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Biomedical subjects

A J Simpson

Publications and source records attributed to A J Simpson.

242 records · Page 14Linked to original sources
PubMedDate not supplied

Further studies on the molecular systematics of Biomphalaria snails from Brazil.

The polymerase chain reaction and restriction fragment length polymorphism (RFLP) of the internal transcribed spacer (ITS) region of the rRNA gene, using the enzyme DdeI were used for the molecular identification of ten species and one subspecies of Brazilian Biomphalaria. Emphasis is given to the analysis of B. oligoza, B. schrammi and B. amazonica. The RFLP profiles obtained using this enzyme were highly distinctive for the majority of the species and exhibited low levels of intraspecific polymorphism among specimens from different regions of Brazil. However, B. peregrina and B. oligoza presented very similar profiles that complicated their identification at the molecular level and suggested a very close genetic similarity between the two species. Others enzymes including HaeIII, HpaII, AluI and MnlI were tested for their ability to differentiate these species. For B. amazonica three variant profiles produced with DdeI were observed. The study demonstrated that the ITS contains useful genetic markers for the identification of these snails

Animals↗
PubMedDate not supplied

Identification of planorbids from Venezuela by polymerase chain reaction amplification and restriction fragment length polymorphism of internal transcriber spacer of the RNA ribosomal gene.

Snails of the genus Biomphalaria from Venezuela were subjected to morphological assessment as well as polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. Morphological identification was carried out by comparison of characters of the shell and the male and female reproductive apparatus. The PCR-RFLP involved amplification of the internal spacer region ITS1 and ITS2 of the RNA ribosomal gene and subsequent digestion of this fragment by the restriction enzymes DdeI, MnlI, HaeIII and MspI. The planorbids were compared with snails of the same species and others reported from Venezuela and present in Brazil, Cuba and Mexico. All the enzymes showed a specific profile for each species, that of DdeI being the clearest. The snails were identified as B. glabrata, B. prona and B. kuhniana.

Animals↗
PubMedDate not supplied

Random amplified polymorphic DNA (RAPD) analysis of Paracoccidioides brasiliensis isolates.

Five Paracoccidioides brasiliensis isolates of humans origin were analyzed using three arbitrary primers (3301, 3304 and 3307 of 10, 9 and 10 oligonucleotídes respectively) in random amplified polymorphic DNA (RAPD) analysis. The analysis of the complex RAPD profiles obtained were carried out using the Dice similarity coefficient that distinguished the isolated Pb 02 from the others (Pb 18, Pb 192, Pb 265 and Pb SN). The results revealed limited intraspecific genomic variations in these P. brasiliensis isolates and indicate that RAPD can be useful for analysis of P. brasiliensis genome for characterization or differentiation within this genus.

DNA, Fungal↗