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Plant roots adapt to the mechanical constraints of the soil to grow and absorb water and nutrients. As in animal species, mechanosensitive ion channels in plants are proposed to transduce external mechanical forces into biological signals. However, the identity of these plant root ion channels remains unknown. Here, we show that Arabidopsis thaliana PIEZO1 (PZO1) has preserved the function of its animal relatives and acts as an ion channel. We present evidence that plant PIEZO1 is expressed in the columella and lateral root cap cells of the root tip, which are known to experience robust mechanical strain during root growth. Deleting PZO1 from the whole plant significantly reduced the ability of its roots to penetrate denser barriers compared to wild-type plants. pzo1 mutant root tips exhibited diminished calcium transients in response to mechanical stimulation, supporting a role of PZO1 in root mechanotransduction. Finally, a chimeric PZO1 channel that includes the C-terminal half of PZO1 containing the putative pore region was functional and mechanosensitive when expressed in naive mammalian cells. Collectively, our data suggest that Arabidopsis PIEZO1 plays an important role in root mechanotransduction and establish PIEZOs as physiologically relevant mechanosensitive ion channels across animal and plant kingdoms.

In response to touch, some carnivorous plants such as the Venus flytrap have evolved spectacular movements to capture animals for nutrient acquisition. However, the molecules that confer this sensitivity remain unknown. We used comparative transcriptomics to show that expression of three genes encoding homologs of the MscS-Like (MSL) and OSCA/TMEM63 family of mechanosensitive ion channels are localized to touch-sensitive trigger hairs of Venus flytrap. We focus here on the candidate with the most enriched expression in trigger hairs, the MSL homolog FLYCATCHER1 (FLYC1). We show that FLYC1 transcripts are localized to mechanosensory cells within the trigger hair, transfecting FLYC1 induces chloride-permeable stretch-activated currents in naïve cells, and transcripts coding for FLYC1 homologs are expressed in touch-sensing cells of Cape sundew, a related carnivorous plant of the Droseraceae family. Our data suggest that the mechanism of prey recognition in carnivorous Droseraceae evolved by co-opting ancestral mechanosensitive ion channels to sense touch.

Iron overload causes progressive organ damage and is associated with arthritis, liver damage, and heart failure. Elevated iron levels are present in 1%-5% of individuals; however, iron overload is undermonitored and underdiagnosed. Genetic factors affecting iron homeostasis are emerging. Individuals with hereditary xerocytosis, a rare disorder with gain-of-function (GOF) mutations in mechanosensitive PIEZO1 ion channel, develop age-onset iron overload. We show that constitutive or macrophage expression of a GOF Piezo1 allele in mice disrupts levels of the iron regulator hepcidin and causes iron overload. We further show that PIEZO1 is a key regulator of macrophage phagocytic activity and subsequent erythrocyte turnover. Strikingly, we find that E756del, a mild GOF PIEZO1 allele present in one-third of individuals of African descent, is strongly associated with increased plasma iron. Our study links macrophage mechanotransduction to iron metabolism and identifies a genetic risk factor for increased iron levels in African Americans.

In response to touch, some carnivorous plants such as the Venus flytrap have evolved spectacular movements to capture animals for nutrient acquisition. However, the molecules that confer this sensitivity remain unknown. We used comparative transcriptomics to show that expression of three genes encoding homologs of the MscS-Like (MSL) and OSCA/TMEM63 family of mechanosensitive ion channels are localized to touch-sensitive trigger hairs of Venus flytrap. We focus here on the candidate with the most enriched expression in trigger hairs, the MSL homolog FLYCATCHER1 (FLYC1). We show that FLYC1 transcripts are localized to mechanosensory cells within the trigger hair, transfecting FLYC1 induces chloride-permeable stretch-activated currents in naïve cells, and transcripts coding for FLYC1 homologs are expressed in touch-sensing cells of Cape sundew, a related carnivorous plant of the Droseraceae family. Our data suggest that the mechanism of prey recognition in carnivorous Droseraceae evolved by co-opting ancestral mechanosensitive ion channels to sense touch.

SummaryPlant roots adapt to the mechanical constraints of the soil to grow and absorb water and nutrients. As in animal species, mechanosensitive ion channels in plants are proposed to transduce external mechanical forces into biological signals. However, the identity of these plant root ion channels remains unknown. Here, we show that Arabidopsis thaliana PIEZO (AtPIEZO) has preserved the function of its animal relatives and acts as an ion channel. We present evidence that plant PIEZO is highly expressed in the columella and lateral root cap cells of the root tip which experience robust mechanical strain during root growth. Deleting PIEZO from the whole plant significantly reduced the ability of its roots to penetrate denser barriers compared to wild type plants. piezo mutant root tips exhibited diminished calcium transients in response to mechanical stimulation, supporting a role of AtPIEZO in root mechanotransduction. Finally, a chimeric PIEZO channel that includes the C-terminal half of AtPIEZO containing the putative pore region was functional and mechanosensitive when expressed in naive mammalian cells. Collectively, our data suggest that Arabidopsis PIEZO plays an important role in root mechanotransduction and establishes PIEZOs as physiologically relevant mechanosensitive ion channels across animal and plant kingdoms.

