Predation by invertebrate predators on the colonial rotifer Sinantherina socialis

Abstract. Colonies of the freshwater colonial rotifer Sinantherina socialis (Monogononta, Flosculariidae) have been shown to be unpalatable to a variety of small-mouthed, zooplanktivorous fishes. To test whether invertebrate predators ingest the rotifer S. socialis , we conducted two types of experiments: (1) Microcosm experiments—in separate experiments, four invertebrate predators (i.e., dragonfly nymphs, damselfly nymphs, notonectids, and Hydra ) were offered prey either singly or in combination. Prey were comprised of S. socialis; Epiphanes senta , a solitary, free-swimming rotifer; and Daphnia magna , a microcrustacean. In each experiment, the percent of prey surviving after 12, 18, and 24 h was recorded. (2) Paired-feeding experiments—in separate experiments, predators were offered prey in a pairwise fashion, in which members of D. magna were alternated with a rotifer, either S. socialis or E. senta. The results of the microcosm experiments showed that, after 24 h, 60–100% prey items of S. socialis survived the predators, but significantly fewer individuals of E. senta (6–89%) and D. magna (<25%) survived. When offered rotifers and individuals of D. magna simultaneously, predators tested consistently consumed more specimens of Daphnia. However, predators significantly reduced percent survival in E. senta but not in S. socialis. Predators, given a choice between the two rotifer species, all consumed significantly more specimens of E. senta than S. socialis after 24 h. In the paired-feeding experiments, three of the four predators captured members of S. socialis , but these colonies were frequently released rather than ingested, although in some cases colony structure was seriously disrupted. Our results suggest that the unpalatable nature of members of S. socialis to certain fishes extends to several invertebrate predators, but the nature of the putative factor(s) responsible for this remains unknown.     

Synthesis and structure-function study of artificial nucleases on the basis of hemin conjugates with peptide fragments of cell differentiation factor HLDF

A series of octa-hexapeptide fragments of HLDF and their conjugates with hemin were obtained by solid phase peptide synthesis. A relationship between the structure and the nuclease activity of the compounds was established. The effect of various factors (medium pH, the presence of metal ions, complexons, reducers, and buffer composition) on the DNA destruction with hemin peptides was studied. Preliminary information confirming an oxidative mechanism of this process was obtained. The cleavage of plasmid DNA under the action of hemin peptides was studied by the methods of electron microscopy, gel electrophoresis, and atomic force microscopy.     

Interaction of delta sleep-inducing peptide and its analogues with cellular membranes: A structure-function analysis

The possibility of a correlation between the membrane properties of the delta sleep-inducing peptide (DSIP) and its analogues and their biological activity in vivo was examined by a comparative study of the membrane effects of these peptides. The peptides exhibiting biological activity in vivo were shown to cause a statistically reliable disordering of lipids in thrombocyte plasma membranes similar to the effect of DSIP. The membrane effect of the D-Val²-, D-Tyr²-, and Tyr¹, Pro² analogues of DSIP had the same bimodal dose dependence characteristic of natural DSIP. Only a slight nonspecific lipid disordering was registered for Trp-Asp-Ala-Ser-Gly-Glu, a biologically inactive hexapeptide analogue. These results indicate a correlation between the biological activity of the peptides during in vivo tests and their membrane properties in vitro. The structure-function relationship was studied within the group of DSIP analogues examined in vitro. The DSIP modeling effect, especially pronounced under the action of stress factors, was suggested to be directly associated with the ability of DSIP to change the dynamic structure of biological membranes.     

A synthesis of cinnamoyloxyisoflavones

Interaction of 7-hydroxyisoflavonones with cinnamoyl chloride results in cinnamoyloxyisoflavonones.     

Whole blood glutathione peroxidase and erythrocyte superoxide dismutase activities, serum trace elements (Se, Cu, Zn) and cardiovascular risk factors in subjects from the city of Ponta Delgada, Island of San Miguel, The Azores Archipelago, Portugal

