Taste preferences and taste thresholds to classical taste substances in the carnivorous fish, kutum Rutilus frisii kutum (Teleostei: Cyprinidae)

The Physiology of Taste in Fish: Potential Implications for Feeding Stimulation and Gut Chemical Sensing

“…This generalization of a lower responsiveness to sugar in carnivores has also been made in mammals, with the most extreme example being cats, which possess a non-expressed pseudogene for T1R2 (Li et al, 2005). Nevertheless, several exceptions exist and, for instance, a palatability study on rainbow trout, Oncorhynchus mykiss, found that sugars evoked a positive response in this species (Jones, 1990), while in katum the response varied from deterrent, stimulant or indifferent depending on sucrose concentration (Goli et al, 2015).…”

“…Sucrose, for instance, is an interesting case. It has been found indifferent or even deterrent in several species, including channel catfish, Ictalurus punctatus (Kanwal and Caprio, 1983), brown trout (Kasumyan and Sidorov, 2005) and kutum, Rutilus frisii kutum (Goli et al, 2015). This is not too surprising, considering its low predominance in aquatic food webs and lack of dietary requirements (low nutritional value) for carbohydrates in fish, even though this varies considerably among species, with warmwater species utilizing more effectively higher levels of carbohydrates than coldwater and marine fish (Wilson, 1994).…”

“…Although some individual variability has been detected, it is much less marked for substances showing higher attractiveness (Kasumyan, 2000). On the other hand, it appears that there are no phylogenetic relationships since, in most cases, correlations in taste preferences between species sharing a close systematic position have not been found (Kasumyan and Døving, 2003;Shamushaki et al, 2008;Goli et al, 2015). In addition, no associations were found also with respect to ecology and feeding habits (Kasumyan and Nikolaeva, 2002), not even between sympatric species, while different stocks or populations of red sea bream, Chrysophrys major, or brown trout from widely isolated and distinct geographic regions were shown to have similar taste preferences (Goh and Tamura, 1980a;Kasumyan and Sidorov, 2005).…”

Evolutionary conserved brainstem circuits encode category, concentration and mixtures of taste

“…In order to study the gustatory computations in the brainstem, we mainly focused our measurements on the zebrafish facial lobe ( Figs 1 and 2a–c ), which is homologous to the mammalian nucleus of the solitary tract 1 35 . We presented a broad set of tastants 11 36 with different behavioral significances by using a computer controlled taste delivery system, while imaging the neural activity by a two photon microscope. The neuronal calcium signals in facial lobe neurons in response to the taste stimulation were robust and reproducible ( Supplementary Figure 1,2 ).…”

“…Stimulus intensity (concentration) can change the perceived taste quality. For example, humans, rodents and teleost fish perceive low concentrations of sour taste as a feeding cue 36 44 45 46 , and high concentrations of sour taste as unpleasant 44 45 . Moreover, different taste categories have been shown to have different detection thresholds 47 ; for example, bitter compounds can be detected at lower concentrations 48 49 .…”