DNA Barcoding Invertebrate #1 - Lab Report Example

Biology Topic: lab report on DNA barcoding Introduction: DNA barcoding provides a versatile tool for ification of organism based on DNA taxonomy and delimitation and ‘discovery’ of new species. Sequences that are used as barcodes are usually those that are unique and conserved within a species. In DNA barcoding, usually a four staged approache is engaged. The first stage is to obtain a specimen which may be from from tissue or culture collections. In the second stage, laboratory analysis which involves extraction of genetic material to obtain DNA batcode sequence is done.

These sequences are later placed in a barcode database such as the Barcode intiative to be used as species identifiers to assign unknown specimens to known species. Currently two such databases exists, the Barcode of life (BOLD) and The International Nucleotide Sequence Database Collaborative which is an intiative of the three main Nucleotide databases, GenBank, EMBL and DDBJ. The fouth and final stage is to carry out an analysis where specimens are identified with the closest matching reference record in the aforementioned databases.

In this lab report, we sought to perform a barcode analysis using mayfly DNA sequences in the BOLD database. The barcode sequence is mainly a short DNA sequence which has a uniform location in the genome and is used to identify species. One of the commonly used sequence in DNA barcoding is the cytochrome oxidase subunit 1 (COI). This was the sequence we used this work. The barcoding process involves identifying a universal locus which has retained enough sequence conservation throughout evolution and can be sourced from many organisms.

This sequence should also be diverse so as to be competent enough to differentiate a target species to the family level. Generally regions of the chloroplast (rbcL gene) and the mitochondria (COI) meet these requirements. Various studies have been undertaken by Herbert et al (2003a, 2004b) and established this COI sequence as the sequence of choice in DNA barcoding in insects and vertebrates. Inverterbrates such as mayfly are collected whole and may be euthanized in a kill jar by placing them in a freezer.

In the lab, primers are designed to target the conserved regions flanking the rbcL or the COI regions.Examples of the barcoding primers which may be used in insects5-GTAAAACGACGGCCAGTATTCAACCAATCATAAAGATATTGG-3 (forward primer - LepF1_t1)5-TGTAAAACGACGGCCAGTTCTCAACCAACCACAAAGACATTGG-3 (forward primer - VF1_t1)5-TGTAAAACGACGGCCAGTTCTCAACCAACCACAARGAYATYGG-3 (forward primer - VF1d_t1)5-TGTAAAACGACGGCCAGTTCTCAACCAACCAIAAIGAIATIGG-3 (forward primer - VF1i_t1)5-CAGGAAACAGCTATGACTAAACTTCTGGATGTCCAAAAAATCA-3 (reverse primer - LepR1_t1)5-CAGGAAACAGCTATGACTAGACTTCTGGGTGGCCRAARAAYCA-3 (reverse primer - VR1d_t1)5-CAGGAAACAGCTATGACTAGACTTCTGGGTGGCCAAAGAATCA-3 (reverse primer - VR1_t1)5-CAGGAAACAGCTATGACTAGACTTCTGGGTGICCIAAIAAICA-3 (reverse primer - VR1i_t1)These primers should be able to accommodate degeneracy occurring in the conserved regions as a result of evolutionary processes such as the ‘genetic drift’.

Results:BLAST results:FASTA format for the top 2 matchesSequence JF287131.1:>gi|325653673|gb|JF287131.1| Ephemerella subvaria voucher 08-SWRC-0922 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrialACTTTATACTTTATTTTCGGGGCTTGATCCGGCATAATTGGCACCTCTTTAAGTCTACTCATTCGGGCCGAACTGGGGCAACCTGGGTCCCTGATTGGAGATGACCAAATTTACAATGTCATCGTTACCGCCCATGCCTTCATTATAATTTTCTTTATAGTAATGCCTATTATAATTGGAGGATTTGGGAATTGGTTAGTGCCCCTCATACTCGGAGCTCCCGATATAGCTTTCCCCCGCATAAATAATATAAGCTTTTGACTTTTGCCTCCTGCCTTAACACTCCTATTAGCCAGTAGCATGGTAGAAAGAGGGGCGGGTACTGGTTGAACAGTTTACCCACCCCTGGCTTCCGGTATTGCTCATGCTGGAGGCTCTGTAGATCTCGCCATTTTCTCTCTTCACTTGGCTGGAGTCTCCTCTATTCTAGGAGCTGTGAACTTTATTACAACAACTATTAATATGCGGGCAAGAGGTATATCTATAGACCGGATTCCCCTTTTCGTATGATCTGTCCTAATTACAGCTATCTTACTTTTACTTTCTCTCCCAGTTTTAGCAGGAGCCATCACGATACTCCTCACTGACCGGAACCTTAATACATCCTTCTTTGACCCTGCTGGGGGAGGAGACCCCATTCTTTACCAGCATTTATTTSequence two JF287129.

