NUCLEAR GENOME CHARACTERIZATION OF THE CARRAGEENOPHYTE HYPNEA-MUSCIFORMIS (RHODOPHYTA)

DNA reassociation kinetics were used to determine nuclear genome organ ization and complexity in the carrageenophyte Hypnea musciformis (Giga rtinales, Rhodophyta). Results indicate the presence of three second o rder components corresponding to fast (2%), intermediate (33%) and slo w (65%) fractions. Microspectrophotometry with the DNA-localizing fluo rochrome DAPI confirmed ploidy level differences in the gametophytic a nd tetrasporophytic phases. Elevated (endopolyploid) nuclear DNA level s were observed in both gametophytic and cystocarpic tissue. Compariso n of mean nuclear DNA (I(f)) values to chicken erthrocytes (RBC) resul ted in an estimate of 0.22 pg/2 C genome for Hypnea musciformis. Karyo logical studies using aceto-orcein revealed a chromosome complement of five bivalents during diakinesis of tetraspore mother cells.