Biology subjects

Rohilla, P.

Publications and source records attributed to Rohilla, P..

11 recordsLinked to original sources

bioRxiv2026

Viscoelastic liquid lassos extend the defensive reach of termite soldiers

Small animals face a severe size asymmetry when defending themselves against larger predators. Soldiers of Nasutitermes termites overcome this constraint by ejecting tens of nanoliters of secretion through a cephalic nozzle, the nasus. High-speed imaging in the field, rheometry, micro-CT, flow simulation, behavioral assays, and scaled experiments reveal a multistage defense. A near-linear nasus and shear-thinning secretion support rapid ejection. Lateral head oscillation at 5-30 Hz couples with rope-coiling instability to distribute the filament as loops and meanders, a ``liquid lasso,'' reaching up to three body lengths. After deposition, the apparent extensional viscosity increases 8- 80-fold, delaying breakup as the secretion cures into a persistent adhesive. The lasso coats the sensory and grooming structures of predatory ants, and tethers them to the substrate. Synthetic experiments show that nozzle geometry, orientation, height, and oscillatory motion jointly control ejection and coverage, providing design principles for deploying small volumes of time-evolving viscoelastic materials.

biophysics↗

bioRxiv2026

Male Age and Sexual Maturity: Lipopolysaccharide-induced tumor necrosis factor influences sperm quality and reproduction in Anopheles culicifacies

Elucidating the biological and molecular mechanisms that govern male fertility and mating behavior in mosquitoes is critical for optimizing genetic and sterile insect technique-based vector control strategies. Here, we examined age-related changes in male reproductive capacity in Anopheles culicifacies, using female egg output as an indirect indicator of male fertility. Our results demonstrated that male reproductive age follows a non-linear pattern of fertility. Morphometric analysis from emergence to day 13 post-eclosion revealed a strong correlation between seminal vesicle capacity and female fecundity, suggesting that age-dependent gonadal development directly influences reproductive potential. At the molecular level, we identified AcLITAF6 as a key regulator of male reproductive homeostasis. RNAi-mediated knockdown of AcLITAF6 impaired apoptosis-associated and phagocytic clearance, reduced sperm viability, and decreased female productive outcomes. Conclusively, we reveal a previously unrecognized role of LITAF in sperm quality control and male reproductive fitness, highlighting AcLITAF6 as a potential target for mosquito population suppression strategies.

developmental biology↗

bioRxiv2025

Sensory Appendage Protein triggers alarm to pyrethroid in Indian malarial vector Anopheles culicifacies

Sensory appendage proteins (SAPs) serve as molecular arms of odorant-binding protein family members and mediate chemical communication from the external to the internal environment of the insect body. We recently reported that SAP members might have an important role in blood-feeding and/or insecticide resistance-associated behavioral physiologies, but the mechanism remains unclear. Here we show how SAP contributes (i) to the host attraction during navigation for blood-feeding, and (ii) triggers an alert via integrated actions of eyes and peripheral sensory organs to circumvent the toxic effect of insecticide in the susceptible strain of An. culicifacies. Among the six identified SAP members, AcSAP1 and AcSAP2 are abundantly expressed in the olfactory and legs, and their expression is significantly modulated at night in naive adult female mosquitoes. We noticed that AcSAP1 silencing significantly impairs the host-attraction properties of the mosquitoes. Its strong binding affinity to the synthetic pyrethroid prompted us to evaluate the AcSAP1 response to insecticide exposure. Confocal microscopy and molecular profiling data reveal a heightened modulation in the expression of AcSAP1 in eyes, and other peripheral sensory organs including the olfactory (****p<0.00001), legs (**p < 0.004), wings (***p < 0.0004). These findings collectively suggest a crucial role of AcSAP1 in facilitating mosquito navigation, and/or insecticide avoidance. Unraveling the basis of SAP interactions with peripheral sensory systems could pave the way for the development of novel vector control tools.

animal behavior and cognition↗

bioRxiv2024

Mastering the Manu - How humans create large splashes

Manu jumping, a popular water diving style amongst M[a]ori people in New Zealand, focuses on creating large splashes. Divers perform aerial maneuvers such as the "utkatasana" pose, entering the water in a V-shape, and executing underwater maneuvers to maximize the splash size. Our study explores the underlying fluid dynamics of Manu jumping and demonstrates how two key parameters, the V-angle and the timing of body opening, can maximize the Worthington jet formation. To accurately replicate human manu jumping, we studied water entry of both passive solid objects with varying V angles and an active body opening robot (Manubot). The analysis revealed that a 45-degree V angle is optimal for maximizing Worthington jet formation, consistent with human diving data. This angle balances a large cavity size and a deep pinch-off depth. The body opening within a timing window of [Formula] synchronizes the robots potential energies to be timely transferred to the cavity formation, producing the strongest and most vertical, i.e., ideal, Worthington jets. Based on our experimental findings, we propose optimal parameters for generating the largest Manu splashes. These insights offer engineering perspectives on how to modulate underwater cavity dynamics using both passive and active body formations.