1;>gi|325653669|gb|JF287129.1| Ephemerella subvaria voucher 08-SWRC-0728 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrialACTCTATACTTTATTTTCGGGGCTTGATCCGGCATAATTGGCACCTCTTTAAGTCTACTCATTCGGGCCGAACTAGGGCAACCTGGGTCCCTGATTGGAGATGACCAAATTTACAATGTCATCGTTACCGCCCATGCCTTCATTATAATTTTCTTTATAGTAATGCCTATTATAATTGGAGGATTTGGGAATTGATTAGTGCCCCTCATACTCGGAGCTCCCGATATAGCTTTCCCCCGCATAAATAATATAAGCTTTTGACTTTTGCCTCCTGCCTTAACACTCCTATTAGCCAGTAGCATGGTAGAAAGAGGGGCGGGTACTGGTTGAACAGTTTACCCACCCCTGGCTTCCGGTATTGCTCATGCTGGAGGCTCTGTAGATCTCGCCATTTTCTCTCTTCACTTGGCTGGAGTCTCCTCTATTCTAGGGGCTGTAAACTTTATTACAACAACTATTAATATGCGGGCAAGAGGTATATCTATAGACCGGATTCCCCTTTTCGTATGATCTGTCCTAATTACAGCTATCTTACTTTTACTTTCTCTCCCAGTTTTAGCAGGAGCCATCACGATACTCCTCACTGACCGGAACCTTAATACATCCTTCTTTGACCCTGCTGGGGGAGGAGACCCCATTCTTTACCAGCATTTATTTThe top two matches in the BLAST databaseAccession number sequences name E value query coverage1. JF287129.1 Ephemerella subvaria 0.

0 100% voucher 08-SWRC-0728 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial2. JF287129.1 Ephemerella subvaria voucher 08-SWRC-0728 0.0 100% cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrialThe top two mathces in the BOLD databaseTable 1: the first two results of the species level match made by sample #3 in the BOLD databasePhylum classorderFamilyGenusSpeciesSpecimen similarity (%)ArthropodaInsectaephemeropteraEphemerellidaeEphemerellaSubvaria100ArthropodaInsectaephemeropteraEphemerellidaeEphemerellaSubvaria100Discussion:Insects are diverse in nature and present an interesting opportunity for a host of target groups such as taxonomist, conservationists and ecologists.

The coming into place of the DNA technology and its bulging potential has revolutionarized the classification of organisms from the morphological perspective to a more advanced DNA taxonomy which requires DNA barcoding. It provides a novel sytem structured to provide a rapid and accurate species identification by use of short, standardized gene regions as species tag. Mayfly are a common feature in undisturbed freshwater bodies and are utilized by biomonitoring teams in establishing the water quality (Bauernfeind and Moog, 2000).

A match in the taxonomic ID and BOLD ID as evidenced by the BOLD and BLAST results. In some cases matches may fail to occur particularly when the sample is contaminated with DNA from other sources. These contaminants ultimately distort the outcome of the BLAST resulting yielding misleading results. False positives may also occur in queries done in the BOLD database where closely allied congeneric species which have not yet been established in the identification tree may appear in the results thereby resulting to a misleading clasification of the organism of interest.

ReferencesBauernfeind, E. and Moog, O. (2000). Mayflies (Insecta: Ephemeroptera) and the assessment of ecological integrity : a methodological approach. Hydrobiologia 422:71-83Hebert, P. D. N., A. Cywinska, S. L. Ball, and J. R. Dewaard. (2003a). Biological identificationsthrough DNA bar codes. Proceedings of the Royal Society of London B Biological Sciences 270: 313–321.Hebert P.D.N., Stoeckle M.Y, Zemlak T.S., Francis C.M. (2004b). Identification of Birds through DNA Barcodes. PLoS Biol 2: e312.