Biology subjects

Desai, C.

Publications and source records attributed to Desai, C..

5 recordsLinked to original sources

bioRxiv2026

Social ties are maintained through sensory adaptations in green chromides

Sensory systems exhibit considerable plasticity in response to environmental changes, yet the functional implications of such plasticity remain poorly understood, particularly regarding how changes in visual gene expression influence social behaviour. To address this gap, we investigated how visual sensory plasticity relates to conspecific preferences in green chromides (Etroplus suratensis), an Indian cichlid that relies on vision for social preferences towards conspecifics. We first characterized retinal opsin and chromophore-related genes through transcriptomic analysis and subsequently examined behavioural and molecular responses under sequential white- and blue-light environments. We quantified visually mediated conspecific preferences, and the expression of rod and cone opsins and the chromophore-related gene Cyp27c1 at regular intervals. Green chromides retained stable conspecific preferences despite contrasting light environments. Opsins exhibited plasticity, with long wavelength-sensitive opsin (LWS) increasing under blue light, whereas short wavelength-sensitive opsins remained unchanged. Additionally, Cyp27c1 expression declined under blue light, suggesting a potential shift towards increased A1 chromophore utilization. Together, these findings suggest that green chromides undergo multiple molecular modifications under contrasting light environments, whereas maintaining stable social behaviours, demonstrating the cross-talk between the two is not straightforward. Overall, these results highlight that unraveling the underlying proximate mechanisms of behavior is highly intricate, involving multiple pathways, starting from perception (at the retinal level) to post-processing of the stimulus.

ecology↗

bioRxiv2025

The Speed Limit of Visual Perception: Bidirectional influence of image memorability and processing speed on perceived duration and memory recall

Visual stimuli are known to vary in their perceived duration, with some stimuli engendering so-called "time dilation" and others "time compression" effects. Previous theories have suggested these effects rely on the level of attention devoted to stimuli, magnitude of the stimulus dimension, or intensity of the population neural response, yet cannot account for the full range of experimental effects. Recently, we demonstrated that perceived time is affected by the image properties of scene clutter, size, and memorability (Ma, et al. 2024), with the former compressing and latter two dilating duration. Further, perceived duration also predicted recall of images 24h later, on top of memorability. To explain the memorability effect, we found that a recurrent convolutional neural network (rCNN) could recapitulate the time dilation effect by indexing the rate of entropy collapse, or "speed", across successive timesteps, with more memorable stimuli associated with faster speeds. Here, we replicate and extend these findings via three experiments (n=20ea.) where subjects performed a sub-second temporal bisection task using memorability stimuli with increasing memorability, but a constant speed (exp 1), increasing speed, but constant memorability (exp 2), or increasing in both (exp 3), each followed by a surprise memory test 24hr later. We found that either increasing memorability or speed alone led to time dilation effects, with faster/slower speeds shifting memory recall by [~]8.4% in either direction. However, when both metrics increased, memorability dilated time while speed compressed it, while still improving recall overall. These findings can be explained by a model wherein the visual system is tuned to a preferred speed for processing stimuli that scales with the magnitude of visual response, such that stimuli closer to this speed are dilated in time. Overall, these findings provide a new lens for interpreting time dilation/compression effects and how visual stimuli are prioritized at temporal scales. Author SummaryRecent work has demonstrated a link between perceived duration and memory recall, with memorable images dilating time, and perceived duration in turn affecting memory. The link between these two can be indexed by the speed at which images are processed in recurrent convolutional neural networks, yet the limits of this link remain untested. Here, we tested three groups on a timing task using three sets of stimuli selected according to both their memorability and speed. We find that when one factor is held constant, both memorability and speed still dilate perceived duration, with speed alone accounting for a shift in memory recall of [~]17%. However, when speeds are raised to their highest limits, perceived duration is instead compressed. An inverted-U shape rule between time dilation and compression over speed that is moderated by memorability explains this effect and suggests the visual system shifts between these modes to both gather more information and conserve energy, respectively.

neuroscience↗

bioRxiv2025

Fission or fusion: shoaling adaptations in green chromides (Etroplus suratensis) across multiple manipulations