biophysics↗

bioRxiv2024

TSSK homologue regulates the expression of protamine and mosquito testes specific genes in Anopheles stephensi

The testis-specific serine/threonine-protein kinase (tssk) gene is known to play an important role in spermiogenesis in mammals. This study identifies tssk homologues, As_tssk3 and Aea_tssk1 in Anopheles stephensi and Aedes aegypti, respectively. Both As_tssk3 and Aea_tssk1 were found to express in a male-specific manner throughout the development. Efficient knockdown in the expression of As_tssk3 gene was observed upon feeding An. stephensi larvae with target dsRNA. As_tssk3 knockdown led to a reduced sperm reservoir in male adults. Additionally, the knockdown of As_tssk3 resulted in the reduced expression of two male specifically expressed genes, protamine & mosquito testes specific (mts- a sperm-specific marker) homologues of An. stephensi. In-silico interaction analysis suggests that As_TSSK3 protein interacts with the Nucleosome Assembly Protein1 like-4 (NAP1like-4), a putative transcription factor. We hypothesize that As_TSSK3 regulates the transcription of protamine and mts genes via NAP, as both NAP and protamine have previously been shown to function in the establishment and maintenance of chromatin dynamics, in independent studies. The study presented here is the first report of characterisation of tssk homologues in any mosquito species. The knockout studies and phosphorylation assays would provide more insights to explore the mechanism by which As_tssk3 regulates protamine and mts genes in Anopheles stephensi. HighlightsO_LIThis study identifies the tssk homologues in Ae. aegypti and An. stephensi and showed their male-specific expression in both the mosquito species. C_LIO_LIdsRNA mediated knockdown of As_TSSK3 resulted into the males with a reduced size of sperm reservoir. C_LIO_LIdsRNA mediated knockdown of As_TSSK3 led to the reduction in the expression of As_prot and As_mts, homologues of protamine and mosquito testis specific, genes in An. stephensi. C_LIO_LIIn-silico studies suggest that As_TSSK3 regulates the expression of As_prot and As_mts genes via NAP. C_LI

genetics↗

bioRxiv2024

Epineuston vortex recapture enhances thrust in tiny water skaters

Vortex recapture underpins the exceptional mobility of natures finest fliers and swimmers. Utilized by agile fruit flies and efficient jellyfish, this phenomenon is well-documented in bulk fluids. Despite extensive studies on organismal locomotion at the waters surface, a vital fluidic interface where diverse life forms interact, hydrodynamics of interfacial vortex recapture remains unexplored. We investigate interfacial (on water) vortical hydrodynamics in Microvelia americana, one of the smallest and fastest water striders, skating at 50 body lengths per second (BL/s) or 15 cm/s. Their middle legs shed counter-rotating vortices, re-energized by their hind legs, demonstrating interfacial vortex recapture. High-speed imaging, particle imaging velocimetry, physical models, and CFD simulations show re-energization increases thrust by creating positive pressure at the hind tarsi, acting as a virtual wall. This vortex capture is facilitated by the tripod gait, leg morphology, and precise spatio-temporal placement of the hind tarsi during the power stroke. Our study extends vortex recapture principles from bulk fluids to the interface, offering insights into efficient interfacial locomotion, where surface tension and capillary waves challenge movement. Understanding interfacial vortex hydrodynamics can guide the development of energy-efficient microrobots to explore the planets water surface niches, critical frontlines of climate change and pollution. Significance StatementInterfacial Vortex Recapture in Microvelia americana extends the vortex recapture principles to the air-water interface, revealing an efficient locomotory mode in a challenging ecological niche. By demonstrating thrust enhancement through precise vortex interactions, our study bridges biology and fluid dynamics. This discovery informs the design of energy-efficient amphibious microrobots, capable of navigating the water interface with a new tripod gait paradigm, diverging from the conventional drag-based rowing designs. These findings are foundational for exploring and monitoring the water surface, an ecological interface vital for addressing climate change and pollution impacts.

biophysics↗

bioRxiv2024

Molecular basis for plasma membrane recruitment of PI4KA by EFR3

The lipid kinase phosphatidylinositol 4 kinase III alpha (PI4KIII/PI4KA) is a master regulator of the lipid composition and asymmetry of the plasma membrane. PI4KA exists primarily in a heterotrimeric complex with its regulatory proteins TTC7 and FAM126. Fundamental to PI4KA activity is its targeted recruitment to the plasma membrane by the lipidated proteins EFR3A and EFR3B. Here, we report a cryo-EM structure of the C-terminus of EFR3A bound to the PI4KA-TTC7B-FAM126A complex, with extensive validation using both hydrogen deuterium exchange mass spectrometry (HDX-MS), and mutational analysis. The EFR3A C-terminus undergoes a disorder-order transition upon binding to the PI4KA complex, with an unexpected direct interaction with both TTC7B and FAM126A. Complex disrupting mutations in TTC7B, FAM126A, and EFR3 decrease PI4KA recruitment to the plasma membrane. Multiple post-translational modifications and disease linked mutations map to this site, providing insight into how PI4KA membrane recruitment can be regulated and disrupted in human disease. One sentence summaryThe cryo-EM structure of the C-terminus of EFR3A bound to the PI4KA complex reveals the molecular mechanism underlying PI4KA membrane localisation, and provides novel insight into PI4KA regulation and its involvement in human disease.

