Heteromorphic sex chromosomes in the ninespine stickleback Pungitius pungitius

Abstract

Specimens from two freshwater populations of the ninespine stickleback Pungitius pungitius in Poland showed morphologically differentiated sex chromosomes. A heteromorphic pair of chromosomes appeared only in male diploid cells. The Y chromosome was the largest chromosome in the P. pungitius karyotype.

Karyotype Differentiation between Two Stickleback Species (Gasterosteidae)

“…The closest extant relative of G. aculeatus also has a diploid chromosome number of 42, as does a more distant relative, the ninespine stickleback, P. pungitius [Ocalewicz et al, 2008[Ocalewicz et al, , 2011Ross et al, 2009;. However, many differences in chromosome morphology exist between the Gasterosteus species and P. pungitius [Ocalewicz et al, 2008[Ocalewicz et al, , 2011Ross et al, 2009]. A recent report shows that P. pungitius has a higher NF:2n than G. aculeatus [Ocalewicz et al, 2011], indicating a higher number of metacentric and submetacentric chromosome pairs in P. pungitius .…”

“…Stickleback species also have different sex chromosome systems. Both threespine sticklebacks (Gasterosteus aculeatus) and ninespine sticklebacks (Pungitius pungitius) have XX/XY (male heteromorphic) sex chromosome systems, but comparative fluorescence in situ hybridization (FISH) mapping and genetic linkage analyses indicate that these sex chromosome systems arose independently [Peichel et al, 2004;Ocalewicz et al, 2008;Ross and Peichel, 2008;Ross et al, 2009;Shapiro et al, 2009]. A third species, the fourspine stickleback (Apeltes quadracus) , has a ZZ/ZW (female heteromorphic) sex chromosome system [Chen and Reisman, 1970;Ross et al, 2009].…”

Chromosomal location of Ag/CMA3-NORs, 5S rDNA and telomeric repeats in two stickleback species

“…The female karyotype comprised 16 metacentrics, 12 submetacentrics and 14 acrocentrics, whereas males showed 15 metacentrics, 13 submetacentrics and 14 acrocentrics. Two heteromorphic sex chromosomes were identified in the male individuals: the large submetacentric Y chromosome and the metacentric X chromosome (according to Ocalewicz et al 2008, andRoss et al 2009). …”

“…Intraspecies variation in the karyotype morphology in both stickleback species was due to the existence of heteromorphic sex chromosomes (Ocalewicz et al 2008;Ross & Peichel 2008;Ross et al 2009) and chromosome-length polymorphism. Variability in length of the short arms of two small bi-armed chromosomes related to the size variation of the NOR regions affected the number of metacentric and submetacentric chromosomes in the threespine sticklebacks studied in the present paper.…”

“…Although sticklebacks show such an enormous biological importance, the chromosomes of these fish have been comparatively little studied. The available data are mostly the basic information about the chromosome and chromosome arm numbers provided by Giemsa staining in the exponents of the Apeltes, Culaea, Pungitius and Gasterosteus genera (Table I) and the distribution of AT-and GC-rich heterochromatin obtained in the course of DAPI (4 ,6-diamidino-2-phenylindole) and CMA 3 (chromomycin A 3 ) staining in the ninespine stickleback (Ocalewicz et al 2008). Chromosomal distribution of either Nucleolar Organizing Regions (NORs) or 5S rDNA clusters, which are listed as the main markers in the fish chromosome studies, are not yet available in the case of the sticklebacks.…”