Biology subjects

Sujatha, G. B.

Publications and source records attributed to Sujatha, G. B..

3 recordsLinked to original sources

bioRxiv2025

Fate of a fallen ant: Time-resolved micro-CT analysis of ant digestion in Nepenthes pitchers

Carnivorous pitcher plants of the genus Nepenthes have evolved highly specialized leaf-derived traps that capture and enzymatically digest insect prey to supplement nutrient acquisition in nutrient-deficient habitats. This study aimed to elucidate the structural dynamics underlying prey digestion in Nepenthes khasiana using high-resolution micro-computed tomography (micro-CT) integrated with biochemical characterization of the pitcher fluid. Three-dimensional morphometric analysis of the invasive yellow crazy ant, Anoplolepis gracilipes, experimentally incubated in N. khasiana pitcher fluid, was conducted to assess time-dependent structural degradation. Quantitative micro-CT parameters, including volume, surface area, and surface-to-volume ratio, were analyzed to visualize and quantify time-dependent structural degradation and three-dimensional morphological changes in the prey during digestion. A triphasic digestion sequence was identified - comprising rapid soft-tissue hydrolysis, progressive exoskeletal fragmentation, and stabilization of chitinous remnants. The acidic, enzymatic fluid (pH 2.5-4.0) promoted uniform degradation through synergistic enzymatic, oxidative, and acidification processes, while dissolved CO2 enhanced acid stability and catalytic efficiency. The integration of micro-CT morphometrics and biochemical insights reveals a coordinated digestion mechanism in N. khasiana, optimized for efficient prey breakdown and nutrient assimilation. ONE-SENTENCE SUMMARYMicro-CT analysis revealed a triphasic digestion process in Nepenthes khasiana, elucidating the structural and enzymatic dynamics of efficient prey degradation.

ecology↗

bioRxiv2023

Bait, not reward: CO2-enriched Nepenthes pitchers secrete toxic nectar

Nepenthes pitchers are leaf-evolved biological traps holding high levels of CO2 within them. Extrafloral nectar (EFN) secreted by these pitchers has long been regarded as the major reward to visiting arthropods, but its chemical constituents and their role in prey capture are least explored. Here we demonstrate Nepenthes EFN as a sugar (glucose-fructose-sucrose) mix with high C:N ratio, minimal amino acids, proteins, and vitamin C. Nepenthes khasiana peristome and lid EFNs displayed strong acetylcholinesterase (AChE) inhibition; the naphthoquinone derivative, (+)-isoshinanolone, has been identified as the AChE inhibitor. Plumbagin, the major volatile naphthoquinone in Nepenthes, also showed strong AChE inhibition. Direct EFN- and (+)-isoshinanolone-feeding bioassays demonstrated symptoms of cholinergic toxicity in ants. We testify that Nepenthes EFN is a toxic bait which hinders neuronal activity in visiting arthropods. These unique traps adopt various deceptive strategies for prey capture, and our discovery abolishes the notion that Nepenthes EFN is a reward to visiting ants and other arthropods. Moreover, our findings infer elevated CO2 within their pitchers as the key factor influencing the growth, metabolism, herbivory, and carnivory in Nepenthes. HighlightNepenthes extrafloral nectar has high content of carbohydrates and minimal nitrogenous metabolites. It is laced with (+)-isoshinanolone, an acetylcholinesterase inhibitor, and acts as a toxic bait, aiding prey capture.

plant biology↗

bioRxiv2023

Nepenthes pitchers versus thermogenic flowers: thermal patterns and their role in prey capture and pollination

Prey capture in Nepenthes and pollination in angiosperms are two antithetical events; one designed to trap insects and other arthropods (carnivory) and the other to transfer pollen through pollinators (reproduction). In this study infrared thermography is extensively used to obtain thermal profiles of Nepenthes pitchers and thermogenic flowers in field conditions. N. khasiana pitchers displayed below ambient temperatures during evening-night-morning hours (5 pm to 8-9-10 am); pitcher spots recorded lowest and highest temperatures as 14.4 (6-7 am) and 45.6{degrees}C (2 pm), respectively. In the evening-night-morning hours top pitcher spots displayed significant decrease (upto 6.7{degrees}C) from the ambient temperature. The average humidities in the night and day periods were 77.15% and 50.15%, respectively. Thermographic tracking of the pitcher (lid) opening in N. khasiana demonstrated initial wet pitcher in night, which gradually switched to a relatively dry surface in the morning-day times; but the peristome region retained the wetness till 10.30 a.m. The prey capturing zones in Nepenthes pitchers (peristome, lid and their intersection) are colder favoring prey capture, whereas in thermogenic flowers, floral portions are hotter, providing the thermal requirements for the pollinator. In thermogenic plants, floral zones assist pollination by offering a thermal reward through enzymatic processes; but Nepenthes traps achieve lower temperature spots by physical (surface microstructures), chemical (extrafloral nectar) and ecological (rain, humidity) factors.

plant biology↗