Impacts of continuous cropping on the rhizospheric and endospheric microbial communities and root exudates of Astragalus mongholicus.

Astragalus mongholicus is a medicinal plant that is known to decrease in quality in response to continuous cropping. However, the differences in the root-associated microbiome and root exudates in the rhizosphere soil that may lead to these decreases are barely under studies. We investigated the plant biomass production, root-associated microbiota, and root exudates of A. mongholicus grown in two different fields: virgin soil (Field I) and in a long-term continuous cropping field (Field II). Virgin soil is soil that has never been cultivated for A. mongholicus. Plant physiological measurements showed reduced fresh and dry weight of A. mongholicus under continuous cropping conditions (i.e. Field II). High-throughput sequencing of the fungal and bacterial communities revealed differences in fungal diversity between samples from the two fields, including enrichment of potentially pathogenic fungi in the roots of A. mongholicus grown in Field II. Metabolomic analysis yielded 20 compounds in A. mongholicus root exudates that differed in relative abundance between rhizosphere samples from the two fields. Four of these metabolites (2-aminophenol, quinic acid, tartaric acid, and maleamate) inhibited the growth of A. mongholicus, the soil-borne pathogen Fusarium oxysporum, or both. This comprehensive analysis enhances our understanding of the A. mongholicus microbiome, root exudates, and interactions between the two in response to continuous cropping. These results offer new information for future design of effective, economical approaches to achieving food security.

Granular bacterial inoculant alters the rhizosphere microbiome and soil aggregate fractionation to affect phosphorus fractions and maize growth.

The constraint of phosphorus (P) fixation on crop production in alkaline calcareous soils can be alleviated by applying bioinoculants. However, the impact of bacterial inoculants on this process remains inadequately understood. Here, a field study was conducted to investigate the effect of a high-concentration, cost-effective, and slow-release granular bacterial inoculant (GBI) on maize (Zea mays L.) plant growth. Additionally, we explored the effects of GBI on rhizosphere soil aggregate physicochemical properties, rhizosphere soil P fraction, and microbial communities within aggregates. The outcomes showed a considerable improvement in plant growth and P uptake upon application of the GBI. The application of GBI significantly enhanced the AP, phoD gene abundance, alkaline phosphatase activity, inorganic P fractions, and organic P fractions in large macroaggregates. Furthermore, GBI impacted soil aggregate fractionation, leading to substantial alterations in the composition of fungal and bacterial communities. Notably, key microbial taxa involved in P-cycling, such as Saccharimonadales and Mortierella, exhibited enrichment in the rhizosphere soil of plants treated with GBI. Overall, our study provides valuable insight into the impact of GBI application on microbial distributions and P fractions within aggregates of alkaline calcareous soils, crucial for fostering healthy root development and optimal crop growth potential. Subsequent research endeavors should delve into exploring the effects of diverse GBIs and specific aggregate types on P fraction and community composition across various soil profiles.

[Characteristics and Sources of Dissolved Heavy Metals in Summer Precipitation of Taiyuan City, China].

To investigate the characteristics and sources of dissolved heavy metals in precipitation of Taiyuan, 61 precipitation samples were collected using an automated dry and wet sampler from 2013 to 2015 during summertime. The concentrations of 12 dissolved heavy metals were detected using ICP-MS, and wet deposition fluxes and sources were analyzed. The results showed that the pH ranged from 4.34 to 7.95, with a volume-weighted mean of 5.37. The mean concentration of the dissolved heavy metals was 236.931 µg·L-1, with a range of 66.324 to 1029.212 µg·L-1. Zn and Fe were the major components, together accounting for 53.39% of the total concentrations. The wet deposition fluxes of the 12 dissolved heavy metals reached 1.735 mg·(m2·d)-1. The enrichment factors of Ba, Cu, Sr, Zn, As, Cd, and Pb were all in excess of 100, suggesting that these metals were seriously influenced by anthropogenic activities. Results from positive matrix factorization (PMF) indicated that steel smelting emissions, coal combustion, vehicle emissions, and crustal dusts were the major sources of heavy metals in the precipitation of Taiyuan City, with average contributions of 38.34%, 23.06%, 20.45%, and 18.15%, respectively. According to backward trajectory analysis, air masses from the southwest and southeast directions contributed the most to precipitation during summer in Taiyuan, with percentages of 38 and 35, respectively. The southern industrial areas located in the Yuncheng-Linfen-Jinzhong and Jincheng-Changzhi-Jinzhong regions should be paid more attention.

[Serum retinol binding protein 4 and bone metabolism in patients with type 2 diabetes].

