The present work showed that teeth

The present work showed that teeth samples of
dolphins preserved in collections were a good
source of mitochondrial DNA for population
genetics and taxonomic studies. The positive
results in obtaining DNA showed that the pretreatment
of samples chosen for decontamination
from exogenous sources was efficient and did not
damage totally the DNA, leaving enough DNA for
the amplification of the region of interest.
Rosenbaum et al. (1997) did not succeed in
obtaining DNA from Baleen plates after soaking
them overnight in absolute ethanol, as was done in
the present work. They were able to obtain DNA
only when submitted them to a surface cleaning
with this component. In the case of teeth the DNA
is localised internally surrounding the pulp cavity,
therefore, it may be less exposed to the ethanol.
The demineralization process was necessary
because it was expected that mineral compounds
were likely to inibit the PCR, which were also
responsible for the higher preservation of DNA at
this regions. Kiesslich et al. (2002) described an
efficient and quick method of DNA purification by
the use of dialysis using nitrocellulose membranes.
The silica-GUSCN protocol for DNA extraction
was efficient for the present purpose of extracting
DNA from grained teeth, showing that it was a
good protocol for difficult templates as was stated
previously by Hoelzel (1998). More recently, other
authors have used other extraction protocols for
preserved part of specimens from collections, such
as Proteinase-k for lisis, Phenol/Chloroform for
purification, and absolute ethanol for precipitation
(Rosenbaum et al., 1997; Sweet and Hildebrand,
1998) and alternatively using nitrocelulosemediated
dialysis for purification (Kiesslich et al.,
2002). The sílica-GUSCN protocole has the
advantage of providing highly pure DNA,
eliminating known and unknown PCR inibitors
(Höss and Pääbo, 1993; Yang, 1997).
The primers used for amplifying the 16S rRNA
mitochondrial gene described by Palumbi et al.
(1991) were not useful for obtaining part of this
gene in T. truncatus. Therefore, it seemed that they
were not useful for vertebrates. These primers
have proven to be very useful in a variety of
invertebrates (Palumbi et al., 1991; Rawson and
Hilbish, 1995; pers. obs.). In the case of the BDR
region of the Cytochrome-b gene, the primers
tested, described by Unseld et al. (1995) for a very
conservative region of vertebrate species, were useful for amplifying this gene in T. truncatus.
The fragment obtained for this species was close
to 123 bp, the size observed for tunnids (Fig.1)