Collective behaviour contributes towards increased fitness, however, in fission-fusion societies, the decision to participate in a group is based on cost-benefit ratio derived under a given condition. In todays world, this ratio dramatically changes due to increased challenges in degraded habitats, impacting behavioural decisions towards social grouping. In this paper, we used fish shoal as a unit of collective behaviour, and investigated variations in shoaling adaptations across a range of manipulations, mimicking challenges faced by the species under natural conditions. We used green chromides (Etroplus suratensis), a cichlid fish species, and characterised their shoaling behaviour under laboratory conditions for two group sizes, 4 and 8. We then examined the effects of different manipulations, for example, starvation and reduced space (both mimicking resource constrained conditions), and presence of hetero species including tilapia (Oreochromis sp., an alien species widespread within the habitats of E. suratensis) on their shoaling behaviour. Our results showed that E. suratensis formed shoals in both group sizes, 4 and 8. In subsequent analyses, we used group size 8 as a control and demonstrated that space reduction and starvation significantly impacted shoaling, reducing shoal splits and occurrences of solitary fish, while increasing incidences of single, cohesive shoals comprising all individuals. E. suratensis also formed mixed-species shoals with alien Oreochromis spp., but exhibited a large percentage (in absolute terms) of shoal splits. Overall, E. suratensis exhibited plasticity in their shoaling behaviour, and increased fusion of shoals under challenging conditions, which was in contrast to showing more fission in presence of the alien hetero species.

animal behavior and cognition↗

bioRxiv2021

Effects of active and passive enrichment regimes on fecal glucocorticoid metabolite levels in captive Indian leopards (Panthera pardus fusca)

Environmental enrichment improves health and wellbeing of zoo animals. To test this hypothesis, we used Indian leopards, one of the popular zoo animals, as a model system to understand effects of active (interacting) and passive (noninteracting) enrichment elements on stress hormone levels of captive individuals. We included three enrichment categories, category A (having both active: large size cage, and passive: controlled temperature, playback of forest sounds and sound proof glasses to filter visitors noise, enrichment elements), category B (active enrichment type I, small size cage with air coolers), and category C (active enrichment type II, medium size cage without air coolers) for the leopards (n=14) housed in two Indian zoos. We standardized a non-invasive method to measure fecal glucocorticoid metabolite (fGCM) levels in captive leopards. The standardized fGCM assay was further validated by analysing samples from free-ranging leopards, as well. The fGCM levels (Mean{+/-}SE) were 10.45{+/-}2.01 and 0.95{+/-}0.003g/g dry wt of feces in captive and free-ranging leopards, respectively. Our results demonstrated that fGCM levels of leopards in categories B and C were significantly (P<0.05) different from each other, thus, indicating cage size (an active enrichment element) as an important factor in influencing the physiology of the sampled animals. Overall, the findings of the study will contribute towards informing policies for management of the Indian leopards.

ecology↗

bioRxiv2021

A homeostatic interferon-lambda response to bacterial microbiota stimulates preemptive antiviral defense within discrete pockets of intestinal epithelium

Interferon-lambda (IFN-{lambda}) protects intestinal epithelial cells (IECs) from enteric viruses by inducing expression of antiviral IFN-stimulated genes (ISGs). Here, we find that bacterial microbiota stimulate a homeostatic ISG signature in the intestine of specific pathogen-free mice. This homeostatic ISG expression is restricted to IECs, depends on IEC-intrinsic expression of IFN-{lambda} receptor (Ifnlr1), and is associated with IFN-{lambda} production by leukocytes. Strikingly, imaging of these homeostatic ISGs reveals localization to pockets of the epithelium and concentration in mature IECs. Correspondingly, a minority of mature IECs express these ISGs in public single-cell RNA sequencing datasets from mice and humans. Furthermore, we assessed the ability of orally-administered bacterial components to restore localized ISGs in mice lacking bacterial microbiota. Lastly, we find that IECs lacking Ifnlr1 are hyper-susceptible to initiation of murine rotavirus infection. These observations indicate that bacterial microbiota stimulate ISGs in localized regions of the intestinal epithelium at homeostasis, thereby preemptively activating antiviral defenses in vulnerable IECs to improve host defense against enteric viruses.

immunology↗