Complexity and heterogeneity of soil samples have often implied the inclusion of purification steps in conventional DNA extraction for polymerase chain reaction (PCR) assays. Unfortunately the purification steps are also time and labor intensive. Therefore the necessity of DNA purification was re-visited and investigated for a variety of environmental soil samples that contained various amounts of PCR inhibitors. Bead beating and centrifugation was used as the baseline (without purification) method for DNA extraction. Its performance was compared with that of conventional DNA extraction kit (with purification). The necessity criteria for DNA purification were established with environmental soil samples. Using lysis conditions at 3000 rpm for 3 minutes with 0.1 mm glass beads, centrifugation time of 10 minutes and 1:10 dilution ratio, the baseline method outperformed conventional DNA extraction on cell seeded sand samples. Further investigation with PCR inhibitors (i.e., humic acids, clay, and magnesium [Mg]) showed that sand samples containing less than 10 μg/g humic acids and 70% clay may not require purifications. Interestingly, the inhibition pattern of Mg ion was different from other inhibitors due to the complexation interaction of Mg ion with DNA fragments. It was concluded that DNA extraction method without purification is suitable for soil samples that have less than 10 μg/g of humic acids, less than 70% clay content and less than 0.01% Mg ion content.
Centrifugation ; DNA ; DNA, Bacterial ; Glass ; Humic Substances ; Magnesium ; Methods ; Polymerase Chain Reaction ; Population Characteristics ; Soil

OBJECTIVES: To explore the ability of inhibition resistibility of multiple displacement amplification （MDA） in samples with inhibitors. To explain the application and value of MDA in forensic medicine by comparing with using magnetic beads methods （MBM） to purify sample. METHODS: Different concentrations of hemoglobin and humid acid （HA） mixed with DNA samples and then divided the samples into MDA group, MBM group and control group. D3S1358 locus was amplified and detected by polyacrylamide gel electrophoresis detection system and AmpFℓSTR® Identifiler™ Plus Kit-capillary electrophoresis detection system. RESULTS: When hemoglobin concentrations exceed 1 ng/μL or HA concentrations exceed 0.1 ng/μL, amplification products could not be obtained by single-locus system in control group. When hemoglobin concentration exceeds 100 ng/μL or HA concentrations exceed 1 ng/μL, the samples could not be amplified by MBM. Inhibitors in different concentrations were amplified successfully in MDA group without any influence from inhibitors. CONCLUSIONS MDA has the capability to remove the inhibition of hemoglobin and HA, which is better than MBM and has a certain value in forensic practices.
DNA/analysis* ; Electrophoresis, Polyacrylamide Gel ; Forensic Medicine/methods* ; Hemoglobins ; Humans ; Humic Substances ; Nucleic Acid Amplification Techniques

OBJECTIVETo study the influence of humic acid fertilizer on plant growth, assimilation base, dried biomass accumulation, yield, quality and disease infection of Angelica sinensis.

METHODThree kinds of humic acid fertilizer and an amino acid liquid fertilizer were tested in randomized groups at 1 level with 3 times repeat.

RESULTT1 promoted plant and root growth effectively, increased dried biomass accumulation and fresh root average weight remarkably, the yield was increased, the content of ethanol extract was increased by 11.31%. T3 promoted plant and root growth quickly, enlarged leaves area and increased dried plant weight, but effect lasted shortly, the content of ethanol extract was increased by 5.23%. T4 increased more leaves in late growth period, enlarged leaves area, the yield was increased, the content of ethanol extract was increased by 3.09%. T2 increased fresh root average weight remarkably, the yield was increased.

CONCLUSIONHumic acid fertilizer and amino acid liquid fertilizer could effectively promote plant growth, enlarge leaves area, promote dried biomass accumulation and transformation to root and increase yield and content of ethanol extract effectively.

Angelica sinensis ; growth & development ; metabolism ; Biomass ; Fertilizers ; Humic Substances ; Plant Leaves ; growth & development ; metabolism ; Plant Roots ; growth & development ; metabolism