The epaulette shark, Hemiscyllium ocellatum, is a tropical reef shark that can live in an environment with cyclic periods of low oxygen concentration, suggesting that it has a well-developed capacity for anaerobic metabolism. Most investigations of hypoxia-tolerant teleosts and reptiles have focused on species that inhabit cold environments. This study was carried out on a tropical reef shark i...

Evolutionary origin and physiological significance of the tetrodotoxin (TTX) resistance of the vertebrate cardiac Na(+) current (I(Na)) is still unresolved. To this end, TTX sensitivity of the cardiac I(Na) was examined in cardiac myocytes of a cyclostome (lamprey), three teleost fishes (crucian carp, burbot and rainbow trout), a clawed frog, a snake (viper) and a bird (quail). In lamprey, tele...

We show that crucian carp (Carassius carassius) living in normoxic (aerated) water have gills that lack protruding lamellae, the primary site of O(2) uptake in fish. Such an unusual trait leads to a very small respiratory surface area. Histological examination showed that the lamellae (secondary lamellae) of these fish were embedded in a cell mass (denoted embedded lamellae). When the fish were...

Virus-induced interferons (IFNs) have been identified in various fish species and display antiviral activities similar to mammalian type I IFNs. However, apart from the mammalian IFN system, the IFN signaling pathway remains largely unknown. Using transient transfection and recombinant protein, we are reporting in this study that a crucian carp (Carassius auratus L.) IFN exhibits strong antivir...