NADPH Oxidase-generated Hydrogen Peroxide Induces DNA Damage in Mutant FLT3-expressing Leukemia Cells

Internal tandem duplication of the FMS-like tyrosine kinase (FLT3-ITD) receptor is present in 20% of acute myeloid leukemia (AML) patients and it has been associated with an aggressive AML phenotype. FLT3-ITD expressing cell lines have been shown to generate increased levels of reactive oxygen species (ROS) and DNA double strand breaks (DSBs). However, the molecular basis of how FLT3-ITD-driven ROS leads to the aggressive form of AML is not clearly understood. Our group has previously reported that inhibition of FLT3-ITD signaling results in post-translational down-regulation of p22^phox, a small membrane-bound subunit of the NADPH oxidase (NOX) complex. Here we demonstrated that 32D cells, a myeloblast-like cell line transfected with FLT3-ITD, have a higher protein level of p22^phox and p22^phox-interacting NOX isoforms than 32D cells transfected with the wild type FLT3 receptor (FLT3-WT). The inhibition of NOX proteins, p22^phox, and NOX protein knockdowns caused a reduction in ROS, as measured with a hydrogen peroxide (H₂O₂)-specific dye, peroxy orange 1 (PO1), and nuclear H₂O₂, as measured with nuclear peroxy emerald 1 (NucPE1). These reductions in the level of H₂O₂ following the NOX knockdowns were accompanied by a decrease in the number of DNA DSBs. We showed that 32D cells that express FLT3-ITD have a higher level of both oxidized DNA and DNA DSBs than their wild type counterparts. We also observed that NOX4 and p22^phox localize to the nuclear membrane in MV4–11 cells expressing FLT3-ITD. Taken together these data indicate that NOX and p22^phox mediate the ROS production from FLT3-ITD that signal to the nucleus causing genomic instability.     

山西霍山灌丛空隙草本植物物种多样性与更新

采用物种重要值和物种多样性指数,分析了山西霍山灌丛空隙内主要草本组成及其多样性随灌丛空隙面积梯度的变化规律。结果表明:在自然状况下形成的10 m2的灌丛空隙最多,占51.2%。灌丛空隙内草本植物的重要值高于灌丛下草本,且以10~20 m2的空隙为最高。主要草本可分为3类:(1)对灌丛空隙更新反应不明显的草本,(2)对灌丛空隙有正更新反应的草本,(3)对灌丛空隙有负更新反应的草本。灌丛空隙内的物种丰富度、多样性指数和均匀度指数均高于灌丛下,而生态优势度均小于灌丛下,呈现"单峰型"的变化趋势,且在10~20 m2达到峰值。因此,适宜大小的灌丛空隙是森林生态系统草本层植物多样性维持的重要途径。     

云居山栓皮栎群落特征及多样性研究

栓皮栎群落是我国暖温带和亚热带落叶阔叶林的重要森林群落类型之一,也是赣北珍稀森林群落之一,在森林演替和植物资源利用中占有重要的地位。通过对江西云居山栓皮栎(Quercus variabilis)群落进行实地调查,采用区系分析、生活型谱分析、物种多样性和双向聚类等方法对其群落特征进行了研究,发现云居山自然保护区栓皮栎群落结构简单,层次明显,多样性程度不高。物种调查及区系研究结果显示,云居山栓皮栎群落维管束植物共计43科56属70种,植物区系主要以泛热带、东亚及北美间断、北温带分布为主,表现出从温带区系向热带区系过渡的特征;生活型谱以高位芽植物为主(占70%),其他生活型相对较少,反映出中亚热带森林以高位芽植物为主的特点。群落物种丰富度、多样性指数均为乔木层小于灌木层和草本层,均匀度指数分析表明,乔木层为聚集分布、灌木层和草本层为均匀分布。双向聚类分析表明,调查的5个样地均为栓皮栎群落,以乔木层物种多度可将5个样地分为3类,组成群落的24个主要物种可分为10类。     

