Laboratory of
Comparative Physiology
AND Endocrinology

Unveiling the Secrets of Life and Evolution.
Our interest is the physiological mechanisms of vertebrate environmental adaptation and its origin and evolution. We especially focus on hagfishes, one of two extant jawless fish lineages, and conduct research projects at levels from genes to organisms.

※Some of the pictures used in this HP were obtained from Illust AC and Silhouette AC.

【 What's New? 】

• 2025.10.15　Y. Yamaguchi received an Encouragement Award from Japan Society for Comparative Endocrinology for her study on pituitary hormones!
  
  

• 2025.07.10　Gave a talk at 19th International Congress of Comparative Endocrinology, Sendai, Miyagi, Japan.
  Title of the talk: The origin of vertebrate osmoregulatory ability: Insights from the study of the inshore hagfish
  
  

• 2025.06.04　A paper was published on the growth and feeding of the hagfish（Open access）. Selected as a journal cover!
  Yamaguchi Y. (2025) Growth, feeding, and age of the inshore hagfish, Eptatretus burgeri. Zoolog Sci. 42:299-308. doi: 10.2108/zs240097

Introduce by media (Japanese)↓
https://www.itmedia.co.jp/news/articles/2506/25/news049.html
https://www.youtube.com/watch?v=HEenkOIjsAk

• 2025.06.04　A paper was published on the molecular/functional evolution of neurohypophyseal hormones.
  Yamaguchi Y. (2025) Amino acid residues critical to cAMP signaling by V2a-type vasopressin/vasotocin receptor: an evolutionary perspective. Gen Comp Endocrinol. 370:114758. doi: 10.1016/j.ygcen.2025.114758
  
  

• 2024.09.18　State-of-the-Art Presentation at 10th international synposium on fish endocrinology at Baltimore, MD, USA.
  Title of the talk: Osmoregulatory mechanisms in the inshore hagfish, Eptatretus burgeri: Is it “ancestral”?
  
  

• 2024.08.01　A paper was published on the hagfish osmoregulatory ability（Open access）.
  Yamaguchi Y, Ikeba K, Yoshida MA, Takagi W. (2024) Molecular basis of the unique osmoregulatory strategy in the inshore hagfish, Eptatretus burgeri. Am J Physiol Regul Integr Comp Physiol. 327:R208-R233. doi: 10.1152/ajpregu.00166.2023.

・A set of osmoregulatory genes were found in osmoconforming hagfish
・However, the conventional pathway for NaCl  transport is silenced in the hagfish gill and kidney
・It is suggested that the osmoregulatory was secondarily lost in hagfishes
・The osmoconforming strategy of hagfishes are not "ancestral". 

• 2023.05.01　A paper was published on the hagfish neurohypophysial hormone system（Open access）.
  Yamaguchi Y, Takagi W, Kaiya H, Konno N, Yoshida MA, Kuraku S, Hyodo S. (2023) Phylogenetic and functional properties of hagfish neurohypophysial hormone receptors distinct from their jawed vertebrate counterparts. Gen Comp Endocrinol. 336:114257. doi: 10.1016/j.ygcen.2023.114257.

・Receptors of  vasotocin, a hormone secreted from the posterior pituitary (neurohypophysis), was identified in the inshore hagfish
・A new scenario was proposed on the evolution of vertebrate neurohypophysial hormone system, which is more complicated than ever thought.