Dr. Jimenez Speaks on her Research on the Biology of Aging in Dogs


Professor Ana Jimenez, pictured above, lectured on her research in the aging of dogs, and the impact of size on this process. There is little previous research on the answer to these questions. 

Finn Schuemann, Maroon-News Staff

On​ ​Monday, November 7,​ ​Assistant Professor​ ​of Biology Ana​ ​Jimenez​​ ​gave​ ​the​ ​presentation, “The​ ​Biology​ ​of​ ​Aging:​ ​The​ ​Case​ ​of​ ​the​ ​Dog.”​ ​For​ ​the​ ​past​ ​two​ ​years,​ ​Jimenez​ ​has been​ ​collecting​ ​evidence​ ​concerning​ ​how​ ​dogs​ ​age.​ ​She​ ​has​ conducted ​her​ ​research​ ​with​ senior ​Josh Winward ​and​ ​alumna Ursula​ ​Beattie ’17. ​Additionally,​ Assistant Professor of Mathematics ​Will​ ​Cipolli​ ​assisted​ ​in​ ​Jimenez’s research.

In​ ​the​ ​introduction​ ​of​ ​her​ ​presentation,​ ​Jimenez​ ​mentioned​ ​the ​link between​ ​metabolism​ ​and​ ​aging​ ​in​ ​animals.​ ​Jimenez​ ​noted​ ​how​ ​metabolic​ ​rate​ ​increases with​ ​body​ ​mass.​ ​Mentioning​ ​a​ ​mouse​ ​as​ ​an​ ​example,​ ​Jimenez​ ​described ​that,​ ​because​ ​of body​ ​mass,​ ​a​ ​mouse​ ​has​ ​a​ ​smaller​ ​metabolic​ ​rate​ ​than,​ ​say,​ ​an​ ​elephant.​ ​Additionally,​ ​there​ ​is​ ​a trend​ ​Jimenez​ ​spoke​ ​of​ ​between​ ​body​ ​mass​ ​and​ ​mammals.​ ​The​ ​bigger​ ​a​ ​mammal​ is, the​ ​longer​ ​their​ ​life​ ​is.​ ​This​ ​is,​ ​however,​ ​not​ ​present​ ​in​ ​dogs.​ ​Instead,​ ​there​ ​is​ ​a​ ​trend​ ​that​ ​smaller dogs​ ​have​ ​a​ ​longer​ ​lifespan​ ​than​ ​that​ ​of​ ​a​ ​larger​ ​dog.

Jimenez​ ​continued​ ​her​ ​presentation​ ​by​ ​describing​ ​the​ ​anatomy​ ​of​ ​small​ ​and​ ​big dogs.​ ​Small​ ​dogs​ ​have​ ​small​ ​litters,​ ​which​ ​cause​ ​them​ ​to​ ​have​ ​a​ ​minor​ ​reproductive​ ​system,​ ​slow growth ​and​ ​a​ ​late​ ​maturity.​ ​On​ ​the​ ​other​ ​hand,​ ​larger​ ​dogs​ ​have​ ​large​ ​litters,​ ​causing​ ​them​ ​to have​ ​a​ ​more​ ​active​ ​reproductive​ ​system,​ ​faster​ ​growth,​ ​and​ ​early​ ​maturity.​ ​However,​ Jimenez​ ​noted​ ​the​ ​surprising​ ​trend​ ​that​ ​small​ ​dogs​ ​reach​ 50 ​percent​ ​of​ ​their​ ​adult​ ​weight quicker​ ​than​ ​larger​ ​dogs,​ ​but​ ​bigger​​dogs​ ​grow​ ​for longer and at​ ​a​ ​larger​ ​trajectory​. 

The​ ​introduction​ ​of​ ​metabolic​ ​rate​ ​was​ ​then​ ​brought​ ​up​ ​again​ ​to​ ​connect​ ​to​ ​the​ ​growth​ ​of dogs.​ ​Before​ ​doing​ ​so,​ ​Jimenez​ ​explained​ ​the​ ​two​ ​forms​ ​of​ ​metabolic​ ​rate:​ ​basal metabolic​ ​rate ​and​ ​mass​ ​specific​ ​metabolic​ ​rate.​ ​Basal​ ​metabolic​ ​rate​ ​is​ ​measured​ ​through​ ​an oxygen​ ​mask,​ ​whereas​ ​mass​ ​specific​ ​rate​ ​is​ ​measured​ ​through​ ​one​ ​gram​ ​per​ ​tissue.​ ​This​ ​is important​ ​because​ ​at​ ​the​ ​tissue​ ​and​ ​cell​ ​level,​ ​there​ ​are​ ​differences​ ​that​ ​can​ ​be​ ​compared​ ​between big​ ​and​ ​small​ ​dogs.                       

