Method for Flow Measurement in Microfluidic Channels Based on Electrical Impedance Spectroscopy

We have developed and characterized two novel micro flow sensors based on measuring the electrical impedance of the interface between the flowing liquid and metallic electrodes embedded on the channel walls. These flow sensors are very simple to fabricate and use, are extremely compact and can easily be integrated into most microfluidic systems. One of these devices is a micropore with two tantalum/platinum electrodes on its edges; the other is a micro channel with two tantalum /platinum electrodes placed perpendicular to the channel on its walls. In both sensors the flow rate is measured via the electrical impedance between the two metallic electrodes, which is the impedance of two metal-liquid junctions in series. The dependency of the metal-liquid junction impedance on the flow rate of the liquid has been studied. The effects of different parameters on the sensor's outputs and its noise behavior are investigated. Design guidelines are extracted and applied to achieve highly sensitive micro flow sensors with low noise.Comment: 11 pages, 7 figure

The evolution of the plastid chromosome in land plants: gene content, gene order, gene function

This review bridges functional and evolutionary aspects of plastid chromosome architecture in land plants and their putative ancestors. We provide an overview on the structure and composition of the plastid genome of land plants as well as the functions of its genes in an explicit phylogenetic and evolutionary context. We will discuss the architecture of land plant plastid chromosomes, including gene content and synteny across land plants. Moreover, we will explore the functions and roles of plastid encoded genes in metabolism and their evolutionary importance regarding gene retention and conservation. We suggest that the slow mode at which the plastome typically evolves is likely to be influenced by a combination of different molecular mechanisms. These include the organization of plastid genes in operons, the usually uniparental mode of plastid inheritance, the activity of highly effective repair mechanisms as well as the rarity of plastid fusion. Nevertheless, structurally rearranged plastomes can be found in several unrelated lineages (e.g. ferns, Pinaceae, multiple angiosperm families). Rearrangements and gene losses seem to correlate with an unusual mode of plastid transmission, abundance of repeats, or a heterotrophic lifestyle (parasites or myco-heterotrophs). While only a few functional gene gains and more frequent gene losses have been inferred for land plants, the plastid Ndh complex is one example of multiple independent gene losses and will be discussed in detail. Patterns of ndh-gene loss and functional analyses indicate that these losses are usually found in plant groups with a certain degree of heterotrophy, might rendering plastid encoded Ndh1 subunits dispensable

Role of T Cell Recruitment and Chemokine-Regulated Intra-Graft T Cell Motility Patterns in Corneal Allograft Rejection

Keratoplasty is the primary treatment to cure blindness due to corneal opacification. However, immune‐mediated rejection remains the leading cause of keratoplasty failure. Here, we utilize an in vivo imaging approach to monitor, track, and characterize in real‐time the recruitment of GFP‐labeled allo‐specific activated (Bonzo) T cells during corneal allograft rejection. We show that the recruitment of effector T cells to the site of transplantation determined the fate of corneal allografts, and that local intra‐graft production of CCL5 and CXCL9/10 regulated motility patterns of effector T cells in situ, and correlated with allograft rejection. We also show that different motility patterns associate with distinct in vivo phenotypes (round, elongated, and ruffled) of graft‐infiltrating effector T cells with varying proportions during progression of rejection. The ruffled phenotype was characteristic of activated effectors T cells and predominated during ongoing rejection, which associated with significantly increased T cell dynamics within the allografts. Importantly, CCR5/CXCR3 blockade decreased the motility, size, and number of infiltrating T cells and significantly prolonged allograft survival. Our findings indicate that chemokines produced locally within corneal allografts play an important role in the in situ activation and dynamic behavior of infiltrating effector T cells, and may guide targeted interventions to promote graft survival. The authors show that chemokines produced locally within corneal allografts play an important role in the in situ activation and dynamic behavior of infiltrating effector T cells that may guide antichemokine localized interventions to promote corneal allograft survival after transplantation