Should fish feel pain? A plant perspective

Key (2016) claims fish that fish do not feel pain because they lack the necessary neuronal architecture: their responses to noxious stimuli, according to Key, are executed automatically without any feelings. However, as pointed out by many of his commentators, this conclusion is not convincing. Plants might provide some clues. Plants are not usually thought to be very active behaviorally, but the evidence suggests otherwise. Moreover, in stressful situations, plants produce numerous chemicals that have painkilling and anesthetic properties. Finally, plants, when treated with anesthetics, cannot execute active behaviors such as touch-induced leaf movements or rapid trap closures after localizing animal prey

Fish and plant sentience: Anesthetized plants and fishes cannot respond to stimuli

Recent denial of fish sentience is at variance with the fact that all living organisms need environmental awareness in order to survive in a continuously fluctuating environment. Moreover, fish sentience – like plant sentience – is also strongly supported by the sensitivity of fishes and plants to diverse anesthetics

Disruption of actin filaments induces mitochondrial Ca2+ release to the cytoplasm and [Ca2+]c changes in Arabidopsis root hairs

<p>Abstract</p> <p>Background</p> <p>Mitochondria are dynamic organelles that move along actin filaments, and serve as calcium stores in plant cells. The positioning and dynamics of mitochondria depend on membrane-cytoskeleton interactions, but it is not clear whether microfilament cytoskeleton has a direct effect on mitochondrial function and Ca²⁺storage. Therefore, we designed a series of experiments to clarify the effects of actin filaments on mitochondrial Ca²⁺storage, cytoplasmic Ca²⁺concentration ([Ca²⁺]_c), and the interaction between mitochondrial Ca²⁺and cytoplasmic Ca²⁺in <it>Arabidopsis </it>root hairs.</p> <p>Results</p> <p>In this study, we found that treatments with latrunculin B (Lat-B) and jasplakinolide (Jas), which depolymerize and polymerize actin filaments respectively, decreased membrane potential and Ca²⁺stores in the mitochondria of <it>Arabidopsis </it>root hairs. Simultaneously, these treatments induced an instantaneous increase of cytoplasmic Ca²⁺, followed by a continuous decrease. All of these effects were inhibited by pretreatment with cyclosporin A (Cs A), a representative blocker of the mitochondrial permeability transition pore (mPTP). Moreover, we found there was a Ca²⁺concentration gradient in mitochondria from the tip to the base of the root hair, and this gradient could be disrupted by actin-acting drugs.</p> <p>Conclusions</p> <p>Based on these results, we concluded that the disruption of actin filaments caused by Lat-B or Jas promoted irreversible opening of the mPTP, resulting in mitochondrial Ca²⁺release into the cytoplasm, and consequent changes in [Ca²⁺]_c. We suggest that normal polymerization and depolymerization of actin filaments are essential for mitochondrial Ca²⁺storage in root hairs.</p

Actin Turnover Is Required for Myosin-Dependent Mitochondrial Movements in Arabidopsis Root Hairs

Background: Previous studies have shown that plant mitochondrial movements are myosin-based along actin filaments, which undergo continuous turnover by the exchange of actin subunits from existing filaments. Although earlier studies revealed that actin filament dynamics are essential for many functions of the actin cytoskeleton, there are little data connecting actin dynamics and mitochondrial movements. Methodology/Principal Findings: We addressed the role of actin filament dynamics in the control of mitochondrial movements by treating cells with various pharmaceuticals that affect actin filament assembly and disassembly. Confocal microscopy of Arabidopsis thaliana root hairs expressing GFP-FABD2 as an actin filament reporter showed that mitochondrial distribution was in agreement with the arrangement of actin filaments in root hairs at different developmental stages. Analyses of mitochondrial trajectories and instantaneous velocities immediately following pharmacological perturbation of the cytoskeleton using variable-angle evanescent wave microscopy and/or spinning disk confocal microscopy revealed that mitochondrial velocities were regulated by myosin activity and actin filament dynamics. Furthermore, simultaneous visualization of mitochondria and actin filaments suggested that mitochondrial positioning might involve depolymerization of actin filaments on the surface of mitochondria. Conclusions/Significance: Base on these results we propose a mechanism for the regulation of mitochondrial speed of movements, positioning, and direction of movements that combines the coordinated activity of myosin and the rate of actin turnover, together with microtubule dynamics, which directs the positioning of actin polymerization events.Publisher PDFPeer reviewe

Should fish feel pain? A plant perspective

Key (2016) claims fish that fish do not feel pain because they lack the necessary neuronal architecture: their responses to noxious stimuli, according to Key, are executed automatically without any feelings. However, as pointed out by many of his commentators, this conclusion is not convincing. Plants might provide some clues. Plants are not usually thought to be very active behaviorally, but the evidence suggests otherwise. Moreover, in stressful situations, plants produce numerous chemicals that have painkilling and anesthetic properties. Finally, plants, when treated with anesthetics, cannot execute active behaviors such as touch-induced leaf movements or rapid trap closures after localizing animal prey

Sense of space: Tactile sense for exploratory behavior of roots

In soil, plant roots grow in heterogeneous environments. Plant roots are always facing the difficulty of searching effectively the patchy natural resources, such as water, oxygen, ions and mineral nutrition. Numerous studies reported that root apex navigation enables roots to explore complex environments. In this short communication, we characterize how growing maize roots explore narrow space available with two experimental settings: tactile exploration of narrow glass tube and circumnutation in free space. We also discuss root growth in the soil in terms of foraging behavior guided by the sensory root apex