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•The mechanism by which bitter gourd repels insects is poorly known.•Drosophila – model to understand the neurophysiology of aversion to phyto-extracts.•Bitter gourd extract affects ...viability of developing flies, but not adults.•Bitter gourd extract – antifeedant sensed through bitter sensitive taste neurons.•Bitter gourd extract reinforces aversive memory (retained even after 24 h).
Bitter gourd (Momordica charantia L.) has compounds that repel insect pests. Unlike conventional pesticides, these compounds are eco-friendly and beneficial for human health. However the mechanisms by which these compounds repel insects and affect their physiology remains poorly known. Here we used Drosophila melanogaster (Meigen) to address these issues. We tested a wild strain, and a laboratory bred Canton S strain. Bitter gourd extract reduced the viability of developing flies, but did not affect survival in adults. Flies avoided bitter gourd extract in a food choice assay, and consumed a significantly low amount of food mixed with bitter gourd – indicating that it acts as an antifeedant. Transgenic flies with impaired aversive taste sensitive neurons showed a reduced aversion towards bitter gourd extract showing that these compounds act through the bitter sensitive gustatory neurons. Finally, flies also retained the memory of consuming bitter gourd extract for at least 24 hours, suggesting an additional cognitive mechanism for long term aversion. Our study provides the first evidence of bitter gourd compounds acting as antifeedants and also as potent reinforcers of aversive memory in drosophilids. We suggest that flies can be used to understand the physiological and neural mechanisms underlying the mode of action of other such phyto-extracts with the goal of developing potent but less harmful pest control formulations.
Eusocial Hymenoptera colonies are characterized by the presence of altruistic individuals, which rear their siblings instead of their own offspring. In the course of evolution, such sterile castes ...are thought to have emerged through the process of kin selection, altruistic traits being transmitted to following generation if they benefit relatives. By allowing kinship recognition, the detection of cuticular hydrocarbons (CHCs) might be instrumental for kin selection. In carpenter ants, a female-specific olfactory subsystem processes CHC information through antennal detection by basiconic sensilla. It is still unclear if other families of eusocial Hymenoptera use the same subsystem for sensing CHCs. Here, we examined the existence of such a subsystem in Vespidae (using the hornet
), a family in which eusociality emerged independently of ants. The antennae of both males and female hornets contain large basiconic sensilla. Sensory neurons from the large basiconic sensilla exclusively project to a conspicuous cluster of small glomeruli in the antennal lobe, with anatomical and immunoreactive features that are strikingly similar to those of the ant CHC-sensitive subsystem. Extracellular electrophysiological recordings further show that sensory neurons within hornet basiconic sensilla preferentially respond to CHCs. Although this subsystem is not female-specific in hornets, the observed similarities with the olfactory system of ants are striking. They suggest that the basiconic sensilla subsystem could be an ancestral trait, which may have played a key role in the advent of eusociality in these hymenopteran families by allowing kin recognition and the production of altruistic behaviors toward relatives.
Queens and workers are not morphologically differentiated in the primitively eusocial wasp, Ropalidia marginata. Upon removal of the queen, one of the workers becomes extremely aggressive, but ...immediately drops her aggression if the queen is returned. If the queen is not returned, this hyper-aggressive individual, the potential queen (PQ), will develop her ovaries, lose her hyper-aggression, and become the next colony queen. Because of the non-aggressive nature of the queen, and because the PQ loses her aggression by the time she starts laying eggs, we hypothesized that regulation of worker reproduction in R. marginata is mediated by pheromones rather than by physical aggression. Based on the immediate loss of aggression by the PQ upon return of the queen, we developed a bioassay to test whether the queen's Dufour's gland is, at least, one of the sources of the queen pheromone. Macerates of the queen's Dufour's gland, but not that of the worker's Dufour's gland, mimic the queen in making the PQ decrease her aggression. We also correctly distinguished queens and workers of R. marginata nests by a discriminant function analysis based on the chemical composition of their respective Dufour's glands.
There is currently no accurate data on fracture displacement during the rehabilitation of pelvic ring injuries. This study investigated the use of radiostereometric analysis (RSA) in assessing the ...stability of C1 pelvic ring injuries stabilised with a posterior plate and an anterior external fixator. Six patients, instructed to weight-bear as tolerated after surgery, were reviewed at 2, 4, 6, 12, 26, 52 and 104 weeks. The external fixators were removed at 6 weeks. Outcomes, including the Iowa Pelvic Score (IPS), and complications were recorded. Fracture stability was assessed using measurements on plain radiographs and RSA. All patients progressed to full weight-bearing without support within 6 weeks. At 104 weeks, the IPS was excellent in four patients, good in one patient and fair in one patient. Plain radiographs showed that all fractures were well reduced, and no loss of reduction occurred over time. By contrast, RSA measurements identified displacement in all cases. The maximum three-dimensional (3D) displacement at any time point in each patient ranged from 2 to 10 mm. Two patients with the largest displacement over time had the lowest IPS. RSA also demonstrated displacements above the currently defined normal threshold through the ‘un-injured’ sacroiliac joint in the same two patients, suggesting a subtle C2 injury, missed at initial assessment. This study demonstrates the limitations of plain radiographs in assessing pelvic fracture stability and displacement during healing, and the potential of RSA to monitor more accurately the effects of stabilisation and weight-bearing on fracture stability.
