Effects of isoprene on the ozonolysis of Δ3-carene and ß-caryophyllene: Mechanisms of secondary organic aerosol formation and cross-dimerization.

Elucidating the mutual effects between the different volatile organic compounds (VOCs) is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols (SOA). Here, the mixed VOCs experiments of isoprene and Δ3-carene/ß-caryophyllene were carried out in the presence of O3 using an indoor smog chamber. The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer, online vacuum ultraviolet free electron laser (VUV-FEL) photoionization aerosol mass spectrometry, and quantum chemical calculations. The results indicate that the suppression effect of isoprene on the ozonolysis of Δ3-carene and ß-caryophyllene shows fluctuating and monotonous trends, respectively. The carbon content of the precursor could be the main factor for regulating the strength of the suppression effect. Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed, which enrich the category of VOC oxidation products. Meanwhile, a new dimerization mechanism of the RO2 + R'O2 reaction is suggested, which offers an intriguing perspective on the gas phase formation process of particle phase accretion products. The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures, especially nearby the emission origins.

Long-term contributions of VOC sources and their link to ozone pollution in Bronx, New York City.

Changes in energy and environmental policies along with changes in the energy markets of New York State over the past two decades, have spurred interest in evaluating their impacts on emissions from various energy generation sectors. This study focused on quantifying these effects on VOC (volatile organic compounds) emissions and their subsequent impacts on air quality within the New York City (NYC) metropolitan area. NYC is an EPA nonattainment region for ozone (O3) and likely is a VOC limited region. NYC has a complex coastal topography and meteorology with low-level jets and sea/bay/land breeze circulation associated with heat waves, leading to summertime O3 exceedances and formation of secondary organic aerosol (SOA). To date, no comprehensive source apportionment studies have been done to understand the contributions of local and long-range sources of VOCs in this area. This study applied an improved Positive Matrix Factorization (PMF) methodology designed to incorporate atmospheric dispersion and photochemical reaction losses of VOCs to provide improved apportionment results. Hourly measurements of VOCs were obtained from a Photochemical Assessment Monitoring Station located at an urban site in the Bronx from 2000 to 2021. The study further explores the role of VOC sources in O3 and SOA formation and leverages advanced machine learning tools, XGBoost and SHAP algorithms, to identify synergistic interactions between sources and provided VOC source impacts on ambient O3 concentrations. Isoprene demonstrated a substantial influence in the source contribution of the biogenic factor, emphasizing its role in O3 formation. Notable contributions from anthropogenic emissions, such as fuel evaporation and various industrial processes, along with significant traffic-related sources that likely contribute to SOA formation, underscore the combined impact of natural and human-made sources on O3 pollution. Findings of this study can assist regulatory agencies in developing appropriate policy and management initiatives to control O3 pollution in NYC.

Characterization of the N5-dimethylallyl-FMN Intermediate in the Biosynthesis of Prenylated-FMN Catalyzed by UbiX.

Prenylated-FMN (prFMN) is the cofactor used by the UbiD-like family of decarboxylases that catalyzes the decarboxylation of various aromatic and unsaturated carboxylic acids. prFMN is synthesized from reduced FMN and dimethylallyl phosphate (DMAP) by a specialized prenyl transferase, UbiX. UbiX catalyzes the sequential formation of two bonds, the first between N5 of the flavin and C1 of DMAP, and the second between C6 of the flavin and C3 of DMAP. We have examined the reaction of UbiX with both FMN and riboflavin. Although UbiX converts FMN to prFMN, we show that significant amounts of the N5-dimethylallyl-FMN intermediate are released from the enzyme during catalysis. With riboflavin as the substrate, UbiX catalyzes only a partial reaction, resulting in only N5-dimethylallyl-riboflavin being formed. Purification of the N5-dimethylallyl-FMN adduct allowed its structure to be verified by 1H NMR spectroscopy and its reactivity to be investigated. Surprisingly, whereas reduced prFMN oxidizes in seconds to form the stable prFMN semiquinone radical when exposed to air, N5-dimethylallyl-FMN oxidizes much more slowly over several hours; in this case, oxidation is accompanied by spontaneous hydrolysis to regenerate FMN. These studies highlight the important contribution that cyclization of the prenyl-derived ring of prFMN makes to the cofactor's biological activity.

