BARRIGA-SOSA, Irene D. L. A.; Universidad Autonoma Metropolitana-Iztapalapa: Genetic variability of the white fish Chirostoma (Pisces: Atherinopsidae) as revealed by mtDNA genes.

The white fish species “Chirostoma estor, C. humboldtianum, C. lucius, C. promelas” and “C. sphyraena” are of great economical, ichtyological and ecological relevance to the local populations of Patzcuaro and Chapala lakes, M�xico. Several aquaculture programs had recently started in these regions in order to provide high quality food, however the genetic identities or morphological characters used to discriminate among these species and for practical purposes are uncertain. The species are part of the Jordani group (Barbour 1973 a) and are characterized by their high genetic identities and morphology (Barbour 1973 a y b; Barbour y Chernoff 1984; Echelle y Echelle 1984; Barriga-Sosa et al., 2002; Barriga-Sosa 2001). Here we present the preliminary results of 490 bp and 600 bp of the mtDNA cytocrome B and 16S DNA genes, respectively. The mean aligned identity of the compiled sequences and in relation to other teleost fish were 79.8 and 88.6% for cytochrome B and 16S DNA, respectively. The number of variable sites among the species analyzed and for the cyt B was 1.7% (in 423 bp), whereas for the 16S DNA gene it was 3.3%, as well as 23 insertions. An RFLP analysis of the 16S DNA amplified and sequenced fragment and with the enzymes Ava II, Hae III, NdeI, Taq I and Mnl I showed that these species can be practically discriminated for aquaculture practices.