TY  - JOUR
A1  - Nanda, Indrajit
A1  - Schories, Susanne
A1  - Simeonov, Ivan
A1  - Adolfi, Mateus Contar
A1  - Du, Kang
A1  - Steinlein, Claus
A1  - Alsheimer, Manfred
A1  - Haaf, Thomas
A1  - Schartl, Manfred
T1  - Evolution of the degenerated Y-chromosome of the swamp guppy, Micropoecilia picta
JF  - Cells
N2  - The conspicuous colour sexual dimorphism of guppies has made them paradigmatic study objects for sex-linked traits and sex chromosome evolution. Both the X- and Y-chromosomes of the common guppy (Poecilia reticulata) are genetically active and homomorphic, with a large homologous part and a small sex specific region. This feature is considered to emulate the initial stage of sex chromosome evolution. A similar situation has been documented in the related Endler’s and Oropuche guppies (P. wingei, P. obscura) indicating a common origin of the Y in this group. A recent molecular study in the swamp guppy (Micropoecilia. picta) reported a low SNP density on the Y, indicating Y-chromosome deterioration. We performed a series of cytological studies on M. picta to show that the Y-chromosome is quite small compared to the X and has accumulated a high content of heterochromatin. Furthermore, the Y-chromosome stands out in displaying CpG clusters around the centromeric region. These cytological findings evidently illustrate that the Y-chromosome in M. picta is indeed highly degenerated. Immunostaining for SYCP3 and MLH1 in pachytene meiocytes revealed that a substantial part of the Y remains associated with the X. A specific MLH1 hotspot site was persistently marked at the distal end of the associated XY structure. These results unveil a landmark of a recombining pseudoautosomal region on the otherwise strongly degenerated Y chromosome of M. picta. Hormone treatments of females revealed that, unexpectedly, no sexually antagonistic color gene is Y-linked in M. picta. All these differences to the Poecilia group of guppies indicate that the trajectories associated with the evolution of sex chromosomes are not in parallel.
KW  - sex chromosomes
KW  - heterochromatin
KW  - Y chromosome degeneration
KW  - meiosis
KW  - synaptonemal complex
KW  - recombination
KW  - 5-methylcytosine
KW  - testosterone
KW  - sexual antagonistic genes
KW  - sex linked pigmentation pattern
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-267242
SN  - 2073-4409
VL  - 11
IS  - 7
ER  -