Hysteresis-Free Temperature Sensing with Printable Electronic Skins Made of Liquid Polyisoprene/CNTs.

Developing an electronic skin (e-skin) is becoming popular due to its capability to mimic human skin's ability to detect various stimuli. Mostly, such skins are tactile-based sensors. However, the exploration of nontactile-based sensing capability in the e-skin is still in a nascent stage. Herein, we report an approach toward developing electrical hysteresis- and cross-interference-free nontactile e-skin using liquid polyisoprene with an ultralow concentration of multiwalled carbon nanotubes (ϕ = 0.006 volume fraction) by leveraging the stencil printing technique. The impact of cross-linking the samples was studied. Uncross-linked samples demonstrated higher electrical conductivity than the cross-linked samples. A coarse-grained phenomenological model with molecular dynamics simulation was utilized to investigate filler network formation and percolation that dictate the conductivity of uncross-linked and cross-linked samples. Simulation studies supported the fidelity of the experimental findings. The uncross-linked e-skin demonstrated a higher temperature sensitivity (-1.103%/°C) than the cross-linked e-skin (-0.320%/°C) in the thermal conduction mode. Despite the superior sensitivity of the uncross-linked e-skin, the cross-linked systems demonstrated superior cyclic stability (35 thermal cycles), ensuring reliable sensor readings over extended usage. Judicious choice of encapsulant warranted the cross-linked e-skin sensor to nullify the impact of moisture on signal output, thereby providing cross-interference-free results. The optimized e-skin sample retained a similar thermal sensitivity even when used in the nontactile mode. From the application purview, the utility of the developed sensor was tested successfully for nontactile sensing of human body temperature. Additionally, the sensor was utilized to determine the respiratory profile by integrating the developed sensor into a wearable mask. This study advances nontactile e-skin-based sensing technology and opens new avenues for creating wearable and IoT devices for healthcare and human-machine interactions.

Optimizing Archaeal Lipid Biosynthesis in Escherichia coli.

Membrane lipid chemistry is remarkably different in archaea compared with bacteria and eukaryotes. In the evolutionary context, this is also termed the lipid divide and is reflected by distinct biosynthetic pathways. Contemporary organisms have almost without exception only one type of membrane lipid. During early membrane evolution, mixed membrane stages likely occurred, and it was hypothesized that the instability of such mixtures was the driving force for the lipid divide. To examine the compatibility between archaeal and bacterial lipids, the bacterium Escherichia coli has been engineered to contain both types of lipids with varying success. Only limited production of archaeal lipid archaetidylethanolamine was achieved. Here, we substantially increased its production in E. coli by overexpression of an archaeal phosphatidylserine synthase needed for ethanolamine headgroup attachment. Furthermore, we introduced a synthetic isoprenoid utilization pathway to increase the supply of isopentenyl-diphosphate and dimethylallyl diphosphate. This improved archaeal lipid production substantially. The archaeal phospholipids also served as a substrate for the E. coli cardiolipin synthase, resulting in archaeal and novel hybrid archaeal/bacterial cardiolipin species not seen in living organisms before. Growth of the E. coli strain with the mixed membrane shows an enhanced sensitivity to the inhibitor of fatty acid biosynthesis, cerulenin, indicating a critical dependence of the engineered E. coli strain on its native phospholipids.

Responses of plant volatile emissions to increasing nitrogen deposition: A pilot study on Eucalyptus urophylla.

