Chemosensory afference in the tentacle nerve of Lymnaea stagnalis

Although the neural control of behavior has been extensively studied in gastropods, basic gaps remain in our understanding of how sensory stimuli are processed. In particular, there is only patchy evidence regarding the functional roles of sense organs and the extensive peripheral nervous system they contain. Our goal was to use extracellular electrophysiological recordings to confirm the chemosensory role of the tentacles in the great pond snail, Lymnaea stagnalis. Employing a special twin-channel suction electrode to improve signal-to-noise ratio, we applied three food odors (derived from earthworm-based food pellets, algae-based pellets, and fresh lettuce) to a reduced preparation of the tentacle while recording neuronal activity in the tentacle nerve. Responses were assessed by comparing average spike frequencies produced in response to saline flow with and without odors. We report stronger neuronal responses to earthworm-based food odors and weaker responses to algae-based food odors. There were no clear neuronal responses produced when lettuce food odor or control saline was applied to the tentacle. Overall, our results provide strong evidence for the chemosensory role of the tentacles in navigation behavior by L. stagnalis. Although it is unclear whether the differences in neuronal responses to different odors are a technical consequence of our recording system or a genuine feature of the snail sensory system, these results are a useful foundation for further study of peripheral nervous system function in gastropods.     

A gel-free approach in vascular smooth muscle cell proteome: perspectives for a better insight into activation

Background  

The use of chromatography coupled with mass spectrometry (MS) analysis is a powerful approach to identify proteins, owing to its capacity to fractionate molecules according to different chemical features. The first protein expression map of vascular smooth muscle cells (VSMC) was published in 2001 and since then other papers have been produced. The most detailed two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) map was presented by Mayr et al who identified 235 proteins, corresponding to the 154 most abundant unique proteins in mouse aortic VSMC. A chromatographic approach aimed at fractionating the VSMC proteome has never been used before.     

Proteomics changes in adhesion molecules: a driving force for vascular smooth muscle cell phenotypic switch

Vascular smooth muscle cells (VSMCs), if activated by growth factors as a consequence of vessel injuries, acquire the ability to proliferate and migrate thus contributing to the formation of neointima and atherosclerotic plaque. In this study, a gel-free and label-free proteomic approach was proposed to highlight factors modulated during VSMC activation. Twenty proteins, differentially expressed between quiescent and activated cells, were identified. A constellation of elements, that move together and are closely and functionally related, was visualized. The great majority of them are involved in cell migration and in adhesion formation, suggesting a pivotal role of these protein complexes on the phenotypic modulation. This study represents a first step to ascertain the precise actors of cell activation, their roles and interactions.     

Sensing scaffolds to monitor cellular activity using impedance measurements

Scaffolds are cell adhesive matrices for the realisation of tissue constructs. Here we describe how scaffolds for tissue engineering can also be used as sensors for monitoring cellular activity such as adhesion and spreading. Carbon nanotube polymer composites were fabricated into membranes and scaffolds with electro-conductive properties. Impedance techniques were used to measure the effects of media and cell cultures on composite membranes and the results were analysed using lumped parameter models. We show that protein adhesion can be distinguished from cell adhesion as the impedance changes are much smaller for the latter (5%). In the presence of cells, impedance changes are of the order of 40% and can be correlated with adhesion, spreading and changes in cell density.     

Advances in microbial culturing conditions to activate silent biosynthetic gene clusters for novel metabolite production

Journal of Industrial Microbiology & Biotechnology - Natural products (NPs) produced by bacteria and fungi are often used as therapeutic agents due to their complex structures and wide range of...