Abstract
According to the synthesis of 30 years of multidisciplinary studies, parthenogenetic species of rock lizards of genus Darevskia were formed as a result of different combination patterns of interspecific hybridization of the four bisexual parental species: Darevskia raddei, D. mixta, D. valentini, and D. portschinskii. In particular, D. portschinskii and D. raddei are considered as the parental species for the parthenogenetic species D. rostombekowi. Here for the first time, we present the result of comparative immunocytochemical study of primary spermatocyte nuclei spreads from the leptotene to diplotene stages of meiotic prophase I in two species: D. portschinskii and D. raddei. We observed similar chromosome lengths for both synaptonemal complex (SC) karyotypes as well as a similar number of crossing over sites. However, unexpected differences in the number and distribution of anti-centromere antibody (ACA) foci were detected in the SC structure of bivalents of the two species. In all examined D. portschinskii spermatocyte nuclei, one immunostained centromere focus was detected per SC bivalent. In contrast, in almost every studied D. raddei nuclei we identified three to nine SCs with additional immunostained ACA foci per SC bivalent. Thus, the obtained results allow us to identify species-specific karyotype features, previously not been detected using conventional mitotic chromosome analysis. Presumably the additional centromere foci are result of epigenetic chromatin modifications. We assume that this characteristic of the D. raddei karyotype could represent useful marker for the future studies of parthenogenetic species hybrid karyotypes related to D. raddei.
Highlights
According to the results of long term fundamental international studies initiated by Darevsky (1958, 1966, 1967, 1992) convincing evidence has been obtained that sevenHow to cite this article Spangenberg V, Arakelyan M, Galoyan E, Pankin M, Petrosyan R, Stepanyan I, Grishaeva T, Danielyan F, Kolomiets O. 2019
We performed a detailed analysis of the meiotic prophase I stages of two species: D. portschinskii and D. raddei which are parental for the parthenogenetic species D. rostombekowi
Stages of meiotic prophase I in D. portschinskii and D. raddei: leptotene and zygotene In both species D. portschinskii and D. raddei, leptotene begins with the formation of axial structures, which resemble dotted lines (Figs. 1A and 1B) until the early zygotene (Figs. 1C and 1D)
Summary
According to the results of long term fundamental international studies initiated by Darevsky (1958, 1966, 1967, 1992) convincing evidence has been obtained that sevenHow to cite this article Spangenberg V, Arakelyan M, Galoyan E, Pankin M, Petrosyan R, Stepanyan I, Grishaeva T, Danielyan F, Kolomiets O. 2019. We performed a detailed analysis of the meiotic prophase I stages of two species: D. portschinskii and D. raddei which are parental for the parthenogenetic species D. rostombekowi. We represent detailed comparative cytogenetic study of synaptonemal complexes karyotypes (SC karyotypes) using spread preparation and immuno-fluorescent in situ hybridization (FISH) technique. This approach provides visualization of meiotic SC bivalents which are three to five times longer than mitotic metaphase chromosomes and makes it possible to discover chromosomal rearrangements that are undetectable at diakinesis and metaphase I (Kalikinskaya et al, 1986). Additional information can be obtained: precise localization of centromeres, distribution of crossing over sites, and telomere DNA-repeats in the structure of meiotic chromosomes
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