Biogenic volatile organic compounds (BVOCs) significantly impact atmospheric chemistry, with emissions potentially influenced by nitrogen (N) deposition. The response of BVOC emissions to increasing N deposition remains debated. In this study, we examined Eucalyptus urophylla (E. urophylla) using three N treatments: N0, N50, and N100 (0, 50, and 100 kg N hm-2 yr-1 N addition). These treatments were applied to mature E. urophylla trees in a plantation subjected to over 10 years of soil N addition in southern China, a region with severe N deposition. Seventeen BVOCs were measured, with isoprene (36.99 %), α-pinene (38.80 %), and d-limonene (14.27 %) being the predominant compounds under natural conditions. Total BVOC emissions under N50 were nearly double those under N0 and N100, with leaf net CO2 assimilation identified as the most critical photosynthetic parameter. Isoprene and α-pinene emissions significantly increased under N50 compared to N0, while d-limonene emission decreased under N100. Stronger correlations for individual BVOCs under N50 and N100 compared to N0 might be due to differences in BVOC biosynthetic pathways and storage structures. The localized canopy-scale emission factors (EFs) under N50 were significantly higher than the default values in the Model of Emissions of Gases and Aerosols from Nature (MEGAN), suggesting the model might underestimate BVOC emissions from Eucalyptus in southern China under increased N deposition. Additionally, the secondary pollutant formation potentials of BVOCs were evaluated, identifying isoprene and monoterpenes as primary precursors of ozone and secondary organic aerosols. This study provides insights into the impacts of increased N deposition on BVOC emissions and their contribution to secondary atmospheric pollution. Updating localized BVOC EFs for subtropical tree species in southern China is crucial to reduce uncertainties in BVOC estimations under current and future N deposition scenarios.

Impact of severe drought on biogenic volatile organic compounds emissions from Sphagnum mosses in boreal peatlands.

Climate change and the associated increased frequency of extreme weather events are likely to alter the emissions of biogenic volatile organic compounds (BVOCs) from boreal peatlands. Hydrologically sensitive Sphagnum mosses are keystone species in boreal peatland ecosystems that are known to emit various BVOCs. However, it is not known how their emissions respond to seasonal droughts. In this study, we quantified the effect of severe drought, and subsequent recovery, on the BVOC emissions from Sphagnum mosses using mesocosms originating from wet open and naturally drier treed boreal fens and bogs. Here we report the emissions of 30 detected BVOCs, of which isoprene was the most abundant with an average flux rate of 5.6 µg m-2 h-1 (range 0-31.9 µg m-2 h-1). The experimental 43-day ecohydrological drought reduced total BVOC and isoprene emissions. In addition, in mesocosms originating from bogs, sesquiterpene emissions decreased with the drought, while the emissions of green leaf volatiles were induced. Sesquiterpene emissions remained low even six weeks after rewetting, indicating a long and limited recovery from the drought. Our results further imply that long-term exposure to deep water tables does not decrease sensitivity of Sphagnum to an extreme drought; we did not detect differences in the emission rates or drought responses between Sphagna originating from wet open and naturally drier treed habitats. Yet, the differences between fen and bog originating Sphagna indicate local variability in the BVOC quality changes following drought, potentially altering the climate feedback of boreal peatland BVOC emissions.

Coupling the Isopentenol Utilization Pathway and Prenyltransferase for the Biosynthesis of Licoflavanone in Recombinant Escherichia coli.

Prenylflavonoids are promising candidates for food additives and functional foods due to their diverse biological activities and potential health benefits. However, natural prenylflavonoids are generally present in low abundance and are limited to specific plant species. Here, we report the biosynthesis of licoflavanone from naringenin and prenol by recombinant Escherichia coli. By investigating the activities of seven different sources of prenyltransferases overexpressed in E. coli toward various flavonoid substrates, the prenyltransferase AnaPT exhibits substrate preference when naringenin serves as the prenyl acceptor. Furthermore, licoflavanone production was successfully achieved by coupling the isopentenol utilization pathway and AnaPT in recombinant E. coli. In addition, the effects of fermentation temperatures, induction temperatures, naringenin concentrations, and substrate feeding strategies were investigated on the biosynthesis of licoflavanone in recombinant E. coli. Consequently, the recombinant E. coli strain capable of improved dimethylallyl diphosphate (DMAPP) supply and suitable for prenylflavonoid biosynthesis increased licoflavanone titers to 142.1 mg/L in a shake flask and to 537.8 mg/L in a 1.3 L fermentor, which is the highest yield for any prenylflavonoids reported to date. These strategies proposed in this study provide a reference for initiating the production of high-value prenylflavonoids.

