RESTRICTION ENZYMES INDUCED BANDS IN THE CAVE CRICKET DOLICHOPODA-SCHIAVAZZII (ORTHOPTERA, RHAPHIDOPHORIDAE) - IMPLICATIONS FOR HETEROCHROMATIN CHARACTERIZATION AND SATELLITE DNA DISTRIBUTION

In this study the activity of some class II restriction endonucleases, RE, on fixed metaphase chromosomes has been tested on two sample populations of the cave cricket Dolichopoda schiavazzii, a species endemic in Tuscany. In particular, the 6-base cutter PstI was chosen to detect the occurrence and localization on chromosomes of a satellite DNA family (named pDoP102) whose repetition units, analyzed in a previous study, contain the cleavage site of this enzyme. A comparison of the PstI digestion pattern and the C-banding one, suggests that this satDNA family is mainly localized in certain heterochromatic regions of chromosomes 1, 3, 8, 10 and in the Y chromosome. As a negative control in situ digestion was performed with RE AluI whose cleavage site is not contained in the pDoP102 satDNA sequence. The partial overlap between the PstI and AluI digested regions suggests the occurrence of at least another satDNA family detected by PstI and containing the AluI target. AluI restriction banding also showed variation between the two population samples, suggesting a role of these cytological markers in microevolutionary studies.