An Improve Naked Mole Rat Trap, Group III

This project attempts to improve on Dr. Stan Braude’s current Naked Mole Rat trap design. Dr. Braude currently uses his trap to catch and tag naked mole rats for his research. While Dr. Braude is happy with his current trap, he designed them himself over twenty years ago, and believes that they can be improved and modernized for increased ease and convenience. The key project goal is to deliver an improved trap to Dr. Braude that will meet his needs. The modifications that this project will attempt to deliver are a repeatable, solar powered trap that is compatible with his current design

Benthic-Pelagic Links and Rocky Intertidal Communities: Bottom-Up Effects on Top-Down Control?

Insight into the dependence of benthic communities on biological and physical processes in nearshore pelagic environments, long considered a ``black box,'' has eluded ecologists. In rocky intertidal communities at Oregon coastal sites 80 km apart, differences in abundance of sessile invertebrates, herbivores, carnivores, and macrophytes in the low zone were not readily explained by local scale differences in hydrodynamic or physical conditions (wave forces, surge flow, or air temperature during low tide). Field experiments employing predator and herbivore manipulations and prey transplants suggested top-down (predation, grazing) processes varied positively with bottom-up processes (growth of filter-feeders, prey recruitment), but the basis for these differences was unknown. Shore-based sampling revealed that between-site differences were associated with nearshore oceanographic conditions, including phytoplankton concentration and productivity, particulates, and water temperature during upwelling. Further, samples taken at 19 sites along 380 km of coastline suggested that the differences documented between two sites reflect broader scale gradients of phytoplankton concentration. Among several alternative explanations, a coastal hydrodynamics hypothesis, reflecting mesoscale (tens to hundreds of kilometers) variation in the interaction between offshore currents and winds and continental shelf bathymetry, was inferred to be the primary underlying cause. Satellite imagery and offshore chlorophyll-a samples are consistent with the postulated mechanism. Our results suggest that benthic community dynamics can be coupled to pelagic ecosystems by both trophic and transport linkages.KEYWORDS: scale, productivity, currents, upwelling, community structureThis is the publisher’s final pdf. The published article is copyrighted by the National Academy of Sciences of the United States of America and can be found at: http://www.pnas.org

Rocky intertidal oceanography: an association between community structure and nearshore phytoplankton concentration

On Oregon coastal rocky shores, filter‐feeders were relatively abundant and macrophytes were relatively scarce at Strawberry Hill, whereas opposite abundance patterns occurred at Boiler Bay. To determine whether nearshore oceanographic differences were associated with these patterns, we made shore‐based measurements of nutrient and Chl a concentrations. We used a three‐level nested design to identify ecologically appropriate sampling scales: “site” (10s of km), “bench” nested within site (100s of m), and “location” nested within bench (10s of m). Nutrients varied inconsistently but Chl a was consistently higher at Strawberry Hill. For Chl a, site explained ∼70% of the variance, whereas bench and location explained <20%. For nutrients, site and bench explained most of the variance, but neither was consistently more important. The data tentatively suggest that nutrient levels are weakly related to the between‐site ecological differences. In addition to the between‐site differences, Chl a changed seasonally, with maximum levels in summer. For nutrients, temporal changes were more complex, with highest levels tending to occur in late summer and autumn. No nutrient, however, was scarce enough at either site to limit phytoplankton growth, with the possible exception of nitrate in June. These results were consistent with the hypothesis that nearshore phytoplankton standing stock, a bottom‐up factor, could underlie differences in rocky intertidal community structure

Haematopoietic stem and progenitor cells from human pluripotent stem cells

A variety of tissue lineages can be differentiated from pluripotent stem cells by mimicking embryonic development through stepwise exposure to morphogens, or by conversion of one differentiated cell type into another by enforced expression of master transcription factors. Here, to yield functional human haematopoietic stem cells, we perform morphogen-directed differentiation of human pluripotent stem cells into haemogenic endothelium followed by screening of 26 candidate haematopoietic stem-cell-specifying transcription factors for their capacity to promote multi-lineage haematopoietic engraftment in mouse hosts. We recover seven transcription factors (ERG, HOXA5, HOXA9, HOXA10, LCOR, RUNX1 and SPI1) that are sufficient to convert haemogenic endothelium into haematopoietic stem and progenitor cells that engraft myeloid, B and T cells in primary and secondary mouse recipients. Our combined approach of morphogen-driven differentiation and transcription-factor-mediated cell fate conversion produces haematopoietic stem and progenitor cells from pluripotent stem cells and holds promise for modelling haematopoietic disease in humanized mice and for therapeutic strategies in genetic blood disorders