Heart Development, Coronary Vascularization and Ventricular Maturation in a Giant Danio (Devario malabaricus)

Abstract

Giant danios (genus Devario), like zebrafish, are teleosts belonging to the danioninae subfamily of cyprinids. Adult giant danios are used in a variety of investigations aimed at understanding cellular and physiological processes, including heart regeneration. Despite their importance, little is known about development and growth in giant danios, or their cardiac and coronary vessels development. To address this scarcity of knowledge, we performed a systematic study of a giant danio (Devario malabaricus), focusing on its cardiac development, from the segmentation period to ten months post-fertilization. Using light and scanning electron microscopy, we documented that its cardiovascular development and maturation proceed along well defined dynamic and conserved morphogenic patterns. The overall size and cardiovascular expansion of this species was significantly impacted by environmental parameters such as rearing densities. The coronary vasculature began to emerge in the late larval stage. More importantly, we documented two possible loci of initiation of the coronary vasculature in this species, and compared the emergence of the coronaries to that of zebrafish and gourami. This is the first comprehensive study of the cardiac growth in a Devario species, and our findings serve as an important reference for further investigations of cardiac biology using this species.

Structure, development, and functional morphology of the cement gland of the giant danio, Devario malabaricus

“…We have recently reported on the breeding, rearing, cardiac development, and coronary vasculature of the D . malabaricus . In the course of these studies, we observed unexpected adhesive behaviors and a cement gland.…”

“…Experimental procedures were approved by the Committee for the Care and Use of Laboratory Animals at DePauw University. The breeding of the D. malabaricus has previously been published . Briefly, adult D. malabaricus 50‐60 mm in standard length from Segrest Farms (Gibsonton, Florida) were first acclimated to 28.5°C for 1‐3 weeks prior to breeding.…”

“…We have recently reported on the breeding, rearing, cardiac development, and coronary vasculature of the D. malabaricus. 33 In the course of these studies, we observed unexpected adhesive behaviors and a cement gland. In this article, we extend our study of this species by first providing preliminary documentation of the overall development of the D. malabaricus, focusing on the emergence of the cement gland in the embryonic stage, its maturation, and its eventual resorption in the third week of larval stage.…”

“…cf aequapinnatus , and more recently cardiac development in the species identified as the D . malabaricus that was bred in laboratory setting …”

“…We have previously studied heart regeneration and cardiac remodeling in a D. cf aequapinnatus, 32 and more recently cardiac development in the species identified as the D. malabaricus that was bred in laboratory setting. 33 The early development of the D. malabaricus (previously D. malabaricus) was described more than 80 years ago 34 from eggs isolated from the Gorewawela Oya hill stream in Ceylon (now Sri Lanka). For many years, this study remained the first and only reported study of the embryonic and larval development of a Devario, but recently description of the development of the D. aequapinnatus was published.…”