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SUMMARYIn many applicative fields, there is the need to model and design complex systems having a mixed discrete and continuous behavior that cannot be characterized faithfully using either discrete or continuous models only. Such systems consist of a discrete control part that operates in a continuous environment and are named hybrid systems because of their mixed nature. Unfortunately, most of the verification problems for hybrid systems, like reachability analysis, turn out to be undecidable. Because of this, many approximation techniques and tools to estimate the reachable set have been proposed in the literature. However, most of the tools are unable to handle nonlinear dynamics and constraints and have restrictive licenses. To overcome these limitations, we recently proposed an open-source framework for hybrid system verification, called ARIADNE, which exploits approximation techniques based on the theory of computable analysis for implementing formal verification algorithms. In this paper, we will show how the approximation capabilities of ARIADNE can be used to verify complex hybrid systems, adopting an assume-guarantee reasoning approach.

Mitochondria control life and death in eukaryotic cells. Harboring a unique circular genome, a by-product of an ancient endosymbiotic event, mitochondria maintains a specialized and evolutionary divergent protein synthesis machinery, the mitoribosome. Mitoribosome biogenesis depends on elements encoded in both the mitochondrial genome (the RNA components) and the nuclear genome (all ribosomal proteins and assembly factors). Recent cryo-EM structures of mammalian mitoribosomes have illuminated their composition and provided hints regarding their assembly and elusive mitochondrial translation mechanisms. A growing body of literature involves the mitoribosome in inherited primary mitochondrial disorders. Mutations in genes encoding mitoribosomal RNAs, proteins, and assembly factors impede mitoribosome biogenesis, causing protein synthesis defects that lead to respiratory chain failure and mitochondrial disorders such as encephalo-and cardiomyopathy, deafness, neuropathy, and developmental delays. In this article, we review the current fundamental understanding of mitoribosome assembly and function, and the clinical landscape of mitochondrial disorders driven by mutations in mitoribosome components and assembly factors, to portray how basic and clinical studies combined help us better understand both mitochondrial biology and medicine.

Model-based design is an important approach for embedded software. The method starts from a mathematical representation of the design problem and derives the software implementation from this representation. The model that has had most success especially for control dominated application is synchronous reactive. While this model simplifies the way of dealing with concurrency by decoupling functional and timing aspects, when implemented, it may be inefficient since the synchronous assumption implies constraints that are stronger than needed. We present in this paper a method for improving the efficiency of the software design process, by relaxing computation constraints, while preserving the synchronous computation semantics, with the introduction of a particular inter-task communication mechanism. We show how this mechanism can be implemented on single processor, multi processor and distributed implementation platforms.

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DinJ-YafQ is a type II TA system comprising the ribosome-dependent RNase YafQ toxin and the DinJ antitoxin protein. Although the module has been extensively characterized in Escherichia coli , little information is available for homologous systems in lactic acid bacteria. In this study, we employed bioinformatics tools to identify DinJ-YafQ systems in Lactobacillus casei , Lactobacillus paracasei and Lactobacillus rhamnosus species, commonly used in biotechnological processes. Among a total of nineteen systems found, two TA modules from Lactobacillus paracasei and two modules from Lactobacillus rhamnosus wild strains were isolated and their activity was verified by growth assays in Escherichia coli either in liquid and solid media. The RNase activity of the YafQ toxins was verified in vivo by probing mRNA dynamics and metabolism with single-cell Thioflavin T fluorescence. Our findings demonstrate that, albeit DinJ-YafQ TA systems are widely distributed in lactic acid bacteria, only few are fully functional, while others have lost toxicity even though they maintain high sequence identity with wild type YafQ and a likely functional antitoxin protein.

Plasmids carry genes that give bacteria beneficial traits and allow them to survive in competitive environments. In many cases, they also harbor toxin-antitoxin (TA) systems necessary for plasmid maintenance. TA systems are generally characterized by a stable “toxin”, a protein or peptide capable of killing the cell upon plasmid loss and by an unstable “antitoxin”, a protein or a non-coding RNA that inhibits toxin activity. Here we report data toward the identification of a RNA-regulated TA system in the plasmid DNA of L. rhamnosus isolated from cheese. The proposed TA system comprises two convergently transcribed RNAs: a toxin RNA encoding a 29 amino acid peptide named Lpt and an antitoxin non-coding RNA. Both toxin and antitoxin RNAs resulted upregulated under conditions mimicking cheese ripening. The toxicity of the Lpt peptide was demonstrated in E. coli by cloning the Lpt ORF under the control of an inducible promoter. Bioinformatics screening of the bacterial nucleotide database, shows that regions homologous to the Lpt TA locus are widely distributed in the Lactobacillus genus, particularly within the L. casei group, suggesting a relevant role of TA systems in plasmid maintenance of cheese microbiota.

Fault-tolerant electronic sub-systems are becoming a standard requirement in the automotive industrial sector as electronics becomes pervasive in present cars. We address the issue of fault tolerant chip architectures for automotive applications. We begin by reviewing fault-tolerant architectures commonly used in other industrial domains where faulttolerant electronics has been a must for a number of years, e.g., the aircraft manufacturing industrial sector. We then proceed to investigate how these architecture could be implemented on a single chip and we compare them with a metric that combines traditional terms such as cost, performance and fault coverage with flexibility, i.e. the ability of adapting to changing requirements and capturing a wide range of applications, an emerging criterion for platform design. Finally, we describe in some details a cost effective dual lockstep platform that can be used as a single fail-operational unit or as two fail-silent channels trading fault-tolerance for performance.