1,582 research outputs found
The Modified Pharaoh Approach: Stingless bees mummify beetle parasites alive
Social insect colonies usually live in nests, which are often invaded by parasitic species^1^. Workers from these colonies use different defence strategies to combat invaders^1^. Nevertheless, some parasitic species are able to bypass primary colony defences due to their morphology and behaviour^1-3^. In particular, some beetle nest invaders cannot be killed or removed by workers of social bees^2-5^, thus creating the need for alternative social defence strategies to ensure colony survival. Here we show, using Diagnostic Radioentomology^6^, that stingless bee workers _Trigona carbonaria_, immediately mummify invading destructive nest parasites _Aethina tumida_ alive, with a mixture of resin, wax and mud, thereby preventing severe damage to the colony. In sharp contrast to the responses of honeybee^7^ and bumblebee colonies^8^, the rapid live mummification strategy of _T. carbonaria_ effectively prevents beetle parasite advancements and removes their ability to reproduce. The convergent evolution of live mummification by stingless bees and social encapsulation by honeybees^3^ suggests that colonies of social bees generally rely on, secondary defence mechanisms when harmful nest intruders cannot be killed or ejected easily. This process is analogous to immune responses in animals
Ingestion of amniotic fluid enhances the facilitative effect of VTA morphine on the onset of maternal behavior in virgin rats
Previous research has shown that injection of morphine into the ventral tegmental area(VTA) facilitates the onset of maternal behavior in virgin female rats, and injection of the opioid antagonist naltrexone into the VTA disrupts the onset of maternal behavior in parturient rats. Placentophagia – ingestion of placenta and amniotic fluid, usually at parturition – modifies central opioid processes. Ingestion of the active substance in placenta and amniotic fluid, Placental Opioid-Enhancing Factor (POEF), enhances the hypoalgesic effect of centrally administered morphine, and more specifically, enhances δ- and κ-opioid-receptor-\ud
mediated hypoalgesia and attenuates μ-opioid-receptor-mediated hypoalgesia. POEF (in placenta or amniotic fluid) ingestion does not, by itself, produce hypoalgesia. In the\ud
present study, we tested the hypothesis that ingestion of amniotic fluid enhances the facilitative effect of opioid activity (unilateral morphine injection) in the VTA on the rate of onset of maternal behavior. Virgin female Long-Evans rats were given one intra-VTA injection of morphine sulfate (0.0, 0.01, or 0.03 μg, in saline) and an orogastric infusion of 0.25 ml amniotic fluid or saline once each day of the first three days of the 10-day testing\ud
period. Subjects were continuously exposed to foster pups that were replaced every 12 h; replacement of pups was followed by a 15-min observation period. Maternal behavior\ud
latency was determined by the first of two consecutive tests wherein the subject displayed pup retrieval, pup licking in the nest, and crouching over all foster pups, during the 15-min observation. We confirmed the previous finding that the VTA injection, alone, of 0.03 μg morphine shortened the latency to show maternal behavior and that 0.0 μg and 0.01 μg morphine did not. Ingestion of amniotic fluid (and therefore POEF) facilitated the onset of\ud
maternal behavior in rats receiving an intra-VTA microinjection of an otherwise subthreshold dose of morphine (0.01 μg)
Drag-n-fly: a Proposal in Response to a Low Reynolds Number Station Keeping Mission
The Drag-n-Fly is a remotely piloted, low Reynolds number vehicle. It was designed to maintain level controlled flight and fly a closed course at flight speeds corresponding to Reynolds numbers of less than 2 x 10(exp 5) and as close to 1 x 10(exp 5) as possible. The success of the mission will be associated with achieving the lowest mean chord Reynolds number possible and maximizing loiter time on the course. The flight plan for the Drag-n-Fly calls for the vehicle to ascent to a cruise altitude of 25 ft. The airfoil selected for the Drag-n-Fly is a Spica chosen for its high lift coefficient at low Reynolds number. The propulsion system for the Drag-n-Fly consists of a 10 inch diameter propeller mounted on the front of the vehicle. Structural support for the Drag-n-Fly comes from four box beams running the length of the fuselage. The tail and horizontal stabilizers are located far aft of the lifting surface in order to assure proper static stability. The present design for the Drag-n-Fly will meet the criteria for the present mission
Associations between psychopathy and the trait meta-mood scale in incarcerated males:A combined latent variable- and person-centered approach
