外源性视黄酸对斑马鱼心血管系统发育的影响

目的观察不同浓度外源性视黄酸对斑马鱼早期胚胎和心血管系统发育的影响,为进一步研究视黄酸影响斑马鱼心脏前后轴(A-P轴)发育的分子机制提供形态学依据。方法选择斑马鱼胚胎孵育的3,6,9·5,12h四个时间点,用不同浓度视黄酸(1×10-6,1×10-7,4×10-8,1×10-8mol/L)处理斑马鱼胚胎,在解剖显微镜下实时观察斑马鱼胚胎心脏发育的全过程和视黄酸对斑马鱼心脏发育的影响。并采用胚胎整体原位杂交技术观察flk-1mRNA在斑马鱼胚胎的表达。结果1×10-6mol/L视黄酸可导致斑马鱼胚胎表现出多系统的严重畸形,胚胎很快死亡。在胚胎孵育的9·5、12h给与10-7~10-8mol/L浓度的视黄酸,胚胎只表现出心血管系统的畸形,其他系统无明显异常。胚胎整体原位杂交显示视黄酸对flk-1mRNA在斑马鱼胚胎血管的表达没有影响。结论视黄酸影响斑马鱼胚胎心脏发育有剂量依赖性和严格的时间窗,视黄酸影响心脏前后轴发育的关键时间是原肠胚晚期。视黄酸处理组胚胎的循环缺陷主要为心脏发育异常所致。10-7~10-8mol/L浓度视黄酸在9·5、12h处理斑马鱼胚胎可以作为研究心脏发育调控机制的动物模型。     

Sea turtle nesting distributions and oceanographic constraints on hatchling migration

Patterns of abundance across a species''s reproductive range are influenced by ecological and environmental factors that affect the survival of offspring. For marine animals whose offspring must migrate long distances, natural selection may favour reproduction in areas near ocean currents that facilitate migratory movements. Similarly, selection may act against the use of potential reproductive areas from which offspring have difficulty emigrating. As a first step towards investigating this conceptual framework, we analysed loggerhead sea turtle (Caretta caretta) nest abundance along the southeastern US coast as a function of distance to the Gulf Stream System (GSS), the ocean current to which hatchlings in this region migrate. Results indicate that nest density increases as distance to the GSS decreases. Distance to the GSS can account for at least 90 per cent of spatial variation in regional nest density. Even at smaller spatial scales, where local beach conditions presumably exert strong effects, at least 38 per cent of the variance is explained by distance from the GSS. These findings suggest that proximity to favourable ocean currents strongly influences sea turtle nesting distributions. Similar factors may influence patterns of abundance across the reproductive ranges of diverse marine animals, such as penguins, eels, salmon and seals.     

A Comprehensive Proteomic Analysis of the Type III Secretome of Citrobacter rodentium

Enteropathogenic Escherichia coli, enterohemorrhagic E. coli, and Citrobacter rodentium belong to the family of attaching and effacing (A/E) bacterial pathogens. They intimately attach to host intestinal epithelial cells, trigger the effacement of intestinal microvilli, and cause diarrheal disease. Central to their pathogenesis is a type III secretion system (T3SS) encoded by a pathogenicity island called the locus of enterocyte effacement (LEE). The T3SS is used to inject both LEE- and non-LEE-encoded effector proteins into the host cell, where these effectors modulate host signaling pathways and immune responses. Identifying the effectors and elucidating their functions are central to understanding the molecular pathogenesis of these pathogens. Here we analyzed the type III secretome of C. rodentium using the highly sensitive and quantitative SILAC (stable isotope labeling with amino acids in cell culture)-based mass spectrometry. This approach not only confirmed nearly all known secreted proteins and effectors previously identified by conventional biochemical and proteomic techniques, but also identified several new secreted proteins. The T3SS-dependent secretion of these new proteins was validated, and five of them were translocated into cultured cells, representing new or additional effectors. Deletion mutants for genes encoding these effectors were generated in C. rodentium and tested in a murine infection model. This study comprehensively characterizes the type III secretome of C. rodentium, expands the repertoire of type III secreted proteins and effectors for the A/E pathogens, and demonstrates the simplicity and sensitivity of using SILAC-based quantitative proteomics as a tool for identifying substrates for protein secretion systems.     

Hypoxia Increases the Dependence of Glioma Cells on Glutathione

Glutathione (GSH) is an essential antioxidant responsible for the maintenance of intracellular redox homeostasis. As tumors outgrow their blood supply and become hypoxic, their redox homeostasis is challenged by the production of nitric oxide and reactive oxygen species (ROS). In gliomas, the sustained import of l-cystine via the l-cystine/l-glutamate exchanger, system x_c⁻, is rate-limiting for the synthesis of GSH. We show that hypoxia causes a significant increase in NO and ROS but without affecting glioma cell growth. This is explained by a concomitant increase in the utilization of GSH, which is accompanied by an increase in the cell-surface expression of xCT, the catalytic subunit of system x_c⁻, and l-cystine uptake. Growth was inhibited when GSH synthesis was blocked by buthionine sulfoximine (BSO), an inhibitor of the enzyme required for GSH synthesis, or when cells were deprived of l-cystine. These findings suggest that glioma cells show an increased requirement for GSH to maintain growth under hypoxic conditions. Therefore, approaches that limit GSH synthesis such as blocking system x_c⁻ may be considered as an adjuvant to radiation or chemotherapy.     

