Paleoenvironmental changes at treeline: a 6,500 year long pollen and stable isotope record

Thesis (M.S.) University of Alaska Fairbanks, 2001Combined pollen, macrofossil and stable-isotope records from two lakes in the sub-alpine zone of the north-central Alaska Range indicate significant changes in vegetation and lake productivity during the past 6̃750 ¹⁴C yrs BP. These changes are associated with neoglacial cooling and climate variations during the Little Ice-Age (LIA). Highest spruce densities occurred during a period from 5,000 ¹⁴C yrs BP and 2,500 ¹⁴C yrs BP and coincided with the onset of cooler and moister climate. The shifts in climate, which resulted in increased effective moisture levels in Central Alaska, possibly shifted the competitive balance towards spruce and against tundra taxa. Lake productivity declined as climate cooled. A brief episode of climate amelioration between 1,500 ¹⁴C yrs BP and 800 ¹⁴C yrs was followed by cooking events of the LIA which resulted in decreased spruce densities in the sub-alpine forest-tundra zone and a possible lowering in treeline at higher elevation

Institute of Northern Engineering 2006 Annual Report

MESSAGE FROM THE DIRECTOR -- OVERVIEW AND MISSION -- CENTER PROFILES -- ORGANIZATION & CENTER LEADERS -- ARCTIC ENERGY TECHNOLOGY DEVELOPMENT LABORATORY -- ALASKA UNIVERSITY TRANSPORTATION CENTER -- MINERAL INDUSTRY RESEARCH LABORATORY -- PETROLEUM DEVELOPMENT LABORATORY -- WATER & ENVIRONMENTAL RESEARCH CENTER -- INE GENERAL RESEARCH -- ACCOMPLISHMENTS 2006 -- GOALS 2007 -- RESOURCES, FUNDING, AND EXPENDITURE

Optogenetic activation of mGluR1 signaling in the cerebellum induces synaptic plasticity

Summary: Neuronal plasticity underlying cerebellar learning behavior is strongly associated with type 1 metabotropic glutamate receptor (mGluR1) signaling. Activation of mGluR1 leads to activation of the Gq/11 pathway, which is involved in inducing synaptic plasticity at the parallel fiber-Purkinje cell synapse (PF-PC) in form of long-term depression (LTD). To optogenetically modulate mGluR1 signaling we fused mouse melanopsin (OPN4) that activates the Gq/11 pathway to the C-termini of mGluR1 splice variants (OPN4-mGluR1a and OPN4-mGluR1b). Activation of both OPN4-mGluR1 variants showed robust Ca2+ increase in HEK cells and PCs of cerebellar slices. We provide the prove-of-concept approach to modulate synaptic plasticity via optogenetic activation of OPN4-mGluR1a inducing LTD at the PF-PC synapse in vitro. Moreover, we demonstrate that light activation of mGluR1a signaling pathway by OPN4-mGluR1a in PCs leads to an increase in intrinsic activity of PCs in vivo and improved cerebellum driven learning behavior

Cardiopulmonary response to inhalation of secondary organic aerosol derived from gas-phase oxidation of toluene

The biological response to inhalation of secondary organic aerosol (SOA) was determined in rodents exposed to SOA derived from the oxidation of toluene, a precursor emitted from anthropogenic sources. SOA atmospheres were produced to yield 300 µg·m^(−3) of particulate matter (PM) plus accompanying gases. Whole-body exposures were conducted in mice to assess both pulmonary and cardiovascular effects. ApoE^(−/−) mice were exposed for 7 days and measurements of TBARS and gene expression of heme-oxygenase-1 (HO-1), endothelin-1 (ET-1), and matrix metalloproteinase-9 (MMP-9) were made in aorta. Pulmonary inflammatory responses in both species were measured by bronchoalveolar lavage fluid (BALF) cell counts. No pulmonary inflammation was observed. A mild response was observed in mouse aorta for the upregulation of ET-1 and HO-1, with a trend for increased MMP-9 and TBARS, and. Overall, toluene-derived SOA revealed limited biological response compared with previous studies using this exposure protocol with other environmental pollutants