Zinc as a Signal to Stimulate Red Blood Cell Formation in Fish

Abstract

The common carp can tolerate extremely low oxygen levels. These fish store zinc in a specific zinc-binding protein presented in digestive tract tissues, and under low oxygen, the stored zinc is released and used as a signal to stimulate erythropoiesis (red blood cell formation). To determine whether the environmental supply of zinc to other fish species can serve as a signal to induce erythropoiesis as in the common carp, head kidney cells of four different fish species were cultured with supplemental ZnCl2. Zinc stimulated approximately a three-fold increase in immature red blood cells (RBCs) in one day. The stimulation of erythropoiesis by zinc was dose-dependent. ZnSO4 solution was injected into an experimental blood loss tilapia model. Blood analysis and microscopic observation of the blood cells indicated that, in vivo, the presence of additional zinc induced erythropoiesis in the bled tilapia. In the fish species studied, zinc could be used as a signal to stimulate erythropoiesis both in vitro and in vivo. The present report suggests a possible approach for the induction of red blood cell formation in animals through the supply of a certain level of zinc through either diet or injection.

Effects of Dietary Zinc Amino Acid Complex and Zinc Sulfate on Growth Performance, Digestive Enzyme Activity and Immune Response in Asian Seabass (Lates calcarifer)

“…In the current study, hematocrit was significantly higher in the fish from both ZnAA and ZnSO 4 treatments. It was reported that zinc could act as a signal to stimulate red blood formation in the common carp [45,46]. However, no significant effect on red blood cells of the Asian seabass was observed in this study.…”

Zinc Supplementation Stimulates Red Blood Cell Formation in Rats

“…Previous studies indicated that zinc could induce erythropoiesis in fish [ 51 , 52 , 53 , 54 ], but the RBCs of fish maintain the nucleus, whereas mammalian RBCs differ fundamentally from those of fish and lack a nucleus. Thus, it was unclear whether the mechanism of zinc-induced erythropoiesis stimulation in fish also occurs in rats.…”

“…Recently, it was reported that “zinc signal” is essential for physiology [ 58 ]. We reported that zinc is not only a signal for common carp to stimulate erythropoiesis, but also for many other fish [ 54 ]. In the present report, we found that this kind of mechanism also exists in rats.…”

“…The stimulation of RBC formation by zinc signal appears to be common among different animals. However, the zinc concentration for maximum activation of RBCs in vitro seems differs in different animal species, e.g., in rats, it is 0.3 mM; for common carp, also 0.3 mM; but 0.6, 0.2, 0.3, and 1.2 mM for crucian carp, grass carp, silver carp, and tilapia, respectively [ 54 ]. Although the newly proliferated RBC cells of rats ( Figure 4 ) and fish [ 54 ] all showed strong immunofluorescence when stained with the CD-71 antibody; the new reticulocytes of the rat blood have a ‘star’ shape ( Figure 2 ) and have no nucleus, while the newly proliferated RBCs in the fish blood showed a round shape and contain a nucleus [ 54 ].…”

Effects of acute and chronic zinc exposure on steroid hormone receptor expression in the lined seahorse, Hippocampus erectus

“…Each individual received a one‐time injection of 20 μL of saline solution into the abdomen at the beginning of the experiment. Individuals in the control groups were injected with 20 μL saline solution, and individuals of the low concentration (LC) and high concentration (HC) groups received 66 mg/L, and 132 mg/L Zn (as Zn sulfate), respectively (Chen, Shiu, Ho, & Jeng, ). All other husbandry conditions remained the same as before the experiment.…”