Number of chromosomes

Value 42 chromosomes
Organism Sea urchin Strongylocentrotus purpuratus
Reference Eno CC, Böttger SA, Walker CW. Methods for karyotyping and for localization of developmentally relevant genes on the chromosomes of the purple sea urchin, Strongylocentrotus purpuratus. Biol Bull. 2009 Dec217(3):306-12. abstractPubMed ID20040754
Method "[Researchers] obtained excellent chromosomal preparations from a manual coverslip-squash technique. Use of heated slides in a moist environment as described in previous literature (Gerhart et al. , 1979) did not reliably yield interpretable chromosomal preparations. Excellent chromosomal preparations consistently resulted from protocols involving colchicine treatment, use of Nytex mesh for dissociation of blastomeres, and manual squashing of blastomeres under coverslips (Fig. 1). The most important procedures for generating cells for chromosomal squashes are complete removal of the fertilization membrane and complete separation of blastomeres from one another."
Comments "Here [researchers] describe the first successful methods for karyotyping and localizing specific gene loci on chromosomes of Strongylocentrotus purpuratus and those of the phylogenetically related Strongylocentrotus droebachiensis. Both species have 42 chromosomes in their diploid genomes (n = 21). There are 2 large, 8 medium, and 10 small pairs, plus one putative sex pair."
Entered by Uri M
ID 111373