University Of Tasmania
142708 - Embryonic onset of sexually dimorphic heart rates in the viviparous fish.pdf (2.25 MB)
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Embryonic onset of sexually dimorphic heart rates in the viviparous fish, Gambusia holbrooki

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posted on 2023-05-20, 20:45 authored by Seyed Ehsan MousaviSeyed Ehsan Mousavi, Gary PurserGary Purser, Jawahar PATILJawahar PATIL
In fish, little is known about sex-specific differences in physiology and performance of the heart and whether these differences manifest during development. Here for the first time, the sex-specific heart rates during embryogenesis of Gambusia holbrooki, from the onset of the heart rates (HRs) to just prior to parturition, was investigated using light cardiogram. The genetic sex of the embryos was post-verified using a sex-specific genetic marker. Results reveal that heart rates and resting time significantly increase (p < 0.05) with progressive embryonic development. Furthermore, both ventricular and atrial frequencies of female embryos were significantly higher (p < 0.05) than those of their male sibs at the corresponding developmental stages and remained so at all later developmental stages (p < 0.05). In concurrence, the heart rate and ventricular size of the adult females were also significantly (p < 0.05) higher and larger respectively than those of males. Collectively, the results suggest that the cardiac sex-dimorphism manifests as early as late-organogenesis and persists through adulthood in this species. These findings suggest that the cardiac measurements can be employed to non-invasively sex the developing embryos, well in advance of when their phenotypic sex is discernible. In addition, G. holbrooki could serve as a better model to study comparative vertebrate cardiovascular development as well as to investigate anthropogenic and climatic impacts on heart physiology of this species, that may be sex influenced.


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Institute for Marine and Antarctic Studies



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Copyright 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://

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Socio-economic Objectives

Control of pests, diseases and exotic species in coastal and estuarine environments