Activities of whole blood glutathione peroxidase (GSH-Px) and erythrocyte superoxide dismutase (SOD) and serum levels of selenium (Se), copper (Cu) and zinc (Zn) were measured in 118 apparently healthy subjects aged 20-60 years from the city of Ponta Delgada, Island of San Miguel, The Azores Archipelago, Portugal. Data were analysed by age/gender, lipid profile and blood pressure as cardiovascular risk factors searching for their relevance when assessing reference values for antioxidant biomarkers. GSH-Px was in the same range, but SOD was significantly lower than in other Portuguese populations. Neither activity differed with gender. GSH-Px activity increased with age, namely in normolipidemic men versus the hyperlipidemic group in which a decrease was observed. This suggests a progressive impairment of GSH-Px with age caused by an enhanced production of oxidant species in hyperlipidemia. GSH-Px was 30% lower in male hypertensives versus normotensives. SOD activity did not relate to age or blood pressure but was 17% higher in the hyperlipidemic men versus the normolipidemic group, suggesting a better antioxidant protection by SOD than by GSH-Px in hyperlipidemia and hypertension. Se was higher in men versus women, particularly in the older subjects, and partly related to hyperlipidemia. Zn levels showed a similar dependency on gender, not related to age or lipid profile. Cu levels were much higher in women than in men in all age or lipid profile classes and decreased in hyperlipidemia. They were lowered with age in both genders, particularly in normolipidemic women. The present research therefore suggests that hyperlipidemia and hypertension do affect antioxidant status and should be considered when assessing antioxidant biomarkers in blood.     

Reconsidering null models of diversity: Do geometric constraints on species ranges necessarily cause a mid‐domain effect?

Recent null models that place species ranges randomly within a bounded domain have produced controversial results. Many such geometric constraint models predict a peak in species richness in the centre of domains in the absence of underlying environmental gradients or interspecific interactions. We used two-dimensional simulation models to explore different ways that species ranges could interact with the domain boundary. In the rejection model, a randomly generated range that overlaps a domain boundary is removed from the simulation. In the reshaping model, a range that overlaps the domain boundary is reshaped so that the entire range is placed within the domain. The truncation model allows potential ranges to extend across the boundary, but only that portion of the range within the domain is included in the realized range. Both rejection and reshaping models produced a drop in species richness near domain boundaries, though the effect was less pronounced in the reshaping model. Our truncation model did not produce any spatial pattern in species richness. Thus the random placement of species ranges within a bounded domain does not necessarily lead to a mid-domain effect.
  Range truncation is consistent with bioclimate envelope models, which can successfully predict a species range in response to the availability of appropriate climate conditions. We argue that such flexible range sizes are more realistic than the assumption that range size is an unvarying characteristic of a species. Other range characteristics, including size and shape, can change near domain boundaries in the null models, including the truncation model. A broader consideration of range characteristics near domain boundaries could be productive.     

A taxonomy of application scheduling tools for high performance cluster computing