Impact of three decades of warming, increased nutrient availability, and increased cloudiness on the fluxes of greenhouse gases and biogenic volatile organic compounds in a subarctic tundra heath.

Climate change is exposing subarctic ecosystems to higher temperatures, increased nutrient availability, and increasing cloud cover. In this study, we assessed how these factors affect the fluxes of greenhouse gases (GHGs) (i.e., methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2)), and biogenic volatile organic compounds (BVOCs) in a subarctic mesic heath subjected to 34 years of climate change related manipulations of temperature, nutrient availability, and light. GHGs were sampled from static chambers and gases analyzed with gas chromatograph. BVOCs were measured using the push-pull method and gases analyzed with chromatography-mass spectrometry. The soil temperature and moisture content in the warmed and shaded plots did not differ significantly from that in the controls during GHG and BVOC measurements. Also, the enclosure temperatures during BVOC measurements in the warmed and shaded plots did not differ significantly from temperatures in the controls. Hence, this allowed for assessment of long-term effects of the climate treatment manipulations without interference of temperature and moisture differences at the time of measurements. Warming enhanced CH4 uptake and the emissions of CO2, N2O, and isoprene. Increased nutrient availability increased the emissions of CO2 and N2O but caused no significant changes in the fluxes of CH4 and BVOCs. Shading (simulating increased cloudiness) enhanced CH4 uptake but caused no significant changes in the fluxes of other gases compared to the controls. The results show that climate warming and increased cloudiness will enhance CH4 sink strength of subarctic mesic heath ecosystems, providing negative climate feedback, while climate warming and enhanced nutrient availability will provide positive climate feedback through increased emissions of CO2 and N2O. Climate warming will also indirectly, through vegetation changes, increase the amount of carbon lost as isoprene from subarctic ecosystems.

Smart-Adhesive, Breathable and Waterproof Fibrous Electronic Skins.

For the need of direct contact with the skin, electronic skins (E-skins) should not only fulfill electric functions, but also ensure comfort during wearing, including permeability, waterproofness, and easy removal. Herein, the study has developed a self-adhesive, detach-on-demand, breathable, and waterproof E-skin (PDSC) for motion sensing and wearable comfort by electrospinning styrene-isoprene block copolymer rubber with carbon black nanosheets as the sensing layer and liner copolymers of N, N-dimethylacrylamide, n-octadecyl acrylate and lauryl methacrylate as the adhesive layer. The high elasticity and microfiber network structure endow the PDSC with good sensitivity and high linearity for strain sensing. The hydrophobic and crystallizable adhesive layer ensures robust, waterproof, and detaching-on-demand skin adhesion. Meanwhile, the fiber structure enables the PDSC good air and water permeability. The integration of electric and wearable functions endows the PDSC with great potential for motion sensing during human activities as both the sensing and wearable performances.

High-Resolution Modeling of Summertime Biogenic Isoprene Emissions in New York City.

As cities strive for ambitious increases in tree canopy cover and reductions in anthropogenic volatile organic compound (AVOC) emissions, accurate assessments of the impacts of biogenic VOCs (BVOCs) on air quality become more important. In this study, we aim to quantify the impact of future urban greening on ozone production. BVOC emissions in dense urban areas are often coarsely represented in regional models. We set up a high-resolution (30 m) MEGAN (The Model of Emissions of Gases and Aerosols from Nature version 3.2) to estimate summertime biogenic isoprene emissions in the New York City metro area (NYC-MEGAN). Coupling an observation-constrained box model with NYC-MEGAN isoprene emissions successfully reproduced the observed isoprene concentrations in the city core. We then estimated future isoprene emissions from likely urban greening scenarios and evaluated the potential impact on future ozone production. NYC-MEGAN predicts up to twice as much isoprene emissions in NYC as the coarse-resolution (1.33 km) Biogenic Emission Inventory System version 3.61 (BEIS) on hot summer days. We find that BVOCs drive ozone production on hot summer days, even in the city core, despite large AVOC emissions. If high isoprene emitting species (e.g., oak trees) are planted, future isoprene emissions could increase by 1.4-2.2 times in the city core, which would result in 8-19 ppbv increases in peak ozone on ozone exceedance days with current NOx concentrations. We recommend planting non- or low-isoprene emitting trees in cities with high NOx concentrations to avoid an increase in the frequency and severity of future ozone exceedance events.

