Nuclear Small Subunit 18S rRNA Research Articles

Molecular-genetic identification and taxonomic relationships of fungi belonging to fungi imperfecti

To identify phytopathogenic and entomopathogenic fungi, mostly belonging to the classes Ascomycetes and Deuteromycetes we used standard and changed primers to amplify mitochondrial small subunits of rRNA (NMS3, NMS4), nuclear small subunit18S rRNA (NS7, NS8) and the two of internal transcribed spacer regions (ITS1, ITS2), between the genes 18S and 28S rRNA. Using the standard primers NMS1 and NMS2, ITS1 and ITS2 did not lead to the amplification of DNA of the fungi in PCR. It was interesting to note that only when the region of the small subunit 18 S RNA (NS7 and NS8) was used could positive results be obtained amplifying the DNA of both entomopathogenic and phytopathogenic fungi. Using the modified primers provided means for the differentiation of 13 strains of entomopathogenic fungi and 6 strains of Ascomycetes from different geographic zones.

Phylogenetic information of freshwater copepod (Diaptomus sicilis) with special reference to 18S rRNA

<p>In the present investigation to isolate freshwater calanoid copepods (<em>Diaptomus sicilis</em>) was characterized and identify the organisms by 18S rRNA sequencing. Plankton samples containing <em>D. sicilis</em> were collected during January 2014 (Post-monsoon) from Madippakkam Lake (12°57'41"N80°11'27"E) Chennai, Tamil Nadu. Immediately after sampling, specimens for genetic analyses were fixed in 95% ethyl alcohol. The total DNA was extracted from the individual copepod <em>D. sicilis</em> using Qiagen Blood tissue kit. The nuclear small subunit 18S rRNA gene was amplified using the Universal primer LCO —1490 (5’-GGTCAACAAATCATAAAGATATTGG-3’) and HCO-2198 (5’-TAAACTTCAGGGTGACCAAAAAATCA-3’). PCR products were loaded onto a 1% TAE agarose gel. Sequences were carried out an automated sequencer. The nucleotide sequence of 1282 base pair region of 18S rRNA was determined for D. sicilis. The similarity of sequences of <em>D. sicilis</em> was retrieved by BLASTn pro­gram and maximum identity and E-value was 76% and 0.00, respectively. The PCR products of <em>D. sicilis</em> individuals showed 80% similarity with the partial nuclear small subunit 18S rRNA gene region of other calanoid copepods. Based on molecular data the freshwater Calanoid copepods showed different algorithms and similar types of topologies useful for designing molecular analyses using phylogeny tree construction.Present molecular stud­ies on the relationship of D. sicilis with other freshwater calanoid copepods indicate that this species is close to <em>D. castor</em> followed by <em>D. keniraensis</em><em>.</em></p>