Application scheduling plays an important role in high-performance cluster computing. Application scheduling can be classified as job scheduling and task scheduling. This paper presents a survey on the software tools for the graph-based scheduling on cluster systems with the focus on task scheduling. The tasks of a parallel or distributed application can be properly scheduled onto multi-processors in order to optimize the performance of the program (e.g., execution time or resource utilization). In general, scheduling algorithms are designed based on the notion of task graph that represents the relationship of parallel tasks. The scheduling algorithms map the nodes of a graph to the processors in order to minimize overall execution time. Although many scheduling algorithms have been proposed in the literature, surprisingly not many practical tools can be found in practical use. After discussing the fundamental scheduling techniques, we propose a framework and taxonomy for the scheduling tools on clusters. Using this framework, the features of existing scheduling tools are analyzed and compared. We also discuss the important issues in improving the usability of the scheduling tools. This work is supported by the Hong Kong Polytechnic University under grant H-ZJ80 and by NASA Ames Research Center by a cooperative grant agreement with the University of Texas at Arlington. Jiannong Cao received the BSc degree in computer science from Nanjing University, Nanjing, China in 1982, and the MSc and the Ph.D degrees in computer science from Washington State University, Pullman, WA, USA, in 1986 and 1990 respectively. He is currently an associate professor in Department of Computing at the Hong Kong Polytechnic University, Hong Kong. He is also the director of the Internet and Mobile Computing Lab in the department. He was on the faculty of computer science at James Cook University and University of Adelaide in Australia, and City University of Hong Kong. His research interests include parallel and distributed computing, networking, mobile computing, fault tolerance, and distributed software architecture and tools. He has published over 120 technical papers in the above areas. He has served as a member of editorial boards of several international journals, a reviewer for international journals/conference proceedings, and also as an organizing/programme committee member for many international conferences. Dr. Cao is a member of the IEEE Computer Society, the IEEE Communication Society, IEEE, and ACM. He is also a member of the IEEE Technical Committee on Distributed Processing, IEEE Technical Committee on Parallel Processing, IEEE Technical Committee on Fault Tolerant Computing, and Computer Architecture Professional Committee of the China Computer Federation. Alvin Chan is currently an assistant professor at the Hong Kong Polytechnic University. He graduated from the University of New South Wales with a Ph.D. degree in 1995 and was subsequently employed as a Research Scientist by the CSIRO, Australia. From 1997 to 1998, he was employed by the Centre for Wireless Communications, National University of Singapore as a Program Manager. Dr. Chan is one of the founding members and director of a university spin-off company, Information Access Technology Limited. He is an active consultant and has been providing consultancy services to both local and overseas companies. His research interests include mobile computing, context-aware computing and smart card applications. Yudong Sun received the B.S. and M.S. degrees from Shanghai Jiao Tong University, China. He received Ph.D. degree from the University of Hong Kong in 2002, all in computer science. From 1988 to 1996, he was among the teaching staff in Department of Computer Science and Engineering at Shanghai Jiao Tong University. From 2002 to 2003, he held a research position at the Hong Kong Polytechnic University. At present, he is a Research Associate in School of Computing Science at University of Newcastle upon Tyne, UK. His research interests include parallel and distributed computing, Web services, Grid computing, and bioinformatics. Sajal K. Das is currently a Professor of Computer Science and Engineering and the Founding Director of the Center for Research in Wireless Mobility and Networking (CReWMaN) at the University of Texas at Arlington. His current research interests include resource and mobility management in wireless networks, mobile and pervasive computing, sensor networks, mobile internet, parallel processing, and grid computing. He has published over 250 research papers, and holds four US patents in wireless mobile networks. He received the Best Paper Awards in ACM MobiCom’99, ICOIN-16, ACM, MSWiM’00 and ACM/IEEE PADS’97. Dr. Das serves on the Editorial Boards of IEEE Transactions on Mobile Computing, ACM/Kluwer Wireless Networks, Parallel Processing Letters, Journal of Parallel Algorithms and Applications. He served as General Chair of IEEE PerCom’04, IWDC’04, MASCOTS’02 ACM WoWMoM’00-02; General Vice Chair of IEEE PerCom’03, ACM MobiCom’00 and IEEE HiPC’00-01; Program Chair of IWDC’02, WoWMoM’98-99; TPC Vice Chair of ICPADS’02; and as TPC member of numerous IEEE and ACM conferences. Minyi Guo received his Ph.D. degree in information science from University of Tsukuba, Japan in 1998. From 1998 to 2000, Dr. Guo had been a research scientist of NEC Soft, Ltd. Japan. He is currently a professor at the Department of Computer Software, The University of Aizu, Japan. From 2001 to 2003, he was a visiting professor of Georgia State University, USA, Hong Kong Polytechnic University, Hong Kong. Dr. Guo has served as general chair, program committee or organizing committee chair for many international conferences, and delivered more than 20 invited talks in USA, Australia, China, and Japan. He is the editor-in-chief of the Journal of Embedded Systems. He is also in editorial board of International Journal of High Performance Computing and Networking, Journal of Embedded Computing, Journal of Parallel and Distributed Scientific and Engineering Computing, and International Journal of Computer and Applications. Dr. Guo’s research interests include parallel and distributed processing, parallelizing compilers, data parallel languages, data mining, molecular computing and software engineering. He is a member of the ACM, IEEE, IEEE Computer Society, and IEICE. He is listed in Marquis Who’s Who in Science and Engineering.     

Genetic Engineering and Nitrogen Fixation

Molecular cloning is based on isolation of a DNA sequence of interest to obtain multiple copies of it in vitro. Application of this technique has become an increasingly important tool in clinical microbiology due to its simplicity, cost effectiveness, rapidity, and reliability. This review entails the recent advances in molecular cloning and its application in the clinical microbiology in the context of polymicrobial infections, recombinant antigens, recombinant vaccines, diagnostic probes, antimicrobial peptides, and recombinant cytokines. Culture-based methods in polymicrobial infection have many limitation, which has been overcome by cloning techniques and provide gold standard technique. Recombinant antigens produced by cloning technique are now being used for screening of HIV, HCV, HBV, CMV, Treponema pallidum, and other clinical infectious agents. Recombinant vaccines for hepatitis B, cholera, influenza A, and other diseases also use recombinant antigens which have replaced the use of live vaccines and thus reduce the risk for adverse effects. Gene probes developed by gene cloning have many applications including in early diagnosis of hereditary diseases, forensic investigations, and routine diagnosis. Industrial application of this technology produces new antibiotics in the form of antimicrobial peptides and recombinant cytokines that can be used as therapeutic agents.