Jasmonate biosynthesis arising from altered cell walls is prompted by turgor-driven mechanical compression

Despite the vital roles of jasmonoyl-isoleucine (JA-Ile) in governing plant growth and environmental acclimation, it remains unclear what intracellular processes lead to its induction. Here, we provide compelling genetic evidence that mechanical and osmotic regulation of turgor pressure represents a key elicitor of JA-Ile biosynthesis. After identifying cell wall mutant alleles in KORRIGAN1 (KOR1) with elevated JA-Ile in seedling roots, we found that ectopic JA-Ile resulted from cell nonautonomous signals deriving from enlarged cortex cells compressing inner tissues and stimulating JA-Ile production. Restoring cortex cell size by cell type–specific KOR1 complementation, by isolating a genetic kor1 suppressor, and by lowering turgor pressure with hyperosmotic treatments abolished JA-Ile signaling. Conversely, hypoosmotic treatment activated JA-Ile signaling in wild-type plants. Furthermore, constitutive JA-Ile levels guided mutant roots toward greater water availability. Collectively, these findings enhance our understanding on JA-Ile biosynthesis initiation and reveal a previously undescribed role of JA-Ile in orchestrating environmental resilience.

Jasmonate biosynthesis arising from altered cell walls is prompted by turgor-driven mechanical compression and guides root hydrotropism

ABSTRACTDespite the vital roles of jasmonoyl-isoleucine (JA-Ile) in governing plant growth and environmental acclimation, it remains unclear what intracellular processes lead to its induction. Here, we provide compelling genetic evidence that mechanical and osmotic regulation of turgor pressure represents a key factor in eliciting JA-Ile biosynthesis. After identifying cell wall mutant alleles in KORRIGAN1 (KOR1) with elevated JA-Ile in seedling roots, we found that ectopic JA-Ile resulted from cell non-autonomous signals deriving from enlarged cortex cells compressing inner tissues and stimulating JA-Ile production. Restoring cortex cell size by cell-type-specific KOR1 complementation, by isolating a genetic kor1 suppressor, and by lowering turgor pressure with hyperosmotic treatments, abolished JA-Ile signalling. Strikingly, heightened JA-Ile levels guided kor1 roots towards greater water availability, uncovering a previously unrecognized JA-Ile function in root hydrotropism. Collectively, these findings enhance our understanding of JA-Ile biosynthesis initiation, and reveal a novel role of JA-Ile in orchestrating environmental resilience.

Favorable Effects of Astaxanthin on Brain Damage due to Ischemia- Reperfusion Injury

Background: Activated inflammation and oxidant stress during cerebral ischemia reperfusion injury (IRI) lead to brain damage. Astaxanthin (ASX) is a type of carotenoid with a strong antioxidant effect. Objective: The aim of this study was to investigate the role of ASX on brain IRI. Methods: A total of 42 adult male Sprague-Dawley rats were divided into 3 groups as control (n=14) group, IRI (n=14) group and IRI + ASX (n=14) group. Cerebral ischemia was instituted by occluding middle cerebral artery for 120 minutes and subsequently, reperfusion was performed for 48 hours. Oxidant parameter levels and protein degradation products were evaluated. Hippocampal and cortex cell apoptosis, neuronal cell count, neurological deficit score were evaluated. Results: In the IRI group, oxidant parameter levels and protein degradation products in the tissue were increased compared to control group. However, these values were significantly decreased in the IRI + ASX group (p<0.05). There was a significant decrease in hippocampal and cortex cell apoptosis and a significant increase in the number of neuronal cells in the IRI + ASX group compared to the IRI group alone (p<0.05). The neurological deficit score which was significantly lower in the IRI group compared to the control group was found to be significantly improved in the IRI + ASX group (p<0.05). Conclusion: Astaxanthin protects the brain from oxidative damage and reduces neuronal deficits due to IRI injury.

Piriform cortex provides a dominant gamma LFP oscillation in the anterior limbic system

Oscillations in the local field potential (LFP) are widespread throughout the rodent limbic system, including in structures such as the orbitofrontal cortex and nucleus accumbens. Synchrony between LFPs across these structures, as seen during specific behavioral events, is often interpreted as evidence of a functional interaction. However, the source of these oscillations is often tacitly assumed to be local, leading to a potential misattribution of function. Using in vivo simultaneous multisite recordings in freely moving male rats (n = 7) we demonstrate that gamma-band LFP oscillations (45-90 Hz) in multiple anterior limbic structures are highly synchronous not only with each other, but also with those in piriform cortex. Phase reversals across the piriform cortex cell layer and susceptibility to nasal occlusion indicate that piriform cortex is the source of these common gamma oscillations. Thus, gamma-band LFP oscillations seen in brain regions adjacent to the piriform cortex are likely not generated locally, but are instead volume conducted from the piriform cortex. This emerging view of gamma oscillations in anterior limbic circuits highlights the importance of the common piriform cortex input as a major influence and introduces caveats in the interpretation of locally recorded LFPs.

