663 research outputs found
Suboptimal Larval Habitats Modulate Oviposition of the Malaria Vector Mosquito Anopheles coluzzii.
Selection of oviposition sites by gravid females is a critical behavioral step in the reproductive cycle of Anopheles coluzzii, which is one of the principal Afrotropical malaria vector mosquitoes. Several studies suggest this decision is mediated by semiochemicals associated with potential oviposition sites. To better understand the chemosensory basis of this behavior and identify compounds that can modulate oviposition, we examined the generally held hypothesis that suboptimal larval habitats give rise to semiochemicals that negatively influence the oviposition preference of gravid females. Dual-choice bioassays indicated that oviposition sites conditioned in this manner do indeed foster significant and concentration dependent aversive effects on the oviposition site selection of gravid females. Headspace analyses derived from aversive habitats consistently noted the presence of dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and 6-methyl-5-hepten-2-one (sulcatone) each of which unitarily affected An. coluzzii oviposition preference. Electrophysiological assays across the antennae, maxillary palp, and labellum of gravid An. coluzzii revealed differential responses to these semiochemicals. Taken together, these findings validate the hypothesis in question and suggest that suboptimal environments for An. coluzzii larval development results in the release of DMDS, DMTS and sulcatone that impact the response valence of gravid females
Chemoreceptor Evolution in Hymenoptera and Its Implications for the Evolution of Eusociality.
Eusocial insects, mostly Hymenoptera, have evolved unique colonial lifestyles that rely on the perception of social context mainly through pheromones, and chemoreceptors are hypothesized to have played important adaptive roles in the evolution of sociality. However, because chemoreceptor repertoires have been characterized in few social insects and their solitary relatives, a comprehensive examination of this hypothesis has not been possible. Here, we annotate ∼3,000 odorant and gustatory receptors in recently sequenced Hymenoptera genomes and systematically compare >4,000 chemoreceptors from 13 hymenopterans, representing one solitary lineage (wasps) and three independently evolved eusocial lineages (ants and two bees). We observe a strong general tendency for chemoreceptors to expand in Hymenoptera, whereas the specifics of gene gains/losses are highly diverse between lineages. We also find more frequent positive selection on chemoreceptors in a facultative eusocial bee and in the common ancestor of ants compared with solitary wasps. Our results suggest that the frequent expansions of chemoreceptors have facilitated the transition to eusociality. Divergent expression patterns of odorant receptors between honeybee and ants further indicate differential roles of chemoreceptors in parallel trajectories of social evolution
Chemosensory sensitivity reflects reproductive status in the ant Harpegnathos saltator.
Insects communicate with pheromones using sensitive antennal sensilla. Although trace amounts of pheromones can be detected by many insects, context-dependent increased costs of high sensitivity might lead to plasticity in sensillum responsiveness. We have functionally characterized basiconic sensilla of the ant Harpegnathos saltator for responses to general odors in comparison to cuticular hydrocarbons which can act as fertility signals emitted by the principal reproductive(s) of a colony to inhibit reproduction by worker colony members. When released from inhibition workers may become reproductive gamergates. We observed plasticity in olfactory sensitivity after transition to reproductive status with significant reductions in electrophysiological responses to several long-chained cuticular hydrocarbons. Although gamergates lived on average five times longer than non-reproductive workers, the shift to reproductive status rather than age differences matched the pattern of changes in olfactory sensitivity. Decreasing sensillum responsiveness to cuticular hydrocarbons could potentially reduce mutually inhibitory or self-inhibitory effects on gamergate reproduction
Two-loop Integrability of Planar N=6 Superconformal Chern-Simons Theory
Bethe ansatz equations have been proposed for the asymptotic spectral problem
of AdS_4/CFT_3. This proposal assumes integrability, but the previous
verification of weak-coupling integrability covered only the su(4) sector of
the ABJM gauge theory. Here we derive the complete planar two-loop dilatation
generator of N=6 superconformal Chern-Simons theory from osp(6|4)
superconformal symmetry. For the osp(4|2) sector, we prove integrability
