Distribution of different taste buds and expression of α-gustducin in the barbells of yellow catfish (Pelteobagrus fulvidraco)

In order to explore the distribution of different taste buds in the barbells of yellow catfish (Pelteobagrus fulvidraco) collected from the Yangtze River, the quantity, morphology and distribution of different taste buds in the barbells was studied by bright-field optical microscope and scanning electron microscopy. The taste buds in the barbell were predominantly localized at the middle two thirds regions of the barbells, and could be categorized into three major types based on their morphological and histological features. Type I and II TB were distributed on the elevated layer of the surrounding epithelium, while Type III TB ended apically at the level with the epithelium. Significant quantitative differences (p < 0.05) in the TB number within unit length barbell were observed between NB and MB (p = 0.00001), NB and MIB (p = 0.00758), and NB and MOB (p = 0.00209); no significant differences (p > 0.05) were found between MB and MIB (p = 0.05293), MB and MOB (p = 0.05994) and MIB and MOB (p = 0.08320). The number, distribution and morphological variability of TBs could be a consequence of adaptation to the environment. α-Gustducin immunofluoresence signals were detected in cells of all types of TBs. The strong expression of α-gustducin on the barbells of catfish suggests that the taste-induced signal transduction in taste cells was common to all vertebrates.