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Journal of Comparative Physiology A

, Volume 191, Issue 2, pp 125–134 | Cite as

Photoreceptors and photopigments in a subterranean rodent, the pocket gopher (Thomomys bottae)

  • Gary A. Williams
  • Jack B. Calderone
  • Gerald H. Jacobs
Original Paper

Abstract

Pocket gophers (Thomomys bottae) are rodents that spend much of their lives in near-lightless subterranean burrows. The visual adaptations associated with this extreme environment were investigated by making anatomical observations of retinal organization and by recording retinal responses to photic stimulation. The size of the eye is within the normal range for rodents, the lens transmits light well down into the ultraviolet, and the retina conforms to the normal mammalian plan. Electroretinogram recording revealed the presence of three types of photopigments, a rod pigment with a spectral peak of about 495 nm and two types of cone pigment with respective peak values of about 367 nm (UV) and 505 nm (medium-wavelength sensitive). Both in terms of responsivity to lights varying in temporal frequency and in response recovery following intense light adaptation, the cone responses of the pocket gopher are similar to those of other rodents. Labeling experiments indicate an abundance of cones that reach densities in excess of 30,000 mm−2. Cones containing UV opsin are found throughout the retina, but those containing medium-wavelength sensitive opsin are mostly restricted to the dorsal retina where coexpression of the two photopigments is apparently the rule. Rod densities are lower than those typical for nocturnal mammals.

Keywords

Photoreceptors Thomomys bottae Photopigment coexpression Ultraviolet Electroretinogram 

Abbreviations

ERG

Electroretinogram

L

Long-wavelength sensitive

M

Medium-wavelength sensitive

S

Short-wavelength sensitive

UV

Ultraviolet-wavelength sensitive

ONL

Outer nuclear layer

Notes

Acknowledgements

We thank John Fenwick for help with the anatomy and Kris Krogh for making the lens measurements. All animal care and experimental procedures were in accordance with institutional care and use guidelines and with the Principles of animal care, publication No. 86–23, revised 1985 of the National Institutes of Health. This research was facilitated by a grant from the National Eye Institute (EY002052).

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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Gary A. Williams
    • 1
  • Jack B. Calderone
    • 1
  • Gerald H. Jacobs
    • 1
  1. 1.Neuroscience Research Institute and Department of PsychologyUniversity of CaliforniaSanta BarbaraUSA

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