Biology subjects

Rajput, N.

Publications and source records attributed to Rajput, N..

5 recordsLinked to original sources

bioRxiv2025

The effects of Arabian jasmine on zebrafish behavior depends on strain, sex, and personality

Jasminum sambac (L.) Aiton, commonly known as Arabian jasmine, is widely used in Thai traditional medicine for mental health ailments. While most studies in humans and animals find that Arabian jasmine reduces stress and anxiety, there are a handful of reports that it can oppose relaxation by increasing autonomic arousal. Using adult zebrafish, we sought to determine whether factors like strain, sex, and personality might contribute to the variable effects of J. sambac on anxiety-related behavior. The flowers of J. sambac were extracted by ultrasonic-assisted extraction with optimal air pressure. Headspace solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS) identified the main components in the Arabian jasmine flower extract, including linalool (an anxiolytic compound) and benzaldehyde. We fed three strains of zebrafish (AB, TL, and WIK) a gelatin pellet containing different concentrations of J. sambac (5-20 mg kg-1) and assessed 3-dimensional swim behavior in the novel tank and mirror biting tests. We found that in female AB fish, J. sambac resulted in a decrease in bottom distance during the novel tank test, consistent with an anxiogenic effect; there was no effect in WIK or TL fish. We also found that behavioral/personality type influenced the effects of J. sambac where shy AB females increased their percent explored, consistent with an anxiolytic effect. Thus, we find that sex, genetics, and personality interact to influence the anxiety-related effects of Arabian jasmine suggesting that these factors may contribute to the opposing effects of Arabian jasmine reported in the literature.

animal behavior and cognition↗

bioRxiv2025

Individual differences in fear memory expression engage distinct functional brain networks

Fearful stimuli elicit a mix of active (e.g., evasion) and passive (e.g., freezing) behaviors in a wide range of species, including zebrafish (Danio rerio). How these different responses are encoded in the brain, and the extent to which individuals vary in their fear responses, is not clear. To investigate this, we first developed a contextual fear conditioning paradigm in adult zebrafish where fish associate a specific tank with an aversive pheromone, conspecific alarm substance (CAS). We collected data from over 300 fish across four different strains (AB, TU, TL, and WIK) and both sexes finding that, as expected, fish exhibit a mix of active and passive responses during CAS exposure and during memory expression. We also found that behavior fell into four distinct groups: non-reactive, evaders, evading freezers, and freezers, with the evading freezer and freezer groups most clearly associated with memory formation. Background strain and sex also influenced how fish respond to CAS, with males more likely to increase evasive behaviors in response to CAS and the TU strain more likely to be non-reactive during recall. Finally, using whole-brain activity mapping, we identified the brain regions associated with active and passive fear responses during memory expression and how the functional brain networks of evading freezers and freezers differed. Freezing behavior was associated with widespread neural activity that was particularly strong in the cerebellum, reticular formation, and parts of the telencephalon associated with olfactory processing. Evasive behavior was associated with an increase in the activity of visual threat detection and a decrease in the activity of brain regions related to foraging and navigation. Network analysis revealed that animals with high freezing and low evasion (i.e., freezers) had strong interactions between the pallium and cerebellum as well as strong interconnectivity between visual (pretectal) and thalamic analog (preglomerular) nuclei. Animals that mix freezing with evasive behaviors (i.e., evading freezers) had higher subpallial connectivity to regions involved in autonomic function and stress responses such as the hypothalamus and preoptic areas.

neuroscience↗

bioRxiv2024

Whole-brain mapping in adult zebrafish and identification of a novel tank test functional connectome

