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Sharma K.R.,Auburn University | Sharma K.R.,900 University Avenue | Fadamiro H.Y.,Auburn University
Journal of Insect Physiology | Year: 2013

Pseudacteon tricuspis, Pseudacteon obtusus and Pseudacteon curvatus are three species of parasitic phorid flies (Diptera: Phoridae), which have been introduced as classical biological control agents of imported, Solenopsis fire ants (Hymenoptera: Formicidae) in the southern USA. Previous studies demonstrated the behavioral response of P. tricuspis to the venom alkaloids and alarm pheromone of the fire ant, S. invicta. In the present study, we compared the responses of P. tricuspis, P. obtusus and P. curvatus to Solenopsis invicta alarm pheromone, venom alkaloids, or a mixture of both chemicals in four-choice olfactometer bioassays. The main hypothesis tested was that the fire ant alarm pheromone and venom alkaloids act in concert to attract Pseudacteon phorid flies. Both sexes of all three Pseudacteon species were attracted to low doses of the fire ant alarm pheromone or venom alkaloids (i.e. 1 ant worker equivalent) alone. However, the flies were significantly more attracted to a mixture of both chemicals (i.e., 1:1 mixture of alarm pheromone. +. alkaloids) than to either chemical. The results suggest an additive rather than a synergistic effect of combining both chemicals. Comparing the fly species, P. tricuspis showed relatively greater attraction to cis alkaloids, whereas the alkaloid mixture (cis+. trans) was preferred by P. obtusus and P. curvatus. In general, no key sexual differences were recorded, although females of P. tricuspis and P. obtusus showed slightly higher response than conspecific males to lower doses of the alarm pheromone. The ecological significance of these findings is discussed, and a host location model is proposed for parasitic phorid flies involving the use of fire ant alarm pheromone and venom alkaloids as long range and short range attractants, respectively. © 2013 Elsevier Ltd. Source

Pires M.N.,University of California at Riverside | Pires M.N.,900 University Avenue | Bassar R.D.,University of California at Riverside | Mcbride K.E.,University of California at Riverside | And 3 more authors.
Functional Ecology | Year: 2011

1. The Northern Clade of the fish genus Poeciliopsis includes six closely related species, three of which lack placentas and three that have placentas but vary in the extent of post-fertilization provisioning. 2. We used this diversity to evaluate a series of hypotheses proposed in earlier publications concerning why the placenta has evolved. All hypotheses share the attribute of arguing that the placenta evolved to enhance the evolution of some other life-history trait, such as to reduce the age at maturation or to increase offspring size. We refer to these hypotheses collectively as 'life-history facilitation hypotheses'. 3. A general way to evaluate the plausibility of such proposals is to ask whether the evolution of the placenta is predictably associated with the evolution of other components of the life history. 4. We evaluated such associations in two ways. First, we performed a multivariate analysis of life-history data for fish collected and preserved in nature. This analysis included 16 populations across all six species. Secondly, we performed a more complete quantification of the life histories of the laboratory descendents from five populations representing four species, then performed a similar multivariate analysis. The laboratory study added information about the timing of reproduction (age at maturity, frequency of reproduction). 5. Both analyses yielded similar results, which were that the evolution of increased placentation is correlated with the evolution of a smaller size at first reproduction, the production of fewer and smaller offspring per litter, but an increase in the number of litters that were developing simultaneously in the ovary (superfetation). Increased placentation is associated with progressively earlier ages at maturation and shorter intervals between the birth of successive litters of offspring. Overall, increased placentation was associated with an increase in the rate of production of offspring early in life. A peculiar attribute of placentation is that this increase in the rate of offspring production can be attained despite a simultaneous reduction in the proportional quantity of resources devoted to reproduction. 6. These trends support one of the life history facilitation hypotheses, which is that placentation facilitates earlier maturity and a higher rate of reproduction early in life. They also suggest a possible connection between the evolution of the placenta and the well-established theory of life-history evolution, since these same life history attributes are predicted to evolve in response to exposure to high extrinsic rates of adult mortality. © 2011 The Authors. Functional Ecology © 2011 British Ecological Society. Source

Zhao Y.,900 University Avenue | Liao J.,900 University Avenue | Liao J.,University of California at Riverside
Heterocycles | Year: 2011

GW1100 is an antagonist of GPR40 identified by high throughput screening recently. The feasible synthesis of GW1100 has been developed in mild conditions. The key step involves the cyclization of the 2-thiouracil heterocycle under acidic conditions at room temperature. © The Japan Institute of Heterocyclic Chemistry. Source

Malik-Chaudhry H.K.,900 University Avenue | Saavedra A.,900 University Avenue | Liao J.,900 University Avenue | Liao J.,University of California at Riverside
Biotechnology and Bioengineering | Year: 2014

Förster resonance energy transfer (FRET) technology has been widely used in biological and biomedical research and is a valuable tool for elucidating molecular interactions in vitro and in vivo. Quantitative FRET analysis is a powerful method for determining biochemical parameters and molecular distances at nanometer levels. Recently, we reported theoretical developments and experimental procedures for determining the dissociation constant, Kd and enzymatic kinetics parameters, Kcat and KM, of protein interactions with the engineered FRET pair, CyPet and YPet. The strong FRET signal from this pair made these developments possible. However, the direct link of fluorescent proteins with proteins of interests may interfere with the folding of some fusion proteins. Here, we report a new protein engineering strategy for improving FRET signals by adding a linker between the fluorescent protein and the targeted protein. This improvement allowed us to follow the covalent conjugation of NEDD8 to its E2 ligase in the presence of E1 and ATP, which was difficult to determine without linker. Three linkers, LAEAAAKEAA, TSGSPGLQEFGT, and LAAALAAA, which are alpha helix or random coil, all significantly improved the FRET signals. Our results show a general methodology for improving trans-FRET signals to effectively determine biochemical reaction intermediates. © 2014 Wiley Periodicals, Inc. Source

Evtyushkin D.,Binghamton University State University of New York | Ponomarev D.,Binghamton University State University of New York | Abu-Ghazaleh N.,University of California at Riverside | Abu-Ghazaleh N.,900 University Avenue
ACM Transactions on Architecture and Code Optimization | Year: 2016

Covert channels through shared processor resources provide secret communication between two malicious processes: the trojan and the spy. In this article, we classify, analyze, and compare covert channels through dynamic branch prediction units in modern processors. Through experiments on a real hardware platform, we compare contention-based channel and the channel that is based on exploiting the branch predictor's residual state. We analyze these channels in SMT and single-threaded environments under both clean and noisy conditions. Our results show that the residual state-based channel provides a cleaner signal and is effective even in noisy execution environments with another application sharing the same physical core with the trojan and the spy. We also estimate the capacity of the branch predictor covert channels and describe a software-only mitigation technique that is based on randomizing the state of the predictor tables on context switches. We show that this protection eliminates all covert channels through the branch prediction unit with minimal impact on performance. © 2016 ACM. Source

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