CHARACTERIZATION OF DIFFERENT CHROMATIN TYPES IN MYTILUS-GALLOPROVINCIALIS L AFTER C-BANDING, FLUOROCHROME AND RESTRICTION-ENDONUCLEASE TREATMENTS

In this study, we have carried out the cytogenetical characterization of Mytilus galloprovincialis L. (2n = 28)using conventional staining a nd banding techniques such as fluorochromes and restriction endonuclea ses treatment. Chromosome digestion with trypsin enzyme resulted in a G-banding pattern which allowed us to clearly identify and classify th e chromosome pairs of M. galloprovincialis. C-banding and chromomycin A(3) staining confirmed the existence of small amounts of constitutive heterochromatin. The treatment of samples with AluI, HaeIII, DpnI, Ms pI, HpaII and HinfI restriction endonucleases produced specific bandin g patterns which demonstrate the potential of endonucleases for chromo some banding in mussels. The results obtained allow us to describe six different types of chromatin in M. galloprovinicialis. The type is de termined by the response of the chromosomes to the different treatment s. Differential digestion by the enzyme pair HpaII-MspI of specific C- band positive heterochromatic areas in some of the chromosomes suggest s the presence of methylation.