IntroductionMechanotransduction, the conversion of mechanical cues into biochemical signals, is crucial for many biological processes in plants and animals1,2. In mammals, some mechanosensory processes such as touch sensation and vascular development are mediated by the PIEZO family of mechanically activated (MA) ion channels3-5. In plants, the impact of gravity or soil properties on root development, wind on stem growth, and turgor pressure on plant-cell size and shape are proposed to involve activation of MA ion channels6,7. Homologues of the bacterial MA channel MscS (MSLs) exist in plants, and MSL8 is shown to be involved in pollen hydration8; however, the identity of the MA channels required for most mechanotransduction processes in plants have remained elusive9. Here, we identify various members of the 15 OSCA proteins from Arabidopsis thaliana (previously reported as hyperosmolarity sensors10,11) as MA ion channels. Purification and reconstitution of OSCA1.2 in liposomes induced stretch-activated currents, suggesting that OSCAs are inherently mechanosensitive, pore-forming ion channels. This conclusion is confirmed by a high-resolution electron microscopy structure of OSCA1.2 described in a companion paper12. Beyond plants, we present evidence that fruit fly, mouse, and human TMEM63 family of proteins, homologues of OSCAs, induce MA currents when expressed in naïve cells. Our results suggest that OSCA/TMEM63 proteins are the largest family of MA ion channels identified, and are conserved across eukaryotes. We anticipate that further characterization of OSCA isoforms which have diverse biophysical properties, will help gain substantial insight on the molecular mechanism of MA ion channel gating and permeation. OSCA1.1 mutant plants have impaired leaf and root growth under stress, potentially linking this ion channel to a mechanosensory role11. We expect future studies to uncover novel roles of OSCA/TMEM63 channels in mechanosensory processes across plants and animals.

We provide here a detailed protocol for studying the changes in electrical surface potential of leaves. This method has been developed over the years by plant physiologists and is currently used in different variants in many laboratories. The protocol records surface potential changes to measure long distance electrical signals induced by diverse stimuli such as leaf wounding or current injection. This technique can be used to determine signaling speeds to measure the connectivity between different plant organs and by exploiting mutant plants to identify transporters and ion channels involved in electrical signaling. The approach can be combined with the analysis of mRNA expression and of metabolite concentrations to correlate electrical signaling to specific physiological events. We describe how to use this protocol on Arabidopsis looking at the effects of leaf wounding; however it is broadly applicable to other plants and can be used to study other aspects of plant physiology. After wound infliction surface potential recording takes approximately 20 min per plant.

In a large (250 registrants) general education lecture course, neuroscience principles were taught by two professors as co-instructors, starting with simple brain anatomy, chemistry, and function, proceeding to basic brain circuits of pleasure and pain, and progressing with fellow expert professors covering relevant philosophical, artistic, marketing, and anthropological issues. With this as a base, the course wove between fields of high relevance to psychology and neuroscience, such as food addiction and preferences, drug seeking and craving, analgesic pain-inhibitory systems activated by opiates and stress, neuroeconomics, unconscious decision-making, empathy, and modern neuroscientific techniques (functional magnetic resonance imaging and event-related potentials) presented by the co-instructors and other Psychology professors. With no formal assigned textbook, all lectures were PowerPoint-based, containing links to supplemental public-domain material. PowerPoints were available on Blackboard several days before the lecture. All lectures were also video-recorded and posted that evening. The course had a Facebook page for after-class conversation and one of the co-instructors communicated directly with students on Twitter in real time during lecture to provide momentary clarification and comment. In addition to graduate student Teaching Assistants (TAs), to allow for small group discussion, ten undergraduate students who performed well in a previous class were selected to serve as discussion leaders. The Discussion Leaders met four times at strategic points over the semester with groups of 20–25 current students, and received one credit of Independent Study, thus creating a course within a course. The course grade was based on weighted scores from two multiple-choice exams and a five-page writing assignment in which each student reviewed three unique, but brief original peer-review research articles (one page each) combined with expository writing on the first and last pages. A draft of the first page, collected early in the term, was returned to each student by graduate TAs to provide individual feedback on scientific writing. Overall the course has run three times at ful or near enrollment capacity despite being held at an 8:00 AM time slot. Student-generated teaching evaluations place it well within the normal range, while this format importantly contributes to budget efficiency permitting the teaching of more required small-format courses (e.g., freshman writing). The demographics of the course have changed to one in which the vast majority of the students are now outside the disciplines of neuroscience or psychology and are taking the course to fulfill a General Education requirement. This pattern allows the wide dissemination of basic neuroscientific knowledge to a general college audience.

