FISIOLOGÍA ANIMAL La fisiología de los animales. Un gasto energético diario excepcionalmente bajo en el panda gigante devorador de bambú

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Yonggang Nie¹, John R Speakman², Qi Wu¹

¹Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

Science (New York, N.Y.)

|July 11, 2015

Resumen

Los pandas gigantes tienen un gasto de energía excepcionalmente bajo debido a adaptaciones únicas. Estos incluyen órganos más pequeños, actividad reducida y niveles más bajos de hormonas tiroideas, lo que permite la supervivencia en una dieta de bambú.

Área de la Ciencia:

Zoología Zoología Zoología.
La Fisiología Comparada.
Genética La genética.

Sus antecedentes:

Los pandas gigantes (Ailuropoda melanoleuca) poseen una dieta especializada de bambú, a pesar de que su sistema digestivo está mal adaptado para ello.
Esta especialización dietética presenta un desafío fisiológico, que requiere adaptaciones únicas para la conservación de la energía.

Objetivo del estudio:

Investigar los mecanismos fisiológicos y genéticos que subyacen al bajo gasto energético del panda gigante.
Para determinar cómo estas adaptaciones permiten la supervivencia en una dieta de bambú pobre en nutrientes.

Principales métodos:

Gasto energético diario medido (DEE) en pandas gigantes en cautiverio y salvaje.
Comparó el DEE con los valores pronosticados para mamíferos de tamaño similar.
Se evaluaron el tamaño de los órganos, los niveles de actividad física y las concentraciones de hormonas tiroideas circulantes (T4 y T3).
Analizó el gen DUOX2 en busca de mutaciones que podrían afectar la síntesis de hormonas tiroideas.

Principales resultados:

Los pandas gigantes exhibieron un DEE significativamente más bajo (promedio de 5.2 MJ/día, 37.7% de lo previsto) en comparación con otros mamíferos.
Los pandas salvajes también mostraron una reducción de DEE (6,2 MJ/día, 45% de la expectativa).
Se observaron tamaños reducidos de órganos vitales, baja actividad física y niveles circulantes significativamente más bajos de tiroxina (T4) y triiodotironina (T3).
Se identificó una mutación única en el gen DUOX2, que podría explicar los bajos niveles de hormonas tiroideas.

Conclusiones:

Los pandas gigantes exhiben un conjunto de adaptaciones morfológicas, conductuales, fisiológicas y genéticas que reducen drásticamente el gasto energético.
Estas adaptaciones, incluida una mutación única de DUOX2 que afecta a las hormonas tiroideas, son cruciales para su supervivencia en una dieta basada en bambú.

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