基于DNA条形码技术的海参物种鉴定

DNA条形码技术(DNA barcoding)是一种新型高效的物种鉴别方法。本研究基于DNA条形码技术,以线粒体细胞色素氧化酶I基因(COI)和16S核糖体RNA(16S rRNA)基因作为靶基因对海参物种进行鉴别,结果表明COI基因或16S rRNA基因均能实现大部分海参的物种鉴定,部分样品需结合两个靶基因鉴定出来。将所建立的DNA条形码方法用于市售海参样品的物种鉴定,24份市售海参样品中10份市售海参样品的物种鉴定结果与标签名称相符,6份样品与标签名称不符,存在将低价海参品种标为高价海参的现象;其余8份样品的标签只有商品名但没有明确的物种信息,利用DNA条形码技术对其鉴定可得到明确的海参种名。本研究结果证实DNA条形码技术可应用于市售海参的物种鉴定,为海参的监管提供技术支撑。     

DNA barcoding to confirm morphological traits and determine relative abundance of burrowing mayfly species in western Lake Erie

Burrowing mayfly species of the genus Hexagenia are well known indicators of environmental health in lakes and rivers. Two species, H. limbata and H. rigida, are indistinguishable as nymphs and as adult females. Our objectives were to develop a genetic technique to distinguish between the two species and identify morphological features that separate cryptic nymphs and adult females. Fifty nymphs were collected before emergence from 10 sites throughout the western basin of Lake Erie in 2004 and 2005. Using known specimens of adult aerial male H. limbata and H. rigida, we used the mitochondrial cytochrome c oxidase subunit 1 (COI) gene to identify a 16 base pair (bp) difference between species. DNA sequencing confirmed correct species identification based on differences in abdominal pigmentation patterns on adult female imagos in 19 of 20 cases; the lone exception was a female with very faint pigmentation. Pigmentation patterns between species were consistent on nymphs, subimagos and imagos of both sexes. Populations of both species are panmictic across the western basin of Lake Erie, but H. limbata is the numerically dominant species, representing 70 to 100% of nymphs at sites in both years. A separate lineage of H limbata was discovered in the samples. The ability to distinguish nymphs of the two species will aid in developing more sensitive ecosystem indicators.     

A study on robust adaptive modulation controller for TCSC based on COI signal in interconnected power systems

This paper proposes a novel robust adaptive modulation controller (RAMC) for thyristor controlled series capacitor (TCSC) in interconnected power systems to damp low frequency oscillation. The main idea of the controller is to drive the area centers of inertia (COI) to a stable equilibrium point and keep system synchronization. COI-coordinate-based model is derived first. Then RAMC for TCSC is derived using back-stepping method with COI dynamic signals from WAMS. The new controller performance is tested through a three-area power system and the simulation results show clearly that the new controller using COI signals has superior performance as compared with the conventional controller.     

Modeling and simulation on long-term dynamics of interconnected power system using area COI concept

In order to study long-term frequency and voltage dynamics of interconnected power systems under cascading events, the paper has developed a proper mathematical model and simulation algorithm for it with network structure preserved. Similar to the traditional dynamic power flow, the proposed model assumes that the system has survived in the transient stability and has enough damping torque. Therefore, the relative swings among generator rotors in one area will be neglected in long-term dynamics; and each control area is assumed to have a uniform frequency, represented by its area center of inertia (COI). Fast decoupled method has been extended to solve the structure-preserved multi-area network equations. Computer test results from a modified IEEE30-bus power system demonstrate the validity and effectiveness of the proposed model and algorithm. The work establishes a simulation platform for future study on long-term frequency and voltage stability control strategy and coordination of interconnected power systems.     

The genetic diversity of two invasive sympatric bivalves (Corbicula fluminea and Dreissena polymorpha) from Lakes Garda and Maggiore,Northern Italy

Corbicula fluminea and Dreissena polymorpha are two non-indigenous species (NIS), known to provoke biodiversity loss of the existent native communities and alterations in the ecosystem functioning structure. Both of these NIS have successfully founded well established populations in Lakes Maggiore and Garda (Northern Italy). Here, we evaluated the mitochondrial COI genetic diversity of C. fluminea and D. polymorpha populations from the aforementioned lakes. The COI gene analysis revealed one C. fluminea haplotype, belonging to the FW5 androgenetic invasive lineage. Two D. polymorpha haplotypes – LM1 and LM2 – were detected in Lake Maggiore. The D. polymorpha comparative phylogeographical haplotype analysis between Lake Maggiore and the retrieved COI data available from Lake Garda revealed that LM1 is the dominant haplotype in both populations, whereas LM2 a rare haplotype was only detected in Lake Maggiore. These findings contribute for a better understanding of the demographic history of these highly invasive species in these Italian lakes, thus suggesting that C. fluminea and D. polymorpha populations present a similar genetic pattern. The low genetic diversity detected in both of these bivalve populations seems to reflect a pre-existent low genetic pool prevenient from the introductory source(s).     

