Leaf microscopy applications in photosynthesis research: identifying the gaps.

Leaf imaging via microscopy has provided critical insights into research on photosynthesis at multiple junctures, from the early understanding of the role of stomata, through elucidating C4 photosynthesis via Kranz anatomy and chloroplast arrangement in single cells, to detailed explorations of diffusion pathways and light utilization gradients within leaves. In recent decades, the original two-dimensional (2D) explorations have begun to be visualized in three-dimensional (3D) space, revising our understanding of structure-function relationships between internal leaf anatomy and photosynthesis. In particular, advancing new technologies and analyses are providing fresh insight into the relationship between leaf cellular components and improving the ability to model net carbon fixation, water use efficiency, and metabolite turnover rate in leaves.

On the shape of cicada's wing leading-edge cross section.

An important role that the leading-edge cross-section shape plays in the wing flight performance is well known in aeronautics. However, little is known about the shape of the leading-edge cross section of an insect's wing and its contribution to remarkable qualities of insect flight. In this paper, we reveal, in the first time, the shape of the leading-edge cross section of a cicada's wing and analyze its variability along the wing.

Aerosol generation with various approaches to oxygenation in healthy volunteers in the emergency department.

Objectives: Health care workers experience an uncertain risk of aerosol exposure during patient oxygenation. To improve our understanding of these risks, we sought to measure aerosol production during various approaches to oxygenation in healthy volunteers in an emergency department.

Methods: This was a prospective study conducted in an empty patient room in an academic ED.

Contribution and consequences of xylem-transported CO assimilation for C plants.

Traditionally, leaves were thought to be supplied with CO for photosynthesis by the atmosphere and respiration. Recent studies, however, have shown that the xylem also transports a significant amount of inorganic carbon into leaves through the bulk flow of water. However, little is known about the dynamics and proportion of xylem-transported CO that is assimilated, vs simply lost to transpiration.

What is the fate of xylem-transported CO in Kranz-type C plants?

High concentrations of dissolved inorganic carbon in stems of herbaceous and woody C plants exit leaves in the dark. In the light, C species use a small portion of xylem-transported CO for leaf photosynthesis. However, it is not known if xylem-transported CO will exit leaves in the dark or be used for photosynthesis in the light in Kranz-type C plants.

Using multirate rapid A/C curves as a tool to explore new questions in the photosynthetic physiology of plants.

Steady-state photosynthetic CO responses (A/C curves) are used to assess environmental responses of photosynthetic traits and to predict future vegetative carbon uptake through modeling. The recent development of rapid A/C curves (RACiRs) permits faster assessment of these traits by continuously changing [CO ] around the leaf, and may reveal additional photosynthetic properties beyond what is practical or possible with steady-state methods. Gas exchange necessarily incorporates photosynthesis and (photo)respiration.

Using the rapid A-C response (RACiR) in the Li-Cor 6400 to measure developmental gradients of photosynthetic capacity in poplar.

The rapid A-C response (RACiR) technique alleviates limitations of measuring photosynthetic capacity by reducing the time needed to determine the maximum carboxylation rate (V ) and electron transport rate (J ) in leaves. Photosynthetic capacity and its relationships with leaf development are important for understanding ecological and agricultural productivity; however, our current understanding is incomplete. Here, we show that RACiR can be used in previous generation gas exchange systems (i.

Unsaturation of vapour pressure inside leaves of two conifer species.

Stomatal conductance (g) impacts both photosynthesis and transpiration, and is therefore fundamental to the global carbon and water cycles, food production, and ecosystem services. Mathematical models provide the primary means of analysing this important leaf gas exchange parameter. A nearly universal assumption in such models is that the vapour pressure inside leaves (e) remains saturated under all conditions.

The Sphagnome Project: enabling ecological and evolutionary insights through a genus-level sequencing project.

Considerable progress has been made in ecological and evolutionary genetics with studies demonstrating how genes underlying plant and microbial traits can influence adaptation and even 'extend' to influence community structure and ecosystem level processes. Progress in this area is limited to model systems with deep genetic and genomic resources that often have negligible ecological impact or interest. Thus, important linkages between genetic adaptations and their consequences at organismal and ecological scales are often lacking.

Inside out: efflux of carbon dioxide from leaves represents more than leaf metabolism.

High concentrations of inorganic carbon in the xylem, produced from root, stem, and branch respiration, travel via the transpiration stream and eventually exit the plant through distant tissues as CO2. Unlike previous studies that focused on the efflux of CO2 from roots and woody tissues, we focus on efflux from leaves and the potential effect on leaf respiration measurements. We labeled transported inorganic carbon, spanning reported xylem concentrations, with 13C and then manipulated transpiration rates in the dark in order to vary the rates of inorganic carbon supply to cut leaves from Brassica napus and Populus deltoides.

The rapid A-C response: photosynthesis in the phenomic era.

Phenotyping for photosynthetic gas exchange parameters is limiting our ability to select plants for enhanced photosynthetic carbon gain and to assess plant function in current and future natural environments. This is due, in part, to the time required to generate estimates of the maximum rate of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) carboxylation (V ) and the maximal rate of electron transport (J ) from the response of photosynthesis (A) to the CO concentration inside leaf air spaces (C ). To relieve this bottleneck, we developed a method for rapid photosynthetic carbon assimilation CO responses [rapid A-C response (RACiR)] utilizing non-steady-state measurements of gas exchange.

