Dear Sir. Concerning your issue about the commercial kit or tecnique for extract DNA from zooplancton. Molecular approaches are widely applied in species identification and taxonomic studies of minute zooplankton. One of the most focused zooplankton nowadays is from Subclass Copepoda. Accurate species identification of all life stages of the generally small sized copepods through molecular analysis is important, especially in taxonomic and systematic assessment of harpacticoid copepod populations and to understand their dynamics within the marine community. However, total genomic DNA (TGDNA) extraction from individual harpacticoid copepods can be problematic due to their small size and epibenthic behavior. In this research, six TGDNA extraction methods done on individual harpacticoid copepods were compared. The first new simple, feasible, efficient and consistent TGDNA extraction method was designed and compared with the commercial kit and modified available TGDNA extraction methods. The newly described TGDNA extraction method, “Incubation in PCR buffer” method, yielded good and consistent results based on the high success rate of PCR amplification (82%) compared to other methods. Coupled with its relatively consistent and economical method the “Incubation in PCR buffer” method is highly recommended in the TGDNA extraction of other minute zooplankton species. Freshwater ostracods are ecologically and evolutionarily important small free-living crustaceans occurring in lakes, rivers and small water bodies. However, despite their importance, only a few genetic studies have been conducted so far in ostracoda due to isolation of insufficient amounts of DNA. We present a simple, efficient and cost-effective total DNA extraction protocol from freshwater ostracods for PCR amplification. Total DNA was extracted from four freshwater ostracods; Heterocypris incongruens, Cypridopsis vidua, Eucypris virens and Herpetocypris chevreuxi. We also compared the performance of our protocol with two manual DNA extraction protocols (HotSHOT, Chelex-100) and a commercial kit (Highpure PCR template preparation kit-Roche). The success of the isolation protocol was tested by PCR and sequencing of 18S rRNA and COI regions. Although our technique, Roche and HotSHOT methods resulted in acceptable DNA concentrations and showed an amplifiable band of expected size, both our protocol and Roche generally gave better results than HotSHOT, whereas the poor results were obtained from Chelex protocol. Therefore, we suggest that filter-based DNA isolation is more reproducible than other protocols. Our protocol requires no hazardous organic solvents and adaptable to 0.5 mL 8-strip PCR tubes format facilitating DNA extraction from a large number of samples. I think the following below links may help you in your analysis:

http://www.genaqua.org/uploads/pdf_2.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5130931/pdf/40064_2016_Article_3724.pdf http://homepages.cs.ncl.ac.uk/lucy.eland/publications/eland2012.pdf

Thanks

Isam Eldin Hussein Elgailani Thank you so much for your help, It was very useful!

Kazım Köse