ANALISIS DE LA VARIABILIDAD ALOZIMATICA DE LA LEUCIN-AMINOPEPTIDASA (LAP), DE LA FOSFOGLUCOMUTASA (PGM) Y DE LA FOSFOGLUCOSA-ISOMERASA (PGI) DE ARTEMIA FRANCISCANA BAJO DIFERENTES CONDICIONES DE CULTIVO
(ANALYSIS OF ALLOZYMATICAL VARIABILITY OF LEUCIN-AMINOPEPTIDASE (LAP), PHOSPHOGLUCOMUTASE (PGM) AND PHOSPHOGLUCOSE-ISOMERASE (PGI) OF ARTEMIA FRANCISCANA AT DIFFERENT CULTURE CONDITIONS - in Spanish)
MSc Thesis by D.E. Rodriguez Cortes, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Division de Oceanologia, Departamento de Acuicultura, Ensenada, BC, Mexico, 1998, 61 pp.
Summary:
In the present study, it is analysed and discussed whether different culture conditions can induce genetic differences in Artemia franciscana from Great Salt lake (Utah, USA), and whether these variations are related to phenotypic characteristics of aquacultural importance such as final sizes and biochemical composition, within a same cohort. The starch gel electrophoresis was used to analyse the allelic variation of four polymorphic loci: leucin-aminopeptidase-2 (Lap-2); leucin-aminopeptidase-3 (Lap-3); phosphoglucomutase (Pgm) and phosphoglucose-isomerase (Pgi) in A. franciscana cultured in eight different experimental conditions. The analysed organisms were cultured to adult stage under an experimental design of 2 X 2 X 2 (22 and 30 C; salinity 30 and 60 ppt and live Dunalliela sp. and dry commercial Spirulina sp. as nutriment). Under the hypothesis that there is no short term significant allelic variation in one same population maintained in different experimental conditions, it was found that the average values of observed heterozygosity (Ho) vary from 0.135 to 0.388. The allelic frequencies of Lap-2A vary from 0.757 to 0.948; of Lap-3A from 0.868 to 0.862; of Pgi-1 from 0.391 to 1.000 and Pgi-1A from 0.5 to 0.729. The results obtained show an important allelic variation as a function of culture conditions. When applying Fisher's exact test, using contingency tables, the existence of significant differences (alpha = 0.05) were found in the allelic frequencies in each locus. Therefore, the hypothesis of independence among treatments and allelic composition by locus, is rejected. However, Tukey's test of no aditivity and interactive of the multifactorial analysis, which was used to analyse if there is a synergetic effect of the factors and the allelic composition by locus, proved that there are no significant differences by any of the factors nor by the interaction among them and, therefore, proved to be determinant in the observed allelic variation. The allelic variation present in the Lap locus seems to indicate, as has been reported by other authors, that it has a specific junction in the osmoregulation at different salinities and temperatures, as well as Pgm and Pgi, which take part in the transformation of glocuse. The biochemical composition of the culture organisms as well as the provided diets was analysed by standard analytic methods, determining the protein, lipid and carbohydrate contents. The results prove a great variability in the biochemical composition of A. franciscana, not only due to the quality of the furnished diet, but also due to an effect produced by temperature and salinity. In the majority of the cases, it was observed that the grater total length/thorax and total length/abdomen, correspond to the organisms cultured under low salinity conditions. When integrating the different aspects of this study, it is seen that the average degrees heterozygosity observed of the four loci did not show an apparent relationship with total length, growth velocities, or with the biochemical profile. However, a positive relationship of the values of heterozygosity with temperature was found. This study proves that there is variability in specific locus, in one same population, under different environments, which emphasizes the necessity of having precautions when analysing the genetic information of natural populations through time. In the aquacultural aspect, the results of this study are of great use because it is possible to obtain different nutritional and morphological profiles in A. franciscana, which can be used to the greatest advantage in diets for fish and shrimp culture, according to their necessities.