Sensitive quantification of mevalonate pathway intermediates and prediction of relative novel analogs by chemical derivatization-based LC-MS/MS.

The mevalonate (MVA) pathway plays a crucial role in the occurrence and progression of various diseases, such as osteoporosis, breast cancer, and lung cancer, etc. However, determining all the MVA pathway intermediates is still challenging due to their high polarity, low concentration, chelation effect with metal compartments, and poor mass spectrometric response. In this study, we established a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method coupled with N2, N2, N4, N4-tetramethyl-6-(4-(piperazin-1-ylsulfonyl) phenyl)-1,3,5-triazine-2,4-diamine (Tmt-PP) labeling for the simultaneous analysis of all MVA intermediates in biospecimens. Chemical derivatization significantly improved the chromatographic retention, peak shape, and detection sensitivity of the analytes. Moreover, we employed a method named mass spectrum calculation to achieve the absolute quantification of the isomers, i.e., isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). The established method was fully qualified and applied to explore the difference of these metabolites in cisplatin-resistant non-small cell lung cancer (NSCLC) cells. Additionally, several MVA intermediate analogs, including isopentenyl monophosphate or dimethylallyl monophosphate (IMP/DMAMP), geranyl monophosphate (GMP), 5-triphosphomevalonate (MTP), and isopentenyl triphosphate or dimethylallyl triphosphate (ITP/DMATP), were identified for the first time using a knowledge-driven prediction strategy. We further explored the tissue distribution of these novel metabolites. Overall, this work developed a sensitive quantification method for all MVA intermediates, which will enhance our understanding of the role of this pathway in various health and disease conditions. The novel metabolites we discovered warrant further investigations into their biosynthesis and biological functions.

A picomolar inhibitor of the Plasmodium falciparum IPP pathway.

We identified MMV026468 as a picomolar inhibitor of blood-stage Plasmodium falciparum. Phenotyping assays, including isopentenyl diphosphate rescue of parasite growth inhibition, demonstrated that it targets MEP isoprenoid precursor biosynthesis. MMV026468-treated parasites showed an overall decrease in MEP pathway intermediates, which could result from inhibition of the first MEP enzyme DXS or steps prior to DXS such as regulation of the MEP pathway. Selection of MMV026468-resistant parasites lacking DXS mutations suggested that other targets are possible. The identification of MMV026468 could lead to a new class of antimalarial isoprenoid inhibitors.

Transcriptomic and free monoterpene analyses of aroma reveal that isopentenyl diphosphate isomerase inhibits monoterpene biosynthesis in grape (Vitis vinifera L.).

BACKGROUND: Monoterpenes are among the most important volatile aromatic compounds contributing to the flavor and aroma of grapes and wine. However, the molecular basis of monoterpene biosynthesis has not yet been fully elucidated. RESULTS: In our study, transcriptomics and gas chromatography-mass spectrometry (GC-MS) were used to mine candidate genes and transcription factors involved in monoterpene biosynthesis between high-monoterpene and zero-monoterpene table grape cultivars. We found that monoterpene biosynthesis was positively correlated by the expression of five genes encoding 1-deoxy-D-xylulose-5-phosphate synthase (VvDXSs), one encoding 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (VvHDR), three hydroxy-3-methylglutaryl-CoA synthases (VvHMGSs) and one mevalonate kinase (VvMVK), whereas the expression of one isopentenyl diphosphate isomerase (VvIDI) and one 3-hydroxy-3-methylglutaryl-CoA reductase (VvHMGR) negatively correlated monoterpene biosynthesis. Of these genes, VvIDI was selected to validate its function in monoterpene accumulation through a transient overexpression experiment, and was shown to inhibit the biosynthesis of grape linalool and α-terpineol. Meanwhile, we found that a 64-amino acid extension sequence at the N-terminus can guide the VvIDI protein to target the chloroplast. CONCLUSIONS: The findings of this study should help to guide future functional analysis of key genes as well as mining the potential regulatory mechanism of monoterpene biosynthesis in grapes and grape products.

