Research progress on the effects of soil erosion on vegetation

The relationship between vegetation and soil erosion deserves attention due to its scientific importance and practical applications. A great deal of information is available about the mechanisms and benefits of vegetation in the control of soil erosion, but the effects of soil erosion on vegetation development and succession is poorly documented. Research shows that soil erosion is the most important driving force for the degradation of upland and mountain ecosystems. Soil erosion interferes with the process of plant community development and vegetation succession, commencing with seed formation and impacting throughout the whole growth phase and affecting seed availability, dispersal, germination and establishment, plant community structure and spatial distribution. There have been almost no studies on the effects of soil erosion on seed development and availability, of surface flows on seed movement and redistribution, and their influences on soil seed bank and on vegetation establishment and distribution. However, these effects may be the main cause of low vegetation cover in regions of high soil erosion activity and these issues need to be investigated. Moreover, soil erosion is not only a negative influence on vegetation succession and restoration, but also a driving force of plant adaptation and evolution. Consequently, we need to study the effects of soil erosion on ecological processes and on development and regulation of vegetation succession from the points of view of pedology and vegetation, plant and seed ecology, and to establish an integrated theory and technology for deriving practical solutions to soil erosion problems.     

趋磁细菌及磁小体在肿瘤治疗中的应用

提高抗肿瘤药物的靶向性是肿瘤治疗、降低药物副作用的重要手段。在肿瘤组织内部由于癌细胞的快速增殖致使其形成低氧区,低氧区会对多种肿瘤治疗方案产生耐受。趋磁细菌 (Magnetotactic bacteria, MTB) 是一类能在细胞内产生外包生物膜、纳米尺寸、单磁畴磁铁矿 (Fe3O4) 或硫铁矿 (Fe3S4) 晶体颗粒-磁小体的微生物的统称。在磁场的作用下,趋磁细菌可凭借鞭毛运动至厌氧区。趋磁细菌在动物体内毒性较低且生物相容性良好,其磁小体与人工合成的磁性纳米材料相比优势显著。文中在介绍趋磁细菌及其磁小体生物学特点、理化性能的基础上,综述了趋磁细菌作为载体偶联药物进入肿瘤内部,并通过感受低氧信号定位于肿瘤低氧区,以及趋磁细菌竞争肿瘤细胞铁源的研究进展,总结了磁小体运载化疗药物、抗体、DNA疫苗靶向结合肿瘤的研究进展,分析了趋磁细菌及磁小体肿瘤治疗中面临的问题,并对趋磁细菌和磁小体在肿瘤治疗中的应用进行了展望。     

人源乳酸菌对2型糖尿病小鼠的缓解效果

为考察人源乳酸菌(发酵乳杆菌Lactobacillus fermentum 11、305和植物乳杆菌Lactobacillus plantarum 22、25)对2型糖尿病的缓解效果,对2型糖尿病小鼠连续灌胃菌粉溶液12周.每周记录各组小鼠体重、进食量和血糖.实验结束前进行口服葡萄糖耐量试验和胰岛素抵抗试验.实验结束后...     

荷叶铁线蕨自然居群的遗传多样性研究

荷叶铁线蕨(Adiantumreniformevar. sinense)为我国特有植物,具有重要的经济价值,目前仅分布于重庆的少数地区。近几十年来,由于过度开发,该种的分布范围日益缩小,已处于灭绝的边缘。本研究利用等位酶标记检测了荷叶铁线蕨 6个自然居群共 136个个体的遗传多样性,共检测到了 5个酶系统的 14个位点,获得了 7个多态位点。结果表明:与其他蕨类植物相比,荷叶铁线蕨居群内的遗传多样性水平比较低。平均每位点的有效等位基因数(Ae)为 1. 778,多态位点百分率(P)为 0. 441,期望杂合度(He)为 0. 199,观察杂合度 (Ho)为 0. 235。其居群间的遗传分化也很低,居群间的遗传变异仅占总变异的 1. 49%,而 98. 51%的变异存在于居群内部。采用Hardy Wein berg平衡和固定指数F对荷叶铁线蕨的居群遗传结构进行了分析,结果表明其种群可能是以配子体间异交为主的混合交配体系。导致荷叶铁线蕨濒危的主要原因是生境的破坏以及过度开采所导致的生境片断化使其居群变小、近交率加大、遗传变异趋低,降低了其生存以及进化的潜力。     

