CARATTERIZZAZIONE DI ARTEMIA TUNISIANA DELLE SALINE DI TRAPANI.
CHARACTERISATION OF ARTEMIA TUNISIANA OF THE TRAPANI SALTWORKS (in Italian)
MSc Thesis by F. Catania, Università degli studi di Palermo, Sicily, Italy
1999, 107 pp.
Conclusions:
The comparative genetic analysis of different commercial batches of Artemia franciscana and the endemic Artemia populations of Trapani (Sicily) saltworks, belonging to the species A. tunisiana (=salina), demonstrates that there is no contamination in local Artemia populations, due to accidental or deliberate inoculations of the mentioned batches of Artemia franciscana.
This result is based not only on statistically significant results obtained by using AMOVA (analysis of the molecular variance), but also on the evidence of bands of species-specific DNA. Such bands are identical within each of the two different groups of endemic Artemia populations and Artemia franciscana. Moreover, from the analysis of the amplified products, obtained from the primers which generated species-specific bands, the presence of DNA bands, that could indicate contamination, was never observed.
It was also possible, during this experiment, to highlight a significant difference in terms of genetic distance (Fst), within the same endemic populations, between the populations of Salina Lago and Salina Curto (Marsala) and the rest of the other endemic populations studied (Trapani).
Probably such divergence is linked in some way to the distance between the two saltworks and the group of the other ones (a mean value of 9 Km), and hence to some difficulty in the occurrence of genetic flow among them.
The genetic divergence among the Artemia populations through the dendrogram is remarkable. In the phylogenetic tree the presence of two distinct groups can be observed, corresponding to the two Artemia strains studied : Artemia salina and Artemia franciscana.
Moreover, within the group of endemic populations, the extreme position of S-LG and S-CR can be pointed out, which reflects the significant value of the genetic distance between these two populations and the rest of the endemic populations.
As for the qualitative and nutritional value, the analysis of lipid and fatty acid contents performed seems to indicate that the local samples present better nutritional characteristics than the Artemia franciscana samples.
Although the content in lipids is significantly higher in the Artemia franciscana batches, compared to the endemic populations, the amount of essential fatty acids n-3, both in cysts and nauplii of endemic Artemia populations, is more balanced.
The mean content of EPA in local cysts is 10.92 % against 4.43 % of commercial cysts, whereas in nauplii a value of 12 % is observed in endemic Artemia against 4.17 % in the commercial ones.
These data are also in agreement with the content of linolenic acid in both groups. The content of this fatty acid is inversely proportional to the EPA content. It confirms the enzymatic block, according to literature data (Sargent et al., 1993), at the level of desaturase-5 which is involved in the bioconversion of linolenic acid to HUFA n-3.
These results, and the hatching values of the endemic cysts, that are not significantly different from the values observed in the analysed batches of Artemia franciscana, seem once again to indicate that the overall quality of the Artemia from Trapani saltworks is good and that, consequently, it might also be feasible to take into account the possibility of using it as a valuable aquaculture food source.
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