Identifying general principles of brain function requires the study of structure-function relationships in a variety of species. Zebrafish have recently gained prominence as a model organism in neuroscience, yielding important insights into vertebrate brain function. Although methods have been developed for mapping neural activity in larval animals, we lack similar techniques for adult zebrafish that have the advantage of a fully developed neuroanatomy and larger behavioral repertoire. Here, we describe a pipeline built around open-source tools for whole-brain activity mapping in freely swimming adult zebrafish. Our pipeline combines recent advances in histology, microscopy, and machine learning to capture cfos activity across the entirety of the adult brain. Images captured using light-sheet microscopy are registered to the recently created adult zebrafish brain atlas (AZBA) for automated segmentation using advanced normalization tools (ANTs). We used our pipeline to measure brain activity after zebrafish were subject to the novel tank test. We found that cfos levels peaked 15 minutes following behavior and that several regions containing serotoninergic, dopaminergic, noradrenergic, and cholinergic neurons were active during exploration. Finally, we generated a novel tank test functional connectome. Functional network analysis revealed that several regions of the medial ventral telencephalon form a cohesive sub-network during exploration. We also found that the anterior portion of the parvocellular preoptic nucleus (PPa) serves as a key connection between the ventral telencephalon and many other parts of the brain. Taken together, our work enables whole-brain activity mapping in adult zebrafish for the first time while providing insight into neural basis for the novel tank test.

animal behavior and cognition↗

bioRxiv2022

Beyond bold versus shy: Zebrafish exploratory behavior falls into several behavioral clusters and is influenced by strain and sex

Consistent individual differences in exploratory behavior have been found across a range of taxa, including zebrafish, and are thought to contribute to evolutionary fitness. Animals that explore more of a novel environment, and visit areas of high predation risk, are considered bold, whereas animals with the opposite pattern of behavior are considered shy. Here, we examined whether this bimodal characterization of bold versus shy adequately captures the breadth of exploratory behavior exhibited by zebrafish or if, instead, behavior falls into multiple distinct behavioral subtypes. To identify the presence of behavioral subtypes, we applied unsupervised machine learning to behaviors extracted from three-dimensional swim traces from over 400 adult zebrafish across four strains (AB, TL, TU, and WIK) and both sexes. We found that behavior stratified into four distinct clusters. These included previously described bold and shy behavior as well as two new behavioral types: wall-huggers and active explorers. Consistent with prior work that found individual differences to be stable across time and influenced by biological factors like genetics and sex, the behavioral subtypes we identified were stable for up to 10 weeks and were influenced by the strain and sex of the animals. Taken together, our work suggests that individual differences in zebrafish exploratory behavior goes beyond bold versus shy and exhibits greater complexity than is typically assumed.

animal behavior and cognition↗

bioRxiv2018

Risk of disease spillover from dogs to wild carnivores in Kanha Tiger Reserve, India.

Many mammalian carnivore species have been reduced to small, isolated populations by habitat destruction, fragmentation, poaching, and human conflict. Their limited genetic variability and increased exposure to domestic animals such as dogs place them at risk of further losses from infectious diseases. In India, domestic and feral dogs are associated with villages in and around protected areas, and may serve as reservoirs of pathogens to the carnivores within. Indias Kanha Tiger Reserve (KTR) is home to a number of threatened and endangered mammalian carnivores including tiger (Panthera tigris), leopard (Panthera pardus), wolf (Canis lupus), and dhole (Cuon alpinus). It also has more than 150 villages with associated dog populations. We found that dog populations ranged from 14 to 45/village (3.7 to 23.7/km2), and did not vary with village area, human population size, or distance from the KTRs core area, though they all increased between summer 2014 and winter 2015, primarily through reproduction. No dog tested positive for rabies but seroprevalence levels to three other generalist viral pathogens were high in summer (N=67) and decreased somewhat by winter (N=168): canine parvovirus (83.6% to 68.4%), canine distemper virus (50.7% to 30.4%) and canine adenovirus (41.8% to 30.9%). The declines in seroprevalence were primarily due to new recruitments by birth and these were not yet exposed to the viruses. Wild carnivores frequently entered the villages, as shown by tracks, scats, kills and other indicators, and the dogs are known to leave the villages so that encounters between dogs and wild carnivores may be common. We conclude that there is a large population of unvaccinated dogs in and around Kanha Tiger Reserve, with high levels of seroprevalence to pathogens with broad host ranges and these dogs which interact with wild carnivores, therefore posing a high risk of disease spillover to the wild carnivores.

ecology↗