Mouse (Mus musculus) embryonic cerebral cortex cell death caused by carbofuran insecticide exposure

Introduction The aim of the study was to describe the process of neuron death in the cerebral cortex caused by embryonic carbofuran exposure. Material and Methods 81 mouse foetuses from 27 breeding mice were used in the study. Carbofuran was administered by gavage from the 6th to the 15th day of gestation to two groups: one at 0.0208 and the other at 0.0417 mg/kg b.w. On the 17th day, the mice were sacrificed and the foetuses were taken to measure the ROS (malondialdehyde/MDA and superoxide dismutase/SOD) activity in brain tissue, the number of apoptotic embryonic cerebral cortex neurons using a TUNEL assay, and necrotic cells using HE staining. Examination of p53 and caspase 3 expression was done by immunohistochemistry. Data were analysed using analysis of variance (ANOVA) and Duncan’s test. Results Increased activity of cerebral ROS characterised by significant elevation of the MDA level (P < 0.05), decreased SOD (P < 0.01), increased p53 and caspase 3 expression, and cerebral cortical neuron death either by necrosis or apoptosis (P < 0.05) were found. At the low dose carbofuran increased expression of p53, caspase 3, and apoptosis. At the high dose it increased levels of MDA and necrosis. Conclusion Increased expression of p53 and caspase 3 and apoptosis indicated that carbofuran may cause apoptosis through the intrinsic pathway. The increased apoptosis grants an opportunity to prevent and treat the effect of ROS due to gestational carbofuran exposure.

Cortex cell hydraulic conductivity, endodermal apoplastic barriers and root hydraulics change in barley (Hordeum vulgare L.) in response to a low supply of N and P

Background Mineral nutrient limitation affects the water flow through plants. We wanted to test on barley whether any change in root-to-shoot ratio in response to low supply of nitrogen and phosphate is accompanied by changes in root and cell hydraulic properties and involves changes in aquaporin (AQP) gene expression and root apoplastic barriers (suberin lamellae, Casparian bands). Methods Plants were grown hydroponically on complete nutrient solution or on solution containing only 3.3 % or 2.5 % of the control level of nutrient. Plants were analysed when they were 14–18 d old. Results Nutrient-limited plants adjusted water flow to an increased root-to-shoot surface area ratio through a reduction in root hydraulic conductivity (Lp) as determined through exudation analyses. Cortex cell Lp (cell pressure probe analyses) decreased in the immature but not the mature region of the main axis of seminal roots and in primary lateral roots. The aquaporin inhibitor HgCl2 reduced root Lp most in nutrient-sufficient control plants. Exchange of low-nutrient for control media caused a rapid (20–80 min) and partial recovery in Lp, though cortex cell Lp did not increase in any of the root regions analysed. The gene expression level (qPCR analyses) of five plasma membrane-localized AQP isoforms did not change in bulk root extracts, while the formation of apoplastic barriers increased considerably along the main axis of root and lateral roots in low-nutrient treatments. Conclusions Decrease in root and cortex cell Lp enables the adjustment of root water uptake to increased root-to-shoot area ratio in nutrient-limited plants. Aquaporins are the prime candidate to play a key role in this response. Modelling of water flow suggests that some of the reduction in root Lp is due to increased formation of apoplastic barriers.

Adaptive morphoanatomy and ecophysiology of Billbergia euphemiae, a hemiepiphyte Bromeliaceae

Habitats under distinct selective pressures exert adaptative pressures that can lead individuals of the same species to present different life strategies for their survival. The aim of this study was to analyse morphoanatomical and physiological traits for identification of adaptive ecological strategies related to both terrestrial and epiphytic life phases of Billbergia euphemiae. It was verified that B. euphemiae showed lower height, as well smaller length, width and foliar area in epiphytic phase than in terrestrial phase. Concerning to foliar anatomy, the thicknesses of leaf and water-storage parenchyma were higher in terrestrial phase, as densities of stomata and scales on the abaxial surface were higher in epiphytic phase. About the contents of photosynthetic pigments, only chlorophyll a/b ratio showed differences between life phases. In both habits, plants exhibited roots with absorption hair. In epiphytic phase, roots exhibited higher velamen thickness, smaller outer cortex, higher number of inner cortex cell layers and higher number of protoxylem poles. Thus, B. euphemiae individuals in epiphytic exhibited lots of traits related to water retention, once these plants are not into the ground. Besides, the plasticity observed may contribute for survival of this group in habitats submitted to modifications (e.g., climate change and other variations caused by human interference).