OBJECTIVE: To determine the relation between serum concentration of retinol binding protein (RBP) 4 and markers of bone metabolism, bone mineral density (BMD) in patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 82 patients newly diagnosed with T2DM and 46 subjects with normal glucose tolerance (NGT) enrolled in the cross-sectional study. Subset analyses were performed, dividing subjects on the basis of gender into M-T2DM, F-T2DM, M-NGT, and F-NGT. The serum concentrions of RBP4, osteocalcin (OC) and C-terminal telopeptide of collagen type I (CTX) were measured with ELISA. The BMD was measured by dual-energy X-ray absorptiometry (DXA) with a Hologic QDR4500A device. RESULTS: In both the T2DM groups, lnRBP4 showed a positive relationship with lnCTX (M-T2DM, r=0.564, P<0.01; F-T2DM, r=0.386, P=0.018), but no association with lnOC. After adjusting for age, smoking, creatinine clearance rate (CCr), and waist-to-hip ratio (WHR), lnRBP4 still showed a strong association with lnCTX in the M-T2DM group (r'=0.536, P<0.01), but not in F-T2DM (r'=0.317, P=0.072). In the NGT group, there was no relation between lnRBP4 and lnCTX or lnOC. LnRBP4 showed no association with BMD in all groups. CONCLUSION: The level of serum RBP4 may be correlated with the bone metabolism in patients with T2DM.

[Effect of body composition on bone mineral density in males with different glucose tolerance].

OBJECTIVE: To investigate the effect of body composition on bone mineral density (BMD) in males with different glucose tolerance. METHODS: A total of 87 male subjects aged 35~64 years were divided into 2 groups by glucose tolerance test, 57 diagnosed T2DM and 30 with normal glucose tolerance(NGT). BMDs of anteroposterior lumbar vertebrae (AP), left femur neck (FN), total hip (T-hip), and total bone mineral density(TBMD)were measured by dual-energy-X-ray absorptiometry (DEXA). Body composition was also measured by DEXA, while fat tissue mass(FTM), lean tissue mass(LTM), percentage of truncal fat (Tru-fat%) and total fat (Fat%) were computed. The effect of body composition on the BMD of the 2 groups was analyzed. RESULTS: LTM and FN-BMD had a positive correlation in the NGT group, but no correlation in the T2DM group. The percentage of fat showed a negative relationship with the BMD of AP in the T2DM group, but not in the NGT group. The percentage of fat and total BMD had a negative association in both the NGT and the T2DM groups. In the NGT group, LTM was the independent predictor of BMD of AP,FN and hip (b=0.509, 0.411, and 0.585; P<0.01 or 0.05; R2=0.169~0.342). In the T2DM group, LTM was the independent predictor of BMD of AP (b=0.330, P<0.05, R2=0.109) and hip (b=0.462, P<0.01,R2=0.213), but not FN. CONCLUSION: LTM has an attenuated effect on the BMD in male patients with T2DM compared with patients with NGT. An increased percent of fat percent is harmful to preserve bone mass in male adults, regardless of normal glucose tolerance or T2DM.

[Association of serum testosterone with lean body mass, body fat content, and bone mineral density in postmenopausal females].

OBJECTIVE: To determine the relationship between serum testosterone level and lean body mass, body fat content, and bone mineral density (BMD). METHODS: The study involved 185 healthy females in Changsha, aged 45-81. Fasting serum testosterone was measured by radioimmunoassay. Hologic QDR 4500A fan beam X-ray bone densitometer was used to measure the BMD of anteroposterior lumber (AP, L(1-4)) and total hip,to measure the bone mineral content, BMD, body fat content and muscle tissue weight of head, trunk, ribs, pelvis, spine, upper limbs, lower limbs and the total body. Body weight, lean body mass and body fat percentage were calculated. SPSS11.0 software was used to conduct regression analysis. RESULTS: (1) Serum testosterone showed no correlation with lean body mass, body fat content, and body fat percentage. (2) Serum testosterone was positively related with the BMD of lumbar spine and hip, but showed no correlation with the BMD after adjustment of age and years since postmenopause. (3) Lean body mass showed significant positive correlation with the BMD of different sites. Total body fat content showed positive correlation with the BMD of total hip, while body fat percentage showed negative correlation with the BMD of the whole body. CONCLUSION: Keeping lean body mass benefits postmenopausal women to maintain bone mineral content, and taking androgen should still be cautious.

[Change in bone mineral density in female patients with hyperthyroidism].

OBJECTIVE: To investigate the effect of the course and menopause on the change of bone mineral density (BMD) in female patients with hyperthyroidism. METHODS: BMDs of hip and lumbar vertebrae were measured by dual-energy X-rays absorptiometry(DEXA) in the female patients (n=192, aged 14 approximately 72). Patients were divided into 2 groups (premenopausal and postmenopausal)and 2 subgroups(short-course and long-course). The BMDs were compared between those of age-matched, weight-matched, height-matched and body mass index matched control subgroups. RESULTS: In the premenopausal hyperthyroidic patients, only the BMDs of the second and total lumbar vertebrae with long-course were significantly lower than those of short-course group(P< 0.05). In the post-menopausal group with the long-course,each BMD measured had a lower level compared with that with short-course, of which the hip and the second lumber vertebrae were evident (P< 0.01). CONCLUSION: The course and menopause have an effect on the BMDs in female patients with hyperthyroidism.