biochemistry↗

bioRxiv2024

Limb loss and specialized leg dynamics in tiny water-walking insects

The air-water of the planets water bodies, such as ponds, lakes and streams, presents an uncertain ecological niche with predatory threats from above and below. As Microvelia move across the water surface in small ponds, they face potential injury from attacks by birds, fish, and underwater invertebrates. Thus, our study investigates the effects of losing individual or pairs of tarsi on the Microvelias ability to walk on water. Removal of both hind tarsi causes Microvelia spp. to rock their bodies (yaw) while running across the water surface at {+/-}19{degrees}, compared to {+/-}7{degrees} in non-ablated specimens. This increase in yaw, resulting from the removal of hind tarsi, indicates that Microvelia use their hind legs as rudders to regulate yaw, originating from the contralateral middle legs strokes on the waters surface through an alternating tripod gait. Ablation of the ipsilateral middle and hind tarsi disrupts directionality, making Microvelia turn in the direction of their intact limbs. This loss of directionality does not occur with the removal of contralateral middle and hind tarsi. However, Microvelia lose their ability to use the alternating tripod gait to walk for water walking on the day of contralateral ablation. Remarkably, by the next day Microvelia adapt and regain the ability to walk on water using the alternating tripod gait. Our findings elucidate the specialized leg dynamics within the alternating tripod gait of Microvelia spp., and their adaptability to tarsal loss. This research could guide the development and design strategies of small, adaptive, and resilient micro-robots that can adapt to controller malfunction or actuator damage for walking on water and terrestrial surfaces.

animal behavior and cognition↗

bioRxiv2021

Effect of air pockets in drug delivery in jet injections

Needle-free jet injections are actuated by a pressure impulse that can be delivered by different mechanisms, and the resultant jets are [Formula](102) m/s. Here, we report on the effect of entrapped air bubbles since filling procedures for pre-filled ampoules can induce bubbles, especially for viscous fluids. We use spring-piston devices as the principal actuation mechanism and vary both the location and size of the initial bubble. We find that the bubble location does have a statistically significant (p < 0.05) effect on the jet exit speed, based upon the volumetric flow rate. However, we reveal subtle features such as intermittent atomization when the gas pockets pass through the orifice and de-pressurize, which leads to spray formation and a temporary increase in jet dispersion, both of which can lead to product loss during an injection. These results have implications for the development of prefilled ampoules for jet injection applications.

bioengineering↗

bioRxiv2021

Drug delivery via tattooing: Effect of needle and fluid properties

Tattooing is a commonplace practice among the general populace in which ink is deposited within dermal tissue. Typically, an array of needles punctures the skin which facilitates the delivery of a fluid within the dermis. Although, a few studies in the past have investigated the potential of tattooing as an intradermal (ID) drug injection technique, an understanding of the fluid dynamics involved in the delivery of fluid into skin is still lacking. Herein, we sought to provide insight into the process via an in vitro study. We utilize a five needle flat array (5F) with a tattoo machine to inject fluids into gelatin gels. High-speed imaging was used to visualize the injection process and estimate the amount of fluid delive red after each injection upto the 50th injection. We investigate the role of reciprocating frequency (f) of the needle array and the physical properties of the fluids on the volume (Vo) and the percentage delivery ({eta}) after injection. In addition, we illustrate the physical mechanism of fluid infusion during tattooing, which has not been reported. An understanding of the injection process via tattooing can be useful in the development of ID tattoo injectors as drug delivery devices.

bioengineering↗

bioRxiv2019

Loading effects on the performance of needle free jet injections in different skin models

Intradermal delivery of vaccines with jet injection is one of the leading alternatives to conventional delivery with hypodermic needles via the Mantoux technique. However, for a given fluid, the effects of various parameters related to injector design, as well as skin properties are still not well understood. Whilst the key design parameters are orifice diameter, jet speed, ampoule volume, and standoff distances, we must also consider applied load of the device on the skin, and axial skin tension. These parameters are all studied herein using different ex-vivo models (guinea pig, pig and human skin) and different fluid viscosities. We find that the applied load can have a significant effect on the amount of drug delivered through the skin, as well as the fluid dispersion pattern in the intradermal tissues. Regardless of skin type or fluid viscosity, we show that minimal standoff and applied loads of approximately 1 kg should be used to maximize injection efficiency when targeting intradermal tissue.

bioengineering↗