Extraradical hyphae alleviate nitrogen deposition-induced phosphorus deficiency in ectomycorrhiza-dominated forests.

The continuous imbalance between nitrogen (N) and phosphorus (P) deposition is expected to shift many ecosystems from N- to P limitation. Extraradical hyphae of ectomycorrhizal (ECM) fungi play important roles in plant nutrient acquisition under nutrient deficiency. However, whether and how ECM hyphae enhance soil P availability to alleviate N-induced P deficiency remains unclear. We investigated the impacts of ECM hyphae on transformations among different soil P fractions and underlying mechanisms under N deposition in two ECM-dominated forests. Ectomycorrhizal hyphae enhanced soil P availability under N addition by stimulating mineralization of organic P (Po) and desorption and solubilization of secondary mineral P, as indicated by N-induced increase in positive hyphal effect on plant-available P pool and negative hyphal effects on Po and secondary mineral P pools. Moreover, ECM hyphae increased soil phosphatase activity and abundance of microbial genes associated with Po mineralization and inorganic P solubilization, while decreasing concentrations of Fe/Al oxides. Our results suggest that ECM hyphae can alleviate N-induced P deficiency in ECM-dominated forests by regulating interactions between microbial and abiotic factors involved in soil P transformations. This advances our understanding of plant acclimation strategies via mediating plant-mycorrhiza interactions to sustain forest production and functional stability under changing environments.

Extraradical hyphae exhibit more plastic nutrient-acquisition strategies than roots under nitrogen enrichment in ectomycorrhiza-dominated forests.

Ectomycorrhizal (ECM) functional traits related to nutrient acquisition are impacted by nitrogen (N) deposition. However, less is known about whether these nutrient-acquisition traits associated with roots and hyphae differentially respond to increased N deposition in ECM-dominated forests with different initial N status. We conducted a chronic N addition experiment (25 kg N ha-1 year-1 ) in two ECM-dominated forests with contrasting initial N status, that is, a Pinus armandii forest (with relatively low N availability) and a Picea asperata forest (with relatively high N availability), to assess nutrient-mining and nutrient-foraging strategies associated with roots and hyphae under N addition. We show that nutrient-acquisition strategies of roots and hyphae differently respond to increased N addition. Root nutrient-acquisition strategies showed a consistent response to N addition, regardless of initial forest nutrient status, shifting from organic N mining toward inorganic N foraging. In contrast, the hyphal nutrient-acquisition strategy showed diverse responses to N addition depending on initial forest N status. In the Pinus armandii forest, trees increased belowground carbon (C) allocation to ECM fungi thus enhancing hyphal N-mining capacity under increased N availability. By comparison, in the Picea asperata forest, ECM fungi enhanced both capacities of P foraging and P mining in response to N-induced P limitation. In conclusion, our results demonstrate that ECM fungal hyphae exhibit greater plasticity in nutrient-mining and nutrient-foraging strategies than roots do in response to changes of nutrient status induced by N deposition. This study highlights the importance of ECM associations in tree acclimation and forest function stability under changing environments.

Analysis of clinical characteristics and prognostic factors of elderly patients with renal cell carcinoma based on the SEER database.

To study the difference of clinical characteristics and prognostic factors from elderly patients with renal cell carcinoma (RCC), the statistical analysis was carried out based on the surveillance, epidemiology, and end results database. The relevant clinical information of 19,472 RCC patients from 2010 to 2015 were collected, and the differences of clinicopathological characteristics and survival rate was analyzed by log-rank method and Chi square test, respectively. Multivariate Cox regression model was used to explore the independent risk factors affecting the long-term survival of RCC patients. Results showed that the proportion of elderly RCC patients in the 60-64-year group in 2010 was 15.20%, but the value elevated to 18.51% in 2015, and the Chi-square test revealed the significant correlation between elderly RCC patients with gender, race, American Joint Committee on cancer stage, T stage, N stage, and M stage. The difference of survival time between the 60-69 year, 70-79 year, 80-84 year, and 85+ year group was significant, and Kaplan-Meier analysis showed a negative effects of age on survival rate of RCC patients, indicating a worsening trend with increasing age. Cox proportional hazards model analysis further confirmed that age was the important independent prognostic factor. Our study reveals that the onset age of RCC in elderly population is gradually decreasing, and the malignant degree of elderly RCC patients is increasing with age. The female elderly population could be more susceptible to RCC than male elderly population, and 85+ year population could also be cancer susceptible with a higher lymph node metastasis rate, later tumor stage, and poor prognosis, suggesting that these elderly populations should pay more attention to the RCC screening.

[Research progress of root exudates collection technology]. / æ ¹ç³»åˆ†æ³Œç‰©æ”¶é›†æŠ€æœ¯ç ”ç©¶è¿›å±•.

Root exudates play an important role in mediating the exchange of substrates, energy and information within the rhizosphere in terrestrial ecosystems. Constructing accurate and applicable sampling system of root exudates to precisely collect the characters including the component and concentration of root exudates and their responses to changing environments are a critical link and prerequisite to understand ecological processes and information exchanges across the root-soil interface. While both traditional and novel techniques for collecting root exudates aim to explore the diversity and concentration of root exudates, current exudate-collection methods could hardly avoid the damage of root system, the adsorption and release of root exudates by soil particles, and distur-bance from microbial metabolism, largely because plant roots are highly associated with the surrounding substrates and environments supporting their growth. Therefore, all root exudate collection methods have their own merits and shortcomings. We systematically reviewed the widely-used traditional and novel root exudates collection techniques and compared their advantages and disadvantages. Furthermore, considering the significance and authenticity of field study on the rhizosphere ecological processes in forest ecosystems, we proposed three frontier research directions regarding the construction of techniques for collecting root exudates in forest ecosystems according to the limits of current studies, aiming to provide foundation for related studies in the future.