Correction: Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform
[This corrects the article DOI: 10.1371/journal.pone.0168138.].
Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform
Pollen tubes are used as a model in the study of plant morphogenesis, cellular differentiation, cell wall biochemistry, biomechanics, and intra- and intercellular signaling. For a “systems-understanding” of the bio-chemo-mechanics of tip-polarized growth in pollen tubes, the need for a versatile, experimental assay platform for quantitative data collection and analysis is critical. We introduce a Lab-on-a-Chip (LoC) concept for high-throughput pollen germination and pollen tube guidance for parallelized optical and mechanical measurements. The LoC localizes a large number of growing pollen tubes on a single plane of focus with unidirectional tip-growth, enabling high-resolution quantitative microscopy. This species-independent LoC platform can be integrated with micro-/nano-indentation systems, such as the cellular force microscope (CFM) or the atomic force microscope (AFM), allowing for rapid measurements of cell wall stiffness of growing tubes. As a demonstrative example, we show the growth and directional guidance of hundreds of lily (Lilium longiflorum) and Arabidopsis (Arabidopsis thaliana) pollen tubes on a single LoC microscopy slide. Combining the LoC with the CFM, we characterized the cell wall stiffness of lily pollen tubes. Using the stiffness statistics and finite-element-method (FEM)-based approaches, we computed an effective range of the linear elastic moduli of the cell wall spanning the variability space of physiological parameters including internal turgor, cell wall thickness, and tube diameter. We propose the LoC device as a versatile and high-throughput phenomics platform for plant reproductive and development biology using the pollen tube as a model.
Discourse Forms and Processes in Indigenous Lowland South America: An Areal-Typological Perspective
▪ Abstract In indigenous lowland South America there are several discourse forms and processes that are shared by groups of people of distinct genetic linguistic affiliations; this leads us to posit this large region, which we label greater Amazonia, as a discourse area, a concept that parallels the notion of linguistic area. The discourse forms and processes we examine are ceremonial dialogue, dialogical performance, templatic ratifying, echo speech, ceremonial greeting, ritual wailing, evidentiality, speech reporting practices, parallelism, special languages, and shamanistic language use. We hypothesize that in lowland South America, discourse is the matrix for linguistic diffusion, i.e., that linguistic areas emerge within discourse areas. What we propose then is a discourse-centered approach to language change and history, parallel to a discourse-centered approach to language structure and use. Our survey includes a plea for a careful archiving of recorded and written materials dealing with lowland So...