Engineered Saccharomyces cerevisiae harbors xylose isomerase and xylose transporter improves co-fermentation of xylose and glucose for ethanol production.

Saccharomyces cerevisiae cannot assimilate xylose, second to glucose derived from lignocellulosic biomass. Here, the engineered S. cerevisiae strains INVSc-XI and INVSc-XI/XT were constructed using xylA and Xltr1p to co-utilize xylose and glucose, achieving economic viability and sustainable production of fuels. The xylose utilization rate of INVSc-XI/XT was 2.3-fold higher than that of INVSc-XI, indicating that overexpressing Xltr1p could further enhance xylose utilization. In mixed sugar media, a small amount of glucose enhanced the consumption of xylose by INVSc-XI/XT. Transcriptome analysis showed that glucose increased the upregulation of acetate of coenzyme A synthetase (ACS), alcohol dehydrogenase (ADH), and transketolase (TKL) gene expression in INVSc-XI/XT, further promoting xylose utilization and ethanol yield. The highest ethanol titer of 2.91 g/L with a yield of 0.29 g/g at 96 h by INVSc-XI/XT was 56.9% and 63.0% of the theoretical ethanol yield from glucose and xylose, respectively. These results showed overexpression of xylA and Xltr1p is a promising strategy for improving xylose and glucose conversion to ethanol. Although the ability of strain INVSc-XI/XT to produce ethanol was not very satisfactory, glucose was discovered to influence xylose utilization in strain INVSc-XI/XT. Altering the glucose concentration is a promising strategy to improve the xylose and glucose co-utilization.

INVSc-XI and INVSc-XI/XT strains were newly constructed to utilize xylose and glucose.XylA, in combination with xylose transporter Xltr1p, enhances xylose consumption.A small amount of glucose enhanced xylose utilization in INVSc-XI/XT strain.The expression of ACS, ADH, and TKL genes is upregulated in the media containing mixed sugars.The highest ethanol yield of 0.29 g/g was produced in a 2-L scale-up fermenter.

Rational fabrication of cadmium-sulfide/graphitic-carbon-nitride/hematite photocatalyst with type II and Z-scheme tandem heterojunctions to promote photocatalytic carbon dioxide reduction.

Artificial photosynthesis has become one of the most attractive strategies for lowering atmospheric carbon dioxide (CO2) level and achieving the carbon balance; whereas, the fast electron-hole recombination and sluggish charge transfer in photocatalysts are themain stumbling blocks to the applications. Constructing semiconductor nano-heterostructures provides a promising strategy to accelerate the separation and transfer of photoinduced charge carriers for promoting the multielectron CO2 reduction reaction. Herein, a CdS/g-C3N4/α-Fe2O3 three-component photocatalyst consisting of type II and Z-scheme tandem heterojunctions is skillfully fabricated via the solvothermal synthesis followed with photoinduced deposition. The CdS/g-C3N4/α-Fe2O3 tandem-heterojunction photocatalyst exhibits superior performance toward the conversion of CO2 to fuels (CO and CH4), compared with the single- and binary-component systems, owing to the favorable energy-level alignment, accelerated charge separation, facilitated water dissociation and sufficient reactive-hydrogen provision. The total consumed electron number of CdS/g-C3N4/α-Fe2O3 catalyst for CO2 reduction is about 10.5 times that of pure g-C3N4. The photocatalytic mechanism is elucidated according to detailed characterizations and in-situ spectroscopy analyses. This work sheds light on the rational construction of heterojunction photocatalysts to promote the conversion of CO2 to solar fuels, without using any sacrifice reagent or noble-metal cocatalysts.

Effective Biotransformation of Variety of Guaiacyl Lignin Monomers Into Vanillin by Bacillus pumilus.

Biotransformation has gained increasing attention due to its being an eco-friendly way for the production of value-added chemicals. The present study aimed to assess the potential of Bacillus pumilus ZB1 on guaiacyl lignin monomers biotransformation for the production of vanillin. Consequently, isoeugenol, eugenol, and vanillyl alcohol could be transformed into vanillin by B. pumilus ZB1. Based on the structural alteration of masson pine and the increase of total phenol content in the supernatant, B. pumilus ZB1 exhibited potential in lignin depolymerization and valorization using masson pine as the substrate. As the precursors of vanillin, 61.1% of isoeugenol and eugenol in pyrolyzed bio-oil derived from masson pine could be transformed into vanillin by B. pumilus ZB1. Four monooxygenases with high specific activity were identified that were involved in the transformation process. Thus, B. pumilus ZB1 could emerge as a candidate in the biosynthesis of vanillin by using wide guaiacyl precursors as the substrates.

