Scientists have shed new light on how one-humped Arabian camels (Camelus dromedarius) can survive for weeks in the desert without drinking water.
A team led by researchers from the University of Bristol in the United Kingdom investigated the response of the kidneys of these animals when they experienced chronic dehydration and rapid rehydration.
For a study published in the journal Communications Biology, the team analyzed how thousands of genes changed in the camel kidneys as a result of dehydration and rehydration.
One of the key adaptations that enables these camels to survive for so long without water is the ability of their very well-adapted kidneys to produce highly concentrated urine—these ensure that very little water is wasted.
In the latest study, the team found that the level of cholesterol—a waxy type of fat, or lipid—in the camel kidney plays an important role in the conservation of water.
“A decrease in the amount of cholesterol in the membrane of kidney cells would facilitate the movement of solutes and water across different sections of the kidney—a process that is required to efficiently reabsorb water and produce a highly concentrated urine, thus avoiding water loss,” lead authors of the study, Fernando AlviraI Iraizoz and Benjamin Gillard from Bristol’s Medical School, said in a statement.
“This is, to the best of our knowledge, the first time that the level of cholesterol has been directly associated with water conservation in the kidney. Thus, we describe a novel role for this lipid that may be of interest when studying other species.”
The researchers say there is renewed interest in the mechanisms that enable camels to survive in extremely dry conditions given the current context of climate change and widespread desertification in some areas of the world.
The Arabian camel is the most important livestock animal in the arid and semi-arid regions of North and East Africa, the Arabian Peninsula and Iran. Experts think the animals were domesticated between around 6,000 and 3,000 years ago.
In that time, they have been used as beasts of burden, for riding and sport, and as sources of milk and meat. Even today, they help to provide basic needs to millions of people in these regions.
In addition to the very well adapted kidney of the Arabian camel, the animals also display several other characteristics and behaviors that help them to survive in arid conditions.
For example, these animals solely eat the leaves of plants, only reproduce in the cooler winter season, and are capable of drinking very large amounts of water in one go when the resource becomes available.
The intricate shape of their nasal passage allows the camels to recover water when they breathe out. In addition, their body temperature can fluctuate significantly between day and night in dehydrated camels, saving more than a gallon of water per day that would otherwise be lost in sweat.