An​ ​interesting​ ​topic​ ​was​ ​reactive​ ​oxygen​ ​species,​ ​which​ ​can​ ​be​ ​seen​ ​in​ ​up​ ​to​ 15 percent​ ​of​ ​oxygen,​ ​and​ ​can​ ​contain​ ​damaging​ ​chemicals​ ​that​ ​can​ ​cause​ ​aging,​ ​and​ ​further detrimental​ ​effects​ ​on​ ​lipids,​ ​protein,​ ​DNA ​and​ ​joints.​ ​Related​ ​to​ ​oxidative​ ​stress,​ ​reactive oxygen​ ​species​ ​can​ ​affect​ ​oxidative​ ​stress​ ​through​ ​marking​ ​an​ ​imbalance​ ​in​ ​reactive​ ​oxygen species​ ​and​ ​in​ ​a​ ​biological​ ​system’s​ ​capabilities​ ​in​ ​attempting​ ​to​ ​suppress​ ​the​ ​toxins​ ​damaging cells.​ ​In​ ​dogs,​ ​large​ ​breeds​ ​tend​ ​to​ ​have​ ​smaller​ ​antioxidant​ ​capacity,​ ​meaning​ ​that​ ​they​ ​have​ ​less resources​ ​in​ ​trying​ ​to​ ​prevent​ ​oxidative​ ​stress​ ​from​ ​causing​ ​damage.​ ​Smaller​ ​breeds,​ ​however, have​ ​a​ ​larger​ ​antioxidant​ ​capacity.​ ​This​ ​relates​ ​to​ ​aging​ ​because​ ​smaller​ ​dogs​ ​are​ ​less​ ​likely​ ​to receive​ ​damage​ ​to​ ​their​ ​biological​ ​system​ ​as​ ​compared​ ​to​ ​larger​ ​breeds,​ ​which​ ​are​ ​more​ ​likely​ ​to be​ ​negatively​ ​affected​ ​by​ ​reactive​ ​oxygen​ ​species​ ​and​ ​intake​ ​diseases​, ​such​ ​as​ ​cancer.                     

As​ ​defined​ ​by​ ​Jimenez,​ ​aging​ ​is​ ​the​ ​malfunction​ ​of​ ​most​ ​systems.​ ​In​ ​order​ ​to find​ ​a​ ​trend​ ​within​ ​dogs​ ​in​ ​an​ ​experimental​ ​setting,​ ​four​ ​groups​ ​were​ ​created​ ​for​ ​her​ ​experiment with the variables of size and age, including both young​ and senior small ​breed​ ​dogs and young and senior large breed​ ​​dogs.​ ​Oxygen​ ​consumption​ ​rate​ ​and​ ​glycolysis​ ​were​ ​measured.​ ​It​ ​was​ ​determined that​ ​small​ ​dogs​ ​lived​ ​longer​ ​because​ ​they​ ​had​ ​a​ ​smaller​ ​production​ ​of​ ​reactive​ ​oxidative​ ​species than​ ​larger​ ​breeds.​ ​Because​ ​larger​ ​breeds​ ​of​ ​dogs​ ​suffer​ ​more​ ​from​ ​oxidative​ ​stress,​ ​this​ ​causes​ ​significantly​ ​larger​ ​damage​ ​in​ ​DNA​ ​and​ ​basal​ ​lipid​ ​peroxidation.​ ​These​ ​detrimental​ ​effects​ ​in large​ ​dogs​ ​causes​ ​them​ ​to​ ​be​ ​highly​ ​susceptible​ ​to​ ​diseases​ ​and​ ​injury,​ ​which​ ​explains​ ​their shorter​ ​lifespan​ ​to​ ​that​ ​of​ ​small​ ​dogs.                       

Not​ ​much​ ​research​ ​has​ ​been done​ ​to​ ​measure​ ​aging​ ​in​ ​dogs​ ​besides​ ​her​ ​research.​ ​This​ ​unique​ ​topic​ ​highlights​ ​the​ ​perplexity of​ ​aging,​ ​however,​ ​further​ ​attention​ ​to​ ​this​ ​matter​ ​can​ ​result​ ​in​ ​unforeseen​ ​achievements​ ​in science.​ ​Jimenez’s​ ​research​ ​has​ ​already​ ​been​ ​reported​ ​on​ ​by​ ​academic​ ​journals​ ​such​ ​as Science​ ​Magazine.                        

Students​ attending the lecture​ ​reacted​ ​positively​ ​to​ ​Jimenez’s​ ​research. 

First-year Jake​ ​Bilodeau, ​remarked​ ​how​ ​“different,​ ​yet​ ​important”​ ​her presentation​ ​was and said that he was interested in future implications of her work. 

“[In​ ​the​ ​future​ ​it​ ​may​ ​be​ ​possible​ ​to​ ​see]​ ​advancements​ ​in​ ​preventing cells​ ​from​ ​aging,” Bilodeau said. ​ 

First​-year​ ​Andrew​ ​Blum ​noted ​how​ ​Jimenez’s​ work ​has​ ​influenced​ the field. 

​“More​ ​research​ ​should​ ​be​ ​done​ ​on​ ​cell​ ​aging. [Research on cells and aging] can have important medicinal uses,” Blum said. ​ ​

Jimenez felt that while the two years she spent on the research were valuable, she is still interested in learning more on the topic. 

Contact Finn Schuemann at [email protected].