Behaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)

Sound production is widespread among fishes and accompanies many social interactions. The literature reports twenty-nine cichlid species known to produce sounds during aggressive and courtship displays, but the precise range in behavioural contexts is unclear. This study aims to describe the various Oreochromis niloticus behaviours that are associated with sound production in order to delimit the role of sound during different activities, including agonistic behaviours, pit activities, and reproduction and parental care by males and females of the species.Sounds mostly occur during the day. The sounds recorded during this study accompany previously known behaviours, and no particular behaviour is systematically associated with sound production. Males and females make sounds during territorial defence but not during courtship and mating. Sounds support visual behaviours but are not used alone. During agonistic interactions, a calling Oreochromis niloticus does not bite after producing sounds, and more sounds are produced in defence of territory than for dominating individuals. Females produce sounds to defend eggs but not larvae.Sounds are produced to reinforce visual behaviours. Moreover, comparisons with O. mossambicus indicate two sister species can differ in their use of sound, their acoustic characteristics, and the function of sound production. These findings support the role of sounds in differentiating species and promoting speciation. They also make clear that the association of sounds with specific life-cycle roles cannot be generalized to the entire taxa

Adenosine receptors in gestational diabetes mellitus and maternal obesity in pregnancy

Regulation of blood flow depends on the systemic and local release of vasoactive molecules including the endogenous nucleoside adenosine. Vasodilation caused by adenosine results from the activation of adenosine receptors (ARs) at the vascular endothelium and smooth muscle. Adenosine receptors are four subtypes, i.e. AAR, AAR, AAR and AAR, of which AAR and AAR activation in the endothelium lead to increased generation of nitric oxide and relaxation of the underlying smooth muscle cell layer. Adenosine also causes vasoconstriction via a mechanism involving AAR activation by increasing the release of vasoconstrictors. Adenosine increases the sensitivity of vascular tissues from diseases coursing with insulin resistance, including gestational diabetes mellitus (GDM) and obesity. ARs also play a role in obesity since they modulate D-glucose homeostasis, inflammation and adipogenesis. Agonists and/or antagonists of high selectivity for ARs may result in reversing the obesity state since normalises lipolysis and insulin sensitivity. A considerable fraction of pregnant women with GDM show with pregestational obesity and/or supraphysiological gestational weight gain. These conditions associated with reduced vascular responsiveness to adenosine and insulin. However, it is unclear whether GDM plus obesity in pregnancy could worsen these alterations in the foetoplacental vascular function. This chapter summarises available findings that address the potential involvement of ARs to modulate human foetoplacental vasculature in GDM and obesity in pregnancy