Engineering Catalytic Interfaces in Cuδ+/CeO2-TiO2 Photocatalysts for Synergistically Boosting CO2 Reduction to Ethylene.

Photocatalytic CO2 conversion into a high-value-added C2 product is a highly challenging task because of insufficient electron deliverability and sluggish C-C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C2 product from CO2 reduction. Herein, a Cuδ+/CeO2-TiO2 photocatalyst that contains atomically dispersed Cuδ+ sites anchored on the CeO2-TiO2 heterostructures consisting of highly dispersed CeO2 nanoparticles on porous TiO2 is designedly constructed by the pyrolytic transformation of a Cu2+-Ce3+/MIL-125-NH2 precursor. In the designed photocatalyst, TiO2 acts as a light-harvesting material for generating electron-hole pairs that are efficiently separated by CeO2-TiO2 interfaces, and the Cu-Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C-C coupling. As a consequence, the Cuδ+/CeO2-TiO2 photocatalyst exhibits a production rate of 4.51 µmol-1·gcat-1·h-1 and 73.9% selectivity in terms of electron utilization for CO2 to C2H4 conversion under simulated sunlight, with H2O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO2 conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C2 product.

Cadmium-sulfide/gold/graphitic-carbon-nitride sandwich heterojunction photocatalyst with regulated electron transfer for boosting carbon-dioxide reduction to hydrocarbon.

Developing the heterogeneous photocatalysts with high performance for carbon dioxide (CO2) conversion to solar fuels is remarkably significant for reducing the atmospheric CO2 level and achieving the target of carbon neutrality through the artificial photosynthesis strategies. However, it remains a great challenge for most of the photocatalysts to achieve the CO2-to-hydrocarbon conversion via a multi-proton coupled multi-electron reduction process. In this work, the cadmium-sulfide/gold/graphitic-carbon-nitride (CdS/Au/g-C3N4) heterojunction photocatalyst with sandwich nanostructures is designedly constructed by a selective two-step photodeposition process. The better separation of photogenerated electrons and holes in CdS/Au/g-C3N4 heterojunction creates the higher density of surface photogenerated electron, dynamically accelerating the multi-electron reduction of CO2. Moreover, the selective photodeposition of CdS on Au/g-C3N4 affords sufficient electron-enriched Sδ- active sites which are more beneficial to the provision of H adatoms. These advantages jointly improve the photocatalytic CO2 conversion to methane (CH4) via a multi-proton coupled multi-electron reduction process. The CH4 yield rate on CdS/Au/g-C3N4 photocatalyst is about twice that of CdS/g-C3N4, while g-C3N4 and Au/g-C3N4 only produce CO. The total electron utilization for CO2 reduction on CdS/Au/g-C3N4 photocatalyst is 6.9 times that of g-C3N4. Furthermore, the CdS/Au/g-C3N4 photocatalyst exhibits high stability in consecutive cycles of CO2 reduction reaction. The photocatalytic mechanism is proposed on the basis of in situ spectrographic analyses together with other detailed characterizations.

An effective strategy for improving the specific activity and saccharification efficiency of cellulase by pre-incubation with phenolic acids.

This short communication analyzed the effects of lignin-derived phenolic acid compounds on cellulase. Vanillic acid, syringic acid, ferulic acid, and isovanillic acid improved cellulase specific activity and saccharification efficiency. In the enzymatic hydrolysis process, the promotion effect of phenolic acid was concentration-dependent. The effect of low concentration of phenolic acids (less than 5 mM) was negligible. After pre-incubating 1 g cellulase with 5 mmol phenolic acid, FPase-specific activity, CMCase-specific activity, and pNPGase-specific activity increased by 57.06%, 136.79%, and 110.61%, respectively. After digestion with pre-incubated cellulase, the saccharification efficiency of phosphoric acid-swollen cellulose increased by 45.13%. Pre-incubation with phenolic acid improved the saccharification efficiency of cellulase. It might be helpful to enhance the comprehensive utilization capacity of lignin-derived compounds.