The carbon fertilization effect over a century of anthropogenic CO emissions: higher intracellular CO and more drought resistance among invasive and native grass species contrasts with increased water use efficiency for woody plants in the US Southwest.

From 1890 to 2015, anthropogenic carbon dioxide emissions have increased atmospheric CO concentrations from 270 to 400 mol mol . The effect of increased carbon emissions on plant growth and reproduction has been the subject of study of free-air CO enrichment (FACE) experiments. These experiments have found (i) an increase in internal CO partial pressure (c ) alongside acclimation of photosynthetic capacity, (ii) variable decreases in stomatal conductance, and (iii) that increases in yield do not increase commensurate with CO concentrations.

Why small fluxes matter: the case and approaches for improving measurements of photosynthesis and (photo)respiration.

Since its inception, the Farquhar et al. (1980) model of photosynthesis has been a mainstay for relating biochemistry to environmental conditions from chloroplast to global levels in terrestrial plants. Many variables could be assigned from basic enzyme kinetics, but the model also required measurements of maximum rates of photosynthetic electron transport (J max ), carbon assimilation (Vcmax ), conductance of CO2 into (g s ) and through (g m ) the leaf, and the rate of respiration during the day (R d ).

Evolution of photorespiration from cyanobacteria to land plants, considering protein phylogenies and acquisition of carbon concentrating mechanisms.

Photorespiration and oxygenic photosynthesis are intimately linked processes. It has been shown that under the present day atmospheric conditions cyanobacteria and all eukaryotic phototrophs need functional photorespiration to grow autotrophically. The question arises as to when this essential partnership evolved, i.

The arc mutants of Arabidopsis with fewer large chloroplasts have a lower mesophyll conductance.

Photosynthetic cells of most land plant lineages have numerous small chloroplasts even though most algae, and even the early diverging land plant group the hornworts, tend to have one or a few large chloroplasts. One constraint that small chloroplasts could improve is the resistance to CO2 diffusion from the atmosphere to the chloroplast stroma. We examined the mesophyll conductance (inverse of the diffusion resistance) of mutant Arabidopsis thaliana plants with one or only a few large chloroplasts per cell.

On-line stable isotope gas exchange reveals an inducible but leaky carbon concentrating mechanism in Nannochloropsis salina.

Carbon concentrating mechanisms (CCMs) are common among microalgae, but their regulation and even existence in some of the most promising biofuel production strains is poorly understood. This is partly because screening for new strains does not commonly include assessment of CCM function or regulation despite its fundamental role in primary carbon metabolism. In addition, the inducible nature of many microalgal CCMs means that environmental conditions should be considered when assessing CCM function and its potential impact on biofuels.

Spatio-temporal decoupling of stomatal and mesophyll conductance induced by vein cutting in leaves of Helianthus annuus.

Reduction of hydraulic conductance to the canopy has been shown to result in stomatal responses to limit transpiration. To test for similar responses to perturbations of the hydraulic network in leaves, we simultaneously measured leaf gas exchange with spatially explicit chlorophyll-a fluorescence and leaf temperature to examine the effects of cutting a primary leaf vein in Helianthus annuus. We repeated the leaf treatment at each of three different vapor pressure deficits and monitored the short-term dynamics of gas exchange following the treatment.

Targeted 13C enrichment of lipid and protein pools in the body reveals circadian changes in oxidative fuel mixture during prolonged fasting: a case study using Japanese quail.

Many animals undergo extended periods of fasting. During these fasts, animals oxidize a ratio of macronutrients dependent on the nutritional, energetic, and hydric requirements of the fasting period. In this study, we use Japanese quail (Coturnix coturnix japonica), a bird with natural intermediate fasting periods, to examine macronutrient use during a 6d fast.

The physiological basis for genetic variation in water use efficiency and carbon isotope composition in Arabidopsis thaliana.

Ecologists and physiologists have documented extensive variation in water use efficiency (WUE) in Arabidopsis thaliana, as well as association of WUE with climatic variation. Here, we demonstrate correlations of whole-plant transpiration efficiency and carbon isotope composition (δ(13)C) among life history classes of A. thaliana.

Simulating pH effects in an algal-growth hydrodynamics model(1).

Models and numerical simulations are relatively inexpensive tools that can be used to enhance economic competitiveness through operation and system optimization to minimize energy and resource consumption, while maximizing algal oil yield. This work uses modified versions of the U.S.

Rolled liverwort mats explain major Prototaxites features: Response to commentaries.

In volume 97(2) of the American Journal of Botany (pp. 268-275), we published an article entitled "Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats". Here, we respond to a letter and a commentary on our article in the present issue, welcoming this opportunity to continue the scientific dialogue about an issue that has long been stimulating and controversial.

The Arabidopsis thaliana aquaporin AtPIP1;2 is a physiologically relevant CO₂ transport facilitator.

Cellular exchange of carbon dioxide (CO₂) is of extraordinary importance for life. Despite this significance, its molecular mechanisms are still unclear and a matter of controversy. In contrast to other living organisms, plants are physiologically limited by the availability of CO₂.

Influence of diurnal variation in mesophyll conductance on modelled 13C discrimination: results from a field study.

Mesophyll conductance to CO(2) (g(m)) limits carbon assimilation and influences carbon isotope discrimination (Delta) under most environmental conditions. Current work is elucidating the environmental regulation of g(m), but the influence of g(m) on model predictions of Delta remains poorly understood. In this study, field measurements of Delta and g(m) were obtained using a tunable diode laser spectroscope coupled to portable photosynthesis systems.