Effects of inbreeding and genetic modification on Aedes aegypti larval competition and adult energy reserves

<p>Abstract</p> <p>Background</p> <p>Genetic modification of mosquitoes offers a promising strategy for the prevention and control of mosquito-borne diseases. For such a strategy to be effective, it is critically important that engineered strains are competitive enough to serve their intended function in population replacement or reduction of wild mosquitoes in nature. Thus far, fitness evaluations of genetically modified strains have not addressed the effects of competition among the aquatic stages and its consequences for adult fitness. We therefore tested the competitive success of combinations of wild, inbred and transgenic (created in the inbred background) immature stages of the dengue vector <it>Aedes aegypti </it>in the presence of optimal and sub-optimal larval diets.</p> <p>Results</p> <p>The wild strain of <it>Ae. aegypti </it>demonstrated greater performance (based on a composite index of survival, development rate and size) than the inbred strain, which in turn demonstrated greater performance than the genetically modified strain. Moreover, increasing competition through lowering the amount of diet available per larva affected fitness disproportionately: transgenic larvae had a reduced index of performance (95-119%) compared to inbred (50-88%) and wild type larvae (38-54%). In terms of teneral energy reserves (glycogen, lipid and sugar), adult wild type mosquitoes had more reserves directly available for flight, dispersal and basic metabolic functions than transgenic and inbred mosquitoes.</p> <p>Conclusions</p> <p>Our study provides a detailed assessment of inter- and intra-strain competition across aquatic stages of wild type, inbred, and transgenic mosquitoes and the impact of these conditions on adult energy reserves. Although it is not clear what competitive level is adequate for success of transgenic strains in nature, strong gene drive mechanisms are likely to be necessary in order to overcome competitive disadvantages in the larval stage that carryover to affect adult fitness.</p

Dive performance in a small-bodied, semi-aquatic mammal in the wild

Aquatic foraging is a fundamental component of the behavior of a number of small mammals, yet comprehensive observations of diving are often difficult to obtain under natural circumstances. Semiaquatic mammals, having evolved to exploit prey in both aquatic and terrestrial environments, are generally not as well adapted for diving (or for life in the water) as are fully aquatic species. Because dive ability also tends to increase with body size, small, semiaquatic mammals are presumed to have fairly limited dive ability. Nevertheless, diving plays an important role in food acquisition for many such species. We used time–depth recorders (TDRs) to measure and describe the dive performance of 9 female and 5 male free-living American mink (Neovison vison; body mass approximately 1 kg) on lowland rivers in the southern United Kingdom. We recorded dives up to 2.96 m deep (maximum depth X ¯ 5 1.82 m) and up to 57.9 s in duration (maximum duration X ¯ 5 37.2 s). Dive duration was approximately 40% of that predicted by allometry for all air-breathing diving vertebrates (as might be expected for a small, semiaquatic animal) but was twice as long as previously measured for mink in captivity. Mink performed up to 189 dives per day (X ¯ 5 35.7 dives/day), mostly during daylight, and spent a maximum of 38.4 minutes diving per day (X ¯ 5 7.6 min/day). Some individuals maintained particularly high diving rates over the coldest months, suggesting that the benefits of aquatic foraging in winter outweigh the costs of heat loss. We observed a number of very shallow dives (depth approximately 0.3 m) of particularly long duration (up to 30 s). The function of these dives is currently unknown, but possibilities include searching for prey, travelling, or avoidance of threats. There is only 1 other study of which we are aware that presents detailed measurements of dive performance in a small, shallow-diving, semiaquatic mammal.Fil: Harrington, Lauren. University of Oxford; Reino UnidoFil: Hays, Graeme C.. Swansea University; Reino UnidoFil: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Harrington, Andrew L.. University of Oxford; Reino UnidoFil: Righton, David. No especifíca;Fil: Macdonald, David W.. University of Oxford; Reino Unid

Considerations for Accurate Identification of Adult Culex restuans (Diptera: Culicidae) in Field Studies