The present study sought to replicate and extend current knowledge on the relevance of emotion regulation (ER) for psychopathy. In a large sample of incarcerated adult males (N = 578), latent profile analysis (LPA) and structural equation modeling (SEM) were employed to examine person- and variable-centered associations between self-reported ER and both self-report and clinical ratings of psychopathy. With LPA, participants were classified into three profiles corresponding to low, medium, and high ER. The low-ER profile displayed higher affective traits across psychopathy assessments compared with the other profiles. The same pattern of findings was evident for overt behavioral features of psychopathy, but not for interpersonal traits. SEM results were consistent with LPA findings: interpersonal (positively), affective, and lifestyle (negatively) facets had unique associations with a superordinate ER latent variable. Findings replicate and extend prior associations between psychopathy and ER and suggest differential links between ER and affective and interpersonal traits of psychopathy
A novel and ancient group of type I keratins with members in bichir, sturgeon and gar
<p>Abstract</p> <p>1. Background</p> <p>Vertebrate epithelial cells typically express a specific set of keratins. In teleosts, keratins are also present in a variety of mesenchymal cells, which usually express vimentin. Significantly, our previous studies revealed that virtually all known teleost keratins evolved independently from those present in terrestrial vertebrates. To further elucidate the evolutionary scenario that led to the large variety of keratins and their complex expression patterns in present day teleosts, we have investigated their presence in bichir, sturgeon and gar.</p> <p>2. Results</p> <p>We have discovered a novel group of type I keratins with members in all three of these ancient ray-finned fish, but apparently no counterparts are present in any other vertebrate class so far investigated, including the modern teleost fish. From sturgeon and gar we sequenced one and from bichir two members of this novel keratin group. By complementary keratin blot-binding assays and peptide mass fingerprinting using MALDI-TOF mass spectrometry, in sturgeon we were able to assign the sequence to a prominent protein spot, present exclusively in a two-dimensionally separated cytoskeletal preparation of skin, thus identifying it as an epidermally expressed type I keratin. In contrast to the other keratins we have so far sequenced from bichir, sturgeon and gar, these new sequences occupy a rather basal position within the phylogenetic tree of type I keratins, in a close vicinity to the keratins we previously cloned from river lamprey.</p> <p>3. Conclusion</p> <p>Thus, this new K14 group seem to belong to a very ancient keratin branch, whose functional role has still to be further elucidated. Furthermore, the exclusive presence of this keratin group in bichir, sturgeon and gar points to the close phylogenetic relationship of these ray- finned fish, an issue still under debate among taxonomists.</p
Locating the LCROSS Impact Craters
The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted
a spent Centaur rocket stage into a permanently shadowed region near the lunar
south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact
and performed a small braking maneuver in order to observe the Centaur impact
plume, looking for evidence of water and other volatiles, before impacting
itself. This paper describes the registration of imagery of the LCROSS impact
region from the mid- and near-infrared cameras onboard the SSC, as well as from
the Goldstone radar. We compare the Centaur impact features, positively
identified in the first two, and with a consistent feature in the third, which
are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta
region. The images are registered to Lunar Reconnaisance Orbiter (LRO)
topographical data which allows determination of the impact location. This
location is compared with the impact location derived from ground-based
tracking and propagation of the spacecraft's trajectory and with locations
derived from two hybrid imagery/trajectory methods. The four methods give a
weighted average Centaur impact location of -84.6796\circ, -48.7093\circ, with
a 1{\sigma} un- certainty of 115 m along latitude, and 44 m along longitude,
just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC
impact location is -84.719\circ, -49.61\circ, with a 1{\sigma} uncertainty of 3
m along the Earth vector and 75 m orthogonal to that, 766 m from the target
location and 2.803 km south-west of the Centaur impact. We also detail the
Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS
mission requirements are shown to be met by wide margins. We hope that these
results facilitate further analyses of the LCROSS experiment data and follow-up
observations of the impact region.Comment: Accepted for publication in Space Science Review. 24 pages, 9 figure
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