Kinetic study of isoprene hydroxy hydroperoxide radicals reacting with sulphur dioxide and their global-scale impact on sulphate formation.

Isoprene is the most relevant volatile organic compound emitted during the biosynthesis of metabolism processes. The oxidation of isoprene by a hydroxy radical (OH) is one of the main consumption schemes that generate six isomers of isoprene hydroxy hydroperoxide radicals (ISOPOOs). In this study, the rate constants of ISOPOOs + sulphur dioxide (SO2) reactions that eventually generate sulphur trioxide (SO3), the precursor of sulphate aerosol (SO42-(p)), are determined using microcanonical kinetic theories coupled with molecular structures and energies estimated by quantum chemical calculations. The results show that the reaction rates range from 10-27 to 10-20 cm3 molecule-1 s-1, depending on the atmospheric temperature and structure of the six ISOPOO isomers. The effect of SO3 formation from SO2 oxidation by ISOPOOs on the atmosphere is evaluated by a global chemical transport model, along with the rate constants obtained from microcanonical kinetic theories. The results show that SO3 formation is enhanced in regions with high SO2 or low nitrogen oxide (NO), such as China, the Middle East, and Amazon rainforests. However, the production rates of SO3 formation by ISOPOOs + SO2 reactions are eight orders of magnitude lower than that from the OH + SO2 reaction. This is indicative of SO42-(p) formation from the direct oxidation of SO2 by ISOPOOs, which is almost negligible in the atmosphere. The results of this study entail a detailed analysis of SO3 formation from gas-phase reactions of isoprene-derived products.

Effects of aluminum (Al) stress on the isoprenoid metabolism of two Citrus species differing in Al-tolerance.

Isoprenoid metabolism and its derivatives took part in photosynthesis, growth regulation, signal transduction, and plant defense to biotic and abiotic stresses. However, how aluminum (Al) stress affects the isoprenoid metabolism and whether isoprenoid metabolism plays a vital role in the Citrus plants in coping with Al stress remain unclear. In this study, we reported that Al-treatment-induced alternation in the volatilization rate of monoterpenes (α-pinene, ß-pinene, limonene, α-terpinene, γ-terpinene and 3-carene) and isoprene were different between Citrus sinensis (Al-tolerant) and C. grandis (Al-sensitive) leaves. The Al-induced decrease of CO2 assimilation, maximum quantum yield of primary PSII photochemistry (Fv/Fm), the lower contents of glucose and starch, and the lowered activities of enzymes involved in the mevalonic acid (MVA) pathway and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway might account for the different volatilization rate of isoprenoids. Furthermore, the altered transcript levels of genes related to isoprenoid precursors and/or derivatives metabolism, such as geranyl diphosphate (GPP) synthase (GPPS) in GPP biosynthesis, geranylgeranyl diphosphate synthase (GGPPS), chlorophyll synthase (CHS) and GGPP reductase (GGPPR) in chlorophyll biosynthesis, limonene synthase (LS) and α-pinene synthase (APS) in limonene and α-pinene synthesis, respectively, might be responsible for the different contents of corresponding products in C. grandis and C. sinensis. Our data suggested that isoprenoid metabolism was involved in Al tolerance response in Citrus, and the alternation of some branches of isoprenoid metabolism could confer different Al-tolerance to Citrus species.