茶条槭愈伤组织的再生体系建立及其没食子酸含量的测定

通过愈伤组织诱导途径, 建立了快速高效的茶条槭再生体系。成熟种子在MS+1.0 mg·L-1 6-BA的培养基中萌发, 以茎段作为外植体, 在WPM+0.002-0.01 mg·L-1 TDZ+0.1 mg·L-1 6-BA中培养3周诱导形成愈伤组织, 诱导频率平均为98.0%。愈伤组织转入WPM+0.01 mg·L-1 TDZ+0.1 mg·L-1 6-BA培养基中得到再生芽, 分化频率为42.0%,平均每块愈伤产生再生芽10个左右。转到WPM+0.3 mg·L-1 IBA的培养基上的再生芽均可生根并长成完整植株, 小苗移栽成活率达到89.0%。实验还建立了愈伤组织中没食子酸的提取和HPLC检测方法。对深绿色愈伤组织连续培养2个继代后, 没食子酸含量达到2.8%。     

近自然化改造对马尾松和杉木人工林生物量及其分配的影响

近自然化改造作为森林新增碳汇的最有希望的选择之一,将如何通过改变林分结构影响林分生物量和生产力进而影响林分固碳能力和潜力目前尚不清楚,因此,了解近自然化改造对人工林生物量及其分配的影响,对人工林生态系统碳管理具有重要意义。以马尾松近自然化改造林(P(CN))、马尾松未改造纯林(P(CK))、杉木近自然改造林(C(CN))和杉木未改造纯林(C(CK))4种人工林为研究对象,采用样方调查和生物量实测的方法,分析4种林分生物量差异,旨在揭示近自然化改造对马尾松和杉木人工林生物量及其分配的影响。结果表明:马尾松杉木人工林近自然化改造通过调整林分结构显著提升马尾松和杉木人工林生物量和生产力,8a后马尾松和杉木林分生物量分别增加46.71%和37.24%。乔木层生物量在林分生物量总量中占主导地位(95.48%-98.82%),并对林分生态系统总生物量变化起决定性作用。林分生物量和生产力的增加主要因为近自然化改造改变了林分群落结构,进而提高了乔木层生产力。研究结果表明,合理的经营措施不仅可以改善林分结构,提升林分生产力,并可为增强植被固碳能力创造有利条件。     

Generation of virus‐resistant potato plants by RNA genome targeting

CRISPR/Cas systems provide bacteria and archaea with molecular immunity against invading phages and foreign plasmids. The class 2 type VI CRISPR/Cas effector Cas13a is an RNA‐targeting CRISPR effector that provides protection against RNA phages. Here we report the repurposing of CRISPR/Cas13a to protect potato plants from a eukaryotic virus, Potato virus Y (PVY). Transgenic potato lines expressing Cas13a/sgRNA (small guide RNA) constructs showed suppressed PVY accumulation and disease symptoms. The levels of viral resistance correlated with the expression levels of the Cas13a/sgRNA construct in the plants. Our data further demonstrate that appropriately designed sgRNAs can specifically interfere with multiple PVY strains, while having no effect on unrelated viruses such as PVA or Potato virus S. Our findings provide a novel and highly efficient strategy for engineering crops with resistances to viral diseases.     

珍珠黄杨叶片的蛋白质提取方法探讨

蛋白质样品制备是双向电泳的核心.为了找到一种适合提取珍珠黄杨叶片蛋白质的方法,本文以该树种扦插苗的叶片为材料,用TCA-丙酮沉淀法、Tris-饱和酚法和2-D Clean-up Kit提取蛋白质,并进行双向凝胶电泳,采用银染法进行检测.结果表明,TCA-丙酮沉淀法得到的样品图谱背景模糊、拖尾;Tris-饱和酚法得到的样品图谱清晰,蛋白点饱满,无纵向或横向拖尾,但有蛋白点丢失;2-D Clean-Up Kit提取的蛋白质样品得到了较好双向电泳图谱.     

Phenotypic responses of hatchlings to constant versus fluctuating incubation temperatures in the multi-banded krait, Bungarus multicintus (Elapidae)

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.