Ontogeny of globin expression in zebrafish (Danio rerio)

Abstract

Respiratory proteins are responsible for transport and storage of oxygen. It is well established that specific requirements for oxygen during vertebrate ontogeny cause switches of hemoglobin chain expression. Here, we characterize the developmental profiles of zebrafish (Danio rerio) globins by means of quantitative real-time reverse transcription PCR. The total mRNA levels of the hemoglobin chains, including a newly identified embryonic α-chain, as well as myoglobin, neuroglobin, cytoglobin 1 and 2, and globin X were estimated. mRNAs of all globins were detectable in unfertilized eggs, suggesting maternal storage. Embryonic α- and β-hemoglobin mRNA peaked at hatching and the switch to adult hemoglobin expression occurred 16 dpf. Enhanced myoglobin mRNA levels were detected ~31 h post-fertilization (hpf), coinciding with the heart and the muscle development, while neuroglobin mRNA expression pattern correlates with the formation of the nervous system. Amounts of myoglobin and neuroglobin mRNA were similar within an order of magnitude throughout the ontogeny, tentatively supporting a respiratory role of neuroglobin. Cytoglobin 2 mRNA levels increased gradually, whereas cytoglobin 1 mRNA levels increased strongly after ~31 hpf, which is in agreement with a function in cell proliferation. Globin X mRNA level was highest in oocytes, but low in later stages. Together, these data suggest a specific role for each globin, which are also associated with certain events in fish development.

Globin X is a six-coordinate globin that reduces nitrite to nitric oxide in fish red blood cells

“…Thus we provide evidence that the ancestral globins in blood were efficient nitrite reductases. levels only in unfertilized eggs (19). Here we found the highest expression at 4 hpf, likely of maternal origin, and a gradual increase from 18 hpf to the adult stage (Fig.…”

Whole-Genome Duplication and the Functional Diversification of Teleost Fish Hemoglobins

“…Expression data for cod, medaka, and zebrafish were obtained from the literature. The cod sequences were classified following Wetten et al (2010), the medaka sequences were classified following Maruyama, Yasumasu and Iuchi (2004), and the zebrafish sequences were classified following Tiedke et al (2011). For globin genes in fugu, gar, green-spotted puffer, platyfish, salmon, and tilapia, we inferred the timing of expression by identifying matches with sequences in EST databases (supplementary table S4, Supplementary Material online).…”

“…During ontogeny, regulatory changes in blood-O 2 transport are mediated by the expression of multiple, functionally distinct hemoglobin (Hb) isoforms that are adapted to the particular O 2 -transport challenges encountered by the developing embryo or fetus (in viviparous or oviparous species) and in free-swimming larvae and adults (reviewed by Ingermann 1997; Jensen et al 1998). As in other vertebrates, the developmental regulation of Hb synthesis in fish involves differential expression of duplicated genes that encode the α- and β-chain subunits of distinct tetrameric α 2 β 2 Hb isoforms (Chan et al 1997; Brownlie et al 2003; Maruyama, Yasumasu, and Iuchi 2004; Maruyama, Yasumasu, Naruse, et al 2004; Tiedke et al 2011). …”

Function and evolution of vertebrate globins

“…Phylogenetic analyses show remarkable differences in the evolution of Hb‐chains that are expressed in the embryonic and larval stages, which reflect the specific O 2 requirements in this phase of life (Tiedke et al . , Hoffmann et al . , Opazo et al .…”