Contrasting Summertime Trends in Vehicle Combustion Efficiency in Los Angeles, CA and Salt Lake City, UT.

Policy interventions and technological advances are mitigating emissions of air pollutants from motor vehicles. As a result, vehicle fleets are expected to progressively combust fuel more efficiently, with a declining ratio of carbon monoxide to carbon dioxide (CO/CO) in their emissions. We assess trends in traffic combustion efficiency in Los Angeles (LA) and Salt Lake City (SLC) by measuring changes in summertime on-road CO/CO between 2013 and 2021 using mobile observations.

Intensive leaf cooling promotes tree survival during a record heatwave.

Increasing heatwaves are threatening forest ecosystems globally. Leaf thermal regulation and tolerance are important for plant survival during heatwaves, though the interaction between these processes and water availability is unclear. Genotypes of the widely distributed foundation tree species were studied in a controlled common garden during a record summer heatwave-where air temperature exceeded 48 °C.

Tradeoffs between leaf cooling and hydraulic safety in a dominant arid land riparian tree species.

Leaf carbon gain optimization in hot environments requires balancing leaf thermoregulation with avoiding excessive water loss via transpiration and hydraulic failure. The tradeoffs between leaf thermoregulation and transpirational water loss can determine the ecological consequences of heat waves that are increasing in frequency and intensity. We evaluated leaf thermoregulation strategies in warm- (>40°C maximum summer temperature) and cool-adapted (<40°C maximum summer temperature) genotypes of the foundation tree species, Populus fremontii, using a common garden near the mid-elevational point of its distribution.

Episodic defoliation rapidly reduces starch but not soluble sugars in an invasive shrub, Tamarix spp.

Premise: Plants rely on pools of internal nonstructural carbohydrates (NSCs: soluble sugars plus starch) to support metabolism, growth, and regrowth of tissues damaged from disturbance such as foliage herbivory. However, impacts of foliage herbivory on the quantity and composition of NSC pools in long-lived woody plants are currently unclear. We implemented a controlled defoliation experiment on mature Tamarix spp.

Repeated Vaginal Exposures to the Common Cosmetic and Household Preservative Methylisothiazolinone Induce Persistent, Mast Cell-Dependent Genital Pain in ND4 Mice.

A history of allergies doubles the risk of vulvodynia-a chronic pain condition of unknown etiology often accompanied by increases in numbers of vulvar mast cells. We previously established the biological plausibility of this relationship in mouse models where repeated exposures to the allergens oxazolone or dinitrofluorobenzene on the labiar skin or inside the vaginal canal of ND4 Swiss Webster outbred mice led to persistent tactile sensitivity and local increases in mast cells. In these models, depletion of mast cells alleviated pain.

Does sexual dimorphism predispose dioecious riparian trees to sex ratio imbalances under climate change?

Environmental changes have resulted in significant declines in native riparian forests that are comprised largely of dioecious tree taxa, including boxelder and iconic cottonwood/willow gallery forests. Dioecious species may be especially vulnerable to the effects of climate change given that they often exhibit skewed sex ratios that are reinforced by physiological and morphological specialization of each sex to specific microhabitats. A comprehensive data synthesis suggests that male individuals of boxelder and cottonwood taxa have a higher representation on dry microhabitats than females and are less physiologically sensitive to increased aridity than co-occurring females.

Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth.

Cities are concentrated areas of CO emissions and have become the foci of policies for mitigation actions. However, atmospheric measurement networks suitable for evaluating urban emissions over time are scarce. Here we present a unique long-term (decadal) record of CO mole fractions from five sites across Utah's metropolitan Salt Lake Valley.

Can local adaptation explain varying patterns of herbivory tolerance in a recently introduced woody plant in North America?

Patterns of woody-plant mortality have been linked to global-scale environmental changes, such as extreme drought, heat stress, more frequent and intense fires, and episodic outbreaks of insects and pathogens. Although many studies have focussed on survival and mortality in response to specific physiological stresses, little attention has been paid to the role of genetic heritability of traits and local adaptation in influencing patterns of plant mortality, especially in non-native species. spp.