through a Yangian construction. We argue that integrability extends to the full
planar two-loop dilatation generator, confirming the applicability of the Bethe
equations at weak coupling. Further confirmation follows from an analytic
computation of the two-loop twist-one spectrum.Comment: 45 pages, v2: typos in (D.9) fixed, reference added, many small
change
The Complete One-Loop Dilation Operator of N=2 SuperConformal QCD
We evaluate the full planar one-loop dilation operator of N=2 SuperConformal
QCD, the SU(N_c) super Yang-Mills theory with N_f = 2 N_c fundamental
hypermultiplets, in the flavor-singlet sector. Remarkably, the spin-chain
Hamiltonian turns out to be completely fixed by superconformal symmetry, as in
N=4 SYM. We present a more general calculation, for the superconformal quiver
theory with SU(N_c)X SU(N_c) gauge group, which interpolates between N=2 SCQCD
and the Z_2 orbifold of N=4 SYM; here symmetry fixes the Hamiltonian up to a
single parameter, corresponding to the ratio of the two marginal gauge
couplings.Comment: v2: typo corrected, cosmetic changes. JHEP versio
On Symmetry Enhancement in the psu(1,1|2) Sector of N=4 SYM
Strong evidence indicates that the spectrum of planar anomalous dimensions of
N=4 super Yang-Mills theory is given asymptotically by Bethe equations. A
curious observation is that the Bethe equations for the psu(1,1|2) subsector
lead to very large degeneracies of 2^M multiplets, which apparently do not
follow from conventional integrable structures. In this article, we explain
such degeneracies by constructing suitable conserved nonlocal generators acting
on the spin chain. We propose that they generate a subalgebra of the loop
algebra for the su(2) automorphism of psu(1,1|2). Then the degenerate
multiplets of size 2^M transform in irreducible tensor products of M
two-dimensional evaluation representations of the loop algebra.Comment: 35 pages, v2: references added, sign inconsistency resolved in
(5.5,5.6), v3: Section 3.4 on Hamiltonian added, minor improvements, to
appear in JHE
Роль органічних речовин води Нафтуся у її фізіологічній активності
В экспериментах на крысах, а также ex vivo, используя воду Нафтуся из различных скважин и в разные периоды ее мониторинга, а также выделенные из Нафтуси ее гидрофобные и гидрофильные органические вещества, выявлено 5 различающихся между собой кластеров физиологических эффектов, обусловленных количественными и качественными различиями органической компоненты Нафтуси.In experiments on rats, and also ex vivo, using water Naftussya from various chinks and in the different periods of her monitoring, and also allocated from Naftussya her hydrophobic and hydrophyle organic substances, is revealed 5 differing among themselves clusters of physiological effects caused by quantitative and qualitative distinctions organic components Naftussya
From Scattering Amplitudes to the Dilatation Generator in N=4 SYM
The complete spin chain representation of the planar N=4 SYM dilatation
generator has long been known at one loop, where it involves leading
nearest-neighbor 2 -> 2 interactions. In this work we use superconformal
symmetry to derive the unique solution for the leading L -> 2 interactions of
the planar dilatation generator for arbitrarily large L. We then propose that
these interactions are given by the scattering operator that has N=4 SYM
tree-level scattering amplitudes as matrix elements. We provide compelling
evidence for this proposal, including explicit checks for L=2,3 and a proof of
consistency with superconformal symmetry.Comment: 39 pages, v2: reference added and minor changes, published versio
The period gene encodes a predominantly nuclear protein in adult Drosophila
The period gene of Drosophila melanogaster (per) is important for the generation and maintenance of biological rhythms. Previous light microscopic observations indicated that per is expressed in a variety of tissues and cell types and suggested that the per protein (PER) may be present in different subcellular compartments. To understand how PER influences circadian rhythms, it is important to define its subcellular location, especially in adult flies where inducible promoter experiments suggested that it is most relevant to circadian locomotor activity rhythms. To this end, we report the results of an immunoelectron microscopic analysis of wild-type flies and per-beta- galactosidase (beta-gal) fusion gene transgenics using a polyclonal anti-PER antibody or an anti-beta-gal antibody, respectively. Most of the PER antigen and the fusion gene product were located within nuclei, suggesting that PER acts in that subcellular compartment to affect circadian rhythms. The results are discussed in terms of per's possible biochemical functions
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