Importance of feature selection in decision-tree and artificial-neural-network ecological applications. Alburnus alburnus alborella: A practical example

Recent advances in computing technology have increased interest in applying data mining to ecology. Machine learning is one of the methods used in most of these data mining applications. As is well known, approximately 80% of the resources in most data mining applications are devoted to cleaning and preprocessing the data. However, there are few studies on preprocessing the ecological data used as the input in these data mining systems. In this study, we use four different feature selection methods (χ², Information Gain, Gain Ratio, and Symmetrical Uncertainty) and evaluate their effectiveness in preprocessing the input data to be used for inducing artificial neural networks (ANNs) and decision trees (DTs). The presence/absence of fish is the data item used to illustrate our models. Feature selection is fundamental in order to increase the performances of the models obtained. Accuracy of classification improves when a small set of optimally selected features is used. DTs and ANNs are very useful tools when applied to modeling presence/absence of Alburnus alburnus alborella. ANNs generally performed better than DT models.     

Joint control by rodent herbivory and nutrient availability of plant diversity in a salt marsh–salty steppe transition zone

Questions: Do current models that predict shifting effects of herbivores on plant diversity with varying nutrient conditions apply to stressful systems like salt marshes? Do herbivores affect different components of the diversity as nutrient availability varies? Location: Salt marsh–salty steppe transition zone at the SW Atlantic Mar Chiquita coastal lagoon (37°44′52″S, 57°26′6″W), Argentina. Methods: We experimentally evaluated the separate and interactive effect of nutrients and rodent (Cavia aperea) herbivory, using exclosures and applying fertilizer (mostly nitrogen), following a factorial design in 50 cm × 50 cm plots. Results: We found a negative effect of herbivory on diversity in the resource‐poor scenario (due to a reduction in species richness), but a positive effect when nutrients were added, by reducing the abundance of the dominant plant (and hence increasing evenness). Conclusions: Our experimental results contribute to the limited factorial evidence evaluating the role of nutrients and herbivory on the diversity of terrestrial plant communities, even in highly stressful environments like salt marsh–salty steppe transition zones. Our results also support the model that predicts negative effects of herbivores on plant diversity in low‐nutrient conditions and positive effects in nutrient‐enriched scenarios, and also support the mechanism assumed to act in these situations.     

Factors influencing the seed source and sink functions of a floodplain nature reserve in the Netherlands

Question: How do species traits and abiotic factors influence the extent of hydrochorous dispersal into and out of a small floodplain area along a free‐flowing river in The Netherlands? Location: The Kappersbult nature reserve (53°07′28″N, 6°37′14″E), which is a floodplain along the Dutch River Drentsche Aa. Methods: Seeds transported by the river were collected in fine mesh nets for 24 consecutive hours once or twice a week for 1 year, upstream and downstream of the studied floodplain. Data on the captured seeds were related to species traits and abiotic factors and species composition in the floodplain. Results: The floodplain functioned both as a seed source and sink. High levels of river water seemed to promote seed transport to or from the floodplain. Seeds of riverbank species occurred significantly more often in the river water than expected. Net source species had significantly higher seed production, taller stature and higher seed buoyancy, but lower site elevation than net sink species. Seed weight was significantly higher for sink species than for other species. Conclusion: Our study found that inundation, and therefore more natural river water management, is a prerequisite for seed transport to and from a floodplain. The restoration of target floodplain vegetation may be successful for common species that produce many seeds and grow in proximity to the river. Consequently, it is expected that the probability of restoring vegetation types that occur further from the river, such as wet grasslands, by hydrochorous dispersal is low.     

