NOTE OPTIMIZATION OF DNA EXTRACTION FROM BROWN ALGAE (PHAEOPHYCEAE) BASED ON A COMMERCIAL KIT 1 Alodie Snirc 2 UMS 2700, Service de Syste ´matique Mole ´culaire, De ´partement Syste ´matique et Evolution, Muse ´um National d’Histoire Naturelle – IMAGENE, 57 rue Cuvier CP 26, 75231 Paris Cedex 05, France Thomas Silberfeld UMR 7138 Syste ´matique, Adaptation, Evolution, De ´partement Syste ´matique et Evolution, Muse ´um National d’Histoire Naturelle, 57 rue Cuvier CP39, 75231 Paris Cedex 05, France Jacques Bonnet Plateforme ge ´nomique fonctionnelle, Universite ´ Bordeaux 2, 146 rue Le ´o Saignat, 33076 Bordeaux Cedex, France Annie Tillier UMS 2700, Service de Syste ´matique Mole ´culaire, De ´partement Syste ´matique et Evolution, Muse ´um National d’Histoire Naturelle, 57 rue Cuvier CP 26, 75231 Paris Cedex 05, France Sophie Tuffet IMAGENE, 2 alle ´e du Doyen Georges Brus, 33600 Pessac, France and Jian-Sheng Sun USM 0503, UMR 5153 CNRS-MNHN, U565 INSERM, De ´partement Re ´gulation, De ´veloppement et Diversite ´ Mole ´culaire, Muse ´um National d’Histoire Naturelle, 57 rue Cuvier CP 26, 75231 Paris Cedex 05, France Large-scale DNA molecular studies require reli- able and efficient tools for DNA extractions. How- ever, for some plant species and brown algae, isolation of high-quality DNA is difficult. We devel- oped a novel method for isolating high-quality DNA from the polysaccharide-rich and polyphenol-rich brown algae based on a commercial kit and protocol (Qiagen) by optimizing the lysis step and including a chloroform ⁄ isoamyl alcohol supplementary purifi- cation step. DNAs from 24 brown algal species extracted using the original and the modified Qia- gen protocol were compared for yield, quality, and effectiveness in PCR amplification. There was no significant difference in the yields between proto- cols. However, a statistically significant increase in DNA purity was obtained with the modified proto- col, for which the A 260 ⁄ A 280 and A 260 ⁄ A 230 absor- bance ratios averaged 1.66 ± 0.05 and 1.31 ± 0.01, respectively, compared to 1.37 ± 0.04 and 0.52 ± 0.04 with the original protocol. DNAs extracted by the modified procedure were more suc- cessfully amplified by PCR (nuclear, mitochondrial, and chloroplastic regions) than DNAs extracted using the original commercial kit and protocol. Importantly, the modified protocol can be applied in a high-throughput (e.g., 96-well plate) format, allowing a higher efficiency for downstream molecu- lar analysis. In addition, improved DNA quality could increase its stability for long-term storage. Key index words: brown algae; commercial kit; DNA extraction; fluorometry; optimization; PCR; quantification; spectrophotometry Abbrevations: CIA, chloroform ⁄ isoamyl alcohol; PVP, polyvinylpyrolidone; TBE, Tris Borate EDTA Having sufficient amounts of high-quality DNA is a prerequisite for successful population genetic and molecular phylogenetic studies. However, for some taxa, isolation of high-quality DNA is difficult due to various secondary compounds that might be co-isolated with genomic DNA. Furthermore, these contaminants can cause further difficulties in down- stream DNA applications, such as DNA amplifica- tion or restriction enzyme digestion (Kreader 1996, Huang et al. 2000). This issue is of a particular rele- vance to seaweeds and plants (Varma et al. 2007). The brown algae (class Phaeophyceae) are charac- terized by cell walls containing large amounts of 1 Received 5 March 2009. Accepted 7 December 2009. 2 Author for correspondence: e-mail snirc@mnhn.fr; alodie.snirc@ gmail.com; imagene@imagene.fr. J. Phycol. 46, ***–*** (2010) Ó 2010 Phycological Society of America DOI: 10.1111/j.1529-8817.2010.00817.x 1