Figure 6.

ca15b RNA is maternally expressed but not germ plasm-localized in Devario aequipinnatus embryos. A) ca15b RNA localization in zebrafish (Danio rerio) and Devario aequipinnatus four-cell embryos as visualized by fluorescence in situ hybridization and confocal microscopy. In zebrafish, ca15b is specifically localized to the germ plasm aggregates at the distal ends of cleavage furrows. In contrast, ca15b does not localize to germ plasm in Devario aequipinnatus cleavage furrows, and instead appears to be distributed throughout the blastodisc. This is in contrast to the generalized background fluorescence exhibited when using a sense RNA probe for ca15b (B). All micrographs are maximum projections of three-dimensional stacks, with lower insets showing increased magnification of furrow regions. C) A gene tree depicting the evolutionary relationship between the putative Devario aequipinnatus ca15b sequence and all known members of the carbonic anhydrase 4/15 family in the zebrafish genome. The tree was built using the Maximum Likelihood method and Tamura-Nei model (Tamura & Nei, 1993) with evolutionary analysis conducted in MEGA X (Kumar et al., 2018; Stecher et al., 2020) (also see Methods). D) Expression of ca15b during the 2-cell (45 mpf), 1000 cell (3 hpf), and dome (4.3 hpf) stages of Devario aequipinnatus as assayed by reverse-transcriptase PCR. Transcripts of ca15b are maternally expressed, with positive signal at the 2-cell and 1000 cell stages and decreased signal at the dome stage. Beta-actin was used as a control.