ABSTRACT Understanding the ecology and behavior of different mosquito species (Diptera: Culicidae) is essential for identifying their role in disease transmission cycles and public health risk. Two species of Culex mosquitoes in the northeastern United States, Culex pipiens L. and Culex restuans Theobald, have been implicated in enzootic transmission of West Nile virus (family Flaviviridae, genus Flavivirus, WNV). Despite the difÞculty of differentiating these two species as adults, many public health workers and vector biologists collecting adults in the Þeld separate these species based on external morphology. This approach is often used rather than examination of dissected male genitalia or polymerase chain reaction (PCR)-based diagnostics due to time or cost constraints. We evaluated the reliability of seven published morphological characters to differentiate adults of these species by comparing blindly scored morphology with PCR-based conÞrmations. Our study demonstrates that morphological identiÞcation of Cx. pipiens is marginal and often not reliable for Cx. restuans. We also examined error rates with molecular-based approaches. DNA samples were contaminated with as little as one leg from another species. We conclude that to fully understand the respective roles of Culex species in the epidemiology of WNV and other pathogens, more attention should be paid to these considerations for accurate species identiÞcation

Blood feeding patterns of mosquitoes: random or structured?

<p>Abstract</p> <p>Background</p> <p>The foraging behavior of blood-sucking arthropods is the defining biological event shaping the transmission cycle of vector-borne parasites. It is also a phenomenon that pertains to the realm of community ecology, since blood-feeding patterns of vectors can occur across a community of vertebrate hosts. Although great advances in knowledge of the genetic basis for blood-feeding choices have been reported for selected vector species, little is known about the role of community composition of vertebrate hosts in determining such patterns.</p> <p>Methods & Results</p> <p>Here, we present an analysis of feeding patterns of vectors across a variety of locations, looking at foraging patterns of communities of mosquitoes, across communities of hosts primarily comprised of mammals and birds. Using null models of species co-occurrence, which do not require ancillary information about host abundance, we found that blood-feeding patterns were aggregated in studies from multiple sites, but random in studies from a single site. This combination of results supports the idea that mosquito species in a community may rely primarily on host availability in a given landscape, and that contacts with specific hosts will be influenced more by the presence/absence of hosts than by innate mosquito choices. This observation stresses the importance of blood-feeding plasticity as a key trait explaining the emergence of many zoonotic mosquito transmitted diseases.</p> <p>Discussion</p> <p>From an epidemiological perspective our observations support the idea that phenomena promoting synchronization of vectors and hosts can promote the emergence of vector-borne zoonotic diseases, as suggested by observations on the linkages between deforestation and the emergence of several human diseases.</p

The TSC1-2 tumor suppressor controls insulin–PI3K signaling via regulation of IRS proteins

Insulin-like growth factors elicit many responses through activation of phosphoinositide 3-OH kinase (PI3K). The tuberous sclerosis complex (TSC1-2) suppresses cell growth by negatively regulating a protein kinase, p70S6K (S6K1), which generally requires PI3K signals for its activation. Here, we show that TSC1-2 is required for insulin signaling to PI3K. TSC1-2 maintains insulin signaling to PI3K by restraining the activity of S6K, which when activated inactivates insulin receptor substrate (IRS) function, via repression of IRS-1 gene expression and via direct phosphorylation of IRS-1. Our results argue that the low malignant potential of tumors arising from TSC1-2 dysfunction may be explained by the failure of TSC mutant cells to activate PI3K and its downstream effectors

PenQuest Volume 1, Number 2

Table of Contents for this Volume: Untitled by Julie Ambrose Night by Judith Gallo Untitled by Judy Gozdur the shamans by Charles Riddles Untitled by Jerry Connell Untitled by Laura Woods Untitled by LEMA Wicked Bird by Laura Jo Last Untitled by Rick Dentos Untitled by Jeni Moody Untitled by Bettie W. Kwibs Untitled by Joann Stagg The Protector Stood by Laura Jo Last Visions of Salome by Charles Riddles Untitled by Thomas Tutten Kennesaw Line by Don Ova-Dunaway Stone Blood by Mary Ellen C. Wofford Untitled by Roger Whitt Jr. Untitled by C. Wingate Untitled by Doug Dorey Untitled by Karen Blumberg Untitled by Beverly Oviatt Untitled by Virginia Shrader The Crapulous Credo of Charles C. by Charles Riddles the brave and the true by David Reed Untitled by Charles Gutierrez Canoe Creek by Patricia Kraft Untitled by Linda Bobinger The Man in the Iron Lung by Patricia Kraft Untitled by Roger Whitt, Jr. Childish Things by Kathleen Gay Untitled by Joseph Avanzini The Lover by Mary S. Aken Untitled by Ann Harrington And He Taketh Away by David Reed Untitled by Mary Graham Untitled by Melody A. Cummons Untitled by Karen Blumberg To The Poets by Judith Gallo Untitled by Ann Harringto

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011