双馈风电机组对接入区域系统暂态功角稳定性的影响分析

系统惯性中心的动态行为可以有效地反映系统的整体动态趋势。基于系统惯性中心的动态数学模型,推导了双馈风电机组(Doubly Fed Induction Generator, DFIG)接入后的系统惯性中心运动方程。并通过分析DFIG接入对系统惯性中心运动方程中关键因素的影响,揭示了DFIG以不同方式接入系统时对系统惯性中心功角加速度暂态响应的影响机理。当DFIG直接接入系统时,系统惯性中心的暂态功角加速度的变化趋势主要取决于DFIG的接入容量和暂态功率响应特性。当DFIG等容替代同步发电机组接入系统时,DFIG的暂态功率响应和被替代同步发电机组的功率和惯量在原系统中的比重大小将共同决定系统惯性中心的暂态功角加速度的变化情况。仿真结果验证了理论分析的有效性和正确性。     

互联系统长期动态仿真的结构保留建模

为了研究互联电力系统在级联事件下的频率和电压长期动态特性及其控制,提出了一种网络结构保留的多区域互联系统长期动态仿真模型和算法.与动态潮流计算相似,模型假定系统已渡过初始的暂态稳定阶段且有足够阻尼,从而忽略同一控制区域的机组间相对摇摆,即假定每个控制区域具有统一的频率动态,即区域内惯量中心动态,以便仿真几分钟及更长时间的长期动态.IEEE 30节点3区域系统的仿真结果表明了文中建议的仿真模型的可行性和计算方法的有效性;与详细机电暂态仿真软件仿真结果的比较表明,"区域统一频率动态"假定引起的系统长期动态仿真误差在工程上可以接受.从而为进一步开展级联事件下的频率和电压长期动态的稳定控制和协调提供了仿真工具.     

A simple molecular assay differentiates two burrowing mayfly species, Hexagenia limbata and H. rigida (Ephemeroptera: Ephemeridae), in western Lake Erie

Burrowing mayflies (Hexagenia spp.) are important indicators of mesotrophic water conditions, and have been studied for several decades in conjunction with the changing trophic status of western Lake Erie. However, most studies on the biology of burrowing mayflies have failed to differentiate between immature H. limbata and H. rigida, the life stages that are most commonly collected. We developed a simple molecular assay to facilitate species-level identification of the two mayflies as an easier alternative to sequencing the COI gene. We analyzed a total of 152 cytochrome c oxidase, subunit I barcoding sequences from the Barcode of Life Data System (BOLD) for these mayfly species and developed a diagnostic primer set. We tested our primers on 46 random burrowing Lake Erie mayfly nymphs using both conventional PCR and qPCR. Results of the two methods were consistent and unambiguous. Sequencing of the COI barcoding region in the mayflies confirmed that the PCR assays correctly identified mayflies in all cases. Our assay is simple and effective, and will facilitate species-level identification of burrowing mayflies in future studies on their biology where the two species co-occur.     

DNA barcoding reveals commercial and health issues in ethnic seafood sold on the Italian market

The number of seafood species sold on Western markets is constantly growing and many unconventional species are sold in ethnic food outlets. In this work, 68 ethnic seafood products variously processed were collected from the Italian market and a molecular analysis was performed by sequencing a full cytochrome c oxidase (COI) DNA barcode (FDB, ∼655 bp) or a mini COI DNA barcode (MDB, ∼139 bp) using universal primers. Barcodes were then compared with sequences available in BOLD and GenBank. In addition, the label information was assessed according to the European legislation. By using the IDs analysis on BOLD a maximum species identity ≥98% was retrieved for 84% of the sequences. Of these, 67% were unambiguously identified at species level (51.3% of the FDB and 74% of the MDB). Using NCBI BLAST, 74% of the sequences scored a maximum species identity ≥98%, of which 73% were identified at species level (52% of the FDB and 61% of the MDB). Both databases performed better in mollusk identification. Overall, 45 products (66%) were not correctly labeled according to the European requirements. Finally, the comparison between the molecular and the label analysis highlighted that 48.5% of the products presented discrepancies between labeling and molecular identification. In particular, health implications were highlighted for 2 samples labeled as squid but identified as Lagocephalus spp., a poisonous puffer fish species banned from the EU market. The present results confirm DNA barcoding as a reliable tool for protecting consumers' health and economic interests.