Wounded leaves communicate their damage status to one another through a poorly understood process of long-distance signalling. This stimulates the distal production of jasmonates, potent regulators of defence responses. Using non-invasive electrodes we mapped surface potential changes in Arabidopsis thaliana after wounding leaf eight and found that membrane depolarizations correlated with jasmonate signalling domains in undamaged leaves. Furthermore, current injection elicited jasmonoyl-isoleucine accumulation, resulting in a transcriptome enriched in RNAs encoding key jasmonate signalling regulators. From among 34 screened membrane protein mutant lines, mutations in several clade 3 GLUTAMATE RECEPTOR-LIKE genes (GLRs 3.2, 3.3 and 3.6) attenuated wound-induced surface potential changes. Jasmonate-response gene expression in leaves distal to wounds was reduced in a glr3.3 glr3.6 double mutant. This work provides a genetic basis for investigating mechanisms of long-distance wound signalling in plants and indicates that plant genes related to those important for synaptic activity in animals function in organ-to-organ wound signalling.

The wound response prohormone jasmonic acid (JA) accumulates rapidly in tissues both proximal and distal to injury sites in plants. Using quantitative liquid chromatography-mass spectrometry after flash freezing of tissues, we found that JA accumulated within 30 s of injury in wounded Arabidopsis leaves (p = 3.5 e(-7)). JA augmentation distal to wounds was strongest in unwounded leaves with direct vascular connections to wounded leaves wherein JA levels increased significantly within 120 s of wounding (p = 0.00027). This gave conservative and statistically robust temporal boundaries for the average velocity of the long distance signal leading to distal JA accumulation in unwounded leaves of 3.4-4.5 cm min(-1). Like JA, transcripts of the JA synthesis gene LIPOXYGENASE2 (LOX2) and the jasmonate response gene JAZ10.3 also accumulated to higher levels in directly interconnected leaves than in indirectly connected leaves. JA accumulation in a lox2-1 mutant plant was initiated rapidly after wounding then slowed progressively compared with the wild type (WT). Despite this, JAZ10.3 expression in the two genotypes was similar. Free cyclopentenone jasmonate levels were similar in both resting WT and lox2-1. In contrast, bound cyclopentenone jasmonates (arabidopsides) were far lower in lox2-1 than in the WT. The major roles of LOX2 are to generate arabidopsides and the large levels of JA that accumulate proximal to the wound. LOX2 is not essential for some of the most rapid events elicited by wounding.

The Helicobacter pylori use a number of mechanisms to survive in the stomach lumen and can lead to gastritis and reduction in stomach acid secretion. It has been found that the risk of developing gastric carcinoma is associated to heterogeneity of H. pylori virulence factors such as HopQ. The HopQ is one of the outer membrane proteins involved in bacterial adherence to gastric mucosa and has been suggested to also main role in the virulence of H. pylori. The purpose of the current study was to investigate the association between different H. pylori virulence hopQI (types I) genotyping and patients with gastroduodenal disorders. For this purpose 58 stomach biopsies of the patients with gastric cancer and 100 saliva samples from healthy and H. pylori infected individuals were collected and studied. Then genomic DNA was purified and PCR was done for desired gene via specific primers. The H. pylori infections were diagnosed using PCR for GlmM gene. Then frequencies of hopQI+ and hopQI- genotypes were determined in H. pylori infected cases. Statistical analysis showed that there were not significant differences between healthy and diseased ones for genotypes hopQI+ and hopQI-. Then the hopQI+ cannot be as a risk factor genotype for gastric cancer.

Generalized aggressive periodontitis (GAP) is a subtype of periodontal diseases that characterized by rapid destruction of periodontal supporting tissues. The MnSOD Val-9Ala mutation of manganese superoxide dismutase gene (MnSOD Val-9Ala) and its correlation with periodontal diseases has been studied in different populations. The purpose of this study was to investigate the possible association of MnSODVal-9Ala polymorphism with periodontitis disease in sample of GAP patients in Iran for the first time. Following a GAP examination, 50 GAP patients and 100 healthy individuals were recruited. Genomic DNA was extracted from peripheral blood leukocytes and the MnSODVal-9Ala polymorphismwas detected using PCR-RFLP method. The frequency of Ala/Ala, Ala/Val and Val/Val genotypes in healthy individuals were 25, 66 and 9%, respectively. In periodontitis patients, frequencies were as Ala/Ala (12%), Ala/Val (50%) and Val/Val (38%) genotypes. There was a significant positive association between distribution of MnSOD Val-9Ala genotypes and the risk of periodontitis disease (p0.05). Our results indicated that MnSOD Val-9Ala gene polymorphism has a positive association with the risk of periodontitis disease.