Finding a suitable system scale to optimize program performance on software DSM systems

Recently, software distributed shared memory systems have successfully provided an easy user interface to parallel user applications on distributed systems. In order to prompt program performance, most of DSM systems usually were greedy to utilize all of available processors in a computer network to execute user programs. However, using more processors to execute programs cannot necessarily guarantee to obtain better program performance. The overhead of paralleling programs is increased by the addition in the number of processors used for program execution. If the performance gain from program parallel cannot compensate for the overhead, increasing the number of execution processors will result in performance degradation and resource waste. In this paper, we proposed a mechanism to dynamically find a suitable system scale to optimize performance for DSM applications according to run-time information. The experimental results show that the proposed mechanism can precisely predict the processor number that will result in the best performance and then effectively optimize the performance of the test applications by adapting system scale according to the predicted result. Yi-Chang Zhuang received his B.S., M.S. and Ph.D. degrees in electrical engineering from National Cheng Kung University in 1995, 1997, and 2004. He is currently working as an engineer at Industrial Technology Research Institute in Taiwan. His research interests include object-based storage, file systems, distributed systems, and grid computing. Jyh-Biau Chang is currently an assistant professor at the Information Management Department of Leader University in Taiwan. He received his B.S., M.S. and Ph.D. degrees from Electrical Engineering Department of National Cheng Kung University in 1994, 1996, and 2005. His research interest is focused on cluster and grid computing, parallel and distributed system, and operating system. Tyng-Yeu Liang is currently an assistant professor who teaches and studies at Department of Electrical Engineering, National Kaohsiung University of Applied Sciences in Taiwan. He received his B.S., M.S. and Ph.D. degrees from National Cheng Kung University in 1992, 1994, and 2000. His study is interested in cluster and grid computing, image processing and multimedia. Ce-Kuen Shieh currently is a professor at the Electrical Engineering Department of National Cheng Kung University in Taiwan. He is also the chief of computation center at National Cheng Kung University. He received his Ph.D. degree from the Department of Electrical Engineering of National Cheng Kung University in 1988. He was the chairman of the Electrical Engineering Department of National Cheng Kung University from 2002 to 2005. His research interest is focused on computer network, and parallel and distributed system. Laurence T. Yang is a professor at the Department of Computer Science, St. Francis Xavier University, Canada. His research includes high performance computing and networking, embedded systems, ubiquitous/pervasive computing and intelligence, and autonomic and trusted computing.     

First record of an epibiosis between the sand crab Emerita analoga (Stimpson, 1857) (Decapoda: Hippidae) and the mussel Semimytilus algosus (Gould, 1850) (Bivalvia, Mytilidae) in southern Peru

Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.     

Immune modulation by mesenchymal stem cells

Mesenchymal stem cells (MSCs) have been shown to suppress activation of T cells both in vivo and in vitro. In vivo, this may be a way for the body to maintain homeostasis and inhibit immune activation in distinct compartments, such as the bone marrow and the interface between mother and fetus. MSCs modulate the immune function of the major cell populations involved in alloantigen recognition and elimination, including antigen presenting cells, T cells, and natural killer cells. The molecular mechanism that mediates the immunosuppressive effect of MSCs is not completely understood.     

Techniques of EMG signal analysis: detection, processing, classification and applications

Electromyography (EMG) signals can be used for clinical/biomedical applications, Evolvable Hardware Chip (EHW) development, and modern human computer interaction. EMG signals acquired from muscles require advanced methods for detection, decomposition, processing, and classification. The purpose of this paper is to illustrate the various methodologies and algorithms for EMG signal analysis to provide efficient and effective ways of understanding the signal and its nature. We further point up some of the hardware implementations using EMG focusing on applications related to prosthetic hand control, grasp recognition, and human computer interaction. A comparison study is also given to show performance of various EMG signal analysis methods. This paper provides researchers a good understanding of EMG signal and its analysis procedures. This knowledge will help them develop more powerful, flexible, and efficient applications.     

Detecting un-authorized genetically modified organisms (GMOs) and derived materials

Genetically modified plants, in the following referred to as genetically modified organisms or GMOs, have been commercially grown for almost two decades. In 2010 approximately 10% of the total global crop acreage was planted with GMOs (James, 2011). More than 30 countries have been growing commercial GMOs, and many more have performed field trials. Although the majority of commercial GMOs both in terms of acreage and specific events belong to the four species: soybean, maize, cotton and rapeseed, there are another 20 + species where GMOs are commercialized or in the pipeline for commercialization. The number of GMOs cultivated in field trials or for commercial production has constantly increased during this time period. So have the number of species, the number of countries involved, the diversity of novel (added) genetic elements and the global trade. All of these factors contribute to the increasing complexity of detecting and correctly identifying GMO derived material. Many jurisdictions, including the European Union (EU), legally distinguish between authorized (and therefore legal) and un-authorized (and therefore illegal) GMOs. Information about the developments, field trials, authorizations, cultivation, trade and observations made in the official GMO control laboratories in different countries around the world is often limited, despite several attempts such as the OECD BioTrack for voluntary dissemination of data. This lack of information inevitably makes it challenging to detect and identify GMOs, especially the un-authorized GMOs. The present paper reviews the state of the art technologies and approaches in light of coverage, practicability, sensitivity and limitations. Emphasis is put on exemplifying practical detection of un-authorized GMOs. Although this paper has a European (EU) bias when examples are given, the contents have global relevance.