Plants actively perceive and respond to perturbations in their cell walls which arise during growth, biotic and abiotic stresses. However, few components involved in plant cell wall integrity sensing ...have been described to date. Using a reverse-genetic approach, we identified the Arabidopsis thaliana leucine-rich repeat receptor kinase MIK2 as an important regulator of cell wall damage responses triggered upon cellulose biosynthesis inhibition. Indeed, loss-of-function mik2 alleles are strongly affected in immune marker gene expression, jasmonic acid production and lignin deposition. MIK2 has both overlapping and distinct functions with THE1, a malectin-like receptor kinase previously proposed as cell wall integrity sensor. In addition, mik2 mutant plants exhibit enhanced leftward root skewing when grown on vertical plates. Notably, natural variation in MIK2 (also named LRR-KISS) has been correlated recently to mild salt stress tolerance, which we could confirm using our insertional alleles. Strikingly, both the increased root skewing and salt stress sensitivity phenotypes observed in the mik2 mutant are dependent on THE1. Finally, we found that MIK2 is required for resistance to the fungal root pathogen Fusarium oxysporum. Together, our data identify MIK2 as a novel component in cell wall integrity sensing and suggest that MIK2 is a nexus linking cell wall integrity sensing to growth and environmental cues.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In Dublin, the War of Irish Independence (1919-1921) was an intense and dirty battle between military intelligence agents. While IRA flying columns fought the British Army and the Black and Tans in ...the countryside, the fighting in Ireland's capital city pitted the wits of IRA commander Michael Collins against the cloak-and-dagger innovations of British Intelligence chief Colonel Ormonde de l'Epee Winter. Drawing on detailed witness statements of Irish participants and documents and biographies from the British side, this history chronicles the covert war of assassinations, arrests, torture and murder that climaxed in the Bloody Sunday mass assassination of British intelligence officers by IRA squads in November 1920.
The plant cell wall is a dynamic and complex structure whose functional integrity is constantly being monitored and maintained during development and interactions with the environment. In response to ...cell wall damage (CWD), putatively compensatory responses, such as lignin production, are initiated. In this context, lignin deposition could reinforce the cell wall to maintain functional integrity. Lignin is important for the plant's response to environmental stress, for reinforcement during secondary cell wall formation, and for long-distance water transport. Here, we identify two stages and several components of a genetic network that regulate CWD-induced lignin production in Arabidopsis (Arabidopsis thaliana). During the early stage, calcium and diphenyleneiodonium-sensitive reactive oxygen species (ROS) production are required to induce a secondary ROS burst and jasmonic acid (JA) accumulation. During the second stage, ROS derived from the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D and lA-isoleucine generated by IASMONIC ACID RESISTANT1, form a negative feedback loop that can repress each other's production. This feedback loop in turn seems to influence lignin accumulation. Our results characterize a genetic network enabling plants to regulate lignin biosynthesis in response to CWD through dynamic interactions between JA and ROS.
The plant nucleus and the actin cytoskeleton are intimately connected. The actin cytoskeleton is pivotal for nuclear positioning, shape, and dynamics. These properties of the nucleus are important ...for its functions during normal development and in response to external cues such as biotic and abiotic stresses. Moreover, we know that there is a direct physical connection between the actin cytoskeleton and the nucleus which spans the double-membraned nuclear envelope into the nuclear lamina, and this connection is called the linker of nucleoskeleton and cytoskeleton (LINC) complex. Recently a role for actin in regulating inter-nuclear organization via the control of nuclear invaginations has emerged. Therefore, a detailed understanding of nuclear shape, organization, and dynamics and the techniques used to measure and quantify these metrics will allow us to determine and further understand the contribution made by actin to these parameters. The protocols described here will allow researchers to determine the circularity index of a nucleus, quantify nuclear deformations, and determine dynamics of nuclei within plant cells.
i Women have too often been written out of history. This is especially true in the fight for Irish independence. The women's struggle was three-fold, beginning with the suffragettes' fight to win the ...vote. Then came the push for fair pay and working conditions. Binding them together became part of the national struggle, first for home rule, then for the establishment of an Irish Republic. The Easter Rising of 1916 brought them together as soldiers of the Republic. Through the terrible years that followed, they became the conscience of Republicanism. Following independence, they were betrayed by the men they had served alongside. DeValera and the Catholic Church restricted their roles in society--they were to be wives and mothers without a voice. It was not until Ireland's entry into the European community and the self destruction of a corrupt Church that Irish women were acknowledged for what they had achieved.
