<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics"^^ . "Microfluidic devices allow precise control to manipulate fluids within micrometer sized channel\r\nnetworks. In single phase microfluidic systems where miscible fluids are infused, laminar flow\r\ncan be generated. This means liquid streams can flow parallel to each other without convective\r\nmixing. In two phase microfluidic systems where two immiscible fluids are infused, droplets are\r\ngenerated. Using this system, uniformly sized aqueous micro compartments can be generated in\r\noil. This dissertation describes the development of novel microfluidic devices based on single\r\nphase and two phase systems to monitor responsiveness of cells and organisms to different\r\nchemical cues. Firstly, the possibility to apply a specifically designed single-phase microfluidic\r\nchip to study zooplankton ecology has been demonstrated. Zooplankton perceive their\r\nsurrounding using chemical cues and rely on these cues for development and survival. However,\r\nwith the current rapid global climatic changes affecting the ocean chemistry, it is unclear on how\r\nplankton, which form the base of the marine food chain, are coping. So far, measurements on\r\nzooplankton ecology have been hampered by technical impracticalities of exposing actively\r\nswimming plankton species to different chemical conditions simultaneously while monitoring\r\ntheir behavior on an individual level. Using the microfluidic device, first measurements on\r\nbehavioral preferendum of zooplankton species to changes in pH and salinity could be made\r\nwith a precision that additionally allowed estimating the “responsiveness”, which is the\r\nminimum change in concentration required for the plankton to elicit a response, to an\r\nenvironmental stimulus. Platynereis dumerilii, cosmopolitan model plankton were more\r\nsensitive to changes in pH than salinity. In addition, comparing different species lead to the\r\nobservation that Euterpina acutifrons, a copepod species showed a narrower pH preferendum\r\nthan P.dumerilii. These measurements allow making predications on sensitive and resilient\r\nspecies. Furthermore, the ability to study the interaction of zooplankton with their prey and\r\npredators and perform functional studies on identifying cell types responsible for a sensory\r\nresponse has been demonstrated.\r\nFor cell-based screening assays however, the high-throughput offered by droplet-based systems\r\noutcompetes single-phase systems. But, generating chemical diversity in droplets that can allow\r\nscreening entire chemical libraries while being able to track the sample identity remains to be\r\ndemonstrated. Here a novel approach has been devised that allows generating sample barcoded\r\ncombinatorial mixtures. In addition the approach has been optimized to suit for screening rare\r\nvi\r\nand sensitive cells like mouse embryonic stem (mES) cells. The ability to maintain viable mES\r\ncells in droplets for a period of 48 h has been demonstrated and in addition the possibility to\r\ndifferentiate them by encapsulating them together with 10-8 M retinoic acid (RA) has been\r\nshown.\r\nLastly, a new microfluidic approach combining the advantages of single phase and two phase\r\nmicrofluidics has been described. This approach allows high-content cell-based screening with\r\nfreely accessible cells allowing regular tissue culture handling and potentially, immunostaining\r\nexperiments which are not possible when cells are encapsulated. To maximize the throughput\r\nper chip, chemicals were encapsulated in droplets and were allowed to locally diffuse through\r\nthe chip material to the cells. The usability of this approach has been demonstrated by localized\r\ninduction of GFP in tetracycline inducible HeLa-TRexTM cells.\r\nIn conclusion, different microfluidic approaches have been described in this thesis and used for\r\napplications ranging from analyzing cells to organisms. The good spatial resolution, precise\r\ncontrol over liquids, possibility of assays on the individual level and low cell number/reagent\r\nquantity requirement, enabled by microfluidics makes the devices an advantageous tool for\r\nbiological applications."^^ . "2016" . . . . . . . "Nirupama"^^ . "Ramanathan"^^ . "Nirupama Ramanathan"^^ . . . . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (PDF)"^^ . . . "Nirupama Ramanathan PhD thesis.pdf"^^ . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (Other)"^^ . . . . . . "small.jpg"^^ . . . "Monitoring the response of cells and organisms to different chemical cues using microfluidics (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #19143 \n\nMonitoring the response of cells and organisms to different chemical cues using microfluidics\n\n" . "text/html" . . . "500 Naturwissenschaften und Mathematik"@de . "500 Natural sciences and mathematics"@en . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .