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Summary: Timing (phenology) and amount (production) are two integral facets of root growth, and their shifts have profound influences on below‐ground resource acquisition. However, the environmental control and the effects of nitrogen (N) deposition on the production and phenology of ectomycorrhizal (ECM) roots remain unclear.Using a 4 yr minirhizotron experiment, we explored the control of the production and three phenophases (initiation, peak, and cessation of growth) of ECM roots in two soil layers and investigated their dynamic responses to N addition in a seasonally dry subtropical Pinus elliottii forest.We found a stronger control of water availability on the production and a stronger control of temperature on the phenology of ECM roots under ambient conditions. Temperature was correlated positively with initiation and negatively with cessation, especially in the shallow layer. N addition did not affect the phenology of ECM roots but increased their production by modifying N and phosphorus (P) stoichiometry in the soil and foliage.Our findings suggest a greater sensitivity of production than phenology of ECM roots to N addition. The increased production of ECM roots under N addition could be driven by N‐induced P limitation or some combination of below‐ground resources (P, N, water). [ABSTRACT FROM AUTHOR]

Background and aims: Studies on the aboveground growth and traits of plants suggest that plants exhibit faster growth with greater plasticity in leaf traits to adapt to changing environments. However, our knowledge of belowground growth and trait responses and associated root foraging strategies, under competition remains limited.Methods: Using an understory species-addition experiment, we investigated the responses of function-based root (absorptive fine roots [AFRs] vs. transport fine roots [TFRs]) growth, mycorrhizal association, and order-based root traits (morphological, architectural, and chemical traits) of Pinus massoniana (native species) and Pinus elliottii (exotic species), which are the dominant coniferous tree species in subtropical China.Results: Higher understory-species diversity increased the biomass of AFRs, but not TFRs and total fine roots (AFRs plus TFRs) of both species. Higher diversity increased the biomass ratio of the AFRs and TFRs of P. elliottii, indicating a tradeoff in plant carbon investment between the two functional root modules for P. elliottii. Higher diversity increased the total root length of P. massoniana, but did not affect that of P. elliottii. Increased species diversity decreased the ectomycorrhizal colonization rate of P. massoniana, but increased that of P. elliottii. Increased species diversity altered the branching-related traits (increased branching ratio and intensity), but did not affect the morphological (diameter, specific root length, and root tissue density) or chemical traits across the root orders of either species.Conclusions: Our findings indicate that P. elliottii employed dual root foraging strategies (growth and mycorrhizal strategies) and had a cost-benefit tradeoff between AFR and TFR construction. In comparison, P. massoniana only accelerated root growth under competition. These results facilitate a better understanding of the root foraging strategies of plants and the rapid adaptation of exotic species in novel environments. [ABSTRACT FROM AUTHOR]

Plants operate along a continuum of stringency of regulation of plant water potential from isohydry to anisohydry. However, most metrics and proxies of plant iso/anisohydric behavior have been developed from limited sets of site-specific experiments. Understanding the underlying mechanisms that determine species' operating ranges along this continuum, independent of site and growing conditions, remains challenging. We compiled a global database to assess the global patterns of metrics and proxies of plant iso/anisohydry and then explored some of the underlying functional traits and trade-offs associated with stringency of regulation that determines where species operate along the continuum. Our results showed that arid and semi-arid biomes were associated with greater anisohydry than more mesic biomes, and angiosperms showed marginally greater anisohydry than gymnosperms. Leaf water potential at the turgor loss point (Ψtlp) and wood density were the two most powerful proxies for ranking the degree of plant iso/anisohydry for a wide range of species and biomes. Both of these simple traits can be easily and rapidly determined, and therefore show promise for a priori mapping and understanding of the global distribution pattern of the degree of plant iso/anisohydry. Generally, the most anisohydric species had the most negative values of Ψtlp and highest wood density, greatest resistance to embolism, lowest hydraulic capacitance and lowest leaf-specific hydraulic conductivity of their branches. Wood density in particular appeared to be central to a coordinated series of traits, trade-offs and behaviors along a continuum of iso/anisohydry. Quantification of species' operating ranges along a continuum of iso/anisohydry and identification of associated trade-offs among functional traits may hold promise for mechanistic modeling of species-specific responses to the anticipated more frequent and severe droughts under global climate change scenarios. [ABSTRACT FROM AUTHOR]

Background and aims: Spatially segregating root systems is a fundamental mechanism by which plants can avoid competition for resources. Understory roots contribute substantially to total forest fine-root biomass, but the strategy of function-based fine root placement between trees and understory species at the plant community level is unknown. The aim of this study was to determine the differences between trees and understory plants in the deployment of fine roots.Methods: We collected fine roots of trees and understory species in two subtropical coniferous forests, sorted the fine roots into absorptive and transport roots, determined the vertical placement of these two types of fine roots, and examined the abiotic and biotic factors that may regulate the horizontal allocation of fine roots.Results: We found that the contribution of absorptive shrub roots to absorptive roots of the woody plants was higher than the contribution of total shrub fine roots to the total fine roots of the woody plants in the topsoil. Understory plants allocated a greater proportion of their absorptive roots to transport roots (RatioA/T) and more total fine-root biomass than trees in the topsoil. Trees had a lower RatioA/T in the topsoil; but increased their contribution of fine-root biomass to the total fine-root biomass and RatioA/T with depth. The proliferation of shrub fine roots in the topsoil was affected more by soil structure (rock-fragment content and bulk density) than by nearby stems, and the growth of tree fine roots was inhibited by nearby dense and/or large stems.Conclusions: Our results provide evidence of an elaborate differentiation of root deployment between trees and understory plants. The roots of understory plants dominated the topsoil by possessing a higher branching capacity of absorptive roots than trees, filling the readily occupied macropores and being less affected by nearby stems. Trees enhance their resource foraging towards deeper soil by increasing their advantage of occupying soil volume and branching capacity of absorptive roots with depth. We also suggested that the roots of understory plants may affect ecosystemic carbon and nutrients cycling more than expected because of the disproportionately higher investment of absorptive roots in the topsoil. [ABSTRACT FROM AUTHOR]

Placement of the division site at midcell in Escherichia coli requires the MinE protein. MinE acts by imparting topological specificity to the MinCD division inhibitor, preventing the inhibitor from acting at the midcell site while permitting it to block division at other unwanted sites along the length of the cell. It was previously shown that MinE assembled into a ring structure that appeared to be localized near midcell, apparently explaining the ability of MinE to specifically counteract MinCD at midcell. We report here that the MinE ring is not fixed in position near midcell but is a dynamic structure that undergoes a repetitive cycle of movement first to one cell pole and then to the opposite pole. Taken together with studies of the dynamic behavior of the MinD protein, the results suggest that the topological specificity of division site placement may not involve a localized action of MinE to counteract the MinCD division inhibitor at midcell but rather the ability of MinE to move the division inhibitor away from midcell and to the cell poles.

Nitrogen (N) and phosphorus (P) additions can affect soil microbial carbon (C) accumulation. However, the mechanisms that drive the changes in residual microbial C that occur after N and P additions have not been well-defined for Chinese fir plantations in subtropical China. We set up six different treatments, viz. a control (CK), two N treatments (N1: 50 kg ha−1 a−1; N2: 100 kg ha−1 a−1), one P treatment (P: 50 kg ha−1 a−1), and two combined N and P treatments (N1P: 50 kg ha−1 a−1 of N + 50 kg ha−1 a−1 of P; N2P: 100 kg ha−1 a−1 of N + 50 kg ha−1 a−1 of P). We then investigated the influences of N and P additions on residual microbial C. The results showed that soil pH and microbial biomass decreased after N additions, while microbial biomass increased after P additions. Soil organic carbon (SOC) and residual microbial C contents increased in the N and P treatments but not in the control. Residual microbial C accumulation varied according to treatment and declined in the order: N2P > N1P > N2 > N1 > P > CK. Residual microbial C contents were positively correlated with available N, P, and SOC contents, but were negatively correlated with soil pH. The ratio of residual fungal C to residual bacterial C increased under P additions, but declined under combined N + P additions. The ratio of residual microbial C to SOC increased from 11 to 14% under the N1P and N2P treatments, respectively. Our results suggest that the concentrations of residual microbial C and the stability of SOC would increase under combined applications of N and P fertilizers in subtropical Chinese fir plantation soils. [ABSTRACT FROM AUTHOR]

Summary: Fine roots of woody plants comprise multiple root orders, which can be functionally partitioned into two pools: absorptive fine roots (AFRs, orders 1, 2) and transport fine roots (TFRs, orders 3–5). However, the function‐based fine‐root dynamics and especially their responses to increased nitrogen (N) availability remain unclear. We explored dynamic responses of both AFRs and TFRs of Pinus elliottii to N addition in subtropical China based on a 4‐yr minirhizotron experiment and a two‐stage – early (0.5 yr) vs late (4 yr) – decomposition experiment. N addition increased the production, mortality, and turnover of AFRs but not TFRs. High rates of N persistently inhibited AFR decomposition but affected TFR decomposition differentially at the early (no effect) and late (negative effect) stages. The increased production of AFRs was driven by N‐induced decrease in foliar and soil phosphorus (P) concentrations. The decreased decomposition of AFRs might be due to the increased acid‐unhydrolyzable residues in decomposing roots. AFRs are the resource‐acquiring module, the increased carbon allocation to AFRs may represent a P‐acquiring strategy when N no longer limits growth of P. elliottii. Our results suggest that AFRs and TFRs respond differently to N deposition, both in terms of production, mortality, and turnover and in terms of decomposition. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Young leaves are conventionally used in the analysis to study the nutrient status of evergreen plants and their responses to environmental changes, but the role of old leaves remains poorly understood. We selected two stand types in 31-year-old Chinese fir ( Cunninghamia lanceolata) plantations with similar soil conditions but different stand densities, to test the hypothesis that nitrogen (N) concentration of old leaves and twigs is more sensitive to stand density than that of young ones. Leaves and twigs were sampled and sorted into young (one-year-old) and old (two- and three-year-old) groups. Significant differences in N concentration and carbon: nitrogen ratio between the low-density stand and high-density stand were only found in the old leaves and twigs but not in the young ones. Although the N resorption efficiency did not vary significantly with stand density, the annual N resorption rates were increased in old leaves and relatively young twigs at high stand density. These results show the potential use of old tissues in the nutrient analysis in Chinese fir plantations. Testing the generality of these results could improve the use of foliar analysis as an indicator of nutrient status and environmental changes in evergreen tree species. [ABSTRACT FROM AUTHOR]

Background: There is sufficient evidence supporting a relationship between increased body mass index (BMI) and an increased risk for breast cancer among postmenopausal women. However, most studies have found a decreased risk for premenopausal breast cancer. This study was conducted to find out the different effects of BMI on the risk of breast cancer among premenopausal and postmenopausal women, and explore the potential factors that influence the associations.Methods: A dose-response meta-analysis with 3,318,796 participants from 31 articles was conducted. Cohort studies that included BMI and corresponding breast cancer risk were selected through various databases including PubMed, Medline, Web of Science, the China National Knowledge Infrastructure (CNKI) and Chinese Scientific Journals (VIP). Random effects models were used for analyzing the data.Results: The summary relative risks (RRs) were 1.33 (95%CI: 1.20-1.48) and 0.94(95%CI: 0.80-1.11) among postmenopausal and premenopausal women, respectively. The dose-response meta-analysis indicated a positive non-linear association between BMI and breast cancer risk among postmenopausal women, and compared to the mean level of the normal BMI category (21.5 kg/m2) the RR in total postmenopausal women were1.03 (95% CI: 1.02-1.05) per 1 kg/m2 increment. However, no statistically significant association among total premenopausal women was detected. In subgroup analysis among European premenopausal women, the summary RR was 0.79(95%CI: 0.70-0.88). The non-linear relationship showed a negative non-linear association between BMI and breast cancer risk among European premenopausal women. When compared to the mean level of the normal BMI category, the RRs were 0.98 (95%CI: 0.96-1.00) per 1 kg/m2 increment, respectively.Conclusions: In line with previous studies BMI had different effects on pre-menopausal and postmenopausal breast cancer risk. However, contrary to previous studies, a high BMI was not associated with decreased risk in total pre-menopausal women. More research is needed to better understand these differences. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microcystin-LR (MC-LR), one of aquatic environmental contaminants with reproductive toxicity produced by cyanobacterial blooms, but its toxic effects and mechanisms on the ovary are not fully understood. Here, proteomic techniques and molecular biology experiments were performed to study the potential mechanism of MC-LR-caused ovarian toxicity. Results showed that protein expression profile of ovarian granulosa cells (KK-1) was changed by 17 μg/mL MC-LR exposure. Comparing with the control group, 118 upregulated proteins as well as 97 downregulated proteins were identified in MC-LR group. Function of differentially expressed proteins was found to be enriched in pathways related to adherent junction, such as cadherin binding, cell-cell junction, cell adhesion and focal adherens. Furthermore, in vitro experiments, MC-LR significantly downregulated the expression levels of proteins associated with adherent junction (β-catenin, N-cadherin, and α-catenin) as well as caused cytoskeletal disruption in KK-1 cells (P < 0.05), indicating that the adherent junction was damaged. Results of in vivo experiments have shown that after 14 days of acute MC-LR exposure (40 μg/kg), damaged adherent junction and an increased number of atretic follicles were observed in mouse ovaries. Moreover, MC-LR activated JNK, an upstream regulator of adherent junction proteins, in KK-1 cells and mouse ovarian tissues. In contrast, JNK inhibition alleviated MC-LR-induced adherent junction damage in vivo and in vitro , as well as the number of atretic follicles. Taken together, findings from the present study indicated that JNK is involved in MC-LR-induced granulosa cell adherent junction damage, which accelerated follicular atresia. Our study clarified a novel mechanism of MC-LR-caused ovarian toxicity, providing a theoretical foundation for protecting female reproductive health from environmental pollutants. [Display omitted] • MC-LR exposure can alter the protein expression profile in ovarian granulosa cells. • MC-LR can induce β-catenin degradation in mouse ovarian granulosa cells. • JNK-mediated adherent junction damage is involved in MC-LR-induced follicular atresia. • Inhibition of JNK contributes to alleviating MC-LR-induced ovarian toxicity. [ABSTRACT FROM AUTHOR]

