Hi, I think it's a pretty easy answer: DNA barcoding is a method to identify a particular species. Cheers, Nadine

Dear Ansari

It is unfortunate that these day neither we have funds nor have time and sufficient skills to undertake detailed (microscopy based) taxonomy of intractable lower groups like nematodes. That is why we are moving towards carrying out DNA barcoding (amplification and matching of one or more short gene sequences taken from a standardized portion of the genome of an organism to identify species through reference to DNA sequence libraries or databases) of these problematic groups to identify them. There are several positive and negative aspects of DNA barcoding practices. I personally believe that one should always go for basic morphometry to identify an organism and the findings may be backed up with the results of DNA barcoding before confirming about the taxonomy of that organism.

YOu may look into:

1. http://nopr.niscair.res.in/bitstream/123456789/13074/1/IJMS%2040(5)%20645-647.pdf

2. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013716

3. http://www.zjubiolab.zju.edu.cn/wumin/userfiles/lab-paper/000384-20110911193046.pdf

Best

Dola

Well, I think barcoding makes only sense, once the species has been first identified. Besides, the genetic variability within a species is sometimes greater than the variabilty among close species, thus barcoding in such cases is not a useful tool to identify the species to which an individual belong. Barcoding is only an additional tool to resolve many biological questions of importance rather than an objective per se.

Well, i am agree with DNA barcoding is a method to identify a particular species. But in case of nematodes especially marine forms, there is no information of earlier databases except some species. In my question is how to identify when we don't have any sequences regarding the similar species or higher similarity?

Hi, somebody has to start with identifying species.... Maybe you can do this if you work with them?!

well there are methods to isolate regions with no sequencing done around but these are quite messy. Check those articles. might be useful.

Bhadury P, Austen MC (2010) Barcoding

marine nematodes: an improved set of nematode

18S rRNA primers to overcome eukaryotic

co-interference. Hydrobiologia 641:

245–251

Derycke S, Vanaverbeke J, Rigaux A et al

(2010) Exploring the use of cytochrome oxidase

c subunit 1 (COI) for DNA barcoding of

free-living marine nematodes. PLoS One

5:e13716

Bhadury P, Austen MC, Bilton DT et al (2007)

Exploitation of archived marine nematodes – a

hot lysis DNA extraction protocol for molecular

studies. Zoolog Scripta 36:93–98

Floyd R, Abebe E, Papert A, Blaxter M (2002)

Molecular barcodes for soil nematode identifi -

cation. Mol Ecol 11:839–850

I I think, At the beginning, you need to work with the classic morphological way togehter with bacording to produce a "DNA sequence list", due to there are few information about nematodes DNA sequences. And I later, it looks as good tools to reduce research time and maybe reduction of economical resources to any research. for example in the case of trophic studies, to identify feed ítems to any crustacean species, bacording should be better than try to identify the presence of "any "structutre of nematode inside the gut, which in fact, is nearly imposible.