High sodium chloride affects BMP-7 and 1α-hydroxylase levels through NCC and CLC-5 in NRK-52E cells.

A diet high in sodium chloride (NaCl) can affect renal function damage and increase urinary calcium excretion, leading to bone loss. in renal tubules, Na-Cl co-transporter (NCC) and chloride channel 5 (CLC-5) are involved in regulating urinary calcium excretion. In addition, some cytokines, such as Bone morphogenetic protein 7 (BMP-7) and 1α-hydroxylase, are synthesized by renal tubules, which target on bone and play important roles on bone metabolism. However, the specific mechanisms between NaCl and these ion channels or cytokines still need investigations from many aspects. This study, in culture normal rat renal tubular epithelial NRK-52E cells, showed that high concentrations of NaCl significantly inhibited the cell viability and increased the cell apoptosis. High concentration of NaCl reduce bone mineral density (BMD), as demonstrated by the significantly increased mRNA and protein levels of NCC and osteopontin (OPN), but decreased the levels of CLC-5, BMP-7, and 1α-hydroxylase. In addition, we found that ovariectomized (OVX) rats on a high-salt diet for 12 weeks had altered levels of these indices in the renal cortices. Moreover, the BMD in fourth and fifth lumbar vertebra (LV4 and 5) and femurs were significantly decreased and bone microstructure was destroyed of these rats. We also demonstrated that high concentration of NaCl enhanced the inhibition of these cytokines which is beneficial to increase BMD, induced by modulating ion channels NCC and CLC-5. In conclusion, our results indicate that high concentration of NaCl reduce BMD by regulating ion channels NCC and CLC-5.

The Clean Synthesis of Small-Particle TS-1 with High-Content Framework Ti by Using NH4HCO3 and Suspended Seeds as an Assistant.

The synthesis of a TS-1 zeolite with high-content framework Ti and small particles has been developed by adding NH4HCO3 and suspended seeds as an assistant. With the addition of NH4HCO3, the Hofmann decomposition of the tetrapropylammonium cation (TPA+) decreased, and the framework Ti content of the zeolite increased first and then decreased while the particle became larger. With the assistance of suspended seeds, the TS-1 synthesized under a low-alkalinity system possesses small particle size and high-content framework Ti, and it shows the best catalytic activity among the prepared catalysts. Because the decomposition of TPA+ decreased, the mother liquid could be reused in the next run of preparation. Even though the recycled mother liquid was reused five times, all obtained TS-1 samples exhibited similar catalytic performances in propylene epoxidation. This work provides an efficient process for preparing TS-1 with good catalytic performance and reduces the discharge of the waste liquid.

Modulating oxygen vacancies on bismuth-molybdate hierarchical hollow microspheres for photocatalytic selective alcohol oxidation with hydrogen peroxide production.

Photocatalytic selective oxidation of alcohols into high value-added carbonyl compounds accompanied by producing hydrogen peroxide (H2O2) is undoubtedly a more efficient solar energy conversion strategy with high atom economy. Herein, we have developed an efficient photocatalyst of bismuth-molybdate (Bi2MoO6) hierarchical hollow microspheres with tunable surface oxygen vacancies (OVs) for promoting the photocatalytic selective alcohol oxidation with H2O2 production. The effect of surface OVs on the photocatalytic efficiency is studied systematically by comparing the performance of different photocatalysts. The benzaldehyde and H2O2 production rates over the OV-rich Bi2MoO6 photocatalyst reach up to 1310 and 67.2 µmol g-1 h-1, respectively, which are 2.3 and 4.0 times those generated from the OV-poor Bi2MoO6 hollow microspheres. The roles of various active radicals in the photocatalytic reaction are probed by a series of controlled experiments and in situ ESR measurements, revealing that both superoxide radical (•O2-) and carbon-centered radical are the key active intermediates. The introduction of surface OVs on Bi2MoO6 hollow microspheres accelerates the separation and transfer of photo-generated charge carriers as well as enhances the adsorption and activation of reactant molecules, thereby greatly promoting the photocatalytic selective oxidation of alcohols along with H2O2 production. This work not only demonstrates a facile strategy for the preparation of high-efficiency photocatalysts by simultaneous modulations of morphology and surface defects, but also offers insight into developing the dual-functional photocatalytic reactions for the full utilizations of photoinduced electrons and holes.

Air temperature optima of vegetation productivity across global biomes.

