This video illustrates the technique for extracting DNA from the species of microbes resident in the termite hindgut. The preparation of a wet mount slide, which is useful for visualizing the gut microbial community is also illustrated, and a tour through the species-rich gut environment is given.
Procedural summary for termite whole-gut DNA extraction:
Protocol:
In our experience, DNA extracted from the microbial communities of wood-feeding termite species like Zootermopis nevadensis is sufficiently pure for PCR template after one round of extraction and purification. However, some termites such as litter-feeding and soil-feeding species may have a higher concentration of humic acids in their gut contents and may require additional purification of gut microbial DNA. The total DNA yield from the guts of 5 Z. nevadensis workers is in the range of 10-30 μg. For termite species significantly smaller or larger than this species, more or fewer specimens may be needed to obtain a similar amount of DNA.
This method can easily be adapted to allow RNA extraction. For RNA extraction, substitute 1x RNAprotect Bacteria reagent from Qiagen (catlog no. 76506) for the ice-cold TE buffer described in step 2 of the protocol. Qiagen RNeasy reagents and columns (catlog no. 74104) should be used in place of the DNeasy purification procedure described above. As DNA can be purified from RNAprotect-stabilized samples and only 300 μL of the approx. 700 μL aqueous layer retrieved in step 7 is required for nucleic acid purification, this method can be used to retrieve both DNA and RNA in parallel from a single sample.
These techniques depend on the extraction and purification of high-quality nucleic acids from the termite gut environment. The extraction technique described in this video is a modified compilation of protocols developed for extraction and purification of nucleic acids from environmental samples (Moré et al., 1994; Berthelet et al., 1996; Purdy et al., 1996; Salmassi & Leadbetter, 2003; Ottesen et al. 2006) and it produces DNA from termite hindgut material suitable for use as template for polymerase chain reaction (PCR).
Material Name | Tipo | Company | Catalogue Number | Comment |
---|---|---|---|---|
PVPP/SDS/phenol | Buffer | homogeneization buffer | ||
DNeasy Tissue Kit | Kit | Qiagen | 77607 | Used according to the protocol for isolation of genomic DNA from crude lysates (Appendix H, product manual version: July 2003) |
TE | Buffer | Sigma | T9285 | 1x buffer (1 mM Tris-HCl, 0.1 mM EDTA, pH 8.0) from 100x concentrate |
zirconia/silica beads | Supplies | BioSpec Products | 11079101z | 0.1 mm |
PVPP | Reagent | Sigma | P6755 | 1% w/v polyvinylpolypyrrolidone prepared from dry reagent as a 1x suspension in TE buffer |
Zootermopsis nevadensis | Animal | Termites | ||
SDS | Reagent | Sigma | L4390 | Sodium dodecyl sulfate 20% soln. in water from dry reagent |
Phenol | Reagent | Sigma | 77607 | TE-saturated, ~73% |
MiniBeadbeater-8 | Tool | BioSpec Products | 963 | |
BSS | Buffered Salt Solution, pH 7.2 | Formulation per liter: 2.5 g K2HPO4, 1.0 g KH2PO4, 1.6 g KCl, 1.4 g NaCl, 0.075 g CaCl, 1 g MgCl, and 10 mL of a 1M soln. of NaHCO3 | ||
AxioPlan-2 | Microscope | Carl Zeiss, Inc. USA | Outfitted with 40x objective, 1.6x optivar and 10x ocular lenses. Samples were viewed using phase contrast illumination |