Resolving distinct genetic regulators of tomato leaf shape within a heteroblastic and ontogenetic context.

Leaf shape is mutable, changing in ways modulated by both development and environment within genotypes. A complete model of leaf phenotype would incorporate the changes in leaf shape during juvenile-to-adult phase transitions and the ontogeny of each leaf. Here, we provide a morphometric description of >33,000 leaflets from a set of tomato (Solanum spp) introgression lines grown under controlled environment conditions.

iTILLING: personalized mutation screening.

One powerful approach to studying gene function is to analyze the phenotype of an organism carrying a mutant allele of a gene of interest. In order to use this experimental approach, one must have the ability to easily isolate individual organisms carrying desired mutations. A widely used method for accomplishing this task in plants and other organisms is a procedure called TILLING.

Deletion of a tandem gene family in Arabidopsis: increased MEKK2 abundance triggers autoimmunity when the MEKK1-MKK1/2-MPK4 signaling cascade is disrupted.

An Arabidopsis thaliana mitogen-activated protein (MAP) kinase cascade composed of MEKK1, MKK1/MKK2, and MPK4 was previously described as a negative regulator of defense response. MEKK1 encodes a MAP kinase kinase kinase and is a member of a tandemly duplicated gene family with MEKK2 and MEKK3. Using T-DNA insertion lines, we isolated a novel deletion mutant disrupting this gene family and found it to be phenotypically wild-type, in contrast with the mekk1 dwarf phenotype.

Ice-Cap: a method for growing Arabidopsis and tomato plants in 96-well plates for high-throughput genotyping.

It is becoming common for plant scientists to develop projects that require the genotyping of large numbers of plants. The first step in any genotyping project is to collect a tissue sample from each individual plant. The traditional approach to this task is to sample plants one-at-a-time.

Calibration of thermal dissipation sap flow probes for ring- and diffuse-porous trees.

Thermal dissipation probes (the Granier method) are routinely used in forest ecology and water balance studies to estimate whole-tree transpiration. This method utilizes an empirically derived equation to measure sap flux density, which has been reported as independent of wood characteristics. However, errors in calculated sap flux density may occur when large gradients in sap velocity occur along the sensor length or when sensors are inserted into non-conducting wood.

iTILLING: a personalized approach to the identification of induced mutations in Arabidopsis.

TILLING (for Targeting Induced Local Lesions IN Genomes) is a well-established method for identifying plants carrying point mutations in genes of interest. A traditional TILLING project requires a significant investment of time and resources to establish the mutant population and screening infrastructure. Here, we describe a modified TILLING procedure that substantially reduces the investment needed to perform mutation screening.

Wood anatomy constrains stomatal responses to atmospheric vapor pressure deficit in irrigated, urban trees.

Plant transpiration is strongly constrained by hydraulic architecture, which determines the critical threshold for cavitation. Because species vary greatly in vulnerability to cavitation, hydraulic limits to transpiration and stomatal conductance have not generally been incorporated into ecological and climate models. We measured sap flow, leaf transpiration, and vulnerability to cavitation of a variety of tree species in a well-irrigated but semi-arid urban environment in order to evaluate the generality of stomatal responses to high atmospheric vapor pressure deficit (D).

Evaluation of centrifugal methods for measuring xylem cavitation in conifers, diffuse- and ring-porous angiosperms.

A centrifugal method is used to measure 'vulnerability curves' which show the loss of hydraulic conductivity in xylem by cavitation. Until recently, conductivity was measured between bouts of centrifugation using a gravity-induced head. Now, conductivity can be measured during centrifugation.

Mutational evidence that the Arabidopsis MAP kinase MPK6 is involved in anther, inflorescence, and embryo development.

Loss-of-function, dominant-negative, and change-of-function genetic approaches were used to investigate the role played by the Arabidopsis mitogen-activated protein (MAP) kinase MPK6 throughout development. Plants homozygous for T-DNA null alleles of MPK6 displayed reduced male fertility and abnormal anther development. In addition, a portion of the seed produced by mpk6 plants was found to contain embryos that had burst out of their seed coats.