The global distribution of the optimum air temperature for ecosystem-level gross primary productivity ([Formula: see text]) is poorly understood, despite its importance for ecosystem carbon uptake under future warming. We provide empirical evidence for the existence of such an optimum, using measurements of in situ eddy covariance and satellite-derived proxies, and report its global distribution. [Formula: see text] is consistently lower than the physiological optimum temperature of leaf-level photosynthetic capacity, which typically exceeds 30 °C. The global average [Formula: see text] is estimated to be 23 ± 6 °C, with warmer regions having higher [Formula: see text] values than colder regions. In tropical forests in particular, [Formula: see text] is close to growing-season air temperature and is projected to fall below it under all scenarios of future climate, suggesting a limited safe operating space for these ecosystems under future warming.

Lead exposure inhibits osteoblastic differentiation and inactivates the canonical Wnt signal and recovery by icaritin in MC3T3-E1 subclone 14 cells.

Exposure to lead (Pb) poses a threat to human bone health, including changes in bone mineral composition and the inhibition of skeletal growth and bone maturation. However, little is known about how Pb directly affects osteoblasts. In this work, we found that sub-toxic Pb concentrations suppressed bone nodule formation and inhibited differentiation in MC3T3-E1 subclone 14 cells, as shown by decreased expression levels of the differentiation markers alkaline phosphatase (ALP), type 1 collagen (COL1), osteocalcin (OC), and runt-related transcription factor 2 (RUNX2). Moreover, Pb inactivated the canonical Wnt pathway by regulating key components, such as Wnt3a, Dkk-1, pGSK3ß, and ß-catenin. Icaritin (ICT), a hydrolytic product of icariin from the genus Epimedium, attenuates the inhibitory effect of Pb on osteoblastic differentiation, as well as activate the canonical Wnt signal pathway. Taken together, the results suggest ICT as a potential bone protectant that may be used to prevent bone damage caused by Pb and can activate the canonical Wnt signal pathway.

Layer-by-layer immobilization of amphoteric carboxymethyl chitosan onto biocompatible silk fibroin nanofibrous mats.

Novel antimicrobials with well biocompatibility are urgently needed for human public health protecting. Here, the silk fibroin (SF) nanofibrous mats coated with carboxymethyl chitosan (CMC), both extracted from natural polymers, were fabricated by combining electrospinning and electrostatic layer-by-layer (LBL) self-assembly techniques. The amphoteric CMC could be easily adsorbed on the surface of SF nanofibers due to the electrostatic interaction, which were a highly efficient and "green" route for the surface modification of SF mats. The mats after LBL procedure exhibited better hydrophilicity and stronger mechanical properties. The experimental results demonstrated that the LBL modified mats not only kept well biocompatibility but also obtained extremely enhanced antibacterial activity. More importantly, the mats displayed better bacterial inhibition with the increased CMC layers. LBL10 and LBL10.5 owned the antibacterial activity of more than 67% at the bacterial concentrations of 106 cfu ml-1 after 24 h cultivation, which implied that these novel natural polymer-based materials could be utilized as wound dressings for clinical skin and tissue regeneration, especially for infected wounds.

Efficient fabrication of reversible pH-induced carboxymethyl chitosan nanoparticles for antitumor drug delivery under weakly acidic microenvironment.

Searching for the carrier systems for drug controlled release under weakly acidic condition related to tumor environment has attracted a tremendous level of attention. In this study, amphiphilic carboxymethyl chitosan (CMC) was employed to fabricate nanoparticles (NPs) with an efficient and simple method by adjusting the pH values of CMC aqueous solutions. The prepared NPs could not only capture the doxorubicin hydrochloride (DOX) efficiently and alleviate the initial burst release, but also exhibit pH sensitivity under weakly acidic microenvironment for tumor therapy. Importantly, rectorite (REC) with lamellar structure could be intercalated with CMC chains to construct more compact structure and DOX could be captured in the interlayer of REC, which could contribute to heightening the encapsulation efficiency and loading capacity of DOX, as well as reducing the initial burst release and prolonging the therapeutic time. The NPs displayed the behavior of controlled DOX release at pH 4.5, which suggested that the intelligent colloids might be utilized in tumor therapy.

Emerging negative impact of warming on summer carbon uptake in northern ecosystems.