林芝云杉群落特征的研究

析了林芝云杉( Picea likiangensis var. linzhiensis )群落的种类组成、区系特征、群落外貌、垂直结构和水平结构等特性。结果表明：调查样地共有维管植物144种,隶属于53科116属,其中只含1种的属占81.03%。林芝云杉群落的区系组成、植物生活型谱、叶片性质等特征反映了群落的温带性质。群落垂直结构明显,可分为乔木层、灌木层、草本层及层间植物,乔木层郁闭度为0.4~0.8,林芝云杉大多为乔木层的单一优势种,有时与急尖长苞冷杉(Abies georgei var. smithii)、华山松(Pinus armandii)等混生,而群落植物的水平分布不均匀。优势种种群的年龄结构分析表明,该种群处于稳定状态;群落的物种丰富度为32.6364,其Shannon-Wiener指数为3.0926,Simpson指数为0.9366,均匀度指数为0.8942,且均为草本层>灌木层>乔木层。     

哀牢山中山湿性常绿阔叶林不同生长基质苔藓植物的组成与分布特征

苔藓植物是构成山地原生常绿阔叶林结构及景观的重要组分之一,在生态系统生物多样性的维系等方面发挥重要的生态功能。本研究以云南哀牢山中山湿性常绿阔叶林为对象,对林冠树干和林下木质残体、林地及岩石表面四类不同生长基质上苔藓植物的物种分布特征进行了调查研究,并运用Kendall一致性指数计算了各生长基质上苔藓植物物种之间的相关联程度,用聚类的方法对不同生长基质上苔藓植物物种进行了分类。研究结果表明：本区山地森林具有丰富的苔藓植物,共记录141种,分属38科69属,其中林冠树干上分布的苔藓植物的物种数量最多,为94种,林地上最少,仅29种;有27种苔藓植物同时分布在这3种以上的生长基质上。通过对不同类型生长基质之间苔藓植物种间关联程度的分析,发现在微生境的尺度上,随着优势苔藓植物种类间的关联程度的增加,苔藓植物多样性呈现出逐渐减少的趋势。     

三门湾海域冬夏季口足目和十足目虾类的种类组成、时空分布及多样性分析

根据2007年12月和2008年6月三门湾海域的2个航次的渔业资源调查资料,研究三门湾海域口足目与十足目中虾类在冬季和夏季的密度、优势种及多样性的时空分布,并结合该调查海区的地形地貌和水文等因素对虾类的分布进行分析.结果表明,三门湾海域虾类以广温、广盐种为主,其夏季种类数高于冬季,且夏季虾类质量和尾数密度均值亦高于冬季...     

Restoration of managed pine fens: effect on hydrology and vegetation

Question: How does restoration affect the hydrology and the understorey vegetation of managed pine fens? Location: Oligotrophic pine fens in Natura 2000 areas in Kainuu, eastern Finland. Methods: Eleven managed pine fens and eight pristine reference pine fens were chosen for the study in 2005. The managed fens, which had been drained for forestry during the 1970s and 1980s, were restored in 2007. The water table was monitored in all fens over four growing seasons during 2006 to 2009, and vegetation was surveyed from permanent sample plots in 2006 and 2009. Results: Before restoration in 2006, the water table was at a significantly lower level in the managed fens compared with the pristine fens. Immediately after restoration, the water table rose to the same level as in the pristine fens, and this change was permanent. Forest drainage had had little impact on the understorey vegetation of the managed fens in the three decades before restoration, with species typical of pristine fens still dominating the sites. Forest dwarf shrubs and feather mosses had started to increase in cover, but mire dwarf shrubs and Sphagnum mosses still dominated the managed fens. Only the typical hollow species Sphagnum majus, Sphagnum balticum and Scheuzeria palustris were missing from the managed fens. Two years after restoration, the changes in species composition were also marginal, with increased cover of mire dwarf shrubs and sedges being the only significant change. Conclusions: The success of restoration of oligotrophic pine fens seems likely, given that changes in hydrological functioning occurred rapidly, and since little change has occurred in the vegetation composition after draining. Speeding up the regeneration process in these peatland types by restoration may, therefore, be recommended, especially if the drainage effect extends to nearby pristine mires and influences their biodiversity.