Impact on Inpatient Length of Stay in Adults with Deep Partial-Thickness Burns: Comparing the Bioengineered Allogeneic Cellularized Construct Expanded-Access Trial with National Burn Repository Data.

Purpose: To investigate the effect of StrataGraft (bioengineered allogeneic cellularized construct [BACC]) treatment on inpatient length of stay (LOS) as an indicator of hospital resource utilization.

Patients And Methods: Data from the single-arm StrataCAT trial for adult patients with deep partial-thickness (DPT) burns who received BACC were compared with data from a matched external control arm comprising patients who received autografting for burn treatment from the National Burn Repository (NBR) during the same time period as StrataCAT. A matching, quasi-experimental approach was used to investigate the cause-and-effect relationship between BACC treatment and LOS (days).

Effects of alder- and salmon-derived nutrients on aquatic bacterial community structure and microbial community metabolism in subarctic lakes.

Alder (Alnus spp.) and Pacific salmon (Oncorhynchus spp.) provide key nutrient subsidies to freshwater systems.

Resilience and sensitivity of ecosystem carbon stocks to fire-regime change in Alaskan tundra.

Fire disturbance has increased in some tundra ecosystems due to anthropogenic climate change, with important ramifications for terrestrial carbon cycling. Assessment of the potential impact of fire-regime change on tundra carbon stocks requires long-term perspectives because tundra fires have been rare historically. Here we integrated the process-based Dynamic Organic Soil version of the Terrestrial Ecosystem Model with paleo-fire records to evaluate the responses of tundra carbon stocks to changes in fire return interval (FRI).

Divergent shrub-cover responses driven by climate, wildfire, and permafrost interactions in Arctic tundra ecosystems.

The expansion of shrubs across the Arctic tundra may fundamentally modify land-atmosphere interactions. However, it remains unclear how shrub expansion pattern is linked with key environmental drivers, such as climate change and fire disturbance. Here we used 40+ years of high-resolution (~1.

Exploring genomic variation associated with drought stress in populations.

Predicted increases in drought and heat stress will likely induce shifts in species bioclimatic envelopes. Genetic variants adapted to water limitation may prove pivotal for species response under scenarios of increasing drought. In this study, we aimed to explore this hypothesis by investigating genetic variation in 16 populations of black spruce () in relation to climate variables in Alaska.

Arctic and boreal paleofire records reveal drivers of fire activity and departures from Holocene variability.

Boreal forest and tundra biomes are key components of the Earth system because the mobilization of large carbon stocks and changes in energy balance could act as positive feedbacks to ongoing climate change. In Alaska, wildfire is a primary driver of ecosystem structure and function, and a key mechanism coupling high-latitude ecosystems to global climate. Paleoecological records reveal sensitivity of fire regimes to climatic and vegetation change over centennial-millennial time scales, highlighting increased burning concurrent with warming or elevated landscape flammability.

Ice-age persistence and genetic isolation of the disjunct distribution of larch in Alaska.

(eastern larch, tamarack) is a transcontinental North American conifer with a prominent disjunction in the Yukon isolating the Alaskan distribution from the rest of its range. We investigate whether in situ persistence during the last glacial maximum (LGM) or long-distance postglacial migration from south of the ice sheets resulted in the modern-day Alaskan distribution. We analyzed variation in three chloroplast DNA regions of 840 trees from a total of 69 populations (24 new sampling sites situated on both sides of the Yukon range disjunction pooled with 45 populations from a published source) and conducted ensemble species distribution modeling (SDM) throughout Canada and United States to hindcast the potential range of during the LGM.

Resilience of lake biogeochemistry to boreal-forest wildfires during the late Holocene.

Novel fire regimes are expected in many boreal regions, and it is unclear how biogeochemical cycles will respond. We leverage fire and vegetation records from a highly flammable ecoregion in Alaska and present new lake-sediment analyses to examine biogeochemical responses to fire over the past 5300 years. No significant difference exists in δC, %C, %N, C : N, or magnetic susceptibility between pre-fire, post-fire, and fire samples.

Invoking adaptation to decipher the genetic legacy of past climate change.

Persistence of natural populations during periods of climate change is likely to depend on migration (range shifts) or adaptation. These responses were traditionally considered discrete processes and conceptually divided into the realms of ecology and evolution. In a milestone paper, Davis and Shaw (2001) Science 292:673 argued that the interplay of adaptation and migration was central to biotic responses to Quaternary climate, but since then there has been no synthesis of efforts made to set up this research program.

Isotopic analysis on nanogram quantities of carbon from dissolved insect cuticle: a method for paleoenvironmental inferences.

Rationale: Carbon isotope (δ C ) data from arthropod cuticles provide invaluable information on past and present biogeochemical processes. However, such analyses typically require large sample sizes that may mask important variation in δ C values within or among species.

Methods: We have evaluated a spooling-wire microcombustion (SWiM) device and isotope ratio mass spectrometry (IRMS) to measure the δ C values of carbon dissolved from the cuticle of chitinous aquatic zooplankton.

MicroRNA-185-5p mediates regulation of SREBP2 expression by hepatitis C virus core protein.

Aim: To investigate the molecular mechanism for regulation of cholesterol metabolism by hepatitis C virus (HCV) core protein in HepG2 cells.

Methods: HCV genotype 1b core protein was cloned and expressed in HepG2 cells. The cholesterol content was determined after transfection.

Charcoal reflectance reveals early holocene boreal deciduous forests burned at high intensities.

Wildfire size, frequency, and severity are increasing in the Alaskan boreal forest in response to climate warming. One of the potential impacts of this changing fire regime is the alteration of successional trajectories, from black spruce to mixed stands dominated by aspen, a vegetation composition not experienced since the early Holocene. Such changes in vegetation composition may consequently alter the intensity of fires, influencing fire feedbacks to the ecosystem.

