Nucleotide variation and molecular structure of the heterochromatic repetitive AluI DNA in the brine shrimp Artemia franciscana

Abstract

It has been suggested that DNA bending could play a role in the regulation of gene expression, chromosome segregation, specific recombination and/or DNA packaging. We have previously demonstrated that an AluI DNA family of repeats is the major component of constitutive heterochromatin in the brine shrimp A. franciscana. By the analysis of cloned oligomeric (monomer to hexamer) heterochromatic fragments we verified that the repetitive AluI DNA shows a stable curvature that determines a solenoidal geometry to the double helix. This particular structure could be of relevant importance in conferring the characteristic heterochromatic condensation. In this paper we evaluate how the point mutations that occurred during the evolution of the AluI sequence of A. franciscana could influence the sequence-dependent tridimensional conformation. The obtained data underline that, in spite of the high sequence mutation frequency (10%) of the repetitive DNA, the general structure of the heterochromatic DNA is not greatly influenced, but rather there is a substantial variation of the copy number of the repetitive AluI fragment. This variation could be responsible for the hypothetical function of the constitutive heterochromatin.

Phylogenetic study of bisexual Artemia using random amplified polymorphic DNA

“…This variability, together with the data obtained regarding the distribution of the AluI-113bp satellite DNA (Landsberger et al 1992), could indicate that this species is actually expanding, from an evolutionary point of view, more actively.…”

“…In recent years attempts were made (Badaracco et al 1987;Landsberger et al 1992) to correlate some populations living in different regions of the world by means of a molecular approach utilizing a repetitive AluI heterochromatic sequence as probe (Barigozzi et al 1984;Cruces et al 1986). The results showed a great variation (more than 100-fold) in the copy number of the AluI fragment of the American strains, revealing the existence of a gradient of heterochromatin amount increasing from the south to the north of the continent.…”

Updating Geographic Distribution of Artemia urmiana Günther, 1890 (Branchiopoda: Anostraca) in Europe: An Integrated and Interdisciplinary Approach

“…BARIGOZZI et al (1984), BADARACCO et al (1987;1991) and LANDSBERGER et al (1992) used the AluI-type of repetitive DNA. PEREZ et al (1994) first analyzed the mtDNA and concluded that A. salina, A. franciscana and two parthenogenetic strains should be considered as belonging to different species.…”

Significance of cyst fragments ofArtemia sp. recovered from a 27,000 year old core taken under the Great Salt Lake, Utah, USA

“…Importantly, the DNA of contemporary cysts is the continuing object of study (Kim et al, 1992;Landsberger et al, 1992;Escalente et al, 1994;Franco et al, 1994;Jellie et al, 1996;Ortega et al, 1996) and the complete sequence of their mitochondrial DNA has recently been published (Valverde et al, 1994), providing a basis for future comparison with sequences obtained from ancient cysts. If sufficiently old cysts can be obtained in the future this system may also provide a way to evaluate the rate of nucleotide substitutions in selected genes over "real time".…”