EuHDZ25 positively affects rubber biosynthesis by targeting EuFPS1 in Eucommia leaves.

Eucommia ulmoides is a temperate gum source plant that produces trans-polyisoprene (TPI), also known as Eucommia rubber. The structural configuration and function of TPI offer a new material with important potential for industrial development. In this study, we detected the TPI content in the leaves of diploid and triploid E. ulmoides plants. The average TPI content in the leaves of triploid E. ulmoides was significantly higher than that of diploid. Transcriptome data and weighted gene co-expression network analyses identified a significant positive correlation between the EuFPS1 gene and TPI content. Overexpression of EuFPS1 increased the density of rubber particles and TPI content, indicating its crucial role in TPI biosynthesis. In addition, the expression of EuHDZ25 in E. ulmoides was significantly positively correlated with EuFPS1 expression. Yeast one-hybrid and dual-luciferase assays demonstrated that EuHDZ25 mainly promotes TPI biosynthesis through positive regulation of EuFPS1 expression. The significantly up-regulated expression of EuHDZ25 and its consequent upregulation of EuFPS1 during the biosynthesis of TPI may partially explain the increased TPI content of triploids. This study provides an important theoretical foundation for further exploring the molecular mechanism of secondary metabolites content variation in polyploids and can help to promote the development and utilization of rubber resources.

Natural transformation of Vibrio natriegens with large genetic cluster enables alginate assimilation for isopentenol production.

Alginate is a major component of brown macroalgae, and its efficient utilization is critical for developing sustainable technologies. Vibrio natriegens is a fast-growing marine bacterium that has gained massive attention due to its potential as an alternative industrial chassis. However, V. natriegens cannot naturally metabolize alginate, limiting its usage in marine biomass conversion. In this study, V. natriegens was engineered to utilize marine biomass, kelp, as a carbon source. A total of 33.8 kb of the genetic cluster for alginate assimilation from Vibrio sp. dhg was integrated into V. natriegens by natural transformation. Engineered V. natriegens was further modified to produce 1.8 mg/L of isopentenol from 16 g/L of crude kelp powder. This study not only presents the very first case in which V. natriegens can be naturally transformed with large DNA fragments but also highlights the potential of this strain for converting marine biomass into valuable products.

Plant terpenoid biosynthetic network and its multiple layers of regulation.

Terpenoids constitute one of the largest and most chemically diverse classes of primary and secondary metabolites in nature with an exceptional breadth of functional roles in plants. Biosynthesis of all terpenoids begins with the universal five­carbon building blocks, isopentenyl diphosphate (IPP) and its allylic isomer dimethylallyl diphosphate (DMAPP), which in plants are derived from two compartmentally separated but metabolically crosstalking routes, the mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathways. Here, we review the current knowledge on the terpenoid precursor pathways and highlight the critical hidden constraints as well as multiple regulatory mechanisms that coordinate and homeostatically govern carbon flux through the terpenoid biosynthetic network in plants.

Optimal seasonal schedule for the production of isoprene, a highly volatile biogenic VOC.

The leaves of many trees emit volatile organic compounds (abbreviated as BVOCs), which protect them from various damages, such as herbivory, pathogens, and heat stress. For example, isoprene is highly volatile and is known to enhance the resistance to heat stress. In this study, we analyze the optimal seasonal schedule for producing isoprene in leaves to mitigate damage. We assume that photosynthetic rate, heat stress, and the stress-suppressing effect of isoprene may vary throughout the season. We seek the seasonal schedule of isoprene production that maximizes the total net photosynthesis using Pontryagin's maximum principle. The isoprene production rate is determined by the changing balance between the cost and benefit of enhanced leaf protection over time. If heat stress peaks in midsummer, isoprene production can reach its highest levels during the summer. However, if a large portion of leaves is lost due to heat stress in a short period, the optimal schedule involves peaking isoprene production after the peak of heat stress. Both high photosynthetic rate and high isoprene volatility in midsummer make the peak of isoprene production in spring. These results can be clearly understood by distinguishing immediate impacts and the impacts of future expectations.