Molecular phylogeography and ecological niche modelling of a widespread herbaceous climber, Tetrastigma hemsleyanum (Vitaceae): insights into Plio-Pleistocene range dynamics of evergreen forest in subtropical China.

Warm-temperate evergreen (WTE) forest represents the typical vegetation type of subtropical China, but how its component species responded to past environmental change remains largely unknown. Here, we reconstruct the evolutionary history of Tetrastigma hemsleyanum, an herbaceous climber restricted to the WTE forest. Twenty populations were genotyped using chloroplast DNA sequences and nuclear microsatellite loci to assess population structure and diversity, supplemented by phylogenetic dating, ancestral area reconstructions and ecological niche modeling (ENM) of the species distributions during the Last Glacial Maximum (LGM) and at present.

Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years.

Wildfire activity in boreal forests is anticipated to increase dramatically, with far-reaching ecological and socioeconomic consequences. Paleorecords are indispensible for elucidating boreal fire regime dynamics under changing climate, because fire return intervals and successional cycles in these ecosystems occur over decadal to centennial timescales. We present charcoal records from 14 lakes in the Yukon Flats of interior Alaska, one of the most flammable ecoregions of the boreal forest biome, to infer causes and consequences of fire regime change over the past 10,000 y.

Ecological facilitation between two epiphytes through drought mitigation in a subtropical rainforest.

Positive species interactions (facilitation) play an important role in shaping the structures and species diversity of ecological communities, particularly under stressful environmental conditions. Epiphytes in rainforests often grow in multiple-species clumps, suggesting interspecies facilitation. However, little is known about the patterns and mechanisms of epiphyte co-occurrence.

Climatic and land cover influences on the spatiotemporal dynamics of Holocene boreal fire regimes.

Although recent climatic warming has markedly increased fire activity in many biomes, this trend is spatially heterogeneous. Understanding the patterns and controls of this heterogeneity is important for anticipating future fire regime shifts at regional scales and for developing land management policies. To assess climatic and land cover controls on boreal forest fire regimes, we conducted macroscopic-charcoal analysis of sediment cores and GIS analysis of landscape variation in south-central Alaska, USA.

Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa.

Fires burning the vast grasslands and savannas of Africa significantly influence the global carbon cycle. Projecting the impacts of future climate change on fire-mediated biogeochemical processes in these dry tropical ecosystems requires understanding of how various climate factors influence regional fire regimes. To examine climate-vegetation-fire linkages in dry savanna, we conducted macroscopic and microscopic charcoal analysis on the sediments of the past 25 000 years from Lake Challa, a deep crater lake in equatorial East Africa.

Nonlinear response of summer temperature to Holocene insolation forcing in Alaska.

Regional climate responses to large-scale forcings, such as precessional changes in solar irradiation and increases in anthropogenic greenhouse gases, may be nonlinear as a result of complex interactions among earth system components. Such nonlinear behaviors constitute a major source of climate "surprises" with important socioeconomic and ecological implications. Paleorecords are key for elucidating patterns and mechanisms of nonlinear responses to radiative forcing, but their utility has been greatly limited by the paucity of quantitative temperature reconstructions.

Direction and extent of organelle DNA introgression between two spruce species in the Qinghai-Tibetan Plateau.

A recent model has shown that, during range expansion of one species in a territory already occupied by a related species, introgression should take place preferentially from the resident species towards the invading species and genome components experiencing low rates of gene flow should introgress more readily than those experiencing high rates of gene flow. Here, we use molecular markers from two organelle genomes with contrasted rates of gene flow to test these predictions by examining genetic exchanges between two morphologically distinct spruce Picea species growing in the Qinghai-Tibetan Plateau. The haplotypes from both mitochondrial (mt) DNA and chloroplast (cp) DNA cluster into two distinct lineages that differentiate allopatric populations of the two species.

Phylogeographic history of white spruce during the last glacial maximum: uncovering cryptic refugia.

Although a recent study of white spruce using chloroplast DNA uncovered the presence of a glacial refuge in Alaska, chloroplast failed to provide information on the number or specific localities of refugia. Recent studies have demonstrated the utility of nuclear microsatellites to refine insights into postglacial histories. The greater relative rate of mutation may allow finer scale resolution of historic dynamics, including the number, location, and sizes of refugia.

Radiocarbon dating of individual lignin phenols: a new approach for establishing chronology of late quaternary lake sediments.

The reliability of chronology is a prerequisite for meaningful paleoclimate reconstructions from sedimentary archives. The conventional approach of radiocarbon dating bulk organic carbon in lake sediments is often hampered by the old carbon effect, i.e.

Linking sediment-charcoal records and ecological modeling to understand causes of fire-regime change in boreal forests.

Interactions between vegetation and fire have the potential to overshadow direct effects of climate change on fire regimes in boreal forests of North America. We develop methods to compare sediment-charcoal records with fire regimes simulated by an ecologica model, ALFRESCO (Alaskan Frame-based Ecosystem Code) and apply these methods to evaluate potential causes of a mid-Holocene fire-regime shift in boreal forests of the south-central Brooks Range, Alaska, U.S.

Patterns and drivers of Holocene vegetational change near the prairie-forest ecotone in Minnesota: revisiting McAndrews' transect.

Holocene vegetational dynamics along the prairie-forest border of Minnesota were first documented in McAndrews' classic work. Despite numerous subsequent paleo-studies, a number of questions remain unanswered about the vegetation history of the region. Here, pollen, stable-isotope, mineral, and charcoal data are described from three lakes near McAndrews' sites.