Embryonic and larval development of the northern pike: An emerging fish model system for evo‐devo research

Abstract

The northern pike, Esox lucius, is one of the largest temperate freshwater apex predators with a characteristic morphology: an elongated body with pelvic, dorsal, and anal fins located at the rear as a functional feature to sprint predation. However, the typical pike character is its head, which is characterized by a long, flattened snout, a well‐armed mouth with numerous teeth, and large eyes characteristic of shallow water visual predators. Although the northern pike is becoming increasingly popular as a model system for ecology and evolutionary research, a detailed staging table has not yet been reported. In this study, we report the first comprehensive staging table for the northern pike, spanning from the one‐cell stage to the freely‐swimming juvenile stage. In addition to classical embryological descriptions, we use a DAPI staining to distinguish individual cells and embryonic structures during the early development. This dataset, in combination with the genomic and transcriptomic resources already available, serves as a foundation for in‐depth mechanistic studies dealing with development using this species.

Migratory patterns and evolutionary plasticity of cranial neural crest cells in ray-finned fishes

“…1D, H). Gar embryos undergo neurulation in a manner that is similar that described for teleosts including pike (Schmitz et al, 1993;Lowery and Sive, 2004;Pospisilova et al, 2019) with the neuroectoderm forming a solid neural keel that only later develops a central lumen of the neural tube by means of cavitation ( Fig. 1I-L).…”

“…We speculate that this advanced development of the hyoid CNC may be associated with a unique early chondrogenesis of the hyosymplectic cartilage in pike ( Fig. 8O; Pospisilova et al, 2019) which forms an essential component of jaw attachment in ray-finned fishes (Richter and Underwood, 2018). Only in the whiting (Merlangius merlangus Linnaeus, 1758) has a similar process of advanced chondrogenesis been described (de Beer, 1937).…”

“…Pike belongs to teleost fishes that represent the vast majority of extant ray-finned fish species. Embryonic development of pike is very similar to other teleosts (Pospisilova et al, 2019), including model organisms like zebrafish or medaka (Kimmel et al, 1995;Iwamatsu, J o u r n a l P r e -p r o o f 2004). Despite the high similarity of the early development of pike and other teleosts, our data show that the hyoid CNC stream in pike embryos initiates migration much earlier than the mandibular neural crest stream (Fig.…”

“…This study was performed by analysis of detailed developmental series of the Senegal bichir (Polypterus senegalus Cuvier, 1829), the sterlet sturgeon (Acipenser ruthenus Linnaeus, 1758), the tropical gar (Atractosteus tropicus T. N. Gill, 1863) and the northern pike (Esox lucius Linnaeus, 1758). Husbandry and collection of embryos were performed as previously described (Minarik et al, 2017;Pospisilova et al, 2019), with embryos being staged as previously described (Dettlaff et al, 1993;Long and Ballard, 2001;Diedhiou and Bartsch, 2009;Pospisilova et al, 2019), fixed in 4% paraformaldehyde (PFA) in 0.1 M PBS at 4°C overnight, and dehydrated in 100% methanol for storage at -20°C. This study was conducted by following institutional guidelines for the use of embryonic material and international animal welfare guidelines (Directive 2010/63/EU) in the animal facility of the Department of Zoology, Charles University in Prague.…”

“…Fig. 1I-L and Schmitz et al, 1993;Lowery and J o u r n a l P r e -p r o o f Sive, 2004;Pospisilova et al, 2019;Rocha et al, 2019). We next asked when CNC cells begin their migration.…”