Comparison of Neuroglobin distribution and expression in the retina of adult yak and cattle v1

Background: The yaks belong to the genus Bos and are therefore related to cattle (Bos primigenius species). The yak may have diverged from cattle at any point between one and five million years ago, and it is suggested that the yak is more closely related to cattle than other members of its designated genus. Objective:Thestudy evaluated the distribution of Neuroglobin (NGB) expression in the retina of adult yak and cattle. Method: The total of ten (10) healthy yaks and cattle were used in the study (5 each). The immuno-histochemical staining procedures method was performed to assay the distribution of NGB in the retina of adult yak and cattle. Result: The results demonstrated that NGB in the retina of adult yak and cattle was extremely positive in the ganglion cell layer, outer plexiform layer, photoreceptor inner segments and pigment epithelial layer (+++) while strongly positive in the nerve fiber layer, ganglion cell layer, inner plexiform layer and photoreceptor outer segments (++) and both inner nuclear layer (+) and outer nuclear layer (-) were weakly and negatively expressed respectively. Expression in the inner limiting membrane, outer limiting membrane and optic nerves of the cattle waspositive (+) andconsistent with the adult yak. No NGB expression was found in the outer nuclear layer of both yak and cattle.The statistical t-test reported the significant level of NGB found in the retinal ganglion cell layer, kernel layer, optic nerve and photoreceptor inner segments were higher in yak than cattle (P < 0.05). Conclusion: These results suggest that NGB might play an important role in oxygen homeostasis of the retina and normal functions in the optic nerve of yak and cattle under high altitude hypoxia. Despite the results, its specific functional mechanism needs further investigation.