Dental fluorosis (DF) is a widely prevalent disease caused by excessive fluoride with limited awareness of its underlying pathogenesis. Here, a pilot population study was conducted to explore the pathogenesis of DF from the perspective of intestinal microbiome changes, and verified it in animal experiments combining intestinal microbiome and metabolomics. A total of 23 children were recruited in 2017 in China and divided into DF (n = 9) and control (n = 14) groups (DFG and CG, respectively). The SD rat model was established by drinking water containing sodium fluoride (NaF). Gut microbiome profiles of children and rats were analyzed by16S rDNA V3-V4 sequencing, and the intestinal metabolomics analysis of rats was performed by LC-MS methods. The 16 S rDNA sequencing revealed that the gut microbiome composition was significantly perturbed in children in DFG compared to that in CG. Acidobacteria and Thermi were specifically observed in DFG and CG, respectively. Besides, 15 fecal microbiotas were significantly altered at the genus level in DFG. Furthermore, only the expression of annotated genes for pentose and glucuronate interconversion pathway was significant lower in DFG than that in CG (P = 0.04). Notably, in NaF-treated rats, we also observed the changes of some key components of pentose and glucuronate interconversion pathway at the level of microorganisms and metabolites. Our findings suggested that the occurrence of DF is closely related to the alteration of intestinal microorganisms and metabolites annotated in the pentose and glucuronate interconversion pathway. [Display omitted] • The intestinal microorganisms in children is detected by 16 S rDNA sequencing. • The changes of intestinal microorganisms and metabolites in rats are detected. • Annotated genes for pentose and glucuronate interconversion pathway is significantly changed in DF children. • Several components of pentose and glucuronate interconversion pathway are changed in DF rats. [ABSTRACT FROM AUTHOR]

In the optimization design of a pre-bend wind turbine blade, there is a coupling relationship between blade aerodynamic shape and structural layup. The evaluation index of a wind turbine blade not only shows on conventional ones, such as Annual energy production (AEP), cost, and quality, but also includes the size of the loads on the hub or tower. Hence, the design of pre-bend wind turbine blades is a true multi-objective engineering task. To make the integrative optimization design of the pre-bend blade, new methods for the blade's pre-bend profile design and structural analysis for the blade sections were presented, under dangerous working conditions, and considering the fundamental control characteristics of the wind turbine, an integrated aerodynamic-structural design technique for pre-bend blades was developed based on the Multi-objective particle swarm optimization algorithm (MOPSO). By using the optimization method, a three-dimensional Pareto-optimal set, which can satisfy different matching requirements from overall design of a wind turbine, was obtained. The most suitable solution was chosen from the Pareto-optimal set and compared with the original 1.5 MW blade. The results show that the optimized blade have better performance in every aspect, which verifies the feasibility of this new method for the design of pre-bend wind turbine blades. [ABSTRACT FROM AUTHOR]