[Nutrients and Ecological Stoichiometry Characteristics of Typical Wetland Soils in the Lower Yellow River].

Carbon, nitrogen, phosphorus, and potassium in the soil are the necessary nutrient elements for plant growth, and their contents and ecological stoichiometry can reflect the status of soil quality and nutrient limitation. The Huayuankou Yellow River Floating Bridge Wetland in the lower Yellow River was selected as the research object. The methods of ANOVA, redundancy analysis, and linear regression fitting were used to study the contents of organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), and their ecological stoichiometric ratios as well as the limiting elements of soil nutrients, and the key physicochemical properties that affect soil nutrients and their ecological stoichiometry in the wetland were revealed. The results showed that the mean values of ω(SOC), ω(TN), ω(TP), ω(TK), ω(AN), ω(AP), and ω(AK) in wetland soil were 5.46 g·kg-1, 0.60 g·kg-1, 0.28 g·kg-1, 17.06 g·kg-1, 13.75 mg·kg-1, 6.54 mg·kg-1, and 158.56 mg·kg-1, respectively, which showed an increasing trend from the river bank to the shoaly land and were generally higher at the high vegetation coverage areas than at the low vegetation coverage areas. There were significant correlations among SOC, TN, TP, and TK. Soil C/P, C/K, N/P, and N/K showed a consistent trend with soil nutrients, whereas C/N showed the opposite. The coefficients of variation of SOC, TN, AN, N/P, and N/K in the soil exceeded 50.00%, with significant spatial differences. The average value of C/N in wetland soil was 11.882, which was close to the average level of soils in China, whereas the average values of C/P and N/P were 49.119 and 4.516, respectively, both of which were lower than the average level of soils in China, and the N/P of soil was far less than 14, which indicated that N was limited in the soil. The proportion of clay and electrical conductivity combined to explain 61.4% and 43.9% of the variation in the soil nutrients and their ecological stoichiometry, respectively, which were the dominant soil physicochemical properties affecting the soil nutrients and their ecological stoichiometry of Huayuankou Yellow River Floating Bridge Wetland. The research results are helpful to improve our knowledge of nutrients and their influencing factors in the wetland soil of the lower Yellow River and provide an important scientific basis for the ecological restoration and management of the wetland in the lower Yellow River.

[Refining sample preparation procedures for solution 3P-NMR analysis of organic P in sediment].

Solution phosphorus-31 nuclear magnetic resonance spectroscopy (31P-NMR) is a novel technology in characterization of organic phosphorus (P) composition in sediments. This study was aim to refine sample preparation procedures for 31P-NMR, including determination of sample pretreatment, extraction time, sample to extractant ratio and concentration method. The results showed that recovery of P with air dried sample treatment was higher than that for the fresh samples. Most of the P was extracted within the first 8 hours, and the time could extend to 12 to 16 hours in order to improve the recovery of P. Using the extraction ratio [m(sediment): V(extractant)] of 1:8 received more spectral signals compared to 1:20 when both the extracts were concentrated at the same time. No evident loss of P was found when the extract was concentrated at 28 degrees C followed by centrifugation under low temperature.

[Cloning and sequence analysis of full-length cDNA of secoisolariciresinol dehydrogenase of Dysosma versipellis].

OBJECTIVES: To obtain the full-length cDNA sequence of Secoisolariciresinol Dehydrogenase gene from Dysosma versipellis by RACE PCR,then investigate the character of Secoisolariciresinol Dehydrogenase gene. METHODS: The full-length cDNA sequence of Secoisolariciresinol Dehydrogenase gene was obtained by 3'-RACE and 5'-RACE from Dysosma versipellis. RESULTS: We first reported the full cDNA sequences of Secoisolariciresinol Dehydrogenase in Dysosma versipellis. The acquired gene was 991bp in full length, including 5' untranslated region of 42bp, 3' untranslated region of 112bp with Poly (A). The open reading frame (ORF) encoding 278 amino acid with molecular weight 29253.3 Daltons and isolectric point 6.328. The gene accession nucleotide sequence number in GeneBank was EU573789. Semi-quantitative RT-PCR analysis revealed that the Secoisolariciresinol Dehydrogenase gene was highly expressed in stem. Alignment of the amino acid sequence of Secoisolariciresinol Dehydrogenase indicated there may be some significant amino acid sequence difference among different species. CONCLUSION: Obtain the full-length cDNA sequence of Secoisolariciresinol Dehydrogenase gene from Dysosma versipellis.