Abstract
We describe the karyotype, location of nucleolus-organizing regions (NORs) and heterochromatin composition and distribution in Lepidochitona caprearum (Scacchi, 1836). The examined specimens had 2n=24 chromosomes; the elements of pairs 1–4 were metacentric, subtelocentric those of the fifth pair, telocentric the elements of other pairs. NOR-FISH, Ag-NOR- and CMA3 banding showed NORs localized on pericentromeric regions of a medium small sized, telocentric chromosome pair. After C-banding or digestions with restriction enzyme NOR associate heterochromatin only was cytologically evident, resulting CMA3 positive. The comparison with chromosome data of other chitons, other than to evidence a karyotypic similarity of Lepidochitona caprearum to species of suborder Acanthochitonina, allows us to infer that chromosome evolution in the suborder mainly occurred via reduction of the number of the chromosomes by centric fusions, which took place repeatedly and independently in the different lineages of Acanthochitonina.
Highlights
Polyplacophora, known as chitons, includes about 900 living species, exclusively marine, distributed worldwide, mostly from the intertidal to the sub-littoral zone (Slieker 2000)
One nucleolus-organizing regions (NORs) bearing pair resulted evidenced after staining with Ag-NOR staining of Nucleolus Organizer Regions (Ag-NORs), chromomycin A3 (CMA3) banding and NOR-FISH; loci NORs were on pericentromeric regions of two medium sized telocentric chromosomes, tentatively the pair eight or nine (Fig. 2 A, B and C)
According to the classification by Kaas and Van Belle (1998) species of genus Lepidochitona belong to the family Ischnochitonidae Dall, 1989, suborder Chitonina
Summary
Polyplacophora, known as chitons, includes about 900 living species, exclusively marine, distributed worldwide, mostly from the intertidal to the sub-littoral zone (Slieker 2000). In order to increase karyological data on this class of mollusks we performed a chromosomal analysis using both conventional and banding staining methods and in situ hybridization (NOR-FISH) on Lepidochitona caprearum (Scacchi, 1836). For this chiton karyological data concern the chromosome number of 2n=24 and some details on morphology of eight large elements (meta- or sub-metacentric) (Vitturi et al 1982). On the basis of the classification priority criterion, nomenclatural validity of the Scacchian taxon was demonstrated by Piani (1983) and a few years later by Gaglini (1985)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