Most studies of the northern hemisphere carbon cycle based on atmospheric CO2 concentration have focused on spring and autumn, but the climate change impact on summer carbon cycle remains unclear. Here we used atmospheric CO2 record from Point Barrow (Alaska) to show that summer CO2 drawdown between July and August, a proxy of summer carbon uptake, is significantly negatively correlated with terrestrial temperature north of 50°N interannually during 1979-2012. However, a refined analysis at the decadal scale reveals strong differences between the earlier (1979-1995) and later (1996-2012) periods, with the significant negative correlation only in the later period. This emerging negative temperature response is due to the disappearance of the positive temperature response of summer vegetation activities that prevailed in the earlier period. Our finding, together with the reported weakening temperature control on spring carbon uptake, suggests a diminished positive effect of warming on high-latitude carbon uptake.

Design, synthesis, biological evaluation and structure-activity relationship of sophoridine derivatives bearing pyrrole or indole scaffold as potential antitumor agents.

Taking sophoridine as a lead compound, 58 sophoridine derivatives were designed, synthesized and evaluated for their antiproliferative activity in the HepG2 cancer cell line. Among the 58 compounds, 33 compounds showed potent antiproliferative activity with IC50 less than 10 µM. Compound 5w showed the most potent anti-proliferative activity in the HepG2 cancer cell line. Thus, we further extended our characterization of the antiproliferative activity of 5w in six cancer cell lines (HepG2, SMMC-7721, Hela, CNE1, CNE2 and MCF7). The representative compound 5w displayed robust anti-proliferative activities in all the tested cell lines with IC50 values in range of 0.93-1.89 µM which were much lower than that of sophoridine. Here, we report the structure-activity relationships (SAR) in a sophoridine series of compounds, which indicated that introduction of N-benzyl indole group on the 14-carbon atom of sophoridine can significantly enhance the antiproliferative activity. By molecular docking and enzymatic assay, compound 5w was found to be able to inhibit the activity of DNA Topo I. Furthermore, apoptosis assay displayed that compound 5w could significantly induce the apoptosis of HepG2 cells in a dose-dependent manner by activating caspase-3, increasing expression of cleaved caspase-3 and reducing the ratio of Bcl-2/Bax. The in vivo antitumor assay demonstrated that 5w suppressed the growth of HepG2 xenografts in nude mice without any obvious side effects.

A traditional Chinese medicine therapy for coronary heart disease after percutaneous coronary intervention: a meta-analysis of randomized, double-blind, placebo-controlled trials.

Huoxue Huayu therapy (HXHY) has been widely used to treat cardiovascular diseases in traditional Chinese medicine (TCM) such as hypertension and coronary heart disease (CHD). The present study describes a meta-analysis of a series of prospective randomized, double-blind, placebo-controlled trials conducted to evaluate the effect of HXHY on patients with CHD after percutaneous coronary intervention (PCI). The Cochrane Library, PubMed, EMBASE, the China National Knowledge Infrastructure (CNKI), the Chinese Biomedical Literature database, and the Wanfang database were searched up until June 2018. A series of randomized controlled clinical trials were included and the subjects were patients with CHD who had undergone PCI. The experimental group was treated with HXHY therapy, and the control group was treated with placebo; meanwhile, all the patients accepted conventional Western medicine. Review Manager 5.3 software was used for the statistical analysis. Ten trials were included in the final study. The overall risk of bias assessment was low. HXHY had a greater beneficial effect on reducing the in-stent restenosis (ISR) rate (RR = 0.57, 95% confidence interval [CI] [0.40-0.80], P=0.001) and the degree of restenosis (MD = -8.89, 95% CI [-10.62 to -7.17], P<0.00001) compared with Placebo. Moreover, HXHY was determined to be more effective in improving Seattle Angina Questionnaires (SAQ) and the revascularization rate (RR = 0.54, 95% CI [0.32-0.90], P=0.02) compared with Placebo, whereas the rate of death and MI of patients treated with HXHY were no different from those treated with the placebo (P>0.05). Therefore, HXHY is an effective and safe therapy for CHD patients after PCI.

Drought timing influences the legacy of tree growth recovery.

