging-related Disorders and Disease

There is a major increase in the awareness of the positive impact of exercise on improving several disease states with neurobiological basis; these include improving cognitive function and physical performance. As a result, there is an increase in the number of animal studies employing exercise. It is argued that one intrinsic value of forced exercise is that the investigator has control over the factors that can influence the impact of exercise on behavioral outcomes, notably exercise frequency, duration, and intensity of the exercise regimen. However, compliance in forced exercise regimens may be an issue, particularly if potential confounds of employing foot-shock are to be avoided. It is also important to consider that since most cognitive and locomotor impairments strike in the aged individual, determining impact of exercise on these impairments should consider using aged rodents with a highest possible level of compliance to ensure minimal need for test subjects. Here, the pertinent steps and considerations necessary to achieve nearly 100% compliance to treadmill exercise in an aged rodent model will be presented and discussed. Notwithstanding the particular exercise regimen being employed by the investigator, our protocol should be of use to investigators that are particularly interested in the potential impact of forced exercise on aging-related impairments, including aging-related Parkinsonism and Parkinson’s disease.     

Measurement of Lifespan in Drosophila melanogaster

Aging is a phenomenon that results in steady physiological deterioration in nearly all organisms in which it has been examined, leading to reduced physical performance and increased risk of disease. Individual aging is manifest at the population level as an increase in age-dependent mortality, which is often measured in the laboratory by observing lifespan in large cohorts of age-matched individuals. Experiments that seek to quantify the extent to which genetic or environmental manipulations impact lifespan in simple model organisms have been remarkably successful for understanding the aspects of aging that are conserved across taxa and for inspiring new strategies for extending lifespan and preventing age-associated disease in mammals.The vinegar fly, Drosophila melanogaster, is an attractive model organism for studying the mechanisms of aging due to its relatively short lifespan, convenient husbandry, and facile genetics. However, demographic measures of aging, including age-specific survival and mortality, are extraordinarily susceptible to even minor variations in experimental design and environment, and the maintenance of strict laboratory practices for the duration of aging experiments is required. These considerations, together with the need to practice careful control of genetic background, are essential for generating robust measurements. Indeed, there are many notable controversies surrounding inference from longevity experiments in yeast, worms, flies and mice that have been traced to environmental or genetic artifacts^1-4. In this protocol, we describe a set of procedures that have been optimized over many years of measuring longevity in Drosophila using laboratory vials. We also describe the use of the dLife software, which was developed by our laboratory and is available for download (http://sitemaker.umich.edu/pletcherlab/software). dLife accelerates throughput and promotes good practices by incorporating optimal experimental design, simplifying fly handling and data collection, and standardizing data analysis. We will also discuss the many potential pitfalls in the design, collection, and interpretation of lifespan data, and we provide steps to avoid these dangers.     

昆虫平衡棒的发育及功能

平衡棒(haltere)是双翅目昆虫后翅特化而成的结构,可在飞行中起重要作用。平衡棒基部的感受器可以检测到飞行中的惯性力,向运动神经元提供反馈,迅速地平衡身体并纠正航向。昆虫的平衡棒由成虫盘发育形成,其特化受HOX基因(Ultrabithorax,Ubx)调控。发育成熟的平衡棒由两层上皮细胞组成,末端球状结构内部充满高度空泡化的细胞,基部具有大量感器。平衡棒的运动由独立的肌肉控制,相对于同侧的翅反向移动,翅与平衡棒的协同运动对于昆虫起飞和维持平衡十分重要。近年来,平衡棒的导航原理越来越多地应用于仿生学研究中,基于果蝇平衡棒的结构和功能,研制出多种飞行器的导航设备。本文结合近年来相关领域的研究成果,就平衡棒的发育、形态结构、功能和仿生应用等方面的研究进展进行综述,为深入理解昆虫平衡棒的发育机制和生物学功能提供参考。