Metamorphosis in insects is a remarkable phenomenon where the larva undergoes a striking morphological reorganization to give rise to the adult. Over the years, various physiological factors and ...pathways that govern metamorphosis have been discovered, and at the same time, some understanding about the origins of this phenomenon has also emerged. This review summarizes the current state of knowledge of both the mechanisms underlying metamorphosis, as well as the theories put forward to explain its evolution.
•We investigate the impact of remittances on women’s acceptance of domestic violence (DV) using data from Punjab, Pakistan.•Women in remittance-receiving households accept DV 5.5-7 percentage points ...less than women in non-remittance households.•The result is robust to disaggregating remittances by source, though international remittances have a greater impact.•However, the causal impact of remittances is sensitive to the context for DV.
There is an emerging interdisciplinary literature that explores the transformation of prevailing gender norms as communities experience emigration and associated inflows of remittances. This paper focuses on a key gender norm, namely, women’s perception of experiencing domestic violence. Specifically, we investigate the impact of household access to remittance income on attitudes held by women in the household regarding the acceptability of domestic violence. Using data from a Multiple Indicators Cluster Survey conducted in the Punjab province of Pakistan in 2014, we isolate the causal impact of remittance income by employing a matching estimator to construct counterfactuals that allow us to compare women from otherwise identical households who differ solely in their access to remittances. Our results indicate that women in households with access to remittances are less likely to accept domestic violence than women in comparable households without remittance income, though there is considerable heterogeneity once we differentiate between different contexts for DV. Interestingly, the result persists even when we distinguish between transnational and domestic remittances, access to either type of transfer reducing the acceptance of domestic violence by comparable magnitudes. This suggests the operation of mechanisms other than the transnational diffusion of gender norms that has typically been emphasized in the literature.
Cellulose acetate (CA) fibers were reinforced with multi-walled carbon nanotubes (MWCNTs) at 0.5%, 1.0%, 1.5% and 2.0%. Yield strength, ultimate tensile strength, fracture strain and toughness of the ...nanocomposite fiber increased up to 1.5 wt. % of the carbon nanotube (CNT) loading, however, further inclusion (2.0%) of MWCNTs in CA decreased the mechanical properties. Experimental properties were also compared with analytical predictions using a Shear lag model for strength and the rule of mixture for modulus. A solution spinning process, coupled with sonication, mixing, and extrusion, was used to process the CNT-reinforced composite fiber. Scanning electron microscopy (SEM) images of the cross sections of neat CA and CA-MWCNT fibers showed the formation of voids and irregular features. The enhanced interconnected fibrillation in the CNT-reinforced CA samples resulted in improved mechanical properties, which were observed by tensile testing. Fourier transform infrared spectroscopy (FTIR) spectra showed the area under the curve for C–H bonding after the inclusion of CNT. There was no significant shift of wavenumber for the inclusion of MWCNT in the CA matrix, which indicates that the sonication process of the CNT-loaded solution did not degrade the CA bonding structure.
The availability of protein is an important factor for the determination of the size of the mitotic spindle. Involved in spindle-size regulation is kinesin-8, a molecular motor and microtubule (MT) ...depolymerase, which is known to tightly control MT length. Here, we propose and analyze a theoretical model in which kinesin-induced MT depolymerization competes with spontaneous polymerization while supplies of both tubulin and kinesin are limited. In contrast to previous studies where resources were unconstrained, we find that, for a wide range of concentrations, MT length regulation is bistable. We test our predictions by conducting in vitro experiments and find that the bistable behavior manifests in a bimodal MT length distribution.
During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and ...maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.
Synopsis
Kinesin motors are involved in organizing the mitotic spindle by cross-linking and sliding microtubules. This work shows that the sideways stepping of human kinesin-5, KIF11, causes helical motion of anti-parallel microtubules and orbiting motion of parallel microtubules.
KIF11 drives a right-handed helical motion of short microtubules around long, suspended microtubules in anti-parallel overlaps.
The microtubule-microtubule distance (i.e., motor extension) decreases with increasing sliding velocity.
KIF11 drives an orbiting motion of parallel microtubules at nearly full motor extension.
Altering the length of the KIF11 neck linker increases forward velocity and pitch of microtubules in anti-parallel overlaps.
Sideways stepping of human KIF11 causes helical and orbiting motions of microtubules that may contribute to flexible filament formation and mitotic spindle torque regulation.
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