Proteomic analysis of cold stressed Arabidopsis thaliana chloroplasts

Low temperature is one of the major abiotic stresses limiting the productivity and the geographical distribution of many species. The effect of cold acclimatization is evident at chloroplast level because one of the main target of damages causes by low temperatures is the photosynthetic apparatus. For this reason our aim is to analyze the change in level of expression of chloroplast proteins during stress. 13-days old plants were acclimatized at 4°C for 1 week and treated at -10°C for 12 h and then recovered for 24 h. Freezing treatment produced stress phenotypes of rolling leaves, decrease in pigment content. At low temperature wild-type plants exhibited symptoms of severe oxidative stress: lipid peroxidation, chlorophyll bleaching, and photoinhibition. In acclimatated plants, which accumulate over twice as much zeaxanthin as the control, these symptoms were significantly ameliorated. The changes of total proteins in chloroplasts were examined using two-dimensional electrophoresis. Among 200 protein spots reproducibly detected on each gel, we found up- and down-regulated spots. Mass spectrometry analysis allowed the identification of 30 differentially expressed proteins, including well know cold-responsive proteins. Several proteins showed enhanced degradation during freezing stress, especially the photosynthetic proteins such as Rubisco activase (RcbA) and Rubisco large subunit (RcbL) of which 4 fragments were detected. The identified proteins are involved in several processes: photosynthesis, RNA processing, protein translation and processing, metabolism of carbon, nitrogen end energy. These proteins might work cooperatively to reach an homeostatic equilibrium to overcome stress conditions

Synthetic and bio-artificial tactile sensing: a review

This paper reviews the state of the art of artificial tactile sensing, with a particular focus on bio-hybrid and fully-biological approaches. To this aim, the study of physiology of the human sense of touch and of the coding mechanisms of tactile information is a significant starting point, which is briefly explored in this review. Then, the progress towards the development of an artificial sense of touch are investigated. Artificial tactile sensing is analysed with respect to the possible approaches to fabricate the outer interface layer: synthetic skin versus bio-artificial skin. With particular respect to the synthetic skin approach, a brief overview is provided on various technologies and transduction principles that can be integrated beneath the skin layer. Then, the main focus moves to approaches characterized by the use of bio-artificial skin as an outer layer of the artificial sensory system. Within this design solution for the skin, bio-hybrid and fully-biological tactile sensing systems are thoroughly presented: while significant results have been reported for the development of tissue engineered skins, the development of mechanotransduction units and their integration is a recent trend that is still lagging behind, therefore requiring research efforts and investments. In the last part of the paper, application domains and perspectives of the reviewed tactile sensing technologies are discussed