Species identification of some common necrophagous flies in Guangdong province,southern China based on the rDNA internal transcribed spacer 2 (ITS2)

Recent studies suggest that sequence analysis technique displays a tempting foreground in identifying unknown specimens of necrophagous flies. In this study, we analyzed 63 complete ITS2 sequences concerning 29 fly species to evaluate the identification potential of the ITS2 region, among of which 41 sequence entries were obtained by sequencing and 22 sequence entries were available on the line. Additionally, phenetic method was recommended to substitute for phylogenetic method because it is very difficult to align the ITS2 sequences. The neighbor-joining tree generated by clustalx1.81 allowed us to differentiate each species. Meanwhile the tree topology also suggested that the ITS2 region showed no resolution for the distinction of geographical populations of some species. The overlapping between intra- and interspecific variation revealed by sequence analyses did not affect species identification. High sequence homology between some congeneric species required further sequencing for forensic practice.     

Preliminary data on the usefulness of internal transcribed spacer I (ITS1) sequence in Cannabis sativa L. identification.

A method is described to identify an unknown sample of plant material of forensic interest as Cannabis sativa L. The method consists in comparing the sequence of the nuclear ribosomal DNA Internal Transcribed Spacer I (ITS1) of the unknown sample with a Cannabis sequence. Our preliminary results show that the ITS1 is an ideal molecule for the identification of a sample suspected to be marijuana.     

Identification of forensically important sarcophagid flies (Diptera: Sarcophagidae) in China, based on COI and 16S rDNA gene sequences

Insects attracted to cadavers may provide important indications of the postmortem interval (PMI). However, use of the flesh flies (Diptera: Sarcophagidae) for PMI estimation is limited as the species are often not morphologically distinct, especially as immatures. In this study, 23 forensically important flesh flies were collected from 13 locations in 10 Chinese provinces. Then, a 278-bp segment of the cytochrome oxidase subunits one (COI) gene and a 289-bp segment of the 16S rDNA gene of all specimens were successfully sequenced. Phylogenetic analysis of the sequenced segments showed that all sarcophagid specimens were properly assigned into four species (Boerttcherisca peregrina [Robineau-Desvoidy, 1830], Helicophagella melanura [Meigen, 1826], Parasarcophaga albiceps [Meigen, 1826], and Parasarcophaga dux [Thompson, 1869]) with relatively strong supporting values, thus indicating that the COI and 16S rDNA regions are suitable for identification of sarcophagid species. The difference between intraspecific threshold and interspecific divergence confirmed the potential of the two regions for sarcophagid species identification.