Abstract
Oikopleura dioica is a ubiquitous marine zooplankton of biological interest owing to features that include dioecious reproduction, a short life cycle, conserved chordate body plan, and a compact genome. It is an important tunicate model for evolutionary and developmental research, as well as investigations into marine ecosystems. The genome of north Atlantic O. dioica comprises three chromosomes. However, comparisons with the genomes of O. dioica sampled from mainland and southern Japan revealed extensive sequence differences. Moreover, historical studies have reported widely varying chromosome counts. We recently initiated a project to study the genomes of O. dioicaindividuals collected from the coastline of the Ryukyu (Okinawa) Islands in southern Japan. Given the potentially large extent of genomic diversity, we employed karyological techniques to count individual animals' chromosomes in situ using centromere-specific antibodies directed against H3S28P, a prophase-metaphase cell cycle-specific marker of histone H3. Epifluorescence and confocal images were obtained of embryos and oocytes stained with two commercial anti-H3S28P antibodies (Abcam ab10543 and Thermo Fisher 07-145). The data lead us to conclude that diploid cells from Okinawan O. dioicacontain three pairs of chromosomes, in line with the north Atlantic populations. The finding facilitates the telomere-to-telomere assembly of Okinawan O. dioica genome sequences and gives insight into the genomic diversity of O. dioica from different geographical locations. The data deposited in the EBI BioImage Archive provide representative images of the antibodies' staining properties for use in epifluorescent and confocal based fluorescent microscopy.
Highlights
The larvacean, Oikopleura dioica, possesses a fascinating genome: it has reduced to a mere 70Mbp and exhibits unique characteristics such as non-canonical splicing and the scattering of Hox genes (Denoeud et al, 2010; Edvardsen et al, 2005; Marz et al, 2008; Seo et al, 2001)
Metaphase-specific histone 3 (H3) markers have been used to determine the structure and the segregation of genetic material during oogenesis in situ (Ganot et al, 2006; Schulmeister et al, 2007). One such marker that has been successfully visualized in O. dioica is histone H3 phosphorylated at Ser-28 (Kawajiri et al, 2003; Kurihara et al, 2006), whose localization depends on the phase of the cell cycle: during metaphase, sister chromatids were stained in a manner consistent with alignment along the metaphase plate, whereas in non-mitotic cells, spatially punctate signals were found evenly spread within the nuclear envelope (Campsteijn et al, 2012; Feng & Thompson, 2018; Feng et al, 2019; Olsen et al, 2018)
We initially attempted to visualize chromosomes using Giemsa staining on developing embryos
Summary
The larvacean, Oikopleura dioica, possesses a fascinating genome: it has reduced to a mere 70Mbp and exhibits unique characteristics such as non-canonical splicing and the scattering of Hox genes (Denoeud et al, 2010; Edvardsen et al, 2005; Marz et al, 2008; Seo et al, 2001). Metaphase-specific histone 3 (H3) markers have been used to determine the structure and the segregation of genetic material during oogenesis in situ (Ganot et al, 2006; Schulmeister et al, 2007). One such marker that has been successfully visualized in O. dioica is histone H3 phosphorylated at Ser-28 (Kawajiri et al, 2003; Kurihara et al, 2006), whose localization depends on the phase of the cell cycle: during metaphase, sister chromatids were stained in a manner consistent with alignment along the metaphase plate, whereas in non-mitotic cells, spatially punctate signals were found evenly spread within the nuclear envelope (Campsteijn et al, 2012; Feng & Thompson, 2018; Feng et al, 2019; Olsen et al, 2018). We visualized anti-H3S28P stained embryos from two commercially available antibody
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
