Cell wall integrity: Targeted post-synthetic modifications to reveal its role in plant growth and defense against pathogens

The plant cell wall, a dynamic network of polysaccharides and glycoproteins of significant compositional and structural complexity, functions in plant growth, development and stress responses. In recent years, the existence of plant cell wall integrity (CWI) maintenance mechanisms has been demonstrated, but little is known about the signaling pathways involved, or their components. Examination of key mutants has shed light on the relationships between cell wall remodeling and plant cell responses, indicating a central role for the regulatory network that monitors and controls cell wall performance and integrity. In this review, we present a short overview of cell wall composition and discuss post-synthetic cell wall modification as a valuable approach for studying CWI perception and signaling pathways.     

GISH painting of the Y chromosomes suggests advanced phases of sex chromosome evolution in three dioecious Cannabaceae species (Humulus lupulus,H. japonicus,and Cannabis sativa)

Protoplasma - In plants, dioecy is relatively rare, and it involves sex chromosome systems that often developed independently over time. These characteristics make dioecious plants an attractive...     

Arkaïm-Sintachta : expérience de la mise en valeur des steppes eurasiatiques à l’Âge du Bronze

The “Earth of fortified settlement” is one of the last big discoveries of the end of the XXth century. Situated on the oriental slopes of the mounts of Ural, fortified settlement, date the Middle Bronze Age. These strengthened structures are particular in the archaeology of steppes. They were built according to geometrical plans, Cities in oval being the most ancient, the rectangular cities being the most recent. The most remarkable are together of strengthened structures appropriate for the culture of Sintachta-Arkaïm. This city distinguishes itself from the others by the unique integrity of the works of fortification and by the graves which are connected to these last ones. Situated on a prominence, Arkaim consists of two defensive walls, maybe of a third, the rampart and the ditch. The space between the defensive walls was occupied by the houses of shape trapezoidale and directed as beams to the center of the city. The center of the city, the rectangular shape, was not built and formed a place where foyers were found. Complex entrances were at the four corner of the city. The excavations of fortified settlement and graves allowed to have an idea on the level of development of the everyday life at the time of the Middle Bronze Age in transouraliennes plains.     

Mesoscopic Models of Plants Composed of Metallic Nanowires

Various metallic structures of complex shape resembling living plant organisms (biomimetics) are produced as a result of self-assembly of nanowires growing on porous membranes in the course of pulse current electrodeposition. These structures occur if the electroplating is continued after the nanowires appear on the membrane surface. By varying the membrane geometry, pulse current electroplating parameters, and alternating electrodeposition from two baths composed of a variety of electrolytes, diverse models were fabricated, including a hollow container with a wall thickness of 10 nm – 20 nm. This biomimetic method suggests an analogy between the shape-forming processes of plants and their metallic models. Nanostructured mesostructures of various metals (Ag, Pd, Ni), alloys (PdNi, PbIn) and hybrid structures (PdNi/Pb, PdNi/PbIn) were obtained. They can be of interest for fundamental research (self-assembly, morphogenesis) as well as for applications in nanotechnology (catalysis, nanoplasmonics, medicine, superhydrophobic surfaces).     

Symbiosis extended: exchange of photosynthetic O2 and fungal-respired CO2 mutually power metabolism of lichen symbionts

Photosynthesis Research - Lichens are a symbiosis between a fungus and one or more photosynthetic microorganisms that enables the symbionts to thrive in places and conditions they could not compete...     

High Prevalence of Multistability of Rest States and Bursting in a Database of a Model Neuron

Flexibility in neuronal circuits has its roots in the dynamical richness of their neurons. Depending on their membrane properties single neurons can produce a plethora of activity regimes including silence, spiking and bursting. What is less appreciated is that these regimes can coexist with each other so that a transient stimulus can cause persistent change in the activity of a given neuron. Such multistability of the neuronal dynamics has been shown in a variety of neurons under different modulatory conditions. It can play either a functional role or present a substrate for dynamical diseases. We considered a database of an isolated leech heart interneuron model that can display silent, tonic spiking and bursting regimes. We analyzed only the cases of endogenous bursters producing functional half-center oscillators (HCOs). Using a one parameter (the leak conductance ()) bifurcation analysis, we extended the database to include silent regimes (stationary states) and systematically classified cases for the coexistence of silent and bursting regimes. We showed that different cases could exhibit two stable depolarized stationary states and two hyperpolarized stationary states in addition to various spiking and bursting regimes. We analyzed all cases of endogenous bursters and found that 18% of the cases were multistable, exhibiting coexistences of stationary states and bursting. Moreover, 91% of the cases exhibited multistability in some range of . We also explored HCOs built of multistable neuron cases with coexisting stationary states and a bursting regime. In 96% of cases analyzed, the HCOs resumed normal alternating bursting after one of the neurons was reset to a stationary state, proving themselves robust against this perturbation.