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Plants allocate a substantial amount of C belowground for root exudates and for the construction and adjustment of root morphological and architectural traits. What relationships exist between root exudates and other root traits and these relationships change with growing season, however, remain unclear. We quantified the root exudation rate and root morphological traits, including total root length (RL), total root surface area (RS), root diameter (RD), specific root length (SRL), specific root area (SRA) and root tissue density (RTD), and architectural traits, such as branching intensity (BI), and investigated their associations during the rapidly growing season (April and August) and the slowly growing season (December) of three common native tree species, Liquidambar formosana , Michelia maudiae and Schima superba , in subtropical China. We found that the linkages of RD, SRL, SRA, RTD and BI did not change with the growing season, reflecting their highly conservative relationships. The root exudation rate varied significantly with growing season (P  < 0.05) and produced various associations with other root traits at different growing seasons. During the rapidly growing season (i.e. April), the exudation rate was the highest and was positively correlated with RL. The exudation rate was the lowest during the slowly growing season (i.e. December) and was negatively associated with RL, RS and RTD. Our findings demonstrate the seasonality of the linkages of root exudation rate with other root traits, which highlights the highly plastic and complex associations of belowground root traits. These findings help to deepen our understanding of plant nutrient acquisition strategies. [ABSTRACT FROM AUTHOR]

Xylan is the second most abundant polysaccharide group in plants and has a wide variety of food and pharmaceutical applications. However, little information on the safety assessment of extracted xylan as dietary supplement is available. As part of a comprehensive toxicological assessment, this study examined the potential toxicity of xylan extracted from sugarcane bagasse by three genotoxicity studies (Ames test, in vivo mice bone marrow micronucleus test, and mice sperm abnormality test) and a teratogenicity study in rats. In the Ames test, xylan showed no mutagenic activity on histidine dependent strains of Salmonella typhimurium at concentrations up to 5000 μg/plate; results of the in vivo mice bone marrow micronucleus test and mice sperm abnormality test indicated no significant effect on sperm morphology and micronucleus rate of polychromatic erythrocytes in mice at doses up to 5 g/kg body weight. In the teratogenicity study, a total of 60 pregnant rats were exposed to 10, 5, and 2.5% xylan in diet, from gestation days 7 to 16, and the no-observed-adverse-effect levels (NOAEL) of xylan was determined to be 9.8 g/kg body weight. The safe dose of xylan for human was estimated to be 98 mg/kg/day (i.e., 6.86 g/day for a 70-kg person), using a 100-fold safety factor. Taken together, results of this study indicated that xylan is practically nontoxic in terms of potential dietary consumption by humans in food or as a dietary supplement. [ABSTRACT FROM AUTHOR]

Aims: Multi-elemental stoichiometry can represent the biogeochemical niches of species, which can further guide community assemblage. Mycorrhizae play a key role in plant elemental acquisition. Whether and how mycorrhizal type influences the plant multi-elemental stoichiometries and elemental coordination in above- and belowground organs, however, remain unclear. Methods: We determined the concentrations of C, N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, Na, Pb and Sr and some elemental ratios in the leaves and roots of arbuscular mycorrhizal (AM) trees (Phoebe bournei, Schima superba, Michelia maudiae and Cunninghamia lanceolata) and ectomycorrhizal (ECM) trees (Cyclobalanopsis glauca, Pinus massoniana and P. elliottii) in subtropical China. The effects of root traits and soil abiotic factors on elemental concentrations and ratios were reported. Results: The elemental concentrations and ratios differed substantially between the AM and ECM trees, indicating the their biogeochemical niches' differentiation. The C, P, Mg and Mn concentrations and the K:Mg andCa:Mg ratios for AM and the N, Mn and Na concentrations and the Fe:Mn ratio for the ECM species were strongly correlated between leaves and roots, but the correlations were positive or negative depending on elemental composition and mycorrhizal type. The root branching ratio, branching intensity and length played important roles in the plant elemental stoichiometries. Conclusions: The biogeochemical niche's differentiation between the AM and ECM species emphasizes the important role of mycorrhizal type in the assemblage of co-occurring species. This study offers a new opinion for species choosing in mixed forests from the view of the biogeochemical niche's separation. [ABSTRACT FROM AUTHOR]

Cistanche deserticola(C. deserticola), a holoparasitic plant widely distributed in arid or semi-arid areas in Eurasia and North Africa, has been used as an important tonic in traditional Eastern medicine for centuries. However, little information on the systemic toxicity and safety evaluation of it is available. The purpose of this study was to investigate the potential toxicity of powderedC. deserticolaas a novel food ingredient by use of a subchronic toxicity study in Sprague-Dawley (SD) rats. A total of 80 male and female rats were fed with diets containing 8, 4, 2 and 0% (control) powderedC. deserticolafor 90 days. A toxicological assessment was performed including mortality, body and organ weight, food consumption, blood biochemistry, hematology, gross necropsy and histopathological examinations. There were no signs of toxicity and treatment-related changes in rats treated with powderedC. deserticola. The no-observed-adverse-effect level (NOAEL) of powderedC. deserticolawas 7.8 g kg−1body weight for males and 8.0 g kg−1body weight for females of rats under the experimental conditions of this study. [ABSTRACT FROM AUTHOR]

Introduction: A combination of zidovudine (AZT), lamivudine (3TC) and lopinavir/ritonavir (LPV/r) is one of the most effective drugs for preventing mother‐to‐child transmission (PMTCT) of HIV. However, limited information is available regarding its systemic toxicity. This study aimed to investigate its potential toxicity. Method: An acute oral toxicity test was conducted to assess the potential acute toxicity of AZT + 3TC + LPV/r. Bacterial reverse mutation, mammalian erythrocyte micronucleus and mouse spermatogonia chromosomal aberration tests were conducted to assess its potential genotoxicity. A 28‐day feeding test was conducted to assess the potential subacute toxicity. Results: In mice, the LD50 of the AZT + 3TC + LPV/r mixture was greater than 2000 mg/kg body weight (BW). The rate of micronucleated polychromatic erythrocytes (PCEs) increased in a dose‐dependent manner in mice (P < 0.01). After treatment with AZT + 3TC + LPV/r for 28 days, the BW gain of male and female rats in the high‐dose group was lower than that in the control group (P < 0.05); the relative weights of the liver, kidney, spleen and brain increased (P < 0.05); and pathological abnormalities appeared in the thyroid and spleen of male and female rats in the high‐dose group. The haemoglobin (HGB) and red blood cells (RBCs) count in male and female rats decreased, but the white blood cells (WBCs) and lymphocyte apoptosis rates in male and female rats in the high‐dose group increased (P < 0.05). The total protein, albumin, cholesterol and blood glucose levels of male and female rats in the high‐dose group were significantly decreased (P < 0.05). The alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine (Cr) and blood urea nitrogen (BUN) levels of male and female rats in the medium‐ and high‐dose groups increased significantly (P < 0.05). Conclusion: The results suggest that AZT + 3TC + LPV/r may exhibit genotoxicity and subacute toxicity under experimental conditions. [ABSTRACT FROM AUTHOR]