•Oscillations are ubiquitous in insulin-secreting beta-cells of the pancreas.•These may be due to intrinsic glycolytic oscillations or calcium feedback onto glycolysis.•A pulsatile blood insulin ...level facilitates glucose clearance from the blood.•The oscillation mechanisms are analyzed here using fast-slow analysis.
Insulin-secreting pancreatic β-cells are electrically excitable cells that are unusual because their electrical activity is influenced directly by metabolism via ATP-sensitive K+ channels. At the same time, changes in the intracellular Ca2+concentration that result from the cell’s electrical activity influence metabolism in several ways. Thus, there is bidirectional coupling between the electrical dynamics and the metabolic dynamics in β-cells. A mathematical model has been previously developed, called the Integrated.
Oscillator Model (IOM), to highlight the bidirectional coupling involved in the oscillation mechanism. In this study, we show how this coupling can produce oscillations in β-cell activity. These oscillations have period similar to that of insulin secretion pulses observed in rats, mice, dogs, and humans, which has been shown to facilitate the action of the liver in maintaining glucose homeostasis. In a companion paper we show that the IOM can produce oscillations using two distinct mechanisms, depending on the values of electrical and metabolic parameters. In the present article, we use fast-slow analysis to understand the mechanisms underlying each of these oscillations. In particular, we show why a key variable in the glycolytic pathway generates a pulsatile time course in one type of oscillation, while it generates a sawtooth time course in the other type. The significance of these patterns is that the time course is a reflection of whether an intrinsic glycolytic oscillator is active, or whether the oscillations are a direct consequence of Ca2+ feedback onto glycolysis.
Focusing on British involvement in the American Civil War, this history names the overseas bankers and manufacturers who, in critical need of cotton and other Confederate exports, financed and ...equipped the fast little ships that ran the Union blockade.
Seeds of dicotyledonous plants store proteins in dedicated membrane-bounded organelles called protein storage vacuoles (PSVs). Formed during seed development through morphological and functional ...reconfiguration of lytic vacuoles in embryos M. Feeney
,
177, 241-254 (2018), PSVs undergo division during the later stages of seed maturation. Here, we study the biophysical mechanism of PSV morphogenesis in vivo, discovering that micrometer-sized liquid droplets containing storage proteins form within the vacuolar lumen through phase separation and wet the tonoplast (vacuolar membrane). We identify distinct tonoplast shapes that arise in response to membrane wetting by droplets and derive a simple theoretical model that conceptualizes these geometries. Conditions of low membrane spontaneous curvature and moderate contact angle (i.e., wettability) favor droplet-induced membrane budding, thereby likely serving to generate multiple, physically separated PSVs in seeds. In contrast, high membrane spontaneous curvature and strong wettability promote an intricate and previously unreported membrane nanotube network that forms at the droplet interface, allowing molecule exchange between droplets and the vacuolar interior. Furthermore, our model predicts that with decreasing wettability, this nanotube structure transitions to a regime with bud and nanotube coexistence, which we confirmed in vitro. As such, we identify intracellular wetting J. Agudo-Canalejo et al., Nature 591, 142-146 (2021) as the mechanism underlying PSV morphogenesis and provide evidence suggesting that interconvertible membrane wetting morphologies play a role in the organization of liquid phases in cells.
Metabolism in islet β-cells displays oscillations that can trigger pulses of electrical activity and insulin secretion. There has been a decades-long debate among islet biologists about whether ...metabolic oscillations are intrinsic or occur in response to oscillations in intracellular Ca2+ that result from bursting electrical activity. In this article, the dynamics of oscillatory metabolism were investigated using five different optical reporters. Reporter activity was measured simultaneously with membrane potential bursting to determine the phase relationships between the metabolic oscillations and electrical activity. Our experimental findings suggest that Ca2+ entry into β-cells stimulates the rate of mitochondrial metabolism, accounting for the depletion of glycolytic intermediates during each oscillatory burst. We also performed Ca2+ clamp tests in which we clamped membrane potential with the KATP channel-opener diazoxide and KCl to fix Ca2+ at an elevated level. These tests confirm that metabolic oscillations do not require Ca2+ oscillations, but show that Ca2+ plays a larger role in shaping metabolic oscillations than previously suspected. A dynamical picture of the mechanisms of oscillations emerged that requires the restructuring of contemporary mathematical β-cell models, including our own dual oscillator model. In the companion article, we modified our model to account for these new data.
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