Whether and how the timing of extreme events affects the direction and magnitude of legacy effects on tree growth is poorly understood. In this study, we use a global database of Ring-Width Index (RWI) from 2,500 sites to examine the impact and legacy effects (the departure of observed RWI from expected RWI) of extreme drought events during 1948-2008, with a particular focus on the influence of drought timing. We assessed the recovery of stem radial growth in the years following severe drought events with separate groupings designed to characterize the timing of the drought. We found that legacies from extreme droughts during the dry season (DS droughts) lasted longer and had larger impacts in each of the 3 years post drought than those from extreme droughts during the wet season (WS droughts). At the global scale, the average integrated legacy from DS droughts (0.18) was about nine times that from WS droughts (0.02). Site-level comparisons also suggest stronger negative impacts or weaker positive impacts of DS droughts on tree growth than WS droughts. Our results, therefore, highlight that the timing of drought is a crucial factor determining drought impacts on tree recovery. Further increases in baseline aridity could therefore exacerbate the impact of punctuated droughts on terrestrial ecosystems.

Enhanced physical and biological properties of silk fibroin nanofibers by layer-by-layer deposition of chitosan and rectorite.

The search for biodegradable and biocompatible materials applied to the antibacterial field has become a significant topic of interest worldwide. In this study, the electrospinning and electrostatic layer-by-layer self-assembly (LBL) techniques were applied to achieve composite mats with enhanced physical and biological properties. Electrospun silk fibroin (SF) was selected as the substrate, and chitosan (CS) and rectorite (REC) were assembled on the surface of the substrate as positively and negatively charged layers via electrostatic LBL. The morphology, composition and structure of the mats were examined, and the results suggested that LBL modification was successful. In addition, the variation of the bilayer numbers and the component of the outmost layer could affect the morphology and the physical and biological properties of LBL mats. Additionally, the morphology and the water contact angle investigation results of the as-prepared mats indicated that the surface features were changed through the LBL process, resulting in a rougher surface than in pure SF mats. Moreover, the mechanical properties of the SF mats were improved after the LBL process. Furthermore, the antibacterial activity of the LBL self-assembled SF mats against E. coli and S. aureus with a concentration of 106 CFU/mL were 84 and 92%, respectively. The cell-culture experiments demonstrated that the mats maintained superior biocompatibility after the introduction of CS and REC.

Design, synthesis and biological evaluation of matrine derivatives as potential anticancer agents.

Using matrine (1) as the lead compound, a series of new 14-(N-substituted-2-pyrrolemethylene) matrine and 14-(N-substituted-indolemethylene) matrine derivatives was designed and synthesized for their potential application as anticancer agents. The structure of these compounds was characterized by 1H NMR, 13C NMR and ESI-MS spectral analyses. The target compounds were evaluated for their in vitro cytotoxicity against three human cancer cell lines (SMMC-7721, A549 and CNE2). The results revealed that compound A6 and B21 displayed the most significant anticancer activity against three cancer cell lines with IC50 values in range of 3.42-8.05 µM, which showed better activity than the parent compound (Matrine) and positive control Cisplatin. Furthermore, the Annexin V-FITC/PI dual staining assay revealed that compound A6 and B21 could significantly induce the apoptosis of SMMC-7721 and CNE2 cells in a dose-dependent manner. The cell cycle analysis also revealed that compound A6 could cause cell cycle arrest of SMMC-7721 and CNE2 cells at G2/M phase.

Velocity of change in vegetation productivity over northern high latitudes.

Warming is projected to increase the productivity of northern ecosystems. However, knowledge on whether the northward displacement of vegetation productivity isolines matches that of temperature isolines is still limited. Here we compared changes in the spatial patterns of vegetation productivity and temperature using the velocity of change concept, which expresses these two variables in the same unit of displacement per time. We show that across northern regions (>50° N), the average velocity of change in growing-season normalized difference vegetation index (NDVIGS, an indicator of vegetation productivity; 2.8 ± 1.1 km yr-1) is lower than that of growing-season mean temperature (T GS; 5.4 ± 1.0 km yr-1). In fact, the NDVIGS velocity was less than half of the T GS velocity in more than half of the study area, indicating that the northward movement of productivity isolines is much slower than that of temperature isolines across the majority of northern regions (about 80% of the area showed faster changes in temperature than productivity isolines). We tentatively attribute this mismatch between the velocities of productivity and temperature to the effects of limited resource availability and vegetation acclimation mechanisms. Analyses of ecosystem model simulations further suggested that limited nitrogen availability is a crucial obstacle for vegetation to track the warming trend.